Thomas McFadden

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The endocrine system coordinates development of the mammary gland with reproductive development and the demand of the offspring for milk. Three categories of hormones are involved. The levels of the reproductive hormones, estrogen, progesterone, placental lactogen, prolactin, and oxytocin, change during reproductive development or function and act directly(More)
The growth and morphogenesis of mammaryparenchyma varies substantially between species and isregulated by an array of systemic and local factors.Central to this regulation is the mammary fat pad, amatrix of adipose and connective tissue capable ofmediating hormone action and synthesizing an array ofgrowth regulatory molecules. In this article wehighlight(More)
The mammary gland undergoes dramatic functional and metabolic changes during the transition from late pregnancy to lactation. To better understand the molecular events underlying these changes, we analyzed expression profiles of approximately 23,000 gene transcripts in bovine mammary tissue about day 5 before parturition and day 10 after parturition. At the(More)
Fifteen beef cows and 13 dairy cows were used to investigate the physiological basis of breed differences in IgG1 concentration in colostrum. Concentrations of progesterone and alpha-LA in sera and IgG1 in sera and secretion were quantified in samples collected prepartum. Serum progesterone concentration decreased significantly between 30 and 10 d(More)
Eight primiparous cows in midlactation were used to determine a method for the mammary biopsy of standing cows in full lactation. Cows were mildly sedated; therefore, preoperative feed withdrawal was not necessary. A core of secretory tissue (0.75 to 1 g) was extracted using a rotating stainless steel cannula with a retractable blade at the cutting edge.(More)
Cows exposed to short day photoperiod during the dry period produce significantly more milk in their subsequent lactation than cows exposed to long days. The mechanism(s) underlying this effect are unknown. Because concentrations of prolactin (PRL) in circulation are consistently affected by changes in photoperiod, we hypothesized that alterations in the(More)
GLUT8 is a newly identified member of the facilitative glucose transporter family, which characteristically exhibits high-affinity glucose transport activity. The expression of GLUT8 has been shown to depend on gonadotropin secretion in human testes and to be regulated by insulin in the blastocyst. To characterize GLUT8 and investigate its role in normal(More)
The objectives of this study were to determine the local effects of transforming growth factor-beta1 (TGF-beta1) on mammary epithelial and stromal cell proliferation and expression of the TGF-beta1 responsive genes c-myc and fibronectin. A single slow-release plastic pellet containing 5 microg of TGF-beta1 and 20 mg of BSA was implanted in the parenchyma of(More)
Frequent milking of dairy cows during early lactation results in a persistent increase in milk yield; however, the mechanism underlying this effect is unknown. We hypothesized that increased exposure of the mammary gland to prolactin (PRL) mediates the milk yield response. Fifteen multiparous Holstein cows were assigned to 3 treatments for the first 3 wk of(More)
Suppressors of cytokine signaling (SOCS) are induced by prolactin and act through negative feedback to inhibit cytokine signaling. We hypothesized that lower prolactin concentrations in cows exposed to short-day photoperiod (SD; 8 h light:16 h dark) lead to decreased expression of SOCS, which mediate the effects of SD on mammary proliferation during the dry(More)