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.     

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。     

神经生长因子诱导后的交感神经元样PC12细胞与新生大鼠心肌细胞共培养的实验研究

探讨神经生长因子(NGF)诱导的交感神经元样PC12细胞作为体外再造心肌神经支配研究模型的可行性。用含0.04?TA的0.25%胰酶分离新生大鼠原代心肌细胞,然后与NGF诱导的交感神经元样PC12细胞共培养,通过光学显微镜观察、常规H.E.染色、激光共聚焦显微镜和扫描电镜观察等对其进行评价。结果表明:在二维共培养模型中,NGF诱导的交感神经元样PC12细胞长出神经突起,突起及其上的膨体能够到达跳动的心肌细胞表面,神经突起随心肌细胞一起跳动。采用神经元样PC12细胞作为体外再造心肌神经支配研究模型是可行的,神经细胞与心肌细胞可能存在支配关系。     

Major phospholipids and phosphatidylcholine synthesis in adult Schistosoma mansoni

The major phospholipids present in the phospholipid extract of Schistosoma mansoni were phosphatidylcholine (28%), phosphatidylethanolamine (25%), phosphatidylserine (15%) and phosphatidylglycerol (8%). The synthesis of phosphatidylcholine in S. mansoni adults occurred by the choline to phosphatidylcholine or Kennedy pathway. Incorporation of CDPcholine and choline into the phosphatidylcholine of worm slices appeared linear over time with no demonstrable sex differences in choline incorporation. A slight difference in the incorporation of CDPcholine by separate sexes was evident. Methylation of phosphatidylethanolamine to phosphatidylcholine could not be demonstrated.     

Detection of a trigger zone of bradykinin-induced fast calcium waves in PC12 neurites

 Bradykinin and caffeine were used as two different agonists to study inositol 1,4,5-trisphosphate (IP₃)-sensitive and caffeine/ryanodine-sensitive intracellular Ca²⁺ release in the outgrowing neurites of nerve-growth-factor (NGF)-treated rat phaeochromocytoma cells (PC12). Changes in neuritic intracellular free Ca²⁺ ([Ca²⁺]_i) in single cells were measured after loading with a 1:1 mixture of the acetoxymethyl (AM) ester of the Ca²⁺-sensitive dyes Fura-red and Fluo-3, in combination with confocal microscopy. Bradykinin-induced Ca²⁺ release was blocked by U73211, a specific phospholipase C inhibitor. Caffeine-induced Ca²⁺ release was very low in neurites at rest. It increased after the cells were preloaded with Ca²⁺. The Ca²⁺ signal evoked at high concentrations of bradykinin (>500 nM) arose from a trigger zone in the proximal part of the neurite, as a bi-directional wave towards the growth cone and cell body. The speed of neuritic Ca²⁺ waves was reduced in cells loaded with the Ca²⁺ chelator 1,2-bis(2-aminophenoxy)ethane-tetraacetic acid/AM. Preloading of Ca²⁺ stores led to increased bradykinin-induced Ca²⁺ release, as seen for caffeine, and faster Ca²⁺ wave speeds. Caffeine evoked a simultaneous [Ca²⁺]_i rise along the neurites of Ca²⁺ preloaded cells. Higher Ca²⁺ signal amplitudes and faster Ca²⁺ wave speeds, but no longer-lasting IP₃-induced [Ca²⁺]_i signals, correlated with increased caffeine-induced Ca²⁺ release in the neurites. At low concentrations of bradykinin (<1.0 nM), the Ca²⁺ signals ceased to propagate as complete Ca²⁺ waves. Instead, repetitive stochastic Ca²⁺ release events (neuritic Ca²⁺ puffs) were observed. Neuritic Ca²⁺ puffs spread across only a few microns, at a slower speed than neuritic Ca²⁺ waves. These Ca²⁺ puffs represent elementary Ca²⁺ release units, whereby the released Ca²⁺ ions form these elementary events into the shape of a Ca²⁺ wave. Received: 16 April 1996 / Received after revision and accepted: 13 May 1996     

Doxorubicin, an RNA synthesis inhibitor, prevents vasoconstriction and inhibits aberrant expression of endothelin-1 in the cerebral vasospasm model of the rat

The present study investigates the effects of bis(7)-tacrine, a novel dimeric acetylcholinesterase inhibitor, on hydrogen peroxide(H₂O₂)-induced cell injury with comparison to the corresponding monomer, tacrine. Exposure of rat pheochromocytoma line PC12 cells to H₂O₂ induced significant cell damage. This reagent also caused redox desequilibrium as indicated by a decrease in activities of intracellular antioxidant enzymes such as glutathione peroxidase as well as catalase and an accumulation of malondialdehyde, a product of lipid peroxidation. Pretreatment of cells with bis(7)-tacrine or tacrine attenuated H₂O₂-induced cell toxicity, and bis(7)-tacrine demonstrated higher potency than tacrine in improving redox desequilibrium. These results suggest that bis(7)-tacrine and tacrine significantly protect against H₂O₂ insult, which might be beneficial for their potential usage in the prevention and treatment of Alzheimer's disease.