摘要:

Abstract—The highly basic encephalitogenic protein isolated from bovine spinal cord was studied by various physicochemical methods:1The molecular weight was determined by sedimentation equilibrium, by calculation from the data on sedimentation coefficients and intrinsic viscosities, by measurement of intrinsic viscosity in the presence of concentrated guanidine hydrochloride (according to the method of Tanford, Kawaharaand Lapanie, 1967), and by exclusion chromatography on Sephadex G‐100 columns. All values obtained were in good agreement and indicated a molecular weight of approximately 18,000–20,000.2Studies of sedimentation velocities in the presence and absence of 6m‐guanidine‐HCl indicated that there was a significant difference in the values of sedimentation coefficients.3The same conditions were applied to the measurements of viscosity; the difference was small but significant. These findings and the magnitude of the intrinsic viscosity suggested that this protein was in a disordered configuration. From these data, it is concluded that the protein was apparently monodispersed, in the presence or absence of the denaturing agent. This protein behaved like a polyelectrolyte in neutral aqueous solution.4The measurements of optical rotatory dispersion also confirmed that this protein existed in a disordered conf

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03360.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The synthesis of asparagine in rat brain was studied bothin vitroandin vivo.A conversionin vitroof about 2 per cent of the addedl‐[14C]aspartic acid into asparagine was found after a 2 h incubation with the 100,000 g supernatant fraction from brain. This corresponded to a formation of 4·8 nmol of asparagine/mg of protein/h. The reaction required ATP and glutamine, and was linear with time during the 2 h incubation. When the crude mitochondrial fraction was added to the incubation mixture the reaction was inhibited, probably because of the presence of ATPase activity in the mitochondrial preparation. Inhibition by the reaction product seemed unlikely since removal of endogenous asparagine did not stimulate the reaction; only when asparagine was added at levels of 0·5 or 1·0 mmwas significant inhibition found. Ammonium chloride was less effective than glutamine as an amide donor. Endogenous asparaginase (EC 3.5.1.1.) activity was low in thein vitropreparation and did not significantly affect the conversion. Synthesis of asparagine from aspartic acid did not occur in slices of brain nor was there a significant conversion of aspartic acid or glucose to asparagine after their intracerebral administrationi

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03361.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Stimulant‐induced changes in soluble preparations from rabbit olfactory epithelium were monitored by ultraviolet difference spectroscopy. A time‐dependent decrease of absorbance, maximum at 267 nm, was generated when specific stimulants were mixed with the olfactory preparations. Only seven of the 37 organic chemicals tested generated the absorbance change at 267 nm. The olfactory preparations exhibited a high degree of selectivity and sensitivity; measurable absorbance changes were observed when the active stimulant concentrations were 1 × 10−5m. The experimental results suggest a complex mechanism of conformational change for the initial stimulant‐induced molecular interactions in biological ch

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03362.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The distribution of glucose, glycogen, ATP, P‐creatine and inorganic phosphate was measured in layers I, III, IV, V and VI of cerebral cortex and subjacent white matter of mouse brain. ATP, P‐creatine and inorganic phosphate were evenly distributed in all regions examined, whereas levels of glucose and glycogen were higher in white matter than the average for the other layers. Anaesthesia increased levels of glucose and P‐creatine in layers I and V and subjacent white matter (other layers were not examined). Anaesthesia doubled the level of glycogen in molecular layer I with lesser increases in layers III, IV, V and VI, but with no change in white matter from the unanaesthetized control value.The metabolic rates in the individual layers were estimated from the rates of expenditure of energy reserves during total ischaemia. In non‐anaesthetized mice, white matter had a higher metabolic rate than either layer I or V. Anaesthesia reduced the metabolic rates in all layers; however, the largest reduction occurred in subjacent white matter (86 per cent), with reductions of 54 per cent and 76 per cent respectively in layer

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03363.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—To study the involvement of cholesterol esters in myelination and demyelination, we determined the concentration of free cholesterol and cholesterol esters and the activity of hydrolytic cholesterol esterase (sterol ester hydrolase; EC 3.1.1.13) in hen sciatic nerve during Wallerian degeneration. A progressive increase in the ratio of cholesterol ester to free cholesterol was observed in the degenerating nerve at 8, 16 and 32 days after nerve section. Hydrolytic cholesterol esterase activity decreased progressively in the degenerating nerves at the same time.In addition we measured the ratio of RNA to DNA, and the activity of the NADP+‐dependent isocitrate dehydrogenase [L8‐isocitrate: NADP oxidoreductase (decarboxylating); EC 1.1.1.42] at 8, 16 and 32 days after nerve section. The RNA to DNA ratios decreased progressively in the degenerating nerves. NADP+‐dependent isocitrate dehydrogenase increased in activity after nerve section, reaching a peak at

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03364.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Zusammenfassung—In akuten Versuchen an nicht narkotisierten, relaxierten, aufgespannten Katzen löst stereotaktisch in verschiedene Hirnregionen injiziertes Natriumglutamat eine generalisierte bioelektrische Krampfaktivität aus. Von allen untersuchten Regionen wurde für den Hippocampus die niedrigste Krampfschwelle nachgewiesen. Andere Hirngebiete sowie der Ventrikel reagierten nicht Oder nur auf höhere Glutamat‐Konzentrationen mit einem Krampf. Als krampfauslösende Ursachen werden Konzentrationsverschiebungen im Glutaminsäurestoffwechsel diskutiert.Abstract—Sodium glutamate stereotactically injected into different cerebral regions of cats caused generalized electroencephalographic seizures. The hippocampus was shown to have the lowest seizure threshold of all regions investigated. Other cerebral regions and the ventricle did not react at all or only to higher concentrations of glutamate. Differences in the activity of the glutamic acid metabolism are discussed as releasing factors f

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03365.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Total cholinesterase, acetylcholinesterase, (AChE) and monoamine oxidase (MAO) activity and protein content were determined throughout the embryonic life of the chick in spinal and sympathetic ganglia. The greatest part of total cholinesterase activity was due to AChE.AChE and MAO activity increased in both spinal and sympathetic ganglia very similarly from the 6th to the 12th day of incubation; from this day on a significant divergence occurred, mainly owing to a steady fall in spinal ganglion AChE, which decreased to approximately one tenth of the maximum value. The ratio of MAO activity in sympathetic and spinal ganglia increased from the 8th day onwards and approached 5·0 at hatching. The ratio between sympathetic and spinal ganglia, for AChE, choline acetylase (ChAc) and MAO activity, suggests a relationship between the maturation of the synapse in the sympathetic ganglia and the maximal activity of these enzym

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03366.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Slices of rabbit cerebral cortex were incubated in the presence of labelled amino acids. Following incubation, neuron‐ and gliaenriched fractions were obtained by density gradient centrifugation and the TCA‐insoluble radioactivity determined. The protein‐bound radioactivity was five to six times higher in the neuronal‐enriched fraction than in the glial‐enriched fraction after incubation with tritiated leucine. The neuronal fraction incorporated also a number of other amino acids to a higher extent than the glial fraction (neuron/glia ratio 2·5‐6). A definite dependence of incorporation on the rate of oxygenation was demonstrated. The suppression of amino acid incorporation was more marked for the neuronal fraction than for the glial fraction during incubation in relative hypoxia. An increase of potassium concentration in the incubation medium enhanced the amino acid incorporation in both fractions. Low sodium levels decreased the incorporation. Puromycin inhibited incorporation to approximately 30 per cent of control for both fractions. Addition of cycloheximide and dinitrophenol resulted in greater inhibition of incorporation in the neuronal fraction than in the neuroglial fraction. Actinomycin D did not markedly affect the incorporation in any fraction. These results are discussed in relation toin vivoand inin vitrodifferences for transport and incorporation

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03367.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Data have been presented indicating that in chicks the time lag in the onset of seizures after the administration of hydrazides was not caused by a slow penetration of the convulsant agents into the brain. A correlation was evident between the rate of decrease in concentration of cerebral GABA and the susceptibility of chicks to hydrazide‐induced seizures. Earlier studies precluding a role for GABA in hydrazide‐induced convulsions were re‐e

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03368.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Of the free amino acids found in extracts of cat spinal roots, dorsal root ganglia and peripheral nerves, only glutamate was present in disproportionately high concentrations in those parts of the dorsal roots between ganglia and spinal cord. This distribution suggests that the high dorsal root levels of glutamate may result from synthesis in dorsal root ganglia and subsequent transport towards the spinal cord. Four excitant amino acids were detected in the extracts: aspartate, cysteate, cysteine sulphinate and glutamate. The unique regional distribution of glutamate is consistent with the proposed role of this amino acid as an excitatory transmitter at the terminals of primary afferent fibre

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb03369.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY