Reduced deformability of erythrocytes exposed to hypercapnia

Summary The effect of hypercapnia on the deformability of erythrocytes was studied by means of a nuclepore membrane filter method. A decrement of the deformability by 20–40% was observed when was increased from 50 mm Hg to 200 mm Hg, accompanied with an increment of 5% in hematocrit value.     

Reduced deformability of erythrocytes exposed to hypercapnia.

The effect of hypercapnia on the deformability of erythrocytes was studied by means of a nuclepore membrane filter method. A decrement of the deformability by 20--40% was observed when PCO2 was increased from 50 mm Hg to 200 mm Hg, accompanied with an increment of 5% in hematocrit value.     

利用环介导恒温扩增法简易诊断松萎蔫病

诊断松萎蔫病的传统方法是从木质组织中分离松材线虫,然后用显微镜进行形态学鉴定.基于DNA分子检测的方法尽管很灵敏,不需要固定发育阶段的松材线虫,但是仍然需要用Baermann漏斗法分离线虫,并且需要昂贵的仪器.笔者研发了利用环介导恒温扩增法检测松材线虫的存在,该方法包括:(1)从木块中提取DNA；(2) DNA扩增；(3)通过反应溶液的颜色做出诊断.该方法仅使用培养箱且整个过程只需要90 min,比以往方法更加简便和快速.     

Ground observations of post-noon aurora: a case study

The characteristics of the post-noon aurora observed at Antarctic Zhongshan station on June 12, 1999, were discussed and analyzed. In the condition of the magnetic activity is not large (K _p≈1), for post-noon 630.0 nm emissions, the total fluxes of soft precipitating particles were increasing from 10∶50 UT to 13∶35 UT and were decreasing from 13∶35 UT to 18∶00 UT in almost monotonous way. Away from noon, the 557.7 nm emissions increased gradually from 10∶50 UT to 17∶10 UT. The behaviors of the precipitating particles for exciting 630.0 nm aurora and 557.7 nm aurora were quite different. The peak intensity of 630.0 nm and 557.7 nm emissions appeared at about 13∶35 UT and 15∶40 UT respectively, the time difference of two peaks is about 2 h. The energy of precipitating electrons remained fairly steady until 15∶00 UT when it rose dramatically. Foundation item: Support by the National Natural Science Foundation of China (49634160) Biography: Ai Yong (1958-), male, Associate professor, research direction: upper atmosphere physics.     

Suppression of tumorigenicity in human colon carcinoma cells by introduction of normal chromosome 5 or 18.

Development of colon carcinomas can be associated with allelic deletions on several chromosomes, including 5q and 18q. The APC gene on 5q and the DCC gene on 18q have been identified as potential tumour suppressor genes, whose suppression contributes to colon carcinogenesis. To investigate the role of genes in these deleted regions, we have now introduced a single normal human chromosome into a human colon carcinoma cell line, COKFu, through microcell hybridization. Several clones of hybrid cells containing normal chromosome 5, and others containing normal chromosome 18, were obtained. The morphology of the hybrid cells was markedly altered: the hybrids with chromosome 5 exhibited a closely packed polygonal morphology, and the hybrid cells with chromosome 18 were flattened. The cloning efficiency of the hybrid cells in soft agar was reduced from 0.46 to 0% of that of the parental carcinoma cells, and the tumorigenicity of these hybrid cells in athymic nude mice was completely suppressed. The growth properties of the hybrid cells with chromosome 11 were not substantially changed. These results strongly suggest that the genes on normal chromosome 5 and 18 function as tumour suppressors in colon carcinogenesis.     

Einfluss des Licht-Dunkel-Wechsels auf den O2-Umsatz der Rattenleber

Summary Similar diurnal periodicity in oxygen consumption of liver slices in Wistar rats was observed as that previously found in Sprague-Dawley rats. The rate of oxygen consumption was low in the morning and high in the evening. After inversion of lighting regimes, the phase shifted and reached the reversal curve in about 30 days. On the basis of these findings, it is estimated that diurnal periodicity in oxygen consumption of liver slices is influenced by alteration of the periods of light and darkness. Liver glycogen rhythm showed a reversed correlation to that of oxygen consumption in both lighting regimes.     

Magnetization distribution in the mixed-phase state of hole-doped manganites

The effect of 'colossal magnetoresistance' (CMR) in hole-doped manganites--an abnormal decrease of resistivity when a magnetic field is applied--has attracted significant interest from researchers in the past decade. But the underlying mechanism for the CMR phenomenon is not yet fully understood. It has become clear that a phase-separated state, where magnetic and non-magnetic phases coexist, is important, but the detailed magnetic microstructure of this mixed-phase state is so far unclear. Here we use electron microscopy to study the magnetic microstructure and development of ferromagnetic domains in the mixed-phase state of La(1-x)Sr(x)MnO3 (x = 0.54, 0.56). Our measurements show that, in the absence of a magnetic field, the magnetic flux is closed within ferromagnetic regions, indicating a negligible magnetic interaction between separated ferromagnetic domains. However, we also find that the domains start to combine with only very small changes in temperature. We propose that the delicate nature of the magnetic microstructure in the mixed-phase state of hole-doped manganites is responsible for the CMR effect, in which significant conduction paths form between the ferromagnetic domains upon application of a magnetic field.     

Mechanotransduction through growth-factor shedding into the extracellular space

Physical forces elicit biochemical signalling in a diverse array of cells, tissues and organisms, helping to govern fundamental biological processes. Several hypotheses have been advanced that link physical forces to intracellular signalling pathways, but in many cases the molecular mechanisms of mechanotransduction remain elusive. Here we find that compressive stress shrinks the lateral intercellular space surrounding epithelial cells, and triggers cellular signalling via autocrine binding of epidermal growth factor family ligands to the epidermal growth factor receptor. Mathematical analysis predicts that constant rate shedding of autocrine ligands into a collapsing lateral intercellular space leads to increased local ligand concentrations that are sufficient to account for the observed receptor signalling; direct experimental comparison of signalling stimulated by compressive stress versus exogenous soluble ligand supports this prediction. These findings establish a mechanism by which mechanotransduction arises from an autocrine ligand-receptor circuit operating in a dynamically regulated extracellular volume, not requiring induction of force-dependent biochemical processes within the cell or cell membrane.     

两级水解酸化-FCR系统处理印染废水

采用两级水解酸化-FCR系统处理印染废水,考察了不同水力停留时间(HRT)对COD、色度、NH3-N和苯胺等去除效果的影响,并对最佳水力停留时间时脱氮效果进行了研究.结果表明:当HRT为30h时,系统COD、色度、TN、NH3-N和苯胺的平均去除率分别为93.3%、81.9%、79.9%、98.1%和74.8%,出水满足《GB 4287—92纺织染整工业水污染物排放标准》的一级标准.该系统具有较高的去污脱色效果,脱氮效果尤其显著,可应用于中、高浓度印染废水的处理.