Thesis (Ph. D.)--Illinois State University, 1973. / Title from title page screen, viewed Oct. 14, 2004. Dissertation Committee: William L. Daniel (chair), Herman E. Brockman, David F. Weber, Arlan Richardson, Howard Hetzel. Includes bibliographical references (leaves 53-66) and abstract. Also available in print.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (p. 147-155).

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2008. / Committee Co-Chair: Hud, Nicholas; Committee Co-Chair: Radhakrishna, Harish; Committee Member: Doyle, Donald; Committee Member: Fahrni, Christoph; Committee Member: McCarty, Nael. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 82-90).

Thesis (Ph. D.)--State University College of Forestry at Syracuse University, 1968. / Typescript. Vita: leaf 231. Description based on print version record. Includes bibliographical references (leaves 108-121).

Thesis (PhD) - University of Queensland, 2004. / Includes bibliography.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 130-155). Also available on the Internet.

Calcium transport across the placenta is asymmetrical and is believed to be an active transport. An essential step in such a transport is translocation of the ion across a single plasma membrane. The objective of this thesis was to study the Ca2+ -related properties of the placental plasma membranes and to gain some knowledge of their role in Ca2+ -transport. Three Ca2+ -related properties were studied: 1. Ca2+ -binding to the placental plasma membranes; 2. The membrane bound enzyme Ca -ATPase; and 3. Ca2+ -uptake by the placental plasma membrane vesicles. Ca2+ -binding properties of the membrane preparation were studied by the use of a new method, the flow dialysis system. Two types of sites for Ca were found: 1) high affinity, low capacity sites, and 2) low affinity, high capacity sites. The high affinity sites had 10-fold higher affinity for Ca2+ than for Mg2+ . A calcium-stimulated, membrane-bound enzyme, namely Ca2+ -ATPase, was located in the placental plasma membranes. This enzyme is distinct from the Na+, K+-ATPase and alkaline phosphatase. The enzyme can be activated by Mg2+ but with lower efficiency. Both Ca2+ and Mg2+ activate the enzyme at the same site. A formula was derived, enabling one to predict very precisely the velocity of the enzyme incubated under any combination of Ca2+ and Mg2+ ; this relationship is presented in a three dimensional model. The formula can be used for other enzymes or other substrates, as was demonstrated with ATP and ADP. The placental plasma membrane vesicles are capable of accumulating Ca2+ . Ca2+ -uptake was defined as the amount of Ca2+ which is not available for rapid exchange and cannot be displaced by a high concentration of competitor in the presence of ATP. This definition is different from and more accurate than the one which is widely used and cited in the literature. An intravesicular Ca2+ concentration of 190 mM was recorded, which was 24-fold higher than the external Ca2+ concentration (8 mM). Ca2+ -uptake was dependent on ATP hydrolysis by the placental Ca2+ -ATPase. This process was independent of Mg2+ . It is suggested that while the substrate for Ca2+ -ATPase is Ca-ATP, the substrate for Ca2+ -uptake is Ca2+. The overall Ca2+ -related properties of the placental plasma membranes are independent of Mg and the entire process from binding to membrane through activation of the enzyme and finally Ca2+ -uptake is dependent on Ca2+ alone. This situation is unique to the placental plasma membranes. It is tempting to speculate that the link between the maternal and the fetal circulation is achieved by forming vesicles loaded with Ca2+ on the maternal side and unloading them through fusion with the basal plasma membrane on the fetal side. The Ca2+ -related properties of placental plasma membranes described in this thesis, provide many answers regarding the first step in the asymmetrical transplacental Ca2+ -transport. Further investigation is required before a full understanding of the entire process is achieved. / Medicine, Faculty of / Cellular and Physiological Sciences, Department of / Graduate

Binding sites for prolactin have been identified and characterized in a plasma membrane enriched fraction isolated from livers of mature female rats. By chemical and enzymatic analysis the membrane preparation was shown to have slight contamination with nuclei and endoplasmic reticulum, while mitochondria were not detected. Sidedness analysis indicated that the membrane preparation was largely composed of inside-out vesicles. ¹²⁵I-oPRL prepared by the lactoperoxidase method had a specific activity of 40-60 μCi/μg. Competition studies using iodoprolactin indicated that iodination of the hormone did not affect its affinity for the receptor as compared to the native hormone. Binding of ¹²⁵I-oPRL was inhibited by prolactin from various species including ovine, bovine and rat prolactin while bGH, pACTH and AVP had no effect on binding. The binding of 125 I-oPRL was activated by both bivalent and monovalent cations - bivalent cations exerting a greater effect than monovalent cations. In the presence of 10 mM CaCl₂, binding of ¹²⁵I-oPRL was equal to the binding in the presence of the physiological concentration of NaCI. The association of ¹²⁵I-oPRL with the membrane was a time and temperature dependent process, being maximal at 37°. The dissociation of ¹²⁵I-oPRL was time and temperature dependent only with 150 mM NaCl at 37° while at all other temperatures and in the presence of 10 mM CaCl₂ dissociation was not.observed. The binding of ¹²⁵I-oPRL was strongly influenced by pH with an optimum observed at pH 6.5. Receptor activity was destroyed by pronase and phospholipase C, while neuraminidase increased binding. Treatment of the membranes by RNase and DNase did not effect the binding. Binding of ¹²⁵I-oPRL was inhibited by p-chloromercuribenzoic acid, dithiothreitol, and by brief exposure to high temperatures. Scatchard analysis of the binding of ¹²⁵I-oPRL to receptors indicates that prolactin has a high affinity for its receptor / Medicine, Faculty of / Biochemistry and Molecular Biology, Department of / Graduate