Plasma IP-10, apoptotic and angiogenic factors associated with fatal cerebral malaria in India

Background

Knowledge on insecticide resistance in target species is a basic requirement to guide insecticide use in malaria control programmes. Malaria transmission in the Mekong region is mainly concentrated in forested areas along the country borders, so that decisions on insecticide use should ideally be made at regional level. Consequently, cross-country monitoring of insecticide resistance is indispensable to acquire comparable baseline data on insecticide resistance.

Methods

A network for the monitoring of insecticide resistance, MALVECASIA, was set up in the Mekong region in order to assess the insecticide resistance status of the major malaria vectors in Cambodia, Laos, Thailand, and Vietnam. From 2003 till 2005, bioassays were performed on adult mosquitoes using the standard WHO susceptibility test with diagnostic concentrations of permethrin 0.75% and DDT 4%. Additional tests were done with pyrethroid insecticides applied by the different national malaria control programmes.

Results

Anopheles dirus s.s., the main vector in forested malaria foci, was susceptible to permethrin. However, in central Vietnam, it showed possible resistance to type II pyrethroids. In the Mekong delta, Anopheles epiroticus was highly resistant to all pyrethroid insecticides tested. It was susceptible to DDT, except near Ho Chi Minh City where it showed possible DDT resistance. In Vietnam, pyrethroid susceptible and tolerant Anopheles minimus s.l. populations were found, whereas An. minimus s.l. from Cambodia, Laos and Thailand were susceptible. Only two An. minimus s.l. populations showed DDT tolerance. Anopheles vagus was found resistant to DDT and to several pyrethroids in Vietnam and Cambodia.

Conclusion

This is the first large scale, cross-country survey of insecticide resistance in Anopheles species in the Mekong Region. A unique baseline data on insecticide resistance for the Mekong region is now available, which enables the follow-up of trends in susceptibility status in the region and which will serve as the basis for further resistance management. Large differences in insecticide resistance status were observed among species and countries. In Vietnam, insecticide resistance was mainly observed in low or transmission-free areas, hence an immediate change of malaria vector control strategy is not required. Though, resistance management is important because the risk of migration of mosquitoes carrying resistance genes from non-endemic to endemic areas. Moreover, trends in resistance status should be carefully monitored and the impact of existing vector control tools on resistant populations should be assessed.     

Quantitation of dissolved gas content in emulsions and in blood using mass spectrometric detection

Quantitation of dissolved gases in blood or in other biological media is essential for understanding the dynamics of metabolic processes. Current detection techniques, while enabling rapid and convenient assessment of dissolved gases, provide only direct information on the partial pressure of gases dissolved in the aqueous fraction of the fluid. The more relevant quantity known as gas content, which refers to the total amount of the gas in all fractions of the sample, can be inferred from those partial pressures, but only indirectly through mathematical modeling. Here we describe a simple mass spectrometric technique for rapid and direct quantitation of gas content for a wide range of gases. The technique is based on a mass spectrometer detector that continuously monitors gases that are rapidly extracted from samples injected into a purge vessel. The accuracy and sample processing speed of the system is demonstrated with experiments that reproduce within minutes literature values for the solubility of various gases in water. The capability of the technique is further demonstrated through accurate determination of O(2) content in a lipid emulsion and in whole blood, using as little as 20 μL of sample. The approach to gas content quantitation described here should greatly expand the range of animals and conditions that may be used in studies of metabolic gas exchange, and facilitate the development of artificial oxygen carriers and resuscitation fluids.     

The co-distribution of Plasmodium falciparum and hookworm among African schoolchildren

Background

On the island of Bioko (Equatorial Guinea), insecticide-treated nets (ITNs) have been the main tool used to control malaria over the last 13 years. In 2004, started an indoor residual spraying (IRS) campaign to control malaria. The purpose of this study is to asses the impact of the two control strategies on the island of Bioko (Equatorial Guinea), with regards to Plasmodium infection and anaemia in the children under five years of age.

Methods

Two transversal studies, the first one prior to the start of the IRS campaign and the second one year later. Sampling was carried out by stratified clusters. Malaria infection was measured by means of thick and thin film, and the packed cell volume (PCV) percentage. Data related to ITN use and information regarding IRS were collected. The Pearson's chi-square and logistic regression statistical tests were used to calculate odds ratios (OR)

Results

In the first survey, 168 children were sampled and 433 children in the second one. The prevalence of infection was 40% in 2004, and significantly lower at 21.7% in 2005. PCV was 41% and 39%, respectively. 58% of the children surveyed in 2004 and 44.3% in 2005 had slept under an ITN. 78% of the dwellings studied in 2005 had been sprayed. In the 2005 survey, sleeping without a mosquito net meant a risk of infection 3 times greater than sleeping protected with a net hanged correctly and with no holes (p < 0.05).

Conclusion

IRS and ITNs have proven to be effective control strategies on the island of Bioko. The choice of one or other strategy is, above all, a question of operational feasibility and availability of local resources.     

Skin allograft maintenance in a new synchimeric model system of tolerance.

Treatment of mice with a single donor-specific transfusion plus a brief course of anti-CD154 mAb uniformly induces donor-specific transplantation tolerance characterized by the deletion of alloreactive CD8+ T cells. Survival of islet allografts in treated mice is permanent, but skin grafts eventually fail unless recipients are thymectomized. To analyze the mechanisms underlying tolerance induction, maintenance, and failure in euthymic mice we created a new analytical system based on allo-TCR-transgenic hemopoietic chimeric graft recipients. Chimeras were CBA (H-2(k)) mice engrafted with small numbers of syngeneic TCR-transgenic KB5 bone marrow cells. These mice subsequently circulated a self-renewing trace population of anti-H-2(b)-alloreactive CD8+ T cells maturing in a normal microenvironment. With this system, we studied the maintenance of H-2(b) allografts in tolerized mice. We documented that alloreactive CD8+ T cells deleted during tolerance induction slowly returned toward pretreatment levels. Skin allograft rejection in this system occurred in the context of 1) increasing numbers of alloreactive CD8+ cells; 2) a decline in anti-CD154 mAb concentration to levels too low to inhibit costimulatory functions; and 3) activation of the alloreactive CD8+ T cells during graft rejection following deliberate depletion of regulatory CD4+ T cells. Rejection of healed-in allografts in tolerized mice appears to be a dynamic process dependent on the level of residual costimulation blockade, CD4+ regulatory cells, and activated alloreactive CD8+ thymic emigrants that have repopulated the periphery after tolerization.     

Connectivity in piping plovers: Do breeding populations have distinct winter distributions?

Resightings of uniquely marked birds from 2001 to 2008 were used to determine winter distributions of 4 breeding populations of a species at risk, the piping plover (Charadrius melodus). Although considerable overlap exists, a distinct pattern in winter distributions was evident. Birds originating from eastern Canada wintered farthest north compared to other populations. Most individuals from the United States Great Lakes were found in South Carolina and Georgia in winter, whereas birds from eastern Canada were found primarily in North Carolina. Although the great majority of birds marked in Prairie Canada were observed wintering in Texas, particularly southern Texas, breeding plovers from the United States Great Plains were more widely distributed on the gulf coast from Florida to Texas. Very few large-scale movements of individuals in winter were reported either within or between years. This study highlights the significance of geographic regions for eastern Canada, the United States Great Lakes, the United States Great Plains, and Prairie Canada populations, and demonstrates relatively high winter site fidelity. This information will help focus conservation efforts for specific breeding populations during the winter. © 2011 The Wildlife Society.