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23 results on '"Gorden, P.J."'

10. The effects of zinc amino acid complex on biomarkers of gut integrity, inflammation, and metabolism in heat-stressed ruminants

Author

Opgenorth, J., primary, Abuajamieh, M., additional, Horst, E.A., additional, Kvidera, S.K., additional, Johnson, J.S., additional, Mayorga, E.J., additional, Sanz-Fernandez, M.V., additional, Al-Qaisi, M.A., additional, DeFrain, J.M., additional, Kleinschmit, D.H., additional, Gorden, P.J., additional, and Baumgard, L.H., additional

Published
2021
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13. The role of thecal androgen production in the regulation of estradiol biosynthesis by dominant bovine follicles during the first follicular wave

Author

Valdez, K.E., Cuneo, S.P., Gorden, P.J., and Turzillo, A.M.

Subjects
Cattle -- Physiological aspects, Cattle -- Research, Estrogen -- Research, Birds -- Reproduction, Birds -- Research, Cattle -- Reproduction, Endangered species -- Reproduction, Endangered species -- Research, Fishes -- Reproduction, Fishes -- Research, Livestock -- Reproduction, Livestock -- Research, Lizards -- Reproduction, Lizards -- Research, Mammals -- Reproduction, Mammals -- Research, Snails -- Reproduction, Snails -- Research, Zoology and wildlife conservation
Abstract

The first wave of follicular development following ovulation in cattle is characterized by selection and growth of a large, estrogenic dominant follicle. After the follicle becomes morphologically dominant, concentrations of estradiol in its follicular fluid decrease abruptly. The purpose of this study was to determine whether this decrease in estrogen production is caused by an insufficient supply of androgen from theca interna or decreased aromatization of androgen precursor by granulosa cells. Dominant follicles were collected from Holstein heifers on d 4, 6, or 8 of the first follicular wave (n = 5/d). Amounts of 17[alpha]-hydroxylase mRNA in theca interna were sevenfold higher (P < 0.01) on d 4 than on d 8. After 3 h in culture, secretion of androstenedione by theca interna collected on d 4 (236 [+ or -] 44 pg/[micro]g of protein) tended to be lower (P = 0.055) compared with d 6 (517 [+ or -] 162 Pg/[mu]g protein) and was lower (P < 0.05) compared with d 8 (387 [+ or -] 51 pg/[micro]g of protein). In granulosa cells, amounts of aromatase mRNA decreased (P < 0.05) on d 8 compared with d 6 but not d 4. In vitro secretion of estradiol was higher in granulosa cells collected on d 4 (3.5 [+ or -] 0.8 ng/[10.sup.5] cells x 3 h]) compared with d 6 (1.8 [+ or -] 0.6 ng/[[10.sup.5] cells x 3 h]; P < 0.05) and tended to be higher on d 4 than on d 8 (2.2 [+ or -] 0.2 ng/[[10.sup.5] cells x 3 h]; P = 0.058). We conclude that the decrease in estradiol production observed during atresia of the dominant follicle is not due to lack of androgen substrate for aromatization or downregulated expression of the aromatase gene, but may be the direct result of decreased activity of the aromatase enzyme within granulosa cells. Key Words: Bovine, Granulosa Cells, Ovary, Steroidogenesis, Theca interna

Published
2005

19. Comparative plasma and interstitial fluid pharmacokinetics of flunixin meglumine and ceftiofur hydrochloride following individual and co-administration in dairy cows

Author

Gorden, P.J., Kleinhenz, M.D., Wulf, L.W., Rajewski, S.J., Wang, C, Gehring, R., Coetzee, J.F., Gorden, P.J., Kleinhenz, M.D., Wulf, L.W., Rajewski, S.J., Wang, C, Gehring, R., and Coetzee, J.F.

Abstract

Item does not contain fulltext, Ceftiofur (CEF) and flunixin meglumine (FLU) are two drugs approved for use in beef and dairy cattle that are frequently used in combination for many diseases. These two drugs are the most commonly used drugs in dairy cattle in their respective drug classes. Two research groups have recently published manuscripts demonstrating altered pharmacokinetics of FLU and CEF in cows affected with naturally occurring mastitis. The objective of this study was to determine whether pharmacokinetics of flunixin meglumine administered intravenously or intramuscularly administered ceftiofur hydrochloride would be altered when co-administered versus individual administration to healthy dairy cattle. Ten cows were utilized in a three-period, three-treatment crossover design, with all cows receiving each treatment one time with a 10-day washout period between treatments. Following treatment, plasma and interstitial fluid samples were collected and stored for later analysis. Additionally, plasma ultrafiltrate was collected using microcentrifugation to determine plasma protein binding of each drug. Drug concentrations in plasma, plasma ultrafiltrate, and interstitial fluid were determined using high-pressure liquid chromatography coupled with mass spectrometry. The results of this trial indicate that drug interactions between FLU and CEF do not occur when the two drugs are administered simultaneously in healthy cattle. Further work is needed to determine whether this relationship is maintained in the presence of severe disease.

Published
2018

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