Thesis (M.S.)--Purdue University, 2003. / Includes bibliographical references (leaves [70]-80). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1969. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Thesis (M.S.)--Purdue University, 2003. / Includes bibliographical references (leaves [70]-80).

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Nuclear Engineering, 1977 / Bibliography : leaves 169-175. / Ph. D. / Ph. D. Massachusetts Institute of Technology, Department of Nuclear Engineering

A brainstem-related abnormality in respiratory control appears to be one of the most compelling mechanisms for sudden infant death syndrome (SIDS). The elements calcium, copper, iron, potassium, magnesium, sodium, phosphorus, sulfur, and zinc were analyzed by inductively coupled plasma atomic emission spectroscopy in the brainstem of 30 infants who died from SIDS and 10 infants who died from other causes (control). No differences were found between SIDS and control for any element except for more calcium in the SIDS group. A multivariate analysis of the data failed to group the majority of SIDS and control subjects in different clusters. Further research is required to determine the biological significance of the higher calcium found in the SIDS group.,

Calcium is a crucial intracellular messenger controlling a plethora of important intracellular events. Elevated [Ca2+]i levels regulate numerous processes due to the versatility of the Ca2+ signaling in terms of speed, amplitude and spatia-temporal patterning. Depletion of intracellular calcium stores functions as a primary trigger for a message that is translated to the plasma membrane, resulting in the slow activation of plasma membrane Ca2+ influx channels, which allow entry of external calcium. Since these channels depend upon the state of filling of the intracellular Ca2+stores, these influx channels are called store-operated channels (SOCs). It is unclear how empty intracellular stores signal activation of plasma membrane capacitative calcium entry (CCE). In order to bridge the gaps in our understanding of calcium's role in T cell regulation, this project was designed to look at the effects of various pharmacological regulators of T cell calcium stores. At the start, the effort was directed at the regulation of the microsomal calcium A TPases, considering these are perhaps the most essential mediators of intracellular calcium storage. Thapsigargin (TG) and cyclopiazonic acid (CPA) were shown to be the most potent inhibitors of the Ca2+ -ATPase, also a new Ca2+ regulator aaptamine was shown to exert more modest inhibition of the Ca2+ pump. We also characterized a novel compound, gingerol, findings its actions are to stimulate Ca2+ pumps. Cell growth assays revealed an important role for ryanodine receptors (RyRs) in regulating T cell growth. RyR activators CMC and PCB95 dramatically altered T cell growth patterns leading to significantly reduced cell viability. In contrast RyR antagonist dantrolene appeared to induce growth arrest in that cell proliferation was curtailed, yet cells remained viable. Cell viability studies revealed that the Ca2+ pump regulators TG and aaptamine were also observed to reduce cell growth rates, presumably as a result of their ability to deplete Ca2+ stores (100 nM TG was able to decrease cell viability by 90% within 24 hrs of exposure). PCB95 was able to decrease cell viability by 50% within 24 of hrs exposure and CMC decreased cell viability by 75% within 24 hrs and further over a 48 hr period. 2-APB and aaptamine were cytotoxic at higher doses. The inositol 1 ,4,5 -trisphosphate receptor (IP3R) pathway was also found to be critically linked to T cell growth control. We observed that the IP3R modulator, 2- aminoethoxydiphenyl borate (2-APB) induced antigen-like Ca2+ spike that correlates with suppression of T cell growth rates. In this study we have identified two novel T cell Ca2+ store regulators, aaptamine and gingerol. We also find that Ca2+ stores are indeed sensitively linked to T cell growth regulation. Depletion of Ca2+ stores with SERCA inhibitors as well as both RyR and IP3R activators profoundly suppress T cell proliferation most likely via activation of apoptosis.

The versatility of Ca2+ as a messenger regulating a myriad of signalling events requires that the concentration of Ca2+ ions in the cytoplasm be highly regulated. Capacitative Ca2+ entry (CCE) or store-operated Ca2+ (SOC) entry, whereby the depletion of intracellular Ca2+ stores induces the influx of Ca2+ across the plasma membrane, plays a crucial role in Ca2+ signalling. Despite the recent advances in elucidating the entry pathway, its molecular identity, biophysical properties and store-depletion signal remains undefined. Thapsigargin (TG), a sarcoplasmic/endoplasmic reticulum Ca2+ A TPase pump (SERCA), inhibitor induces passive depletion of the internal Ca2+ stores and triggers CCE. The universality of this signal has been widely accepted and TG has proven to be a valuable tool in studying CCE. The neuronal cell line NG 115 -401 L lacks the TG activated Ca2+ influx pathway. Agonists of the ryanodine receptor (RyR); chlorom- cresol (CMC), polychlorinated biphenyl 95 (PCB), ryanodine, caffeine, and that of the inositol-1 ,4 ,5-trisphosphate receptor (IP3R), bradykinin, effectively couple to the activation of Ca2+ influx in these cells. The Ca2+ influx signal due to these agonists can be inhibited by SOC blockers such as La3+, Zn2+, Ni2+ and SF&F 96365. Thapsigargin, CMC and PCB95 share the same Ca2+ releasable pools in the 401 L cells. Our data thus suggests that the channels present in the 401 L cells are likely to be receptor-activated channels rather than the store-depletion activated channels. Cell viability studies show that thapsigargin (25 nM) can decrease viability by 75% within 24 hrs and the RyR agonist caffeine decreased viability to <60% within 24hrs. CMC, PCB95 and ryanodine also were cytotoxic at higher doses. Nuclear fragmentation patterns and activation of caspase-3 in thapsigargin and caffeine-treated cells suggest the induction of apoptosis within 12 hrs of treatment. The treated cells were shown to generate nitric oxide, a potential apoptosis inducing agent.

Le VIP (ou vasoactive intestinal peptide) est un neuropeptide actif au niveau du syst¨¨me nerveux central et p¨¦riph¨¦rique (syst¨¨mes cardiovasculaire, respiratoire, tractus gastro-intestinal¡­). Il agit sur ces tissus cibles par interaction avec les r¨¦cepteurs VPAC1 et VPAC2, pour lesquels il poss¨¨de une haute affinit¨¦. Ces r¨¦cepteurs appartiennent ¨¤ la classe II des r¨¦cepteurs ¨¤ 7 h¨¦lices transmembranaires coupl¨¦s aux prot¨¦ines G, distincte de celle des r¨¦cepteurs apparent¨¦s ¨¤ la rhodopsine. En r¨¦ponse au VIP, ils stimulent pr¨¦f¨¦rentiellement l'ad¨¦nylate cyclase. Seul le r¨¦cepteur VPAC1 est capable, lorsqu'il est exprim¨¦ ¨¤ haute concentration, d¡¯augmenter les concentrations de calcium intracellulaire :G*i participe ¨¤ cette interaction. L'exposition des deux r¨¦cepteurs au VIP n'aboutit pas seulement ¨¤ leur activation :elle induit une succession de m¨¦canismes cellulaires intrins¨¨ques responsables d'une diminution de la capacit¨¦ du r¨¦cepteur ¨¤ r¨¦pondre ¨¤ un agoniste :la d¨¦sensibilisation. <p>Diff¨¦rents processus peuvent contribuer ¨¤ la d¨¦sensibilisation d¡¯un r¨¦cepteur :le d¨¦couplage du r¨¦cepteur de la prot¨¦ine G, la s¨¦questration du r¨¦cepteur, ou encore leur "down regulation", r¨¦sultat ¨¤ plus long terme de la perte d'une partie du pool total de r¨¦cepteurs. Les m¨¦canismes impliqu¨¦s d¨¦pendent du r¨¦cepteur consid¨¦r¨¦ et de l'¨¦quipement prot¨¦ique de la cellule. <p>Il a ¨¦t¨¦ r¨¦cemment montr¨¦ que le r¨¦cepteur VPAC1 humain ¨¦tait phosphoryl¨¦ (en position S447) en r¨¦ponse ¨¤ l¡¯agoniste, que la ¦Â-arrestine ¨¦tait transloqu¨¦e ¨¤ la membrane plasmique et que l¡¯internalisation qui s¡¯en suivait induisait un ph¨¦nom¨¨ne dynamine-d¨¦pendant. Aucune information plus pr¨¦cise n¡¯est r¨¦f¨¦r¨¦e dans la litt¨¦rature. <p>Ce travail de th¨¨se a donc consist¨¦ en une ¨¦tude plus approfondie de la phosphorylation, l¡¯internalisation et la r¨¦cup¨¦ration du r¨¦cepteur VPAC1 humain.<p><p>Dans un premier temps, nous nous sommes consacr¨¦ ¨¤ l¡¯¨¦laboration d¡¯un anticorps monoclonal sp¨¦cifique anti-r¨¦cepteur afin de visualiser le r¨¦cepteur. Nous avons eu recours ¨¤ l¡¯immunisation g¨¦n¨¦tique qui consiste ¨¤ injecter l¡¯antig¨¨ne sous forme d¡¯ADN. <p>Une majorit¨¦ des souris immunis¨¦es ont produit des anticorps. L¡¯une d¡¯entre-elle a permis de g¨¦n¨¦rer un anticorps monoclonal, lequel a ¨¦t¨¦ compl¨¨tement caract¨¦ris¨¦ :les r¨¦sultats obtenus par FACS montrent qu¡¯il est sp¨¦cifique, s¨¦lectif et que son ¨¦pitope est localis¨¦e au sein de l¡¯extr¨¦mit¨¦ amino-terminale du r¨¦cepteur (figure 1). Il n¡¯interf¨¨rent pas avec la liaison du ligand et ne modifie en rien l¡¯activation du r¨¦cepteur par celui-ci. Cet anticorps monoclonal ne permet pas de d¨¦tecter le r¨¦cepteur par Western Blott, mais est capable de l¡¯immunopr¨¦cipiter. <p><p>Dans un second temps, nous avons abord¨¦ l¡¯¨¦tude de la phosphorylation, de l¡¯internalisation et du trafficking du r¨¦cepteur VPAC1 humain.<p> / Doctorat en sciences médicales / info:eu-repo/semantics/nonPublished