Partial Protection of PC12 Cells from Cellular Stress by Low-Dose Sodium Nitroprusside Pre-treatment.

The PC12 rat pheochromocytoma cell line is an in vitro model system widely used for the investigation of intracellular signaling events contributing to neuronal differentiation and cell death. We found earlier that the nitric oxide donor compound sodium nitroprusside (SNP) induced apoptosis of PC12 cells if it was applied in high concentration (400 µM). Yoshioka et al. (J Pharmacol Sci 101:126-134, 2006) reported that cell death evoked by cytotoxic concentrations of SNP could be prevented by a 100 µM SNP pre-treatment in a murine macrophage cell line. The apoptosis caused by toxic-dose SNP treatment (400 µM) could be partially overcome in PC12 cells as well by the low-dose SNP pre-treatment. The partial inhibition of apoptosis was accompanied by reduced phosphorylation of certain proteins (such as stress-activated protein kinases, the p53, and the eIF2α proteins), decreased caspase activation, and less intense internucleosomal DNA fragmentation. The 100 µM SNP pre-treatment reduced the pro-apoptotic potential of certain other stress stimuli (serum withdrawal, cisplatin and tunicamycin treatments) as well, although the underlying biochemical changes were not entirely uniform. On the contrary, the 100 µM SNP pre-treatment was unable to prevent cell death caused by the protein synthesis inhibitor anisomycin. Further clarification of the above-mentioned processes may be important in understanding the mechanisms by which mild nitrosative stress protects cells against certain forms of cellular stress conditions.

Dominating prevalence of P[8],G1 and P[8],G9 rotavirus strains among children admitted to hospital between 2000 and 2003 in Budapest, Hungary.

Group A rotaviruses are the main cause of acute dehydrating diarrhea in children, responsible for high mortality in developing countries and a significant socio-economic burden associated with treating the disease in developed countries. Two rotavirus vaccine candidates predicated on either homotypic or heterotypic protection have undergone clinical trials recently and await licensure for routine use. In anticipation of a future vaccination campaign in Hungary, the diversity of rotaviruses collected from Budapest between 2000 and 2003 were analyzed by polyacrylamide gel electrophoresis (PAGE) of the viral genome and by serotyping and genotyping of the outer capsid genes, VP7 and VP4. Among 2,763 rotavirus positive specimens available for analysis, we were able to determine the electropherotype of 2,227, and, of these, 1,517 (68.1%) were subjected to G typing and 1,173 (52.7%) were subjected to P typing. We successfully G typed 1,481 (97.6%) and P typed 1,130 (96.3%) strains, respectively. A total of six G types (G1, 50.2%; G2, 2.2%; G3, 1.7%; G4, 5.8%; G6, 0.6%; and G9, 34.4%) and four P types (P[4], 3.0%; P[6], 0.7%; P[8], 89.9%; and P[9], 1.7%) were identified in nine individual combinations (P[8],G1; P[4],G2; P[8],G3; P[8],G4; P[8],G9; P[6],G4; P[4],G1; P[9],G3; and P[9],G6). The prevalence of VP7 and VP4 specificities varied from year to year. In this regard, a shift in serotype predominance from G1 in 2000-2001 (61.8%) and 2001-2002 (69.7%) to G9 in 2002-2003 (51.3%) was an intriguing observation that has been reported recently in some other countries, as well. The emergence of serotype G9 rotaviruses in Hungary and other parts of the world may have implications for future vaccine development and use, particularly, if current vaccine candidates cannot confer adequate homotypic or heterotypic protection against these strains.

Molecular epidemiology of human P[8],G9 rotaviruses in Hungary between 1998 and 2001.

Increasing numbers of studies have documented the widespread distribution of human G9 rotaviruses and demonstrated that these strains may represent a fifth epidemiologically important G serotype. Serotype G9 strains were identified in Hungary for the first time in the 1997-1998 rotavirus season. Contrary to numerous surveys that reported several unexpected P-G combinations among recent G9 isolates (e.g. genotypes P[4], P[6] and P[19]), all Hungarian strains characterized to date possess the globally most common P-type, P[8], which was found among the first G9 isolates that were identified during the 1980s in the USA (WI61) and Japan (F45). To study the genetic variability within Hungarian G9 strains, RNA profile analysis and nucleotide sequencing were performed on a subset of samples that were collected between 1998 and 2001. These strains could be classified into four major RNA profiles, of which two were characteristic for epidemiologically major and two for epidemiologically minor G9 strains. Phylogenetic analysis demonstrated substantial sequence differences between the VP7 gene of Hungarian G9 strains and early strains that were isolated in the USA (WI61), Japan (F45) and India (116E) and a few recently identified isolates, e.g. from China (97'SZ37) and the USA (OM67) (< 90 % nucleotide sequence similarity). In contrast, the VP7 genes of Hungarian G9 strains were related very closely to the vast majority of G9 strains that were isolated in a variety of countries over the last several years (> 96 % nucleotide sequence similarity). With respect to the VP4 gene, Hungarian G9 rotaviruses fell into two of the major genetic lineages of genotype P[8], one corresponding to the epidemic strains (lineage II; P-like) and the other for two unique strains (lineage I; Wa-like), suggesting independent introduction of distinct P[8],G9 strains into Hungary or genetic reassortment between locally circulating P[8] strains and descendants of G9 isolates that were imported into the country at an earlier time. The unexpected heterogeneity found for G9 VP7 genes from several countries suggests that genetic variation among these strains has not yet been fully explored.