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Different Cellular Processes (different + cellular_process)

Distribution by Scientific Domains
Medical Sciences50%

Selected Abstracts

Diversity of bacteriorhodopsins in different hypersaline waters from a single Spanish saltern

ENVIRONMENTAL MICROBIOLOGY, Issue 11 2003
R. Thane Papke
Summary Haloarchaeal rhodopsins are a diverse group of transmembrane proteins that use light energy to drive several different cellular processes. Two rhodopsins, bacteriorhodopsin and halorhodopsins, are H+ and Cl, ion pumps, respectively, and two rhodopsins, sensory rhodopsin I and II, regulate phototaxis. Bacteriorhodopsin is of special interest as it is a non-chlorophyll-based type of phototrophy (i.e. generation of chemical energy from light energy). However, very little is known about the diversity and distribution of rhodopsin genes in hypersaline environments. Here, we have used environmental PCR and cloning techniques to directly retrieve rhodopsin genes from three different salinity ponds located in a sea salt manufacturing facility near Alicante, Spain. Our survey resulted in the discovery of previously concealed variation including what is hypothesized to be bacteriorhodopsin genes from the uncultivated square morphotype that dominates these environments. In some instances, identical genes were discovered in seemingly different habitats suggesting that some haloarchaea are present over widely varying concentrations of salt. [source]

Influence of Treatment Conditions on the Chemical Oxidative Activity of H2SO4/H2O2 Mixtures for Modulating the Topography of Titanium,

ADVANCED ENGINEERING MATERIALS, Issue 12 2009
Fabio Variola
Abstract Host-tissue integration of medical implants is governed by their surface properties. The capacity to rationally design the surface physico-chemical cues of implantable materials is thus a fundamental prerequisite to confer enhanced biocompatibility. Our previous work demonstrated that different cellular processes are elicited by the nanotexture generated on titanium (cpTi) and Ti6Al4V alloy by chemical oxidation with a H2SO4/H2O2 mixture. Here, we illustrate that by varying the etching parameters such as temperature, concentration, and treatment time, we can create a variety of surface features on titanium which are expected to impact its biological response. The modified submicron and nanotextured surfaces were characterized by scanning electron (SEM) and atomic force (AFM) microscopies. Contact angle measurements revealed the higher hydrophilicity of the modified surfaces compared to untreated samples and Fourier transform infrared spectroscopy (FT-IR) established that the etching generated a TiO2 layer with a thickness in the 40,60,nm range. [source]

Mechanisms of gene amplification and evidence of coamplification in drug-resistant human osteosarcoma cell lines

GENES, CHROMOSOMES AND CANCER, Issue 4 2009
Claudia M. Hattinger
Gene amplification and copy number changes play a pivotal role in malignant transformation and progression of human tumor cells by mediating the activation of genes and oncogenes, which are involved in many different cellular processes including development of drug resistance. Since doxorubicin (DX) and methotrexate (MTX) are the two most important drugs for high-grade osteosarcoma (OS) treatment, the aim of this study was to identify genes gained or amplified in six DX- and eight MTX-resistant variants of the human OS cell lines U-2OS and Saos-2, and to get insights into the mechanisms underlying the amplification processes. Comparative genomic hybridization techniques identified amplification of MDR1 in all six DX-resistant and of DHFR in three MTX-resistant U-2OS variants. In addition, progressive gain of MLL was detected in the four U-2OS variants with higher resistance levels either to DX or MTX, whereas gain of MYC was found in all Saos-2 MTX-resistant variants and the U-2OS variant with the highest resistance level to DX. Fluorescent in situ hybridization revealed that MDR1 was amplified in U-2OS and Saos-2/DX-resistant variants manifested as homogeneously staining regions and double minutes, respectively. In U-2OS/MTX-resistant variants, DHFR was amplified in homogeneously staining regions, and was coamplified with MLL in relation to the increase of resistance to MTX. Gene amplification was associated with gene overexpression, whereas gene gain resulted in up-regulated gene expression. These results indicate that resistance to DX and MTX in human OS cell lines is a multigenic process involving gene copy number and expression changes. © 2008 Wiley-Liss, Inc. [source]

Increased Acid Sphingomyelinase Activity in Peripheral Blood Cells of Acutely Intoxicated Patients With Alcohol Dependence

ALCOHOLISM, Issue 1 2010
Martin Reichel
Background:, Acid sphingomyelinase (ASM; EC 3.1.4.12) hydrolyses membrane sphingomyelin into the bioactive lipid ceramide and is thus involved in different cellular processes such as differentiation, immunity, or cell death. Activation of ASM has been reported in particular in conjunction with the cellular stress response to several external stimuli, and increased ASM activity was observed in a variety of human diseases. Ethanol-induced activation of ASM has been observed in different cell culture systems, thus raising the question about the effect of alcohol intoxication in human subjects on ASM activity in vivo. Methods:, We determined ASM activity in peripheral blood mononucleated cells of 27 patients suffering from alcohol dependence. Patients were classified according to their blood alcohol concentration at admission, and ASM activity was determined repeatedly from all patients during alcohol withdrawal. Results:, Acutely intoxicated patients displayed significantly higher ASM activity than patients in early abstinence (Mann,Whitney U test: Z = , 2.6, p = 0.009). ASM activity declined in acutely intoxicated patients to normal values with the transition from the intoxicated state to early abstinence (Wilcoxon test: Z = ,2.7, p = 0.007). At the end of withdrawal, ASM activity was significantly increased again compared to the early phase of abstinence in both patient groups (Wilcoxon test: Z = ,2.691, p = 0.007 and Z = ,2.275, p = 0.023, respectively). Conclusions:, Alcohol-induced activation of ASM occurs in human subjects and might be responsible for deleterious effects of ethanol intoxication. Chronic alcohol abuse may induce deregulation of sphingomyelin metabolism in general, and this impairment may cause side effects during withdrawal from alcohol. [source]