EFFECTS OF TRIMETAZIDINE ON OXIDANT/ANTIOXIDANT STATUS IN TRINITROBENZENESULFONIC ACID-INDUCED CHRONIC COLITIS

Trimetazidine (TMZ), an anti-ischemic agent with proposed antioxidant properties, was used in a chronic colitis model in order to evaluate its effectiveness as a therapeutic agent in chronic colitis. Treatment of male Swiss Albino rats with ethanol (50%) and trinitrobenzenesulfonic acid (TNBS) (30 mg/kg) produced colitis as evidenced by histopathologic damage and inflammatory alterations, lipid peroxidation [increased malondialdehyde (MDA) levels], and enhanced neutrophil infiltration [increased myeloperoxidase (MPO) activity] without marked change in glutathione status. Administration of TMZ (5 mg/kg) to TNBS-treated rats failed to affect the TNBS-induced changes in histopathology and MPO activities. Unexpectedly, intrarectal (ir) administration of TMZ significantly elevated colonic MDA levels to a greater extent than TNBS alone. Intraperitoneal (ip) TMZ treatment seemed to increase total glutathione (tGSH), GSH, and GSH/GSSG values. In conclusion, our results demonstrated that (a) ir administration of ethanol and TNBS is an effective way of inducing a chronic colitis model, (b) inflammation and lipid peroxidation augment tissue damage in the chronic colitis model, (c) ip TMZ treatment significantly inhibits MDA production in the chronic colitis model, (d) TMZ treatment is more effective via the ip compared to ir route, and (e) TMZ seems to show its antioxidant effect via preserving the tissue's GSH/GSSG ratios.     

Investigation into the role of the cholinergic system in radiation-induced damage in the rat liver and ileum

It has been previously shown that acetylcholine (ACh) may affect pro-inflammatory and anti-inflammatory cytokines. The role of the cholinergic system in radiation-induced inflammatory responses and tissue damage remains unclear. Therefore, the present study was designed to determine the radio-protective properties of the cholinergic system in the ileum and the liver of rats. Rats were exposed to 8-Gy single-fraction whole-abdominal irradiation and were then decapitated at either 36 h or 10 d post-irradiation. The rats were treated either with intraperitoneal physiological saline (1 ml/kg), physostigmine (80 µg/kg) or atropine (50 μg/kg) twice daily for 36 h or 10 d. Cardiac blood samples and liver and ileal tissues were obtained in which TNF-α, IL-1β and IL-10 levels were assayed using ELISA. In the liver and ileal homogenates, caspase-3 immunoblots were performed and myeloperoxidase (MPO) activity was analyzed. Plasma levels of IL-1β and TNF-α increased significantly following radiation (P < 0.01 and P < 0.001, respectively) as compared with non-irradiated controls, and physostigmine treatment prevented the increase in the pro-inflammatory cytokines (P < 0.01 and P < 0.001, respectively). Plasma IL-10 levels were not found to be significantly changed following radiation, whereas physostigmine augmented IL-10 levels during the late phase (P < 0.01). In the liver and ileum homogenates, IL-1β and TNF-α levels were also elevated following radiation, and this effect was inhibited by physostigmine treatment but not by atropine. Similarly, physostigmine also reversed the changes in MPO activity and in the caspase-3 levels in the liver and ileum. Histological examination revealed related changes. Physostigmine experiments suggested that ACh has a radio-protective effect not involving the muscarinic receptors.     

An anti-inflammatory drug (mefenamic acid) incorporated in biodegradable alginate beads: development and optimization of the process using factorial design

The objective of this study was to prepare and evaluate biodegradable alginate beads as a controlled-release system for a water-insoluble drug, mefenamic acid (MA), using 3 x 2(2) factorial design by ionotropic gelation method. Therefore, the mefenamic acid dispersion in a solution of alginate was dropped into the cross-linking CaCl(2) solution and a fairly high yield (71-89%) of MA-alginate beads were obtained. Their encapsulation efficiencies were in the range of 79.3-98.99%. The effect of drug:polymer ratio, CaCl(2) concentration, and curing time on the time for 50% of the drug to be released (t(50%)), and the drug entrapment efficiency were evaluated with factorial design method. It was found that drug:polymer ratio and interaction of drug:polymer ratio and curing time had an important effect on the drug to be released (t(50%)). The effect of CaCl(2) concentration is also important on the drug release. On the other hand, all factors except CaCl(2) concentration were effective on the drug entrapment efficiency. The swelling properties of beads were also studied. The release mechanism was described and found to be non-Fickian, Case II, and Super Case II transport for the formulations. This study suggested a new mefenamic acid alginate bead formulation for oral delivery of nonsteroidal anti-inflammatory drugs, which cause gastric irritation.     

Development and validation of a rapid RP-HPLC method for the determination of cetirizine or fexofenadine with pseudoephedrine in binary pharmaceutical dosage forms

Chagas disease is a serious health problem in Latin America. Hidroxymethylnitrofurazone (NFOH) is a nitrofurazone prodrug more active than nitrofurazone against Trypanosoma cruzi. However, NFOH presents low aqueous solubility, high photodecomposition and high toxicity. The present work is focused on the characterization of an inclusion complex of NFOH in 2-hydroxypropyl-β-cyclodextrin (HP-β-CD). The complexation with HP-β-CD was investigated using reversed-phase liquid chromatography, solubility isotherms and nuclear magnetic resonance. The retention behavior was analyzed on a reversed-phase C₁₈ column, using acetonitrile–water (20/80, v/v) as the mobile phase, in which HP-β-CD was incorporated as a mobile phase additive. The decrease in the retention times with increasing concentrations of HP-β-CD enables the determination of the apparent stability constant of the complex (K = 6.2 ± 0.3 M⁻¹) by HPLC. The solubility isotherm was studied and the value for the apparent stability constant (K = 7.9 ± 0.2 M⁻¹) was calculated. The application of continuous variation method indicated the presence of a complex with 1:1 NFOH:HP-β-CD stoichiometry. The photostability study showed that the formation of an inclusion complex had a destabilizing effect on the photodecomposition of NFOH when compared to that of the “free” molecule in solution. The mobility investigation (by NMR longitudinal relaxation time) gives information about the complexation of NFOH with HP-β-CD. In preliminary toxicity studies, cell viability tests revealed that inclusion complexes were able to decrease the toxic effect (p < 0.01) caused by NFOH.     

Design and synthesis of tri-ring P3 benzamide-containing aminonitriles as potent, selective, orally effective inhibitors of cathepsin K

We have prepared a series of achiral aminoacetonitriles, bearing tri-ring benzamide moieties and an aminocyclohexanecarboxylate residue at P2. This combination of binding elements resulted in sub-250 pM, reversible, selective, and orally bioavailable cathepsin K inhibitors. Lead compounds displayed single digit nanomolar inhibition in vitro (of rabbit osteoclast-mediated degradation of bovine bone). The best compound in this series, 39n (CRA-013783/L-006235), was orally bioavailable in rats, with a terminal half-life of over 3 h. 39n was dosed orally in ovariectomized rhesus monkeys once per day for 7 days. Collagen breakdown products were reduced by up to 76% dose-dependently. Plasma concentrations of 39n above the bone resorption IC50 after 24 h indicated a correlation between functional cellular and in vivo assays. Inhibition of collagen breakdown by cathepsin K inhibitors suggests this mechanism of action may be useful in osteoporosis and other indications involving bone resorption.     

A novel class of nonpeptidic biaryl inhibitors of human cathepsin K

A novel series of nonpeptidic biaryl compounds was identified as potent and reversible inhibitors of cathepsin K. The P2-P3 amide bond of a known amino acetonitrile dipeptide 1 was replaced with a phenyl ring, thereby giving rise to this biaryl series that retained potency vs cathepsin K and showed an improved selectivity profile against other cathepsins. Structural modification within this series resulted in the identification of compound (R)-2, a potent human cathepsin K inhibitor (IC(50) = 3 nM) that is selective versus cathepsins B (IC(50) = 3950 nM), L (IC(50) = 3725 nM), and S (IC(50) = 2010 nM). In an in vitro assay involving rabbit osteoclasts and bovine bone, compound (R)-2 inhibited bone resorption with an IC(50) of 95 nM. It was shown that, unlike some peptidic nitrile inhibitors of cysteine proteases, the nitrile moiety of (R)-2 is not converted to the corresponding amide 3 by cathepsin K. This indicates that this class of nonpeptidic nitrile inhibitors is unlikely to be hydrolyzed by cysteine proteases. Furthermore, the inhibition of cathepsin K by compound (R)-2 was shown to be fully reversible and not observably time-dependent. To demonstrate the efficacy of compound (R)-2 in vivo, it was administered to ovariectomized (OVX) rhesus monkeys at 20 mg/kg, po once daily for 8 days, and a urinary marker of bone turnover, N-telopeptide of type I collagen (uNTx), was measured. During the eight-day dosing period, the mean reduction by compound (R)-2 in uNTx was 80% (p < 0.001). This demonstrates that inhibition of cathepsin K leads to an inhibition of this bone resorption marker in OVX rhesus monkeys and strongly suggests that inhibition of cathepsin K is a viable therapeutic approach for the treatment of osteoporosis.     

原发性房角关闭眼激光虹膜切除术后UBM测量参数比较

目的:比较激光虹膜切开术前后原发性房角关闭(primary angle closure,PAC)眼超声生物显微镜(ultrasound biomicroscopy,UBM)参数。方法:对46例74眼PAC患者进行了一项前瞻性临床试验。平均年龄58,04±11.33(24.0-82.0)岁。所有病例行完整的眼科检查,前房角镜A超生物测量和超声生物显微镜检查(Vu-max,SonomedInc.,NY,USA)及24-2标准无色差视野检查(SAP,Humphrey Visual Field Analyzer-II i,Carl Zeiss Meditec Inc.,Dublin,CA,USA)。使用配对t检验评估基准和随访的平均值之间的变化。结果:激光周边虹膜切除术(laser peripheral iridotomy,LPI)术后,平均房角从8.02±4.61(0.10-19.60)度增加到17.66±6.39(0.10-32.70)度(P=0.000),房角开放距离500(angle opening distance 500,AOD500)从0.11±0.06(0.01-0.30)mm增加到0.23±0.07(0.13-0.50)mm(P=0.000),平均虹膜厚度(iris thickness,IT)从0.58±0.11(0.33-0.99)mm下降到0.52±0.10(0.25-0.77)mm(P=0.000)。小梁睫状突距离,虹膜睫状突距离和睫状体厚度均未发现显著统计学差异。结论:LPI术后PAC的白种人眼睛的AOD500,虹膜晶体距离和前房角增加,IT和虹膜晶体高度减少。这说明LPI解除了瞳孔阻滞,加深了前房,扩大了房角,减少了虹膜前凸和增厚。     

Urate oxidation during percutaneous transluminal coronary angioplasty and thrombolysis in patients with coronary artery disease

Thrombolysis and percutaneous transluminal coronary angioplasty (PTCA) are kinds of procedures that can be used to restore the blood flow of previously ischemic myocardium that can be the result of excessive production of reactive oxygen and nitrogen species, such as superoxide and hydroxyl radical, hypochlorous acid and peroxynitrite. Reaction of urate with some of these potent oxidants results in allantoin production. In this study, we measured the serum allantoin levels, an oxidation product of urate, and "in vivo" marker of free radical generation in reperfusion of ischemic myocardium. After an overnight fasting state, blood samples were collected from 35 patients with coronary occlusive diseases (7 women and 28 men) and 31 healthy subjects (8 women and 23 men). Serum allantoin and urate levels were measured by a GC-MS method. Serum allantoin levels of patients on PTCA therapy (mean+/-SD, 27.4 +/- 15.2 micromol/l) and thrombolytic therapy (24.6 +/- 8.6 micromol/l) were significantly higher than those of the patients without therapy (15.8 +/- 6.2 micromol/l, p < 0.05 with PTCA and p < 0.006 with thrombolysis) and healthy controls (12.6 +/- 6.3 micromol/l, p < 0.002 with PTCA and p < 0.0001 with thrombolysis). Although serum urate levels in PTCA (380.1 +/- 72.6 micromol/l) and thrombolysis (359.5 +/- 60.0 micromol/l) were higher than those in the non-therapy patients (336.6 +/- 53.8 micromol/l) and controls (318.3 +/- 81.0 micromol/l), there were no significant differences among groups (p > 0.05). The results of the study are consistent with others which have demonstrated, higher urate levels are associated with coronary occlusive diseases. Our data support the hypothesis that generation of ROS occurs during myocardial reperfusion. Increased allantoin levels may be used as an index of increased oxidative stress during reperfusion.