Risk assessment of ionizing radiation and radiological thresholds to compound an environmental baseline for the unconventional gas industry.

The exploration of unconventional hydrocarbons may be very effective in promoting economic development and confronting energy crisis around the world. However, the environmental risks associated with this practice might be an impediment if not adequately dimensioned. In this context, naturally occurring radioactive materials and ionizing radiation are sensitive aspects in the unconventional gas industry that may compromise the environmental sustainability of gas production and they should be properly monitored. This paper provides a radioecological assessment of the São Francisco Basin (Brazil) as part of an environmental baseline evaluation regarding the Brazilian potential for exploring its unconventional gas reserves. Eleven and thirteen samples of surface waters and groundwater were analyzed for gross alpha and beta using a gas flow proportional counter. A radiological background range was proposed using the ± 2 Median Absolute Deviation method. Using geoprocessing tools, the annual equivalent doses and lifetime cancer risk indexes were spatialized. Gross alpha and beta background thresholds in surface water ranged from 0.04-0.40 Bq L-1 to 0.17-0.46 Bq L-, respectively. Groundwater radiological background varies from 0.006-0.81 Bq L-1 to 0.06-0.72 Bq L-1 for gross alpha and beta, respectively. All environmental indexes are relatively higher in the south of the basin, probably a direct response to the local volcanic formations. Traçadal fault and local gas seepages might also influence the gross alpha and beta distribution. All samples have radiological indexes below the environmental thresholds, and should remain at acceptable levels with the development of the unconventional gas industry in Brazil.

Farnesol increases the susceptibility of Burkholderia pseudomallei biofilm to antimicrobials used to treat melioidosis.

AIMS: The aim of this study was to analyse the in vitro activity of farnesol alone and combined with the antibacterial drugs amoxicillin, doxycycline, ceftazidime and sulfamethoxazole-trimethoprim against Burkholderia pseudomallei biofilms. METHODS AND RESULTS: Susceptibility was assessed by the broth microdilution test and cell viability was read with the oxidation-reduction indicator dye resazurin. The biofilms were evaluated through three microscopic techniques (optical, confocal and electronic microscopy). The minimum biofilm erradication concentration (MBEC) for farnesol was 75-2400 mmol l(-1). In addition, farnesol significantly reduced the MBEC values for ceftazidime, amoxicillin, doxycycline and sulfamethoxazole-trimethoprim by 256, 16, 4 and 4 times respectively (P < 0·05). Optical, confocal and electronic microscopic analyses of farnesol-treated B. pseudomallei biofilms demonstrated that this compound damages biofilm matrix, probably facilitating antimicrobial penetration in the biofilm structure. CONCLUSIONS: This study demonstrated the effectiveness of farnesol against B. pseudomallei biofilms and its potentiating effect on the activity of antibacterial drugs, in particular ceftazidime, amoxicillin, doxycycline and sulfamethoxazole-trimethoprim. SIGNIFICANCE AND IMPACT OF THE STUDY: The intrinsic antimicrobial resistance of B. pseudomallei is a serious challenge for the treatment of melioidosis. Thus, this paper reports the inhibitory potential of farnesol against B. pseudomallei biofilms, as well as highlights the favourable pharmacological interaction of farnesol with antibiotics tested, not only on cell viability, but also in the structural morphology of biofilms.

Dietary sodium intake and cardiac nerve cell hypertrophy in Wistar rats.

We determined the effect of dietary sodium intake (0.15 and 8% NaCl) on the cardiac neuron size of normotensive 3-week old Wistar rats. An increase in dietary sodium for 48 weeks induced an increase in neuronal size. The number of large neurons (larger than 500 microns 2) increased significantly (chi-square test) in rats ingesting 8% NaCl in their food. The rats presented hypertension (128 +/- 9 vs 134 +/- 16 mmHg; difference not significant, Student t-test) and a statistically significant increase in cardiac muscle mass (1.6 +/- 0.1 vs 2.0 +/- 0.2 mg/g of rat). We conclude that food sodium can significantly increase cardiac nerve cell size and this trophic response occurs concomitantly with an increase of cardiac muscle mass.

Dietary sodium intake and cardiac nerve cell hypertrophy in Wistar rats

We determined the effect of dietary sodium intake (0.15 and 8 per cent NACl) on the cardiac neuron size of normotensive 3-week old Wistar rats. An increase in dietary sodium for 48 weeks induced an increase in neuronal size. The number of large neurons (larger than 500 muM2) increased significantly (chi-square test) in rats ingesting 8 per cent NaCl in their food. The rats presented hypertension (128 ñ 9 vs 134 ñ 16 mmHg; difference not significant, Student t-test) and a statistically significant increase in cardiac muscle mass (1.6 ñ 0.1 vs 2.0 ñ 0.2 mg/g of rat). We conclude that food sodium can significantly increase cardiac nerve cell size and this trophic response occurs concomitantly with an increase of cardiac muscle mass.