摘要:

AbstractNerve growth factor binds to two different specific receptors on responsive cells. The relationship of these two receptors is not fully understood at this time. We have studied the binding of labeled NGF to a different strain of white leghorn chicken embryo dorsal root ganglionic cells. The equilibrium dissociation constants for the two sites (K d I= 4.1 ± 1.8 × 10−11M, K d II= 1.0 ± 0.8 × 10−9M) are identical to those obtained previously. Also, the number of type I sites per cell (3.8 ± 1.3 × 103) is the same as that previously determined. However, the number of type II sites per cell (1.9 ± 1.3 × 104) is significantly different than that previously determined. This 2.5‐fold decrease in the number of type II sites does not affect the concentration of NGF needed to obtain maximal fiber outgrowth from explanted sensory ganglia. The rate of association (1.2 ± 0.2 × 107M−1sec−1at 22°C) of labeled NGF with receptors on sensory neurons from this different strain of chickens is identical to that previously obtained.The rate of association of NGF with its receptors on sensory neurons was also determined at 4°C. This rate constant (2.1 ± 1.1 × 106M−1sec−1) along with the rate constants obtained at 22° and 37°C were used to determine an activation energy for the binding of NGF to its receptors. The activation energy obtained (16.2 kcal/mole) suggests that binding

ISSN:0360-4012    

DOI:10.1002/jnr.490070202

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

年代:1982

数据来源: WILEY

摘要:

AbstractMixed neuronal and nonneuronal cell cultures were obtained from 8‐day‐old chick embryos cerebral hemispheres and glial‐enriched cultures were obtained from fifteen‐day‐old chick embryo cerebral hemispheres. Cultures were exposed to methadone, a narcotic drug, from days four to six. The activity of ornithine decarboxylase (ODC) was determined at day eight and the activity of cyclic nucleotide phosphohydrolase (CNP) was determined at day fifteen. Both ODC and CNP activity were higher in mixed neuronal‐nonneuronal cell cultures treated with methadone as compared to control. No effect was observed in the neuronal‐enriched or glial‐enriched cultures. These findings are interpreted to reflect that neuronal‐glial interaction is important in the response of primary neural c

ISSN:0360-4012    

DOI:10.1002/jnr.490070203

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

年代:1982

数据来源: WILEY

摘要:

AbstractOligodendrocytes from early postnatal mouse cerebellum were isolated using polyacrylamide‐coated magnetic beads carrying monoclonal antibody to 04 cell surface antigen. Oligodendrocytes were enriched to a purity of 91 ± 4% starting from a mixed cell population containing approximately 1.5% antigen‐positive oligodendrocytes. Viability of 04 antigen‐positive oligodendrocytes was approximately 90% as judged by exclusion of trypan blue. Oligodendrocytes were recovered after detachment from the beads with a yield of 19 ± 6% and after collection by centrifugation onto glass coverslips with yields of approximately 6% of all 04 antigen‐positive cells. The final cell yield of oligodendrocytes is approximately 8 × 105cells/gram fresh cerebel

ISSN:0360-4012    

DOI:10.1002/jnr.490070204

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

年代:1982

数据来源: WILEY

摘要:

AbstractOligodendrocytes isolated by immunoaffinity on magnetic beads using a monoclonal antibody to oligodendrocyte cell surfaces were obtained with a purity of 91 ± 4% [see companion paper, Meier et al, 1982]. Contaminating cells consisted mostly of tetanus toxin‐positive neurons with small cell bodies. Very few glial fibrillary acidic protein‐positive astrocytes and fibronectin‐positive fibroblasts or fibroblast‐like cells could be detected by indirect immunofluorescence. Macrophages, as identified by their characteristic morphology, were rarely detectable in the cultures. With increasing time in culture, the degree of homogeneity of the cultured oligodendrocytes increased slightly, while the cell density of oligodendrocytes decreased drastically within the first week of culture. Cultures of immunoselected oligodendrocytes with a lower degree of purity showed a better survival of oligodendrocytes, but a considerable reduction in purity after three weeks in culture, probably due to overgrowth of nonoligodendroglial

ISSN:0360-4012    

DOI:10.1002/jnr.490070205

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

年代:1982

数据来源: WILEY

摘要:

AbstractHypoxic treatment causes changes of some enzymatic activities involved in the glycerolipid metabolism in subcellular fractions of guinea pig cerebral hemispheres. The activity of lysophosphatidylcholine acyltransferase, choline phosphotransferase, glycerol‐3‐phosphate acyltransferase(s), as well as the activity of triacylglycerol lipase significantly decreased in the microsomes of cerebral hemispheres of animals intermittently exposed to hypoxic treatment for eighty hours. At the same time, a marked activation of microsomal and mitochondrial phospholipase A2occurred. The changes of the above‐mentioned enzymatic activities after the hypoxic treatment correlated well with the increase in the level of brain and blood free fatty acids. The changes also correlated with the decrease of labeled lipid precursors incorporated into lipids of the cerebral hemispheres, observed during oxygen insuffic

ISSN:0360-4012    

DOI:10.1002/jnr.490070206

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

年代:1982

数据来源: WILEY

摘要:

AbstractIn order to further characterize the reaction mechanism of brain ChAc in its purified form, we have investigated the reverse reaction of ChAc in terms of pH optimum, salt effects, and substrate kinetics using a radiochemical assay. We directly measured the reaction product acetylcoenzyme A which was separated from the substrate ACh by a cation exchange column, Dowex 50W‐X8 (Na+form). The reverse reaction of ChAc was linear with incubation time up to 40 minutes, and with enzyme protein concentration up to 5 μg. It had a pH optimum at 7.0. At 0.22 M the monovalent chloride and bromide salts activated the reverse ChAc activity by 23–47% but the fluoride and iodide salts inhibited the reverse enzyme activity by 10–30%. Kinetic studies in the absence of salt showed that KAChwas 0.62 ± 0.06 mM, KCoA·SHwas 12.68 ± 1.21 μM, and Vmaxwas 11.6 ± 1.0 nmol AcCoA/mg protein/min. These data are in disagreement with the values reported on partially purified ChAc from bovine brain by Glover and Potter [1971] and Hersh [1980]. This indicates that further investigations are necessary to clarify or resolve these

ISSN:0360-4012    

DOI:10.1002/jnr.490070207

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

年代:1982

数据来源: WILEY

摘要:

AbstractStrips of guinea pig ileum lose over 70% of their contractility when bathed in Krebs‐Ringer solution containing 0.4–0.9 M formamide (FMD). This effect is not accompanied by an appreciable loss of tissue water and is totally reversed by washing the preparation in normal solution. Frog sartorius muscles also paralyze when immersed in Ringer containing FMD, but higher concentrations (1.0–2.0 M) and longer exposure times are required. Contractility is not recovered upon transferring these muscles to normal Ringer. However, the contractile proteins still respond to activator calcium as shown by the fact that these muscles still contract in the presence of caffeine. The membrane of muscles uncoupled by FMD retain electrical excitability, and neuromuscular transmission appears to be unimpaired. However, alterations in the early after‐potential of the spikes suggest the occurrence of a sarcotubular disruption. Therefore, FMD appears to exert two separate effects on muscle: a reversible inhibition of contractility, as observed in ileal strips and an irreversible blockade due to an osmotic shock observed when frog muscles are returned to normal Ringer. The reversible effect is probably related to interference with the availability of activator calcium, since no marked inhibitory effects on the activities of the actomyosin‐like and the calcium‐dependent and ‐independent ATPases could be observed on FMD‐treated subcel

ISSN:0360-4012    

DOI:10.1002/jnr.490070208

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe acetylcholine (ACh) responses of anterior aorta muscle cells of Aplysia kurodai were studied by intracellular recording and ACh iontophoresis. Three different types of membrane potential change were observed in response to ACh pulses: a rapid Na+‐mediated depolarizing response, a slow, mainly Cl−, in part K+‐mediated, hyperpolarizing response, and Na+(for depolarizing component) and Cl−(for hyperpolarizing component)‐mediated biphasic response. The depolarizing response and the depolarizing component of the biphasic response were effectively blocked by hexamethonium or atropine. The hyperpolarizing response and the hyperpolarizing component of the biphasic response were completely blocked by tubocurarine. Low concentrations of ACh inhibited and relaxed the anterior aorta muscle; high concentrations of ACh excited the muscle and initiated contraction. The biphasic responses to ACh are likely due to the presence of more than one ACh receptor type on the same cell membrane of the anterior aorta mus

ISSN:0360-4012    

DOI:10.1002/jnr.490070209

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

年代:1982

数据来源: WILEY

摘要:

AbstractSome metabolites (glycogen, glucose, glucose‐6‐phosphate, pyruvate, lactate, citrate, α‐ketoglutarate, succinate, fumarate, malate, glutamate, aspartate, γ‐aminobutyrate, glutamine, alanine, NH+4) were measured in rat cerebral cortex after 5 minutes of complete compression ischemia, as well as after 5, 15, or 30 minutes of recirculation following 5 minutes of ischemia.Complete ischemia induced a drop of glycolytic substrates and intermediates, consistent with the increase of lactate, succinate, alanine, and γ‐aminobutyrate, and with the decrease of malate, fumarate, and α‐ketoglutarate. These events may be regarded as an expression of the activation of the γ‐aminobutyrate cycle and of the succinate cycle, where succinate itself, in the absence of O2, acts as a terminal electron acceptor.During post‐ischemic recovery, cerebral parameters tended to normalize, except for the further increase of alanine and the still higher than normal content of both succinate and γ‐aminobutyrate, as an expression of the possible activation of the γ‐glutamyl and γ‐aminobu

ISSN:0360-4012    

DOI:10.1002/jnr.490070210

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

年代:1982

数据来源: WILEY

摘要:

AbstractClinical signs of EAE were infrequently observed (1/20) in adult Hartley guinea pigs challenged with isolated human myelin lipophilin in complete Freund's adjuvant. However, CNS vasculitis and parenchymal infiltration by inflammatory cells were found in 10 of 20 inoculated animals. Localized, nonconfluent, small demyelinated lesions were detected in the brain and spinal cord of 5/20 Hartley guinea pigs during an observation period of 120 days. The frequency of both inflammatory and demyelinated lesions in Hartley animals appeared to be dosedependent, but extensive demyelinated lesions were not induced. Persistent residual inoculation mixture at the site of injection was found in animals showing CNS inflammatory and/or demyelinated lesions. In contrast to the Hartley strain, young strain 13 guinea pigs were clincally and pathologically unresponsive to challenge with lipophilin and mycobacteria in water‐in‐oil emuls

ISSN:0360-4012    

DOI:10.1002/jnr.490070211

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

年代:1982

数据来源: WILEY