Vertebrate CTF18 and DDX11 essential function in cohesion is bypassed by preventing WAPL-mediated cohesin release.

The alternative PCNA loader containing CTF18-DCC1-CTF8 facilitates sister chromatid cohesion (SCC) by poorly defined mechanisms. Here we found that in DT40 cells, CTF18 acts complementarily with the Warsaw breakage syndrome DDX11 helicase in mediating SCC and proliferation. We uncover that the lethality and cohesion defects of ctf18 ddx11 mutants are associated with reduced levels of chromatin-bound cohesin and rescued by depletion of WAPL, a cohesin-removal factor. On the contrary, high levels of ESCO1/2 acetyltransferases that acetylate cohesin to establish SCC do not rescue ctf18 ddx11 phenotypes. Notably, the tight proximity of sister centromeres and increased anaphase bridges characteristic of WAPL-depleted cells are abrogated by loss of both CTF18 and DDX11 The results reveal that vertebrate CTF18 and DDX11 collaborate to provide sufficient amounts of chromatin-loaded cohesin available for SCC generation in the presence of WAPL-mediated cohesin-unloading activity. This process modulates chromosome structure and is essential for cellular proliferation in vertebrates.

Stabilization of indocyanine green dye in polymeric micelles for NIR-II fluorescence imaging and cancer treatment.

One of the most commonly used near infrared (NIR) dyes is indocyanine green (ICG), which has been extensively used for NIR bioimaging, photothermal and photodynamic therapy. However, upon excitation this dye can react with molecular oxygen to form singlet oxygen (SO), which can then cleave ICG to form non-fluorescent debris. In order to reduce the reaction between ICG and oxygen, we used energy transfer (ET) between the former and the NIR dye IR-1061. The two dyes were encapsulated in micelles composed of biocompatible poly(ethylene glycol)-block-poly(ε-caprolactone) (PCL-PEG). Micelles were characterized for their size using dynamic light scattering (DLS) and were found to measure about 35 nm in diameter. Fluorescence emission measurements were conducted to show that the stability of ICG against photodecomposition is increased. Moreover, this increased stability allows the encapsulated dye to generate more heat and for a longer time, compared to its free form. Studies with a SO indicator showed that as more IR-1061 is added to the micelles, less SO is produced. These results show how by changing the amount of added IR-1061 it is possible to tune the heat and SO generated by the system. Cell viability studies demonstrated that while particles were nontoxic under physiological conditions, upon 808 nm irradiation they become potent at eradicating MCF7 cancer cells. Moreover, it was demonstrated that both the increase of temperature and the creation of decomposition debris play a role in the cytotoxic efficacy of the micelles. Dye-loaded micelles that were injected to live mice showed bright fluorescence in the over 1000 nm NIR (OTN-NIR) region, allowing for visualization of blood vessels and internal organs. Most importantly, the encapsulated dyes remained stable for over 30 minutes, gradually accumulating in the liver and spleen. The presence of IR-1061 in addition to the heat-generating dye ICG allowed for simultaneous temperature modification and monitoring. We were able to assess the change in temperature by measuring the change in the fluorescence intensity of IR-1061 in the OTN-NIR region, a range with deep penetration of living tissues. These features illustrate the potential use of ICG/IR-1061 in PCL-PEG micelles as promising candidates for cancer treatment and diagnosis.

Biological Deep Temperature Imaging with Fluorescence Lifetime of Rare-Earth-Doped Ceramics Particles in the Second NIR Biological Window.

Contactless thermal imaging generally relies on mid-infrared cameras and fluorescence imaging with temperature-sensitive phosphors. Fluorescent thermometry in the near-infrared (NIR) region is an emerging technique for analysing deep biological tissues but still requires observation depth calibration. We present an NIR fluorescence time-gated imaging (TGI) thermometry technology based on fluorescence lifetime, an intrinsic fluorophore time constant unrelated to observation depth. Fluorophore used is NaYF4 co-doped with Nd3+ and Yb3+ that emits fluorescence at 1000 nm. An agarose gel-based phantom with the fluorophore embedded at a 5-mm depth was covered by sheets of meat to vary the observation depth. The temperature was determined independently from depth by sequences of NIR fluorescence decay images, and the rate of change in the fluorescence lifetime per temperature was almost constant (-0.0092 ~ -0.010 °C-1) at depths ranging from 0 to 1.4 mm of meat, providing non-contact and absolute measurements of temperature in deep biological tissues.

Urethral function and histopathology in aged female rats as a stress urinary incontinence model.

OBJECTIVE: Stress urinary incontinence (SUI) is a common disease condition in elderly women, suggesting that its etiology may be linked to aging. To investigate the hypothesis that urethral dysfunction and histopathological changes are possible contributors to SUI in elderly women, several parameters of urethral function, as well as histological parameters, were compared between young and aged rats. METHODS: Virgin female rats were examined at 3 different ages, namely 3, 12, and 24 months, corresponding to young, middle-aged, and aged rats, respectively. Urethral function was assessed by measuring the leak point pressure (LPP), pudendal nerve stimulation (PNS)-induced elevation in urethral pressure, and phenylephrine-induced increase in urethral perfusion pressure (UPP). Histopathological assessments were performed following hematoxylin and eosin (HE), Masson's trichrome, and immunofluorescence staining of urethral tissue. RESULTS: LPP of aged rats was significantly reduced compared to that of both young and middle-aged rats. PNS-induced elevation in urethral pressure in aged rats was also significantly lower than that in young rats. In contrast, there were no significant differences in the phenylephrine-induced increase in UPP between young and aged rats. Connective tissue area in the external urethral sphincter (EUS) layer was increased in aged rats, whereas the smooth muscle layer was histologically similar to that in young rats. The number of EUS fibers was significantly reduced in aged rats, whereas the cross-sectional area of EUS fibers increased from differed compared with young rats. CONCLUSION: We have demonstrated age-related changes in EUS function and morphology in the rat urethra, which are considered to be etiological risk factors for SUI in humans.

Warsaw breakage syndrome DDX11 helicase acts jointly with RAD17 in the repair of bulky lesions and replication through abasic sites.

Warsaw breakage syndrome, a developmental disorder caused by mutations in the DDX11/ChlR1 helicase, shows cellular features of genome instability similar to Fanconi anemia (FA). Here we report that DDX11-deficient avian DT40 cells exhibit interstrand crosslink (ICL)-induced chromatid breakage, with DDX11 functioning as backup for the FA pathway in regard to ICL repair. Importantly, we establish that DDX11 acts jointly with the 9-1-1 checkpoint clamp and its loader, RAD17, primarily in a postreplicative fashion, to promote homologous recombination repair of bulky lesions, but is not required for intra-S checkpoint activation or efficient fork progression. Notably, we find that DDX11 also promotes diversification of the chicken Ig-variable gene, a process triggered by programmed abasic sites, by facilitating both hypermutation and homeologous recombination-mediated gene conversion. Altogether, our results uncover that DDX11 orchestrates jointly with 9-1-1 and its loader, RAD17, DNA damage tolerance at sites of bulky lesions, and endogenous abasic sites. These functions may explain the essential roles of DDX11 and its similarity with 9-1-1 during development.

AND-1 fork protection function prevents fork resection and is essential for proliferation.

AND-1/Ctf4 bridges the CMG helicase and DNA polymerase alpha, facilitating replication. Using an inducible degron system in avian cells, we find that AND-1 depletion is incompatible with proliferation, owing to cells accumulating in G2 with activated DNA damage checkpoint. Replication without AND-1 causes fork speed slow-down and accumulation of long single-stranded DNA (ssDNA) gaps at the replication fork junction, with these regions being converted to DNA double strand breaks (DSBs) in G2. Strikingly, resected forks and DNA damage accumulation in G2, but not fork slow-down, are reverted by treatment with mirin, an MRE11 nuclease inhibitor. Domain analysis of AND-1 further revealed that the HMG box is important for fast replication but not for proliferation, whereas conversely, the WD40 domain prevents fork resection and subsequent DSB-associated lethality. Thus, our findings uncover a fork protection function of AND-1/Ctf4 manifested via the WD40 domain that is essential for proliferation and averts genome instability.

Tamsulosin potently and selectively antagonizes human recombinant α(1A/1D)-adrenoceptors: slow dissociation from the α(1A)-adrenoceptor may account for selectivity for α(1A)-adrenoceptor over α(1B)-adrenoceptor subtype.

We determined the binding affinity of tamsulosin, a selective α(1)-adrenoceptor antagonist, for human α(1)-adrenoceptor subtypes in comparison with those of other α(1)-adrenoceptor antagonists including silodosin, prazosin, 5-methylurapidil, terazosin, alfuzosin, nafopidil, urapidil and BMY7378. The association and dissociation kinetics of [(3)H]tamsulosin for recombinant human α(1)-adrenoceptor subtypes were compared with those of [(3)H]prazosin. Tamsulosin competitively inhibited [(3)H]prazosin binding to human α(1A)-, α(1B)- and α(1D)-adrenoceptors (pK(i) values were 10.38, 9.33, 9.85) indicating 11 and 3.4-fold higher affinities for human α(1A)-adrenoceptor than those for α(1B)- and α(1D)-adrenoceptors, respectively. The affinity of tamsulosin for the human α(1A)-adrenoceptor was, respectively, 5, 9.9, 38, 120, 280, 400, 1200 and 10000 fold higher than those of silodosin, prazosin, 5-methylurapidil, terazosin, alfuzosin, naftopidil, urapidil and BMY7378, respectively. [(3)H]Tamsulosin dissociated from the α(1A)-adrenoceptor slower than from the α(1B)- and α(1D)-adrenoceptors (α(1B)>α(1D)>α(1A)). Moreover, [(3)H]tamsulosin dissociated slower than [(3)H]prazosin from the α(1A)-adrenoceptor and faster from the α(1B)- and α(1D)-adrenoceptors. In conclusion, tamsulosin potently and selectively antagonized α(1A/1D)-adrenoceptor ligand binding, and slowly dissociated from the α(1A)-adrenoceptor subtype.

Anti-neutrophilic inflammatory activity of ASP3258, a novel phosphodiesterase type 4 inhibitor.

Neutrophil-dominant pulmonary inflammation is an important feature of chronic obstructive pulmonary disease (COPD). Here, we evaluated the in vitro and in vivo anti-neutrophilic inflammatory activities of ASP3258, a novel, orally active, and selective phosphodiesterase (PDE) 4 inhibitor with anti-inflammatory potency comparable to that of second-generation compound roflumilast but with lower emetic activity in vivo. In in vitro experiments using human peripheral blood neutrophils, PDE4 inhibitors ASP3258, cilomilast, and roflumilast inhibited fMLP-induced superoxide production in a concentration-dependent manner with IC50 values of 5.0, 96, and 4.7 nM, respectively. ASP3258, cilomilast, and roflumilast also attenuated fMLP-induced neutrophil chemotaxis in a concentration-dependent manner with IC30 values of 18, 270, and 9.7 nM, respectively. In contrast, the glucocorticoid prednisolone inhibited neither superoxide production nor chemotaxis up to 1 µM. In a rat model of lipopolysaccharide (LPS)-induced lung inflammation, orally administered ASP3258, cilomilast, roflumilast, and prednisolone (at 10 or 30 mg/kg) dose-dependently attenuated pulmonary accumulation of neutrophils. The inhibitory effect of ASP3258 was more potent than cilomilast and almost the same as roflumilast and prednisolone. Treatment with ASP3258 inhibited the elevation of TNF-α in the bronchoalveolar lavage fluid following LPS instillation. Histological examination revealed significant inhibition of neutrophil and macrophage infiltration into alveoli by ASP3258. Overall, these findings suggest that ASP3258 has therapeutic potential for treating neutrophilic inflammation such as COPD, partly through direct inhibition of neutrophil activation as well as possibly through inhibition of the TNF-α-mediated pathway.

Tacrolimus ameliorates dextran sulfate sodium-induced colitis in mice: implication of interferon-γ and interleukin-1ß suppression.

We investigated the effect of tacrolimus, a calcineurin inhibitor, on dextran sulfate sodium (DSS)-induced colitis. After inducing colitis in C57BL/6 mice by administering DSS solution as drinking water for 7 d, the animals were treated with tacrolimus. Severity of colonic inflammation was evaluated based on colon weight per unit length. Levels of cytokines (interferon (IFN)-γ, interleukin (IL)-1ß, IL-2, IL-4, IL-5, IL-6, IL-12, and tumor necrosis factor (TNF)-α) released from isolated inflamed colons of mice treated with tacrolimus or vehicle were also measured. Treatment with tacrolimus for 14 d reduced the colon weight per unit length and suppressed the release of IFN-γ and IL-1ß, but not other cytokines, in inflamed colons of colitic mice compared with vehicle-treated mice. A positive correlation was noted between colon weight per unit length and released level of IFN-γ or IL-1ß. The release of IFN-γ and IL-1ß was also suppressed after single dosing with tacrolimus to colitic mice. Taken together, these results suggested that tacrolimus ameliorated DSS-induced colitis by suppressing release of IFN-γ and IL-1ß from inflamed colon.

Preventive and therapeutic effects of tacrolimus in an interleukin-10-deficient mouse model of colitis.

OBJECTIVE: To investigate the preventive and therapeutic effects of tacrolimus on colonic inflammation in interleukin-10-deficient (IL-10(-/-)) mice, which spontaneously develop T-cell-mediated colitis. METHODS: Tacrolimus or prednisolone, an anti-inflammatory glucocorticoid, was administered to IL-10(-/-) mice with pre- or post-symptomatic colitis. Effects on colonic inflammation were examined by measuring indices of colitis such as colonic weight/length ratio, cell infiltration, and goblet cell depletion. Effects on cytokine production in colonic lamina propria mononuclear cells (LPMCs) isolated from IL-10(-/-) mice were also examined. RESULTS: Tacrolimus prevented development of colitis and improved already-developed colitis. Prednisolone prevented the development of colitis, but had no effect on already-developed colitis. Tacrolimus completely inhibited IFN-γ and TNF-α production of activated T-cells in LPMCs, but only partially inhibited IFN-γ, TNF-α, and IL-12 production of activated monocytes/macrophages in LPMCs. Prednisolone inhibited cytokine production in both cell types but exhibited greater potency on monocytes/macrophages than on T-cells. CONCLUSION: These results suggest that the preventive and therapeutic effect of tacrolimus in IL-10(-/-) mice colitis might be attributed to the inhibition of colonic T-cell activation rather than monocyte/macrophage activation. T-cell immunosuppression may thus be a promising strategy for treating colonic inflammation.

Disease-modifying effect of ASP3258, a novel phosphodiesterase type 4 inhibitor, on subchronic cigarette smoke exposure-induced lung injury in guinea pigs.

ASP3258 is a novel, orally active, selective phosphodiesterase (PDE) 4 inhibitor which has an improved therapeutic window over second generation compounds such as roflumilast and cilomilast. Here, we investigated the effect of ASP3258 on cigarette smoke exposure-induced lung injury in guinea pigs, a well-defined model for chronic obstructive pulmonary disease (COPD). COPD-like lung injury was induced by repeated cigarette smoke exposure (10 cigarettes/day, 5 days/week, for 4 weeks). Orally administered ASP3258 (0.3, 1, and 3mg/kg) dose-dependently suppressed pulmonary accumulation of mononuclear cells and neutrophils, and the inhibitory effect of ASP3258 (1mg/kg) was almost the same as that of roflumilast (1mg/kg). In contrast, a glucocorticoid prednisolone (10mg/kg, p.o.) did not show any effect. Histological examination revealed that ASP3258 treatment significantly inhibited infiltration of neutrophils and macrophages into either or both alveolar or peribronchiolar areas, as well as hyperplastic and squamous metaplastic changes of epithelium in the bronchi. Decreasing trends in histological scores for accumulation of lymphocytes in the alveoli and alveolar wall thickening were also observed in ASP3258-treated animals. Further, ASP3258 attenuated augmentation of matrix metalloproteinase-9 activity in the bronchoalveolar lavage fluid. These findings suggest that ASP3258 has therapeutic potential for treating COPD not only through inhibition of pulmonary cellular accumulation but also by preventing lung structural alterations initiated by repeated cigarette smoke exposure. To our knowledge, this is the first paper demonstrating that PDE4 inhibitors exert significant inhibitory effects on subchronic cigarette smoke exposure-induced lung injury in guinea pigs.

Unique "delta lock" structure of telmisartan is involved in its strongest binding affinity to angiotensin II type 1 receptor.

Angiotensin II type 1 receptor (AT1 receptor) blockers (ARBs) are one of the most popular anti-hypertensive agents. Control of blood pressure (BP) by ARBs is now a therapeutic target for the organ protection in patients with hypertension. Recent meta-analysis demonstrated the possibility that telmisartan was the strongest ARB for the reduction of BP in patients with essential hypertension. However, which molecular interactions of telmisartan with the AT1 receptor could explain its strongest BP lowering activity remains unclear. To address the issue, we constructed models for the interaction between commonly used ARBs and AT1 receptor and compared the docking model of telmisartan with that of other ARBs. Telmisartan has a unique binding mode to the AT1 receptor due to its distal benzimidazole portion. This unique portion could explain the highest molecular lipophilicity, the greatest volume distribution and the strongest binding affinity of telmisartan to AT1 receptor. Furthermore, telmisartan was found to firmly bind to the AT1 receptor through the unique "delta lock" structure. Our present study suggests that due to its "delta lock" structure, telmisartan may be superior to other ARBs in halting cardiovascular disease in patients with hypertension.

The forefront for novel therapeutic agents based on the pathophysiology of lower urinary tract dysfunction: ameliorative effect of solifenacin succinate (Vesicare), a bladder-selective antimuscarinic agent, on overactive bladder symptoms, especially urgency episodes.

Overactive bladder (OAB) syndrome is a common condition that is most often observed in the elderly. Pharmacological treatment with muscarinic receptor antagonists has been most widely used for OAB. An antimuscarinic agent, solifenacin, showed the highest affinity for the muscarinic M(3) receptor, which mediates urinary bladder contraction. In preclinical studies, solifenacin exhibited a highly bladder-selective profile compared with other antimuscarinic agents. Solifenacin was also shown to increase bladder capacity without affecting residual urine in an OAB model of rats. Urgency is now considered to result from overactivation of afferent nerves from the urinary bladder. It has been reported that afferent nerves are located adjacent to the urothelium, and stimulation of muscarinic receptors expressed on the urothelium may contribute to the activation of afferent nerves via non-neuronal ATP release. Solifenacin produces its inhibitory effect on bladder afferent activity partly via the suppression of non-neuronal ATP release. Clinically, solifenacin ameliorates all symptoms in OAB patients; and in particular, it produces a significant decrease in urgency episodes, which is the principal symptom of OAB. The pharmacological profile of solifenacin is therefore considered to contribute to its beneficial effects of high efficacy against OAB symptoms with good tolerability.

Effects of the dipeptidyl peptidase-IV inhibitor ASP8497 on glucose tolerance in animal models of secondary failure.

UNLABELLED: Sulfonylureas promote insulin secretion and potently lower blood glucose levels, however, they induce hypoglycemia and undergo a reduction in efficacy when administered long-term (secondary failure). The dipeptidyl peptidase (DPP)-IV inhibitor ASP8497, (2S,4S)-4-fluoro-1-({[4-methyl-1-(methylsulfonyl)piperidin-4-yl]amino}acetyl)pyrrolidine-2-carbonitrile monofumarate, inhibits the degradation of glucagon-like peptide-1 (GLP-1), an incretin hormone, and promotes insulin secretion in a glucose-dependent manner. ASP8497 is therefore less likely to induce hypoglycemia and less likely to show reduced efficacy even after repeated administration. Here, to determine whether or not ASP8497 improves glucose tolerance in Zucker fatty rats, we examined the effects of ASP8497 and gliclazide, a sulfonylurea, on glucose tolerance after repeated administration. We also developed an animal model of secondary failure using streptozotocin-nicotinamide-induced diabetic mice. RESULTS: ASP8497 (3mg/kg) improved glucose intolerance in Zucker fatty rat without any attenuation (blood glucose AUC: P=0.034 vs. vehicle) while gliclazide (10mg/kg) did not (P=0.916 vs. vehicle). Furthermore, ASP8497 (3, 10mg/kg) was found to effect glucose tolerance dose-dependently (3mg/kg: P=0.230, 10mg/kg: P=0.003 vs. glibenclamide (10mg/kg)) by enhancing insulin secretion in mice inadequately controlled with glibenclamide. Our results suggest that ASP8497 may be effective even in patients with secondary failure who are unable to maintain satisfactory glycemic control using sulfonylureas.

The dopaminergic stabilizer ASP2314/ACR16 selectively interacts with D2(High) receptors.

Dopaminergic stabilizers are recognized as compounds that can either enhance or antagonize dopamine (DA)-dependent behaviors depending on the prevailing dopaminergic tone. The dopaminergic stabilizer ASP2314 is being tested clinically and has been reported to have antipsychotic effects in a clinical trial as an add on medication. To elucidate the mechanisms of action of this dopaminergic stabilizer, its potency on the functional dopamine D2(High) receptors was examined. In competition with D2 receptors selectively labeled by [3H]domperidone, ASP2314 had a dissociation constant, Ki(High), of 1.62 microM for D2(High) in human cloned D2Long receptors and 0.83 muM for rat homogenized striata. Using the D2 agonist ligand [3H](+)-4-propyl-3,4,4a,5,6,10b-hexahydro-2H-naphtho[1,2-b][1,4]oxazin-9-ol ((+)PHNO), ASP2314 had a high-affinity Ki of 32 nM for D2(High) for rat homogenized striata. ASP2314 stimulated the incorporation of [35S]GTP-gamma-S into rat striata by 50% at 43 nM, and into the cloned D2Long membranes by 50% at 3.2 microM (compared to 100% stimulation by 10 microM dopamine). With similar concentrations of ASP2314 inhibiting the binding of ligands at D2(High) and stimulating [35S]GTP-gamma-S incorporation, the data indicate that the dopaminergic stabilizing action of ASP2314 may be related to the selectivity for the D2(high) state of the D2 receptor.

New topics in vasopressin receptors and approach to novel drugs: research and development of conivaptan hydrochloride (YM087), a drug for the treatment of hyponatremia.

Hyponatremia is the most common electrolyte disorder in hospitalized patients and is associated with the risk of intractable seizures and death. The effectiveness of conventional therapies for hyponatremia is inconsistent, and the rapid correction of plasma sodium levels is thought to result in the occurrence of neurological complications. Arginine vasopressin (AVP) is the primary regulator of renal electrolyte-free water reabsorption via AVP-receptor type 2 (V2-R), and inappropriate or excessive AVP secretion independent of serum osmolality frequently causes excessive water retention, which is the etiological basis of hyponatremia. Therefore, the use of V2-R antagonists as anti-hyponatremic drugs in the clinical setting is anticipated to be reliable and safe. Conivaptan hydrochloride (YM087) is a novel dual AVP-R antagonist for AVP-R types 1a (V1a) and V2-R. In vitro studies have shown that it possesses high affinity for V1a-R and V2-R without any species differences. It also potently inhibited AVP-induced intracellular signaling through human V2 and V1a receptors with no agonistic activity. Conivaptan hydrochloride improved the plasma sodium concentration and plasma osmolality in hyponatremic rats, and its effectiveness was demonstrated in hyponatremic patients. This drug has been approved for use in the United States, which will bring relief to patients with hyponatremia.

Micro-CT imaging analysis for the effect of celecoxib, a cyclooxygenase-2 inhibitor, on inflammatory bone destruction in adjuvant arthritis rats.

Cyclooxygenase (COX)-2 is known to play an important role in the differentiation and maturation of osteoclasts. However, the role of COX-1 in bone metabolism has not been well explored. In this study, the bone-conserving effects of COX-2-specific (celecoxib), COX-nonselective (loxoprofen), and COX-1-specific agents (SC-58560) were compared using an adjuvant-induced arthritis (AIA) rat model. Arthritis was induced by injecting 50 microl liquid paraffin containing 1 mg Mycobacterium butyricum into the left footpad of Lewis rats. Drugs were given orally twice daily for 10 days beginning 15 days after adjuvant injection. Celecoxib was administered at the rate of 3 mg/kg per day, loxoprofen at 3 mg/kg per day, and SC-58560 at 10 mg/kg per day. The therapeutic effects on 3-D architectural bone changes in the arthritic condition, e.g., the bone volume/total tissue volume ratio and the amount of trabecular bone pattern factor, were determined by analyzing the hindpaw calcaneus of AIA rats using microcomputed tomography (micro-CT). In addition, dual-energy X-ray absorptiometry 2-D bone analysis was performed to compare with micro-CT analysis. AIA rats are prone to substantial bone erosion, which allows for significant changes in the 3-D architectural index. This inflammatory bone destruction was suppressed potently by celecoxib, only moderately by loxoprofen, and not at all by SC-58560. These data suggest that COX-2 plays an important role in the inflammatory bone destruction that occurs with rheumatoid arthritis. The results also suggest that COX-2 is more effective than COX-1 at suppressing the destruction of bone associated with arthritis.