家兔脊髓蛛网膜下腔注射乙酰胆碱对血压和心率的影响

将乙酰胆碱(ACh)注入麻醉家兔脊髓蛛网膜下腔,观察其对心血管活动的影响。结果表明:(1)脊髓蛛网膜下腔注射50～100μg ACh可使血压下降,心率减慢;(2)预先由脊髓蛛网膜下腔注射阿托品,可阻断ACh引起的降压和降心率作用;(3)脊髓蛛网膜下腔注射六甲双铵、酚妥拉明或心得安均不能阻断上述ACh的心血管反应;(4)切断两侧颈部迷走神经,ACh不再使心率减慢,但其降低血压的作用不受到任何影响。 脊髓中ACh水平升高可通过激活胆碱能M-受体引起血压下降和心率减慢。ACh的这种降压作用既没有中枢肾上腺素能受体活动参与,也不是通过迷走神经实现的,可能是由于脊髓交感血管中枢紧张性降低所造成的。     

人参多肽基因的化学合成和克隆

 本文报道了具有降血糖作用的人参多肽基因的设计及用固相亚磷酰胺法的合成。再以质粒pUC19作为克隆载体,以大肠杆菌JM101为受体菌,克隆了人参多肽基因,并成功地获得了克隆菌株。     

长白山树舌水溶性色素多糖CF_1的分离纯化与结构研究

 从长白山树舌子实体中分离色素多糖,其均一性检查用Sepharose CL-4B柱层析、高压玻璃纤维纸电泳、醋酸纤维素薄膜电泳、超离心分析等方法,用凝胶层析测定的分子量为18.5万。 均一的脱色多糖(CF_1a)分子量为14万。用红外光谱,G.C,~1H-N.M.R,~(13)CN.M.R,高碘酸氧化与Smith降解,甲基化分析等确定其结构为葡聚糖,其基本结构可能如下式: 总色素用次氯酸氧化法测定为24％。在色素多糖中的色素可能是聚合形式。色 素经薄层层析、紫外吸收性质检查等表明可能是新黄酮类化合物。     

The acidic polysaccharide from Palmaria decipiens (Palmariales,Rhodophyta)

Palmaria decipiens, one of the most abundant red seaweeds of the chilean Antarctic, was collected in King George Island. The hot water extract (26% yield) showed by acid hydrolysis to contain xylose, galactose and traces of glucose. Fractionation with cetrimide gave a soluble neutral xylan and an insoluble fraction. The insoluble fraction afforded an acidic polysaccharide that contained 4.8% of uronic acids, 2.8% of sulfate and 18.9% of protein. Polyacrylamide gel electrophoresis showed that it was homogeneous. The GLC and HPLC analysis of the total acidic hydrolysis products showed that the acidic polysaccharide was composed of the neutral sugars galactose and xylose in the molar ratio 8.2:1.0 and of galacturonic and glucuronic acid in the ratio 1.5:1.0. The second-derivative FT-IR spectrum showed the characteristic amide I, II and III bands of proteins. Alkaline cleavage with 0.1 M NaOH indicated the presence of a glycoprotein with O-glycosidic linkage.Results found in this work suggest that the acidic polysaccharide extracted from Palmaria decipiens is an acidic xylogalactan-protein complex.     

Modulation of maize roots H+-ATPase by sulfated polysaccharides

Vesicles derived from maize roots retain a membrane bound H⁺-ATPase that is able to pump H⁺ at the expense of ATP hydrolysis. In this work it is shown that heparin, fucose-branched chondroitin sulfate and dextran sulfate 8000 promote a shift of the H⁺-ATPase optimum pH from 6.0 to 7.0. This shift is a result of a dual effect of the sulfated polysaccharides, inhibition at pH 6.0 and activation at pH 7.O. At pH 6.0 dextran 8000 promotes an increase of the apparent K_m for ATP from 0.28 to 0.95 mM and a decrease of the V_max from 14.5 to 7.1 mol P_i/mg · 30 min^–1. At pH 7.0 dextran 8000 promotes an increase in V_max from 6.7 to 11.7 mol Pi/mg · 30 min^–1. In the presence of lysophosphatidylcholine the inhibitory effect of the sulfated polysaccharides observed at pH 6.0 was not altered but the activation of pH 7.0 decreased. It was found that in the presence of sulfated polysaccharides the ATPase became highly sensitive to K⁺ and Na⁺. Both the inhibition at pH 6.0 and the activation promoted by the polysaccharide were antagonized by monovalent cations (K⁺>Na⁺Li⁺).Abbreviations Mops 4-morpholinopropanesulfonic acid - EDTA ethylenediaminetetraacetic acid - ACMA 9-amino-6-chloro-2-methoxyacridine - FCCP carbonyl cyanide p(trifluoromethoxy)-phenylhyrazone     

Toxicity to alveolar macrophages in rats following parenteral injection of mercuric chloride

Alveolar macrophages collected by pulmonary lavage from male Fisher-344 rats at intervals (24–72 h) after HgCl₂ injection (1–5 mg/kg, sc) were analyzed by several techniques. Within 24–72 h, the macrophages showed morphological signs of activation (hypertrophy and ruffled plasma membrane). Lipid peroxidation (increased malondialdehyde concentration) was not detected until 48 h. Dose- and time-related effects of HgCl₂ on malondialdehyde concentration and time-related effects of HgCl₂ on malondialdehyde concentration and mercury content of alveolar macrophages were observed 24–72 h postinjection. Diminished cell viability occurred only at 72 h after the highest dosage of HgCl₂. This study demonstrates that the alveolar macrophage was a cellular target for mercury toxicity following parenteral exposure to HgCl₂.     

罗伦隐球酵母胞外多糖的研究 Ⅰ.发酵条件

研究了罗伦隐球酵母(cryptococcus laurentii)产生胞外多糖的适宜条件。培养基组成(g/L):葡萄糖80.00,酵母膏1.25,KH_2PO_3.00,MgSO_4·7H_2O0.05,CaCO_3 10.00,pH6.0。在30℃,旋转式摇床(200r/min)上培养6天。胞外多糖产量最高可达17.38g/L,对底物的转化率为21.725％。     

伤寒Vi多糖菌苗接种反应观察

本文报告了对我国首次成功的伤寒Ｖｉ多糖菌苗进行人体接种反应观察结果,接种对象为２０至５４岁无伤寒病史,近年无伤寒菌苗接种史的健康人,共６０名,以完全随机的方法分为两组,实验组注射３０μｇＶｉ多糖菌苗,对照组注射Ｖｉ多糖菌苗的稀释液。其结果３０名Ｖｉ多糖菌苗接种者注射后体温无中重反应发生,局部红肿仅有１例中反应。注射后对血压、心律没有影响。红细胞计数,白细胞计数均在正常范围,与接种前相比,无显著差异     

艰难梭菌荚膜多糖单糖组成的气相色谱分析

本文对两株艰难梭菌（ＣｄＡ３１８和ＣｄＣＤＣ２７９）荚膜多糖进一步分析,结果证实纯化的艰难梭菌荚膜多糖为单一均匀的物质;经气相色谱分析表明,其单糖组分主要由Ｄ－葡萄糖、Ｄ－甘露糖和Ｄ－半乳糖组成,不同菌株的荚膜多糖可能有微小差异。     

Effects of medium carbon-to-nitrogen ratio on biofilm formation and plasmid stability

Biofilm formation and plasmid segregational instability in biofilm cultures of Escherichia coli DH5alpha (pMJR1750) were investigated under different medium-carbon-to-nitrogen (C/N) ratios. At C/N ratios of 0.07 and 1, net accumulation of both biofilm plasmid-bearing and plasmid-free cells continued through the entire experiment without attaining any apparent steady state. At C/N ratios of 5 and 10, net biofilm cell accumulation for the two populations reached apparent steady states after 84 and 72 h, respectively. At C/N ratios of 0.07 and 1, polysaccharide production increased slowly and reached about 2g alginate equivalent/cm(2) by the end of both experiments. At a C/N ratio of 5, polysaccharide increase significantly after 84 h, reaching about 7mug alginate equivalent/cm(2) prior to termination. At a C/N ratio of 10, polysaccharide increased significantly after 72 h and reached 21 mug alginate equivalent/cm(2) at 108 h. At C/N ratios of 0.07 and 1, protein production reached 6.5 and 4 mug/cm(2), respectively. At C/N ratios of 5 and 10, protein production increased slightly for the first 84 h and reached a maximum at 108 h, at 3 and 2 mug/cm(2), respectively, then decreased over the last 12 h of the experiment. Ratios of polysaccharide to protein increased with increasing C/N ratios. At C/N ratios of 0.07 and 1, the ratios between extracellular polysaccharide (EP) and protein were no more than 205 mug polysaccharide/mug protein, whereas those at C/N ratios of 5 and 10 increased to about 7 and 12 mug polysaccharide/mug protein, respectively.Probabilities of plasmid loss in the biofilm cultures increased with increasing C/N ratios. At C/N ratios of 0.07, 1, and 5, the probabilities of plasmid loss were 0.0013 +/- 0.011, 0.020 +/- 0.006 and 0.122 +/- 0.021, respectively. At a C/N ratio of 10, the probability of plasmid loss was significantly higher, reaching 0.38 +/- 0.125. The increase of probability of plasmid loss at higher C/N ratios results from competition between cell replication and extracellular polysaccharide production. (c) 1994 John Wiley & Sons, Inc.