Efecto del tipo y del número de lavados en la eficacia de mosquiteros tratados con deltametrina de larga duración para el control de Aedes aegypti en Girardot, Colombia / Effect of the type and number of washes in the efficacy of long lasting insecticidal nets for Aedes aegypti control in Girardot, Colombia

Resumen Introducción. El uso de mosquiteros tratados con insecticida en fórmulas de larga duración ha demostrado resultados prometedores en el control de Aedes aegypti. Objetivo. Evaluar la eficacia de mosquiteros impregnados con deltametrina en una fórmula de larga duración para el control de A. aegypti en Girardot, Colombia, después de tres lavados. Materiales y métodos. Se hicieron bioensayos de eficacia de los mosquiteros contra A. aegypti silvestres después de utilizar los siguientes tres productos de lavado, siguiendo la metodología de la Organización Mundial de la Salud: detergente en polvo, detergente en polvo y blanqueador, y jabón de barra, todos utilizados hasta en 20 lavados. Resultados. El tipo de producto de lavado y el número de lavados afectaron significativamente la eficacia de los mosquiteros impregnados con deltametrina. El lavado con jabón de barra presentó el mayor efecto, pues en tan solo seis lavados la mortalidad bajó a 50 % (25/50), en contraste con 66 % (33/50 de mortalidad después del lavado con detergente en polvo y de 84 % (42/50) después del lavado con detergente y blanqueador. En cuanto al número de lavados, el jabón en barra también causó una mayor reducción de la eficacia: a 68 % con solo tres lavados. Conclusión. La eficacia de los mosquiteros impregnados con deltametrina de larga duración en el control de A. aegypti varió con el tipo de producto de lavado y el número de lavados, siendo el jabón en barra el que redujo su eficacia en mayor medida. Se requieren nuevos estudios para establecer la disminución en la concentración del insecticida entre lavados.

Abstract Introduction: The use of long lasting insecticidal materials has shown promising results in the control of Aedes aegypti. Objective: To evaluate the efficacy of long-lasting insecticidal nets (PermaNet®) for Aedes aegypti control after three washing treatments in the city of Girardot, Colombia. Materials and methods: Standard bioassays were conducted with the nets following the World Health Organization protocols using wild A. aegypti after three washing treatments: (1) Detergent powder, (2)detergent powder and bleach, and (3) bar soap, until completing 20 washes. Results: The type and number of wash treatments had a significant effect on net efficacy. Greater effects in the insecticide bioavailability were seen for the bar soap treatment. After six washes, mortality decreased by 50% (25/50), vs 66% (33/50) for the detergent powder and 84% (42/50) for the detergent powder and bleach treatments. Regarding the number of washes, the bar soap treatment reduced the efficacy to 68% after only three washes. Conclusion: The effectiveness of long-lasting insecticidal nets (PermaNet 2.0) for A. aegypti control varied in relation to the treatment and number of washes. The bar soap treatment resulted in the greatest reduction of mortality. Further studies on insecticidal reductions are needed under local conditions.

Synergic actions of polyphenols and cyanogens of peanut seed coat (Arachis hypogaea) on cytological, biochemical and functional changes in thyroid.

In animals, long-term feeding with peanut (Arachis hypogaea) seed coats causes hypertrophy and hyperplasia of the thyroid gland. However, to date there have been no detailed studies. Here, we explored the thyroidal effects of dietary peanut seed coats (PSC) in rats. The PSC has high levels of pro-goitrogenic substances including phenolic and other cyanogenic constituents. The PSC was mixed with a standard diet and fed to rats for 30 and 60 days, respectively. Animals fed with the PSC-supplemented diet showed a significant increase in urinary excretion of thiocyanate and iodine, thyroid enlargement, and hypertrophy and/or hyperplasia of thyroid follicles. In addition, there was inhibition of thyroid peroxidase (TPO) activity, 5’-deiodinase-I (DIO1) activity, and (Na+-K+)-ATPase activity in the experimental groups of rats as compared to controls. Furthermore, the PSC fed animals exhibited decreased serum circulating total T4 and T3 levels, severe in the group treated for longer duration. These data indicate that PSC could be a novel disruptor of thyroid function, due to synergistic actions of phenolic as well as cyanogenic constituents.

Response surface methodology of nitrilase production by recombinant Escherichia coli

Growth and nitrilase production by recombinant Escherichia coli cells harbouring pET 21 (b) plasmid, for the expression of Pseudomonas putida nitrilase were improved using response surface methodology. Central composite design was used for obtaining ideal concentration of critical medium components which include fructose, tryptone, yeast extract and lactose. The optimal values for the concentration of fructose, tryptone, yeast extract and lactose were found to be 1.13, 2.26, 3.25 and 0.9 percent (w/v), respectively. Here, fructose served as carbon source for the growth while lactose was preferably used as inducer for the expression of foreign protein. Yeast extract in the medium was used as a growth promoter while tryptone was added as a major nitrogen source. Using this optimized medium, an experimental growth of 6.67 (OD at 600 nm) and nitrilase activity of 27.13 U/ml was achieved. This approach for medium development led to an enhancement of the growth and enzyme activity by 1.4 and 2.2 times, respectively, as compared to the un-optimized medium.