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Biomedical subjects

G G Wagner

Publications and source records attributed to G G Wagner.

At least 19 recordsLinked to original sources
PubMed1992

Babesia bigemina: quantitation of infection in nymphal and adult Boophilus microplus using a DNA probe.

Candidates for a subunit vaccine against bovine babesiosis include surface proteins of infective forms found in the salivary glands of tick vectors. However, low numbers of infective forms are present within ticks and hinder analysis of this stage. To solve this problem, conditions which yield high numbers of infective forms were investigated with the use of a Babesia bigemina-specific DNA probe. DNA from progeny of female Boophilus microplus infected with B. bigemina was hybridized to probe DNA to detect and quantitate infection. There was no difference in the prevalence of infection in progeny of three strains of Bo. microplus. However, within a strain, prevalence could be increased to 30% by combining selection of progeny from heavily (3+) infected female ticks and selection of eggs laid 120 hr postengorgement. Quantitation of infective forms within pooled salivary gland preparations of 10 infected nymphal and adult Bo. microplus demonstrated that Day 9 and 10 nymphal ticks contained the highest numbers of parasites and represented approximately 10(6) infective forms. This number of infective forms is suitable for isolation and further characterization.

Animals↗
PubMed1992

Monthly incidence of Theileria cervi and seroconversion to Babesia odocoilei in white-tailed deer (Odocoileus virginianus) in Texas.

Monthly monitoring of fawns collected from an area in Texas endemic for Theileria cervi and Babesia odocoilei showed that transmission of T. cervi occurred during July and August, a time period consistent with the occurrence of Amblyomma americanum. Seroconversion to B. odocoilei occurred during October to December and possibly continued through January and February. The time of seroconversion was more suggestive of transmission of B. odocoilei by Ixodes scapularis than by Amblyomma americanum.

Animals↗
PubMed1991

Cell-mediated immune responses to Babesia bovis merozoite antigens in cattle following infection with tick-derived or cultured parasites.

Peripheral blood mononuclear cells from cattle experimentally infected with Babesia bovis were examined for parasite-specific cell-mediated immune responses. Unfractionated merozoites and soluble and membrane fractions derived from merozoites were all antigenic for immune cattle, although the membrane fraction was the most stimulatory. Cattle responded to different antigenic fractions in a differential manner, and only that animal immunized with autologous cultured parasites responded to parasitized erythrocyte culture supernatants. Plastic-adherent cells (presumably monocytes/macrophages) were required for a proliferative response to babesial antigens but not to the T-cell mitogen concanavalin A, suggesting that babesial proteins are not simply mitogenic for T cells. Lymphocyte responses directed against a different hemoparasite from Mexico, Babesia bigemina, indicate that this parasite shares cross-reactive T-cell epitopes with B. bovis. These studies define a system whereby T lymphocytes from babesia-immune cattle can be used in proliferation assays to identify babesial merozoite antigens which are immunogenic for T cells. Because identification of helper T-cell epitopes is important for the design of a babesial subunit vaccine which will evoke anamnestic responses, the studies described here provide a basis for such experiments.

Animals↗
PubMed1991

Gastric emptying in infants and children: limited utility of 1-hour measurement.

Gastric emptying measurements were performed in infants and children at 1 and 2 hours after a liquid feeding. The 1-hour measurements were predictive of only 58% of the variability in the 2-hour measurements, indicating that the 1-hour measurement was not a good predictor of the 2-hour measurement. Gastric emptying measurements in children should be continued until 2 hours after feeding unless rapid emptying is observed during the 1st hour of the study.

Child, Preschool↗
PubMed1991

Comparative studies of Babesia spp. from white-tailed and sika deer.

Babesia odocoilei from white-tailed deer (Odocoileus virginianus) in Texas (USA) and B. capreoli isolated from sika deer (Cervus nippon) in Ireland were compared morphologically and antigenically. Babesia odocoilei and B. capreoli paired pyriforms resembled each other closely when in sika deer, but B. odocoilei pyriforms in white-tailed deer were slightly different. Babesia odocoilei in white-tailed deer also differed from B. odocoilei and B. capreoli in sika deer in the frequency of its developmental forms. Indirect immunofluorescence antibody test titres showed that there was some antigen cross-reactivity, but not as much as between B. capreoli and the bovine parasite, B. divergens. The Babesia spp. from deer that we studied appear to be distinct but related species. The low infectivity of B. odocoilei for a splenectomised sika deer suggests that sika deer in North America are probably not very susceptible to this parasite in the wild.

Animals↗
PubMed1990

Microwave fixation: in situ tick (Acari: Ixodidae) histoanatomy, thin sectioning of tick tissues, and antigen preservation in mouse spleen.

Microwave irradiation was used for the fixation of eggs, nymphs, and adult Boophilus spp. ticks. Although optimal temperatures for fixation of the different tick stages varied, heating to 58 degrees C of adult ticks submerged in either PBS or fixative was found to be sufficient. After microwave fixation, whole adult ticks, hand held, were sectioned with a sharp razor blade. The resulting sections revealed the in situ histoanatomy of the tick. Thin sections of ticks were obtained after either paraffin or polyester wax embedding. Microwave fixation combined with polyester wax embedding made serial thin sections of the different stages of Boophilus ticks possible. The technique preserved antigens as demonstrated by the immunostaining of lymphocytes and erythrocytes infected with Babesia microti in mouse tissues subjected to the same treatment as the ticks. With the microwave fixation-polyester wax technique, the specimen preparation time from fixation to the section on the glass slide was reduced to less than 8 h.

Animals↗
PubMed1989

Babesia bovis: gene isolation and characterization using a mung bean nuclease-derived expression library.

Genomic DNA prepared from erythrocyte cultures of Babesia bovis merozoites was digested with mung bean nuclease and used to construct a lambda gt11 expression library of B. bovis recombinants. Immunoscreening with two polyclonal antibody probes detected multiple recombinants from which two, designated Bb-1 and Bb-3, were chosen for further analysis. Monospecific immunoglobulins isolated from the screening sera using nitrocellulose-bound fusion proteins were employed to determine the native molecular weight and the intracellular location of the babesial proteins encoded by the recombinants. Clone Bb-1 encodes an antigen of 77,000 Da located at the apical end of the intraerythrocytic parasite. A protein of 75,000 Da encoded by clone Bb-3 is associated with the infected red blood cell cytoplasm and/or membrane but not with the merozoite.

Animals↗
PubMed1989

Serological prevalence and isolation of Babesia odocoilei among white-tailed deer (Odocoileus virginianus) in Texas and Oklahoma.

Serum samples collected from 581 white-tailed deer (Odocoileus virginianus) from Texas and from 124 white-tailed deer from Oklahoma were tested by the indirect fluorescent antibody technique against Babesia odocoilei. Prevalence of seropositive reactors varied from site to site in both states. Prevalence rates were statistically ranked as high, intermediate or low. Deer less than 12-mo-old had a significantly lower prevalence than all other age classes.

Age Factors↗
PubMed1988

Effect of carrier erythrocytes containing inositol hexaphosphate on Babesia microti infection.

Erythrocytes containing inositol hexaphosphate (IHP) were administered to mice. Mice were then challenged with Babesia microti. Mice receiving IHP carrier erythrocytes had significantly lower percentages of parasitaemias on days 3, 5 and 7 after infection. Carrier erythrocytes containing IHP have altered P50 oxygen values. Thus, carrier erythrocytes containing IHP may be useful in treating naive animals before transporting into areas endemic for babesiosis.

Animals↗
PubMed1988

Some effects of the trypanocidal drug isometamidium on encapsulation in bovine carrier erythrocytes.

Bovine erythrocyte exposure to isometamidium chloride causes increased osmotic fragility. Control cells tolerated up to 1 mg/ml drug with no effects. Carrier erythrocytes were highly susceptible to drug, with increased osmotic fragility and decreased encapsulation potential of sucrose and inulin. Scanning electron micrographs of control and carrier erythrocytes exposed to drug revealed the formation of enkephalocytes with carrier erythrocytes. Control erythrocytes showed greater tolerance to the drug. Apparently, access of the drug to the interior of the erythrocyte membrane allows the drug to be more interactive with the membrane.

Animals↗
PubMed1988

Comparison of the effect of T-2 toxin with that of dexamethasone or cyclophosphamide on resistance to Babesia microti infection in mice.

The effect of T-2 toxin on host resistance to acute and latent Babesia microti infections was evaluated in mice and was compared with the effects of the immunosuppressive drugs dexamethasone and cyclophosphamide. Mice with acute or latent B microti infection were treated with 2 mg of T-2 toxin/kg of body weight, 0.2 mg of dexamethasone/kg, or 30 mg of cyclophosphamide/kg daily for 5 days. Treatment with dexamethasone or cyclophosphamide caused significant (P less than 0.05) increases in Babesia parasitemia during acute infection and significantly (P less than 0.05) prolonged the duration of parasitemia during acute babesiosis. Treatment with T-2 toxin caused a transient significant (P less than 0.05) increase in Babesia parasitemia on day 10 after acute infection and numerical, though statistically nonsignificant, increases in the maximal level and duration of parasitemia during acute babesiosis. Significant (P less than 0.005) recrudescence of parasitemia was observed in the dexamethasone- and cyclophosphamide-treated mice with latent Babesia infection. Treatment with T-2 toxin did not cause recrudescence of parasitemia in mice with latent Babesia infection.

Acute Disease↗
PubMed1988

In vitro cultivation of a Babesia isolated from a white-tailed deer (Odocoileus virginianus).

Pyriforms and ring forms of Babesia odocoilei were detected in thin blood smears obtained from a white-tailed deer killed by a hunter in Anderson County, Texas. Erythrocytes from the deer were cultured and the parasites maintained through 8 serial subcultures during 1 mo. The parasite was successfully established in culture using Medium 199 supplemented with either 20% deer serum or 40% normal adult bovine serum. The highest parasitemia observed was 30% and more than 4 parasites per erythrocyte were often observed. Cultured B. odocoilei remained infective for a susceptible white-tailed deer.

Animals↗
PubMed1985

Demonstration of vaccine-induced immunity to anaplasmosis without induction of persistent postvaccinal complement-fixing and agglutinating antibodies in yearling steers.

The protective effect and anti-Anaplasma complement-fixing and agglutinating antibody responses induced in yearling steers by vaccination with an inactivated Anaplasma marginale vaccine were evaluated by challenge exposure. Eleven 12- to 14-month-old Hereford X Angus steers were randomly allotted into 6 principals and 5 controls. The principals were injected IM with 5 ml of vaccine on days 0 and 21. On day 70, the 11 steers were challenge exposed by IV inoculation of A marginale-infected blood. After a prolonged prepatent period, the vaccinated steers developed a significantly (P less than 0.01) lower A marginale parasitemia (8.0%) than did the nonvaccinated controls (26.3%). The persistence of a greater than or equal to 0.5% parasitemia was significantly (P less than 0.025) reduced from 34 days in the control to 21 days in the vaccinated group. The percentage reduction in PCV was significantly (P less than 0.025) less in the vaccinated group (34%) as compared with the controls (57%). Complement-fixing and agglutinating antibody responses induced by vaccination did not persist for more than 21 days after the 2nd vaccine injection and did not interfere with positive seroconversion resulting from challenge exposure.

Agglutination Tests↗
PubMed1984

Serological prevalence of bovine babesiosis in Mali.

A serological survey of cattle in Mali was carried out to determine the prevalence of antibody activity to Babesia bovis and B. bigemina. It was found that the level of B. bovis infection as indicated by antibody activities was too low to be of immediate concern. However, the serological prevalence of B. bigemina was high and this may indicate a potential disease problem. It was also found that when zebu and N'Dama cattle grazed together the N'Dama were twice as likely to have positive titres to Babesia as were the zebus.

Age Factors↗
PubMed1984

13C NMR studies of glycolysis in intra- and extra-erythrocytic Babesia microti.

Metabolism in the erythrocytes of normal mice and mice infected with Babesia microti has been monitored non-invasively by high resolution 13C NMR spectroscopy. The conversion of [U-13C]glucose to lactate in both normal and infected cells together with the effect of the trypanocidal drug, 4,4'-diamidinodiazoaminobenzene diaceturate, on glycolytic rates were monitored. These studies show that erythrocytes utilize [U-13C]glucose at a rate of 3 X 10(-12) mumol cell-1 min-1 at 35 degrees C while parasitized cells consume 2.9 X 10(-11) mumol cell-1 min-1 and produce lactate as the sole end-product. This rate decreases to 9 X 10(-12) mumol cell-1 min-1 on the addition of 0.75 mM drug.

Animals↗