Effects of low density lipoprotein on cytosolic [Ca++] in cultured rat mesangial cells

BACKGROUND: Recently, a low density lipoprotein (LDL) receptor has been identified in mesangial cells. However, the nature of intracellular signals in mesangial cells after exposure to LDL is unclear. METHODS: We studied the effect of LDL on cultured rat mesangial cell [Ca++]i using spectrofluorometry. RESULTS: Addition of LDL (15 micrograms/mL) produced a rapid, transient, and dose-dependent rise in [Ca++]i within seconds, returning to baseline in 6 minutes. No further rise was observed at higher LDL concentrations. No significant rise in [Ca++]i was observed with LDL in cells placed in a Ca(++)-free medium. The [Ca++]i rise was greatly attenuated in magnitude and duration when lanthanum was used. In contrast, verapamil failed to block the LDL-induced rise in [Ca++]i. Addition of LDL did not alter production of inositol 1,4,5-triphosphate (IP3) by mesangial cells. CONCLUSIONS: Low density lipoprotein caused a transient rise in [Ca++]i in cultured rat mesangial cells. The observed rise in [Ca++]i was largely caused by influx of extracellular Ca++ through receptor-gated channels. Mobilization from intracellular stores and activation of IP3 were not involved. The rise in [Ca++]i may mediate the effects of LDL on mesangial cell function.     

Results of engineering geological research in granite

The assessment of deep-seated rock in terms of engineering geology and geotechnology with respect to its suitability as a host rock for a final repository for radioactive waste requires the knowledge of the in-situ behavior of the rock in particular the stress and deformation behavior as well as the knowledge of permeability. The waterpercolation through fissured granite and the stress field is being studied in a Swiss German cooperation by the Federal Institute for Geosciences and Natural Resources (BGR) in the Grimsel Rock Laboratory in Switzerland. This laboratory is operated by the National Corporation for the Storage of Radioactive Waste (NAGRA) of Switzerland. German participants are the BGR and the Research Centre for Environmental Sciences (GSF). BGR is responsible for the Fracture System Flow Test (BK), a modified water injection test and advanced Rock Stress Measurements (GS) in deep boreholes. Target of both projects is the development of methods and instruments. In the presentation, some of the results of the stress and permeability measurements will be used to discuss the methods.     

Trajectories of perceived adult and peer discrimination among Black, Latino, and Asian American adolescents: Patterns and psychological correlates.

This article presents results from a 3-year longitudinal study of the growth patterns and correlates of perceived discrimination by adults and by peers among Black, Latino, and Asian American high school students. Results revealed a linear increase over time in levels of perceived discrimination by adults, whereas perceptions of discrimination by peers remained stable over time. Asian American and non-Puerto Rican Latino adolescents (primarily Dominican) reported higher levels of peer and/or adult discrimination than did Puerto Rican youth, whereas Black adolescents reported a steeper increase over time in levels of perceived discrimination by peers and by adults than did Puerto Rican adolescents. Peer and adult discrimination was significantly associated with decreased self-esteem and increased depressive symptoms over time. Ethnic identity and ethnicity were found to moderate the relationships between perceived discrimination and changes in psychological well-being over time. Results underscore the need to include perceptions of discrimination when studying the development and well-being of ethnic minority adolescents. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Wolfgang Beitz与工程设计学

编者按:Gerhard Pahl和Wolfgang Beitz是国际公认的设计方法学的主要开拓者.他们合著的<工程设计学>以7种文字在世界上出版,从而成为至今在世界上流传最广、影响最大的设计学领域最经典的著作.不幸的是这一对"忘年交"中较年轻的Beitz教授在1998年11月因病去世.     

Analysis of Monte Carlo methods applied to blackbody and lower emissivity cavities

Monte Carlo methods are often applied to the calculation of the apparent emissivities of blackbody cavities. However, for cavities with complex as well as some commonly encountered geometries, the emission Monte Carlo method experiences problems of convergence. The emission and absorption Monte Carlo methods are compared on the basis of ease of implementation and convergence speed when applied to blackbody sources. A new method to determine solution convergence compatible with both methods is developed, and the convergence speeds of the two methods are compared through the application of both methods to a right-circular cylinder cavity. It is shown that the absorption method converges faster and is easier to implement than the emission method when applied to most blackbody and lower emissivity cavities.     

Hydrodynamische Beanspruchung von Rührorganen

Mechanical design of agitation equipment requires information about the hydrodynamic stresses acting on impeller shafts, baffles, and vessels. In particular, vibrations induced in the generally freely supported impeller shafts impose very strong stresses on the shaft bearings at the natural frequency of the assembly and can lead to shaft fracture in extreme cases. Depending upon the speed of rotation, the surrounding medium acts as variable damping member owing to the differing flow conditions. This situation is examined in the present article.     

Einsatz und Auslegung statischer Mischer

Application and design of static mixers . Static mixers are units without, or only with fixed, internal fittings which effect the mixing of flowing materials with the aid of their kinetic energy. They are used for continuous homogenization and dispersion, for limitation of the residence time spectrum, and for raising heat and mass transfer in all areas of chemical engineering. Over 20 static mixers are presented, and compared with regard to pressure drop, mixing quality, energy consumption, and residence time and heat transfer behaviour. Important selection criteria are reported. Static mixers have the following advantages over dynamic mixers: use for a wide range of viscosities, narrow residence time spectrum, readily adaptable to existing pipe systems, frequently require no extra space (in-line mixers), negligible maintainance and wear, low investment and operating costs.     

Analysis of thermochemically-derived wood oil

An oil derived by thermochemical conversion of Douglas fir wood chips has been characterized by capillary column gas chromatography/mass spectrometry analysis after fractionation by vacuum distillation. The oil was composed primarily of phenols, but cyclic ketones and alcohols were also present in the low-boiling fraction. The alkenes, cycloalkenes, and alkyl benzenes reported by other workers were not found, and the potential for confusing cyclic ketones and alcohols with them on the basis of both mass spectra and retention times is discussed.