轮状病毒腹泻患儿检测结果分析

目的:探讨轮状病毒感染与天气因素之间的关系,以指导临床采取合理的防治策略.方法:采用免疫胶体金法对1155例腹泻患儿进行轮状病毒检测;收集2005年到2007年的天气资料;分别分析轮状病毒阳性患儿人次与温度、湿度之间变化的规律.结果:501份标本轮状病毒阳性,6m-24m年龄段婴幼儿阳性检出率最高.每年秋季(第33周时)随着周平均气温缓慢下降患儿人次开始逐渐上升,到第41周患儿人数达到最高峰,之后回落,达高峰前几周湿度也略有下降,表明天气因素与轮状病毒的传播有密切的关系.结论:秋季周平均气温、相对湿度是影响轮状病毒传播流行的自然因素.     

Effects of capric acid on rumen methanogenesis and biohydrogenation of linoleic and α-linolenic acid

Capric acid (C10:0), a medium chain fatty acid, was evaluated for its anti-methanogenic activity and its potential to modify the rumen biohydrogenation of linoleic (C18:2n-6) and α-linolenic acids (C18:3n-3). A standard dairy concentrate (0.5 g), supplemented with sunflower oil (10 mg) and linseed oil (10 mg) and increasing doses of capric acid (0, 10, 20 and 30 mg), was incubated with mixed rumen contents and buffer (1 : 4 v/v) for 24 h. The methane inhibitory effect of capric acid was more pronounced at the highest (30 mg) dose compared to the medium (20 mg) (-85% v. -34%), whereas the lower dose (10 mg) did not reduce rumen methanogenesis. A 23% decrease in total short-chain fatty acid (SCFA) production was observed, accompanied by shifts towards increased butyrate at 20 mg and increased propionate at 30 mg of capric acid (P < 0.001). Capric acid linearly decreased the extent of biohydrogenation of C18:2n-6 and C18:3n-3, by up to 60% and 86%, respectively. This reduction was partially due to a lower extent of lipolysis when capric acid was supplemented. Capric acid at 20 and 30 mg completely inhibited the production of C18:0 (P < 0.001), resulting in an accumulation of biohydrogenation intermediates, mainly C18:1t10 + t11 and C18:2t11c15. In contrast to effects on rumen fermentation (methane production and proportions of SCFA), 30 mg of capric acid did not induce major changes in rumen biohydrogenation as compared to the medium (20 mg) dose. This study revealed the dual action of capric acid, being inhibitory to both methane production and biohydrogenation of C18:2n-6 and C18:3n-3.     

Design and study of peptide-based inhibitors of amylin cytotoxicity

The incidence of type II diabetes is on the increase each year and the World Health Organisation (WHO) predicts there to be over 360 million diabetic patients worldwide by the year 2030. Deposits consisting mainly of a small protein, called islet amyloid polypeptide (amylin), which aggregates into oligo-/polymeric beta sheet structures is responsible for cytoxicity to the pancreatic β-cells, thus inhibition of this process has been explored as a potential prevention or treatment. N-Methylated and non N-methylated peptides spanning the length of amylin_1–37 were synthesised and evaluated for their inhibition of full length amylin mediated cytoxicity to RIN-5F cells. The non N-methylated peptides were very effective in inhibiting the cytotoxicity while the N-methylated peptides were not. Both the N-methylated and non N-methylated versions of the 29-34 region were equally effective.     

遮荫对半夏叶片光合色素与保护酶活性的影响

对半夏进行不同程度遮荫处理,研究了其生长过程中叶组织的光合色素含量、叶绿素a/b值、保护酶体系(SOD、POD、CAT)活性和丙二醛(MDA)含量的变化及其生理特性.结果表明:不同处理的半夏在生长过程中,光合色素的含量呈先升后降的趋势;与全光照相比,遮荫处理的叶绿素含量较高,叶绿素a/b值较低,类胡萝卜素含量在生长发育中早期较低而后期较高;SOD、POD、CAT活性呈由低到高再降低的趋势,MDA含量持续升高;遮荫处理的SOD、POD活性和MDA含量均低于全光照处理,CAT活性则表现为先高于后低于全光照处理.适度的遮荫可以提高半夏叶绿素的含量,降低膜系统受到的伤害,改善半夏的倒苗状况,为半夏叶片的生长提供较好的环境.     

Tyr-716 in the platelet-derived growth factor beta-receptor kinase insert is involved in GRB2 binding and Ras activation.

Ligand stimulation of the platelet-derived growth factor (PDGF) beta-receptor leads to activation of its intrinsic tyrosine kinase and autophosphorylation of the intracellular part of the receptor. The autophosphorylated tyrosine residues mediate interactions with downstream signal transduction molecules and thereby initiate different signalling pathways. A pathway leading to activation of the GTP-binding protein Ras involves the adaptor molecule GRB2. Here we show that Tyr-716, a novel autophosphorylation site in the PDGF beta-receptor kinase insert, mediates direct binding of GRB2 in vitro and in vivo. In a panel of mutant PDGF beta-receptors, in which Tyr-716 and the previously known autophosphorylation sites were individually mutated, only PDGFR beta Y716F failed to bind GRB2. Furthermore, a synthetic phosphorylated peptide containing Tyr-716 bound GRB2, and this peptide specifically interrupted the interaction between GRB2 and the wild-type receptor. In addition, the Y716(P) peptide significantly decreased the amount of GTP bound to Ras in response to PDGF in permeabilized fibroblasts as well as in porcine aortic endothelial cells expressing transfected PDGF beta-receptors. The mutant PDGFR beta Y716F still mediated activation of mitogen-activated protein kinases and an increased DNA synthesis in response to PDGF, indicating that multiple signal transduction pathways transduce mitogenic signals from the activated PDGF beta-receptor.     

Purification of Proteins by the Use of Hydrophobic Zeolite Y

Hydrophobic zeolite Y can be used as a fast and efficient and inexpensive matrix in the purification of proteins from crude extracts. Preferably the zeolite can be used in the first purification step, replacing the commonly used precipitation techniques with (NH₄)₂SO₄ or ethanol. The time required for the zeolite prefractionation was a few hours compared to the much more time consuming precipitation procedure which demands centrifugation and subsequent dialysis. Proteins can be adsorbed on the zeolite either in order to remove undesired proteins or to be subsequently eluted from the zeolite in order to achieve purification and concentration. Removal of undesired proteins is exemplified by the purification of horseradish peroxidase from a crude extract. The zeolite procedure enhanced the specific activity five times and provided a yield similar to that which was obtained by the use of standard procedures, (NH₄)₂SO₄ fractionation and ion-exchange chromatography. Binding and subsequent elution of proteins from the zeolite is exemplified by the purification of monoclonal antibodies from hybridoma culture supernatants. Proteins were desorbed from the zeolite by the use of polyethylene glycol 600 and this procedure yielded a purification factor of 5.     

Ancestral origins of the Machado-Joseph disease mutation: a worldwide haplotype study

Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder originally described in families of Portuguese-Azorean ancestry. The cloning of the MJD1 gene allowed identification of the disease in many other populations, and MJD is now known to be the most common cause of dominant spinocerebellar ataxia. The hypothesis that its present world distribution could result from the spread of an original founder mutation has been raised, both at historical and molecular levels. In the present study, we tested this hypothesis by linkage-disequilibrium analysis of tightly linked polymorphisms and by haplotype comparison, in 249 families from different countries. We typed five microsatellite markers surrounding the MJD1 locus (D14S1015, D14S995, D14S973, D14S1016, and D14S977), and three intragenic single-base-pair polymorphisms (A(669)TG/G(669)TG, C(987)GG/G(987)GG, and TAA(1118)/TAC(1118)). The results show two different haplotypes, specific to the island of origin, in families of Azorean extraction. In families from mainland Portugal, both Azorean haplotypes can be found. The majority of the non-Portuguese families also share the same intragenic haplotype seen in the families coming from the island of Flores, but at least three other haplotypes were seen. These findings suggest two introductions of the mutation into the Portuguese population. Worldwide, the sharing of one intragenic haplotype by the majority of the families studied implies a founder mutation in MJD.     

High-performance liquid chromatography–tandem electrospray mass spectrometry for the determination of lidocaine and its metabolites in human plasma and urine

A sensitive, selective and accurate high-performance liquid chromatographic–tandem mass spectrometric assay was developed and validated for the determination of lidocaine and its metabolites 2,6-dimethylaniline (2,6-xylidine), monoethylglycinexylidide and glycinexylidide in human plasma and urine. A simple sample preparation technique was used for plasma samples. The plasma samples were ultrafiltered after acidification with phosphoric acid and the ultrafiltrate was directly injected into the LC system. For urine samples, solid-phase extraction discs (C₁₈) were used as sample preparation. The limit of quantification (LOQ) was improved by at least 10 times compared to the methods described in the literature. The LOQ was in the range 1.6–5 nmol/l for the studied compounds in plasma samples.     

纳米载药系统在肿瘤多药耐药中的应用

当今世界,肿瘤已经成为威胁人类健康的重大疾病。在肿瘤疾病中,化疗可控制肿瘤的生长和转移,增强放疗的疗效,是治疗肿瘤疾病的主要手段之一。而肿瘤多药耐药是影响化疗药物疗效、引起化疗失败的重要原因,影响肿瘤患者的治愈效果,降低生存率。如何提高化疗的疗效,延长肿瘤患者的寿命成为医学界的难题。纳米载药系统是生物医学领域研究的热点,相对于单一药物,纳米载药体现了许多优越性,具有良好的应用前景。纳米级颗粒更有利于药代动力学,这些纳米载药颗粒通过被动和主动的机制表现出在全身血液循环寿命延长,持续的药物释放动力,使其能更好的在肿瘤细胞中积累而发挥作用,提高化疗的疗效。本文综述了肿瘤多药耐药研究中主要的纳米载体以及它们在逆转多药耐药方面的应用,并展望载药系统的有更多更好的发展趋势。