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Biomedical subjects

J Buys

Publications and source records attributed to J Buys.

At least 19 recordsLinked to original sources
PubMed1985

[Tapeworms in the Netherlands].

Scientists have been discussing the nature of helminths, and particularly tapeworms, for ages. A synopsis of the ancient literature and literature of the Middle-Ages concerned with this subject is presented. Even today a number of remarkable stories about tapeworms is being told. One of them is that tapeworms do not occur in The Netherlands. The incidence of the tapeworm Taenia saginata in man in The Netherlands was carefully calculated from figures on cysterci observed in bovine carcases and estimates based on sales records of anthelmintics. It was concluded that tapeworms are relatively common (0,2-0,3%). The life cycle of Taenia saginata showed a remarkably constant pattern during the past twenty-five years.

Animals↗
PubMed1984

Myeloperoxidase is more efficient than eosinophil peroxidase in the in vitro killing of newborn larvae of Trichinella spiralis.

Myeloperoxidase (MPO) and eosinophil peroxidase (EPO) catalyse the formation of hypochlorite (OCl-) from chloride ions (OCl-) and hydrogen peroxide (H2O2). OCl- proved to be highly toxic for Trichinella spiralis newborn larvae (NBL) in in vitro assays. Using purified human MPO and EPO it was found that even at neutral pH both enzymes under appropriate conditions are able to kill NBL. The rate at which OCl- is produced is much lower in the EPO- than in the MPO-mediated reaction. This difference in enzymic activity may explain why in the MPO-mediated reaction half the amount of OCl- was sufficient to kill 50% of the NBL, as compared to the EPO-mediated reaction. Purified human eosinophil major basic protein showed excellent OCl- scavenging properties, resulting in a significant decrease in the EPO-mediated NBL killing. Addition of ammonium ions [(NH4)2SO4] to the EPO-mediated reaction increased the NBL killing remarkably. It was concluded that in vitro MPO is more efficient than EPO in killing NBL. Furthermore, it was suggested that although eosinophils show marked parasiticidal effects in various in vitro systems, their primary biological role might be the regulation of the inflammatory reactions.

Animals↗
PubMed1983

[Immunologic defense and inflammation in parasitic infections. The role of eosinophilic granulocytes].

The origin, kinetics and role of eosinophilic granulocytes in immune defense and inflammatory response in parasitism are reviewed. Particular attention was paid to the toxic action of eosinophilic granulocytes on parasites and the biochemical reactions which are of importance in these cases. Reference was also made to the regulatory role of eosinophilic granulocytes in inflammatory reactions, particularly in regard to mast cells. It was concluded that (1) several new insights into the role of eosinophilic granulocytes were gained in recent years, (2) that these cells can at any rate be said to have a dual function (viz. a directly parasitotoxic and regulatory role) and (3) a definite statement regarding the role of eosinophilic granulocytes in helminthic infections cannot so far be made.

Antibody Formation↗
PubMed1983

Rat mononuclear cells and neutrophils are more effective than eosinophils in antibody-mediated stage-specific killing of Trichinella spiralis in vitro.

The capacity of non-infected rat total, eosinophil-enriched and eosinophil-depleted fractions of peritoneal exudate and bone marrow cells to adhere to and kill Trichinella spiralis newborn larvae with immune rat serum has been studied in vitro. The eosinophil-depleted peritoneal exudate cell fraction contained mainly mononuclear cells, whereas the corresponding bone marrow cell fraction consisted of a considerable number of neutrophils. All cell types either originating from the peritoneal cavity or the bone marrow, showed adherence and killing properties to the Trichinella newborn larvae. It was concluded that mononuclear cells and neutrophils are capable of and more effective than eosinophils in stage-specific killing of Trichinella in vitro.

Animals↗
PubMed1983

The athymic nude rat. IV. Immunocytochemical study to detect T-cells, and immunological and histopathological reactions against Trichinella spiralis.

The anti-parasite response was investigated after oral infection of athymic nude (rnu/rnu) rats and heterozygous (+/rnu) littermates with 1000 muscle larvae of Trichinella spiralis. No IgM, IgG and IgE antibodies were detected in serum of rnu/rnu rats. Expulsion of adult worms from the small intestine was prolonged (worms were nearly all expelled at days 14 and 91 in +/rnu and rnu/rnu rats respectively). The yield of muscle larvae in the carcasses of nude rats at day 91 was 33 times higher than in +/rnu rats. In contrast to the strong inflammatory reaction in the parasitized tongue of +/rnu rats, no infiltration was observed in rnu/rnu rats. Using an immunoperoxide method with monoclonal anti-rat T-cell antibody, no T cells were identified in spleen, mesenteric lymph node and Peyer's patches. These data support earlier studies that the nude rat lacks functional T cells. As the counts of connective tissue mast cells (CTMC), intestinal mast cells (IMC) and globule leucocytes (GL) in small intestine of uninfected rnu/rnu rats were equal or higher than in +/rnu rats, it is concluded that the origin of these cells is thymus-independent. In contrast to +/rnu rats, infection of rnu/rnu rats induced no increase of CTMC, IMC or GL. Thus, these cells depend on T cells to undergo proliferation. Finally, results of this study were inconclusive whether IMC are precursors for GL, or that they represent independent cell populations.

Animals↗
PubMed1981

The killing of newborn larvae of Trichinella spiralis by eosinophil peroxidase in vitro.

Helminth infections in mammals are characterized by a high level of eosinophils in parasitized tissues and blood, and it has recently been suggested that these cells have a direct parasiticidal effect. Newborn larvae of Trichinella spiralis can be killed within 20 min by incubation at room temperature in a cell-free system, including purified human eosinophil peroxidase (EPO), H2O2 and chloride at pH 5.5. Killing was measured by microscopic observation of the larvae. The larvicidal effect was dependent on each component of the EPO/H2O2/Cl- system and could be prevented by using SO4(2-) instead of Cl-. Killing was totally inhibited by sodium azide and catalase, and substantially by bovine serum albumin, a protein that is an effective scavenger for HOCl. Since larvae could also be killed directly by HOCl under these conditions and EPO is able to oxidize Cl- to hypochlorous acid, it is very likely that the larvicidal effect of the EPO system is due to formation of hypochlorous acid. It is proposed that in vivo, the combination of EPO, which is exocytosed onto the surface of the parasite, and H2O2, which is generated by stimulated eosinophils, is responsible for the larvicidal effect.

Animals↗
PubMed1980

Immunological aspects of some parasitic infections.

In this review article, some recent developments in the immunology of parasitic infections are presented. After an introduction in which the major human parasitic infectious diseases, including malaria, african and american trypanosomiasis, leishmaniasis, filariasis an schistosomiasis are mentioned, a description of the host/parasite relationship in malaria presented. The possibility for the development of vaccins against malaria are described. The close relation between the immunological responses and the inflammatory reactions present both in Schistosoma mansoni and Trichinella spiralis infections is stressed. Particularly the recently recognized direct anti-parasitic activity of eosinophils was emphasized. Next, ways of escape of parasites from the host defence were described, with special emphasis on the immunomodulating properties of parasitic infections. Finally, the development and improvement of new immunodiagnostic methods, including the detection of circulating antigens were discussed.

Animals↗
PubMed1980

Ovalbumin immunity in the rat: simultaneous testing of IgM, IgG and IgE response measured by ELISA and delayed-type hypersensitivity.

After immunization of Wistar rats with different concentrations of ovalbumin (OA) emulsified in complete H37Ra adjuvant, the optimal antigen dose for specific IgM, IgG and IgE production and for delayed-type hypersensitivity appeared to be the same. It is therefore concluded that in the rat these function tests can be combined, which decreases the number of experimental animals needed. For the determination of IgM, IgG and IgE antibodies to OA, the enzyme-linked immunosorbent assay (ELISA) was used, which proved to be a specific method. In addition, using a multi-channel photometer, it is shown that specific antibody concentrations can be readily quantified by micro-ELISA instead of using end-point titrations.

Animals↗
PubMed1979

Quantification of total IgM and IgG and specific IgM and IgG to a thymus-independent (LPS) and a thymus-dependent (tetanus toxoid) antigen in the rat by enzyme-linked immunosorbent assay (ELISA).

Rat IgM and IgG was determined by mechanized "sandwich" enzyme-linked immunosorbent assay (ELISA) using peroxidase labeled anti-rat-IgM and -IgG. Linear ranges in standard curves of a reference rat serum had a slope similar to the slopes found with sera of 25 rats of various age. IgM and IgG measurements by ELISA in these sera correlated well with results obtained by single radial immuno-diffusion (SRID). In addition, the precision of the enzyme immunoassay was the same as obtained with the SRID. Compared with SRID, ELISA is less time consuming and the amount of antiserum used in the macro-ELISA is one order of magnitude lower; and again 10 times lower in the mechanized micro-ELISA that is currently being developed. In conclusion, the ELISA is a specific, reliable, sensitive, and economic method for routine measurement of rat serum IgG and IgM e.g. in toxicity studies. In the second part of this study, ELISA and the passive hemagglutination test were compared to determine the primary and secondary antibody response to E. coli lipopolysaccharide (LPS) and tetanus toxoid in rats. In the ELISA, the antigens were bound to the wells of polystyrene microplates. Tetanus toxoid was coated directly, LPS after complexing with methylated bovine serum albumin. After incubation with dilutions of the rat sera, the amount of antibody bound to the solid phase was quantified by means of peroxidase-labeled antiimmunoglobulin. The specificity of the enzyme immunoassay was tested by absorption of the sera with the respective antigens. ELISA proved to be more sensitive than the hemagglution reaction, except when titers were determined during the secondary response to tetanus toxoid. Besides its specificity and sensitivity, ELISA is a convenient method for measuring both IgM and IgG antibodies. Finally, evidence is presented that in the rat, the humoral immune response to LPS is a thymus-independent phenomenon. Thus, by using the antibody response to LPS and tetanus toxoid in function studies of the immune system of the rat, insight can be obtained in the thymus-independent and thymus-dependent humoral immune response.

Age Factors↗
PubMed1979

Comparison of enzyme-linked immunosorbent assay and passive hemagglutination method for quantification of antibodies to lipopolysaccharide and tetanus toxoid in rats.

In a comparative study, the enzyme-linked immunosorbent assay, using peroxidase labeled anti-rat immunoglobulin M and immunoglobulin G, and the passive hemagglutination test were applied to determine the primary and secondary antibody response to lipopolysaccharide and tetanus toxoid in rats. In the enzyme-linked immunosorbent assay, the antigens were bound to the wells of polystyrene microplates, tetanus toxoid directly, and lipopolysaccharide after complexing it with methylated bovine serum albumin. After incubation with dilutions of the rat sera, the amount of antibody bound to the solid phase was quantified by means of peroxidase-labeled anti-immunoglobulin. The specificity of the enzyme immunoassay was tested by absorption of the sera with their respective antigens. The enzyme-linked immunosorbent assay proved to be more sensitive than the hemagglutination reaction, except when titers were determined during the secondary response to tetanus toxoid. Besides its specificity and sensitivity, the enzyme-linked immunosorbent assay is a convenient method for measuring both immunoglobulin M and immunoglobulin G antibodies. At low serum dilutions of lipopolysaccharide antisera, inhibition of the reaction in the enzyme-linked immunosorbent assay occurred. This phenomenon could be prevented by heating the sera at 56 degrees C for 30 min. Lipopolysaccharide was immunogenic in rats over an extremely wide dose range (from 10 pg to 1 mg); the optimal immunogenic dose of lipopolysaccharide for young adult rats was 0.1 to 1,000 mug when administered intravenously, and that of tetanus toxoid was 5 to 10 lines of flocculation, as determined by the Ramon flocculation test.

Animals↗
PubMed1979

The serodiagnosis of chronic fascioliasis (Fasciola gigantica) using a fluorescent-antibody technique with single and multiple whole-fluke antigens.

Sera from cattle with single or mixed infections of Fasciola gigantica. Dicrocoelium hospes, Schistosoma bovis and paramphistomes were examined for fluorescent antibodies. Cross-reacting antibodies of the heterologous flukes were easily detected by using cryostat sections with whole-fluke-antigen of all three flukes. The presence of F. gigantica antibodies in a cattle herd was tested at two monthly intervals in order to establish the occurrence of chronic fascioliasis. The lack of significant differences in antibody levels of infected, treated and uninfected cattle however showed that herd antibody levels are not very useful to detect chronic Fasciola infections.

Animals↗
PubMed1977

Application of the enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of human African trypanosomiasis (sleeping sickness).

An enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of human African trypanosomiasis (sleeping sickness) is described. A crude extract of a Trypanosoma brucei suspension which was purified from all blood components was used as antigen. In rabbits experimentally infected with T. brucei or T. rhodesiense both homologous (anti-T. brucei) and heterologous (anti-T. rhodesiense) Trypanosoma antibodies could be detected with ELISA using T. brucei as antigen. The sensitivity of ELISA was comparable with that of the immunofluorescence (IF) technique. Sera of patients with sleeping sickness were examined with ELISA and IF. It proved possible to discriminate between groups of individuals with and without trypanosomiasis. Cross reactions were only observed with serum from a patient in which antibodies to Leishmania were detected. No cross reactions were observed in sera from patients with malaria, toxoplasmosis, schistosomiasis, or echinococcosis. ELISA represents a good alternative to IF in the serology of African trypanosomiasis, and may be particularly suitable for mass screening purposes.

Animals↗