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Biomedical subjects

I R Tizard

Publications and source records attributed to I R Tizard.

At least 37 records · Page 2Linked to original sources
PubMed1980

Hemolytic complement and serum C3 levels in Zebu cattle infected with Trypanosoma congolense and Trypanosoma vivax and the effect of trypanocidal treatment.

Total hemolytic complement and C3 levels were found to drop to 6.25% and 50% of preinfection levels, respectively, during trypanosome infections. Chemotherapeutic elimination of the trypanosomes with Berenil led to recovery of preinfection levels within 7 days and 11 days when cattle infected with Trypanosome congolense and Trypanosoma vivax, respectively, were treated 37 days after onset of infection. Recovery was slower in T. vivax-infected cattle treated on day 50. Berenil treatment had no effect on complement levels in control animals. The possible causes and implications of these low complement levels in bovine trypanosomiasis are discussed.

Amidines↗
PubMed1980

Indirect hemagglutination employing enterobacterial common antigen and Yersinia somatic antigen: a technique to differentiate brucellosis from infections involving cross-reacting Yersinia enterocolitica.

The existence of enterobacterial common antigen in Yersinia enterocolitica and its absence in Brucella abortus were utilized in an attempt to provide a method to distinguish Brucella infections from infections with cross-reacting Yersinia. The indirect hemagglutination test was employed for this purpose. In experimental laboratory animals, the presence of anti-enterobacterial common antigen was found to be indicative of prior exposure to Y. enterocolitica rather than B. abortus. In cattle, however, low titers of anti-enterobacterial common antigen were present in all animals. It was observed that anti-enterobacterial common antigen titers either equaled or exceeded anti-Yersinia O titers in Yersinia-exposed animals, whereas in animals infected with B. abortus the anti-Yersinia O titer generally exceeded the anti-enterobacterial common antigen titer.

Animals↗
PubMed1980

Studies on the relationship between Yersinia enterocolitica IX and Brucella abortus agglutinins in naturally infected animals.

Attempts were made to define the Brucella abortus and Yersinia enterocolitica IX infection status of animal populations by means of selected agglutination tests. The Brucella abortus O, the Yersinia enterocolitica IX OH and the Y enterocolitica IX H agglutinin titres were measured in a large number of cattle, goat and pig sera In the goats and, to a much lesser extent, the pigs, the relationships between these titres suggested that Yersinia infection was common. In contrast, the results from the cattle sera were complex and tended to indicate the presence of both Yersinia infection and brucellosis.

Agglutinins↗
PubMed1980

Accumulation of phospholipase A1 in tissue fluid of rabbits infected with Trypanosoma brucei.

Samples of tissue fluid were obtained from plastic cages implanted subcutaneously in rabbits. A phospholipase A1 similar to that found in Trypanosoma brucei appeared in the tissue fluid about seven days after infection with this parasite, increasing with parasite burden, and reaching levels of more than 5 nmol phosphatidylcholine hydrolysed per min per ml tissue fluid. The large amount of phospholipase A1 found free in the tissue fluid appeared to be of trypanosomal origin and was either secreted by living parasites or released from dying organisms. Phospholipase A1 was detectable in blood plasma from the infected rabbits, but at a level considerably lower than in the tissue fluid. An inhibitor of the phospholipase was present in the plasma after the first two week of infection which may be partly responsible for this lower level.

Animals↗
PubMed1980

Immunosuppression in bovine trypanosomiasis. The establishment of "memory" in cattle infected with T. congolense and the effect of post infection serum on in vitro (3H)-thymidine uptake by lymphocytes and on leucocyte migration.

Cattle infected with Trypanosoma congolense were intravenously immunized with Leptospira biflexa 15 days after trypanosomal infection. The primary immune response to L. biflexa was considerably reduced as compared to uninfected controls. The infected cattle mounted a secondary response when they were cured of trypanosomes by treatment with Berenil 25 days after infection and re-immunized 8 days later. The mean secondary response in these previously infected animals was lower tha, but not significantly different from that of the uninfected control animals. Serum collected 15, 20 and 25 days after infection was inhibitory to the migration of both autologous and isologous (control) peripheral blood leucocytes. The migration inhibitory activity was abolished by heating the serum at 56 degrees C for 30 minutes implying the involvement of a heat labile serum component(s). The same serum did not modify the mitogenic effect of PHA on autologous peripheral lymphocytes.

Animals↗
PubMed1980

Studies on the generation of biologically active substances by Trypanosoma theileri in vitro.

Trypanosoma theileri was grown in bovine primary spleen cell cultures. These organisms were tested for phospholipase activity which was found to be very low, for haemolytic activity which was very weak and for lymphocyte mitogenicity which was found to be absent. High concentrations of T theileri were found to activate bovine complement probably by both the alternate and classical pathways. There was no evidence that these organisms exerted any significant toxic effect in vitro or in vivo. This is compatible with the known low pathogenicity of this species.

Animals↗
PubMed1980

Inhibition of leukopoiesis by sera from Trypanosoma congolense infected calves: partial characterization of the inhibitory factor.

Sera collected from calves infected with Trypanosoma congolense inhibited bovine granulocyte/macrophage colony formation in vitro, but not erythroid colony formation. The inhibitor was found to be TCA precipitable in nature and on Sephadex G-200 chromatography, it was found to elute with the second major peak. Sonicated T. brucei, T. congolense, and T. theileri added directly into the cultures had no effect on granulocyte/macrophage colony formation, but induced significant enhancement of erythroid colony formation.

Animals↗
PubMed1979

Growth agglutination and growth inhibition tests in the diagnosis of brucellosis.

Growth agglutination and growth inhibition tests were established for the diagnosis of Brucella abortus infection. The former involves the agglutination of living organisms while the latter is a bactericidal test. Using mouse, guinea-pig, rabbit and bovine serum it was shown that the growth agglutination test is approximately ten times, and the growth inhibition test one hundred times, more sensitive than the conventional tube agglutination test. It is suggested that these techniques may be of assistance in diagnosing bovine brucellosis in situations in which the tube agglutination test results are suspected of being falsely negative.

Agglutination Tests↗
PubMed1979

Suppression of antibody response to Leptospira biflexa and Brucella abortus and recovery from immunosuppression after Berenil treatment.

Zebu cattle infected with either Trypanosoma congolense EATRO 1800 or Trypanosoma vivax EATRO 1721 had suppressed humoral immune responses to Leptospira biflexa injected intravenously and to attenuated Brucella abortus injected subcutaneously. T. congolense infections were more suppressive than T. vivax infections. In cattle infected with T. vivax, the suppression of immune responses to both bacterial immunogens was abrogated when the animals were treated with Berenil at the time of antigen administration. In cattle infected with T. congolense, simultaneous Berenil treatment at the time of vaccination abolished the suppression of immune response to L. biflexa, and lessened but did not abrogate the suppression of immune response to B. abortus.

Amidines↗
PubMed1979

Experimental studies on the serological relationships between Yersinia enterocolitica and Brucella abortus.

Yersinia enterocolitica O9 was shown to provoke O, OH and H antibody response in calves. Brucella abortus failed to generate Yersinia H antibody response and generated Brucella O antibodies that cross-reacted with Yersinia O and OH antigens. The presence of Yersinia H agglutinins along with a higher titre of Yersinia OH antibody than Brucella O antibody is suggestive of subclinical infection with yersiniosis rather than brucellosis. Cross-absorption of sera from calves with established Yersinia infections indicated that absorption of sera with Brucella O antigens, although completely removing Brucella O antibodies, failed to remove completely Yersinia O, OH and H antibodies, and thus provides an additional method of distinguishing between the two infections.

Agglutination Tests↗
PubMed1979

A simple technique to differentiate between animals infected with Yersinia enterocolitica IX and those infected with Brucella abortus.

While both Brucella abortus and Yersinia enterocolitica IX have O antigens in common, they differ significantly with respect to motility. Thus Br abortus is always non-motile while Y enterocolitica is motile when grown at room temperature. The presence of yersinia H agglutinins in serum can be shown to be evidence of previous exposure to Y enterocolitica. These agglutinins are not generated by brucella infection. A rapid H agglutination test will serve to provide this differentiation without interference from cross-reacting O antigens.

Agglutination Tests↗
PubMed1979

Studies on experimental enteric salmonellosis in ponies.

Clinical, bacteriological, serological and haematological observations were made on 13 adult ponies orally inoculated with Salmonella typhimurium. The results were compared to two control ponies and four others infected by accidental transmission. The clinical responses in inoculated ponies included pyrexia lasting four days and neutropaenia during the first five days after inoculation followed by a neutrophilia. Pyrexia and neutropaenia was associated with maximal shedding of organisms in the rectal faeces. Changes in the character of the faeces occurred between one and two days after inoculation and appeared to be associated with the serological response. Serological responses occurred in all the infected ponies except one. At necropsy, of the 14 ponies with positive cultures in the colon, seven had negative cultures in the rectal faeces. Serological studies performed on 43 clinically normal horses indicated a correlation between age and salmonella agglutination titre.

Animals↗
PubMed1979

Free flying sparrows as carriers of salmonellosis.

Salmonella typhimurium was isolated from nine of 60 wild sparrows trapped in the Guelph area. While this organism was isolated from birds trapped at several different locations, the highest prevalence was in sparrows trapped in close proximity to an animal clinic. The significance of these findings in relation to human and animal salmonellosis is discussed.

Animals↗
PubMed1978

Mitogenicity of autolysates of Trypanosoma congolense.

Autolysates of Trypanosoma congolense, in subcytotoxic amounts, were found to be highly mitogenic in vitro for the spleen cells of normal mice. Significant amounts of [3H]-thymidine were also incorporated by the responding spleen cells of nu/nu (athymic) mice. In contrast, the spleen cells of cyclophosphamide-treated mice were unresponsive. The findings suggest that a potent B-cell-mitogen is generated by the autolysing T. congolense organism.

Animals↗