A mechanism for improved talc pleurodesis via foam delivery.

Talcum powder is recognized as the leading drug for pleurodesis, a treatment of choice for malignant pleural effusions. Recently, it was shown that hydrogel foam delivery systems significantly enhanced the number of adhesions between the chest wall and the lung in a New Zealand rabbit model due to the sol-gel transition. However, many questions still remain regarding the cause of improved efficacy, such as: (1) Would only hydrogel foams improve the efficacy of talc pleurodesis? (2) Is it possible to achieve the same efficacy of hydrogels using non-hydrogel foams? 3) What are the physicochemical properties that can be correlated to the efficacy of talc pleurodesis? In this study, we use non-hydrogel foam formulations to determine the efficacy of pleurodesis. Foam stability and rheology of the formulations were correlated to adhesion formation. The results clearly suggest a correlation of pleurodesis efficacy to the viscosity and modulus of the foam delivery system.

Applying weight gain in Pomacea lineata (Spix 1824) (Mollusca: Prosobranchia) as a measure of herbicide toxicity

Pomacea lineata, um molusco amplamente distribuído e considerado como peste em plantações de arroz no Oriente, pode ser considerado como um valioso recurso para monitorar a qualidade da água no Nordeste do Brasil. Neste trabalho, apresentamos dados que demonstram que o incremento de peso em moluscos neonatos é uma medida consistente que responde eficientemente ao estresse imposto por concentrações tóxicas subletais dos herbicidas Paraquat e Round-up. Os resultados de crescimento para avaliar a toxicidade crônica foram obtidos em experimentos de quatro e quatro, oito, doze e dezesseis dias para Paraquat e Round-up, respectivamente. A maior concentração de efeito não observado (NOEC) e a menor concentração de efeito observado (LOEC) para Paraquat, após 96 horas, foram respectivamente de 0,12 e 0,25 mg/L. Para o Round-up, os valores de NOEC e LOEC estimados foram respectivamente de 0,25 e 0,5 mg/L. Todas as concentrações de Round-up testadas após 192 horas de exposição provocaram diminuições nas taxas de crescimento, sendo significativamente diferentes do controle. Conseqüentemente não pode ser estimado o valor de NOEC. O valor de LOEC foi menor do que 0,12 mg/L. Além disso, não houve nenhuma mortalidade durante o teste. Por conseguinte, nenhum NOEC pôde ser derivado e o LOEC era < 0,12 mg/L. Para as mais baixas concentrações de Paraquat testadas (0,005 mg/L), houve um aumento do crescimento que foi significativamente maior que o controle, sugerindo a ocorrência de um efeito hormético.

Applying weight gain in Pomacea lineata (SPIX 1824) (Mollusca: Prosobranchia) as a measure of herbicide toxicity.

Pomacea lineata, an extremely ubiquitous snail and pest to rice farmers throughout Asia, holds promise as a valuable resource for monitoring water quality in northeast Brazil. In this paper, we present data demonstrating the rate of weight gain in P. lineata neonates as a consistent measure of the stress imposed by sublethal concentrations of the herbicides Paraquat and Round-up. Our secondary agenda is to demonstrate the feasibility of incorporating bioassay into the standard municipal and state procedure of monitoring water quality. Growth data to assess chronic toxicity were generated in experiments of four and four, eight, twelve and sixteen days for Paraquat and Round-up, respectively. We estimated a 96 h no observed effect concentration (NOEC) and lowest observed effect concentration (LOEC) for Paraquat of 0.12 and 0.25 mg/L. The 96 h Round-up data yielded NOEC and LOEC values, respectively, of 0.25 and 0.5 mg/L. All concentrations of Round-up tested for the 192 h exposure yielded significantly lower growth than the control. Consequently, no NOEC could be derived. The LOEC was < 0.12 mg/L. Furthermore, there was no mortality during the test. At the lowest concentrations of Paraquat tested (0.005 mg/L) there was a significant increase in growth compared with the controls, suggesting a hormetic effect.

The impact of depressed pH and elevated aluminum concentrations on specific dynamic action in Somatochlora cingulata (de Selys).

Differences in oxygen consumption attributable to apparent specific dynamic action (SDA) were measured in relation to feeding level in the dragonfly naiad Somatochlora cingulata exposed to low pH and sublethal aluminum concentration plus low pH. The average increases in respiration among the treatments following feeding were 50-60% that of controls. The average treatment peak height ratios (post/prefeeding respiration rates) were proportionately reduced and not significantly different from the average controls indicating that the resting metabolism, rather than SDA, was reduced.

Laboratory measure of an ecosystem response to a sustained stress.

A new method is described for measuring environmental stress through the use of the duckweed (Lemna minor) rhizosphere.