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Biomedical subjects

G G Wagner

Publications and source records attributed to G G Wagner.

At least 73 records · Page 4Linked to original sources

Hypocholesterolemia and hypocortisolemia in acute and terminal Babesia bovis infections.

Sera from Babesia bovis-infected cross-bred cows and purebred steers were evaluated throughout the course of acute Babesia bovis infection for cholesterol and cortisol concentrations. Cholesterol and cortisol values of surviving cattle became markedly reduced (less than 50% of normal values) during the acute phase of the disease, Days 10-15 postinoculation, and returned to essentially normal values by the end of the 35 day experimental period. The combined control group values were approximately 2.98 mM/l cholesterol and 0.085 mM/l cortisol throughout the experimental period. The results suggest that if normal synthesis of cholesterol by hepatocytes or other tissues is not maintained, then cholesterol-derived compounds such as cortisol may not be produced at levels adequate to protect against the effects of stress and cell damage during the disease process.

Animals↗

Ultrastructure of Babesia bovis sexual stages as observed in Boophilus microplus cell cultures.

Propagation of Babesia bovis in a Boophilus microplus cell line resulted in the appearance of the sexual stage of the parasite normally found only within tick intestine. These sexual stages, which possessed spike-like projections containing microtubules, were present in the medium and within cultured cells. Other ultrastructural characteristics of this sexual stage are described.

Animals↗

Survival of carrier erythrocytes in splenectomized calves.

Carrier erythrocyte survival was investigated in intact and splenectomized calves. Survival curves for both were biphasic, with a characteristic early loss of 10% to 15% of the carrier cells in intact calves followed by a half-life of 22 to 24 days. In splenectomized calves, 50% to 75% of the carrier cells disappeared from circulation in the first 24 hours. The 2nd phase of survival showed a 44-day half-life for the remaining carrier cells. Erythrocytes from splenectomized calves appeared to be permeable to [14C]sucrose and were more susceptible to irreversible hemolysis from the dialysis encapsulation procedure. Blood volume determination showed a 22% decrease after splenectomy.

Animals↗

The bovine immune response to tick-derived Babesia bovis infection: serological studies of isolated immunoglobulins.

A cryopreserved stabilate was prepared from Babesia bovis-infected Boophilus microplus ticks. The stabilate was used to infect a group of mature Bos taurus-Bos indicus cows. The survivors of the initial infection were rechallenged with the homologous stabilate 65 days later. All cows reacted parasitologically after primary challenge, and most responded serologically. With the exception of two cows, those not responding serologically died of acute babesiosis. The two that survived the primary challenge, but did not produce detectable antibody, died after secondary challenge. All serologically-positive cows survived the secondary challenge. Complement fixation and indirect fluorescent antibody tests were performed on all cows' sera and, in addition, immunoglobulin fractions were prepared and analyzed from selected sera. Both IgM and IgGl were important in the initial response. A secondary IgM response was noted by complement fixation assays. No activity was detected in any IgG2 fraction.

Animals↗

Clinical and serological evidence of bovine babesiosis and anaplasmosis in St. Lucia.

One hundred fifty-nine Holstein calves were imported into St. Lucia from the U.S.A. An outbreak of babesiosis occurred 17 days post-arrival, and an outbreak of anaplasmosis occurred 5 months after importation. Sera obtained 3, 6, and 12 months post-importation revealed a high prevalence of IFA titres to Babesia bovis and B. Bigemina 3 months after arrival and an increase in titres to Anaplasma marginale 6 months after arrival. Sera obtained from native cattle from several places on the island indicated infection rates of 80, 65 and 64% with A. marginale, B. bigemina and B. bovis, respectively. The rapid card test only indicated a 25% prevalence of infection of native cattle by A. marginale. This low prevalence was probably due to deterioration of serological activity during shipment.

Anaplasma↗

Serological prevalence of bovine babesiosis in Guyana.

The serological prevalence of bovine babesiosis in Guyana was determined utilising the indirect fluorescent antibody (IFA) and the complement fixation (CF) tests. Babesia bigemina IFA and CF antibody activity was detected in 80% and 40% respectively of the sera from native cattle while IFA and CF antibody activity to Babesia bovis was observed in 61% and 16% of the sera. The prevalence of antibody was compared between calves less than 6 months of age and mature cattle. There was little difference between the CF and IFA tests for B. bigemina in the calves but the prevalence of IFA antibody activity to B. bovis in calves and to B. bovis and B. bigemina was greater in adult cattle. Examination of sequential serum samples from imported calves revealed that CF antibody activity appeared earlier but by day 51 following exposure to natural infection the prevalence of antibody as determined by both tests was the same.

Animals↗

Recrudescence of Anaplasma marginale induced by immunosuppression with cyclophosphamide.

Eight doses of cyclophosphamide (5 mg/kg), at 2-day intervals between doses, were administered IV to Anaplasma-carrier splenectomized calves. Significant decreases in serum immunoglobulins, diminished complement-fixing antibody response, and transitory leukopenia were associated with the treatment. Recrudescence of clinical Anaplasma infection occurred after the 5th dose of cyclophosphate was given and was characterized by rapid increase in parasitemia, marked decrease in PCV, and mortality. The results of the present study indicated that humoral mediated immunity may contribute to the maintenance of a state of equilibrium in the host-parasite relationship and that suppression of humoral immune responses may alter the course and outcome of infection in Anaplasma carriers.

Anaplasmosis↗

Bovine babesiosis in northern Mexico.

The occurrence of Boophilus microplus infections accompanied by bovine babesiosis was confirmed for 2 locations in northern Mexico. The confirmation at one location was made by transferring whole blood to a splenectomised calf which subsequently developed an acute Babesia bovis infection. Examination of thin blood smears from a suspect animal at the second location revealed B. bovis-infected erthrocytes. A serological survey of other herd members at both locations showed antibody activity against both Babesia and Anaplasma spp.

Anaplasmosis↗

Comparison of four serological tests in the diagnosis of caprine brucellosis.

Results from four serological tests for diagnosing brucellosis--serum tube agglutination (SAT), agar gel immunodiffusion (AGIT), Rose Bengal plate (RBPT) and complement fixation (CFT)--were compared using sera from goats from farms infected with Brucella melitensis. Ninety-two goats were negative and 29 positive to all four tests. The remaining 85 reacted to one or more tests. The RBPT was the most sensitive test and the AGIT the most specific, when compared with the CFT. The results suggest that the SAT adds little information when used with other tests but that RBPT and AGIT are useful for testing caprine brucellosis where facilities for the CFT are not available.

Agglutination Tests↗

Antibody-dependent cell-mediated cytotoxicity in cattle: activity against 51Cr-labeled chicken erythrocytes coated with protozoal antigens.

Bovine mononuclear cells in the presence of bovine anti-chicken erythrocyte sera at high dilutions induce release of chromium-51 from labeled chicken erythrocytes. Bovine effector cells are capable of recognizing both bovine immunoglobulin G(1) and bovine immunoglobulin G(2); in contrast, human effector cells only recognize immunoglobulin G(1). Effector cell activity of bovine mononuclear cells is equally distributed between peripheral blood and spleen. As in other species, thymus and lymph node cells exert no antibody-dependent effect, although some direct cytotoxicity by lymph node cells may be observed. Antibody-dependent cell-mediated cytotoxicity against a bovine cell line can also be detected. By using a tannic acid technique, it was found that chicken erythrocytes coated with Theileria parva piroplasm antigen or with Trypanosoma rhodesiense variant-specific coat antigen form suitable targets for bovine antibody-dependent cell-mediated cytotoxicity assays. By using such targets, a moderate degree of direct cytotoxicity by bovine mononuclear cells, in the absence of antibody, is always observed; this may be reduced by choosing optimal conditions of tannic acid treatment and antigen sensitization and by the use of short incubation periods for the cytotoxicity assay. Observations have been made on the variant specificity, time course of appearance, and association with immunoglobulin G(1) of the antibody activity responsible for cell-dependent cytotoxicity against chicken erythrocytes coated with T. rhodesiense antigens. The potential usefulness of this technique in the analysis of protective immune responses against protozoal infections is discussed.

Animals↗

East Coast fever: cultivation in vitro of cell-free schizonts and merozoites of Theileria parva and their immunogenicity in cattle.

Cell-free schizonts and merozoites of Theileria parva and Theileria lawrencei, derived from parasitized lymphoid cell lines, were propagated in vitro using enriched medium. Use of radioisotopic markers showed that the bovine cell-independent parasites passed through a limited but marked replication by day 4. If normal bovine RBC were inoculated in vitro with the cell-free merozoites, development of piroplasms in the RBC occurred. Electron microscopic studies of the merozoites and piroplasms revealed their structure to be similar to previous descriptions. Cattle inoculated with T parva merozoites and schizonts and later challenge exposed with homologous stabilate developed leukopenia, showed low macroschizont index, and survived longer than unvaccinated controls.

Animals↗

Purification and characterization of precipitating antigens from Theileria parva.

Precipitating antigens from Theileria parva have been partially purified. Two antigens from each of the schizont and piroplasm stages of the parasite were identified; the major antigens from the two stages shared the same specificity. The antigens showed considerable molecular heterogeneity, almost certainly a result of the preparative method, and they always contained large amounts of DNA. The piroplasm antigens were of parasite nuclear origin and the schizont antigens were probably of the same origin. The antigens were weakly antigenic, and the activity against them of humoral antibody from cattle immune to East Coast fever was low. These antigens do not appear to induce protection against East Coast fever.

Animals↗

Sex differences in corticosteroids in man.

The serum concentrations of progesterone (P), 17-OH-progesterone (17-OHP), 11-deoxycorticosterone (DOC), corticosterone (B), 11-deoxycortisol (S), 18-OH-11-deoxycorticosterone (18-OH-DOC), aldosterone (Aldo) and cortisol (F) were measured in 18 normal men (M), 14 normal women in the folicular phase (FF) and 14 normal women in the luteal phase (FL) of menstrual cycle from blood samples obtained between 0800 and 0900 h. Steroids were estimated by a sensitive and specific radioimmunoassay allowing the simultaneous determination of all steroids studied from one 3 ml serum sample. The mean steroid concentrations (ng/1dl) in FF were found to be as follows: P, 20.3; 17-OHP, 58; DOC, 3.8; B, 241; S, 20.7; 18-OH-DOC, 12.3; Aldo, 8.8; F, 9860. Apart from P, steroid concentrations in FF were significantly lower than in M. Serum 17-OHP, DOC, B and Aldo in FF were significantly lower than in FL. With the exception of P, there were no significant differences of mean steroid concentrations between M and FL.

17-Hydroxycorticosteroids↗

[Artefacts of lipid electrophoresis: edge zoning effects in agarose gel (author's transl)].

The evaluation of lipid electropherograms obtained by electrophoresis in agarose gel is sometimes difficult owing to methodological errors, e. g. the artificial mal-formation of individual lipoprotein bands. It was shown that this "edge zoning effect", e. g. resulting from broadened bands with irregular boundries, can be abolished by the addition of EDTA (0,36 g/l buffer) to the gel.

Diagnostic Errors↗

The specific immunoglobulin response in cattle to Theileria parva (Muguga) infection.

Cattle were inoculated with dilutions of Theileria parva (Muguga) stabilate without concurrent antibiotic treatment. The dilutions were selected to induce severe East Coast fever infections, which in some cases would lead to death. Serum samples were collected and the complement fixation (CF), indirect haemagglutination (IHA) and indirect immunofluorescence (IFA) tests were used to detect T. parva serum antibodies. Sera were fractionated on Sephadex G200 to determine the activities of specific immunoglobulin fractions. Sequential production of IgM antibody followed by 7SIg antibody was demonstrated by the IHA and CF tests. All IFA activity was restricted to the 7SIg fraction. Serologic reactions in the IHA test were detected as early as 4 days after inoculation of the stabilate, CF activity after 8 days and IFA activity after 21 days.

Animals↗

Diminished antibody response to rinderpest vaccination in cattle undergoing experimental East Coast fever.

The immunocompetence of cattle undergoing East Coast Fever (ECF) reactions of varying degrees of intensity was evaluated using the neutralising antibody response of these cattle to the vaccine response was found in animals undergoing severe ECF reactions. The results suggest that the massive lymphoid cell involvement of such severe ECF reactions diminishes the immune responsiveness of cattle to rinderpest vaccine.

Animals↗