Physiological effects of copper in the euryhaline copepod Acartia tonsa: waterborne versus waterborne plus dietborne exposure

The physiological effects of waterborne and waterborne plus dietborne copper exposure were determined in the euryhaline copepod Acartia tonsa at different salinities (5, 15 and 30ppt). Copepods were exposed (48h) to a reported 48-h LC50 for copper (CuCl(2)), which had been previously determined under the same experimental conditions. Whole body copper accumulation, ion concentrations (Na(+), Cl(-), Mg(2+)), and Na(+), K(+)-ATPase activity were the endpoints measured in all experimental groups. Feeding rate was also measured in fed experimental groups. In copper-exposed copepods, whole body copper accumulation was dependent on salinity, decreasing as salinity increased. However, it was similar in copepods exposed to waterborne and waterborne plus dietborne copper, irrespective the salinity tested. Waterborne copper exposure induced a disturbance of the whole body Na(+) concentration in all salinities tested. This effect was characterized by an increased whole body Na(+) concentration in seawater (salinity 30ppt) and a decreased whole body Na(+) concentration at lower salinities (5 and 15ppt). The ionoregulatory imbalance in low salinity (5ppt) was associated with an inhibition of the whole body Na(+), K(+)-ATPase activity, as observed in freshwater fish and crustaceans. When copepods were exposed to waterborne plus dietborne copper, the physiological effects described were only observed at a low salinity (5ppt) and were associated with a marked inhibition of the feeding rate. Taken altogether, the data suggest that the physiological effects induced by waterborne copper exposure in A. tonsa acclimated to higher salinities (15 and 30ppt) are due to a combined effect of food restriction and copper exposure. Differential physiological responses to waterborne and waterborne plus dietborne copper cannot be ascribed to differences in whole body copper burden.     

Expression of a metastatic phenotype in IFNs-primed/TNFα-activated B16 murine melanoma cells: role of JAK1/PKCδ signal transduction factors

In previous studies, we found that IFNγ and TNFα generated by activated macrophages stimulate the metastatic potential in F10-M3 cells, a clone isolated from B16-F10 murine melanoma line. In this phenomenon, TNFα promoted the expression of a metastatic phenotype in tumor cells previously primed with IFNγ. Here, we demonstrate that IFNα or IFNβ may replace IFNγ in priming tumor cells. We also noticed that an enhancement of the expression of p55TNFα receptor was associated with the preconditioning of tumor cells with IFNγ and IFNβ. By the use of an appropriate inhibitor, we observed that JAK1 signal transduction pathway was involved in the expression of a metastatic phenotype and of p55TNFα receptor shown in IFNγ- and IFNβ-primed melanoma cells stimulated with TNFα. Furthermore, the activity of the protein kinase C (PKC) was required for IFNγ-primed melanoma cells to express a metastatic phenotype after stimulation with TNFα. In conclusion, our study shows that a metastatic phenotype was expressed in B16 murine melanoma cells stimulated with TNFα regardless of whether the cells were primed with IFNγ IFNα or IFNβ. The molecular events leading to the expression of a metastatic phenotype in F10-M3 melanoma cells are represented by: (a) an enhanced expression of p55TNFα receptor in IFNs-primed tumor cells dependent on JAK1 signal transduction pathway; and (b) an intact PKC activity during TNFα stimulation.     

Randomized controlled trial: effects of diet on DNA damage in heavy smokers

We have conducted a randomized trial which investigated the ability of dietary changes (in particular diets rich in cruciferous vegetables and flavonoids), to increase urinary antimutagenicity and inhibit DNA damage in smokers. Ninety heavy smokers were recruited and randomly assigned to three groups, and were given three different diets. The first diet was based on flavonoid-rich foods, particularly cruciferous vegetables, but not based on supplementation; the second was a normal isocaloric diet (with an adequate administration of fruits and vegetables); and the third was based on supplementation of flavonoids in the form of green tea and soy products. DNA adducts were measured by (32)P-postlabelling in exfoliated bladder cells at different times since the start of the trial. In spite of randomization, subjects in the control group smoked more than those in the experimental groups, and this can explain the higher adduct levels at baseline. A slight decrease in bulky DNA adducts in exfoliated bladder cells was observed after 1 year since the end in the supplementation group and after 1 month in white blood cells. The only statistically significant association was found in a regression model that adjusted for smoking, in which the increase in flavonoid intake was associated with a decrease in adducts after 1 year (P = 0.02). These data suggest that adherence to a diet rich in cruciferous vegetables and flavonoids might reduce genotoxicity in the human urinary bladder of smokers, but they should be interpreted with caution owing to small numbers and the uneven distribution of smoking habits in the experimental groups. Smoking is the most important single preventable cause of cancer; at the present stage of knowledge it is totally unlikely that certain dietary habits can seriously counteract the effects of tobacco smoking.     

First national survey of antibiotic susceptibility of the Bacteroides fragilis group: emerging resistance to carbapenems in Argentina

The antibiotic susceptibility rates of 363 clinical Bacteroides fragilis group isolates collected from 17 centers in Argentina during the period from 2006 to 2009 were as follows: piperacillin-tazobactam, 99%; ampicillin-sulbactam, 92%; cefoxitin, 72%; tigecycline, 100%; moxifloxacin, 91%; and clindamycin, 52%. No metronidazole resistance was detected in these isolates during this time period. Resistance to imipenem, doripenem, and ertapenem was observed in 1.1%, 1.6%, and 2.3% of B. fragilis group strains, respectively. B. fragilis species showed a resistance profile of 1.5% to imipenem, 1.9% to doripenem, and 2.4% to ertapenem. This is the first report of carbapenem resistance in Argentina. The cfiA gene was present in 8 out of 23 isolates, all of them belonging to the B. fragilis species and displaying reduced susceptibility or resistance to carbapenems (MICs ≥ 4 μg/ml). Three out of eight cfiA-positive isolates were fully resistant to carbapenems, while 5 out of 8 isolates showed low-level resistance (MICs, 4 to 8 μg/ml). The inhibition by EDTA was a good predictor of the presence of metallo-β-lactamases in the fully resistant B. fragilis strains, but discrepant results were observed for low-level resistant isolates. B. fragilis was more susceptible to antimicrobial agents than other Bacteroides species. Bacteroides vulgatus species was the most resistant to ampicillin-sulbactam and piperacillin-tazobactam, and B. thetaiotaomicron/ovatus strains showed the highest level of resistance to carbapenems, with an unknown resistance mechanism. B. vulgatus and the uncommon non-Bacteroides fragilis species were the most resistant to moxifloxacin, showing an overall resistance rate of 15.1%.     

Clinical and socioeconomic impact of pediatric seasonal and pandemic influenza

Influenza is frequent among otherwise healthy day-care and school-aged children. Recent studies have demonstrated its significant effect on various outcome factors, including significantly more school and parental work absenteeism, and secondary illnesses among family members. Other studies have shown that the potential benefit of vaccinating children against influenza extends to other members of their families, thus supporting earlier economic modeling analyses of immunization programs. Although there are some differences in the clinical and socio-economic impact of seasonal and pandemic influenza, the benefits of vaccination are similar in both cases. The vaccination of otherwise healthy children may significantly reduce direct and indirect influenza-related costs, which supports the recommendation to make wider use of influenza vaccine in healthy children of any age in order to reduce the burden of infection on the community.     

Effect of copper on ion content in isolated mantle cells of the marine clam Mesodesma mactroides

The effect of copper on ion content (Na(+), K(+), Ca(2+), and Cl(-)) was evaluated in isolated mantle gills of the marine clam Mesodesma mactroides. Clams were collected at the Mar Grosso Beach (S?o José do Norte, Rio Grande do Sul [RS], southern Brazil), cryoanesthetized, and had their mantles dissected. Mantle cells were isolated and incubated in a calcium-free phosphate solution without (control) or with Cu (CuCl(2)). Cells were exposed to Cu for 1 h (5 μM) or 3 h (2.5 and 5 μM). In cells incubated with 2.5 μM Cu, a significant decrease in intracellular Cl(-) content was observed. However, in cells incubated with 5.0 μM Cu, significant reductions in Na(+), K(+), and Cl(-) intracellular content were observed. Given the mechanisms involved in ion transport in mantle cells of the marine clam M. mactroides, the findings described here suggest that Cu exposure inhibits carbonic anhydrase and Na(+)/K(+) -ATPase activity. Also, it can be suggested that Cu is competing with Na(+) for the same mechanisms of ion transport in the cell membrane, such as the Na(+) channels and the Na(+)/K(+)/2Cl(-) cotransporter. Results from the present study also clearly indicate that processes involved in cellular anion regulation are more sensitive to Cu exposure than those associated with the cellular cation regulation. Characterization of sites for Cu accumulation and toxicity in aquatic animals is important for derivation of metal binding constants at the biotic ligand. Also, identification of the mechanism of metal toxicity is needed for modeling metal accumulation in the biotic ligand and its consequent toxicity. Therefore, the findings reported here are extremely valuable for the development of a biotic ligand model version for marine and estuarine waters.     

Validated stability-indicating HPLC method for the determination of pridinol mesylate. Kinetics study of its degradation in acid medium

The stability of pridinol mesylate (PRI) was investigated under different stress conditions, including hydrolytic, oxidative, photolytic and thermal, as recommended by the ICH guidelines. Relevant degradation was found to take place under acidic (0.1N HCl) and photolytic (visible and long-wavelength UV-light) conditions, both yielding the product resulting from water elimination (ELI), while submission to an oxidizing environment gave the N-oxidation derivative (NOX). The standards of these degradation products were synthesized and characterized by IR, (1)H and (13)C NMR spectroscopy. A simple, sensitive and specific HPLC method was developed for the quantification of PRI, ELI and NOX in bulk drug, and the conditions were optimized by means of a statistical design strategy. The separation employs a C(18) column and a 51:9:40 (v/v/v) mixture of MeOH, 2-propanol and potassium phosphate solution (50mM, pH 6.0), as mobile phase, delivered at 1.0 ml min(-1); the analytes were detected and quantified at 220 nm. The method was validated, demonstrating to be accurate and precise (repeatability and intermediate precision levels) within the corresponding linear ranges of PRI (0.1-1.5 mg ml(-1); r=0.9983, n=18) and both impurities (0.1-1.3% relative to PRI, r=0.9996 and 0.9995 for ELI and NOX, respectively, n=18). Robustness against small modifications of pH and percentage of the aqueous mobile phase was ascertained and the limits of quantification of the analytes were also determined (0.4 and 0.5 microg ml(-1); 0.04% and 0.05% relative to PRI for ELI and NOX, respectively). Peak purity indices (>0.9997), obtained with the aid of diode-array detection, and satisfactory resolution (R(s)>2.0) between PRI and its impurities established the specificity of the determination, all these results proving the stability-indicating capability of the method. The kinetics of the degradation of PRI in acid medium was also studied, determining that this is a first-order process with regards to drug concentration, with an activation energy of 25.5 Kcal mol(-1) and a t(1/2)=10,830 h, in 0.1N HCl at 38 degrees C.