白细胞介素及肿瘤坏死因子基因超家族在先兆子痫胎盘中的表达

为探讨白细胞介素和肿瘤坏死因子 (受体 )超家族基因表达与先兆子痫病理发生的关系 ,以包含 2 4 3种人类细胞因子相关基因cDNA片段的基因芯片 ,检测严格配对的先兆子痫和正常胎盘组织中基因表达谱的差异。结果显示受检的白细胞介素和 (或 )白细胞介素受体基因共 2 2种 ,绝大多数基因在先兆子痫胎盘中的表达增强 ,而IL 2受体 (IL 2Rα )基因 (Gen Bank :X0 10 5 7)在先兆子痫胎盘中的表达低于正常胎盘。肿瘤坏死因子 (GenBank :X0 2 910 )及其配体 (GenBank :U0 3398、U375 18、AF0 5 3712、AF0 5 5 872 )、受体 (GenBank :X6 0 5 92、X6 3717、M835 5 4、AF0 16 2 6 6、AF0 16 2 6 7、U812 32 )等 10余种肿瘤坏死因子 (受体 )超家族基因在先兆子痫胎盘中的表达也较高。说明 ,白细胞介素及肿瘤坏死因子 (受体 )基因超家族的高表达可能与先兆子痫的病理发生关系密切     

兔肾缺血再灌注损伤时TNF-α、IL-6和bFGF的变化及当归的影响

目的:探讨当归对兔肾缺血再灌注损伤的防治作用及其机制。方法:健康成年日本大耳白兔25只, 随机均分为假手术对照(control)组、单纯缺血再灌注(IR)组和缺血再灌注+当归(RAS+IR)组。在肾缺血1h再灌注48h后取肾组织作电镜检查, 并测血清肌酐(Cr)、肾组织肿瘤坏死因子(TNF-α)、白细胞介素-6(IL-6)和碱性成纤维细胞生长因子(bFGF)含量。结果:IR组肾组织变性改变显著, RAS+IR组病变轻微;IR组Cr、TNF-α和IL-6含量显著高于control组(P<0.05, P<0.05和P<0.01);RAS+IR组上述指标显著低于IR组。IR组bFGF含量显著低于control组(P<0.01), RAS+IR组bFGF含量显著高于IR组(P<0.01)和control组(P<0.05).结论:当归具有防治肾IR损伤的作用, 其机制可能与其对TNF-α、IL-6和bFGF等细胞因子的调控有关。     

Recirculating and germinal center B cells differentiate into cells responsive to polysaccharide antigens

Antibodies against bacterial capsular polysaccharides play a critical protective role. Responses to these antigens can occur without the help or control of T cells and are associated with marginal zone (MZ) B cells. Capsular antigens are diverse and some cross-react with self-carbohydrate epitopes. This diversity may explain the recruitment of non-autoreactive recirculating B cells and memory B cells to the MZ in addition to other B cells, some of which are weakly autoreactive cells, that are recruited to the MZ without entering the recirculating pool. To test whether memory B cells respond to polysaccharide-based antigens, mice with hapten-specific memory B cells were challenged with hapten-polysaccharide. Hapten-specific plasma cells producing high affinity antibody with Ig V-region mutations were induced. To test whether naive recirculating B cells can form MZ cells that respond to polysaccharide, recirculating B cells from lymph nodes were transferred into Rag-1-deficient mice. MZ cells differentiated from the donor cells without proliferation or T cell help and responded to polysaccharide-based antigen. The differentiation of B cells both from germinal centers and the recirculating pool to the MZ phenotype is likely to make an important contribution to the repertoire of B cells that respond to polysaccharide antigens.     

Mechanisms of enhanced prevalence of asthma and atopy in developed countries

Atopy — a T helper 2 cell driven hypersensitivity to innocuous antigens (allergens) which causes most cases of asthma — is of complex genetic and environmental origins. There is compelling epidemiological evidence for a rise in atopic disease in ‘westernised’ communities. The changing pattern of microbial exposure in early childhood is suggested to be the principal candidate mechanism for this rise.     

The effect of yoghurt on the cytotoxic and phagocytic activity of macrophages in tumour‐bearing mice

In a previous paper, it was demonstrated that feeding yoghurt was able to inhibit the growth of an intestinal tumour induced chemically with 1,2‐dimethylhydrazine (DMH). This effect was due to the increase in IgA‐producing cells and a diminution of the inflammatory immune response. In this paper the phagocytic and cytotoxic capacity of macrophages both involved and not involved in the target organ are studied. The study was aimed at determining whether in the intestinal tumour inhibition demonstrated previously the systemic immune response was also increased. The cytotoxic capacity and ß‐glucuronidase enzyme levels of the peritoneal macrophages were analyzed together with the cytolytic effect of the serum on tumour cells and the phagocytic activity of the macrophages infiltrating the intestinal mucosa. Groups of mice were split into three experimental groups. One group was treated with DMH. The others were treated with DMH, and their diets were supplemented with yoghurt for 7 or 10 consecutive days, during 24 weeks. It was demonstrated that feeding yoghurt for 7 or 10 days increased cytotoxic and ß‐glucuronidase levels in peritoneal macrophages, and also the cytolytic capacity of serum, reaching values significantly higher than those in the DMH control. Enhancement of the phagocytic activity of the macrophages associated with the large intestine was also observed. This increase in the macrophage activity involved in the systemic and mucosal immune responses could also be responsible for the tumour inhibition observed in the group of mice fed with yoghurt. The presence in the serum of lytic factors (cytokines) which were released by immune cells activated by feeding yoghurt may also have had a role in tumour inhibition.     

Mating-type suppression of the DNA-repair defect of the yeast rad6Δ mutation requires the activity of genes in the RAD52 epistasis group

The RAD6 gene of Saccharomyces cerevisiae is required for post-replication repair of UV-damaged DNA, UV mutagenesis, and sporulation. Here, we show that the radiation sensitivity of a MAT a rad6 strain can be suppressed by the MAT2 gene carried on a multicopy plasmid. The a1-2 suppression is specific to the RAD6 pathway, as mutations in genes required for nucleotide excision repair or for recombinational repair do not show such mating-type suppression. The a1-2 suppression of the rad6 mutation requires the activity of the RAD52 group of genes, suggesting that suppression occurs by channelling of post-replication gaps present in the rad6 mutant into the RAD52 recombinational repair pathway. The a1-2 repressor could mediate this suppression via an enhancement in the expression, or the activity, of recombination genes.     

The effect of automated landmark identification on morphometric analyses

Morphometric analysis of anatomical landmarks allows researchers to identify specific morphological differences between natural populations or experimental groups, but manually identifying landmarks is time‐consuming. We compare manually and automatically generated adult mouse skull landmarks and subsequent morphometric analyses to elucidate how switching from manual to automated landmarking will impact morphometric analysis results for large mouse (Mus musculus) samples (n = 1205) that represent a wide range of ‘normal’ phenotypic variation (62 genotypes). Other studies have suggested that the use of automated landmarking methods is feasible, but this study is the first to compare the utility of current automated approaches to manual landmarking for a large dataset that allows the quantification of intra‐ and inter‐strain variation. With this unique sample, we investigated how switching to a non‐linear image registration‐based automated landmarking method impacts estimated differences in genotype mean shape and shape variance‐covariance structure. In addition, we tested whether an initial registration of specimen images to genotype‐specific averages improves automatic landmark identification accuracy. Our results indicated that automated landmark placement was significantly different than manual landmark placement but that estimated skull shape covariation was correlated across methods. The addition of a preliminary genotype‐specific registration step as part of a two‐level procedure did not substantially improve on the accuracy of one‐level automatic landmark placement. The landmarks with the lowest automatic landmark accuracy are found in locations with poor image registration alignment. The most serious outliers within morphometric analysis of automated landmarks displayed instances of stochastic image registration error that are likely representative of errors common when applying image registration methods to micro‐computed tomography datasets that were initially collected with manual landmarking in mind. Additional efforts during specimen preparation and image acquisition can help reduce the number of registration errors and improve registration results. A reduction in skull shape variance estimates were noted for automated landmarking methods compared with manual landmarking. This partially reflects an underestimation of more extreme genotype shapes and loss of biological signal, but largely represents the fact that automated methods do not suffer from intra‐observer landmarking error. For appropriate samples and research questions, our image registration‐based automated landmarking method can eliminate the time required for manual landmarking and have a similar power to identify shape differences between inbred mouse genotypes.     

Amiloride-sensitive Na+ transport across cultured renal (A6) epithelium: evidence for large currents and high NaK selectivity

Electrical techniques were used to determine the NaK selectivity of the amiloride-sensitive pathway and to characterize cellular and paracellular properties of A6 epithelium. Under control conditions, the mean transepithelial voltage (V _T) was –57±5 mV, the short-circuit current (I _sc) averaged 23±2 A/cm² and the transepithelial resistance (R _T) was 2.8±0.3 kcm² (n=13). V _T and I _sc were larger than reported in previous studies and were increased by aldosterone. The conductance of the amiloride-sensitive pathway (G _amil) was assessed before and after replacement of Na⁺ in the mucosal bath by K⁺, using two independent measurements: (1) the slope conductance (G _T), determined from current-voltage (I-V) relationships for control and amiloride-treated tissues and (2) the maximum amiloride-sensitive conductance (G _max) calculated from the amiloride dose-response relationship. The ratio of G _amil in mucosal Na⁺ solutions to G _amil for mucosal K⁺ solutions was 22±6 for G _T measurements and 15±2 for G _max data. Serosal ion replacements in tissues treated with mucosal nystatin indicated a potassium conductance in the basolateral membrane. Equivalent circuit analyses of nystatin and amiloride data were used to resolve the cellular (E _c) and paracellular (R _j) resistances (5 kcm² and 8–9 kcm², respectively). Analysis I-V relationships for tissues depolarized with serosal K⁺ solutions revealed that the amiloride-sensitive pathway could be described as a Na⁺ conductance with a permeability coefficient (P _Na)=1.5±0.2× 10^–6 cm/s and the intracellular Na⁺ concentration (Na_i)=5±1 mM (n=5), similar to values from other tight epithelia. We conclude that A6 epithelia are capable of expressing large amiloride-sensitive currents which are highly Na⁺ selective.     

Regulation of intracellular pH in cultured bovine retinal pigment epithelial cells

Regulation of intracellular pH (pH_i) in bovine retinal pigment epithelium (RPE) was investigated in cell culture. pH_i was measured using the pH-sensitive absorbance of intracellularly trapped 5 (and 6)-carboxy-dimethyl-fluorescein (CDMF). (1) Regulation of pH_i after induction of an acid load by removal of NH₄Cl could be blocked either totally by removal of extracellular sodium, or subtotally (about 90%) by application of amiloride (1 mmol/l). Additional flux measurements revealed a dose-dependent, amiloride-sensitive²²Na⁺-uptake into Na⁺-loaded cells. Both results suggest the presence of a Na⁺/H⁺ antiport.(2) When alkalinization of the cells was induced by preincubation with 50 mmol/l acetate in HCO ₃ ^– -Ringer's and subsequent removal of the weak acid, the following regulation was dependent on the presence of extracellular chloride. This process could be blocked with DIDS (1 mmol/l), suggesting the presence of a Cl^–/HCO ₃ ^– exchange mechanism.(3) We found no evidence for a Na⁺/HCO ₃ ^– -cotransport, which had been postulated to be present in RPE by others. We conclude that two processes are involved in regulation of pH_i in RPE: A Na⁺/H⁺ antiport responsible for recovery of pH_i from acid load, and a DIDS-sensitive Cl^–/HCO ₃ ^– exchange mechanism responsible for recovery of pH_i after alkalinization.Parts of this work jhave been published in abstract from [20, 21]