Chromogranin A can act as a reversible processing enzyme inhibitor. Evidence from the inhibition of the IRCM-serine protease 1 cleavage of pro-enkephalin and ACTH at pairs of basic amino acids

Bovine parathyroid chromogranin A inhibits the cleavage of Z-Ala-Lys-Arg-AMC by either trypsin or IRCM-serine protease 1 (IRCM-SP1), a putative novel processing enzyme originally isolated from porcine pituitary anterior and neurointermediate lobes. On larger substrates, chromogranin A is a reversible competitive inhibitor of the cleavage at pairs of basic amino acids by IRCM-SP1. The substrates tested included pituitary ACTH and adrenal medulla pro-enkephalin-derived peptides such as the 8.6 kDa synenkephalin-containing precursor and peptide B. Chromogranin A is itself selectively processed by IRCM-SP1, and ACTH was shown to compete for such cleavage. These data suggest that chromogranins as a class of acidic proteins could participate in the tissue-specific processing of pro-hormones.     

通用流感疫苗研究进展

流感是一种对人类危害极大的传染病,接种疫苗被认为是预防流感的最有效手段。目前所用的流感疫苗主要是根据现行流行株的减毒或灭活病毒疫苗及基于流感血凝素和神经氨酸酶设计的重组蛋白质疫苗。但流感病毒变异大,易逃逸机体免疫监视,有效的疫苗须不断分离新流行株和不断更新疫苗免疫原。为解决这一问题,很多科学家一直在研究基于病毒高度保守性蛋白质、能够预防所有流感病毒毒株、可诱导持久保护性免疫的通用流感疫苗。我们对基于基质蛋白M2、核蛋白等的通用流感疫苗做一简要综述。     

复方斑蝥胶囊联合放疗治疗鼻咽癌的临床疗效分析

摘要目的：观察复方斑蝥胶囊联合放疗治疗鼻咽癌的临床效果及不良反应。方法：将2007年6月至2010年12月来我科就诊的120例Ⅱ、Ⅲ期低分化鳞状细胞鼻咽癌伴有颈淋巴结转移的患者随机分为复方斑蝥胶囊辅助放疗组、甘氨双唑钠辅助放疗组（阳性对照组）和单纯放疗组（阴性对照组）,每组各40例,比较治疗后各组患者的治疗效果和不良反应。结果：各组患者在接受相同放射疗程的情况下,复方盥蝥胶囊辅助放疗组和甘氨双唑钠辅助放疗组的治疗总有效率均明显优于单纯放疗组（P〈0．05）,但复方斑蝥胶囊辅助放疗组与甘氨双唑钠辅助放疗组比较无明显差异（P〉0．05）。复方斑蝥胶囊辅助放疗组皮肤反应的发生率明显低于单纯放疗组（P〈O．05）;皮肤反应、黏膜反应、口腔溃疡和心电图异常的发生率均明显低于甘氨双唑钠辅助放疗组（P〈O．05）,但两组恶心呕吐的发生率比较无明显差异（P〉0．05）。结论：复方斑蝥胶囊辅助治疗可显著提高放疗治疗鼻咽癌的临床疗效,且无明显毒副作用,值得临床推广应用。     

Elevation of plasma 7B2 (a novel pituitary protein) in cord blood at obstetrical delivery and the possible correlation with GH

Plasma 7B2-immunoreactivity (7B2-IR) concentrations in umbilical artery (UA), umbilical vein (UV) and maternal vein (MV) were measured by RIA at the time of obstetrical delivery at term. Plasma 7B2-IR concentrations (Mean +/- SEM) in UA (N = 12), UV (N = 16) and MV (N = 16) were 725 +/- 69, 699 +/- 64 and 116 +/- 4.5 pg/ml, respectively. Plasma 7B2-IR concentrations in UA and UV were much higher than those in MV. There was no arterio-venous gradient between UA and UV. A trace amount of 7B2-IR (Mean +/- SEM, 226 +/- 16.8 pg/g tissue) was detected in the placental extracts. A statistically significant positive correlation (r = 0.7595, p less than 0.005) was found between plasma 7B2-IR and GH in the UV. Significant negative correlations between body weight of the neonates and plasma levels of GH (r = -0.6836, p less than 0.01) and 7B2-IR (r = -0.4939, p less than 0.05) were also apparent. When analyzing cord blood plasma using gel permeation chromatography and SDS-polyacrylamide gel electrophoresis, a major peak with an apparent molecular weight of 20,000 was observed. These findings suggest that 7B2-IR in UA and UV originates from the fetus and that 7B2-IR does not permeate through the placenta. The possibility of involvement of 7B2 in fetal growth warrants attention.     

Root Growth, Secondary Root Formation and Root Gravitropism in Carotenoid-deficient Seedlings of Zea mays L.

The effect of ABA on root growth, secondary-root formation androot gravitropism in seedlings of Zea mays was investigatedby using Fluridone-treated seedlings and a viviparous mutant,both of which lack carotenoids and ABA. Primary roots of seedlingsgrown in the presence of Fluridone grew significantly slowerthan those of control (i.e. untreated) roots. Elongation ofFluridone-treated roots was inhibited significantly by the exogenousapplication of 1 mM ABA. Exogenous application of 1 µMand 1 nM ABA had either no effect or only a slight stimulatoryeffect on root elongation, depending on the method of application.The absence of ABA in Fluridone-treated plants was not an importantfactor in secondary-root formation in seedlings less than 9–10d old. However, ABA may suppress secondary-root formation inolder seedlings, since 11-d-old control seedlings had significantlyfewer secondary roots than Fluridone-treated seedlings. Rootsof Fluridone-treated and control seedlings were graviresponsive.Similar data were obtained for vp-9 mutants of Z. mays, whichare phenotypically identical to Fluridone-treated seedlings.These results indicate that ABA is necessary for neither secondary-rootformation nor for positive gravitropism by primary roots. Zea mays, gravitropism, carotenoid-deficient, Fluridone, root growth, vp-9 mutant     

The Effects of pH and Carbon Dioxide on Ion Uptake by Excised Barley Roots

The effects of carbon dioxide concentrations up to 8 per centin air on uptake of potassium and chloride at two pH levels,nominally pH 6 and 8, werestudied. In all experiments, enhanced uptake of potassium occurred atthe higher pH level with carbon dioxidefree air, but chlorideuptake was generally unaffected. At nominal pH 6, 1 per cent carbon dioxide reduced and 6 percent increased potassium uptake. There was no effect on chlorideuptake except with 1 per cent carbon dioxide where a markedenhancement was recorded. At nominal pH 8, l and 2 per cent carbon dioxide increased potassiumuptake whereas 6 and 8 per cent were inhibitory. Chloride uptakewas favoured by 1 and 8 per cent concentrations of the gas.     

Complete amino acid sequence of Shigella toxin B-chain. A novel polypeptide containing 69 amino acids and one disulfide bridge

The complete amino acid sequence of the B-chain of Shigella toxin has been determined using both liquid- and gas-phase sequenators. It reveals a 69-amino acid peptide with a single disulfide bridge, predicting a subunit molecular weight of 7691. No Asn-X-Ser(Thr) sequence was found, confirming the absence of potential N-glycosylation sites. A computer data bank search using a mutation data matrix did not detect any similarity greater than 30% with known sequences to date, indicating a novel primary structure. However, some distant homology with the 103-residue B-chain of cholera and Escherichia coli enterotoxins was revealed. Hydropathy, fractional exposure, and Chou and Fasman calculations all point to an ordered structure with a hydrophobic core spanning residues 36-52 and a hydrophilic domain between residues 10 and 20, the latter probably representing the most antigenic domain.     

THE TOXIC EFFECTS OF TRIALKYLTIN COMPOUNDS ON NERVE AND MUSCLE

The toxicity of trimethyltin chloride and triethyltin sulphate on animal tissues was assessed by their effects on isolated phrenic nerve-diaphragm preparations. Studies by electron microscopy show that the inhibitory effects of these compounds on the muscular contractility of this tissue are associated with (a) the disruption of mitochondria and disorganisation of muscle fibres and (b) the depletion of neuromicrotubules in the axons of nerves innervating the muscle. The neurotoxie effect of triethyltin sulphate on neuromicrotubules is further substantiated by its inhibition (in a concentration-dependent manner) of the specific colchicine-binding activity of the crude and purified tubulin preparations derived from brain tissue. In addition, both triethyltin sulphate and trimethyltin chloride at a concentration greater than 100 μM completely prevent the normal in vitro assembly of microtubules from tubulin.     

CpG联合铝佐剂对HCV免疫原体液免疫作用的影响

目的:探讨胞苷酸鸟苷寡脱氧核苷酸(CpG ODN)联合铝佐剂对丙型肝炎病毒(HCV)重组免疫原的体液免疫作用。方法:采用高交叉HCV-HVR1和E1重组蛋白与CpG ODN、铝佐剂组合,免疫BALB/c小鼠后以ELISA、酶联免疫斑点测定、流式细胞术、免疫沉淀等方法检测相关体液免疫指标和免疫血清多抗的交叉反应性。结果:CpG联合铝佐剂激发了最高的特异性抗体滴度;佐剂通过提高抗体分泌细胞数量、增加脾脏中记忆B细胞数量、增加脾淋巴细胞IL-6、IL-10分泌浓度实现体液免疫增效;CpG则能提高免疫效率,联合铝佐剂时显著提高浆细胞数量;12份HCV阳性血清中有10份可与多抗HVR1 IgG发生免疫沉淀。结论:CpG和铝佐剂联合应用具有协同作用,多抗HVR1 IgG具有较好的交叉反应性。     

Biosynthesis of polypeptide hormones

The biosynthesis of numerous polypeptide hormones implicates two types of precursors: pre- and prohormones. The structure, characteristics, and role of these hormone precursors is discussed taking as examples parathyroid hormone and insulin. After this general introduction, the case of the common precursor for adrenocorticotropin and beta-lipotropin is then discussed. Its maturation proceeds through a serie of proteolytic steps which lead to the formation of various end products characterized each by a biological activity of its own.