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R M Roberts

Publications and source records attributed to R M Roberts.

At least 181 records · Page 10Linked to original sources
PubMed1986

The vaginal mucus agglutination test in the diagnosis of bovine brucellosis.

Of 1140 vaginal mucus agglutination tests (VMAT) on specimens obtained in 1971-72 from 663 dairy cows in seven herds infected with brucellosis, 97 were positive. When the VMAT was positive one or more serological tests were also positive. Of the 97 corresponding serum agglutination tests 80 sera had titres of more than 533 international units. Only 69.8 per cent of VMAT from serologically positive cows were positive. No evidence was found of non-specific agglutinins in vaginal mucus and positive VMAT reactions appeared to be specific for field infection. Three cows showed evidence of local agglutinins in the vagina. Hence herd testing by VMAT has no advantage over tests of blood serum but the test could be an aid in establishing whether individual cattle are infected.

Agglutination Tests↗
PubMed1986

Cell surface glycoproteins of CHO cells. I. Internalization and rapid recycling.

The major cell surface proteins of Chinese hamster ovary (CHO) cells have been investigated after reacting cells at 4 degrees C with the membrane-impermeant reagent, trinitrobenzenesulfonate (TNBS). Immunoprecipitation and subsequent two-dimensional, sodium-dodecyl sulfate, polyacrylamide gel electrophoresis (SDS-PAGE) of proteins from derivatized cells that had been labelled previously with [3H]D-glucosamine or [3H]L-leucine showed that TNBS reacted with most of the high molecular weight (HMW) acidic glycoproteins that became labelled with iodine by the lactoperoxidase technique and that bind the lectin, wheat germ agglutinin (WGA). After warming the cells to allow endocytosis to proceed, molecules haptenized with trinitrophenol (TNP) groups were followed radiochemically by means of [125I]anti-DNP antibodies. The half-life for internalization of proteins tagged with either [125I]anti-DNP IgG or Fab averaged about 5 min. A similar result was obtained when a monoclonal antibody directed against a single plasma membrane glycoprotein was used, or when the rate of surface loss of TNP groups unoccupied by antibodies was measured. Within 15 min at 37 degrees C, a steady-state between surface and cytoplasmic label was reached, with about 65% of the hapten located internally. Recycling of internalized TNP groups back to the cell surface also occurred rapidly (t 1/2 approximately 5 min). Most of the intracellular radioactivity was associated with a membrane fraction of density similar to that of the plasma membrane. Over a 4-h period, there was no significant entry of labeled molecules into lysosomes. By contrast, the fluid-phase marker, horseradish peroxidase, became associated with the lysosomes within 1 h. Our results are consistent with the view that the majority of plasma membrane glycoproteins are continuously being internalized and recycled at a high rate.

Animals↗
PubMed1986

Cell surface glycoproteins of CHO cells. II. Surface distribution and pathway of internalization.

The surface distribution and pathway for internalization of the major cell surface proteins of Chinese hamster ovary (CHO) cells have been investigated after reacting cells at 4 degrees C with the membrane-impermeant reagent trinitrobenzenesulfonate. Molecules, haptenized with trinitrophenol groups, the majority of which are in a group of high molecular weight acidic glycoproteins (HMWAG), were labelled at 4 degrees C with anti-dinitrophenol immunoglobulins coupled to fluorescein isothiocyanate (FITC), horseradish peroxidase, or colloidal gold and either immediately fixed for mapping their distribution or followed intracellularly after warming to allow endocytosis to proceed. The distribution of label on the CHO cell surface was non-random with a large proportion arranged in clusters from 100 to 300 nm in diameter. Antibody label was concentrated heavily on microvilli, and about 10% of the molecules were always associated with clathrin-coated pits. Upon warming the cells to 37 degrees C, HMWAG were internalized immediately into smooth-membraned tubules (less than 80 nm luminal diameter) that appeared to connect with vesicles (less than 300 nm luminal diameter) located in the cortical cytoplasm. By 60 min, labelled antibody was located within larger vesicles (greater than 300 nm luminal diameter) that had a morphology characteristic of multivesicular bodies and not lysosomes. There was no evidence for entry of labelled molecules into either electron-dense, secondary lysosomes or into the Golgi cisternae, suggesting that neither compartment is involved in the major pathway of cell surface endocytosis. Our results are consistent with the view that the majority of plasma membrane protein are internalized as small discrete domains by a pathway very similar to that described by others for adsorptive endocytosis.

Animals↗
PubMed1986

Inhibition of uterine prostaglandin-F2 alpha production by bovine conceptus secretory proteins.

The effect of bovine conceptus secretory proteins (CSP) on uterine prostaglandin (PG)-F2 alpha production was evaluated in dairy cattle following injection of estradiol-17 beta. Intrauterine injections of dialyzed serum proteins (Control, n = 5) or CSP (n = 5) were administered from days 15 through 18 post-estrus. Following intrauterine treatments on day 18, all cows were injected with E2 (3 mg) to stimulate uterine PGF2 alpha production. Plasma concentrations of progesterone (P4) and 15-keto-13,14-dihydro-PGF2 alpha (PGFM) were determined by RIA. The PGFM responses following E2 challenge were decreased (p less than 0.01) for cows receiving CSP versus serum proteins into the uterine lumen. Individual PGFM, P4 and cycle length responses are discussed. Data suggest that proteins secreted by the bovine conceptus suppress uterine PGF2 alpha production during pregnancy recognition in the cow.

Animals↗
PubMed1986

Interrelationships between uterus and conceptus to maintain corpus luteum function in early pregnancy: sheep, cattle, pigs and horses.

Processes associated with "Maternal Recognition of Pregnancy" are reviewed extensively from the ovine, bovine, porcine and equine species. Comparisons among these species indicate that CL maintenance is achieved primarily by a predominant antiluteolytic-anti PGF effect, and there is strong evidence for antiluteolytic-luteoprotective and luteotropic controls that complement this basic system. The nature of the chemical signals (steroids, prostaglandins and proteins) to regulate these processes among the species are described. Common to all of the species reviewed is a change in vascular dynamics to and from the uterus and ovary during early pregnancy. The dialogue between endometrial epithelium and trophectoderm of the developing conceptus is described. The consequence of these various physiological and biochemical responses of early pregnancy is maintenance of the CL to provide a sustained embryotrophic environment. Either in the absence of or death of a conceptus, an efficient and acute system is operational to terminate this progestational environment via regression of the CL through uterine production of PGF.

Animals↗
PubMed1986

Proteins secreted by the sheep conceptus suppress induction of uterine prostaglandin F-2 alpha release by oestradiol and oxytocin.

In Exp. I, 0.5 mg oestradiol or vehicle (0.5 ml absolute ethanol + 0.5 ml 0.9% NaCl) was injected i.v. at 08:00 h on Day 14 (onset of oestrus = Day 0). Blood samples were obtained via a jugular catheter at 30 and 1 min before oestradiol and every 30 min for 10 h afterwards. Plasma was obtained and assayed for 15-keto-13,14-dihydro-PGF-2 alpha (PGFM) by radioimmunoassay. Before oestradiol, PGFM basal values were higher (P less than 0.01) in pregnant (N = 10) than nonpregnant (N = 6) ewes (193 +/- 30 vs 67 +/- 8 pg/ml). However, at 4-10 h after oestradiol, pregnant ewes (N = 5) had less variable (P less than 0.01) PGFM values than did nonpregnant ewes (N = 5). In Exp II, conceptus secretory proteins (CSP) were obtained by pooling medium from cultures of Day-16 sheep conceptuses (N = 40). Ewes received 750 micrograms CSP + 750 micrograms plasma protein (N = 6) or 1500 micrograms plasma protein (N = 6) per uterine horn at 08:00 h and 18:00 h on Days 12-14. All ewes received 0.5 mg oestradiol at 08:00 h on Day 14 and blood samples were collected as in Exp. I and assayed for PGFM. On Day 15, 3 ewes in each group received 10 i.u. oxytocin and 3 received saline i.v. at 08:00 h and blood samples were taken continuously from 10 min before to 60 min after treatment. Mean PGFM response to oestradiol was suppressed (P = 0.05) in CSP- vs plasma protein-treated ewes (371 +/- 129 vs 1188 +/- 139 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Role of conceptus secretory products in establishment of pregnancy.

Conceptuses produce steroids, prostaglandins, proteins and possibly other unidentified agents which may play a role in the establishment and maintenance of pregnancy. A key event in this process is protection of the corpus luteum (CL) from the luteolytic activity of prostaglandin (PG) F-2 alpha of uterine origin. Oestrogens produced by the pig conceptuses between Days 11 and 16 appear to exert an antiluteolytic effect resulting in the sequestering of PGF-2 alpha within the uterine lumen. Failure of the pregnant uterus to release PGF-2 alpha in an endocrine fashion, therefore, allows for maintenance of CL function. Conceptuses of sheep and cattle produce proteins which, when introduced into the uterine lumen of nonpregnant ewes and cows, suppress the ability of oestradiol and oxytocin to stimulate uterine production of PGF-2 alpha. These conceptus secretory proteins appear to exert an antiluteolytic effect by inhibiting uterine production of luteolytic amounts of PGF-2 alpha. The horse conceptus produces both oestrogens and proteins during early pregnancy when uterine production of PGF-2 alpha is suppressed. Co-culture of horse endometrium and conceptus inhibits endometrial production of PGF-2 alpha. Conceptuses of pigs, sheep and cattle undergo elongation to achieve apposition between trophectoderm and endometrium but the horse embryo migrates rapidly and consistently throughout the uterus to achieve endometrial contact.

Animals↗
PubMed1986

Proteins secreted by day-16 to -18 bovine conceptuses extend corpus luteum function in cows.

Corpus luteum function, interoestrous interval and spontaneous uterine PGF-2 alpha (PGF) production were evaluated in 9 cyclic Holstein cows (3/group) after intrauterine injections of pooled conceptus secretory proteins, 5 beta-pregnan-3 alpha-ol-20-one, or homologous serum proteins on Days 15.5 through 21 after oestrus. A significant extension of corpus luteum lifespan and interoestrous interval were detected in cows treated with conceptus secretory proteins compared to the other 2 groups. CL lifespan and interoestrous interval were not different (P greater than 0.25) between 5 beta-pregnan-3 alpha-ol-20-one and control groups. Evaluation of spontaneous PGF responses suggested that proteins synthesized and secreted by the bovine conceptus accommodate luteal maintenance during early gestation via an attenuation of endometrial PGF production.

Animals↗
PubMed1986

Role of uteroferrin in placental iron transport in swine: relationship between uteroferrin levels and iron deposition in the conceptus during gestation.

This study was to examine the relationship between uteroferrin and Fe, and Fe and Cu in the fetal pig. In Exp. 1, conceptus tissues and fluids were obtained on d 30, 45, 60, 75 and 90 of gestation for Fe and Cu analyses. In fetus minus liver, total Fe and Cu increased constantly between d 30 and 90, but Fe and Cu concentrations (microgram/g dry tissue) both decreased between d 30 and 45 and then remained relatively constant to d 90. For fetal liver, total Fe increased from d 30 (27 micrograms) to d 90 (3,222 micrograms), as did total Cu (14 micrograms on d 30 to 960 micrograms on d 90). Fetal liver Fe concentration (microgram/g dry tissue) decreased from d 30 (1,021) to d 60 (472) and then increased to d 90 (1,082), whereas Cu concentration increased between d 30 (537) and 60 (830) and then decreased between d 60 (471) and 90 (329). In allantoic fluid, both total Fe and Cu increased between d 30 and 60 and then decreased to d 90. Data from this study indicated a close temporal relationship between Fe and Cu in the fetal tissues and fluids examined. In Exp. 2, the relationship between Fe and uteroferrin in fetal tissues and fluids was studied. Uteroferrin, measured indirectly by acid phosphatase activity and Fe in fetal tissues and fluid underwent closely related temporal changes between d 30 and 112 of gestation. Changes in total Fe and Fe concentration during gestation were similar to those described for Exp. 1 in fetus minus liver, fetal liver and allantoic fluid. In addition, total Fe and Fe concentration in placental and endometrial tissues were analyzed. It was concluded that uteroferrin provides a major source of Fe in endometrial secretion and that it may be stored in placental and endometrial tissues. The relationship between Fe and Cu in conceptus tissues and erythropoiesis also is discussed.

Acid Phosphatase↗
PubMed1986

Role of uteroferrin in transplacental iron transport in the pig.

The pig possesses a noninvasive, diffuse type of epitheliochorial placentation in which the blood supply of the mother is well separated from the absorptive surface of the chorion, a feature that must complicate the movement of nutrient molecules across the placenta. Evidence is presented that a protein synthesized and secreted by the glandular epithelial cells of the maternal uterus of the pig is involved in iron transport to the fetus. This protein, uteroferrin, is induced by progesterone; is purple, which results from an unusual iron center; and possesses acid phosphatase activity. Secreted uteroferrin is taken up by specialized chorionic epithelial cells located in domed structures, called areolae, overlying the mouth of each uterine gland. Uteroferrin then enters the placental venous drainage and its iron is efficiently incorporated into fetal hemoglobin. It is taken up by the fetal liver or cleared by the kidney. The liver is the main site of erythropoiesis in the fetus. From the kidney uteroferrin enters the allantoic sac where it exchanges its iron with fetal transferrin. The rate of uteroferrin biosynthesis in the uterus and its rate of metabolism in the fetus can theoretically provide sufficient iron for the needs of pregnancy, at least until around day 70 of the 115-day gestation. Uteroferrin and transferrin, the iron transport protein of plasma, appear to be unrelated proteins.

Acid Phosphatase↗
PubMed1985

The type 5, acid phosphatase from spleen of humans with hairy cell leukemia. Purification, properties, immunological characterization, and comparison with porcine uteroferrin.

The spleens of patients with hairy cell leukemia contain high levels of a tartrate-insensitive, cationic, acid phosphatase (the human Type 5 isozyme). This phosphatase has been purified by a procedure which involves only two chromatographic steps: CM-cellulose chromatography and immunoaffinity chromatography on sheep antibodies generated against porcine uteroferrin. Uteroferrin is an abundant iron-containing acid phosphatase that can be recovered readily from porcine uterine secretions. Like uteroferrin, the purified human Type 5 phosphatase is a glycoprotein of molecular weight about 34,000. It contains two atoms of iron/molecule. The human phosphatase and uteroferrin also resemble each other closely in electrophoretic mobility, substrate specificity, and response to a variety of activators and inhibitors. Mouse monoclonal antibodies have been raised to uteroferrin and to the human Type 5 phosphatase. Three monoclonal antibodies which bind with high affinities to distinct sites on the uteroferrin molecule also recognize the human spleen enzyme, but bind to it with much lower affinity. These antibodies also recognize cationic acid phosphatases purified from bovine and rat spleens. A monoclonal antibody raised against the human enzyme, but selected for binding to uteroferrin, appears to recognize a relatively conserved site on all four phosphatases. We conclude that the human Type 5 isozyme belongs to a growing class of structurally related, iron-containing acid phosphatases which includes the iron-transport protein, uteroferrin.

Acid Phosphatase↗
PubMed1985

The carbohydrate structure of porcine uteroferrin and the role of the high mannose chains in promoting uptake by the reticuloendothelial cells of the fetal liver.

Uteroferrin, the iron-containing, progesterone-induced phosphatase of the porcine uterus, is a glycoprotein carrying a single oligosaccharide chain. Most of the uteroferrin isolated from either uterine secretions or allantoic fluid has endoglycosidase H-sensitive carbohydrate chains with either five or six mannose residues. As determined by 1H-NMR spectroscopy, the Man6 oligosaccharide has the following structure. (Formula: see text) The Man5 species lacks the terminal alpha 1,2-linked residue. Uteroferrin is transported across the pig placenta and has been proposed to be involved in iron transfer to the fetus (see Buhi, W. C., Ducsay, C. A., Bazer, F. W., and Roberts, R. M. (1982) J. Biol. Chem. 257, 1712-1721). Injection of 125I-labeled uteroferrin into the umbilical vein of midpregnant fetuses resulted in incorporation of label into the liver, the major site of fetal erythropoiesis. Light and electron microscope autoradiography revealed that the primary sites of uteroferrin uptake were the reticuloendothelial cells lining the liver sinusoids. Reticuloendothelial cells isolated from either fetal pig or adult rat livers were shown to accumulate uteroferrin when cultured in vitro. Uptake was inhibited by yeast mannan and by glycopeptides isolated from either ovalbumin or uteroferrin. Rat cells did not accumulate uteroferrin whose high mannose chains had been removed using endoglycosidase H. Moreover, the K uptake values (3 X 10(-7) M), specific competition by D-mannose and L-fucose bovine serum albumin, and inhibition by EDTA are consistent with an uptake mechanism involving a receptor for high-mannose oligosaccharides on the liver sinusoidal cells. It is suggested that one function of this receptor in the fetal pig is to remove maternally derived uterine glycoproteins from the fetal circulation. In the case of uteroferrin this process provides iron to the fetal liver.

Acid Phosphatase↗
PubMed1985

Syndromes with lissencephaly. II: Walker-Warburg and cerebro-oculo-muscular syndromes and a new syndrome with type II lissencephaly.

Lissencephaly (smooth brain) is an abnormality of brain development characterized by incomplete neuronal migration and a smooth cerebral surface. At least two distinct pathological types occur, each associated with several recognized syndromes. In this paper, we report on the clinical and pathologic manifestations of four additional patients and classify and delineate three separate disorders with type II lissencephaly. We also report on a previously undescribed abnormality in one of the four patients--dilated rough endoplasmic reticulum cisternae containing an unknown osmiophilic secretory product, probably a glycoprotein.

Abnormalities, Multiple↗
PubMed1985

Localization of the iron transport glycoprotein, uteroferrin, in the porcine endometrium and placenta by using immunocolloidal gold.

Uteroferrin, a glycoprotein implicated in transplacental iron transport in the pig, has been localized within the porcine uterus during mid pregnancy by using immunocolloidal gold labeling of sectioned material. In the endometrium where uteroferrin is synthesized, it was located exclusively in the non-ciliated cells of the glandular epithelium where it appeared to follow a common route of secretory glycoprotein from the cell (i.e., rough endoplasmic reticulum----Golgi----condensing vacuoles----secretory granules). Uteroferrin was present in the lumen of the glands and overlying placental areolae and in the large absorptive chorionic epithelial cells of the areolae. The latter cells contained numerous small vesicles and tubules as well as large endocytotic vacuoles. All these structures contained uteroferrin and are probably involved in translocating the glycoprotein in intact form from the uterine lumen to the blood capillaries draining the placenta.

Acid Phosphatase↗
PubMed1985

Characterization of proteins produced in vitro by periattachment bovine conceptuses.

Bovine conceptuses from Days 16 (n = 4), 19 (n = 6), 22 (n = 3), and 24 (n = 4), and chorion from Day 69 (estrus/mating = Day 0) were cultured for 24 h in modified minimum essential medium (MEM) in the presence of radioactive L-leucine [( 3H] leucine) to characterize de novo synthesis and release of proteins. Proteins released into MEM were identified by two-dimensional polyacrylamide gel electrophoresis, fluorography, and gel and ion exchange chromatography. Major polypeptides identified in MEM were different from those identified in conceptus and chorionic tissues. Both uptake of [3H] leucine and quality of polypeptides produced de novo and released into MEM were related to stage of conceptus development. Percent retention of [3H] leucine in MEM was lowest (P less than 0.01) in Day 16 cultures (1.2 +/- 4.1%), increased in Days 19 (16.8 +/- 3.7%) and 22 cultures (20.9 +/- 5.8%), and decreased (P less than 0.07) in Day 24 cultures (6.9 +/- 4.1%). Complexity of polypeptides increased after Day 16. Days 16, 19, 22 and 24 conceptus culture MEM was enriched in low-Mr, acidic polypeptides (Mr/isoelectric point ranges: 22K-26K/6.5-5.6, 20K-26K/5.5-5.4, and 16K-20K/5.0-4.5), which were not prominent products of Day 29 and 69 tissues. A high-Mr (Mr +/- SEM; 735K +/- 22K) glycoprotein was produced by all conceptus and chorionic tissues. The transient nature of production of low-Mr polypeptides suggests that they may be required during the periattachment period.

Amino Acids↗
PubMed1985

Characterization of proteins produced in vitro by bovine endometrial explants.

Endometrial tissues were obtained from 17 pregnant (P, estrus/mating = Day 0; Day 16, n = 4; Day 19, n = 6; Day 22, n = 3; Day 24, n = 4) and six nonpregnant (NP; Day 16, n = 4; Day 19, n = 2) cattle, as well as from one cyclic (nonbred) cow (Day 4), one later-pregnant cow (Day 69), and both ligated and pregnant uterine horns of three unilaterally pregnant cattle (UP; Day 270). Tissues (approximately equal to 500 mg wet tissue/explant) were cultured for 24 or 48 h in modified minimal essential medium (MEM), in the presence of radioactive amino acid and/or amino sugar substrate(s) (L-[3H] leucine, L-[14C] leucine, and D-[3H] glucosamine), in order to characterize substrate uptake and de novo synthesis and release of proteins and polypeptides in vitro. Endometrial explants from all cattle produced proteins de novo from radiolabeled substrates. Chromatographic (gel filtration, cation, and anion exchange) and two-dimensional polyacrylamide gel electrophoretic analyses revealed complex patterns of primarily acidic radiolabeled polypeptides in dialyzed MEM, which were absent from endometrial tissue homogenates. No qualitative differences were noted in the array of proteins released into MEM associated with either pregnancy status (P vs. NP, UP) or stage of gestation (Days 16, 19, 22, 24, 69, and 270). Medium from all endometrial explants was enriched in polypeptides in four Mr (X 10(3)/pH classes (I, approximately equal to 14/greater than 7.2; II, 19-24/5.4-6.3; III, 28-31/6.9-7.3; and IV, greater than or equal to 150/less than or equal to 5.1).

Amino Acids↗