Glutamine deprivation induces apoptosis in intestinal epithelial cells

BACKGROUND: Glutamine is the most abundant amino acid in the blood, and its deprivation leads to gut mucosal atrophy. The small intestinal mucosa is maintained by a balance between cell proliferation and cell death by apoptosis. We reported that glutamine is required for nitrogen-stimulated proliferation in intestinal epithelial cells. We do not know whether glutamine regulates apoptosis in the gut. The purpose of this study is to determine whether glutamine deprivation induces apoptosis in rat intestinal epithelial (RIE-1) cells and to compare the effect of glutamine starvation with that of methionine and cysteine (Met/Cys) starvation. METHODS: RIE-1 cells were deprived of either glutamine or Met/Cys for 24 hours. Cell numbers were determined by cell counting and tetrazolium enzymatic assay. Apoptosis was quantified by Annexin V assay and confirmed by DNA gel electrophoresis and Hoecsht nuclear staining. RESULTS: Deprivation of glutamine or Met/Cys resulted in decreased cell numbers. However, only the glutamine-deprived group showed significant induction of apoptosis with increased Annexin V staining, DNA laddering, and nuclear condensation. CONCLUSIONS: This study provides biochemical and morphologic evidence that glutamine deprivation induces apoptosis in rat intestinal epithelial cells. In contrast, Met/Cys starvation suppresses cell number without induction of apoptosis. These results suggest that glutamine serves as a specific survival factor in enterocytes.     

Characterization and detection of Anopheles vestitipennis and Anopheles punctimacula (Diptera: Culicidae) larval habitats in Belize with field survey and SPOT satellite imagery

Surveys of larval habitats of Anopheles vestitipennis and Anopheles punctimacula were conducted in Belize, Central America. Habitat analysis and classification resulted in delineation of eight habitat types defined by dominant life forms and hydrology. Percent cover of tall dense macrophytes, shrubs, open water, and pH were significantly different between sites with and without An. vestitipennis. For An. punctimacula, percent cover of tall dense macrophytes, trees, detritus, open water, and water depth were significantly different between larvae positive and negative sites. The discriminant function for An. vestitipennis correctly predicted the presence of larvae in 65% of sites and correctly predicted the absence of larvae in 88% of sites. The discriminant function for An. punctimacula correctly predicted 81% of sites for the presence of larvae and 45% for the absence of larvae. Canonical discriminant analysis of the three groups of habitats (An. vestitipennis positive; An. punctimacula positive; all negative) confirmed that while larval habitats of An. punctimacula are clustered in the tree dominated area, larval habitats of An. vestitipennis were found in both tree dominated and tall dense macrophyte dominated environments. The forest larval habitats of An. vestitipennis and An. punctimacula seem to be randomly distributed among different forest types. Both species tend to occur in denser forests with more detritus, shallower water, and slightly higher pH. Classification of dry season (February) SPOT multispectral satellite imagery produced 10 land cover types with the swamp forest and tall dense marsh classes being of particular interest. The accuracy assessment showed that commission errors for the tall, dense marsh and swamp forest appeared to be minor; but omission errors were significant, especially for the swamp forest (perhaps because no swamp forests are flooded in February). This means that where the classification indicates there are An. vestitipennis breeding sites, they probably do exist; but breeding sites in many locations are not identified and could be more abundant than indicated.     

GD3, a prominent ganglioside of human melanoma. Detection and characterisation by mouse monoclonal antibody

Mouse monoclonal antibody AbR24 has a high degree of specificity for human melanoma cells when tested on viable cultured cells using the protein A mixed hemagglutinin serological assay. The antigen detected by this antibody has been isolated from melanoma cells and shown to be GD3 ganglioside by compositional and partial structural analysis and by comparison with authentic GD3 in thin layer chromatography (TLC). AbR24 reacts with authentic GD3, but not with any other ganglioside tested. Using TLC and reactivity with AbR24, a wide range of cells and tissues was examined for the presence of GD3. A new serological assay, termed glycolipid-mediated immune adherence, was devised for assaying the reactivity of AbR24 with gangliosides. Melanomas (cultured cells or tumor tissue) were shown to have GD3 and GM3 as major gangliosides. Other cells and tissues examined also contained GD3, but usually only in low amounts. Melanomas (and MOLT-4, a T cell line) were characterized by a simplified ganglioside profile with GD3 and GM3 as major components. The apparent discrepancy between the ubiquitous presence of GD3 and the serological specificity of AbR24 for melanoma cells can be explained in terms of localization and concentration of GD3 in different cells.     

Atypical vagal Wenckebach period in a high performance athlete

A 27-year-old man, engaged in heavy physical training, exhibited sinusbradyarrhythmia with atrial abnormality and second degree av-block (atypical Wenckebach period). Since abnormal sinusrhythms was established with exercise and following parasympathetic blockade, this rhythm disorder was considered consequential exaggerated vagal tone. With the aid of His-bundle electrocardiography the block was localized in the av-node (AH).     

关于解决供电配电所问题的协调控制战略研究

提出了在主变压器事故、工作计划、过负荷、预防过负荷等问题在供电配电所出现的时候,以电力SCADA系统和配电SCADA的协作控制战略(CCT:Coord ination Control Strategy)为基础,研究运用负荷切换战略来消除事故波及效果的同时提高配电所运营安全性的方法.协调控制战略分为2阶段:第1阶段,通过利用母线重构解决方案(DSBRES:D istribution Substation Bus ReconfigurationExpert System)得出供电配电所的母线重构战略;第2阶段,根据从第1阶段得出的资料和配电系统重构解决方案(DSFRES:D istribution Systsem FeederReconfiguration Expert System)而得出配电系统线路重构.最后,给出了能表示供电、配电所和配电系统特性的代表性供电配电所模式和配电系统的模式.     

Effect of heat treatment on corrosion properties of CuAlNi shape memory alloy

The effect of heat treatment on corrosion properties of CuAlNi shape memory alloy was investigated in 0.9% NaCl solution at pH 7.4 and 37 °C by open circuit potential measurements, polarisation techniques, and electrochemical impedance spectroscopy. Investigations were performed on CuAlNi alloy samples in as-cast state and after heat treatment procedure containing annealing at 850, 885 and 920 °C followed by water quenching. Electrochemical impedance measurement results indicate that heat treatment of CuAlNi alloy leads to the increase in charge transfer resistance and surface layer resistance and the decrease in values of capacitance of the double and surface layers, indicating higher corrosion resistance compared with the as-cast CuAlNi alloy. The increase in polarisation resistance and the decrease in corrosion current density of heat-treated CuAlNi alloy also suggest beneficial influence of heat treatment on corrosion resistance of CuAlNi alloy. Optical microscopy, SEM/EDX and XRD analysis of samples surface after polarisation measurements show the occurrence of pitting corrosion on the electrode surfaces, with the existence of CuCl₂, AlCl₃ and Cu₂Cl(OH)₃ compounds as the surface corrosion products.     

Purification and Characterization of β-amylase from Bacillus polymyxa No. 26-1

An extracellular β-amylase, which was easily adsorbable onto raw corn starch, was purified 22.5-fold from a new isolate of Bacillus polymyxa No 26–1 with a M_r of 53 kDa and pI of 9.1. The optimum temperature was 45°C and pH 5.5 for raw corn starch. Thermal stability at 40°C and pH stability at 5.0–8.5 were shown. The degradation ofraw starch by β-amylase was greatly stimulated by pullulanase addition. Scanning electron micrographs revealed that starch granule degradation by the enzyme alone occured at the equatorial grooves of lecticular granules. Corn starch granules hydrolyzed by β-amylase had large holes on granule surfaces.