摘要:

Abstract—A specific radioimmunoassay (RIA) for myelin basic protein is described which is sensitive to 10−9g of basic protein. The amount of basic protein detected in isolated myelin by the RIA and by SDS‐gel electrophoresis and spectrophotometric quantitation agree to within experimental error. In contrast to isolated myelin, the major portion of the basic protein in fresh tissue is not accessible to its antibody. It is shielded from its antibody in a complex which is disrupted by heat, organic solvents, and various detergents. Maximum antibody binding was obtained with tissue heated to 100°C for 10 min. It is possible to calculate that the RIA quantitatively detects basic protein in boiled tissue. Boiled adult rat brain contains approximately 2·5 μg of basic protein/mg wet wt of cerebral cortex. The antibody to basic protein has no capacity to bind non‐neur

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb04329.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—Thyroid hormone deficiency induced during the neonatal period in the rat, resulted in an enhanced incorporation of [2‐14C]uridine and [8‐14C]adenosinein vitrointo cerebral cortical RNA at 25 days of age. An examination of the acid‐soluble pool constituents separated by polyethyleneiminecellulose TLC, revealed that all phosphorylated derivatives were more highly labelled compared to controls. These differences were not apparent at a lower incubation temperature (4°C). When the average specific activity of precursor pool ATP labelled from adenosine was utilized for the calculation of the rate of RNA synthesis, no change was observed in hypothyroidism. The results are compatible with a maturational‐dependent increase in nucleoside transport and rate of phosphorylation in hypothyroidism which is reflected in the stimulated incorporation into cerebral RNA. The apparent normal rate of RNA synthesis coupled with a diminished cellular RNA concentration in thyroid hormone deficiency, suggests an increased RNA turnover. Experiments with actinomycin D revealed no apparent difference in the rate of decay of rapidly‐labelled (nuclear) RNA. The possibility is discussed that the processing of nuclear RNA, the formation of stable ribosomal complexes and events at the translational level are subject to modification in developing hypo

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb04331.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—Using a simple apparatus designed to perfuse nervous tissue mini‐slices retained on glass fibre filter discs, slices of adult (13 week) rat cerebral cortex and spinal cord were shown to release radioactive GABA and glycine, but not 2‐amino‐isobutyric acid, in response to increased potassium ion concentration of the perfusing medium. A major portion of this potassium‐stimulated release was dependent upon the presence of calcium ions in the perfusing medium. Slices of cerebral cortex and spinal cord from rats of 1 day and 10 days postnatal age showed potassium‐stimulated, calcium‐dependent release of radioactive GABA and glycine respectively. These findings are consistent with other evidence that GABA and glycine are functioning as inhibitory transmitters in rats at least as soon as 1 da

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb04333.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—Bulk prepared neuronal perikarya, nerve endings and glial cells have been used to study amino acid concentrations and GABA metabolismin vitro.All amino acids were more concentrated in synaptosomes and glial cells than in neuronal perikarya. Cell specificity was found with respect to the relative distribution of some amino acids. Glutamate decarboxylase activity was considerably higher in synaptosomes than in glial cells. The inhibitory effect of amino‐oxyacetic acid on glutamate decarboxylase activity differed between synaptosomes and glial cells. γ‐Aminobutyric acid‐α‐ketoglutarate transaminase had the highest activity in the glial cell fraction; the inhibition of amino‐oxyacetic acid differed between glial and neuronal material. The metabolism of exogenous GABA just accumulated by a cell showed similar time characteristics in neuronal and g

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb04335.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—RNA from rat brain synaptosomes, mitochondria and microsomes was analysed by gel electrophoresis under conditions allowing good resolution in three different molecular weight ranges: 4s‐16s, 16s‐28s and>28s.Two synaptosome specific RNA bands were found, one with comparatively low molecular weight (8‐9 × 104Daltons) and another very large (sE>60s).RNA species with electrophoretic characteristics similar to those reported for liver mitochondrial RNA were found in brain mitochondria. From the electrophoretic data their mean geometric radii were de

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb04337.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—Tryptophan hydroxylase form pig brain has been purified using a method which involved sonic disintegration of a whole homogenate, ammonium sulphate fractionation, hydroxylapatite fractionation, column chromatography on Sephadex G‐100 or G‐200 and finally electrophoresis on poly‐acrylamide gel. The enzyme was stabilized during purification by tryptophan and dithiothreitol. The partially purified enzyme has a molecular weight of 55,000‐60,000 as measured by gel‐filtration. TheKmof the soluble partially purified enzyme was 0‐4 mm, which differed significantly from that of the particulate enzyme (0·02mm). Enzyme activity was not stimulated by ferrous ion. However, it was inhibited by the chelating agents 8‐hydroxyquinoline, O‐phenanthroline and EDTA. In contrast to dopamine, high concentration of tryptophan (10 mm), 5‐hydroxytryptamine, tryptamine and tyramine at 0‐5 mmconcentration did not inhibit the enzyme in the presence of dimethyltetrahydropterin (DMPH4). A number of monoamine oxidase inhibitors, phenelzine, pheniprazine and chlorgyline at 1 mmstrongly inhibit the formation of 5‐hydroxytryptamine. Evidence is presented for the presence of an endogenous inhibitor o

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb04338.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—The regulation of [14C]ACh synthesis was studied in rat striatal synaptosomes incubated in presence of various concentrations of Triton X‐100, using [2‐14C]pyruvate or [6‐14C]glucose as precursors. The progressive rupture of the cytoplasmic and mitochondrial compartments induced by the non‐ionic detergent was followed by studying the release, into the incubating medium, of lactate dehydrogenase and choline acetyltransferase (ChAc) and of fumarate hydratase, respectively. [3H]Choline uptake (1 μm) was measured to determine the activity of the high affinity choline permease.14CO2formation from [2‐14C]pyruvate was used as an index of the Krebs cycle activity.The rate of [14C]ACh synthesis from [2‐14C] pyruvate was dependent on the Triton X‐100 concentration; the ester formation decreased between 0·001% (v/v) and 0·010%, but increased again beyond this concentration of detergent. This last phenomenon was interpreted as the result of an extracellular synthesis of ACh involving pyruvate dehydrogenase and ChAc. At 0·002% Triton X‐100 the14CO2formation was not affected, indicating a normal mitochondrial activity. The decrease of [14C]ACh synthesis observed up to this detergent concentration could be correlated to the decline of the highaffinity choline permease activity. In these experimental conditions, the ester synthesis could not be restored by the addition of large amounts of choline in the incubating medium suggesting that the molecules of choline must cross the high‐affinity choline permease system in order to be acetylated. This could indicate a close association between the permease and ch

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb04339.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—It was the aim of the present study to develop organ culture conditions for the rat adrenal medulla which are representative for thein vivosituation. This is a prerequisite for studying the complex processes involved in trans‐synaptic enzyme induction. The processes of trans‐synaptic enzyme induction initiatedin vivoby injecting 5 mg/kg of reserpine 2 h prior to the removal of the adrenal medulla, continued in this culture system and final levels of tyrosine hydroxylase were comparable to those seenin vivo.That these culture conditions are representative for thein vivoinduction is also supported by the fact that transection of the splanchnic fibres supplying the adrenal medulla or administration of actinomycin D prior to reserpine abolished the rise in tyrosine hydroxylase activity not onlyin vivo, but also in culture.The findings that high concentrations (0·29 mm) of corticosterone in the culture medium inhibited the increase in tyrosine hydroxylase activity caused by reserpine support the hypothesis that glucocorticoids act as modulatory agents in trans‐synaptic enzyme induction. This inhibition was exhibited only when corticosterone was added at the initiation of the culture period. If added 2 or 4 h after the beginning of the culture period there was little or no effect on the subsequent increase of tyrosine hyd

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb04340.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—Glial cells were cultured from brain tissue obtained at autopsy of a patient with Sanfilippo A syndrome. Mucopolysaccharides were labeled by culturing the cells in the presence of [35S]sulfate. After proteolysis, intracellular and media‐elaborated mucopolysaccharides were fractionated by Dowex 1 chromatography. One fraction, identified as heparan sulfate by chromatographic, electrophoretic, and enzyme susceptibility properties, accumulated in Sanfilippo glial cells in greater amounts than in controls. Heparan sulfate was also excreted into the culture media by both Sanfilippo and normal cultures, and it constituted a major fraction of the sulfated mucopolysaccharides synthesized by glial cells. Sanfilippo and normal fibroblasts were also included in these studies for comparative purposes. Sanfilippo fibroblasts accumulated significantly increased amounts of heparan sulfate as compared to normal fibroblasts. Heparan sulfate was excreted into the culture media by Sanfilippo and normal fibroblasts in equivalent amounts, but in contrast to glial cells, it was only a minor component of the sulfated mucopolysaccharides produced. Cultured glial cells should provide a useful system for investigating the role of heparan sulfate in glial cell funct

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb04345.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—The concentration of GTP was found to be critically important in determining the characteristics of incorporation of GMP by DNA‐dependent RNA polymerase from rat brain nuclei. The linearity of the incorporation rate was related to the log of the GTP concentration. Three hundred μM‐GTP in the presence of the other nucleoside triphosphates (1 mM) was near to the optimal conditions in terms of maximum incorporation and linearity. The concentration of ammonium sulfate was an important factor in determining the maximum GMP and UMP incorporation. The U/G incorporation ratio was less than one at low concentrations of substrate and increased with increasing substrate or ammonium sulfate concentration. α‐Amanitin strongly inhibited the reaction, indicating that RNA polymerase II is the effecti

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb04347.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY