Among the substances released from human blood platelets are serotonin and various proteins. It was hypothesized that one of these proteins binds serotonin and that serotonin might be important to the protein's function or that the protein might be important to serotonin's function. Two platelet-specific proteins, platelet factor 4 (PF4) and ß-thromboglobulin ( ßTG) were found to bind serotonin in vitro. Endogenous PF4 was isolated by serotonin-affinity chromatography and was identified by radioimmunoassay. Purified l¹²⁵ I] -PF4 and native PF4 bound to and eluted from a serotonin-affinity column similarly. Ultrafiltration of the homologous protein, (ßTG, with [¹⁴C]-serotonin demonstrated binding of about 8 moles serotonin per mole tetrameric ßTG with a dissociation con stant of about 4 x 10-8ThesisThesis⁻⁸ M. Equilibrium dialysis of PF4 with radiolabelled serotonin was attempted, but no binding constant values were obtained because serotonin apparently bound to the dialysis membrane. Since EDTA was one of the two agents that eluted PF4 from the serotonin-affinity gel, calcium binding by -PF4 was investigated by equilibrium dialysis. Evidence was obtained for positively cooperative binding of calcium ions by PF4. It is concluded that PF4 and ßTG bind serotonin in vitro, that they may also bind in vivo when platelets undergo release, and that the functions of serotonin, PF4 and ßTG may be mediated in part by serotonin-protein associations. / KMBT_363 / Adobe Acrobat 9.53 Paper Capture Plug-in

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The aim of this study is to determine the changes in respiration in tissues from specific brain areas X-irradiated in vitro using a direct monometric procedure also to determine the differences in radiosensitivity of specific areas in the brain as reflected by changes in oxygen uptake and to shed some light on the nature of the biochemical lesions in nerve tissues brought about by ionizing radiation.

Thesis--Ph. D., University of Hong Kong.

(Uncorrected OCR) Abstract Abstract of thesis entitled "A comparative study of some possible mechanisms governing the intraluminal and intravascular release of 5-HT from the rabbit jejunum" submitted by WONG Joseph Chi-yan for the degree of Doctor of Philosophy (Pharmacology) at the University of Hong Kong in April 1973. Experiments were carried out on rabbit jejunal segments in. vivo and in vitro under conditions of intraluminal and intravascular perfusion. 5-HT was released into the effluent of both intraluminal- and intravascular perfusate during perfusion with Krebs solution under quiescent conditions. Enhanced 5-HT release was observed during active peristalsis elicited by increasing the intraluminalpressure during intraluminal perfusion. The addition of hydrochloric acid in physiological amounts to give pH values of 7.2, 6, 5 and 4 in Krebs solution revealed a progressive increase in 5-HT release as the pH fell, during intraluminal perfusion. Enhanced 5-HT release was also observed during intraluminal perfusions with 0.3 M and 0.6 M sucrose solutions; 0.6 M glucose solution and 7.5% egg albumin in Krebs solution. During intraluminal perfusion, Sennosides A & BlO ~g/ml., Nicotine 1 ~g/ml. and Morphine 10 ~g/ml. in Krebs solution, all enhanced 5-HT release; but not 1% Monosodium L-glutamate. Monoamine oxidase inhibitor, Nialamide, in a concentration of 100 ~g/ml. prevented . the destruction of both endogenous and exogenous 5-HT. Nicotine 1 ~g/ml. and Morphine 10 ~g/ml. did not enhance 5-HT release during intravascular perfusion. From the above observations, it is concluded that, in rabbits, 5-HT is involved in the normal physiological functions of digestion, absorption and motility. It possibly functions as a local hormone in regulating these processes. The intravascular release of 5-HT demonstrated in these experiments may not have any direct physiologic~l significance. It is not appropriate to compare the two perfusion methods in terms of the net amount of released 5-HT. From histological observations, it is suspected that the results of intraluminal perfusion are complicated by the shedding off of intestinal epithelial cells, into the perfusing fluid. Further investigations are needed to evaluate the reliability of this method in the study of the phenomenon of 115-HT release II under such experimental conditions, and the interpretation which can be put upon the results obtained. ii / abstract / toc / Pharmacology / Doctoral / Doctor of Philosophy

Thesis (M.S.)--Georgia State University, 2008. / Title from file title page. Lucjan Strekowski, committee chair; A.L. Baumstark, Gabor Patonay, Doyle Barrow , committee members. Electronic text (68 p. : ill.) : digital, PDF file. Description based on contents viewed June 23, 2008. Includes bibliographical references (p. 42-430.

Thesis (Ph.D.) -- University of Montana, 2008. / Title from author supplied metadata. Description based on contents viewed on June 20, 2009. ETD number: etd-12052008-124938. Includes bibliographical references.

Thesis (M.S.)--Georgia State University, 2008. / Title from file title page. Lucjan Strekowski, committee chair; A.L. Baumstark, Jerry Smith, committee members. Electronic text (83 p. : ill.) : digital, PDF file. Description based on contents viewed August 8, 2008. Includes bibliographical references (p. 44-46).