Effect of EGF on H2O2-induced inhibition of alpha-MG uptake in renal proximal tubule cells: involvement of MAPK and AA release

Both oxidative stress and epidermal growth factor (EGF) contribute to the initiation and progression of renal proximal tubular dysfunction under pathophysiologic conditions. Thus, this study was performed (1) to examine both the individual, and the combined effects of H2O2 and EGF on alpha-methyl-D-glucopyranoside uptake (alpha-MG uptake) in the primary cultured renal proximal tubule cells (PTCs), and (2) to elucidate the involvement of p44/42 mitogen activated protein kinase (MAPK) and phospholipase A2 in mediating these actions. Both H2O2 and EGF inhibited alpha-MG uptake individually, while the combination of H2O2 and EGF further potentiated the inhibitory effect on alpha-MG uptake, which was elicited by each agent. H2O2 not only caused a rapid increase in the phosphorylation of p44/42 MAPK, but also promoted the translocation of cytosolic phospholipase A2 (cPLA2) from the cytosolic to particulate fraction, and stimulated cellular [3H]-arachidonic acid (AA) release. EGF similarly activates phosphorylation of p44/42 MAPK and stimulates [3H]-AA release. When PTCs were exposed to 100 microM H2O2 and 50 ng/ml EGF simultaneously, a further increase in the phosphorylation of p44/42 MAPK, of [3H]-AA release, and of prostaglandin E2 (PGE2) production was elicited as compared with the effects of each individual agonist alone. Moreover, the additive phosphorylation of p44/42 MAPK, [3H]-AA release, and PGE2 production by H2O2 and EGF was almost completely inhibited by the p44/42 MAPK inhibitor, PD 98059. In conclusion, these results are consistent with the hypothesis that under conditions of oxidative stress, the H2O2-induced inhibition of alpha-MG uptake in the renal proximal tubule is mediated through a modulation of the EGF signaling pathway, promoting further phosphorylation of p44/42 MAPK, activation of PLA2.     

Morphological characterization of a human glioma cell l ine

A human malignant continuous cell line, named NG97, was recently established in our laboratory. This cell line has been serially subcultured over 100 times in standard culture media presenting no sign of cell senescence. The NG97 cell line has a doubling time of about 24 h. Immunocytochemical analysis of glial markers demonstrated that cells are positive for glial fibrillary acidic protein (GFAP) and S-100 protein, and negative for vimentin. Under phase-contrast microscope, cultures of NG97 showed cells with variable morphological features, such as small rounded cells, fusiform cells (fibroblastic-like cells), and dendritic-like cells. However, at confluence just small rounded and fusiform cells can be observed. At scanning electron microscopy (SEM) small rounded cells showed heterogeneous microextentions, including blebs and filopodia. Dendritic-like cells were flat and presented extensive prolongations, making several contacts with small rounded cells, while fusiform cells presented their surfaces dominated by microvilli.     

Managing familial risk in genetic testing

Increasing numbers of people are seeking genetic testing and uncovering information that directly concerns their biological relatives as well as themselves. This familial quality of genetic information raises ethical quandaries for physicians, particularly related to their duty of confidentiality. In this article, the American Medical Association's Council on Ethical and Judicial Affairs examines the informed consent process in the specific context of genetic testing, giving particular consideration to the handling of information that has consequences for biological relatives. Furthermore, it addresses the question of whether physicians' obligation to warn biological relatives ever should override the obligation to protect patient confidentiality.     

Is endothelial-nitric-oxide-synthase-derived nitric oxide involved in cardiac hypoxia/reoxygenation-related damage?

Nitric oxide (NO) has been reported to act both as a destructive and a protective agent in the pathogenesis of the injuries that occur during hypoxia/reoxygenation (H/R). It has been suggested that this dual role of NO depends directly on the isoform of NO synthase (NOS) involved. In this work, we investigate the role that NO derived from endothelial NOS (eNOS) plays in cardiac H/R-induced injury. Wistar rats were submitted to H/R (hypoxia for 30 min; reoxygenation of 0 h, 12 h and 5 days), with or without prior treatment using the selective eNOS inhibitor l-NIO (20 mg/kg). Lipid peroxidation, apoptosis and protein nitration, as well as NO production (NOx), were analysed. The results showed that l-NIO administration lowered NOx levels in all the experimental groups. However, no change was found in the lipid peroxidation level, the percentage of apoptotic cells or nitrated protein expression, implying that eNOS-derived NO may not be involved in the injuries occurring during H/R in the heart. We conclude that l-NIO would not be useful in alleviating the adverse effects of cardiac H/R.     

The small-subunit ribosomal RNA gene sequences from the hypotrichous ciliates Oxytricha nova and Stylonychia pustulata

We have determined the complete nucleotide sequence of the small- subunit ribosomal RNA genes for the ciliate protozoans Stylonychia pustulata and Oxytricha nova. The sequences are homologous and sufficiently similar that these organisms must be closely related. In a phylogeny inferred from comparisons of several eukaryotic small-subunit ribosomal RNAs, the divergence of the ciliates from the eukaryotic line of descent is seen to coincide with the radiation of the plants, the animals, and the fungi. This radiation is preceded by the divergence of the slime mold, Dictyostelium discoideum.