- About
-
The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
provided by the
Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
Search results
Showing 1 to 5 of 5 (0.061 seconds)Spelling suggestions: "subject:"; enzyme inhibitors; pharmacology"" "subject:"; enzyme inhibitors; pharmacologyc""
| 1 |
HIV-1 reverse transcriptase as a target in the development of specific enzyme inhibitors /Zhang, Hong. January 1900 (has links)
Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 9 uppsatser.
|
| 2 |
Rat angiotensin-converting enzyme : tissue specific expression during pharmacological inhibitionBrice, Edmund Andrew William January 1995 (has links)
The renin-angiotensin system plays a central role in the maintenance of blood pressure. Angiotensin II, the main effector of this system, results from the action of angiotensin-converting enzyme (ACE) on angiotensin I. Angiotensin II, maintains vasomotor tone via its vasoconstrictor action, and also increases salt and water retention by stimulating the release of aldosterone. ACE inhibitors, such as captopril, enalapril and lisinopril, are highly effective in the treatment of hypertension and congestive cardiac failure. Previous studies have suggested that angiotensin converting enzyme (ACE) production may be enhanced during pharmacological inhibition of the enzyme. Little is known, however about the mechanism of this induction. After demonstrating increases in circulating ACE protein in cardiac failure patients receiving the ACE inhibitor captopril, a rat model was used to study this effect. A sensitive enzyme linked immunosorbent assay for rat ACE was developed and a partial cDNA for rat ACE cloned to enable examination of ACE mRNA and protein expression during enzyme inhibition with enalapril. Rat lung ACE mRNA increased by 156% (p<0.05) and ACE protein doubled within 3 hours of administering a single dose of enalapril. Testicular ACE mRNA also increased by 300% (p<0.05) within 2 hours and returned to pretreatment levels by 6 hours. The angiotensin II antagonist saralasin similarly caused a significant (p<0.0001) 800% enhancement of mRNA expression. Aldosterone pretreatment of rats prior to enalapril administration was found to abolish this mRNA induction. These findings indicate that increased ACE expression during inhibition results from reduced levels of angiotensin II with consequent reduced stimulation of the angiotensin 11 receptor and its effects, such as aldosterone release. This suggests that ACE levels are regulated by a negative feedback loop involving the distal components of the renin-angiotensin system, namely angiotensin II and aldosterone. In situ hybridisation and immunohistochemical techniques were employed to localise the site of this inductive response in rat tissue sections. It was found that lung macrophages were markedly induced to produce ACE, as was ACE in seminiferous tubules. ACE induction was also noted in the expected sites of renal tubular epithelium and glomerular tissue. Interestingly, ACE expression was also enhanced in cardiac valves. In these studies it has been conclusively demonstrated that new ACE expression is induced by enzyme inhibitor therapy. A variety of techniques have been developed that will allow futher study of ACE in rat tissues.
|
| 3 |
Biguanide metformin acts on tau phosphorylation via mTOR/protein phosphatase 2A (PP2A) signalingKickstein, E., Krauss, S., Thornhill, P., Rutschow, D., Zeller, R., Sharkey, J., Williamson, Ritchie, Fuchs, M., Kohler, A., Glossmann, H., Schneider, R., Sutherland, C., Schweiger, S. January 2010 (has links)
Hyperphosphorylated tau plays an important role in the formation of neurofibrillary tangles in brains of patients with Alzheimer's disease (AD) and related tauopathies and is a crucial factor in the pathogenesis of these disorders. Though diverse kinases have been implicated in tau phosphorylation, protein phosphatase 2A (PP2A) seems to be the major tau phosphatase. Using murine primary neurons from wild-type and human tau transgenic mice, we show that the antidiabetic drug metformin induces PP2A activity and reduces tau phosphorylation at PP2A-dependent epitopes in vitro and in vivo. This tau dephosphorylating potency can be blocked entirely by the PP2A inhibitors okadaic acid and fostriecin, confirming that PP2A is an important mediator of the observed effects. Surprisingly, metformin effects on PP2A activity and tau phosphorylation seem to be independent of AMPK activation, because in our experiments (i) metformin induces PP2A activity before and at lower levels than AMPK activity and (ii) the AMPK activator AICAR does not influence the phosphorylation of tau at the sites analyzed. Affinity chromatography and immunoprecipitation experiments together with PP2A activity assays indicate that metformin interferes with the association of the catalytic subunit of PP2A (PP2Ac) to the so-called MID1-alpha4 protein complex, which regulates the degradation of PP2Ac and thereby influences PP2A activity. In summary, our data suggest a potential beneficial role of biguanides such as metformin in the prophylaxis and/or therapy of AD.
|
| 4 |
Resveratrol-mediated SIRT-1 interactions with p300 modulate receptor activator of NF-kappaB ligand (RANKL) activation of NF-kappaB signaling and inhibit osteoclastogenesis in bone-derived cellsShakibaei, M., Buhrmann, C., Mobasheri, A. January 2011 (has links)
Resveratrol is a polyphenolic phytoestrogen that has been shown to exhibit potent anti-oxidant, anti-inflammatory, and anti-catabolic properties. Increased osteoclastic and decreased osteoblastic activities result in bone resorption and loss of bone mass. These changes have been implicated in pathological processes in rheumatoid arthritis and osteoporosis. Receptor activator of NF-kappaB ligand (RANKL), a member of the TNF superfamily, is a major mediator of bone loss. In this study, we investigated the effects of resveratrol on RANKL during bone morphogenesis in high density bone cultures in vitro. Untreated bone-derived cell cultures produced well organized bone-like structures with a bone-specific matrix. Treatment with RANKL induced formation of tartrate-resistant acid phosphatase-positive multinucleated cells that exhibited morphological features of osteoclasts. RANKL induced NF-kappaB activation, whereas pretreatment with resveratrol completely inhibited this activation and suppressed the activation of IkappaBalpha kinase and IkappaBalpha phosphorylation and degradation. RANKL up-regulated p300 (a histone acetyltransferase) expression, which, in turn, promoted acetylation of NF-kappaB. Resveratrol inhibited RANKL-induced acetylation and nuclear translocation of NF-kappaB in a time- and concentration-dependent manner. In addition, activation of Sirt-1 (a histone deacetylase) by resveratrol induced Sirt-1-p300 association in bone-derived and preosteoblastic cells, leading to deacetylation of RANKL-induced NF-kappaB, inhibition of NF-kappaB transcriptional activation, and osteoclastogenesis. Co-treatment with resveratrol activated the bone transcription factors Cbfa-1 and Sirt-1 and induced the formation of Sirt-1-Cbfa-1 complexes. Overall, these results demonstrate that resveratrol-activated Sirt-1 plays pivotal roles in regulating the balance between the osteoclastic versus osteoblastic activity result in bone formation in vitro thereby highlighting its therapeutic potential for treating osteoporosis and rheumatoid arthritis-related bone loss.
|
| 5 |
Molecular Regulation of Interleukin-13 and Monocyte Chemoattractant Protein-1 Expression in Human Mast Cells by Interleukin-1betaLee, Steven A., Fitzgerald, S M., Huang, Shau K., Li, Chuanfu, Chi, David S., Milhorn, Denise M., Krishnaswamy, Guha 01 September 2004 (has links)
Mast cells play pivotal roles in immunoglobulin (Ig) E-mediated airway inflammation, expressing interleukin (IL)-13 and monocyte chemoattractant protein-1 (MCP-1), which in turn regulate IgE synthesis and/or inflammatory cell recruitment. The molecular effects of IL-1beta on cytokine expression by human mast cells (HMC) have not been studied well. In this report, we provide evidence that human umbilical cord blood-derived mast cells (CBDMC) and HMC-1 cells express the type 1 receptor for IL-1. We also demonstrate that IL-1beta and tumor necrosis factor-alpha are able to induce, individually or additively, dose-dependent expression of IL-13 and MCP-1 in these cells. The induction of IL-13 and MCP-1 gene expression by IL-1beta was accompanied by the activation of IL-1 receptor-associated kinase and translocation of the transcription factor, nuclear factor (NF) kappaB into the nucleus. Accordingly, Bay-11 7082, an inhibitor of NF-kappaB activation, inhibited IL-1beta-induced IL-13 and MCP-1 expression. IL-1beta also induced IL-13 promoter activity while enhancing the stability of IL-13 messenger RNA transcripts. Dexamethasone, a glucocorticoid, inhibited IL-1beta-induced nuclear translocation of NF-kappaB and also the secretion of IL-13 from mast cells. Our data suggest that IL-1beta can serve as a pivotal costimulus of inflammatory cytokine synthesis in human mast cells, and this may be partly mediated by IL-1 receptor-binding and subsequent signaling via nuclear translocation of NF-kappaB. Because IL-1beta is a ubiquitously expressed cytokine, these findings have important implications for non-IgE-mediated signaling in airway mast cells as well as for innate immunity and airway inflammatory responses, such as observed in extrinsic and intrinsic asthma.
|
Page generated in 0.0782 seconds