Induction of atherosclerosis in Brown Norway rats by immunization with ovalbumin.
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A study was carried out to establish an animal model that would be suitable for evaluating the role of the diet in immune cell-mediated atherogenesis. Brown Norway rats were initially treated with hypervitamin D2 for 4 days and then fed on an atherogenic diet for 3 months, during which period the rats were either immunized with ovalubumin plus Al(OH)3 (OVA group) or with Al(OH)3 alone (control group) every 3 weeks. Aortic lesions were mainly composed of foam cells, the lesions evaluated by the intimal thickness of the ascending aorta being more severe in the OVA group than in the control group. The OVA group, in comparison with the control group, showed prominently increased serum levels of OVA-specific IgG and rat chymase, an indicator of mast cell degranulation. The intimal thickness was positively correlated with the level of chymase. Immunization had no effect on the serum lipid levels. These results support the hypothesis that mast cells play a role in the early stage of atherosclerosis and suggest that this animal model could be useful for evaluating the role of the diet in immune-related atherogenesis. (+info)
The evaluation of hypersensitivity tests in cattle after foot-and-mouth disease vaccination.
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The response to passive cutaneous anaphylaxis, dermal hypersensitivity and intravenous provocation tests has been compared in 30, 40, 31 and 24 cattle injected with foot-and-mouth disease vaccine 0, 1, 2 and 3 times respectively, using vaccine components and other substances as test materials. Reaginic antibodies demonstrated by passive cutaneous anaphylaxis in goats, were directed against BHK 21 cell extracts (20), hydroxypropylmethylcellulose (3) and an unidentified vaccine component (3), and distributed in 0, 5, 19 and 75 per cent of the cattle vaccinated 0, 1, 2 and 3 times. None of the animals showed clinical signs of allergy after vaccination. When BHK 21 cell extract was injected intradermally a significant correlation was noted between the development of large weals and the presence of reagins although the size of the weals was not correlated with the reagin titres. In the case of hydroxypropylmethylcellulose a similar trend was evident. The majority of cattle with large dermal weals possessed reagins but the number of reactions was too small for statistical evaluation. Dermal reactions to sodium penicillin, sodium carboxymethylcellulose, saponin and whole vaccine occurred in both unvaccinated and vaccinated cattle but BHK 21 cell lysate and normal bovine serum provoked weals which increased in frequency according to the number of vaccinations experienced. Intravenous hydroxypropylmethylcellulose elicited a response in all the animals previously injected with certain batches of vaccine but cell extract intravenously produced a clinical response in half the tested animals which was uncorrelated with the results of the passive cutaneous anaphylaxis or dermal hypersensitivity tests. (+info)
Comparison of the Serodia Treponema pallidum particle agglutination, Captia Syphilis-G, and SpiroTek Reagin II tests with standard test techniques for diagnosis of syphilis.
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We compared the microhemagglutination assay for Treponema pallidum (MHA-TP), a treponemal test, with two other treponemal tests, the Serodia Treponema pallidum particle agglutination (TP-PA) assay and the Captia Syphilis-G enzyme immunoassay, using 390 clinical serum samples. We also compared two nontreponemal tests, the rapid plasma Reagin (RPR) card test and the SpiroTek Reagin II test. Agreements of the MHA-TP with the TP-PA test and the Syphilis-G test were 97.4 and 97.7%, respectively. There was 89.2% agreement between the RPR and Reagin II tests. The Reagin II test was more apt to be reactive if the treponemal test was also reactive. We conclude that either the Serodia TP-PA test or the Captia Syphilis-G test is an appropriate substitute for the MHA-TP and that the Spirotek Reagin II test could substitute for the RPR test as a screening test. (+info)
Whole-blood hemagglutination inhibition test for venereal disease research laboratory (VDRL) antibodies.
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Nontreponemal antibody tests such as the Venereal Disease Research Laboratory (VDRL) test are carried out on serum and widely used as screening tests for syphilis. The aim of the present study was to develop a screening test for syphilis making use of whole blood and VDRL liposomes. Antibody to human red blood cells was conjugated to VDRL liposomes and reacted with a diluted sample of patient whole blood. A total of 951 samples were tested by the new test and the VDRL tube test. All 49 VDRL samples positive by the VDRL test showed inhibition of hemagglutination in the whole-blood test (sensitivity, 100%). Of 902 samples with negative results by the VDRL test, 901 caused hemagglutination when tested with the liposomes (specificity, 99.9%). The hemagglutination inhibition method tests for syphilis in a simple one-step procedure in which whole blood is added to a tube containing liposomes. The new test has potential for point-of-care testing in developing countries. (+info)
Correlation of anaphylactic bronchoconstriction with circulating reaginic antibody level and active cutaneous anaphylaxis in the rat.
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The interrelationships of anaphylactic bronchoconstriction, active cutaneous anaphylaxis and circulating reaginic antibody level in rats sensitized with Nippostrongylus brasiliensis have been studied. The mean rise in bronchial reactivity during the 5-week sensitization period was correlated with the rise in circulating reaginic antibody level in groups of rats, although weak bronchial reactivity was observed before circulating reagin was demonstrable. In individual animals bronchial reactivity did not significantly correlate with circulating reaginic antibody level or cutaneous reactivity. Bronchial and cutaneous reactivity on challenge may be transferred to non-sensitized rats by passive sensitization with reaginic serum. It is concluded that the ability of a tissue to respond to antigen challenge is multifactorial and may not be reliably predicted from a knowledge of circulating reaginic antibody level or the response of another tissue in the same animal. (+info)
The allergens of Schistosoma mansoni. II. Further separation by sephadex G-200 and ion-exchange chromatography.
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A total of thirty-five antigen fractions were prepared from adult Schistosoma mansoni by extraction into borate-buffered saline, precipitation at pH 4-6, gel-filtration on Sephadex G-100 and G-200, and ion-exchange chromatography on CM- and DEAE-cellulose. The allergic activity of these antigens was assayed by a modified Prausnitz-Kustner (P-K) type reaction in rats. The results showed that the allergen-reagin axis in rat schistosomiasis is a multicomponent system involving molecules of widely different chemical nature and molecular weight, rather than a simple, single antigen-antibody interaction. The significance of these findings to the use of purified antigens for the diagnosis of schistosomiasis in the field is discussed. (+info)
Performance of the rapid plasma reagin and the rapid syphilis screening tests in the diagnosis of syphilis in field conditions in rural Africa.
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OBJECTIVES: To assess the rapid plasma reagin (RPR) test performance in the field and to evaluate a new rapid syphilis test (RST) as a primary screen for syphilis. METHODS: 1325 women of reproductive age from rural communities in the Gambia were tested for syphilis seropositivity using a RPR 18 mm circle card and a RST strip. Within 1 week a repeat RPR and a TPHA test were carried out using standard techniques in the laboratory. RESULTS: Comparing field tests to a diagnosis of "active" syphilis defined as laboratory RPR and TPHA positive, the RPR test was 77.5% sensitive and 94.1% specific; the RST was 75.0% sensitive and 95.2% specific. The RST was easier to use and interpret than the RPR test especially where field conditions were difficult. In this setting with a low prevalence of syphilis in the community (3%), the chance of someone with a positive test being confirmed as having serologically active syphilis was less than 50% for both tests. CONCLUSIONS: The appropriateness of syphilis screening using RPR testing in antenatal clinics and health centres should be questioned if there is a low prevalence in the population, conditions for testing are poor, and resources limited. There is still an urgent need for an appropriate rapid syphilis test for field use. (+info)
The VDRL test in a blood transfusion service.
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A survey has been made of the results of 12 months' VDRL screening in a blood transfusion service. Positive VDRL tests were found on 318 of the 73 350 blood donations collected during 1974. Thirty-four tests confirming specific treponemal infection were found in 24 donors. A battery of confirmatory tests showed the remaining 284 positive VDRL reactions from 235 donors to be biological false positive (BFP) results, and, of these, one-third were considered entirely negative by the reference laboratory. BFP reactions were commoner in female donors than in males, and a higher incidence than expected was observed in younger female donors and older male donors. A marked seasonal incidence was noted, 65% of all BFP tests from the transfusion service being found in the four colder months of May to August. Although some differences exist between the group as a whole and the 36 donors (15.3%) found to have BFP results on more than one occasion during the year, there is little evidence from these studies to suggest that regular blood donation per se is a contributing factor to the finding of a BFP result in VDRL screening. It is probable that the population tested regularly by the blood transfusion service reflects a small but representative sample of the community as a whole. (+info)