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  • 1980-1984  (6,773)
  • 1965-1969  (9,583)
  • 1930-1934
  • 1910-1914  (1,666)
  • 1890-1899  (2,349)
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  • 1
    Electronic Resource
    Electronic Resource
    Interstellar molecules (1980)
    Springer
    Journal of molecular evolution 15 (1980), S. 79-101 
    Details
    ISSN: 1432-1432
    Keywords: Molecules ; Interstellar ; Chemistry ; Isotopes ; Solar system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The study of interstellar molecules broadly includes two areas of interest. One area uses the unique ability of molecules to act as probes of the physical conditions in the cold, dense, visually opaque component of the interstellar medium. The physical properties of this and other components of the interstellar medium are summarized. The other area deals with the chemistry of interstellar molecules, recent aspects of which are emphasized in this review. Gas-phase chemistry, shock chemistry, and grain surface chemistry are discussed in the context of recent observations. No present observations suggest that surface reactions are relevant, but neither can they be ruled out. Ion-molecule reactions are clearly operative, at least for the simpler species. Chemical isotope fractionation is reviewed, andd it is concluded that the complexities of the chemistry allow no cosmological conclusions to be drawn from observations of deuterium in interstellar molecules, while the presence of13C in interstellar molecules permits an estimate of the12C/13C ratio which is consistent with the current concepts of the nucleosynthesis history of the Galaxy. Possible connections between interstellar molecules and the early molecular history of the solar system are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01732663
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  • 2
    Electronic Resource
    Electronic Resource
    Cumulative effect of brief daily periods of monocular vision on kitten striate cortex (1980)
    Springer
    Experimental brain research 38 (1980), S. 53-56 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Monocular deprivation ; Visual cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Eight kittens were subjected to daily 4-h sessions with vision restricted to one eye between the 4th and 9th postnatal weeks. The total duration of monocular exposure ranged from 76 to 152 h. Between monocular exposure periods, four kittens were kept in total darkness, and four experienced binocular vision under normal colony conditions. At the end of the rearing period, all experimental animals and four normally reared controls were studied by means of single-unit recording in primary visual cortex. In kittens with inter-session dark rearing, very few neurons could be driven through the deprived eye. This effect was more extreme than that observed after continuous dark rearing. Visual responses mediated by the experienced eye appeared normal. In contrast, in kittens with inter-session binocular vision, the large majority of visual cortical neurons responded to visual stimulation of either eye. A few neurons appeared to have lost their responsiveness to the deprived eye, but this effect was small. We conclude that monocular vision delivered during brief daily sessions produces a cumulative competitive inactivation of transmission in the pathway from the deprived eye to striate cortex so long as no visual stimulation occurs outside the monocular periods. Binocular visual stimulation received between sessions rapidly and almost completely reverses the effects of monocular vision.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237930
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  • 3
    Electronic Resource
    Electronic Resource
    Development of binaural input, response patterns, and discharge rate in single units of the cat inferior colliculus (1980)
    Springer
    Experimental brain research 38 (1980), S. 103-108 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Auditory ; Binaural ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The binaural input to single neurones in the inferior colliculus of barbiturate- and ketamine-anaesthetised kittens was tested using pure tones. Stimuli were presented to each ear independently via sealed sound-delivery systems. Cells were classified according to the predominant type of input (excitatory or inhibitory) from each ear. There was no significant difference between age groups in the proportions of cells showing each type of binaural input. For all ages, cells excited by monaural stimulation of either ear (EE cells) tended to be of low best frequency (BF) and cells excited by monaural stimulation of one ear, but inhibited by simultaneous stimulation of the other ear (EI cells), had higher BFs. Units for which quantitative spike count data were obtained were also categorised according to their response pattern. Cells categorised as “onset”, “pauser” and “burst-type” were found in approximately equal proportions in animals of all age groups. “Primary-like” units were not found in animals less than 20 days old. Unit discharge rate was significantly higher for adults than for any of the three kitten groups. These data suggest that (1) binaural connections are not subject to postnatal developmental alteration and (2) the development of excitatory responses after 20 days consists of an increase in the number of discharges rather than a change in the pattern of these discharges.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237936
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  • 4
    Electronic Resource
    Electronic Resource
    A direct pathway from thalamus to visual callosal neurons in cat (1980)
    Springer
    Experimental brain research 38 (1980), S. 121-123 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Visual cortex ; Corpus callosum ; Horseradish peroxidase ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Horseradish peroxidase was injected in the right visual cortex and a large electrolytic lesion made in the left lateral geniculate nucleus of an adult cat. Neurons of origin of the callosal projection to the injected cortex were identified by retrograde labelling and selected for electron microscopic study. Degenerating thalamo-cortical axon terminals were found to contact a labelled stellate cell in layer IV and a labelled pyramidal cell in layer III at the border region of areas 17 and 18. We conclude that there is a monosynaptic pathway from lateral geniculate nucleus to the cells of origin of callosal axons to the contralateral visual cortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237940
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructure of degenerating cerebellothalamic terminals in the ventral medial nucleus of the cat (1980)
    Springer
    Experimental brain research 38 (1980), S. 125-135 
    Details
    ISSN: 1432-1106
    Keywords: Ventromedial thalamic nucleus ; Cerebellar degenerating boutons ; Ultrastructure ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Terminal degeneration of cerebellar afferents in the ventral medial thalamic nucleus (VM) was studied in cats at the ultrastructural level after uni- or bilateral lesions in the brachium conjunctivum (BC). To achieve discrete lesions within the BC, a new very accurate stereotaxic technique was used. Numerous large terminals belonging to a population of so-called LR boutons were observed degenerating in the VM. The boutons displayed a wide variety of degenerative changes. Some revealed the features of the classical neurofilamentous type of degeneration. Others, although containing a slightly increased number of neurofilaments, featured much more prominently large numbers of coated vesicle shells and heavy accumulations of a flocculent electrondense material. Degeneration in a third group of boutons similar to some extent to the light type of degeneration was characterized by tight clumping of enormously swollen or distorted synaptic vesicles within a light matrix. At later stages, however, all these boutons were believed to become shrunken and electron-dense since intermediate stages between the light- and dark-appearing boutons were observed. The degenerating cerebellar boutons formed asymmetrical synaptic contacts. Groups of 3 or 4 boutons terminated upon dendrites of projection neurons synapsing more frequently on spines than on dendritic stems. The synaptic contacts between cerebellar boutons and the vesicle-containing dendrites of local circuit neurons were encountered as often if not more than the contacts on projection neuron dendrites. Triads consisting of cerebellar boutons and dendrites of both types of neurons were observed very regularly. This synaptic arrangement provides the anatomical basis for the modification of cerebellar input in the VM by interneurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236734
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  • 6
    Electronic Resource
    Electronic Resource
    Stimulation of the superior colliculus in the alert cat (1980)
    Springer
    Experimental brain research 39 (1980), S. 63-73 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Stimulation ; Superior colliculus ; Eye movements ; Eye-head coordination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electrical stimulation of the cat superior colliculus (SC), in conjunction with the accurate measurement of elicited eye movements and histologically verified electrode positions, has revealed a striking antero-posterior variation in collicular organization. Three zones could be defined in the SC on the basis of eye movement patterns and associated neck muscle EMG activity evoked from the deeper layers. The Anterior zone was coextensive with the central 25 ° of the visual retinotopically coded map contained in the superficial layers. Saccades evoked from this zone were also retinotopically coded, and the latency of EMG activity depended on the position of the eye in the orbit. A similar observation applies to the entire monkey SC. The Intermediate zone was coextensive with the 25 °–70 ° of visual projections. Saccades evoked from this region were “goal-directed” and were associated with invariant, short latency EMG responses. The Posterior zone was found in the extreme caudo-lateral portion of the SC. Eye movements evoked from this zone were centering saccades associated with constant latency EMG activity. The present results in conjunction with previously demonstrated antero-posterior variations in projections to the SC, suggest that the motor strategies controlling gaze shifts toward visual targets vary depending on the location of the target in the visual field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237070
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  • 7
    Electronic Resource
    Electronic Resource
    Prefrontal cortex of the cat: Paucity of afferent projections from the parietal cortex (1980)
    Springer
    Experimental brain research 39 (1980), S. 105-112 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Prefrontal cortex ; Parietal cortex ; Mediodorsal thalamic nucleus ; Horseradish peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twenty-one cat brains with cortical injections of horseradish peroxidase resulting in labelled cells in the thalamic mediodorsal nucleus (MD) were screened for afferent projections from the parietal cortex. Contrary to expectation, nearly the whole prefrontal cortex (PFC) situated around the frontal pole was free of parietal afferents, while a small area in the anterior sylvian gyrus (orbito-insular subregion of PFC) consistently received afferents from the parietal cortex. The few afferents projecting to the cortex around the frontal pole originated exclusively from the convexity of the suprasylvian gyrus, while the great majority of the parietal neurons projecting to the anterior sylvian gyrus was situated within the fundus of the suprasylvian sulcus. While the main regions of the prefrontal cortex of the rhesus monkey receive a substantial projection from the parietal lobe, whereas the main regions of the cat's prefrontal cortex are free of afferents from the parietal cortex, possible differences in the parieto-prefrontal organization of both species are discussed. Furthermore, differences between the orbito-insular subregion and the rest of the PFC are emphasized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237073
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  • 8
    Electronic Resource
    Electronic Resource
    Rarity of luxotonic responses in cortical visual areas of the cat (1980)
    Springer
    Experimental brain research 39 (1980), S. 125-132 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Visual cortex ; Luxotonic sustained responses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neuronal responses to continuous, diffuse white light or darkness were studied in cortical visual areas 17, 18, 19 and Clare-Bishop of the unanesthetized cat. In contrast to squirrel monkeys and macaques in which about 40 or 25% of the units in striate cortex are luxotonic (response to continuous light or darkness sustained〉2.0 min), all of the visual areas in the cat had fewer than 4.0% of the units exhibiting such luxotonic activity. The functional basis of this difference may be related to differences between the two species in the quantitative balance of antagonistic receptive field properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237544
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  • 9
    Electronic Resource
    Electronic Resource
    Low threshold afferent projections from the oral cavity and the face to the cerebral cortex of the cat (1980)
    Springer
    Experimental brain research 39 (1980), S. 133-147 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Somatosensory cortex ; Oral projections ; Face projections ; Cytoarchitectonic organization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The projections of low threshold afferents from the oral cavity and the face to the cerebral cortex of cats anaesthetized with chloralose were investigated. The projection fields of the ipsi- and contralateral lingual, inferior alveolar, mental, superior alveolar, infraorbital, (separate branches from whiskers and nose), ophthalmic, great auricular and the contralateral superficial radial nerves were localized. Surface potentials of short latency and maximal amplitude were recorded and their location traced on photographs of the rostral part of the right cerebral hemisphere. Reference points were indicated with india ink punctures. The extent of the cytoarchitectonic areas was determined on histological serial sections and the borders transferred to the photographs of the hemisphere. The features of the projections were related to the cytoarchitecture and to the pattern of the gyri and sulci. It was observed that the low threshold afferents from the oral cavity and the face projected via fast conducting, presumably three synaptic paths, to separate locations in areas 3a, 3b, 5a and 6aβ. The projections to area 3b were somatotopically organized starting with the auricular and the ophthalmic nerve projections lateral to the 3b projection of the forelimb in the posterior sigmoid gyrus and continuing with the maxillary nose, maxillary whiskers, mental nerve, superior alveolar, inferior alveolar and lingual nerve fields along the coronal gyrus towards the presylvian sulcus. The somatotopy was, however, not isomorphic with the body surface but displayed consecutive, overlapping bands across area 3b. The projections to area 3a were similarly organized. The somatotopy was less obvious in area 5a and 6aβ. Convergent projections with responses of slightly longer latency were observed in area 43 (gyrus orbitalis).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237545
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  • 10
    Electronic Resource
    Electronic Resource
    The effect of electrical stimulation in the hypothalamus on the monosynaptic jaw closing and the disynaptic jaw opening reflexes in the cat (1980)
    Springer
    Experimental brain research 39 (1980), S. 389-400 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Jaw reflexes ; Hypothalamus ; Aggression ; Bruxisrn
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of electrical stimulation in the hypothalamus on the monosynaptic jaw closing and the disynaptic jaw opening reflexes were investigated in cats anaesthetized with chloralose. The hypothalamic electrodes were located by observation of behavioural attack responses in the unanaesthetized animal and by means of Horsley-Clarke coordinates. The locations were verified in histological serial sections. Hypothalamic conditioning with trains of 3–10 pulses, 0.5 ms duration, 0.5 mA, 500 Hz, evoked a strong facilitation of the jaw closing reflex and a facilitation followed by an inhibition of the jaw opening reflex. These effects differed from those elicited from the cerebral cortex. The hypothalamic effects had a longer latency (11–13 ms) and required a longer train of conditioning stimuli than was the case with those evoked from the cortex. Bilateral ablation of the sensorimotor cerebral cortex or lesion of the pyramids at the lower pontine level diminished but did not abolish the hypothalamic effects. They did, however, disappear after lesions including the ventral midbrain tegmentum. The stimulus positions eliciting the largest hypothalamic effects on the jaw reflexes were located in a region extending medio-laterally from the perifornical area to the entrance of the ansa lenticularis in the lateral hypothalamus. Rostro-caudally the location was found at the level of the ventromedial hypothalamic nucleus and the anterior hypothalamus just rostral to this nucleus. The region corresponds to those parts of the hypothalamus from which agonistic and feeding responses have been evoked. It is suggested that the observed hypothalamotrigeminal mechanism may exercise a tonic influence on the trigeminal motoneurones, thereby controlling the set point of the biting force. The implications of this hypothesis on the etiology of bruxism and the myofascial pain dysfunction are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239303
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  • 11
    Electronic Resource
    Electronic Resource
    Functional amblyopia in kittens with unilateral exotropia (1980)
    Springer
    Experimental brain research 40 (1980), S. 294-304 
    Details
    ISSN: 1432-1106
    Keywords: Squint amblyopia ; Visual cortex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In two cats in which surgically induced, unilateral divergent strabismus had led to behaviourally determined amblyopia, a variety of electrophysiological parameters were determined in search of neuronal correlates of squint amblyopia. Tests that assess global neuronal excitability along the pathways from the two eyes to the visual cortex (areas 17 and 18) failed to reflect the functional inferiority of the squinting eye: retinographic responses and cortical evoked potentials elicited by Ganzfeld-stimulation and by stimulation of the optic nerves were identical for the two eyes. The ocular dominance distribution of neurons in area 17 showed the expected disruption of binocularity but failed to provide clear evidence for a functional inferiority of the squinting eye. At other levels of analysis, however, a clear difference between the two eyes was apparent: 1. Responses to optimally aligned light stimuli tended to be more sluggish and the under-representation of neurons with vertically oriented receptive fields was more pronounced in neurons driven from the deviated eye than in cells dominated by the normal one. 2. Interocular inhibition as assessed from electrically evoked potentials was found to be asymmetric; responses evoked from the amblyopic eye were suppressed more readily and over longer periods by conditioning shocks applied to the normal nerve than vice versa. 3. Numerous abnormalities reflecting the functional inferiority of the squinting eye became apparent in cortical potentials evoked by phase reversal of gratings of variable spatial frequency and contrast. A laminar analysis of these field potentials suggests impaired transmission along the intracortical pathways which relay activity to supragranular layers as a major cause for abnormal responses from the squinting eye. It is concluded that squint amblyopia is associated with a variety of neuronal changes at various levels of the visual system, the present data providing evidence for alterations at the cortical level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237794
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  • 12
    Electronic Resource
    Electronic Resource
    Effect of amphetamine and pentobarbital on sleep-wake patterns of cats with basal forebrain lesions (1980)
    Springer
    Psychopharmacology 68 (1980), S. 179-184 
    Details
    ISSN: 1432-2072
    Keywords: Amphetamine ; Pentobarbital ; Sleepwake ; EEG ; REM sleep ; Forebrain ; Cat ; Lesion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of amphetamine and pentobarbital upon electrographic state were studied in naive cats and cats with forebrain lesions that induce insomnia. Amphetamine increased alertness and decreased both slow wave sleep (SWS) and rapid eye movement (REM) sleep states for up to 12 h in both intact animals and cats with lesions. Pentobarbital inhibited REM sleep and alert states while increasing SWS and drowsy states in naive cats. The effect was mainly restricted to the first 8 h. In cats with forebrain lesions, the effects were similar except that the amount of REM sleep was significantly elevated. During a portion of the first 8 h, the tracing cannot be distinguished from a normal control sample. It is hypothesized that pentobarbital mimics the normal inhibitory influence of the intact forebrain and either induces or facilitates ‘normal’ sleep patterns in cats with forebrain lesions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00432138
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  • 13
    Electronic Resource
    Electronic Resource
    The tapetal cell: A unique melanocyte in the tapetum lucidum cellulosum of the cat (Felis domestica L.) (1980)
    Springer
    Anatomy and embryology 158 (1980), S. 289-302 
    Details
    ISSN: 1432-0568
    Keywords: Tapetum lucidum ; Cat ; Melanocytes ; Development ; DOPA-reaction ; DOPA ; cysteinyldopa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The postnatal development of the tapetum lucidum cellulosum of the cat was studied with cytochemical, histochemical, microspectrofluorimetric, and chemical methods. At birth, the prospective tapetal cells exhibit a cytoplasmic, formaldehyde-induced catechol fluorescence which, by spectrographical criteria, is due to the presence of a thioether of DOPA, most likely 5-S-cysteinyldopa. These cells show a positive DOPA-reaction in the GERL, a Golgi-associated system of smooth endoplasmic reticulum. Beyond the third postnatal week, tyrosinase activity is found in the GERL and in the premelanosomal-like tapetal rods. Shortly thereafter, cells in the innermost layers of the tapetum reveal a change in the colour of the fluorophore from green (formaldehyde-induced) to orange-yellow (autofluorescent). Concomitant with the appearance of the yellow fluorophore (having spectral characteristics similar to authentic riboflavin), the DOPA-reactivity in the tapetal cells is no longer detectable and the cells attain the feature of mature tapetal elements with typical elongated, parallelly arranged, electron-dense rods. The increases and decreases in tyrosinase activity are parallelled by similar time-dependent changes in DOPA and cysteinyldopa content. Both DOPA and cysteinyldopa are considered as potential precursors of melanin polymers. Thus, these data support the concept that the tapetal cells represent uniquely differentiated and highly specialized choroidal melanocytes. The compact arrangement of these cells in the tapetum lucidum renders it an ideal tissue for studying the developmental biology of melanocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301818
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  • 14
    Electronic Resource
    Electronic Resource
    The reticulocerebellar projection in the cat as studied with retrograde transport of horseradish peroxidase (1980)
    Springer
    Anatomy and embryology 160 (1980), S. 341-359 
    Details
    ISSN: 1432-0568
    Keywords: Reticulocerebellar ; Peroxidase ; Retrograde transport ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Injections of horseradish peroxidase into the various parts of the cerebellar cortex and the cerebellar nuclei in the cat result in labelled cells within the reticular formation proper. All the reticular nuclei (with the exception of the reticular formation of the mesencephalon) send fibres to the cerebellum. The highest number of labelled neurons after cerebellar injections is found in the caudal reticular formation, especially within nucleus reticularis ventralis, nucleus reticularis lateralis and nucleus reticularis gigantocellularis. Another region for an accumulation of labelled cells is the rostral part of nucleus reticularis pontis caudalis. Except for the paraflocculus, all cerebellar cortical areas and all cerebellar nuclei receive afferents from one or more of the nuclei within the reticular formation proper, but the largest number of labelled neurons is observed in cases with injections including the intermediate-lateral part of lobulus simplex and the adjacent areas of the anterior lobe and crus I. The projection is bilateral with an ipsilateral preponderance (the cerebellar nuclei appear to receive a higher number of fibres from the contralateral side). Cells of all sizes are labelled, but labelled giant cells are found only after large cortical injections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00305113
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  • 15
    Electronic Resource
    Electronic Resource
    Mapping of monoamine neurones and fibres in the cat lower brainstem and spinal cord (1980)
    Springer
    Anatomy and embryology 161 (1980), S. 169-195 
    Details
    ISSN: 1432-0568
    Keywords: Monoamines ; Histofluorescence ; Brainstem ; Spinal cord ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The localization of monoaminergic neurones in the medulla oblongata and the pons, and the distribution of catecholaminergic fibres in the spinal cord of the cat were investigated by means of formaldehyde-induced (FIF) or glyoxylic-acid-induced (GIF) fluorescence. Four groups of catecholamine (CA)-containing neurones were found in the following regions: (1) in the ventrolateral medulla oblongata within and adjacent to the lateral reticular nucleus, beginning slightly rostral to the medullo-spinal junction and extending rostrally to the cranial third of the inferior olive; (2) in the commissural, medial and lateral nucleus of the solitary tract; (3) cranial to the first group, closely adjacent to the facial nucleus and the superior olive; and (4) in the dorsolateral pons distributed to different nuclei, namely the nucleus coeruleus and subcoeruleus, the Koelliker-Fuse nucleus, and the medial and lateral parabrachial nuclei. The indoleamine (IA)-containing cell bodies were in general confined to the raphe nuclei, namely the nucleus raphe pallidus, nucleus raphe obscurus, nucleus raphe magnus, nucleus raphe pontis, nucleus raphe dorsalis and the central superior nucleus. A few IA-neurones were located more laterally, especially dorsal and lateral of the cranial half of the inferior olive, around the root of the hypoglossal nerve, in the lateral tegmental field and the pontine central gray. In the spinal cord most CA-fibres were found in the intermediolateral cell column. Another dense accumulation of CA-fibres was located dorsally and laterally of the central canal. The ventral and dorsal horns also contained CA-nervefibres which were slightly more numerous in the sacral spinal cord than in the more rostral parts of the spinal cord.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00305343
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  • 16
    Electronic Resource
    Electronic Resource
    The cat locus coeruleus (1980)
    Springer
    Anatomy and embryology 159 (1980), S. 181-198 
    Details
    ISSN: 1432-0568
    Keywords: Cat ; Locus coeruleus ; Neuroanatomy ; Cytology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The neuronal cell bodies of the locus coeruleus (LC) and subcoeruleus (SC) of the cat were investigated using Nissl and Golgi preparations, and electron microscopy. On the basis of morphological criteria — size and shape of cell body, branching pattern of dentrites, distribution of cytoplasmic organelles and number of axosomatic synapses — four types of neuronal perikarya were recognized in each region: medium-sized, small-sized and two groups of intermediate-sized neurons. The medium-sized neurons (30–50 μm) had an elongated cell body, thick dendrites with a moderate number of branchings, abundant organelles arranged in concentric rings around the nucleus and a moderate number of axosomatic synapses. They were found throughout the LC and SC and most probably correspond to the larger class of catecholaminergic neurons demonstrated by fluorescence histochemistry. The small neurons (10–25 μm) were also seen in both LC and SC and are believed to represent non-monoaminergic local interneurons. They displayed sparsely branching dendrites and a thin rim of cytoplasm containing few organelles. In the SC, some of these small cells occurred in closely associated pairs. Ultrastructural analysis of such pairs revealed a close apposition (80–100 Å) of the cell membranes for long distances (up to 10 μm) and a narrowing of the intercellular space (30–40 Å) at some discrete points, perhaps indicative of an electrical interaction. The intermediate-sized neurons exhibited some regional morphological differences, but two distinct subgroups could be distinguished. One was characterized by a low number of axosomatic synapses, while the other exhibited a high number of such contacts. It may be assumed that the two subgroups of intermediate-sized neurons comprise catecholaminergic and indolaminergic neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304977
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  • 17
    Electronic Resource
    Electronic Resource
    The importance of energetic particle precipitation on the chemical composition of the middle atmosphere (1980)
    Springer
    Pure and applied geophysics 118 (1980), S. 128-151 
    Details
    ISSN: 1420-9136
    Keywords: Galactic cosmic rays ; Solar proton events ; Particle precipitation ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract An assessment is made of the relative contribution of certain classes of energetic particle precipitation to the chemical composition of the middle atmosphere with emphasis placed on the production of odd nitrogen and odd hydrogen species and their subsequent role in the catalytic removal of ozone. Galactic cosmic radiation is an important source of odd nitrogen in the lower stratosphere but since the peak energy deposition occurs below the region where catalytic removal of O3 is most effective, it is questionable whether this mechanism is important in the overall terrestrial ozone budget. The precipitation of energetic solar protons can periodically produce dramatic enhancement in upper stratospheric NO. The long residence time of NO in this region of the atmosphere, where catalytic interaction with O3 is also most effective, mandates that this mechanism be included in future modelling of the global distribution of O3. Throughout the mesosphere the precipitation of energetic electrons from the outer radiation belt (60°≲Λ≲70°) can sporadically act as a major local source of odd hydrogen and odd nitrogen leading to observable O3 depletion. Future satellite studies should be directed at simultaneously measuring the precipitation flux and the concomitant atmosphere modification, and these results should be employed to develop more sophisticated models of this important coupling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01586448
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  • 18
    Electronic Resource
    Electronic Resource
    Profile of the sensitive period for monocular deprivation in kittens (1980)
    Springer
    Experimental brain research 39 (1980), S. 17-21 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Monocular deprivation ; Visual cortex ; Sensitive period
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Thirteen kittens were subjected to 10–12 days of unilateral eye closure at ages spaced regularly through the first 4 months after birth. At the end of each kitten's period of monocular vision, the degree of functional disconnection between the deprived eye and neurons in striate cortex was assessed by means of single-unit recording. When the proportion of cortical cells giving no response to stimulation through the deprived eye was analyzed as a function of the kitten's age at the onset of eye closure, it was found that the effectiveness of monocular deprivation rose prior to postnatal day 28, remained high through day 48 and then subsided gradually, probably persisting at least through the end of the fourth postnatal month. The degree of functional modifiability persisting in the visual cortex of older kittens may be related to the initial ocular dominance of each neuron. Cells responsive exclusively to the deprived eye prior to deprivation probably do not acquire functional input from the nondeprived eye in kittens older than 48 days, for a normal proportion of such cells is encountered after the period of eye closure. Conversely, cells dominated by the nondeprived eye probably are most likely to lose their input from the deprived eye, as indicated by the columnar organization of cells not responsive to the deprived eye.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237065
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  • 19
    Electronic Resource
    Electronic Resource
    Functional changes across the 17–18 border in the cat (1980)
    Springer
    Experimental brain research 39 (1980), S. 177-186 
    Details
    ISSN: 1432-1106
    Keywords: Visual cortex ; Cat ; Areas 17 and 18 ; Velocity sensitivity ; Magnification factor ; Vertical meridian
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Changes in velocity sensitivity, receptive field (RF) position, and RF size were investigated in long oblique penetrations crossing the 17–18 border. The penetrations were histologically reconstructed and the border determined by cytoarchitectonics. In cortex subserving central and paracentral vision change in velocity sensitivity allowed a reasonable physiological identification of the 17–18 border. The physiological border correlates well with the histological border zone, best with its medial edge. Changes in RF position and RF size are of little use for physiological identification of the border in this region. In this cortical region area 18 representation of the vertical meridian (VM) has a high magnification factor. In cortex subserving peripheral vision, the change in velocity sensitivity was small and the change in RF position coincided with the cytoarchitectonics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237548
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  • 20
    Electronic Resource
    Electronic Resource
    Facilitation and inhibition of jaw reflexes evoked by electrical stimulation of the cat's cerebral cortex (1980)
    Springer
    Experimental brain research 39 (1980), S. 149-164 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Jaw reflexes ; Cerebral cortex ; Cytoarchitectonic areas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of electrical stimulation of the cerebral cortex on the monosynaptic jaw closing and the disynaptic jaw opening reflexes were studied in cats anaesthetized with chloralose. The time course of the reflex effects was recorded. Similar rhythmic sequences of facilitation and inhibition were observed in both reflexes (Fig. 3). The sequence could start with facilitation or inhibition. The latency of the initial effects was short (2.5 ms) indicating a minimum of two synapses in the descending path. The period of the rhythmic sequence was approximately 10 ms. Optimal parameters for the conditioning cortical stimuli were found to be: trains of 3–5 surface anodal pulses, 0.5 ms, 400 Hz. The threshold of the cortical effects on the reflexes was 0.3 mA. A single pulse evoked effects. The cortical origin of the effects was located and related to the somatosensory projections, and to the cytoarchitecture. The effects of largest amplitude and most complex time course were evoked from the oral and perioral projections to areas 3a and 3b. Effects evoked from areas 4γ, 5a, and 6aβ were less complex and of lower amplitude. It is suggested that a trigemino-cortico-trigeminal loop via 3a may function in reflex modulation of the jaw movements. In addition area 3a may contribute to cortico-cortical motor elaborations via U-fiber connections to area 4γ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237546
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  • 21
    Electronic Resource
    Electronic Resource
    Mécanorécepteurs splanchniques de la voie biliaire et de son péritoine (1980)
    Springer
    Experimental brain research 40 (1980), S. 146-153 
    Details
    ISSN: 1432-1106
    Keywords: Microelectrode technique ; Splanchnic mechanoreceptors ; Gall bladder ; Cat ; Microélectrode mecanarecepteurs splanchniques ; Vesicule biliaire ; Chat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Le but de ce travail est l'étude électrophysiologique des mécanorécepteurs de la vésicule biliaire. L'activité unitaire des neurones est enregistrée au moyen de microélectrodes de verre extracellulaires implantées dans les ganglions spinaux (T6-L1). Deux types de mécanorécepteurs ont été mis en évidence par stimulation punctiforme. Mécanorécepteurs musculaires a) Des récepteurs à adaptation lente localisés dans l'ensemble du tractus biliaire, sensibles à la distension. b) Des récepteurs à adaptation rapide, localisés dans la vésicule biliaire, mis en jeu par la phase dynamique de la stimulation. Ces récepteurs sont connectés avec des fibres C. Mécanorécepteurs péritonéaux a) Des corpuscules de Pacini, localisés dans le mésentère entourant le tractus biliaire. b) Des récepteurs à adaptation lente (récepteurs de mouvement), localisés dans la séreuse de la vésicule biliaire et le péritoine péricystique et péricholédocien. Les corpuscules de Pacini sont connectés avec des fibres Aβ, les récepteurs de mouvement avec des fibres Aγδ et B.
    Notes: Summary The aim of the present paper is to study the electrophysiology of splanchnic gall bladder mechanoreceptors. The neurons unitary activity is recorded by means of glass extracellular microelectrodes implanted in the spinal ganglion (T6-L1). Two types of mechanoreceptors have been revealed by punctiform stimulations. Muscular Mechanoreceptors a) Slowly-adapting receptors, located in the whole biliary tract, sensitive to distension. b) Rapidly-adapting receptors, located in the gall bladder, recruited during the dynamic phases of stimulation. These receptors connected with C fibers. Peritoneal Mechanoreceptors a) Pacinian corpuscles, located in the mesentery surrounding the biliary tract. b) Slowly-adapting receptors (movement receptors), located in the serosa of the gall bladder and the pericystic and pericholedochal peritoneum. Pacinian corpuscles are connected with Aβ fibers, movement receptors with Aγδ and B fibres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237532
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  • 22
    Electronic Resource
    Electronic Resource
    Organization of the cortico-caudate projections (1980)
    Springer
    Experimental brain research 40 (1980), S. 203-208 
    Details
    ISSN: 1432-1106
    Keywords: Cortico-caudate neurones ; Premotor area ; Horseradish peroxidase ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The organization of the cortico-caudate projection neurones in the cerebral cortex was demonstrated by utilizing retrograde axonal transport of horseradish peroxidase (HRP) in the cat. Following injection of HRP into the head portion of the caudate nucleus, cortical labelled cells with HRP could be divided into two groups, consisting of smaller and larger pyramidal neurones. The location of the smaller neurones in the cortex was mainly in layer III, while that of the larger neurones was exclusively in layer V. In the cerebral cortex ipsilateral to the HRP-injected side, labelled cells belonging to the smaller group were distributed mostly in area 6 and occasionally in areas 4 and 5. Labelled cells belonging to the larger group were located exclusively in area 6. In the contralateral cortex, labelled cells were all smaller in size and distributed only in area 6. Referring to recent physiological as well as anatomical data, the smaller, labelled pyramidal cells were considered to be the proper, direct cortico-caudate neurones. The larger, labelled pyramidal cells were regarded as cortico-caudate projection neurones also sending axons to the lower brains tern and/or the spinal cord. The results of the present study indicate the existence of a close relationship between area 6 (premotor area) of the cerebral cortex and the caudate nucleus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237538
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  • 23
    Electronic Resource
    Electronic Resource
    Brain stem projections to the pulvinar-lateralis posterior complex of the cat (1980)
    Springer
    Experimental brain research 40 (1980), S. 209-220 
    Details
    ISSN: 1432-1106
    Keywords: Thalamus ; Visual system ; HRP ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present experiments were undertaken to define the areas of projection of pretectum and superior colliculus to the pulvinar and n. lateralis posterior, respectively, and to define other brain stem structures projecting to these thalamic nuclei in cats. For this purpose the technique of retrograde transport of horseradish peroxidase (HRP) has been used. After injection of the enzyme in the pulvinar, neurons were labeled in all subdivisions of the pretectal area. The majority of the labeled cells were located in the n. pretectalis posterior and n. tractus opticus although cells filled with HRP were present also in the n. pretectalis anterior pars compacta and area pretectalis medialis. Neurons projecting to the pulvinar were also found in the periaqueductal gray, reticular formation and locus coeruleus. When HRP was injected in the n. lateralis posterior, labeled neurons were present in the II and III subdivisions of the second layer of the superior colliculus. The location of these cells shifted from medial to lateral as the injections were shifted from posterior to anterior within the lateralis posterior. Neurons projecting to this nucleus were also present in the intermediate layers of the superior colliculus, lateral hypothalamus and parabigeminal nucleus. The possible role of the pretectal area and superior colliculus in mediating somesthetic input to the pulvinar and lateralis posterior, respectively, and the role of these structures in the control of ocular movements, are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237539
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  • 24
    Electronic Resource
    Electronic Resource
    Cells of origin of crossed and uncrossed corticospinal fibers in the cat (1980)
    Springer
    Experimental brain research 40 (1980), S. 23-34 
    Details
    ISSN: 1432-1106
    Keywords: Pyramidal tract ; MI ; SI ; SII ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The cortical distribution of the cells of origin of the dorsolateral and the ventral corticospinal tracts was studied in cat. This was done by making subtotal spinal transections, which in different experiments spared different portions of one ventral or one lateral funiculus at C5–C7. One week later horseradish peroxidase (HRP) injections were made one segment caudal to the lesion and the cortical distribution of the HRP labeled neurons was studied. Thus, it was found that the dorsolateral corticospinal tract at C5–C7 is composed of crossed and uncrossed fibers in a ratio of about 10 ∶ 1, while the ventral corticospinal tract, which contains much fewer cortical fibers, is composed of crossed and uncrossed fibers in a ratio of approximately 1 ∶ 1. Further, the primary motor cortex (area 4) was found to contribute fibers to both the crossed and the uncrossed dorsolateral corticospinal tract as well as to both the crossed and the uncrossed ventral corticospinal tract. The primary somatosensory cortex (area 3a, 3b, 1–2, 5a, 5b) as well as the secondary somatosensory cortex (area 2 pre-insularis), on the other hand, were found to contribute fibers mainly to the crossed dorsolateral tract. Area 4 was found to display a further organization, such that it contains a medial and a lateral part, both of which contribute mainly fibers to the crossed dorsolateral tract, while the remainder of area 4 contributes fibers to the crossed and uncrossed dorsolateral as well as to the crossed and uncrossed ventral tracts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236659
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  • 25
    Electronic Resource
    Electronic Resource
    Functional amblyopia in kittens with unilateral exotropia (1980)
    Springer
    Experimental brain research 40 (1980), S. 305-310 
    Details
    ISSN: 1432-1106
    Keywords: Squint amblyopia ; Visual cortex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In two dark reared, 40 day old kittens unilateral divergent squint was induced be resecting the insertion of the medial rectus muscle. Behavioural testing revealed that the kittens used only the normal eye for fixation. Contrast sensitivity functions of the two eyes and visual acuity were determined behaviourally in a jumping stand whereby the kittens had to discriminate sine-wave gratings or variable spatial frequency and contrast from a flux equated homogeneous field. At photopic luminance levels the deviated eye showed a significant deficit in both kittens. This impairment was apparent over the whole range of spatial frequencies (0.18–0.99 c/deg) except for the lowest spatial frequency in one kitten. The interocular difference of visual acuity disappeared at scotopic luminance levels. In subsequent electrophysiological experiments contrast sensitivity functions were determined from cortical evoked potentials that were elicited by phase reversing square wave gratings. Comparison between behavioural and electrophysiological results revealed a very good correspondence between the two sets of data. It is concluded that exotropia without alternating fixation leads to functional amblyopia of the deviated eye.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237795
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  • 26
    Electronic Resource
    Electronic Resource
    Physiological responses of cat vestibular nerve to a selective mechanical stimulation of the lateral crista ampullaris (1980)
    Springer
    Experimental brain research 40 (1980), S. 358-360 
    Details
    ISSN: 1432-1106
    Keywords: Mechanical stimulation ; Cristae ampullares ; Vestibular ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present report describes a bidirectional mechanical stimulation technique of cristae ampullares in the cat. Bimodal field potentials are seen in the vestibular nerve and nucleus after an excitatory stimulus. This technique should allow an in vivo and selective study of the vestibular receptors in mammals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237804
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  • 27
    Electronic Resource
    Electronic Resource
    A statistical analysis and comparison of soma diameter spectra for classical neurones from different regions of the cat retinal ganglion cell layer (1980)
    Springer
    Pflügers Archiv 388 (1980), S. 239-242 
    Details
    ISSN: 1432-2013
    Keywords: Statistical model ; Cat ; Retina ; Ganglion cell layer ; Neuronal diameter spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Multimodal soma diameter spectra for neurones of the cat retinal ganglion cell layer have been represented by three subpopulations of independent, normal diameter distribution. Recurrent computation according to the technique of Vibert and Caille (1978) has extracted best fit populations for samples from various regions of central and peripheral retina. The model subpopulations from all these regions did not differ significantly in their relative proportions or variance. Significant progressive variation between subpopulations representing different regions of retina were observed only in the mean diameter of the α and β mode cells. The parameters of the γ mode population were statistically uniform across the retina. The cat retina thus appears to be more homogeneously organized than has been suggested elsewhere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00658488
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  • 28
    Electronic Resource
    Electronic Resource
    The effects of phenylmethanesulfonyl fluoride on delayed organophosphorus neuropathy (1980)
    Springer
    Archives of toxicology 46 (1980), S. 305-311 
    Details
    ISSN: 1432-0738
    Keywords: Cat ; Neurotoxic esterase ; Diisopropylfluorophosphate ; Phenylmethanesulfonyl fluoride ; Neuropathy ; Prevention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A delayed localized neuropathy of peripheral nerves in a single hind leg of the cat develops after a single intraarterial 2 mg/kg injection of diisopropylfluorophosphate (DFP). This neuropathy is manifested by a maximum loss of the capacity of soleus α-motor nerve terminals to generate stimulus-bound repetition 21 days after DFP exposure. Phenylmethanesulfonyl fluoride (PMSF) is a protective inhibitor of the neurotoxic esterase which is associated with the development of the delayed organophosphorus neuropathy. Pretreatment of cats with PMSF (30 mg/kg i.p.) 24 h before the DFP injection protected the cats from the delayed neuropathy. No clinical neurotoxic signs were observed at 21 days after DFP. The stimulus-bound repetitive capacity of soleus α-motor nerve terminals was not lost at this time and its incidence was much greater than that which occurred in cats not pretreated with PMSF.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310448
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  • 29
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    Electronic Resource
    Veränderungen im Sehsystem der Katze nach Netzhautläsionen (1980)
    Springer
    European archives of psychiatry and clinical neuroscience 228 (1980), S. 117-133 
    Details
    ISSN: 1433-8491
    Keywords: Afferent visual system ; Retinal lesions ; Functional neuroplasticity ; Cat ; Afferentes Sehsystem ; Netzhautläsionen ; Funktionelle Neuroplastizität ; Katze
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei erwachsenen Katzen wurden Schichten des Corpus geniculatum laterale (CGL) vollständig oder teilweise durch monoculäre, genau definierte Photokoagulatorläsionen der Netzhaut deafferentiert. Mit Mikroelektroden wurden Einzelneurone aus einer experimentell veränderten Schicht mit Kontrollneuronen aus einer normalinnervierten Schicht des CGL eines Versuchstieres verglichen. Nach Unterbrechung aller Afferenzen eines Auges durch Photokoagulation stieg die anfangs stark verringerte Spontanaktivität in der deafferentierten Schicht an, ohne normale Entladungsraten innerhalb von 10 Wochen wieder zu erreichen. Das Muster von Erregung und Hemmung nach Lichtreizung des nicht-dominanten, gesunden Auges hatte sich zu dieser Zeit völlig verändert. Bei begrenzten, nasalen Netzhautläsionen fanden sich beginnend etwa 27 Tage nach der Koagulation in den Randbezirken der partiellen, visuellen Deafferentierung lichterregbare Zellen mit verschobenen rezeptiven Feldern, denen eine läsionsinduzierte Erregungsausbreitung um maximal 200 μm im CGL zugrunde lag. Kleine, runde Netzhautläsionen bedingten anfänglich eine vollständige, visuelle Deafferentierung eines bestimmten CGL-Bezirks. Nach 30 und mehr Tagen wurde visuelle Erregung aus der normal innervierten Umgebung an Zellen gefunden, die in den ersten Tagen nach der Koagulation unerregbar waren. So wurde bei unveränderter Größe der retinalen Läsion ihre Repräsentation im CGL deutlich verkleinert. Die Befunde weisen im subcorticalen visuellen System der erwachsenen Katze auf läsionsinduzierte Reorganisation hin, die das System zu einer gewissen Kompensation nach Verlust visueller Eingänge befähigen könnte. Eine Übertragbarkeit der Befunde auf die Humanpathophysiologie wird kritisch diskutiert.
    Notes: Summary Layers of the lateral geniculate nucleus (LGN) of mature cats were completely or partially deafferentated by precisely defined photocoagulation of the retina. Single neuron recordings were performed with microelectrodes from an experimentally modified layer and compared with neurons from a normally innervated layer in the same animal. The spontaneous activity of cells after monocular deafferentation was severely reduced in the beginning and increased subsequently without reaching normal values within ten weeks. At this time the pattern of excitation and inhibition after light stimulation of the nondominant unsevered eye had completely changed. Twenty-seven days and later after coagulation of a part of the nasal retina light-excitable cells with displaced receptive fields were found in the LGN in the border region of the partial visual deafferentation. This indicated a lesion-induced lateral expansion of excitation by up to 200 μm within the LGN. Small, round retinal lesions initially caused a complete visual deafferentation of a certain region in the LGN. After 30 days and later visual excitation from the normally innervated surrounding was observed in cells which were not light-excitable during the first days after coagulation. Thus, while the retinal lesion itself did not substantially change, its representation within the LGN was distinctly reduced. The results indicate lesion-induced reorganization in the subcortical visual system of the adult cat. This might enable the system to a certain degree of compensation after loss of visual inputs. The transferability of these results to human pathophysiology has to be critically considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00365600
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  • 30
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    Electronic Resource
    Dopamine-induced diuresis in the cat without changes in renal hemodynamics (1980)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 312 (1980), S. 77-83 
    Details
    ISSN: 1432-1912
    Keywords: Dopamine ; Diuresis ; Renal blood flow ; Sympathetic activity ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of intravenous (i.v.) and intraarterial (i.a.) injection and infusion of dopamine (DA) on renal hemodynamics, regional sympathetic activity and kidney function were investigated in anaesthetized cats. In response to the i.v. bolus injection of DA (25 μg/kg), mean arterial blood pressure (MABP) was increased by 19.7%, renal blood flow (RBF) by 16.6%, and regional sympathetic discharges were inhibited. The principal effect of i.a. bolus injection of DA into the renal artery was vasoconstriction. Vasodilation was observed neither after lower doses of DA nor after pretreatment with phenoxybenzamine. During continuous i.v. infusion of 10 μg DA kg−1 min−1 MABP, RBF, renal sympathetic discharges and glomerular filtration rate (GFR) did not change, whereas urine volume was increased by 120.5%, sodium excretion by 99.7%, chloride excretion by 143.2%, and potassium excretion by 31.9%. Urine osmolality was decreased and osmolal clearance increased. Raising the DA dose to 25 μg kg−1 min−1 resulted in a fall of GFR, but the diuretic response was not significantly different from that of the low dose. Bulbocapnine (6 mg/kg i.v.) antagonized the DA-induced diuresis. In conclusion, the diuretic effect of DA in the cat is not dependent on a change in RBF, GFR or renal sympathetic activity. This suggests that a tubular site of action is primarily responsible for DA diuresis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00502578
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  • 31
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    Electronic Resource
    Central blood pressure effects of guanylyl-imido-diphosphate and cyclic guanosine-monophosphate (1980)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 312 (1980), S. 31-35 
    Details
    ISSN: 1432-1912
    Keywords: Central blood pressure control ; Cat ; Guanylyl-imido-diphosphate ; Cyclic guanosine monophosphate ; Intracerebroventricular administration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Injections of guanylyl-imido-diphosphate (250, 500 and 1,000 μg/kg) into the lateral cerebral ventricle of the anaesthetized cat induced increases in blood pressure and heart rate while the intravenous injections of the same doses were ineffective, thus indicating a central mechanism of action of this compound which activates adenylcyclase at the catalytic subunit. The results support the hypothesis that the activity of cardiovascular centres depends on the prevailing concentration of cAMP. Intracerebroventricular injection of cGMP (125, 250 and 500 μg/kg) caused hypotension and bradycardia. The effects increased with the dose but were subject to tachyphylaxis. The lack of an effect after intravenous administration indicates a central site of action. This result is in agreement with the Yin Yang hypothesis and suggests that cGMP is a second transmitter in cardiovascular centres which may be involved in central cardiovascular effects in response to stimulation by putative neurotransmitter substances such as acetylcholine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00502571
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  • 32
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    Hereditary deafness in the cat: An electron-microscopic study of the tectorial membrane (1980)
    Springer
    European archives of oto-rhino-laryngology and head & neck 229 (1980), S. 55-68 
    Details
    ISSN: 1434-4726
    Keywords: Erbliche Taubheit ; Katze ; Elektronenmikroskop ; Membrana tectoria ; Hereditary deafness ; Cat ; Electron microscopy ; Tectorial membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The tectorial membrane is affected at an early stage of the cochlear degeneration in the hereditarily deaf white cat. The membrane first descends towards the organ of Corti with obliteration of the intervening sub-tectorial space in the basal coil during the second post-natal week. Both the microvilli of supporting and Hensen's cells, and the hair cell stereocilia make deep indentations on the under-surface of the membrane. Cells are found insinuated between the tectorial membrane and Corti's organ, and numerous cellular processes occur within the former. A phagocytic function would appear probable for these cells, which seem to originate from the internal sulcus region. The membrane is retracted into the latter around the 2-month stage. At all ages, small spherical structures, which may represent altered interdental cell secretions, are found within the membrane, these becoming calcified in older animals.
    Notes: Zusammenfassung Veränderungen in der Membrana tectoria treten in einer frühen Phase der cochlearen Degeneration bei der weißen Katze mit erblicher Taubheit auf. Die Membran bewegt sich erst gegen das Cortische Organ mit Obliteration des dazwischenliegenden subtectorialen Raumes in der zweiten postnatalen Woche. Sowohl die Mikrovilli der Hensenschen Zellen und die der Stützzellen als die Stereozilien der Haarzellen machen tiefe Eindrücke auf der Unterseite der Membran. Zellen sind zwischen Membrana tectoria und dem Cortischen Organ gefunden, und viele zellulare Prozesse entstehen innerhalb Membrana tectoria. Eine phagocytotische Funktion würde für diese Zellen möglich sein, die aus der Region des Sulcus internus zu stammen scheinen. Bei älteren Tieren ist die Membran gegen den Sulcus internus retraktiert. Für alle Altersstufen findet man kleine spherischen Strukturen, die veränderte interdentale Zellensekrete vertreten können. Diese Strukturen werden innerhalb der Membran gefunden, und sind bei älteren Tieren verkalkt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00453752
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  • 33
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    Electronic Resource
    Reversion of the B to A transition of DNA induced by specific interaction with the oligopeptide distamycin A (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 823-831 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of the DNA-binding oligopeptide distamycin A on the B to A transition of DNA in ethanol/water solutions has been studied by means of CD. (The overbars indicate that it does not matter which particular form of the corresponding families is considered.) The results show that increasing the concentration of distamycin A reverses the A conformation (in 82% ethanol) to the B conformation due to its strong binding and stabilization of the latter. In accordance with previous data for pure aqueous solutions, a site size of 3.5 base pairs is obtained from the studies in water/ethanolic solutions. From the data on the B to A transition in the presence of distamycin A, we estimated the length of the cooperativity ν0 = 10 base pairs.The results demonstrate that the oligopeptide systems of distamycin, as well as those of netropsin, are effective stabilizers of the DNA B-conformation.
    Additional Material: 6 Ill.
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    NMR evidence for a type I β-turn in (Pro2)-tetrapeptides and interdependence of cis:Trans isomerism, ring flexibility, and backbone conformation (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 781-804 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrapeptides with proline in position 2, asparagine or leucine in position 3, and glycine in positions 1 and 4, with end groups free or blocked on the N-terminal side, were studied in their various ionic states in 2H2O and in Me2SO-d6 by 1H- and 13C-nmr. In order to clarify or refine some details, successive substitutions of the residues in these peptides with amino acids enriched to 85% in 13C, or to 85% 13C plus 97% 2H were carried out. The 1H and 13C chemical shifts as well as the 1H-1H, 13C-13C, and 13C-1H coupling constants and the signal intensities show strong similarity of behavior between the tetrapeptides of asparagine and leucine. The main conformational characteristics are (1) the almost total stabilization of the trans conformer in the type I β-turn structure when the peptide is in the zwitterion state dissolved in Me2SO. This is deduced from the 3JC3αH-N3H and the 3JC2′-H3α coupling constants, which both furnish a dihedral angle of φ3 = -90°, and from the positive value of the temperature coefficient of the glycine-4 amide protons, which suggests a type 4 → 1 hydrogen bond; (2) the evolution of cis and trans isomer fractions which change with the ionic state of the peptides in Me2SO, whereas they remain constant in aqueous solution; and (3) the conformation of the pyrrolidine ring as it follows the variations in cis:trans isomer populations together with the side-chain rotamer fractions of the residue in position 3. In the β-turn conformation the isomer cis is less abundant and the pyrrolidine ring is more flexible; this explains the perfect accommodation of the proline residue in position 2 of a bend. The interdependence of these phenomena where interactive forces play a predominant role underlines the importance of cooperative effects in the molecule. The results also suggest that the cis isomer of proline can adapt itself just as well as the trans isomer to position 2 of a type I β-turn.
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    Transport properties of particles with segmental flexibility. II. Decay of fluorescence polarization anisotropy from hinged macromolecules (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 913-930 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An algorithm is presented for the Monte Carlo simulation of the decay of fluorescence polarization from segmentally flexible molecules. Based on the random walk model of Brownian motion, the treatment explicitly follows the stochastic changes in the diffusion coefficients as the molecule bends. It includes the effects of a linear restoring force opposing the bending and the effects of hydrodynamic coupling between the translational, rotational, and bending motions. One application is presented: the simulation of anisotropy decay curves for hinged rods. A variety of decay curves are obtained, including single- and multiexponential behavior, and the following conclusions are reached: (1) increasing the flexibility is usually, but not always, accompanied by a more rapid rate of depolarization; (2) reducing the size of the fluorescent subunit will usually, but not always, increase the rate of depolarization; and (3) the complex interplay between the effects of molecular shape, relative sizes of the subunits, restoring force, and orientation of the transition dipoles renders it unlikely that any simple method can be used to interpret anisotrophy data without simulation. In particular, it is not possible to determine the extent of bending by fitting the data with the two-exponential approximation used by some investigators in the past.
    Additional Material: 6 Ill.
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    13C-nmr spectroscopy of red algal galactans (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 977-990 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C-nmr spectra of red seaweed galactans, belonging to the agar and carrageenan groups or having the “intermediate” type of structure, were interpreted on the basis of 13C-nmr spectra of model compounds. Signal assignments have been made for most of the known extreme structures of such galactans. 13C-nmr spectroscopy was shown to be a rapid and convenient method of structural analysis, which permits one to determine the type of galactan structure, the absolute configurations of its constituents (galactose and 3,6-anhydrogalactose), and the positions of the sulfate and O-methyl groups in a polysaccharide molecule.
    Additional Material: 3 Ill.
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    Dielectric changes in hyaluronate solutions at microwave frequencies as a function of concentration, system pH, and temperature (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 931-944 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dielectric response of human umbilical cord hyaluronic acid in various environments has been studied at microwave frquencies using a resonant microwave cavity as a probe. Both the real and imaginary parts of complex dielectric constant and the loss tangent for hyaluronate solutions are obtained by utilizing equations for perturbation of a resonant cavity. Dielectric changes at room temperature have been observed in aqueous solutions of hyaluronic acid as a function of concentration ranging from 0 to 350 mg/ml. The data indicate the existence of ordered phases in hyaluronate solutions at selective concentrations, that is, exhibiting lyotropic-type transitions. Hyaluronate solutions at 1.5 and 3 mg/ml concentrations have been studied at various pH in the range of 6-8 and at constant ionic strength 0.1. A temperature-dependent transition in hyaluronate solution of 120 mg/ml concentration has been observed at physiological temperature. It is shown that this temperature-dependent behavior can be related to the orientational polarizability term in the Debye theory of polar molecules in liquids.
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    A quantitative test of Zimm's model for the rotor-speed-department sedimentation of linear DNA molecules (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 945-964 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In 1974, Zimm described a theory which predicts that the sedimentation coefficient of high-molecular-weight DNA will decrease as the rotor speed of measurement increases. In 1979, this theory was revised, and the new formula predicts speed-dependence effects that are substantially smaller than the predictions of the original version. This report describes the results of subjecting both the original and the revised versions of the theory to quantitative tests using a well-defined sucrose-gradient system and a DNA of known molecular weight (T4c DNA). T4c bacteriophage is a mutant, whose DNA contains the unmodified base cytosine, instead of the glucosylated hydroxymethylcytosine characteristic of the T-even bacteriophages, and has a molecular weight of 115 ± 3 × 106. The DNA of the wild-type phage (T4D+) was also used in some experiments.In addition to the quantitative tests, the experiments test for an effect first observed by Rubenstein and Leighton, which showed that the sedimentation coefficient measured for T2 DNA depended on the composition of the centrifuge tube used for the measurement (tube composition effect). It can be inferred from this observation that an interaction occurs between particle and tube wall during sedimentation, and this leads to a reduction in sedimentation velocity independent of the reduction in S described by Zimm's theory.The results show that in the range of 25,000-50,000 rpm, the original but theoretically incorrect form of the theory quite accurately describes the sedimentation behavior of both T4c and T4D+ DNA, although T4D+ was a special case in some respects. The revised (corrected) form of the theory predicts much less of a speed-dependence effect than that actually observed. The discrepancy between corrected theory and observation suggests that other factors (perhaps arising from the use of the swinging bucket rotor geometry) are causing the additional observed reduction in S20,w. However, the experiments show that the tube composition effect does not seem to be one of these.
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    Proton NMR study of the interaction of cis-dichloro-diamine-platinum(II) with poly(I) and poly(I)·poly(C) (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1299-1309 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fixation of cis (NH3)2Cl2Pt(II) to poly(I)·poly(C) leads to the formation of two complexed species. One involves coordination to a single base (accounting for about 70% of the total platinum bound over the rb range 0.07-0.25) and the other to two bases which are not adjacent to each other but may be on the same strand and separated by a loop. Reaction of the platinum compound with poly(I) gives in addition to the above two species a minor one (about 15%, independent of rb over the range 0.05-0.30) in which the platinum is bound to two adjacent bases. The availability of such coordination reduces the dominance of the 1:1 species, which, however, remains the major one (ca. 55%).
    Additional Material: 3 Ill.
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    Heavy-atom effects associated with methylmercury (II) binding to rabbit glyceraldehyde-3-phosphate dehydrogenase (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1329-1344 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complex of CH3Hg(II) with the accessible cysteines of glyceraldehyde-3-phosphate dehydrogenase (GAPD, EC 1.2.1.12) from rabbit muscle has been studied by phosphorescence and optically detected magnetic resonance (ODMR) spectroscopy. The wavelength dependence of the phosphorescence decay kinetics has also been measured. Comparison of CH3Hg(II)-GAPD with GAPD by these methods shows that a specific optically resolved tryptophan site of GAPD is perturbed by the interaction with a nearby mercury atom. The perturbation on the luminescence and ODMR properties is typical of an external heavy-atom effect. Based on the x-ray diffraction structure of the lobster enzyme, it is proposed that the heavy-atom effect results from the interaction of tryptophan-310 with CH3Hg(II) bound to cysteine-281 in the rabbit muscle enzyme.
    Additional Material: 7 Ill.
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  • 41
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    Interaction of spermine with different forms of DNA. A conformational study (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1415-1434 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The energy of interaction of a spermine molecule with the A- and B-forms of DNA has been calculated, assuming that the molecule of spermine is fixed in the narrow groove of the DNA helix with the formation of hydrogen bonds between the amino groups of spermine and the phosphate groups of DNA. The atom-atom potentials method was used. Optimal structures for the A-DNA-spermine and B-DNA-spermine complexes are suggested. It is shown that, in agreement with the experimental data, the interaction of the spermine molecule with the A-DNA is energetically more favorable than that with the B-DNA. Two main factors are responsible for this: (1) the distance between neighboring phosphates of the chain in A-DNA (which is about 1 Å less than that in B-DNA) corresponds better to the distance between the amino groups of the propyl part of spermine; and (2) the orientation of phosphate groups in A-DNA inside the groove is preferable for complex formation with spermine to the outside groove arrangement of the phosphates in B-DNA. These conclusions are further confirmed by the calculations for DNA-propane diamine complexes.
    Additional Material: 7 Ill.
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    Crystal and molecular structure of isoleucinomycin, cyclo[-(D-Ile-Lac-Ile-D-Hyi)3-](C60H102N6O18) (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1517-1534 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of a synthetic analog of valinomycin, cyclo[-(D-Ile-Lac-Ile-D-Hyi)3-] (C60H102N6O18), has been determined by x-ray diffraction procedures. The crystals are orthorhombic, space group P212121, with cell parameters a = 11.516, b = 15.705, c = 39.310 Å, and Z = 4. The atomic coordinates for the C, N, O atoms were refined in the anisotropic thermal motion approximation and for the H atoms in the isotropic approximation. Values of standard (R) and weighted (Rw) reliability factors after refinement are 0.073 and 0.056, respectively. The structure is completely asymmetric. The cyclic molecular backbone is stabilized by six intramolecular hydrogen bonds N—H…O=C, five bonds being of the 4→1 type and one being of the 5→1 type. The side chains are located on the molecular periphery. The conformational state of isoleucinomycin in the crystal is intermediate between the corresponding crystalline states of valinomycin and meso-valinomycin. The observed conformation suggests that complexation could proceed via entry of the ion at the face possessing the L-Lac residues, the less crowded face.
    Additional Material: 5 Ill.
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    Conformational analysis of the milk oligosaccharides (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1555-1566 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Possible conformations of lacto-N-tetraose, lacto-N-neotetraose, related disaccharides, and other milk oligosaccharides have been studied by an energy-minimization procedure using empirical potential functions. Lacto-N-tetraose favors a “curved” conformation, while lacto-N-neotetraose favors an approximately “straight” conformation. These two conformations differ mainly in the position of the terminal galactose residue with respect to the rest of the molecule. This difference explains the greater strength of lacto-N-neotetraose compared with lacto-N-tetraose in its ability to inhibit the cross-reaction of blood group P1 fractions with Type XIV pneumococcal antipolysaccharide. Although the favored conformation of lacto-N-tetraose (inactive) agrees with the model proposed by the earlier workers, that for lacto-N-neotetraose (active) differs. The favored conformations for the disaccharides galactose-β(1-4)-N-acetylglucosamine, galactose-β(1-3)-N-acetylglucosamine, and lactose are similar in overall shape, differing only in the nature and orientation of the side groups. This explains their nearly equal inhibitory activity. These theoretical models also explain the increased activity of lacto-N-fucopentaose I over that of lacto-N-tetraose and the relative activities of the substituted lactoses. The present studies suggest that it is the overall shape of the molecule which is important for activity, rather than the terminal β(1-4)-linked galactose residue alone.
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    Influence of methanol on the rotational diffusion of poly(L-lysine) in the helix-coil transition (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1571-1585 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C spin-lattice relaxation times of poly(L-lysine) have been obtained at 67.9 MHz in aqueous solution and in a mixed solvent (40% methanol/60% water). A concomitant determination of the conformation by CD permits the correlation of conformation and rotational diffusion of the polymer. The dependence on pH of the spin-lattice relaxation times of the 13Cα and the side-chain carbon resonances reflects the diffusional motion in the random-coil conformation, in the helix-coil transition, and in the conformation of the α-helix. In the mixed solvent the reorientational correlation time of the Cα-Hα vector increases from τ = 0.37 nsec (random coil) to τ = 12.0 nsec (α-helix). In aqueous solution the correlation time of this vector increases from τ = 0.33 nsec (random coil) to τ ≫ 11 nsec. The reorientation rates of the side-chain methylene groups in the two solvents are markedly different. The reorientation of all methylene groups is reduced in the mixed solvent.
    Additional Material: 7 Ill.
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  • 45
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    Solid-state conformation of copolymers of β-benzyl-L-aspartate with L-alanine, L-leucine, L-valine, γ-benzyl-L-glutamate, or ∊-carbobenzoxy-L-lysine (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1603-1615 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solid-state conformation of copolymers of β-benzyl-L-aspartate [L-Asp(OBzl)] with L-leucine (L-Leu), L-alanine (L-Ala), L-valine (L-Val), γ-benzyl-L-glutamate [L-Glu(OBzl)], or ∊-carbobenzoxy-L-lysine (Cbz-L-Lys) has been studied by ir spectroscopy and circular dichroism (CD). The ir spectra in the region of the amide I and II bands and in the region of 700-250 cm-1 have been determined. The results from the ir studies are in good agreement with data obtained by CD experiments. Incorporation of the amino acid residues mentioned above into poly[L-Asp(OBzl)] induces a change from the left-handed into the right-handed α-helix. This conformational change for the poly[L-Asp(OBzl)] copolymers was observed in the following composition ranges: L-Leu, 0-15 mol %; L-Ala, 0-32 mol %; L-Val, 0-8 mol %; L-Glu(OBzl), 3-10 mol %; and Cbz-L-Lys, 0-9 mol %.
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    Physical aging of dry elastin (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1667-1673 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dry purified ligamentum nuchae elastin has been investigated for physical aging. The samples were quenched from a temperature (197°C) close to the softening point to a number of measuring temperatures ranging from -20 to +180°C. At each temperature, the small-strain torsional creep properties were determined at a number of elapsed intervals after the quench. Aging effects were found over the whole temperature range, and the creep and aging behavior of elastin turned out to be very similar to that of synthetic polymers.
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    DNA backbone conformation in cis-syn pyrimidine[]pyrimidine cyclobutane dimersPresented at the American Society of Biological Chemists and Biophysical Society Meeting, June 1-5, 1980, New Orleans, Louisiana [(1980) Fed. Proc. 39, 1879]. (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1695-1701 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1980.360190913
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    Toroidal elastic supercoiling of DNA (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1705-1713 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Covalently closed circular DNA can exist in different configurations known as circular, toroidal, and interwound. Changes among these forms can be made in several ways, including the insertion of dye molecules between adjacent base pairs, which tends to untwist the double-helical structure. The aim of this paper is to discuss these configurations, and the changes among them, in the context of classical elastomechanics. The concepts of twisting, linkage and writhing are explained. Simple experiments on a twisted linear-elastic rod are described, and it is shown that although the circular and interwound forms may be modeled in this way, the toroidal form does not occur, being mechanically unstable. Theoretical energy calculations by Levitt on bent and twisted DNA show that DNA exhibits a particular kind of nonlinear elasticity in which there is an unusual coupling between bending and twisting. The aim of the paper is to show qualitatively that this special kind of elasticity can stabilize the toroidal form of closed circular DNA.
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    Physicochemical investigation of k-carrageenan in the random state (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1357-1374 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Light-scattering, viscosity, and sedimentation experiments on aqueous solutions of k-carrageenan show that this sulfated polygalactose is an expanded flexible random coil. This expansion is due to long-range interactions that are predominantly electrostatic. Extrapolation of viscosity data to infinite ionic strength provided values for the intrinsic viscosity which were subjected to the Stockmayer-Fixman analysis, giving a value for the Mark-Houwink coefficient under theta-conditions, Kθ, of 0.27. The characteristic ratio, C∞, under these conditions is 7.8, and the conformation factor σ is 2. In a solution of 0.118 ionic strength, where a Mark-Houwink exponent aη of 0.86 is found, the radii of gyration calculated from viscosity data are lower than those found from the angular dependence of scattered light. On the other hand, the radius of gyration found from the sedimentation rate agrees well with the light-scattering radius. The relations between molecular parameters are corrected for the poly-dispersity of the sample.
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    An interaction of albumin with hyaluronic acid and chondroitin sulfate: A study of affinity chromatography and circular dichroism (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1407-1414 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
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    Masthead (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980) 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190801
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    The translational friction of toroids (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1475-1489 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An approximate analytic expression for the translational friction coefficient of a toroid modeled as a continuous shell of frictional elements is derived using the Kirkwood approximation. The accuracy of this expression was determined by comparing the friction coefficients predicted by it to those predicted by extrapolated shell-model calculations using the modified Oseen tensor. To show that these calculations do indeed yield the correct friction coefficients, actual translational friction coefficients were determined by observing settling rates of macroscopic model rings or toroids in a high-viscosity silicone fluid. Our conclusion is that the approximate expression yields friction coefficients that are about 1.5-3% low for finite rings. For thin rings, a comparison is also made with the exact result of Yamakawa and Yamaki [J. Chem. Phys. 57, 1572 (1972); 58, 2049 (1973)] for the translational friction of plane polygonal rings. This comparison shows that the approximate expression yields results which are low by 2-3% unless the rings are extremely thin, in which case the error is larger. In the limit of an infinitely thin ring the approximate expression reduces to the Kirkwood result [J. Polym. Sci. 12, 1 (1954)], which is low by 8.3%. We discuss briefly how this work may be useful in determining the structure of DNA compacted by various solvent-electrolyte systems and polyamines.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1980.360190805
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    Dynamic light scattering studies of internal motions in DNA. II. Clean viral DNAs (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1451-1474 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Internal Brownian motions of clean φ29 and λ-DNAs have been studied using photon-correlation techniques at both visible (λ0 = 632.8 nm) and uv (λ0 = 363.8 nm) wavelengths. The present dynamic light scattering data, which extend to K2 = 19 × 1010 cm-2, can in every case be satisfactorily simulated by a Rouse-Zimm model polymer with an appropriate choice of the three model parameters. The effects of pH, salt concentration, single-strand breaks, and molecular weight on those model parameters have also been investigated. Intact clean DNAs exhibit surprisingly little variation with pH from 7.85 to 10.25, with salt concentration from 0.01 NaCl to 5.4M NH4Cl, or with molecular weight or GC content. The single-strand breaks have no effect at pH 9.46, but produce dramatic changes in the model parameters at pH 10.0 and 10.25, indicating the introduction of titratable joints at those pHs. The failure of either single-strand breaks or a large change in GC content to alter the model parameters in the neutral pH range is a strong indication that local denaturation is not required for those flexions and torsions that dominate the relaxation of fluctuations in the scattered light. The Langevin relaxation time for the slowest internal mode of a particular Rouse-Zimm model derived from the dynamic light scattering data is compared with pertinent literature data extrapolated to the same molecular weight. The present algorithm for determining model parameters from the light-scattering Dapp vs K2 curve actually yields a Langevin time in fairly good agreement with the literature value. For unknown reasons the light-scattering D0 values generally exceed those obtained from the molecular weight and sedimentation coefficient by about 20%.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1980.360190804
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    Ultraviolet Raman spectroscopy of polyribouridylic acid: Excitation profile of the hypochromism induced by order-disorder transition (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1507-1515 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Raman spectra of polyribouridylic acid excited in the uv region, from 363 to 290 nm, are reported. The conformational changes of the polymer from random coil to ordered structure with stacked bases at high and low temperature, respectively, are reflected by important changes in the Raman line intensities; this Raman hypochromism is itself a function of the excitation wavelength - its profile has been determined and shows negative values in the region of 290 nm (near resonance), i.e., hypochromism becomes hyperchromism. Thus the knowledge of the hypochromism excitation profile is important in following order-disorder transition of a polymer using resonance Raman spectroscopy. Theoretical attempts are proposed for explanation, involving not only the relative variations of the molar extinction coefficient on the order-disorder transition of the polymer, but also the damping factors of the vibronic levels. The theoretical curve is found to fit adequately the experimental data over the excitation range, using only the frequency of the O-O transition of uracil and a vibronic linewidth of 2200 cm-1.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1980.360190807
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    Interaction of poly(α-L-glutamic acid) and sodium poly(α-L-glutamate) with solvent components in water-2-chloroethanol mixtures (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 2177-2190 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preferential interaction of sodium poly(α-L-glutamate) and poly(α-L-glutamic acid) with the solvent components in water/2-chloroethanol mixtures has been determined using density-increment measurements. The degree of preferential interaction was deduced from the density increments at constant molality of 2-chloroethanol and at constant chemical potential of 2-chloroethanol. Sodium poly(α-L-glutamate) and poly(α-L-glutamic acid) are both preferentially hydrated in the whole range of solvent composition. A dehydration process occurs during the 2-chloroethanol-induced coil-to-helix transition of sodium poly(α-L-glutamate). This dehydration process was attributed to the release of some moles of water from the neighborhood of the peptide bond during the nucleation of the helix. After the conformational transition, sodium poly(α-L-glutamate) is solvated by one 2-chloroethanol molecule. The location of water and 2-chloroethanol molecules in the different parts of the residue (more polar and less polar portions) is also discussed.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1980.360191204
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    Effects of pD on ring-stacking interactions between dinucleoside phosphates and tryptamine (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 2223-2245 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complex formation between tryptamine and mononucleotides and dinucleoside phosphates containing adenine and/or cytosine has been studied at five pD's ranging from 1.1 to 7.4 by proton magnetic resonance spectroscopy. Chemical shifts of base ring protons and the ribose anomeric proton in the nucleotides and indole ring protons in tryptamine were monitored and their changes with pD and intermolecular interactions interpreted qualitatively. Stacked complexes were found to exist at all pD's in the range studied. Complex geometries differ depending on pD. An electrostatic interaction between the tryptamine amino group and the nucleotide phosphate group contributes to complex formation above pD 4 but is not strong enough to shift the dinucleoside phosphate equilibrium towards the unstacked conformer.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1980.360191207
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    Conformational energy studies on N-methylated analogs of thyrotropin releasing hormone, enkephalin, and luteinizing hormone-releasing hormone (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1943-1973 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Empirical conformational energy calculations have been carried out for N-methyl derivatives of alanine and phenylalanine dipeptide models and N-methyl-substituted active analogs of three biologically active peptides, namely thyrotropin-releasing hormone (TRH), enkephalin (ENK), and luteinizing hormone-releasing hormone (LHRH). The isoenergetic contour maps and the local dipeptide minima obtained, when the peptide bond (ω) preceding the N-methylated residue is in the trans configuration show that (1) N-methylation constricts the conformational freedom of both the ith and (i + 1)th residues; (2), the lowest energy position for both residues occurs around φ = -135° ± 5° and ψ = 75° ± 5°, and (3) the αL conformational state is the second lowest energy state for the (i + 1)th residue, whereas for the ith residue the C5 (extended) conformation is second lowest in energy. When the peptide bond (ωi) is in the cis configuration the ith residue is energetically forbidden in the range φ = 0° to 180° and ψ = -180° to +180°. Conformations of low energy for ωi = 0° are found to be similar to those obtained for the trans peptide bond. In all the model systems (irrespective of cis or trans), the αR conformational state is energetically very high. Significant deviations from planarity are found for the peptide bond when the amide hydrogen is replaced by a methyl group. Two low-energy conformers are found for [(N-Me)His2]TRH. These conformers differ only in the φ and ψ values at the (N-Me)His2 residue. Among the different low-energy conformers found for each of the ENK analogs [D-Ala2,(N-Me)Phe4, Met5]ENK amide and [D-Ala2,(N-Me)Met5]ENK amide, one low-energy conformer was found to be common for both analogs with respect to the side-chain orientations. The stability of the low-energy structures is discussed in the light of the activity of other analogs. Two low-energy conformers were found for [(N-Me)Leu7]LHRH. These conformations differ in the types of bend around the positions 6 and 7 of LHRH. One bend type is eliminated when the active analog [D-Ala6,(M-Me)Leu7]LHRH is considered.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1980.360191103
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    Interactions of molecules with nucleic acids. III. Steric and electrostatic energy contours for the principal intercalation sites, prerequisites for binding, and the exclusion of essential metabolites from intercalation (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 2067-2089 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Based on steric and electrostatic considerations, the prerequisites for binding to DNA via the intercalation mechanism are proposed. Steric contour energy curves are presented to demonstrate the region inaccessible to an intercalant. They are calculated with a 6-n (n = 14) potential. This method is a soft potential analog of an excluded-volume approach. Electrostatic contours on the steric surface illustrate the relatively positive and negative regions of the binding site. The principal intercalation sites, predicted to fit into B-DNA via a tetramer-duplex unit, and the unconstrained dimer-duplex units, obtained in crystal structures, are examined. These contours illustrate the requirements of size, conformation, and net atomic charges necessary for intercalation and optimum binding. Based on the limited space available for intercalation by the presence of the backbone and the maximum base-pair separation of 8.25 Å, an Essential Metabolite Exclusion Hypothesis is presented.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1980.360191110
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    The chiroptical properties of proteins. II. Near-ultraviolet circular dichroism of lysozymeTaken in part from the Ph.D. dissertation of W. J. G. (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 2191-2208 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A study of the near-uv CD spectrum of lysozyme was carried out in the presence and absence of the inhibitor tri-N-acetylglucosamine, and theoretical chiroptical calculations based on the tetragonal crystal structure of the enzyme and the enzyme-inhibitor complex were performed. The results of these calculations indicate that the near-uv CD spectrum of lysozyme can be adequately explained in terms of negative rotatory strengths arising from the tryptophan 1La (293-300 nm) and the disulfide n-σ* bands (250 rm), and positive rotatory strength contributions from the tryptophan 1Lb bands (291 nm) and the tyrosine 1Lb bands (275 nm). Contributions to the rotatory strength of each band were approximated in terms of specific interactions between chromophores. It was found that the rotatory strength of most of the near-uv transitions arises primarily from coupling interactions involving other side-chain chromophores and amide groups which are in close proximity. Changes which are observed in the lysozyme CD spectrum on binding of tri-N-acetylglucosamine may be explained in terms of changes in the rotatory strength which result from interactions of the 1La transitions of the active-site tryptophans with the acetamide groups of the inhibitor. The reasonable agreement which is found between the experimental and calculated rotatory strengths implies that the crystal conformation of lysozyme must resemble the solution conformation.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1980.360191205
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    Relationship between conformation and physicochemical properties of polypeptides. I. Synthesis of homo- and co-oligopeptides by the liquid-phase method (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 173-187 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the following oligo- and co-oligopeptides by the liquid-phase method is described: (L-Met)15 (I), [L-Glu(OBzl)]20 (II), (L-Val)8-Gly (IV), (L-Ile)8-Gly (V), (L-Ile)4-Gly-(L-Ile)4 (VI), (L-Ile)4-Pro-(L-Ile)4 (VII), (L-Met)5-L-Pro-(L-Met)5 (VIII), [L-Glu(OBzl)]7-L-Pro-[L-Glu(OBzl)]7 (IX). The oligomers are covalently bound to bifunctional polyethylene glycol (PEG) and monofunctional PEG-M of Mr 5 × 103-2 × 104. Analytical controls were carried out after each step of synthesis in order to ensure quantitative coupling yields. All products could be obtained in high purity as indicated by amino acid analysis, thin-layer chromatography and chiroptical methods. The solubility of the oligomers was strongly enhanced by the presence of the C-terminal PEG group, enabling conformational investigations in a variety of solvents. A significant relationship between conformation and physicochemical properties of the oligopeptides was observed. Oligomers with tendencies to adopt α-helical (I, II) or unordered structures (VI-IX) showed no pronounced change in solubility or coupling kinetics during chain elongation, whereas the onset of a β-structure (IV, V) was paralleled by a drastic decrease in solubility and reactivity of the terminal amino groups. Most notably, the insertion of a proline or glycine in the middle of a β-forming peptide chain (VI, VII) resulted in a considerable increase in solubility compared to the corresponding homo-oligomers. The impact of the conformational properties of a peptide chain on strategic considerations of peptide synthesis in solution is delineated.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/bip.1980.360190112
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    Circular dichroism and conformational analysis of the membrane-modifying peptide -N-t-Boc-(Aib-L-Ala)5-Gly-Ala-Aib-Pro-Ala-Aib-Aib-Glu-(OBzl)-Gln-OMe with respect to alamethicin (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 203-214 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational analysis of the CD spectrum is reported for the synthetic and membrane-modifying nonadecapeptide analog of alamethicin N-t-Boc-(Aib-L-Ala)5-Gly-Ala-Aib-Pro-Ala-Aib-Aib-Glu(OBzl)- Gln-OMe. The CD data are evaluated according to three different methods and are discussed with respect to those obtained from natural alamethicin and suitable models such as N-t-Boc-(Aib-L-Ala)7-OPOE, fragments of the synthetic nonadecapeptide, and the hexadecapeptide N-t-Boc-(Aib-L-Ala)5-Pro-Ala-Aib-Aib-Glu(OBzl)-Gln-OMe. The synthetic nonadecapeptide with the longer helical region exhibits membrane activities comparable to those of alamethicin, whereas the hexadecapeptide with the shorter helix is inactive.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1980.360190114
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    Masthead (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980) 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190201
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    Dynamic light scattering in a flow - a new method of particle anisotropy investigation (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 231-240 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper deals with the light scattering from particles rotating in a flow with a transverse velocity gradient. It is theoretically substantiated and experimentally proved that the scattered light spectrum contains reliable information of the particle configuration and dimensions. The proposed technique may prove also very promising for the analysis of particle polydispersion.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1980.360190203
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    Poly(ε-L-lysine): Synthesis and conformationPart of this work was presented at the International Symposium on Biomolecular Structure held in Madras, India, in January 1978. (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 219-229 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of poly(ε-L-lysine) is described. This is a poly(ε-amino acid) in which the ε-amino group of lysine is condensed with the α-carboxyl group to produce a chain backbone that is a variant of the usual one seen in proteins and the side chain is the α-amino group. Conformational studies of poly(ε-L-lysine) and its t-butyloxycarbonyl derivative suggest the likelihood of a chain order that is formally similar to the antiparallel pleated-sheet conformation of proteins.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1980.360190202
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    Contribution of electrodiffusion to the dynamics of electrically stimulated changes in mechanical properties of collagen membranesPresented at the Third International Congress of Biorheology, August 28-September 1, 1978, La Jolla, California. (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 241-262 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have studied the kinetics of oscillatory tensile forces in collagen membranes. These forces were generated by sinusoidal electric fields applied across the membrane. Both the magnitude and phase of the measured force changed with frequency over a three-decade range. The membrane-separated electrolyte baths had different ionic strength but identical non-isoelectric pH. Changes in intramembrane ionic strength due to the electric field were calculated over the same frequency range via an electrodiffusion model that was generalized to include convection and electrokinetic coupling. A comparison of the experimental and theoretical phases and amplitudes versus frequency suggests that electrodiffusion is the dominant rate-limiting process in this electromechanochemical transduction. These results are relevant to electrostatic interactions in connective tissues and to membrane-based filtration devices in which membrane permeability may be actively varied and controlled by an applied electric field.
    Additional Material: 8 Ill.
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    Heat capacity changes and partial molal heat capacities of some di- and tripeptides in water (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 263-272 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Integral enthalpies of solution of several dipeptides and tripeptides in water at low concentrations have been determined at 25 and 35°C. These data have been used to derive the changes in heat capacity on dissolution at infinite dilution ΔCp0 at 30°C. Limiting partial molal heat capacities ΔCp20 have been determined by combining ΔCp0 with Cp2 (heat capacity of pure solid peptides). Using the data on ω-amino acids and these peptides, the partial molal heat capacity of a peptide group —CONH— was semiquantitatively estimated.
    Additional Material: 6 Tab.
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    URL: http://dx.doi.org/10.1002/bip.1980.360190205
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    Heat capacities of transfer of some amino acids and peptides from water to aqueous urea solution (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 273-284 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Integral enthalpies of solution at low concentrations of several amino acids and peptides in 2 and 6M urea solutions have been determined at 25 and 35°C. These data have been used to derive the enthalpies of transfer (at 25 and 35°C) and heat capacities of transfer (at 30°C) of these amino acids and peptides from water to aqueous urea solutions. Furthermore, the enthalpies of transfer and heat capacities of transfer per CH2 group and per peptide group —CONH— have also been estimated. These results show that while the enthalpies and heat capacities of transfer per CH2 group are positive and negative, respectively, the reverse is true for —CONH— group. The implications of these results in the mechanism of the denaturation of proteins by urea are discussed.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1980.360190206
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    Studies on transfer ribonucleic acids and related compounds. XXVI.Paper XXV: Ohtsuka, E., Miyake, T. & Ikehara, M. (1979) Chem. Pharm. Bull. 27, 341-345. Circular dichroic properties of cyclic oligoribonucleotides and their linear counterparts (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 285-296 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The CD spectra of cUpUp, cCpCp, and cGpGp derived from DCC-catalyzed polymerization of the relevant protected ribonucleoside 3′-phosphates are described. Similar studies on Up, U 〉 p, and cUp, as well as cUpUpUp and cUpUpUpUp, are presented. The spectral properties of the cyclic oligomers are compared with those of the corresponding linear oligomers with terminal 3′-phosphates so as to demonstrate that disruption of normal right-handed base stacking is considerable in these RNA loops.
    Additional Material: 7 Ill.
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    Chemical synthesis of (1 → 2)-α-D-mannopyranan (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 297-309 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of 1,2-anhydro-3,4,6-tri-O-benzyl-β-D-mannopyranose proceeds in the presence of Lewis acids, cationic coordination catalysts, and strong bases. Debenzylation of the products yields oligomeric saccharides or low polymers. Polymerization in toluene by means of potassium alkoxide complexed with crown ethers leads to essentially stereoregular (1 → 2)-α-D-mannopyranan. The original derivatives have been characterized by optical rotation, viscosity, molecular weight, gel permeation chromatography, and spectrometry. The free polysaccharides have been characterized by optical rotation, molecular weight, and 1H- and 13C-nmr spectrometry and compared to yeast mannan hydrolysate oligomers.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1980.360190208
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    Physical association of two simple alkylators to some DNA sequences (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 311-324 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular mechanics calculations have been used to determine the preferred physical association sites of the known alkylating agent dimethyl aziridinium ion (Az+) and a CH3+ prototype test probe with B-form, tetrameric DNA sequences. Electrostatic interactions are most important in determining these preferential physical association sites. In turn, the intermolecular energy minima depend on the charge distribution assigned to the DNA sequence. However, for three reported DNA charge distributions, only two distinct sets of energy minima were obtained for the CH3+-like ion interacting with (G-C)4, (A-T)4, and [(G-C)·(A-T)]2 deoxyribonucleic acids. These minima correspond to physical association geometries in which the CH3+-like ion is near known alkylation sites. The results of the Az+ … [(G-C)·(A-T)]2 interaction are virtually identical to those found for the CH3+-like ion. Aqueous solvation energetics have little effect on the physical association of Az+ with [(G-C)·(A-T)]2.
    Additional Material: 6 Ill.
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    Chemical reactivity of protonated aziridine with nucleophilic centers of DNA bases (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 325-340 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of molecular orbital calculations, using MINDO/3 and CNDO/2L methods, have been used to characterize the chemical reaction of protonated aziridine with DNA nucleophilic base sites. The N-7 atom of guanine is found to be the preferred alkylation site only when the O-6 atom of guanine is involved in base-pair hydrogen bonding. Otherwise O-6 is the predicted major site of alkylation. This indirectly suggests that protonated aziridine alkylation processes involve base-paired DNA structures, since N-7 guanine is the observed major site of alkylation. Alkylation of N-3 adenine is predicted to be more favorable than chemical attack of the N-7 adenine position. Both of these sites, however, are predicted to be less reactive than N-7 of guanine. These chemical reactivity studies resolve alkylation specifically not achieved in the DNA-alkylator physical association calculations reported in the preceding paper.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190210
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  • 72
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    Conformational analysis of somatostatin and selected analogs in oriented polyoxyethylene by infrared dichroism (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 341-352 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Infrared dichroic studies and deuterium exchange measurements of somatostatin and some of its analogs incorporated in uniaxially oriented polyoxyethylene are described. Band positions and dichroic ratios in the N-H stretching and amide I and II regions are similar to those of flexible and nonordered peptides like valinomycin and poly[Glu(ONa)]. This information, together with fast deuterium exchange rates, suggests that somatostatin exists in a flexible nonordered conformation in polyoxyethylene. One analog, di-S3,14-acetamidomethyl dihydrosomatostatin, was found to exist in both nonordered and β-like conformations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190211
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  • 73
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    Monte carlo simulation of the solvent structure in crystals of a hydrated cyclic peptide (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 395-418 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Monte Carlo simulation of the structure of the 16 ordered and disordered waters in the unit cell of crystals of the cyclic peptide cyclo(-L-Ala-L-Pro-D-Phe)2 is reported. The water structure has been characterized in terms of the statistically averaged positions of the individual molecules, their root-mean-square movements about these positions, the probability of finding a water in a given spatial position in the crystal (probability maps), and examination of individual configurations of the system. In this way a picture is obtained of the water structure, including water orientations (hydrogen positions), the hydrogen-bonding network, and fluctuations in these structural features, to a degree hitherto unavailable either from experimental or theoretical studies. In addition, the variation in water structure in various peptide environments was studied and correlated with the energetics of the individual water molecules. Variations in the crystalline environment of different water molecules lead to energy differences of as much as 4-5 kcal/mol in their average energies. Similarly, differences are observed in the water-peptide and water-water components of the energy. Two different water potentials were tested. The results were compared with experimental data in terms of mean positions, root-mean-square movements, and the Fourier transform of the simulated water structure. The agreement factor (R factor) calculated from the theoretical water probability distribution was 18.8% compared to the x-ray value of 14.5%, and the value of 28% when the water is omitted.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190214
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  • 74
    Electronic Resource
    Electronic Resource
    Masthead (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190301
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  • 75
    Electronic Resource
    Electronic Resource
    Polymeric model system for protein-bilirubin interaction (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 445-448 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190217
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  • 76
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    Conformational flexibility of peptides containing α,β-unsaturated amino acid residues. I. Conformational analysis of N-acetyl-N′-methylamides of dehydroalanine and N-methyldehydroalanine (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 469-475 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational energy calculations on the N-acetyl-N′-methylamides of dehydroalanine and N-methyldehydroalanine indicate that their conformational behavior is very different from that of the corresponding saturated compounds. The conformational data in the literature from x-ray and nmr investigations on peptides containing α,β-unsaturated residues are discussed on the basis of these theoretical results.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190303
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  • 77
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    Synthesis and ordered structure of amphipatic block copolymers with a saccharide and a peptide block (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 493-507 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Amphipatic block copolymers (OβEb) with a hydrophilic saccharide block and a hydrophobic polypeptide block were synthesized. In these copolymers the saccharide block is the glyco-amino acid Oβ from ovomucoid and the peptide block (Eb) is a poly(γ-benzyl-L-glutamate) block. Copolymers OβEb exhibit, in the solid state and in Me2SO concentrated solutions, mesomorphic lamellar structures where the polypeptide chains are in an α-helical conformation. Depending on the molecular weight of the polypeptide block, three types of lamellar structures are obtained, and they differ by the mode of organization of the polypeptide chains in their lamellae and by the T or Y conformation of the saccharide block.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190305
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  • 78
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    Spectroscopic and equilibrium dialysis studies of poly(α-L-glutamic acid)-Cu(II) complexes in the pH range 4-7For the preceding paper of the Macromolecule-Metal Ion Complex series, see Macromolecules 12 (1979) in press. (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 477-491 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The formation of complex between the Cu2+ ion and poly(α-L-glutamic acid) [poly(Glu)] in 150 mM NaCl solutions was studied by uv-visible absorption and equilibrium dialysis methods at the mixing ratios of Glu residues to Cu2+, R, of 32, 16, and 8 and in the pH range 4-7. The results showed that more than 90% of Cu2+ ions bind to the poly(Glu) at pH 〉 4.9, but the bound Cu(II) begins to dissociate with a decrease in pH. The absorption spectra of bound Cu(II) varied with pH and R in a complicated manner. Three different component spectra were disclosed from the analysis of the pH dependence of the bound spectra. We concluded that poly(Glu)-Cu(II) complexes fall into three classes in the pH range 4-7, with the proportions of these complexes varying with both pH and R. The three complexes predominate either in the helix or extended-coil region, in the helix-coil transition region, or in the helix-aggregate region. The stability constant and binding mode of each Cu(II)-Glu complex were estimated from the dialysis data. With these results, the possible structure of each complex is discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190304
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  • 79
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    Nearest-neighbor and next-nearest-neighbor effects in the proton NMR spectra of the oligoribonucleotides ApGpX and CpApX (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 557-573 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The variable-temperature proton nmr spectra of the oligoribonucleotides in the series CpApX and the series ApGpX, X = A, G, C, U, together with the parent dimers CpA and ApG have been measured. A complete analysis of all the nonexchangeable base proton resonances and ribose H-1′ proton resonances was made. The presence of trends in the shielding abilities of the various bases at both the nearest-neighbor and next-nearest-neighbor positions were identified. The observed shieldings could be used to predict the chemical shifts of protons in related systems. Based on the empirical results from ribodinucleoside monophosphates, the temperature-dependent behavior of the J1′2′ coupling constants of the triribonucleotides suggested that the compounds in the CpApX series stacked from the 5′-end to the 3′-end, while those in the ApGpX series stacked from the 3′-end to the 5′-end.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190309
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  • 80
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    Monte carlo computation of the supercoiling energy, the sedimentation constant, and the radius of gyration of unknotted and knotted circular DNA (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 619-637 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Closed random Gaussian polygonal chains of N (6 〈 N 〈 150) bonds of equal length b and thickness d have been generated on a computer. The knot type, the writhing number w, the radius of gyration, and the average of the inverse of the distance between two apices have been determined for each chain. For all the studied knot types - 0, 31, 41, 51, and 52 - the probability density of finding a given w is Gaussian. The Gaussian is centered about 0 for the amphichiral knots. Therefore, for long circular DNAs, the contribution to the supercoiling energy, which depends on w only, may be considered as purely entropic and may be expressed as ARTw2/N, in agreement with previous semiempirical considerations. The parameter A increases with chain thickness, it decreases as N gets larger but rapidly reaches a plateau. Comparison with experimental data from the literature would suggest that the ratio of the writhing to the constraint increases with ionic strength. The ratio of sedimentation constant of the supercoiled DNA to the sedimentation constant of the nicked DNA varies as N1/4 (w/N)2, and therefore depends on the writhing density and on the length of the DNA.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190312
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  • 81
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    Application of band centrifugation to the study of the assembly of alfalfa mosaic virus (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 575-595 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A band-centrifugation method for the analysis of an assembly reaction of a simple virus from its RNA and protein is described. The experiment was carried out by sedimenting a band of viral RNA through a solution of depolymerized coat protein. The resulting radial distribution of the reaction products, followed as a function of time, was analyzed by a computer simulation of the series of reaction. This method is based on a numerical solution of the continuity equation for the sedimentation-diffusion process [Claverie, J.-M., Dreux, H. & Cohen, R. (1975) Biopolymers 14, 1685-1700; Cohen, R. & Claverie, J.-M. (1975) Biopolymers 14, 1701-1716]. A numerical method for the simulation of the chemical reaction is derived. From the simulated reaction series, equilibrium constants emerge for the successive addition of protein subunits to the growing nucleoprotein particle.The method is applied to the assembly of alfalfa mosaic virus. If the reaction between RNA and protein is carried out in 0.32M CsCl, pH 7.0, two stages during particle growth are resolved, each characterized by an equilibrium constant K. The determined values for K range from 5 × 105 to 3 × 106 l. mol-1. The existence of these two stages may have a structural implication in the assembly, as they likely represent an elongation and a termination stage. If the reaction is carried out under more favorable conditions (0.25M CsCl, pH 7.0), a kinetic constant of at least 105 l. mol-1 sec-1 is derived for each reaction step. Under these conditions the assembly appears to be completed within 1 min, which is too fast to detect distinct stages by band sedimentation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190310
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  • 82
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    Characterization of molecular motions in 13C-labeled aortic elastin by 13C-1H magnetic double resonance (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 597-617 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Purified insoluble elastin samples labeled with [1-13C]valine, [1-13C]alanine, and [1-13C]-lysine were prepared from chick aorta in culture. The molecular mobility at the labeled sites was investigated using 13C-1H magnetic double-resonance spectroscopy. Linewidths, T1, and nuclear Overhauser effect (NOE) values of the labeled carbons alone were obtained from dipolar decoupled difference spectra. Analysis of these parameters together with signal intensity measurements showed that essentially all the valyl residues, ca. 75% of the alanyl residues, and ca. 60% of the lysyl residues were characterized by rapid backbone motions having τ = 65 nsec. Resonances due to the remaining alanyl and lysyl residues were detected in cross-polarization experiments, which enhance the signals of motionally restricted carbons. Since lysyl and alanyl residues are found in the crosslink regions of elastin, whereas valyl residues are not, we conclude that crosslinks rather than secondary structures in the extensible region of the protein are the main source of motional restrictions in the protein. Elastin chain mobility was monitored by linewidth measurements over the range -90 to +70°C. When the swelling solvent (0.15M NaCl) was fixed at 0.6 g/g of elastin, a rapid monotonic reduction in chain mobility was observed as the temperature was lowered from 50 to 5°C. Liquidlike mobility was completely lost at 5°C. In contrast, the same sample in contact with excess solvent retained its liquidlike molecular mobility until -13°C, where it abruptly became rigid. The molecular mobility of this sample was temperature insensitive in the physiologically interesting range, 20-40°C, as a consequence of the opposing influences of temperature and swelling. Taken together these nmr data indicate that under physiological conditions, elastin is a network of mobile chains whose motions are strongly influenced by protein-solvent interactions.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190311
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  • 83
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    Measurement of preferential solvation of some glucans in mixed solvent systems by gel-permeation chromatography (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 639-653 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preferential solvation of the glucans amylose, pullulan, and dextran in binary dimethyl-sulfoxide/water (DMSO/H2O) solvent mixtures has been measured using gel-permeation chromatography. The preferential solvation behavior of the three glucans in DMSO/H2O solvent mixtures is indistinguishable in the experiments reported. In solvent mixtures with mol ratio DMSO/H2O less than 1:2, all three glucans are solvated preferentially by H2O. The maximum extent of preferential solvation by H2O is about 2.5 mol H2O/mol of glucose residues. When the DMSO/H2O mol ratio exceeds 1:2, DMSO solvates the glucans preferentially to a maximum extent of about 1 mol DMSO/mol of glucose residues. An interpretation of the change in preferential solvation with mixed solvent composition is suggested in terms of the known characteristics of the binary solvent system, and the relationship of preferential solvation, reported here, to the absolute solvation of the glucan chains is discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190313
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  • 84
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    Electrical conductivity of single crystals of lysozyme (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 669-679 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dc electrical conductivity of large single crystals of hen egg-white lysozyme has been measured. The samples were grown from aqueous solution and dried in air with silica gel. The temperature dependence of the conductivity obeyed the relation σ = σ0 exp(- ΔE/kT), with ΔE = 1.2 eV. The ΔE value agreed with most of the previous results for various proteins in the form of lyophilized powder. On the other hand, log σ0, being between 7 and 11, was much larger than the previously reported values and differed among the samples. An irreversible decrease in σ0, without affecting ΔE, was observed on heating the samples above 85°C. It was shown that the set of results can be explained if the charge carriers responsible for the observed conduction are regarded as protons, originating from residual water molecules. Photoresponse of the samples to uv radiation below 305-315 nm was also observed. Reproducible and reliable results were obtained relatively easily in the present experiments, which is thought to be the main advantage of using single-crystalline samples.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190315
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  • 85
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    Transport properties and hydrodynamic centers of rigid macromolecules with arbitrary shapes (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 751-766 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general formalism, which includes translation-rotation coupling, is proposed for calculating translational and rotational transport properties, as well as intrinsic viscosities, of rigid macromolecules with an arbitrary shape. This formalism is based on Brenner's theory of translational-rotational dynamics and on methods for the calculation of hydrodynamic properties that have been already presented, and can be regarded as a generalization of the one proposed by Nakajima and Wada. The calculated transport properties depend on the origin as predicted by Brenner's theory, but in a disagreement with him, the center of resistance and the center of diffusion do not coincide. As one can define several hydrodynamic centers, which in practice turn out to be located at different points, the influence of the choice of the center on the calculated transport properties is discussed. An analysis of the translation-rotation coupling effects in translational diffusion reveals that they arise exclusively from hydrodynamic interactions and are rather small in some cases of interest. Finally, we present a study of the rotational diffusion of rigid bent rods with a fixed length-to-diameter ratio. The diffusion coefficients obtained can be useful to estimate changes with respect to a straight rod.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190404
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  • 86
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    Integriertes Organisches Praktikum. Von S. Hünig, G. Märkl und J. Sauer. Verlag Chemie, Weinheim 1979. XL VIII, 744 S., Abb. u. Tab., brosch. DM 59,- (1980)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 14 (1980), S. 72-72 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19800140207
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  • 87
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    Flüssiger Schwefel - ein Rohstoff komplizierter Zusammensetzung (1980)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 14 (1980), S. 73-81 
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    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19800140302
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  • 88
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    Kleben und Klebstoffe (1980)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 14 (1980), S. 124-133 
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    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19800140404
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  • 89
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    Methoden chemisch-kinetischer Berechnungen. Von H.-J. Bittrich, D. Haberland, G. Just. Verlag Chemie, Weinheim 1979. 217 S., 59 Abbildungen, 13 Tabellen, kart. DM 39, - (1980)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 14 (1980), S. 134-134 
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    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19800140406
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  • 90
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    Chronik (1980)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 14 (1980), S. 176-176 
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    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19800140506
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  • 91
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    Ethische Ziele und natur-wissenschaftliche Entwicklung. Probleme einer vernachlässigten Beziehung (1980)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 14 (1980), S. 168-175 
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    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19800140505
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  • 92
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    Bioaktive Siliciumverbindungen (1980)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 14 (1980), S. 197-207 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19800140605
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  • 93
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    Organische Chemie. Von A. Streitwieser und C. H. Heathcock. Verlag Chemie, Weinheim, Deerfield Beach, Basel 1980. XXXI, 1490 S., 411 Abb., 132 Tab., geb. DM 98, - (1980)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 14 (1980), S. 209-209 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19800140607
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  • 94
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    Experiments in Environmental Chemistry. A Laboratory Manual. Von P. D. Vowles und D. W. Connell. Pergamon Press, Oxford, New York, Toronto, Sydney, Paris, Frankfurt 1980. VII, 102 S., Zeichn. u. Abb., kart. $ 9,95 (1980)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 14 (1980), S. 210-210 
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    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19800140609
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  • 95
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    Adsorption of polypeptides on the solid surface. II. Effect of secondary chain structure and helix-coil transition (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 805-821 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The theory of adsorption of semistiff chains on a planar surface developed by the authors previously has been used to consider the helix-coil transition in single-stranded macromolecule interacting with an adsorbent plane. The cases of nonselective interaction when the adsorption energy is independent of the unit conformation (a) and selective interaction with only helical (b) or coiled (c) sequences active in adsorption were investigated. In case (b) the existence of secondary structure favors chain bonding to the surface. This leads to the increase in the stability of the helical state and complete polypeptide chain spiralization. The profile of the conformational helix-coil transition acquires an asymmetrical shape inherent to the second-order phase transition.In case (c) the bonding of a partially helical chain to the surface is similar to the adsorption of Gaussian coils and is accompanied by the destruction of secondary structure, this destruction being appreciable even if the helical state in space was favorable.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190407
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  • 96
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    Electronic Resource
    Unwinding of DNA induced by fluorescein mercuric acetate (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 991-999 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fluorescein mercuric acetate causes the unwinding of DNA and binds to the separated bases. This unwinding process can be followed by measuring absorption changes of this reagent. For untreated calf thymus DNA, the initial rate was very slow, and the shape of the kinetic curve was sigmoidal. When double-strand breaks of DNA were produced by DNase II treatment or sonication, the initial rate increased and the sigmoidal character disappeared. The initial rate was shown to be proportional to the concentration of helix ends. From this relation the rate of unwinding was estimated to be 2.0 base pairs/sec at 1.0 × 10-5M fluorescein mercuric acetate and 25°C. DNase I treatment, which produces single-strand breaks and a smaller number of double-strand breaks, also increased the initial rate. However, this increase was due only to the double-strand breaks, that is, single-strand breaks had no significant effect on the initial rate. Also, uv irradiation increased the initial rate linearly with uv dose, at least up to 2 × 105 erg/mm2, suggesting that this increase is due to photoproducts other than usual pyrimidine dimers. We discuss the usefulness of this kinetic method in structural studies of DNA.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190505
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  • 97
    Electronic Resource
    Electronic Resource
    Circular dichroism of nucleic acid monomers. I. Calculated adenosine and 2′-deoxyadenosine CD spectra (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1017-1038 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A combination of the DeVoe and Kirkwood polarizability concepts is developed to calculate CD spectra of nucleic acid monomers. The method is perfectly general and applies to any system where the constituents have absorption properties which are widely separated in terms of frequency. The theory is applied to calculate the CD spectra of adenosine and 2′-deoxyadenosine conformers. Bond polarizabilities are evaluated for the ribosyl moiety of adenosine, as a function of glycosidic rotational angles and polarizability anisotropies. It is found that a wide range of C-C and C-O bond polarizabilities give similar CD results. Isotropic atom polarizabilities are also evaluated. It is found that the CD results using these polarizabilities do not differ significantly from those obtained with bond polarizabilities. The CD spectra of adenosine and 2′-deoxyadenosine are calculated for three x-ray diffraction determined geometries: A-form RNA, B-form DNA, and C-form DNA. The results indicate that the monomer CD spectra are strongly dependent on the precise geometry and appear to be of importance in understanding the spectra of oligomers and polymers. The deoxyadenosine conformers are found to have calculated CD spectra which are less intense than those of the ribosyl conformers. These results indicate that the measured differences between the CD magnitudes of ribo- and deoxyriboadenosine are due to the presence or absence of the 2′-hydroxyl. Weighted averaged adenosine CD spectra are calculated with the aid of probability distributions from conformational energy calculations. The results suggest a new method for obtaining empirical monomer parameters for use in optical calculations. The calculations in this paper indicate for the first time that DeVoe theory, in combination with the Kirkwood theory, provides a useful method for the calculation of the CD spectra of nonpolymeric molecules.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190507
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  • 98
    Electronic Resource
    Electronic Resource
    β-Chain conformation of the high-sulfur proteins from wool (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1093-1097 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190512
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  • 99
    Electronic Resource
    Electronic Resource
    Calorimetric determination of the enthalpy of ionization of oxidized and reduced horse heart cytochrome c (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 899-911 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The heats of ionization of protons, ΔHi, of oxidized and reduced horse heart cytochrome c in 0.15M KCl at 20°C were determined using a titration calorimeter which simultaneously afforded the potentiometric titration curve. Reproducibility of the thermal titrations is within 2%, and evaluation of the heats observed after the heat loss corrections is estimated to be within 5%. A single titration of oxidized cytochrome c from pH 11 to 3 is in excellent agreement with the thermal titration of this protein obtained with flow calorimetry. The thermal titration, however, is not reversible, due in part to the loss of titratable group(s) in this pH region and to the heat contribution of the acid and alkaline conformational changes which occur. Although of lesser magnitude, the reduced form also indicates similar thermal transitions. These differences are due solely to conformational contributions to the thermal process, since the potentiometric curves are reversible. The nature of the irreversibility for oxidized cytochrome c appears to involve the loss of a group with pK′ 8.9 and the shift of two groups from pK′ 5.6 to 4.8. Thermal difference curves for this process indicate that heats of -7.8 and -24.1 kcal/mol are liberated which are centered at pH 9.3 and 3.9, respectively.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190413
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  • 100
    Electronic Resource
    Electronic Resource
    Syn-anti equilibrium of purine bases in dinucleoside monophosphates as studied by proton longitudinal relaxation (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1211-1239 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preferential orientations of the purine bases in dinucleoside monophosphates such as ApA, ApG, and GpA in 10-2M neutral aqueous solutions have been investigated by proton relaxation at 250 MHz. These orientations are deduced from computer simulations of the magnetization recovery curves following a 180° nonselective pulse. The distances between the H(8) proton of a base and the ribose ring protons which are used in these calculations are obtained by minimization as a function of the glycosyl torsion angle ϒ of the standard deviation between the isotropic reorientation correlation times τR derived from the relaxation rates of these protons. The average H(1′) - H(8) distance obtained by this procedure may be readily verified from the reduction of the H(1′) relaxation rate when H(8) is substituted by a deuteron. The limits of validity of the assumption of a single correlation time τR governing the proton relaxation have been estimated, taking into account several possible internal motions, e.g., the rotation of the base, of the methylene exocyclic group and the N ⇄ S interconversion of the ribose ring. For 10-10 〈 τR 〈 2 × 10-10 sec, it appears that the influence of these motions on the proton relaxation becomes perceptible when the jump rates among equilibrium positions exceed ca. 109 sec-1.The whole of the experimental results show that for the ribose ring N conformer, the orientation of the bases is found in the ranges 60° 〈 ϒ 〈 80° (syn) and 180° 〈 ϒ 〈 210° (anti). For ribose S conformer, it is observed that this orientation is mainly syn with 5° 〈 ϒ 〈 90°. The average H(1′) - H(8) distance provides semiquantitative information on the overall syn or anti orientations of the base in each nucleoside moiety. At 298 K the population of the anti conformer is found to increase in the order A- pG 〈 Ap-G ∼ Gp-A 〈 Ap-A 〈 A-pA 〈 G-pA. A more detailed analysis of relaxation data shows that the maximum possible fraction of the stacked form of dinucleotides, due to the occurrence of N-anti conformers in both nucleoside moieties, is in the order ApG 〈 GpA 〈 ApA, in agreement with previous works, with however smaller values.Lastly the deuteron linewidth in position 8 of the bases indicates a syn-anti transition rate of the order of 109 sec-1 at room temperature, without noticeable effects therefore on the proton relaxation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190608
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