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Jau-Cheng Liou Yun-Ching Cheng Kai-Hsiang Kang Yuan-Ping Chu Chen-Chung Yang Long-Sen Chang 《Toxicon》2004,43(3):341-346
In the present study, Xenopus nerve-muscle cultures were used to explore the functional roles of A chain (a phospholipase A(2) subunit) and B chain (a non-phospholipase A(2) subunit) of Bungarus multicinctus beta-bungarotoxin. It was found that beta-bungarotoxin induced an increment of the frequency of spontaneous synaptic currents (SSCs) in the nerve-muscle cultures. Modification of beta-bungarotoxin with pyridoxal-5'-phosphate or substitution of Ca(2+) with Ba(2+) in buffer abolished the phospholipase A(2) activity of beta-bungarotoxin and the facilitatory phase of SSC as well. Antibodies that were directed specifically against A chain or B chain effectively inhibited phospholipase A(2) activity, and as a consequence the SSC frequency was not greatly different from the control rate. These results suggest that both A and B chains are indispensable parts of beta-bungarotoxin for inducing the facilitation of SSC frequency with Xenopus nerve-muscle cultures. 相似文献
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Long-Sen Chang Pei-Fung Wu Jau-Cheng Liou Wen-Hsien Chiang-Lin Chen-Chung Yang 《Toxicon》2004,44(5):491-497
Notexin, a presynaptic phospholipase A2 (PLA2) neurotoxin isolated from Notechis scutatus scutatus venom, was inactivated by arginine-specific reagents, phenylglyoxal and 1,2-cyclohexanedione. Kinetic analyses of the modification reaction revealed that the inactivation of notexin followed pseudo-first order kinetics and the loss of PLA2 activity was correlated with the incorporation of one molecule of modification reagent per toxin molecule. However, the results of amino acid analysis and sequence determination revealed that two arginine residues at positions 43 and 79 of notexin were modified simultaneously. Modification of the arginine residues was accompanied with a decrease in the ability to inhibit the indirectly evoked contraction of chick biventer cervicis muscle and bind with synaptic membranes. The secondary structure of the toxin molecule did not significantly change after modification with phenylglyoxal as revealed by the CD spectra. The modified derivative retained its affinity for Ca2+, indicating that the modified arginine residues did not participate in Ca2+ -binding. Together with the notion that Arg-43 and Arg-79 of notexin are located in the proximity of its catalytic site and toxic site, respectively, our results suggest that modification of Arg-43 and Arg-79 should differently contribute to the observed decrease in the PLA2 activity and neurotoxic effect of notexin. 相似文献
26.
报告正常足月产、妊娠高血压综合征及过期妊娠时胎膜在光镜和电镜下的结构及变化特点。观察发现,妊娠高血压综合征时胎膜为缺氧所致的可复性病变,而过期妊娠之胎膜则为不可复性自身老化。胎膜广泛纤维化表明在妊娠高血压综合征和过期妊娠时易发生早破膜。此外,尚讨论了胎膜屏障存在的可能机制及明、暗细胞这一现象。 相似文献
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Mota HC; Vijayakumar S; Sibata C; Higgins PD; Thomas FJ; Saxton J; Weinstein M 《Radiology》1988,168(3):859-861
To determine the optimal width of a midline posterior spinal block (MPSB) (to avoid delivering too great a dose to the cord and too small a dose to adjacent tissue), the authors determined with magnetic resonance (MR) imaging normal ranges of cord depth and width and correlated them with film dosimetric data. In 59 randomly selected patients there was a wide range for both depth and width. The average depths of the anterior and posterior surfaces of the cord were 6.7 cm +/- 1.4 and 5.4 cm +/- 1.3, respectively. The average cord width was 1.6 cm +/- 0.4. Optimal cord block width as a function of cord width was determined for a 6-MV photon beam. The optimal cord block width at the surface (half-value layer [HVL] thickness = 6) varied from 1.5 to 3.0 cm for cord widths of 0.8-2.4 cm, which correspond to two standard deviations from the average. There was no significant dependence on depth of the cord. For optimal treatment outcome, the MPSB width may have to be determined for each patient individually. 相似文献
28.
目的:观察麝香保心丸(SXBXW)对内皮素-1(ET-1)诱导原代培养的人脐动脉血管平滑肌细胞(VSMCs)增殖作用的影响。方法:建立ET-1刺激原代培养人脐动脉VSMCs增殖的细胞模型,设对照组、ET-1组、ET-1+SXBXW0.25g/L组、ET-1+SXBXW0.5g/L组、ET-1+SXBXW1.0g/L组和ET-1+SXBXW2.0g/L组,采用MTT法测定ET-1和SXBXW对细胞增殖的影响;用台盼蓝拒染和乳酸脱氢酶检测方法观察不同浓度的SXBXW对VSMCs的毒性作用;用流式细胞术观察ET-1和SXBXW对VSMCs增殖周期的影响。结果:与对照组相比,ET-1可显著促进VSMCs的增殖,一定剂量的SXBXW能够有效地抑制ET-1诱导的VSMCs细胞增殖,呈剂量依赖性;SXBXW抑制细胞增殖,但对活细胞数目和乳酸脱氢酶释放量均没有影响,提示对VSMCs无毒性作用。ET-1能够刺激VSMCs从G1期进入S期,从而促进细胞增殖,而SXBXW能抑制这一作用。结论:SXBXW能够有效抑制ET-1诱导的VSMCs增殖作用,其作用机制可能与其抑制细胞周期从G1期进入S期有关。 相似文献
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A case of a 22-year-old woman with rare neurologic complications including encephalopathy and acute axonal sensorimotor polyneuropathy in the course of acute pancreatitis is reported. The encephalopathy emerged 3 weeks after the onset of the illness with complete remission being noted 1 week later. The polyneuropathy presented as quadriplegia and respiratory failure that required intubation and partially remitted gradually. There was no pancreatic lesion, no major pancreatic surgery, no sepsis, and no multiple organ failure, all of which had been proposed as the predisposing factors. Severe inflammatory response syndrome (SIRS) that developed during the clinical course of this patient might have induced these neurologic complications. 相似文献
30.
Tai-Cherng Liou Shee-Chan Lin Horng-Yuan Wang Wen-Hsiung Chang 《World journal of gastroenterology : WJG》2006,(19)
AIM: To define the optimal injection volume of epineph-rine with high efficacy for hemostasis and low complication rate in patients with actively bleeding ulcers. METHODS: This prospective, randomized, comparative trial was conducted in a medical center. A total of 228 patients with actively bleeding ulcers (spurting or oozing) were randomly assigned to three groups with 20, 30 and 40 mL endoscopic injections of an 1:10000 solution of epinephrine. The hemostatic effects and clinical outcomes were compared between the three groups. RESULTS: There were no significant differences in all background variables between the three groups. Initial hemostasis was achieved in 97.4%, 98.7% and 100% of patients respectively in the 20, 30 and 40 mL epinephrine groups. There were no significant differences in the rate of initial hemostasis between the three groups. The rate of peptic ulcer perforation was significantly higher in the 40 mL epinephrine group than in the 20 and 30 mL epinephrine groups (P < 0.05). The rate of recurrent bleeding was significantly higher in the 20 mL epinephrine group (20.3%) than in the 30 (5.3%) and 40 mL (2.8 %) epinephrine groups (P < 0.01). There were no significant differences in the rates of surgical intervention, the amount of transfusion requirements, the days of hospitalization, the deaths from bleeding and 30 d mortality between the three groups. The number of patients who developed epigastric pain due to endoscopic injection, was significantly higher in the 40 mL epinephrine group (51/76) than in the 20 (2/76) and 30 mL (5/76) epinephrine groups (P < 0.001). Significant elevation of systolic blood pressure after endoscopic injection was observed in the 40 mL epinephrine group (P < 0.01). Significant decreasing and normalization of pulse rates after endoscopic injections were observed in the 20 mL and 30 mL epinephrine groups (P < 0.01). CONCLUSION: Injection of 30 mL diluted epinephrine (1:10000) can effectively prevent recurrent bleeding with a low rate of complications. The optimal injection volume of epinephrine for endoscopic treatment of an actively bleeding ulcer (spurting or oozing) is 30 mL. 相似文献