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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↗
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↗
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↗
PubMed1976

Reliability of the enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of Trichinella spiralis infections in conventionally raised pigs.

An enzyme innunoassay using horse radish peroxidase as teh marker enzyme for the detection of antibodies to Trichinella spiralis in pigs was described. In the enzyme-linked immunosorbent assay (ELISA) quantitation os specific antibodies is obtained by means of peroxidase labeled anti-species-immunoglobulin in antigen-coated tubes. The enzyme remaining in the tube after wasging provides a measure of the amount of specific antibodies in the serum. A crude saline extract of T. spiralis muscle larvae served as antigen. In experiments in which conventionally raised pigs intended for slaughter were infected with various numbers of T. spiralis larvae (25,000; 12,500; 5,000; 2,500; 1,500; 500; 150; 50) a positive correlation was found between initial dose of larvae administered and amount of antibodies detected by ELISA. Compared with immuno-fluorescence (IF) ELISA was more sensitive. IF yielded positive results in 11 out of 34 infected animals, whereas ELISA results were positive in 27 cases. In order to evaluate ELISA results under practical conditions extinction values os sera from both infected and non-infected conventional pigs were compared with the highest extinction value of a group of 74 negative conventional pig sera. Due to the relatively high background reaction of some of these negative sera the number of positive practical ELISA results decreased from 27 to 19 out of 34 animals. Furthermore, in 1 out of 10 non-infected animals a false positive practical ELISA result was obtained. Ways to improve the reliability of ELISA are discussed.

Animals↗
PubMed1976

Reliability of the enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of Trichinella spiralis infections in conventionally raised pigs.

An enzyme immunoassay with horse radish peroxidase as marker enzyme for detection of antibodies to Trichinella spiralis in pigs is described. In the enzyme-linked immunosorbent assay (ELISA) quantitation of specific antibodies is obtained by means of peroxidase labeled anti-species-immunoglobulin in antigen-coated tubes. The enzyme remaining in the tube after washing provides a measure of the amount of specific antibodies in the serum. A crude saline extract of T. spiralis muscle larvae served as antigen, 5 mug protein/ml being a satisfactory concentration. Lyophilization of antigen had no adverse effect on sensitivity. To decrease background staining the use of an optimal conjugate dilution was important. Adding bovine serum albumen to the conjugate was essential to decrease background reactions. Suitable substrate incubation times were studied. Washing was performed with tap water and Tween 20. In experiments with conventionally raised slaughter pigs infected with different numbers of T. spiralis larvae a positive correlation was found between initial dose of larvae and amount of antibodies detected by ELISA. Compared with immunofluorescence (IF) ELISA was more sensitive. IF yielded positive results in 11 out of 34 infected animals, whereas ELISA results were positive in 27. To evaluate ELISA under practical conditions extinction values of sera from infected and non-infected conventional pigs were compared with the highest extinction value in a group of 74 negative conventional pig sera. The relatively high background reaction of some of these negative sera decreased the number of positive practical ELISA results from 27 to 19 out of 34. In 1 out of 10 non-infected animals a false positive practical ELISA result was obtained.

Animals↗
PubMed1975

Application of immunofluorescence and immunoenzyme methods in the serodiagnosis of Trichinella spiralis infection.

To detect antibodies to T. Spiralis in sera, the IF methods with the cuticle of T. spiralis larvae (the tube test) was compared to the cryostat method. In the latter method, cryostat sections were prepared from isolated T. spiralis larvae or from tongue or diaphragm musculature in which encysted T. spiralis larvae were present. In this case, both cuticle and internal structures were employed as antigenic sites. The cryostat method proved to be more sensitive than the tube test. With the cryostat method, specific antibodies were detected in sera of experimentally infected mice 14 days after infection, whereas with the tube test, antibodies were detected on Day 24 postinfection and consistently thereafter. The enzyme-linked immunosorbent assay (ELISA) was then studied. Quantitation of specific antibodies was achieved with alkaline phosphatase- or peroxidase-labeled antispecies immunoglobulin in antigen-coated tubes. The enzyme that remained in the tube after washing provided a measure of the amount of specific antibodies in the serum. A saline extract of T. spiralis larvae served as the antigen. In the experimental models studied (T. spiralis-infected rabbits and pigs), ELISA proved to be more sensitive than IF. At Day 3 postinfection and thereafter, specific antibodies could be detected. ELISA was modified to satisfy requirements for routine application.

Alkaline Phosphatase↗
PubMed1975

Studies on isolation and drug sensitivity of Trypanosoma vivax in northern Nigeria.

In a study to investigate the occurrence in cattle of Trypanosoma vivax strains resistant to the normal therapeutic dose of homidium, 47 isolates of T. vivax were collected from 10 different trypanosomiasis treatment centres in the North Central State of Nigeria. Of these 47 isolates, 23 produced infection in the experimental animals that were used for subsequent drug sensitivity trials. While all but one of the experimental cattle inoculated with T. vivax became infected, less than 50% of the experimental sheep and none of the experimental goats were able to reproduce infection. This difference in infectivity is discussed and related to the stage of the T. vivax infection in the donor cattle. None of the 23 isolates of T. vivax was resistant to homidium. The value of sheep and goats in T. vivax experiments is discussed.

Animals↗
PubMed1975

[Immunofluorescence technique in diagnosis of trichinellosis in swine. II. Comparative investigations with the tube test and the cryostate method (author's transl)].

A series of comparative IF tests have been made on serum samples from 9 SPF pigs experimentally infected with Trichinella spiralis (50-500 larvae per animal). The techniques applied included a tube test (antigen: whole Trichinella larvae), and a cryostat test (antigen: sections of Trichinella larvae). With the cryostat test a positive reaction was recorded in 2 animals already on the 6th day and in 5 animals on the 13th day p.i., while with the tube test such reaction was not demonstrated until the 27th day p.i. (2 animals). A potential risk of cross-reaction of unknown origin seems, however, to limit the application of the cryostat test to SPF- pigs.

Animals↗