Changes in mercury distribution and its body burden in delphinids affected by a morbillivirus infection: Evidences of methylmercury intoxication in Guiana dolphin

An unusual mortality event (UME) attributed to morbillivirus infection was identified in two Guiana dolphin populations from the Southeastern Brazilian coast. The aim of this study was to characterize total mercury (THg), methylmercury (MeHg) and selenium (Se) bioaccumulation and body burden in Guiana dolphins from Sepetiba Bay (RJ) collected before (n = 61) and during the UME (n = 20). Significantly lower Se concentrations were found in the livers of individuals collected during the UME (Mann-Whitney test; p = 0.03), probably due to impairment of the detoxification process in the liver. There were differences in THg and Se concentrations in the organs and tissues of individuals (Kruskal-Wallis test, p < 0.05), but not MeHg (Kruskal-Wallis test, p = 0.07). For THg, the liver showed the higher concentrations and differed among organs and tissues analyzed such as blubber (Tukey's test for unequal N; p = 0.003). For Se concentrations, the skin and kidney presented the higher concentrations and varied among other tissues/organs, like muscle (Tukey's test for unequal N; p = 0.02). Differences in body burdens were observed among specimens collected previously and during the UME probably due to the remobilization and transport of the muscle-stored MeHg to other tissues/organs. This abrupt input of MeHg into the bloodstream may cause serious health damage. Indeed, evidences of methylmercury intoxication was observed in Guiana dolphins in Sepetiba Bay. In conclusion, bioaccumulation patterns, the detoxification process and body burden were affected by morbillivirus.

Effect of immunostimulatory feed supplements on the development of acquired immunity in rainbow trout (Oncorhynchus mykiss)

Immunostimulatory feed supplements are an increasingly common feature of aquaculture management and their benefit has been confirmed for a wide area of products. However, these investigations have often focused on the benefit of these supplements on the innate immune system. In the current project, we investigated a mixture of two commercial feed supplements (Biotronic^® Top 3 and Levabon^® Aquagrow E) with a known protective effect against bacterial infections. The effect of the supplemented diet on antibody titters of Oncorhynchus mykiss vaccinated against Yersinia ruckeri was determined by ELISA. Furthermore, an infection trial was performed to confirm the effect of the supplements on the survival of the fish. Finally, their effects on the growth parameters of the fish were also determined. The results from this study found no significant effect on the general antibody titters. However, when considering only the titters of specific anti-Y ruckeri antibodies, the supplemented feed was associated with an improved response to the vaccine, significantly better than in the fish that had received the control feed.

The Allium cepa bioassay to evaluate landfarming soil, before and after the addition of rice hulls to accelerate organic pollutants biodegradation

Landfarming is a soil bioremediation technology practiced by oil refineries in order to reduce or eliminate hydrocarbons from petroleum sludge. The goal of the current study was to use Allium cepa bioassay to assess landfarming and landfarming with rice hulls amendment before and after hydrocarbons biodegradation assay in the laboratory. Three cytogenetic endpoints were used: mitotic and chromosome abnormalities (MCA), micronucleus (MN) and nuclear buds (NB). Landfarming presented 13.5 g/kg of total petroleum hydrocarbons (TPHs) and caused strong clastogenic and mutagenic effects (p<0.05) in A. cepa. After 108 days of biodegradation, the landfarming reached the rate of 26.30 mmol of CO(2) released, the concentration of TPHs decreased by 27% and there was significant reduction in MCA, MN and NB. Landfarming treated with rice hulls had the highest release of CO(2), 110.9 mmol, associated with a remarkable reduction in TPHs concentration, 59%, and had the highest decrease in MCA, MN and NB (p>0.05). Our findings showed that the use of rice hulls accelerated the biodegradation efficacy of landfarming and reduced their clastogenicity, indicating that supplementary treatments are important to improve the efficiency of bioremediation processes.

Methionine depletion enhances the antitumoral efficacy of cytotoxic agents in drug-resistant human tumor xenografts

Efficacy of chemotherapy is limited in numerous tumors by specific cellular mechanisms that inactivate cytotoxic antitumoral drugs, such as ATP-dependent drug efflux and/or drug detoxification by glutathione. In reducing ATP pools and/or glutathione synthesis, it might be possible to enhance the efficacy of drugs affected by such resistance mechanisms. Reduction of the ATP pool and glutathione content is achievable in cancer cells by depleting the exogenous methionine (Met) supply and ethionine. Thus, the rationale for the present study was to use Met depletion to decrease the ATP and glutathione pools so as to sensitize tumors refractory to cytotoxic anticancer drugs. Met depletion was achieved by feeding mice a methionine-free diet supplemented with homocysteine. The effects of Met depletion combined with ethionine and/or chemotherapeutic agents were studied using human solid cancers xenografted into nude mice. TC71-MA (a colon cancer) SCLC6 (a small cell lung cancer), and SNB19 (a glioma) were found to be refractory to cisplatin, doxorubicin, and carmustine, respectively. These three drugs are used to treat such tumors and are dependent for their activity on the lack of cellular ATP- or glutathione-dependent mechanisms of resistance. TC71-MA, SCLC6, and SNB19 were Met dependent because their proliferation in vitro and growth in vivo were reduced by Met depletion. Cisplatin was inactive in the treatment of TC71-MA colon cancer, whereas a methionine-free diet, alone or in combination with ethionine, prolonged the survival of mice by 2-fold and 2.8-fold, respectively. When all three approaches were combined, survival was prolonged by 3.3-fold. Doxorubicin did not affect the growth of SCLC6, a MDR1-MRP-expressing tumor. A Met-deprived diet and ethionine slightly decreased SCLC6 growth and, in combination with doxorubicin, an inhibition of 51% was obtained, with survival prolonged by 1.7-fold. Combined treatment produced greater tumor growth inhibition (74%) in SCLC6-Dox, a SCLC6 tumor pretreated with doxorubicin. Growth of SNB19 glioma was not inhibited by carmustine, but when it was combined with Met depletion, survival duration was prolonged by 2-fold, with a growth inhibition of 80%. These results indicate the potential of Met depletion to enhance the antitumoral effects of chemotherapeutic agents on drug-refractory tumors.

Doppler echocardiographic indexes and 24-h ambulatory blood pressure data in sedentary middle-aged men presenting exaggerated blood pressure response during dynamical exercise test

Previous studies have pointed out that exaggerated blood pressure (BP) response during physical exercise could be an early marker of essential hypertension. Apparently some of the exaggerated BP responders present changes in the heart geometry and function that are usually found in the early course of the hypertensive disease. To evaluate the association between exaggerated BP response and these changes, we submitted 20 normotensive men presenting elevated BP response during bicycle exercise (hyperreactive group, systolic BP > or = 220 mmHg at maximal workload) to 24-h ambulatory blood pressure monitoring (ABPM) and to two-dimensionally guided M-mode echocardiography and pulsed Doppler. The results from this group were contrasted with those of a comparable group, which otherwise, presented normal BP response during the same procedure (control group, systolic BP < or = 210 mmHg at maximal workload). The ABPM measurements were normal and analogous between the two groups: the mean 24-h systolic blood pressure (SBP) was respectively 126 +/- 6 mmHg and 129 +/- 5 mmHg, diastolic blood pressure (DBP) 82 +/- 4 mmHg in both groups, and heart rate (HR), respectively 76 +/- 9 and 74 +/- 7 bpm. The univariate correlation (R) between the maximal BP response during bicycle exercise and BP measurements in the ABPM were in general weak, and as a whole, the hyperreactive group presented the weakest correlation coefficients. M-mode echocardiographic data such as the left ventricular mass index (LVMI, 80 +/- 10 vs. 81 +/- 11 g/m2), posterior wall and interventricular septal thickness (PWT, 8.8 +/- 0.6 vs. 8.6 +/- 0.7 mm; IVST, 9.0 +/- 0.4 vs. 8.8 +/- 0.6) were also normal and comparable between the groups. LV systolic functional indexes such as fractional shortening (LVFS, 39 +/- 2.8 vs. 40 +/- 3.5%) and ejection fraction (LVEF, 70 +/- 3.5 vs. 71 +/- 3.7%) were also normal and similar. Doppler-derived LV diastolic functional indexes such as the peak velocity of early flow divided by the peak velocity of late flow (RE/A) and isovolumetric relaxation time (IVRT) were also equivalent (RE/A, both 1.3 +/- 0.2, IVRT 79 +/- 7 vs. 81 +/- 6 msec). These results support the concept that an exaggerated BP elevation during physical activity, when not accompanied of higher levels of BP during daily activities are not associated with changes in the heart geometry or in the ventricular function, and might represent an hemodynamical behavior of limited pathological and clinical importance. These conclusions must be taken cautiously since personal characteristics such as life style, family history of hypertension, gender, race and also the levels of BP chosen to delimit a normal and an exaggerated BP response might be important factors determining the consequences of the hyperreactive behavior.