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Biomedical subjects

E Studer

Publications and source records attributed to E Studer.

At least 37 records · Page 2Linked to original sources
PubMed1986

Embryo transfer and transmission of bovine leukosis virus in a dairy herd.

Transmission of bovine leukosis virus (BLV) by embryo transfer was investigated in a large commercial Holstein herd. One hundred and sixteen calves, transplanted as embryos from BLV-positive cows into BLV-negative heifers, were serologically negative, as were recipients, whereas 5 of 29 (17%) calves transplanted as embryos into BLV-positive recipients were infected with BLV, as evidenced by antibodies in the agar gel immunodiffusion test.

Animals↗
PubMed1983

Binding sites for monoclonal antibodies and for mRNPs on SV40 large T-antigen determined with a cleavage map.

Immune complexes of simian virus 40 large T-antigen with monoclonal papovavirus protein antibodies PAb 416, PAb 402, or PAb 423 were bound to protein-A-Sepharose and then cleaved into discrete fragments by limited tryptic proteolysis. PAb 402 protected a specific cleavage site, located approximately within amino acid residues 450-500, from tryptic proteolysis; PAb 423 protected another site within residues 675-699. As shown by immunoblotting, 125I-labeled PAb 416 was bound to a 17-kDa N-terminal fragment of large T-antigen (amino acid residues 1-130), and PAb 423 was bound to several overlapping fragments derived from the C terminus of large T-antigen. These monoclonal antibodies were then used as accessibility probes to study the interaction of mRNPs with cytoplasmic large T-antigen. Whereas small T-antigen and nuclear large T-antigen were fully immunoreactive, cytoplasmic large T-antigen reacted poorly with PAb 402 or polyclonal antibodies unless the mRNP moiety was removed by treatment with EDTA/RNase A. In contrast, mRNP/T-antigen complexes were fully immunoreactive with PAb 416 or PAb 423 and did not require treatment with EDTA/RNase A. The results suggest that the binding site of PAb 402 is blocked due to the interaction with mRNPs whereas the N-terminal binding site of PAb 416 and the C-terminal binding site of PAb 423 remain accessible to antibodies.

Antibodies, Monoclonal↗
PubMed1983

Properties of two monoclonal antibodies directed against the Fc and Fab' regions of rat IgE.

Hybridoma antibodies directed against the Fc and Fab portions of rat IgE were produced by immunizing BALB/c mice with rat IgE and fusing the spleen cells with the nonsecreting plasmacytoma P3/X63Ag8.653. Two of the antibodies, designated as A2 and B5, were extensively characterized. Competitive binding experiments using rat IgE from the IR 162 and IR2 immunocytomas and rat IgG indicated that both A2 and B5 were epsilon-chain specific and not anti-idiotype. A2 also exhibited some cross-reactivity with mouse IgE. When IgE was treated with chymotrypsin so as to produce both F(ab')2 and Fab fragments, the enzyme-treated IgE retained reactivity with B5, but the reactivity to A2 was lost. Heat denaturation of IgE at 56 degrees C resulted in a progressive loss of reactivity of the IgE for both A2 and the Fc receptor on rat basophilic leukemia cells; the reactivity of B5 remained unchanged. A2 does not evidently interact with the same site on the Fc of IgE that is involved in binding to the rat basophilic leukemia cell Fc receptor; A2 exerted little influence on the binding of IgE to rat basophilic leukemia cells. Thus, the data indicate that the antigenic site for B5 is in the Fab region of the IgE molecule and that A2 reacts with the IgE Fc. Use of these antibodies to measure cell-bound IgE was also evaluated in dual label experiments, and potential problems in using divalent antibodies to quantitate cell surface antigens are discussed.

Animals↗
PubMed1981

Bovine leukemia virus infection in a large Holstein herd: prospective comparison of production and reproductive performance in antibody-negative and antibody-positive cows.

Serum samples from lactating cows in a purebred Holstein herd were tested annually (from 1977 to 1980) for antibodies to bovine leukemia virus (BLV), using the agargel immunodiffusion test. Production and reproductive variables were obtained from Dairy Herd Improvement Association records. All milk and fat production values were converted to 3.5% fat-corrected milk (FCM). Variables examined included: FCM, 305-day actual; FCM, 305-day mature-equivalent; FCM, total lactation; FCM per day, 305-day actual; total days milked during lactation; days nonlactating; age at calving; calving interval; days open, and number of times bred. Lactations were stratified from 1 to greater than 5 for comparison of variables. A matched case-control analysis was performed to assess the risk of clinical mastitis in BLV-infected cows. The retention of BLV antibody-negative and antibody-positive cows in the herd was compared. There were no significant trends in the means of production and reproductive variables between BLV antibody-negative and antibody-positive cows. The relative risk of clinical mastitis in BLV antibody-positive cows was 1.3, which was not significant (P greater than 0.05). Survivorship analysis over 3 years demonstrated no significant difference in the retention of BLV antibody-negative and antibody-positive cows in the herd. The BLV-infected cows did not have lower milk production, poorer reproductive efficiency, increased prevalence of mastitis, or lesser longevity in the herd than did noninfected cows.

Animals↗
PubMed1978

Postpartum evaluation of bovine reproductive potential: comparison of findings from genital tract examination per rectum, uterine culture, and endometrial biopsy.

The genital tract of 106 cows was evaluated after parturition by rectal palpation and by visual inspection of vaginal discharges. Analysis of these results revealed a significant (P less than 0.01) correlation with the ratings of endometrial biopsies. The most frequent bacterial isolations included Corynebacterium pyogenes, coliforms, or streptococci, or combinations thereof. Abnormal ratings obtained by gross evaluation and by histologic examination were associated principally with C pyogenes. Purulent discharges in particular were highly correlated (P less than 0.01) with infection caused by C pyogenes. Neither the gross genital tract condition nor the uterine histopathology rating was positively correlated with conception rate; however, the association between days open and conception rate was significant (P less than 0.05). Bacterial infections significantly (P less than 0.05) increased the number of services required for conception and significantly (P less than 0.01) increased the number of cows culled because of infertility. Cows up to 4 years old had a 61% 1st-service conception rate compared with 35% for older cows, and this difference was significant (P less than 0.05). The development of one or more postpartum diseases significantly (P less than 0.05) reduced 1st-service conception rate, whereas milk production was negatively correlated (P less than 0.05) with conception.

Animals↗