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B Betschart

Publications and source records attributed to B Betschart.

61 records · Page 4Linked to original sources
PubMedDate not supplied

Detecting malaria sporozoites in live, field-collected mosquitoes.

A method is described for identifying malaria-infected mosquitoes, without killing them or hampering their fitness. Individual mosquitoes were induced to salivate on coverslips, and sporozoites, deposited on the glass surface, were visualized by Giemsa staining. Of 21 mosquitoes found to contain sporozoites by salivary gland dissection, 13 had delivered sporozoites on coverslips. A positive correlation was found between the amount of saliva expelled and ejection of sporozoites, indicating that the sensitivity of the method may be increased by improving the probing behaviour of the mosquitoes. The procedure described may be suitable for selecting infected mosquitoes which are able to eject sporozoites during probing. Being applicable to wild Anopheles and to large numbers of mosquitoes, the method lends itself for use in field studies on malaria.

Animals↗
PubMedDate not supplied

Comparison of intramuscular and intravenous quinine for the treatment of severe and complicated malaria in children.

To compare the efficacy and side effects of intramuscular (i.m.) and intravenous (i.v.) quinine, children in Mozambique with severe and complicated malaria between 6 months and 7 years were randomized to treatment with i.m. or i.v. quinine, both in a dosage of quinine dihydrochloride 20 mg/kg followed by 10 mg/kg every 8 h. Of 57 children treated with i.m. quinine, 4 died, 3 had neurological sequelae and 2 had sterile intramuscular abscesses. Of 47 children treated with i.v. quinine, 6 died and 1 had neurological sequelae. The mean parasite clearance time was 58.6 h in the i.m. group and 59.3 h in the i.v. group. Mean temperature clearance times were 56.1 and 51.8 h, and mean coma clearance times 40.4 and 38.7 h, respectively. None of these differences was statistically significant. Mean trough and peak concentrations of quinine were almost identical in the 2 groups, ranging from 10.5 to 12.6 mg/L, which is in the therapeutic non-toxic range. It is concluded that i.m. quinine is as effective as quinine by i.v. infusion in children with severe and complicated malaria; that minor local side effects can probably be avoided by using diluted quinine for i.m. injection; and that the optimal dose regimen for children with severe and complicated malaria in Africa at present is probably quinine salt 20 mg/kg followed by 10 mg/kg every 12 h.

Child↗
PubMedDate not supplied

Hybrid formation between African trypanosomes during cyclical transmission.

Trypanosomes of the species Trypanosoma brucei reproduce primarily by binary fission, but the frequency of enzyme electrophoretic variants in natural populations of T. brucei has provided indirect evidence for the existence of a sexual cycle. These studies, coupled with studies of restriction fragment length polymorphisms of genes encoding glycolytic enzymes, have also provided evidence for T. brucei being diploid. Here we report direct evidence of gene exchange between two different clones of trypanosomes after mixed infection and full cyclical development in the tsetse fly vector.

Animals↗
PubMedDate not supplied

Isoniazid plus sulphadoxine-pyrimethamine can reduce morbidity of HIV-positive patients treated for tuberculosis in Africa: a controlled clinical trial.

An annual 20% excess mortality rate is observed in HIV-seropositive patients after treatment for tuberculosis. An affordable secondary prophylaxis against main opportunistic diseases is needed, i.e. against tuberculosis, toxoplasmosis, pneumocystosis and other infections occurring in this target population. This open prospective randomized study assessed morbidity and mortality in 2 cohorts of HIV-seropositive patients having recently recovered from pulmonary tuberculosis: 134 patients assigned to prophylactic treatment with isoniazid (INH, 300 mg once daily) plus sulphadoxine-pyrimethamine (S, 500 mg/P, 25 mg once weekly), and 129 were controls, comparable for sex, age, weight and HIV-serology. Patients were followed-up for up to 2 years: 192 person-years (PY) in the prophylaxis group and 142 PY in the control group. Four patients developed tuberculosis and 20 patients died in the prophylaxis group, compared to 10 and 23 controls, respectively. Sick days were reported by 22 patients in the prophylaxis group and by 77 patients in the control group. This prophylaxis was associated with a moderate decrease of mortality (log rank test: p = 0.1736), a significant decrease of tuberculosis incidence (log rank test: p = 0. 0234), a highly significant reduction of adverse events and sick days, and a prevention of wasting (p = 0.008) and anaemia (p = 0. 045). No death from toxoplasmosis occurred in the prophylaxis group as compared to 2 possible cases among controls; toxoplasmosis IgG levels declined in treated patients, but increased in controls (p = 0.01). There was no adverse drug reaction due to SP (10,006 doses) or to INH. Compliance with SP intake was good, but moderate as with INH intake. We conclude that a secondary prophylaxis with INH+SP represents a cost-effective measure to improve health conditions of HIV-infected adults in Côte d'Ivoire, following a full treatment course against tuberculosis.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

The in vitro distribution of halofantrine in human blood and Plasmodium falciparum-parasitised red blood cells.

The in vitro distribution of the antimalarial drug halofantrine was measured in drug-preincubated whole blood after separation of the blood cells from the plasma according to their type. In normal blood, halofantrine was mainly associated with plasma (85% of the total drug) and to a lesser degree with erythrocytes (11%). The drug accumulated in lymphocytes to an approximately 250-fold higher concentration than in normal erythrocytes, but this represented only a small fraction (1%) of the total drug. It was not significantly bound to thrombocytes (2%), lymphocytes (1%) or granulocytes (0.3%). The distribution of halofantrine into Plasmodium falciparum-parasitised red blood cells was measured at different parasite stages and with varying serum concentrations. Halofantrine accumulated in P. falciparum-parasitised red blood cells to concentrations up to 60-fold those found in normal erythrocytes. The amount of accumulated drug depended on the parasite stage and presence of serum, since mature parasites showed the highest accumulation, and serum reduced drug accumulation compared to incubation under standard cultivation conditions.

Animals↗
PubMedDate not supplied

Comparative chromatin analysis of Trypanosoma congolense.

The chromatin of Trypanosoma congolense was analyzed by electron microscopy. The chromatin is organized as nucleosome filaments but does not form a 30 nm fiber. There are five groups of histones, including a histone H1-like protein, which as a molecular weight within the range of the core histones, and is extremely hydrophilic. Weak histone-histone interaction, a typical feature of trypanosome chromatin, was found. These results are similar to those for T. cruzi and T. b. brucei, but differ significantly from those for higher eukaryotes. The results confirm the model of trypanosome chromatin, and support the theory of their early separation from the other eukaryotes during the evolution. T. congolensis is an excellent model for chromatin research on trypanosomes, because it is easy to cultivate and its chromatin has, a relatively high stability, compared to that of other trypanosomes.

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