The effect of dose and concentration on D-xylose absorption in healthy,immature dogs

Nine combinations of dosages and concentrations of D-xylose were given orally to eight clinically normal, immature dogs. The concentrations and dosages of D-xylose consisted of 5%, 10%, and 20% at 250 mg/kg, 500 mg/kg, and 750 mg/kg. Serum samples were collected at 0, 30, 60, 90, 120, and 180 minutes. Serum xylose was quantitated using the phloroglucinol microassay technique. A peak in serum xylose concentration was seen for each treatment combination at 60 or 90 minutes after dosing. The dosage effect was important in influencing serum xylose values (P < 0.0001). As the test solution dosages increased from 250 mg/kg to 500 mg/kg and 750 mg/kg, serum xylose values (when dosage was analyzed over the length of the entire test) rose linearly (R(2) = 0.98). The treatment combinations of 5% and 20% xylose solutions dosed at 750 mg/kg produced the highest serum xylose values at the 60- and 90-minute peak intervals. The independent effect of concentration was significant (p < 0.001) but was overridden by the stronger dosage effect. Serum xylose concentrations varied little statistically (p > 0.05) when the 5%, 10%, and 20% solutions were compared at a specific dosage.     

Evaluation of the importance of centrifugation as a component of zinc sulfate fecal flotation examinations

Fifty canine fecal samples were evaluated by five flotation procedures to compare the sensitivity of the zinc sulfate (ZnSO4) centrifugation flotation test with ZnSO4 flotation tests using benchtop incubation during the flotation period. One or more parasite species were detected in 40 samples. Results showed that centrifugation with ZnSO4 solution was significantly more likely to detect a positive sample than benchtop procedures. The difference in procedures was due primarily to increased detection of Trichuris eggs and Giardia cysts by centrifugal flotation. No significant difference was seen in the ability of benchtop procedures to detect positive samples when tests sat either for 5 or 10 minutes before examination.     

Prevalence of IgG Antibodies to Toxoplasma gondii in Veterinary and Undergraduate Students at Virginia Tech,Blacksburg, Virginia

Toxoplasma gondii is a globally distributed parasitic protozoan that infects humans and other warm‐blooded vertebrates. Felids are the only definitive host for T. gondii, and they excrete oocysts in their faeces. The national prevalence in humans is declining in the United States. This zoonotic organism is of particular interest due to its importance in pregnant women, in individuals with altered immune systems, and in reactivated ocular infections. Exposure to the parasite in humans is usually associated with consumption of raw or undercooked meat or by accidental ingestion of oocysts. It was hypothesized that veterinary students would have a greater chance at exposure to the parasite than an average population of undergraduate students due to increased contact with cats who are infected. A commercially available ELISA was used to examine serum samples from 336 students (252 veterinary students and 84 undergraduate students) at Virginia Polytechnic Institute and State University and the Virginia‐Maryland Regional College of Veterinary Medicine for serum IgG antibodies to T. gondii antigen. The prevalence of T. gondii in these subjects was 5.6% in veterinary school students (n = 252) and 2.4% in undergraduates (n = 84). There was no significant difference (P > 0.05) in the prevalence of T. gondii antibodies in veterinary versus undergraduate students. The overall prevalence of 4.8% in all students in this study reflects the continuing decline of antibodies to T. gondii in humans in the United States.     

Resistance of St. Croix lambs to Haemonchus contortus in experimentally and naturally acquired infections.

Parasitological and immunological parameters of experimental or naturally acquired infections with Haemonchus contortus were compared in St. Croix and Dorset lambs. In experimental infections, St. Croix lambs developed significantly greater levels of resistance to H. contortus, following primary exposure, as compared with Dorset lambs. This resistance was influenced both by age and by prior exposure to parasites. In grazing experiments on H. contortus-infected pasture, St. Croix lambs shed significantly fewer eggs as early as 5 weeks following initial exposure. Further, St. Croix lambs had more than 99% fewer worms in the abomasum at necropsy compared with age-matched Dorset lambs. Lymphoproliferative assays using peripheral blood mononuclear cells and antigen-specific serological tests demonstrated only minor differences in immune responsiveness between the two breeds despite the dramatic parasitological differences. Similarly, abomasal mucus from both breeds had elevated levels of parasite-specific antibodies and contained substances mediating larval paralysis. In contrast, St. Croix lambs which had become resistant to nematode infection had dramatically higher numbers of globule leukocytes in the abomasal mucosa compared with Dorset lambs.     

Evaluation of the results of ELISA in the quantitative determination of antibodies against infectious bursitis in poultry]

Specific antibodies were investigated in serums of chicks vaccinated with live vaccine and revaccinated with inactivated vaccine against the infectious bursal disease virus, using three methods. An ELISA technique was used to determine antibody titres at a fourfold serum dilution; the reaction was evaluated visually. The results were compared with the titres of neutralizing antibodies and percentage of samples with precipitin activity (Fig. 1). The average values of neutralizing antibody titres and ELISA titres were found to have an analogical pattern; a decrease in maternal antibodies on the first days of chick life and an increase in the antibodies after vaccination, accompanied by an increase in precipitin activity, were typical in these tests. Using the different ELISA technique, 138 samples of fowl serum were examined (Fig. 2). The high correlation, r = 0.85, was found between the ELISA titres determined by visual reading of the reaction within the fourfold serum dilutions and the absorbance values determined at single serum dilution. Applying a spectrophotometer programme, a scale of antibody quantification was made up pursuant to the intensity of immunoenzymatic reaction. For the purposes of method reproducibility, the evaluation was made within the average values of absorbance of positive serum on the one hand and of negative serum on the other. The span of these values was divided into ten equal parts, designated by degrees 0 to 9. Corresponding degrees of positivity were assigned to the examined samples in dependence on the determined value of absorbance (Fig. 3). The correlation r = 0.61 was found between the ELISA values and the titres of neutralizing antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)     

Utility of diagnostic tests used in diagnosis of infection in dogs experimentally inoculated with a North American isolate of Leishmania infantum infantum

Eight female beagles were infected with 1 x 10(7) (low dose, LD) or 2 x 10(8) (high dose, HD) promastigotes of a North American isolate of Leishmania infantum infantum (LIVT-1 strain) isolated from naturally infected Virginia Foxhounds. Two female beagles served as negative controls and 2 male beagles chronically infected (> 3 years) with Leishmania infantum chagasi were positive controls. Bone marrow (BM) and lymph node (LN) aspirates were collected every 6-8 weeks for cytologic evaluation, parasite culture, and polymerase chain reaction (PCR). Serum samples were collected monthly for determination of serologic responses by indirect fluorescent antibody test (IFAT) and diagnostic rK39 antigen. Cultures of BM and LN aspirates and cytology evaluation were consistently positive in positive control dogs during the course of study. Negative control dogs were negative on BM and LN cultures and on cytologic evaluation of aspirates. Amastigotes were present on cytological examination of BM aspirates in 2 experimentally infected dogs. Cultures of LN aspirates were positive on 22 samples, whereas BM cultures were positive on 12 samples for all dogs. IFA titers ranged from 0 to 1 :400 in experimentally infected dogs during the course of the study. Recombinant K39 immunoassay tests were consistently positive in positive control dogs and in the HD dogs by approximately 8 weeks after infection. BM PCR products were identified more consistently in the HD dogs compared with the LD dogs. Kappa statistics indicated PCR correlated better with cultures and cytology than did IFAT or the rK39 immunoassay results in the experimentally infected dogs.     

Evaluation of the results of the ELISA reaction in the serologic diagnosis of bovine leukosis

Blood serum samples collected from two cattle herds were examined by the immunodiffusion test (ID), pseudotype neutralization test (PsNT) and ELISA procedure for the presence of antibodies to the bovine leukosis virus. The spectrophotometric readings of the ELISA procedure were evaluated on the basis of the arithmetical mean (means) and standard deviation (Sd) of the values obtained in negative controls. The examination of 208 samples of serums taken in the negative herd confirmed in all cases a negative reaction in the ID and PsNT tests. In all samples the ELISA reaction values remained within the range delimited by the relation of means + 3 Sd, which was defined as the threshold value of positive reaction. Out of the 223 serum samples of the positive herd, 132 samples were within the range below means and five of them were leukosis-positive in PsNT. Twenty-nine samples were within the range of means to means + 3 Sd; five of them were found positive in PsNT and three in the ID test. Sixty-two samples were above the threshold value of positivity; of these, positivity was confirmed in 58 cases by PsNT and in 55 cases by ID. As the results suggest, the ELISA procedure is suitable for the detection of animals positively reacting to bovine leukosis, to which special attention should be paid.