三种不同品系小鼠在肺肿瘤短期诱发试验中的敏感性比较

用不同剂量尿烷一次腹腔注射，对ＫＭ、ＢＡＬＢ／ｃ和Ａ／Ｊ系小鼠进行肺肿瘤短期诱导试验，以比较其敏感性，为环境化学物致癌性鉴定的实验条件提供依据。结果显示：以肺肿瘤发生率和平均发瘤数两项指数来衡量发瘤危险，Ａ／Ｊ系均在最低染毒剂量（２５ｍｇ／ｋｇ）即出现发瘤危险明显增高；ＫＭ系以发生率衡量时，１００ｍｇ／ｋｇ为发瘤危险增高的最低剂量，而以平均发瘤数衡量时，最低剂量为２００ｍｇ／ｋｇ；ＢＡＬＢ／ｃ系前     

Differential changes of nicotinic receptors in the ratbrain following ibotenic acid and 192-IgG saporin lesionsof the nucleus basalis magnocellularis

The basal forebrain cholinergic neurons are implicated in the pathogenesis ofneurodegenerative diseases including Alzheimer^fn2s disease (AD). The nicotinic acetylcholine receptors (nAChRs) have been found to besignificantly afflicted in AD. To study the underlying mechanisms for dysfunction of the basalforebrain cholinergic neurons development of suitable animal models is warranted. In this studywe investigated the effects of bilateral lesions of the nucleus basalis magnocellularis on nAChRs inthe rat brain using the cholinergic system selective immunotoxin 192-IgG saporin andnon-selective excitotoxin ibotenic acid. Changes in nAChRs were measured by ³H-cytisineand ³H-epibatidine, two ligands with different selectivity for nAChRs subtypes. Inthe parietal cortex of ibotenic acid lesioned rates, the choline acetyltransferase activity (ChAT)was decreased by 24% while no changes were detected in the frontal cortex or hippocampus.Similarly, a 40% decrease was observed in the number of nAChRs labelled by ³H-cytisine,but not by ³H-epibatidine, in the parietal cortex, while no changes were found in thefrontal cortex or hippocampus. Although the 192-IgG saporin induced lesions reduced the ChATactivity in the frontal cortex, parietal cortex and hippocampus by 77, 50 and 21%, respectively, nochanges were observed in the number of nAChRs as studied by ³H-cytisine or ³H-epibatidine. The results indicate a difference in vulnerability of the cortical nAChRsubtypes to experimental lesions of the nucleus basalis magnocellularis. The findings in this studysuggest that a major portion of the nAChRs might be located on non-cholinergic neurons in thebrain.     

吡那地尔对高血压心脏结构和功能重构的影响

在等降压剂量下吡那地尔和赖诺普利可使４月龄自发性高血压大鼠的血压下降６．０￣８．０ｋＰａ，并接近同种属正常血压大刀瓣血压水平。     

呼出气氢测定试验对飞行人员乳糖酶缺乏症的研究

对66名汉族飞行人员进行乳糖呼出气氢测定试验,乳糖吸收不良的发生率为83.3％,其中乳糖不耐受者占34.6％;与一般汉族人群无明显差别。对10名确定为中度以上乳糖吸收不良的飞行人员进行250ml鲜牛奶的试验结果,有50％呼出气氢含量在正常范围,并无一例出现胃肠道症状。提示较长期食用牛奶未能使乳糖酶缺乏状态发生改变,但每日食用适量牛奶属合理营养。     

Detection of T cells responsive to a vascular growth factor in rheumatoid arthritis

The primary lesion in rheumatoid arthritis (RA) is a destructive synovitis characterized by proliferation of endothelial cells, fibroblasts, and vascular smooth muscle cells, and with perivascular lymphocyte aggregates. A nonhematopoietic growth factor, acidic fibroblast growth factor (aFGF), may induce many of the biological features found in rheumatoid synovium, including T cell activation. To determine if aFGF-responsive T cells are increased in RA, we developed an assay to measure the frequency of peripheral blood T cells that are costimulated by aFGF. The data indicate that the frequency of aFGF-responsive T cells is increased in RA and may change with disease activity and treatment.     

Temporal variability of Cryptosporidium in the Chesapeake Bay

Although Cryptosporidium has been found worldwide in molluscan shellfish from waters contaminated with human and animal feces, little or no related environmental data have been obtained. In the present study, oysters ( Crassostrea virginica) were collected eight times over 3 years from seven sites in the Chesapeake Bay or its tributaries, with accompanying data on water temperature, salinity, rainfall, and streamflow. Oyster gill washings were examined by immunofluorescence microscopy for Cryptosporidium oocysts. Of 1,590 oysters collected, 19.6% had detectable oocysts. Of 53 collections, oocysts were detected 81% of the time. The time when the greatest percentage of oysters at most sites had detectable oocysts coincided with the time of greatest weekly and monthly rainfall, greatest streamflow into the Bay, and lowest water temperatures. In 28% of 53 collections, C. parvum genotypes 1 and 2 and C. baileyi were identified by PCR and gene sequencing. Oocyst infectivity was confirmed from 37.5% of 40 collections by initiating C. parvum genotype 2 infections in mice.     

Identification, characterization, and expression pattern of the chicken EKLF gene.

EKLF/KLF1 was the first of the Krüppel-like factors (KLFs) to be identified in mammals and plays an important role in primitive and definitive erythropoiesis. Here, we identify and characterize EKLF in the chicken (cEKLF). The predicted amino acid sequence of the zinc finger region of cEKLF is at least 87.7% similar to mammalian EKLF proteins and is 98.8% and 95% similar to the EKLF orthologues in Xenopus and zebrafish, respectively. During early embryonic development, cEKLF expression is seen in the posterior primitive streak, which gives rise to hematopoietic cells, and then in the blood islands and in circulating blood cells. cEKLF mRNA is expressed in blood cells but not in brain later in chicken embryonic development. cEKLF mRNA is increased in definitive compared with primitive erythropoiesis. The conserved sequence and expression pattern of cEKLF suggests that its function is similar to its orthologues in mammals, Xenopus, and zebrafish.     

cagA-Positive Helicobacter pylori Populations in China and The Netherlands Are Distinct

The aim of this research was to study whether and to what extent Chinese cagA-positive Helicobacter pylori isolates differ from those in The Netherlands. Analysis of random amplified polymorphic DNA (RAPD)-PCR-assessed DNA fingerprints of chromosomal DNA of 24 cagA-positive H. pylori isolates from Dutch (n = 12) and Chinese (n = 10) patients yielded the absence of clustering. Based on comparison of the sequence of a 243-nucleotide part of cagA, the Dutch (group I) and Chinese (group II) H. pylori isolates formed two separate branches with high confidence limits in the phylogenetic tree. These two clusters were not observed when the sequence of a 240-bp part of glmM was used in the comparison. The number of nonsynonymous substitutions was much higher in cagA than in glmM, indicating positive selection. The average levels of divergence of cagA at the nucleotide and protein levels between group I and II isolates were found to be high, 13.3 and 17.9%, respectively. Possibly, the pathogenicity island (PAI) that has been integrated into the chromosome of the ancestor of H. pylori now circulating in China contained a different cagA than the PAI that has been integrated into the chromosome of the ancestor of H. pylori now circulating in The Netherlands. We conclude that in China and The Netherlands, two distinct cagA-positive H. pylori populations are circulating.     

上颌窦窦口的形态观察及其临床意义

目的：为了指导鼻内窥镜下功能性上颌窦手术。方法：对６０个头部标本（男３４，女２６）１２０侧进行了上颌窦口及其毗邻结构的观察测量。结果：上颌窦鼻通道的鼻开口口径为平均３．８ｍｍ，上颌窦通道长度为５．６ｍｍ，鼻内开口到前鼻棘连线与鼻底平面夹角为４５．２°，前鼻棘至鼻内开口的距离为３７．０ｍｍ，下鼻甲前端至鼻内开口距离为１９．５ｍｍ，中鼻甲前端至鼻内开口距离为１４．６ｍｍ。结论：上颌窦窦口为管状通道，该处的病变可以导致窦腔炎症，可以进行内窥镜下窦口扩大术，术中应避免损伤眼眶及鼻泪管。     

Recombinant single-chain variable fragment antibodies directed against Clostridium difficile toxin B produced by use of an optimized phage display system

Recombinant antibody cloning and phage display technologies were used to produce single-chain antibodies (scFv) against Clostridium difficile toxin B. The starting material was the mouse B cell hybridoma line 5A8, which generates a monoclonal antibody against the toxin. The integrated cloning, screening, and phage display system of Krebber et al. (J. Immunol. Methods 201:35-55, 1997) allowed us to rapidly obtain toxin B-binding scFv sequences derived from the hybridoma cell line. The best candidate scFv sequences, based on preliminary enzyme-linked immunosorbent assay (ELISA) screening data were then subcloned into the compatible expression vector. Recombinant single-chain antibodies were expressed in Escherichia coli. A 29-kDa band was observed on polyacrylamide gel electrophoresis as predicted. The expressed product was characterized by immunoblotting and detection with an anti-FLAG antibody. The toxin B-binding function of the single-chain antibody was shown by a sandwich ELISA. The antibody was highly specific for toxin B and did not cross-react with material isolated from a toxin B-negative C. difficile strain. The sensitivity of the soluble single-chain antibody is significantly higher than the original monoclonal antibody based on ELISA data and could detect a minimum of 10 ng of toxin B/well. Competitive ELISAs established that the affinity of the 5A8 parent antibody and the best representative (clone 10) of the single-chain antibodies were similar and in the range of 10(-8) M. We propose that recombinant antibody technology is a rapid and effective approach to the development of the next generation of immunodiagnostic reagents.