摘要:

Abstract:Highly sensitive enzyme irnmunoassay systems for three forms (αα, αγ, and γγ) of rat brain enolase were prepared by use of specific antisera to two distinct subunits (α and γ) of the isozymes and β‐D‐galactosidase from Escherichia coli as label. Less than fmol‐levels of the homologous dimer forms (αα and γγ) could be determined with the corresponding antibody F(ab′)2‐bound solid‐phase and the antibody Fab′‐βD‐galactosidase complex. The hybrid form (αγ) could also be assayed specifically by use of the antibody to one subunit as solid‐phase, and the antibody to another subunit as labelled complex with a minim

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1981.tb01663.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract:Avermectin B1a, a macrocyclic lactone anthelmintic agent, causes a concentration‐dependent increase of [3H]flunitrazepam binding to membranes from rat cerebellum by increasing the affinity and the number of binding sites. This effect appears to be independent of the concentration of chloride ions. The effects of avermectin B1a occur with high affinity (EC50= 70 nM), and they persist after washing of the membranes with drug‐free buffer. Pretreatment of the membranes with Triton X‐100 completely abolishes the action of avermectin B1a. GABA and the GABA‐mimetic compounds piperidine‐4‐sulfonic acid and THIP diminish the effects of avermectin B1a on benzodiazepine receptor binding in a bicuculline‐methiodide‐sensitive mode. In addition, the stimulation of [3H]flunitrazepam binding by avermectin B1a is decreased by the pyrazolopyridines etazolate and cartazolate. These observations suggest that avermectin B1a stimulates benzodiazepine receptor binding by acting on a modulatory site which 1s independent of the GABA recognition site and of the drug receptor for the pyrazolopyridines, but which is in functional interaction w

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1981.tb01664.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract:A simple and sensitive gas‐chromatographic method for the determination of N‐acetyl‐l‐aspartic acid (NA‐Asp), N‐acetyl‐α‐aspartylglutamic acid (NA‐Asp‐Glu) and β‐citryl‐l‐glutamic acid (β‐CG) was developed. The organ, regional and phylogenetic distributions of these compounds were studied. NA‐Asp and NA‐Asp‐Glu were highly concentrated in nervous tissue, and less than 1% of the amounts in the nervous tissues were found in nonnervous organs. These two compounds showed a reciprocal relationship in their regional distribution in mature brains, but such a relationship was not evident or was even reversed in immature brains. The two compounds also showed different developmental changes in different regions of the brain. Fish brain contained a relatively high concentration of NA‐Asp, but only a trace amount of NA‐Asp‐Glu. By contrast, a 10 times higher concentration of NA‐Asp‐Glu than NA‐Asp was found in frog brain. Reptilian brain contained similar amounts of each compound. Avian and mammalian brain had NA‐Asp at a roughly 10 times higher concentration than NA‐Asp‐Glu. β‐CG occurred at the highest concentration in the immature brain of rat and guinea pig, but disappeared in the mature brains. The adult frog brain, however, contained a large amount of β‐CG. In the a

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1981.tb01665.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract:The specific binding ofl‐[3H]glutamate was investigated in the presence and the absence of sodium ions in freshly prepared membranes from rat hippocampus. Sodium ions were found to have a biphasic effect; low concentrations induced a marked inhibition of the binding (in the range 0.5‐5.0 mM), whereas higher concentrations resulted in a dose‐dependent stimulation of binding (in the range 10‐ 150 mM). These results permit the discrimination of two binding sites in hippocampal membranes. Both Na+‐independent and Na+‐dependent binding sites were saturable, exhibiting dissociation constants at 30°C of 750 nM and 2.4 μM, respectively, with Hill coefficients not significantly different from unity, and maximal number of sites of 6.5 and 75 pmol/mg protein, respectively. [3H]Glutamate binding to both sites reached equilibrium between 5 and 10 min and was reversible. The relative potencies of a wide range of compounds, with known pharmacological activities, to inhibit [3H]glutamate binding were very different for the Na+‐independent and Na+‐ dependent binding and suggested that the former sites were related to postsynaptic glutamate receptors, whereas the latter were related to high‐affinity uptake sites. This conclusion was also supported by the considerable variation in the regional distribution of the Na+‐dependent binding site, which paralleled that of the high‐affinity glutamate uptake; the Na+‐independent binding exhibite

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1981.tb01666.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract:The aim of the present study is to ascertain lipid composition in the ganglia of Mollusca. Nervous ganglia in the periesophageal ring dissected fromHelix pomatia, Lymnaea stagnalis, Murex trunculusandMurex brandariswere studied by biochemical and histochemical procedures. Glycosphyngolipids are present mainly as sulpholipid; sialic acid and gangliosides are not present as revealed by Svennerholm's reaction and TLC separation. The phospholipidcholesterol ratios are: 0.47 (Helix), 0.42 (Lyrnnaea), 0.86 (Murex brandaris) and 1.01 (Murex trunculus).

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1981.tb01667.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract:The effect of bilirubin on the temperature dependence of Na, K‐ATPase activity was investigated with NaI‐treated microsomes prepared from young (13‐ to 23‐day‐old) and adult (about 1‐year‐old) rat cerebra. The Arrhenius plots for the enzymic activities in the young and adult rats showed break temperatures at 26 and 18°C, respectively. In the young rat enzyme, bilirubin caused a shift of the break temperature to 23 and 22°C at concentrations of 60 and 120 μM, respectively, with a significant increase of the activation energy below the break temperature. However, no significant changes in the break temperature and the activation energy were observed in the adult rat enzyme exposed to the same concentrations of the pigment. The results suggest that the lipid environment surrounding the enzyme and modulating its activity in the plasma membranes may differ between the young and adult rat cerebra, and that bilirubin may change the physical state of the lipids related to the activity of the young

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1981.tb01668.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract:This is a study of the effects of a single “therapeutic” dose of glycerol [2 g(22 mmol)/kg i.p.] on brain carbohydrate and energy metabolism in normal nursing weanling mice. Findings were correlated with brain water and electrolyte content and with metabolite changes in plasma, red blood cells, and liver.Plasma glycerol levels peaked at 21 mM 7.5 min after injection and returned to the control value, 0.16 mM, by 2 h. Plasma Na+concentration decreased and plasma protein increased for as long as 2 h after injection. Although red blood cells were freely permeable to glycerol, there was no evidence for glycerol metabolism in these cells. Glycerol levels in liver paralleled those in plasma. Glycerol injection increased liver glucose concentration 23% and doubled hepatic glycerol‐1‐phosphate levels. Liver ATP levels were reduced 24% after glycerol injection.Brain water concentration was significantly reduced from 7.5 min to 30 min after glycerol injection; brain Na+and K+levels were unchanged. There was no evidence for glycerol entry into brain (the amount detected in brain tissue could be explained by the glycerol content in the blood of the brain). While plasma glucose increased 33%, brain glucose increased 87%. Concomitantly there were statistically significant increases in fructose‐1,6‐diphosphate, lactate, α‐ketoglutarate, and malate levels.The disproportionately high brain glucose value suggests increased transport of glucose from the blood to the brain. Increases in fructose‐1,6‐diphosphate, lactate, α‐ketoglutarate, and malate are compatible with an increased metabolic flux in the glycolytic pathway and Krebs citric acid cycle. As has been previously shown for urea and/or mannitol, these changes may result from the effects of the hyperosmolar glycerol solution on the blood‐brain barrier and on cerebral glucose utilization.The sustained lowering of plasma Na+concentration after a single “therapeutic” glycerol injection suggests a need for monitoring plasma Na+levels in the clinical situation. Possible lowering of hepatic ATP levels by the use of glycerol i

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1981.tb01669.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract:Free and membrane‐bound polysomes were prepared from rat forebrain and added to a cell‐free system containing rabbit reticulocyte factors and L‐[35S]methionine. The translation products were analyzed by two‐dimensional gel electrophoresis followed by autoradiography. The free polysomes synthesized actin and at least four major tubulin subunits (α1, α2, β1, and α2) that are found in rat forebrain cytoplasm. The membrane‐bound polysomes synthesized predominantly one protein (MB) in the tubulin region of the two‐dimensional gel. MB has a molecular weight and isoelectric point similar to α‐tubulin. Only trace amounts of α‐ and β‐tubulin and actin were synthesized by the membrane‐bound polysomes. MB co‐purified with cytoplasmic tubulin after two cycles of aggregation and disaggregation. MB synthesizedin vitro(from membrane‐bound polysomes) and α‐ and β‐tubulin and actin subunits (synthesized from free polysomes) were digested withStaphylococcus aureusV8 protease, and the resulting peptides were separated by slab gel electrophoresis followed by autoradiography. The peptide pattern of MB was similar but not identical to the peptide patterns of α‐ and β‐tubulin; MB yielded peptides not found in tubulin. We conclude that membrane‐bound polysomes from rat forebrain do not synthesize significant amounts of the predominant tubulin subunits synthesized by free polysomes. A major protein (MB) is synthesized by membrane‐bound polysomes and is similar, but not identical, to α‐tubulin synthesized by free polysomes on the basis of molecula

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1981.tb01670.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract:Enhanced phosphorylation of two specific protein bands accompanied catecholamine secretion from cultured bovine adrenal medulla cells stimulated by different secretagogues. Cells preincubated with32Piwere treated with nicotine, veratridine, Ionomycin, or barium. Each of these secretagogues stimulated the phosphorylation of two protein bands with apparent molecular weights of 60,000 and 95,000. Phosphorylation of the 60,000 M.W. protein band was two‐ to threefold higher than that of the 95,000 M.W. band on stimulation with nicotine, veratridine, or barium, but Ionomycin stimulated phosphorylation of each protein band to the same extent. In general, the increase in phosphorylation was most rapid during the first minute of stimulation and occurred prior to detectable secretion. Phosphorylation reached a relatively constant level within 5 min after onset of stimulation at a time when catecholamine release was still proceeding at a rapid rate. Nicotine‐stimulated phosphorylation and catecholamine secretion were calcium‐dependent and blocked byd‐tubocurarine, whereas tetrodotoxin inhibited veratridine‐stimulated secretion and phosphorylation. We conclude that catecholamine secretion and protein phosphorylation occur under similar conditions and that Ca2+‐dependent incorporation of phosphate into specific proteins may be a link in stimulus‐secre

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1981.tb01671.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Abstract:Using affinity chromatography and enzyme‐labelled immunological assays combined with aftinity adsorption, we have obtained evidence for the binding of a brain glycoprotein to hyaluronic acid, and on this basis named it hyaluronectin. This binding was inhibited by hyaluronic acid and by the products of its hydrolysis by hyaluronidase from bovine testis, but was not inhibited by other glycosaminoglycans or by monosaccharides. Preparative affinity chromatography of brain acid‐soluble proteins produced hyaluronectin in a good degree of purity. Contamination by albumin was less than 1% and the yield was as high as

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1981.tb01672.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY