摘要:

AbstractRegeneration of severed peripheral nerves is unfortunately often incomplete, due to loss of nerve fibers and neuroma formation. A new approach is presented with the intention of improving the conditions for nerve repair. In the first of the two stages, a pseudosynovial tube is formed around a silicone rubber rod, surrounded by a stainless steel spiral, which was placed in the backs of rats. This tube, in the second stage, is used as a free “tube graft” to bridge gaps of about 10–12‐mm lengths in the severed sciatic nerve. The tube was kept open by the metal spiral. Regenerating nerve fibers with their sprouts grew into the initially open space in the tube. A new nerve trunk was formed, comprised of closely packed myelinated and unmyelinated axons, organized into fascicles. Demonstration by electron microscopy and by EMG recording of reinnervation of foot muscles supported successful long‐term results. The fascicles were delimited by perineurial and epineurial sheaths and, furthermore, showed signs of maturation. It was also demonstrated that the nerve‐fiber regeneration ceased after a few weeks if there was no distal nerve inserted into the tube. The importance of optimizing the interaction between local factors and regenerating nerve fibers for reestablishment of functionally valuable motor units i

ISSN:0360-4012    

DOI:10.1002/jnr.490060302

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe effects of various neurotransmitters and cyclic nucleotides on45Ca2+efflux in cultured human glioma cells were investigated. Glutamate and glycine, but not GABA, stimulated45Ca2+release from the cells.Stimulation of beta‐adrenergic receptors but not alpha‐adrenergic receptors also increased45Ca2+efflux. Cholinergic receptor stimulation by carbachol had the same effect. The stimulatory effect of carbachol was abolished in the presence of either atropine or hexamethonium.C‐AMP and c‐GMP increased the45Ca2+efflux, suggesting that these agents are involved in the transmitter‐stimulated release of45Ca2+from the cells.Kinetic analysis of the efflux revealed four calcium compartments. The carbachol‐stimulated efflux represented a net release of calcium and could be ascribed to the slowest compartment.The physiological role of the transmitter‐stimulated calcium release is discussed in terms of calcium‐regulated stimulus‐response coupling in glial‐neural interactio

ISSN:0360-4012    

DOI:10.1002/jnr.490060303

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

年代:1981

数据来源: WILEY

摘要:

AbstractSeveral metabolic activities in dissociated cultures of newborn mouse brain were compared to the situation in vivo. The developmental activity pattern of cerebroside‐sulfotransferase, cyclic nucleotide phosphohydrolase, and β‐hydroxy‐β‐methyl glutaryl‐coenzyme A‐reductase and the synthesis and deposition of sulfatide and cholesterol in culture were estimated. The enzyme activity patterns in vivo and in culture are the same. Since the cultures show very little myelin formation, the parallel increase of enzyme activities necessary for myelination in vivo and in culture suggest the existence of intrinsic factors regulating the biochemical differentiation. In addition, the formation of the products, determined in culture, follows the patterns of the enzyme activities. Dissociated brain cell cultures are therefore a valid model for the study of biochemical parameters related to the synthesis of brain lipids durin

ISSN:0360-4012    

DOI:10.1002/jnr.490060304

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

年代:1981

数据来源: WILEY

摘要:

AbstractMyelin basic protein (MBP) was quantified using a RIA technique in the spinal cord, cerebellum, diencephalon plus brainstem region and cerebral hemispheres of two dysmyelinating murine mutants, quaking (qk) and jimpy (jp) mice. Comparison was made with normal control values. The whole life‐span has been investigated: ie, ages ranging from 0 to 26 days for the jp, 0 to one year for the qk, and prenatal stage to three years for the control animals. Assays in the mutants at early ages were rendered feasible by the use of marker genes, which has allowed the diagnosis of the mutation at birth, 12 days before the expression of their typical tremor phenotype. Special care was given to the period of early myelinogenesis in order to clarify the dysynchrony between the various parts of the central nervous system.In normal mice, MBP was already detected in the brain of 19‐day‐old embryos. During development, rapid accumulation of MBP first occurred in the spinal cord then in the diencephalon, the brainstem, the cerebellum, and finally in the cerebral hemispheres.In the 25‐day‐old jimpy mutant, levels of MBP were found dramatically decreased, never exceeding 6% of the normal controls in any of the areas investigated.The situation for the quaking mouse was quite different. This mutant could be investigated up to one year old. At that age, a high discrepancy was observed between the values found in the brain and in the spinal cord (respectively, 10% and 35%) compared to normal controls.In both mutants, not only were the levels of MBP decreased, but also its appearance during development was delayed. Nevertheless, in both mutants the caudo‐rostral timing of myelination as assayed by MBP levels was maintained. Furthermore, the later myelination occurred, the stronger was the deficit in MBP. Interestingly, in the quaking mutant, the specific plasticity of the spinal cord was exemplified by its ability to reduce constantly, even at an advanced age, its initial def

ISSN:0360-4012    

DOI:10.1002/jnr.490060305

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe level of binding of a labeled acetylcholine muscarinic antagonist (quinuclidinyl benzilate) to different cerebral membranes has been measured. Of the regions examined, circadian rhythmicity of binding could only be detected significantly in the hippocampus and the hypothalamus and not in the cerebral cortex, striatum, or cerebellum.

ISSN:0360-4012    

DOI:10.1002/jnr.490060306

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe nerve growth factor protein (NGF) stimulates neurite outgrowth from embryonic sensory ganglia and sympathetic ganglia at all stages of development. In addition, NGF is required for the maintenance of the differentiated state in adult sympathetic ganglia. A clonal cell line, IMR‐32, derived from a human neuroblastoma was found to contain a population of cells that respond to NGF by exhibiting morphological differentiation. The effect of NGF on these cells is compared with that of other agents known to induce differentiation of IMR‐32, including glioma‐conditioned

ISSN:0360-4012    

DOI:10.1002/jnr.490060307

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

年代:1981

数据来源: WILEY

摘要:

AbstractSlow‐twitch soleus and fast‐twitch extensor digitorum longus muscles of the rat were denervated unilaterally by sciatic nerve section at mid‐thigh level. Activities of adenylate cyclase, guanylate cyclase, low Kmand high Kmcyclic AMP phosphodiesterase, and cyclic GMP phosphodiesterase were compared on the same, freshly prepared homogenates of denervated and shamoperated contralateral muscles one, two, three, or five days after surgery. As an early consequence of denervation, cyclic AMP metabolism was differentially affected in these different types of skeletal muscle. The adenylate cyclase activity of soleus muscle increased significantly by the second day following denervation and continued to rise through the fifth day, while this enzyme did not increase in denervated extensor digitorum longus even by the fifth day. The high Kmcyclic AMP phosphodiesterase was already increased by day one in the denervated soleus, but not until the fifth day in the denervated extensor digitorum longus. Parallel increases beginning the first day were observed for the low Kmcyclic AMP phosphodiesterase in both muscles. Since the activity of cytosolic cyclic AMP‐dependent protein kinase of soleus muscle was also increased two days following denervation, the changes in cyclic AMP synthetic and degradative enzymes apparently result in a rise in intracellular cyclic AMP concentration. Alterations of the cyclic GMP enzymes following denervation were similar in the soleus and extensor digitorum longus, but were delayed relative to the increases in activity in the cyclic AMP

ISSN:0360-4012    

DOI:10.1002/jnr.490060308

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

年代:1981

数据来源: WILEY

摘要:

AbstractIsolated frog rod outer segments (ROS) incubated in a Krebs‐bicarbonate medium, and illuminated for 2 h, show a profound alteration in their structure. This is characterized by distention of discs, vesiculation, and a marked swelling. The light‐induced ROS disruption requires the presence of bicarbonate and sodium chloride. Replacement of bicarbonate by TRIS or HEPES protects ROS structure. Also, substitution of sodium chloride by sucrose or choline chloride maintains unaltered the ROS structure. Deletion of calcium, magnesium, or phosphate does not modify the effect produced by illumination. An increased accumulation of labeled bicarbonate and tritiated water is observed in illuminated ROS, as compared with controls in the dark. The presence of taurine, GABA, or glycine, at concentrations of 5–25 mM, effectively counteracts the light‐induced ROS disruption. Taurine (25 mM) reduces labeled bicarbonate and tritiated water levels to those observed in the dark incuba

ISSN:0360-4012    

DOI:10.1002/jnr.490060309

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

年代:1981

数据来源: WILEY

摘要:

AbstractFibroblasts provide a source of living cells that can be obtained easily from humans and used to evaluate inherited differences in the activities of enzymes important in neurotransmitter and drug metabolism. Here, we describe biochemical characteristics of catechol‐O‐methyltransferase (COMT, EC 2.1.1.6) activity in homogenates of cultured human skin fibroblasts. Many properties of the enzyme, including apparent affinity for dihydroxybenzoic acid and Sadenosyl methionine, optimal pH and (Mg++), and inhibition by Ca++, are similar to those reported in lysates of human erythrocytes. Culture and assay conditions have been established for optimal and reproducible measurement of COMT activity in individual fibroblast lines. In 16 control lines, COMT activity ranged from 115 to 263 pmol/min/mg protein with a mean of 181 pmol/min/mg protein. Enzyme activity did not vary with the age or sex of the donor. The COMT activities in fibroblasts from eight patients with dystonia musculorum deformans, an inherited movement disorder of unknown etiology, were not significantly different from controls. Monoamine oxidase (MAO, EC 1.4.3.4) type A activity was measured in 12 lines from patients with dystonia, and values did not differ significantly from age‐ and sex‐matched controls. We conclude that inherited variation in activity of these two catabolic enzymes is not sufficient to explain alterations in monoamine metabolism described in this d

ISSN:0360-4012    

DOI:10.1002/jnr.490060310

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

年代:1981

数据来源: WILEY

摘要:

AbstractGangliosides are enriched in the nervous system compared to other tissues. The synthesis of gangliosides by monolayer cultures of isolated oligodendrocytes has not previously been investigated. Cells were labeled with [3H]galactose at preselected times and gangliosides isolated by phase partition, purified, and identified by chromatography. Cultured oligodendrocytes showed selectivity in their synthesis of gangliosides, which was expressed in the type of ganglioside synthesized as well as in the change of incorporation over time in culture. For the first ten days, there was very little incorporation of [3H]galactose in gangliosides, but this was followed by a stimulation of uptake for GM3, GM1/GD3, and GD1gangliosides, reaching a maximum after approximately 25–30 days in vitro. There was little incorporation into GM2or trisialogangliosides throughout the life of the cultures. Since oligodendrocytes synthesize extensive membranes during this period, one may speculate that the de novo‐synthesized gangliosides are used for membra

ISSN:0360-4012    

DOI:10.1002/jnr.490060311

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

年代:1981

数据来源: WILEY