Biomedical subjects

F W Bazer

Publications and source records attributed to F W Bazer.

At least 145 records · Page 8Linked to original sources

PubMed1991

Cloning and expression in Saccharomyces cerevisiae of a synthetic gene for the type-I trophoblast interferon ovine trophoblast protein-1: purification and antiviral activity.

Ovine trophoblast protein-1 (oTP-1) is a unique, Type I, trophoblast interferon (IFN) that possesses potent antiviral activity and is thought to be primarily responsible for maternal recognition of pregnancy in sheep. To provide sufficient amounts of protein for detailed studies, a synthetic gene for oTP-1 was designed and assembled in Escherichia coli, subcloned into a yeast expression plasmid, and used to overproduce recombinant oTP-1 in Saccharomyces cerevisiae. Recombinant oTP-1 was purified from soluble yeast extract using sequential ion-exchange and molecular sieve chromatography. Recombinant oTP-1 purified in this fashion exhibited potent antiviral activity (0.6 x 10(8) U/mg) similar to native oTP-1. This expression system will enable production of large quantities of soluble, biologically active, and correctly processed recombinant oTP-1. Furthermore, the synthetic gene construct facilitates introduction of mutations for ongoing structure/function studies of this unique, Type I, trophoblast IFN.

Amino Acid Sequence↗

PubMed1991

Characterization of feline conceptus proteins during pregnancy.

This study characterized proteins secreted de novo by feline conceptuses collected on Days 10, 12, and 15 (n = 22, preimplantation blastocysts); Days 15, 16, 17, 19, 21, and 25 (n = 6, postimplantation zonary girdle [ZG] i.e. trophoblast and endometrium); and Days 30, 36, 39, and 50 (n = 5, postimplantation ZG and free chorioallantois [CA]) and cultured in Minimal Essential Medium. De novo secretion was shown by incorporation of 3H-leucine into proteins detected in culture media by 2D-PAGE and fluorography. Western blotting, and NH2-terminal amino acid microsequencing. Major radiolabeled proteins identified as they appeared temporally on fluorographs were as follows: feline conceptus protein 1 (fCP1), Mr = 20,000, pI 5.0-5.3; fCP2, Mr = 80,000, pI 6.5-7.2; fCP3a, Mr = 67,000, pI 6.3-6.5; fCP3b, Mr = 67,000, pI 5.9-6.3; fCP4, Mr = 56,000, pI 5.0-6.0; and fCP5, Mr = 29,000, pI 5.0-5.8. The fCP1 was produced by blastocysts on Days 10-15, ZG on Days 16-25, and CA on Day 30; on Days 39-50, CA synthesized 5 proteins, possibly fCP1 isomers. The fCP2, fCP3a and b, and fCP4 were produced by blastocysts on Day 15, ZG on Day 25, and CA on Days 30-50. The fCP5 was made by ZG on Days 16-36 and by CA on Days 30-39. Western blotting identified fCP1 as retinol-binding protein (RBP), fCP2 as alpha fetoprotein, fCP3a as albumin, and fCP3b as transferrin. Amino acid sequence homologies between fCP1 and rabbit and human plasma RBP and porcine conceptus RBP2 were 93, 96, and 100%, respectively, at the first 37 NH2-terminal amino acids. The identities of fCP4 and fCP5 have not been established. Antiviral activity detected in all media was less than 3 units/ml when tested with feline fibroblast cells infected with vesicular stomatitis virus.

Amino Acid Sequence↗

PubMed1991

Regulation of synthesis of uterine secretory proteins: evidence for differential induction of porcine uteroferrin and antileukoproteinase gene expression.

Mechanisms regulating the expression of two pregnancy-associated proteins of the porcine uterus, namely the iron-transport protein uteroferrin (UF) and the lysosomal serine proteinase-inhibitor antileukoproteinase (ALP), were investigated by comparing the effects of estrogen (E), progesterone (P4), and conceptuses on the steady-state levels of their mRNAs. For UF, the expression of mRNA with production and secretion of the corresponding protein was also investigated. Progesterone increased the levels of endometrial UF mRNA and of secreted UF, but did not affect the levels of ALP mRNA in ovariectomized gilts that had received P4 treatment for 8 days. Estrogen inhibited the accumulation of endometrial UF mRNA, increased UF secretion in these gilts, but had no effect on levels of ALP mRNA. Administration of E to gilts on Day 11 of the cycle slightly diminished UF mRNA levels at 1 h post-E; had no effect at 6, 12, and 24 h post-E; and increased levels of secreted UF in uterine luminal fluids 24 h post-E. The presence of conceptuses increased levels of endometrial ALP mRNA and decreased UF protein in uterine luminal fluids, but did not affect levels of endometrial UF mRNA. Myometrium, endometrium, and placenta from Day 75 and Day 105 pregnant gilts were also evaluated for ALP and UF mRNA expression to determine regional expression of these steroid-regulated genes. Myometrium and endometrium expressed comparable levels of UF and ALP mRNAs within Days 75 or 105, but placenta did not express detectable levels of mRNA for either protein. Within the myometrium, UF protein is immunolocalized mostly to the inner circular and to a lesser extent to the outer longitudinal layer of smooth muscle. These results indicate that E, P4, and presence of conceptuses differentially affect endometrial expression of ALP and UF mRNAs and secretion of UF.

Acid Phosphatase↗

PubMed1991

Relationship between variation in conceptus development and differences in estrous cycle duration in ewes.

The objective of this study was to examine conceptus development on Day 13 in ewes with estrous cycles of different durations. Ewes (n = 80) were screened according to the length of their estrous cycles. Subsequently, ewes that had either SHORT or LONG cycles were utilized (15.9 +/- 0.1 or 18.6 +/- 0.4 days; mean +/- SEM, p less than 0.01; 10 ewes per group). Jugular blood samples were collected twice daily from Days 0-6 after mating and then once a day until slaughter on Day 13. Concentrations of progesterone in plasma and amounts of ovine trophoblast protein-1 (oTP-1), protein, and prostaglandins (PG) E2 and F2 alpha (PGF2 alpha) in uterine flushings were determined. Concentrations of progesterone were greater (Day by treatment interaction, p less than 0.01) on Days 2-4 for ewes in the SHORT group. On Day 5 and thereafter, progesterone concentrations were not different between groups. More (p less than 0.05) oTP-1 and protein (8.1 +/- 1.3 micrograms and 1.8 +/- 0.3 micrograms versus 2.4 +/- 1.3 micrograms and 0.8 +/- 0.3 mg) were recovered from uterine flushings from ewes in the SHORT versus LONG groups, respectively. The ratio of PGE2:PGF2 alpha was higher (p less than 0.06) in flushings from ewes in the SHORT versus LONG group (1.4 +/- 0.2 versus 0.9 +/- 0.2, respectively). Conceptuses were classified by stage of morphological development. Conceptus development was accelerated (p less than 0.01) in ewes of the SHORT group, as shown by filamentous conceptuses recovered from 78% versus 0% of SHORT versus LONG ewes, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Insulin-like growth factors in sheep uterine fluids: concentrations and relationship to ovine trophoblast protein-1 production during early pregnancy.

Uterine luminal fluids (ULFs) from Days 10, 12, 14, and 16 cyclic (C) and pregnant (Px) ewes were analyzed for presence of insulin-like growth factors (IGF-I, IGF-II) and other mitogenic factor(s). IGF content and non-IGF mitogenic activity were measured by IGF RIAs after removal of IGF binding proteins and by stimulatory effects on DNA synthesis of density arrested AKR-2B cells, respectively. ULF IGF-I content was not different between days, but differences in IGF-I between C and Px groups at Day 16 (C greater than Px) were found (p less than 0.05). ULF IGF-II content was not different between C and Px ewes; however, differences among days (p less than 0.01) were apparent. In both C and Px ewes, Day 14 ULF had highest IGF-II content (C: 4.60 +/- 0.98 ng/ml, Px: 5.39 +/- 1.38 ng/ml). In Day 12 and Day 14 (C and Px) ULF, IGF-II concentration was about 10-fold greater than that of IGF-I. AKR-2B mitogenic activity in ULF differed among days (p less than 0.01), but not between C and Px ewes. Highest activity was observed for Day 14 and Px ULF, whereas lowest activity was for Day 10 C and Day 16 Px ULF. Sephadex G-200 gel-filtration chromatography of ULF from Day 14 Px ewes demonstrated mitogenic activity in the column void volume fractions and in the 30-kDa size range of eluted proteins. Day 13 conceptuses were cultured in serum-free medium to define the effect of exogenous IGFs on ovine trophoblast protein-1 (oTP-1) secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Expression of messenger RNAs encoding insulin-like growth factor-I, -II, and insulin-like growth factor binding protein-2 in bovine endometrium during the estrous cycle and early pregnancy.

The present study characterized the changes in concentrations of insulin-like growth factors-I and -II (IGF-I and IGF-II) in uterine luminal flushings, and the endometrial mRNA levels of IGF-I, IGF-II, and IGF binding protein-2 (IGFBP-2) obtained from Days 0 through 18 of the bovine estrous cycle and early pregnancy. Concentrations of IGF-I and IGF-II in uterine flushings were greater on Days 0 and 5 than on other days of the estrous cycle or pregnancy. Northern blot analysis of endometrial poly(A)+ RNA revealed two major transcripts of 7.5 and 1.0 Kb for IGF-I, one major transcript of 4.0 Kb for IGF-II, and one major transcript of 1.3 Kb for IGFBP-2. RNA dot-blot analyses indicated that endometrial expression of IGF-I mRNA was unaffected by day of the estrous cycle or status (cyclic vs. pregnancy). However, endometrial expression of IGF-II mRNA was greater in pregnant than in cyclic endometrium on Days 15 and 18. Levels of endometrial IGFBP-2 mRNA increased (p less than 0.05) between Days 10 and 18 of the estrous cycle and early pregnancy. Results suggest that the presence of the bovine conceptus has a stimulatory effect on endometrial expression levels of IGF-II, whereas progesterone appears to be involved with enhancement of IGFBP-2.

Animals↗

PubMed1991

Type I conceptus interferons: maternal recognition of pregnancy signals and potential therapeutic agents.

In summary, Type I conceptus interferons of sheep, cows, and goats (perhaps all ruminants), which signal maternal recognition of pregnancy, may be useful for enhancing fertility in animal agriculture and may have a role in human and veterinary medicine as well. The Type I conceptus interferons share antiviral, anticellular, and immunosuppressive properties with Type I leukocyte interferons, but lack their cytotoxic effects, which may make them especially useful as therapeutic agents in human and veterinary medicine. The unique N-terminal structure of oTP-1 may account for its distinctive biological properties, including its antiluteolytic activity.

Animals↗

PubMed1991

Comparative aspects of conceptus signals for maternal recognition of pregnancy.

Maintenance of corpus luteum (CL) function is essential for establishment of pregnancy in mammals. Estrogens from pig conceptuses (embryo and associated membranes) initiate events that, with prolactin, redirect secretion of the uterine luteolytic hormone prostaglandin F2 alpha (PGF) from an endocrine (to uterine veins) to an exocrine (to uterine lumen) direction to prevent luteolysis. Ovine conceptuses secrete ovine trophoblast protein-1 (oTP-1), which exhibits high amino acid sequence relatedness with alpha II interferons (IFN alpha II) and inhibits synthesis of endometrial receptors for oxytocin and uterine production of luteolytic pulses of PGF. Estrogens and oTP-1 are local antiluteolytic signals to endometrium, whereas human chorionic gonadotrophin (hCG) appears to have a direct luteotrophic effect on CL. A progestational endometrium secretes proteins that serve as growth factors, transport proteins, regulatory proteins and enzymes, as well as transporting nutrients into the uterine lumen to support conceptus development.

Animals↗

PubMed1991

Immunoreactive methionine-enkephalin secretion by porcine uterus.

The current study examined the presence of immunoreactive methionine-enkephalin (ir-MENK) in porcine uterine fluid and endometrial extracts, characterized ir-MENK biochemically, and investigated the effect of ovarian steroids on uterine secretion of ir-MENK. Porcine uterine fluid was collected by flushing the uterine lumen with saline. Endometrial tissues were extracted with acetic acid. Both uterine fluid and endometrial extracts exhibited inhibition curves parallel to that of authentic MENK in the MENK RIA system. Sephadex G-15 gel filtration chromatographic profiles indicated that both concentrated uterine fluid and endometrial extracts contained two peaks of ir-MENK, a major peak which coeluted with standard MENK, and a minor peak eluting near the void volume (Vo). Reverse phase-HPLC chromatographic profiles also demonstrated two peaks of ir-MENK for concentrated uterine fluid and endometrial extracts, a major peak which coincided with standard MENK, plus a highly hydrophilic peak. The effect of ovarian steroids on the uterine secretion of ir-MENK was examined by measuring ir-MENK in uterine fluids from cyclic and pregnant gilts as well as ovariectomized, ovarian steroid-treated gilts. Day effects (P less than 0.01) were detected for cyclic and pregnant gilts, since values for ir-MENK increased between days 8 and 14 after onset of estrus. In ovariectomized gilts, treatment with progesterone (P4) increased the uterine secretion of ir-MENK (202 +/- 9 vs. 65 +/- 4 pg/ml for control, P less than 0.05). The combined treatment of P4 and estradiol did not further enhance secretion of ir-MENK, while treatment with estradiol did not alter ir-MENK levels relative to values for control gilts. These results indicate the presence of ir-MENK in porcine uterine fluid and endometrium, and suggest that uterine secretion of ir-MENK is regulated primarily by P4.

Animals↗

PubMed1991

Ontogeny of insulin-like growth factors (IGF-I and IGF-II) and IGF-binding proteins in porcine serum during fetal and postnatal development.

The insulin-like growth factors (IGF-I and IGF-II) circulate in plasma in association with IGF-binding proteins (IGFBPs). As a first step to understanding the regulation of expression of these proteins in pigs, we characterized the ontogeny of circulating IGFs and IGFBPs during fetal and early postnatal development. Serum IGFs were separated from IGFBPs, before IGF RIA, by acidification and chromatography on C18 Sep-Pak cartridges. The IGF-I levels increased during the latter half of fetal life from 11 +/- 1 ng/ml on day 60 to 37 +/- 3 ng/ml on day 112 (2-3 days before term) and further increased postnatally to 227 +/- 21 to 265 +/- 26 ng/ml) and also increased higher than IGF-I levels, with no obvious developmental pattern, during fetal life (170 +/- 21 to 265 +/- 26 ng/ml) and also increased postnatally by 2-fold (463 +/- 29 ng/ml on day 42). These results support the view that IGF-II is a fetal and postnatal growth factor, whereas IGF-I is primarily a postnatal growth mediator in pigs. Serum IGF-binding proteins were identified by Western ligand blotting. Five IGFBPs with apparent mol wt of 43K, 39K, 34K, 31K, and 26K were detected in fetal and postnatal sera. The two largest proteins were shown to be glycoproteins and immunologically related to porcine (p) IGFBP-3, suggesting that they are glycosylation variants of pIGFBP-3. The abundance of these two IGFBPs increased coincidently with increasing serum IGF-I levels. The 34K IGFBP was immunologically related to rIGFBP-2 and was 2- to 3-fold more abundant in fetal serum than in postnatal serum. The 31K IGFBP was resolved into a triplet and also was a component of pIGFBP-3 immunoprecipitates. Similarly, the 26K IGFBP was present in pIGFBP-3 immunoprecipitates. The 31K and 26K IGFBPs represented a minor portion of serum IGF-binding activity in fetal and postnatal pigs and exhibited no obvious developmental patterns. It is hypothesized that the postnatal increases in serum IGF-I and 43K and 39K IGFBPs as well as the decrease in the 34K IGFBP are driven by GH action.

Animals↗

PubMed1991

In vitro synthesis of oviductal proteins associated with estrus and 17 beta-estradiol-treated ovariectomized ewes.

The objectives of this study were: 1) to identify and characterize ewe oviductal secretory proteins (OSP) de novo synthesized during the estrous cycle; 2) to examine the effect of estrogen (E) and progesterone (P) on synthesis of OSP; and 3) to determine synthesis of OSP by ampulla (A) and isthmus (I). Oviducts were collected from cyclic ewes on days 1, 8, and 16 and ovariectomized (OVX) ewes after treatment with corn oil (CO), E, P, and E + P. Tissue was incubated in the presence of 3H-leucine or 3H-glucosamine. Rates of 3H-leucine incorporation into nondialyzable macromolecules by explants was greater (P less than 0.05) on day 1 than days 8 and 16, greater (P = 0.01) in OVX E-treated ewes, greater in A than I regardless of treatment and greater (P less than 0.05) in A than I with E. Culture medium was analyzed by one- and two-dimensional polyacrylamide gel electrophoresis and fluorography. Two major basic proteins (Mr 90-92,000) and three minor proteins were only present on day 1 of estrus. E treatment demonstrated these same proteins which were not found with CO or P treatment. Two-dimensional analysis of medium from A and I cultured separately indicated that A synthesized the two major basic and three minor E-dependent proteins. Of three protein complexes present regardless of treatment or cycle day, two were dominant in the A and one was dominant in the I suggesting a synthetic gradient. Tunicamycin did not inhibit incorporation of 3H-glucosamine into E-dependent proteins. Gel filtration revealed a high Mr fraction (2 x 10(6] 2.5-fold greater on day 1 than day 8 and 2.2-fold greater with E than CO treatment. This study clearly demonstrates: 1) that the oviduct from estrus and E-treated ewes synthesizes two major basic and three minor glycoproteins not detectable on other cycle days or with OVX or P treatment; 2) the E-dependent glycoproteins are synthesized by the A; and 3) a high Mr fraction is induced or amplified by E.

Animals↗

PubMed1991

Regulation of the uteroferrin gene promoter in endometrial cells: interactions among estrogen, progesterone, and prolactin.

Expression of the gene for the porcine transplacental iron transport protein uteroferrin (UF) is largely restricted to the uterus, where it is differentially regulated by estrogen (E) and progesterone (P). To study the regulatory mechanisms subserving these effects, a 2-kilobase genomic fragment corresponding to -2005 to 48 nucleotides of the UF gene was ligated up-stream to the reporter gene chloramphenicol acetyltransferase (CAT). This construct (UF-CAT) was transiently transfected into rabbit endometrial (HRE-H9), mouse fibroblastic (AKR-2B), and human choriocarcinoma (JEG-3) cells. The basal gene promoter activity of UF-CAT was exhibited in H9 cells, but not in AKR-2B or JEG-3 cells. In contrast, a simian virus-40 early promoter (SV2) was functional in all three cell lines. The H9 cells were used to examine steroid regulation of the UF gene promoter. The CAT expression in H9 cells primed with E and PRL, but not with E or PRL alone, was stimulated by P. In contrast, basal activity of SV2 in these cells was unaffected by hormones, singly or in combination. To examine the basis for the E/PRL-dependent response to P, levels of P and E receptors in H9 cells were quantified. PRL and E plus PRL increased the number of high affinity sites for P, but had little effect on levels of high affinity sites for E in treated vs. untreated H9 cells. In vivo administration of PRL to cyclic gilts had no effect on levels of endometrial UF mRNA and secreted UF protein; however, E- plus PRL-treated gilts had higher (P less than 0.05) levels of endometrial UF mRNA and luminal UF than PRL-treated gilts. These results demonstrate in vitro functional activity of the UF gene promoter and associated 5' flanking region and suggest that sequences within this region may mediate tissue-specific and steroid hormone-regulated expression of the UF gene. Moreover, interactions among E, PRL, and P modulate UF gene expression in vivo and in vitro.

Acid Phosphatase↗

PubMed1991

Production of two species of interferon by Large White and Meishan pig conceptuses during the peri-attachment period.

Antiviral activities present in uterine flushings from pregnant Large White, Large White 'hyperprolific', and prolific Meishan gilts, between Days 8 and 20 of gestation were compared. Flushings (20 ml) from all gilts between Days 14 and 20 were positive in an in-vitro interferon (IFN) assay using vesicular stomatitis virus as a challenge infection. Highest antiviral activities (of up to 400,000-1,200,000 total Units/flushing) were obtained at Day 16 of gestation, i.e. clearly after the beginning of attachment. There was no major difference between breeds although, at Day 14, flushings from Meishan gilts yielded significantly higher titres than those from the other two, suggesting a correlation with the previously described earlier trophoblast elongation in Meishan gilts. Conceptus cultures contained antiviral activity, with values very close to those obtained in vivo, but the difference between breeds was not significant. Cultures from Day 20 on contained very little antiviral activity. The antiviral activity was associated with a mixture of at least two IFNs, one of which was IFN-alpha like, and the other was serologically identified as an IFN-gamma, that is an 'immune IFN', previously found to be secreted only by T lymphocytes. This finding may have implications for our understanding of the immunology of early pregnancy.

Animals↗

PubMed1991

Stimulation of 2',5'-oligoadenylate synthetase activity in sheep endometrium during pregnancy, by intrauterine infusion of ovine trophoblast protein-1, and by intramuscular administration of recombinant bovine interferon-alpha I1.

In Expt 1, activity of 2',5'-oligoadenylate (2',5'-A) synthetase in endometrium collected on Day 16 (oestrus is Day 0) from the uterine horn ipsilateral to the corpus luteum was greater (P less than 0.001) for pregnant (135.5 +/- 1.72 nmol/mg protein/h) than for cyclic ewes (58.5 +/- 0.99 nmol/mg protein/h). In pregnant ewes, activity of 2',5'-A synthetase in endometrium collected from the contralateral uterine horn (119.5 +/- 1.72 nmol/mg protein/h) did not differ from that of the ipsilateral horn. In Expt 2, three ovariectomized ewes were treated with progesterone for 10 days and then with oestrogen for 2 days. Activity of 2',5'-A synthetase on Day 13 was 18% greater (P less than 0.10) in endometrium collected from the uterine horn receiving infusions of 30 micrograms ovine trophoblast protein-1 (oTP-1) twice a day on Days 10, 11 and 12(57.7 +/- 0.22 nmol/mg protein/h) than from the uterine horn receiving control infusions of serum protein (SP; 48.8 +/- 0.22 nmol/mg protein/h). In Expt 3, activity of 2',5'-A synthetase on Day 15 was not significantly greater in endometrium collected from the uterine horn of cyclic ewes receiving infusions of 30 micrograms oTP-1 twice a day on Days 12, 13 and 14 (46.5 +/- 0.37 nmol/mg protein/h) than in endometrium from the uterine horn receiving infusions of SP (38.2 +/- 0.37 nmol/mg protein/h). When results of Expt 2 and Expt 3 were combined, intrauterine infusion of oTP-1 increased (P less than 0.05) activity of 2',5'-A synthetase in endometrium by 20%.(ABSTRACT TRUNCATED AT 250 WORDS)

2',5'-Oligoadenylate Synthetase↗

PubMed1991

Effects of insulin-like growth factor-I on aromatase cytochrome P450 activity and oestradiol biosynthesis in preimplantation porcine conceptuses in vitro.

The effects of insulin-like growth factor-I (IGF-I) on aromatase P450 activity and steroid production in preimplantation pig conceptuses were evaluated in vitro. Conceptuses recovered from gilts on days 10 and 12 of pregnancy were incubated for 6 h in modified Eagle's Minimum Essential Medium (MEM) plus IGF-I (0.1 microgram/ml) or insulin (8.5 micrograms/ml), and conceptuses were monitored for their ability to convert [1,2-3H]beta-testosterone into oestrogens. Aromatase activity of day-10 conceptuses was low and unaffected by IGF-I or insulin. In contrast, basal aromatase activity in day-12 conceptuses was about threefold higher and was further increased by IGF-I (P less than 0.02), but was unaffected by insulin. To determine whether higher aromatase P450 activity was associated with increased oestradiol production, concentrations of oestradiol were determined by radioimmunoassay in culture medium of day-11 and -12 conceptuses, after incubation in MEM alone or in the presence of dehydroepiandrosterone (DHA, 1 microgram/ml) with or without IGF-I (0.1 microgram/ml) or insulin (0.1 or 8.5 micrograms/ml) for 24 h. Conceptuses in MEM plus DHA produced more oestradiol (P less than 0.01) than those in MEM alone. Addition of IGF-I or insulin did not increase the effect of DHA. Basal oestradiol production was dependent on conceptuses size; however, IGF-I or insulin did not affect basal or DHA-stimulated oestradiol production regardless of conceptus size. These findings demonstrate that IGF-I can modulate aromatase activity in vitro, without affecting overall de-novo steroidogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Ontogeny of hepatic bovine growth hormone receptors in cattle.

A series of studies examined the binding characteristics and ontogeny of hepatic growth hormone binding sites in dairy bulls on d 2, 30, 180, and 365 of age. Binding of iodinated recombinant bovine growth hormone ([125I]rbGH) to liver membrane receptors was membrane protein-dependent. Receptors were considered growth hormone-specific, because physiological concentrations of bovine prolactin (bPRL) failed to displace [125I]rbGH from bovine hepatocyte membranes. Only 50% of [125I]rbGH was bound reversibly to hepatic microsomes. Addition of dithiothreitol (DTT) to the receptor-assay buffer increased the binding of [125I]rbGH to hepatic membranes in a time-dependent manner. Moderate concentrations of Ca++ and Mg++ in the receptor-assay buffer had no detectable effects on binding of [125I]rbGH to hepatic microsomes. In growing dairy bulls, specific binding of [125I]rbGH per milligram of membrane protein increased from 1.9 +/- 1.8% at d 2 to 14.1 +/- 1.8% at d 180 and then declined to 5.2 +/- 1.6% at d 365. Likewise, concentration of insulin-like growth factor (IGF)-I in serum was low during the 1st mo of age (d 2, 13.3 +/- 8.8 ng/ml; d 30, 9.7 +/- 8.8 ng/ml), but it became maximal at d 180 (151.0 +/- 8.8 ng/ml). Circulating concentrations of IGF-II increased linearly during the 1st yr of growth. Serum concentrations of GH, triiodothyronine, and thyroxine declined from 39.9 +/- 6.5, 2.7 +/- .2, and 75.4 +/- 4.6 ng/ml at d 2 to 16.5 +/- 6.5, 1.3 +/- .2, and 53.4 +/- 4.6 ng/ml at d 30, respectively, and remained low through 1 yr of age. Insulin concentration in serum did not change significantly with development. Results indicated that increasing concentrations of specific bGH receptors in the bovine liver may play a key role in regulating postnatal growth in cattle.

Aging↗

PubMed1991

Physiological mechanisms of pregnancy recognition in ruminants.

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 absent for ewes, cows and goats. Exogenous oestrogens can, through a uterine-dependent mechanism, stimulate synthesis of endometrial receptors for oxytocin and uterine production of PGF-2 alpha; an effect which is significantly attenuated during early pregnancy. These results suggest that oTP-1, bTP-1 and possibly cTP-1 exert their antiluteolytic effect(s) by: (1) inhibiting effects of oestrogen and/or progesterone necessary for synthesis of endometrial receptors for oxytocin; (2) inhibiting endometrial synthesis and/or recycling of oxytocin receptors directly; or (3) inducing the endometrium to synthesize an inhibitor of an enzyme(s) necessary for synthesis of PGF-2 alpha.

Animals↗

PubMed1991

Uteroferrin: a progesterone-induced hematopoietic growth factor of uterine origin.

Uteroferrin is a purple progesterone-induced glycoprotein containing two molecules of iron per 35,000 molecular weight polypeptide, which has high amino acid sequence homology with Type 5 acid phosphatases from normal human placentae, from sera of patients with hairy cell leukemia, Gaucher's disease, and osteoporosis, as well as from normal spleens of pigs, cattle, rats, and mice. Results of the present study indicate that uteroferrin also has colony-forming unit (CFU) activity for committed erythroid (BFU-E) and granulocyte-monocyte/macrophage (CFU-GM) cell lines and exists as far back as the granulocyte, erythrocyte, monocyte/macrophage, megakaryocyte (CFU-GEMM) committed lineage. Uteroferrin exerts maximum CFU activities at 1 microgram/ml in serum-free culture medium with no supplemental iron (90 micrograms/ml ferric iron). However, when ferric iron concentration in medium was increased to 200 micrograms/ml, uteroferrin had maximum CFU activities at 100 pg/ml. Preincubation of uteroferrin with polyclonal antiserum or monoclonal antibody to uteroferrin effectively eliminated its CFU activities. Uteroferrin derived from human term placentae also exhibits BFU-E, CFU-GM, and CFU-GEMM activities. The mechanism by which uteroferrin stimulates proliferation and differentiation of primitive hematopoietic stem cells is unclear.

Acid Phosphatase↗