摘要:

AbstractThe present investigation was aimed at studying the interrelation between hemodynamic, metabolic and oxygen tension in the brain of the gerbil exposed to various physiological and pathological conditions in the awake and anesthetized states. The hemodynamic and metabolic activities were evaluated by the DC fluorometer/reflectometer and were correlated to the pO2values obtained by a surface electrode.When the awake brain was exposed to spreading depression (SD), a typical oxidation cycle of the NADH was recorded concomitant with a decrease cycle of the pO2. Under anesthetic effect the same dip in pO2response was found but the NADH showed a “reduction cycle.” The pO2values were in a very good correlation with the changes in the reflectance trace, namely, the pO2was a good indicator of the vasoconstriction‐vasodilatation responses under various conditions. The same model was used under hypoxic and ischemic conditions, as well as under the effects of anesth

ISSN:0360-4012    

DOI:10.1002/jnr.490050302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractA new approach is described to study the mechanism of protein leakage through the endothelial cells in acute hypertension and after intracarotid infusion of hyperosmolar solutions. The luminal surface of the cerebrovascular endothelial cells was labeled with choleragenoid‐peroxidase before the blood‐brain barrier (BBB) dysfunction was induced. Numerous pinocytotic vesicles and some trans‐endothelial channels were formed and showed labeling of parts of their membranes.Our results indicate that the mechanism behind the protein leakage induced by hypertension and by hyperosmolar solutions is the same – ie, transendothelial pino

ISSN:0360-4012    

DOI:10.1002/jnr.490050303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractWhen vasopressin is administred into the lateral ventricles of rats it produces severe convulsive activity characterized by a rapid barrel rotation. Electrical recordings from the dorsal hippocampus indicate marked elevations in the amplitude and frequency at doses of 5 μl of 2 × 10−5M vasopressin. No significant behavioral effects were noted with oxytocin, somatostatin, β‐melanophore‐stimulating hormone, adrenocorticotropin, or leu‐enkephalin. Pretreatment of the rats with intraventricularly administered oxytocin, β‐MSH, or systemically administered Dilantin prevented the vasopressin‐induced seizures. With the use of chemical and enzymic modification procedures, the essential fragment and amino acids of vasopressin needed for the activity were determined. It was concluded that although the peptide could be acting by vasoconstricting blood arterioles and capillaries in the brain, it may also be exerting a direct excitatory ac

ISSN:0360-4012    

DOI:10.1002/jnr.490050304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe sodium dependence of the high‐affinity transport of glutamic acid in rat brain synaptosomes has been studied in animals maintained on a diet deficient in essential fatty acids (EFAD), and the results compared to similar studies with animals on a normal diet. Although the data give best fit to the same kinetic model as for control data, there are differences in the constants that describe the model. Except at low sodium concentrations, uptake is lower for the EFAD group.As a consequence of the differences in constants for the two groups, there are quantitative differences in the transport mechanism. The rate equation for the best fit model has been utilized to define certain functions in terms of dissociation and translocation constants, glutamate, sodium, and total carrier concentrations. These functions were calculated and utilized to compare the transport mechanism for the two groups. Although there are differences between these functions for control and EFAD animals, these differences are small and therefore of doubtful physiological significanc

ISSN:0360-4012    

DOI:10.1002/jnr.490050305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractBrain cathepsin D, purified by affinity chromatography on Sepharose pepstatin columns, was incubated with synthetic peptides corresponding to the susceptible regions of the myelin basic protein encompassing the two Phe‐Phe bonds. One peptide, Leu‐Gly‐Arg‐Phe‐Phe‐Gly‐Gly, was cleaved by cathepsin D at the Phe‐Phe bond while another, Val‐His‐Phe‐Phe‐Lys‐Asn‐Gly, was resistant to cleavage. To determine if this was a result of His flanking the Phe‐Phe bond, or chain length on the N‐terminal side, two decapeptides were synthesized differing only in the presence or absence of His adjacent to Phe. The results show that both of the decapeptides were cleaved by cathepsin D at the Phe‐Phe linkages. In addition, prolonged incubation led to release of N‐terminal Lys, indicating an additional cleavage at the Phe‐Lys bond. In contrast to the limited cleavage by cathepsin D, pepsin split all four peptides. These results support earlier work on the limited proteolysis of basic protein at the Phe‐Phe bond and suggest additional sites upon prolonged exposure. Such peptides may have utility as alternative substrates for basic protein or as models for subsequent synthes

ISSN:0360-4012    

DOI:10.1002/jnr.490050306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractElectron spin resonance (ESR) was used in a search for a possible generalized membrane defect underlying myelin instability in multiple sclerosis (MS). In contrast to most ESR studies of biological membranes, a small, nonelectrolyte spin label, TEMPO, was chosen; its partition coefficient was determined in extracted erythrocyte lipids from MS patients and normal controls. No differences were observed. The advantages and limitations of TEMPO in comparison with lipid spin labels as probes for the study of biological membranes are discussed.

ISSN:0360-4012    

DOI:10.1002/jnr.490050307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractMutli‐unit activity was recorded from the diencephalon of unanesthetized, immobilized female rats. Less than 50% of the recording sites in the hypothalamus showed changes in the level of multi‐unit activity to changes in the level of glucose utilization induced by injection of 2‐deoxy‐D‐glucose (2‐DG). It was also not possible to specificy an area within the hypothalamus in which there was a concentration of recording sites which consistently responded to 2‐DG. Relatively large amplitude, long duration changes in multi‐unit activity levels were also observed in the optic tract, suggesting that 2‐DG induced a widespread cellular metabolic response to glucoprivation which may not have been related to the regu

ISSN:0360-4012    

DOI:10.1002/jnr.490050308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractD‐[3‐3H]‐3‐deoxy‐3‐fluoroglucose was synthesized chemically and shown to be transported into rat brain synaptosomes by a saturable process with a Km6.2 × 10−4M and a Vmax2.8 nmole · mg protein−1. After an initial, rapid period of transport, further uptake of the fluorosugar is restricted by the rate of its phosphorylation. Both D‐glucose and cytochalasin B are competitive inhibitors of 3‐deoxy‐3‐fluoro‐D‐glucose transport with Kivalues of 93 μm and 6.0 × 10−7M, respectively. Phloretin, N‐ethylmaleimide and p‐chloromercuribenzoate also inhibit the fluorosugar uptake, whereas ouabain and changes in K+, Na+, Mg2+and Ca2+ions have only a small effect. The recorded 3‐deoxy‐3‐fluoro‐D‐glucose influx is slightly reduced by potassium cyanide, antimycin A, 2,4‐dinitrophenol, and rotenone. The uptake reduction caused by these four reagents is relieved by the addition of exogenous ATP. The possible influence of hexok

ISSN:0360-4012    

DOI:10.1002/jnr.490050309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractImmobility reflex (IR) durations of rabbits were remarkably consistent (weighted average range of 0.36–0.70 minutes/trial), under the special conditions when rabbits were “habituated” by approximately 25 preliminary trials and when termination of IR was operationally defined as the point at which any attempt, even abortive, at righting occurred. When the mean duration for each rabbit was normalized (into quartile duration points) and then rabbits were tested at these points to determine arousal threshold, each rabbit revealed a clear progressive decrease in the “depth” of IR as the duration of a given episode progressed.Both duration and depth were decreased when body hair was removed. The hippocampal EEG revealed persistent theta activity throughout a given trial; but the specific frequency the theta increased briefly just prior to induction of IR and decreased immediately afterwards. In Short‐duration trials, theta frequency increased progressively until the IR terminated spontaneously. In long‐duration trials frequency changes oscillated.Each of these observations in interpreted to support the theory that, during IR, reverberating neural circuits (in the brainstem reticular formation) are activated and their output inhibits spinal

ISSN:0360-4012    

DOI:10.1002/jnr.490050310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

ISSN:0360-4012    

DOI:10.1002/jnr.490050301

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY