摘要:

Abstract:Thein vivooxidation of the norepinephrine metabolite 4‐hydroxy‐3‐methoxyphenylglycol (HMPG) to 4‐hydroxy‐3‐methoxymandelic acid was studied in man with two different doses of deuterium‐labeled HMPG and a tracer dose of [14C]HMPG. HMPG oxidation appeared to be dose‐dependent with an oxidation of 62–70% for doses below or equal to 2.2 μmol. With the use of a capillary column coated with an optically active phase (Chirasil‐Val) and gas chromatography mass‐spectrometry the human urinary excretions of the two stereoisomers of deuterium‐labelled HMPG (free + conjugates

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb04743.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:The effect of phospholipid methylation on both [3H]diazepam and [3H]GABA ([3H]γ‐aminobutyric acid) binding to crude synaptic plasma membrane from rat cerebellum has been studied.S‐Adenosylmethionine (SAM) stimulates [3H]methyl group incorporation into membrane phospholipids and enhances [3H]diazepam binding by increasing the apparentBmax. Conversely, inhibition of [3H]methyl group transfer from [3H]SAM to phospholipids by preincubation with SAM at 0°C or with SAH abolishes the increase of binding. After preincubation with SAM, analysis of the GABA binding reveals the presence of binding sites with high affinity, a property absent in control membranes preincubated without SAM. Among the neurotransmitter bindings tested, only those of GABA and benzodiazepine in the cerebellum and β‐adrenergic ligands in the cerebral cortex are enhanced upon stimulation of phospholipid methyltransferase activity. [3H]Dihydromorphine, [3H]dihydro‐α‐ergokryptine and [3H]spiroperidol bindings are not affected by SAM. The present data suggest an involvement of phospholipid methylation in regulation of both [3H]GABA and [3H]‐d

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb04744.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:Perilymph, which bathes the sensory cells of the cochlea, was collected from guinea pigs exposed to noise and analyzed via two cation‐exchange HPLC procedures with fluorescence detection, resolving 51 and 81 primary‐amine compounds, respectively, at a sensitivity limit of 0.1 pmol relative to leucine. During a first period, each animal was either exposed to noise at 80, 90, or 115 decibels sound‐pressure level or maintained in silence (controls), and during a second period, the same animal was maintained in silence. Perilymph was collected during both periods, and perilymphatic components were compared, within animals and across animals, for several levels of sound stimulation. A 7‐aminobutyric acid‐like component was elevated in the first period in proportion to stimulus intensity by the various methods of comparison, suggesting an auditory‐neurotransmitter role for this component. Aspartic acid was elevated in the second period, 2–3.5 h after onset of sound stimulation, compatible with the release of aspartic acid from central auditory synapses. In addition, a methionine‐enkephalin‐like component, distinct from leucine‐enkephalin, was detected in perilymph from control animals and was elevated in response to noise at 115 decibels. Regression coefficients, determined for the relation between sound intensity and first‐period concentrations or the difference between first and second‐period concentrations, indicated zero linear regression at p = 0.05 for glutamic acid, aspartic acid, glycine, taurine, and 39 other perilymphatic components, consistent with the hypothesis that these compounds are unlikely to be peripheral aud

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb04745.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:A neutral, mannose‐rich, concanavalin A (Con A)‐binding glycopeptide fraction was obtained by proteolytic digestion of defatted beef brain tissue. Hydrazinolysis followed by gel filtration of the reaction products provided three oligosaccharides. A portion of each oligosaccharide was treated by exhaustive digestion with α‐mannosidase. Another portion was subjected to selective acetolysis of Manαl‐6Man linkages, providing two fragments that were recovered by gel filtration. The structure of the intact oligosaccharides, as well as the fragments obtained by selective acetolysis and enzymatic treatment, were resolved by gas‐liquid chromatographic‐mass spectrometric analysis. The structures of the three oligosaccharides were: (a) Manαl‐2Manαl‐6(Manαl ‐3)Manαl‐6(Manαl‐2Manαl‐2Manαl 3)Manβ1‐4‐N‐acetylglucosamine (GlcNAc)β ‐4N‐acetylglucosaminitol (GlcOLNAc); (b) Manαl ‐2Manαl ‐6(Manαl ‐3)Manαl‐6(Manαl‐2Manαl‐3)‐Manβ1‐4GlcNAcβl ‐4GlcOLNAc; and (c) Manαl ‐6(Manαl‐3) Manαl ‐ 6(Manαl ‐ 3)Manβl ‐4GlcNAc‐βl ‐ 4GlcOLNAc. These structures account for 15–20% of the glycoprotein‐carbohydrate of whole beef brain and most of the oligosaccharides that demonstrate a high affinity for Con A. In view of the large number of Con A‐binding glycoproteins in brain tissue, it appears

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb04746.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:Affinity‐purified anti‐B‐50 protein antibodies were used to study the previously proposed relationship of the phosphorylation state of B‐50 protein and polyphosphoinositide metabolism in synaptic plasma membranes. Antibodies were raised against a membrane extract enriched in the B‐50 protein and its adrenocorticotropin‐sensitive protein kinase, obtained from rat brain. Anti‐B‐50 protein immunoglobulins were purified by affinity chromatography on a solid immunosorbent prepared from B‐50 protein isolated by an improved procedure. The purified antibodies reacted only with the B‐50 and B‐60 protein, a proteolysis derivative (of B‐50), as assessed by the sodium dodecyl sulfate‐gel immunoperoxidase method. These antibodies inhibited specifically the endogenous phosphorylation of B‐50 protein in synaptic plasma membranes, without affecting notably the phosphorylation of other membrane proteins. This inhibition was accompanied by changes of the formation of phosphatidylinositol 4,5‐diphosphate and phosphatidic acid in synaptic plasma membranes, whereas formation of phosphatidylinositol 4‐phosphate was not altered. Inhibition by ACTH1–24of the endogenous phosphorylation of B‐50 protein in membranes was associated only with an enhancement of the phosphorylation of phosphatidylinositol 4‐phosphate to phosphatidylinositol 4,5‐diphosphate. These data support our hypothesis on the functional interaction of B‐50 protein and phosphatidylinositol 4‐phosphate kinase in rat brain membranes. The evidence shows that purified anti‐B‐50 protein antibodies can be used to probe specifi

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb04747.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:Adrenoleukodystrophy (ALD) is an X‐linked progressive neurological disorder characterized by the accumulation of saturated very‐long‐chain fatty acids (C24to C30) in lipids, especially cholesterol esters of tne brain white matter and adrenal cortex. In the present study we have investigated the localization of accumulated cholesterol esters in brain white matter. During isolation of purified myelin membrane from regions of active demyelination, significant enrichment in cholesterol ester was found in two fractions, mainly in a low‐density floating fraction and to a lesser degree in the purified myelin preparation. The fatty acid composition of cholesterol esters from both the ALD floating and myelin fractions was enriched approximately 10‐fold in saturated very‐long‐chain fatty acids (≥C24) compared with contr

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb04748.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:High‐affinity [3H]5‐hydroxytryptamine ([3H]5‐HT) binding in the rat spinal cord is similar to that demonstrated in the frontal cortex. [3H]5‐HT binds with nearly the same affinity to sites in both tissues. Furthermore, similar patterns of displacement of [3H]5–HT were seen in both tissues, with either spiperone or LSD as the unlabeled ligand. This high‐affinity binding appears to be to multiple sites, since displacement studies using 2nM [3H]5–HT result in Hill coefficients less than unity for spiperone, LSD, and quipazine [Hill coefficients (nH): 0.44, 0.39, 0.40, respectively]. These sites apparently have an equal affinity for [3H]5‐HT, since unlabeled 5‐HT did not discriminate between them. Thus, the high‐affinity [3H]5‐HT binding in the spinal cord may be analogous to that observed in the frontal cortex, where two populations of sites have previously been described (5‐HTIA, 5‐HTIB). In addition to the multiple high‐affinity spinal cord binding sites, a low‐affinity [3H]5‐HT binding component was also identified. A curvilinear Scatchard plot results from saturation studies using [3H]5‐HT (0.5–100nM) in the spinal cord. The plot can be resolved into sites having apparent dissociation constants of 1.4nM and 57.8nM for the high‐and low‐affinity components, respectively. Additional support for a change in affinity characteristics at higher radioligand concentrations comes from the displacement of 30nM [3H]5‐HT by the unlabeled ligand. A nonparallel shift in the dissociation curve was seen, resulting in a Hill coefficient less than unity (0.32). None of the specifically bound [3H]5‐HT in the spinal cord is associated with the 5‐HT uptake carrier, since fluoxetine, an inhibitor of 5‐HT uptake, does not alter binding characteristics. In addition, a 5‐HT binding site analogous to the site designated 5‐HT, was not apparent in the spinal cord. Ketanse‐rin and cyproheptadine, drugs that are highly selective for 5‐HT, sites, did not displace [3H]5‐HT from spinal tissue, and [3H]spiperone, a radioligand that binds with high affinity to 5‐HT2sites, did not exhibit saturable binding in the tissue. Thus, the 5‐HT2binding site reported in other regions of the central nervous system, and the serotonin uptake carrier do not appear to contribute

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb04749.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:D2 is a glycoprotein enriched in neuronal membranes and probably involved in intercellular adhesion. An immunochemical relationship between D2 and the neuronal cell adhesion molecule from chick has been demonstrated. Changes in D2 concentration in human body fluids correlate to certain neurological diseases.We here report the purification of the D2 membrane proteins from fetal and adult human brain and the demonstration of physicochemical differences between the two proteins. Enrichments of 133 times (fetal D2) and 350 times (adult D2) were found. Specific rabbit antisera against the purified D2 proteins were produced, and this enabled the setting up of an enzyme‐linked immunosorbent assay for D2 quantification in human brain extracts, cerebrospinal fluids, sera, and amniotic fluid

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb04750.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:D2 is a glycoprotein existing in both membrane‐bound and soluble forms. Employing a specific rabbit antibody against purified human brain D2, we developed an enzyme‐linked immunosorbent assay (ELISA) for the quantification of D2 and applied it to amniotic fluids from 87 normal and 36 pathological pregnancies. With a cut‐off point of 150 ng D2/ml, no false positive D2 values were obtained in any of the amniotic fluids from normal fetuses, although the alpha‐fetoprotein concentrations were slightly increased in 13 cases. No false negative D2 values were found in any of the 18 investigated amniotic fluids from fetuses with anencephaly. Of 8 amniotic fluids from fetuses with spina bifida, 2 false negative D2 values were found. No false negative alphafetoprotein values were found in any of the cases with neural tube defects in this study. In 10 amniotic fluids from fetuses with other malformations, 5 samples showed raised D2 concentrations. The D2 level in sera from 10 women carrying normal fetuses and 16 women carrying malformed fetuses was also determined, but no statistically significant difference in D2 level was found in the pathological sera when compared with normal sera. It was concluded that the determination of D2 concentrations in amniotic fluid by means of the D2‐ELISA may be used as an additional test in the screening of fetal malformations in early

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb04751.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:The binding properties ofN6‐cydohexyl [3H]adenosine ([3H]CHA) and 1, 3‐diethyl‐8‐[3H]phenyl‐xanthine ([3H]DPX) in rat forebrain membrane are compared. The kinetic parameters of binding for each ligand are quite distinct, with [3H]CHA displaying two populations of binding sites (KD= 0.4 ± 0.05nMand 4.2 ± 0.3nM;Bmax= 159 ± 17 and 326 ± 21 fmol/mg protein), whereas [3H]DPX yielded monophasic Scatchard plots (KD= 13.9 ±1.1 nM;Bmax= 634 ± 27 fmol/mg protein). The metals copper, zinc, and cadmium are potent inhibitors of [3H]CHA binding, with respective IC50concentrations of 36[μM, 250)μM, and 70μM. Copper is a much less potent inhibitor of [3H]DPX binding (IC50= 350μM). The inhibitory effect of copper on both [3H]CHA and [3H]DPX binding is apparently irreversible, as membranes pretreated with copper cannot be washed free of its inhibitory effect. The inhibitory effect of both copper and zinc on [3H]CHA binding was reversed by the guanine nucleotide Gpp(NH)p. [3H]DPX binding is only partially inhibited by zinc and cadmium (60% of specific binding remains unaffected), suggesting that this adenosine receptor ligand binds to two separate sites. Guanine nucleotides had no effect on the inhibition of [3H]DPX binding by either copper or zinc. Differential thermal and proteolytic denaturation profiles are also observed for [3H]CHA and [3H]DPX binding, with the former ligand binding site being more labile in both cases. Stereospecificity is observed in the inhibition of both [3H]CHA and [3H]DPX binding, with l‐N‐phenylisopropyladenosine (PIA) being 50‐fold more potent than d‐PIA in both cases. Evidence is therefore provided that adenosine receptor agonists and antagonists have markedly different binding properties t

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb04752.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY