Pharmacodynamic comparison of LY3023703, a novel microsomal prostaglandin e synthase 1 inhibitor, with celecoxib.

To assess the safety, tolerability, and pharmacology of LY3023703, a microsomal prostaglandin E synthase 1 (mPGES1) inhibitor, a multiple ascending dose study was conducted. Forty-eight subjects received LY3023703, celecoxib (400 mg), or placebo once daily for 28 days. Compared with placebo, LY3023703 inhibited ex vivo lipopolysaccharide-stimulated prostaglandin E2 (PGE2 ) synthesis 91% and 97% on days 1 and 28, respectively, after 30-mg dosing, comparable to celecoxib's effect (82% inhibition compared to placebo). Unlike celecoxib, which also inhibited prostacyclin synthesis by 44%, LY3023703 demonstrated a maximal increase in prostacyclin synthesis of 115%. Transient elevations of serum aminotransferase were observed in one subject after 30-mg LY3023703 dosing (10× upper limit of normal (ULN)), and one subject after 15-mg dosing (about 1.5× ULN). Results from this study suggest that mPGES1 inhibits inducible PGE synthesis without suppressing prostacyclin generation and presents a novel target for inflammatory pain.

Oxidation and keto reduction of 12-hydroxy-5,8,10,14-eicosatetraenoic acids in bovine corneal epithelial microsomes.

The R and S enantiomers of 12-hydroxyeicosatetraenoic acid (12-HETE) exhibit different biological activities. Although they appear to be produced by different enzymatic pathways, cytochrome P-450 monooxygenase and lipoxygenase, respectively, they display similar metabolism in both corneal epithelium and neutrophils. In corneal epithelial microsomes, both enantiomers are subject to oxidation and keto reduction reactions to form the dihydro metabolite, 12-hydroxy-5,8,14-eicosatrienoic acid (12-HETrE), via a keto intermediate. The apparent Km for the formation of 12-HETrE was 17.9 and 20 microM for 12(R)-HETE and 12(S)-HETE, respectively, and the apparent Vmax of the reaction was 17.4 and 8.2 pmol/mg per min, respectively. Chiral analysis of the dihydro metabolite demonstrated a product enantiospecificity. Arachidonic acid, 12(R)-HETE, 12(S)-HETE and the intermediate of this reaction, 12-oxo-ETrE, were metabolized predominantly to 12(R)-HETrE in a ratio [12(R)-HETrE: 12(S)-HETrE] of 7.3:1, 4.3:1, 1.5:1 and 2.3:1, respectively. 12(R)-HETrE is a potent vasodilator, chemotactic and angiogenic factor whose synthesis is induced in inflamed tissues; 12(S)HETrE is devoid of these properties. 12(R)-HETE, derived from NADPH-dependent cytochrome P-450 monooxygenases, and 12(S)-HETE, derived from 12-lipoxygenase, may both play an important role in regulating the inflammatory response by serving as substrates for the local synthesis of 12(R)-HETrE.

Results from the IQ-CSRC prospective study support replacement of the thorough QT study by QT assessment in the early clinical phase.

The QT effects of five "QT-positive" and one negative drug were tested to evaluate whether exposure-response analysis can detect QT effects in a small study with healthy subjects. Each drug was given to nine subjects (six for placebo) in two dose levels; positive drugs were chosen to cause 10 to 12 ms and 15 to 20 ms QTcF prolongation. The slope of the concentration/ΔQTc effect was significantly positive for ondansetron, quinine, dolasetron, moxifloxacin, and dofetilide. For the lower dose, an effect above 10 ms could not be excluded, i.e., the upper bound of the confidence interval for the predicted mean ΔΔQTcF effect was above 10 ms. For the negative drug, levocetirizine, a ΔΔQTcF effect above 10 ms was excluded at 6-fold the therapeutic dose. The study provides evidence that robust QT assessment in early-phase clinical studies can replace the thorough QT study.

The 22K variant of rat prolactin: evidence for identity to prolactin-(1-173), storage in secretory granules, and regulated release.

Western blot analyses of the rat pituitary have detected a 22K PRL variant distinct from intact PRL (25K). We recently reported that glandular kallikrein (GK), an estrogen-induced lactotroph protease, can process PRL in vitro from a 25K form to a 22K form in a thiol-dependent cleavage at Arg174-Arg175 to remove 23 amino acids. We also detected an estrogen- and thiol-induced 22K PRL variant in the rat pituitary comigrating with a PRL product generated by in vitro processing with GK and carboxypeptidase-B. This study addressed whether the in vivo 22K PRL variant originates through a GK-like cleavage and is a regulated secretory product of the rat pituitary. A polyclonal antipeptide antiserum was raised against a synthetic peptide [PRL-(163-173)] representing the new C-terminus after GK and carboxypeptidase-B processing. In slot and Western blots, this antiserum (CT-antiserum) specifically recognized PRL processed in vitro by GK and carboxypeptidase-B and did not recognize intact PRL or PRL cleaved by GK alone. Western blot analysis of rat pituitary extracts with CT-antiserum specifically detected an estrogen- and thiol-induced 22K band that comigrated with a PRL product generated by in vitro processing with GK and carboxypeptidase-B. This 22K band was concentrated in subcellular fractions of the pituitary enriched in secretory granules. During short term incubations in medium 199, pituitaries from normal adult female rats released substantial amounts of 22K PRL; in contrast, male pituitaries did not release detectable 22K PRL. The release of 22K PRL from female pituitaries was powerfully blocked by bromocriptine, a dopaminergic agonist. GK was also released from pituitaries of female, but not male, rats, and GK release was inhibited by bromocriptine. The results identify the 22K PRL variant as PRL-(1-173), which is consistent with GK-like processing at Arg174-Arg175, followed by carboxypeptidase-B-like processing. The results also show that 22K PRL is a natural female-specific secretory product of the rat pituitary under inhibitory dopaminergic control.

Alkali burn-induced synthesis of inflammatory eicosanoids in rabbit corneal epithelium.

PURPOSE: Alkali burning of the rabbit cornea is a well-established model for the study of anterior surface inflammation, neovascularization, and wound-healing processes. 12-hydroxyeicosanoids have been implicated as mediators of such responses. 12(S)-hydroxyeicosatetraenoic acid (12[S]-HETE) is a lipoxygenase-derived arachidonate metabolite and 12(R)-hydroxyeicosatetraenoic acid (12[R]-HETE) is formed by a cytochrome P450 monooxygenase; both give rise to the potent angiogenic factor 12(R)-hydroxyeicosatrienoic acid (12[R]-HETrE). In this study, the authors correlate the pattern of their synthesis in the corneal epithelium with the inflammatory response after alkali injury. METHODS: New Zealand albino rabbits were anesthetized and alkali burns created with 10-mm filter paper discs (1 N NaOH for 2 minutes). Corneas were then rinsed; 1 to 7 days later, corneal epithelium was scraped and used to assess 14C-arachidonic acid conversion to 12-HETE and 12-HETrE enantiomers in the presence of NADPH by chiral high-pressure liquid chromatography. The inflammatory response secondary to the alkali burn was quantified through area measurements of reepithelialization and neovascularization. RESULTS: Alkali burn induced a time-dependent production of corneal epithelial 12-HETE and 12-HETrE. A marked increase in 12-HETE and 12-HETrE synthesis was evident at day 2 (from 22 +/- 7 to 139 +/- 22 ng/hour) after injury, increasing to 800 +/- 68 ng/hour at day 7. Chiral analysis revealed a time-dependent synthesis of the R and S enantiomers of 12-HETE (24% R, 76% S) and 12-HETrE (72% R, 28% S). Total arachidonate metabolism, as well as the formation of 12(R)-HETrE, correlated with the area of neovascularization (P < 0.01 and P < 0.02, respectively). CONCLUSIONS: The results demonstrate that surviving and regenerating epithelium has an increased capacity of synthesizing 12(S)-HETE and 12(R)-HETE and that maximal production of 12(R)-HETrE, a known direct and indirect angiogenic factor, coincides with neovascularization in this model. Thus, the lipoxygenase and cytochrome P450-dependent activities increased in a time-dependent manner, indicating the potential involvement of both pathways in the inflammatory response to alkali burn. The formation of significant quantities of 12(R)-HETE and 12(R)-HETrE is a novel finding in this alkali injury model.

A closed eye contact lens model of corneal inflammation. Part 1: Increased synthesis of cytochrome P450 arachidonic acid metabolites.

PURPOSE: To characterize a model of contact lens-induced corneal inflammation in the closed eye, with respect to inflammatory parameters and the metabolism of arachidonic acid by homogenates of the corneal epithelium. METHODS: Rabbit eyes were fitted with extended wear etafilcon A (58% water) hydrogel contact lenses in stacked fashion (two lenses per eye), followed by a silk suture tarsorrhaphy of approximately 90%. The anterior surface was analyzed over a 9-day period for inflammatory events through slit lamp biomicroscopy, subjective inflammatory scoring, corneal pachymetry, and corneal epithelial [1-(14)C]-arachidonic acid metabolism. RESULTS: Hydrogel contact lens wear in the closed eye resulted in a progressive anterior surface inflammatory response correlated over time (r = 0.999). Central corneal thickness progressively increased and was also correlated to the inflammatory score (r = 0.995). [1-(14)C]-arachidonic acid metabolism by homogenates of the corneal epithelium resulted in the time-dependent formation of two major products, 12-hydroxyeicosatetraenoic acid (12-HETE) and 12-hydroxyeicosatrienoic acid (12-HETrE). Correlations were established between the synthesis of 12-HETE and 12-HETrE, the subjective inflammatory score (r = 0.963) and the progressive increase in corneal thickness (r = 0.971), over 9 days. CONCLUSIONS: With this model of contact lens wear, eicosanoid synthesizing capacity of the corneal epithelium showed a time-dependent increase in the production of 12-HETE and 12-HETrE strongly correlating to the in situ inflammatory response. The relationship between 12-HETE and 12-HETrE synthesis and the degree of anterior surface inflammation implicate these eicosanoids, among others, as mediators of the inflammatory response to hydrogel contact lens wear in the closed eye.

A closed eye contact lens model of corneal inflammation. Part 2: Inhibition of cytochrome P450 arachidonic acid metabolism alleviates inflammatory sequelae.

PURPOSE: The authors have previously shown a marked increase in corneal epithelial arachidonic acid metabolism to 12-hydroxyeicosatetraenoic acid (12-HETE) and 12-hydroxyeicosatrienoic acid (12-HETrE) in a model of closed eye-contact lens wear. Their formation was predominantly cytochrome P450-dependent and significantly correlated with inflammatory score and corneal thickness. In the current study, the authors used stannous chloride to inhibit the epithelial cytochrome P450-dependent synthesis of 12-HETE and 12-HETrE to assess the role of these eicosanoids as mediators of the inflammatory response to contact lens wear in the closed eye. METHODS: Hydrogel contact lenses were soaked in stannous chloride (100 micrograms/ml) or vehicle and fitted to the rabbit eye in stacked fashion (two lenses/eye), followed by a silk suture tarsorrhaphy of approximately 90%. Eyes were analyzed over a 7-day period for inflammatory responses through slit lamp biomicroscopy, subjective inflammatory scoring, ultrasonic pachymetry, and corneal epithelial [1-14C]-arachidonic acid metabolism. RESULTS: Closed eye-hydrogel contact lens wear resulted in a progressive anterior surface inflammatory response. Coinciding with these events was a time-dependent increase in corneal thickness and 12-HETE and 12-HETrE production rates by corneal epithelial homogenates. Treatment of the lenses with stannous chloride (100 micrograms/ml) significantly attenuated by day 7 the inflammatory score (56% decrease), corneal thickness (17% decrease), and 12-HETE and 12-HETrE synthesis (77% and 71% decrease, respectively). CONCLUSIONS: This study further substantiates the involvement of cytochrome P450, through the synthesis of 12-HETE and 12-HETrE, in the inflammatory response associated with hydrogel contact lens wear in the closed eye. Thus, inhibition of cytochrome P450, with subsequent decreases in 12-HETE and 12-HETrE, may attenuate the pathophysiologic response to contact lens wear in the closed eye.

Adenovirus-mediated heme oxygenase-1 gene transfer into rabbit ocular tissues.

PURPOSE: Heme oxygenase-1 (HO-1) is a stress protein induced up to 100-fold within a few hours after exposure to oxidative stress, and it has been shown to counteract oxidative injury induced by ultraviolet light or free radicals. The current study was undertaken to determine whether the HO-1 gene can be introduced into adult rabbit ocular tissues by microinjection of a recombinant replication-deficient adenovirus human HO-1 cDNA (Adv-HHO). METHODS: Human HO-1 gene was used for transfection studies to differentiate endogenous from transfected HO. The purified Adv-HHO construct (10(8) pfu/ml) was mixed with lipofectamine and microinjected into the anterior chamber, vitreous cavity, and subretinal space of New Zealand rabbit eyes. After 2 weeks, total RNA was extracted from different ocular tissues, reverse transcription-polymerase chain reaction was performed using specific human HO-1 primers, and amplification products were subjected to Southern hybridization. RESULTS: Transfection with the Adv-HHO construct into rabbit corneal epithelial cells in culture resulted in a functional expression of the human HO-1 gene; the human HO-1 mRNA was detected, and enzyme activity increased threefold. Human HO-1 mRNA was detected in the retina after microinjection of the Adv-HHO construct into the subretinal space. Microinjection into the vitreous resulted in HO-1 mRNA expression in the corneal endothelium, iris, lens, and retina; after intracameral injection of the Adv-HHO construct, human HO-1 mRNA was detected in corneal epithelium and endothelium, ciliary body, lens, and iris. Regardless of the injection site, transfected human HO-1 mRNA was undetectable in tissues outside the eye, that is, brain, liver, and kidney. CONCLUSIONS: These results demonstrated a tissue-selective functional transfer of the human HO-1 gene into rabbit ocular tissues in vivo. This technique may be a promising means for delivering HO-1 gene in vivo as a protective mechanism against oxidative stress that contributes to the pathogenesis of ocular diseases such as cataract, light-induced injury, age-related macular degeneration, and diabetic retinopathy.

Pharmacodynamics, safety, tolerability, and pharmacokinetics of the 0.8-mg dose of cerivastatin in patients with primary hypercholesterolemia.

Cerivastatin is a third generation hydroxy-methyl-glutaryl-Co-enzyme A (HMG-CoA) reductase inhibitor proven to lower low-density lipoprotein (LDL) cholesterol 28% to 31% in patients with primary hypercholesterolemia when given at 0.3 mg/day. This study evaluates the safety, tolerability, pharmacodynamics, and pharmacokinetics of cerivastatin 0.8 mg once daily for 4 weeks. In this randomized, double-blind, placebo-controlled parallel group trial conducted at 2 study centers, 41 patients (63% women) with primary hypercholesterolemia were placed on an American Heart Association Step 1 diet for 4 weeks. Single-blind placebo was administered for the final 2 weeks, before randomization. Patients received cerivastatin 0.8 mg (n = 28) or placebo (n = 13) once each evening for 28 days. Cerivastatin at 0.8 mg daily was well tolerated. No discontinuations occurred during the study. Adverse events were mild and transient. One cerivastatin-treated patient experienced asymptomatic creatinine kinase, 8x the upper limit of normal (ULN) elevation on the last day of the study, which resolved 6 days after the completion of the study. Cerivastatin 0.8 mg daily significantly reduced LDL cholesterol compared with placebo (-44.0 +/- 2.0% vs 2.2 +/- 2.8%, p <0.0001); total cholesterol (-30.8 +/- 1.4% vs 2.6 +/- 2.1%, p <0.0001), triglycerides (-11.2 +/- 5.9% vs 15.9 +/- 8.6%, p <0.02), but did not significantly alter high-density lipoprotein (HDL) cholesterol (3.2 +/- 2.1% vs -1.2 +/- 3.1%, p = NS). The pharmacokinetics of the 0.8-mg dose revealed dose proportional elevations in the 24-hour area under the curve and maximum plasma concentration relative to 0.3- and 0.4-mg doses with no change in time to maximum concentration or the elimination half-life in plasma. The increased efficacy and lack of clinically significant laboratory abnormalities or adverse events demonstrates a need for a large long-term study to confirm the safety and efficacy of this dose of cerivastatin.

Pharmacokinetics and pharmacodynamics of peldesine (BCX-34), a purine nucleoside phosphorylase inhibitor, following single and multiple oral doses in healthy volunteers.

The pharmacokinetic parameters of peldesine (BCX-34) were investigated after single and multiple oral doses in two groups of healthy adult volunteers. The pharmacodynamic elevation of endogenous inosine and 2'-deoxyguanosine was simultaneously monitored. The first group of 8 subjects received an intravenous dose (18 mg/m2) and five oral doses (30, 63, 108, 144, and 192 mg/m2) of drug. A second group of 12 subjects received 160 mg/m2 in four and in six divided doses orally. Serial blood samples and total urine outputs were collected during dosing and for at least 24 hours after the last dose was administered. One set of samples was analyzed using high-pressure liquid chromatography/ultraviolet (LC/UV) methods, validated for intact drug in human plasma and urine samples. Another set of samples was analyzed for the biomarkers, inosine and 2'-deoxyguanosine, using high-pressure LC with either mass spectrometry (MS) or electrochemical detection (EC) methods. The pharmacokinetic parameters of inosine and 2'-deoxyguanosine were calculated using noncompartmental methods and correlated against the pharmacokinetic parameters of BCX-34. For the single-dose study, the results exhibited linear pharmacokinetics over the dose range from 30 to 144 mg/m2. The calculated terminal half-life was 3.5 +/- 1.0 h, and the absolute bioavailability of the oral formulation was approximately 51%. Analysis of urine in the first 24 hours of collection accounted for approximately 82% of the absorbed intact drug. Evaluation of the multiple-dose pharmacokinetics indicated that steady-state blood concentrations were achieved by 24 hours when the drug was administered four or six times a day. A drug dose-related elevation of plasma 2'-deoxyguanosine was observed. This phenomenon was not seen with plasma inosine levels. However, analysis of urine samples showed an increase in inosine output with an increase in the drug dose. The calculated terminal half-life of inosine and 2'-deoxyguanosine was 15.3 +/- 1.8 h and 1.3 +/- 0.1 h, respectively.

Valsartan, a new angiotensin II antagonist for the treatment of essential hypertension: efficacy, tolerability and safety compared to an angiotensin-converting enzyme inhibitor, lisinopril.

OBJECTIVE: To compare the efficacy, safety and tolerability of valsartan to an angiotensin-converting enzyme (ACE) inhibitor, lisinopril, and placebo in patients with mild-to-moderate essential hypertension. DESIGN: A total of 734 men and women were randomised in this multicentre, double-blind, optional titration, parallel group trial. Volunteers received valsartan 80 mg (n = 364), lisinopril 10 mg (n = 187) or placebo (n = 183) daily for 4 weeks, with subsequent titration of dose depending on response to treatment (valsartan 80 mg titrated to valsartan 160 mg once daily or valsartan 80 mg twice daily, lisinopril 10 mg titrated to lisonopril 20 mg once daily). Patients were assessed at 4, 8 and 12 weeks. MAIN OUTCOME MEASURES: The primary variable was change from baseline in mean sitting diastolic blood pressure (SDBP). Other efficacy variables included sitting systolic blood pressure (SSBP) and percentage of 'successful' responders (SDBP <90 mm Hg or > or =10 mm Hg reduction from baseline). RESULTS: All active treatment groups were shown to demonstrate significant reductions in SDBP compared to placebo at endpoint of therapy (least mean square reduction from baseline: valsartan 80/160 mg: -5.25 mm Hg (Cl -7.17, -3.34, P< 0.001); valsartan 80/80 mg twice daily: -5.63 mm Hg (Cl -7.51, -3.75, P< 0.001); lisinopril 10/20 mg: -6.93 mm Hg, (Cl -8.81, -5.05, P< 0.001). There were no statistically significant differences between the active treatment groups at endpoint of therapy. In patients requiring titration to a higher dose (placebo n = 142, valsartan 80/80 twice daily n = 124, valsartan 80/160 n = 114, lisinopril 10/20 n = 120), there were no significant treatment differences between valsartan 160 mg given as a single daily dose or as 80 mg twice daily (P = 0.658). Both valsartan and lisinopril produced similarly high percentages of 'successful' responders at endpoint of therapy. A somewhat higher frequency of drug related cough was observed in lisinopril treated patients (8%) compared to valsartan (1.1%) or placebo (0.5%). CONCLUSIONS: Valsartan 80 mg daily, with titration to 160 mg daily as required, provides similar antihypertensive efficacy to lisinopril 10 mg daily with titration to 20 mg daily. Valsartan provides a new antihypertensive agent with comparable efficacy to lisinopril and appears to be associated with a reduced incidence of cough.

Gastric emptying, pulmonary function, gas exchange, and respiratory quotient after feeding a moderate versus high fat enteral formula meal in chronic obstructive pulmonary disease patients.

High fat enteral formulas have been advocated for the nutritional support of chronic obstructive pulmonary disease (COPD) patients because dietary fat utilization under ideal conditions produces less CO2 per O2 consumed than carbohydrate. No data exist for these patients comparing the effects of a moderate fat vs. a high fat enteral formula on gastric emptying times (GE) and subsequent CO2 production (VCO2), oxygen consumption (VO2), respiratory quotient (RQ), and pulmonary function. Our double-blind crossover study compared these parameters after feeding a 355 mL (530 kcal) meal with either 41% fat calories (Respalor) or 55% fat calories (Pulmocare). Thirty-six COPD outpatients with a forced expiratory volume in 1 s (FEV1) < 60% of predicted were studied after an overnight fast. Gastric emptying half-time (GE t1/2) was measured using the 99MTc-radionuclide technique; VCO2, VO2, RQ, and other pulmonary functions were measured at 0, 30, 90, and 150 min postprandial using the Canopy Mode of the Deltatrac Metabolic Monitor and the Renaissance Spirometry System. We observed a significantly (p = 0.0001) longer GE t1/2 of the high fat meal when compared to the moderate fat meal (134.1 vs. 108.6 min) At 30 and 90, but not at 150 min postprandial, the VCO2 and VO2 for patients fed the moderate-fat formula were significantly (p = 0.05) higher than for those fed the high-fat formula; no differences were observed for the other pulmonary functions. Although RQ increased significantly (p = 0.01) after both meals, no differences between formulas were noted at all postprandial times tested. Compared to the high-fat meal, the moderate-fat meal significantly enhanced gastric emptying. The earlier rise in VCO2 and VO2 after the moderate-fat meal did not impact pulmonary function and reflected the earlier utilization of the moderate-fat meal. The fact that RQ was not different between the two meals at all postprandial times tested suggest that the higher rise in VCO2 and VO2 after the moderate-fat meal was most likely due to earlier gastric emptying of the moderate-fat meal rather than the difference of the fat-to-carbohydrate ratio between the two tested meals. The impact of these findings on long-term management of COPD patients awaits long-term prospective studies.

Diminished heme oxygenase-1 mRNA expression in RPE cells from diabetic donors as quantitated by competitive RT/PCR.

PURPOSE: The RPE is essential in the maintenance of retinal vasculature homeostasis, since increased cellular expression of heme oxygenase-1 (HO-1) has been implicated as a defense mechanism against oxidative stress. This study was done in an effort to determine the levels of the stress protein (32 kD), HO-1, in retinal pigment epithelium (RPE) cells obtained from diabetic and normal eyes. METHODS: We measured the levels of HO-1 in the RPE from eight normal and six diabetic donor eyes. For comparison, HO-1 levels were assayed in RPE cells from four donor eyes with long-standing hypertension. Heme oxygenase-1 mRNA copy number was determined by competitive RT/PCR on various ex vivo samples and on RPE cultured from the same donors. Total RNA (1-200 ng) was reverse-transcribed and then amplified by PCR in the same tube as an internal standard obtained by deleting a 50 bp restriction site from the native HO-1 gene. RESULTS: Relative to the RPE obtained from control donor eyes, RPE from diabetic donors exhibited significantly decreased levels of HO-1 mRNA. In contrast, no significant difference in the levels of HO-1 mRNA was observed in RPE samples derived from hypertensive donor eyes. The diabetic group showed a range of 340-450 HO-1 mRNA copies/ng of total RNA, as compared to 425-8,000 HO-1 mRNA copies/ng of total RNA in RPE from normal donors and 460-7605 copies/ ng in hypertensive donor eyes. CONCLUSIONS: This study represents initial studies exploring the quantitative expression of heme oxygenase in the RPE human eyes. The decreased expression of HO-1, a stress/heat shock protein, may in the RPE contribute to the vulnerability of the neuroretina to significant metabolic alterations encountered in the diabetic state. This was a limited study; additional screening from different donor eyes will be done in order to establish the relationship between RPE, HO-1 expression and eye diseases in which oxidative stress is believed to be a determinant in the pathophysiology.

High affinity binding sites for 12(R)-Hydroxyeicosatrienoic acid [12(R)-HETrE] in microvessel endothelial cells.

12(R)-HETrE is an NADPH-dependent arachidonic acid-derived metabolite whose synthesis is induced several fold in inflamed corneal epithelium correlating with the development of the in situ inflammatory response, i.e., vasodilation, PMN chemotaxis, endothelial cell mitogenesis, and neovascularization. Because this novel eicosanoid may serve as an endogenous mediator of the angiogenic response in the cornea during inflammation we probed microvessel endothelial cells for a specific binding site which could possibly account for the mechanism by which this eicosanoid initiates changes in cellular activity. Binding of radioactive ligand [3H-12(R)-HETrE] was saturable with time and concentration. Scatchard analysis indicated a single, saturable binding site for 12(R)-HETrE with a Bmax = 24,700 sites/cell and an apparent Kd = 0.043 nM. Thin layer chromatography analysis of cell-associated ligand revealed that esterification of 12(R)-HETrE was 2-7 fold less than unesterified, cell bound ligand. The concentrations of 12(R)-HETrE at which maximum biological activity has been observed, i.e., 0.1 nM, roughly corresponds to the Kd value, suggesting a functional link to this binding site. These studies begin to reveal a potential mechanism by which 12(R)-HETrE stimulates microvessel endothelial cells to invade the cornea leading to corneal neovascularization.

Chiral analysis of 12-hydroxyeicosatetraenoic acid formed by calf corneal epithelial microsomes.

The production of 12-hydroxyeicosatetraenoic acid by the corneal epithelium of several species has been extensively reported yet the controversy over the exclusive production of the (S) epimer (a lipoxygenase-derived metabolite) endures. Incubation of calf corneal epithelial microsomes (3 mg/ml) with arachidonic acid and NADPH resulted in the formation of 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE). The synthesis of 12-HETE was inhibited by SKF-525A and clotrimazole, selective inhibitors of cytochrome P450 dependent activities, but not by indomethacin or BW-755C, inhibitors of cyclooxygenase and lipoxygenase activities, respectively. Chiral analysis revealed the presence of both enantiomers; however, the R isomer was the predominant one, i.e., 91 +/- 5% vs. 9 +/- 5% for the R and S enantiomers, respectively. Since the R enantiomer is the product of a cytochrome P450-mediated reaction, it suggests that the major metabolic activity in these microsomes is cytochrome P450-dependent and supports the claim for cytochrome P450 reactions in this ocular tissue.

Modulation of corneal heme oxygenase expression by oxidative stress agents.

Heme oxygenase, the rate-limiting enzyme in the degradation of heme to bile-pigments and carbon monoxide, is induced in response to increased oxidative stress and is believed to provide a cytoprotective effect. We investigated the role of heme oxygenase in cultured rabbit corneal epithelial cells (RCE), and its potential to alleviate oxidative stress-induced cell damage. Heme oxygenase in RCE was effectively and potently induced by most metals tested, including tin, silver, and gold, and cytokines such as IL-6, and TGF beta. Stannous chloride and heme-induced heme oxygenase mRNA by 40 and 100 fold within 1-3 hours and increased enzyme activity by 9.2- and 10-fold, respectively, over a 24 hour period. IL-6, TGF beta and H2O2 induced heme oxygenase by 2-3 fold. Zinc protoporphyrins were effective inhibitors of heme oxygenase activity in vitro. However, when incubated with cells for 24 h they induced heme oxygenase mRNA but decreased or had no effect on its activity. Administration of heme, SnCl2, and H2O2 resulted in some degree of glutathione perturbation (GSH/GSSG). However, in all cases, depletion of glutathione was exacerbated if heme oxygenase was simultaneously inhibited. Conversely, perturbation of glutathione levels was minimized if heme oxygenase was induced by heme or stannous chloride. These results demonstrate that RCE cells exhibit functional heme oxygenase activity which is inducible in response to inflammatory cytokines and oxidative stress agents and suggest a cytoprotective role for heme oxygenase against cell injury.

Effects of specific criteria and calibration on examiner reliability.

The purpose of this pilot study was to investigate the use of specific criteria and examiner calibration on the reliability of inexperienced examiners on dental sealant evaluations. Dental (N = 8) and dental hygiene (N = 8) students participated as examiners. The study objectives were to identify differences in calibrated and non-calibrated examiners, examiners calibrated by an expert or non-expert, and reliability between dental and dental hygiene student examiners. A criterion-referenced evaluation form was used to evaluate dental sealant end product on 20 teeth, twice by each examiner. Eight of 16 examiners participated in a one-hour calibration session between evaluations. The session consisted of a discussion of operational definitions, the evaluation procedure for dental sealants, and use of the criterion-referenced form. Intra- and interexaminer reliabilities were measured. There were no statistically significant differences (p less than .05) in intraexaminer reliability. Although calibration produced no significant increase in interexaminer reliability, the post-training reliability scores for the group calibrated by an expert decreased, and scores for the group calibrated by a non-expert increased. No significant difference was found in reliability between dental and dental hygiene student examiners.

A phase I/II randomized, double-blind, placebo-controlled, dose-ranging study evaluating the efficacy, safety and pharmacokinetics of ravuconazole in the treatment of onychomycosis.

OBJECTIVE: To determine the effectiveness and safety of ravuconazole in the treatment of toenail onychomycosis. DESIGN: A phase I/II randomized, double-blind, double-dummy, placebo-controlled, dose-ranging study. Four 12-week dosing regimens were used: 200 mg/day; 100 mg/week; 400 mg/week and placebo. Subjects returned at weeks 2, 4, 6, 8, 10, 12, 14, 16, 24, 36 and 48 for assessment. Subjects were enrolled at 10 dermatology practices (seven in the United States, one in Canada, two in France). SUBJECTS: Adults with distal subungual onychomycosis of one great (hallux) toenail (minimum area of 25%), and at least 2 mm of proximal nail clear of disease were selected. Onychomycosis was confirmed by direct microscopy and/or fungal culture. Subjects with conditions known to produce abnormal-appearing nails were excluded. One hundred and fifty-one subjects were randomized in a 2:2:2:1 ratio to the treatments above. MAIN OUTCOME MEASURES: Primary efficacy was the effective cure rate at week 48 (mycological cure, and clinical cure or > 30% improvement). RESULTS: Effective cure was found in 56% of subjects using 200 mg/day. Effective cure was 10% in subjects receiving 100 mg/week, 8% of subjects using 400 mg/week, and 15% of subjects using placebo. Mycological cure was seen in 59% of subjects in the 200-mg/day group, which was significantly higher than the rates found in the other groups. Drug-related adverse events were infrequent in all treatment arms. Headache was the most frequently reported event. Abnormal laboratory tests were infrequent over the 12 weeks of dosing. Abnormal laboratory findings with increases beyond normal of Grade 2, 3 or 4 were found in 8/148 subjects (5.4%). Only the 200 mg daily regimen had a mean plasma steady state concentration of ravuconazole exceeding the MIC(90) adjusted for 98% protein binding (3000 ng/mL). CONCLUSIONS: For the treatment of onychomycosis, ravuconazole 200 mg/day for 12 weeks is the most effective of the regimens investigated. The safety of all regimens was acceptable. The concentrations of ravuconazole in the plasma compared to the adjusted MIC(90) may be useful in predicting the clinical and mycologic response of therapy.