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Papers by mark mirando

Research paper thumbnail of The Death of the Letter? Epistolary Intent, Letterness and the Many Ends of Letter-Writing

Cultural Sociology

Is the letter now 'dead', in terminal decline because of the impact of new digital technologies? ... more Is the letter now 'dead', in terminal decline because of the impact of new digital technologies? Such arguments raise important points. However, they fail to distinguish between prevailing genre conventions for letter-writing in different time periods and the underlying 'epistolary intent' and 'letterness' involved, and so overstate the newness of the changes discussed. Examples of overtime departures from 'the letter' but which display clear epistolary intent and deploy inventive forms of letterness are discussed, including the letters of Olive Schreiner, St Paul's epistles, communications between Roman legionaries, Second World War love letters, an exchange involving mathematicians, and student emails.

Research paper thumbnail of Endocrine secretion of prostaglandin F2α in cyclic gilts is decreased by intrauterine administration of exogenous oxytocin

Animal Reproduction Science, 2004

When administered systemically, oxytocin (OT) stimulates secretion of uterine prostaglandin F 2␣ ... more When administered systemically, oxytocin (OT) stimulates secretion of uterine prostaglandin F 2␣ (PGF 2␣) in swine, but the role of endometrially-derived OT in control of PGF 2␣ release is not clear. This study determined the effect of exogenous OT, administered into the uterine lumen of intact cyclic gilts, on PGF 2␣ secretion during late diestrus. Intrauterine infusion of 40 USP units OT (in 30 ml 0.9% saline) was performed for 30 min (1 ml/min) into each uterine horn between 7:00 and 9:00 h on days 10, 12, 14 and 16 after estrus. Beginning 20 min before infusion, samples of jugular venous blood were drawn at 5-10-min intervals for 140 min for quantification of 13,14-dihydro-15-keto-PGF 2␣ (PGFM), the major stable metabolite of PGF 2␣. Progesterone was analyzed in samples collected 0, 60 and 120 min after initiation of OT infusion. Treatment with OT did not alter plasma concentrations of PGFM on days 10 or 12 but decreased (P < 0.001) PGFM concentrations for 40 min after onset of infusion on day 16. Concentrations of PGFM also were reduced in the pre-treatment samples on day 14 (P = 0.05) and day 16 (P < 0.001) in OT-infused gilts. Plasma progesterone declined (P < 0.01) between days 10 and 16 in control-infused gilts but did not decline until after day 14 (P < 0.001) in gilts infused with OT. These results indicate that when OT is administered into the uterine lumen of pigs during late diestrus, it has an anti-luteolytic

Research paper thumbnail of Oxytocin-stimulated phosphoinositide hydrolysis and prostaglandin F2α secretion by luminal epithelial, glandular epithelial and stromal cells from pig endometrium. II. Responses of cyclic, pregnant and pseudopregnant pigs on Days 12 and 1

Reprod Fert Develop, 2000

In pigs, the exact mechanism for the shift in endometrial PGF 2α secretion from an endocrine to a... more In pigs, the exact mechanism for the shift in endometrial PGF 2α secretion from an endocrine to an exocrine mode during pregnancy recognition is not known. The objective of this study was to examine whether this shift involved a change in the responsiveness of luminal epithelial, glandular epithelial and stromal cells to 0 or 100 nM oxytocin. Luminal epithelial cells, glandular epithelial cells and stromal cells were isolated from cyclic, pregnant or oestrogen-induced pseudopregnant gilts on Day 12 (Experiment 1) or Day 16 (Experiment 2) post oestrus (oestrus = Day 0). For cells obtained on Day 12, oxytocin stimulated PGF2α secretion by stromal cells (P<0.01) similarly for each reproductive status, whereas oxytocin stimulated PGF 2α secretion from luminal and glandular epithelial cells (P<0.05) from pregnant and pseudopregnant gilts but not from cyclic gilts. For both concentrations of oxytocin, mean PGF2α secretion was less (P<0.05) from stromal cells of pregnant than cyclic gilts. For cells obtained on Day 16, oxytocin stimulated PGF 2α release from stromal cells of cyclic gilts but not from stromal cells of pregnant gilts. Mean PGF 2α secretion also was less (P<0.05) from stromal cells of pregnant gilts than cyclic gilts. Oxytocin tended to stimulate PGF 2α release (P<0.07) from glandular epithelial cells of cyclic but not pregnant or pseudopregnant gilts. Luminal epithelial cells from all reproductive statuses were similarly unresponsive to oxytocin. In conclusion, the increased PGF2α secretory response to oxytocin of luminal and glandular epithelial cells from pregnant gilts on Day 12, combined with the decreased response of stromal cells from pregnant gilts on Days 12 and 16, may contribute, in part, to the shift in endometrial PGF2α secretion from an endocrine to an exocrine direction during early pregnancy in pigs.

Research paper thumbnail of Induction of Parturition: A Comparison of the Effects of Lutalyse and Estrumate on Sows

The aim of this study was to determine the efficiency of prostaglandin analogue treatments on the... more The aim of this study was to determine the efficiency of prostaglandin analogue treatments on the induction of parturition during late pregnancy in sows, based on fewer and less intense side effects. Twenty-four sows were randomly treated on day 114 of gestation with: (1) 175 micrograms Estrumate; (2) 10 mg Lutalyse; (3) 2 ml. saline (control) or on day 115 with 2 ml saline (control). Sows injected with Lutalyse showed a significant increase in position changes/minute as compared to the C114 treatments. L114 treated sows displayed a significant increase in frequency of bar biting compared to the E114, C115, and C114 treatments, and a significant increase in frequency of defecation compared to the C115 and C114 treatment. These results demonstrate that sows treated with Estrumate are likely to have fewer, less intense side effects than sows treated with Lutalyse.

Research paper thumbnail of Relationships among endometrial oxytocin receptors, oxytocin-stimulated phosphoinositide hydrolysis and prostaglandin F2 alpha secretion in vitro, and plasma concentrations of ovarian steroids before and during corpus luteum regression in cyclic heifers

Biology of Reproduction

Oxytocin stimulates secretion of endometrial prostaglandin (PG) F and induces endometrial phospho... more Oxytocin stimulates secretion of endometrial prostaglandin (PG) F and induces endometrial phosphoinositide hydrolysis around the time of regression of the corpus luteum (CL) in cows. This study investigated the relationship between endometrial oxytocin receptors, oxytocin-stimulated phosphoinositide hydrolysis and PGF,, secretion in vitro, and plasma concentrations of ovarian steroids before and during CL regression in cyclic heifers (i.e., Days 13-19 post-estrus). Reproductive tracts were collected from 16 cyclic heifers on Days 13 (n = 5), 16 (n = 5), and 19 (n = 6). Decreases in mean CL weight (4.7, 4.6, and 3.0 + 0.6 g for Days 13, 16, and 19, respectively; p < 0.05) and plasma progesterone (12.2, 10.5, and 4.3 1.5 ng/ml for Days 13, 16, and 19, respectively; p < 0.01) were detected between Days 16 and 19, indicating that CL regression had been initiated in the group of Day 19 heifers. Mean concentration of plasma estradiol (3.4, 3.8, and 5.6 + 1.7 pg/ml for Days 13, 16, and 19, respectively) did not differ significantly (p > 0.5) among days of the estrous cycle. Concentration of endometrial oxytocin receptors increased (p < 0.06) during the estrous cycle (36, 49, and 789 234 fmol/mg protein on Days 13, 16, and 19, respectively), but the greatest increase (p < 0.05) occurred between Days 16 and 19. Similarly, incorporation of [ 3 H]inositol into endometrial inositol phosphates induced in vitro with 100 nM oxytocin also increased (p < 0.01) during the estrous cycle (5121 vs. 5819, 4529 vs. 7239, and 5888 vs. 68 096 18 564 dpm/g tissue for control vs. oxytocin-treated endometrium on Days 13, 16, and 19, respectively) with the greatest increase (p < 0.01) in responsiveness to oxytocin occurring between Days 16 and 19. Endometrial PGF, 0 secretion in response to 100 nM oxytocin increased linearly (p < 0.05) during the estrous cycle (905 vs. 1151, 783 vs. 1947, and 639 vs. 2485 510 pg/g tissue/min for control vs. oxytocin-treated endometrium on Days 13, 16, and 19, respectively). On Day 19, CL regression was not yet apparent in 3 of 6 heifers, whereas luteolysis was clearly occurring in the remaining 3 heifers (2.1 vs. 4.0 0.4 g, p < 0.05, for CL weight and 1.1 vs. 7.6 + 0.6 ng/ml, p < 0.01, for plasma progesterone in heifers with regressing and nonregressing CL, respectively). Mean concentrations of plasma estradiol did not differ significantly (p > 0.25) between heifers with a regressing CL (8.3 3.1 pg/ml) and heifers with a functional CL (2.8 + 3.1 pg/ml), although 2 of 3 heifers with a regressing CL and 0 of 3 heifers with a functional CL had elevated concentrations of estradiol. Concentration of endometrial oxytocin receptors was greater (p < 0.05) in heifers undergoing luteolysis than in heifers with CL maintained on Day 19 (1490 vs. 88 + 265 fmol/mg protein, respectively). Incorporation of [ 3 H]inositol into endometrial inositol phosphates in response to oxytocin also increased (p < 0.06) in those heifers undergoing luteolysis compared with those still having a functional CL (6170 vs. 120 353 and 5606 vs. 15 837 18 564 dpm/g tissue for control vs. oxytocin-treated endometrium from regressing and maintained heifers, respectively). In contrast, endometrial PGF,, secretion in response to oxytocin did not differ significantly between the two groups. These results indicate that 1) endometrial concentration of oxytocin receptors and oxytocin-induced phosphoinositide hydrolysis increased similarly during luteolysis with the greatest increases occurring around the time of onset of luteolysis; 2) endometrial PGF,. secretary response to oxytocin coincides with the early gradual increases in endometrial oxytocin receptor concentration and oxytocin-induced phosphoinositide hydrolysis between Days 13 and 16, but precedes the large increase in activity of the oxytocin receptor-phospholipase C system occurring 16-19 days post-estrus; and 3) oxytocin receptors and oxytocin-induced phosphoinositide hydrolysis are markedly increased during CL regression in cows. We suggest that a modest increase in the oxytocin receptor-phospholipase C system between Days 13 and 16 may be responsible for initiating endometrial sensitivity to oxytocin required for onset of luteolytic PGF,, secretion, whereas the large increase in the oxytocin receptorphospholipase C system occurs late in the estrous cycle as a consequence of luteolysis.

Research paper thumbnail of Ovine interferon-tau regulates expression of endometrial receptors for estrogen and oxytocin but not progesterone

Biology of Reproduction

Ovine interferon-T (olFN-T) may stabilize endometrial progesterone receptor (PR) and/or inhibit e... more Ovine interferon-T (olFN-T) may stabilize endometrial progesterone receptor (PR) and/or inhibit estrogen receptor (ER) gene expression during pregnancy recognition to suppress endometrial oxytocin receptor (OTR) formation and production of luteolytic prostaglandin (PG) F2, pulses. This study determined whether or not olFN-T stabilized PR expression in the endometrium during PR down-regulation by continuous exposure to progesterone. Twenty cyclic ewes were bilaterally ovariectomized and fitted with uterine catheters on Day 2 of the estrous cycle (Day 0 = estrus). Ewes were then assigned randomly to be treated, in a 2 x 2 factorial arrangement, with recombinant olFN-T (rolFN-T; 2 x 107 antiviral units per ewe per day) or control proteins (6 mg/day) by intrauterine injection from Days 10 to 14, and with daily i.m. injections of 20 mg progesterone from Days 2 to 14 (P) or progesterone from Days 2 to 14 plus 50 g estradiol-17p from Days 12 to 14 (P+E). All ewes were hysterectomized on Day 15. Endometrial PR mRNA (p < 0.01) and protein (p < 0.03) were higher in ewes receiving P+ E than in those receiving P alone. However, the increase in PR mRNA and protein was not as great in the endometrium of rolFN-T-treated ewes as compared to controls (p < 0.08, treatment x steroid). In ewes receiving P alone, PR mRNA and immunoreactive PR were localized to stroma and deep glandular epithelium and were not present in endometrial luminal and shallow glandular epithelium. Values for endometrial ER mRNA (p < 0.02) and ER protein (p < 0.01) were greater in controls than in rolFN-T-treated ewes regardless of steroid treatment. Among controls, ER mRNA and immunoreactive ER protein were present in the luminal and glandular epithelium and were increased in the epithelium and stroma in ewes receiving estrogen. In contrast, endometrial ER mRNA and immunoreactive ER protein were very low or absent in the endometrium of rolFN-T-treated ewes and were not increased by estrogen. Among controls, endometrial OTR density was greater (p < 0.09) in ewes treated with P+E than in those treated with P alone. In rolFN-treated ewes, endometrial OTR density was lower (p < 0.01) than in the controls. Results indicate that rolFN-T did not stabilize or prevent autolotous down-regulation of PR mRNA or protein expression in the endometrium. However, rolFN-T did suppress endometrial ER expression and OTR formation in ewes regardless of steroid treatment. The results support the hypothesis that the antiluteolytic effects of oIFNare to suppress endometrial ER gene expression in the endometrial epithelium, thereby inhibiting formation of OTR and production of luteolytic PGF,, pulses.

Research paper thumbnail of A proposed role for oxytocin in regulation of endometrial prostaglandin F2α secretion during luteolysis in swine

Advances in Experimental Medicine and Biology

Pulsatile secretion of endometrial prostaglandin (PG)F2 alpha is stimulated by oxytocin (OT) duri... more Pulsatile secretion of endometrial prostaglandin (PG)F2 alpha is stimulated by oxytocin (OT) during late diestrus in domestic ruminants (i.e., cattle, sheep and goats) and results in corpus luteum (CL) regression leading to the onset of a new estrous cycle. Pulsatile PGF2 alpha release is also responsible for CL regression in swine, but the stimulus for its secretion from the uterine endometrium is not known. We propose that OT binds to specific OT receptors (OTR) on the endometrium to stimulate phosphoinositide (PI) hydrolysis, thereby activating the inositol trisphosphate (IP3)-diacylglycerol (DAG) second-messenger system to promote pulsatile PGF2 alpha secretion. Exogenous OT administered to cyclic gilts during late diestrus (days 10-16) decreased interestrous interval in three of four experiments. However, OT did not promote CL regression in hysterectomized gilts indicating that the effect of OT was uterine-dependent. Circulating concentrations of 13,14-dihydro-15-keto PGF2 alpha (the major stable metabolite of PGF2 alpha) were increased (p &lt; 0.01) 10 min after i.v. injection of OT on days 14 and 16 in cyclic gilts and on days 10-16 in pregnant gilts, but the magnitude of the response to OT on all days in pregnant gilts was markedly reduced compared to the response in cyclic gilts on days 14 and 16. Mean density and Kd of OTR detected on endometrium of cyclic pigs 15 days post-estrus were 29.2 +/- 5.5 fmol/mg protein and 1.59 +/- 0.23 nM, respectively. Density of OTR was correlated with OT-stimulated PI hydrolysis (r = 0.83, p &lt; 0.05) and PGF2 alpha secretion (r = 0.87, p &lt; 0.10). Endometrial IP3 was increased within 30 seconds after OT treatment and preceded the increase in PGF2 alpha release stimulated by OT. Endometrial PI hydrolysis and PGF2 alpha secretion were similarly increased by AIF4-(phospholipase C activator), but not by cholera toxin (adenylyl cyclase activator). Although OT binding to OTR could be displaced by lysine-vasopressin and lysine-vasopressin stimulated PI hydrolysis, lysine-vasopressin did not stimulate PGF2 alpha release. Distinct receptors for OT and lysine-vasopressin on pig endometrium were confirmed by treatment with 100 nM OT + 100 nM lysine-vasopressin which stimulated PI hydrolysis more than 100-200 nM OT or lysine-vasopressin alone. These results support the hypothesis that OT stimulates phospholipase C to hydrolyze PI, yielding IP3 and DAG second-messengers which promote endometrial PGF2 alpha release during CL regression in pigs.

Research paper thumbnail of Physiological mechanisms of pregnancy recognition in ruminants

Journal of reproduction and fertility. Supplement, 1991

Maternal recognition of pregnancy in sheep, cattle and goats involves physiological mechanisms th... more Maternal recognition of pregnancy in sheep, cattle and goats involves physiological mechanisms that result in protection of corpora lutea from luteolysis by modification or inhibition of uterine production of luteolytic pulses of prostaglandin (PG) F-2 alpha. Ovine, bovine and caprine luteal cells release oxytocin in a pulsatile manner during late dioestrus. Oxytocin then binds to its endometrial receptors and initiates luteolytic pulses of PGF-2 alpha. Ovine, bovine and caprine trophoblast protein-1 (oTP-1, bTP-1 and cTP-1) are secreted by the trophectoderm of conceptuses between Days 10 and 21-24 of pregnancy. These antiluteolytic proteins (oTP-1 and bTP-1) are primarily responsible for inhibiting uterine production of luteolytic amounts of PGF-2 alpha. During early pregnancy, the numbers of endometrial receptors for oxytocin are significantly lower in ewes and cows, and stimulatory effects of exogenous oxytocin on uterine production of PGF-2 alpha are correspondingly reduced or a...

Research paper thumbnail of Interestrous interval of cyclic gilts is decreased by systemic but not intrauterine administration of exogenous oxytocin

Journal of animal science, 2000

Oxytocin (OT) stimulates pulsatile secretion of uterine prostaglandinF2alpha in ruminants, but th... more Oxytocin (OT) stimulates pulsatile secretion of uterine prostaglandinF2alpha in ruminants, but the role of OT in the estrous cycle regulation of pigs is not clear. These studies were performed to determine the effect of exogenous OT on interestrous interval of intact cyclic gilts. Intrauterine infusion of 80 USP units three times daily on d 10 to 16 after estrus did not decrease interestrous interval (24.5+/-1.3 d) compared with control gilts (22.5+/-1.3 d). In contrast, i.m. injections of 20 USP units of OT twice daily or 80 USP units of OT three times daily on d 10 to 16 after estrus decreased (P < 0.05) interestrous interval (20.0+/-0.3 or 19.5+/-0.4 d, respectively) compared with control gilts (20.5+/-0.3 d). When gilts received a single i.m. injection of 0 or 1 mg of estradiol valerate on d 11 and twice daily i.m. injections of 0 or 20 USP units OT on d 10 to 16 after estrus, an interaction (P = 0.05) between OT and estradiol valerate was detected. In the absence of exogenou...

Research paper thumbnail of Directional secretion of prostaglandin F(2alpha) by polarized luminal epithelial cells from pig endometrium

Prostaglandins & other lipid mediators, 2000

In swine, endometrial prostaglandin F(2alpha) (PGF(2alpha)) is the luteolysin. The capacity of lu... more In swine, endometrial prostaglandin F(2alpha) (PGF(2alpha)) is the luteolysin. The capacity of luminal epithelial cells isolated from the endometrium of day 16 cyclic pigs, to secrete PGF(2alpha)500 Omega/cm(2)), they were treated on the apical, basal or both surfaces with 0 or 100 nM oxytocin (OT) in Experiment 1 or phorbol 12-myristate 13-acetate (PMA) in Experiment 2. In the absence of OT or PMA, PGF(2alpha) secretion occurred primarily from the basal surface and was approximately 12-fold greater (P < 0.001) than from the apical surface. Treatment with OT did not stimulate PGF(2alpha) secretion from either surface regardless of which surface was treated. In contrast, PMA increased PGF(2alpha) secretion from both surfaces. Treatment of the apical surface or both surfaces with PMA increased (P < 0.001) PGF(2alpha) secretion similarly from both surfaces. Treatment of only the basal surface with PMA increased (P < 0.01) PGF(2alpha) secretion from both surfaces, but tended (P...

Research paper thumbnail of Endometrial inositol phosphate turnover in pigs is reduced during pregnancy and estradiol-induced pseudopregnancy

Journal of animal science, 1990

Three experiments were conducted to examine inositol phosphate (IP) turnover in response to treat... more Three experiments were conducted to examine inositol phosphate (IP) turnover in response to treatments applied in vitro to endometrium from cyclic (CYC), pregnant (PREG) and estradiol-induced pseudopregnant (PSP) gilts. In Exp. 1, treatments (in 25 microliters .1 M NaHCO3) were 1) control (NaHCO3), 2) 125 ng oxytocin, 3) .25 micrograms prolactin, 4) 2.5 micrograms prolactin and 5) 5 micrograms pig conceptus secretory proteins (pCSP). Basal IP turnover on d 14 (estrus = d 0) for CYC was 3.9 to 5.0-fold greater than for PREG gilts and .6 to 1.1-fold greater than for PSP gilts (P less than .05). Oxytocin increased IP turnover 23 to 42% in CYC gilts (P less than .05), but not in PREG or PSP gilts. The treatment x reproductive status interaction (P less than .05) indicated that pCSP increased IP turnover 74 to 140% in PREG gilts but decreased it 18 to 22% in CYC and 17 to 50% in PSP gilts. In Exp. 2, treatments were applied in a 2 x 2 x 2 arrangement: 1) 0 or 125 ng oxytocin; 2) 0 or 2.5...

Research paper thumbnail of Movement characteristics of boar sperm obtained from the oviduct or hyperactivated in vitro

Journal of andrology

The objectives of this study were to describe hyperactivated motility in boar sperm and to determ... more The objectives of this study were to describe hyperactivated motility in boar sperm and to determine the incidence of hyperactivation among boar sperm flushed from the oviduct. Oviducts were surgically removed from 13 gilts 32 hours after mating them to fertile boars. The majority of the sperm flushed from the oviducts was immotile, weakly motile, or stuck to mucus or cellular debris. The mucus could not be penetrated by the sperm. The remaining 3% to 19% of the flushed sperm was free-swimming. Only five hyperactivated sperm were recovered, all from the ampulla of the oviduct. The remainder of the free-swimming sperm travelled in linear trajectories and possessed significantly higher flagellar curvature ratios (the flagella were less bent) than boar sperm measured in diluted semen. Hyperactivated motility was induced in washed ejaculated boar sperm, using a 1-minute pulse of 4 mumol/L calcium ionophore A23187. The ionophore-treated sperm had significantly lower straight-line velocit...

Research paper thumbnail of Mechanisms Regulating Prostaglandin F2α Secretion from the Bovine Endometrium

Journal of Dairy Science, 1998

The mechanism that regulates luteolytic PGF2a secretion as stimulated by oxytocin is thought to i... more The mechanism that regulates luteolytic PGF2a secretion as stimulated by oxytocin is thought to in- volve induction of the inositol (1,4,5)-trisphosphate- diacylglycerol second messenger system, which mobi- lizes intracellular calcium and activates protein kinase C. In Experiment 1, endometrial explants taken from heifers on d 18.5 to 19.5 postestrus had increased PGF2a secretion after treatment with 1 mM calcium ionophore

Research paper thumbnail of Morphometric analysis of the uterine endometrium of swine on days 12 and 16 postestrus

The Anatomical Record, 2002

The uterine endometrium of swine is comprised of luminal epithelial, glandular epithelial, and st... more The uterine endometrium of swine is comprised of luminal epithelial, glandular epithelial, and stromal cells that secrete the luteolysin, prostaglandin F 2␣ (PGF 2␣), during late diestrus. However, which of these cells contribute the most to luteolytic PGF 2␣ secretion is unknown because the cellular composition of the endometrium has not been quantified. Therefore, this study quantified the cellular composition of the endometrium on days 12 and 16 postestrus by histologic and morphometric analyses. On day 12, the endometrium consisted predominantly of stromal cells (47% of total cell quantity) and glandular epithelial cells (37%), whereas luminal epithelial cells represented only 16% of the total of the three cell types. The number of glandular epithelial cells tended to increase (P Ͻ 0.10) between days 12 and 16, such that they comprised 45% of the endometrium by day 16, while the number of stromal and luminal cells did not change and accounted for 45% and 10% of the cells, respectively. Luminal epithelial cells had a 58% greater cross-sectional area (P Ͻ 0.001) than glandular epithelial cells, whereas glandular epithelial cells had a 22% greater area (P Ͻ 0.001) than stromal cells. Glandular epithelial cells decreased (P Ͻ 0.001) in cross-sectional area between days 12 and 16, whereas the area of luminal epithelial and stromal cells remained unchanged. These results indicate that the porcine endometrium is comprised predominantly of stromal and glandular epithelial cells that are likely to contribute substantially to endometrial PGF 2␣ secretion during luteolysis. The contribution of glandular epithelium to luteolytic PGF 2␣ secretion probably increases during diestrus as the number of these cells increases.

Research paper thumbnail of USDA-CSREES National Research Initiative: Support for Agricultural Research – The competitive grants program in the United States

Agricultural Research Management, 2007

Research paper thumbnail of Oxytocin stimulates prostaglandin F2α secretion from porcine endometrial cells through activation of calcium-dependent protein kinase C☆

Prostaglandins & Other Lipid Mediators, 2001

Research paper thumbnail of Intracellular free calcium in response to oxytocin in pig endometrial cells

Molecular and Cellular Endocrinology, 1999

Intracellular free calcium concentration ([Ca 2 + ] i) in response to oxytocin (OT) was studied i... more Intracellular free calcium concentration ([Ca 2 + ] i) in response to oxytocin (OT) was studied in stromal, glandular epithelial and luminal epithelial cells obtained from the endometrium of gilts 16 days post-estrus. The amplitude of increased [Ca 2 + ] i in response to 100 nM OT was greatest in stromal cells, intermediate in glandular epithelial cells and not evident in luminal epithelial cells. During continuous OT administration, stromal cells responded initially with a synchronous spike of [Ca 2 + ] i that did not require extracellular Ca 2 + and then displayed spontaneous asynchronous [Ca 2 + ] i spikes that required extracellular Ca 2 +. Each cell possessed its own characteristic response. Increasing concentrations of OT induced an increasing percentage of stromal cells responding, with some cells having nearly equal [Ca 2 + ] i responses at all concentrations and others having graded [Ca 2 + ] i responses as the concentration of OT increased. These results are consistent with the proposed mechanism of OT action in pig endometrium involving activation of phosphoinositide-Ca 2 + signaling pathway.

Research paper thumbnail of REPRODUCTION SYMPOSIUM: External influences on reproductive neuroendocrinology

Journal of Animal Science, 2014

Research paper thumbnail of Effect of recombinant alpha interferons on fertility and interestrous interval in sheep

Theriogenology, 1992

In Experiment 1, 12 unmated cyclic ewes received twice-daily intrauterine injections on Days 12 t... more In Experiment 1, 12 unmated cyclic ewes received twice-daily intrauterine injections on Days 12 to 14 of one of the following treatments: 1) ovine conceptus secretory proteins (oCSP) containing 25 microg of ovine trophoblast protein-1 (oTP-1) as determined by RIA; 2) 25 or 50 microg recombinant human interferon alpha1 (rhlFN); or 3) 1500 microg of serum proteins (oSP) from a Day-16 pregnant ewe (estrus = Day 0) per uterine horn. Ewes receiving oCSP had longer interestrous intervals (27 +/- 2 days; P&lt;0.05) than ewes receiving oSP (17 +/- 2 days). Ewes receiving either dose of rhlFN had an interestrous interval of 16 +/- 2 days which did not differ (P&gt;0.10) from that of oSP-treated ewes. In Experiment 2, 59 normally cycling ewes, mated on Day 0, received twice-daily intramuscular injections of either 2 mg recombinant bovine interferon alpha1 (rblFN) or placebo on Days 12 to 15 post estrus. On Day 16, pregnancy was confirmed by flushing a morphologically normal conceptus from the uterus. Pregnancy rates for rblFN-treated (80%) and placebo-treated (62%) ewes were not different (P&gt;0.10). Uterine flushings and conceptus-conditioned medium were assayed for oTP-1. Total oTP-1 in conceptus-conditioned culture medium was higher (P&lt;0.02) when conceptuses were from placebo-treated (104 +/- 14 microg/conceptus) than from rblFN-treated (56 +/- 12 microg/conceptus) ewes; while total oTP-1 in uterine flushings was similar (P&gt;0.10) for placebo-treated (132 +/- 15 microg/conceptus) and rblFN-treated (147 +/- 17 microg/conceptus) ewes. The interval from mating to subsequent estrus following conceptus removal was 31 +/- 1 and 28 +/- 1 days for pregnant ewes treated with rblFN and placebo, respectively. Interestrous intervals for nonpregnant ewes were longer (P&lt;0.02) for rblFN-treated (27 +/- 3 days) than for placebo-treated (18 +/- 2 days) ewes.

Research paper thumbnail of The role of essential trace elements in embryonic and fetal development in livestock

The Veterinary Journal, 2003

This review addresses the concept that essential trace minerals play a vital role in many enzymat... more This review addresses the concept that essential trace minerals play a vital role in many enzymatic and metabolic pathways that are critical for conceptus development during pregnancy in livestock species. The conceptus relies entirely on the maternal system for a sufficient supply of trace minerals and other nutrients needed for normal development. If this supply is inadequate, growth and/or health of the conceptus can be affected adversely, and many of these effects carry over into the neonatal period. Information, accumulated in our laboratory and presented herein, indicates that zinc, copper and manganese are among the trace minerals that have the greatest impact on reproduction. For example, levels of zinc, copper and manganese were several fold greater in the conceptus than in other reproductive tissues, indicating that the conceptus preferentially accumulates these minerals, an action that may be important for conceptus development, growth and survival. Moreover, some recent results indicate that increasing the biological availability of zinc, copper and manganese, by attachment to short peptide chains (i.e., proteinated trace minerals) can enhance reproductive performance of swine. Mineral concentrations in conceptuses from female pigs consuming proteinated trace minerals were greater than those from females that consumed only inorganic mineral salts. Elucidating the mechanisms whereby conceptus development and survival are enhanced by essential trace minerals may lead to development of specific feeding programs to increase the number and health of offspring at parturition, thereby allowing for further improvements in production efficiency in animal agriculture.

Research paper thumbnail of The Death of the Letter? Epistolary Intent, Letterness and the Many Ends of Letter-Writing

Cultural Sociology

Is the letter now 'dead', in terminal decline because of the impact of new digital technologies? ... more Is the letter now 'dead', in terminal decline because of the impact of new digital technologies? Such arguments raise important points. However, they fail to distinguish between prevailing genre conventions for letter-writing in different time periods and the underlying 'epistolary intent' and 'letterness' involved, and so overstate the newness of the changes discussed. Examples of overtime departures from 'the letter' but which display clear epistolary intent and deploy inventive forms of letterness are discussed, including the letters of Olive Schreiner, St Paul's epistles, communications between Roman legionaries, Second World War love letters, an exchange involving mathematicians, and student emails.

Research paper thumbnail of Endocrine secretion of prostaglandin F2α in cyclic gilts is decreased by intrauterine administration of exogenous oxytocin

Animal Reproduction Science, 2004

When administered systemically, oxytocin (OT) stimulates secretion of uterine prostaglandin F 2␣ ... more When administered systemically, oxytocin (OT) stimulates secretion of uterine prostaglandin F 2␣ (PGF 2␣) in swine, but the role of endometrially-derived OT in control of PGF 2␣ release is not clear. This study determined the effect of exogenous OT, administered into the uterine lumen of intact cyclic gilts, on PGF 2␣ secretion during late diestrus. Intrauterine infusion of 40 USP units OT (in 30 ml 0.9% saline) was performed for 30 min (1 ml/min) into each uterine horn between 7:00 and 9:00 h on days 10, 12, 14 and 16 after estrus. Beginning 20 min before infusion, samples of jugular venous blood were drawn at 5-10-min intervals for 140 min for quantification of 13,14-dihydro-15-keto-PGF 2␣ (PGFM), the major stable metabolite of PGF 2␣. Progesterone was analyzed in samples collected 0, 60 and 120 min after initiation of OT infusion. Treatment with OT did not alter plasma concentrations of PGFM on days 10 or 12 but decreased (P < 0.001) PGFM concentrations for 40 min after onset of infusion on day 16. Concentrations of PGFM also were reduced in the pre-treatment samples on day 14 (P = 0.05) and day 16 (P < 0.001) in OT-infused gilts. Plasma progesterone declined (P < 0.01) between days 10 and 16 in control-infused gilts but did not decline until after day 14 (P < 0.001) in gilts infused with OT. These results indicate that when OT is administered into the uterine lumen of pigs during late diestrus, it has an anti-luteolytic

Research paper thumbnail of Oxytocin-stimulated phosphoinositide hydrolysis and prostaglandin F2α secretion by luminal epithelial, glandular epithelial and stromal cells from pig endometrium. II. Responses of cyclic, pregnant and pseudopregnant pigs on Days 12 and 1

Reprod Fert Develop, 2000

In pigs, the exact mechanism for the shift in endometrial PGF 2α secretion from an endocrine to a... more In pigs, the exact mechanism for the shift in endometrial PGF 2α secretion from an endocrine to an exocrine mode during pregnancy recognition is not known. The objective of this study was to examine whether this shift involved a change in the responsiveness of luminal epithelial, glandular epithelial and stromal cells to 0 or 100 nM oxytocin. Luminal epithelial cells, glandular epithelial cells and stromal cells were isolated from cyclic, pregnant or oestrogen-induced pseudopregnant gilts on Day 12 (Experiment 1) or Day 16 (Experiment 2) post oestrus (oestrus = Day 0). For cells obtained on Day 12, oxytocin stimulated PGF2α secretion by stromal cells (P<0.01) similarly for each reproductive status, whereas oxytocin stimulated PGF 2α secretion from luminal and glandular epithelial cells (P<0.05) from pregnant and pseudopregnant gilts but not from cyclic gilts. For both concentrations of oxytocin, mean PGF2α secretion was less (P<0.05) from stromal cells of pregnant than cyclic gilts. For cells obtained on Day 16, oxytocin stimulated PGF 2α release from stromal cells of cyclic gilts but not from stromal cells of pregnant gilts. Mean PGF 2α secretion also was less (P<0.05) from stromal cells of pregnant gilts than cyclic gilts. Oxytocin tended to stimulate PGF 2α release (P<0.07) from glandular epithelial cells of cyclic but not pregnant or pseudopregnant gilts. Luminal epithelial cells from all reproductive statuses were similarly unresponsive to oxytocin. In conclusion, the increased PGF2α secretory response to oxytocin of luminal and glandular epithelial cells from pregnant gilts on Day 12, combined with the decreased response of stromal cells from pregnant gilts on Days 12 and 16, may contribute, in part, to the shift in endometrial PGF2α secretion from an endocrine to an exocrine direction during early pregnancy in pigs.

Research paper thumbnail of Induction of Parturition: A Comparison of the Effects of Lutalyse and Estrumate on Sows

The aim of this study was to determine the efficiency of prostaglandin analogue treatments on the... more The aim of this study was to determine the efficiency of prostaglandin analogue treatments on the induction of parturition during late pregnancy in sows, based on fewer and less intense side effects. Twenty-four sows were randomly treated on day 114 of gestation with: (1) 175 micrograms Estrumate; (2) 10 mg Lutalyse; (3) 2 ml. saline (control) or on day 115 with 2 ml saline (control). Sows injected with Lutalyse showed a significant increase in position changes/minute as compared to the C114 treatments. L114 treated sows displayed a significant increase in frequency of bar biting compared to the E114, C115, and C114 treatments, and a significant increase in frequency of defecation compared to the C115 and C114 treatment. These results demonstrate that sows treated with Estrumate are likely to have fewer, less intense side effects than sows treated with Lutalyse.

Research paper thumbnail of Relationships among endometrial oxytocin receptors, oxytocin-stimulated phosphoinositide hydrolysis and prostaglandin F2 alpha secretion in vitro, and plasma concentrations of ovarian steroids before and during corpus luteum regression in cyclic heifers

Biology of Reproduction

Oxytocin stimulates secretion of endometrial prostaglandin (PG) F and induces endometrial phospho... more Oxytocin stimulates secretion of endometrial prostaglandin (PG) F and induces endometrial phosphoinositide hydrolysis around the time of regression of the corpus luteum (CL) in cows. This study investigated the relationship between endometrial oxytocin receptors, oxytocin-stimulated phosphoinositide hydrolysis and PGF,, secretion in vitro, and plasma concentrations of ovarian steroids before and during CL regression in cyclic heifers (i.e., Days 13-19 post-estrus). Reproductive tracts were collected from 16 cyclic heifers on Days 13 (n = 5), 16 (n = 5), and 19 (n = 6). Decreases in mean CL weight (4.7, 4.6, and 3.0 + 0.6 g for Days 13, 16, and 19, respectively; p < 0.05) and plasma progesterone (12.2, 10.5, and 4.3 1.5 ng/ml for Days 13, 16, and 19, respectively; p < 0.01) were detected between Days 16 and 19, indicating that CL regression had been initiated in the group of Day 19 heifers. Mean concentration of plasma estradiol (3.4, 3.8, and 5.6 + 1.7 pg/ml for Days 13, 16, and 19, respectively) did not differ significantly (p > 0.5) among days of the estrous cycle. Concentration of endometrial oxytocin receptors increased (p < 0.06) during the estrous cycle (36, 49, and 789 234 fmol/mg protein on Days 13, 16, and 19, respectively), but the greatest increase (p < 0.05) occurred between Days 16 and 19. Similarly, incorporation of [ 3 H]inositol into endometrial inositol phosphates induced in vitro with 100 nM oxytocin also increased (p < 0.01) during the estrous cycle (5121 vs. 5819, 4529 vs. 7239, and 5888 vs. 68 096 18 564 dpm/g tissue for control vs. oxytocin-treated endometrium on Days 13, 16, and 19, respectively) with the greatest increase (p < 0.01) in responsiveness to oxytocin occurring between Days 16 and 19. Endometrial PGF, 0 secretion in response to 100 nM oxytocin increased linearly (p < 0.05) during the estrous cycle (905 vs. 1151, 783 vs. 1947, and 639 vs. 2485 510 pg/g tissue/min for control vs. oxytocin-treated endometrium on Days 13, 16, and 19, respectively). On Day 19, CL regression was not yet apparent in 3 of 6 heifers, whereas luteolysis was clearly occurring in the remaining 3 heifers (2.1 vs. 4.0 0.4 g, p < 0.05, for CL weight and 1.1 vs. 7.6 + 0.6 ng/ml, p < 0.01, for plasma progesterone in heifers with regressing and nonregressing CL, respectively). Mean concentrations of plasma estradiol did not differ significantly (p > 0.25) between heifers with a regressing CL (8.3 3.1 pg/ml) and heifers with a functional CL (2.8 + 3.1 pg/ml), although 2 of 3 heifers with a regressing CL and 0 of 3 heifers with a functional CL had elevated concentrations of estradiol. Concentration of endometrial oxytocin receptors was greater (p < 0.05) in heifers undergoing luteolysis than in heifers with CL maintained on Day 19 (1490 vs. 88 + 265 fmol/mg protein, respectively). Incorporation of [ 3 H]inositol into endometrial inositol phosphates in response to oxytocin also increased (p < 0.06) in those heifers undergoing luteolysis compared with those still having a functional CL (6170 vs. 120 353 and 5606 vs. 15 837 18 564 dpm/g tissue for control vs. oxytocin-treated endometrium from regressing and maintained heifers, respectively). In contrast, endometrial PGF,, secretion in response to oxytocin did not differ significantly between the two groups. These results indicate that 1) endometrial concentration of oxytocin receptors and oxytocin-induced phosphoinositide hydrolysis increased similarly during luteolysis with the greatest increases occurring around the time of onset of luteolysis; 2) endometrial PGF,. secretary response to oxytocin coincides with the early gradual increases in endometrial oxytocin receptor concentration and oxytocin-induced phosphoinositide hydrolysis between Days 13 and 16, but precedes the large increase in activity of the oxytocin receptor-phospholipase C system occurring 16-19 days post-estrus; and 3) oxytocin receptors and oxytocin-induced phosphoinositide hydrolysis are markedly increased during CL regression in cows. We suggest that a modest increase in the oxytocin receptor-phospholipase C system between Days 13 and 16 may be responsible for initiating endometrial sensitivity to oxytocin required for onset of luteolytic PGF,, secretion, whereas the large increase in the oxytocin receptorphospholipase C system occurs late in the estrous cycle as a consequence of luteolysis.

Research paper thumbnail of Ovine interferon-tau regulates expression of endometrial receptors for estrogen and oxytocin but not progesterone

Biology of Reproduction

Ovine interferon-T (olFN-T) may stabilize endometrial progesterone receptor (PR) and/or inhibit e... more Ovine interferon-T (olFN-T) may stabilize endometrial progesterone receptor (PR) and/or inhibit estrogen receptor (ER) gene expression during pregnancy recognition to suppress endometrial oxytocin receptor (OTR) formation and production of luteolytic prostaglandin (PG) F2, pulses. This study determined whether or not olFN-T stabilized PR expression in the endometrium during PR down-regulation by continuous exposure to progesterone. Twenty cyclic ewes were bilaterally ovariectomized and fitted with uterine catheters on Day 2 of the estrous cycle (Day 0 = estrus). Ewes were then assigned randomly to be treated, in a 2 x 2 factorial arrangement, with recombinant olFN-T (rolFN-T; 2 x 107 antiviral units per ewe per day) or control proteins (6 mg/day) by intrauterine injection from Days 10 to 14, and with daily i.m. injections of 20 mg progesterone from Days 2 to 14 (P) or progesterone from Days 2 to 14 plus 50 g estradiol-17p from Days 12 to 14 (P+E). All ewes were hysterectomized on Day 15. Endometrial PR mRNA (p < 0.01) and protein (p < 0.03) were higher in ewes receiving P+ E than in those receiving P alone. However, the increase in PR mRNA and protein was not as great in the endometrium of rolFN-T-treated ewes as compared to controls (p < 0.08, treatment x steroid). In ewes receiving P alone, PR mRNA and immunoreactive PR were localized to stroma and deep glandular epithelium and were not present in endometrial luminal and shallow glandular epithelium. Values for endometrial ER mRNA (p < 0.02) and ER protein (p < 0.01) were greater in controls than in rolFN-T-treated ewes regardless of steroid treatment. Among controls, ER mRNA and immunoreactive ER protein were present in the luminal and glandular epithelium and were increased in the epithelium and stroma in ewes receiving estrogen. In contrast, endometrial ER mRNA and immunoreactive ER protein were very low or absent in the endometrium of rolFN-T-treated ewes and were not increased by estrogen. Among controls, endometrial OTR density was greater (p < 0.09) in ewes treated with P+E than in those treated with P alone. In rolFN-treated ewes, endometrial OTR density was lower (p < 0.01) than in the controls. Results indicate that rolFN-T did not stabilize or prevent autolotous down-regulation of PR mRNA or protein expression in the endometrium. However, rolFN-T did suppress endometrial ER expression and OTR formation in ewes regardless of steroid treatment. The results support the hypothesis that the antiluteolytic effects of oIFNare to suppress endometrial ER gene expression in the endometrial epithelium, thereby inhibiting formation of OTR and production of luteolytic PGF,, pulses.

Research paper thumbnail of A proposed role for oxytocin in regulation of endometrial prostaglandin F2α secretion during luteolysis in swine

Advances in Experimental Medicine and Biology

Pulsatile secretion of endometrial prostaglandin (PG)F2 alpha is stimulated by oxytocin (OT) duri... more Pulsatile secretion of endometrial prostaglandin (PG)F2 alpha is stimulated by oxytocin (OT) during late diestrus in domestic ruminants (i.e., cattle, sheep and goats) and results in corpus luteum (CL) regression leading to the onset of a new estrous cycle. Pulsatile PGF2 alpha release is also responsible for CL regression in swine, but the stimulus for its secretion from the uterine endometrium is not known. We propose that OT binds to specific OT receptors (OTR) on the endometrium to stimulate phosphoinositide (PI) hydrolysis, thereby activating the inositol trisphosphate (IP3)-diacylglycerol (DAG) second-messenger system to promote pulsatile PGF2 alpha secretion. Exogenous OT administered to cyclic gilts during late diestrus (days 10-16) decreased interestrous interval in three of four experiments. However, OT did not promote CL regression in hysterectomized gilts indicating that the effect of OT was uterine-dependent. Circulating concentrations of 13,14-dihydro-15-keto PGF2 alpha (the major stable metabolite of PGF2 alpha) were increased (p &lt; 0.01) 10 min after i.v. injection of OT on days 14 and 16 in cyclic gilts and on days 10-16 in pregnant gilts, but the magnitude of the response to OT on all days in pregnant gilts was markedly reduced compared to the response in cyclic gilts on days 14 and 16. Mean density and Kd of OTR detected on endometrium of cyclic pigs 15 days post-estrus were 29.2 +/- 5.5 fmol/mg protein and 1.59 +/- 0.23 nM, respectively. Density of OTR was correlated with OT-stimulated PI hydrolysis (r = 0.83, p &lt; 0.05) and PGF2 alpha secretion (r = 0.87, p &lt; 0.10). Endometrial IP3 was increased within 30 seconds after OT treatment and preceded the increase in PGF2 alpha release stimulated by OT. Endometrial PI hydrolysis and PGF2 alpha secretion were similarly increased by AIF4-(phospholipase C activator), but not by cholera toxin (adenylyl cyclase activator). Although OT binding to OTR could be displaced by lysine-vasopressin and lysine-vasopressin stimulated PI hydrolysis, lysine-vasopressin did not stimulate PGF2 alpha release. Distinct receptors for OT and lysine-vasopressin on pig endometrium were confirmed by treatment with 100 nM OT + 100 nM lysine-vasopressin which stimulated PI hydrolysis more than 100-200 nM OT or lysine-vasopressin alone. These results support the hypothesis that OT stimulates phospholipase C to hydrolyze PI, yielding IP3 and DAG second-messengers which promote endometrial PGF2 alpha release during CL regression in pigs.

Research paper thumbnail of Physiological mechanisms of pregnancy recognition in ruminants

Journal of reproduction and fertility. Supplement, 1991

Maternal recognition of pregnancy in sheep, cattle and goats involves physiological mechanisms th... more Maternal recognition of pregnancy in sheep, cattle and goats involves physiological mechanisms that result in protection of corpora lutea from luteolysis by modification or inhibition of uterine production of luteolytic pulses of prostaglandin (PG) F-2 alpha. Ovine, bovine and caprine luteal cells release oxytocin in a pulsatile manner during late dioestrus. Oxytocin then binds to its endometrial receptors and initiates luteolytic pulses of PGF-2 alpha. Ovine, bovine and caprine trophoblast protein-1 (oTP-1, bTP-1 and cTP-1) are secreted by the trophectoderm of conceptuses between Days 10 and 21-24 of pregnancy. These antiluteolytic proteins (oTP-1 and bTP-1) are primarily responsible for inhibiting uterine production of luteolytic amounts of PGF-2 alpha. During early pregnancy, the numbers of endometrial receptors for oxytocin are significantly lower in ewes and cows, and stimulatory effects of exogenous oxytocin on uterine production of PGF-2 alpha are correspondingly reduced or a...

Research paper thumbnail of Interestrous interval of cyclic gilts is decreased by systemic but not intrauterine administration of exogenous oxytocin

Journal of animal science, 2000

Oxytocin (OT) stimulates pulsatile secretion of uterine prostaglandinF2alpha in ruminants, but th... more Oxytocin (OT) stimulates pulsatile secretion of uterine prostaglandinF2alpha in ruminants, but the role of OT in the estrous cycle regulation of pigs is not clear. These studies were performed to determine the effect of exogenous OT on interestrous interval of intact cyclic gilts. Intrauterine infusion of 80 USP units three times daily on d 10 to 16 after estrus did not decrease interestrous interval (24.5+/-1.3 d) compared with control gilts (22.5+/-1.3 d). In contrast, i.m. injections of 20 USP units of OT twice daily or 80 USP units of OT three times daily on d 10 to 16 after estrus decreased (P < 0.05) interestrous interval (20.0+/-0.3 or 19.5+/-0.4 d, respectively) compared with control gilts (20.5+/-0.3 d). When gilts received a single i.m. injection of 0 or 1 mg of estradiol valerate on d 11 and twice daily i.m. injections of 0 or 20 USP units OT on d 10 to 16 after estrus, an interaction (P = 0.05) between OT and estradiol valerate was detected. In the absence of exogenou...

Research paper thumbnail of Directional secretion of prostaglandin F(2alpha) by polarized luminal epithelial cells from pig endometrium

Prostaglandins & other lipid mediators, 2000

In swine, endometrial prostaglandin F(2alpha) (PGF(2alpha)) is the luteolysin. The capacity of lu... more In swine, endometrial prostaglandin F(2alpha) (PGF(2alpha)) is the luteolysin. The capacity of luminal epithelial cells isolated from the endometrium of day 16 cyclic pigs, to secrete PGF(2alpha)500 Omega/cm(2)), they were treated on the apical, basal or both surfaces with 0 or 100 nM oxytocin (OT) in Experiment 1 or phorbol 12-myristate 13-acetate (PMA) in Experiment 2. In the absence of OT or PMA, PGF(2alpha) secretion occurred primarily from the basal surface and was approximately 12-fold greater (P < 0.001) than from the apical surface. Treatment with OT did not stimulate PGF(2alpha) secretion from either surface regardless of which surface was treated. In contrast, PMA increased PGF(2alpha) secretion from both surfaces. Treatment of the apical surface or both surfaces with PMA increased (P < 0.001) PGF(2alpha) secretion similarly from both surfaces. Treatment of only the basal surface with PMA increased (P < 0.01) PGF(2alpha) secretion from both surfaces, but tended (P...

Research paper thumbnail of Endometrial inositol phosphate turnover in pigs is reduced during pregnancy and estradiol-induced pseudopregnancy

Journal of animal science, 1990

Three experiments were conducted to examine inositol phosphate (IP) turnover in response to treat... more Three experiments were conducted to examine inositol phosphate (IP) turnover in response to treatments applied in vitro to endometrium from cyclic (CYC), pregnant (PREG) and estradiol-induced pseudopregnant (PSP) gilts. In Exp. 1, treatments (in 25 microliters .1 M NaHCO3) were 1) control (NaHCO3), 2) 125 ng oxytocin, 3) .25 micrograms prolactin, 4) 2.5 micrograms prolactin and 5) 5 micrograms pig conceptus secretory proteins (pCSP). Basal IP turnover on d 14 (estrus = d 0) for CYC was 3.9 to 5.0-fold greater than for PREG gilts and .6 to 1.1-fold greater than for PSP gilts (P less than .05). Oxytocin increased IP turnover 23 to 42% in CYC gilts (P less than .05), but not in PREG or PSP gilts. The treatment x reproductive status interaction (P less than .05) indicated that pCSP increased IP turnover 74 to 140% in PREG gilts but decreased it 18 to 22% in CYC and 17 to 50% in PSP gilts. In Exp. 2, treatments were applied in a 2 x 2 x 2 arrangement: 1) 0 or 125 ng oxytocin; 2) 0 or 2.5...

Research paper thumbnail of Movement characteristics of boar sperm obtained from the oviduct or hyperactivated in vitro

Journal of andrology

The objectives of this study were to describe hyperactivated motility in boar sperm and to determ... more The objectives of this study were to describe hyperactivated motility in boar sperm and to determine the incidence of hyperactivation among boar sperm flushed from the oviduct. Oviducts were surgically removed from 13 gilts 32 hours after mating them to fertile boars. The majority of the sperm flushed from the oviducts was immotile, weakly motile, or stuck to mucus or cellular debris. The mucus could not be penetrated by the sperm. The remaining 3% to 19% of the flushed sperm was free-swimming. Only five hyperactivated sperm were recovered, all from the ampulla of the oviduct. The remainder of the free-swimming sperm travelled in linear trajectories and possessed significantly higher flagellar curvature ratios (the flagella were less bent) than boar sperm measured in diluted semen. Hyperactivated motility was induced in washed ejaculated boar sperm, using a 1-minute pulse of 4 mumol/L calcium ionophore A23187. The ionophore-treated sperm had significantly lower straight-line velocit...

Research paper thumbnail of Mechanisms Regulating Prostaglandin F2α Secretion from the Bovine Endometrium

Journal of Dairy Science, 1998

The mechanism that regulates luteolytic PGF2a secretion as stimulated by oxytocin is thought to i... more The mechanism that regulates luteolytic PGF2a secretion as stimulated by oxytocin is thought to in- volve induction of the inositol (1,4,5)-trisphosphate- diacylglycerol second messenger system, which mobi- lizes intracellular calcium and activates protein kinase C. In Experiment 1, endometrial explants taken from heifers on d 18.5 to 19.5 postestrus had increased PGF2a secretion after treatment with 1 mM calcium ionophore

Research paper thumbnail of Morphometric analysis of the uterine endometrium of swine on days 12 and 16 postestrus

The Anatomical Record, 2002

The uterine endometrium of swine is comprised of luminal epithelial, glandular epithelial, and st... more The uterine endometrium of swine is comprised of luminal epithelial, glandular epithelial, and stromal cells that secrete the luteolysin, prostaglandin F 2␣ (PGF 2␣), during late diestrus. However, which of these cells contribute the most to luteolytic PGF 2␣ secretion is unknown because the cellular composition of the endometrium has not been quantified. Therefore, this study quantified the cellular composition of the endometrium on days 12 and 16 postestrus by histologic and morphometric analyses. On day 12, the endometrium consisted predominantly of stromal cells (47% of total cell quantity) and glandular epithelial cells (37%), whereas luminal epithelial cells represented only 16% of the total of the three cell types. The number of glandular epithelial cells tended to increase (P Ͻ 0.10) between days 12 and 16, such that they comprised 45% of the endometrium by day 16, while the number of stromal and luminal cells did not change and accounted for 45% and 10% of the cells, respectively. Luminal epithelial cells had a 58% greater cross-sectional area (P Ͻ 0.001) than glandular epithelial cells, whereas glandular epithelial cells had a 22% greater area (P Ͻ 0.001) than stromal cells. Glandular epithelial cells decreased (P Ͻ 0.001) in cross-sectional area between days 12 and 16, whereas the area of luminal epithelial and stromal cells remained unchanged. These results indicate that the porcine endometrium is comprised predominantly of stromal and glandular epithelial cells that are likely to contribute substantially to endometrial PGF 2␣ secretion during luteolysis. The contribution of glandular epithelium to luteolytic PGF 2␣ secretion probably increases during diestrus as the number of these cells increases.

Research paper thumbnail of USDA-CSREES National Research Initiative: Support for Agricultural Research – The competitive grants program in the United States

Agricultural Research Management, 2007

Research paper thumbnail of Oxytocin stimulates prostaglandin F2α secretion from porcine endometrial cells through activation of calcium-dependent protein kinase C☆

Prostaglandins & Other Lipid Mediators, 2001

Research paper thumbnail of Intracellular free calcium in response to oxytocin in pig endometrial cells

Molecular and Cellular Endocrinology, 1999

Intracellular free calcium concentration ([Ca 2 + ] i) in response to oxytocin (OT) was studied i... more Intracellular free calcium concentration ([Ca 2 + ] i) in response to oxytocin (OT) was studied in stromal, glandular epithelial and luminal epithelial cells obtained from the endometrium of gilts 16 days post-estrus. The amplitude of increased [Ca 2 + ] i in response to 100 nM OT was greatest in stromal cells, intermediate in glandular epithelial cells and not evident in luminal epithelial cells. During continuous OT administration, stromal cells responded initially with a synchronous spike of [Ca 2 + ] i that did not require extracellular Ca 2 + and then displayed spontaneous asynchronous [Ca 2 + ] i spikes that required extracellular Ca 2 +. Each cell possessed its own characteristic response. Increasing concentrations of OT induced an increasing percentage of stromal cells responding, with some cells having nearly equal [Ca 2 + ] i responses at all concentrations and others having graded [Ca 2 + ] i responses as the concentration of OT increased. These results are consistent with the proposed mechanism of OT action in pig endometrium involving activation of phosphoinositide-Ca 2 + signaling pathway.

Research paper thumbnail of REPRODUCTION SYMPOSIUM: External influences on reproductive neuroendocrinology

Journal of Animal Science, 2014

Research paper thumbnail of Effect of recombinant alpha interferons on fertility and interestrous interval in sheep

Theriogenology, 1992

In Experiment 1, 12 unmated cyclic ewes received twice-daily intrauterine injections on Days 12 t... more In Experiment 1, 12 unmated cyclic ewes received twice-daily intrauterine injections on Days 12 to 14 of one of the following treatments: 1) ovine conceptus secretory proteins (oCSP) containing 25 microg of ovine trophoblast protein-1 (oTP-1) as determined by RIA; 2) 25 or 50 microg recombinant human interferon alpha1 (rhlFN); or 3) 1500 microg of serum proteins (oSP) from a Day-16 pregnant ewe (estrus = Day 0) per uterine horn. Ewes receiving oCSP had longer interestrous intervals (27 +/- 2 days; P&lt;0.05) than ewes receiving oSP (17 +/- 2 days). Ewes receiving either dose of rhlFN had an interestrous interval of 16 +/- 2 days which did not differ (P&gt;0.10) from that of oSP-treated ewes. In Experiment 2, 59 normally cycling ewes, mated on Day 0, received twice-daily intramuscular injections of either 2 mg recombinant bovine interferon alpha1 (rblFN) or placebo on Days 12 to 15 post estrus. On Day 16, pregnancy was confirmed by flushing a morphologically normal conceptus from the uterus. Pregnancy rates for rblFN-treated (80%) and placebo-treated (62%) ewes were not different (P&gt;0.10). Uterine flushings and conceptus-conditioned medium were assayed for oTP-1. Total oTP-1 in conceptus-conditioned culture medium was higher (P&lt;0.02) when conceptuses were from placebo-treated (104 +/- 14 microg/conceptus) than from rblFN-treated (56 +/- 12 microg/conceptus) ewes; while total oTP-1 in uterine flushings was similar (P&gt;0.10) for placebo-treated (132 +/- 15 microg/conceptus) and rblFN-treated (147 +/- 17 microg/conceptus) ewes. The interval from mating to subsequent estrus following conceptus removal was 31 +/- 1 and 28 +/- 1 days for pregnant ewes treated with rblFN and placebo, respectively. Interestrous intervals for nonpregnant ewes were longer (P&lt;0.02) for rblFN-treated (27 +/- 3 days) than for placebo-treated (18 +/- 2 days) ewes.

Research paper thumbnail of The role of essential trace elements in embryonic and fetal development in livestock

The Veterinary Journal, 2003

This review addresses the concept that essential trace minerals play a vital role in many enzymat... more This review addresses the concept that essential trace minerals play a vital role in many enzymatic and metabolic pathways that are critical for conceptus development during pregnancy in livestock species. The conceptus relies entirely on the maternal system for a sufficient supply of trace minerals and other nutrients needed for normal development. If this supply is inadequate, growth and/or health of the conceptus can be affected adversely, and many of these effects carry over into the neonatal period. Information, accumulated in our laboratory and presented herein, indicates that zinc, copper and manganese are among the trace minerals that have the greatest impact on reproduction. For example, levels of zinc, copper and manganese were several fold greater in the conceptus than in other reproductive tissues, indicating that the conceptus preferentially accumulates these minerals, an action that may be important for conceptus development, growth and survival. Moreover, some recent results indicate that increasing the biological availability of zinc, copper and manganese, by attachment to short peptide chains (i.e., proteinated trace minerals) can enhance reproductive performance of swine. Mineral concentrations in conceptuses from female pigs consuming proteinated trace minerals were greater than those from females that consumed only inorganic mineral salts. Elucidating the mechanisms whereby conceptus development and survival are enhanced by essential trace minerals may lead to development of specific feeding programs to increase the number and health of offspring at parturition, thereby allowing for further improvements in production efficiency in animal agriculture.