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Biomedical subjects

W T Bosu

Publications and source records attributed to W T Bosu.

At least 19 recordsLinked to original sources
PubMed1991

Serum cortisol changes in heifers induced by lipid X: a monosaccharide precursor in the biosynthesis of Gram-negative endotoxin.

An experiment was conducted to measure the changes in serum cortisol and luteinising hormone (LH) concentrations in heifers during the luteal phase of the oestrous cycle after the administration of lipid X and Gram-negative endotoxin. Nine heifers whose oestrous cycles were synchronised with prostaglandin F2 alpha were assigned at random on day 10 after the second prostaglandin injection to one of the following groups. Group 1 heifers (n = 3) received 5 micrograms kg-1 bodyweight of Escherichia coli endotoxin as an intrauterine infusion and one hour later received an intravenous injection of lipid X (5 micrograms kg-1 bodyweight). The treatment was reversed in group 2 heifers (n = 3), endotoxin was administered one hour after the lipid X treatment. Group 3 heifers (n = 3) received endotoxin infusion and lipid X treatment at the same time. Similar dosages and routes of administration were used in all the groups for lipid X and endotoxin treatments. Blood samples were collected once every 15 minutes for seven hours, beginning once hour before and six hours after the initial treatment. In group 1 heifers there was a fourfold increase in serum cortisol concentrations within 30 minutes after both the treatments (from 6.5 to 24.6 ng ml-1 and from 7.3 to 29.5 ng ml-1 respectively). In group 2 heifers the cortisol concentrations increased from the baseline concentrations of 7.2 to 33.2 ng ml-1 within 30 minutes after lipid X treatment and remained at 22.5 ng ml-1 during endotoxin treatment. There was a further increase in cortisol concentrations (28.9 ng ml-1) after the endotoxin treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Temporal changes in metabolites of prostanoids in milk of heifers after intramammary infusion of Escherichia coli organisms.

A study was conducted to characterize the changes in the concentrations of three metabolites of prostanoids in the milk of a) heifers (n = 14; control) inoculated with Escherichia coli (E. coli) organisms into the udder and b) in heifers (n = 10; treatment) vaccinated with E. coli bacterin and treated similar to control heifers. Milk samples were obtained from the challenged quarter and analyzed for the concentrations of stable metabolites of thromboxane A2 (TXB2), prostacyclin (PCM) and prostaglandin E2 (PGEM) using radioimmunoassays. In control heifers milk TXB2 concentrations were significantly higher (P = 0.03) compared to treated heifers. Milk PCM concentrations increased significantly (P = 0.02) in control and treated heifers after the respective treatments, however, differences between the two groups were not significant. Milk PGEM concentrations also increased significantly (P = 0.02) in control and treated heifers after the respective treatments, and there were no differences between the two groups. Results of the present study suggest that, the prostanoids have a role in the pathophysiologic process of coliform mastitis.

Animals↗
PubMed1990

Quantitative morphologic study of the pituitary and thyroid glands of dogs administered L-thyroxine.

To determine the effects of long-term thyroxine treatment, histomorphometric analysis was performed on the pituitary and thyroid glands of healthy dogs, dogs treated for 9 weeks with a replacement dose of L-thyroxine, and dogs at 6 weeks after cessation of thyroxine treatment. In treated dogs, the volume density of thyrotropes decreased during thyroxine treatment and increased 6 weeks after cessation of treatment, compared with thyrotropes of healthy nontreated dogs. The activity of the thyroid gland was decreased in dogs during thyroxine treatment, as evidenced by decreases in epithelial volume density, epithelial height, and follicular area, and increase in colloid volume density, compared with thyroid gland activity in nontreated dogs. After cessation of thyroxine treatment, the thyroid gland had decreased colloid area, follicular area, and epithelial volume density, and increased interstitial volume density, compared with the thyroid gland of healthy nontreated dogs. Thyroxine treatment resulted in suppression of pituitary thyrotropes and thyroid follicular activity.

Animals↗
PubMed1990

Thyroid function tests in euthyroid dogs treated with L-thyroxine.

The effects of treatment with L-thyroxine (1 mg/m2 of body surface/d, PO, for 8 weeks) on the thyroxine (T4) and triiodothyronine (T3) responses to thyrotropin (TSH) and thyrotropin-releasing hormone (TRH) administration were determined in 10 euthyroid Beagles; 4 other dogs acted as controls. The TSH response test was performed before treatment and at weeks 2, 4, and 8 of treatment in all dogs and at 2 and 4 weeks after cessation of treatment in 6 dogs. The TRH response test was performed before treatment and at week 6 of treatment in all dogs and at 5 weeks after cessation of treatment in 6 dogs. Suppression of the T3 response to TSH was evident at treatment week 2, whereas the T4 response was suppressed at week 4 and remained suppressed for the duration of the study. Four weeks after stopping treatment, T4 and T3 responses to TSH in 2 dogs were within the hypothyroid range. The T4 response to TRH was completely suppressed after 6 weeks of thyroxine treatment, but returned to pretreatment values by 5 weeks after cessation of treatment. Suppression of thyroid and pituitary function is evident after administration of a replacement dose of L-thyroxine to euthyroid dogs.

Animals↗
PubMed1989

Surgical management of urovagina and associated infertility in a cow.

Severe urovagina, secondary to a calving injury, was diagnosed as the cause of necrotizing endometritis and infertility in a Holstein cow. Urethral extension surgery resulted in resolution of the urovagina and endometrial recovery. Temporary paresis of the bladder was a postsurgical complication. The cow conceived promptly after insemination, but suffered similar injuries subsequently during calving.

Animals↗
PubMed1989

Suppression of preovulatory luteinizing hormone surges in heifers after intrauterine infusions of Escherichia coli endotoxin.

A study was conducted to test the hypothesis that high cortisol concentrations associated with products of infections (endotoxin) cause derangement in the neuroendocrine mechanism controlling ovulation in heifers. Eight Holstein heifers were given 2 injections of prostaglandin (PG), 11 days apart, to synchronize estrus. Starting from 25 hours after the second injection of PG (PG-2), the uterus of each heifer was infused with 5 ml of pyrogen-free water (control, n = 3) or Escherichia coli endotoxin (5 micrograms/kg of body weight) in 5 ml of pyrogen-free water (treated, n = 5), once every 6 hours for 10 treatments. Blood samples were obtained every 15 minutes via indwelling jugular catheter for an hour before and 2 hours after each infusion, then hourly until an hour before the next infusion. Ultrasonography of the ovaries was performed every 12 hours, starting 24 hours after PG-2 injection until 96 hours after PG-2 injection. Serum concentrations of luteinizing hormone and cortisol were determined by validated radioimmunoassays. Changes in cortisol concentrations were not detected in control heifers with preovulatory luteinizing hormone surges at 60 to 66 hours after PG-2 injection, followed by ovulations 72 to 96 hours after PG-2 was injected. None of the treated heifers ovulated, and the resulting follicular cysts (14 to 18 mm diameter) persisted for 7 to 21 days. In all treated heifers, serum cortisol concentrations increased (4- to 10-fold) during the first 2 hours after each infusion and then decreased gradually until the next infusion. Luteinizing hormone concentrations remained at baseline values throughout the treatment period in all treated heifers.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Reproductive physiology of the nonpregnant mare. An overview and update.

This article reviews the reproductive events in the nonpregnant mare with emphasis on recent advances. The discussion is restricted to the salient features of puberty (prenatal and prepubertal events), seasonality (gonadotropins, photoperiod, and other modifying factors), and the estrous cycle (hormones, estrus, diestrus, and the control of cyclicity) in the nonpregnant mare.

Animals↗
PubMed1988

Short-term changes in serum luteinizing hormone, ovarian response and reproductive performance following gonadotrophin releasing hormone treatment in postpartum dairy cows with retained placenta.

Thirty-six postpartum Holstein cows consisting of eighteen cows that shed the placenta soon after calving (NRP) and eighteen cows that retained placenta greater than 24 h (RP) were used. There were four treatment groups. Group I consisted of 9 NRP cows which received intramuscular injection of sterile saline on day 15 postpartum. The second group consisted of 9 NRPN cows which received 100 micrograms of gonadotrophin releasing hormone on day 15 postpartum (NRPT). The third group consisted of 9 RP cows which received saline on day 15 postpartum (RPN) and the fourth group consisted of 9 RP cows which received 100 micrograms of gonadotrophin releasing hormone on day 15 postpartum (RPT). Blood samples were collected once daily during the first month and once every other day during the second month postpartum. In addition fourteen cows (RPT, n = 7; NRPT, n = 7), were used to study short-term changes in serum luteinizing hormone concentrations following gonadotrophin releasing hormone treatment on day 15 postpartum. Blood samples were obtained from these cows every 15 min during 1 h before and 6 h after gonadotrophin releasing hormone administration. Sera from all samples were assayed for progesterone and luteinizing hormone concentrations. Starting from four days after calving rectal palpations and ultrasound examinations of the ovaries were carried out once every four days until day 28 postpartum in order to monitor ovarian changes. All cows were inseminated on the first estrus after day 60 postpartum and examined for pregnancy between 35 and 42 days after insemination.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Plasma endotoxin and concentrations of stable metabolites of prostacyclin, thromboxane A2, and prostaglandin E2 in postpartum dairy cows.

The presence of endotoxin in plasma and patterns of stable metabolites of prostacyclin (PC), thromboxane A2 (TXA2) and prostaglandin E2 (PGE2) were determined during the first postpartum estrous cycles in sixteen dairy cows. These included 8 cows with uterine infections which exhibited shortened luteal phases (SC) and 8 cows which had normal luteal phases (NC) after the first post partum ovulations. Endotoxin was consistently detected in all SC cows during the abbreviated estrous cycles while plasma samples of NC cows were free of endotoxin. Plasma concentrations of TXA2 metabolite was higher in SC cows (p less than 0.05) (1785-3452 pg/ml) compared to NC cows (723-1240 pg/ml). Similarly, plasma concentrations of PC metabolite was higher in SC cows (p less than 0.07) (423-1847 pg/ml) compared to NC cows (159-325 pg/ml). In contrast, plasma concentrations of PGE2 metabolite was higher in NC cows (p less than 0.05) (850-2219 pg/ml) compared to SC cows (455-628 pg/ml). The results of this study suggest that postpartum uterine infections mediate the release of prostaglandins from the uteri by means of the endotoxin and endotoxin appears to stimulate selectively the production of PC and TXA2 favoring early demise of corpora lutea formed after first postpartum ovulations in dairy cows.

Animals↗
PubMed1987

Histology of the normal and retained equine testis.

Abdominal, inguinal and scrotal testes of horses were examined grossly and by light microscopy. An average of 1.5, 2.3 and 4.6 layers of spermatogenic cells, and mean seminiferous tubule diameters of approximately 66.2, 83.6 and 146.6 micron in the abdominal, inguinal and scrotal testes, respectively, were recorded. The interstitial spaces and the number of interstitial cells (of Leydig) seemed to be increased while spermatogenesis appeared to be arrested in the retained testes. Early spermatocytes were the most mature stages of the spermatogenic cells in the retained testes. An extensive vacuolation of spermatogenic cells was evident in these testes. The changes may result due to a high temperature of the abdominal environment in concert with the altered production of androgens.

Animals↗
PubMed1987

Peripartal changes in serum alkaline phosphatase activity and lactate dehydrogenase activity in dairy cows.

Peripartal serum alkaline phosphatase activity and lactate dehydrogenase activity were measured in 30 dairy cows in order to examine the association between retained fetal membranes and enzyme activity. Daily blood samples were obtained from pregnant cows, starting 15 days before the expected day of calving until eight days after parturition. Sera from 15 cows which retained fetal membranes longer than 24 hours and 15 cows which shed fetal membranes within six hours after parturition were analyzed for alkaline phosphatase and lactate dehydrogenase enzyme activities. Mean alkaline phosphatase enzyme activities ranged from 15.93 to 32.6 U/L in retained and nonretained placenta cows. There was a trend towards higher serum alkaline phosphatase activities in retained placenta cows but the differences were not significant among the groups (P greater than 0.05). Mean lactate dehydrogenase activities ranged from 307.2 to 438.86 U/L in nonretained and retained placenta cows. Lactate dehydrogenase enzyme activities in nonretained and retained placenta cows were similar (P greater than 0.05). The alkaline phosphatase and lactate dehydrogenase enzyme activities peaked at the time of parturition in both groups. However, the differences in alkaline phosphatase and lactate dehydrogenase activities on different days within non-retained and retained placenta cows were significant (P less than 0.05). Results indicate that prepartal changes in alkaline phosphatase and lactate dehydrogenase enzyme activities are not predictive of placental retention postpartum.

Alkaline Phosphatase↗
PubMed1986

The effects of gonadotrophin releasing hormone administration four days after insemination on first-service conception rates and corpus luteum function in dairy cows.

One hundred and eighty-five Holstein-Friesian dairy cows received either sterile water or 250 micrograms of gonadotrophin releasing hormone intramuscularly on the fourth day after the first service postpartum. Heparinized blood samples were taken immediately prior to treatment (day 4) and on day 8 postinsemination for analysis of plasma progesterone concentration. Pregnancy diagnosis was carried out by rectal palpation at 42 days postinsemination and reconfirmed after 60 days postbreeding. The pregnancy rates after first, second or third service were not significantly different between gonadotrophin releasing hormone-treated and control cows. Plasma progesterone concentrations on day 4 and day 8 postinsemination, as well as the change in plasma progesterone concentration from day 4 to day 8, were similar for gonadotrophin releasing hormone-treated and control cows. The plasma progesterone concentrations on day 8 postbreeding were significantly higher (p less than 0.005) and the change in progesterone concentrations between days 4 and 8 were significantly greater (p less than 0.002) in pregnant cows compared to nonpregnant cows.

Animals↗
PubMed1986

The maternal to fetal transfer of immunoglobulins associated with placental lesions in sheep.

In this study we evaluated maternofetal transmission of immunoglobulins in ewes under conditions of altered placental morphology. Intravenous injection of human red blood cells was used to induce immunoglobulins in pregnant ewes. The hemagglutination test was used to detect antibody in maternal serum, fetal and placental fluids. Placental injury was induced by intravenous inoculation of Escherichia coli endotoxin or spores of Aspergillus fumigatus into pregnant ewes at days 99 or 100 of gestation respectively. Placental infarction, thrombosis of maternal placental vessels and variable neutrophil infiltrate characterized lesions produced by A. fumigatus. Endotoxin treated ewes developed marked placental edema, congestion, hemorrhage and focal loss of uterine epithelium. Human red blood cell agglutinating antibody was not detected in placental or fetal fluids obtained from ewes with either of the above placental lesions. Placentitis of undetermined etiology was observed in seven ewes. Two ewes had received A. fumigatus, two had received endotoxin and three were untreated ewes. Histological examination of their placentas revealed trophoblastic and endometrial epithelial necrosis and necrotizing vasculitis of the chorioallantois. Human red blood cell agglutinating antibody was detected only in the fetal and placental fluids of the seven ewes with these placental lesions. The nature of these lesions would have produced a functional confluence of the maternal and fetal circulations. Antibody transfer from dam to fetus was observed only in association with placental lesions which produced this confluence of circulations. The character of the placental lesions, rather than the mere presence of placental lesions apparently determined the transfer of immunoglobulins.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Veterinary↗
PubMed1986

Serum progesterone concentrations associated with superovulation and premature corpus luteum failure in dairy goats.

The incidence and cause of premature corpora lutea failure and the response to luteinizing hormone treatment was investigated in superovulated dairy goats. Does were treated with 1000 IU pregnant mare serum gonadotropin intramuscularly, followed by either luteinizing hormone (treated group) or saline (control group). Serum progesterone concentrations were used to monitor corpus luteum function. The dose of pregnant mare serum gonadotropin used induced superovulation in a majority of the does, but the responses varied depending on the time of year. Premature regression of the corpora lutea occurred in 4 of 18 does after pregnant mare serum gonadotropin treatment, but there was no difference in the incidence of corpora lutea failure between treated and control groups. Decreases in serum progesterone concentrations were evident by day 3 after ovulation in does that experienced corpora lutea failure indicating this to be the critical time for premature regression of the corpora lutea in superovulated does.

Animals↗
PubMed1985

Interrelationships between postpartum events, hormonal therapy, reproductive abnormalities and reproductive performance in dairy cows: a path analysis.

Path analysis was used to determine the interrelationships between postpartum administration of gonadotrophin releasing hormone and cloprostenol and the occurrence of reproductive disease and reproductive performance in dairy cows. The data analysed were those collected on 226 Holstein-Friesian cows calving in a commercial dairy herd during a 17 month period (May 1, 1981 to October 1, 1982). Cows administered gonadotrophin releasing hormone at day 15 postpartum experienced an improved rate of uterine involution as determined by rectal palpation nine days later. Although this improved rate of uterine involution reduced the risk of pyometritis, it actually directly delayed conception. Also, gonadotrophin releasing hormone therapy directly resulted in an increased incidence of pyometritis which in turn resulted in an increase incidence of cystic ovarian disease and anestrus. The occurrence of these abnormalities resulted in increased intervals from calving to first observed estrus, first service and conception. In addition to this effect, the administration of gonadotrophin releasing hormone was also associated with increased plasma progesterone concentrations at days 24 and 28 postpartum which delayed conception. Cloprostenol therapy at day 24 postpartum resulted in a decreased plasma progesterone concentration at day 28 postpartum which was directly and indirectly associated with a decrease in the calving to conception interval. The indirect effects were mediated by a reduction in days to first estrus. Cloprostenol therapy also directly resulted in a decreased calving to first observed estrus interval for reasons not attributable to the level of progesterone at day 28.

Anestrus↗
PubMed1985

Interrelationships between ambient temperature, age at calving, postpartum reproductive events and reproductive performance in dairy cows: a path analysis.

Path analysis was used to determine the interrelationships between ambient temperature, age at calving, postpartum reproductive events and reproductive performance in dairy cows. The data used in the analysis were collected on 226 Holstein-Friesian cows calving in a commercial dairy herd during a 17 month period (May 1, 1981 to October 1, 1982). The data were obtained from a double blind study evaluating the effects of gonadotrophin releasing hormone and cloprostenol in postpartum cows. Rectal palpation to assess uterine involution and ovarian activity was performed on each cow on days 15, 24 and 28 postpartum. At the same time, blood samples were collected for subsequent progesterone assay. Data were recorded on the occurrence of reproductive diseases and events from the time of parturition until the diagnosis of pregnancy or until the cow left the herd in the case of culled cows. There was an increase in the incidence of retained placenta, in the percentage of cows with abnormal vaginal discharge in the early postpartum period as well as a delay in uterine involution during the winter months. In addition, cows calving during the winter had prolonged intervals to first estrus, first service and conception compared to cows calving during the summer. (Cows calving during the warmest months, on average, were seen in estrus 24 days sooner, received first service 42 days sooner and conceived 27 days sooner than cows calving during the coldest months of the year).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗