A novel cardioprotective p38-MAPK/mTOR pathway

Despite intensive study, the mechanisms regulating activation of mTOR and the consequences of that activation in the ischemic heart remain unclear. This is particularly true for the setting of ischemia/reperfusion (I/R) injury. In a mouse model of I/R injury, we observed robust mTOR activation, and its inhibition by rapamycin increased injury. Consistent with the in-vivo findings, mTOR activation was also protective in isolated cardiomyocytes exposed to two models of I/R. Moreover, we identify a novel oxidant stress-activated pathway regulating mTOR that is critically dependent on p38-MAPK and Akt. This novel p38-regulated pathway signals downstream through REDD1, Tsc2, and 14-3-3 proteins to activate mTOR and is independent of AMPK. The protective role of p38/Akt and mTOR following oxidant stress is a general phenomenon since we observed it in a wide variety of cell types. Thus we have identified a novel protective pathway in the cardiomyocyte involving p38-mediated mTOR activation. Furthermore, the p38-dependent protective pathway might be able to be selectively modulated to enhance cardio-protection while not interfering with the inhibition of the better-known detrimental p38-dependent pathways.     

Early Activation of Antioxidant Responses in Ni-Stressed Tomato Cultivars Determines Their Resilience Under Co-exposure to Drought

Journal of Plant Growth Regulation - Throughout their life cycle, plants are subjected to a variety of environmental constraints, including abiotic stresses. The present study aimed at...     

Using 2-aminopurine fluorescence to measure incorporation of incorrect nucleotides by wild type and mutant bacteriophage T4 DNA polymerases

The ability of wild type and mutant T4 DNA polymerases to discriminate in the utilization of the base analog 2-aminopurine (2AP) and the fluorescence of 2AP were used to determine how DNA polymerases distinguish between correct and incorrect nucleotides. Because T4 DNA polymerase incorporates dTMP opposite 2AP under single-turnover conditions, it was possible to compare directly the kinetic parameters for incorporation of dTMP opposite template 2AP to the parameters for incorporation of dTMP opposite template A without the complication of enzyme dissociation. The most significant difference detected was in the K(d) for dTTP, which was 10-fold higher for incorporation of dTMP opposite template 2AP (approximately 367 microm) than for incorporation of dTMP opposite template A (approximately 31 microm). In contrast, the dTMP incorporation rate was reduced only about 2-fold from about 318 s(-1) with template A to about 165 s(-1) for template 2AP. Discrimination is due to the high selectivity in the initial nucleotide-binding step. T4 DNA polymerase binding to DNA with 2AP in the template position induces formation of a nucleotide binding pocket that is preshaped to bind dTTP and to exclude other nucleotides. If nucleotide binding is hindered, initiation of the proofreading pathway acts as an error avoidance mechanism to prevent incorporation of incorrect nucleotides.     

Simple method for determination of paraquat in plasma and serum of human patients by high-performance liquid chromatography

A simple and fast HPLC system is presented for quantifying paraquat in human plasma and serum using 1,1'-diethyl-4,4'-bipyridyldiylium (diethyl paraquat) as an internal standard. An octadecyl-silica column is used with an eluent of 10% acetonitrile (v/v) containing sodium 1-octanesulphonic acid (3.0 mM) and a diethylamine-orthophosphoric acid buffer (pH 3). Unlike with other techniques, sample treatment requires only the precipitation of protein contents by 6% perchloric acid (v/v) in methanol. The method has a limit of detection of 0.1 microg/ml and is linear up to 10 microg/ml. The serum of four patients and the plasma of one patient with paraquat intoxication's were analysed and positive identification and quantification was readily achieved. One of those patients survived, partially given the rapid disclosure of his levels of paraquat. Therefore, this method is suitable for quantification of paraquat in toxicological samples. It may be used as a prognostic tool in critical case detoxification and to quickly identify potentially salvageable patients for enrollment in new hemofiltration studies.     

Effect of thiadiazine derivatives on intracellular amastigotes of Leishmania amazonensis

Current therapy for leishmaniasis is not satisfactory. We describe the in vitro antiproliferative effects of new thiadiazine derivatives against Leishmania amazonensis. The compounds were found to be active against the amastigote form of the parasite, inhibiting parasite growing, from 10 to 89%, at a concentration of 100 ng/ml. This activity suggests that thiadiazine derivatives could be considered as potential antileishmanial compounds.     

Occurrence of Salmonella spp in estuarine and coastal waters of Portugal

The presence of Salmonella and its relationship with indicator organisms of fecal pollution, such as total coliforms, fecal coliforms and fecal streptococci, was studied at two marine zones in Portugal. Seventeen different Salmonella serotypes were isolated and identified, S. virchow was the most frequently isolated (21.6%). In addition, a high percentage (35.1%) was recorded for some Salmonella serotypes of clinical significance, namely S. enteritidis, S. infantis, S. typhimurium and S. virchow. In any of the samples from the two zones Salmonella was not detected in the absence of any of the indicator organisms. However, the incidence of Salmonella as a function of indicator concentration intervals established by the EEC standards was 0, 10 and 19.3% at guide values of total coliforms, fecal coliforms and fecal streptococci, respectively in the Faro samples (south of Portugal). In contrast, Salmonella incidence rates of 37.5, 36.4 and 33.3% were recorded at the corresponding guide values the Caminha samples (north of Portugal). No significant correlations (p>0.005) were obtained between Salmonella and the indicators at the sampling stations; however, total coliforms and fecal streptococci were the indicators most closely related to Salmonella in Caminha and Faro samples, respectively. Survival experiments in Escherichia coli, Enterococcus faecalis and S. typhimurium, using diffusion chambers, were performed to verify whether the lack of correlation between indicators and Salmonella was due to different inactivation rates in seawater. The results indicate that survival percentages of the three microorganisms tested were similar after 48 h of exposure to seawater.