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R E Ulane

Publications and source records attributed to R E Ulane.

15 recordsLinked to original sources
PubMed1994

Cystic fibrosis and phosphatidylcholine biosynthesis.

The cystic fibrosis (CF) gene defect may be associated with a defect in membrane recycling. We have investigated the metabolism of the main constituent of plasma membrane, phosphatidylcholine (PC). In this study of platelets and fibroblasts, we show an increased uptake of choline into PC of CF cells as compared with normal cells. No accumulation of PC was seen. Other patients with respiratory disease (not CF) showed normal rates of incorporation of choline into platelet PC. Platelets from heterozygote individuals showed intermediate turnover rates of choline incorporation into PC. The increase in choline incorporation into PC in CF platelets was not due to modified or increased sensitivity to either cAMP or prostaglandin E2. The total amount and the proportions of the major phospholipids in platelets of control and CF individuals were identical. These findings indicate an increased turnover rate of this phospholipid in CF cells rather than an increased net synthesis.

Base Sequence↗
PubMed1984

Prolactin binding in the developing rat fetal liver.

The binding of prolactin by fetal rat liver cell membrane fractions from 17 to 21 days gestation was studied. Particulate liver membranes were prepared in Dulbecco's Phosphate Buffered Saline (PBS) by ultracentrifugation and incubated at 22 degrees C for 16 hours with [125I] iodo-human growth hormone (hGH). Non-specific binding was assessed by parallel incubations in the presence of a 2000-fold excess ovine prolactin. Specific prolactin binding sites were detected only at 21 days gestation (2932 +/- 401 cpm/mg protein) in freshly prepared membranes. On freezing at -20 degrees C for 24 to 48 hours, the membranes of 20 days gestation animals were able to specifically bind prolactin (1295 +/- 239 cpm/mg protein). Freezing led to a 45 +/- 7% increase (4270 +/- 701 cpm/mg protein) in prolactin binding at 21 days gestation. No hormonal binding was detected from 17 through 19 days gestation in either fresh or freeze-thawed membranes. Scatchard analysis revealed a high affinity binding site with a Ka of approximately 1.4 X 10(8)M-1 in both fresh and freeze-thawed membrane preparations. The data show that 1) prolactin receptors appear in liver only during late fetal life and that 2) freezing of membranes may unmask binding sites that are initially unavailable to specifically bind prolactin.

Animals↗
PubMed1982

Insulin receptors in the developing fetal lung.

Fetal lung insulin receptor numbers and affinities were studied in rat pregnancies from 15 to 22 days gestation. Insulin receptor binding capacities were found to increase six-fold from approximately 100 fmoles insulin bound/mg lung DNA at 15 days gestation to approximately 600 fmoles bound/mg DNA at 22 days gestation. However, the affinity constants of the receptors were unchanged during this same period (high affinity, 1.9 +/- 0.4 S.E. and low affinity, 0.03 +/- 0.01 S.E.). The results suggest that the lung may become increasingly more sensitive to insulin as development progresses.

Animals↗
PubMed1982

Role of uteroglobin and transglutaminase in masking the antigenicity of implanting rabbit embryos.

Using rabbit as a model, the roles of uteroglobin (UG) and transglutaminase (TG) in masking the antigenicity of early developing mammalian embryo have been investigated. Maternal lymphocytes in vitro, when mixed with mitomycin-C inactivated blastomeres, incorporated H3-thymidine, suggesting recognition of embryonic antigens by these cells. However, pretreatment of blastomeres with pregnant uterine fluid (PUF) or with UG alone or in combination with TG (coagulation factor XIIIa), resulted in a significant and dose-dependent suppression of H3-thymidine incorporation into these lymphocytes. A complete suppression was achieved at a concentration of 250 micrograms of UG/ml, in the absence of TG. However, in the presence of TG, only 1.0 micrograms of UG/ml was required for total suppression. Neither nonpregnant uterine fluid (NPUF), nor myoglobin, a nonspecific protein similar in molecular weight to UG, had any suppressive effect. Incubation of uteroglobin with anti-UG or TG with its antiserum prior to the pretreatment of blastomeres eliminated the suppressive effect of these proteins. Inhibition of TG by neopentyl chloroethyl nitrosourea (NPCNU) also eliminated the suppressive effects of uteroglobin on H3-thymidine incorporation into maternal lymphocytes. These results suggest that in the pregnant uterus UG in conjunction with TG may play a specific role in masking the antigenicity of developing embryos during implantation.

Animals↗
PubMed1982

Effect of homocysteine and homocystine on platelet and vascular arachidonic acid metabolism.

Normal hemostasis depends in part on the balance achieved between proaggregatory and prothrombotic platelet thromboxane A2, measured as its stable end-product thromboxane B2 (TXB2), and vascular prostacyclin (PGI2), which inhibits platelet aggregation and is antithrombotic. Cystathionine-beta-synthase deficiency is characterized by a high frequency of thromboembolic disease. We therefore studied, in vitro, the effects of homocysteine and related compounds on platelet TXB2 and vascular PGI2 formation. In paired samples of platelet rich plasma, which had been preincubated with L-homocystine (1 mM), mean production of the two platelet cyclooxygenase products, TXB2 and 12-hydroxy-5, 8,10-heptadecatrienoic acid increased significantly from control levels [13.6% +/- 1.9 to 19.8% +/- 2.1 (P less than 0.02) TXB2 and 29.8% +/- 4.2 to 39.4% +/- 4.1 (P less than 0.01) HHT]. In the presence of D,L-homocysteine (1 mM), mean TXB2 and 12-hydroxy-5,8,10-heptadecatrienoic acid production was also significantly increased [12.7% +/- 1.5 to 16.9% +/- 1.5 (P less than 0.01) TXB2 and 27% +/- 4 to 31% +/- 4.1 (P less than 0.02) HHT]. Cystine, cysteine, or methionine (1 mM) did not have similar effects in this test system. Homocysteine and homocystine were without effect on the synthesis of vascular PGI2 by umbilical artery segments [control, 0.22 +/- 0.03 to 0.21 +/- 0.03 ng/mg with D,L-homocysteine and 0.20 +/- 0.04 control to 0.19 +/- 0.04 ng/mg with D,L-homocystine]. A homocyst(e)ine-induced increase in platelet thromboxane production in the absence of an increase in vascular prostacyclin, if present in vivo, may contribute to the vascular thromboses characteristic of human homocystinemias (homocystinurias).

Arachidonic Acid↗
PubMed1978

Evidence for the existence of a single enzyme catalyzing the phosphorylation of choline and ethanolamine in primate lung.

Choline kinase (ATP:choline phosphotransferase, EC 2.7.1.32) has been isolated and purified 1000-fold from adult African Green monkey lung with a yield of 10%. The purified enzyme also phosphorylated ethanolamine (ratio of ethanolamine kinase to choline kinase = 0.30). This ratio remained constant throughout the purification procedure. The Km for choline (3.0 - 10(-5) M) was lower than that of ethanolamine (1.2 - 10(-3) M.) Choline was also found to inhibit ethanolamine kinase activity by 50% at a concentration of 0.005 mM, while ethanolamine inhibited choline only at very high concentrations (100--150 mM). When the enzyme was subjected to inactivation by heat, hemicholinium-3, trypsin digestion, and p-hydroxymercuribenzoate, both ethanolamine kinase and choline kinase activities were destroyed at the same rate. Freezing and thawing in the absence of glycerol also destroyed both activities at the same rate. Based on these findings, we conclude that in adult African Green monkey lung tissue, there is only one enzyme for the phosphorylation of ethanolamine and choline, and that choline phosphorylation predominates.

Animals↗
PubMed1976

The activating system of chitin synthetase from Saccharomyces cerevisiae. Purification and properties of the activating factor.

The yeast proteinase that causes activation of the chitin synthetase zymogen has been purified by a procedure that includes affinity chromatography on an agarose column to which the proteinaceous inhibitor of the enzyme had been covalently attached. The purified enzyme yielded a single band upon disc gel electrophoresis at pH 4.5 in the presence of urea. At the same pH, but without urea, a faint band was detected in coincidence with enzymatic activity, whereas at pH 9.5, either in the absence or in the presence of sodium dodecyl sulfate, no protein zone could be seen. From sedimentation and gel filtration data, a molecular weight of 44,000 was estimated. The proteinase was active within a wide range of pH values, with an optimum between pH 6.5 AND 7. Titraton of the activity with the protein inhibitor from yeast required 1 mol of inhibitor/mol of enzyme. A similar result was obtained with phenylmethylsulfonyl fluoride, an indication that 1 serine residue is required for enzymatic activity. The enzyme exhibited hydrolytic activity with several proteins and esterolytic activity with many synthetic substrates, including benzoylarginine ethyl ester and acetyltyrosine ethyl ester.A comparison of the properties of the enzyme with those of known yeast proteinases led to the conclusion that the chitin synthestase activating factor is identical with the enzyme previously designated as proteinase B (EC 3.4.22.9). This is the first time that a homogeneous preparation of proteinase B has been obtained and characterized.

Chitin Synthase↗
PubMedDate not supplied

A comparison of insulin receptors in the developing fetal lung in normal and in streptozotocin-induced diabetic pregnancies.

Insulin receptors from fetal rat lungs of normal and streptozotocin-induced diabetic pregnancies were examined for their binding capacities and association constants. Sprague-Dawley rats, given a single dose of streptozotocin at 7 days' gestation, became hypoinsulinemic and hyperglycemic within 48 hours, although they remained healthy enough to carry fetuses to term. The fetuses of the streptozotocin-treated pregnancies had hyperglycemia (3,750 +/- 400 micrograms glucose/ml vs 390 +/- glucose/ml for control subjects), but were not hyperinsulinemic. Insulin receptor binding capacities of fetal lungs from control pregnancies increased as a function of gestational age from 16 to 21 days. Receptor binding capacities of lungs from streptozotocin-treated pregnancies also increased with gestational age until 21 days, when they dropped to 50% of control values. It was demonstrated in organ culture that fetal lung receptors from normal pregnancies of 20 days' gestation could be down-regulated in the presence of insulin and that this down-regulation is coupled to a biologic effect of insulin, hexose transport. It was concluded that fetal lung insulin receptors can be regulated by insulin concentrations in vitro and by experimental diabetic pregnancies in vivo.

Animals↗