Effect of electrical stimulation of leg muscles on physiological responses during arm-cranking exercise in healthy men

The purpose of this study was to investigate the hypothesis that changes in physiological responses during arm-cranking exercise using electrical stimulation of the leg muscles (ACE-ES) compared to arm-cranking exercise alone (ACE) in able-bodied subjects (ABS) are based on an increase in active muscle mass rather than the enhancing effect of the leg muscle pump. In ABS the sympathetic nervous system induced vasoconstriction and activity of the leg muscle pump are intact, therefore, a normal redistribution of blood takes place during exercise. Consequently, ES should have no additional effect on the redistribution of blood in these ABS during exercise and, thus, changes in physiological responses will be based on an increase in active muscle mass. A group of 11 ABS performed three maximal arm-cranking tests. In the first test peak power output (PO _peak) was determined. The other tests were both submaximal and maximal ACE, once with ACE-ES and once with ACE. The PO _peak was not significantly different between ACE-ES and ACE. Oxygen uptake (O₂) increased significantly during ACE-ES compared to ACE. Cardiac output (), stroke volume (SV), heart rate and ventilation were not significantly different during ACE-ES compared to ACE. Respiratory exchange ratios were significantly lower during ACE-ES compared to ACE at 60% PO _peak and at maximal exercise. In conclusion, ACE-ES caused significant increases in O₂ with a lack of elevation in and SV during submaximal and maximal exercise in ABS. The results of this study suggest that changes in physiological responses during ACE-ES are based on an increase in the active muscle mass rather than stimulation of the leg muscle pump. Accepted: 6 August 1996     

小鼠脊髓背根神经节细胞共培养中P物质神经元的形态学观察

小鼠脊髓－背根神经节细胞在体外共培养状态Ｐ物质神经元的形态在国内尚未见文献报道。我们利用体外培养及免疫细胞化学方法对Ｐ物质神经元的胞体及突起形态做了观察,发现背根神经节中Ｐ物质免疫反应阳性的胞体为圆形成近似圆形,胞体直径大约为２８μｍ,突起较长,可有多级分枝。脊髓细胞中Ｐ物质反应阳性胞体多为圆形或椭圆形,胞体直径大约为１３μｍ左右,其突起有单极、双极和多极。在这种共培养状态下,Ｐ物质阳性反应纤维均比较纤细,但有的少见膨体,有的则膨体多见     

大鼠脊髓心房利钠肽的基因表达

用地高辛配基标记的ＡＮＰｃＤＮＡ作为探针,与大鼠脊髓腰段切片原位杂交,观察到杂交反应阳性神经元主要分布于前角（ⅨⅧ层）,少数中间带（Ⅶ层）和后角基部（Ⅶ层）。脊髓中央管室管膜上皮呈弱阳性反应。结果提示脊髓前角神经元和中央管室管膜上皮存在着ＡＮＰｍＲＮＡ,能内源性合成ＡＮＰ。     

Herpes Simplex Virus 1-Mediated Transfer of Preproenkephalin A in Rat Dorsal Root Ganglia

Abstract: Recombinant herpes simplex virus-1 encoding the rat preproenkephalin A (HSVLatEnk₁) was generated for driving the expression of preproenkephalin A-derived peptides in dorsal root ganglia of rats in vivo. Three weeks after infection via the hind footpads, quantitative RT-PCR and in situ hybridization experiments showed a strong expression of preproenkephalin A mRNA in lumbar dorsal root ganglia. In addition, a 40–160% increase in radioimmunoassayable Met-enkephalin-like material concentrations was found in the dorsal spinal cord and dorsal root ganglia, respectively, at the lumbar level in HSVLatEnk₁-infected rats as compared with animals infected with β-galactosidase-encoding recombinant herpes simplex virus-1 or control rats. These data demonstrate the efficacy of the preproenkephalin A encoding vector and suggest that it should help in elucidating the role of Met-enkephalin-containing primary afferent fibers in pain transmission and/or control.     

Myelinated nerve cell perikaryon in mouse spinal cord

Summary In the thoracic cord (posterior horn region) of a wild mouse, we have observed a small nerve cell soma completely enveloped by a myelin sheath. The number of myelin lamellae varied between 7 and 12. In one place, the existence of an inner mesoperikaryon could also be shown. The significance of this fortuitous finding has not yet been explained.

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Zusammenfassung Im Thorakalmark (Hinterhornbereich) einer Wildmaus wurde ein kleines Nervenzellperikaryon beobachtet, das vollständig von einer Markscheide umhüllt war. Die Zahl der Markscheidenlamellen variierte zwischen 7 und 12. An einer Stelle konnte ein sogenanntes inneres Mesoperikaryon nachgewiesen werden. Die Bedeutung dieses zufällig erhobenen Befundes ist vorerst noch offen.

     

Synaptic junction development in the spinal cord of an amphibian embryo: An electron microscope study

Summary An electron microscopical study has been made of the cervical spinal cord of Xenopus laevis embryos, from the time that the neural tube closes until the larvae were hatched and could swim. Sections of the whole cord were searched for intercellular junctions during this period. Two nonsynaptic types were found, the first were widely distributed puncta adherentia, the second were rare and similar to gap junctions. Membrane specializations with synaptic vesicles were first found when the neural folds had fused; membrane-vesicle clusters which looked like the presynaptic half of a synaptic junction were present, together with synaptic junctions lacking any postsynaptic membrane thickening or cytoplasm density. About four hours later, mature synaptic junctions with full thickening of the postsynaptic membrane, dense cytoplasm and striated or dense material in the synaptic cleft were present. Presynaptic mitochondria, dense-cored and flattened vesicles, fibre to fibre and fibre to cell body synapses were present from the first, as were synapses onto very fine dendrites which might be filopodia from dendritic growth cones. Synaptogenesis may start with the accumulation of vesicles in dense cytoplasm near a thickened cell membrane; the postsynaptic element becomes associated with this membrane-vesicle cluster and matures by increasing cleft and cytoplasmic density, and by membrane thickening.     

An electron microscopic study of macroglia and microglia in the lateral funiculus of the developing spinal cord in the fetal monkey

Summary An electron-microscopic study has been made of the glial cells in the developing lateral funiculus of the cervical spinal cord in fetal rhesus monkeys. The various macroglial cell types, their precursor cells, and microglia are discussed in detail. An astrocytic lineage is proposed in which glioblasts present in the lateral funiculus give rise to astroblasts that then develop into mature astrocytes. Oligoblasts apparently migrate into the lateral funiculus as such and develop into active oligocytes. The active oligocytes become most predominant during the initial stages of myelinogenesis and are in direct continuity with developing myelin. The active oligocytes develop into mature oligocytes after myelination is completed. Microglia cells are present throughout development as three forms; resting microglia, globose microglia, and active microglia. The globose and active microglia predominates at specific times early in development when degeneration of apparent neuronal processes is taking place. The microglia cells are characterized by dense nuclear chromatin clumps, lipid inclusion bodies, dense vesicles, and, often, intracellular debris.Supported in part by a Parson Trust Endowment Research Grant at the University of South Dakota School of Medicine. The author gratefully acknowledges the help of Dr. Ronald DiGiacomo who was responsible for the surgery involved in the fetal deliveries.     

miR-32-5p-mediated Dusp5 downregulation contributes to neuropathic pain

Previous studies have demonstrated that microRNAs (miRNAs) play important roles in the pathogenesis of neuropathic pain. In the present study, we found that miR-32-5p was significantly upregulated in rats after spinal nerve ligation (SNL), specifically in the spinal microglia of rats with SNL. Functional assays showed that knockdown of miR-32-5p greatly suppressed mechanical allodynia and heat hyperalgesia, and decreased inflammatory cytokine (IL-1β, TNF-α and IL-6) protein expression in rats after SNL. Similarly, miR-32-5p knockdown alleviated cytokine production in lipopolysaccharide (LPS)-treated spinal microglial cells, whereas its overexpression had the opposite effect. Mechanistic investigations revealed Dual-specificity phosphatase 5 (Dusp5) as a direct target of miR-32-5p, which is involved in the miR-32-5p-mediated effects on neuropathic pain and neuroinflammation. We demonstrated for the first time that miR-32-5p promotes neuroinflammation and neuropathic pain development through regulation of Dusp5. Our findings highlight a novel contribution of miR-32-5p to the process of neuropathic pain, and suggest possibilities for the development of novel therapeutic options for neuropathic pain.     

江豚脊髓的研究

本文研究了江豚脊髓的形态和内部构造,首次报道鲸类脊髓灰质分层和神经核的对应关系,并发现在胸段8—13节 、腰尾段1一6节等白质的侧索中有特殊细胞群,以多极或小三角形细胞为多,也有少数棱形细胞,呈串珠状排列或散在分布,分别与背角I- Ⅴ层相联系,它们显示出与感觉传导系有关,作者认为应分别称之为胸外侧核和腰尾外倒核。