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  • 101
    Electronic Resource
    Electronic Resource
    Calcium-dependent, slowly inactivating potassium currents in cultured neurons of rat neocortex (1995)
    Springer
    Experimental brain research 107 (1995), S. 197-204 
    Details
    ISSN: 1432-1106
    Keywords: Slowly inactivating potassium currents ; Patch-clamp ; Cortical neurons ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Slowly inactivating outward currents were examined in neurons from rat anterior cortex dissociated at postnatal day 1 and recorded after 7–48 days in vitro by the use of whole-cell patch-clamp technique, in the presence of 0.5–0.8 μM tetrodotoxin (TTX), 50 μM carbachol and 1–5 mM CsCl2. Experiments were often carried out in the additional presence of 1–5 mM CsCl2, which blocks the anomalous, inwardly rectifying I Q, the fast Ca 2 + -dependent K+ current (I C), and 50 μM carbachol, which depresses the I M current. These currents were evoked by depolarizing steps to -40+-5 mV from a conditioning hyperpolarization to -110+-10 mV. Their sensitivity to elevation from 2.5 to 12.5 mM in extracellular K+ concentration, together with their sensitivity to 5–15 mM tetraethylammonium, suggests that they are mainly carried by K+ ions. Their activation and inactivation curves show that the threshold for activation is -65 mV, that their inactivation is achieved at -75 mV and that potentials more negative than -120 mV are needed to abolish it. The time-dependence of de-inactivation gives a maximal current amplitude for conditioning hyperpolarizations of 2 s and is best described by a monoexponential function with a time constant of 0.7 s. Slow, transient K+ currents were depressed by low doses of 4-aminopyridine (30–100 μM), which indicates the occurrence of an I D-type component in the recorded K+ currents. No slowly declining K+ current was expressed when a recording solution containing 10 mM 1,2-bis(2-aminophenoxy)ethane-N, N,N′-N′-tetraacetic acid (BAPTA), instead of 1–5 mM BAPTA, was used. When recorded without Ca2+ chelator in the pipette, slowly declining K+ currents were blocked by bath-applied 40–50 μM BAPTA-aminoethoxy, revealing a large-amplitude, rapidly inactivating outward current. This residual component is insensitive to 50 μM 4-aminopyridine and may include a current more related to the I A-type. Our data provide evidence that, in cultured cortical neurons from rat, the expression of an I D-like K+ current is highly dependent on internal Ca2+ concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230041
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  • 102
    Electronic Resource
    Electronic Resource
    Floating-Harbor syndrome: description of a further patient, review of the literature, and suggestion of autosomal dominant inheritance (1995)
    Springer
    European journal of pediatrics 154 (1995), S. 658-661 
    Details
    ISSN: 1432-1076
    Keywords: Floating-Harbor syndrome ; Growth retardation ; Dysmorphology ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Abstract The Floating-Harbor syndrome is a growth retardation syndrome with delayed bone age, speech development, and typical facial features. The face is triangular with deep-set eyes, long eyelashes, bulbous nose, wide columella, short philtrum, and thin lips. We present an additional patient and review 16 cases from the literature. The possible phenotype in the patient's mother suggests a dominant mode of inheritance for the syndrome. Conclusion The Floating Harbor syndrome is a growth deficiency syndrome characterized by proportionate short stature, characteristic face and delayed speech development. Inheritance is possibly autosomal dominant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02079072
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  • 103
    Electronic Resource
    Electronic Resource
    Chromaffin cell xenografts in the rat neocortex can produce antidepressive activity in the forced swimming test (1995)
    Springer
    Experimental brain research 103 (1995), S. 59-69 
    Details
    ISSN: 1432-1106
    Keywords: Chromaffin cells ; Neural grafts Depression ; Frontal cortex ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Adrenal medullary allografts, as well as other monoaminergic tissues, have been demonstrated in our laboratory to increase antidepressive activity when transplanted into the frontal neocortex of rats. Refinement in the optimal parameters for xenograft viability has indicated that isolated bovine chromaffin cells may be an improved source of graft donor tissue. The aim of the present study was to determine whether isolated bovine chromaffin cell grafts to the rat frontal neocortex could provide an alternative source of catecholamines for antidepressant activity. Isolated bovine chromaffin cells, isolated bovine fibroblasts, or an equal volume of vehicle were unilaterally implanted into the right or left frontal cortex or right visual cortex. All rats were assessed before and 6 weeks after transplantation using the forced swimming test, a popular measure of antidepressant activity. Bovine chromaffin cell grafts in either the right or left frontal cortex produced significant increases in antidepressant activity compared to grafts of bovine fibroblasts and sham-operated or nontransplanted rats. In contrast, bovine chromaffin cells transplanted to the visual cortex did not affect antidepressant activity. Bovine fibroblast grafts in the frontal cortex also induced slight increases in antidepressant activity, although significantly less than chromaffin cell grafts. Morphological analysis revealed robust survival of tyrosine hydroxylase-positive chromaffin cells that retained their in situ ultrastructure and occasionally formed synaptic connections with the host parenchyma. These results suggest that xenografted isolated bovine chromaffin cells can provide a viable source of catecholamines for antidepressive activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241965
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  • 104
    Electronic Resource
    Electronic Resource
    Somatostatin-mRNA expression in brainstem projections into the medial preoptic nucleus (1995)
    Springer
    Experimental brain research 103 (1995), S. 344-354 
    Details
    ISSN: 1432-1106
    Keywords: Preoptic area ; Brainstem projections Somatostatin ; In situ hybridisation histochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The medial preoptic nucleus plays an important role in the regulation of neuroendocrine processes, vegetative functions, sexual behaviour and the modulation of the somatomotoric system. The connections of the medial preoptic nucleus to other areas of the central nervous system are very complex, and the area receives afferents using numerous transmitters and neuropeptides. Previous investigations have shown that this nucleus receives afferents from various brainstem nuclei that also contain somatostatinergic neurons. This study was carried out to investigate if somatostatin-projecting neurons of the brainstem are afferents to the medial preoptic nucleus. This was approached by combining somatostatin-mRNA in situ hybridisation with True Blue retrograde tracing. Our results demonstrate somatostinergic brain-stem projections into the medial preoptic nucleus mainly in the pedunculopontine nucleus and in the nucleus of the solitary tract (50% together). Other important somatostatinergic afferents into the medial preoptic nucleus originate in the cuneiform area, the dorsal parabrachial nucleus and in the lateral reticular nucleus (37% together). Less important are the somatostatinergic projections coming from the central grey, the laterodorsal tegmental nucleus, the locus coeruleus and the nucleus raphe magnus. Considering that these areas are involved in diverse functions such as cardiovascular regulation (nucleus of the solitary tract), transmission of visceral sensibility (dorsal parabrachial nucleus), modulation of the somatomotoric system (pedunculopontine nucleus) and in the regulation of neuroendocrine mechanisms (locus coeruleus), it seems tenable that the somatostatin projections demonstrated here also have a diverse functional quality within the medical preoptic nucleus where they terminate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241494
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  • 105
    Electronic Resource
    Electronic Resource
    The colocalization of parvalbumin and calbindin-D28k with GABA in the subnucleus caudalis of the rat spinal trigeminal nucleus (1995)
    Springer
    Experimental brain research 103 (1995), S. 402-408 
    Details
    ISSN: 1432-1106
    Keywords: Calcium-binding proteins ; GABA Immunocytochemistry ; Medullary dorsal horn ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The colocalization of two calcium-binding proteins, parvalbumin (PV) and calbindin-D28k (CaB), which have been reported to be markers of specific subpopulations of neurons in the central nervous system, with the inhibitory amino acid neurotransmitter γ-amino-butyric acid (GABA) was investigated in neurons of laminae I–IV of the subnucleus caudalis of the rat spinal trigeminal nucleus by using post-embedding immunocytochemical methods. Cells immunoreactive for PV, CaB, and GABA were found in all four laminae of the subnucleus caudalis. A substantial proportion of PV-immunoreactive perikarya were also stained for GABA in laminae II and III (44.8% and 39.8%, respectively). However, the majority of PV-containing neurons in laminae I and IV (100% and 86%, respectively), as well as CaB-immunoreactive cells in all four laminae (98.4%), were GABA-negative. These results show that, in contrast to higher brain centers, PV-, CaB-, and GABA-immunoreactive perikarya represent significantly different populations of neurons in the subnucleus caudalis of the rat. In the light of the present findings, the differences in the neurochemical properties of the subnucleus caudalis of the spinal trigeminal nucleus and the spinal dorsal horn are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241499
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  • 106
    Electronic Resource
    Electronic Resource
    Inluence of eye motion on adaptive modifications of the vestibulo-ocular reflex in the rat (1995)
    Springer
    Experimental brain research 103 (1995), S. 393-401 
    Details
    ISSN: 1432-1106
    Keywords: VOR adaptation ; Ocular proprioception Efference copy ; Retinal slip ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract While sustained retinal slip is assumed to be the basic conditioning stimulus in adaptive modifications of the vestibulo-ocular reflex (VOR) gain, several observations suggest that eye motion-related signals might also be involved. We oscillated pigmented rats over periods of 20 min around the vertical axis, at 0.3 Hz and 20°/s peak velocity, in different retinal slip and/or eye motion conditions in order to modify their VOR gain. The positions of both eyes were recorded by means of a phase-detection coil system with the head restrained. The main findings came from the comparison of two basic conditions — including their respective controls — in which one or both eyes were reversibly immobilised by threads sutured to the eyes. In the first condition the animals were rotated in the light with one eye immobilised and the other eye free to move but covered. Rotation in the light in this open-loop condition immediately elicited high-gain compensatory eye movements of the non-impeded, covered eye. At the end of this training procedure, the VOR gain increased by 42.3%. In the second condition, both eyes were immobilised and one eye was covered. The result was an increase in the VOR gain of 26.3%. These two conditions were similar as to the visuo-vestibular drive during the exposure, but different as to the resulting — and allowed — eye motion, showing that the condition where the larger eye movements occurred yielded the larger VOR gain change. Our data support the idea proposed by Collewijn and Grootendorst (1979, p. 779) and Collewijn (1981, p. 146) that “[retinal] slip and eye movements seem to be relevant signals for the adaptation of the rabbit's visuo-vestibular oculomotor reflexes”. Our data also suggest that sensory information related to eye movements, more likely than efference copy, is the coding signal for eye movement which combines with the retinal slip signal to generate adaptive changes of the VOR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241498
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  • 107
    Electronic Resource
    Electronic Resource
    The effect of glial cell line-derived neurotrophic factor in fibrin glue on developing dopamine neurons (1995)
    Springer
    Experimental brain research 104 (1995), S. 199-206 
    Details
    ISSN: 1432-1106
    Keywords: Fibrin glue ; Transplantation ; GDNF ; Substantia nigra ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Glial cell line-derived neurotrophic factor (GDNF), a member of the transforming growth factor-β superfamily, promotes the survival, morphological differentiation, and high-affinity dopamine (DA) uptake of cultured nigral DA neurons. In order to test potential methodology for peptide delivery in vivo, GDNF-containing fibrin glue balls (8 μg/ball) were incorporated with pieces of fetal ventral mesencephalon (E15) and transplanted into the anterior chambers of sympathetically denervated adult rats. Five weeks after grafting, the numbers of TH-positive neurons and the nerve fiber density were significantly higher in the ventral mesencephalic grafts treated with GDNF-containing glue balls than in those treated with vehicle. In addition, the laminin and GFAP immunoreactivities were similar between the two groups. These data support the concept that GDNF is a potent trophic factor for DA neurons in vivo and suggest that fibrin glue may provide a unique and safe means to permit prolonged delivery of trophic molecules to CNS tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00242006
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  • 108
    Electronic Resource
    Electronic Resource
    Excitotoxic lesions of the pedunculopontine tegmental nucleus disinhibit orofacial behaviours stimulated by microinjections of d-amphetamine into rat ventrolateral caudate-putamen (1995)
    Springer
    Experimental brain research 104 (1995), S. 262-274 
    Details
    ISSN: 1432-1106
    Keywords: Oral motor behaviour ; Pedunculopontine tegmental nucleus ; Ventrolateral caudate-putamen ; Amphetamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Data are presented which support the hypothesis that the pedunculopontine tegmental nucleus serves as an output station for the striatum and, in particular, has a role in the expression of behaviour stimulated from the ventrolateral caudate-putamen, a rodent homologue of the primate putamen. Rats received either bilateral ibotenate or sham lesions in the pedunculopontine tegmental nucleus and bilateral cannulation of the ventrolateral caudate-putamen. Oral motor activities were observed following microinjection of 5.0, 10.0 and 20.0 μg d-amphetamine (and vehicle-only control) into the ventrolateral caudate-putamen. As expected, orofacial behaviours such as biting and licking were observed in sham-lesioned rats following this treatment, but pedunculopontine tegmental nucleus-lesioned rats exhibited an increase in the incidence of these oral motor behaviours at all doses of amphetamine compared with the controls. This increase was the product of changes in the duration and number of times in which they engaged in oral motor behaviours, but not the latency to initiate them. There was no change in the normal oral motor activities associated with grooming. Histological analysis showed that ibotenate lesions destroyed both cholinergic and non-cholinergic neurones in the pedunculopontine tegmental nucleus. These data indicate that loss of the pedunculopontine tegmental nucleus disinhibits oral motor behaviours stimulated from the ventrolateral caudateputamen by d-amphetamine and are discussed in terms of their implications for understanding the relationships between striatal outflow and structures in the pons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00242012
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  • 109
    Electronic Resource
    Electronic Resource
    Synaptic interactions involving acetylcholine, glutamate, and GABA in rat auditory cortex (1995)
    Springer
    Experimental brain research 107 (1995), S. 59-72 
    Details
    ISSN: 1432-1106
    Keywords: Acetylcholine ; Glutamate ; NMDA ; GABA ; Cerebral cortex ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Using electrophysiological techniques in the in vitro rat auditory cortex, we have examined how spontaneous acetylcholine (ACh) release modifies synaptic potentials mediated by glutamate and γ-aminobutyric acid (GABA). Single stimulus pulses to lower layer VI elicited in layer III a four-component (A-D) extracellular field response involving synaptic potentials mediated by glutamate and GABA. The cholinesterase inhibitor eserine (10–20 μM) or the cholinergic agonist carbachol (25–50 μM) depressed by 10–50% the glutamatergic components A and C, and the GABAergic components B and D. Atropine reversed the depressive effects of eserine and carbachol. A novel finding was that the degree of depression of component A varied inversely with stimulus intensity. However, during partial pharmacological antagonism of GABAA receptors, depression of A varied directly, not inversely, with stimulus intensity. Normally, then, depression of A is offset by reduced GABAergic inhibition of A. We also tested for differential depression of responses mediated by N-methyl-d-aspartate (NMDA) versus non-NMDA glutamate receptors. Following physiological and pharmacological isolation of the responses, eserine depressed the non-NMDA, but not the NMDA, receptor-mediated potential. Since the isolated NMDA potential still could be depressed by carbachol, the data suggested that activation of NMDA receptors may reduce spontaneous ACh release. In support of this, preincubation of slices in NMDA (10–20 μM) largely prevented eserine's, but not carbachol's, depression of components A and B. These results permit three conclusions of relevance to cortical information processing: (1) spontaneous ACh release tonically depresses synaptic potentials mediated by glutamate and GABA; (2) ACh depresses responses to weak inputs to a greater degree than responses to strong inputs; (3) activation of NMDA receptors may “feed-back” to reduce ACh release, a mechanism that could place regulation of local ACh release under glutamatergic afferent control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228017
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  • 110
    Electronic Resource
    Electronic Resource
    Thermal images of somatic sensory cortex obtained through the skull of rat and gerbil (1995)
    Springer
    Experimental brain research 106 (1995), S. 7-18 
    Details
    ISSN: 1432-1106
    Keywords: Infrared image ; Somatosensory cortex ; Skull ; Rat ; Gerbil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Infrared images of the skull surface were obtained in urethane-anesthetized rats and gerbils before, during and after mechanical stimulation of the face and mystacial vibrissae on one side. Areas of increased temperature on the skull, localized mainly over the face area of the primary somatosensory cortex contralateral to the side of stimulation, appeared within 4–5 s after the onset of stimulation. Rarely, such temperature change was recorded bilaterally. Temperatures did not remain high on the intact skull in rats, but fell to baseline within minutes after stimulus onset regardless of stimulus duration. In rats in which the skull had been thinned and in gerbils with intact skull, temperatures remained elevated during the course of stimulation. We were unable to resolve the activation of individual vibrissae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241352
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  • 111
    Electronic Resource
    Electronic Resource
    A survey of spinal dorsal horn neurones encoding the spatial organization of withdrawal reflexes in the rat (1995)
    Springer
    Experimental brain research 106 (1995), S. 19-27 
    Details
    ISSN: 1432-1106
    Keywords: Pain ; Nociception ; Sensorimotor integration ; Receptive field ; Somatosensory ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The withdrawal reflex pathways to hindlimb muscles have an elaborate spatial organization in the rat. In short, the distribution of sensitivity within the cutaneous receptive field of a single muscle has a spatial pattern that is a mirror image of the spatial pattern of the withdrawal of the skin surface ensuing on contraction in the respective muscle. In the present study, a search for neurones encoding the specific spatial input-output relationship of withdrawal reflexes to single muscles was made in the lumbosacral spinal cord in halothane/nitrous oxide-anaesthetized rats. The cutaneous receptive fields of 147 dorsal horn neurones in the L4-5 segments receiving a nociceptive input and a convergent input from A and C fibres from the hindpaw were studied. The spatial pattern of the response amplitude within the receptive fields of 118 neurones was quantitatively compared with those of withdrawal reflexes to single muscles. Response patterns exhibiting a high similarity to those of withdrawal reflexes to single muscles were found in 27 neurones located in the deep dorsal horn. Twenty-six of these belonged to class 2 (responding to tactile and nociceptive input) and one belonged to class 3 (responding only to nociceptive input). None of the neurones tested (n=20) with reflex-like response patterns could be antidromically driven from the upper cervical cord, suggesting that they were spinal interneurones. With some overlap, putative interneurones of the withdrawal reflexes to the plantar flexors of the digits, the plantar flexors of the ankle, the pronators, the dorsiflexors of the ankle, and a flexor of the knee, were found in succession in a mediolateral direction. It is concluded that neurones that are able to encode the specific spatial input-output organization of the withdrawal reflexes to single muscles do exist in the deep dorsal horn. Such reflex encoders appear to have a “musculotopic” organization. A hypothesis of the organization of the withdrawal reflex system is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241353
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  • 112
    Electronic Resource
    Electronic Resource
    Raphespinal and reticulospinal neurons project to the dorsal vagal complex in the rat (1995)
    Springer
    Experimental brain research 106 (1995), S. 79-92 
    Details
    ISSN: 1432-1106
    Keywords: Autonomic ; Axon collaterals ; Medial tegmental field ; Motoneurons ; Respiratory ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Stimulation of the caudal raphe nuclei alters visceral functions. The caudal raphe nuclei project to the nucleus of the solitary tract, which receives the central terminations of vagal afferents and plays an important role in the central integration of autonomic activities. The caudal raphe nuclei also project to the somatic and preganglionic autonomixc motoneurons of the spinal cord. Diamidino yellow was injected into the nucleus of the solitary tract, and fast blue was injected into either the cervical, thoracic, or lumbar spinal cord. Large numbers of double-labeled neurons were present within the caudal raphe nuclei and the adjacent reticular formation of the medial tegmental field. This observation documents that individual raphespinal and reticulospinal neurons project an axon collateral to the nucleus of the solitary tract. These data demonstrate the anatomic substrate for global modulation of the autonomic motoneuron pool by the caudal raphe nuclei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241358
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  • 113
    Electronic Resource
    Electronic Resource
    Fictive motor activities in adult chronic spinal rats transplanted with embryonic brainstem neurons (1995)
    Springer
    Experimental brain research 106 (1995), S. 69-78 
    Details
    ISSN: 1432-1106
    Keywords: Neural transplantation ; Locomotion ; Paw shaking ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The present study was designed to examine the effects of an intraspinal transplantation of embryonic brainstem neurons on fictive motor patterns which can develop in hindlimb nerves of adult chronic spinal rats. Seventeen adult rats were spinalized at T8-9 level and, 8 days later, a suspension of embryonic cells obtained either from the raphe region (RR, n=8) or from the locus coeruleus (LC, n=9) was injected caudally (T12–13) to the cord transection. Eight control animals (control rats) were spinalized and injected with vehicle under the same conditions. One to three months later, the animals were decorticated and fictive motor patterns were recorded in representative hindlimb nerves. The data revealed that both control and grafted spinal rats could exhibit two distinctly different fictive motor patterns, one which could be associated with stepping and the other with hindlimb paw shaking. They further showed that following transplantation of embryonic RR or LC neurons the excitability of the spinal stepping generator was increased, whereas that of the spinal neural circuits which generate hindlimb paw shaking was not significantly affected. A histological analysis performed on the spinal cord segments below the transection revealed complete absence of serotonin and noradrenaline immunoreactivity in control spinal animals and, in both types of grafted rats, an extensive monoaminergic reinnervation with synaptic contacts between monoaminergic transplanted neurons and host interneurons and/or motoneurons. The possible mechanisms by which grafted monoaminergic neurons can influence the spinal motor networks are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241357
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  • 114
    Electronic Resource
    Electronic Resource
    Astroglial responses in photochemically induced focal ischemia of the rat cortex (1995)
    Springer
    Experimental brain research 106 (1995), S. 1-6 
    Details
    ISSN: 1432-1106
    Keywords: Spreading depression ; GFAP ; Astrocytes ; Focal ischemia ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study investigated astroglial responses after focal cerebral ischemia in the rat cortex induced by photothrombosis. Astrocyte activation was studied at various time points by immunocytochemistry for glial fibrillary acidic protein (GFAP) and vimentin (VIM). We found a dual astrocytic response to focal ischemia: In the border zone of the infarct, GFAP-positive astrocytes were present within 2 days and persisted for 10 weeks. These astrocytes additionally expressed VIM. Remote from the ischemic lesion, cortical astrocytes of the entire ipsilateral hemisphere transiently expressed GFAP, but not VIM, beginning on day 3 after photothrombosis. This response had disappeared on day 14. By recording DC potentials, five to seven spreading depressions (SD) could be detected on the cortical surface during the first 2 h after photothrombosis. Treatment with MK801, a non-competitive NMDA-receptor antagonist, completely abolished SD and remote ipsilateral astrocytic activation, while the reaction in the border zone of the infarct remained unchanged. Functionally, persistent astrocytosis around the infarct might be induced by leukocyte-derived cytokines, while NMDA-receptor-mediated SD might cause remote responses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241351
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  • 115
    Electronic Resource
    Electronic Resource
    Intrinsic burst generation of preinspiratory neurons in the medulla of brainstem-spinal cord preparations isolated from newborn rats (1995)
    Springer
    Experimental brain research 106 (1995), S. 57-68 
    Details
    ISSN: 1432-1106
    Keywords: Respiratory rhythm ; Respiratory neurons ; Pacemaker neurons ; Perforated patch ; Nystatin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In brainstem-spinal cord preparations isolated from newborn rats, intrinsic burst-generating properties of preinspiratory (Pre-I) neurons in the rostral ventrolateral medulla, which have been suggested to be primary respiratory rhythm-generating neurons, were studied by “perforated” whole-cell recordings using the antibiotic nystatin. Nystatin causes small pores to be formed in the cells, through which pass small monovalent ions. For blockade of chemical synaptic transmission, perfusate Ca2+ concentration was lowered to 0.2 mM and the Mg2+ concentration was increased to 5 mM. In Iow-Ca2+, high-Mg2+ solution (referred to here as “low Ca”), 10 of 55 Pre-I neurons generated rhythmic bursts (burst type), 14 fired tonically (tonic type), and 31 were silent (silent type). Burst-type neurons showed periodic depolarization of 5–12 mV in low Ca, at a rate of 12±6.5/min. Hyperpolarization of the membrane caused decrease in or disappearance of the periodic depolarization and prolongation of the cycle period. Thus, the burst generations were voltage dependent. The firing frequency of tonictype neurons was 2.3±1.6 Hz and was decreased by hyperpolarization. In 6 of these neurons, the firing patterns changed to burst patterns during continuous hyperpolarization. Membrane depolarization by continuous outward current injection into some silent-type neurons (3 of 11 tested) induced bursting activity. Activity of C4 and Pre-I neurons was completely silent with 0.1–1 μM tetrodotoxin (TTX) added to the standard perfusate. In low Ca, burst-type neurons (n=3) were also silent with 1 μM TTX perfusion. Inspiratory neurons either became silent (n=4) or fired tonically (n=1) in low Ca. The present study by “perforated” whole-cell recordings confirmed that some Pre-I neurons possess intrinsic burst-generating properties, which were not attributable to phasic synaptic inputs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241356
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  • 116
    Electronic Resource
    Electronic Resource
    Cooperative effects of neuronal ensembles (1995)
    Springer
    Experimental brain research 106 (1995), S. 106-110 
    Details
    ISSN: 1432-1106
    Keywords: Spiking neural network ; Refractory period ; Phase transition ; Finite-size effect ; Hippocampal culture ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Electrophysiological properties of neurons as the basic cellular elements of the central nervous system and their synaptic connections are well characterized down to a molecular level. However, the behavior of complex noisy networks formed by these constituents usually cannot simply be derived from the knowledge of its microscopic parameters. As a consequence, cooperative phenomena based on the interaction of neurons were postulated. This is a report on a study of global network spike activity as a function of synaptic interaction. We performed experiments in dissociated cultured hippocampal neurons and, for comparison, simulations of a mathematical model closely related to electrophysiology. Numeric analyses revealed that at a critical level of synaptic connectivity the firing behavior undergoes a phase transition. This cooperative effect depends crucially on the interaction of numerous cells and cannot be attributed to the spike threshold of individual neurons. In the experiment a drastic increase in the firing level was observed upon increase of synaptic efficacy by lowering of the extracellular magnesium concentration, which is compatible with our theoretical predictions. This “on-off” phenomenon demonstrates that even in small neuronal ensembles collective behavior can emerge which is not explained by the characteristics of single neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241360
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    A behavioral model of excitotoxicity: retinal degeneration, loss of vision, and subsequent recovery after intraocular NMDA administration in adult rats (1995)
    Springer
    Experimental brain research 106 (1995), S. 93-105 
    Details
    ISSN: 1432-1106
    Keywords: Retina ; NMDA ; HRP ; Neurotoxicity ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To establish a new behavioral animal model of excitotoxicity, we injected adult rats intraocularly with a single dose of 2, 20, or 100 nmol of N-methyl-d-aspartate (NMDA). We quantified visual impairment by plotting the size of the visual field in which the rats successfully oriented towards a small, moving target. In comparison to the saline-injected (contralateral) control side, the side injected with 2 nmol of NMDA was not significantly impaired. When injected with higher doses, the rats were nearly blind immediately after surgery, with only about 20% (20 nmol NMDA) or 10% (100 nmol NMDA) of residual vision. Within about 3 weeks, however, visual performance returned to near-normal levels. Simultaneous intraocular administration of a non-competitive NMDA-antagonist, MK-801 (1 nmol), resulted in complete behavioral protection. NMDA administration led to a dose-dependent loss of cells within the ganglion cell layer, as assessed in whole-mounted retinae which were retrogradely labelled with horseradish peroxidase (HRP). Whereas 2 nmol of NMDA led to the loss of about 30% of retinal ganglion cells (RGCs), at higher NMDA doses only 13% of the RGCs survived. After the injection of 20 nmol of NMDA, large-diameter RGCs (〉22 μm) survived the lesion to a greater extent than small diameter cells (8–21 μm); at 100 nmol cells of all diameters were equally affected. The number of Nissl-stained cells with small diameters (〈11 μm), presumed to be displaced amacrine cells, was also affected by NMDA, although to a lesser degree. Analysis of behavioral performance (vision score) and the number of cells in the retina revealed a correlation of r=0.76 between visual performance and the number of HRP-filled RGCs immediately after surgery. Lower correlations were found between visual performance and cells stained with Nissl of diameters smaller than 11 μm (presumably displaced amacrine cells) or larger than 11 μm (presumed RGCs without retinofugal connections; r=0.55 and r=0.58, respectively). Because of the spontaneous recovery of vision, all correlations declined to values near 0 after 3 weeks. Thus, despite a dramatic loss of RGCs following NMDA administration, visual deficits recover significantly in adult rats within 2–3 weeks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241359
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    Synaptic depression in visual cortex tissue slices: an in vitro model for cortical neuron adaptation (1995)
    Springer
    Experimental brain research 106 (1995), S. 145-155 
    Details
    ISSN: 1432-1106
    Keywords: Adaptation ; Depression ; LTD ; LTP ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Synaptic depression was assessed from intracellular recordings in cortical tissue slices. Evoked postsynaptic potentials exhibited synaptic depression with an exponential or double exponential decrease (time constants: 〈1–30 s) in amplitude during repetitive afferent stimulation by short trains of suprathreshold stimuli. Depressed synaptic responses recovered with an exponential time course (time constants: 10 s-8 min) during presentation of similar short trains of stimuli every 5 or 10 s. Cortical cells recorded extracellularly in cat visual cortex show similar time constants of response decrement during adaptation to moving stripes. Postsynaptic voltage- or ion-regulated conductances and chloride conductances do not appear to be involved in synaptic depression. Input resistance changes and effects of injection of chloride indicate a lack of GABAA receptor-mediated effects. Hyperpolarizing or depolarizing neurons, and pairing polarization with afferent stimulation, also did not affect synaptic depression. This distinguishes these processes from long-term depression and long-term potentiation. Our results suggest that the most likely mechanisms of synaptic depression and adaptation in cortical cells are presynaptic decrease in transmitter release and/or receptor desensitization. Short-term postsynaptic changes may also occur after synaptic depression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241364
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  • 119
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    NMDA and non-NMDA receptors mediate taste afferent inputs to cortical taste neurons in rats (1995)
    Springer
    Experimental brain research 106 (1995), S. 391-402 
    Details
    ISSN: 1432-1106
    Keywords: Taste ; Insular cortex ; Excitatory amino acid receptor ; Iontophoresis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two main subclasses of ionotropic receptors for excitatory amino acids (EAAs), N-methyl-d-aspartate (NMDA) receptors and non-NMDA receptors, are involved in neurotransmission in the cortex of mammals. To examine whether EAAs are transmitters at the cortical taste area (CTA) in rats and to elucidate which types of the two ionotropic receptors operate at these synapses, we studied the effects of microiontophoretic administration of EAA antagonists on the responses of 64 taste cortical neurons to four basic taste stimuli in urethane-anesthetized rats. Both d-2-amino-5-phosphonovalerate (APV), a selective antagonist for NMDA receptors, and 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX), a selective antagonist for non-NMDA receptors, suppressed most of the taste responses. The percentage of neurons suppressed by APV (70.3%) was almost the same as that suppressed by CNQX (64.1%). These suppressive effects were independent of the effects of background discharges during the prestimulus, water-rinsing period. The percentage of neurons suppressed by the antagonists did not differ between any pairs of taste stimuli. The number of neurons possessing both receptors was larger in the granular insular area (area GI), one of the two CTAs, than in the dysgranular insular area (area DI). In addition, taste responses were suppressed by CNQX or by both APV and CNQX in area GI in a significantly larger number of layer V neurons than in area DI. The present results indicate that normal excitatory transmission of taste afferents in the CTA in rats was mediated by both NMDA and non-NMDA receptors. The finding that a large fraction of neurons in the CTA in rats mediated taste information through NMDA receptors in normal transmission might be related to the higher potency of the plasticity observed in the CTA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231062
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  • 120
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    Nephrotic syndrome associated with N-hydroxyureas, inhibitors of 5-lipoxygenase (1995)
    Springer
    Archives of toxicology 69 (1995), S. 480-490 
    Details
    ISSN: 1432-0738
    Keywords: Key words 5-Lipoxygenase inhibitors ; N-Hydroxyureas ; Nephrotoxicity ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The N-hydroxyurea derivatives 70C ((E)-N-{3-[3-(4-fluorophenoxy)phenyl]-1-(R,S)-methylprop-2-enyl}-N-hydroxyurea) and its (R) 225C and (S) 404C enantiomers, which were being developed as 5-lipoxygenase inhibitors for the treatment of certain allergic and inflammatory conditions, were found to cause severe glomerulonephropathy in the rat. The lesion appeared to be of greater severity in female rats compared with male rats. In addition, 70C and 225C treated animals appeared more severely affected than 404C treated animals. Detailed examination of the lesion in animals dosed with 225C showed that there was a clear relationship between the onset of the lesion and the dose given, i.e. the higher the dose the sooner the lesion developed. The earliest changes detected in the kidney by transmission electron microscopy were noted in the glomeruli, in which the visceral cells appeared enlarged and showed varying degrees of foot process loss. In the more advanced lesion, the degree of foot process loss became more obvious and changes in the kidney tubules were seen by light microscopy. The morphological changes were mirrored by a dose-related increase in water consumption, an increased kidney to body weight ratio and gastrointestinal oedema, suggesting impaired renal function. Shortly after the onset of foot process loss, decreases in the total plasma protein and albumin and increases in the plasma cholesterol, triglycerides, urea and creatinine were recorded. These changes, particularly the foot-process loss, together with increased proteinuria, hypoalbuminaemia, hypercholesterolaemia and lipaemia, are all characteristic of “minimal change nephrotic syndrome”. Because of the serious nature of the kidney lesion caused by these N-hydroxyureas in the rat, it was considered that it precluded their development as therapeutic agents for use in man.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050202
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    Regional differences in expression of osteonectin mRNA after administration of cadmium to rats (1995)
    Springer
    Archives of toxicology 69 (1995), S. 590-595 
    Details
    ISSN: 1432-0738
    Keywords: Key words Cadmium ; Osteonectin ; Metallothionein ; Gene expression ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Osteonectin gene expression in relation to metallothionein mRNA expression was investigated in various tissues from Cd-treated rats. After a single 50 μmol/kg subcutaneous injection of CdCl2, Cd predominantly accumulated in the liver and metallothionein gene expression significantly increased concomitantly with Cd accumulation, but no alteration of osteonectin gene expression was observed. In the kidney and lung, both metallothionein and osteonectin mRNA increased significantly but the elevation of metallothionein mRNA levels (1 h after Cd administration) preceded that of osteonectin (3 h after administration). A significant elevation of osteonectin mRNA levels was also observed in the testis after 3 h, but that of metallothionein mRNA occurred after 6 h. Not only accumulation of Cd but also increments in both osteonectin and metallothionein mRNA were minimal in the brain, but a significant increase in gene expression was observed after 1 h for osteonectin and after 3 h for metallothionein. Since, except in the testis, metallothionein gene expression preceded osteonectin gene expression, the induced metallothionein might transpose Cd and thereby affect its levels immediately, thus reducing the levels of Cd available for accumulation in other tissues. Hence, the osteonectin-Cd interaction might be secondary to the metallothionein-Cd interaction. However, the fact that osteonectin mRNA was predominantly induced by Cd administration in the target tissues of Cd toxicity, such as the lung, kidney and testis, suggests the possible involvement of osteonectin in Cd intoxication/detoxication mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050218
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    Effects of paraquat, dinoseb and 2,4-D on intracellular calcium and on vasopressin-induced calcium mobilization in isolated hepatocytes (1995)
    Springer
    Archives of toxicology 69 (1995), S. 460-466 
    Details
    ISSN: 1432-0738
    Keywords: Key words Paraquat ; Dinoseb ; 2 ; 4-D Intracellular calcium ; Rat ; Hepatocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The effects of the herbicides paraquat, dinoseb and 2,4-D on intracellular Ca2+ levels and on vasopressin-induced Ca2+ mobilization were investigated in intact isolated hepatocytes. Incubation of rat hepatocytes with paraquat (5 mM for 60 min) and dinoseb (10 μM) resulted in a time-dependent loss of viability by approximately 25%. Viability of cells treated with 2,4-D decreased significantly, dropping to about 20% at 10 mM and 60 min incubation. Exposure of hepatocytes to paraquat (1–10 mM) for 60 min had no effect on the basal level of [Ca2+] i . Additionally, exposure to paraquat had no effect on the magnitude and on the duration of the [Ca2+] i response to vasopressin. In the presence of 2,4-D (1–10 mM), basal [Ca2+] i increases as a function of herbicide concentration. The magnitude of the Δ[Ca2+] i response decreases from 256±8 nM in control to 220±5 nM, at 10 mM 2,4-D. Exposure of hepatocytes to dinoseb (1–10 μM) had no effect on the basal level of [Ca2+] i . However, a strong concentration-dependent decrease in the magnitude of Δ[Ca2+] i in response to vasopressin was noticed at 60 min incubation. Dinoseb markedly inhibited the stimulation of the production of inositol phosphates by vasopressin stimulus. The present study demonstrates that paraquat, 2,4-D and dinoseb cause cell death in hepatocytes by mechanisms not related to an early increase in [Ca2+] i . Additionally, it has been shown for the first time that dinoseb disturbs the transduction mechanism promoted by vasopressin by inhibiting the formation of IP3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050199
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    Investigation of potential oncogenetic effects of β-cyclodextrin in the rat and mouse (1995)
    Springer
    Archives of toxicology 69 (1995), S. 631-639 
    Details
    ISSN: 1432-0738
    Keywords: Key words β-Cyclodextrin ; Oncogenicity ; Rat ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The results of oncogenicity studies of β-cyclodextrin in inbred Fischer 344 rats and CD-1 outbred mice are presented. Chronic feeding of β-cyclodextrin to Fischer 344 rats and CD-1 mice did not cause any treatment related carcinogenic effects. The only toxic effect was seen in mice as macroscopic distension of the large intestine with soft or fluid contents, histologically associated with the mucosa covered by mucous secretion containing exfoliated cells, and mucosal flattening and intestinal gland atrophy. Despite these observations, no differences between control and treated groups were observed concerning mortality, clinical observations or body weight and food consumption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050224
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    Prediction of uptake of methyl mercury by rat erythrocytes using a two-compartment model (1995)
    Springer
    Archives of toxicology 70 (1995), S. 34-42 
    Details
    ISSN: 1432-0738
    Keywords: Key words Compartment model ; Erythrocytes ; Intracellular compartmentation ; Methyl mercury ; Rat ; Uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The uptake of methyl mercury (MeHg) by isolated rat erythrocytes was studied at 37°C using MeHg-cysteine (MeHgCySH), MeHg-glutathione (MeHgGSH), MeHg-mercaptalbumin (MeHgMASH) and the mixture of MeHgCySH with MeHgGSH, MeHgCySH with MeHgMASH, MeHgGSH with MeHgMASH at different MeHg concentrations. The measured MeHg concentrations were analyzed according to the Akaike’s information criterion in order to determine the suitable compartment model. After determining a two-compartment model, a model-independent two-compartment model was developed from the kinetics of uptake of MeHg at a concentration of 1 mmol MeHg/l packed erythrocytes using MeHgCySH, MeHgGSH and MeHgMASH, respectively. The developed two-compartment model was validated by predicting the kinetics of uptake of MeHg by rat erythrocytes at different MeHg concentrations and different mixtures of MeHg-complexes. Then, the predicted values were compared with the measured values. The results suggested: 1) MeHg uptake appeared suitable to be described by a two-compartment model, while using MeHgGSH, MeHgMASH, MeHgCySH at lower concentrations and the mixtures of MeHg-complexes; 2) MeHgCySH uptake was slowest among three kinds of MeHg-complexes, although a postulated cysteine-facilitated MeHgCySH transport system might exist in erythrocyte membrane; 3) the mixture of MeHg-complexes might facilitate MeHgCySH uptake; 4) there might be a second MeHg intracellular compartment in rat erythrocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050246
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    Cytotoxicity of propyl gallate and related compounds in rat hepatocytes (1995)
    Springer
    Archives of toxicology 69 (1995), S. 204-208 
    Details
    ISSN: 1432-0738
    Keywords: Key words Propyl gallate ; Rat ; Hepatocytes ; Cytotoxicity ; Gallate esters ; Antioxidant ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The cytotoxic effects of propyl gallate (PG), its related gallates and gallic acid have been studied in freshly isolated rat hepatocytes. Addition of PG (0.5–2.0 mM) to hepatocyte suspension elicited concentration-dependent cell death accompanied by losses of intracellular ATP, adenine nucleotide pools, glutathione (GSH) and protein thiols. The rapid loss of intracellular ATP preceded the onset of cell death caused by PG. In the comparative toxic effects of PG and related gallates at concentration of 1 mM, octyl gallate (OG), dodecyl gallate (DG) and butyl gallate (BG) elicited an abrupt depletion of ATP, followed by an acute cell death. These gallates were more toxic than PG; the toxic effects of PG were similar to those of methyl gallate (MG) and ethyl gallate (EG). In mitochondria isolated from rat liver, PG caused a concentration-dependent increase in the rate of state 4 oxygen consumption, indicating an uncoupling effect. The rate of state 3 oxygen consumption was inhibited by OG and DG. According to the respiratory control index, the order of impairment potency to mitochondria was OG〉BG, DG〉PG〉EG, MG〉gallic acid. These results indicate that PG and related gallates are toxic to hepatocytes and that the acute cytotoxicity may be due to mitochondrial dysfunction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050159
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    Subchronic toxicity of 3-phenylamino alanine, an impurity in L-tryptophan reported to be associated with eosinophilia-myalgia syndrome (1995)
    Springer
    Archives of toxicology 69 (1995), S. 444-449 
    Details
    ISSN: 1432-0738
    Keywords: Key words Eosinophilia-myalgia syndrome ; L-Tryptophan ; 3-(Phenylamino) alanine ; Rat ; 1 ; 1’-Ethylidenebis (L-tryptophan)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Consumption of certain product lots of L-tryptophan (LT) has been reported to be epidemiologically associated with an outbreak of eosinophilia-myalgia syndrome (EMS) in the United States. Since the production lots were found to contain 3-phenylamino alanine (PAA) as an impurity, its effects were studied by administering the substance orally by gavage to 5-week-old Sprague-Dawley rats. Groups of animals were given PAA for 13 consecutive weeks at dose levels of 1, 10 and 100 mg/kg per day. The animals were killed at 4 or 8 weeks. Hematological and blood biochemical tests were performed and detailed histopathological observations were made. No significant abnormalities were observed in the test animals and in particular no EMS-like conditions. A brief summary of other animal studies using several species of rats and mice performed in our laboratory since 1989 on various LT related substances is also presented. No EMS-like effects were observed in these studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050197
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    Fetal brain disruption sequence in sisters (1995)
    Springer
    European journal of pediatrics 154 (1995), S. 654-657 
    Details
    ISSN: 1432-1076
    Keywords: Fetal development ; Brain diseases ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report two female siblings with the fetal brain disruption sequence. Extensive investigation of both children failed to define a definitive aetiology but clinical and laboratory findings are consistent with a hitherto unknown storage disease. We postulate that the accumulation of a neurotoxic metabolite may be responsible for the disease phenotype observed. This is the first report of recurrence of the fetal brain disruption sequence and supports the existence of a genetic form of this condition. Previous reports have emphasized possible environmental aetiologies. Infants with fetal brain disruption sequence should be investigated exhaustively and, in the absence of definitive evidence of an environmental cause, the possibility of a genetic aetiology should be considered. In some families the recurrence risk may be as high as one in four.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02079071
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    Fetal brain disruption sequence in sisters (1995)
    Springer
    European journal of pediatrics 154 (1995), S. 654-657 
    Details
    ISSN: 1432-1076
    Keywords: Key words Fetal development ; Brain diseases ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report two female siblings with the fetal brain disruption sequence. Extensive investigation of both children failed to define a definitive aetiology but clinical and laboratory findings are consistent with a hitherto unknown storage disease. We postulate that the accumulation of a neurotoxic metabolite may be responsible for the disease phenotype observed. This is the first report of recurrence of the fetal brain disruption sequence and supports the existence of a genetic form of this condition. Previous reports have emphasized possible environmental aetiologies. Infants with fetal brain disruption sequence should be investigated exhaustively and, in the absence of definitive evidence of an environmental cause, the possibility of a genetic aetiology should be considered. In some families the recurrence risk may be as high as one in four.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004310050366
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    Floating-Harbor syndrome: description of a further patient, review of the literature, and suggestion of autosomal dominant inheritance (1995)
    Springer
    European journal of pediatrics 154 (1995), S. 658-661 
    Details
    ISSN: 1432-1076
    Keywords: Key words Floating-Harbor ; syndrome ; Growth retardation ; Dysmorphology ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The Floating-Harbor syndrome is a growth retardation syndrome with delayed bone age, speech development, and typical facial features. The face is triangular with deep-set eyes, long eyelashes, bulbous nose, wide columella, short philtrum, and thin lips. We present an additional patient and review 16 cases from the literature. The possible phenotype in the patient's mother suggests a dominant mode of inheritance for the syndrome. Conclusion The Floating Harbor syndrome is a growth deficiency syndrome characterized by proportionate short stature, characteristic face and delayed speech development. Inheritance is possibly autosomal dominant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004310050367
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    A genetic study of idiopathic focal dystonias (1995)
    Springer
    Journal of neurology 242 (1995), S. 508-511 
    Details
    ISSN: 1432-1459
    Keywords: Dystonia ; Torticollis ; Blepharospasm ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The inheritance of focal dystonias was investigated in 43 families containing 43 index cases with torticollis (n = 21), blepharospasm (n = 18) and writer's cramp (n = 4). They generated a potential population of 235 first-degree relatives, and 168 out of 179 living first-degree relatives were examined. Ten relatives with dystonia were identified in ten families. Another two parents from two of the same group of ten families were affected according to the family history. The majority of the secondary cases (six patients, five siblings, and one child) were not aware of any dystonia. The tendency for affected relatives to have the same type of dystonia as index patients was observed only for torticollis. Overall, 23% of index patients had relatives with dystonia. Segregation analysis suggested the presence of an autosomal dominant gene or genes with reduced penetrante underlying focal dystonia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00867421
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    Genetische Faktoren bei der Entstehung und Progression maligner Melanome (1995)
    Springer
    Der Hautarzt 46 (1995), S. 394-399 
    Details
    ISSN: 1432-1173
    Keywords: Schlüsselwörter Malignes Melanom ; Genetische Instabilität ; Genetik ; Syndrom der dysplastischen Nävi ; Xeroderma pigmentosum ; Key words Malignant melanoma ; Genetic instability ; Genetics ; Dysplastic nevus syndrome ; Xeroderma pigmentosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Exposure of the skin to ultraviolet irradiation is an important risk factor for the development of malignant melanoma, with UVA possibly playing an important role. Hereditary factors are also relevant. In the dysplastic nevus syndrome a genetic instability has been shown by different methods. In xeroderma pigmentosum the DNA repair defect is thought to be responsible for the high incidence of malignant melanoma. Frequent and non-random changes in certain chromosomes have been demonstrated in melanoma cells. These might contain sequences that control melanoma growth or melanoma suppressor genes. Especially the short arm of chromosome 9 is thought to contain one of these genes. This hypothesis is supported by a genetic linkage analysis in melanoma families and the demonstration of a germ line deletion of the locus 9p21 in a patient with eight primary melanomas. Changes in known tumor suppressor genes and oncogenes have also been reported in melanoma, but no consistent sequence of genetic events is known.
    Notes: Zusammenfassung Die Exposition der Haut mit ultravioletten Strahlen ist ein wichtiger Risikofaktor für die Entwicklung eines malignen Melanoms. Möglicherweise spielt hierbei UVA-A eine besondere Rolle. Daneben sind hereditäre Faktoren von Bedeutung. Während beim Syndrom der dysplastischen Nävi eine genetische Instabilität mit verschiedenen Methoden nachgewiesen wurde, wird bei Xeroderma pigmentosum der DNA-Reparaturdefekt für die hohe Melanominzidenz verantwortlich gemacht. In Melanomzellen sind überzufällig häufig karyotypische Veränderungen in bestimmten Chromosomen gefunden worden. Diese enthalten möglicherweise Melanomwachstumsregulierende Sequenzen oder Melanom-Suppressorgene. Insbesondere der kurze Arm des Chromosoms 9 steht in Verdacht, eines dieser Gene zu enthalten. Diese Hypothese wird auch unterstützt durch eine genetische Kopplungsanalyse an Melanomfamilien und dem Nachweis einer Keimbahndeletion des Lokus 9p21 bei einer Patientin mit 8 primären Melanomen. Veränderungen an bereits bekannten Tumorsuppressorgenen oder Onkogenen sind ebenfalls in Melanomen beschrieben worden, ohne daß jedoch eine konsistente Reihenfolge von genetischen Ereignissen bekannt wäre.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001050050272
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    Myotonic dystrophy in a large Sicilian kinship: a case report (1995)
    Springer
    Child's nervous system 11 (1995), S. 453-455 
    Details
    ISSN: 1433-0350
    Keywords: Myotonic ; Dystrophy ; Muscle disease ; Genetics ; Case report
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A large Sicilian kinship in which myotonic dystrophy (DM) affected spanning four generations is presented. The pedigree clearly illustrates the phenomenon of anticipation, and illustrates that this phenomenon is more marked when transmission occurs through an affected female rather than an affected male. The pedigree is interpreted in light of recent genetic advances in DM. Neurosurgeons and neurologists should consider a diagnosis of DM when asked to evaluate a floppy infant with enlarged lateral ventricles, and should be aware of special features regarding its inheritance pattern.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334964
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    Social deprivation enhances the vulnerability of male Wistar rats to stressor- and amphetamine-induced behavioral sensitization (1995)
    Springer
    Psychopharmacology 117 (1995), S. 116-124 
    Details
    ISSN: 1432-2072
    Keywords: Psychostimulant ; Amphetamine ; Stress ; Long-term sensitization ; Social isolation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of the present study was to assess the influence of experimential factors on the vulnerability of rats to develop amphetamine (AMPH)- and stressor-induced behavioral sensitization. Young male Wistar rats with previous social experience were isolated from their peers for 2 weeks. 1) The effect of this short-lasting social deprivation were: a) a reduced tendency to explore a fearful environment; b) a prolonged exploratory activity in response to a novel but little fearful environment; and c) a dose-dependent increase in the psychomotor stimulation induced by systemic AMPH injection. 2) After repeated AMPH injections (injection every other day for 10 days), isolated rats exhibited behavioral sensitization at lower doses (0.5 and 0.75 mg/kg) than those required for group-housed rats (1 mg/kg). 3) After being submitted to a repeated stressor (3, 7 or 14 footshock sessions, with 2 days between sessions), the isolated rats exhibited a greater increase in the behavioral responsivity to a subsequent AMPH challenge (1 mg/kg) than did the group-housed rats regardless of the number of stress sessions. In conclusion, these results suggest that experiential factors such as privation of contact with peers (social isolation) may make rats more vulnerable to the long-term repercussions of chronic environmental and pharmacological challenges.
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    URL: http://dx.doi.org/10.1007/BF02245106
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    Can the DRL 72s schedule selectively reveal antidepressant drug activity? (1995)
    Springer
    Psychopharmacology 117 (1995), S. 154-161 
    Details
    ISSN: 1432-2072
    Keywords: Antidepressants ; DRL 72s schedule Water reinforcement ; Chlordiazepoxided-Amphetamine ; Haloperidol ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of three antidepressants, desipramine (2.5–20 mg/kg) tranylcypromine (0.63–2.5 mg/kg) mianserin (1.25–10 mg/kg) and three non-antidepressants, chlordiazepoxide (CDP; 1.25–10 mg/kg) haloperidol (0.02–0.16 mg/kg)d-amphetamine (0.31–1.25 mg/kg) were evaluated in rats responding for water reinforcement under a DRL 72s schedule. The antidepressants all produced dose-related decreases in overall response rates, but no significant changes in reinforcement frequency. In contrast, the anxiolytic CDP did increase the number of reinforcers obtained. Haloperidol decreased both reinforcers and responses whilstd-amphetamine stimulated responding, thereby decreasing reinforcement frequency. An analysis of the modes of inter-response times (IRTs) revealed no significant shifts in the peaks of the IRT distributions for most of the drugs tested. Amphetamine, however, (0.31 and 0.63 mg/kg) decreased the modal values in correspondence with the shift to the left of the peak of responding caused by this compound. These results are discussed in the context of the use of the DRL 72s procedure as a screening test for antidepressant drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245181
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  • 135
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    Strain differences in the rewarding and dopamine-releasing effects of morphine in rats (1995)
    Springer
    Psychopharmacology 117 (1995), S. 240-247 
    Details
    ISSN: 1432-2072
    Keywords: Microdialysis Conditioned place preference ; Morphine Locomotor activity ; Genetic differences ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Studies examining differential sensitivity to psychoactive drugs in mice suggest that genotype may play a critical role. Furthermore, an involvement of genotype in mediating individual differences in sensitivity to the rewarding effects of several drugs of abuse has also been postulated. The aim of this study was to examine the conditioned rewarding and dopamine-releasing effects of morphine in two outbred rat strains commonly used in addiction research. Additionally, the behavioural and neuroendocrine responses of these strains to the stress of novelty were also examined. Basal locomotor activity was higher in Wistar rats than Sprague-Dawley following exposure to a novel environment. In contrast, elevations in plasma corticosteroid levels following novelty exposure did not differ between the two strains. In a counterbalanced place preference conditioning procedure, increasing doses of morphine (1.0–10.0 mg/kg SC) produced significant conditioned place preferences (CPP) in both Wistar and Sprague-Dawley strains. However, Wistar rats required a significantly larger dose of morphine (5.0 mg/kg) to produce a significant CPP than the Sprague-Dawley rats. In the latter strain, CPP occurred with doses of 3.0 mg/kg and greater. In parallel microdialysis experiments, both strains showed significant dose-related increases in dopamine release in the nucleus accumbens following acute morphine challenge (1.0–10.0 mg/kg SC). Again in Wistar rats, a larger dose of morphine was necessary to produce a significant increase in comparison to Sprague-Dawley rats. These results show that genetically distinct rat strains can show differential sensitivity to opioids, more specifically to drug-seeking responses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245193
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    Chronic treatment with fluvoxamine by osmotic minipumps fails to induce persistent functional changes in central 5-HT1A and 5-HT1B receptors, as measured by in vivo microdialysis in dorsal hippocampus of conscious rats (1995)
    Springer
    Psychopharmacology 117 (1995), S. 358-363 
    Details
    ISSN: 1432-2072
    Keywords: Microdialysis ; Dorsal hippocampus 5-HT1A and 5-HT1B receptors ; Chronic treatment Fluvoxamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study investigated the alterations of the 5-HT1A and 5-HT1B autoreceptor function following chronic treatment with fluvoxamine using osmotic minipumps. The 5-HT1A and 5-HT1B autoreceptor function were studied using microdialysis in the dorsal hippocampus. The effect of the 5-HT1A receptor agonist 8-OH-DPAT (0.3 mg/kg, SC) and the 5-HT1B receptor agonist RU-24969 (100 nM through the dialysis probe for 30 min) on 5-HT release was compared with rats chronically treated with saline. 8-OH-DPAT decreased 5-HT release to 55% and 60% of baseline, while RU-24969 decreased 5-HT release to 66% and 70% of baseline value in the saline and fluvoxamine group, respectively. In both cases, differences between the saline and fluvoxamine groups were not statistically significant. Plasma levels of fluvoxamine after 21 days of treatment ranged from 3 to 5 ng/ml. Fluvoxamine concentration in rat brain during treatment was estimated between 100 and 200 nM, which approximates to the IC50 value of fluvoxamine on the 5-HT transporter in synaptosomes and is 50 times higher than the Kd value for the 5-HT reuptake site. In conclusion, no evidence was found for changes in 5-HT1A,B receptor function using 8-OH-DPAT and RU-24969 as probes after continuous treatment with fluvoxamine by means of osmotic minipumps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246110
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    Dissociation between cognitive and motor/motivational deficits in the delayed matching to position test: effects of scopolamine, 8-OH-DPAT and EAA antagonists (1995)
    Springer
    Psychopharmacology 122 (1995), S. 268-280 
    Details
    ISSN: 1432-2072
    Keywords: Operant delayed matching task ; MK-801 ; CGS 19755 ; Scopolamine ; 8-OH-DPAT ; Cognition ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of the muscarinic antagonists scopolamine HBr and MeBr, the 5-HT1A agonst 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), and theN-methyl-d-aspartate (NMDA) antagonists MK-801 and CGS-19755 on performance of rats in a delayed matching-to-position task were examined. Pretreatment with scopolamine HBr (0.05 and 0.1 mg/kg), resulted in a delay-dependent decrease in the percentage of correct responses and discriminability (logd), but had no effect on either the latency to complete trials, or the rate of trial completion during the fixed duration session. Scopolamine MeBr (0.1 mg/kg) did not impair percent correct or increase the response latency but did decrease the rate of trial completion. 8-OH-DPAT (up to 0.3 mg/kg), had no effect on percent correct, but did induce a small decrease in discriminability. The impairment in discriminability occurred only at a dose that substantially reduced the rate of trial completion. Both MK-801 (0.05 mg/kg) and CGS 19755 (10 mg/kg) induced a delay-independent impairment in percent correct, discriminability and a reduction in the rate of trial completion without affecting latency. A lower dose of CGS 19755 (5.0 mg/kg) induced a slight impairment in discriminability without significantly affecting the other measures. Taken together, these results demonstrate some dissocation between drug-induced cognitive and motor/motivational deficits in the DMTP test. However, the data question the specificity of putative cognitive impairments reported in many previous studies with the 5-HT1A agonist 8-OH-DPAT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246548
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    Effects of morphine on different aspects of social play in juvenile rats (1995)
    Springer
    Psychopharmacology 117 (1995), S. 225-231 
    Details
    ISSN: 1432-2072
    Keywords: Social play ; Opioid ; Morphine Environment ; Social isolation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To clarify the influence of opioids on social play, the effects of morphine on playful and non-playful social behavior in juvenile rats was investigated under different conditions. Environmental variables employed were different (dim and intense) levels of illumination during testing, familiarity to the test cage, and different periods of social isolation prior to testing. Under dim light conditions, morphine markedly increased playful social behavior, such as pinning, boxing/wrestling and following/chasing, whereas non-playful social behavior such as social exploration and contact behavior was hardly affected. This effect of morphine was independent of duration of previous isolation and dose-dependent, with a maximal effect at 1.0 mg/kg. The mechanism of this effect is interpreted as an action on the rewarding aspects of play. A dose of 0.1 mg/kg of morphine abolished the initial suppression of play induced by unfamiliarity to the test cage, without influencing total levels of play. This may be an effect of morphine on the integration of sensory stimuli. Under intense light conditions, where playful behavior was completely suppressed, morphine itself hardly affected such behavior, but decreased some aspects of non-playful social behavior. These results suggest that in juvenile rats playful and non-playful forms of social behavior are differentially regulated. In addition, opioid systems may be involved at different levels in the regulation of social play.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245191
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    The ambivalent behaviour “stretched approach posture” in the rat as a paradigm to characterize anxiolytic drugs (1995)
    Springer
    Psychopharmacology 121 (1995), S. 81-90 
    Details
    ISSN: 1432-2072
    Keywords: Stretched approach posture ; Ambivalent behaviour ; Intention movements ; Ethological observation ; Rat ; Anxiety disorders ; Benzodiazepines ; 5-HT1A receptor agonists ; 5-HT uptake inhibitors ; Clonidine ; Clorgyline ; Anxiogenic drugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of various psychotropic drugs on the ambivalent behaviour “stretched approach posture” (SAP) in the rat was assessed. SAP was elicited after a mild startle reaction due to physical contact with an electrified prod at one end of a straight runway. Using ethological observation methods, SAP as well as intention movements, prod contact, crossings, rearing, exploration, grooming and immobility were recorded. The benzodiazepine receptor agonists chlordiazepoxide, diazepam and alprazolam, the 5-HT1A receptor agonists flesinoxan and ipsapirone and the 5-HT uptake inhibitor clomipramine selectively (no effect on crossings) reduced SAP. Except for alprazolam, these drugs also reduced intention movements. In addition, chlordiazepoxide and diazepam enhanced prod contact. Reductions of SAP and intentions with concomitant reductions of crossings (nonspecific anti-ambivalent effects) were established for the α2-adrenoceptor agonist clonidine and the MAO inhibitor clorgyline. The 5-HT uptake inhibitor fluvoxamine suppressed intention movements, but not SAP. The mixed 5-HT/NA uptake inhibitor imipramine did not significantly affect SAP or intentions, but reduced crossings. The 5-HT2C/1B receptor agonist m-CPP, the inverse BZD receptor agonists FG 7142 and DMCM, and the α2-adrenoceptor antagonist yohimbine, to all of which putative anxiogenic effects have been ascribed, had no effect on SAP directed towards the prod. m-CPP, however, produced an increase in the stretched posture directed away from the prod (SAwayP). FG 7142 reduced intentions while strongly enhancing immobility (freezing). SAwayP and/or freezing may possibly reflect anxiogenic properties of drugs. The putative anxiogenic drug pentylenetetrazol false positively reduced SAP while increasing exploration. The dopamine-D2 receptor antagonist haloperidol and the catecholamine releaserdl-amphetamine had no effect on ambivalent behaviour. The muscarine receptor antagonist scopolamine reduced SAP and intentions while stimulating crossings. Finally, the 5-HT2C receptor antagonist ritanserine, the CCKA receptor antagonist devazepide, the CCKB receptor antagonist L-365.260 and the strychnine-insensitive glycine site antagonist 7-Cl-kynurenic acid were without effect on the behaviours in this paradigm using single doses. In conclusion, SAP and intention movements were reduced selectively by anxiolytic agents from different classes, including benzodiazepine receptor agonists, 5-HT1A receptor agonists and a 5-HT uptake inhibitor, whereas an α2-adrenoceptor agonist and a MAO inhibitor reduced SAP non-selectively. SAP in relation to other behaviours may therefore serve as a valuable paradigm to characterize anxiolytic drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245594
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    Effects of benzodiazepine receptor partial inverse agonists in the elevated plus maze test of anxiety in the rat (1995)
    Springer
    Psychopharmacology 121 (1995), S. 118-126 
    Details
    ISSN: 1432-2072
    Keywords: Anxiety ; Plus maze ; Rat ; Benzodiazepine receptor ; DMCM ; FG 7142 ; Yohimbine ; Pentylenetetrazol ; β-Carboline ; Inverse agonist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The present series of experiments examined the effects of five benzodiazepine receptor (BZR) partial inverse agonists on the behaviour of rats on an elevated plus maze. The drugs were tested in a standard plus maze with 3-cm walls added to the open arms, as this has been shown to increase the sensitivity of the plus maze to anxiogenic-like drug effects (Jones and Cole 1995). The drugs tested were FG 7142 (0–100 mg/kg),β-CCE (0–30 mg/kg), ZK 132 556 (0–100 mg/kg), ZK 90 886 (0–30 mg/kg) and Ro 15–4513 (0–30 mg/kg). In addition, to allow a comparison with previous studies, the effects of three reference substances, DMCM (0–2.5 mg/kg), pentylenetetrazol (PTZ; 0–30 mg/kg) and yohimbine (0–5 mg/kg), were also examined. These three reference compounds produced a dose-dependent reduction in the duration of open arm exploration and the total number of open arm entries, indicative of anxiogenic-like effects. DMCM produced significant effects at the doses of 1.25 and 2.5 mg/kg, PTZ at 30 mg/kg, and yohimbine at 5 mg/kg. The BZR partial inverse agonist FG 7142 (10, 30 and 100 mg/kg) also reduced the duration of open arm exploration and the total number of arm entries. The minimally effective dose resulted in a receptor occupancy of approximately 80%. Ro 15–4513 also produced anxiogenic-like effects, but only at a dose (30 mg/kg) that resulted in a receptor occupancy of approximately 95%. In contrast, the other BZR partial inverse agonists, ZK 132 553 and ZK 90 886, did not significantly reduce the duration of open arm exploration, even at doses that produced greater than 95% receptor occupancies.β-CCE also did not reduce open arm exploration at any dose tested (0–30 mg/kg). The GABA shift, a biochemical index of intrinsic activity, indicates that these latter three compounds are more inverse agonistic than Ro 15–4513. In summary, these results demonstrate that not all BZR receptor partial inverse agonists have anxiogenic-like activity in the rat plus maze, and that the GABA shift, a biochemical index of intrinsic efficacy, does not predict which BZR partial inverse agonists are anxiogenic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245598
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    Failure of CCK receptor ligands to modify anxiety-related behavioural suppression in an operant conflict paradigm in rats (1995)
    Springer
    Psychopharmacology 121 (1995), S. 127-134 
    Details
    ISSN: 1432-2072
    Keywords: Anxiety ; Cholecystokinin ; CCK-A and CCK-B receptor antagonists ; CCK-B receptor agonists ; Behavioural suppression ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of cholecystokinin (CCK) receptor ligands were studied in the rat safety signal withdrawal conflict procedure, an operant paradigm sensitive to both anxiolytic and anxiogenic compounds. In this procedure, behavioural suppression of lever pressing for food was induced by the withdrawal of a conditioned signal for safety without the usual presentation of a conditioned signal for danger. The compounds tested were selective CCK-B antagonists [CI-988 (0.01–1 mg/kg SC), L-365,260 (0.004–2 mg/kg IP) and LY 262,691 (0.001–1 mg/kg SC)], CCK-B agonists [CCK-4 (0.01–1 mg/kg SC) and BC 264 (0.004–1 mg/kg IP)] and CCK-A antagonists [devazepide (0.001–1 mg/kg SC) and lorglumide (0.01–1 mg/kg SC)]. None of these drugs induced the expected behavioural effects, i.e. an anxiolytic-like release of the behavioural suppression with CCK-B and, possibly, CCK-A antagonists and/or a further reduction of lever pressing with CCK-B agonists, indicative of an anxiogenic-like potential. In contrast, the established anxiolytic lorazepam (0.06–0.25 mg/kg IP), as well as diazepam (2 mg/kg IP) and buspirone (0.25 mg/kg SC) used as positive control drugs, released the suppression of pressing for food during the period associated with the safety signal withdrawal, whereas picrotoxin (1 mg/kg IP), used as an anxiogenic control, further reduced responding during this conflict period. The present results contrast with a series of published data suggesting the involvement of CCK processes in anxiety-related behaviour in rodent models such as the elevated plus-maze or the light:dark two compartment test, and in panic disorders in humans. They indicate that the behavioural effects of one category of drugs might vary considerably, depending on the experimental situation. Furthermore, they allow the conclusion that anticipatory anxiety generated by withdrawal of conditioned signals for safety does not involve CCK-related processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245599
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    Scopolamine prevents augmentation of stereotypy induced by chronic methamphetamine treatment (1995)
    Springer
    Psychopharmacology 121 (1995), S. 158-163 
    Details
    ISSN: 1432-2072
    Keywords: Methamphetamine ; Behavioral sensitization ; Scopolamine ; Acetylcholine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cholinergic neurotransmission has been implicated in various forms of neural plasticity such as kindling and learning. We have previously shown that blockade of muscarinic cholinergic receptors prevents the development of locomotor sensitization to methamphetamine. The present study was conducted to examine whether scopolamine, a muscarinic cholinergic antagonist, would also block augmentation of stereotypy induced by chronic methamphetamine (MA) treatment. Rats treated with MA (2.5 mg/kg, SC) for 10 days indicated significantly enhanced stereotyped behavior when tested with MA (2.5 mg/kg) after a 7-to 8- day withdrawal. Pretreatment with scopolamine (3 mg/kg) prior to MA administration prevented the augmentation of stereotypy. Rats treated with scopolamine alone showed no difference in MA-induced stereotypy compared to those treated with saline. Scopolamine methylbromide, a derivative of scopolamine that does not easily cross the blood-brain barrier, had no effect on the augmentation of stereotypy. These results suggest that stimulation of central muscarinic cholinergic receptors plays a role in the development of sensitization to the stereotypy stimulating effect of methamphetamine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245625
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    Inhibitory mechanisms in epileptiform activity induced by low magnesium (1995)
    Springer
    Pflügers Archiv 430 (1995), S. 238-245 
    Details
    ISSN: 1432-2013
    Keywords: Epilepsy ; Epileptiform activity ; Mg2+-free media ; Low magnesium ACSF ; PDS afterpotentials ; Inhibition ; Hippocampus ; Rat ; GABA ; Ca2+-dependent K+ current
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In rat hippocampal slices epileptiform activity was induced by superfusion with Mg2+-free artificial cerebrospinal fluid (ACSF). Paroxysmal depolarization shifts (PDS) were evoked by electrical stimulation of Schaffer collaterals. To investigate the afterpotentials that follow PDS, intracellular recordings were made from CA1 pyramidal cells. The experiments revealed that several components are engaged in the generation of PDS afterpotentials in Mg2+-free ACSF. A long lasting component which determined the overall duration of the PDS afterhyperpolarization was blocked by intracellular application of ethylenebis(oxonitrilo)-tetraacetate (EGTA); concomitantly, the afterhyperpolarizations following depolarizing current injections were blocked. This indicated that the long lasting component was due to a slow Ca2+-activated K+ current. The block of Ca2+-activated K+ current uncovered a depolarizing PDS afterpotential with an N-shaped voltage dependence, suggesting that this depolarizing afterpotential component may be due to an N-methyl d-aspartate (NMDA) conductance. Intracellular injection of Cl− revealed that the PDS were followed by Cl− currents lasting about 500 ms. This component could be blocked by application of bicuculline suggesting that it is due to a synaptically GABA-mediated (i.e. γ-aminobutyric acid) Cl− current. A comparison of PDS afterpotentials in Mg2+-free ACSF and those in other models of epileptiform activity suggests that similar sequences of inhibitory components are activated in spite of different pharmacological alterations of membrane conductances which induce the epileptiform discharges.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00374655
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    Diffusion of myoglobin in skeletal muscle cells — dependence on fibre type, contraction and temperature (1995)
    Springer
    Pflügers Archiv 430 (1995), S. 519-525 
    Details
    ISSN: 1432-2013
    Keywords: Diffusion coefficient ; Muscle cells ; Myoglobin ; Microinjection ; Oxygen ; Facilitated diffusion ; Intracellular oxygen transport ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We measured the diffusion coefficient of myoglobin (D Mb) inside mammalian skeletal muscle cells with a microinjection technique. A small bolus of horse Mb was injected into a single muscle fibre and the subsequent time-dependent changes of the Mb profiles along the fibre axis were measured with a microscope-photometer. For fibres of the rat soleus muscle at 22° C, a D Mb of 1.3·10−7 cm2/s was found, confirming a result obtained previously by us for rat diaphragm muscle with a photo-oxidation technique. In the extensor digitorum longus muscle of the rat, a higher value of 1.9 · 10−7 cm2/s was measured. Auxotonic muscle contractions did not change the apparent D Mb. For the temperature range between 22 ° C and 37 ° C, a temperature coefficient, Q 10, of 1.5 was calculated. The implication of this result for the role of Mb in the facilitation of oxygen transport was examined. Model calculations show that with this relatively low D Mb value, the intracellular oxygen supply can be improved only slightly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00373888
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    Involvement of intracellular calcium ions in the release of the fluorescent dye calcein by cholinergic and α-adrenergic agonists from rat parotid acinar cells (1995)
    Springer
    Pflügers Archiv 429 (1995), S. 555-560 
    Details
    ISSN: 1432-2013
    Keywords: Rat ; Parotid glands ; Salivary glands ; Calcein ; Amylase ; Secretion ; Carbachol ; Noradrenalin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Effects of cholinergic and adrenergic agonists on the secretion of the fluorescent dye calcein were examined to clarify the involvement of calcium ions in the secretion of calcein from acinar cells dispersed from the rat parotid gland. Addition of carbachol (CCh) and noradrenalin (NA), but not isoproterenol (IPR), enhanced the net release of calcein from acinar cells during the subsequent 10 min in a dose range from 10−8 M to 10−6 M. The net release of calcein reached a maximum 7 min after the addition of CCh. The release of calcein was suppressed by the simultaneous additions of atropine with CCh, or phenoxybenzamine with NA. Addition of CCh induced a sustained dosedependent increase in the intracellular levels of calcium ions, ([Ca2+]i). Addition of NA at 10−6 M increased [Ca2+]i. Phenoxybenzamine completely inhibited the NA-induced increase, but propranolol did not. The removal of extracellular calcium ions did not influence the release of calcein induced by 10−6 M CCh, but it abolished the sustained increase in [Ca2+]i. The transient increase in [Ca2+]i induced by CCh was observed in the absence of extracellular calcium ions. A calcium ion chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid (BAPTA) inhibited the CCh-induced release of calcein. The calcium ionophore, A23187 (2.5×10−6 M), but not 10−3 M dibutyryl cAMP, evoked the release of calcein. It also increased [Ca2+]i. Removal of extracellular calcium ions suppressed the A23187-induced release of calcein. These results suggest that the release of calcein from parotid acinar cells is transiently induced through an increase in [Ca2+]i by muscarinic and α-adrenergic agonists and may represent the initial process of salivary secretion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00704161
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    Promotion of sleep by heat in young rats (1995)
    Springer
    Pflügers Archiv 430 (1995), S. 729-738 
    Details
    ISSN: 1432-2013
    Keywords: Sleep ; Thermoregulation ; Slow wave activity ; Sleep drive ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of the experiments was to study the effects of a moderate heat load on sleep in young (26-day-old) rats and to determine whether the sleep-promoting effect of heat results from stimulation of the homeostatic sleep process. The changes in sleep-wake activity, electroencephalogram slow wave activity (SWA) during non-rapid eye movement sleep (NREMS) and cortical temperature (T crt) were determined during and after long (24-h) and short (2.5-h) heat loads (elevation of ambient temperature from 26° C to 32° C), and after total sleep deprivation (SD) combined with a short-term heat load. The heat exposures elicited increases in T crt and rectal temperature (2 and 1.7° C respectively). The long-term heat load induced persistent, albeit slight enhancements in NREMS. Rapid eye movement sleep (REMS) increased with a 12-h delay during the 24-h heat load. Heat elicited an immediate large increase in SWA. After this initial increase, SWA declined and tended to fall below the baseline level during the last 12 h of the 24-h heat load. SWA and REMS were significantly suppressed after termination of 24-h heat loading. The increased SWA during the short-term heat load was not followed by subsequent alterations in sleep when the ambient temperature had returned to normal. However, after the combination of SD with the shortterm heat load the durations of NREMS and SWA were significantly enhanced compared with those found after SD at 26° C. The results are interpreted as suggesting that heat increases NREMS in the young rat by the same mechanism as is involved in the enhancement of NREMS after SD: a stimulation of sleep drive.
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    URL: http://dx.doi.org/10.1007/BF00386168
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    Effects of hypobaric hypoxia on histochemical fibre-type composition and myosin heavy chain isoform component in the rat soleus muscle (1995)
    Springer
    Pflügers Archiv 429 (1995), S. 601-606 
    Details
    ISSN: 1432-2013
    Keywords: Hypobaric hypoxia ; Histochemistry ; Muscle fibre-type ; Electrophoresis ; Myosin heavy chain isoform ; Soleus muscle ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Histochemical fibre-type composition and myosin heavy chain isoform component in the soleus muscle were studied in normoxic rats at postnatal ages of 5, 10, 15, and 20 weeks and in rats exposed to hypobaric hypoxia (460 torr) for 5 weeks from postnatal ages of 5, 10, and 15 weeks. The increase in the percentage of type I fibres and the concomitant decrease in that of type IIa fibres in the soleus muscle of normoxic rats were observed until 15 weeks of age. On the other hand, no change in the fibre-type composition of the muscle during postnatal development was observed in hypoxic rats, irrespective of the age at which they were exposed to hypoxia. The changes in the myosin heavy chain isoform component (MHC I and MHC IIa) of the muscle during postnatal development and by hypoxia corresponded well with those in the muscle fibre-type composition. It is concluded that hypobaric hypoxia inhibits the growth-related shift of muscle fibre-types from type IIa to type I and of myosin heavy chain isoforms from MHC IIa to MHC I in the rat soleus muscle, and that there are no changes in the muscle fibre-type composition or the myosin heavy chain isoform component caused by hypoxia after the shifts in these parameters which occur during postnatal development are completed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00373980
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  • 148
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    Developmental variation of the permeability to Ca2+ of AMPA receptors in presumed hilar glial precursor cells (1995)
    Springer
    Pflügers Archiv 431 (1995), S. 244-252 
    Details
    ISSN: 1432-2013
    Keywords: Rat ; Hippocampus ; Hilus ; Glutamate ; Kainate ; Patch-clamp in situ
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Glial cells in the hilus of the dentate gyrus of the rat were investigated using the patch-clamp technique in acute slices of the hippocampal formation. According to their voltage-gated current patterns, two classes of glial cells — putative astrocytes and presumed glial precursor cells — were apparent. The glutamate receptor agonists kainate, glutamate, and α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) evoked inward currents at a holding potential of −70 mV in astrocytes and presumed glial precursor cells. Inward currents could also be induced in nucleated patches, indicating a direct action on glial receptors. In presumed hilar glial precursor cells, 6,7-dinitroquinoxaline-2,3-dione (DNQX; 10 μM) blocked the kainate-induced current, while it was partially inhibited by Zn2+ (2 mM) and Evans Blue (10 μM). Cyclothiazide (100 μM), in contrast, potentiated this current, indicating the presence of AMPA receptors. In 90% of the presumed glial precursor cells the excitatory amino-acid-evoked current voltage (I/V) relations were linear or outwardly rectifying and reversed close to 0 mV, which is characteristic for non-specific cation channels. To determine the permeability to Ca2+, I/V relations were determined in a Na+-free solution containing 40 mM Ca2+ and showed reversal potentials of a wide variation ranging from −63 mV to + 1 mV with corresponding P Ca/ P Cs permeability ratios of between 0.09 and 2.10. Statistical analysis revealed that the permeability to Ca2+ significantly decreased with an advance in age (r=−0.596; n=21; P〈0.01). These data suggest that the Ca2+ influx mediated by the activation of AMPA receptors expressed in presumed hilar glial precursor cells is dependent on the developmental stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410197
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  • 149
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    Psychopharmacological studies in rats responding at touch-sensitive devices (1995)
    Springer
    Psychopharmacology 118 (1995), S. 226-229 
    Details
    ISSN: 1432-2072
    Keywords: Touch-sensitive device ; Visual attention ; Cognition ; Amphetamine ; Serotonin ; 5-HT ; Acetylcholine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A multiple choice serial reaction time task was used to investigate visual attention in rats. The intelligence panel consisted of a transparent touch-sensitive device, placed directly in front of a video monitor. Amphetamine (0.2–1.6 mg/kg IP) increased errors of omission and decreased latency to respond, but had no effect on accuracy. The 5-HT agonist quipazine (0.6–2.4 mg/kg IP) increased errors of omission, but did not affect other parameters. ICV administration of hemicholinium-3 (1–4 µg) had no effect upon performance. Thus, psychopharmacological manipulations can reliably alter performance in the touch window box, suggesting potential new avenues for rat cognitive testing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245846
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  • 150
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    Sulpiride antagonizes the biphasic locomotor effects of quinpirole in weanling rats (1995)
    Springer
    Psychopharmacology 119 (1995), S. 299-304 
    Details
    ISSN: 1432-2072
    Keywords: Dopamine ; Autoreceptor ; Sulpiride ; Quinpirole ; Locomotion ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Low doses of dopamine (DA) agonists such as the D2 receptor subfamily agonist quinpirole are thought to stimulate DA autoreceptors selectively, thereby inhibiting locomotor activity. High doses of quinpirole initially suppress and later activate locomotion during a single test session; the activation is presumably due to stimulation of postsynaptic receptors. The aim of this study was to investigate whether pretreatment with a selective DA D2 receptor antagonist, sulpiride, could block the putative autoreceptor-mediated inhibition at a lower dose than was required to block the postsynaptically mediated activation. Male and female 30-day-old rats were injected SC with one of eight doses of sulpiride (0.313–40 mg/kg) or the vehicle. Sixty minutes later, rats were injected SC with 0.2 mg/kg quinpirole or the vehicle. Five minutes after the second injection, rats were placed in automated activity monitors which recorded locomotor behavior for 60 min at 5-min intervals. Quinpirole at this dose first suppressed and later increased locomotor activity. Sulpiride pretreatment dose-dependently reversed both the early inhibition and later activation of quinpirole-induced locomotion. However, sulpiride did not block the quinpirole-induced early suppression at a lower dose than was required to block the later activation. Thus, there was no evidence that the locomotor suppression elicited by quinpirole is mediated by a more sensitive subset of DA receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246295
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  • 151
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    Phencyclidine injections into the dorsal hippocampus disrupt long- but not short-term memory within a spatial learning task (1995)
    Springer
    Psychopharmacology 120 (1995), S. 203-208 
    Details
    ISSN: 1432-2072
    Keywords: Phencyclidine ; Dorsal hippocampus ; Rat ; Spatial navigation task
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Since the hippocampus is likely to be a major site of phencyclidine (PCP) action, the effects of various doses of PCP (1.8, 18 or 36 nM) as well as 3.6 nM MK-801 or saline injected directly into the dentate gyrus of the hippocampus was tested for acquisition of a spatial navigation task (dry land version of a water maze) using a paradigm that assesses short term memory based on learning within a day and long term memory based on learning between days. Results indicated that relative to saline or 1.8 nM PCP injected rats, rats with 18 or 36 nM PCP or 3.6 nM MK-801 injections were impaired in acquisition of the task as measured by increased distances traveled to find the food location between days but not within days. In additional experiments 36 nM PCP or 3.6 nM MK-801 did not produce any deficits in the acquisition of an object discrimination task. It is suggested that PCP through its blocking action of the NMDA receptor in the dentate gyrus or CA1 region of the dorsal hippocampus mediates the consolidation of new spatial location information.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246194
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  • 152
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    Acute and subchronic effects of clozapine on licking in rats: tolerance to disruptive effects on number of licks, but no tolerance to rhythm slowing (1995)
    Springer
    Psychopharmacology 120 (1995), S. 249-255 
    Details
    ISSN: 1432-2072
    Keywords: Clozapine ; Ritanserin ; Atypical neuroleptic ; Lick rhythm ; Oscillator slowing ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to assess the effects of the atypical neuroleptic clozapine on orolingual competence in rats, tongue function was measured by quantitating the rhythm of tongue movements after acute (1.0, 3.0, 6.0 mg/kg) or subchronic intraperitoneal treatment (1.5, 3.0, 4.5 mg/kg, each dose for at least 7 days) with the drug. Thirsty rats were trained to lick water from a force-sensing disk by thrusting the tongue through a 12-mm-diameter hole to strike the horizontal disk located 5 mm below the hole. Number of licks in 2 min and rhythm of tongue movements (as determined by Fourier analysis of the force-time signal) were each dose dependently reduced in the acute dose-effect phase of the study. In the subchronic study number of licks exhibited tolerance, but the slowing of lick rhythm did not show tolerance. An acute dose range of the serotonin antagonist ritanserin (0.5, 1.0, 2.0, 4.0 mg/kg) was also studied in the same rats. Ritanserin had no effect on any of the measures of orolingual function. The clozapine result was replicated in a second study using younger, drug naive rats. The results for clozapine were contrasted with previous reports indicating that haloperidol has little effect on lick rhythm. Additional discussion evaluated the possible contribution of neurotransmitter receptors on motor neurons of the hypoglossal nucleus to the observed rhythm slowing induced by clozapine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311171
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  • 153
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    The competitive NMDA antagonists CGP 43487 and APV potentiate dopaminergic function (1995)
    Springer
    Psychopharmacology 118 (1995), S. 310-315 
    Details
    ISSN: 1432-2072
    Keywords: MK-801 ; APV and CGP 43487 ; Apomorphine-induced behavior ; Motor activity ; Rota-rod test ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The administration to rats of different doses of the non competitive NMDA receptor blocker MK-801 (0.03–1 mg/kg IP) induced stimulation or reduction of locomotor activity, depending on the dose, whereas the competitive NMDA antagonists CGP 43487 (0.188–6 mg/kg IP) and APV (2.5–20 μg/rat ICV) inhibited locomotion at the highest doses. Unlike MK-801 and APV treatment, the administration of CGP 43487 did not induce impairment of rota-rod test performance. Both competitive and non-competitive NMDA antagonists, at doses devoid of any behavioral effect per se, potentiated the responses elicited by apomorphine (0.25 mg/kg SC). In particular, the occurrence of episodes of licking was weakly affected by MK-801 administration, but significantly increased by CGP 43487 and APV treatment; the presence of gnawing was augmented by all the pretreatments; sniffing, locomotion, grooming and rearing occurrence were not affected by the administration of NMDA antagonists. The results suggest that the competitive antagonists which facilitated dopaminergic function without causing motor impairment could be useful supplements in the treatment of Parkinson's disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245960
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  • 154
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    Retarded acquisition of a temporal discrimination following destruction of noradrenergic neurones by systemic treatment with DSP4 (1995)
    Springer
    Psychopharmacology 118 (1995), S. 332-337 
    Details
    ISSN: 1432-2072
    Keywords: Noradrenaline ; DSP4 ; Operant behaviour Timing ; Interval bisection procedure ; Acquisition ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This experiment examined the effect of destroying central noradrenergic neurones, using the selective neurotoxin DSP4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine) on the acquisition and performance of discrimination between two time intervals. Rats that had received systemic treatment with DSP4 and vehicle-treated control rats were trained in a series of discrete trials to press lever A following a 2-s presentation of a light stimulus and lever B following an 8-s presentation of the same stimulus. Both groups acquired the discrimination (〉90% correct choices) within 15 sessions; however, the DSP4-treated group showed significantly slower acquisition than the control group. When stable performance had been attained, ‘probe’ trials were introduced in which the light was presented for intermediate durations. Both groups showed sigmoid functions relating percent choice of lever B to log stimulus duration. Neither the bisection point (duration corresponding to 50% choice of lever B) nor the Weber fraction differed significantly between the DSP4-treated and control groups. The levels of noradrenaline were markedly reduced in the neocortex and hippocampus of the DSP4-treated group, but the levels of dopamine and 5-hydroxytryptamine were not altered. The results indicate that noradrenaline depletion induced by DSP4 retarded the acquisition of temporal discrimination, but did not impair steady-state discriminative precision.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245963
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  • 155
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    Behavioural consequences of maternal exposure to natural cannabinoids in rats (1995)
    Springer
    Psychopharmacology 122 (1995), S. 1-14 
    Details
    ISSN: 1432-2072
    Keywords: Rat ; Development ; Behavior ; Cannabis ; Delta-9-tetrahydrocannabinol ; Motor activity ; Place preference ; Grooming ; Corticosterone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cannabis sativa preparations (hashish, marijuana) are the most widely used illicit drugs during pregnancy in Western countries. The possible long-term consequences for the child of in utero exposure to cannabis derivatives are still poorly understood. Animal models of perinatal cannabinoid exposure provide a useful tool for examining the developmental effects of cannabinoids. Behavioral consequences of maternal exposure to either cannabis preparations or to its main psychoactive component, Δ9-tetrahydrocannabinol (THC) in rat models are reviewed in this paper. Maternal exposure to cannabinoids resulted in alteration in the pattern of ontogeny of spontaneous locomotor and exploratory behavior in the offspring. Adult animals exposed during gestational and lactational periods exhibited persistent alterations in the behavioral response to novelty, social interactions, sexual orientation and sexual behavior. They also showed a lack of habituation and reactivity to different illumination conditions. Adult offspring of both sexes also displayed a characteristic increase in spontaneous and water-induced grooming behavior. Some of the effects were dependent on the sex of the animals being studied, and the dose of cannabinoid administered to the mother during gestational and lactational periods. Maternal exposure to low doses of THC sensitized the adult offspring of both sexes to the reinforcing effects of morphine, as measured in a conditioned place preference paradigm. The existence of sexual dimorphisms on the developmental effects of cannabinoids, the role of sex steroids, glucocorticoids, and pituitary hormones, the possible participation of cortical projecting monoaminergic systems, and the mediation of the recently described cannabinoid receptors are also analyzed. The information obtained in animal studies is compared to the few data available on the long-term behavioral and cognitive effects on in utero exposure to cannabis in humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246436
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  • 156
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    Examination of drug-induced and isolation-induced disruptions of prepulse inhibition as models to screen antipsychotic drugs (1995)
    Springer
    Psychopharmacology 122 (1995), S. 15-26 
    Details
    ISSN: 1432-2072
    Keywords: Prepulse inhibition ; Schizophrenia ; Dopamine ; Serotonin ; Glutamate ; Social isolation ; Clozapine ; Raclopride ; Haloperidol ; Rirsperidone ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Prepulse inhibition (PPI) of an acoustic startle response is impaired in schizophrenics. PPI can also be studied in the rat, and is impaired by dopamine (DA) D2/3 receptor agonists such as apomorphine. This disruption is reversed by DA antagonists, leading to proposals that this approach may be a useful means to identify novel antipsychotics. There is also evidence to suggest a role of serotonergic (5-HT) and glutamatergic systems in schizophrenia, and accordingly PPI can be disrupted by the 5-HT2 agonist DOI, and the non-competitive NMDA antagonist, dizocilpine. In the present study we have examined the effect of four antipsychotic drugs, haloperidol (0.1–0.3 mg/kg), raclopride (0.03–0.3 mg/kg), risperidone (0.3–3 mg/kg) and clozapine (0.0001–10 mg/kg), against the PPI disruptions induced by apomorphine (0.5 mg/kg), DOI (3 mg/kg) and dizocilpine (0.15 mg/kg). Furthermore, these drugs have been examined for their ability to restore a PPI deficit produced by housing rats under conditions of social isolation. All drugs except clozapine reversed an apomorphine-induced disruption. However, clozapine and risperidone, but not raclopride and haloperidol, reversed a DOI-induced disruption. Only risperidone was effective in restoring a PPI deficit produced by dizocilpine. In contrast to the drug-induced disruptions which were differentially sensitive to the various neuroleptics, isolation-induced disruptions were restored by each drug. These results support the idea that non-drug induced disruptions of PPI, such as social isolation, may be a more viable approach to identify novel antipsychotics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246437
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  • 157
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    Characterization of Japanese families with early-onset type 2 (non-insulin dependent) diabetes mellitus and screening for mutations in the glucokinase and mitochondrial tRNALeu(UUR) genes (1995)
    Springer
    Acta diabetologica 32 (1995), S. 17-22 
    Details
    ISSN: 1432-5233
    Keywords: Maturity-onset diabetes of the young (MODY) ; Genetics ; Diabetes mellitus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Genetic linkage studies of families with earlyonset type 2 diabetes have facilitated the identification of diabetes-susceptibility genes. In order to assess the feasibility of using linkage approaches to identify genes responsible for the development of type 2 diabetes in Japanese subjects, we examined our clinical records for multigenerational families suitable for genetic studies. We identified 16 families in which at least one subject was diagnosed with type 2 diabetes before 25 years of age. Seven of these families had a pattern of inheritance consistent with a diagnosis of maturity-onset diabetes of the young (MODY) and nine families showed a complex pattern of inheritance of type 2 diabetes with transmission of diabetes-susceptibility genes from both parents. The glucokinase and mitochondrial tRNALeu(UUR) genes were screened for mutations in at least one affected subject from each family in order to assess the contribution of mutations in these genes to the development of the diabetes. No mutations were found, which suggests that the diabetes in these families resulted from mutations in other genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581039
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  • 158
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    Cell deletion by apoptosis during regression of rat parotid sialadenosis (1995)
    Springer
    Virchows Archiv 427 (1995), S. 181-186 
    Details
    ISSN: 1432-2307
    Keywords: Isoproterenol ; Apoptosis ; Rat ; Parotid ; Sialadenosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Enlargement of the rat parotid salivary glands was induced by repeated administration of isoproterenol. Mean wet weights of the treated glands increased steadily to 240% of control values. Following withdrawal of the drug, quantitative histological techniques were used to investigate the balance between hypertrophy, hyperplasia and apoptosis. The volume occupied by acinar cells relative to the total gland volume together with cytoplasmic|:|nuclear area ratios as measures of hypertrophy increased during the early experimental period. Similarly, serous acinar cell mitotic counts increased, indicating that hyperplasia had occurred. Apoptosis was demonstrated at light microscopical level to be the main mechanism for cell deletion as the glands returned to normal size and weight. The results indicate that hypertrophy and hyperplasia of serous acinar cells contribute to isoproterenol-induced sialadenosis. The experimental animal model demonstrates that these proliferative changes are completed by 48 h and thereafter are balanced by apoptosis as the glands recover their normal size and weight.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196524
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  • 159
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    Domestication via hybridization of the wild tetraploid oats Avena magna and A. murphyi (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 639-646 
    Details
    ISSN: 1432-2242
    Keywords: Gene introgression ; Genetics ; Linkage ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The wild tetraploid (2n=28) oat species Avena magna and A. murphyi have been domesticated by having been transferred from the common oat, A sativa (2n=42), the characteristics of non-shedding spikelets glabrous and yellow lemma, and reduced awn formation. Domestication has been achieved by crossing the common oat with either of the tetraploid species and then backcrossing the pentaploid hybrids with pollen of the tetraploid wild parent. Among the BC plants obtained only a few produced some seeds. Fertile tetraploids exhibiting the domesticated syndrome have been selected for in the F2 generation. Although morphologically they were almost indistinguishable from the common oat, they were tetraploids. Wild x domesticated A. magna hybrids were vigorous and fertile. They retained their spikelets at maturity, lemma color and pubescence were intermediate between the parental lines, and awns were formed only on the lower floret of the spikelet. Each of these characteristics segregated in a 3∶1 fashion, indicating single gene control, as in the common oat. These four characteristics formed a linkage group in one F2 family and two linkage groups in the other two families. The usefulness of the domesticated tetraploids for oat research and production has been discussed. Taxonomically, the domesticated tetraploids were ranked as subspecies: A. magna ssp. domestica, and A. murphyi ssp. rigida.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223291
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  • 160
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    Diallel analysis for mineral element absorption in tropical adapted soybeans [Glycine max (L.) Merrill] (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 707-713 
    Details
    ISSN: 1432-2242
    Keywords: Mineral stress ; Nutrient efficiency ; Aluminium tolerance ; Inheritance ; Genetics ; Breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Brazilian tropical adapted soybeans contains, in addition to superior morphological characters, genetic factors for tolerance to cultivation in acidic, mineral-stressed soils. However, the selection process for these hindrances has been empirical, and information on the genetics of mineral element uptake by the plant is necessary. The objective of this investigation was to identify the mode of inheritance for the absorption of phosphorus, potassium, calcium, magnesium, iron, aluminium, manganese, zinc and copper in a 9 × 9 diallel cross. General combining ability (GCA) was higher than specific combining ability (SCA), with the exception of copper, manganese and zinc, indicating predominantly additive effects. The ratios of GCA/SCA varied between 3.4 (calcium) and 8.5 (magnesium). The regression of covariance (Wr) on variance (Vr) showed that the additive-dominance model explained the genetic differences in this germ plasm. However, the detection of overdominance could be related to possible heterozygosity in the parental varieties for mineral absorption. Broad-sense heritability values were higher than narrow sense heritability values for aluminium, iron, potassium, calcium and magnesium, being in the range of 67.9–86.9% and 42.0–56.6%, respectively. This is an indication that soybeans can be further improved to efficient utilisation of nutrients and to tolerate toxic factors in the soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222137
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  • 161
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    Allelic relationships between genes for resistance to tomato spotted wilt tospovirus in Capsicum chinense (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 146-149 
    Details
    ISSN: 1432-2242
    Keywords: Capsicum chinense ; Resistance gene ; Genetics ; Pepper ; Tomato spotted wilt virus ; Tospoviruses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pepper (Capsicum chinense Jacq.) has been reported to be an important reservoir of resistance genes to tomato spotted wilt virus (TSWV). The genes for TSWV resistance present in three C. chinense lines (‘PI 152225’, ‘PI 159236’ and ‘Panca’) were investigated for allelism. All resistant lines were crossed with each other. Parents, F1, backcrosses and F2 populations (including reciprocals) developed from those crosses were mechanically inoculated with a highly virulent TSWV isolate. Susceptible C. annuum cv ‘Magda’ was used to check inoculum virulence. Fifty plants of the F1 hybrids; ‘Magda’ x ‘PI 152225’, ‘Magda’ x ‘PI 159236’, and ‘Magda’ x 'Panca, were also inoculated with the TSWV isolate. The resistance response in all C. chinense sources was associated with a localized, hypersensitive-like reaction that was phenotypically expressed as a prompt formation of large local lesions accompanied by premature leaf abscission. All F1 generations presented a final score of resistant; indicating that the expression of resistance to TSWV is conditioned by a dominant gene regardless of the source. The absence of segregation for resistance to TSWV that was observed in all generations of the crosses between C. chinense lines indicated that either a tightly linked group of genes exists or that the resistance is governed by the same single major gene (probably the already described Tsw gene). Previous reports have indicated that the Tsw gene is not effective against tospovirus members of serogroup II, i.e. tomato chlorotic spot virus (TCSV) and groundnut ring spot virus (GRSV). In the assay described here, all of the C. chinense lines showed, after mechanical inoculation, an identical susceptibility response to the TCSV and GRSV isolates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221009
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    Identification of genomic regions affecting plant height in sorghum and maize (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 380-388 
    Details
    ISSN: 1432-2242
    Keywords: Genetics ; Breeding ; Sorghum bicolor Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The objective of this study was to use restriction fragment length polymorphisms (RFLPs) to determine the genetic location and effects of genomic regions controlling plant height in sorghum. F2 plants (152) from the cross CK60 x PI229828 were used. Genomic and cDNA clones (106) identified 111 loci distributed among ten linkage groups covering 1299 cM. Interval mapping identified four regions, each in a separate linkage group. These regions may correspond to loci (dw) previously identified by alleles with qualitative effects. Also, these regions identified in sorghum may be orthologous to those previously reported for plant height in maize. Gene effects and gene action varied among genomic regions. In each region, PI229828 alleles resulted in increased plant height. Each region accounted for 9.2–28.7% of the phenotypic variation. Positive, additive effects ranged from 15 to 32cm. Tallness was dominant or overdominant and conferred by alleles from PI229828 for three quantitative trait loci (QTL). At the fourth QTL, PI229828 contributed to increased plant height, but short stature was partially dominant. One digenic interaction was significant. The presence of a PI229828 allele at one region diminished the effects of the other region. A multiple model indicated that these four regions collectively accounted for 63.4% of the total phenotypic variation. The utility of this information for germplasm conversion through backcross breeding is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221980
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  • 163
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    Localization and coexistence of atrial natriuretic peptide (ANP) and neuropeptide Y (NPY) in vertebrate adrenal chromaffin cells immunoreactive to TH, DBH and PNMT (1995)
    Springer
    Cell & tissue research 280 (1995), S. 267-276 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Adrenal organ ; Atrial natriuretic peptide ; Neuropeptide Y ; Catecholamine synthesizing enzymes ; Coexistence ; Rat ; Guinea pig ; Coturnix c. japonica (Aves ; Phasianiformes) ; Lacerta viridis (Lacertilia) ; Bufo marinus ; Caldula pulchra (Anura) ; Cyprinus carpio ; Cottus scorpius (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Antisera specific for mammalian atrial natriuretic peptide (ANP) and neuropeptide Y (NPY) were applied to examine, in immunofluorescence, the occurrence of cells immunoreactive to ANP and NPY in the adrenal organs of mammals, birds, reptiles, amphibians, and bony fish. Catecholamine-containing cells were identified using antisera against tyrosine-hydroxylase, dopamine-β-hydroxylase, and phenylethanolamine-N-methyl-transferase. In all vertebrates studied, immu- noreactivities to ANP and NPY occurred in adrenal chromaffin cells but were absent from the cortex or its homolog, the interrenal. The majority of immunoreactivities to ANP and NPY was confined to the adrenaline cells. In mammals, the number of ANP-immuno-reactive cells (60%–80% of the total cell population) exceeded that of the NPY-immunoreactive cells (35%–45%). In birds, reptiles, and Amphibia, the numbers of ANP-immunoreactive (35%–40%) and NPY-immunoreactive (30%–35%) cells were in a similar range. The bony fish showed a density of both ANP-immunoreactive (80%–90%) and NPY-immunoreactive (35%–40%) cells. In all species studied, immunoreactivities to ANP and NPY partially coexisted. Generally, 30%–55% of the ANP-immunoreactive cells also contained NPY-immunoreactivity. In rat, coexistence amounted to almost 100% and in quail to 95%. Except for the rat, three subpopulations of chromaffin cells seemed to occur: ANP-immunoreactive non-NPY-immunoreactive, ANP-immunoreactive+NPY-immunoreactive, and NPY-immunoreactive non-ANP-immunoreactive cells. Thus, adrenal ANP and NPY share a conservative history and coexist as early as at the level of bony fish. The endocrine actions of ANP and NPY derived from medullary cells on cortical cells as found in mammals might be based on an ancestoral paracrine system. In submammalians, ANP and NPY may not only act as endocrine hormones, but also influence steroid-producing interrenal cells in a paracrine manner, and act as modulators on chromaffin cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307798
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    Pro-enkephalin opioid peptides are abundant in porcine and bovine splenic nerves, but absent from nerves of rat, mouse, hamster, and guinea-pig spleen (1995)
    Springer
    Cell & tissue research 281 (1995), S. 143-152 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Enkephalin ; Opioid peptides ; Spleen ; Innervation ; Neuro-immunology ; Species differences ; Immunohistochemistry ; Cow ; Pig ; Guinea-pig ; Mouse ; Rat ; Dsungarian hamster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The opioidergic innervation of the mammalian spleen and possible species differences were investigated. Light-microscopic immunohistochemistry revealed that splenic nerves of bovine and porcine spleen, but not of rat, mouse, hamster and guinea-pig spleen contained proenkephalin-derived opioidergic innervation. Immunoreactivity to both prodynorphin and pro-opiomelanocortin was absent from splenic nerves. In bovine and porcine spleen, fibers immunoreactive for met-enkephalin, met-enkephalin-Arg-Phe, met-enkephalin-Arg-Gly-Leu, leu-enkephalin and peptide F formed perivascular plexus, traveled in trabecular connective tissue, and extended into the capsule. Spatial relationships with immune cells were apparent in the white and red pulp, excluding lymphoid follicles. Colocalization of enkephalin immunoreactivity with immunoreactivities for tyrosin hydroxylase, dopamin-β-hydroxylase, and neuropeptide Y, but not for substance P or calcitonin gene-related peptide were found. Our results provide evidence that opioid expression in splenic innervation is strongly species-dependent and exclusively proenkephalin-derived. Colocalization with marker enzymes of noradrenergic neurons indicates a mainly postganglionic sympathetic origin of proenkephalinergic splenic innervation. Opioidergic perivascular nerves probably control the splenic blood flow. A close interrelationship of opioidergic fibers with immune cells provides the anatomical basis for direct effects of neurally released opioids on splenic immune functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307968
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  • 165
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    Electronic Resource
    Localization and coexistence of atrial natriuretic peptide (ANP) and neuropeptide Y (NPY) in vertebrate adrenal chromaffin cells immunoreactive to TH, DBH and PNMT (1995)
    Springer
    Cell & tissue research 280 (1995), S. 267-276 
    Details
    ISSN: 1432-0878
    Keywords: Adrenal organ ; Atrial natriuretic peptide ; Neuropeptide Y ; Catecholamine synthesizing enzymes ; Coexistence ; Rat ; Guinea pig ; Coturnix c. japonica (Aves, Phasianiformes) ; Lacerta viridis (Lacertilia) ; Bufo marinus, Caldula pulchra (Anura) ; Cyprinus carpio, Cottus scorpius (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Antisera specific for mammalian atrial natriuretic peptied (ANP) and neuropeptide Y (NPY) were applied to examine, in immunofluorescence, the occurrence of cells immunoreactive to ANP and NPY in the adrenal organs of mammals, birds, reptiles, amphibians, and bony fish. Catecholamine-containing cells were identified using antisera against tyrosine-hydroxylase, dopamine-β-hydroxylase, and phenylethanolamine-N-methyl-transferase. In all vertebrates studied, immunoreactivities to ANP and NPY occurred in adrenal chromaffin cells but were absent from the cortex or its homolog, the interrenal. The majority of immunoreactivities to ANP and NPY was confined to the adrenaline cells. In mammals, the number of ANP-immuno-reactive cells (60%–80% of the total cell population) exceeded that of the NPY-immunoreactive cells (35%–45%). In birds, reptiles, and Amphibia, the numbers of ANP-immunoreactive (35%–40%) and NPY-immunoreactive (30%–35%) cells were in a similar range. The bony fish showed a density of both ANP-immunoreactive (80%–90%) and NPY-immunoreactive (35%–40%) cells. In all species studied, immunoreactivities to ANP and NPY partially coexisted. Generally, 30%–55% of the ANP-immunoreactive cells also contained NPY-immunoreactivity. In rat, coexistence amounted to almost 100% and in quail to 95%. Except for the rat, three subpopulations of chromaffin cells seemed to occur: ANP-immunoreactive non-NPY-immunoreactive, ANP-immunoreactive+NPY-immunoreactive and NPY-immunoreactive non-ANP-immunoreactive cells. Thus, adrenal ANP and NPY share a conservative history and coexist as early as at the level of bony fish. The endocrine actions of ANP and NPY derived from medullary cells on cortical cells as found in mammals might be based on an ancestoral paracrine system. In submammalians, ANP and NPY may not only act as endocrine hormones, but also influence steroid-producing interrenal cells in a paracrine manner, and act as modulators on chromaffin cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307798
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  • 166
    Electronic Resource
    Electronic Resource
    Pro-enkephalin opioid peptides are abundant in porcine and bovine splenic nerves, but absent from nerves of rat, mouse, hamster, and guinea-pig spleen (1995)
    Springer
    Cell & tissue research 281 (1995), S. 143-152 
    Details
    ISSN: 1432-0878
    Keywords: Enkephalin ; Opioid peptides ; Spleen ; Innervation ; Neuro-immunology ; Species differences ; Immunohistochemistry ; Cow ; Pig ; Guinea-pig ; Mouse ; Rat ; Dsungarian hamster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The opioidergic innervation of the mammalian spleen and possible species differences were investigated. Light-microscopic immunohistochemistry revealed that splenic nerves of bovine and porcine spleen, but not of rat, mouse, hamster and guinea-pig spleen contained proenkephalin-derived opioidergic innervation. Immunoreactivity to both prodynorphin and pro-opiomelanocortin was absent from splenic nerves. In bovine and porcine spleen, fibers immunoreactive for met-enkephalin, met-enkephalin-Arg-Phe, met-enkephalin-Arg-Gly-Leu, leu-enkephalin and peptide F formed perivascular plexus, traveled in trabecular connective tissue, and extended into the capsule. Spatial relationships with immune cells were apparent in the white and red pulp, excluding lymphoid follicles. Colocalization of enkephalin immunoreactivity with immunoreactivities for tyrosin hydroxylase, dopamin-β-hydroxylase, and neuropeptide Y, but not for substance P or calcitonin gene-related peptide were found. Our results provide evidence that opioid expression in splenic innervation is strongly species-dependent and exclusively proenkephalin-derived. Colocalization with marker enzymes of noradrenergic neurons indicates a mainly postganglionic sympathetic origin of proenkephalinergic splenic innervation. Opioidergic perivascular nerves probably control the splenic blood flow. A close interrelationship of opioidergic fibers with immune cells provides the anatomical basis for direct effects of neurally released opioids on splenic immune functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307968
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  • 167
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    Effect of exposure to oxygen at 101 and 150 kPa on the cerebral circulation and oxygen supply in conscious rats (1995)
    Springer
    European journal of applied physiology 71 (1995), S. 475-484 
    Details
    ISSN: 1439-6327
    Keywords: Cardiovascular changes ; Hyperbaric O2 ; Microspheres ; Rat ; Regional cerebral blood flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Hyperbaric oxygen at pressures of 300 to 500 kPa has been shown to induce changed distribution of cerebral blood flow ( $$\dot Q$$ CBF) in rats, in places reducing the supply of the supplementary O2. Thus, in the present study, the effect of hyperoxia at 101 (group 1, n = 9) and 150 (group 2, n = 9) kPa OZ on cerebral blood flow distribution and central haemodynamics was tested in conscious, habituated rats. During the control period the systolic arterial pressure (BPs), heart rate (f c), breathing frequency (f b), cardiac output ( $$\dot Q$$ c), arterial acid-base chemistry and glucose, as well as $$\dot Q$$ CBF distribution (r $$\dot Q$$ CBF) were similar in the two groups of animals. During O2 exposure, the acid-base chemistry remained unchanged. The haemoglobin decreased in group 2, but remained unchanged in group 1. The f c decreased rapidly in both groups during the change in gas composition, after which f c remained constant both in group 1 and in group 2, for whom pressure was increased. The $$\dot Q$$ c and f b decreased and BPs increased similarly in the two groups. Total $$\dot Q$$ CBF and r $$\dot Q$$ CBF decreased to the same extent in both groups, and the r $$\dot Q$$ CBF changes were equally scattered. In group 1, breathing of pure O2 did not increase the O2 supply to any cerebral region except to the thalamus and colliculi after 60 min, whereas the O2 supply to the hypothalamus decreased and remained low. In group 2, the O2 supply was unchanged compared to the control period in all regions. These findings agree with previous observations during exposures to higher O2 pressures. In air after O2 exposure the acid-base chemistry remained normal. The f c and f b increased to higher levels than during the control period. The BPs remained high. The brain blood flows were increased, inducing elevated O2 supply to several brain regions compared to the control period. In conclusion, O2 supply to the central nervous system was found to be in the main unchanged during breathing of O2 at 101 kPa and 150 kPa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238548
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  • 168
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    Growth, hormonal status and protein turnover in rats fed on a diet containing peas (Pisum sativum L.) as the source of protein (1995)
    Springer
    Plant foods for human nutrition 47 (1995), S. 211-220 
    Details
    ISSN: 1573-9104
    Keywords: Hormonal status ; Legume diet ; Pisum sativum L. ; Protein turnover ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The inclusion of peas (Pisum sativum L.) as the source of protein in the diet of growing rats brings about a reduction in growth rate as well as the impairment in the liver, muscle and spleen weights as compared with casein fed controls. Also, a fall in plasma glucose, triglycerides and protein was observed in the legume fed animals, while no changes in cholesterol levels were found. Furthermore, the rats fed on the diet containing peas showed lower levels of plasma insulin, corticosterone, IGF-I and T4 as compared with casein controls. Liver and muscle total protein (mg) and total DNA (mg) were markedly decreased in the legume fed animals, but DNA/g, protein/DNA and RNA/protein ratios were similar in both dietary groups. Likewise, liver and muscle fractional synthesis rates were similar in the casein and legume groups, while the whole body protein synthesis is assumed to be lower in the legume fed animals due to differences in body weights. It is concluded that animals fed on a diet containing peas (Pisum sativum L.) as the only source of protein showed less adverse effects than those found with other legumes such asVicia faba L. orPhaseolus vulgaris L., in which protein quality, antinutritional factors and nutrient availability could be involved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01088329
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  • 169
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    Industrial mycology and the new genetics (1995)
    Springer
    Journal of industrial microbiology and biotechnology 14 (1995), S. 355-364 
    Details
    ISSN: 1476-5535
    Keywords: Transformation ; Fungi ; Yeast ; Genetics ; Biotechnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The genetic investigation of fungi has been extended substantially by DNA-mediated transformation, providing a supplement to more conventional genetic approaches based upon sexual and parasexual processes. Initial transformation studies with the yeastSaccharomyces cerevisiae provided the model for transformation systems in other fungi with regard to methodology, vector construction and selection strategies. There are, however, certain differences betweenS. cerevisiae and filamentous fungi with regard to type of genomic insertion and the availability of shuttle vectors. Single-site linked insertions are common in yeast due to the high level of homology required for recombination between vectored and genomic sequences, whereas mycelial fungi often show a high frequency of heterologous and unlinked insertions, often in the form of random and multiple-site integrations. While extrachromosomally-maintained or replicative vectors are readily available for use with yeasts, such vectors have been difficult to construct for use with filamentous fungi. The development of vectors for replicative transformation with these fungi awaits further study. It is proposed that replicative vectors may be inherently less efficient for use with mycelial fungi relative to yeasts, since the mycelium, as an extended and semicontinuous network of cells, may delimit an adequate diffusion of the vector carrying the selectable gene, thus leading to a high frequency of abortive or unstable transformants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569951
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  • 170
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    Effect of infra-red low-power laser irradiation on regeneration of myelinated axons (1995)
    Springer
    Lasers in medical science 10 (1995), S. 273-277 
    Details
    ISSN: 1435-604X
    Keywords: Ga-As laser ; Myelinated fibre regression ; Rat ; Sciatic nerve
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The purpose of the present study was to examine the regeneration of myelinated axons under the effect of laser irradiation at various wavelengths and energy densities. Laser irradiation at 890 nm with an energy dose of 0.33 J cm−2 as well as He-Ne laser irradiation failed to change the number of regenerating myelinated axons in distal nerve stumps on the 30th day after cutting the nerve. An increase of dose delivered to the skin to 9.33 J cm−2 resulted in a 49% decrease in the number of myelinated axons. A 24% suppression of nerve regeneration was also registered using 1220 nm wavelength laser (dose 0.98 J cm−2). This phenomenon is likely to be attributed to the stimulating effect of laser irradiation of the near-infra-red range on proliferation of fibroblasts and scar formation. 1220 nm of 7.2 J cm−2 dose effected neither the growth nor the myelinization of axons in distal nerve stumps on the 20th day following nerve damage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02133620
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  • 171
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    Have fishes had their chips? The dilemma of threatened fishes (1995)
    Springer
    Environmental biology of fishes 43 (1995), S. 1-27 
    Details
    ISSN: 1573-5133
    Keywords: Conservation ; Extinction ; Rarity ; Biodiversity ; Breeding guilds ; Endemism ; Speciation ; Habitat degradation ; Environmental management ; Invasive fishes ; Genetics ; Ecology ; Stenotopy ; Captive propagation ; Legislation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The conservation status and factors threatening fishes worldwide are reviewed in order to introduce a series of one-page articles on ‘Threatened fishes of the world’, and to encourage the incorporation of information on threatened fishes into international conservation programmes. Information on fish extinction and threat rates are compared with those of other animal groups, and the unique characteristics of fish conservation problems are highlighted. At present 979 species of fishes are listed as threatened in the IUCN Red List and at least 36 species and three subspecies are listed as recently extinct. It is argued that these figures are probably gross underestimates and that they may mislead conservation authorities and resource users about the seriousness of the situation. Freshwater fishes may be the most threatened group of vertebrates after the Amphibia. Urgent action is required to save many narrowly endemic, stenotopic species from extinction, especially in Africa, Asia and South America. The conservation of common species that drive essential ecological processes is also important. Anthropogenic pressures, especially habitat degradation, the introduction of invasive species and pollution, on inland and coastal waters are particularly severe and many major fish communities are threatened with elimination throughout the world. The conservation of marine fishes is complicated by the fact that it is difficult to ascertain their rarity. The importance of the retention of genetic variation is highlighted, and both orthodox and innovative conservation measures are encouraged. Further research on minimum viable populations, genetics, and the factors that cause fishes to become vulnerable to extinction, is urgently required.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00001812
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  • 172
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    Optimization of mechanical strength of reinforced composites. 1. Study on the effect of reactive bismaleimide on the mechanical performance of CaCo3-filled polypropylene (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 224 (1995), S. 9-20 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß von 3-Phenylenbismaleimid auf die Werkstoffeigenschaften von CaCO3 gefüllten Polypropylen-Verbundstoffen wurde untersucht. Die Verarbeitungstemperatur spielte eine entscheidende Rolle bei der Herstellung der Verbundwerkstoffe. Bei Verarbeitungstemperaturen oberhalb der Bismaleimid-Zersetzungstemperatur zeigte die Bismaleimid-Verbindung einen positiven Effekt. Die chemische Zusammensetzung der modifizierten Verbunde wurde mit den mechanischen Eigenschaften korreliert. Basierend auf ESCA-Analysen werden Wechselwirkungen zwischen dem Polymeren und CaCO, diskutiert.
    Notes: The effect of 3-phenylene bismaleimide on the mechanical performance of an inorganic filler-based polypropylene composite was studied. The selection of processing temperature played a significant role in the preparation of such composites. A positive effect of the bismaleimide compound was obtained for a processing temperature above the decomposition temperature of bismaleimide. The chemical composition of the modified composite was correlated to its mechanical strength by experimentation involving a rotatable design. An interaction between polymer and CaCO3 has been proposed based on ESCA analysis.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052240102
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  • 173
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    The effect of the processing steps on the oxidative stability of polyethylene tubing crosslinked by irradiation (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 224 (1995), S. 33-48 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Chemische und mechanische Eigenschaften von Zwischenprodukten der PE-Schrumpfschlauch-Produktion wurden bei unterschiedlichen Compound-Zusammensetzungen (PE, ein aromatisches Amin oder Phenolderivat als Antioxidans und in einigen Fällen ein Flammschutzmittel und/oder eine Elastomerkomponente) untersucht.Während der Herstellung, besonders während der durch Elektronenstrahlung initiierten Vernetzung, nimmt die thermooxidative Stabilität des Materials gegenüber der des compoundierten Granulats ab. Das aromatische Amin scheint bei gleicher Zusammensetzung das wirksamere und strahlungsbeständigere Antioxidans im Vergleich zum Phenolderivat zu sein. Die Oxidationsstabilität der hergestellten Schrumpfschläuche wird nicht von der Qualität des eingesetzten PE-Ausgangsgranulats beeinflußt.Durch die Alterung des Materials ändern sich die mechanischen Eigenschaften geringfügig. Die Elastomerzugabe bewirkt keine Änderung von Zugfestigkeit und Reißdehnung. Die Stabilität des Endprodukts ist bei weitem ausreichend, um den Spannungen, die beim Schrumpfen während des Gebrauchs auftreten, standzuhalten. Die gute Zugfestigkeit des Materials wird durch die Alterung ebenfalls nicht beeinträchtigt.Bei der Extrusion des Granulats tritt keine nennenswerte Änderung des Molekulargewichts bzw. der Molekulargewichtsverteilung auf. Durch die Bestrahlung wird das Material vernetzt und zu mehr als 50% unlöslich, und seine thermooxidativen Eigenschaften ändern sich deutlich gegenüber dem ursprünglichen PE und dem daraus compoundierten Material.
    Notes: Some chemical and mechanical properties of intermediate products obtained in the production of PE heat-shrinkable tubes were studied at different compositions of the material containing PE, antioxidant (aromatic amime or phenol) and, in some cases, flame retardant and/or an elastomer.In the course of the production phase, the thermooxidative stability decreases compared to that of compounded granulate. The greatest decrease is caused by irradiation. The aromatic amine seems to be a more effective antioxidant at similar compositions than the phenol derivative, and it shows a better resistance against irradiation. The oxidative stability of the finished shrinkable tubes is not affected by the quality of commercial granulate (initial polyethylene).Mechanical properties change slightly upon ageing, and the introduction of the elastomer did not alter the tensile strength and elongation at break. The remaining stability of the end product was still high enough to bear the stress of shrinking in use, and the good tensile strength of the material did not decrease upon thermal ageing either.In the extrusion of the granulated compound no significant change in the distribution and average molecular weight took place. Irradiation produced more than 50% insoluble fraction and the thermooxidative properties of the crosslinked sample changed significantly compared to the original PE and to the compound prepared from it.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052240104
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  • 174
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    Thermogravimetrie als brennbarkeitsbestimmungs-methode für lineare polyurethane (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 224 (1995), S. 89-96 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In the present work oxygen index (OI) measurements and thermogravimetric analysis (TG) for a series of polyurethanes based on diols and isocyanate were conducted. It was found that a correlation exists between some of the thermal degradation parameters obtained from TG and OI-values. Analysis of experimental results confirms that the amount of mass loss at 250°C is directly proportional to the OI-value. It was also found that the logarithmic temperatures of maximal decomposition rates are directly proportional to the OI-values.
    Notes: In der vorliegenden Arbeit wurden für eine Serie von Polyurethanen auf der Basis von Diol und Isocyanat der Sauerstoffindex (SI) gemessen und die thermische Zersetzung mittels thermogravimetrischer Analyse (TG) untersucht. Dabei wurde ein Zusammenhang zwischen einigen Parametern der thermischen Zersetzung und den SI-Werten gefunden. Die Auswertung der experimentellen Ergebnisse zeigte, daß die Höhe des Massenverlustes bei 250°C und die SI-Werte direkt proportional zueinander sind. Derselbe Zusammenhang besteht auch zwischen dem Logarithmus der Temperatur bei der maximalen Zersetzungsgeschwindigkeit und den SI-Werten.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052240109
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  • 175
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    Studies on thermal stability of modified polycarboxylate cements (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 224 (1995), S. 109-114 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly(acrylsäre-co-acrylamid) wurde mit Zinkoxid und Kryolith (Na3AlF6) in unterschiedlichen Verhältnissen gemischt und bei Raumtemperatur zu Zahnzementen ausgehärtet. IPDT, Temperaturen bei maximaler Abbaugeschwindigkeit, Aktivierungsenergien und Frequenzfaktoren des thermischen Abbaus der Proben wurden aus thermogravimetrischen Messungen ermittelt. Die Probe mit 20 Gew.-% Kryolith in der Füllstoffmischung ist thermisch sehr stabil.
    Notes: Dental cement compositions made by mixing poly(acrylic acid-co-acrylamide) and mixtures of zinc oxide and cryolite (Na3AIF6) in various proportions of 10-50 wt.-% (w/w) were cured at room temperature. From thermogravimetric analyses of the samples, the integral procedural decomposition temperatures (IPDT), maximum decomposition temperatures, activation energies and frequency factors were evaluated. The cured cement sample containing 20 wt.-% cryolite in the filler mixture is thermally very stable.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052240111
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  • 176
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    Synthesis and characterization of water-soluble diazonium salts as contrast-enhancement materials (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 224 (1995), S. 133-144 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die wasserlöslichen aromatischen Diazonium-Doppelsalze p-Diazodiphenylaminchlorid/Zinkchlorid (DZS-1) und p-Diazoanisolchlorid/Zinkchlorid (DZS-2) wurden auf ihre Verwendbarkeit als photobleichbare Farbstoffe in der Kontrastverstärkungslithographie untersucht. Nach Untersuchung der Bleicheigenschaften der hergestellten Salze wurde DZS-1 in wäßrigen Lösungen mit Poly(vinylalkohol) als Kontrastverstärkungssystem eingesetzt. Die thermische Stabilität, der Resistkontrast, die Bestrahlungsparameter und andere Bleicheigenschaften wurden untersucht. Im Vergleich zu einem handelsüblichen i-Linien-Photoresist beträgt das Kontrastverhältnis der DZS-1/PVA CEL-Schicht 1,67.
    Notes: Water soluble aromatic diazonium double salts, p-diazodiphenylamine chloride zinc chloride (DZS-1) and p-diazoanisol chloride zinc chloride (DZS-2), have been evaluated as photobleachable dyes for contrast enhancement lithography. After testing the bleaching characteristics, aqueous solutions of DZS-1 and poly(vinyl alcohol) were used as a contrast enhancement material. Thermal stability, resist contrast, exposure parameters and other bleaching characteristics of the photobleachable membranes were investigated. A. commercial i-line photoresist was used to evaluate the contrast ratio of the DZS-1/PVA CEL layer. The contrast ratio obtained in this investigation is 1.67.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052240114
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  • 177
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    Comparison of the coupling behaviour of diisocyanate and bisoxazolines in modification of liquid crystalline poly(ethylene terephthalate-co-oxybenzoate)s (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 224 (1995), S. 167-178 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Methylen-4,4′-diphenyldiisocyanat und zwei unterschiedliche Bisoxazoline wurden für Kopplungsreaktionen in mit Carboxygruppen terminierten flüssigkristallinen Poly(ethylenterephthalat-co-oxybenzoat)en eingesetzt. Um definierte Bedingungen zu gewährleisten, erfolgte die Synthese von Copolyestern mit unterschiedlichen Carboxygruppenkonzentrationen. Die Bestimmung des Carboxygruppengehalts wird beschrieben.Es erfolgt ein Vergleich des Kopplungsverhaltens beider Arten von Kettenverlängerern. Es konnte nachgewiesen werde, daß die Bisoxazoline bedeutend schneller reagieren als das Diisocyanat. Durch einen geringen Überschuß and Bisoxazolin in der Reaktionsmischung konnte einer thermischen Schädigung vorgebeugt werden. Abhängig von der Menge an zugegebenem Koppler wurden bei den modifizierten Copolyestern Oxazolinendgruppen beobachtet. Außerdem werden mögliche Vernetzungsreaktionen und die thermische Stabilität diskutiert.
    Notes: Methylene-4,4′-diphenyldiisocyanate and two different bisoxazolines were used for coupling reactions in carboxy-terminated liquid crystalline poly(ethylene terephthalate-co-oxybenzoate). In order to guarantee defined conditions, copolyesters with different carboxylic group concentrations were synthesized. The determination of the carboxylic group content is described.The coupling behaviour of both types of chain extenders has been compared. It was evidenced that the bisoxazolines reacted significantly faster than the diisocyanate. A slight excess of bisoxazoline in the reaction mixture prevented thermomechanical degradation. Depending on the amount of coupling agent added, an oxazoline termination of the copolyester was observed. Additionally, probable crosslinking reactions and the thermal stability have been discussed.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1995.052240117
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  • 178
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    Announcements (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 224 (1995), S. 201-201 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052240120
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  • 179
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    Optimization of mechanical strength of reinforced composites. 2. Reactive bismaleimide-modified polypropylene composites filled with talc and zeolitePart 1 cf.2. (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 225 (1995), S. 11-20 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß von 3-Phenylenbismaleimid auf die Werkstoffeigenschaften von mit Talkum und Zeolith gefüllten Polypropylen-Verbundstoffen wurde untersucht. Durch geeignete Planung des Aufbaus kann die Produkteigenschaft optimiert werden. Die Kapazität zur Füllstoffaufnahme schwankt bei Polypropylen je nach Art des Füllstoffs. Ein hochbelastbarer Verbundstoff kann aus einem geeignet modifizierten, mit Zeolith gefüllten Polypropylen hergestellt werden, auch wenn der Füllstoff in der Verbundmatrix dominiert. Als Ursache dieser Verstärkung wird eine verbesserte Wechselwirkung zwischen dem Polymeren und dem Füllstoff angenommen.
    Notes: The effect of 3-phenylene bismaleimide as a modifier for talc and zeolite-filled polypropylene composites has been studied. The usefulness of the experimental design to assure best product properties has also been illustrated. Polypropylene shows a variable degree of filling capacity depending on the type of filler. A high-strength composite can be prepared with suitably modified zeolite-filled polypropylene even if filler is the dominant phase in the composite matrix. An improved interfacial interaction between polypropylene and filler is proposed to be the reason for this improvement of strength.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1995.052250102
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  • 180
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    Oligomerization of 1-decene with Ziegler-Natta catalysts (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 225 (1995), S. 51-61 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die katalytische Oligomerisation von 1-Decen wurde mit Komplexverbindungen mehrerer Übergangsmetalle (Co(II), Co(III), Zr(IV), Ti(IV), Cr(III), V(V)) und Alkyl-aluminiumhalogeniden als Cokatalysatoren durchgeführt. Mit einem Chrom(III)-Et3Al2Cl3-Katalysatorsystem konnten Dimere (C20), Trimere (C30) und Tetramere (C40) von 1-Decen erhalten werden. Die kinematischen Viskositäten und Fließpunkte der hydrierten Oligomere wurden bestimmt und mit den Werten handelsüblicher Proben verglichen. Ein Mechanismus für die Oligomerisation von 1-Decen mit diesem Katalysatorsystem wird vorgeschlagen.
    Notes: The catalytic oligomerization of 1-decene has been carried out employing several transition metal complexes of Co(II), Co(III), Zr(IV), Ti(IV), Cr(III), V(V) in combination with alkyl aluminum halides as cocatalysts. The chromium(III)-Et3Al2Cl3 system exhibits good oligomerizing activity yielding dimers (C20), trimers (C30) and tetramers (C40) of 1-decene. The kinematic viscosities and pour points of hydrogenated oligomers have been determined and compared with those of commercial samples. The probable mechanism of oligomerization of 1-decene on this catalyst is described.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052250105
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  • 181
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    Zur Häurtung von Bisphenol-A-diglycidether mit Dicyandiamid in Gegenwart von Beschleuniger-Addukten (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 225 (1995), S. 99-107 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Single-component formulations of epoxy resins with reactive accelerators must be storable. The preparation of several blocked accelerators is described. The basicity of tertiary amines, which correlates with accelerating effects, as well as acidity and structure of polyphenols and modified novolacs influences the extend of blocking. The curing process was investigated by measurements of gel time and viscosity.
    Notes: Einkomponentige Epoxidharzsysteme mit effizienten Reaktionsbeschleunigern müssen lagerstabil sein. Daher wurden Versuche unternommen, Beschleuniger auf Basis von tertiären Aminen mit modifizierten Phenolnovolaken zu blockieren. Das Ausmaß der Blockierung ist sowohl von der Basizität der Amine, die mit der beschleunigenden Wirkung korreliert, als auch von der Acidität und dem strukturellen Aufbau der modifizierten Phenole abhängig. Die Bewertung der Härtungseigenschaften erfolgte über Gelzeitbestimmungen und Viskositätsmessungen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052250109
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  • 182
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    Comparison of the crack growth method and the crack stress whitening zone method for the fracture toughness determination of phenolphthalein poly(ether ketone)Key Project of the National Natural Science Foundation of China. (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 225 (1995), S. 131-138 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Bruchzähigkeit von Phenolphthalein-Poly(etherketon) bei 190°C wurde mit zwei verschiedenen Methoden bestimmt, der konventionellen Rißwachstumsmethode und der „stress whitening zone“-Methode. Die gute Übereinstimmung der Ergebnisse zeigt, daß letztere Methode zur Bestimmung der Rißinitiierung einiger Polymerer herangezogen werden kann, für die das „blunting line concept“ nicht geeeignet ist.
    Notes: Fracture toughness values of phenolphthalein poly(ether ketone) (PEK-C) at 190°C were determined by two different methods, i.e. the conventional crack growth method and the crack stress whitening zone method, which show consistent results. This indicates that the crack stress whitening zone method can be used to determine the crack initiation of some polymers for which the blunting line concept is unsuitable.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052250112
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  • 183
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    Thermodynamic studies on some interpolymer interactions and stability of polycomplexes (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 226 (1995), S. 13-22 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Stabilitätskonstanten und zugehörige thermodynamische Parameter (ΔH°, ΔS°) eines intermakromolekularen Komplexes aus Poly(acrylsäure-co-acrylamid), Poly(methacrylsäure-co-acrylamide) und Poly(N-vinylpyrrolidon) wurden mit bekannten Methoden bei verschiedenen Temperaturen bestimmt. Dabei wurde eine stufenweise Auflösung des Komplexes in Abhängigkeit von der Temperatur beobachtet, die mit den Stabilitätskonstanten und den thermodynamischen Parametern korreliert wurde.
    Notes: Stability constant and related thermodynamic parameters (ΔH° and ΔS°) of a multicomponent intermacromolecular complex consisting of poly(acrylic acid-coacrylamide), poly(methacrylic acid-co-acrylamide) and poly(N-vinylpyrrolidone) have been determined using known methods. A distinct stepwise disintegration of the complex at different temperatures has been observed, and this could be correlated with the stability constant and thermodynamic parameters calculated at various temperatures.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1995.052260102
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  • 184
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    The effect of ultrasound in ethyl methacrylate polymerization and depolymerization reactions (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 226 (1995), S. 53-57 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß von Ultraschall auf die Polymerisation und Depolymerisation von Ethylmethacrylat und der Mechanismus des Kettenabbruchs wurden untersucht. Der Polymerisationsumsatz war unabhängig von den verwendeten Ultraschallbedingungen (800 W, 35 kHz). Depolymerisationsversuche mit Ultraschall bei 20°C zeigten, daß Kettenabbruch im wesentlichen durch Disproportionierung stattfindet; dabei werden Molekulargewichte nicht unter ca. 500000 erreicht.
    Notes: The effect of ultrasound in ethyl methacrylate polymerization and depolymerization and the chain termination mechanism for ethyl methacrylate have been studied. Polymerization conversion at 60°C did not depend on energy (80 W) and frequency (35 kHz) of ultrasound applied. In ultrasound depolymerization studies at 20°C the governing termination mechanism was found to be disproportionation and the lower limiting molecular weight was Mn = 500 000.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052260106
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  • 185
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    Reaktive membrancopolymere auf acrylbasis (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 226 (1995), S. 71-87 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The copolymerization of acrylonitrile with maleic anhydride was investigated to synthesize acylic reactive polymers for manufacture of membranes that serve as support for covalent enzyme immobilization. The free-radical copolymer synthesis was carried out in solution (N,N-dimethylformamide (DMF), dimethylacetamide (DMAC), γ-butyrolactone, ethylene carbonate), by precipitation polymerization (dioxane) as well as bulk polymerization. The polymers were characterized using IR spectroscopy, elementary analysis, NMR spectroscopy, gel permeation chromatography, viscosity measurements, osmometry and potentiometry.The kinetic parameters were followed by dilatometric measurements up to high conversions. The anhydride content in the monomer mixtures showed a significant influence on the rate of polymerization and the molecular weight. With raised concentration of anhydride the polymerization rate and molecular weights decreased. Film forming polymers (M̄η 〉 30 000 g/mol) can be obtained by all copolymerization procedures with exception of solution polymerization in DMF and DMAC, respectively. The content of maleic anhydride in the membrane polymers did not exceed 5 mol-%, even though the maleic anhydride content in the monomer mixtures was raised up to the equimolar mixture. Nevertheless, such low maleic anhydride content of prepared membranes is enough for successful enzyme immobilization with amyloglucosidase (copolymer was prepared in γ-butyrolactone, M̄η = 49 000 g/mol, cPMSA = 0,3 mol-%).
    Notes: Die Copolymerisation des Acrylnitrils mit Maleinsäureanhydrid (MSA) wurde mit dem Ziel untersucht, acylfunktionalisierte Reaktivpolymere mit Filmbildungseigenschaften herzustellen, um diese in der Anwendung als Membran für kovalente Enzymfixierungen zu nutzen. Die radikalinitiierte Synthese der Copolymeren wurde in Lösung (Dimethylformamid (DMF), Dimethylacetamid (DMAC), γ-Butyrolacton, Ethylencarbonat), durch Fällungscopolymerisation (Dioxan) sowie in Substanz durchgeführt.Die Polymercharakterisierung erfolgte durch IR-Spektroskopie, Elementaranalyse, Kernresonanzspektroskopie, Gelpermeationschromatographie, Viskosimetrie, Osmometrie und Potentiometrie.Die Kinetik wurde durch dilatometrische Untersuchungen bis zu hohen Umsätzen verfolgt. Danach weist der Anhydridgehalt im Monomergemisch einen signifikanten Einfluß auf die Bruttopolymerisationsgeschwindigkeit und die Molmasse der Polymeren auf. Mit steigendem Anhydridanteil wird die Bruttopolymerisationsgeschwindigkeit herabgesetzt und eine Verringerung der Molmasse herbeigeführt. Die Copolymerisation von Acrylnitril und Maleinsäureanhydrid führt mit Ausnahme der Lösungspolymerisation in DMF bzw. DMAC zu Polymeren mit Molmassen oberhalb 30 000 g/mol, was ihre Anwendung als Membran ermöglicht. Die Einbaurate an Maleinsäureanhydrid in den Membranpolymeren ist bis einschließlich einer äquimolaren Zusammensetzung des Monomergemischs nicht größer als 5 mol-%. Derartig niedrige MSA-Reaktivgruppenanteile erweisen sich jedoch als ausreichend, um an einer aus einem Lösungspolymerisat (γ-Butyrolacton, M̄η = 49 000 g/mol, cPMSA = 0,3 mol-%) formierten Membran eine Enzymimmobilisierung mit Amyloglucosidase nachzuweisen.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052260108
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  • 186
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    Synthesis and characterization of photopolymers with azo units. Interfacial polyaddition, photolysis, photodegradation (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 226 (1995), S. 143-160 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Synthesen einer Aryl-alkyl-azodiisocyanat-Verbindung und einer Azoharnstoff-Modellsubstanz werden beschrieben. Aus dem Azodiisocyanat wurden durch Grenzflächen-Polyaddition neuartige Azoharnstoff-Polymer hergestellt. Die zahlenmittleren Molekulargewichte, bestimmt mit der Gelpermeationschromatographie (GPC), lagen zwischen 6000 und 9000. Die Photolyse- und Thermolysereaktionen der Modellsubstanzen und der Polymeren wurden mittels UV-Spektroskopie und Differentialkalorimetrie (DSC) verfolgt und mit den Ergebnissen von ähnlichen Azoamiden verglichen. Der photochemische Polymerabbau wurde mittels GPC untersucht.
    Notes: The synthesis of an aryl alkyl azo diisocyanate and a model azo urea is described. From the azo diisocyanate new azo polyureas were created by interfacial polyaddition. Molecular weights Mn in the range of 6000 to 9000 were determined by gel permeation chromatography (GPC). Photolysis and thermolysis of both, model compounds and polymers, were studied by UV-spectroscopy and differential scanning calorimetry (DSC), respectively, and the results were compared with those of similar azo amides. Photochemical polymer degradation was followed by GPC.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052260113
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  • 187
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    Announcements (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 226 (1995), S. 219-219 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052260120
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  • 188
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    Molecular structure of liquid-crystalline copolyesters of vanillic acid, 4-hydroxybenzoic acid and poly(ethylene terephthalate) (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 227 (1995), S. 69-85 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Thermotrop flüssigkristalline Copolyester aus Vanillinsäure (V), 4-Hydroxybenzoesäure (B) und Polyethylenterephthalat (E) wurden mittels 1H-NMR-Spektroskopie und Gelpermeationschromatographie (GPC) untersucht. Die neun möglichen Diaden konnten detektiert und zugeordnet werden. Die Abfolge der Grundeinheiten der V/B/E-Copolyester ändert sich mit zunehmendem B-Anteil von statistischer Verteilung zur Blockbildung und ist außerdem geringfügig von der Katalysatorkonzentration und der Polykondensationsdauer abhängig. Die GPC-Ergebnisse deuten darauf hin, daß die V/B/E-Copolyester engere Molekulargewichtsverteilungen aufweisen als die B/E-Copolyester. Mit von 0 bis 5 mol-% steigendem V-Anteil verengt sich die Molekulargewichtsverteilung. Die Gelpermeationschromatogramme der meisten V/B/E-Copolyester weisen im Unterschied zu den Einzelsignalen der B/E-Copolyester Dublett-Peaks auf.
    Notes: Thermotropic liquid-crystalline copolyesters made from vanillic acid (V), 4-hydroxybenzoic acid (B) and poly(ethylene terephthalate) (E) were examined by 1H-NMR and GPC investigations. Nine possible diads could be identified and assigned. The sequence distribution of V/B/E copolyesters tends to change from random to block with an increase of B content in the copolyesters. The sequence distribution also varies slightly with catalyst concentration and polycondensation time. GPC results suggest that the V/B/E copolyesters have narrower molecular weight distribution (MWD) than B/E copolyesters. The MWD of the copolyesters narrows gradually with increasing V content from zero to 5 mol-%. The GPC chromatograms of the most V/B/E copolyesters show double peaks, which is different from the single peak of the GPC chromatograms of the B/E copolyesters.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1995.052270108
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  • 189
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    Effect of pre-irradiation on radiation stability of co-polypropylene (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 227 (1995), S. 111-120 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Strahlungsbeständigkeit von vorbestrahltem Polypropylen mit 2,5 Gew.-% Ethylenanteil wurde mitr einem Copolymeren aus Polypropylen und einem nukleierenden Agens im Hinblick auf die Strahlungssterilisation von medizinischen Geräten verglichen. Die Transparenz des Propylen-Ethylen-Copolymeren wurde durch die Vorbehandlung verbessert. Im Vergleich mit der ebenfalls verbesserten Transparenz des Copolymeren aus Polypropylen und dem nukleierenden Agens wurde durch die Vorbestrahlung die Strahlungsbeständigkeit während der Bestrahlung und bei der Lagerung des bestrahlten Materials verbessert. Dies wird auf die geringere Kristallinität des vorbestrahlten Polypropylens aufgrund von bei der Bestrahlung gebildeten Verzweigungen zurückgeführt.
    Notes: The radiation stability of the pre-irradiated copolymer of polypropylene containing 2.5 wt.-% ethylene units is compared with a copolymer of polypropylene with a nucleating agent with regard to radiation sterilization of medical devices. It is found that transparency property of the propylene-ethylene copolymer is improved through pre-irradiation processes. This finding was compared with the co-polypropylene with nucleating agent which also gives a better transparency property. In comparison, it is found that pre-irradiated copolymer exhibits better radiation stability during irradiation and during storage after irradiation. The radiation stability of the pre-irradiated copolymer is due to its lower crystallinity caused by the formation of branches during the pre-irradiation process.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052270111
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  • 190
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    Mitteilungen/Announcements (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 227 (1995), S. 193-193 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052270117
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  • 191
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    Poly(diaryl diazosulfide)s  -  synthesis and photolysisThis topic is part of the Ph.D.-Thesis of A. Lang.. Photopolymers, diazosulfides, interfacial polycondensation, photolysis (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 228 (1995), S. 73-92 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polydiaryldiazosulfide wurden durch Grenzflächenpolykondensation aus aromatischen Bisdiazoniumionen und Benzol-1,3-dithiol erhalten. Auf diese Weise wurden Molekulargewichte Mn von 3400 bis 11700 erreicht (GPC).Die neue Polymerklasse zeichnet sich durch hohe Photolabilität und relativ geringe Thermostabilität aus. Mittels UV-Spektroskopie wurde die Photolyse von Modellver-bindungen und Polymeren verfolgt, wobei in nahezu allen Fällen ein Zerfall 1. Ordnung beobachtet wurde. Der photochemische Kettenabbau konnte durch GPC-Untersuchungen verfolgt werden. Die thermische Stabilität der polymeren Diazosulfide wurde durch DSC-Messungen untersucht.
    Notes: Poly(diaryl diazosulfide)s were synthesized from aromatic bisdiazonium ions and benzene-1,3-dithiol via interfacial polycondensation. Number-average molecular weights Mn in the range of 3400 to 11700 were determined by gel permeation chromatography (GPC).The new polymer class is distinguished by high photosensitivity and low thermostability. First order kinetics during photolysis of nearly all polymers and model compounds under investigation was observed by means of UV spectroscopy. Polymer degradation upon irradiation was verified by GPC measurements. Thermal decay was followed by differential scanning calorimetry (DSC).
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052280107
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  • 192
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    Methoden zur bestimmung des maleinsäureanhydridgehaltes in acrylnitril-copolymeren in gegenwart initialer carboxygruppen (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 228 (1995), S. 161-178 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Three different titration methods were proved with respect to accuracy, reproducibility and handling for the determination of maleic anhydride (MSA) content in acrylonitrile (AN) copolymers in form of poly(AN-co-MSA) and poly(AN-co-styrene-co-MSA). The comparison comprises (i) the combined method A/H characterized by the reaction of anhydride groups (AG) with aniline and titration of the formed monoacid with methanolic KOH (A) and the complete hydrolysis of AG and titration of acid groups (SG) with aqueous NaOH (H), (ii) method B based on the conversion of AG with n-butylamine (BA) and back-titration of unreacted amine with HClO4 in glacial acetic acid and (iii) method C consisting of the reaction of AG with p-chloroaniline (pCA) followed by Cl-determination after the Schöniger-decomposition. Whereas all mentioned methods are suitable for the determination of AG in the presence of initial SG, the combination of A/H additionally allows the simultaneous determination of AG and SG. In comparison with the other methods the combination of A/H is to be favoured due to the possibility to obtain additional information about SG and because of the better results in accuracy, reproducibility and handling. By means of FTIR spectroscopy the content of AG and SG was estimated qualitatively and a correlation between the spectroscopic and potentiometric data of AG was discovered.
    Notes: Zur Bestimmung des Maleinsäreanhydrid(MSA)-Gehaltes in Acrylnitril(AN)-Copolymeren des Typs Poly(AN-co-MSA) bzw. Poly(AN-co-Styrol-co-MSA) wurden drei verschiedene Titrationsmethoden hinsichtlich ihrer Richtigkeit, Reproduzierbarkeit sowie ihres Zeitaufwandes geprüft. Miteinander verglichen wurden (i) eine Methodenkombination A/H bestehend aus dem Teilschritt A, einer Umsetzung der Anhydridgruppen (AG) mit Anilin einschließlich der Titration der Monosäuregruppen mit methanolischer KOH, und dem Teilschritt H, einer vollständigen Hydrolyse der AG und Titration der Säuregruppen (SG) mit wäßriger NaOH, (ii) Methode B basierend auf der Reaktion der AG mit n-Butylamin (BA) und der Rücktitration des nicht umgesetzten Amins mit Perchlorsäure (HClO4) in Eisessig und (iii) Methode C, beruhend auf der Umsetzung der AG mit p-Chloranilin (pCA) und nachfolgender Chlorbestimmung durch Schöniger-Aufschluß. Während sich alle genannten Methoden prinzipiell für die AG-Bestimmung in Gegenwart initialer SG empfehlen, ist darüber hinaus über A/H eine simultane Bestimmung von AG und SG möglich. Wegen dieses zusätzlichen Informationsgewinns, ihrer besseren Reproduzierbarkeit, der erhöhten Richtigkeit sowie des geringeren zeitlichen und apparativen Aufwandes ist die Kombination A/H zu favorisieren. Mit Hilfe der FTIR-Spektroskopie wurde der Gehalt an AG und SG qualitativ verfolgt und eine Korrelation zwischen den Bandenintensitäten der AG und den potentiometrisch erhaltenen Werten gefunden.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052280113
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  • 193
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    Curing of unsaturated polyester resins with low exotherm peak (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 229 (1995), S. 15-27 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Härtung eines ungesättigten Polyesterharzes mit niedrigem Exotherm-Peak wurde mit der Standardmethodik und der Differential-Kalorimetrie (DSC) untersucht. Ein Kupfersalz und α-Methylstyrol wurden als Polymerisationsverzögerer benutzt. Der Einfluß der Verzögerer auf die Temperatur des exothermen Peaks, die Gelzeit, die Härtungsenthalpie und die Polymerisationskinetik wurden untersucht.
    Notes: The curing behavior of an unsaturated polyester resin with low exotherm peak was studied by a standard procedure and by differential scanning calorimetry (DSC). A copper salt and α-methylstyrene were used as the polymerization retarders. The influence of the retarders on the exotherm peak temperature, gelation time, exothermic heat and the polymerization kinetics was investigated.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052290102
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  • 194
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    Modified syndiotactic polypropene: Poly(propene-co-octene) and blends with atactic oligopropene (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 229 (1995), S. 93-112 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Propen und 1-Octen wurden mit dem syndiospezifischen Metallocen-Katalysator Me2C(Cp)(Flu)ZrCl2/MAO copolymerisiert. Es wurde ein hoher, statistischer Octeneinbau beobachtet. Niedrige Octenkonzentrationen beeinflußten die Aktivität des Katalysators nur wenig; Molekulargewicht, Kristallinität, E-Modul und Glastemperatur wurden dagegen mit ansteigendem Octengehalt erniedrigt. Blends aus ataktischem Oligopropen und syndiotaktischem Polypropen bzw. Poly(propen-co-octen) wurden aus einer Toluol-Lösung hergestellt. Diese Lösungsblends wurden mit einem Reaktorblend verglichen, der mit einem Hybrid-Katalysator bestehend aus einer Mischung von syndiospezifischem Me2C(Cp)(Flu)ZrCl2/MAO und unspezifischem Cp2ZrCl2/MAO hergestellt wurde. Das ataktische Oligopropen wirkte als Weichmacher, der E-Modul und Glastemperatur der Blends erniedrigte.
    Notes: Propene and 1-octene were copolymerized with the syndiospecific homogeneous metallocene catalyst Me2C(Cp)(Flu)ZrCl2/MAO. Large amounts of octene were incorporated randomly. While catalyst activity was not affected markedly by low octene content, molecular weight, crystallinity, Young's modulus, and glass transition temperature were reduced with increasing octene content. Blends of atactic oligopropene with syndiotactic polypropene and poly(propene-co-octene) were prepared from toluene solution and compared with a reactor blend prepared with a hybrid catalyst containing a mixture of syndiospecific Me2C(Cp)(Flu)ZrCl2/MAO and non-specific Cp2ZrCl2/MAO. Atactic oligopropene acted as plasticizer reducing Young's modulus and glass transition temperature of the blends.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052290106
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  • 195
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    Inner surface and void system of regenerated cellulose fibers (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 229 (1995), S. 175-184 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die innere Oberfläche und das Hohlraumsystem von verschiedenartigen Celluloseregeneratfasern werden mit Röntgenkleinwinkelstreuung untersucht. Dabei wird gefunden, daß alle Fasern ein Hohlraumsystem von 0,01 bis 0,1% (Volumenanteil 10-4-10-3) aufweisen. Es zeigt sich jedoch, daß die Größe des Hohlraumsystems für die mechanischen Eigenschaften wenig Bedeutung hat. Es ist vielmehr die Gestalt der Hohlräume und ihre Orientierung, die hier wesentlich sind. Es wird gefunden, daß langgestreckte Hohlräume, vermutlich orientiert, für gute mechanische Eigenschaften verantwortlich sind. Damit können auch verbesserte textile Eigenschaften von Lyocellfasern des NMMO-Typs erklärt werden.
    Notes: Both the inner surface and the void system of different cellulose regenerate fibers are investigated with X-ray small angle scattering. Thereby it turns out that all fibers have a void system of 0.01 to 0.1% (volume fraction 10-4-10-3). However, the amount of the void system has little influence on the mechanical properties. Rather, it is the shape of the voids and their orientation which proves essential. It is found that elongated voids, probably well oriented, are responsible for superior mechanical properties. This explains also improved textile properties of lyocell fibers of the NMMO type.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052290112
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  • 196
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    Radiation-induced copolymerization of methacrylic and acrylic acid with acrylamide (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 230 (1995), S. 1-12 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die mit γ-Strahlen induzierte Polymerisation von Methacrylsäure (MA) und Acrylsäure (AA) mit Acrylamid (AAm) (M2) in Substanz wurde untersucht. Die nach Kelen-Tüdős berechneten Copolymerisationsparameter betragen r1 = 1.35 und r2 = 0.22 für MA-AAm bzw. r1 = 1.75 und r2 = 0.10 für AA-AAm. Die Polymerisationsgeschwindigkeit hängt sowohl von der Temperatur als auch von der Comonomerzusammensetzung ab. Die differentialkinetischen Kurven sind unimodal, was darauf hinweist, daß nur der Copolymerisationsprozeß abläuft. Ein zweites Maximum in diesen Kurven wird mit Vernetzung und der Bildung wasserunlöslicher Bestandteile erklärt. Die Copolymeren sind weiße Pulver; die wasserlöslichen Fraktionen sind im Gegensatz zu den wasserunlöslichen nicht giftig, aber als Immunmodulatoren weniger aktiv.
    Notes: A study was made of the γ-radiation-induced bulk copolymerization of the methacrylic acid-acrylamide (M2) (MA-AAm) and acrylic acid-acrylamide (M2) (AA-AAm) monomeric pairs. The copolymerization reactivity ratios deterined according to the Kelen-Tüdő method were: r1 = 1.35, r2 = 0.22 for the MA-AAm pair, and r1 = 1.75, r2 = 0.10 for the AA-AAm pair. It has been established that the polymerization rate depends both on the composition of the starting reaction mixture and on the reaction temperature. The differential kinetic curves obtained are unimodal ones, suggesting the occurrence of only one process, i.e. copolymerization. A second maximum in these curves, appearing at elevated temperature, is explained by crosslinking and formation of a water-insoluble fraction. The copolymers obtained are white powders; in contrast to their water-insoluble fractions, the water-soluble ones are not toxic but they are less active as immunomodulators.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052300101
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  • 197
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    Synthesis and hydrolytic stability of model poly(ester urethane ureas) (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 228 (1995), S. 201-219 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Hydrolyse von Poly(ester-urethan-harnstoffen) (PURUs) wurde untersucht. Es handelt sich dabei um einen komplexen Vorgang, der die Analyse der Beziehung zwischen der Zusammensetzung der PURUs und ihrer Hydrolysebeständigkeit erschwert. Es wurde gefunden, daß die Hydrolysebeständigkeit mit Zunahme (i) der Polyol-Acidität, (ii) des Estergruppen-Gehaltes, (iii) der Beweglichkeit der Hauptketten und (iv) deren Hydrophilie abnimmt; die Molmasse des Polyols scheint keinen merklichen Einfluß darauf zu haben. Der negative Einfluß von Ethergruppen (obwohl hydrolysebeständiger als Estergruppen) ist möglicherweise auf eine Zunahme der Hauptkettenbeweglichkeit und den dadurch leichteren Zugang von Wassermolekülen zu Estergruppen zurückzuführen. Der positive Effekt von aromatischen Ringen in Polyolen kann einer erhöhten Steifigkeit der Hauptkette als auch einer ansteigenden Hydrolysebeständig-keit benachbarter Estergruppen durch Resonanzeffekte zugeschrieben werden. Insgesamt kann angenommen werden, daß die beschriebenen Effekte sich überlagern und gleichzeitig die resultierende Hydrolysebeständigkeit vorherbestimmen. Es sollte daher möglich sein, qualitative Vorhersagen bezüglich der Hydrolysebeständigkeit in Abhängigkeit von der Zusammensetzung der PURUs zu treffen.
    Notes: Hydrolysis of poly(ester urethane ureas) (PURUs) is a complex phenomenon which impedes the analysis of the relationships between their composition and hydrolytic stability. Hydrolytic stability of PURUs decreases due to rising (i) polyol acidity, (ii) content of ester groups, (iii) flexibility and (iv) hydrophilicity of the backbones; molar mass of polyols does not seem to have any appreciable effect on it. Negative influence of ether groups (which have better hydrolytic stability than ester groups) is probably linked to the increase in the backbone flexibility and, consequently, to easier access of water molecules to ester groups. Positive effect of aromatic rings in polyols can be ascribed to enhanced rigidity of the backbones as well as to increased hydrolytic stability of adjacent ester groups due to the resonance effect. It can be presumed that the mentioned effects will superpose and simultaneously predestine the resulting hydrolytic resistance. Considering the observed tendencies, it is possible to qualitatively predict the trends how the hydrolytic stability will respond to changes in PURUs composition.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052280116
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  • 198
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    Synthesis and characterization of a naphthoquinonediazide positive photoresist derived from bis(hydroxymethyl)phenol (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 229 (1995), S. 63-72 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine neuartige lichtempfindliche Naphthochinondiazid-Verbindung (NQD) wurde aus 2,6-Bis(hydroxymethyl)-3,4-dimethylphenol und Toluoldiisocyanat synthetisiert und mit IR-, NMR- und Elementaranalyse identifiziert. Die Bleicheigenschaften unter Lichteinwirkung wurden mit UV-Spektrophotometrie bestimmt. Die Anwendung von NQD in der Photolithographie als positiver Photoresist sowie einer wäßrigen Lösung von NQD, Novolak, Cellosolve-Acetat und DMF als lichtempfindliches Material wurde untersucht. Das hergestellte NQD erwies sich als effektive Komponente in positiven Photoresists. Die optimalen Bedingungen der UV-Dosis, Schichtdicke und Resistzusammensetzung wurden abgeschätzt. Die Auflösung des positiven Photoresists wurde durch Rasterelektronenmikroskopie bestimmt. Außerdem wurde der Einfluß von UV-Dosis und -Wellenlänge, Einwirkungsdauer und Entwicklungszeit auf die Empfindlichkeit und die Auflösung des Photoresists untersucht.
    Notes: A new photosensitive naphthoquinonediazide (NQD) was synthesized from 2,6-bis-(hydroxymethyl)-3,4-dimethylphenol and toluene diisocyante. NQD was identified by using IR, NMR and elemental analyses. Photobleachable characteristics were evaluated by UV spectrophotometry. Applications of the NQD on the photolithography as a positive working photoresist were investigated. The aqueous solution of NQD, novolak, cellosolve acetate, and DMF was used as a photosensitive material. It was found that NQD synthesized in this investigation can be used as an effective component in a positive photoresist. Optimal conditions of the UV dose, coating thickness, and development of the resist system were estimated. Resolution of the positive resist was evaluated by SEM technique. Effects of UV dose, exposure time, development time, and exposure UV wave length on the sensitivity and resolution of the photoresist were investigated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052290104
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  • 199
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    Investigations on free radical polymerization of phenyl-substituted 2-methylene-1,3-dioxanes (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 229 (1995), S. 123-132 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die radikalinduzierte Polymerisation von phenlysubstituierten 2-Methylen-1,3-dioxanen wurde untersucht. Es kann gezeigt werden, daß die grundlegende Polymerisationstendenz derartiger Ketenacetale darin besteht, über die Doppelbindung zu hochmolekularen Polyacetalen ohne eine nennenswerte Ringöffnung zu polymerisieren. Einflußfaktoren, wie z. B. resonanzstabilisierte Kettenenden oder sterische Hinderungen während des Wachstumsschrittes sind nicht in der Lage, die Polymerisation in die Richtung der gewünschten Ringöffnung zu lenken.Mittels Dichtemessungen wurden Informationen über das Schrumpfungsverhalten gewonnen. Es konnte gezeigt werden, daß raumerfüllende Substituenten am 2-Methylen-1,3-dioxansystem bei der Homopolymerisation grundsätzlich eine geringe Volumenschrumpfung bewirken und die Schrumpfung von herkömmlichen Monomeren bei der Copolymerisation herabsetzen können.
    Notes: We have investigated the free radical polymerization of phenyl-substituted 2-methylene-1,3-dioxanes. It was shown that there is a basic tendency of such ketenacetals to undergo exclusively a vinyl polymerization forming high-molecular polyacetals without any detectable ring opening. The polymerization with the desirable ring opening reaction cannot be controlled by factors like resonance stabilized chain ends or steric hindrance in the growing step.From densitometric measurements we got new information about the shrinkage behaviour. It was demonstrated that bulky substituents attached to the 2-methylene-1,3-dioxane system result in a significant low shrinkage in homopolymerization and the shrinkage of common comonomers can be decreased by copolymerization.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052290108
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  • 200
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    Acrylamide polymerization in concentrated bicontinuous systems (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 229 (1995), S. 133-143 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Polymerisation von Acrylamid (AAM) in einer konzentrierten bikontinuierlichen Mikroemulsion wurde studiert. Die Initiierungsstelle bei Verwendung von radikalischen Initiatoren mit verschiedener Wasserlöslichkeit wurde untersucht. Es wurde festgestellt, daß ein vollständig oder teilweise wasserlöslicher radikalischer Initiator die Acrylamidpolymerisation in der untersuchten Mikroemulsion effektiv initiieren kann. Die dadurch entstandenen Polymeren weisen eine Spezialstruktur auf, die von der Zusammensetzung der ursprünglichen Mikroemulsion abhängig ist.
    Notes: The polymerization of acrylamide (AAM) in concentrated bicontinuous microemulsion systems was studied. The locus of initiation using radical initiators with various water-solubility was investigated. It was found that water-soluble and partially water-soluble initiators initiate the AAM polymerization in the reaction systems under investigation very effectively. The polymers thus formed have special structures dependent on the composition of the original concentrated bicontinuous microemulsion.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052290109
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