Glutathione and the redox control system trypanothione/trypanothione reductase are involved in the protection of Leishmania spp. against nitrosothiol-induced cytotoxicity

Glutathione is the major intracellular antioxidant thiol protecting mammalian cells against oxidative stress induced by oxygen- and nitrogen-derived reactive species. In trypanosomes and leishmanias, trypanothione plays a central role in parasite protection against mammalian host defence systems by recycling trypanothione disulphide by the enzyme trypanothione reductase. Although Kinetoplastida parasites lack glutathione reductase, they maintain significant levels of glutathione. The aim of this study was to use Leishmania donovani trypanothione reductase gene mutant clones and different Leishmania species to examine the role of these two individual thiol systems in the protection mechanism against S-nitroso-N-acetyl-D,L-penicillamine (SNAP), a nitrogen-derived reactive species donor. We found that the resistance to SNAP of different species of Leishmania was inversely correlated with their glutathione concentration but not with their total low-molecular weight thiol content (about 0.18 nmol/10(7) parasites, regardless Leishmania species). The glutathione concentration in L. amazonensis, L. donovani, L. major, and L. braziliensis were 0.12, 0.10, 0.08, and 0.04 nmol/10(7) parasites, respectively. L. amazonensis, that have a higher level of glutathione, were less susceptible to SNAP (30 and 100 microM). The IC50 values of SNAP determined to L. amazonensis, L. donovani, L. major, and L. braziliensis were 207.8, 188.5, 160.9, and 83 microM, respectively. We also observed that L. donovani mutants carrying only one trypanothione reductase allele had a decreased capacity to survive (approximately 40%) in the presence of SNAP (30-150 microM). In conclusion, the present data suggest that both antioxidant systems, glutathione and trypanothione/trypanothione reductase, participate in protection of Leishmania against the toxic effect of nitrogen-derived reactive species.

[Observations on oviposition, hatching and the life span of Triatoma matogrossensis Leite & Barbosa, 1953 (Hemiptera, Reduviidae) as a function of their feeding on pigeons and rabbits]

A laboratory study was carried out concerning the influence of two kinds of blood-meal on egg laying, egg hatching and life span of Triatoma matogrossensis. 68 couples in 4 different groups with 20, 12, 20 and 16 individuals of each sex per group were formed. Maintained under laboratory conditions groups A1 and A2 were fed on pigeons and groups C1 and C2 were fed on rabbits. In relation to egg laying the best results were found in group A1. No differences on egg hatching were found between the groups fed on rabbits and those fed on pigeons. Concerning the life span, no differences between males and females in the 4 groups were observed but group A1 presented the longest life span and group C2 the shortest.

[Epidemic outbreaks of dermatitis caused by butterflies of the genus Hylesia (Lepidoptera: Hemileucidae) in São Paulo State, Brazil]

Epidemic outbreaks of dermatitis caused by Hylesia sp which occurred in the coastal region of the State of S. Paulo during the period of December 1989 to December 1991 are confirmed. The incident assumed its greatest intensity in Bertioga, in Santos County, where 612 cases were registered. The outbreak also affected 12 other counties in that region and it was estimated that hundred of affected persons sought the Local Health Service Care. The majority presented with erythematous and prutiginous lesions and papula which lasted 7 to 14 days on average. Treatment consisted of systemic administration of antihistamines, and the use of topic corticosteroids and cold compresses. During the above-mentioned period, three epidemic episodes, coinciding with the rainy season (November to January), occurred. They were first observed in the northern part of the coastal area and then spread to the south. Information as to how avoid contact with the moth was the main prophylactic measure. In highly infested buildings the effectiveness of residual insecticide procedure was used in the attempt to reduce the level of moth infestation. Satisfactory results were obtained with deltametrin applied in a dosage of 50 mg/m2 of wall.