Thesis (Ph. D.)--Florida State University, 2004. / Advisor: Dr. Michael Chapman, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (viewed Sept. 15, 2005). Document formatted into pages; contains vi, 76 pages. Includes bibliographical references.

Thesis (Ph. D.)--Illinois State University, 1989. / Title from title page screen, viewed October 26, 2005. Dissertation Committee: Glen Collier (chair), Herman Brockman, Alan Katz, Lynne Lucher, Arlan Richardson. Includes bibliographical references (leaves 127-136) and abstract. Also available in print.

Thesis (M.S.)--University of Wisconsin--Madison, 1964. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 33-37.

There is strong evidence which supports a physiological role for arginine vasopressin (AVP) in the negative modulation of the febrile process within the central nervous system (CNS). This evidence arises from a variety of experimental techniques employed in a number of different animal models. The CNS locus of action for AVP-mediated antipyresis is within a rostral diencephalic site called the ventral septal area (VSA). It has become evident that the mechanism by which AVP and aspirin-like drugs transduce changes in febrile body temperature are similar. Moreover, antipyretic drugs and AVP may share a common CNS locus of action. Therefore, investigations were conducted to determine whether antipyretic drugs are functionally linked to the endogenous antipyretic system of the brain. In addition, an examination of the role for centrally acting AVP and the natural suppression of fever during pyrogenic tolerance to endotoxin was conducted. AVP receptor antagonists of the peripheral V₁ and V₂ sub-type or saline control were microinjected into the VSA of rats rendered febrile by an intracerebroventricular (icv) injection of E. coli endotoxin, to assess the effects on the antipyresis elicited by indomethacin. Blockade of central V₁ but not V₂ receptors significantly attenuated the antipyretic effects of indomethacin given intraperitoneally. This effect was even more pronounced when the V₁ antagonist was infused for 30 min before and for 60 min after indomethacin administration. The V₁ analogue alone was without thermoregulatory effects. In order to determine whether the above effects were applicable to antipyretic drugs in general, central V₁ blockade was performed in the febrile rat subsequently treated with intraperitoneal sodium salicylate or acetaminophen. Salicylate-induced antipyresis was blocked, in a dose related manner, by VSA administration of the AVP V₁ antagonist. The fever reducing capacity of acetaminophen was unaffected by central V₁ blockade. Collectively these antipyretic drug studies, suggest that some but not all antipyretic drugs activate the endogenous AVP antipyretic pathway within the brain. Moreover, these data suggest that the mechanism of action of antipyretic drugs can no longer be simply explained as an action on prostaglandin biosynthesis. Endogenous release of AVP from VSA nerve terminals during endotoxin fever and drug-induced antipyresis was examined using the technique of push-pull perfusion. The release of AVP into the perfusion fluid remained unaltered by indomethacin injected into the non-febrile rat. However, during fever indomethacin prompted both an antipyresis as well as a significant increase in AVP release. Acetaminophen injected intraperitoneally also evoked an antipyresis but with no concomitant release of AVP within the VSA. These results are consistent with the antagonist studies. The effects on central AVP release by indomethacin appear to be related to the pyrogen employed because the drug did not evoke the release of AVP when administered prior to the hyperthermia produced by icv PGE₂. Indeed, PGE₂ itself stimulated AVP release which was inhibited by indomethacin treatment. These results are not consistent with an antipyretic role for AVP and await further clarification. Analysis of the release of AVP into the plasma and cerebrospinal fluid (CSF) were conducted during the fever evoked by intravenous endotoxin and subsequent to antipyretic intervention. Intravenous endotoxin was a provocative stimulus for plasma AVP release. Endotoxin-stimulated plasma AVP levels were unaffected by intraperitoneal injections of indomethacin, sodium salicylate or acetaminophen. In non-febrile controls, indomethacin, and to some extent acetaminophen, prompted increases in plasma AVP; although the temporal course of this release was different between the two drugs. Within the CSF, endotoxin treatment did not alter the normal diurnal rhythm of AVP release. Indomethacin treatment significantly suppressed CSF AVP release in non-febrile animals. A similar but non-significant trend was observed in febrile rats. Collectively, these studies demonstrate the independent regulation of AVP release within three separate biological compartments in response to febrogenic and antipyretic stimuli. The suppression of fever after repeated daily intravenous injections of bacterial endotoxins was thought to be exclusively a hepatic phenomenon. Experiments were conducted to determine whether a central mechanism involving AVP may also contribute to the antipyretic state observed during pyrogenic tolerance. In endotoxin tolerant animals, administration of a V₁ but not V₂ AVP receptor antagonist within the VSA, resulted in a significant reversal of the tolerant pyrogenic response. These data support the hypothesis that the central endogenous antipyretic system, involving AVP, plays a role in the mechanism of endotoxin tolerance. Tolerance does not develop following repeated central injections of pyrogens. Further experiments were performed to determine whether tolerance-induced activation of the antipyretic pathway would render an animal hyporesponsive to centrally administered pyrogens. When injected icv, during active endotoxin tolerance, the thermoregulatory responses to PGE₂ or endotoxin were not significantly suppressed from non-tolerant controls. However, analysis of VSA push-pull perfusates performed during a tolerant reaction to intravenous endotoxin revealed that increased AVP activity occurs within the first 30 min after the intravenous injection, well before the time PGE₂ or endotoxin were injected into the cerebral ventricles. This suggests that the antipyretic system is only activated briefly and may explain why centrally evoked fevers were unaffected during active endotoxin tolerance. In summary, this thesis research has demonstrated a direct functional link between the mechanism of action of antipyretic drugs and the endogenous antipyretic system within the brain. These results call into question the hypothesis whereby the fever reducing properties of antipyretic drugs can be explained exclusively as a result of the inhibition of prostaglandin biosynthesis. In addition, the differential effects on AVP release by antipyretic drugs suggests a number of biological pathways that can be activated by these drugs. Finally, a role for the AVP endogenous antiypretic system in the suppression of fever during endotoxin tolerance was established. / Medicine, Faculty of / Cellular and Physiological Sciences, Department of / Graduate

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Protein kinase C (PKC) is translocated to a phospholipid bilayer by calcium. Once at the membrane protein kinase C undergoes a conformational change which results in the removal of the pseudosubstrate domain from the active site. The enzyme then phosphorylates Ser/Thr residues on positively charged substrates. Certain substrates, however, can undergo cofactor independent phosphorylation by producing a conformational change in the enzyme in the absence of phospholipid and calcium. Studying the conformational change in PKC by physical techniques is difficult to perform with a phospholipid bilayer present. To study the conformational change in PKC in the absence of a membrane, the interactions between an Arginine-rich peptide (ARP), which underwent cofactor independent phosphorylation, and PKC was investigated. The Kₘ and kcₐₜ of the enzyme for ARP, in the absence of cofactors, was around 10 μM and 0.38 s⁻¹, respectively. The Kₘ did not significantly change upon the addition of phosphoipid and calcium. However, the kcₐₜ increased 2-3 fold in the presence of phospholipid and calcium. In the absence of phospholipid and calcium, ARP induced the exposure of hydrophobic site(s) on the enzyme. Additionally, ARP was able to promote the translocation of PKC to the membrane in the absence of calcium. PKC translocated to the membrane by ARP displayed the same susceptibility as the calcium membrane bound enzyme to limited proteolytic cleavage. Therefore, both ARP and calcium induce a similar membrane bound conformation in PKC. Additionally, the binding of ARP to PKC seems to occur through at least one high affinity site apart for the active site. These results demonstrate new insight into cofactor independent phosphorylation by PKC as well as illustrate a novel mechanism by which a substrate can promote the translocation of PKC in the absence of calcium. / Thesis / Master of Science (MSc)

In this study, we report that expression of the 𝘢𝘳𝘨𝘊𝘉𝘏 operon is induced in stationary phase cultures and that this increase is largely dependent on RpoS, the alternative stress sigma factor. Using combinatorial 𝘢𝘳𝘨𝘙 and 𝘳𝘱𝘰𝘚 mutants, we evaluated the relative contributions of these two regulators to the expression of 𝘢𝘳𝘨𝘏 using operon 𝘭𝘢𝘤𝘡 fusions. While ArgR was found to be the main factor responsible for de-repression of the 𝘢𝘳𝘨𝘊𝘉𝘏 operon, RpoS was required for full expression of this biosynthetic operon at concentrations below 10 μg arginine ml⁻¹, a level at which growth of an arginine auxotroph was arginine limited. At high arginine concentrations (>10 μg ml⁻¹) 𝘢𝘳𝘨𝘊𝘉𝘏 expression was strongly repressed as expected by ArgR. 𝘢𝘳𝘨𝘊𝘉𝘏 expression was 30 fold higher in Δ𝘢𝘳𝘨𝘙 mutants relative to a wild type fully repressed strain and this expression was independent of RpoS. These results indicate that RpoS plays an important role in the regulation of arginine biosynthesis, particularly when the operon is partially de-repressed as would be the case in starvation conditions. / Thesis / Master of Science (MS)

Thesis (Ph.D.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / In Neurospora, as in other organisms, arginine and pyrimidine biosynthesis shares the common precursor, carbamyl phosphate. The fact that some mutants require only pyrimidines for growth while others require only arginine for growth indicates the possibility of two independent modes for carbamyl phosphate synthesis and utilization. The existence of two carbamyl phosphokinases has been hypothesized to resolve the interplay of nutritional requirements for arginine and pyrimidine. One carbamyl phosphokinase catalyzes the formation of carbamyl phosphate specific for the arginine pathway and the other carbamyl phosphokinase catalyzes the formation of carbamyl phosphate specific for the pyrimidine pathway [TRUNCATED] / 2999-01-01

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