Cultured myotubes from skeletal muscle of adult rats

Summary Mononucleated myogenic cells (satellite cells) were isolated from skeletal muscle of adult rats and grown in culture. These cells replicated and, beginning with the 6th day in culture, they fused and differentiated into multinucleated myotubes, which accumulated creatine kinase and developed cross striation and spontaneous contractions. The differentiation of the excitable membrane and the action of sea anemone toxin ATX II were investigated with microelectrode techniques. Mature myotubes reached a stable membrane potential of –47.3 mV (±6.5 mV) with the IIth day in culture. Action potentials could be generated in all myotubes. During maturation they became faster (increasing rate of rise) and shorter in duration. In spontaneously contracting myotubes spontaneous action potentials were recorded, which were often associated with subthreshold oscillations of membrane potential. ATX II reduced the membrane potential and prolonged the action potential duration with the lowest effective concentrations being 1 nmol/l and 0.5 nmol/l, respectively. Furthermore, ATX II induced electrical activity in quiescent myotubes. After fusion the development of the membrane electrical properties of satellite cell derived muscle cells followed essentially the same pattern as in primary cultures of embryonic myotubes. Electrophysiologically and with respect to their sensitivity to ATX II the mature myotubes resemble denervated muscle fibres. Send offprint requests to I. Tesseraux at the above address     

体外培育牛黄与天然牛黄指纹图谱的比较研究

目的：研究、比较体外培育牛黄与天然牛黄的指纹图谱。方法：利用TOFMS、HPIEJMS技术研究、比较体外培育牛黄与天然牛黄中肽类、胆汁酸类和胆红素类3类成分的指纹图谱。结果：体外培育牛黄与天然牛黄3类成分的指纹基本一致，但各成分间的相对含量有差异。结论：10批体外培育牛黄的指纹图谱有较好的一致性，说明体外培育牛黄的质量稳定。4批天然牛黄的指纹图谱，尤其是胆汁酸类成分的指纹图谱差异明显，说明天然牛黄由于来源不同，导致质量不够稳定.     

南柴胡提取物对小鼠脾细胞体外增殖和淋巴因子分泌水平的影响

目的：探讨南柴胡水提取物和正丁醇提取物对小鼠淋巴细胞体外增殖和分泌白细胞介素－2（IL－2）与肿瘤坏死因（TNF－β）的影响。方法：向小鼠脾细胞加入Con 4和南柴胡的水与正丁醇提取物进行培养,以MTT法检测淋巴细胞增殖反应,用ELISA法测定IL－2与TNF－β分泌水平。结果：南柴胡水提取物能增强ConA诱导的小鼠脾细胞的体外增殖和分泌IL－2与TNF－β的水平,南柴胡的正丁醇提取物可增强IL－2分泌水平。结论：南柴胡的水与正丁醇提取物对小鼠淋巴细胞活性有增强作用。     

Protective effects of epigallocatechin gallate after UV irradiation of cultured human lens epithelial cells

PURPOSE: To evaluate the protective effects of epigallocatechin gallate (EGCG) against UV irradiation of cultured human lens epithelial cells. METHODS: We irradiated cultured human lens epithelial cells with a 30-second pulse from a UV lamp with an irradiance of 0.6 mW/cm(2). Five minutes and 1 hour after UV irradiation, we administered 0, 5, 10, 15, 25, 50, or 100 uM EGCG. The cell number was measured with a microscopic counting chamber and cell viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. RESULTS: Compared to untreated cells, the total number of cultured human lens epithelial cells was markedly higher after UV irradiation. In a dose-dependent manner, viability was also higher in EGCG-treated cells. CONCLUSIONS: EGCG increased the cell count and cell viability after UV irradiation of cultured human lens epithelial cells, indicating that EGCG can protect lens epithelium against UV damage.     

Protective Effect of Nifedipine Against Cytotoxicity and Intracellular Calcium Alterations Induced by Acetaminophen in Rat Hepatocyte Cultures

ABSTRACT

Alteration of calcium homeostasis has been proposed to play a major role in cell necrosis induced by a variety of chemical agents such as acetaminophen (APAP). In this study, a potential protective effect of the dihydropyridine calcium channel blocking agent, nifedipine, was investigated in vitro on acetaminophen-induced hepatocyte damage. Rat hepatocytes were exposed during 20 hours to various concentrations of APAP (0.50 to 4.00 mM). The following metabolic and functional parameters were investigated : - lactate dehydrogenase (LDH) release as an indicator of plasma membrane integrity, - cell viability evaluated by the colorimetric MTT assay, and intracellular calcium concentration as evaluated by two fluorimetric methods : a scanning laser cytometer using indo-1-AM as fluorescent probe and a fluorescence plate reader using fluo-3-AM as calcium indicator.

Incubation of hepatocytes with APAP alone in the range 0.50 to 4.00mM resulted in a dose-response relationship with regard to LDH release (243% to 750% of control) and to the loss of cell viability (0 to 67% of control). Moreover these results were correlated with a significant increase in cytosolic calcium content (189 to 406 nM).

Nifedipine treatment prior to APAP exposure, partially prevented LDH release, the plasma membrane blebbing, and thereby the loss of viability. In addition, intracellular calcium level progressively returned within the limits of the control values with increasing concentrations of nifedipine.

It can be concluded that, in in vitro conditions, nifedipine pretreatment exhibits a preventive effect against acetaminophen hepatocyte injury.     

Allosteric positive interaction of thymol with the GABAA receptor in primary cultures of mouse cortical neurons

Thymol is a naturally occurring phenolic monoterpene known for its anti-microbial and anti-oxidant properties. It is used in dental practice and in anaesthetic halothane preparations. Recent studies have reported enhanced GABA(A) receptor-operated chloride channel activity and increased binding affinity of [(3)H]flunitrazepam in the presence of thymol. In the present work, we more closely examined the pharmacological action of thymol on the native GABA(A) receptor by using primary cultures of cortical neurons. Thymol enhanced GABA-induced (5 microM) chloride influx at concentrations lower than those exhibiting direct activity in the absence of GABA (EC(50) = 12 microM and 135 microM, respectively). This direct effect was inhibited by competitive and non-competitive GABA(A) receptor antagonists. Thymol increased [(3)H]flunitrazepam binding (EC(50) = 131 microM) and showed a tendency to increase [(3)H]muscimol binding. These results confirm that thymol is a positive allosteric modulator of the GABA(A) receptor. The thymol structural analogues menthol and cymene, which lack an aromatic ring or a hydroxyl group, did not affect [(3)H]flunitrazepam binding. Using a pharmacophoric model that includes a hydrogen bond donor group as well as an aromatic ring with two aliphatic substituents, we propose to demonstrate the molecular essential features of these compounds to interact with GABA(A) receptors. Thymol (0-1 mM) did not affect cellular viability.     

造血生长因子对长期培养中骨髓造血细胞增殖和分化的影响

应用骨髓长期培养法研究了ＨＧＦｓ联合应用对ＬＴＢＭＣ中造血干／祖细胞的增殖、分化的影响，结果显示，在ＬＴＢＭＣ中，含有ＨＧＦｓ（ＩＬ－２＋ＩＬ－６＋Ｇ－ＣＳＦ＋ＧＭ－ＣＳＦ＋Ｅｐｏ）的扩增组与对照组相比，ＨＧＦｓ能显著地扩增ＨＳＣｓ，在第一周，ＣＦＵ－ＧＭ，ＣＦＵ－Ｅ和ＢＦＵ－Ｅ总数分别扩增１８．０９－１６．５９倍、１０．２６－８．４８和１４．９９－１２．７８倍，而累积扩增倍数分别达３６．１９－６     

Cellular mechanism of action of resiniferatoxin: a potent sensory neuron excitotoxin

The mechanism of activation of sensory neurons by the potent irritant resiniferatoxin (RTX) was compared with that of the pungent compound, capsaicin. RTX and capsaicin evoked an inward, depolarising current associated with an increase in membrane conductance in a subpopulation of dissociated cultured neurons from rat dorsal root ganglia. RTX also evoked an uptake of⁴⁵Ca into and an efflux of [¹⁴C]guanidinium and of⁸⁶Rb from these cells but was at least 100-fold potent than capsaicin. The levels of cGMP, but not cAMP were elevated by RTX. Prolonged exposure to RTX damaged DRG neurons by a predominantly osmotic process. RTX-sensitive cells were identified by a cobalt-staining method; neurofilament-containing DRG neurons were RTX-insensitive as were all sympathetic neurons and non-neuronal cells. Cultured DRG neurons from chick embryos were also unaffected by RTX. In a neonatal rat spinal cord-tail preparation in vitro, RTX activated capsaicin-sensitive peripheral noiciceptive fibres and caused a subsequent spinal cord depolarization measured in the ventral spinal roots. Neither prolonged exposure to a phorbol ester, to desensitize/down-regulate protein kinase C, nor inhibition of protein kinase C by staurosporine affected responses produced by RTX or capsaicin. The effects of capsaicin were abolished when preparations were exposed to desensitizing concentrations of RTX. RTX therefore acts as a highly potent capsaicin analogue to activate a subpopulation of rat sensory neurons.     

缺血性脑血管病患者骨髓间充质干细胞的实验研究

目的：观察缺血性脑血管病患者骨髓间充质干细胞形态学特征。方法：将缺血性脑血管病患者自体骨髓中的阃充质干细胞（bone marrow mesenchymal stem cells，BM—MSCs）经密度梯度离心法分离、纯化和培养，观察原代和传代细胞的形态。结果：原代培养的BM—MSCs最佳贴壁时间为3d，生长性状不一，呈散在圆形细胞群、散在梭形细胞群、克隆圆形细胞群、花带状细胞群、漩涡状细胞群，而传代培养的细胞，增殖速度较快，性状一致，排列规则，呈饱满的梭行。结论：通过体外非诱导培养获得的自体BM—MSCs，有较强的增殖能力和多向分化潜能，为缺血性脑血管病的临床治疗提供了实验依据。     

肿瘤坏死因子对人甲状腺细胞分泌功能的影响

将正常人甲状腺组织行单层细胞培养后分为两组，Ａ组内加定量ｂＴＳＨ（１ｍＵ／Ｌ）和不同浓度肿瘤坏死因子，Ｂ级内仅加ＴＮＦ。培养２４和４８小时，分别测定上清液甲状腺球蛋白含量。结果：Ａ组ＴＧ含量随ＴＮＦ浓度增加而明显减少，提示ＴＮＦ可阻断ＴＳＨ对甲状腺细胞的刺激作用；Ｂ组ＴＧ含量则不受ＴＮＦ影响，说明ＴＮＦ对甲状腺细胞无直接杀作用。正常甲状腺功能的病态综合征患者血ＴＮＦ浓度明显高，可能是导致Ｔ３和Ｔ４