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Biomedical subjects

W W Thatcher

Publications and source records attributed to W W Thatcher.

At least 217 records · Page 12Linked to original sources
PubMed1984

Proteins released by cultured Day 15-16 conceptuses prolong luteal maintenance when introduced into the uterine lumen of cyclic ewes.

Experiments were performed to determine whether proteins, produced and released into the incubation medium by Day 15-16 sheep conceptuses cultured for 24-48 h, could prolong the functional lifespan of the corpus luteum (CL) when infused into the uterine lumen of cyclic ewes. Beginning on Day 12 (oestrus = Day 0) either a concentrated (2 ml) solution of total conceptus culture medium protein (2.2 mg) or diluted sheep serum (2.2 mg protein) was introduced daily via an indwelling catheter into the uterine lumen of 3 ewes for 7 days (Days 12-18). Peripheral blood samples were collected daily for 14 days (Days 12-25). On Day 25 all ewes were laparotomized and ovaries observed to determine whether CL previously marked with India ink were maintained. All controls had ovulated and formed new CL. By contrast none of the conceptus protein-treated ewes had ovulated, and their peripheral progesterone levels remained elevated. One ewe maintained a functional CL until Day 52 when she was hysterectomized. Light microscopy of histological sections prepared from the endometrium revealed glandular development comparable to that in the endometrium of cyclic animals during late dioestrus. The cells of the CL were similar to those from cyclic animals during mid- to late dioestrus. Ovine trophoblast protein ( oTP -1), a major protein secreted by the sheep conceptus between Days 13 and 21 of pregnancy, was purified from conceptus incubation medium and injected (0.2 mg protein/day) into the uterine lumen of 3 animals. Plasma progesterone concentrations indicated that oTP -1-treated animals maintained luteal function 4 days longer than did control animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Effects of heat stress during pregnancy on postpartum reproductive changes in Holstein cows.

Effects of heat stress during the last third of gestation on reproductive changes postpartum were studied in Holstein cows. Cows and heifers 160 to 190 d of gestation were assigned in June 1978 to shade (n = seven cows and two heifers) or no shade (n = eight cows and two heifers) management treatments. After parturition, all cows (n = 19) were moved to the milking herd and managed uniformly. On the day of calving and on each Monday, Wednesday and Friday thereafter until d 50 postpartum, jugular blood samples were collected. Beginning approximately 7 d postpartum, the reproductive tract of each cow was examined rectally after collection of blood samples. Estrus was monitored twice daily and cows were inseminated after d 45 postpartum. Prepartum heat stress increased 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) concentrations postpartum and increased the rate of uterine involution. Regardless of prepartum treatment, progesterone concentrations indicated that luteal phases had begun by d 12.4 +/- 1.3 postpartum, which was about 3 d before PGFM was basal. The first luteal phase lasted only 10.7 +/- .9 d. First estrus was not detected until d 32.3 +/- 4.8 postpartum. The previously gravid uterine horn had a negative effect on ovarian volume, diameter of the largest follicle and percentage of ovaries with a corpus luteum. However, prepartum heat stress attenuated this effect. This study indicates that heat stress prepartum had residual effects on postpartum reproductive changes, and that the previously gravid uterine horn exerted some control, which was attenuated by heat stress, over ovarian recrudescense. Even though heat stress prepartum affected sensitive measures of postpartum reproductive function, it did not alter days to first estrus, days open (102.3 +/- 13.1) or services/conception (2.5 +/- .3).

Animals↗
PubMed1984

Maternal recognition of pregnancy in cattle.

Nature and potential functions of chemical signals involved in the process of pregnancy recognition in cattle are discussed. The array of prostaglandins, steroid metabolites, and proteins produced by the conceptus and endometrium are described and collated with histological and physiological responses of the uterus and ovary that lead toward maintenance of the corpus luteum. Advances during the last 10 yr partially have identified the conceptus-endometrial-ovarian signal sequence that is associated with maternal recognition of pregnancy in cattle. Final evaluation of the control system should permit investigators to improve embryo survival and augment further the impact of embryo manipulation to improve genetic merit of the cattle population.

Animals↗
PubMed1983

Plasma 13,14-dihydro-15-keto-PGF alpha (PGFM) in pregnant and nonpregnant heifers prior to and during surgery and following intrauterine injection of PGF2 alpha.

On day 17 postestrus or postmating, heifers were given intrauterine injections of saline (2 pregnant, 2 non-pregnant) or 200 micrograms PGF2 alpha (7 pregnant, 6 nonpregnant) through cannulae installed surgically into the uterine horn ipsilateral to the corpus luteum bearing ovary. Jugular blood samples were collected prior to the laparotomy at which the cannulae were installed during surgery, and for 90 min following the intrauterine injection. Plasma was assayed for progesterone and 13,14-dihydro-15-keto-PGF2 alpha (PGFM). Laparotomies were reopened to confirm proper cannula placement and to determine if blastocysts were present in mated heifers. Concentrations of PGFM were higher in pregnant compared to nonpregnant heifers during the presurgery (68 +/- 26 vs 24 +/- 26 pg/ml; P less than .025) and surgery (186 +/- 47 vs 65 +/- 17 pg/ml; P less than .05) periods. Pregnancy status did not alter the mean concentrations of PGFM (pregnant, 554 +/- 70 pg/ml; nonpregnant, 422 +/- 81 pg/ml) or the half-life of its decline in concentration (18 min) following intrauterine injection of PGF2 alpha. Pregnancy at 17 days in cattle does not appear to influence PGF2 alpha transport from the uterine lumen or its metabolism in the uterus or elsewhere in response to an acute intrauterine injection.

Animals↗
PubMed1983

Uterine blood flow in relation to endogenous hormones during estrous cycle and early pregnancy.

To evaluate the extent to which endogenous hormones in peripheral blood can account for uterine blood flow (UBF), rates of blood flow and concentrations of estrone (E1), estradiol (E2), and progesterone (P4) were measured simultaneously in four sheep during the estrous cycle and the first 3 wk of pregnancy. During the estrous cycle, UBF was inversely related to the concentration of P4 (P less than 0.01) and directly related to (E1 + E2)/P4 (P less than 0.01). There was no animal in which UBF was related to estrogen alone. No statistically significant relationship between endogenous hormones and UBF was detected in any ewe during the first 3 wk of pregnancy. Data support the idea that UBF varies during the estrous cycle in relation to peripheral concentrations of P4 and (E1 + E2)/P4 but leaves open the nature of the relationship in early pregnancy.

Animals↗
PubMed1982

Metabolism of arachidonic acid in vitro by bovine blastocysts and endometrium.

Metabolism of arachidonic acid and prostaglandin F2 alpha by bovine blastocysts and endometrial slices recovered on Days 16 and 19 postmating was studied in vitro. In Experiment 1, arachidonic acid (10 microCi tritiated and 200 micrograms radioinert) was added to blastocysts and endometrial slices prior to incubation for 24 h. [3H]arachidonic acid ([3H]AA) and metabolites in extracts of culture medium and tissue homogenates were separated on columns of Sephadex LH-20. Elution profiles of [3H]AA and metabolites in extracts of culture medium revealed that 13, 14-dihydro-15-keto-PGF2 alpha (PGFM), Pge2, PGF2 alpha, and at least four unidentified compounds were produced by Day 16 and Day 19 blastocysts. Endometrial slices from both days of pregnancy produced 3H-prostaglandins. Experiment 2 was conducted to quantify PGE2, PGF2 alpha and PGFM in aliquots of culture medium from Day 16 and Day 19 blastocyst and endometrial incubates. These tissues were incubated with 200 micrograms of radioinert arachidonic acid. Day 16 blastocysts produced less (microgram/blastocyst; P less than 0.01) of each prostaglandin than Day 19 blastocysts (PGE2, 0.7 +/- 0.4 vs. 4.2 +/- 1.0; PGF2 alpha, 2.1 +/- 0.7 vs. 22.8 +/- 4.1; PGFM, 0.03 +/- 0.01 vs. 0.5 +/- 0.2). Endometrial slices produced PGE2, PGF2 alpha and PGFM, but quantities were not affected by day postmating or uterine horncorpus luteum relationships. The third experiment was conducted to determine directly if Day 19 blastocysts and endometrial slices metabolized [3H]PGF2 alpha to [3H]PGFM. Blastocysts and endometrial slices produced [3H]PGFM. Endometrial slices metabolized 34.3 +/- 1.5% of the [3H]PGF2 alpha to [3H]PGFM, while blastocysts metabolized 7.5 +/- 1.6% of the [3H]PGF2 alpha to [3H]PGFM. Results of this study indicate that bovine blastocysts and endometrial slices can metabolize [3H]AA in vitro. It is postulated that prostaglandins of blastocyst and endometrial orgin have a role in maintenance of early pregnancy in cattle.

Animals↗
PubMed1982

Androstenedione, dehydroepiandrosterone and testosterone in ovarian vein plasma and androstenedione in peripheral arterial plasma during the bovine oestrous cycle.

Catheters were placed in the carotid artery via a facial artery (n = 12) and in the ovarian vein (n = 12), and, in conjunction, electromagnetic flow meters were placed around the ovarian artery (n = 6) in cyclic beef cows. Androstenedione was quantitatively the highest and dehydroepiandrosterone the lowest of the ovarian androgens measured. Ovarian androgens were correlated positively with each other (P less than 0.05) but not with ovarian blood flow or day of the cycle. There was a trend for spikes of androgen release (ovarian vein concentration x ovarian blood flow) from the ovary to be greatest during the period of decreasing progesterone and CL regression. However, only with testosterone were spikes of release different (Days--13 to--9 less than Days -8 to -4; P less than 0.05; Day 0 = oestrus). The dynamic changes in ovarian androgens noted in this study were compatible with the concept of continuous follicular development and atresia throughout the oestrous cycle.

Androstenedione↗
PubMed1982

High molecular weight glycoproteins released by expanding, pre-attachment sheep, pig and cow blastocysts in culture.

Blastocysts isolated from sheep (Day 14--16), pigs (Day 16) and cows (Day 19) during the pre-attachment elongation phase were cultured for up to 30 h in a modified MEM medium in the presence of radioactive amino acids (L-[14C]leucine or L-[35S]methionine) to label protein and D-[3H]glucosamine to label complex saccharides. All the blastocysts released considerable quantities of non-dialysable radioactive material into the medium at an approximately linear rate over the course of the incubation. Ion-exchange chromatography on DEAE cellulose at pH 8.2 revealed that the major glucosamine-labelled product in the medium was a non-sulphated glycoprotein which eluted early in the salt gradient. None of the blastocysts produced any detectable glycosaminoglycan-like materials such as hyaluronic acid. The glycoprotein was purified by ion-exchange and gel filtration chromatography and had a molecular weight of greater than 660 000. Up to 100 micrograms of this material could be isolated from incubations of 2 sheep conceptuses. It was relatively resistant to protease hydrolysis and consisted of approximately 50% carbohydrate and 50% protein. The main monosaccharide constituents, as revealed by gas-liquid chromatography, were galactose and N-acetylglucosamine plus some mannose and fucose. No sialic acid was present. The linkages between the carbohydrate chains and the peptide appeared to be resistant to alkaline borohydride cleavage and were probably, therefore, N-glycosidic.

Animals↗
PubMed1982

Effects of heat stress during pregnancy on maternal hormone concentrations, calf birth weight and postpartum milk yield of Holstein cows.

For an evaluation of the effects of heat stress during pregnancy on calf birth weight and postpartum maternal milk yield, 21 cows and 10 heifers were assigned to shade (S; n = 16) or no shade (NS; n = 15) treatments during the last trimester of pregnancy in June 1978. At parturition, all cows were removed from treatment and uniformly managed in the milking herd. At 4-d intervals from d 199 of pregnancy to parturition, respiration rates, rectal temperature, heart rate and Black Globe temperature were recorded and blood samples obtained via tail venipuncture between 1300 and 1600 h. Weekly prepartum body weights of dam, birth weight of calf and subsequent daily milk yield were recorded. Black Globe temperature, rectal temperature and respiration rates were higher in cows given NS. Calf birth weight was lower in the NS group. Milk yield was correlated in a linear manner with calf birth weight, and cows in group NS exhibited reduced lactation performance after calving. Plasma progestin concentrations were higher in heat-stressed cows (6.0 vs 5.1 ng/ml). Estrone-sulfate concentrations were reduced in plasma of NS cows (2,505 vs 4,433 pg/ml). Thus, hormone concentrations of maternal and fetal origin were altered by environment. Plasma thyroxine concentrations were lower in NS cows (51.2 vs 66.4 ng/ml), while plasma triiodothyronine concentrations were elevated (1.8 vs 1.5 ng/ml), indicating altered thyroid hormone metabolism in heat-stressed cows. Heat stress altered endocrine dynamics during pregnancy and reduced calf birth weight and may have indirectly altered subsequent milk yield.

Animals↗
PubMed1982

Ovarian function during the estrous cycle of the cow: ovarian blood flow and progesterone release rate.

To study the function of the corpus luteum (CL) through its major secretory product, progesterone (P4), catheters were inserted into the carotid artery (via the facial artery) and the ovarian vein (n = 12), and electromagnetic flow transducers were placed around the ovarian artery in cycling Angus and Hereford cows (n = 6). Blood samples were taken four times daily (at 0600, 1200, 1800 and 2400 h) and ovarian blood flow (OBF) was monitored for 60 min immediately after each blood sampling. After chromatography, P4 was measured by radioimmunoassay. The P4 concentrations in the ovarian vein (OP4) were correlated with day of the estrous cycle (r = .25; P less than .05) and were higher during the morning hours (P less than .05). Arterial progesterone (SP4) was correlated to OP4 (r = .24; P less than .05) and day of the cycle (r = .35; P less than .05). The OBF changed among days (P less than .05). The highest rates were noted during luteal maturation (23 ml/min; SE = .09) and the lowest were noted with the demise of the CL (SP4 less than 1 ng/ml) and approach of estrus (8 ml/min; SE = .07). The OBF was correlated with SP4 (r = .24; P less than .05), although no within-day trends were noted. Exogenous estrone (6 mg) administered via jugular vein decreased OBF within 30 to 45 min, but similar injections of P4 (up to 100 mg) had no effect. Progesterone release (P4R) from the ovary [(OP4 - SP4) x OBF] was higher in the morning hours (P less than .05). The P4 concentration (OP4, SP4) and release (P4R) exhibited wide variations among and within days. The changes in OP4 and P4R were both good indicators of CL development, maturation and regression, as associated with SP4 changes. Oxygen (O2) and carbon dioxide (CO2) concentrations monitored in the carotid artery and ovarian vein indicated that the ovary with the CL was not limited in O2 availability or CO2 removal during periods of low blood flow or high secretion of P4.

Animals↗
PubMed1982

Induction of lactation: comparison of injections of estradiol-17 beta and progesterone for 7 or 21 days on prolactin response to thyrotropin releasing hormone and milk yield in dairy cattle.

Subcutaneous injections of estradiol-17 beta and progesterone (.10 and .25 mg/kg of body weight) for 7 (group I) or 21 (II) days were used. Dexamethasone (.028 mg/kg of body weight per day) or adrenocorticotropin (200 IU per day) was injected into cows in each group on days 18 to 20 (I) or 32 to 34 (II). Additionally, 100 mug of thyrotropin releasing hormone was injected intravenously on days 1, 7, 17 (I) or 1, 7, and 31 (II). Milking was initiated on days 21 (I) or 35 (II). Overall 13 of 14 cows had mean daily yields of milk greater than 5 kg; 12 had 305-day lactations. Yields of milk in cows injected for 21 days were greater on day 1 and increased more rapidly until peak was reached at 10 wk; daily mean production throughout lactation was greater (14.3 versus 10.1 kg) than for cows injected for 7 days. Lactation curves pooled within cow within treatment differed. Concentrations of estradiol, estrone and progesterone increased during steroid injections and were 2- to 3-fold higher on day 21 in II than on day 7 (I or II), but concentrations of prolactin and total glucocorticoids in plasma did not differ during this time. The quantity of prolactin released in response to injection of thyrotropin releasing hormone was greater 10 days after steroid injections than before or during steroid injections. Preinjection concentrations of prolactin were correlated with magnitude of postinjection response to thyrotropin releasing hormone, but response was not correlated with concentrations of steroids in plasma on day of injection.

Adrenocorticotropic Hormone↗
PubMed1982

Influences of environment and its modification on dairy animal health and production.

Physiological state of dairy animals is a predisposing factor in environmental influences on animal health. Critical phases of life cycle include neonatal period, postpubertal reproduction, and lactation. Primary effect of environment in neonatal period is increased disease incidence associated with reduced immunoglobulin content in plasma of calves. Cold stress has little effect on reproduction; in contrast, heat stress reduces libido, fertility, and embryonic survival in cattle. Heat stress in late gestation reduces fetal growth and alters endocrine status of the dam. Carryover effects of heat stress during late gestation on postpartum lactation and reproduction also are detectable. Heat stress of lactating cattle results in dramatic reductions in roughage intake and rumination. Decreases in roughage intake contribute to decreased volatile fatty acid production and may contribute to alteration in ratio of acetate/propionate. Rumen pH also declines during thermal stress. Electrolyte concentrations, in particular sodium and potassium, also are reduced in rumen fluid of heat stressed cattle. The decrease in sodium and potassium are related to increases in loss of urinary sodium and loss of skin potassium as well as decline in plasma aldosterone and increase in plasma prolactin. Reduction in thyroxine, growth hormone, and glucocorticoid concentrations in chronically heat stressed cattle appear to be related to decreases in basal metabolism.

Adaptation, Physiological↗
PubMed1982

Effect of pregnancy and collection technique on prostaglandin F in the uterine lumen of Pony mares.

Uterine flushings were obtained through the cervix (Method A) and through the wall of the uterus after hysterectomy (Method B) of ovariectomized Pony mares after s.c. injection of oestrogen for 1 week and progesterone for 2 weeks (Exp. 1). Non-pregnant and pregnant mares were flushed by Method A on Day 14 after ovulation and the flushings compared with those of non-pregnant mares injected i.v. with flunixen meglumine, a prostaglandin synthetase inhibitor, shortly before flushing (Exp. 3). Uterine flushings were also collected by Methods A and B from non-pregnant and pregnant Pony mares on Day 14. Endometrial and embryonic tissues from these mares were incubated with and without flunixen meglumine (Exp. 3). In all experiments, pregnancy had a significant effect on PGF content of uterine flushings or incubation media. Flushings from pregnant mares had reduced levels of PGF and were not influenced by collection technique (Exps 1 & 3). Non-pregnant Pony mares treated with progesterone responded to cervical stimulation (Method A) with an increase in intrauterine PGF over levels measured after hysterectomy (Method B) (Exps 1, 2 & 3). There was no effect on endometrial production of PGF in vitro by any tissue combination in a 2 h incubation in Krebs-Ringer-bicarbonate buffer but after 12 h incubation in Minimum Essential Medium endometrial PGF production was significantly higher when the endometria were from pregnant mares than from non-pregnant mares. PGF production in vitro was significantly suppressed by flunixen meglumine, by yolk sac membranes, and yolk sac and trophoblast, but not by trophoblast alone. The low intrauterine PGF levels in pregnant mares and the low in-vitro PGF production in the presence of the conceptus membranes may reflect inhibition of PGF synthesis and/or release by the embryo.

Animals↗
PubMed1981

Effect of estradiol-17beta on PGF and total protein content in bovine uterine flushings and peripheral plasma concentration of 13, 14-dihydro-15-keto-PGF(2alpha).

Two experiments were conducted to examine the effect of estradiol-17beta (E(2)-17beta) on content of immunoreactive prostagladin F(2)alpha (PGF, ng) and total protein (TUP, mg) in uterine flushings, as well as concentrations of 13, 14-dihydro-15-keto-PGF(2)alpha (PGFM) in plasma (Pg/ml). In experiment 1, Holstein heifers were utilized in a single reversal trial in which either E(2)-17beta (3 mg in 2 ml saline/ethanol 50:50; n=5) or vehicle alone (n=6) were given intravenously on day 14 or 15 of the estrous cycle (Period 1) following an induced estrus (day of estrus = day 0). Treatment (Trt) groups were reversed in Period 2 (Day 14 or 15 of the second estrous cycle). Jugular venous plasma was obtained before treatment (Oh), and at 5, 6, and 9h posttreatment (PT). Uterine flushings were collected nonsurgically in vivo , per cervix, via Foley catheter at 6h PT (20 ml of .9% saline per uterine horn). E(2)-17beta did not significantly alter (E(2)-17beta vs vehicle; x(-) +/- S.E.M.) PGF (1674 +/- .11 +/- 338.39 vs 1889.91 +/- 400.24 ng; P> .10) or TUP (33.25 +/- 2.57 vs 39.16 +/- 3.04 mg; P > .10). However, E(2)-17beta increased (P < .05) plasma PGFM (E(2)-17beta vs vehicle) after treatment (0h, 113.2 vs 163.8; 5h, 312.5 vs 203.9; 6h, 324.5 vs 198.0; 9h, 323.2 vs 246.8, pg/ml). In experiment 2, crossbred beef cattle received comparable treatments of either E(2)-17beta (n=5) or vehicle (n=5) on day 14 or 15 postestrus. Jugular venous plasma was obtained at 0h PT, and at 6h PT. Uterine flushings (1.9% saline, 20 ml per uterine horn) and peripheral plasma were collected at slaughter. Estradiol-17beta increased PGF (30.07 +/- 5.94 vs 8.46 +/- 2.01 ng; P> <.05) in uterine flushings as well as PGFM in plasma (E(2)-17beta : 55.82 +/- 19.13 pg/ml, at 0h and 89.31 +/- 14.02 pg/ml, at 6h, vs saline: 103.46 +/- 50.73 pg/ml, at 0h and 17.78 +/- 14.22, at 6h). Estradiol-17beta stimulated uterine production and release of PGF and protein as measured in flushings (experiment 2) as well as plasma PGFM responses (experiments 1 and 2). Uterine and/or cervical stimulation of experiment 1 may have masked uterine response to E(2)-17beta.

Journal Article↗
PubMed1981

Hormonal patterns during heat stress following PGF(2)alpha-tham salt induced luteal regression in heifers.

Ten, normally cycling, Holstein heifers were assigned to one of two environmental treatment groups (21.3 C, 59% RH or 32.0 C, 67% RH). PGF(2)alpha was used to induce luteal regression and synchronize estrus in order to evaluate temperature effects on various hormonal and physiological responses during the proestrous through metestrous periods. Environmental temperature (32.0 C) evoked a 1.4 C increase in rectal temperature and a 3.6 C increase in skin temperatures. Length of estrus was shorter (P<.10) for heifers at 32.0 C (16 vs 21 hr.). Average plasma progestin concentration between treatments was not different (P>.10). Mean estradiol concentrations were significantly (P<.10) lower in heifers at 32.0 C. No differences (P>.10) were detected in mean concentrations of LH between heifers at 21.3 C and 32.0 C. Preovulatory peak LH concentrations were 32.2 and 33.2 ng/ml plasma, respectively. All animals had a preovulatory surge of LH, suggesting that hyperthermia did not alter factors which regulate hypothalamic control of LH release. Mean basal concentrations of prolactin and corticoids were not different between temperature treatments (P>.10). However, mean corticoid response following ACTH was of lower magnitude, earlier to peak, and of shorter duration in heat stressed heifers. Heat stress did not appear to affect the hormonal milieu in peripheral plasma associated with corpus luteum regression (decrease in progestin) and ovulation (LH surge). However, duration of estrus, concentrations of estradiol at proestrus and corticoid response to injection of ACTH were reduced.

Journal Article↗