20 research outputs found
Track D Social Science, Human Rights and Political Science
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138414/1/jia218442.pd
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Escherichia coli Isolatesâ Serotypes, Genotypes, and Virulence Genes and Clinical Coliform Mastitis Severity
Dairy cattle with clinical mastitis caused by Escherichia coli exhibit a wide range of disease severity, from mild, with only local inflammatory changes of the mammary gland, to severe, with significant systemic derangement. The present study was designed to examine the relationship between serotype and virulence genes of E. coli mastitis isolates, different levels of systemic disease severity, and farm from which the E. coli strain was obtained. One hundred twenty-three E. coli milk isolates were obtained from cows with clinical mastitis of varying systemic disease severity from 6 different farms. No predominant serotype was identified by farm or by systemic disease severity; however, the most frequent serotype, O158:NM (n=3), was isolated from cows in the moderate severity group. Virulence genes evaluated were identified infrequently and were not associated with systemic disease severity. Evaluation of genetic similarity showed no clustering assigned by farm or mastitis severity based on systemic disease signs. We concluded that a high degree of genotypic variability is characteristic of E. coli strains causing clinical mastitis within and between different farms and systemic severity groups, and that specific cow factors probably play a more important role in determining systemic disease severity
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Effect of Prolactin on In Vitro Expression of the Bovine Mammary Immunoglobulin G1 Receptor
Explants of mammary tissue from cows in late pregnancy were incubated for 72h in serum-free, hormonally defined media to investigate the regulation of the bovine mammary IgG1 receptor. Treatments included incubation in basal medium alone, basal medium plus estradiol-17β, basal medium plus prolactin, or basal medium plus estradiol-17β and prolactin. ι-Lactalbumin production was measured by radioimmunoassay in culture supernatants collected at 24, 48, and 72h. Explants were examined immunohistochemically for expression of the IgG1 receptor at 24, 48, and 72h. ι-Lactalbumin concentrations increased, and IgG1 receptor expression decreased, by 72h with explants cultured in the medium containing prolactin. Results suggest that, in addition to its positive lactogenic effect, prolactin decreases expression of the bovine mammary IgG1 receptor
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Expression of Immunoglobulin G1 Receptors by Bovine Mammary Epithelial Cells and Mammary Leukocytes
The objective of this study was to identify and evaluate expression of IgG1 receptors by different cell types in mammary tissue sections and digest-dispersed cells from the bovine mammary gland. An immunohistochemical system utilizing avidin-biotin-peroxidase complex demonstrated epithelial expression of IgG1 receptors in mammary tissue sections from cows producing colostrum but not from cows in lactation. Fluorescence flow cytometry demonstrated that cells dispersed in digests from both tissues producing colostrum and lactating tissues selectively bound IgG1. Fluorescence flow cytometry, using monoclonal antibodies to cell surface molecules, cytokeratin, and IgG1 revealed that leukocytes constituted the largest percentage of cells and were the predominant cell type binding IgG1 in mammary tissue digests. Although IgG1 binding to epithelial cells predominated in the gland during colostrum production in situ, digestion and filtration to produce single cell suspensions resulted in the loss of large numbers of epithelial cells. Studies of Ig binding of cells produced by enzymatic digestion must account for the types of cells surviving the digestion process