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This study tested the hypothesis that administration of deracoxib, a cyclooxygenase-2 specific (COX-2) inhibitor, would result in lower gastric lesion scores than administration of buffered aspirin and gastric lesion scores similar to placebo when administered to healthy dogs for 28 days. Twenty-four, healthy, random source dogs were divided into three groups. Group I received buffered aspirin, 23.6 mg/kg PO q 8h, group II received deracoxib, 1.6 mg/kg PO q 24h and placebo twice daily PO q 8h after deracoxib administration, and group III received placebo PO q 8h. Gastroscopy was performed on days -7, 6, 14, and 28 of treatment. Four regions of the stomach (pylorus, incisura, cardia, and body) were evaluated separately and lesions scored on a scale of 1 (mucosal hemorrhage) to 12 (perforating ulcer) by an observer unaware of which treatments the dogs received. Dogs were observed every 8 hours for vomiting, diarrhea and anorexia. Feces were scored from 1-5 (scores <4 were considered diarrhea). Lesion scores for each group, at each location, and total scores, at each time period, were evaluated for the effects of time and treatment using a Kruskal-Wallis test. Total dog days of vomiting and dog days of diarrhea in each group were compared using a Wilcoxon rank sums test. Significance was determined at p<0.05. Significantly higher median total gastric lesion scores were found in the aspirin group compared to the deracoxib or placebo groups on days 6, 14, and 28. There were no significant differences in median total gastric lesion scores between the deracoxib or placebo groups at any time during the study. There was no location effect on gastric lesion scores and there was no significant change in gastric lesion scores over time in any of the groups during treatment. Significantly more dog-days of vomiting occurred in the aspirin group as compared to the deracoxib group. No significant differences were found between groups for dog-days of diarrhea. In this study, the administration of deracoxib to healthy dogs resulted in significantly lower gastric lesion scores compared to dogs receiving aspirin and lesion scores similar to those receiving placebo. / Master of Science

No / Prostaglandins are potent mediators of the inflam-matory response and are also involved in cancer development. In this study, we show that human melanocytes and FM55 melanoma cells express cyclooxygenase-1 and -2 (COX-1 and-2) and thus have the capability to produce prostaglandins. TheFM55 cells produced predominantly PGE2and PGF2a, whereas the HaCaT keratinocyte cell line produced mainly PGE2. The anti-inflammatory peptide, a-melanocyte stimulating hormone(a-MSH), reduced prostaglandin production in FM55 and HaCaT cells and reversed the effect of the pro-inflammatory cytokine TNF-a in the former. These results indicate that melanocytes produce prostaglandins and that a-MSH, by inhibiting this response, may play an important role in regulating inflammatory responses in the skin.

No / Cryptolepis sanguinolenta and its bioactive alkaloid, cryptolepine have shown anti-inflammatory activity. However, the underlying mechanism of anti-inflammatory action in neuronal cells has not been investigated. In the present study we evaluated an extract of C. sanguinolenta (CSE) and cryptolepine (CAS) on neuroinflammation induced with IL-1β in SK-N-SH neuroblastoma cells. We then attempted to elucidate the mechanisms underlying the anti-neuroinflammatory effects of CAS in SK-N-SH cells. Cells were stimulated with 10 U/ml of IL-1β in the presence or absence of different concentrations of CSE (25–200 μg/ml) and CAS (2.5–20 μM). After 24 h incubation, culture media were collected to measure the production of PGE2 and the pro-inflammatory cytokines (TNFα and IL-6). Protein and gene expressions of cyclooxygenase (COX-2) and microsomal prostaglandin synthase-1 (mPGES-1) were studied by immunoblotting and qPCR, respectively. CSE produced significant (p < 0.05) inhibition of TNFα, IL-6 and PGE2 production in SK-N-SH cells. Studies on CAS showed significant and dose-dependent inhibition of TNFα, IL-6 and PGE2 production in IL-1β-stimulated cells without affecting viability. Pre-treatment with CAS (10 and 20 μM) was also found to inhibit IL-1β-induced protein and gene expressions of COX-2 and mPGES-1. Further studies to determine the mechanism of action of CAS showed inhibition of NF-κBp65 nuclear translocation, but not IκB phosphorylation. At 10 and 20 μM, CAS inhibited IL-1β-induced phosphorylation of p38 MAPK. Studies on the downstream substrate of p38, MAPK-activated protein kinase 2 (MAPKAPK2) showed that CAS produced significant (p < 0.05) and dose dependent inhibition of MAPKAPK2 phosphorylation in IL-1β-stimulated SK-N-SH cells. This study clearly shows that cryptolepine (CAS) inhibits neuroinflammation through mechanisms involving inhibition of COX-2 and mPGES-1. It is suggested that these actions are probably mediated through NF-κB and p38 signalling.

Yu, Le. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 171-198). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese.

Based on the results aforementioned, I went on in the second part of the study to examine the impact of aging on EDCF-mediated contractions - the alterations of COX-2-mediated endothelium-dependent contractions and the associated release of prostaglandin(s) in the aortae from aged (>18 month-old) hamsters. Endothelium-dependent contractions in the presence of NG-nitro-L-arginine methyl ester (L-NAME) were significantly greater in the aortae from aged hamsters and contractions could also be observed without L-NAME, which were sensitive to COX-2 inhibitors and TP receptor antagonists. The levels of COX-2 expression, the release of PGF2alpha and vascular sensitivity to PGF 2alpha were augmented in aortae of aged hamsters. The present results indicate a positive impact of aging on COX-2-derived PGF2alpha-mediated endothelium-dependent contractions. / In the first part of the study, I investigated whether COX-2 participated in the occurrence of endothelium-dependent contractions in the aortae from young (-3 month-old) hamsters and identified the most possible EDCF. Endothelium-dependent contractions were elicited by acetylcholine and abolished by COX-2 inhibitors (NS-398, DuP-697 and celecoxib) and thromboxane-prostanoid (TP) receptor antagonists (S 18886, L-655,240 and GR 32191), but not by COX-1 inhibitors (valeryl salicylate and sc 560). RT-PCR and Western blot analysis using aortae with and without endothelium revealed that the COX-2 expression was localized mainly in the endothelium. Levels of prostangladin F2alpha (PGF2alpha ) and prostacyclin (PGI2) increased in response to acetylcholine and the release of both prostaglandins was inhibited by COX-2 but not COX-1 inhibitors. Exogenous PGF2alpha but not PGI2 caused contractions at a concentration that corresponded to the amount released endogenously. The release of PGF2alpha was not affected by the presence of nitric oxide (NO). The results of the present study suggest that a novel constitutive role of COX-2 in endothelium-dependent contractions, with its metabolites PGF2alpha acting as a physiological EDCF in the young hamster aortae. / In the third part of the study, I investigated the relationship and the intracellular signaling cascades linking two pro-inflammatory factors Ang II and COX-2, and tested whether COX-2 mediated the Ang II-induced vascular pathogenesis. Eight hour-incubation with 100 nmol/L Ang II resulted in maximal COX-2 expression in primary rat endothelial cells and it was inhibited by losartan and RNA synthesis inhibitor (actinomycin-D). Inhibitors of either p38 MAPK or ERK1/2 (respectively SB 202190 and PD 98059) decreased the COX-2 expression, and co-treatment with both inhibitors caused an additive effect, suggesting a joint mediation through both kinases. Protein kinase C (PKC) inhibitor (GF109203X), and particularly, the specific PKCdelta inhibitor (rottlerin), prevented Ang II-induced phosphorylation of ERK1/2 and COX-2 expression, indicating an upstream regulation of ERK1/2 by PKC delta. A pivotal role of PKCdelta in Ang II-induced COX-2 expression was further supported by a similar stimulatory effect of PKC activator, signified by the Ang II-stimulated translocation of PKCdelta to the membrane and confirmed by its phosphorylation (Tyr311). Small interfering RNA targeting PKCdelta (siPKCdelta) diminished COX-2 expression, which was abrogated in siPKCdelta-treated cells treated with SB 202190, confirming the parallel pathways of PKC delta-ERK1/2 and p38 MAPK. Aortae and renal arteries from Ang II-infused rats exhibited an increased endothelial COX-2 expression and impaired acetylcholine-induced relaxation that was normalized by celecoxib. Human mesenteric arteries incubated with Ang II demonstrated elevated endothelial COX-2 and MCP-1 expressions, of which the former was inhibited by SB 202190 plus rottlerin and the latter prevented by COX-2 inhibitor celecoxib. Renal arteries from hypertensive or diabetic patients revealed an exaggerated expression of COX-2 and MCP-1 in the endothelium. The present novel findings indicate that the activation of PKCdelta-ERK1/2 and p38 MAPK is critical in Ang II-induced COX-2 up-regulation in endothelial cells, and identify a COX-2-dependent pro-atherosclerotic cytokine MCP-1. (Abstract shortened by UMI.) / Wong, Siu Ling. / Adviser: Huang Yu. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 192-228). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Wong, Wing Tak Jack. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 204-227). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Objective: To appraise whether adverse events following oral implant placement may be associated with peri-operative use of non-steroidal anti-inflammatory drugs (NSAIDs). Methods: All patients with recorded implant failures between 1979 and 2012 in the Implant Prosthodontics Unit were contacted to solicit additional information about potential peri-operative use of NSAIDs. Results: From a total of 168 patients with 292 implant failures between 1979 and 2012, 122 consented to participate and had intact records. Just over half (56.6%) reported no peri-operative NSAID usage. However, compared to patients who did not use peri-operative NSAIDs, four times as many had complicated medical histories and twice as many patients taking NSAIDs suffered multiple implant failures. Conclusions: Patients with a variety of systemic diseases may be adversely affected by the inhibitory effect of NSAIDs on bone healing. Further prospective clinical studies are warranted to clarify this potential causative relationship in humans.

Objective: To appraise whether adverse events following oral implant placement may be associated with peri-operative use of non-steroidal anti-inflammatory drugs (NSAIDs). Methods: All patients with recorded implant failures between 1979 and 2012 in the Implant Prosthodontics Unit were contacted to solicit additional information about potential peri-operative use of NSAIDs. Results: From a total of 168 patients with 292 implant failures between 1979 and 2012, 122 consented to participate and had intact records. Just over half (56.6%) reported no peri-operative NSAID usage. However, compared to patients who did not use peri-operative NSAIDs, four times as many had complicated medical histories and twice as many patients taking NSAIDs suffered multiple implant failures. Conclusions: Patients with a variety of systemic diseases may be adversely affected by the inhibitory effect of NSAIDs on bone healing. Further prospective clinical studies are warranted to clarify this potential causative relationship in humans.