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  • 1985-1989  (1,599)
  • 1965-1969  (1,805)
  • 1960-1964
  • 1930-1934
  • 1985  (1,599)
  • 1968  (1,805)
  • General Chemistry  (2,108)
  • Organic Chemistry  (1,218)
  • Cat
  • Insulin
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Years
  • 1985-1989  (1,599)
  • 1965-1969  (1,805)
  • 1960-1964
  • 1930-1934
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Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Response covariance in cat visual cortex (1985)
    Springer
    Experimental brain research 60 (1985), S. 559-563 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Visual cortex ; Multiunit recordings ; Response variance ; Response covariance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The activity of pairs of neurons in the visual cortex (area 17) of anaesthetized, paralysed cats was recorded using two independently manipulated micropipettes. The number of spikes in the evoked responses of pairs of single neurons were analyzed for response covariance. Responses of the majority of cell pairs (83%) did not covary. Covariance was restricted to closeby neurons with distances of less than 150 μm and with identical orientation and ocular dominance preference.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236942
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  • 2
    Electronic Resource
    Electronic Resource
    Differences in synaptic size in the superficial and deep layers of the molecular layer of the cerebellar cortex of the cat (1985)
    Springer
    Anatomy and embryology 172 (1985), S. 303-309 
    Details
    ISSN: 1432-0568
    Keywords: Synaptology ; Cerebellum ; Quantitative analysis ; Autoradiography ; Electron microscopy ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In a previous study observations in semithin sections of E-PTA-stained cerebellar cortex of the cat revealed differences in size of synaptic grids between the molecular and granular layer (Van der Want et al. 1984). In addition, synaptic size differences were observed between superficial and deep levels in the molecular layer. The present study was an attempt to analyze synapses in ultrathin sections of the cerebellar cortex with special emphasis on size differences of distinct types of synapses at different levels in the molecular layer. Climbing fibers were identified by means of anterograde transport of 3H-leucine injected in the inferior olive and parallel fibers were identified on account of fine structural criteria. Synaptic profiles were measured semi-automatically in the neuropil of the cerebellar cortex at the supra-Purkinje level and the subpial level. Measurements of the trace- and chordlength were obtained from random sections. The frequency distribution of the true diameters of the synapses was reconstructed with a discrete “unfolding”-procedure. The overall diameter at the superficial level was 390.2±1.5 nm, at the deep level 406.6±1.5 nin. Climbing fibers exhibited mean values of 431.9±4.7 and 461.3±4.1 nm at these levels and parallel fiber terminals mean values of 370.7±2.9 and 395.8±3.0 nm. The frequency distributions showed remarkable and statistically significant differences compared with the overall distributions observed at the superficial and the deep levels respectively. The frequency distributions of synaptic diameters at the superficial and deep levels also differ significantly. The results suggest that synapses are characterized by a specific size which might be related to the region of termination or might be determined by the afferent neuron. This is in agreement with earlier observations in E-PTA treated material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318978
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  • 3
    Electronic Resource
    Electronic Resource
    The projection from the superior colliculus to the lateral reticular nucleus in the cat as studied with retrograde transport of WGA-HRP (1985)
    Springer
    Anatomy and embryology 173 (1985), S. 269-274 
    Details
    ISSN: 1432-0568
    Keywords: Lateral reticular nucleus ; Superior colliculus ; Retrograde transport of WGA-HRP ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Medium-sized and large superior collicular neurons were retrogradely labelled after small ejections of the wheat germ agglutinin-horseradish peroxidase complex in the lateral reticular nucleus of the feline medulla. The projection from the superior colliculus to the lateral reticular nucleus is bilateral with a contralateral predominance. It originates mainly from the intermediate, but also from the deep gray layer of the superior colliculus. Our observations provide evidence that the lateral reticular nucleus is an important target of tectal efferents. The findings are discussed in relation to the organization of other fiber connections of the superior colliculus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00316308
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  • 4
    Electronic Resource
    Electronic Resource
    The size and curvature of synapses in the cerebellar cortex of the cat (1985)
    Springer
    Anatomy and embryology 171 (1985), S. 83-89 
    Details
    ISSN: 1432-0568
    Keywords: Quantitative anatomy ; Synaptic length ; Synaptic curvature ; Cerebeller cortex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary At the supra Purkinje layer and the subpial level in the molecular layer of lobules V and VI of the cerebellar cortex of the cat, synaptic profiles were measured in ultrathin serial sections treated with either osmium tetroxide (OsO4) or ethanolic phosphotungstic acid (E-PTA). From trace and chord lengths of the intercepts of synaptic profiles the curvature and the mean caliper diameter of the synapse was calculated. In OsO4-material the curvature of synapses yielded an average angle of about 47 degrees and about 36 degrees in E-PTA material. Although these values are contrary to the assumption of a flat disc, which is commonly required in stereological procedures to estimate caliper diameter, the effect of the curvature on the estimation of the mean caliper diameter is limited. This is shown by serial reconstruction analysis of the largest diameter of synapses from maximal arc and chord length measurements at the subpial and supra Purkinje level. The results provide quantitative data concerning synaptic size, curvature and the frequency of intercepts per synapse at the subpial and supra Purkinje level in the cerebellar cortex in OsO4 and E-PTA material. In addition the advantages and disadvantages of E-PTA and osmiumtetroxide staining in quantitative analysis are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319057
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  • 5
    Electronic Resource
    Electronic Resource
    Distribution of the neurons of origin of the great cerebral commissures in the cat (1985)
    Springer
    Anatomy and embryology 171 (1985), S. 105-120 
    Details
    ISSN: 1432-0568
    Keywords: Cerebral cortex ; Corpus callosum ; Anterior commissure ; Horseradish peroxidase ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Large injections of horseradish peroxidase throughout major portions of the right cerebral hemispheres of four cats revealed extensive distributions of the neurons of origin of the corpus callosum, the anterior commissure and the hippocampal commissures in the uninjected left hemispheres. The distributions of labelled neurons were mapped by semiautomatic computer microscope. The radial and tangential neuron distributions presented here are of a higher density and greater extent than those in previously published studies based on injections of transportable label to more circumcribed areas of the cerebral cortex of the cat. Generally, commissural neurons in the cat were distributed in a bilaminar fashion with supragranular cells more numerous than infragranular cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319060
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  • 6
    Electronic Resource
    Electronic Resource
    Measurement of free insulin concentrations: the influence of the timing of extraction of insulin antibodies (1985)
    Springer
    Diabetologia 28 (1985), S. 831-835 
    Details
    ISSN: 1432-0428
    Keywords: Insulin ; free insulin assay ; insulin antibodies ; radioimmunoassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Plasma insulin concentrations of insulin-treated diabetic patients must be measured after removal of insulin antibodies, usually by precipitation with polyethylene glycol (PEG). Details of the procedure vary between laboratories; commonly, frozen plasma is thawed and incubated at 37 °C to restore a presumed equilibrium between free and antibody bound insulin before extraction. The present study was designed to investigate methodological factors that could affect the measured free insulin concentration. In normal subjects PEG extraction of globulins did not disturb measurement of insulin concentrations, whether carried out after incubation for 2 h at 37 °C, or storage at -20 °C, in either order. Freezing or incubation of PEG extracts of plasma from insulin-treated patients also failed to disturb the measured concentrations of free insulin. When plasma from patients was incubated for 2 h after storage, a marked scatter (51–272%) of measured results occurred when compared to bedside extraction. This problem was not overcome by buffering with HEPES or storage at a lower temperature (-40 °C). Incubation at 0 °C also severely disturbed the apparent concentrations. Incubation of plasma before extraction and freezing also disturbed the measured result, a problem not corrected by maintaining near physiological pH. Total insulin concentrations measured on acid extracts were not disturbed by any of these manoeuvres. The temperature of centrifugation of blood at the time of venepuncture did not influence the result. Furthermore, when insulin concentrations were rising or falling similar percentage changes were seen over a 30-min incubation of plasma before extraction on the day of venepuncture, suggesting that equilibrium between free and bound insulin is maintained in vivo. We suggest that, for accurate estimation of free insulin concentrations in insulin-treated diabetic patients, immediate centrifugation of blood and extraction of insulin antibodies is mandatory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00291073
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  • 7
    Electronic Resource
    Electronic Resource
    Intravenous insulin has no effect on myocardial contractility or heart rate in healthy subjects (1985)
    Springer
    Diabetologia 28 (1985), S. 649-652 
    Details
    ISSN: 1432-0428
    Keywords: Insulin ; myocardial contraction ; heart rate ; diabetes mellitus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To evaluate the acute effects of intravenous insulin on myocardial contractility and heart rate, echocardiography was performed in 12 healthy subjects and continuous heart rate recording in 11 healthy subjects before and during eugly-caemic insulin and glucose infusion. The rate of insulin infusion was 0.5–1.0 mU·kg−1·min−1. Serum insulin concentration was increased from 14.1±5.5 (mean±SD) to a plateau level of 91.3±22.8 mU/l. Left ventricular end-diastolic diameter, ejection phase indices and the heart rate remained at basal levels during the intervention. Thus moderate hyperinsulinaemia, induced by euglycaemic insulin and glucose infusion, has no inotropic or chronotropic effects in healthy supine subjects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00291969
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of work-induced hypertrophy on muscle glucose metabolism in lean and obese mice (1985)
    Springer
    Diabetologia 28 (1985), S. 295-301 
    Details
    ISSN: 1432-0428
    Keywords: Insulin ; insulin resistance ; obesity ; exercise ; glucose metabolism ; glycogen synthase ; fructose 2–6 bisphosphate ; skeletal muscle ; goldthioglucose obese mice ; hypertrophy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of work-induced hypertrophy (without any concomitant change in circulating parameters) on skeletal muscle metabolism was studied in lean mice and in goldthioglucose obese-mice. Soleus muscle was functionally overloaded in one leg by tenotomy of gastrocnemius muscle 4 days before muscle isolation, muscle in the other leg being used as control. Basal deoxyglucose uptake and glycolysis were markedly increased in overloaded muscles compared with control muscles, together with a ten-fold increase in fructose 2–6 bisphosphate content. In the presence of maximally effective insulin concentrations, deoxyglucose uptake and glycolysis were identical in overloaded and control muscles of lean mice, while the effects of overload and insulin were partly additive in muscles of goldthioglucose-obese mice. The sensitivity to insulin and insulin binding to muscles were not modified in overloaded muscles. Insulin-stimulated glycogenogenesis was decreased by about 50% probably due to a lower amount of glycogen synthase in overloaded than in control muscles. Thus, in muscles of goldthioglucose-obese mice work-induced hypertrophy increased the response to maximal insulin concentrations without modifying the altered insulin sensitivity and decreased insulin binding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00271689
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  • 9
    Electronic Resource
    Electronic Resource
    Untoward effects of pharmacological doses of insulin in early chick embryos: through which receptor are they mediated? (1985)
    Springer
    Diabetologia 28 (1985), S. 308-313 
    Details
    ISSN: 1432-0428
    Keywords: Insulin ; proinsulin ; insulin-like growth factors ; multiplication-stimulating activity ; insulin effects on growth ; embryogenesis ; chick embryo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The teratogenic effect of insulin in early vertebrate embryos is controversial and the mechanisms involved are unknown. We studied the effects of pharmacological doses of insulin in chick embryos during the period of differentiation. We compared the effects of insulin with two proinsulins, desoctapeptide-insulin and multiplication-stimulating activity, peptides that have little insulin-like metabolic activity while they have significant growth effects. Chick embryos at 46 h of development were injected with the different peptides. At 96 h the mortality and abnormal growth elicited by the peptides were dose-dependent. Considering the indices of lethality (LD50) and affected embryos (ED50) as 100% for insulin, proinsulin was 59–66% as potent as insulin, desoctapeptide-insulin 2–6% and multiplication-stimulating activity 176–204%. In the surviving embryos, insulin (5 μg, decreased DNA, RNA and protein content by 49%, 40% and 48% respectively compared with controls. The effects of insulin were not corrected by simultaneous glucose injections. These data suggest that insulin, at pharmacological doses, interferes with embryo development through a non-metabolic pathway, probably via a growth-type receptor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00271691
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  • 10
    Electronic Resource
    Electronic Resource
    Chemical stability of insulin in a delivery system environment (1985)
    Springer
    Diabetologia 28 (1985), S. 458-463 
    Details
    ISSN: 1432-0428
    Keywords: Insulin ; insulin stability ; insulin delivery systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Exposure of insulin solutions to elevated temperatures for prolonged periods of time will inevitably lead to chemical modifications of the hormon. Contact with different materials in dosing devices, other design-related factors and motion appear to be chemically more detrimental than storage in glass vials at the same temperature. An in vitro test, designed to mimick the in vivo situation, consisted of delivery of insulin at 37 °C while the device was constantly moved on a shaking apparatus. Insulin quality was assessed using high performance liquid chromatography. A polyethylenepoly-propylene glycol-stabilized neutral human insulin solution (HOE 21 PH) was used. A single insulin derivative is the major modification product which, after passage of the complete infusion system, amounts to up to 10%. The biological potency of the derivative is indistinguishable from native insulin. Delivery of acidic insulin under implant conditions, leads to extensive and multiple insulin derivatization, even though the biological potency remains 95% after 4 weeks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00280891
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  • 11
    Electronic Resource
    Electronic Resource
    Retinal input to the nucleus of the optic tract of the cat assessed by antidromic activation of ganglion cells (1985)
    Springer
    Experimental brain research 59 (1985), S. 395-403 
    Details
    ISSN: 1432-1106
    Keywords: Nucleus of the optic tract ; Direction-selective retinal ganglion cells ; Optokinetic reflex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have studied the physiological properties of ganglion cells in the retina of the cat. The experiments were designed to identify those ganglion cells which project to direction-selective cells in the nucleus of the optic tract (NOT), by demonstrating their antidromic activation at low threshold from an electrode in the NOT. These ganglion cells presumably provide the retinal drive to the optokinetic reflex. Altogether, 11 such ganglion cells were identified in a population of 578 cells studied. All 11 were W-cells, with slow-conducting axons. Five of the 11 had on-centre direction-selective receptive fields; the other 6 had a variety of receptive field patterns. Thus, on centre-selective cells form a much higher proportion of the retinal input to direction-selective cells in the NOT than of the overall ganglion cell population. However, their receptive field properties were too varied fully to account for the selectivity of NOT cells for horizontal stimulus movement. In summary the retinal input to the NOT appears to be formed principally or entirely by W-class ganglion cells, including many which are direction selective. It still seems necessary, however, to postulate, some non-retinal mechanism to account for all the receptive field properties of direction-selective NOT cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230920
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  • 12
    Electronic Resource
    Electronic Resource
    Effects of nitrous oxide on the functional characteristics of cells in the extrastriate cortex of the cat (1985)
    Springer
    Experimental brain research 59 (1985), S. 463-469 
    Details
    ISSN: 1432-1106
    Keywords: Nitrous oxide ; Visual cortical cells ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The directional preferences, receptive field areas, peristimulus-time (PST) histograms and spontaneous activities of 112 feline visual cortical (area 18) cells were studied before, during, and after the administration of nitrous oxide. These cellular characteristics were altered by nitrous oxide inhalation; some quite substantially. The data indicate that the functional characteristics of cortical visual cells, such as the receptive field and the directional preference, are variable; and, among other factors, depend also on the anaesthetic administered to the animal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261335
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  • 13
    Electronic Resource
    Electronic Resource
    The relationship between feline pupil size and luminance (1985)
    Springer
    Experimental brain research 59 (1985), S. 485-490 
    Details
    ISSN: 1432-1106
    Keywords: Vision ; Cat ; Pupil dimensions ; Luminance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relationships between luminance and height, width or area of the feline pupil were investigated in awake, normal adult cats whose pupils were photographed over a range of light levels with the aid of electronic flash. The results are compared with previous measurements of pupil width and height in awake animals (Kappauf 1943); and with estimates of pupil width, height and area in lightly-anaesthetised cats (Wilcox and Barlow 1975). The implications of these results for retinal illumination and colour discrimination are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261338
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  • 14
    Electronic Resource
    Electronic Resource
    Long term survival of cat retinal ganglion cells after intracranial optic nerve transection (1985)
    Springer
    Experimental brain research 59 (1985), S. 633-635 
    Details
    ISSN: 1432-1106
    Keywords: Retinal ganglion cells ; Cat ; Optic nerve cut ; Retrograde labeling ; HRP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary After intracranial transection of the optic nerve in cats the retinal stump of the nerve was injected with HRP. Surviving retinal ganglion cells can be retrogradely labeled at least up to 15.5 months of postoperative survival.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261356
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  • 15
    Electronic Resource
    Electronic Resource
    Somatotopic termination of spinal afferents to the feline lateral cervical nucleus (1985)
    Springer
    Experimental brain research 57 (1985), S. 576-584 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Lectin-conjugated horseradish peroxidase ; Lateral cervical nucleus ; Spinocervical tract ; Somatotopic termination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The labelling pattern of the feline lateral cervical nucleus (LCN) was investigated after pressure injections of lectin-conjugated horseradish peroxidase into cervical, thoracic or lumbar segments of the spinal cord. Sixteen cats received a 5–8 nl injection staining large parts of mainly the ipsilateral grey matter of a single segment. Light microscopic examination of frozen sections reacted with tetramethylbenzidine showed a somatotopic organization in the LCN. Rostral segments of the spinal cord projected mainly to rostroventral and medial parts of the ipsilateral LCN, while more caudally located segments projected to more dorsocaudal and lateral parts of the nucleus. Minor contralateral labelling with a similar somatotopic arrangement was seen in animals given cervical and lumbar injections. No significant labelling was found in the LCN of three control animals, the segmental injections of which were engaged mainly into the ipsilateral dorsal columns and the dorsolateral funiculus. Ultrastructural analysis in two animals which received multiple cervical or lumbar injections showed that about 70% of the peroxidase-positive structures in the LCN were boutons and the rest small myelinated axons. The precise termination pattern of ascending afferents to the LCN is compatible with the somatotopic organization of the other relay centres in the spino-cervicothalamic pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237844
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  • 16
    Electronic Resource
    Electronic Resource
    Combined lesions of septum, amygdala, hippocampus, anterior thalamus, mamillary bodies and cingulate and subicular cortex fail to impair the acquisition of complex learning tasks (1985)
    Springer
    Experimental brain research 58 (1985), S. 346-361 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Learning ; Limbic system ; Memory ; Multiple lesions ; Plasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Previous investigations (Irle and Markowitsch 1982a, 1983, 1984) demonstrated that triple or fourfold lesions within the cat's limbic system fail to produce learning impairments, as opposed to lesions of single or double loci, when tasks of visual reversal, delayed alternation, and active two-way avoidance were used. On the basis of these results, limbic regions of the cat's brain might be considered unessential for intact learning and mnemonic functions. Therefore, in order to obtain indisputable information on the importance of the limbic system for learning and memory, lesions of nearly all limbic core regions of the cat were performed. Ten cats received lesions of seven limbic core regions: the septum, amygdala, anterior thalamus, mamillary bodies, cingulate cortex, subicular cortex, and the hippocampus proper. Nine of these animals were tested postoperatively in the acquisition of a visual reversal task, a spatial alternation and delayed alternation task, and an active two-way avoidance task, and were then compared to the performance levels of ten control animals. The experimental animals turned out to be unimpaired in all tasks tested; the performance scores in the visual reversal and delayed alternation task and — for some experimental animals in the active two-way avoidance task even indicate a slight, though statistically insignificant, facilitation in the learning behavior of these animals. It is assumed that the learning functions underlying the tasks used were taken over by other brain regions, which, prior to massive limbic lesions, may be suppressed or otherwise inhibited. Alternatively, utilization of spared tissue in the damaged limbic regions must be considered as the possible explanation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235316
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  • 17
    Electronic Resource
    Electronic Resource
    Is the retina sensitive to the effects of prolonged blur? (1985)
    Springer
    Experimental brain research 58 (1985), S. 427-434 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Retinal ganglion cells ; Atropine ; Optical blur ; Acuity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two preparations were used to study the developmental effects of prolonged blurring of retinal images on the acuities of retinal ganglion cells. Five kittens were raised from three weeks to six months of age with daily administration of atropine to one eye. Another two kittens were raised from three weeks to 16 weeks with a contact lens of high refractive power fitted to one eye. Behavioural estimates of the visual acuity were made for two animals from each group. Animals of both groups demonstrated an amblyopia in the experimental eye: visual acuity varied from 1.8 to 2.5 cycles per degree compared with 6.0 to 7.5 cycles per degree when using the normal eye. The spatial resolving properties were measured for retinal ganglion cells within the amblyopic eyes of two lens-reared cats and three atropinized cats. Brisk-sustained (X) cells were recorded from along the naso-temporal division. The acuities of ganglion cells from the lens-reared cats were indistinguishable from those from normal cats at comparable eccentricities. However, for the cats raised with atropine administration, sub-normal acuities were determined for retinal ganglion cells from all regions that were studied in the experimental eye. We conclude that blur of retinal images produced by external means has no effect on the resolving power of retinal ganglion cells. The lowered ganglion cell acuities encountered with the atropinised cats must be attributable to a secondary effect of the atropine administration. Organic changes in the retinal blood vessel pattern support this contention.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235859
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  • 18
    Electronic Resource
    Electronic Resource
    Connections between pericruciate cortex and the medullary reticulospinal neurons in cat: an electrophysiological study (1985)
    Springer
    Experimental brain research 61 (1985), S. 109-116 
    Details
    ISSN: 1432-1106
    Keywords: Motor cortex ; Reticulospinal neuron ; Corticobulbar pathways ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The connections between the pericruciate cortex and the medullary reticulospinal (RS) neurons were studied in anesthetized cat. Intracellular recordings were made from reticulospinal neurons and the effects of stimulating different areas of the pericruciate cortex were compared. (1) EPSPs were elicited in all the 93 neurons studied which were antidromically activated by spinal stimulation and had an IS-SD notch on the ascending limb of their antidromic spikes. According to the conduction velocity (c.v.) of the axon and the minimal EPSP latency to cortical stimulation, the neurons could be divided into two groups, i.e. fast-conducting RS neurons (FRS neurons, c.v. 〉 45 m/s) and slow-conducting RS neurons (SRS neurons, c.v. 〈 45 m/s). The minimal latencies of FRS neurons were equal to or shorter than 2 ms whereas those of SRS neurons were longer than 2 ms. (2) EPSPs with short latency (〈 2 ms) could be evoked in FRS neurons by stimulating a relatively wide cortical area including the major part of precruciate area 4 and area 6, with a central area of strongest excitatory effect located in area 4 slighthly medial to the tip of the cruciate sulcus. Stimulation of the postcruciate area 4 only produced long latency EPSPs. (3) By extrapolation from the cortical and peduncular latencies and the conducting distances it was revealed that the earliest part of the minimal latency EPSPs were monosynaptically evoked in FRS neurons and were mediated by fastconducting corticobulbar fibers. (4) FRS neurons could be excited by stimuli applied to both ipsilateral and contralateral pericruciate cortex. The influence from the contralateral cortex was slightly stronger.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235626
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  • 19
    Electronic Resource
    Electronic Resource
    An intracellular HRP-study of cat tensor tympani motoneurons (1985)
    Springer
    Experimental brain research 57 (1985), S. 499-511 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Tensor tympani motoneurons ; Somadendritic morphology ; Intracellular HRP ; Auditory nuclei ; Tensor tympani motor nucleus of V ; Trigeminal motor nucleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The morphology of single tensor tympani motoneurons was investigated following antidromic identification and intracellular injection of horseradish peroxidase. Eight motoneurons were selected for complete reconstruction and quantitative analysis. The mean size of tensor tympani somata (26.3±1.8 μm) make this parvocellular cluster of motoneurons below the trigeminal motor nucleus a population of the smallest cranial motoneurons yet described. Axons emerged from either the soma or a primary dendrite. They coursed dorsolaterally frequently through the trigeminal motor nucleus before looping ventrolaterally into the Vth nerve. No collaterals were observed within the brainstem. The 5 primary dendrites of each cell branched heavily and, on average, exhibited 40 terminal branches with an average tree expansion of 1262.5 μm. The dendritic arborization extended far beyond the nuclear boundaries described by the distribution of cell bodies. These data suggest that the overall membrane area for synaptic innervation is large and thus it provides morphological evidence for the hypothesis that tensor tympani motoneurons receive divergent multisensory synaptic input. The latter assumption was supported by morphological and electrophysiological evidence including close the proximity of motoneuronal dendrites to auditory (superior olivary complex) and somatosensory (trigeminal) relay centers. Since no dendrite ever entered the trigeminal motor nucleus proper the tensor motoneuron pool is distinct from the trigeminal not only in terms of soma size, location and function, but also the disposition and expansion of the postsynaptic receptive field. Based on these criteria the tensor tympani motoneuron pool should no longer be regarded as an accessory trigeminal nucleus but be recognized in its own right as the tensor tympani motor nucleus of V.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237837
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  • 20
    Electronic Resource
    Electronic Resource
    Substantial reduction of noradrenaline in kitten visual cortex by intraventricular injections of 6-hydroxydopamine does not always prevent ocular dominance shifts after monocular deprivation (1985)
    Springer
    Experimental brain research 59 (1985), S. 30-35 
    Details
    ISSN: 1432-1106
    Keywords: Developmental plasticity ; Visual cortex ; Noradrenaline ; Cat ; 6-hydroxydopamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ten kittens had cannulas inserted into their lateral ventricles for daily injections of 6-hydroxydopamine (6-OHDA). At 5–6 weeks of age one eye was sutured shut, and one week later recordings were made from the visual cortex to assay the ocular dominance of a sample of cells. In six kittens the injections of 6-OHDA were continued until the day before recording, while in four kittens the injections were stopped around the time of eye suture, on the assumption that continued injections of 6-OHDA over several days has effects that are not specific to the noradrenaline (NA) system and that the two procedures might show different results. In all animals the concentration of NA in the visual cortex near the site of recording was reduced by approximately 90%. In all animals the ocular dominance histograms recorded from the visual cortex were shifted so that the majority of cells (83 ± 13%) were dominated by the open eye. There were no substantial differences between the two groups of experimental animals or between the experimental animals and two control animals that had cannulas implanted and ascorbate alone injected without 6-OHDA. We conclude that the concentration of NA in the visual cortex can be reduced substantially by injections of 6-OHDA into the lateral ventricle without preventing the shift in ocular dominance that usually occurs after suturing shut the eyelids of one eye.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237662
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  • 21
    Electronic Resource
    Electronic Resource
    Regional distribution of prostanoids in rat brain: effect of insulin and 2-deoxyglucose (1985)
    Springer
    Experimental brain research 61 (1985), S. 87-90 
    Details
    ISSN: 1432-1106
    Keywords: Prostaglandins ; Brain ; Insulin ; 2-deoxy glucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Prostaglandin synthesis in the brain has been suggested as a component in the control mechanism of the cerebral circulation. During insulininduced hypoglycemia there is a significant increase in local cerebral blood flow in various brain regions, however, regional loss of autoregulation occurs under these conditions. In the present study the regional distribution of PGE2, TXB2 (the stable metabolite of thromboxane) and 6-keto-PGF1α (the stable metabolite of prostacyclin) was determined in rat brain following decapitation. Three groups of rats were treated with either saline, insulin or 2-deoxyglucose and their brains were rapidly removed one hour later. Samples from the cortex hypothalamus, hippocampus, striatum, nucleus accumbens and cerebellum were assayed by RIA for the content of PGE2, TXB2 and 6-keto-PGF1α The levels of all three compounds in control rats were the lowest in the striatum and cerebellum, while in the cortex and hippocampus their levels were 4–6 times higher. Insulin had selective effect on the post decapitation levels of prostanoids. It increased PGE2 in the n. accumbens and TXB2 in the hippocampus, and reduced 6-keto-PGF1α and TXB2 in the cortex. 2-DG reduced all PGs in the cortex and 6-keto-PGF1α in the hypothalamus and hippocampus. The results demonstrate that discrete brain areas have a differential capacity to accumulate PGs following decapitation. This capacity is selectively affected by insulin and 2-DG.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235623
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  • 22
    Electronic Resource
    Electronic Resource
    Task-related coding of stimulus and response in cat motor cortex (1985)
    Springer
    Experimental brain research 57 (1985), S. 427-442 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Motor cortex ; Single unit activity ; Tracking ; Input switching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In a previous study in the cat, we have reported that motor cortex neurons discharging before the initiation of an aimed forearm response (lead cells) are better timed to movement of a display (stimulus) than to the response. The present study was done to distinguish the coding of stimulus and response features in the discharge patterns of such early activity in motor cortex. Single neurons were recorded in the arm area of motor cortex in three cats performing the same pair of responses (forearm flexion and extension) but to display movements in either of the two directions by changing display polarity. The modulation of lead cell activity was contingent on the occurrence of the learned motor response and timed to the stimulus in all conditions. The majority of lead cells (88%, n = 50) fell into one of two distinct classes. In one class of neurons, force-direction (56%, n = 32), activity was contingent on a single direction of forelimb response (flexion or extension) and was thus independent of the direction of the display stimulus. The only muscles whose patterns matched the activity of this class of response-related neurons were forelimb flexors and extensors. In these neurons, the onset of modulation was timed to one or the other of the two stimuli according to the stimulus direction which elicited the appropriate response. Thus, the display-related input to these neurons varied according to the response required. In the second class of neurons, stimulus-direction (32%, n = 18), modulation was associated with a specific stimulus direction rather than the response direction. The pattern of activity of these neurons was similar to the pattern of EMG signals of shoulder and neck muscles during the different task conditions. The contraction of proximal and axial muscles corresponded to a second response elicited by the stimulus, namely attempts at head rotation towards the moving display and was independent of the conditioned forelimb response in both time of onset and direction. To test the possibility that stimulus-direction neurons participated in the control of head rotation we trained two of the animals to also produce isometric changes in neck torque in the direction of the moving display without making the forelimb response. The activity of stimulus-direction neurons was similarly modulated during performance of the neck task. By contrast, force-direction neurons examined during the neck task were either unmodulated or discharged after the neck response. These data suggest that force-direction neurons participate in response initiation and that their activity is triggered by stimuli specific for the task. The reorganization of the inputs to motor cortex is likely to result from gating mechanisms associated with behavioral set. Such neural gates could provide for the efficient transfer of any member of an array of behaviorally relevant stimuli to restricted sectors of the somatotopically organized motor areas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237829
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  • 23
    Electronic Resource
    Electronic Resource
    The cholinergic innervation of the visual thalamus: an EM immunocytochemical study (1985)
    Springer
    Experimental brain research 59 (1985), S. 206-212 
    Details
    ISSN: 1432-1106
    Keywords: Lateral geniculate nucleus ; ChAT-immunocyto-chemistry ; Cholinergic pathways ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In this study we demonstrate at the ultrastructural level that both the dorsal lateral geniculate nucleus (dLGN), the visual relay of the thalamus, and the perigeniculate nucleus (PGN), the visual segment of the thalamic reticular nucleus (TRN), are densely innervated by fibres with Choline-Acetyl-Transferase (ChAT) like immuno-reactivity. These axons make synaptic contacts with interneurones considered to be inhibitory, both in the PGN and within the synaptic glomeruli of the dLGN. In addition, Chat positive terminals form intra- and extraglomerular synapses with dendrites thought to arise from relay cells. We interpret these results as evidence for direct cholinergic modulation of both relay cells and inhibitory interneurones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237681
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  • 24
    Electronic Resource
    Electronic Resource
    Canal-neck interaction in vestibular neurons of the cat's cerebral cortex (1985)
    Springer
    Experimental brain research 61 (1985), S. 94-108 
    Details
    ISSN: 1432-1106
    Keywords: Cerebral cortex ; Canal-neck interaction ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Interaction of semicircular canal and neck proprioceptive inputs was studied in the cerebral cortex of awake, intact cats. Neuronal responses were recorded extracellularly in the anterior suprasylvian gyrus of the left hemisphere. Stimulations consisted of horizontal rotations in the dark applied as sinusoids or position ramps. There were three stimulus conditions: (1) Pure canal stimulation; rotation of whole body. (2) Pure neck stimulation; rotation of trunk about stationary head. (3) Canalneck interaction; rotation of head about stationary trunk. (1) We recorded 105 neurons with either Type I or Type II canal response. These showed often pronounced non-linearities such as a clear firing increase upon rotation in the “on-direction” and hardly any decrease in the opposite direction. The responses reflected mostly angular velocity, but angular position signals were also obtained. (2) In 79 neurons, either Type I or Type II neck responses were obtained. They coded either angular velocity, velocity plus position, or position. (3) Canal-neck convergence was found in 67 of 88 neurons tested. In the majority of neurons, interaction was “dantagonistic” in the sense that the canal and neck responses tended to cancel each other during rotation of the head about the stationary trunk. These neurons could signal trunk rotation in space rather than head in space or head relative to trunk. Most of the remaining neurons showed a “synergistic” interaction such that the response upon head rotation was enhanced as compared to whole body or trunk rotation. These neurons might be involved in the dual task of monitoring head rotation in space and relative to trunk. Interaction was compatible with linear summation of canal and neck inputs in 70% of the neurons. In part of these, however, the assumption had to be made that the interaction had taken place already at some stage prior to the cortical neurons investigated. The response characteristics of cortical canal neurons are discussed in comparison to vestibular nuclear neurons. Furthermore, parallels are drawn between the observed canal-neck interactions in the cortical neurons and (i) interactions of canal and neck dependent postural reflexes in the decerebrate cat, and (ii) interactions of canal and neck induced turning sensations in man.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235625
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  • 25
    Electronic Resource
    Electronic Resource
    Variability in the effects of monocular deprivation on the optokinetic reflex of the non-deprived eye in the cat (1985)
    Springer
    Experimental brain research 61 (1985), S. 117-127 
    Details
    ISSN: 1432-1106
    Keywords: Horizontal optokinetic nystagmus ; Nucleus of the optic tract ; Monocular deprivation ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Six cats monocularly deprived by eye lid closure within the first week after birth showed the same deficits in the optokinetic reflex (OKR) when tested through the deprived eye as adults irrespective of whether the deprivation period was 6, 24 or 36 months. Closed loop gain (eye velocity/ stimulus velocity) during temporo-nasal stimulus movement was below 0.8 and approached zero at stimulus velocities above 20°/s. Naso-temporal stimulus movement was ineffective in eliciting OKR gain higher than 0.1 at velocities above 10°/s. 2. Different optokinetic deficits were found when the non-deprived eye was tested. In 3 cats OKR gain of the non-deprived eye was reduced with temporally directed stimulus movement when compared to normal whereas the gain of nasal OKR was uneffected. In these cats only monocular cells could be found in the nucleus of the optic tract (NOT), a pretectal cell aggregation involved in the optokinetic reflex pathway. In the other 3 cats the OKR of the non-deprived eye was not different from normal and could be elicited almost equally well in both directions. In these cats binocular cells were found in the NOT ipsilateral to the non-deprived eye. Again duration (6, 24 or 36 months) of monocular deprivation had no influence on this dichotomy. 3. In a cat with asymmetric OKR of the non-deprived eye, the removal of the visual cortex ipsilateral to the non-deprived eye produced a small but significant gain decrease for temporal OKR of the non-deprived eye but no change when the deprived eye was tested. Visual cortex lesion ipsilateral to the deprived eye in the same cat had also no effect on the deprived eye's performance but reduced nasal OKR gain for the non-deprived eye at high velocities. 4. The effects induced by long term monocular deprivation were not reversed after intensively forcing the use of the deprived eye by closing the non-deprived eye. Also enucleation of the deprived eye had no effect on the gain of the non-deprived eye. 5. These optokinetic deficits are discussed in relation to functional changes in the NOT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235627
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  • 26
    Electronic Resource
    Electronic Resource
    Patterns of cytochrome oxidase activity in areas 17, 18 and 19 of the visual cortex of cats and kittens (1985)
    Springer
    Experimental brain research 58 (1985), S. 125-133 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Kitten ; Cytochrome oxidase ; Visual cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The laminar pattern of cytochrome oxidase activity was studied in visual cortical areas 17,18 and 19 in adult cats and kittens, following electrophysiological determination of the boundaries of these areas in all but the youngest animals. The patterns of cytochrome oxidase staining and the cytoarchitectonic appearances of areas 17, 18 and 19 were compared. At all ages activity was especially high in the region of layers IV and VI in areas 17 and 18, and was low in all laminae in area 19. The results suggest that the degree of cytochrome oxidase activity in these regions of the visual cortex may be related to the strength and type of projection that they receive from the lateral geniculate nucleus. The cytochrome oxidase technique is a useful means of defining the 18/19 border, and may help locate the boundary between areas 17 and 18, in both adult cats and kittens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238960
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  • 27
    Electronic Resource
    Electronic Resource
    Interaction between inhibitory pathways to principal cells in the lateral geniculate nucleus of the cat (1985)
    Springer
    Experimental brain research 58 (1985), S. 134-143 
    Details
    ISSN: 1432-1106
    Keywords: Cat ; Lateral geniculate nucleus ; Recurrent inhibitory system ; Variable gain regulator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Inhibitory interactions between interneurones of the lateral geniculate nucleus (LGN) of the cat were studied with an indirect method based on intracellular recordings of synaptic responses in principal cells. Recurrent inhibitory postsynaptic potentials (IPSPs), evoked by antidromic activation of principal cell axons in the visual cortex, were depresse by a preceding stimulation of the optic tract or the visual cortex. Disynaptic feed-forward IPSPs, evoked by optic tract stimulation, were likewise depressed after cortex stimulation. The duration of the depression was in both cases about 100 ms. The effect was not due to conductance changes in the recorded principal cells or to activation of corticogeniculate fibres. The observations indicate that perigeniculate neurones, the recurrent inhibitory interneurones of the LGN, have mutual inhibitory connexions and that they also project to intrageniculate interneurones, the inhibitory cells in the feed-forward pathway to principal cells. These conclusions were supported by intracellular recordings from a few interneurones. No evidence was found for interaction between feed-forward interneurones activated from separate eyes or for a projection from intrageniculate interneurones to perigeniculate cells. The results point to an unexpected similarity in the organization of the recurrent inhibitory system of principal cells in the LGN and of spinal motoneurones. It is suggested that the recurrent system of the LGN serves as a variable gain regulator in analogy with a recently proposed model for the spinal system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238961
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  • 28
    Electronic Resource
    Electronic Resource
    The effect of stimulation of the reticulo-hypothalamic-hippocampal systems on the cerebral blood flow and neocortical and hippocampal electrical activity in cats (1985)
    Springer
    Experimental brain research 60 (1985), S. 551-558 
    Details
    ISSN: 1432-1106
    Keywords: Reticulo-hypothalamic-hippocampal system ; Cerebral blood flow ; ECoG ; Hippocampal electrical activity ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of stimulation of the medial and lateral reticulo-hypothalamic-hippocampal (RHH) systems on cerebral blood flow (CBF) and electrical activity of the hippocampus and neocortex was examined in 19 encéphale isolé cats. ECoG was recorded from posterior sigmoid gyri and marginal gyri and hippocampal activity from dorsal hippocampus. Changes in hippocampal activity were evoked by electrical stimulation of RHH systems. CBF was measured by external monitoring of the clearance of 133Xe given as a single bolus in the carotid artery. Stimulation of the lateral system resulted in desynchronisation of ECoG and hippocampal activity without changes in CBF. Stimulation of the medial system elicited desynchronisation in ECoG modulated by theta-like synchrony, theta activity in the hippocampus and a 45% CBF increase. After atropine administration, low frequency, high voltage waves appeared in both ECoG and hippocampal activity, but no change in CBF was observed. During stimulation of the medial system there were no changes in the type of electrical activity but the CBF response was still preserved (increase by 50%). Stimulation of the lateral system did not change either the type of electrical activity or the CBF. The results indicate that the two systems of neuronal pathways, which mediate two different patterns of electrical response in the dorsal hippocampus but similar ECoG activity in the neocortex, elicit different CBF responses. It is argued that the alterations of electrical activity of the neocortex and hippocampus mediated by these two pathways depend on the cholinergic system, whereas the CBF changes depend on a different mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236941
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  • 29
    Electronic Resource
    Electronic Resource
    A developmental study of retinal afferents and visual responses in the cat pretectum (1985)
    Springer
    Experimental brain research 60 (1985), S. 350-362 
    Details
    ISSN: 1432-1106
    Keywords: Pretectum ; Development ; Retinal afferents ; Visual responses ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neuronal responses in the pretectum (PT) were analyzed in 4–16 week old kittens after visual and electrical stimulation and compared with adult responses from a previous study. All three retinal fiber types projecting to the adult PT could be electrically activated in kittens from 4 weeks on. There was a dramatic reduction of response latencies to electric shocks to retinal afferents applied at the optic chiasm (OX) and optic tract (OT) in postsynaptic cells as a function of age, involving X-, Y-, and Wfibers. At four through six weeks postnatally the reduction in latency was found to be due to enhanced signal transmission at the axonal terminal region. Latency reduction continued after six weeks of life due to sharp increases in conduction velocity of the afferent fibers. Different steps in the maturation of visual response specifity were found for neurons of different functional types. Possible relationships are discussed between the development of neuronal responses of pretectal cells and the maturation of oculomotor behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235930
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  • 30
    Electronic Resource
    Electronic Resource
    Functional and developmental analysis of a visual corticopretectal pathway in the cat: a neuroanatomical and electrophysiological study (1985)
    Springer
    Experimental brain research 60 (1985), S. 363-374 
    Details
    ISSN: 1432-1106
    Keywords: Pretectum ; Development ; Cortical influence ; Receptive field properties ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The sensory corticopretectal projection in the cat and in its postnatal development were investigated combining neuroanatomical and electrophysiological techniques. The anatomical pattern of fiber termination was studied in relation to age using the anterograde HRP tracing method. Large injections were made in areas 17 and 18 of one or both hemispheres in 1–13 week old kittens and cats. Terminal label in the ipsilateral pretectum was seen only after the fourth week of life. Electrical stimulation in the same cortical areas evoked postsynaptic orthodromic excitation in 9–18% of cells at 4 weeks increasing to about 60% in the adult. In cats, but not in kittens, successful stimulation depended on the retinotopic matching of stimulation and recording sites. In adult cats a high incidence of direction and velocity tuning and a high degree of binocularity were seen in cells driven by the cortex as opposed to cells not so driven. Cortex driven cells in cats and kittens received convergent retinal input mainly via direct W-fibers, whereas cells not driven from cortex shock mainly received delayed W-fiber input. In kittens visual responses lacked sensitivity for direction and high movement velocity of patterns until 6 weeks postnatally, whereas ocular dominance distribution was not age-dependent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235931
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  • 31
    Electronic Resource
    Electronic Resource
    Motion after-effects in cat striate cortex elicited by moving gratings (1985)
    Springer
    Experimental brain research 60 (1985), S. 411-416 
    Details
    ISSN: 1432-1106
    Keywords: Vision ; Motion after-effects ; Cat ; Visual cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Responses of striate cortical neurones to bars of optimal orientation and width, moving with fixed velocity, were recorded in the lightly anaesthetized cat. Effects of periods of pre-adaptation with square-wave gratings of variable spatial frequency and velocity, drifting continuously in each cell's preferred or null directions, were investigated. Variations of cells' directional bias and responsiveness to oriented bars were assessed in relation to the degree and time-course of pre-adaptation to drifting gratings, compared with the preceding level of firing when exposed to uniform backgrounds of the same average luminance. All cells showed some susceptibility to pre-adapting moving gratings: subsequent responses to a bar were initially depressed in the direction of pre-adaptation and, in direction-biased or bidirectional cells, were enhanced in the opposite direction, compared with bar responses following exposure merely to a uniform background. These effects were strongest and most consistent amongst standard complex cells and weakest amongst special complex cells: maximal effects were obtained with adapting gratings of optimal velocity and spatial frequency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235938
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  • 32
    Electronic Resource
    Electronic Resource
    Convergent strabismic amblyopia in cats (1985)
    Springer
    Experimental brain research 60 (1985), S. 1-9 
    Details
    ISSN: 1432-1106
    Keywords: Strabismic amblyopia ; Cat ; Retina ; Acuity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Experiments were carried out to determine the effects of different types of experimental strabismus on the acuities of retinal ganglion cells. Six kittens were raised from twenty-one days of age with an esotropia surgically induced by myectomy of the lateral rectus muscle and a large portion of the superior oblique muscle. The results are compared with those, previously reported, from five other cats also made esotropic, but by tenotomy of the lateral rectus. All animals tested behaviourally were amblyopic in the strabismic eye. For square wave gratings, the visual acuities were 1.0 to 2.5 cyc/deg through the strabismic eye compared with 6.0 to 7.5 cyc/deg through the non-deviating eye. The cut-off spatial frequencies were determined for 132 brisk sustained cells from five of the myectomized strabismic cats. There was a loss of approximately 20% in cut-off spatial frequency when compared with both normal and tenotomized cats. A correlate of the physiologically observed difference between the tenotomized cats and the myectomized cats was also found in the morphology of cells in the lateral geniculate nucleus. The tenotomized cats showed no evidence of cell shrinkage in laminae receiving a projection from the amblyopic eye whereas in the myectomized cats large differences were observed in cell cross-sectional areas between laminae receiving input from the amblyopic eye and those receiving input from the non-deviating eye. Together, these findings indicate that the presence of a neural deficit in the retina of strabismic cats is associated with the actual removal of extra-ocular muscle and probably has little to do with the optical quality of images arriving at the retina.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237012
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  • 33
    Electronic Resource
    Electronic Resource
    Binocular depth perception in the cat following early corpus callosum section (1985)
    Springer
    Experimental brain research 60 (1985), S. 19-26 
    Details
    ISSN: 1432-1106
    Keywords: Corpus callosum ; Binocular depth perception ; Stereoacuity ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The role of the corpus callosum in the mediation of binocular depth perception was examined by measuring monocular and binocular depth discrimination thresholds in cats which had undergone section of the corpus callosum shortly after birth. Three kittens had the posterior callosum sectioned at the age of eleven days. A fourth kitten underwent a sham operation and one additional animal served intitially as an unoperated control. Monocular and binocular depth thresholds were measured for all kittens when they were between three and five months old. Although there was some individual variability, none of the callosum-sectioned kittens showed any deficits of binocular depth perception relative to normal animals. The initially unoperated kitten had its callosum sectioned at five months and was retested following surgery. Its performance did not change from preoperated levels. Finally, the three neonatal callosum-sectioned kittens underwent section of the optic chiasm when they were six months old, causing a complete breakdown in binocular depth discrimination. The results are interpreted to indicate that although the corpus callosum may be a sufficient pathway for the maintenance of stereopsis in cat, it is not necessary.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237014
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  • 34
    Electronic Resource
    Electronic Resource
    Efferent connections of area 20 in the cat: HRP-WGA and autoradiographic studies (1985)
    Springer
    Experimental brain research 60 (1985), S. 179-183 
    Details
    ISSN: 1432-1106
    Keywords: Area 20 ; Corticofugal connections ; Pupilloconstrictor area ; Near reflex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Following injections of horseradish peroxidase-wheat germ agglutinin conjugate (HRP-WGA) and tritiated leucine into area 20 of the cat, terminal labeling was observed in visual areas 19, 21, the splenial visual area, the lateral suprasylvian area as well as in premotor, association and limbic related cerebral cortical regions. Labeled terminals in the subcortex were distributed in the caudate nucleus, the claustrum, the putamen, the anterior ventral nucleus, the intralaminar nuclei, the caudal division of the intermediate lateral nucleus, the lateralis posterior-pulvinar complex, the parvocellular C laminae of the dorsal lateral geniculate nucleus and the ventral lateral geniculate nucleus. In HRP-WGA preparations, retrogradely labeled somata were observed in these regions with the exception of certain subcortical structures. The projections are discussed with respect to the possible role area 20 plays in the cortical control of pupillary constriction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237029
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  • 35
    Electronic Resource
    Electronic Resource
    A β-carboline antagonizes benzodiazepine actions but does not precipitate the abstinence syndrome in cats (1985)
    Springer
    Psychopharmacology 86 (1985), S. 132-136 
    Details
    ISSN: 1432-2072
    Keywords: β-Carbolines ; FG 7142 ; Benzodiazepines ; Diazepam ; Ro 15-1788 ; Drug dependence ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The β-carbolines, which are potent ligands for benzodiazepine receptors, antagonize the pharmacological actions of benzodiazepines. In the cat, the stable β-carboline derivative methylamide-β-carboline-3-carboxylate, FG 7142, and the specific benzodiazepine antagonist Ro 15-1788 reversed behavioral and electroencephalographic (EEG) changes produced by a single dose of diazepam. Surprisingly, the β-carboline did not elicit signs of withdrawal when given after 22 days of a daily dose regimen of diazepam, while Ro 15-1788 precipitated an acute abstinence syndrome largely characterized by tremors, increased muscle tone, back arching, myoclonic jerks and pupil dilatation. Unlike Ro 15-1788, the β-carboline produced effects of its own such as behavioral states of arousal and fearfulness. These findings indicate that the β-carboline functionally interacts with benzodiazepine receptors in a manner unlike that seen with typical agonists and antagonists.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00431697
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  • 36
    Electronic Resource
    Electronic Resource
    The effect of age and body size on the urinary excretion of C-peptide from birth to 14 years of age (1985)
    Springer
    European journal of pediatrics 143 (1985), S. 183-186 
    Details
    ISSN: 1432-1076
    Keywords: C-peptide ; Growth hormone deficiency ; Obesity ; Insulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The daily excretion of C-peptide in the urine was measured in 105 healthy infants and children from birth to 14 years of age. For technical reasons no studies were performed from 1–3 years of age. The excretion of C-peptide showed a close positive correlation with age and weight. The relationship with weight was already apparent in the 1st days of life. The C-peptide/weight and the C-peptide/creatinine ratios were constant throughout most of childhood with the exception of the age range of 1 month-1 year when the C-peptide/creatinine was significantly higher. In obese children the C-peptide/weight and C-peptide/creatinine ratios were similar to those found in children with normal weight. In growth hormone deficiency these ratios were low and increased during the 1st week of growth hormone therapy. It is concluded that urinary C-peptide is a reliable indicator of integrated insulin production and gives new information about insulin secretion in various conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00442133
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  • 37
    Electronic Resource
    Electronic Resource
    Electrical stimulation of arterial and central chemosensory afferents at different times in the respiratory cycle of the cat: I. Ventilatory responses (1985)
    Springer
    Pflügers Archiv 403 (1985), S. 415-421 
    Details
    ISSN: 1432-2013
    Keywords: Arterial chemoreceptors ; Cat ; Control of breathing ; Electrical stimulation ; Intracranial chemosensitivity ; Oesophageal pressure ; Respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Ventilatory responses to stimulation of chemoreceptor afferents were studied in the anesthetized, spontaneously breathing cat. Short bursts of electrical stimuli were applied, at various times in the inspiratory or expiratory phase of consecutive breaths, to the carotid sinus (CSN) and aortic nerves (AN) and to the ventral medulla (VM), and effects on tidal volume (V T), inspiratory, expiratory and cycle durationst I,t E,t tot) and in ventilation (E) were measured. The responses evoked by stimulating CSN, AN and VM were qualitatively the same, although there were quantitative differences. It was found that effects of stimulation in expiration were restricted to the expiratory phase, and vice versa for inspiration. Stimulation during both inspiration and expiration resulted in increasedV T, by increasing end-inspiratory or decreasing end-expiratory lung volume, respectively, and also increased ventilation, E. These effects were most marked in response to stimulation in inspiration. During both phases there was an increasing effect with increasing delay of the stimulus,t St, from onset of inspiration or expiration, respectively. There was a continuous increase int I, from below control to above control values, with increasingt St during inspiration and similarly fort E during expiration. Hence, the total respiratory cycle duration was shortened when a stimulus was applied early in either phase, and was prolonged, when it was applied late. The results show that stimulation of peripheral and of central chemoafferents exerts qualitatively similar effects on respiration. The central neuronal mechanisms generating both inspiration and expiration show the same changes in reactivity in the respiratory cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00589255
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  • 38
    Electronic Resource
    Electronic Resource
    Basolateral membrane responses to transport modifiers in the frog skin epithelium (1985)
    Springer
    Pflügers Archiv 405 (1985), S. S33 
    Details
    ISSN: 1432-2013
    Keywords: Sodium transport ; Epithelial transport ; Transport regulation ; Frog skin ; Oxytocin ; Ouabain ; Insulin ; Neurohypophysial hormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract 1. Application of transepithelial square voltage pulses to the frog skin leads to responses in the transepithelial current and intracellular potential which include transient components. Determinations at 600 ms allow for meaningful estimates of basolateral membrane responses to transport modifiers. 2. Oxytocin produced a large and sustained increase in the amiloride-inhibitable short circuit current (I m) which was accompanied by a large increase of both apical and basolateral membrane conductance (g a andg b, respectively). WhileI m andg a increased nearly simultaneously,g b started to increase several minutes after the increase in the two other parameters. 3. Insulin also increasedI m,g a andg b. As with oxytocin, the increases inI m andg a often preceded the changes ing b. 4. Ouabain reducedI m andg a. The effects ofg b were more complex, since sometimes the inhibition ofI m was first accompanied by an increase followed by a decrease while in other instances only minor changes in conductance could be observed. 5. The currently available information regarding the control of cytoplasmic [Ca2+] and the effects of Ca2+ on cell membrane properties are used to construct a model in which changes in cytoplasmic [Ca2+] account for the observed behavior of the basolateral membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581777
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  • 39
    Electronic Resource
    Electronic Resource
    Increase in insulin response to glucose in the rat chronically treated with clonidine (1985)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 328 (1985), S. 253-257 
    Details
    ISSN: 1432-1912
    Keywords: Clonidine ; Insulin ; Glucose ; Hyper-responsiveness ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Effect of chronic clonidine treatment on the response to glucose of rat pancreatic B-cells was investigated. Clonidine treatment was carried out for 10 days by dissolving the drug into drinking water at a concentration of 10 μg/ml. Control rats were given drug-free tap water. Serum insulin responses to glucose (750 mg/kg, i. v.) of clonidinetreated rats were much smaller than those of control rats. However, after 1 day's withdrawal of clonidine, the rise in the serum insulin level induced by glucose was approximately 2-fold larger in clonidine-treated rats as compared to that in control rats. Since clonidine treatment decreased body weight of the rat by 10%–20% in 10 days, the same experiments were carried out with rats whose body weight loss was made comparable to that of clonidine-treated rats by restricting food for 10 days. Then, some animals of the group thus treated had food-restriction discontinued for 1 day. In both of the above two groups, no increment in glucoseinduced rise in serum insulin level was observed. Islets of Langerhans isolated from clonidine-treated rats showed pronounced insulin releasing capacity in response to glucose. Insulin content per islet of the clonidine-treated rat was slightly larger than that of control rat. These results indicate that the enhancement of serum insulin response to glucose following clonidine treatment is mainly attributable to the hyper-responsiveness developed in the pancreatic B-cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00515550
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  • 40
    Electronic Resource
    Electronic Resource
    Characteristics of the receptors in the isolated capsule of the hip in the cat (1985)
    Springer
    International orthopaedics 9 (1985), S. 123-127 
    Details
    ISSN: 1432-5195
    Keywords: Hip Capsule ; Cat ; Afferent receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les auteurs ont étudié les propriétés des nerfs afférents à la capsule de la hanche, chez le chat en imprimant à l'articulation des mouvements de rotation et sur des préparations de capsule isolée et ouverte en l'étirant directement grâce à un dispositif mécanique. In situ, on a trouvé deux types de nerfs afférents, les uns ayant en réponse à la rotation articulaire une étendue complète de sensibilité et les autres seulement une sensibilité limitée. Sur la capsule isolée les nerfs afférents sont indentiques en ce qui concerne le seuil et la sensibilité et on ne trouve aucun récepteur complet. On en conclut que les récepteurs de toute l'étendue de la sensibilité qui pénètrent les nerfs articulaires de la hanche sont des fibres en fuseau d'origine musculaire et non des récepteurs capsulaires. Sur ces bases et sur les résultats précédemment obtenus chez l'animal et chez l'homme, les auteurs discutent le rôle des récepteurs articulaires dans la cénesthésie et le sens des positions.
    Notes: Summary The properties of the afferent fibres from the capsule of the hip joint have been studied in the cat in situ, in relation to joint rotation, and in an isolated capsule preparation which was opened and stretched directly with an actuator. In situ two types of afferent fibres were found, those having a full range of sensitivity and others having only a limited range in response to the joint rotation. When studied in isolated tissue the afferent fibres of the capsule were uniform in threshold and sensitivities, and no full range receptors were found. We conclude that the full range receptors which enter the articular nerve of the hip are spindle afferents and not capsule receptors. On the basis of these and previous results in animals and man the role of joint receptors in kinaesthesia and position sense is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00266954
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  • 41
    Electronic Resource
    Electronic Resource
    Immuno-electron-microscopic localization of a centriole-related antigen in ciliated cells (1985)
    Springer
    Cell & tissue research 239 (1985), S. 43-50 
    Details
    ISSN: 1432-0878
    Keywords: Centriolar antigen ; Basal body ; Immunoelectron microscopy ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An antigen common to purported centriolar and basal body regions of a variety of cell types was previously visualized by immuno-fluorescence microscopy. The present study demonstrates the localization of the antigen relative to the defined basal body structures of ciliated tracheal cells at the electron-microscopic level. After ethyldimethylaminopropyl carbodiimide-glutaraldehyde-saponin (EGS) fixation and permeabilization, immunoferritin labeling is consistently found associated with amorphous electron-opaque material in proximity to basal bodies and their ciliary rootlets, but not with basal body microtubules themselves. This distribution pattern is distinct from that of other proteins found in the apical region of ciliated cells, such as calmodulin. It is proposed that the dense material may be analogous to pericentriolar material of centrosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214901
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  • 42
    Electronic Resource
    Electronic Resource
    Lysosomes and pancreatic islet function (1985)
    Springer
    Cell & tissue research 239 (1985), S. 537-545 
    Details
    ISSN: 1432-0878
    Keywords: Mouse ; Pancreas, endocrine ; Insulin ; Acid phosphatase ; Lysosomes ; Crinophagy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The relation between qualitative and quantitative glucose-dependent alterations of lysosomes in pancreatic islets and the function of the islets was studied. Isolated islets of the mouse were maintained in tissue culture for one week in either 28, 5.5 or 3.3 mmol/l glucose. Insulin biosynthesis, insulin secretion and insulin content of the cultured islets were determined. After culture, the islets were subjected to acid phosphatase cytochemistry and examined by electron microscopy and ultrastructural morphometry. Islets cultured in 28 mmol/l glucose both produced and secreted insulin rapidly. Such islets seemed, however, unable to maintain more than small amounts of granule-stored insulin. Islets cultured at the lower concentrations of glucose displayed a reduced insulin secretion, which apparently resulted in considerable amounts of intracellularly stored insulin. In all cultured islets different types of lysosomes, identified by their acid phosphatase reactivity, could be seen. Dense bodies, i.e., lysosomes characterized by a homogeneous, very fine, particulate content of high density, seemed to predominate at all concentrations of glucose. It is suggested that, in the islets, the dense bodies correspond morphologically to primary lysosomes. Other types of lysosomes with inclusions of various kinds, which were frequent at the two lower concentrations of glucose, may correspond to secondary lysosomes. Morphometry revealed differences between the size distributions of lysosomes in the three experimental groups. Thus, the average lysosomal size was inversely proportional to the concentration of glucose in the culture medium. However, the numerical density of lysosomes was greatest at the highest glucose concentration. The observation of secondary lysosomes, containing material resembling secretory granules, suggests that the increased size and lowered number of lysosomes in islets cultured at low glucose concentrations may depend on a crinophagic process. Such a process, together with insulin biosynthesis and insulin secretion, may be of physiological importance for control of the secretory granule content within the pancreatic B-cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219232
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  • 43
    Electronic Resource
    Electronic Resource
    Oligodendrocytes in the pons and middle cerebellar peduncle of the cat (1985)
    Springer
    Cell & tissue research 240 (1985), S. 541-552 
    Details
    ISSN: 1432-0878
    Keywords: Oligodendroglia ; Neuroglia ; Perineuronal satellites ; Interfascicular glia ; Pons ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Morphology, microtopography and numerical density of oligodendrocytes were analyzed by light microscopy in the pontine gray and middle cerebellar peduncle of adult cats. The cells were selectively stained by use of the dicyanoargentate technique (Ogawa et al. 1975) that visualizes the entire cell population including perikarya and characteristic features of processes. On the basis of different microtopographical relations to neuronal perikarya and/or transversely oriented axon bundles, six groups of oligodendrocytes were separately analyzed: interfascicular, intrafascicular, perifascicular, perineuronal satellite, perifascicular-perineuronal, and “neuropil” cells. The cell morphology did not co-vary with any of these groups, but the shape of oligodendrocytes was on an average more elongated in the peduncle than in the pontine gray. The average cell density was similar in the gray and white matter (55000–56000 cells/mm3). However, 76% of the cells were concentrated near neuronal perikarya and axon bundles in a volume fraction of only 34%. Between adjacent neurons and axon bundles the cell density was even higher suggesting an additive behavior of these two topographical groups of oligodendrocytes. Axon bundles within the pontine gray contained only very few oligodendrocytes (density 6% that of the peduncle). These observations and quantitative data suggest that the perifascicular cells belong to the group of oligodendrocytes that are topographically related to axons (similar to interfascicular glia of the white matter) rather than to neuronal perikarya or neuropil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216343
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  • 44
    Electronic Resource
    Electronic Resource
    Extravasation of polymorphonuclear leukocytes from the cerebral microvasculature (1985)
    Springer
    Cell & tissue research 242 (1985), S. 399-407 
    Details
    ISSN: 1432-0878
    Keywords: Cerebral microvasculature ; Inflammatory reaction ; Polymorphonuclear leukocytes ; α-Bungarotoxin ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Postcapillary venules represent the segment of the microvasculature most vulnerable to inflammatory processes. While there is a considerable body of data on the peripheral vasculature, little is known about the primary events occurring during inflammatory reactions in cererbral blood vessels. We introduce here a model by which the migration of polymorphonuclear leukocytes through the CNS endothelial barrier can be studied. Alpha-bungarotoxin is used as a chemotactic agent and is shown, for the first time, to act by activating the complement cascade. Leukocytes migrate through the endothelium transcellularly. Two modes of migration are described: (i) a direct mode whereby the cells use temporary pores in the vessel wall as portals, and (ii) an indirect mode whereby the leukocytes leave the vascular compartment after being enveloped by and incorporated into endothelial cells. The functional implications of these findings lead us to conclude that the direct mode of migration is a causal agent in the massive breakdown of the blood-brain barrier under acute inflammatory conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214554
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  • 45
    Electronic Resource
    Electronic Resource
    Substance P-immunoreactive neurons in the brainstem of the cat related to cardiovascular centers (1985)
    Springer
    Cell & tissue research 241 (1985), S. 31-41 
    Details
    ISSN: 1432-0878
    Keywords: Substance P ; Cardiovascular system ; Central nervous system ; Immunohistochemistry ; Mapping ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of substance P-immunoreactivity (SP-IR) in the brainstem and spinal cord of normal and colchicine-pretreated cats was analysed using the peroxidase-antiperoxidase (PAP) technique. Numerous SP-IR fibers are present in the nucleus solitarius, nucleus dorsalis nervi vagi and nucleus spinalis nervi trigemini, various parts of the formatio reticularis, substantia grisea centralis mesencephali, locus coeruleus and nucleus parabrachialis. SP-IR perikarya occur in the substantiae gelatinosa and intermedia of the spinal cord, the nucleus spinalis nervi trigemini-pars caudalis, the nucleus dorsalis nervi vagi, and the nucleus solitarius, as well as in the adjacent formatio reticularis and the medullary nuclei of the raphe. In addition, SP-IR cell bodies are located in the nuclei raphe magnus and incertus, ventral and dorsal to the nucleus tegmentalis dorsalis (Gudden), nucleus raphe dorsalis, substantia grisea centralis mensencephali, locus coeruleus, nucleus parabrachialis and colliculus superior. The results indicate that SP-IR neurons may be involved in the regulation of cardiovascular functions both at the central and peripheral level. A peripheral afferent portion seems to terminate in the nucleus solitarius and an efferent part is postulated to originate from the nucleus dorsalis nervi vagi and from the area of the nuclei retroambiguus, ambiguus and retrofacialis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214623
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  • 46
    Electronic Resource
    Electronic Resource
    Effects of a 24-h carbohydrate-poor diet on metabolic and hormonal responses during prolonged glucose-infused leg exercise (1985)
    Springer
    European journal of applied physiology 54 (1985), S. 420-426 
    Details
    ISSN: 1439-6327
    Keywords: Glycemia ; Glucose infusion ; Diet ; Free fatty acids ; Insulin ; Exercise in humans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Extant literature dealing with metabolic and hormonal adaptations to exercise following carbohydrate (CHO) reduced diets is not sufficiently precise to allow researchers to partial out the effects of reduced blood glucose levels from other general effects produced by low CHO diets. In order to shed light on this issue, a study was conducted to examine the effects of a 24-h CHO-poor diet on substrate and endocrine responses during prolonged (75 min; 60% $$\dot V_{O_{2max} } $$ ) glucose-infused leg exercise. Eight subjects exercised on a cycle ergometer in the two following conditions: 1) after a normal diet (CHON), and 2) after a 24-h low CHO diet (CHOL). In both conditions, glucose was constantly infused intravenously (2.2 mg · kg−1 · min−1) from the 10th to the 75th min of exercise in relatively small amounts (10.4±0.8 g). No significant differences in blood glucose concentrations were found between the two conditions at rest and during exercise although a significant increase (p〈0.01) in glucose level was observed in both conditions after 40 min of exercise. The CHOL as compared to the CHON condition, was associated with significantly (p〈0.05) lower resting concentrations of insulin, muscle glycogen (8.7 vs 10.6 g · kg−1), and triacylglycerol, and greater concentrations of Β-hydroxybutyrate (0.5 vs 0.2 mmol · L−1), and free fatty acids. During exercise, the CHOL condition as compared to the CHON condition, was associated with significantly (p〈0.05) lower insulin and R values, as well as greater free fatty acid (from min 20 to 60) and epinephrine (min 60 to 75) concentrations. Norepinephrine and glucagon concentrations also showed a net tendency (p〈0.06) to be higher in the CHOL condition. There were no significant differences at rest and during exercise in blood lactate and cortisol concentrations between the two conditions. These results demonstrate that blood glucose is not the sole determinant of the metabolic and hormonal responses during prolonged exercise following a low CHO intake and indicate that other factors may be involved in the regulatory mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02337188
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  • 47
    Electronic Resource
    Electronic Resource
    Contribution of the exercise-induced increment in glucose storage to the increased insulin sensitivity of endurance athletes (1985)
    Springer
    European journal of applied physiology 54 (1985), S. 231-236 
    Details
    ISSN: 1439-6327
    Keywords: Glucose storage ; Insulin ; Exercise-training ; Athletes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present study was designed to evaluate the contribution of the exercise-induced increment in glucose storage to the increased insulin sensitivity characterizing endurance athletes. Plasma glucose and insulin were measured during an oral glucose tolerance test (OGTT) in six endurance athletes. Glucose storage and lipid oxidation during this test were also determined using indirect calorimetry. These measurements were compared to those obtained in five non-trained subjects who were tested before and during the three days following a 90-min cycle ergometer exercise performed at 69% of their $$\dot V_{{\text{O}}_{{\text{2max}}} }$$ . As expected, preexercise values of non-trained subjects revealed a much higher insulin response to glucose, and a lower glucose storage and lipid oxidation compared to results obtained in endurance trained individuals. Glucose tolerance was comparable in both groups. The morning following the exercise test, i. e. about 16 h after exercise, glucose storage was significantly increased in non-trained subjects to a level similar to that found in trained subjects. Surprisingly, this was accompanied by higher values of glucose during the OGTT without significant changes in insulinaemia. This impairment in glucose homeostasis was transitory since glucose tolerance had returned to control level on day 2 after exercise. At that time, the increase in glucose storage was less pronounced than in day 1. On day 3 after exercise, glucose and insulin responses to glucose were similar to preexercise values. These results indicate that the increase in glucose storage by acute exercise is not systematically associated with an improved glucose homeostasis, suggesting that other adaptive mechanisms also contribute to the improvement of insulin sensitivity in endurance athletes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00426138
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  • 48
    Electronic Resource
    Electronic Resource
    Hormonal and metabolic response to three types of exercise of equal duration and external work output (1985)
    Springer
    European journal of applied physiology 54 (1985), S. 337-342 
    Details
    ISSN: 1439-6327
    Keywords: Exercise ; Anaerobic ; Aerobic ; Cortisol ; Glucagon ; Insulin ; Lactate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Five normal men, aged 20–30 years, participated in three types of exercise (I, II, III) of equal duration (20 min) and total external work output (120–180 kJ) separated by ten days of rest. Exercises consisted of seven sets of squats with barbells on the shoulders (I; Maximal Power Output $$\dot W$$ max=600−900 W), continuous cycling at 50 rev · min−1 (II; $$\dot W$$ max=100−150 W) and seven bouts of intermittent cycling at 70 rev · min−1 (III; $$\dot W$$ max=300−450 W). Plasma cortisol, glucagon and lactate increased significantly (P〈0.05) during the exercise and recovery periods of the anaerobic, intermittent exercise (I and III) but not in the continuous, aerobic exercise (II). No consistent significant changes were found in plasma glucose. Plasma insulin levels decreased only during exercise II. The highest increase in cortisol and glucagon was not associated with the highest $$\dot V_E $$ , $$\dot V_{O_2 } $$ , $$\dot W$$ max or HR; however it was associated with the anaerobic component of exercise (lactic acid). It is suggested that in exercises of equal duration and total external work output, the continuous, aerobic exercise (II) led to lowest levels of glucogenic hormones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02337175
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  • 49
    Electronic Resource
    Electronic Resource
    Insulin and new bone formation in diffuse idiopathic skeletal hyperostosis (1985)
    Springer
    Clinical rheumatology 4 (1985), S. 294-300 
    Details
    ISSN: 1434-9949
    Keywords: Insulin ; Hyperostosis ; DISH ; New Bone Formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The tendency of patients with DISH towards obesity or an adult onset of diabetes has been reflected in marked hyperinsulinaemia following glucose challenge. It is hypothesized that insulin at prolonged and high physiologic levels promotes new bone growth, particularly in the entheseal regions. These areas are also subject to various mechanical forces. The resulting new bone produces the radiological changes which characterise DISH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02031611
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  • 50
    Electronic Resource
    Electronic Resource
    Masthead (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985) 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680101
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  • 51
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    Electronic Resource
    Inverted Hyperconjugation in Symmetrical 1,4-DihalocubanesPart IV of ‘The Equivalent Bond Orbital Model Revisited’ (Part III: [1]), and Part 50 of ‘Small and Medium Rings’ (Part 49: [1]). (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 23-38 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The σ-orbital manifold of cubane 1, as suggested by its PE spectrum, is divided into two sets separated by a 3 eV gap extending from ∼ -10.5 eV to ∼ -13.5 eV. Halogen substituents with np AO basis energies falling into this gap (e.g. Cl or Br) will, therefore, hyperconjugate appreciably with both sets. Interaction with the lower-lying set will lead to the usual destabilization (‘normal’ hyperconjugation), whereas interaction with the set above will necessarily lead to a ‘stabilization’ (‘inverted’ hyperconjugation). As a result the lone-pair ionization energies of Cl or Br substituted cubanes (derived from PE spectra) are much larger than naively expected for an alkyl halide containing as much as 8 C-atoms. In particular no significant shift of the eg-1 lone-pair bands in the PE spectra of 1,4-dichloro- and 1,4-dibromocubane can be detected with respect to the first ionization energies of the free atoms Cl and Br, or of HCl and HBr.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680104
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  • 52
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    Sesquiterpenoids of the Sponge Dysidea fragilis of the North-Brittany SeaPresented by F.P. as a part of a lecture at the University of Innsbruck on March 15th, 1984. (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 39-48 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title sponge is shown to contain eight new sesquiterpenoids for which a common, unusual biogenetic origin is postulated. The compounds are shown to be: (-)-(1R*,4R*)-3-(3′-furyl)methyl-2-p-menthen-7-yl acetate ((-)-8b); two diols separated as the monoacetates (-)-(1S*,4R*)-3-(3′-furyl)methyl-l-hydroxy-2-p-menthen-7-yl acetate ((-)-13a) and the (-)-(1R*,4R*)-epimer (-)-13b, the two C(4)-epimeric 4-ethoxy-3-(1′(7′),2′-p-menthadien-3′-yl)methyl-2-buten-4-olides ((+)-14a and (-)-14b), (-)-3-(3′-furyl)methyl-7-nor-2-p-menthen-l-one ((-)-11), (-)-(3Z)-1-(3′-furyl)-4,8-dimethylnona-3, 7-dien-2-yl acetate ((-)-17), and (+)-3-(5′,7′-seco-2′(10′)-pinen-7′-yl)methylfuran ((+)-15).
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    Melanotropin Receptors I. Synthesis and Biological Activity of Nα-(5-Bromovaleryl)-Nα-deacetyl-α-melanotropinParts of this report have appeared as a thesis [1]. Nomenclature and abbreviations [2]. Additional abbreviations: MSH = melanophore stimulating hormone (melanotropin), DCC = N, N′-dicyclohexylcarbodiimide, DCU = N, N′-dicyclohexylurea, DMF = dimethylformamide, HOBt = 1-hydroxybenzotriazole, Boc = tert-butoxycarbonyl, OBut = tert-butoxy, Msoc = 2-(methylsulfonyl)ethoxycarbonyl, Np = 4-nitrophenyl, Z = benzyloxycarbonyl, TFA = trifluoroacetic acid. Chiral amino acids are in their L-configuration. Culture media see Experimental.Dedicated to Dr. Nitya Anand, Director of the Central Drug Research Institute, Lucknow, India, on the occasion of his 60th birthday (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 1-11 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemical synthesis and biological activities of a new α-melanotropin derivative are described. Nα-(5-Bromovaleryl)-Nα-deacetyl-α-melanotropin contains the 5-bromopentanoyl group as a chemical ‘handle’ in place of the acetyl group of the natural hormone. The synthesis involved a new protected intermediate which allowed the selective deprotection of either the Nα or Nα amino group. The title compound reacted with sodium thiosulfate to give Nα-deacetyl-Nα-(5-(sulfothio)valeryl)-α-melanotropin, a key intermediate for the preparation of tobaccomosaic virus/α-melanotropin disulfide conjugates. As a basis for the study of the conjugates, biological activities of the title compound on Cloudman S-91 mouse melanoma cell cultures (tyrosinase stimulation, binding, and cyclic AMP accumulation) were determined. They proved to be quite similar to the corresponding α-melanotropin activities. Differences in bindings may be explained by stronger hydrophobic interaction of the new derivative with the lipid phase of the target cell membranes.
    Additional Material: 9 Ill.
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    Bond Angles in Lactones and Lactams (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 76-82 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The carbonyl group in lactones and, to a lesser extent, in lactams tends to show a C—C=O angle that is larger than the O—C=O or N—C=O angle, the difference increasing in magnitude as the ring size decreases. The observed trend provides information on ratios of force constants characterising the flexibility of the s-cis-ester group and may be interpreted in terms of incipient chemical reaction to -O—(CH2)n—C≡O+. Molecular orbital calculations (MINDO/3, MNDO, EH) for model compounds provide an electronic interpretation of this angle difference in terms of an anomeric interaction between the p-type lone pair on the carbonyl O-atom and the antibonding C-O or C-N orbital.
    Additional Material: 3 Ill.
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    Cyclic Octa- and Decapeptides as Ionophores for Magnesium (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 110-118 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic octa- and decapeptides have been prepared, and their ion selectivity in solvent polymeric membranes was studied. Cyclo(-LPro-DLeu-)5 behaves as an ionophore which selects Mg2+ over Ca2+ by a factor of 100. Cyclo(LPro-LLeu)5 induces selectivity in membranes for Mg2+ over Li+, Na+ and K+ by a factor of 400, 200 and 10, respectively, while selectivity of Mg2+ over Ca2+ is poor. Some evidence is presented which indicates that certain ionophores exhibit high selectivity for monovalent magnesium complexes.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19850680114
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    Stereoselective Double Functionalization of Iron-Carbonyl Complexes of 5,6,7,8-Tetramethylidenebicyclo[2.2.2]oct-2-ene. Crystal Structure and Absolute Configuration of (-)-trans-μ-[(2S,5R,7S)-C,5,6,C-η:C,7,8,C-η-(6,7,8-trimethylidene-5-((Z)-2-oxopropylidene)-2-bicyclo[2.2.2]octyl acetate)]-bis(tricarbonyliron) (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 126-134 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Friedel-Crafts monoacylation of trans-η-[(1RS,2RS,4SR,5SR,6RS,7SR,8SR)-C,5,6,C-η:C,7,8,C-η-(5,6,7,8-tetramethylidene-2-bicyclo[2.2.2]octyl acetate)]-bis(tricarbonyliron) ((±)-5) is highly stereoselective and yields trans-η-[(1RS,2RS,4RS,5SR,6RS,7RS,8SR)-C,6-η,oxo-σ:C,7,8,C-η-(6,7,8-trimethylidene-5-((Z)-2-oxopropylidene)-2-bicyclo[2.2.2]octyl acetate)]-bis(tricarbonyliron) ((±)-8) which equilibrates with the trans-η-[(1RS,2RS,4RS,5SR,6RS,7RS,8SR)-C,5,6,C-η:C,7,8,C-η-(6,7,8-trimethylidene-5-((Z)-2-oxopropylidene)-2-bicyclo[2.2.2]octyl acetate)]-bis(tricarbonyliron) ((±)-9) on heating. Optically pure (-)-9 has been prepared from the corresponding optically pure alcohol (+)-4. The structure and absolute configuration of (-)-9 was established by single-crystal X-ray diffraction.
    Additional Material: 4 Tab.
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    Alkylierung in der 2-Stellung von (2S, 4R)- 4-Hydroxyprolin unter Retention (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 155-161 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkylation in the 2-Position of (2S, 4R)-4-Hydroxyproline with Retention of ConfigurationO-Acetyl-4-hydroxyproline (1b) is condensed with pivalaldehyde to give a single stereoisomer of the 2-(tert-butyl)-4-oxo-3-oxa-1-azabicyclo[3.3.0]oct-7-yl acetate (3). This is converted to the enolates 4 or 5, reactions of which with alkyl halides, aldehydes, and acetone (→6,9,10,11) are diastereoselective (lk-1,3-induction). Cleavage of the corresponding products furnishes the enantiomerically pure 2-deuterio-, 2-methyl-, 2-allyl-, and 2-benzyl-substituted 4-hydroxyprolines 2a-2d.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19850680119
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    Über den sterischen Verlauf der Umsetzung von Enaminen aus offenkettigen Aldehyden und Ketonen mit Nitroolefinen zu 2,3-disubstituierten 4-NitroketonenTeilweise in einer Kurzmitteilung beschrieben [1]. (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 162-172 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Steric Course of the Reaction of Enamines Derived from Open-Chain Aldehydes and Ketones with Nitro-olefins Yielding 2,3-Disubstituted 4-NitroketonesThe relative configuration of the nitro-ketone 12 obtained by the title reaction has been proved by a Baeyer-Villiger degradation and subsequent reduction to the amino-alcohol (±)-(u)-20, the relative configuration of which is identical with a sample prepared from 2-methyl-3-hydroxybutyrate of known configuration (Scheme 1). The stereochemical course of the title reaction is thus as predicted by our topological rule. It is assumed that the other nitro-ketones 13-18 described here are also formed by (lk)-combination of the trigonal centers of the educts (diastereoselectivity 〉 90%, see Formulae and Fig. 1). It is not possible to reverse this relative topicity by employing (Z)- instead of (E)-components of the starting materials, due to the reversibility of the primary step of these Michael additions (Schemes 2 and 3, and Fig. 2).
    Additional Material: 2 Ill.
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    Photochemical reactions. 142nd communication141st Communication: [1].. Photochemistry of a 6,7-epoxy-1,3-diene of the ionone series (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 207-211 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On singlet excitation (λ = 254 nm), the epoxydiene (E)-3 underwent (E)/(Z)-isomerization, electrocyclic ring closure of the diene side chain leading to the cyclobutenes 4A + B, and rearrangement to the cyclohexanones 5A + B. Compounds 5A + B were presumably formed in a series of processes including a 1,3-acyl shift of the homoconjugated ketone 8, arising from (Z)-3 by a 1,5-H-shift accompanied by cleavage of the C,O-bond of the oxirane.
    Additional Material: 1 Tab.
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    Camphorsulfonamide-Shielded, Asymmetric 1,4-Additions and Enolate Alkylations; Synthesis of a Southern Corn Rootworm Pheromone. Preliminary CommunicationPresented in part at the Autumn Meeting of the Swiss Chemical Society, Berne, October 19, 1984. (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 212-215 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using readily accessible 10-sulfonamido-isoborneols as regenerable, chiral auxiliaries, highly face-selective C-C-bond formations at Cα and Cβ of carboxylates could be conveniently achieved. Thus, conjugated additions of RCu to enoates (1→2) furnished, after saponification, β-substituted carboxylic acids 3 in 94-98% e.e. Similarly, propionates 12 yielded after deprotonation, enolate alkylation, and reductive ester cleavage the (R)-alcohols 15 in 78-98% e.e. The acid (+)-3e was converted to the pheromone (-)-11.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19850680126
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    The crystal structure of racemic and meso-diastereoisomers of aqua[2,6-bis(3-carboxy-1,2-dimethyl-2-azapropyl)pyridine]-Co(III) · Hexafluorophosphate · Di- and monohydrate, respectively (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 185-191 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of the pentadentate ligand 2,6-bis(3-carboxy-1,2-dimethyl-2-azapropyl)pyridine yields a mixture of the racemic and meso-isomers which it was difficult to separate by column chromatography. When the cationic Co(III)-complex of this ligand was crystallized with hexafluorophosphate as anion, two distinct crystalline forms were produced. The complex of the racemic ligand, 1, has C2 symmetry and is a dihydrate; a = 8.999(8), b = 12.047(6), c = 20.65(1) Å, orthorhombic, space group Peen,Z = 4, R = 0.074 for 1439 observed reflections. The complex of the meso-ligand, 2, shows two independent molecules (2A and 2B) per asymmetric unit, both monohydrates with a resolved disordered H2O molecule in 2A; a = 10.109(4), b = 12.835(2), c = 16.651(3) Å, α = 89.5(1)°, β = 84.7(3)°, γ = 88.6(3)°, triclinic, space group P1, Z = 4, Rs = 0.054 for 4198 observed reflections. The coordination around the Co-atom is distorted octahedral in both complexes, with the coordinated H2O molecule trans to the pyridine N-atom. In the racemic form of the complex, 1, the pyridine ring is twisted about the Co-N(1) bond with respect to the plane defined by atoms Co, N(1), O(W1), N(2) and N(2P) by 17.2(2)°. In the meso-form of the complex, 2, the CH3 substituent C(8P) on atom C(4P), is now axial with respect to the 5-membered chelate ring. As a result of steric hinderance between atom O(1) and CH3(8P), the pyridine ring has been displaced from the best mean-plane formed by atoms Co, O(W1), N(2) and N(2P). The principal axis of the pyridine ring C(3)…N(1), makes an angle of 14.1(1)° (mean) with this plane. At the same time the pyridine ring is twisted about axis C(3)…N(1) with respect to this plane by 19.7(1)° (mean).
    Additional Material: 2 Ill.
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    Halochrome Molekeln. 6. Mitteilung. Spektrophotometrische Untersuchungen zum acidobasischen Verhalten substituierter 6,6-Diphenyl-6H-chromeno[4,3-b]indolizine und ihrer Aza-analogen (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 64-71 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Halochromic Molecules. Spectrophotometric Investigation of the Acidobasic Behaviour of Substituted 6,6-Diphenyl-6H-chromeno[4, 3-b]indolizines and their Aza-analoguesSubstituted 6,6-diphenyl-6H-chromeno[4,3-b]indolizines form ring-opened, intensely coloured (diphenyl)-indolizinylcarbenium salts with acid. UV/VIS spectra of the coloured salts are discussed on the basis of VEPPPCI calculations. The ∊pH* curves in buffered MeOH/H2O solutions and the pK* values are determined. The title compounds undergo very complex protonation equilibria.
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    Dimerisation of caffeine (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 72-75 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Displacements of 1H-NMR chemical shifs for caffeine in D2O solution as a function of concentration conform to the behaviour expected for pure dimer formation according to the equilibrium 2(caffeine)⇄(caffeine)2 with a statistical probability of at least 95%. Confidence limits reported earlier for the dimerisation constant of caffeine represent the real statistical dispersion in the experimental data and do not reflect a systematic error such as tetramer formation.
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    URL: http://dx.doi.org/10.1002/hlca.19850680109
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    The adamantane rearrangement of 1,2-trimethylenenorbornanes. Part IVPart III: [1].. Hydride-ion abstraction in 1,2-exo-trimethylenenorbornane (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 104-109 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the AlBr3-catalyzed adamantane rearrangement in CS2 of 1,2-exo-trimethylenenorbornane (1) to 2-endo,6-endo-trimethylenenorbornane (3), hydride-ion abstraction occurs at C(6) from the exo-side. The kH/kD value for competition between 1 and 5 (Dexo-C(6)) was 1.58 ± 0.05, whereas no kinetic isotope effect was operative for competition between unlabeled 1 and 4 (Dendo-C(5)) and between 1 and 6 (Dendo-C(6)).
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    Syntheses of Racemic Diaminosugar Derivatives Starting from 1,2-Dihydropyridines and from Nitrosobenzene (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 95-103 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Racemic diaminosugars were easily obtained by a regio- and stereoselective three-step synthetis. In the first step, regiospecific hetero-Diels-Alder cycloadditions between 1,2-dihydropyridines 1a and 10 and nitrosobenzene led to the bicyclic compounds 2a and 11, respectively, cis-Glycol formation starting from these latter adducts, followed by hydrogenolysis of the N—O bond and by exhaustive acetylation of the OH-groups, led to the diaminolyxose 5, the diaminomannose 14 and the diaminoallose 15. When starting from benzyl 1,2-dihydropyridine-1-carboxylate (1b) and using the same reaction sequence, the racemic piperidine derivative 8 was obtained.
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    Stoffwechselprodukte von Mikroorganismen. 231. Mitteilung230. Mitteilung s. [1].. Bafilomycin-A1-21-O-(α-L-rhamnopyranosid): Strukturaufklärung durch chemische Verknüpfung mit Bafilomycin A1 und Leucanicidin (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 83-94 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isolation of Bafilomycin-A1-21-O-(α-L-rhamnopyranoside). Structural Determination by Chemical Correlation with Bafilomycin A1 and LeucanicidinFrom cultures of an actinomycete strain, the known antifungal and insecticidal antibiotic leucanicidin (1) and a hitherto unknown antifungal antibiotic, bafilomycin-A1-21-O-(α-L-rhamnopyranoside) (2), were isolated. The latter is spectroscopically closely related to 1 and bafilomycin A1 (3) and gave degradation products identical with compounds obtained by analogous degradation of 1 and 3.
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    Steric Effects on Reaction Rates. VI. Application of a New MM2 Force-Field for Carbenium Ions to Solvolysis Rates of Secondary p-Toluenesulfonates (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 119-125 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An empirical force-field for carbenium ions has been incorporated in Allinger's MM2 programme. Structural parameters of secondary carbenium ions calculated by this method are compared with those obtained with Schleyer's BIGSTRN calculations. The strain changes occurring upon solvolysis of secondary p-toluenesulfonates are evaluated by means of this force-field and correlated with the rate constants for solvolysis. The equation for correlation of acetolysis, relative to cyclohexyl p-toluenesulfonate, of 28 kc substrates is ΔGrel+ = 0.67 ΔEst - 0.20 (r = 0.958).
    Additional Material: 4 Ill.
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    Herstellung enantiomerenreiner cis- oder trans-konfigurierter 2-(tert-Butyl)-3-methylimidazolidin-4-one aus den Aminosäuren (S)-Alanin, (S)-Phenylalanin, (R)-Phenylglycin, (S)-Methionin und (S)-Valin (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 135-143 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparation of the Enantiomerically Pure cis- and trans-Configurated 2-(tert-Butyl)-3-methylimidazolidin-4-ones from the Amino Acids (S)-Alanine, (S)-Phenylalanine, (R)-Phenylglycine, (S)-Methionine, and (S)-ValineIn contrast to α-hydroxy and α-mercapto carboxylic acids, simple α-amino acids do not form acetal-type derivatives (2, X = NH) with pivalaldehyde. For the generation of amino-acid-derived chiral, nonracemic enolates (cf. 3), and hence, for the α-alkylation of amino acids without racemization and without an external chiral auxiliary, the imidazolidinones 12-14 were prepared diastereoselectively. To this end, the methyl or ethyl esters of amino-acid hydrochlorides were first converted to N-methylamides of amino acids which in turn were condensed with pivalaldehyde to give (neopentylidenamino)amides (11). These Schiff bases could be cyclized either to trans-or to cis-imidazolidinones (12, 14 and 13, respectively), which were obtained in enantiomerically pure form after recrystallization. The enantiomeric purities were confirmed by HPLC with chiral stationary phases or by 1H-NMR spectroscopy in the presence of chiral shift reagents. The configurations (cis, trans) were assigned by NOE measurements on 300- or 360-MHz 1H-NMR spectrometers.
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    URL: http://dx.doi.org/10.1002/hlca.19850680117
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    α-Alkylation of Amino Acids without Racemization. Preparation of Either (S)- or (R)-α-Methyldopa from (S)-Alanine (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 144-154 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantiomerically pure cis- and trans-5-alkyl-1-benzoyl-2-(tert-butyl)-3-methylimidazolidin-4-ones (1, 2, 11, 15, 16) and trans-2-(tert-butyl)-3-methyl-5-phenylimidazolidin-4-one (20), readily available from (S)-alanine, (S)-valine, (S)-methionine, and (R)-phenylglycine are deprotonated to chiral enolates (cf. 3, 4, 12, 21). Diastereoselective alkylation of these enolates to 5,5-dialkyl- or 5-alkyl-5-arylimidazolidinones (5, 6, 9, 10, 13a-d, 17, 18, 22) and hydrolysis give α-alkyl-α-amino acids such as (R)- and (S)-α-methyldopa (7 and 8a, resp.), (S)-α-methylvaline (14), and (R)-α-methyl-methionine (19). The configuration of the products is proved by chemical correlation and by NOE 1H-NMR measurements (see 23, 24). In the overall process, a simple, enantiomerically pure α-amino acid can be α-alkylated with retention or with inversion of configuration through pivaladehyde acetal derivatives. Since no chiral auxiliary is required, the process is coined ‘self-reproduction of a center of chirality’. The method is compared with other α-alkylations of amino acids occurring without racemization. The importance of enantiomerically pure, α-branched α-amino acids as synthetic intermediates and for the preparation of biologically active compounds is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680118
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    Nucleophilic 1,2-Shifts of Alkoxycarbonyl and Carboxylate Groups in the Benzilic-Acid Type Rearrangement of α,β-Dioxobutyric EstersReductones and Tricarbonyl Compounds, Part 31. Part 30: [1]. (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 173-180 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: tert-Butyl α,β-dioxobutyrate (hydrate; 1d) undergoes, at medium or high pH, the benzilic-acid rearrangement with exclusive 1,2-shift of the COO(t-Bu) group; the same is true for the corresponding isopropyl ester 1c and ethyl ester 1b at high pH, whereas at lower pH, the overall picture of these reactions is complicated by concurrent hydrolysis of the ester, followed by a 1,2-shift of the COO- group. Consequently, the shift of these electron-attracting groups cannot be considered to be systematically disfavoured (compared, e.g., with alkyl-group shifts). Kinetic measurements of the rearrangement show for both esters (as well as for the analogous ethyl ester 1b, and also for ethyl 3-cyclopropyl-α,β-dioxopropionate (4)) a characteristic rate profile: at relatively low pH, k is proportional to [HO-], approaching saturation with increasing [HO-] (interpreted as complete transformation of the substrate into the hydrate monoanion), which is followed at higher pH by another rate increase with k proportional to [HO-] (probably due to the reaction of the hydrate dianion). The similarity of k values for 1b-d shows that in the shift of COOR steric hindrance caused by R is negligible.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19850680121
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  • 71
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    Photochemical reactions. 141st communication.140th Communication: [1]. Photochemistry of α,β-unsaturated δ,∊-epoxyketones of the ionone series (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 192-206 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On n,π*- as well as on π,π*-excitation, the 4,5-epoxy-α-ionones (E)-1, (E)-2, and (E)-3 undergo (E)/(Z)-isomerization and subsequent γ-H-abstraction leading to the corresponding 4-hydroxy-β-ionones (E/Z)-9, (E/Z)-13, and (E/Z)-17 as primary photoproducts. On photolysis of (E)-3, as an additional primary photoproduct, the β,γ-unsaturated σ,∊-epoxy ketone 18 was obtained. The other isolated compounds, namely the 2H-pyrans 10A + B and 14A + B as well as the retro γ-ionones 11 and 15A + B, represent known types of products, which are derived from the 4-hydroxy-β-ionones (E/Z)-9 and (E/Z)-13, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680124
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  • 72
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    The Structures of Some Products from the Photodegradation of the Pluramycin Antibiotics Hedamycin and Kidamycin (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 391-402 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photolability of the antitumor antibiotic hedamycin (1) was investigated by irradiation in different solvents in the presence or in the absence of oxygen. The products formed were separated chromatographically and their structures determined by NMR spectroscopy. Photolysis of 1 in the presence of oxygen gave only one isolable product, photohedamycin A (3), where ring E of hedamycin had been transformed into an enol ether. The reaction in the absence of oxygen yielded the photohedamycins B, C, and D (5, 6, and 7, respectively). In these compounds, one of the epoxides of hedamycin had been opened reductively, and in photohedamycin D (7) the substituent at C(8) - originally ring E of hedamycin - was now acyclic. In addition to these compounds, the photolyses yielded a large number of unstable minor products, which could not be isolated.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19850680213
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    Synthesis of 1,2-Dihydropyridines, 2,3-Dihydro-4(1H)-pyridinone, and 1,2,3,4-Tetrahydropyridines via N-Acyl N,O-Hemiacetal FormationPresented at the Swiss Chemical Society meeting in Bern, October 19th, 1982. (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 403-414 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New procedures are described for the synthesis of α,β-ethylenic and acetylenic aldehydes from 2-butene- and 2-butyne-1,4-diol, respectively (see Scheme 1). These are applied to the preparation of a particular δ-acetylamino-α,β-ethylenic aldehyde ((E)-5) as well as of its acetylenic analogue 15. On heating in the presence of a silyl enol ether, the former undergoes a complete dehydrative cyclization affording the N-acetyl-1,2-dihydropyridine 19. The addition of HCl to aldehyde (E)-5 results in the production of the 4-chloro-1,2,3,4-tetrahydropyridine 22 which is hydrolyzed to the corresponding alcohol 23 on silica gel. Similarly, the addition of HCl or HBr to the δ-acetyl-amino-α,β-acetylenic aldehyde 15 leads to the previously unknown 4-halo-1,2-dihydropyridines 26; these are easily hydrolyzed to the 2,3-dihydro-4(1H)-pyridinone 27. The ring-forming process involves a N-acyl N,O-hemiacetal as intermediate which is eventually dehydrated.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19850680214
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  • 74
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    Rh-Catalyzed Oxidation of Anthracenes with tert-Butyl Hydroperoxide. Kinetic Aspects (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 450-455 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polar effects of substituents on reactivity in oxidation of 2-substituted anthracenes with tert-butyl hydroperoxide (TBHP)/Rh(PPh3)3Cl have been investigated and compared with those obtained with TBHP/VO(acac)2 and chromic acid. The anthracene reactivities obtained from competition experiments are correlated with Hammett's σp-constants. The P-values are -2.60 for chromic acid and 0.72 for TBHP/VO(acac)2. A poor correlation with p = -0.17 (r = 0.756) was obtained for TBHP/Rh (PPh3)3Cl. It is concluded that the Rh-catalyzed reaction does not consist in electrophilic oxygen transfer to the anthracene.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19850680218
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  • 75
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    Synthese von 3,3-Dimethylperhydro-1,4-diazepin-2,5,7-trionen aus 3-Dimethylamino-2,2-dimethyl-2H-azirin und Malonsäuremonoamiden (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 465-474 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 3,3-Dimethylperhydro-1,4-diazepin-2,5,7-triones from 3-Dimethylamino-2,2-dimethyl-2H-azirine and Malonic Acid MonoamidesReaction of the aminoazirine 1 and malonic acid monoamides 5 in CH3CN yielded triamides of type 6 (Scheme 2), which were transformed to the corresponding phenylthioates 9 by treatment of a solution of 6 and thiophenol in CH3CN with HCl (Scheme 4). Cyclization of 9 to give the 1,4-diazepin-2,5,7-trione of type 10 was achieved with NaH in toluene at about 90°. It has been shown that 2-oxazolin-5-ones are intermediates in the selective cleavage of the therminal amide function of 6 (Scheme 3).
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    URL: http://dx.doi.org/10.1002/hlca.19850680220
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  • 76
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    Nature et stabilité des complexes métalliques de cryptands dinucléants en solution. I. Polyazapolyoxa macrotricycle cylindrique et monocycle constitutif (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 456-464 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nature and Stability of Some Metallic Complexes of Dinucleating Cryptands in Solution. I. A Polyazapolyoxa Cylindrical Macrotricycle and its Monocyclic SubunitpH-metry and UV spectrophotometry were used to study the complexing properties of the cylindrical macrotricycle, 1,7,13,19-tetraaza-4,16-dioxa-10,22,27,32-tetraoxatricyclo[17.5.5.5]tetratriacontane (1) and of its constitutive monocyclic subunit, 1,7-diaza-4,10-dioxacyclododecane (2) with some transition and heavy metal cations (Cu2+, Co2+, Ni2+, Zn2+, Cd2+, Pb2+, Ag+), in aqueous medium 0.1M Et4NClO4, at 25°. The protonation constants of the ligands as well as the nature and the stabilities of the complexes formed in the pH-regions studied were determined. The tricycle 1 only formed dinuclear M2L complexes with Cu2+, Zn2+, and Ag+, accompanied in the latter case by a protonated mononuclear MLH species, and with Cu2+ and Zn2+ at high pH-values by dinuclear hydroxo complexes. Only mononuclear complexes were evidenced with the other cations, ML being accompanied either by protonated or hydroxy mononuclear species. The mononuclear complexes of 1, when they existed, were more stable than the corresponding complexes of 2, except for cobalt which formed complexes of comparable stability with both ligands. In the other cases (Cd2+, Pb2+, Ag+), the stability differences between the complexes of 1 and 2 increased with the size of the cation.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19850680219
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  • 77
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    Planarisierung von tetrakoordiniertem Kohlenstoffatom. Synthese des überbrückten all-cis-[5.5.5.5]Fenestrans 13-Oxapentacyclo[5.5.2.11.7.04,15.010,15] pentadecan-14-onVorläufige Mitteilung: [1]. (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 493-507 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Planarisation of Tetracoordinate Carbon Atom, Synthesis of the Brigded all-cis-[5.5.5.5]Fenestrane 13-Oxapentacyclo[5.5.2.11,7.04,15.010,15]pentadecan-14-oneThe synthesis of the ketolactone 23 from (Z,Z)-1,5-cyclooctadiene is reported. Transannular carben insertion, achieved via photolysis of the deprotonated (2,4,6-trisisopropylphenylsulfonyl)hydrazone of 23 gives the bridged all-cis-[5.5.5.5]fenestrane 3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680223
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    Water Exchange on Hexaaquavanadium(III): a Variable-Temperature and Variable-Pressure 17O-NMR Study at 1.4 and 4.7 TeslaPart 24 of the series ‘High-Pressure NMR Kinetics’. Part 23: [1].These results are part of the Ph. D. thesis of A. H., University of Lausanne, 1984. (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 508-521 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Water exchange on hexaaquavanadium (III) has been studied as a function of temperature (255 to 413 K) and pressure (up to 250 MPa, at several temperatures) by 17O-NMR spectroscopy at 8.13 and 27.11 MHz. The samples contained V3+ (0.30-1.53 m), H+ (0.19-2.25 m) and 17O-enriched (10-20%) H2O. The trifluoromethanesulfonate was used as counter-ion, and, contrary to the previously used chloride or bromide, CF3SO3- is shown to be non-coordinating. The following exchange parameters were obtained: kex298 = (5.0 ± 0.3) · 102 s-1, ΔH* = (49.4 ± 0.8) kJ mol-1, ΔS* = -(28 ± 2) JK-1 mol-1, ΔV* = -(8.9 ± 0.4) cm3 mol-1 and Δβ* = -(1.1 ± 0.3) · 10-2 cm3 mol-1 MPa-1. They are in accord with an associative interchange mechanism, Ia. These results for H2O exchange are discussed together with the available data for complex formation reactions on hexaaquavanadium(III). A semi-quantitative analysis of the bound H2O linewidth led to an estimation of the proportions of the different contributions to the relaxation mechanism in the coordinated site: the dipole-dipole interaction hardly contributes to the relaxation (less than 7%); the quadrupolar relaxation, and the scalar coupling mechanism are nearly equally efficient at low temperature (∼ 273 K), but the latter becomes more important at higher temperature (75-85% contribution at 360 K).
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19850680224
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  • 79
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    Spontane Öffnung des Pyrimidinringes in Pyrrolo[2,3-d]pyrimidinen nach intramolekularer Acylierung (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 534-544 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spontaneous Opening of the Pyrimidine Ring of Pyrrolo[2,3-d]pyrimidines after Intramolecular AcylationPhase-transfer alkylation of 4-methoxy-2-methylthio-7H-pyrrolo[2,3-d]pyrimidine (2) with ethyl 3-bromopropionate leads regioselectively to the ester 3a. After displacement of its methylthio group and saponification of the ester function, the acid 3e is obtained which can be transferred to the functionalized deazahypoxanthine 3f by either treatment with dry HBr/glacial AcOH or by nucleophilic displacement of the 4-methoxide. Reaction of 3f with a H2O-soluble carbodiimide results in an intramolecular acylation at N(1) by the activated ester; the intermediate 4 undergoes spontaneous hydroxylation and subsequent opening of the pyrimidine ring under formation of the pyrrolo[1,2-a]pyrimidine derivative 6. Its structure was proved by X-ray analysis. Subsequent deformylation of 6 in alkaline medium leads to the compound 7 in almost quantitative yield.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19850680226
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    Molluscicidal Saponins from Talinum tenuissimum DINTERPart 3 of the series ‘Phytochemistry of African Medicinal Plants’. For part 2, see [1].Dedicated to Prof. K. Nakanishi on the occasion of his 60th birthday (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 555-558 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new saponins, β-D-glucopyranosyl 3-O[O-βD-xylopyranosyl-(1→3)-O-(β-D-glucopyranosyluronic acid)]oleanolate (1) and 3-O-[O-β-D-xylopyranosyl-(1→3)-O-(β-D-glucopyranosyluronic acid)]oleanolic acid (2), have been isolated from the tubers of Talinum tenuissimum. The structures have been established mainly by 13C-NMR and FAB-MS. The monodesmosidic saponin 2 exhibits very strong molluscicidal activity against the schistosomiasis-transmitting snail Biomphalaria glabrata.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19850680303
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    Variable-Temperature and Variable-Pressure 17O-NMR Study of Water Exchange of Hexaaquaaluminium(III)Part 25 of the series ‘High-Pressure NMR Kinetics’. Part 24: [1].These results are part of the Ph. D. thesis of D. H.-C., University of Lausanne, 1984. (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 545-554 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The transverse relaxation rate of H2O in Al(H2O)63+ has been measured as a function of temperature (255 to 417 K) and pressure (up to 220 MPa) using the 17O-NMR line-broadening technique, in the presence of Mn(II) as a relaxation agent. At high temperatures the relaxation rate is governed by chemical exchange with bulk H2O, whereas at low temperatures quadrupolar relaxation is prevailing. Low-temperature fast-injection 17O-NMR was used to extend the accessible kinetic domain. The samples studied contained Al3+ (0.5 m), Mn2+ (0.2-0.5 m), H+ (0.2-3.1 m) and 17O-enriched (20-40%) H2O. Non-coordinating perchlorate was used as counter ion. The following H2O exchange parameters were obtained: kex298 = (1.29 ± 0.04) s-1, ΔH* = (84.7 ± 0.3) kJ mol-1, ΔS* = +(41.6 ± 0.9) J K-1 mol-1, and ΔVex* = +(5.7 ± 0.2) cm3 mol-1, indicating a dissociative interchange, Id, mechanism. These results of H2O exchange on Al(H2O)63+ are discussed together with the available complex-formation rate data and permit also the assignment of Id mechanisms to these latter reactions.
    Additional Material: 4 Ill.
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    Esters of 1-O-Demethylthiocolchicines: Formation of Isomers in Chloroform Solution (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 571-580 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-O-Acetyl-1-O-demethylcolchicine, and acylated 1-O,2-O-didemethylthiocolchicines, in contrast to 2-O-acetyl-, 2-O,3-O-diacetyl- and 3-O-acetyl analogs, showed after standing in CHCl3 solution significant changes in optical rotation, a duplication of 1H-NMR signals, and the formation of new isomers on TLC. Solid-state X-ray diffraction of O-acetylated colchinoids and thio analogs, showed out of planar arrangements of the aromatic substituents, but the analysis could not help to explain the structures of the newly formed isomers in CHCl3 solution.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19850680306
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  • 83
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    Facile Synthesis of 2′-Deoxyribofuranosides of Allopurinol and 4-Amino-1H-pyrazolo[3,4-d]pyrimidine via Phase-Transfer Glycosylation (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 563-570 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phase-transfer glycosylation of 4-methoxy-1H-pyrazolo[3,4-d]pyrimidine with the 2-deoxyribofuranosyl chloride 9 formed the N(1)-β-nucleoside 10a as main product (39%). As by-products the α-D-anomer 11a (7%) and the N(2)-isomer 12a (18%) were isolated. Assignment of these isomers was made on the basis of their 1H- and 13C-NMR spectra. Removal of the sugar-protecting groups yielded the 4-methoxy-nucleosides 10b, 11b, and 12b, respectively. Nucleophilic displacement of the 4-MeO-group gave the 2-deoxyribofuranosides 1-4 of allopurinol and 4-amino-1H-pyrazolo[3,4-d]pyrimidine.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19850680305
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    Liquid Crystals with Large Negative Dielectric Anisotropy. Part V (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 606-609 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Liquid crystals with negative Δ∊ can be obtained by incorporating a cyano group in the terminal alkyl substituent or in an ethylene bridge between the cyclic units of the rigid core. The clearing points of such compounds are higher than those of the corresponding derivatives where the cyano group is laterally attached to a phenyl moiety. In compounds where both cyclic units of the rigid core are cyclohexyl, this type of substitution leads to an optimal contribution to ∊⊥ in contrast to the cyanophenyl derivatives.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19850680311
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    Propellanes. Part LXXVIII. Preparation of Several Triaza[3.3.3]propellanes and an Oxadiaza[3.3.3]propellanePart LXXVII: [1]. (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 610-613 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3,7,10-Tribenzyl-3,7,10-triaza[3.3.3]propellane (4a), 3,7-dibenzyl-10-phenyl-3,7,10-triaza[3.3.3]propellane (4c), 3,7-dibenzyl-10-(p-tolyl)-3,7,10-triaza[3.3.3]propellane (4b), and 3-oxa-7,10-diaza[3.3.3]propellane (6) have been prepared.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680312
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    Synthesis of the Glycopeptide Partial Sequence A80-A84 of Human Fibroblast Interferon (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 618-622 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The glycopentapeptide H-(GlcNAcβ1-)Asn-Glu-Thr-Ile-Val-OH (10) representing the partial sequence A80-A84 of human fibroblast interferon was synthesized using the newly developed allyl-ester protection of carboxy functions. The allyl esters, which are stable to acids and to bases, can be cleaved under very mild, neutral conditions using tris(triphenylphosphine)rhodium(I) chloride or tetrakis(triphenylphosphine)palladium(0) as a catalyst. This synthetic method opens up a preparative route to glycopeptide model structures of glycoproteins of high biological interest.
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    URL: http://dx.doi.org/10.1002/hlca.19850680314
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    Polar effects. Part 12. Inductivity and carbon participation in the solvolysis of 4-substituted 2-adamantyl arenesulfonates (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 651-660 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate constants (log k) for the solvolysis of 4e-substituted 2e- and 2a-adamantyl p-nitrobenzenesulfonates 14 and 15, respectively, in 80% EtOH correlate linearly with the respective inductive substituent constants σIq. Therefore, relative rates are controlled by the I effect of the substituents at C(4). The derived reaction constants, or inductivities, ρI of -0.80 and -0.64 for the series 14 and 15, respectively, are far smaller than those previously determined for 6-substituted 2-norbornyl and 2-bicyclo[2.2.2]octyl sulfonates, in which the partial structure containing the substituent and the leaving group is the same. The ratio of the retained and inverted adamantanols obtained upon hydrolysis of the series 14 falls from 2.85 for R = CH3 to ca. 1 for R = CN, i.e. as the substituent at C(4) becomes more electron-attracting. In the 2a-series 15 this ratio is uniformly higher. These findings confirm that the 2-adamantyl cation is weakly bridged and that through-space induction in carbocations involves graded bridging of the cationic center by neighboring C-atoms.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19850680317
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  • 88
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    Peptide conformations. Part 31Part 30: [1a].. The conformation of cyclosporin a in the crystal and in solution (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 682-704 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The all-light-atom X-ray crystal-structure analysis of cyclosporin A (1), a cyclic undecapeptide containing seven N-methylated amino acids, reveals a conformation very similar to that of the previously analysed iodo derivative which is characterised by a twisted β-pleated sheet involving the residues Me-Val-11, MeBmt-1, Abu-2, Sar-3, MeLeu-4, Val-5, MeLeu-6, and Ala-7. The β-bend at Sar-MeLeu-4 is of type II′, and the loop of the residual amino acids involves a cis-peptide bond between MeLeu-9 and MeLeu-10. The NH proton of D-Ala-8 closes a yi-bend with a H-bond to the MeLeu-6 CO group. The crystal was grown from acetone. A closely similar backbone conformation in apolar solvents such as CDCl3 or C6D6 has been derived from the interpretation of the NMR spectral parameters (homo- and heteronuclear NOE effects, coupling constants, chemical-shift values of the C-, H-, and N-atoms). A minor variation in the backbone conformation between crystal and solution is observed in the region of D-Ala-8, where in solution a 3-center H-bond is established between the NH of D-Ala-8 und the carbonyl O-atoms of both MeLeu-6 (yi-turn) and D-Ala-8 (C5-bend). A recently proposed technique to identify intramolecular H-bond via heteronuclear NOE from NH proton to carbonyl C-atoms is critically analysed. The main difference between crystal and solution conformations lies in the orientation of the side chains of the unusual amino acid MeBmt (χ1 = +60° in solution, -168° in the crystal) and of MeLeu-10 (X1 = -60° in solution, +60° in the crystal). The differences in crystal and solution are caused by the break of the intermolecular H-bond of the OH group of MeBmt on dissolution of the crystal. The bifurcated H-bond of D-Ala-8 twists the backbone in this region. Molecular modeling demonstrates that this is the origin of the change in the side chain conformation of MeLeu-10. The intramolecular flexibility in the crystal indicated by the thermal parameters obtained from the X-ray refinement, and in solution by an analysis of spin-lattice relaxation times in the NMR experiments, indicate a fairly rigid backbone and fixed conformations for all the side chains except for that of Abu-2 and the distal atoms of MeBmt.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680319
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  • 89
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    The Crystal Structure of trans-2,2′-AzoquinoxalineDedicated to Prof. Dr. Silvio Fallab on the occasion of his 60th birthday (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 581-583 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of the title compound obtained from 2(1H)-quinoxalinone oxime by the template effect of Co(II) and Ni(II) ion has been determined by three dimensional X-ray analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680307
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  • 90
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    Photochemische Synthesen potentiell hypoglykämisch wirkender 3-Oxazoline (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 584-591 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemical Syntheses of 3-Oxazolines which Possibly Exhibit Hypoglycemic ActivityReactions of photochemically generated benzonitrile methylides 2 with carbonyl compounds 3 yielded 3-oxazolines of the types 5 and 6 (Scheme 1). Photooxidation of 5-[p-(dimethylamino)phenyl]-2,2-dimethyl-4-phenyl-3-oxazoline (5a) gave 4′-(2,2-dimethyl-4-phenyl-3-oxazolin-5-yl)-N-methylformanilide (6r) which could be transformed to 2,2-dimethyl-5-[p-(methylamino)phenyl]-4-phenyl-3-oxazoline (6s) by photodecarbonylation. Thirty 3-oxazolines of types 5 and 6 have been synthesized and tested by oral and/or intraperitoneal administration to starved rats and obese-hyperglycemic mice.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680308
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  • 91
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    Photochemische und chemische Synthesen biologisch aktiver 3-Oxazoline (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 600-605 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemical and Chemical Syntheses of Biologically Active 3-OxazolinesUsing the photoreaction of 2H-azirines with carbonyl compounds, the 2,2-dimethyl-3-oxazolines 5a, 5b, and 6a have been obtained which bear a mono- or dichlorophenyl substituent at C(4) of the five-membered heterocycle and pyridyl at C(5). These compounds exhibit interesting activities against phytopathogenic fungi. Because 6a had been selected for field testing, its photochemical preparation was supplemented by a chemical synthesis. However, the overall performance of 6a in the field was inferior to some of the recently introduced agricultural fungicides of the ergosterol biosynthesis inhibitor type. Although 16 additional 3-oxazolines with varied substituents have been prepared, the fungicidal activity found with 6a could not be improved.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19850680310
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  • 92
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    Synthese und Reaktionen des 5-[p-(Dimethylamino)phenyl]-2,2-dimethyl-4-phenyl-3-oxazolins (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 592-599 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Reactions of 5-[p-(Dimethylamino)phenyl]-2,2-dimethyl-4-phenyl-3-oxazolineThe title compound 8 has been synthesized in a one-pot reaction of 4′-(dimethylamino)benzoin (4) with 2-propanone and NH3. The preparation of the intermediate 4 from 3 is the first example of an acid-catalyzed transformation of the stable benzoin 3 into the corresponding less stable benzoin 4. Structures and yields of various by-products occurring under different reaction conditions during the synthesis of 8 from 4 are given. The O-atom of the 3-oxazoline ring in 8 could be replaced by S from P2S5 yielding the 3-thiazoline 14. Separation of the enantiomers of the racemate 8 could only be performed by transforming them into the trimethylanilinium salts 8b and 8c of (-)- and (+)-10-camphorsulfonic acid, respectively. Solid NaOAc in boiling toluene caused the precipitation of the 10-camphorsulfonic acids from the quaternary ammonium salts as sodium salts and the removing of the third methyl group from the quaternary ammonium salts as AcOMe to give the enantiomers (-)-(5S)-8 and (+)-(5R)-8. Their absolute configurations are deduced from an X-ray analysis of 8b.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680309
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  • 93
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    Propellanes. Part LXXX. Baeyer-Villiger Oxidation of [4.3.3]Propellane-8,11-dionePart LXXIX: [1]. (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 614-617 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidation of the title compound with m-chloroperbenzoic acid affords a keto-lactone, two bis-lactones and a bis-spirolactone, in varying amounts depending upon the reaction conditions. The structures were established by means of X-ray diffraction, 1H- and 13C-NMR spectroscopy.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19850680313
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  • 94
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    Synthese substituierter Cyclononatetraene42. Mitt. über Fulvene, Fulvalene. 41. Mitt.: [1]. (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 623-634 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Substituted CyclononatetraenesIn the course of an exploration of possible synthetic pathways to nonafulvenes, a series of 1-substituted cyclononatetraenes (CNT) 4b-1 have been prepared in yields of about 60%. Their structures follow from spectroscopic data as well as from the quantitative valence isomerisation to 1-endo-substituted cis-3a, 7a-dihydroindenes 8. Both all-cis-CNT- 1 and cis,cis,cis,trans-CNT- 2 have been used as nucleophiles. Whereas 2 is normally more nucleophilic than 1, the yield of cyclononatetraenes 4 prepared with 2 may be reduced due to by-products such as 9 and 10.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680315
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  • 95
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    Peptide conformations. Part 30Part 29: [1]. Assignment of the 1H-, 13C-, and 15N-NMR spectra of cyclosporin A in CDCl3 and C6D6 by a combination of homo- and heteronuclear two-dimensional techniques (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 661-681 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H-, 13C-, and 15N-NMR spectra of the immunosuppressive cyclic undecapeptide cyclosporin A (1) have been analyzed at 300 MHz in CDCl3, C6D6, and mixtures of these solvents. A combination of different homo- and heteronuclear two-dimensional NMR techniques enable complete assignment of all H-, C- and 4 N-signals. Recognition of the proton spin systems has been achieved via 1H,1H-COSY and double-quantum-1H-NMR spectroscopy. NOESY spectra yield some sequence assignments, but two techniques using coupling across amide bonds have been applied to get independent assignments of all amino acids in the sequence: (i) An 1H,1H-COSY spectrum optimized for small coupling constants enables the detection of long-range couplings from N-methyl groups to both α-protons attached to that amide bond. (ii) An 1H, 13C-COSY spectrum optimized for C,H-long-range couplings (J = 5 to 10 Hz) to the eleven CO groups again yields coupling to both α-protons attached to that amide bond. Additionally these two experiments yield the assignment of N-methyl protons and carbonyl C-atoms. Normal and relayed 1H,13C-COSY in both solvents have been applied to assign all C-atoms via their directly attached and remote protons. An 1H,13C-COLOC spectrum at 500 MHz in CDCl3, which uses H,C-long-range couplings confirms the assignment of all proton spin systems as well as the C-signals of each individual amino acid. Ambiguities in the assignment of the C(δ)'s of MeLeu have thus been removed. An 1H,15N-COSY spectrum enables the assignment of the 4 NH N-atoms.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19850680318
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  • 96
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    Photochemical reactions. 143rd communication142nd Communication: [1].. Photochemistry of 5,6-epoxy-1,3-dienes in the ionone series. Influence of a hydroxy group in the 7-position (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 635-650 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and photolyses of the epoxydiene (E)-5 are described. On triplet excitation (λ 〉 280 nm, acetone), (E)-5 undergoes initial cleavage of the C(5)—O bond leading to the intermediate c. Presumably an H-shift (c → e) followed by the fragmentation of the 1,4-diradical e leads (via the enol 37) to the diketones (E)-6 and (Z)-12. Alternatively cleavage of the C(6)—C(7) bond of c furnishes the diradical intermediate d which reacts by recombination leading to (E)-13A + B, 16, and 17A + B, or by an H-shift to the enol intermediate 38. The latter undergoes an aldol-type reaction to (E/Z)-14A + B and (E/Z)-15A + B, as well as a photochemical [2 + 2]-cycloaddition to 18. On singlet excitation (λ = 254 nm, MeCN), (E)-5 undergoes photocleavage to the carbene intermediates f and g. The vinyl carbene f reacts with the adjacent double bond furnishing the cyclopropene 22 as the main product. From the carbene intermediate g, compounds 23, 24, and 25 arise by carbene insertion into the neighboring C—C or C—H bond. Furthermore, the diastereomer of the starting material, the epoxydiene (E)-20, is formed via the ylide intermediate h.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680316
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  • 97
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    The Structure of Pyroergotamine (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 724-733 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular structure of pyroergotamine has been determined by single-crystal X-ray diffraction analysis to be the pyruvoyldiketopiperazine 1. The diketopiperazine ring exists in a folded or boat conformation, with a dihedral angle of 40° between the two almost planar peptide units. The R-group of the phenylalanine residue occupies a quasi-axial position of the diketopiperazine ring, while that of the proline residue is in a quasi-equatorial position. Puzzling spectroscopic and chemical properties of the compound can be rationalised in terms of crowding within the molecule.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680322
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  • 98
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    The Electronic Structure of Dopamine. An ab initio Electrostatic Potential Study of the Catechol Moiety (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 715-723 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electronic properties of dopamine were studied by the ab initio STO-3G MO method. The molecular electrostatic potential (MEP) around the aromatic ring and the catechol group remains practically the same in 3,4-dihydroxytoluene (a model compound) and in neutral dopamine examined in its two extended conformations, namely that found in the crystal (side-chain and aromatic ring almost perpendicular) and the one corresponding to 2-amino-6,7-dihydroxytetralin (6,7-ADTN) (side-chain and aromatic ring almost coplanar). In protonated dopamine and in dopamine hydrochloride, the electrostatic potential of the catechol moiety is overshadowed by the positive charge, but the main features remain discernible. The catechol moiety was examined in its two coplanar conformations containing a ‘flip-flop H-bond’. The electrostatic potential around the catechol moiety is quite complex, with alternating positive and negative maxima. At increasing distances above and away from the catechol moiety, only two peripheral maxima, one negative and one positive, remain perceptible. The ‘flip-flop’ mechanism results in an approximate interchange of these two potential maxima, a fact which tends to level out the structural differences between the α- and β-rotamer of dopamine. Based on these results and on the structure of rigid agonists, some pharmacophoric features of dopamine agonists are proposed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680321
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  • 99
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    Synthese und Hydrolyse von 4-substituierten p-Nitrobenzolsulfonsäure (2-adamantyl)estern (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 760-769 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Hydrolysis of 4-Substituted 2-Adamantyl p-NitrobenzenesulfonatesSeveral 4e -substituted 2e- and 2a-adamantyl p-nitrobenzensulfonates have been prepared by new routes. Their hydrolysis products are described.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19850680326
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  • 100
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    Transamidation reactions. Part 11Part 10: [1]. In earlier papers of this series the lactam nomenclature was used. Beginning with this paper the ‘replacement nomenclature’ is preferred. Both systems are in agreement with IUPAC nomenclature of organic chemistry.. N-substituted 3-aminopropanenitriles and 2-aminoacetonitriles as Schiff-base equivalents (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 750-759 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In presence of a strong base, the 13-membered cyclic compound 3 yielded, by loss of acetonitrile or its equivalent, the bicyclic product 5 instead of the 17-membered compound 4 as expected (Scheme 2). Investigation of model compounds (Scheme 4) and of model reactions (Schemes 5 and 6) led to the conclusion that the reaction proceeds via an intermediate formaldehyde imine; a Schiff base, e.g. 3b (Scheme 5), which reacts intra- and intermolecularly with a nucleophile to form a Mannich-type product. It seems to be a general principle that N-substituted 3-aminopropanenitrile and 2-aminoacetonitrile derivatives behave in the presence of a strong base as Schiff -base equivalents (Schemes 5 and 6).
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    URL: http://dx.doi.org/10.1002/hlca.19850680325
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