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Biomedical subjects

N Weiss

Publications and source records attributed to N Weiss.

At least 127 records · Page 7Linked to original sources
PubMed1988

Determination of batroxobin levels in the plasma of guinea pigs after epicutaneous and intravenous applications.

An enzyme immunoassay has been set up to measure batroxobin levels in plasma. This assay allowed the detection of amounts of batroxobin greater than 0.5 ng/ml plasma. After the epicutaneous application of 50 or 100 batroxobin units (BU)/kg body weight, no batroxobin could be detected in plasma samples taken 15, 30, 60, 120 or 240 min after the start of the experiment. In contrast, batroxobin could be detected in plasma samples after i.v. injection of 10 BU/kg body weight.

Animals↗
PubMed1988

The cross-reactive immune response between infective larvae and adult worms of Acanthocheilonema (Dipetalonema) viteae is dominated by phosphorylcholine.

The immune response of BALB/c mice against living L3 or adult extract of Acanthocheilonema viteae induces three antibody populations, namely antibodies which cross-react between the two forms of A. viteae, and either (i) do, or (ii) do not express specificity for phosphorylcholine (PC), and (iii) antibodies which do not cross-react between the two stages. In the anti-L3 serum, almost all cross-reactive antibodies to adult antigen are PC specific and of the IgM isotype, apart from a minor non-PC-reactive IgE response. On the other hand, the cross-reactive antibodies in the anti-adult serum are not PC reactive and of the IgG3 isotype. The non-cross-reactive antibodies in the two sera were predominantly IgM and IgG2/IgG1 for the anti-L3 and anti-adult respectively. Immunofluorescence and immunocytochemical studies on third-stage larvae and female worms revealed that antigens expressing PC determinants were mainly found on certain internal structures, whereas the cuticles of adults and the outer cuticle part of L3 are PC negative. Topographical analyses revealed distinct differences in labelling patterns by the two antisera, in the different areas. Thus the cross-reactive and non-cross-reactive antibodies induced by BALB/c mice to the two stages of A. viteae are different in nature. Since the antibody response induced by the L3 form and cross-reactive to the adult form is directed towards an ubiquitous antigen, namely PC, which is not present on cuticula of either the L3 or adult worms, this response may not contribute to protection against the parasite.

Animals↗
PubMed1987

Humoral immune responses in human onchocerciasis: detection of serum antibodies in early infections.

Sera of children (aged 1-15 years) living in a hyperendemic onchocerciasis area (Mali) were tested for antibodies by an enzyme-linked immunosorbent assay (ELISA) and a radioallergosorbent test (RAST), with an extract of adult Onchocerca volvulus as antigen. Serological results were related to age (equivalent to time of residence in the endemic area) and to parasitological findings (detection of skin microfilariae). This longitudinal study (over three years) allowed us to follow early antibody responses in exposed children with no parasitological or clinical evidence of infection and in children who became microfilaria-positive. Serum antibodies against O. volvulus could be detected one to three years before skin microfilariae. RAST, which detected circulating immunoglobulin E (IgE) antibodies, was more sensitive than ELISA in prepatent infections and gave more positive results for exposed but parasitologically negative individuals than did ELISA. During patent infection, IgE antibody levels tended to decrease in about half those infected, whereas in most children non-IgE antibodies showed no significant changes.

Adolescent↗
PubMed1987

Antibodies to the repetitive epitope of Plasmodium falciparum circumsporozoite protein in a rural Tanzanian community: a longitudinal study of 132 children.

An ELISA employing a novel synthetic peptide consisting of 40 (Asn-Ala-Asn-Pro) repeats of Plasmodium falciparum circumsporozoite protein, (NANP)40, was used to detect antibodies against P. falciparum circumsporozoite protein in 132 children, 1 month to 15 years old, from a rural community (Kikwawila village) of Tanzania, a region where malaria is hyperendemic. The children were surveyed comprehensively over 3 consecutive years for clinical, parasitological, and serological parameters. Entomological data were also gathered for selected households in this village. The following results were obtained: anti-(NANP)40 antibodies increased as a function of age; the majority of children over 10 years showed a stable positivity for such antibodies during the longitudinal study; a negative correlation was observed between the levels of anti-sporozoite antibodies and both spleen enlargement and the presence of parasites in thick smears; no relationship was found between anti-(NANP)40 antibodies and asexual blood stage antibodies; children living in two representative households with comparable indoor resting mosquito densities showed markedly different frequencies of anti-(NANP)40 antibodies, in spite of comparable clinical, parasitological, and serological parameters. Thus, in addition to the exposure to infectious mosquito bites, other (e.g., genetic) factors, may play a role in the ability of certain individuals to mount an antibody response against this immunodominant repetitive epitope. The results presented in this paper confirm that the (NANP)40-ELISA represents a simple, reliable means for the detection of anti-(NANP)40 circumsporozoite protein antibodies and suggest that such antibodies may contribute to the immune protection against malaria in humans.

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

Dipetalonema viteae: phosphorylcholine and non-phosphorylcholine antigenic determinants in infective larvae and adult worms.

The humoral immune response of Balb/c mice to live infective larvae or adult worm extract of Dipetalonema viteae is composed of two antibody populations either with or without specificity for phosphorylcholine. Absorption of immune serum on phosphorylcholine-Sepharose and separation of the antibody population demonstrated that anti-larvae serum contains a larger ratio of phosphorylcholine versus non-phosphorylcholine antibodies as compared to anti-adult serum. Immunofluorescence on crossections of female worms revealed that antigen expressing phosphorylcholine determinants were mainly found on certain internal structures, like egg, uterine, and intestinal membranes, but not on the cuticle. Immunoblotting using an adult worm extract demonstrated that protein bands reacted with either one or both populations of antibodies. The patterns were heterogeneous and moreover differed between the anti-larvae serum and the anti-adult serum.

Animals↗
PubMed1986

Detection of serum antibodies and circulating antigens in a chimpanzee experimentally infected with Onchocerca volvulus.

The course of the humoral immune response was followed in a chimpanzee experimentally infected over 27 weeks with a total of 168 Onchocerca volvulus 3rd-stage larvae obtained from naturally infected wild-caught blackflies. Antibodies against an adult worm extract could be detected by ELISA from week 16 onwards (after the inoculation of 44 larvae). Peak antibody levels were observed between weeks 66 and 74 (about one year after the last larval injection). Thereafter, antibody levels markedly decreased but rose again after week 120. First microfilariae could be detected from week 124 onwards. Microfilarial counts remained low (not more than two microfilariae per skin snip) until the end of the observation period. High levels of IgM antibodies against adult O. volvulus antigens were detectable between weeks 26 and 80 by ELISA. Total IgE levels were found to be only marginally elevated during the course of the infection. Circulating parasite antigens were only detectable for a short time (weeks 34 to 44) of the prepatent period by immuno-radiometric assays (IRMAs) using monoclonal antibodies which were raised against O. gibsoni eggs. Competitive radio-immuno-assays detected host antibodies inhibiting binding of 125I-labelled monoclonal antibodies to parasite antigens from week 28 onwards. Host antibodies clearly interfere later in infection with the detection of circulating antigens.

Animals↗
PubMed1986

Autoantibodies in humans with cystic or alveolar echinococcosis.

Sera from 16 echinococcosis patients were analyzed with respect to polyclonal B cell activation and autoantibody formation. At least 8 of the sera were from patients who were never in tropical countries and therefore their cases were not complicated by other parasitic diseases. In comparison with a group of 52 healthy controls, these patients had significant levels of antibodies to DNP and haemocyanin, indicators of polyclonal B cell activation. There were also significant differences between control and patient groups with respect to antibodies to dsDNA, histones, actin, vimentin, and desmin. This is the first report of autoantibodies in echinococcosis.

Adolescent↗
PubMed1986

Identification of non-cross-reacting antigens of Onchocerca volvulus with lymphatic filariasis serum pools.

Onchocerca volvulus proteins labelled with 125I were immunoprecipitated with onchocerciasis and lymphatic filariasis human serum pools in order to differentiate between cross-reacting and non-cross-reacting antigens. Analysis of the immunoprecipitates by two-dimensional gel electrophoresis revealed that all high molecular weight (Mr) O. volvulus antigens cross-reacted with the lymphatic filariasis serum pools. We observed, however, that at least 8 O. volvulus antigens were specifically immunoprecipitated only by the onchocerciasis serum pools, with Mr ranging from 20,000 up to 43,000 Daltons. These results suggest that the lower Mr O. volvulus antigens are more species specific than the other antigens. The significance of these findings for the immunodiagnosis of onchocerciasis is discussed.

Adult↗
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↗