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Biomedical subjects

F W Bazer

Publications and source records attributed to F W Bazer.

At least 253 records · Page 14Linked to original sources
PubMed1984

H1 histone synthesis by implanting pig blastocysts.

Histones were isolated from pig conceptuses on Days 8-18 of pregnancy, Acid-urea polyacrylamide gel electrophoresis (PAGE) was performed on samples of total histone and on PCA-soluble histone fractions (primarily histone H1). Conceptuses were also incubated for 24 h in vitro in the presence of [3H]lysine, and the histones analysed by autofluorography after PAGE. A minimum of two H1 histone bands was resolved in stained gels by these techniques. The autofluorographs indicate that both H1 histones are synthesized throughout the developmental period analysed. No shift in H1 histone subtype, as encountered in sea urchin development, was observed. The results suggest that such a shift, if it occurs, may have been made before Day 8.

Animals↗
PubMed1984

Adaptations to reduction of endometrial surface available for placental development in sheep.

On Day 5 of pregnancy, before the blastocyst migrates to the uterus, one uterine horn was ligated to restrict the trophoblast to the lumen ipsilateral to the corpus luteum. The numbers of placentomes (caruncles and cotyledons) were reduced by half, but neither at 120 nor at 140 days of pregnancy (term 147 days) did the weights of placentae and fetuses of treated ewes differ significantly from those of control ewes. Amongst uterus-ligated animals prepared for chronic study, the rate of uterine blood flow (electromagnetic flow transducer, ml/min) to the pregnant horn was higher than in control ewes, as was the concentration of progestagens in maternal peripheral blood. There may be a compensatory response that causes hypertrophy of placentomes and that increases blood flow to the uterine horn containing placental tissue.

Adaptation, Physiological↗
PubMed1984

Acid phosphatase and leucine aminopeptidase activity in the uterine flushings of non-pregnant and pregnant gilts.

The activities of uteroferrin, measured as acid phosphatase (AP), and an aminoacylpeptidase (AA) were measured in uterine flushings collected from gilts on Days 6, 8, 10, 12, 14, 15, 16 and 18 of the oestrous cycle and pregnancy (N = 37). Changes in AP (P less than 0.05) were associated with day for both specific and total AP in non-pregnant and pregnant gilts. For pregnant and non-pregnant gilts, AP activity was greatest between Days 14 and 16 and then decreased to Day 18. The AA specific activity increased (P less than 0.01) between Days 10 and 12 of the oestrous cycle and pregnancy, but neither effects of pregnancy nor day by pregnancy status interaction were detected. The AA total activity was greater for pregnant gilts (P less than 0.01). These data suggest an inhibitory effect of oestrogens of blastocyst origin on synthesis and/or secretion of uteroferrin, but not AA.

Acid Phosphatase↗
PubMed1984

Yield and composition of milk and weight gain of nursing pigs from sows fed diets containing fructose or dextrose.

Yield and composition of milk and growth of nursing pigs in response to dietary treatment were estimated from 25 lactating sows during a 22-d period. Eight sows were fed 6 kg/d of a corn-soybean control diet (C sows). Nine were fed the control diet in which approximately 6.5 g X kg body weight (BW-1) X d-1 of carbohydrate was supplied by fructose corn syrup (F sows) and eight were fed the control diet containing equivalent carbohydrate supplied by powdered dextrose (D sows). Blood samples collected via jugular cannulae were analyzed for plasma concentrations of fructose, glucose and insulin. Concentrations of fructose and glucose from F sows were significantly higher throughout the study than that from D and C sows, while insulin concentration was approximately 2.5-fold lower. Milk yield from F sows on d 14 and 21 was significantly higher and pigs weaned on d 21 were heavier than those from D and C sows. Sows fed the diet containing fructose experienced significant BW loss during lactation. Coefficients of gross correlation across treatments showed milk yield and litter weight gain to be negatively associated with percentages of protein, lipids and total solids in milk, but positively associated with concentrations of lactose and gross energy. Nursing pig weight gain at weaning was more responsive to total yields of milk and milk nutrients than to composition. These data support the hypothesis that source of metabolizable energy (ME) affects milk yield, composition and efficiency at which the sow converts dietary nutrients into milk.

Animal Population Groups↗
PubMed1984

Role of uteroferrin in placental iron transport: effect of maternal iron treatment on fetal iron and uteroferrin content and neonatal hemoglobin.

Uteroferrin, an Fe-containing, progesterone-induced glycoprotein is involved in maternal to fetal Fe transport in swine. These studies examined the effect of im Fe injection of dam on conceptus and piglet Fe stores. In Exp. I, eight gilts were bred and assigned to either treatment I (no Fe injections) or treatment II (total of 22 mg iron-dextran/kg body weight on d 40, 45, 50, 55 and 60 of gestation) and hysterectomized on d 90 to determine whether Fe injections increased Fe stores in the conceptus. Total Fe in allantoic fluid (P less than .10) as well as uteroferrin concentration (P less than .05) and total uteroferrin (P less than .05) in placentae were greater for gilts in treatment II. In Exp. II, 19 cross-bred sows were bred and assigned to treatments I and II (d 40, 50 and 60 of gestation), as in Exp. I, and treatment III (total of 22 mg iron-dextran/kg body weight on d 90, 100 and 110 of gestation) to determine effects of treatment on hemoglobin (Hb) values of the piglets at 8 +/- 1 h and d 4 postpartum. Piglets from treatment II had higher (P less than .01) Hb at 8 +/- 1 h, but not on d 4 postpartum. Experiment III was a replication of Exp. II except that Hb values were determined at 8 +/- 1 h, d 4 and d 7 postpartum. On d 7, piglets from treatment II had higher (P less than .05) Hb, but differences at 8 +/- 1 h and d 4 were not significant (P greater than .10).(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗
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

Biochemical aspects of conceptus--endometrial interactions.

Mammalian conceptuses must provide a chemical signal to the maternal system to insure maintenance of corpus luteum (CL) function and of progesterone production and continuation of uterine endometrial secretory activity. These events insure that the developing conceptus is provided with appropriate nutrients, regulatory enzymes and endocrine state to allow successful establishment and maintenance of pregnancy. Pig blastocysts begin to produce estrogens by Day 11 of pregnancy, which prevents secretion of the uterine luteolytic factor (PGF2 alpha) in an endocrine direction, but allows secretion in an exocrine direction, i.e., into the uterine lumen. Therefore, CL are "protected." Blastocyst estrogens also trigger secretion of a group of proteins, including uteroferrin, an iron transport protein, and a family of protease inhibitors whose biosynthesis within the uterine glandular epithelium is under the control of progesterone. Estrogen also appears to promote accumulation of glucose and fructose within the uterine lumen. A complex in vivo "culture medium" is thereby established to promote conceptus development. Pig blastocysts do not undergo invasive implantation within the uterine lumen although they produce the protease, plasminogen activator. Invasion may be prevented by endometrial secretion of progesterone-induced protease inhibitors which are produced in large amounts. In addition to estrogens of conceptus origin, calcium and prostaglandins PGF2 alpha and E2 may affect the uterine vasculature, water and electrolyte transport, capillary permeability, conceptus steroid production, and related events during pregnancy. The blastocysts of the large domestic animals also secrete proteins which include a large glycoprotein (Mr approximately 600,000) and a small acidic protein (Mr approximately 17,000). The latter has been purified from sheep and named ovine trophoblast protein I. These proteins may play unique roles in early pregnancy with respect to establishment and maintenance of pregnancy in the ewe, sow, mare, and cow.

Animals↗
PubMed1983

Relationship between release of plasminogen activator and estrogen by blastocysts and secretion of plasmin inhibitor by uterine endometrium in the pregnant pig.

Pig blastocysts isolated between Days 10 and 16 of pregnancy release the protease, plasminogen activator (PA), into the medium in a time-dependent manner when cultured in vitro. Production is biphasic. The initial phase (Days 10-12) coincides with the early elongation stages, while release during the second phase (Days 14-16) occurs during a time at which the DNA content of the blastocysts is increasing markedly. Uterine flushings from these pregnant animals contain the zymogen substrate for PA, plasminogen, presumably as a serum transudate. Plasminogen is present in highest amounts at Day 12. The blastocyst, therefore, has the potential ability to generate the broadly specific protease, plasmin, within the uterine lumen. However, during this same period, the endometrium secretes an inhibitor of plasmin into the uterine lumen. In pregnant animals the amount of plasmin inhibitory activity rose 7-fold between Day 10.5, when the blastocysts were spherical, and Day 12, when they had become filamentous. At Day 12 each uterine horn contained about 3 to 4 mg of plasmin inhibitor. A similar release of inhibitor can be initiated in nonpregnant gilts given a single, intramuscular injection of estradiol valerate on Day 11 of the estrous cycle. It is suggested that the initiation of estrogen production by the elongating blastocyst triggers the release of plasmin inhibitor by the maternal endometrium and that the inhibitor serves to prevent a proteolytic cascade of reactions initiated by blastocyst PA, which might otherwise damage the uterine epithelium.

Animals↗
PubMed1983

Uterine blood flow: periodic fluctuations of its rate during pregnancy.

Daily measurements of the rate of uterine blood flow (ml/min) during the last half of pregnancy of four normal sheep reflected a 17-day cyclic fluctuation (range, 9.5-42 days) superimposed on a linear increase over time. The cyclic increase was not detected in two (of 7) intact ewes or in four pregnant ewes that had been ovariectomized. The cyclic pattern of increase may be related to ovarian activity.

Animals↗
PubMed1983

Pregnancy and parturition.

The establishment and maintenance of pregnancy in domestic animals requires interactions between the developing conceptus and the maternal system. These interactions are essential for maintenance of the corpora lutea (CL), conceptus development and placentation, regulation of uterine endometrial secretory activity, placental transport of nutrients and gases, regulation of uterine blood flow, achievement of immunological "privilege" for the conceptus, stimulation of development of the maternal mammary glands and various other effects on the physiology and endocrinology of the maternal and conceptus systems. Interactions between the conceptus and maternal systems are also responsible for initiating parturition. All of these events are discussed, on a comparative basis, with respect to current knowledge obtained from studies of domestic farm animals and, where appropriate, data from laboratory species.

Animals↗
PubMed1983

A function of the allantoic sac in the metabolism of uteroferrin and maternal iron by the fetal pig.

The possible roles of the allantoic sac in metabolism of uteroferrin, the iron-containing, purple phosphatase, were examined. This protein, which originates in the maternal endometrium, was measured in allantoic fluid by a specific double-antibody radioimmunoassay and by its beta-mercaptoethanol-activated acid phosphatase activity. Total uteroferrin reaches a maximum between days 60 and 75 of pregnancy, when it constitutes up to one-third of the total protein, and then declines towards term. Fluid volume, total protein and total iron also reach a maximum around day 60. Two-dimensional polyacrylamide-gel electrophoresis was employed to identify proteins in allantoic fluid. Of the proteins detected, at least three basic and two acidic polypeptides are also characteristic of maternal uterine secretions. The remaining proteins appeared identical to those found in fetal serum and included transferrin, albumin and alpha-fetoprotein. Although uteroferrin acid phosphatase activity is stable when incubated in buffer, the enzyme loses activity in sterile allantoic fluid collected at all stages of pregnancy. Experiments with 59Fe-uteroferrin have shown that allantoic fluid promotes iron loss from uteroferrin and that the metal appears in transferrin. Thus the allantoic sac may serve not only as a depot for uteroferrin accumulation but as a site of active iron metabolism.

Acid Phosphatase↗
PubMed1982

Purification and properties of a progesterone-induced plasmin/trypsin inhibitor from uterine secretions of pigs and its immunocytochemical localization in the pregnant uterus.

The porcine uterus secretes a group of basic, low molecular weight protease inhibitors under the influence of progesterone, but not estrogen. One of these inhibitors (Mr approximately 14,500) which inhibits trypsin, plasmin, and chymotrypsin, but not other proteases tested, has been purified 10- to 15-fold from uterine secretions of pseudopregnant pigs using Sephadex G-100 chromatography, CM-cellulose ion exchange chromatography, and Sephadex G-50 or Bio-Gel P-10 chromatography. The inhibitor which is relatively heat- and pH-stable forms a 1:1 molar complex with trypsin which is not dissociated in sodium dodecyl sulfate except by boiling. Chymotrypsin appears to bind at the same site on the inhibitor as trypsin. The inhibitor is high in half-cysteine residues and basic amino acids, and appears not to be a glycoprotein. Antiserum has been raised against the purified inhibitor in rabbits and used to test its distribution in pigs using the immunoperoxidase-staining technique on tissue sections. The inhibitor is associated only with the glandular and surface epithelium of the uterus. Endometrial explants from pseudopregnant animals, cultured in presence of L-[3H]leucine, release the inhibitor in radioactive form indicating that it is a uterine product. The antiserum against the inhibitor cross-reacts with at least three other, basic, low molecular weights plasmin/trypsin inhibitors in porcine uterine secretions, suggesting that a family of isoinhibitors exists which may constitute up to 15% of the protein in porcine uterine secretions. The inhibitor(s) appears to coat and to be taken up by the trophoectoderm cells of the elongating blastocyst during pregnancy. It is suggested that the inhibitors may serve to protect the uterus from proteases released by the porcine trophoblast or to prevent degradation of essential macromolecules, such as uteroferrin, which have to be taken up by the conceptus.

Animals↗
PubMed1982

Iron transfer between the purple phosphatase uteroferrin and transferrin and its possible role in iron metabolism of the fetal pig.

Uteroferrin, a purple-colored, iron-containing phosphatase which is induced by progesterone in the porcine uterus, has been proposed to be an intermediary in iron transfer between the mother and conceptus in the pig. Along with a number of other uterine proteins of maternal origin, it accumulates in the allantoic fluid during mid-pregnancy. When [59Fe]uteroferrin was introduced into the allantoic sacs of five fetuses at Day 60 of pregnancy, its iron was transferred to another protein, identified as transferrin. The half-life of iron loss from uteroferrin was approximately 24 h and the kinetics suggested an approximately second order process. 59Fe was also distributed to the fetus and was recovered at high specific activity in the fetal red blood cells (as hemoglobin), liver, and spleen. Introduction of [59Fe] transferrin to allantoic fluid resulted in an almost identical distribution of isotope in the fetus as was observed with [59Fe]uteroferrin. Whereas [125I]transferrin has been shown to be capable of leaving the allantoic sac in intact form, [125I]uteroferrin either has only a limited capacity to exit or else is almost immediately degraded upon entering the fetal circulation. Following loss of its iron to transferrin in allantoic fluid, uteroferrin rapidly loses immunological reactivity and is cleaved proteolytically into small peptides. The transfer of iron between uteroferrin and transferrin has also been followed in vitro. Iron on uteroferrin is relatively stable to pH and is not readily lost to transferrin at around neutral pH unless low molecular iron chelators such as citrate, pyrophosphate, ATP, or ascorbate are present. Iron transfer was promoted at ascorbate concentrations (approximately 50 microM) and at pH values (approximately 6.8) approximating those found in allantoic fluid. Results are consistent with a model in which maternal uteroferrin can transfer its iron to fetal transferrin via a low molecular weight intermediary in the allantoic sac. Transferrin is then responsible for iron distribution to the fetus.

Acid Phosphatase↗
PubMed1982

Iron content and molecular weight of uteroferrin and a comparison of its iron and copper forms.

The molecular weight of the purple, iron-containing glycoprotein uteroferrin has been determined to be 35140 +/- 1610 by sedimentation equilibrium centrifugation. This is consistent with measurements carried out by other procedures. The dry weight of a solution of uteroferrin with an absorption of 1.00 cm -1 at 280 nm was 0.87 mg/ml. Highly purified uteroferrin has a ratio of absorbance at 280 nm to 545 nm of about 13.2 and a revised extinction coefficient at 545 nm of 3.1 . 10(3) M -1 is presented. The iron content of uteroferrin has been determined both colorimetrically and by atomic absorption spectroscopy. One iron atom is present per polypeptide chain. Reduction with dithionite leads to loss of iron, allowing the apoprotein to be prepared. Enzymatic activity can be restored to the apoprotein with Fe(III) or with Cu(II). The copper enzyme has no visible color and has a higher pH optimum than the Fe-uteroferrin. Whereas the phosphatase activity of the latter is increased several-fold by beta-mercaptoethanol, reduction inactivates Cu-uteroferrin. Both forms of uteroferrin have similar Km values for p--nitrophenyl phosphate and are inhibited by molybdate but not by tartrate. Excess Cu(II) and Fe(III) strongly inhibit uteroferrin phosphatase activity and these results may explain the failure of other to restore activity to the apoprotein using Cu(II) and Fe(III) salts.

Acid Phosphatase↗
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↗