Treatment of mares with the non-steroidal anti-inflammatory drug (NSAID) phenylbutazone transiently affects in vitro maturation of equine oocytes and blastocyst development after Intracytoplasmic Sperm Injection (ICSI)

Mares enrolled in assisted reproductive technologies (ARTs) programs are often treated with non-steroidal anti-inflammatory drugs (NSAIDs), particularly phenylbutazone (Bute), due to chronic lameness. The current study was performed to determine the effect of Bute administration on the developmental competence of in vitro-matured equine oocytes subjected to Intracytoplasmic Sperm Injection (ICSI). In a Preliminary Study, immature cumulus-oocyte complexes (COCs) recovered by post-mortem ovary harvested from two healthy mares (n = 2) treated for 10 days with Bute (4.4 mg/kg, PO, BID), and four non-treated healthy mares (n = 4), were matured in vitro and subjected to Piezo-driven ICSI. Lower oocyte in vitro maturation [Bute: 25% (3/12) vs. Control: 61% (28/46)] and blastocyst rates [Bute: 0% (0/12) vs. Control: 18% (5/28)] were observed in the Bute-treated when compared to the Control mares (P < 0.05). In the Main Experiment, a group of healthy mares (n = 9) received a daily dose of Bute (4.4 mg/kg, orally, SID) for 10 days. A control group of mares (n = 10) was treated with an equal volume of placebo. Mares in both groups were subjected to ultrasound-guided transvaginal oocyte aspiration (TVA) on days 3, 33, and 77 following the last dose of Bute (PT). Recovered COCs from both mare groups were matured in vitro and subjected to Piezo-driven ICSI. By day-3 PT, oocyte in vitro maturation rate was similar between mare groups [Bute: 65% (36/55) vs. Control: 67% (78/116); P > 0.05], while oocyte recovery [Bute: 53% (55/103) vs. Control: 70% (116/166)], cleavage [Bute: 31% (11/36) vs. Control: 62% (48/78)] and blastocyst rates [Bute: [0%] (0/36) vs. Control: 28% (22/78)] were significantly different (P < 0.05). By day 33 PT and 77 PT, differences on oocyte recovery, in vitro maturation, cleavage, and blastocyst rates were not observed between mare groups. In summary, the administration of Bute for 10 consecutive days (4.4 mg/kg, PO, SID, or BID) is associated with a decrease in the ability of immature equine oocytes to undergo in vitro-maturation (Preliminary Study) and develop to the blastocyst stage following ICSI (Preliminary Study and Main Experiment). This negative effect appeared to be transient, as 30- and 77-days post-treatment, no differences on in vitro maturation, cleavage or blastocyst rates were observed.

Effects of phenylbutazone, firocoxib, and dipyrone on the diuretic response to furosemide in horses

BACKGROUND

Treatment with phenylbutazone (nonselective COX inhibitor) decreases the diuretic and natriuretic effects of furosemide by nearly 30% but the effects of COX-2 specific inhibitors (firocoxib) and atypical NSAIDs (dipyrone) are unknown.

HYPOTHESIS

Furosemide-induced diuresis after pretreatment with firocoxib or dipyrone is diminished to a lesser extent than after pretreatment with phenylbutazone.

ANIMALS

Eight healthy mares.

METHODS

Each mare received 4 treatments in a prospective experimental crossover study using a replicated 4 × 4 Latin Square design: furosemide alone (FU), furosemide and phenylbutazone (PB), furosemide and firocoxib (FX), and furosemide and dipyrone (DP). After 24 hours of NSAID treatment at recommended dosages, ureteral catheters were placed for continual urine collection. After a 30-minute baseline collection period, furosemide (1.0 mg/kg, IV) was administered, and urine and blood samples were collected for 4 hours. Data were assessed by repeated measures ANOVA.

RESULTS

Four-hour urine volume was (mean ± SD) ~25% less (P < .001) after pretreatment with all NSAIDs (PB 19.1 ± 2.1 mL/kg, FX 17.7 ± 3.5 mL/kg, DP 19.1 ± 3.9 mL/kg), as compared to FU (23.4 ± 5.1 mL/kg) (P < .001), but there were no differences between PB, FX, or DP. Interindividual variability in furosemide diuresis after pretreatment with different NSAIDs was observed.

CONCLUSIONS AND CLINICAL IMPORTANCE

Though COX-2 selective NSAIDs and dipyrone might have less severe or fever gastrointestinal adverse effects in horses, our data suggest minimal differences in effects on furosemide-induced diuresis, and possibly, risk of nephrotoxicosis.

Toward of Safer Phenylbutazone Derivatives by Exploration of Toxicity Mechanism

A drug design for safer phenylbutazone was been explored by reactivity and docking studies involving single electron transfer mechanism, as well as toxicological predictions. Several approaches about its structural properties were performed through quantum chemistry calculations at the B3LYP level of theory, together with the 6-31+G(d,p) basis sets. Molecular orbital and ionization potential were associated to electron donation capacity. The spin densities contribution showed a preferential hydroxylation at the para-positions of phenyl ring when compared to other positions. In addition, on electron abstractions the aromatic hydroxylation has more impact than alkyl hydroxylation. Docking studies indicate that six structures 1, 7, 8 and 13–15 have potential for inhibiting human as well as murine COX-2, due to regions showing similar intermolecular interactions to the observed for the control compounds (indomethacin and refecoxib). Toxicity can be related to aromatic hydroxylation. In accordance to our calculations, the derivatives here proposed are potentially more active as well safer than phenylbutazone and only structures 8 and 13–15 were the most promising. Such results can explain the biological properties of phenylbutazone and support the design of potentially safer candidates.

Pharmaceutical Metabolism in Fish: Using a 3-D Hepatic In Vitro Model to Assess Clearance

At high internal doses, pharmaceuticals have the potential for inducing biological/pharmacological effects in fish. One particular concern for the environment is their potential to bioaccumulate and reach pharmacological levels; the study of these implications for environmental risk assessment has therefore gained increasing attention. To avoid unnecessary testing on animals, in vitro methods for assessment of xenobiotic metabolism could aid in the ecotoxicological evaluation. Here we report the use of a 3-D in vitro liver organoid culture system (spheroids) derived from rainbow trout to measure the metabolism of seven pharmaceuticals using a substrate depletion assay. Of the pharmaceuticals tested, propranolol, diclofenac and phenylbutazone were metabolised by trout liver spheroids; atenolol, metoprolol, diazepam and carbamazepine were not. Substrate depletion kinetics data was used to estimate intrinsic hepatic clearance by this spheroid model, which was similar for diclofenac and approximately 5 fold higher for propranolol when compared to trout liver microsomal fraction (S9) data. These results suggest that liver spheroids could be used as a relevant and metabolically competent in vitro model with which to measure the biotransformation of pharmaceuticals in fish; and propranolol acts as a reproducible positive control.

The Safety and Pharmacokinetics of Carprofen, Flunixin and Phenylbutazone in the Cape Vulture (Gyps coprotheres) following Oral Exposure

The following study evaluates the overt toxic potential of carprofen (CRP), flunixin (FXN) and phenylbutazone (PBZ) in Old world vultures in relation to historic toxicity data for diclofenac and ketoprofen, with the Cape vulture (Gyps coprotheres) being the indicator species. The toxic potential of a single oral dose of CRP (11.5 mg/kg), FXN (1 mg/kg),PBZ (1.7 mg/kg) or water was evaluated by means of a four-way parallel study (n = 2), as means of ascertaining if these drugs were as toxic as diclofenac in the vulture. No unscheduled deaths or pathological lesions were noted following exposure. Clinical signs of lethargy and depression were, however, noted in one CRP, two FXN and one PBZ treated birds. Mild reversible inhibition of UA excretion was evident in all three groups, although UA remained within the population reference interval in contrast to the effects previously described for diclofenac and ketoprofen. All treatment groups had a drug concentration responsive increase in alanine transferase activity. CRP, FXN and PBZ were characterised by a maximum plasma concentration (Cmax) of 1051.8 ± 620.7 ng/ml, 335.9 ± 36.3 ng/ml and 11150 ± 2474.9 ng/ml at 4 ± 4.3, 0.45 ± 0.02 and 5.3 ± 5.2 hours (Tmax) respectively and a half-life of elimination of 13.3 ±5, 1.8±1 and 18.7 ±11.4 hours respectively. While we could not demonstrate a lethal effect of the tested substances, the presence of toxic clinical signs, clinical pathological changes and/or long half-lives of elimination suggests that all three drugs have a potential for toxicity in a larger population or on repeat administration. In conclusion while the studied substances were not as overtly toxic as diclofenac, they are of safety concern.

Expression of pleiotrophin, an important regulator of cell migration, is inhibited in intestinal epithelial cells by treatment with non-steroidal anti-inflammatory drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most widely used drugs for the suppression of inflammation and pain. However, the analgesic properties of NSAIDs are also associated with significant negative side effects, most notably in the gastrointestinal (GI) tract. Increasingly, evidence indicates that the ulcerogenic properties of some NSAIDs are not exclusively the result of inhibition of cyclooxygenase isoforms in the GI tract, and other mechanisms, including inhibition of cell migration and epithelial restitution, are being explored. Recently, microarray analysis was used to identify potential novel targets of NSAID activity in intestinal epithelial cells. Treated cells exhibited significant reductions in the gene expression of pleiotrophin (PTN), a cytokine and growth factor known to participate in angiogenesis and bone growth. This report aimed to confirm the microarray results reported previously, and to measure protein expression of PTN in intestinal epithelial cells. Furthermore, we also examined the effects of exogenous PTN on cell migration in the presence and absence of either NSAIDs with variable ulcerogenic potential or PTN-specific siRNA. Our results demonstrated that indomethacin and NS-398, two NSAIDs with ulcerogenic potential significantly decrease both gene and protein expressions of PTN in IEC-6 cells and protein expression in IEC-6-Cdx2 cells. Additionally, cell migration experiments with PTN siRNA showed that PTN is an important mediator of IEC-6 cell migration, and addition of exogenous PTN partially restores the deficits in cell migration caused by treatment with indomethacin and NS-398. Finally, measurement of PTN protein expression in the GI tract of horses treated with phenylbutazone showed that PTN expression is reduced by NSAIDs in vivo. Our results show that PTN is an important mediator of cell migration in IEC-6 cells, and PTN is a potential target through which NSAIDs may inhibit cell migration, epithelial restitution, and wound healing in the GI tract.

Competitive binding to plasma thyroid hormone transport proteins and thyroid disruption by phenylbutazone used as a probe

A model of thyroidectomized sheep intravenously supplemented with thyroid hormone (TH) was developed to mimic endogenous TH exposure and to analyze the impact on plasma TH homeostasis of xenobiotic interference with TH binding to plasma proteins. TH was displaced from plasma protein binding sites by using phenylbutazone (PBZ) as a test xenobiotic, to compare the effect of PBZ on steady state free and total plasma TH concentrations between the in vivo situation and an in vitro system. While PBZ increased free TH in vitro, PBZ administration in vivo produced an immediate reduction in both total and free plasma TH. The decrease in the total TH was consistent with a PBZ-induced displacement of TH from its plasma binding proteins, leading to an increase in total TH plasma clearance. However, this reduction in total TH was not expected to be accompanied by a parallel decrease in free plasma TH since the free TH is determined by the clearance of the free plasma TH. This suggested that PBZ may also have interfered with the clearance mechanisms of free TH. It can be concluded that our thyroidectomized sheep model enables a dual action of a xenobiotic on plasma TH to be distinguished, namely a displacement of TH from its binding proteins leading to a decrease in the total plasma concentration, which is not relevant to thyroid function versus an interference with the intrinsic TH clearance leading to a change in the free plasma TH, which has a major impact in terms of thyroid disruption.

The Effects of Anti-Inflammatory Drugs on Some Aspects of Intermediary Metabolism

The effects of salicylate, 2,4-dinitrophenol, hydrocortisone, dexamethasone, phenylbutazone and chloroquine diphosphate on the incorporation of radioactivity from [14C]glucose and [1,4–14C]succinate into the soluble intermediates of rat liver preparations have been studied. It is concluded that the increased incorporation of radiocarbon into oligosaccharides, phosphates and malic and fumaric acids bears no relation to anti-inflammatory activity in the salicylate group of drugs.

Interaction of phenylbutazone and colchicine in binding to serum albumin in rheumatoid therapy: 1H NMR study

The monitoring of drug concentration in blood serum is necessary in multi-drug therapy. Mechanism of drug binding with serum albumin (SA) is one of the most important factors which determine drug concentration and its transport to the destination tissues. In rheumatoid diseases drugs which can induce various adverse effects are commonly used in combination therapy. Such proceeding may result in the enhancement of those side effects due to drug interaction. Interaction of phenylbutazone and colchicine in binding to serum albumin and competition between them in gout has been studied by proton nuclear magnetic resonance ((1)H NMR) technique. The aim of the study was to determine the low affinity binding sites, the strength and kind of interaction between serum albumin and drugs used in combination therapy. The study of competition between phenylbutazone and colchicine in binding to serum albumin points to the change of their affinity to serum albumin in the ternary systems. This should be taken into account in multi-drug therapy. This work is a subsequent part of the spectroscopic study on Phe-COL-SA interactions [A. Sułkowska, et al., J. Mol. Struct. 881 (2008) 97-106].

Anti-inflammatory activity of indanyltetrazole derivatives

A number of indanyl tetrazolederivatives namely 5-(6'-chloroindan-1'-yl)tetrazole (CIT), 5-(6'-bromoindan-1'-yl)tetrazole (BIT), 5-(6'-chloroindan-1'-yl)methyltetrazole (CIMT), 5-(6'-bromoindan-1'-yl)methyl-tetrazole (BIMT) were evaluated for the anti-inflammatory activity in carragennan induced rat paw edema in Swiss albino Wister rats for 24-hour period at the dose of 100 mg/kg of body weight by intraperitoneal route where phenylbutazone (PBZ) was used as the standard. All of these compounds exhibited inhibition on rat paw edema with peak actions observed following 3 hours after administration. Moreover, compounds CIMT and BIMT were further evaluated at dose of 50 mg/kg of body weight. Among the compounds, CIMT showed higher activity than others and was very close to standard phenylbutazone.

Effects of continuous oral administration of phenylbutazone on biomarkers of cartilage and bone metabolism in horses

OBJECTIVE

To evaluate the effects of continuous oral administration of phenylbutazone on serum and synovial fluid biomarkers of skeletal matrix metabolism in horses.

ANIMALS

11 adult female horses without clinical or radiographic evidence of joint disease.

PROCEDURES

Horses were randomly assigned to control or treatment groups. Phenylbutazone was administered orally twice daily at a dose of 4.4 mg/kg for 3 days to the treatment group and subsequently at a dose of 2.2 mg/kg for 7 days. Serum and radiocarpal synovial fluid samples were obtained at baseline and thereafter at regular intervals for 4 weeks. Biomarkers of cartilage aggrecan synthesis (chondroitin sulfate 846) and type II collagen synthesis (procollagen type II C-propeptide) and degradation (collagen type II cleavage) were assayed. Biomarkers of bone synthesis (osteocalcin) and resorption (C-terminal telopeptide of type I collagen) were also measured.

RESULTS

No significant differences were found between control and treatment groups or temporally for the biomarkers chondroitin sulfate 846, procollagen type II C-propeptide, collagen type II cleavage, and C-terminal telopeptide of type I collagen in serum or synovial fluid. A significant increase in osteocalcin concentration occurred in synovial fluid during treatment in the treated group. No treatment effect was detected for serum osteocalcin concentration.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that continuous phenylbutazone administration at recommended doses altered some biomarkers in healthy equine joints after short periods of administration. Increased osteocalcin concentration may indicate an undetermined anabolic effect of phenylbutazone administration on periarticular bone or transient induction of osteogenesis in articular chondrocytes or a mesenchymal subpopulation of synoviocytes.

Glucuronidation of DRF-6574, hydroxy metabolite of DRF-4367 (a novel COX-2 inhibitor) by pooled human liver, intestinal microsomes and recombinant human UDP-glucuronosyltransferases (UGT): Role of UGT1A1,1A3 and 1A8

DRF-4367 is a novel COX-2 inhibitor, which showed good efficacy in several animal models of inflammation. In a comparative in vitro metabolism in various liver microsomes, DRF-4367 forms a hydroxy metabolite (DRF-6574) mediated by CYP2D6 and 2C19 isoenzymes. DRF-6574 readily undergoes Phase-II metabolism and forms glucuronide and sulfate conjugates both in vitro and in vivo. The objective of the present study was two folds: to study the glucuronidation of DRF-6574 in human liver and intestinal microsomes and to identify the recombinant human liver and intestinal UDP-glucuronosyltransferase (UGT) enzymes responsible for glucuronidation of DRF-6574. Of twelve recombinant UGTs tested, two hepatic UGTs viz., UGT1A1 and 1A3 and an extra hepatic UGT i.e., UGT1A8 showed the catalytic activity. The enzyme kinetics in pooled human liver, intestinal and recombinant UGT microsomes showed a typical Michaelis-Menten plot. The apparent Km and Vmax value for DRF-6574 was found to be 116 +/- 24 microM and 2.07 +/- 0.12 microg/min/mg protein and 142 +/- 17 microM and 3.83 +/- 0.15 microg/min/mg protein in pooled human liver and intestinal microsomes, respectively. The intrinsic clearance (Vmax/Km) value for DRF-6574 was estimated to be 0.043 and 0.065 ml/min/mg protein, respectively in pooled human liver and intestinal microsomes. Moreover we have determined the Km and Vmax and intrinsic clearance values for specific UGTs viz., UGT 1A1, 1A3 and 1A8. The apparent Km and Vmax values are 23 +/- 7.2 microM, 3.44 +/- 0.17 microg/min/mg protein for UGT1A1, 60 +/- 7.9 microM, 3.67 +/- 0.11 microg/min/mg protein for UGT1A3, 96 +/- 8.0 microM, 2.95 +/- 0.06 microg/min/mg protein for UGT1A8. The intrinsic clearance values (Vmax/Km) estimated were 0.367, 0.148, 0.074 ml/min/mg protein for UGT1A1, 1A3 and 1A8, respectively. The intrinsic clearance value in UGT1A8 was very close to that in human intestinal and liver microsomes. The formation of DRF-6574 glucuronide by human liver, intestinal and UGT1A1, 1A3 and 1A8 microsomes was effectively inhibited by phenylbutazone.

Evaluation of anti-inflammatory activity of Calotropis gigantea (AKANDA) in various biological system

To evaluate the effect of Calotropis G in various experimental animal models. The anti-inflammatory activity was evaluated using carrageenin-induced kaolin -induced rat paw oedema for acute and cotton-pellet granuloma, adjuvant-induced arthritis model for chronic inflammation. Antipyretic activity was carried out using yeast induced pyresis method. Phenylquinone--induced writhing method in mice was used for analgesic activity. Test compounds exhibited variable anti-inflammatory activity and peak activity of the test compounds were reached at 2 h. Alkaloid fraction possesses comparatively high initial anti-inflammatory activity. The residual anti-inflammatory activity of alkaloid fraction of Calotropis G suggest either a greater protein binding nature of the compound there by providing a slow released pool of active drug molecule in the system or non available of possible bioactive metabolites to retain the activity profile relation.

Inactivation of ?1-Antiproteinase Induced by Phenylbutazone: Participation of Peroxyl Radicals and Hydroperoxide

To clarify the action of a side-effect of phenylbutazone, we investigated the inactivation of alpha(1)-antiproteinase induced by phenylbutazone in the presence of horseradish peroxidase (HRP) and H(2)O(2) (HRP-H(2)O(2)). The activity of alpha(1)-antiproteinase was rapidly lost during the interaction of phenylbutazone with HRP-H(2)O(2) under aerobic conditions. Phenylbutazone showed a marked spectral change under aerobic conditions but not under anaerobic conditions. Spin trap agents were very effective in inhibiting alpha(1)-antiproteinase inactivation induced by phenylbutazone. Oxidation of phenylbutazone was stopped by catalase, but the inactivation reaction of alpha(1)-antiproteinase proceeded even after removal of H(2)O(2) in the reaction mixture. Formation of the peroxidative product from phenylbutazone was detected by iodometric assay. These results indicate that both peroxyl radicals and the peroxidative product of phenylbutazone participated in the inactivation of alpha(1)-antiproteinase. Other anti-inflammatory drugs did not inactivate alpha(1)-antiproteinase during interaction with HRP-H(2)O(2). Inactivation of alpha(1)-antiproteinase may contribute to serious side effects of phenylbutazone.

Effects of phenylbutazone alone or in combination with flunixin meglumine on blood protein concentrations in horses

OBJECTIVE

To assess effects of treatment with phenylbutazone (PBZ) or a combination of PBZ and flunixin meglumine in horses.

ANIMALS

24 adult horses.

PROCEDURE

13 horses received nonsteroidal antiinflammatory drugs (NSAIDs) in a crossover design. Eleven control horses were exposed to similar environmental conditions. Treated horses received PBZ (2.2 mg/kg, PO, q 12 h, for 5 days) and a combination of PBZ and flunixin meglumine (PBZ, 2.2 mg/kg, PO, q 12 h, for 5 days; flunixin meglumine, 1.1 mg/kg, IV, q 12 h, for 5 days). Serum samples were obtained on day 0 (first day of treatment) and day 5, and total protein, albumin, and globulin were measured.

RESULTS

1 horse was euthanatized with severe hypoproteinemia, hypoalbuminemia, and colitis during the combination treatment. Comparisons revealed no significant difference between control horses and horses treated with PBZ alone. There was a significant difference between control and treated horses when administered a combination of PBZ and flunixin meglumine. Correction for horses with values >2 SDs from the mean revealed a significant difference between control horses and horses administered the combination treatment, between control horses and horses administered PBZ alone, and between horses receiving the combination treatment and PBZ alone. Gastroscopy of 4 horses revealed substantial gastric ulcers when receiving the combination NSAID treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

Analysis of results of the study indicates the need for caution when administering a combination NSAID treatment to horses because the detrimental effects may outweigh any potential benefits.

COX-1 and COX-2 inhibition in horse blood by phenylbutazone, flunixin, carprofen and meloxicam: An in vitro analysis

We report on the inhibitory activity of the NSAIDs meloxicam, carprofen, phenylbutazone and flunixin, on blood cyclooxygenases in the horse using in vitro enzyme-linked assays. As expected, comparison of IC50 indicated that meloxicam and carprofen are more selective inhibitors of COX-2 than phenylbutazone and flunixin; meloxicam was the most advantageous for horses of four NSAIDs examined. However at IC80, phenylbutazone (+134.4%) and flunixin (+29.7%) had greater COX-2 selectivity than at IC50, and meloxicam (-41.2%) and carprofen (-12.9%) had lower COX-2 selectivity than at IC50. We therefore propose that the selectivity of NSAIDs should be assessed at the 80% as well as 50% inhibition level.

Interleukin-1beta inhibits paw oedema induced by local administration of latex of Calotropis procera extracts

Interleukin-1beta (IL-1beta), a pro-inflammatory cytokine, has been reported to exhibit anti-inflammatory properties in the carrageenan-induced paw oedema model. In the present study, we have evaluated the anti-inflammatory activity of IL-1beta against inflammation induced by local administration of the methanol extract of dried latex of Calotropis procera (MeDL) and compared it with that against carrageenan. The anti-inflammatory activity of standard anti-inflammatory drugs, phenylbutazone (PBZ) and dexamethasone (DEX), was also evaluated against both inflammagens. Injection of an aqueous solution of dried latex and MeDL into the sub-plantar surface of the rat paw produced intense inflammation with a peak response occurring within 2 h, while the peak inflammatory response with carrageenan was obtained at 3 h. Subcutaneous injection of IL-1beta was found to be more effective against the inflammatory response elicited by carrageenan (70% inhibition) as compared to MeDL (50% inhibition) at 20microg/kg dose. On the other hand, PBZ effectively inhibited the inflammatory response elicited by both MeDL and carrageenan, while DEX was more effective against carrageenan. Thus, our study indicates that the difference in the anti-inflammatory effect of IL-1beta against latex of C. procera extract and carrageenan is due to the release of different mediators released by these inflammagens.

Protein binding characteristics of 2'-benzoyloxycinnamaldehyde

The protein binding characteristic of 2'-Benzoyloxycinnamaldehyde (BCA) was investigated, which has demonstrated a potent antitumor effect against several human solid tumor cell lines and in human tumor xenograft nude mice. Protein binding of BCA in human serum was 86 +/- 0.91% and the predominant binding protein of BCA was fatty-acid-free human serum albumin (HSA) (81 +/- 0.91%). The binding of BCA to HSA was outlined by one class, and Ka and n of BCA were 1.65 x 10(5) M(- 1) and 0.374, respectively. Displacement studies with fluorescence probes suggested that BCA mainly binds to site I on HSA, and BCA-induced enhancement in site II binding. The limited drug-drug interaction experiments suggested that BCA influences both site I and site II drug-HSA bindings via different mechanisms; a competitive displacement and a probable allosteric conformational change in HSA, respectively.

Involvement of opioidergic and alpha2-adrenergic mechanisms in the central analgesic effects of non-steroidal anti-inflammatory drugs in sheep

The level within the central nervous system where non-steroidal anti-inflammatory drugs (NSAIDs) produce analgesia and the mechanisms by which they mediate this effect are still uncertain. This study assessed the central analgesic effects of ketoprofen, phenylbutazone, salicylic acid and tolfenamic acid in sheep implanted with indwelling intrathecal (i.t.) catheters and submitted to mechanical noxious stimulation. The sheep received i.t. cumulative concentrations (0.375-200 microM; 100 microL) as well as a single intravenous (i.v.) dose (3, 8, 10 and 2 mg/kg, respectively) of each NSAID. The sheep were also given i.t. naloxone (5.49 mM; 100 microL) and atipamezole (4.03 mM; 100 microL) prior to i.v. ketoprofen. None of the i.t. NSAIDs increased mechanical thresholds. Intravenously, only ketoprofen and tolfenamic acid raised the pain thresholds. The hypoalgesic effect of i.v. ketoprofen was prevented by i.t. naloxone or atipamezole. Although NSAIDs had no direct effect on the spinal cord, their analgesic action appeared to be spinally mediated.

Preferential and non-selective cyclooxygenase inhibitors reduce inflammation during lipopolysaccharide-induced synovitis

Synovitis in horses is frequently treated by administration of non-steroidal anti-inflammatory drugs (NSAIDs), which inhibit cyclooxygenase isoforms (COX-1 and COX-2). Constitutively expressed COX-1 is involved in physiologic functions such as maintenance of gastric mucosal integrity, whereas COX-2 is up-regulated at sites of inflammation. Thus, COX-2 inhibitors reduce inflammation with reduced gastrointestinal side effects as compared to non-selective COX inhibitors. The objective of the present study was to compare the anti-inflammatory effects of the preferential COX-2 inhibitor etodolac with the non-selective COX inhibitor phenylbutazone in horses with lipopolysaccharide (LPS)-induced synovitis. Three groups of horses (n=6) received no treatment, phenylbutazone (4.4 mg/kg, IV, q12h), or etodolac (23 mg/kg, IV, q12h), respectively, 2-h following injection of LPS into one middle carpal joint. Synovial fluid was analyzed for white blood cell (WBC) count, and TXB2 and PGE2 levels. Phenylbutazone and etodolac significantly reduced WBC count 6 and 24-h following injection of LPS compared to untreated horses. In addition, both drugs significantly reduced PGE2 levels (P<0.05) 6-h following LPS injection, whereas the probable COX-1 prostanoid TXB2 was significantly reduced by phenylbutazone (P<0.05), but not etodolac. Etodolac may serve as a more selective anti-inflammatory agent than phenylbutazone for treatment of equine synovitis.

Effects of the Geiji-Bokryung-Hwan on carrageenan-induced inflammation in mice and cyclooxygenase-2 in hepatoma cells of HepG2 and Hep3B

We investigated the effects of a Korean traditional prescription, Geiji-Bokryung-Hwan (GBH) consisting of five herbs of Cinnamomi Ramulus (Korean name Geiji), Poria cocos (Bokryung), Moutan Cortex Radicis (Modanpi). Paeoniae Radix (Jakyak) and Persicae Semen (Doin) on tumor growth-inhibitory activity and cancer chemopreventive activity in assays representing three major stages of carcinogenesis. Effects of the GBH extracts on carrageenan-induced edema inflammation using female (C57BL/6XC3H) F1 (B6C3F1) mice and tumorigenesis were examined. Finally, cyclooxygenase metabolites were determined after extracts treatment. These data suggest that GBH extracts merits investigation as a potential cancer chemopreventive agent in humans.

Effects of phenylbutazone, indomethacin, prostaglandin E2, butyrate, and glutamine on restitution of oxidant-injured right dorsal colon of horses in vitro

OBJECTIVE

To study the effects of phenylbutazone, indomethacin, prostaglandin E2 (PGE2), glutamine, and butyrate on restitution of oxidant-injured right dorsal colon of horses in vitro.

SAMPLE POPULATION

Right dorsal colon from 9 adult horses euthanatized for reasons other than gastrointestinal tract disease.

PROCEDURES

Mucosal segments from the right dorsal colon were injured via exposure to HOCl and incubated in Ussing chambers in solutions containing phenylbutazone, indomethacin, indomethacin and PGE2, glutamine, and butyrate. Transepithelial resistance and mucosal permeability to mannitol were measured, and all mucosal segments were examined histologically.

RESULTS

The HOCl-injured mucosa had lower resistance and higher permeability to mannitol, compared with control tissue. Histologic changes were also evident. Resistance of HOCl-injured mucosa recovered partially during the incubation period, and glutamine improved recovery. Phenylbutazone and indomethacin increased resistance, but these increases were not significant. Butyrate and PGE2 had no effects, compared with nontreated HOCl-injured tissues. Mucosal permeability to mannitol was lower in glutamine-treated tissue, compared with nontreated tissue. Histologic changes reflected the resistance and permeability changes.

CONCLUSIONS AND CLINICAL RELEVANCE

According to our findings, phenylbutazone and indomethacin do not seem to interfere with restitution of oxidant-injured mucosa of equine colon in vitro, and glutamine could facilitate mucosal restitution.

Influence of thiamphenicol on the primary functions of human polymorphonuclear leucocytes against Streptococcus pyogenes

Current antibiotic therapy encourages the use of antibiotics that may potentiate the host's immune defences. We therefore investigated the effect of thiamphenicol (TAP), the active principle of thiamphenicol glycinate acetylcysteinate (TGA), on human granulocyte functions, mainly phagocytosis and intracellular killing of Streptococcus pyogenes. Our findings support the use of thiamphenicol in the treatment of respiratory tract infections caused by S. pyogenes as it acts directly against the pathogen as well as in cooperation with PMNs by eliciting their intracellular killing.

Synthesis of chloro and bromo substituted 5-(indan-1'-yl)tetrazoles and 5-(indan-1'-yl)methyltetrazoles as possible analgesic agents

Chloro and bromo substututed indanyl tetrazoles (compounds 5a, b) and indanyl methyltetrazoles (compounds 5c, 5d) have been synthesized from their respective acids through amide and nitrile routes, and characterized. The title compounds (5a, 5b, 5c and 5d) were subjected for their analgesic activity in the acetic acid induced writhing test on albino mice. The significant (p < 0.001) analgesic activity, exhibited by the compound 5b at a dose of 50 mg/kg body weight, was comparable to that of phenylbutazone and indometacin at a dose of 100 and 50 mg/kg body weight respectively. The effect of substitution at the benzenoid part of the indan nucleus and chain lenght on analgesic activity was in the following order: bromine > chlorine and tetrazole > methyltetrazole.

Effect of 14-deoxyandrographolide on calcium-mediated rat uterine smooth muscle contractility

In this study, the effect of 14-deoxyandrographolide (14-DAP) on calcium channel-dependent rat uterine smooth muscle contraction was evaluated. Using a tissue bath preparation, 14-DAP was able to reduce the contractile response to 0.3 and 3.0 mm of CaCl(2), with an IC(50) of 1.24 +/- 0.23 x 10(-5) m and 5.94 +/- 0.29 x 10(-5) m, respectively. 14-DAP shifted the CaCl(2) cumulative dose response curve to the right, increasing the EC(50) from 2.08 +/- 0.20 x 10(-4) m to 4.22 +/- 0.22 x 10(-4) m (5 micrometer 14-DAP) and 2.5 +/- 1.0 x 10(-3) m (50 micrometer 14-DAP). In order to determine if 14-DAP had any effect on intracellular calcium, the relaxant response to 14-DAP following contraction by oxytocin, PGF(2alpha) and vanadate in Ca(+2)-free solution was compared with that of isoproterenol and phenylbutazone. While isoproterenol and phenylbutazone relaxed the smooth muscle in a dose-dependent manner, 14-DAP did not have any effect on either the oxytocin, PGF(2alpha) or vanadate-induced smooth muscle contraction. Based on these data, it appears that 14-DAP is an uterine smooth muscle relaxant which produces a selective blockade of voltage operated calcium channels.

Antiinflammatory and antiulcer activities of Bambusa arundinacea

The extracts of Bambusa arundinacea have been used in Indian folk medicine to treat various inflammatory conditions. The plant has got antiulcer activity also. It is thought that these two properties in the same extract are very much useful in the treatment of inflammatory conditions. It is well known fact that the most of the available antiinflammatory drugs are ulcerogenic. The antiinflammatory effect of the methanol extract of the leaves of Bambusa arundinacea against carrageenin-induced as well as immunologically induced paw oedema and also its antiulcer activity in albino rats have been studied and found to be significant when compared to the standard drugs. The combination of methanol extract and phenylbutazone (Non-Steroidal Antiinflammatory Agent, NSAIA) has been studied and found to be the most potent antiinflammatory activity experimentally with least toxic (no ulcerogenic) activity. Thus, the combination of herbal product (methanol extract of Bambusa arundinacea) with modern medicine (NSAIAs) will produce the best antiinflammatory drug and will be useful for long-term treatment of chronic inflammatory conditions like rheumatoid arthritis with peptic ulcer, which are common.

Effects of lipopolysaccharide and phenylbutazone on gastric contents in the horse

REASONS FOR PERFORMING STUDY

Endotoxaemia causes a disruption of gastrointestinal motility in the horse but there is no information on its effects on gastric secretion. Lipopolysaccharide (LPS) administration is known to affect gastric secretion in other species.

HYPOTHESIS

That LPS, a toxic component of Gram-negative bacteria, would reduce gastric acid secretion and that pretreatment with phenylbutazone (PBZ) would block the effects of LPS.

METHODS

The effects of LPS and PBZ on gastric contents were investigated in fasted, mature horses, with permanent gastric cannulae. Horses were pretreated with either saline or PBZ 15 mins before a 60 min infusion of either LPS or saline. Gastric contents were collected at 15 min intervals for 3 h, beginning 15 mins after the start of the LPS or saline infusion.

RESULTS

Lipopolysaccharide significantly decreased gastric acid output, [K+] and potassium output and increased [Na+] and sodium output. Phenylbutazone did not affect basal gastric acid secretion but decreased LPS-induced changes in the secreted volume, [Na+] and sodium output.

CONCLUSIONS

This study provides evidence that LPS affects gastric acid secretion in the horse and that these LPS-induced changes are mediated, in part, by prostaglandins.

POTENTIAL RELEVANCE

Lipopolysaccharide administration can induce changes in the composition of gastric contents in the horse but further work is needed to determine the source of these changes.

The analgesic, antipyretic and anti-inflammatory activity of Diospyros variegata Kruz

Pharmacological studies were conducted with the hexane extract of the dry stem of Diospyros variegata Kruz. (Ebenaceae) on experimental animals for evaluating the analgesic, antipyretic and anti-inflammatory activities. In the analgesic test, the hexane extract elicited inhibitory intensity on acetic acid-induced writhing response and on the late phase of formalin test but possessed only a weak effect on the tail-flick response and on the early phase of formalin test. The hexane extract also elicited antipyretic action when tested in yeast-induced hyperthermia in rats. In addition, the hexane extract showed an anti-inflammatory effect when tested in ethyl phenylpropiolate (EPP)- and arachidonic acid (AA)-induced rat ear edema.

Anti-inflammatory activity of some novel alpha-amino naphthalene derivatives

alpha-Acetylamino naphthalene (1) was reacted with different aromatic aldehydes and with primary or secondary amines to give alpha-aminonaphthylsubstitutedaryl chalkones (2-5) and alpha-(substituted aminoethyl)-amidonaphthalenes (14-25), respectively. These substituted chalkones were treated with hydrazinehydrate and hydroxylamine hydrochloride to give 1-acetyl-5-substitutedaryl-3-(alpha-aminonaphthyl)-2-pyrazolines (6-9) and alpha-(2-substitutedaryl-isoxazolin-4-yl)-aminonaphthalenes (10-13), respectively. Their chemical structures were confirmed by IR and 1H-NMR spectral data and elemental analysis. Studies of the anti-inflammatory and ulcerogenic activities and acute toxicity of these newly synthesized compounds were performed in vivo and compared with the standard drug, phenylbutazone (CAS 50-33-9). Some of these compounds showed potent anti-inflammatory activity and less ulcerogenic effects than phenylbutazone.

Evaluation of the ability of carprofen and flunixin meglumine to inhibit activation of nuclear factor kappa B

OBJECTIVE

To determine whether the nonsteroidal anti-inflammatory drugs (NSAIDs) carprofen, flunixin meglumine, and phenylbutazone have cyclooxygenase (COX)-independent effects that specifically inhibit activation of the proinflammatory transcription factor nuclear factor kappa B (NfkappaB).

STUDY POPULATION

Purified ovine COX-1 and -2 and cultures of RAW 264.7 murine macrophages.

PROCEDURE

The COX-1 and -2 inhibitory effects of the NSAIDs were tested in assays that used purified ovine COX-1 and -2. Prostaglandin production was analyzed by use of a radioimmunoassay. Inhibitory effects of these drugs on lipopolysaccharide (LPS)-induction of inducible nitric oxide synthase (iNOS) and LPS-stimulated translocation of NficB were determined by use of RAW 264.7 murine macrophages.

RESULTS

Flunixin meglumine and phenylbutazone were selective inhibitors of COX-1. Carprofen and flunixin meglumine, but not phenylbutazone, inhibited LPS-induction of iNOS. Carprofen and, to a lesser degree, flunixin meglumine had inhibitory effects on NFkappaB activation.

CONCLUSIONS AND CLINICAL RELEVANCE

The ability of drugs such as carprofen and flunixin meglumine to inhibit activation of NfkappaB-dependent genes such as iNOS, in addition to their effects on COX, suggests an additional mechanism for their anti-inflammatory effects and may explain the ability of flunixin meglumine to be an effective inhibitor of the effects of endotoxin in horses with endotoxemia.

[Clinical problems with oral anticoagulation -- 3 case reports]

Two patients with severe bleeding complications under oral anticoagulant treatment are presented, in one case caused by pharmacokinetic drug interference (phenylbutazone), in the other by genetic predisposition to bleeding induced by coumarin anticoagulants. Another patient with decreasing INR due to drug interference (rifampicin) is presented as well. The possibility of drug interferences with coumarin anticoagulants has to be anticipated, whenever the medication of an orally anticoagulated patient is changed. A founder mutation of the factor IX propeptide constitutes a genetic predisposition to bleeding in patients put on coumarins. Its presence should be excluded in any patient suffering from hemorrhagic complications after starting anticoagulation when INR values are in the target range.

Cortisol responses to dehorning of calves given a 5-h local anaesthetic regimen plus phenylbutazone, ketoprofen, or adrenocorticotropic hormone prior to dehorning

The purpose of this work was to assess whether the non-steroidal anti-inflammatory drugs (NSAIDs) phenylbutazone and ketoprofen, and an adrenocorticotropic hormone (ACTH) induced cortisol surge, reduce the cortisol response which occurs when the local anaesthetic wears off in calves following dehorning. There were four control groups and one dehorned group; also four groups were given local anaesthetic lasting 5h and were dehorned without or with phenylbutazone, ketoprofen or an ACTH injection, one group was injected with ACTH twice (at 0 and 6h) and another received ACTH and 6h later was dehorned. Blood samples were taken before and after dehorning and plasma cortisol concentrations were determined by radio-immunoassay. Dehorning increased the mean plasma cortisol concentrations [max 137 (11)nmoll(-1)] above control values [38 (5)nmoll(-1)] for about 7h, whereas local anaesthesia maintained concentrations at control values until about 5h after dehorning, and then they became elevated until about 10h. The maximum rise in mean concentration which occurred when the local anaesthetic wore off [128 (32)nmoll(-1)] was not affected when phenylbutazone was given before dehorning [141 (28)nmoll(-1)], but was reduced significantly when ketoprofen [65 (17)nmoll(-1)] or ACTH [61 (19)nmoll(-1)] were injected before or at the time of dehorning, respectively. Marked cortisol responses to ACTH injected at 0 and 6h were similar, but the early part of the cortisol response to dehorning 6h after an ACTH injection was reduced. It is suggested that the delayed cortisol response, which began 5h after dehorning, arose both from ketoprofen-sensitive and cortisol-sensitive sensory input as well as from other factors. Phenylbutazone did not affect the sensory input from the amputation wounds in the present calves.

Effects of anti-arthritis preparations on gene expression and enzyme activity of cyclooxygenase-2 in cultured equine chondrocytes

OBJECTIVE

To determine the effects of recombinant equine interleukin -1beta (reIL-1beta) and 4 anti-inflammatory compounds on the expression and activity of cyclooxygenase (COX)-2 in cultured equine chondrocytes.

SAMPLE POPULATION

Articular cartilage from 9 young adult horses.

PROCEDURE

Reverse transcriptase-polymerase chain reaction methods were used to amplify a portion of equine COX-2 to prepare a cDNA probe. Northern blot analysis was used to quantify the expression of COX-2 in first-passage cultures of equine articular chondrocytes propagated in media containing dexamethasone (DEX), phenylbutazone (PBZ), polysulfated glycosaminoglycan, and hyaluronan, each at concentrations of 10 and 100 microg/ml and each with or without reIL-1beta. A commercial immunoassay was used to determine prostaglandin E2 (PGE2) concentrations in conditioned medium of similarly treated cells to quantify COX-2 activity.

RESULTS

Addition of reIL-1beta increased the expression of COX-2 in a dose-dependent manner, which was paralleled by an increased concentration of PGE2 in culture medium. Concentration of PGE2 in spent medium from reIL-beta-treated chondrocytes was significantly reduced by DEX and PBZ; however, only DEX significantly reduced gene expression of COX-2.

CONCLUSIONS AND CLINICAL RELEVANCE

Prostaglandin E2 is considered to be an important mediator in the pathophysiologic processes of arthritis, and cultured chondrocytes respond to interleukin-1 with enhanced expression and activity of COX-2. Palliative relief in affected horses is probably attributable, in part, to inhibition of PGE2 synthesis; however, analysis of these data suggests that of the 4 compounds tested, only DEX affects pretranslational regulation of the COX-2 gene in cultured equine chondrocytes.

Characterization of methotrexate transport and its drug interactions with human organic anion transporters

Life-threatening drug interactions are known to occur between methotrexate and nonsteroidal anti-inflammatory drugs (NSAIDs), probenecid, and penicillin G. The purpose of this study was to characterize methotrexate transport, as well as to determine the site and the mechanism of drug interactions in the proximal tubule. Mouse proximal tubule cells stably expressing basolateral human organic anion transporters (hOAT1 and hOAT3) and apical hOAT (hOAT4) were established. The K(m) values for hOAT1-, hOAT3-, and hOAT4-mediated methotrexate uptake were 553.8 microM, 21.1 microM, and 17.8 microM, respectively. NSAIDs (salicylate, ibuprofen, ketoprofen, phenylbutazone, piroxicam, and indomethacin), probenecid, and penicillin G dose dependently inhibited methotrexate uptake mediated by hOAT1, hOAT3, and hOAT4. Kinetic analysis of inhibitory effects of these drugs on hOAT3-mediated methotrexate uptake revealed that these inhibitions were competitive. The K(i) values for the effects of salicylate, phenylbutazone, indomethacin, and probenecid on hOAT3-mediated methotrexate uptake were comparable with therapeutically relevant plasma concentrations of unbound drugs. In addition, in the presence of human serum albumin, the K(i) values were comparable with therapeutically relevant total plasma concentrations of drugs. In conclusion, these results suggest that methotrexate is taken up via hOAT3 and hOAT1 at the basolateral side of the proximal tubule and effluxed or taken up at the apical side via hOAT4. In addition, hOAT1, hOAT3, and hOAT4 are the sites of drug interactions between methotrexate and NSAIDs, probenecid, and penicillin G. Furthermore, it was predicted that hOAT3 is the site of drug interactions between methotrexate and salicylate, phenylbutazone, indomethacin, and probenecid in vivo.

Pharmacodynamics and pharmacokinetics of phenylbutazone in calves

Phenylbutazone (PBZ) was administered to six calves intravenously (i.v.) and orally at a dose rate of 4.4 mg/kg in a three-period cross-over study incorporating a placebo treatment to establish its pharmacokinetic and pharmacodynamic properties. Extravascular distribution was determined by measuring penetration into tissue chamber fluid in the absence of stimulation (transudate) and after stimulation of chamber tissue with the mild irritant carrageenan (exudate). PBZ pharmacokinetics after i.v. dosage was characterized by slow clearance (1.29 mL/kg/h), long-terminal half-life (53.4 h), low distribution volume (0.09 L/kg) and low concentrations in plasma of the metabolite oxyphenbutazone (OPBZ), confirming previously published data for adult cattle. After oral dosage bioavailability (F) was 66%. Passage into exudate was slow and limited, and penetration into transudate was even slower and more limited; area under curve values for plasma, exudate and transudate after i.v. dosage were 3604, 1117 and 766 microg h/mL and corresponding values after oral dosage were 2435, 647 and 486 microg h/mL. These concentrations were approximately 15-20 (plasma) and nine (exudate) times greater than those previously reported in horses (receiving the same dose rate of PBZ). In the horse, the lower concentrations had produced marked inhibition of eicosanoid synthesis and suppressed the inflammatory response. The higher concentrations in calves were insufficient to inhibit significantly exudate prostaglandin E2 (PGE2), leukotriene B4 (LTB4) and beta-glucuronidase concentrations and exudate leucocyte numbers, serum thromboxane B2 (TxB2), and bradykinin-induced skin swelling. These differences from the horse might be the result of: (a) the presence in equine biological fluids of higher concentrations than in calves of the active PBZ metabolite, OPBZ; (b) a greater degree of binding of PBZ to plasma protein in calves; (c) species differences in the sensitivity to PBZ of the cyclo-oxygenase (COX) isoenzymes, COX-1 and COX-2 or; (d) a combination of these factors. To achieve clinical efficacy with single doses of PBZ in calves, higher dosages than 4.4 mg/kg will be probably required.

In vitro anion transport alterations and apoptosis induced by phenylbutazone in the right dorsal colon of ponies

OBJECTIVES

To study the functional and structural responses of the right dorsal colon (RDC) of ponies to phenylbutazone (PBZ) in vitro at a concentration that could be achieved in vivo.

ANIMALS

8 adult ponies.

PROCEDURE

Short circuit current and conductance were measured in mucosa from the RDC. Tissues incubated with and without HCO3- were exposed to PBZ, bumetanide, or indomethacin. Bidirectional Cl- fluxes were determined. After a baseline flux period, prostaglandin E2 (PGE2) was added to the serosal surfaces and a second flux period followed. Light and transmission electron microscopy were performed.

RESULTS

Baseline short circuit current was diminished significantly by PBZ and indomethacin, and increased significantly after addictions of PGE2. After PGE2 was added, Cl- secretion increased significantly in tissues in HCO3- -free solutions and solutions with anti-inflammatory drugs, compared with corresponding baseline measurements and with control tissues exposed to PGE2. Bumetanide did not affect baseline short circuit current and Cl- fluxes. The predominant histologic change was apoptosis of surface epithelial cells treated with PBZ and to a lesser extent in those treated with indomethacin.

CONCLUSIONS AND CLINICAL RELEVANCE

Prostaglandin-induced Cl- secretion appeared to involve a transporter that might also secrete HCO3-. Both PBZ and indomethacin altered ion transport in RDC and caused apoptosis; PBZ can damage mucosa through a mechanism that could be important in vivo. The clinically harmful effect of PBZ on equine RDC in vivo could be mediated through its effects on Cl- and HCO3- secretion.

Evaluation of the influence of prostaglandin E2 on recombinant equine interleukin-1beta-stimulated matrix metalloproteinases 1, 3, and 13 and tissue inhibitor of matrix metalloproteinase 1 expression in equine chondrocyte cultures

OBJECTIVE

To determine the effects of prostaglandin E2 (PGE2) on recombinant equine interleukin (IL)-1beta-stimulated expression of matrix metalloproteinases (MMP 1, MMP 3, MMP 13) and tissue inhibitor of matrix metalloproteinase 1 (TIMP 1) in vitro.

SAMPLE POPULATION

Cultured equine chondrocytes.

PROCEDURE

Stationary monolayers of first-passage chondrocytes were exposed to graduated concentrations of PGE2 with or without a subsaturating dose (50 pg/ml) of recombinant equine IL-1beta (reIL-1beta) to induce expression of MMP 1, MMP 3, MMP 13, and TIMP 1, followed by RNA isolation and northern blotting. In subsequent experiments, gene expression was similarly quantified from mRNA isolated from cultures pretreated with phenylbutazone to quench endogenous PGE2 synthesis, followed by exposure to reIL-1beta and exogenous PGE2 (5 mg/ml) with appropriate controls.

RESULTS

Exogenous PGE2 (10 mg/ml) significantly reduced reIL-1beta-induced expression of MMP 1, MMP 3, MMP 13, and TIMP 1. Abrogation of cytokine induction with this dose of PGE2 was comparable to that for dexamethasone (10(-5) M) control. Similarly, pretreatment with phenylbutazone, followed by exposure to relL-1beta and PGE2 (5 mg/ml), was associated with a reduced expression of the genes of interest, an effect that was significant for MMP 1, MMP 13, and TIMP 1.

CONCLUSIONS AND CLINICAL RELEVANCE

The MMP and TIMP 1 are important mediators in the pathophysiologic events in osteoarthritis. The potential for physiologically relevant regulation of expression of these genes by PGE2 is a consideration in the use of drugs that inhibit prostanoid synthesis in the treatment of equine arthropathies.

Lipid peroxidation induced by phenylbutazone radicals

Lipid peroxidation was investigated to evaluate the deleterious effect on tissues by phenylbutazone (PB). PB induced lipid peroxidation of microsomes in the presence of horseradish peroxidase and hydrogen peroxide (HRP-H2O2). The lipid peroxidation was completely inhibited by catalase but not by superoxide dismutase. Mannitol and dimethylsulfoxide had no effect. These results indicated no paticipation of superoxide and hydroxyl radical in the lipid peroxidation. Reduced glutathione (GSH) efficiently inhibited the lipid peroxidation. PB radicals emitted electron spin resonance (ESR) signals during the reaction of PB with HRP-H2O2. Microsomes and arachidonic acid strongly diminished the ESR signals, indicating that PB radicals directly react with unsaturated lipids of microsomes to cause thiobarbituric acid reactive substances. GSH sharply diminished the ESR signals of PB radicals, suggesting that GSH scavenges PB radicals to inhibit lipid peroxidation. Also, 2-methyl-2-nitrosopropan strongly inhibited lipid peroxidation. R-Phycoerythrin, a peroxyl radical detector substance, was decomposed by PB with HRP-H2O2. These results suggest that lipid peroxidation of microsomes is induced by PB radicals or peroxyl radicals, or both.

Sperm-zona pellucida interaction involves a carbonyl reductase activity in the hamster

For successful fertilization to occur, the spermatozoa must transit through an egg-specific extracellular matrix or zona pellucida (zp) to reach and ultimately fuse with the oocyte plasma membrane. This process involves ligand-receptor recognition between the zp and the acrosomal cap of the sperm. The hamster sperm protein P26h, a receptor which is acquired during epididymal transit, has been suggested to act in sperm-zp binding. The cloning and characterization of the full-length cDNA-encoding hamster P26h revealed 85% identity with a porcine lung carbonyl reductase. To better understand the mechanism by which P26h interacts with zp proteins, we investigated carbonyl reductase activity during gamete interactions. In the present study, we show that specific inhibitors of carbonyl reductase such as diclofenac and phenylbutazone decreases sperm-zp binding without affecting the motility, progressivity or acrosome integrity of sperm. We also detected, and partly purified, carbonyl reductase activities from cauda epididymal sperm protein extract and this activity was associated with an enriched fraction of P26h. Removing P26h from the partly purified protein fractions by immunoaffinity chromatography led to the loss of carbonyl reductase activity. The findings that sperm-zp binding is blocked by carbonyl reductase inhibitors and that P26h is active in mature sperm suggest that P26h could play an important role in the fertilization process.