Combining multi-isotopic and molecular source tracking methods to identify nitrate pollution sources in surface and groundwater.

Nitrate (NO3-) pollution adversely impacts surface and groundwater quality. In recent decades, many countries have implemented measures to control and reduce anthropogenic nitrate pollution in water resources. However, to effectively implement mitigation measures at the origin of pollution,the source of nitrate must first be identified. The stable nitrogen and oxygen isotopes of NO3- (ẟ15N and ẟ18O) have been widely used to identify NO3- sources in water, and their combination with other stable isotopes such as boron (ẟ11B) has further improved nitrate source identification. However, the use of these datasets has been limited due to their overlapping isotopic ranges, mixing between sources, and/or isotopic fractionation related to physicochemical processes. To overcome these limitations, we combined a multi-isotopic analysis with fecal indicator bacteria (FIB) and microbial source tracking (MST) techniques to improve nitrate origin identification. We applied this novel approach on 149 groundwater and 39 surface water samples distributed across Catalonia (NE Spain). A further 18 wastewater treatment plant (WWTP) effluents were also isotopically and biologically characterized. The groundwater and surface water results confirm that isotopes and MST analyses were complementary and provided more reliable information on the source of nitrate contamination. The isotope and MST data agreed or partially agreed in most of the samples evaluated (79 %). This approach was especially useful for nitrate pollution tracing in surface water but was also effective in groundwater samples influenced by organic nitrate pollution. Furthermore, the findings from the WWTP effluents suggest that the use of literature values to define the isotopic ranges of anthropogenic sources can constrain interpretations. We therefore recommend that local sources be isotopically characterized for accurate interpretations. For instance, the detection of MST inferred animal influence in some WWTP effluents, but the ẟ11B values were higher than those reported in the literature for wastewater. The results of this study have been used by local water authorities to review uncertain cases and identify new vulnerable zones in Catalonia according to the European Nitrate Directive (91/676/CEE).

Shear-thickening fluids in biologically relevant agents.

BACKGROUND: The rheology of shear thickening fluids is well characterized for many physical applications, however the literature surrounding biologically or cryobiologically compatible shear thickening fluids is less well understood. OBJECTIVE: This study examined fluids consisting of corn-derived hydroxyethyl starch with a variety of sugars and cryoprotectants to characterize their shear-rate viscosity relationship. The objective was to establish if cryobiologically relevant materials could be used to afford biologics protection through shear-thickening. RESULTS: Fluids consisting of 50% hydroxyethyl starch by weight exhibited shear thickening with a variety of cryoprotectants. Lowering the temperature of the fluid both reduced critical shear rates and enhanced thickening magnitude. Starch derived from corn, wheat, and rice all exhibited non-Newtonian shear-dependent viscosity behaviour at 50% by weight in water. Between the starch sources however, the shear-rate viscosity relationship varied widely, with wheat-derived starch shear thinning, and the remaining starches forming shear thickening fluids. Different starch sources had different baseline viscosities, critical shear rates, and rates of viscosity increase. CONCLUSIONS: This study established that shear thickening is compatible with cryobiologically relevant agents, particularly so at lower temperatures. This forms the basis for harnessing these phenomena in biological processes such as cryopreservation.

Local ice therapy during bouts of acute gouty arthritis.

OBJECTIVE: To evaluate the effect of local application of ice on duration and severity of acute gouty arthritis. METHODS: Nineteen patients with acute gout were enrolled and randomized into 2 groups. Group A (n = 10) received topical ice therapy, oral prednisone 30 mg PO tapered to 0 over 6 days and colchicine 0.6 mg/day. Group B was the control group (n = 9), given the same regimen but without the ice therapy. The patients were followed for one week. RESULTS: The mean reduction in pain for those patients treated with ice therapy was 7.75 cm (on 10 cm visual analog scale) with standard deviation +/- 2.58 compared with 4.42 cm (+/- SD 2.96) for the control group. Using a Wilcoxon rank-sum test there was a significant difference (p = 0.021 ) in pain reduction between the ice therapy and control groups. Joint circumference and synovial fluid volume also tended to be more effectively reduced after one week of therapy in the ice group compared with controls, but these did not achieve statistical significance. CONCLUSION: The group treated with ice had a significantly greater reduction in pain compared with the control group. Although the clinical improvement was impressive, due to the small sample size we could not show statistically significant improvement in all the variables that tended to suggest that effect was more than simply analgesic. Cold applications may be a useful adjunct to treatment of acute gouty arthritis.

Utilidad de la telerradiografía de tórax en pacientes hospitalizados / Usefulness of the chest roentgenogram in hospitalized patients

Objetivo. Evaluar la utilidad de la telerradiografía de tórax (TRT) en enfermos hospitalizados, en términos de su influencia en el plan diagnóstico y terapéutico anticipado por el clínico. Diseño. Encuesta a un grupo de médicos residentes en medicina interna encargados de los sectores de hospitalización del Instituto Nacional de la Nutrición Salvador Zubirán. Se aplicaron dos tipos de cuestionarios: uno al momento de la solicitud de una TRT (motivo de la solicitud, la probabilidad de un hallazgo anormal y su decisión terapéutica) y otro, una vez conocido el resultado de la radiografía, averiguando lo inseperado del hallazgo radiológico y su influencia en la terapéutica. Se analizaron las respuestas a estos cuestionarios a la luz de la interpretación de la placa por un radiólogo. Resultados. Se analizaron 100 encuestas. La TRT descartó la sospecha anticipada por el médico de aparición de un nuevo evento pulmonar (55 por ciento de las veces) o de una mala evolución de una enfermedad pulmonar ya conocida (en el 50 por ciento). En cambio, la TRT corroboró la ausencia de un nuevo evento pulmonar, de una mejor o estable evolución de una enfermedad pulmonar ya conocida, anticipados por el médico, en el 92 por ciento de los casos. La TRT determinó un cambio en el plan terapéutico anticipado por el clínico en el 61 por ciento de las veces. Conclusión. La TRT en pacientes hospitalizados es de utilidad práctica al médico al evitar sobrediagnósticos clínicos y el consecuente tratamiento innecesario de sus enfermos