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[The characteristics of the epidemic activation of a natural focus of zoonotic cutaneous leishmaniasis in places with a sympatric dissemination of Leishmania major, L. turanica and L. gerbilli].

In 1975-1978 and in 1985-1988 studies of species composition and number of Phlebotomus, R. opimus infestation with L. major, L. turanica and L. gerbilli as well as epidemic activity of the natural foci were performed in the Karshi steppe in Uzbekistan. Typical areas have been compared in the desert, oasis and desert land irrigated for cotton growing. A correlation has been established between the epidemic activity of the natural focus and the nature of epizootic development in R. opimus and species composition of vectors. On desert territories epizootic transmission throughout the whole season develops with the domination of one leishmania species (L. turanica) which is not pathogenic for human beings. Paraphlebotomus are the main vectors transmitting leishmania. In oases epizootic process assumes a two-phase course, with accumulation by the middle of the season L. major species pathogenic for human beings. It is transmitted by P. papatasi. With desert irrigation, the former Phlebotomus species is transformed into the latter one, with the predominance of P. papatasi. Epizootics acquire a stable two-phase nature.

Animals↗
PubMed1990

[The Wesselsbron virus, a new arbovirus for Madagascar].

Wesselsbron virus, an African arbovirus group flavivirus, has been isolated in 1989 for the first time in MADAGASCAR from Aedes circumluteolus collected inside primary forest near the village of MAROVITSIKA. Serological studies in man using haemagglutination inhibition test have permitted to think that Wesselsbron virus have circulated quietly in MADAGASCAR. The detection of Wesselsbron antibodies in Lemurs sets the problem of the biological cycle.

Aedes↗
PubMed1989

[Transmission cycles of arboviruses in Madagascar].

Some arboviruses are highly pathogenic for Men or animals. Arboviruses epidemiological patterns in Madagascar were determined by entomological, serological, and virological surveys. We listed potentials arboviruses vectors in Madagascar. Entomological results generated by us during five years, as well as prior to, are shown. We caught more than 150,000 hematophagous arthropods, belonging to 107 species at least. 3 of these species were new. 4183 inoculation pools were done. We studied serollogically (by HI test) samples collected from 563 animals and 626 Men. Our data, in agreement with others collected from 1965 to 1982, demonstrate that arboviruses circulate in the whole island. Positive reactions were obtained mainly with Flavivirus, in particular with West-Nile. Nine various arboviruses, including dengue-2 virus isolated from an individual having travelled to La Réunion, have been isolated. Dakar-Bat and Mengo virus have been observed. We studied transmission cycles of the following viruses: Babanki, West-Nile, Rift Valley Fever, Crimean-Congo Hemorrhagic Fever, MMP 158, Ngari, Perinet and Andasibe; the last 2 being endemics. In relation to Madagascar biogeographic characteristics (long-term isolation, scarce communications, high endemicity, and low vertebrate density), we evaluated the risk of potential introduction and amplification of various arboviruses (dengue, yellow fever, japanese encephalitis, Sindbis and Chikungunya). The risk is very high for dengue due to the presence of susceptible mosquitoes strains while the virus circulates in East Africa and in the Indian Ocean area. This risk seems to be very low for yellow fever, and intermediate for other arboviruses.

Animals↗
PubMed1989

Autophosphorylation activates the soluble cytoplasmic domain of the insulin receptor in an intermolecular reaction.

The cytoplasmic protein-tyrosine kinase domain of the insulin receptor (residues 959-1355) has been expressed as a soluble protein in Sf9 insect cells via a Baculovirus expression vector (Ellis, L., Levitan, A., Cobb, M.H., and Ramos, P. (1988) J. Virol. 62, 1634-1639). The purified protein is a monomer as judged by its behavior in sucrose gradients and on gel filtration in the presence or absence of protamine. The initial rate of autophosphorylation using 3 mM MgCl2 is increased 20-30-fold by protamine. A maximum of 4-5 mol of phosphate are incorporated per mol of enzyme. The activity of the enzyme as a function of phosphorylation state was studied for three substrates: a synthetic dodecapeptide derived from the sequence of the major autophosphorylation site in the insulin receptor, poly(Glu, Tyr), 4:1, and histone 2B. Autophosphorylation of the protein to a stoichiometry of 4-5 mol of phosphate/mol increases its enzymatic activity as much as 200-fold; a 30-fold increase in activity occurs upon addition of 1 mol of phosphate/mol. The activities of unphosphorylated enzyme with the three substrates are 3.4, 2.3, and 0.44 nmol/min/mg, respectively. The activities of the autophosphorylated enzyme with the three substrates are 175, 274, and 45 nmol/min/mg, respectively. Exposure of the autophosphorylated enzyme to ADP results in a loss of phosphate from the enzyme which is associated with a decrease in enzymatic activity. Autophosphorylation of the kinase in the presence or absence of protamine displays a marked dependence on enzyme concentration. Furthermore, the rate of autophosphorylation decreases as the viscosity of the solution increases. Taken together, these data suggest that phosphorylation occurs via an intermolecular reaction.

Adenosine Diphosphate↗
PubMed1972

A history of Rhodesian sleeping sickness in the Lambwe Valley.

The main events in the spread of Rhodesian sleeping sickness around the eastern shores of Lake Victoria during the 1930s and 1940s are summarized and the history of the disease in the Lambwe Valley area of western Kenya is described since its appearance there in 1959. The area was very receptive to the introduction and dispersal of T. rhodesiense on account of a close association between human communities and their domestic livestock, a large tsetse (Glossina pallidipes) population, and game animals. The possible origins of the first Lambwe Valley disease focus and the epidemiological significance of the main elements of the Lambwe environment (man, tsetse, game animals) are discussed in relation to the consolidation and spread of the disease throughout the area.Between 1968 and 1971 there was a marked decline in the incidence of the disease, probably as a result of tsetse-control operations that included ground and aerial application of insecticides, bush clearance, and the efforts of the Kenya Game Department to enforce the by-laws of the Lambwe Valley Game Reserve. However, it is considered that the situation remains potentially dangerous, mainly because populations of tsetse are recovering from the effects of aerial spraying and because there is evidence that the tsetse habitats are encroaching on farming land.

Animals↗