PubMed Health⌕ Search

Biomedical subjects

B Betschart

Publications and source records attributed to B Betschart.

At least 55 records · Page 3Linked to original sources
PubMed1988

Genetically discrete populations of Trypanosoma congolense from livestock on the Kenyan coast.

Twenty-seven stocks of Nannomonas trypanosomes isolated from livestock in 1982 on a ranch at Kilifi on the Kenyan coast were characterized by isoenzyme electrophoresis and by the abilities of the parasite's DNA to hybridize to two repetitive sequence DNA probes. All the Kilifi stocks which were examined had isoenzyme patterns which were markedly different from the 75 patterns previously described from 78 stocks of Trypanosoma congolense. On average only 15% of the enzyme bands present in the Kilifi stocks were present in those stocks of T. congolense which had previously been surveyed for isoenzymes. The DNA from all the Kilifi stocks which had been examined for isoenzymes hybridized with only the repetitive sequence probe isolated from a clone of a Kilifi stock. In contrast, the DNA from all 27 Kilifi stocks failed to hybridize with a repetitive sequence probe isolated from a clone from a different stock of T. congolense. Thus, the trypanosomes in all the Kilifi stocks examined were both phenotypically and genotypically discrete. These genetically discrete trypanosomes have also been detected in 2 stocks isolated from livestock from another location on the Kenyan coast. The results show that there is a wide range of genetic heterogeneity within the trypanosomes currently classified as T. congolense. We suggest that the limits of this genetic heterogeneity could represent incipient speciation.

Animals↗
PubMed1988

Formation of the circumsporozoite protein of Plasmodium falciparum in Anopheles stephensi.

The place and time of synthesis of the circumsporozoite protein of P. falciparum was analysed with a monoclonal antibody directed against the (NANP)3 repetitive epitope of the CS protein. By using an indirect fluorescent antibody test the epitope could be detected on the oocyst 7 days after infection and 3 days before the appearance of mature sporozoites. Using the Western blot technique, 3 polypeptides from midgut preparations were recognized by the (NANP)3-specific monoclonal antibody from the day 9 of infection onwards. The circumsporozoite precipitation reaction could be induced in sporozoites from either the midgut or the salivary glands 11 days after a blood meal. A similar reactivity of midgut-sporozoites and salivary gland-sporozoites was observed with antisporozoite antisera. Not all sporozoites recovered from the midgut showed a precipitation reaction.

Animals↗
PubMed1987

Distribution of iodinated proteins in Dipetalonema viteae after surface labelling.

Adult females of the filarial parasite Dipetalonema viteae were radiolabelled using chloroglycoluril and different concentrations of iodine with and without carrier iodide. A detailed quantitative analysis of the distribution of the labelled proteins were carried out using sodium dodecylsulfate and beta-mercaptoethanol to isolate the cuticle after different iodination periods. The highest specific activity was found in the pellet, which comprised the cuticular cortical zone with the highly insoluble epicuticle. However, 50% of the radiolabelled proteins were recovered in the extracts, which contained solubilized material from the somatic compartments and the basal and median zones of the cuticle. The data indicate that the isolation of surface-iodinated antigens of filariae is hampered by the presence of a detergent-insoluble epicuticle. Radiolabelled antigens solubilized by detergents are either proteins from internal somatic or cuticular regions or proteins adsorbed onto the epicuticle.

Animals↗
PubMed1987

Chloroquine administration for malaria suppression after abdominal surgery.

Administration of chloroquine after major surgery is indicated in malaria endemic areas. In emergencies it is commonly administered parenterally after the operation. The present study, undertaken at St. Francis Hospital, Ifakara (Kilombero District), Tanzania, compared plasma chloroquine levels after oral and subcutaneous administration of 300 mg of chloroquine base in 14 patients after abdominal, non-bowel-resective surgery and in 12 controls. There were no significant differences in the plasma chloroquine levels of all groups, and the chloroquine concentrations reached suppressive levels for at least 3 days (greater than 0.1 nmol/ml). Oral administration was well tolerated in both patients and controls. In all areas where the Plasmodium strains are still sensitive to chloroquine and where parenteral chloroquine may not be easily available, oral chloroquine represents a cheap, easy and safe alternative for postoperative prophylactic malaria suppression. It can be applied after abdominal non-bowel-resective emergency surgery.

Abdomen↗
PubMed1987

Longitudinal study on the health status of children in a rural Tanzanian community: parasitoses and nutrition following control measures against intestinal parasites.

Three repeated cross-sectional surveys were undertaken among children (1 month to 15 years) of a rural community in southeastern Tanzania. The study was part of a longitudinal project on the interactions among nutrition, parasitic infections and immunity within a primary health care programme emphasizing village health workers. All children underwent interviews and parasitological, anthropometric, anamnestic and clinical examinations. Out of 550-590 children examined each year, a cohort of 170 children could be followed for three consecutive years. Malaria was holo- to hyperendemic in the community, P. falciparum accounting for greater than 90% of the infections. The parasite and spleen rates were 88% and 67%, respectively, and the average enlarged spleen index was 2.0 among children from 2-9 years in 1982. Transmission of malaria was high and stable as indicated by a parasite rate of 80% among infants between 1 month and 1 year during the whole period of study. G. lamblia, hookworm (N. americanus), Strongyloides spp. and Schistosoma haematobium were highly prevalent and annual incidence rates were high, while Entamoeba histolytica, Ascaris and Trichuris were of minor importance. Prevalence and incidence of parasitic infections did not differ by sex. Multiparasitism was very frequent and less than 11% of all children were parasite-free in each year. Not a single child remained parasite-free for three consecutive years. An anthropometric assessment showed a high degree of stunting (35-71%) and a substantial proportion of wasting (3-20%). The growth potential was normal in girls and boys during the whole period of study. There were indications that malaria was the main contributory factor to growth retardation among young children. Hookworm infection did not significantly affect the packed-cell volume of the children, probably owing to the low intensity of infection. Due to the multiparasitism and the lack of parasite-free individuals, single-parasite and single-nutrient effects were difficult to unravel. A latrine campaign followed by a single mass treatment against hookworm (single oral dose of albendazole, 400 mg) and/or G. lamblia (single oral dose of ornidazole, 40 mg/kg) only temporarily affected the prevalence and incidence of G. lamblia, and only resulted in a decrease in the intensity of hookworm infections up to six months after the interventions. As the effects of the latrine campaign and a single mass treatment on the parasite load were only transient, no sustained impact on nutritional variables was observed.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1987

Serum proteins and zinc as parameters to monitor the health of children in a rural Tanzanian community.

Total protein concentration, zinc, prealbumin, albumin, alpha-1-, alpha-2-, beta- and gammaglobulin concentrations were measured in serum samples collected in three successive years (1982, 1983 and 1984) from children (1 month-15 years) of Kikwawila village, Tanzania. The analysis of a total of 1590 serum samples provided the baseline data for children living in a rural Tanzanian community. The total protein values and the concentrations of betaglobulin were within the range described for Caucasians. Albumin, prealbumin, alpha-1- and alpha-2-globulin concentrations were below these standard values. On the other hand the gammaglobulin concentration was twice as high. The concentrations of total protein, gammaglobulin and prealbumin correlated with age. From 1982 to 1983 a significant decrease of most of the serum components (incl. zinc) was observed, although in children older than 2 years the alpha-1-globulins increased. All values increased again from 1983 to 1984, except for the zinc concentration, which decreased further. The individual fluctuations were analysed by comparing paired values for the children participating in the period 1982-1983, or 1983-1984. The proportion of children showing large fluctuations, sometimes exceeding the selected limits of tolerance, was larger in the period 1982-1983 than 1983-1984. This was consistent with the overall pattern found for all children. The prealbumin level, which has been postulated to be an indicator for malnutrition or borderline malnutrition, was analysed in detail. The values were far below normal values (200-300 mg/l), reaching a plateau with 130 mg/l among 4-6-year-old children. The individual fluctuations indicated a decrease from 1982 to 1983, which was considerable both in terms of the proportion of children showing a decrease (55%) and in the magnitude of the decrease. There was an increase from 1983 to 1984 but this increase did not compensate for the loss in 1983. Prealbumin concentrations showed a slight trend towards decreased values with stunting and wasting. No direct correlation was found between the other biochemical parameters and the parasite or anthropometric data collected at the same time. It was difficult to establish direct relationships between the biochemical parameters, which mainly indicate the health status of the child at the time-point of the survey, and anthropometric parameters which reflect the history of the individual over a long period. No direct correlation could be established between the biochemical parameters and the parasitological data.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1987

A longitudinal study on relations of retinol with parasitic infections and the immune response in children of Kikwawila village, Tanzania.

From 1982 to 1984 170 children of Kikwawila village (Kilombero district, Tanzania) were followed for nutritional (anthropometric measures, hematocrit, serum retinol, prealbumin, and zinc concentrations), parasitological (malaria parasitemia, urinary schistosomiasis, intestinal parasites) and immunological characteristics. Between 2.9% and 12.4% had serum retinol levels less than 100 micrograms/l which indicate deficiency. Retinol concentrations were correlated with age, hematocrits, prealbumin levels and mid upperarm circumferences. The latter correlation may be useful in nutritional surveys and primary health care programs for the identification of populations at risk of retinol deficiency. No association was found between average retinol levels and the presence of parasites, with the exception of malaria. Retinol levels were inversely correlated with malaria parasitemia in 1982, and directly correlated with antibody titers to synthetic sporozoite peptide in 1984. Since retinol, malaria parasitemia, and antisporozoite antibodies increased with age, confounding by age could not be excluded. Six months after administration of ornidazole in a single oral dose of 10 mg/kg, a significant effect on the prevalence of Giardia lamblia was found. Following treatment, average retinol levels were increased in persons with confirmed G. lamblia infections, but not in uninfected or untreated controls.

Adolescent↗
PubMed1987

Polyclonal B-cell activation and autoantibody formation during the course of mosquito-transmitted Plasmodium berghei infection in mice.

The time course of polyclonal B cell activation, as measured by titers of antibodies to DNP, FITC, and haemocyanin, as well as the time course of autoantibody formation, was followed in mice infected with Plasmodium berghei via Anopheles stephensi. IgM class antibodies to DNP, FITC, and haemocyanin appeared earlier than IgG class antibodies and persisted until death. Only IgM class anti-DNP peaked, the others remained high until death. Although IgM class autoantibodies also appeared earlier than IgG class, they peaked sharply at days 14 to 15, as did antibodies to mouse RBC. Polyclonal B cell activation, as measured by spleen plaque-forming cells (PFC) using SRBC and TNP-SRBC in the direct test, peaked at day 13. This latter event could be correlated with the time course of hypergammaglobulinemia.

Animals↗
PubMed1986

[Selection of chloroquine-resistant Plasmodium falciparum strains in tourists under chemoprophylaxis].

In a prospective study 20 P. falciparum isolates imported from Africa by non-immune tourists were investigated for chloroquine sensitivity using the in vitro microtest and the results were compared with the plasma chloroquine concentration. All 6 patients taking correct chloroquine prophylaxis (chloroquine plasma levels between 0.1-0.5 nmol/ml) harboured highly resistant P. falciparum strains (schizont maturation at 3.2 and 6.4 nmol/ml blood in 3 patients each). In the 4 patients with inadequate prophylaxis (plasma levels between 0.02-0.1 nmol/ml) the degree of resistance was lower (at 1.6 and 6.4 nmol/ml blood in 2 patients each). Chloroquine-sensitive strains were found only in patients with chloroquine plasma levels below 0.02 nmol/ml and in 4 of 5 patients who did not show chloroquine in the plasma. Selection of chloroquine-resistant P. falciparum strains under short term chloroquine chemoprophylaxis appears to be highly probable.

Africa↗
PubMed1986

Demonstration of anti-cuticular antibodies by immuno-electron microscopy in sera of mice immunized with cuticular extracts and isolated cuticles of adult Dipetalonema viteae (Filarioidea).

The immunogold technique was used for the ultrastructural localization of antibody-binding sites on thin sections of Lowicryl K4M embedded adult females, infective larvae and pieces of adult cuticles of Dipetalonema viteae insoluble in SDS-2-ME. The antisera used were either produced against SDS-2-ME extracts of cuticles or the insoluble pellet after SDS-2-ME extraction. With both types of antisera a labelling of epitopes on fibers was achieved in intact cuticles. In isolated cuticles the corresponding structures were absent. The same sera crossreacted with the larval and microfilarial cuticle as well as with somatic structures of all three stages. The only serum against isolated cuticle, which did not recognize cuticle fibers also did not crossreact with somatic structures. The recognition of the electron dense cortical layer insoluble in SDS-2-ME depended on the number of immunizations. A labelling of the filarial surface was never achieved. A dense labelling of the apical membrane enfoldings of the hypodermis pointed to an involvement in the synthesis of the nematode cuticle. The rough endoplasmic reticulum in the apex of the epithelial cells of the uterus, the content of the nutrient channels, and the substance between eggshell and microfilariae crossreacted with most of the antisera. This led to the conclusion that these substances are partly produced by the uterus epithelium.

Animals↗
PubMed1986

Quantitative determination of chloroquine and desethylchloroquine in biological fluids by high performance thin layer chromatography.

A high performance thin layer chromatographic (HPTLC) method for chloroquine (CQ) and desethylchloroquine (DCQ) determinations in plasma, erythrocytes and urine is described. Samples extracted by heptane from an alkaline water phase are separated on HPTLC silica gel plates, using toluene/diethylamine (9:1). The compounds are quantified by scanning fluorescent signals. The detection limit is 0.01 mumol/1 for CQ and DCQ, with an extraction efficiency of 76 +/- 7%. Further simplification could make the method suitable for use in field surveys.

Chloroquine↗
PubMed1985

The isolation and immunogenicity of the cuticle of Dipetalonema viteae (Filarioidea).

The cuticle of the filaria Dipetalonema viteae was isolated by sonication in 1% sodiumdodecylsulphate (SDS) and in a mixture of 1% SDS and 5% B-mercaptoethanol (BME). Sonication in SDS removed all internal parts and left the cuticle intact; this was verified by light- and electronmicroscopy. Sonication and incubation of the cuticle in the mixture of SDS-BME at pH 6.8 dissolved the basal and part of the median zone of the cuticle. The epicuticle and the cortical zone remained intact. The extracts were investigated using SDS-polyacrylamide gel electrophoresis; the early extracts contained a wide variety of proteins, whereas the later steps showed a consistent pattern with a smaller number of bands. Cuticles after SDS-purification, the extract of cuticular material in SDS-BME, and the cuticles insoluble in SDS-BME were used to immunize mice; the antibodies produced were visualized by an indirect fluorescent antibody test on cryostat sections of female worms. When SDS-purified cuticles were used for immunization, antibodies directed against all organs in the filariae were found. The SDS-BME extract and the insoluble cuticular pellet stimulated the production of antibodies restricted to the cuticle of adult worms and microfilariae. The purification method opens up the possibility of further isolation and characterization of antigens from the cuticle.

Animals↗
PubMed1983

Characterization of Trypanozoon stocks by isoelectric focusing and isoenzyme analysis.

Isoelectric focusing on ultrathin polyacrylamide foils, coupled with isoenzymatic analysis using five different enzymes, was used to characterize blood-forms of T.b. brucei, T.b. rhodesiense and T.b. gambiense and procyclic forms of T.b. brucei and T.b. rhodesiense. The protein concentrations in the lysates were quantified. Qualitative as well as quantitative differences were found.

Animals↗