The multifunctionality of FGF-2 in the adrenal medulla

 Chromaffin cells of the adrenal medulla and their tumor counterparts, the pheochromocytoma (PC12) cells, are well-established model systems in neurobiology. The development of sympathoadrenal progenitor cells to chromaffin cells can be studied with regard to developmental signals which trigger the differentiation. With regard to potential treatments of neurological disorders like Parkinson’s disease chromaffin cell grafting can be used as one therapeutical approach. The beneficial effect of chromaffin cell grafts is possibly not only related to the release of dopamine but may also be linked to the release of growth factors. One of the growth factors that is synthesized by chromaffin and PC12 cells is basic fibroblast growth factor (FGF-2). The experimental data available so far, are in agreement with different functional roles of FGF-2. This article summarizes the putative physiological functions of FGF-2 in the adrenal medulla. Three differential functional roles of FGF-2 are discussed: (1) as a differentiation factor for sympathoadrenal progenitor cells; (2) as a target-derived neurotrophic factor for preganglionic sympathetic neurons which innervate adrenal medullary cells; (3) as an auto-/paracrine factor in the adrenal medulla. Accepted: 21 August 1996     

活化血小板葡萄糖摄取及血小板膜整合素对其的影响

目的 :了解活化血小板葡萄糖摄取过程及血小板膜整合素对其影响 ,探讨整合素与血小板能量代谢的关系 ,旨在研究血小板能量代谢涉及的信号传导 ,并为目前临床应用血小板膜糖蛋白Ⅱb/Ⅲa(GPⅡb/Ⅲa)单抗抗血小板活化提供新的理论依据。方法 :用液态闪烁计数方法检测在血小板膜糖蛋白Ⅱb/Ⅲa单抗 10E5及血小板整合素αυβ3 单抗 6 0 9干预与否情况下凝血酶激活后血小板摄取氚标 2 脱氧葡萄糖 ([3 H]2 DG)率。结果 :在生理浓度范围内活化血小板 [3 H]2 DG摄取率较静息时明显升高 ,单抗 10E5可充分阻断活化血小板葡萄糖摄取 ,单抗 6 0 9可部分阻断。结论 :整合素家族单抗可抑制血小板激活后葡萄糖摄取 ,提示其可能参与血小板能量代谢信号传导过程 ,并可能以GPⅡb/Ⅲa为主     

异丙酚对布比卡因诱导的PC12细胞毒性的作用

目的 探讨异丙酚对布比卡因诱导的PC12细胞毒性的作用及其可能机制。方法PCI2细胞接种于96孔培养板中培养，随机分为4组：对照组、布比卡因组、异丙酚组和布比卡因＋异丙酚组，分别加入Hanks液、布比卡因（终浓度为0．03、0．06、0．09、0．12、0．15mmol／L）、异丙酚（终浓度为1、2,4、8mmol／L）以及同时加入布比卡因（终浓度为0．09mmol／L）和异丙酚（终浓度为1、2,4、8mmol／L）。培养24h时，采用二甲基噻唑二甲基四唑溴盐比色微量分析法测定各孔的细胞活力和上清液乳酸脱氢酶（LDH）的活性，应用流式细胞仪检测硫氧还蛋白-1（Trx-1）和硫氧还蛋白还原酶-1（TrxR-1）表达率。结果 与对照组比较，布比卡因组PC12细胞活力降低（P〈0．01），且呈浓度依赖性；异丙酚组PC12细胞活力差异无统计学意义（P〉0．05）。与布比卡因组的0．09mmol／L亚组比较，布比卡因＋异丙酚组的2—8mmol／L亚组PC12细胞活力增加（P〈0．05）。与对照组比较，布比卡因组和布比卡因＋异丙酚组LDH活性升高，Trx-1和TrxR-1表达率降低（P〈0．01）；与布比卡因组比较，异丙酚组和布比卡因＋异丙酚组LDH活性降低，Trx-1和TrxR-1表达率升高（P〈0．01）。结论 布比卡因对PC12细胞具有浓度依赖性的细胞毒性作用。异丙酚可通过保护内源性硫氧还蛋白系统减轻布比卡因诱导的PCI2细胞的毒性。     

双侧唇裂术后的唇部继发畸形

本文报告了35例双侧唇裂术后唇部继发畸形。这些畸形主要包括唇红缘不整齐、上唇中份厚度不足以及上唇过紧。Z 字成形、V-Y 推进和 Abbe 瓣法常用于矫正这类继发畸形。     

Interactions of γ-immunoglobulins with lipid mono- or bilayers and liposomes. Existence of two conformations of γ-immunoglobulins of different hydrophobicities

Interactions between rabbit-γ-immunoglobulins and model membranes (lipid monalayers, planar lipid bilayers, liposomes) have been investigated. No significant interaction was observed with immunoglobulins. However, immunoglobulins dialysed first vs aqueous buffer having pH 2 or 3 and then dialysed against pH 7 buffer presumably adopt a new conformation which allows their bindings to model membranes. This binding is hydrophobic and the immunoglobulin region interacting with the lipid acyl chains is probably located in the heavy chain, as suggested by labelling in this region by a photosensitive probe previously incorporated into the lipid hydrophobic core. Cleavage at the hinge region by papain or pepsin, or heating above 38°C, induces the loss of the hydrophobic conformation responsible for hydrophobic bindings. The binding capacity of immunoglobulins heated above 38°C is restored after momentary dialysis at pH 2. The possible existence of two Ig isomers is discussed in relation to the mechanism of γ-immunoglobulin passage through the endoplasmic membrane and fixation into the plasma membrane.     

p38MAPK参与高糖刺激大鼠肾小管上皮细胞产生细胞外基质胶原Ⅲ

目的：探讨p38MAPK信号通路在高糖刺激大鼠肾小管上皮细胞产生细胞外基质胶原Ⅲ中的作用。 方法： 采用体外培养和Western blotting等方法，以不同浓度D-葡萄糖、p38MAPK信号通路特异性阻断剂SB203580以及用不同时间刺激正常大鼠肾小管上皮细胞NRK52E，分别检NRK52E细胞p38MAPK磷酸化水平和细胞外基质胶原Ⅲ的表达。 结果： 随D-葡萄糖浓度增加，p38MAPK磷酸化水平、胶原Ⅲ的产生也增加，SB203580可有效阻断高糖引起p38MAPK磷酸化水平的升高和细胞外基质胶原Ⅲ的表达的增高。 结论： 高糖引起p38MAPK磷酸化水平的升高可能在糖尿病肾病的肾间质纤维化中发挥重要作用。SB203580有潜在的糖尿病肾病防治的临床应用价值。     

Induction of specific anti-actin antibodies and their measurement by ELISA technique.

Using the ELISA technique we have been able to quantify antibodies directed against actin and to follow the kinetics of antibody production. Specific anti-actin antisera have been raised in rabbits by immunization with chemically modified white muscle rabbit actin. Two or three dinitrophenyl groups linked per actin molecule were sufficient to break natural tolerance, while linkage of three phosphorylcholine groups to actin was not.     

Renewal of the membrane complex of Schistosoma mansoni is closely associated with lipid metabolism

Metabolic pathways leading to lipid biosynthesis in four different developmental stages of Schistosoma mansoni were explored and quantified by incubation in the presence of labeled precursors in a chemically defined medium. At the schistosomulum stage and in male, female, or paired worms, glycerol and oleate incorporation into neutral lipids, mainly in the form of triacylglycerols, was greater than into phospholipids, whereas in 11-and 15-day-old worms, synthesis mainly led to phospholipids. Incorporation into phospholipids was recovered largely in phosphatidylcholine, and distribution into other phospholipids depended on the developmental stage. Incorporation of choline and ethanolamine into their respective phospholipids represented up to 15% of the parasitic phospholipid content. The formation of phosphatidylcholine by phosphatidylethanolamine methylation occurred mainly in the immature parasitic stages. Inositol incorporation was also measurable, whereas [14C]serine incorporation was low or undetectable. Addition of 1-palmitoyl-2-[14C]oleyl phosphatidylcholine revealed a very high uptake of this phospholipid by the immature stages but further metabolism was not detectable. In contrast, adult S. mansoni were completely unable to take up or absorb this exogenous phospholipid. The most striking aspect of this study was the relatively high metabolic activity in 11-day-old worms and the lower but sustained activity on day 15 and at the schistosomulum stage. By comparison, biosynthetic activity in adult S. mansoni, on which research studies have been focused until now, was very low. We also discuss the participation of lipid metabolism in the constant renewal of the membrane complex which is essential to parasitism by S. mansoni.     

A rapidly inactivating Ca2+-dependent K+ current in pheochromocytoma cells (PC12) of the rat

The membrane electrical properties of undifferentiated pheochromocytoma cells of the rat (PC12) were studied using both current-and voltage-clamp techniques with the use of low-resistance blunt-tipped micropipettes (patch electrodes). In the presence of tetrodotoxin (TTX, 2–3 M), a spike-like wave form with a prominent after-hyperpolarization (AHP) was recorded following brief (< 10 ms) depolarizing current pulses. The inorganic divalent cations, Cd²⁺ (0.5 mM), Mn²⁺ (4mM), and 0 mM Ca²⁺/4 mM Mg²⁺ solution prolonged the duration, attenuated the AHP, slowed the rate of repolarization, and slightly enhanced the amplitude of this wave form. A rapidly inactivating outward current was recorded in over 70% of the cells under voltage-clamp conditions. This transient current was elicited at about ±30 mV, and was blocked by tetraethylammonium (5 mM), inorganic divalent cations (Cd²⁺, 0.5 mM; Mn²⁺, 4 mM; Ba²⁺, 3 mM), and removal of Ca²⁺ (0 mM Ca²⁺/4 mM Mg²⁺) from the local perfusion medium. In addition, 4-aminopyridine (5 mM), which blocks the transient outward K⁺ current I_A in a variety of excitable cells, did not have any appreciable effect on this rapidly inactivating current. Moreover, it was possible to elicit the current at a holding potential of ±40 mV. The reversal potential of this current was ±90 mV, and shifted positively when extracellular K⁺ concentrations were elevated. It is concluded that PC12 cells have a rapidly inactivating Ca²⁺ -dependent K⁺ current. A possible explanation for the transient nature of this current may be the presence of an effective intracellular Ca²⁺ buffering (uptake or extrusion) system.     

管花苷B对抗H2O2诱导的PC12细胞凋亡

目的：观察肉苁蓉提取物管花苷B对H₂O₂诱导的PC12细胞损伤的影响。方法：用MTT法检测细胞存活率，以激光共聚焦显微镜荧光染色法检测细胞内活性氧的产生和线粒体膜电位的变化，DNA琼脂糖凝胶电泳和流式细胞仪检测细胞凋亡的发生，并用荧光酶标仪测定caspase-3的活性。结果：100 μmol·L^-1 H₂O₂处理细胞24 h显著降低细胞的存活率；诱导细胞发生凋亡，凋亡率达48.0％；细胞内活性氧水平及caspase-3的活性显著升高；而线粒体膜电位却明显降低，红/绿荧光强度的比值由正常的5.97降低为0.41左右。而预先给予1、10或100 mg·L^-1浓度的管花苷B处理细胞12 h，可显著提高细胞存活率；并可有效抑制DNA ladder的发生；流式细胞仪检测凋亡率分别降低到30.9%、18.3%和6.2%；激光共聚焦显微镜结果显示管花苷B可明显降低细胞内活性氧的水平；并可逐渐恢复线粒体的高能量状态；caspase-3的活性不断降低，并呈现了一定的剂量依赖性。结论：管花苷B能显著地抑制H₂O₂诱导的PC12细胞凋亡，其神经细胞保护作用可能与其降低细胞内活性氧水平，维持线粒体膜电位的高能状态和抑制caspase-3的活性有关。