Biomedical subjects

B D Murphy

Publications and source records attributed to B D Murphy.

At least 73 records · Page 4Linked to original sources

PubMed1988

A synthetic luteinizing hormone releasing hormone vaccine. I. Conjugation and specificity trials in BALB/c mice.

The immunobiology of luteinizing hormone releasing hormone (LHRH) was explored, to provide a conceptual and practical basis for the use of LHRH in immunocastration. Cysteine substituted analogues of LHRH were synthesized including Cys1-LHRH (C1-LHRH), Cys6-LHRH (C6-LHRH) and Cys10-LHRH (C10-LHRH). These were reacted to carrier molecules using the heterobifunctional cross-linking reagent m-maleimidobenzoylsulfosuccinimide ester (SMBS), producing peptide-carrier conjugates of known peptide content and conjugation orientation. This reaction regime was found to be rapid, efficient and allowed for easy control of peptide to carrier ratios. Conjugates were used in active immunization trials in BALB/c mice to characterize the murine immune response against LHRH. BALB/c mice were shown to have the capacity to recognise all three cysteine substituted LHRH analogues and to produce antibodies cross-reactive with native LHRH. The specificity of LHRH antisera generated was found to be dependent on the site of conjugation of the peptide to carrier molecule. C1-LHRH generated carboxy terminal directed antibodies, C10-LHRH generated amino terminal directed antibodies, while C6-LHRH could generate amino terminal directed or carboxy terminal directed antibodies, or both within a given animal. No intrinsically immunodominant epitopes were seen within the LHRH molecule.

Animals↗

PubMed1988

A synthetic luteinizing hormone releasing hormone vaccine II. Temporal aspects of titer development and formulation trials in BALB/c mice.

Cysteine substituted analogues of luteinizing hormone releasing hormone (LHRH) were coupled to carrier molecules, and the resulting conjugates used to characterize the immune response to native LHRH generated in BALB/c mice and to formulate vaccines in an effort to maximize titer development. In an active immunization trial designed to characterize temporal aspects of anti-LHRH titer development, titers could be detected 1 week after initial immunization. No differences were observed in response between male and female mice. Booster immunizations could enhance the titers against LHRH. The titers developed against the carrier molecule were uniformly higher than the corresponding anti-LHRH titers throughout the course of the trial. In separate trials, vaccines were formulated and tested in BALB/c mice for titer development against LHRH. Adjuvants, carrier molecules, dosage and peptide to carrier ratio were considered. Dosages of 50 micrograms conjugate per immunization per mouse, at conjugation ratios of 3-12 peptides per 10(5) Da carrier molecule, were found to produce immune responses. Adjuvants including Havlogen and dimethyldioctadecylammonium bromide (DDA), and carrier molecules including keyhole limpet hemocyanin (KLH), porcine thyroglobulin (TGB) and equine gamma globulin (EGG) were all found to be effective.

Adjuvants, Immunologic↗

PubMed1988

Prolactin, LH, and estradiol-17 beta in utilization of lipoprotein substrate by porcine granulosa cells in vitro.

Porcine granulosa cells cultured under serum free conditions responded by increased progesterone secretion to the addition of the leuteotropic hormones, LH, prolactin, and estradiol. Provision of extracellular substrate for steroidogenesis in the form of porcine high density lipoprotein or low density lipoprotein enhanced progesterone accumulation by granulosa cell cultures. Estradiol, LH, and prolactin all greatly increased progesterone accumulation in the presence of either high or low density lipoproteins. Increases in progesterone accumulation following addition of prolactin or LH in combination with estradiol suggested the presence of a synergistic interaction among leuteotropins. Pre-exposure of granulosa cell cultures to estradiol increased the subsequent stimulatory effect of prolactin on lipoprotein utilization. It is concluded that all three leuteotropins function to enhance and may interact in the utilization of extracellular lipoprotein substrate for progesterone synthesis.

Animals↗

PubMed1988

Dose response of luteinized porcine granulosa cells in vitro to prolactin: dependency on pre-exposure to human chorionic gonadotrophin.

This study examined the hypothesis that human chorionic gonadotrophin (hCG) increases prolactin (PRL) stimulation of the utilization of lipoprotein-borne cholesterol by pig luteinized granulosa cells in culture. These cells, which luteinize in culture, were harvested from 6-mm or greater diameter follicles and cultured in the presence of 1% fetal calf serum and 1 microgram/mL insulin for 48 h. On the third day, the media were replaced with fresh serum-free media, with the same dose of insulin, and on the following day (day 4) the media were replaced with serum- and insulin-free media. At this time (day 4) hCG was added to some cultures. On day 5, cells from the group with hCG and cells from the group without hCG were treated with graded doses of ovine PRL (0.1-3.0 micrograms/mL). To a second set of cells, likewise treated, 100 micrograms of porcine low density lipoprotein (LDL) was added. Two days later (day 7) media were sampled and replaced with media alone or media containing hormones and (or) LDL. On day 9 cultures were terminated. In the cells pre-exposed to hCG, PRL (1 microgram/mL) in the presence of LDL increased progesterone production 1.7-fold (p less than 0.01) on day 7 and 2.2-fold (p less than 0.01) on day 9. In the granulosa cells in culture pre-exposed to hCG, the effect of PRL on LDL utilization was dose dependent and saturable at 1 microgram/mL on days 7 and 9. We conclude that brief pretreatment of luteinized pig granulosa cells with hCG results in a dose-dependent PRL-induced utilization of LDL for progesterone synthesis.

Animals↗

PubMed1988

Effect of prolactin and cyclic AMP on 125I-labelled low density lipoprotein uptake and metabolism by luteinized porcine granulosa cells in culture.

The present study examines the effect of prolactin (PRL) and N6-2(1)-O-dibutyryladenosine 3'5'-cyclic monophosphate (cAMP) on low density lipoprotein (LDL) uptake and metabolism by luteinized porcine granulosa cells in culture. Granulosa cells from preovulatory follicles were plated with 1% serum and 1 microgram/mL of insulin for the first 48 h. Following plating (day 3) the cells were cultured in serum-free media with the same dose of insulin. The next day the medium was replaced with serum- and insulin-free medium, and to some cultures 1.23 IU/mL of human chorionic gonadotrophin (hCG) was added. On day 5 the medium was again replaced and graded amounts of PRL (0, 0.03, 0.3, and 3 micrograms/mL) were added. Following 48 h of incubation with PRL, 20 micrograms/mL of 125I-labelled LDL was added to cultures. Surface-bound, internalized, and degraded LDLs were quantitated at 12 h following addition of LDL. To examine the effect of cAMP on LDL metabolism, the cells were exposed for 24 h to cAMP (3mM) on day 6 of culture. PRL had a stimulatory effect on LDL degradation by luteinized granulosa cells. Pre-exposure of cells to hCG augmented the stimulatory effect of PRL. Addition of cAMP also enhanced LDL degradation by luteinized granulosa cells. Both PRL and cAMP increased surface binding of LDL in cells pre-exposed to hCG, but there was no effect on internalization. The increase in cell surface binding of LDL with PRL and cAMP was less than their effect on LDL degradation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Changes in endometrial vascular permeability during the periimplantation period in the ferret (Mustela putorius).

A highly localized increase in permeability of uterine blood vessels in the immediate vicinity of implanting blastocysts was first detected on the morning of the 12th day of pregnancy (290 h post coitum). The amount of extravasated dye which accumulated at implantation sites continued to increase through the evening of Day 13 (321 h p.c.). Blastocyst expansion, as indicated by small uterine swellings, preceded a detectable change in vascular permeability by about 10 h, suggesting that the timing of increased permeability is closely associated with initial blastocyst attachment to the uterine epithelium. The results do not support the hypothesis that prostaglandins are required for increased uterine vascular permeability as two doses of indomethacin (4 and 8 mg/kg body wt) administered 5 times/day failed to decrease endometrial vascular permeability. However, the 8 mg dose did cause a significant reduction in size and number of uterine swellings and delayed or inhibited attachment of the trophoblast to the uterine epithelium in 2 of 5 ferrets. These findings suggest that prostaglandins play an important role in the process of implantation that is unrelated to decidual formation as the ferret is an adeciduate species.

Animals↗

PubMed1988

Effect of antemortem electrical stunning on functional properties of turkey muscle.

Muscle samples were collected from two groups of turkeys, one group electrically stunned before exsanguination and the other group nonstunned. Sampling was done at 0, 4, 8, and 24 h postmortem. Examination of muscle samples for glycogen, pH, adenosine triphosphate (ATP), R value (ratio of inosine nucleotides to adenosine nucleotides), and extractable protein demonstrated that glycolysis was delayed by electrical stunning. Muscle myofibrils, however, showed no effect of stunning on Mg++-ATPase, sulfhydryls, or sodium dodecylsulfate-polyacrylamide gel electrophoresis patterns. Functional properties of the muscle as measured by emulsion stability evaluations showed greater stability in prerigor muscle but no significant effect of stunning. The results indicate that although electrical stunning delayed glycolysis, the overall effect was not great enough to be a significant factor in improvement of functional properties of muscle for further processing.

Animals↗

PubMed1987

In vitro binding and utilization of lipoproteins by luteal cells from ferrets treated with dopaminergic drugs during pseudopregnancy.

The effects of administration of dopaminergic drugs in vivo on the binding and utilization of lipoproteins for progesterone synthesis in vitro by ferret luteal cells were investigated. Pimozide, a dopamine antagonist, and bromoergocriptine (CB-154), a dopamine agonist, were administered to pseudopregnant ferrets to alter prolactin (PRL) concentrations daily beginning the day after ovulation. The control group received the vehicle solution only. Corpora lutea taken on Day 13 after ovulation were dissociated and the cells were incubated with canine lipoproteins, cyclic adenosine monophosphate (cAMP), and 5-cholesten-3 beta-25-diol (25-OH-cholesterol). Canine high-density lipoprotein (HDL) and low-density lipoprotein (LDL) stimulated progesterone accumulation by luteal cells from pimozide-treated animals but not from CB-154-treated ferrets. However, when 25-OH-cholesterol, which bypasses the LDL receptor, was provided as the substrate, steroidogenesis was stimulated in all groups. Together these observations suggest that dopaminergic alteration of PRL levels preferentially affects the utilization of lipoproteins. The uptake of canine HDL and LDL by luteal cells was saturable, and a high degree of cross-reactivity was observed. Heparin released surface-bound HDL and LDL, suggesting that HDL was binding to the LDL receptor. The quantity of LDL which could be released from luteal cells by heparin treatment was greater in animals treated with pimozide and decreased by treatment with CB-154, relative to luteal cells from control animals. It was concluded that the chronic administration of pimozide or CB-154 alters serum PRL levels in vivo, and influences the subsequent binding and utilization of lipoproteins by luteal cells in vitro. PRL may increase the number of LDL binding sites in luteal cells, thereby enhancing lipoprotein uptake for progesterone synthesis.

Animals↗

PubMed1987

Use of equine chorionic gonadotrophin in female mink.

This study was comprised of three trials to determine the effects of equine chrionic gonadotrophin (eCG) on induction of sexual receptivity in female mink that had failed to mate by late in the breeding season. In the first trial one ovary was removed from unmated mink, which were then injected with 100 IU eCG. This treatment induced ovarian activity, including ovulation in the remaining ovary. In the second experiment, mink that had not been observed to mate were treated with 100 IU eCG or saline, resulting in mating of 10 11 of the eCG-treated animals, compared to 5 11 controls. Litter sizes were larger in mink in the control group, suggesting that eCG interfered with some phase of the reproductive process. In the third trial, 226 mink that had failed to mate until late in the breeding season were treated with 100 IU eCG. Of the 191 that subsequently mated, 99 produced litters, but litter sizes were reduced slightly from those observed in the remainder of the herd that bred without hormone treatment prior to March 20. Neonatal kit loss per female whelping was greater in mink treated with eCG. It is concluded that eCG treatment will induce mating in mink that refuse to mate, but this treatment results in reduced whelping success and greater neonatal kit loss. Its utility may be restricted to salvage situations where large numbers of mink fail to mate.

Journal Article↗

PubMed1987

Endocrinology of the postpartum period in the Pelibuey ewe.

The postpartum (PP) period in the Pelibuey ewe was studied. Laparotomies were performed on 14 ewes in the first year at d 10, 20 and 30 PP, and at d 10 and 20 PP in the second year on 17 ewes. Progesterone concentrations were determined in serum taken daily, from 4 to 7 d after parturition until estrus. Temporal fluctuation of luteinizing hormone (LH) was determined in samples taken at 30-min intervals for 4 h weekly. The mean interval from lambing to first ovulation was longer (P less than .001) in 1980 (59 +/- 4.9 d) than 1979 (26 +/- 3.1 d), the mean interval from lambing to first estrus was also longer (P less than .001) in 1980 (91 +/- 5.6 d) than 1979 (51 +/- 5.5 d). Follicles were present on the ovaries of the majority of the ewes at d 10. The mean diameter of the largest follicles on each ovary was reduced (P less than .025) in ewes in 1980 (6 mm) compared with 1979 (7.7 mm). Corpora lutea (CL) occurred in 67 and 75% of the ewes by d 20 and 30, respectively in 1979; no CL were found by d 20 in 1980. Progesterone profiles suggested that the PP period was composed of a period of anestrus, and a period of cyclic ovarian activity with one, two or three ovulations without behavioral estrus. In some ewes, the first cycle was of shorter duration, and its CL secreted less progesterone (P less than .05) relative to CL of silent and regular estrous cycles. Luteinizing hormone peaks were recorded as early as 6 d PP. When progesterone concentrations were elevated to luteal phase levels, the frequency, but not magnitude, of LH peaks per 4-h bleeding period was reduced (P less than .05) relative to anestrus. It is concluded that there are periods of anestrus and of silent cycles, which precede the first postpartum estrus in Pelibuey ewes.

Animals↗

PubMed1987

Genetic and temporal variation in serum concentrations and biological activity of horse chorionic gonadotrophin.

The variation in the quantity of circulating chorionic gonadotrophin (CG) and its follicle-stimulating hormone (FSH) and luteinizing hormone (LH) activity in rodent bioassay systems was investigated. A portion of the variability in total CG could be attributed to the stallion that sired the pregnancy and it was possible to select sires and mares to increase CG production. It was further demonstrated that FSH activity per unit of CG was greater at Days 71 and 104 of gestation than at Day 39. LH activity per unit of CG varied with the sire, but no effect of day of gestation could be shown. It was demonstrated that removal of sialic acid increased LH bioactivity and it is proposed that variation in biological activity between animals and during gestation may be a function of differences in carbohydrate content of CG.

Animals↗

PubMed1986

Superovulatory and endocrine responses in heifers treated with FSH-P at different stages of the estrous cycle.

Forty-two Holstein heifers were superovulated with FSH-P (total dose, 30 mg) and cloprostenol. Treatment was initiated on Day 3 (Group D3, n = 11), Day 6 (Group D6, n = 11), Day 9 (Group D9, n = 10) or Day 12 (Group D12, n = 10) of the estrous cycle. Heifers were bled daily for serum progesterone and estradiol-17beta determinations and every 6 h for a 48-h duration at the expected time of estrus for luteinizing hormone (LH) assay. Ova and embryos were flushed from the reproductive tracts and the number of corpora lutea (CL) were recorded after slaughter on Day 7 post-estrus. Mean (+/- SEM) numbers of observed CL were higher (P < 0.05) in Group D9 (33.3 +/- 4.8) than in Group D3 (15.3 +/- 3.8), with Group D6 (17.0 +/- 2.9) and Group D12 (23.9 +/- 7.3) being intermediate. Similarly, mean (+/- SEM) numbers of fertilized embryos were highest (P < 0.05) in Group D9 (13.3 +/- 2.2). There was also a nonsignificant trend for the number of transferable embryos to be greatest in Group D9. Neither serum progesterone concentrations 3 d after the LH peak nor peak serum estradiol 17beta concentrations differed among groups, but both were significantly correlated with numbers of observed CL and total ova and embryos.

Journal Article↗

PubMed1986

Beta-carotene does not influence fertility in beef heifers.

Eighty-four 18-month-old crossbred beef heifers, 3 to 4 months pregnant, were assigned by stratified randomization to either a high or low (control) beta-carotene (B-car) diet to determine the effect of long-term supplementation of B-car on reproductive performance. The heifers were followed through pregnancy, calving and subsequent breeding. The basal diet consisted of barley, canola meal and barley straw. Heifers supplemented by B-car received 625 mg B-car per day in the concentrate. Vitamin A and D complex injections were given monthly to all heifers. Heifers were bred by artificial insemination after Day 60 postpartum. Throughout the study heifers fed the B-car supplement had higher levels of B-car in plasma (> 300 ug/dl) (P < 0.01) than the heifers fed the control diet (< 50 ug/dl). Vitamin A status was satisfactory in all heifers throughout the study. Birth weight of calves, weight gain, and incidence of mortality were not influenced by B-car. For the control and B-car treatments, days postpartum to first normal luteal phase were 67.5 and 62.6 days; days postpartum to first detected estrus were 70.1 and 65.3, and services per conception were 1.24 and 1.29, respectively. Long-term supplementation of B-car increased prepartum plasma progesterone but had no effect on postpartum fertility.

Journal Article↗

PubMed1986

Evidence for dopaminergic regulation of prolactin and a luteotropic complex in the ferret.

The role of dopaminergic agents in prolactin (Prl) release and the luteotrophic role of Prl and luteinizing hormone (LH) were investigated in pseudopregnant female ferrets. A single injection of the dopamine antagonist pimozide (0.63 mg/kg) resulted in a tenfold elevation of plasma Prl in anestrous females. Subcutaneous injection of pimozide on alternate days from Day 2 through Day 16 of pseudopregnancy elevated both Prl and progesterone levels. Daily treatment with the dopamine agonist 2 alpha-bromoergocryptine (bromocriptine, 4 mg/kg), from Day 2 through Day 16 of pseudopregnancy lowered levels of both plasma Prl and progesterone. Neither pimozide nor bromocriptine had a direct effect on progesterone secretion by luteal cells in vitro. Daily intraperitoneal administration of a monoclonal antibody against gonadotropin-releasing hormone from Day 2 through Day 10 of pseudopregnancy lowered both plasma LH and progesterone, but had no effect on plasma Prl concentrations. Daily administration of equine antisera against bovine LH or 100 IU of human chorionic gonadotrophin to pseudopregnant ferrets lowered progesterone levels. It is concluded that Prl release is influenced by dopaminergic compounds, and both Prl and LH are required for luteal maintenance in the ferret.

Anestrus↗

PubMed1986

Blood vitamin and choline concentrations in healthy domestic cats, dogs, and horses.

Blood concentrations of thiamin, biotin, nicotinates, pantothenates, folates, riboflavin, vitamins A, B6, B12, C, E, beta-carotene and choline were analyzed in healthy animals (23 horses, 25 dogs, and 29 cats). B-Complex vitamins and choline also were analyzed in the liver of the dogs and cats. Vitamin concentrations in the blood and livers of dogs were similar; however, blood vitamin A and beta-carotene concentrations were lower in the cat than in the dog. Horses had a higher B12 blood concentration than did the dogs and cats. These data can be useful for detecting overt and hidden vitamin deficits in these species due to various conditions.

Animals↗

PubMed1985

Effect of lipoproteins and luteotrophins on progesterone accumulation by luteal cells from the pregnant pig.

The roles of prolactin (Prl) and LH in the maintenance of luteal function in pregnant pigs were investigated. Luteal cells from pigs between days 70 to 95 of pregnancy were dissociated and incubated for 4 h. In the absence of exogenous cholesterol, LH exhibited a dose-dependent stimulatory effect on progesterone secretion. Prl had a mild stimulatory effect on progesterone accumulation and at lower doses Prl potentiated the response to LH. Low density lipoprotein (LDL) but not high density lipoprotein (HDL) had a mild stimulatory effect on progesterone secretion. When exogenous cholesterol was provided as the substrate in the form of LDL or HDL, Prl had a striking stimulatory effect on progesterone secretion. When 25-hydroxycholesterol which bypasses the lipoprotein receptor was provided as the substrate, Prl failed to stimulate progesterone accumulation. The stimulatory effect of LH was potentiated when LDL, HDL, or 25-hydroxycholesterol were present. The results of this study suggest that LH increases the uptake of exogenous cholesterol in the form of lipoproteins and enhances the utilization of internalized cholesterol for progesterone synthesis. Prl appears to stimulate progesterone synthesis by enhancing the uptake of lipoproteins.

Animals↗

PubMed1985

Monoclonal antibodies against LHRH: development and immunoactivity in vivo and in vitro.

Mouse myeloma NS1-Ag4 cells were fused with spleen cells from a BALB/c mouse previously immunized with luteinizing hormone releasing hormone (LHRH) conjugated to serum bovine albumin (BSA). Fused cells were grown in HAT restrictive medium which was screened for LHRH binding ability via a primary binding assay employing [125I]LHRH and cold ethanol precipitation. One clone (hy-USASK/DSIL-LHRH-A1) was selected for further study. Cell culture fluid and ascites fluid bound 30% of [125I]LHRH at 1:4000 and 1:400,000 dilution respectively. A competitive inhibition assay using ascites fluid at 1:2,000,000 dilution and LHRH standards at 0.125-32.0 ng/ml was established. Initial studies using rabbit anti-mouse allotype sera in a horseradish peroxidase (HRP)-ELISA system indicate the antibody is IgG1. A dose of 0.5 ml ascites fluid containing LHRH antibody given intravenously (i.v.) on day 9 of gestation was effective in terminating pregnancy in rats. A 1 cm progesterone implant made of elastomer polymer and placed interperitoneally blocked this effect. Ascites fluid (4.5 ml) containing LHRH antibody, when infused i.v. into mature spayed female dogs induced a precipitous decline in mean luteinizing hormone (LH) levels and reduced LH pulsatility over 4 days. It was concluded that the mouse monoclonal antibody is specific for LHRH, and can interrupt reproductive events in vivo.

Abortion, Induced↗

PubMed1985

Binding of high-density lipoproteins to luteal membranes: the role of prolactin, luteinizing hormone, and circulating lipoproteins.

Ovarian and adrenal membranes from immature gonadotropin-primed rats, treated with 4-amino-pyrazolopyrimidine (4APP) to reduce endogenous lipoprotein levels, displayed higher binding of porcine high-density lipoprotein (HDL) when compared to control rats. Immature, hypophysectomized (HYPOX) rats bearing corpora lutea (CL) on Day 5 after ovulation had lower levels of serum progesterone and reduced capacity for HDL and human chorionic gonadotropin (hCG) binding to ovarian membranes when compared with intact animals. Hypophysectomy also reduced the number of HDL binding sites in adrenal membranes. Treatment of HYPOX animals with luteinizing hormone (LH) and prolactin (Prl) alone or in combination increased the HDL binding sites in the ovary relative to HYPOX-untreated rats. Neither hormone affected binding to adrenals, where only adrenocorticotropic hormone (ACTH) enhanced HDL binding. LH treatment reduced the serum progesterone levels and hCG binding to the ovaries, whereas Prl administration increased progesterone levels with no effect on hCG binding. We conclude from this study that HDL binding in the luteinized ovary is regulated by Prl and LH and circulating lipoproteins, whereas in adrenals it is regulated by ACTH and circulating levels of lipoproteins.

Adenine↗