Comparison of two techniques using hyaluronic acid to correct the tear trough deformity.

BACKGROUND: Hyaluronic acid (HA) can be used to correct volume loss associated with periorbital aging. OBJECTIVE: To report and compare the efficacy and safety of HA used to treat tear trough deformities with two different injection techniques. MATERIALS AND METHODS: This is a retrospective, single-center study of 81 patients comparing the two injection techniques used for the treatment of tear trough deformities from 2003 to 2011. Hyaluronic acid was administered either in a single depot in the nasojugal groove and massaged into position or in multiple small aliquots along the inferior orbital rim and massaged into position. Patient satisfaction and the incidence of adverse reactions were evaluated. RESULTS: Of the 194 patients treated during the study period, 81 (42%) were successfully contacted. The overall patient satisfaction with the correction was similar for both techniques. Two patients treated with a single depot of HA were later given hyaluronidase, but otherwise, there was no statistically significant difference in the incidence and severity of side effects. CONCLUSIONS: We describe and compare an alternative technique for the correction of tear trough deformity using a single deposition of HA in the nasojugal groove with favorable outcomes.

The effect of rifampin administration on the disposition of fexofenadine.

OBJECTIVE: Our objective was to assess the effect of rifampin (INN, rifampicin) on the pharmacokinetics of fexofenadine and to assess the influence of advanced age and sex. METHODS: Twelve young volunteers (6 men and 6 women; age range, 22 to 35 years) and twelve elderly volunteers (6 men and 6 women; age range, 65 to 76 years) received a 60-mg oral dose of fexofenadine before and after treatment with 600 mg of oral rifampin for 6 days. Blood and urine were collected for 48 hours and assayed for fexofenadine, azacyclonol, and rifampin by HPLC with either fluorescence or mass spectrometry detection. RESULTS: All of the groups had a significant increase (P <.05) in the oral clearance of fexofenadine after rifampin treatment: young men, 2955 +/- 1516 versus 5524 +/- 3410 mL/min; young women, 2632 +/- 996 versus 7091 +/- 5,379 mL/min; elderly men, 1760 +/- 850 versus 4608 +/- 1159 mL/min; and elderly women, 2210 +/- 554 versus 4845 +/- 1600 mL/min. The peak serum concentration of fexofenadine was also significantly reduced (P <.05) by rifampin treatment: young men, 77 +/- 31 versus 52 +/- 17 ng/mL; young women, 72 +/- 19 versus 36 +/- 14 ng/mL; elderly men, 106 +/- 42 versus 52 +/- 14 ng/mL; elderly women, 76 +/- 23 versus 46 +/- 19 ng/mL. Half-life (150 to 230 minutes), time to maximum concentration (130 to 205 minutes), renal clearance (95 to 153 mL/min), and fraction unbound (2.9% to 3.7%) of fexofenadine showed no significant difference between control and treatment. The amount of azacyclonol, a CYP3A4 mediated metabolite of fexofenadine, eliminated renally increased on average 2-fold after rifampin dosing; however, this pathway accounted for less than 0.5% of the dose. No effect of age or sex on fexofenadine disposition or serum trough rifampin concentration (0.2 microg/mL to 1.8 microg/mL) was observed before or after rifampin treatment. CONCLUSION: This study showed that rifampin effectively increased fexofenadine oral clearance and that this effect was independent of age and sex. We conclude that the cause of the increased oral clearance of fexofenadine is a reduced bioavailability caused by induction of intestinal P-glycoprotein.

The effects of St John's wort (Hypericum perforatum) on human cytochrome P450 activity.

BACKGROUND: St John's wort (Hypericum perforatum) is a popular over-the-counter dietary supplement and herbal remedy that has been implicated in drug interactions with substrates of several cytochrome P450 (CYP) isozymes. The effect of St John's wort on CYP activity in vivo was examined with a probe drug cocktail. METHODS: Twelve healthy subjects (5 female, 7 male) completed this 3-period, open-label, fixed schedule study. Tolbutamide (CYP2C9), caffeine (CYP1A2), dextromethorphan (CYP2D6), oral midazolam (intestinal wall and hepatic CYP3A), and intravenous midazolam (hepatic CYP3A) were administered before, with short-term St John's wort dosing (900 mg), and after 2 weeks of intake (300 mg 3 times a day) to determine CYP activities. RESULTS: Short-term administration of St John's wort had no effect on CYP activities. Long-term St John's wort administration caused a significant (P <.05) increase in oral clearance of midazolam from 121.8 +/- 70.7 to 254.5 +/- 127.8 and a corresponding significant decline in oral bioavailability from 0.28 +/- 0.15 to 0.17 +/- 0.06. In contrast to the >50% decrease in the area under the plasma concentration-time curve (AUC) when midazolam was administered orally, long-term St John's wort administration caused a 20% decrease in AUC when midazolam was given intravenously. There was no change in CYP1A2, CYP2C9, or CYP2D6 activities as a result of St John's wort administration. CONCLUSION: Long-term St John's wort administration resulted in a significant and selective induction of CYP3A activity in the intestinal wall. St John's wort did not alter the CYP2C9, CYP1A2, or CYP2D6 activities. Reduced therapeutic efficacy of drugs metabolized by CYP3A should be anticipated during long-term administration of St John's wort.

The contribution of intestinal and hepatic CYP3A to the interaction between midazolam and clarithromycin.

OBJECTIVE: To assess the relative contribution of intestinal and hepatic CYP3A inhibition to the interaction between the prototypic CYP3A substrates midazolam and clarithromycin. METHODS: On day 1, 16 volunteers (eight men and eight women; age range, 20 to 40 years; weight range, 45 to 100 kg) received simultaneous doses of midazolam intravenously (0.05 mg/kg over 30 minutes) and orally (4 mg of a stable isotope, 15N3-midazolam). Starting on day 2, 500 mg clarithromycin was administered orally twice daily for 7 days. On day 8, intravenous and oral doses of midazolam were administered 2 hours after the final clarithromycin dose. Blood and urine samples were assayed for midazolam, 15N3-midazolam, and metabolites by gas chromatography-mass spectrometry. RESULTS: There was no significant (p > 0.05) difference in the urinary excretion of 1'-hydroxymidazolam after intravenous and oral dosing on day 1 or day 8, indicating that the oral dose was completely absorbed into the gut wall. The oral clearance of midazolam was found to be significantly greater in female subjects (1.9 +/- 1.0 versus 1.0 +/- 0.3 L/hr/kg; p < 0.05) than in male subjects but not systemic clearance (0.35 +/- 0.1 versus 0.44 +/- 0.1 L/hr/kg). For women not receiving oral contraceptives (n = 6) a significant gender-related difference was observed for systemic and oral clearance and for area under the curve and elimination half-life after oral administration. A significant (p < 0.05) reduction in the systemic clearance of midazolam from 28 +/- 9 L/hr to 10 +/- 3 L/hr occurred after clarithromycin administration. Oral midazolam availability was significantly increased from 0.31 +/- 0.1 to 0.75 +/- 0.2 after clarithromycin dosing. Likewise, intestinal and oral availability were significantly increased from 0.42 +/- 0.2 to 0.83 +/- 0.2 and from 0.74 +/- 0.1 to 0.90 +/- 0.04, respectively. A significant correlation was observed between intestinal and oral availability (n = 32, r = 0.98, p < 0.05). After clarithromycin administration, a significant correlation was observed between the initial hepatic or intestinal availability and the relative increase in hepatic or intestinal availability, respectively. Female subjects exhibited a greater extent of interaction after oral and intravenous dosing than male subjects (p < 0.05). CONCLUSION: These data indicate that in addition to the liver, the intestine is a major site of the interaction between oral midazolam and clarithromycin. Interindividual variability in first-pass extraction of high-affinity CYP3A substrates such as midazolam is primarily a function of intestinal enzyme activity.

Regioselective and stereoselective metabolism of ibuprofen by human cytochrome P450 2C.

The cytochrome P450s responsible for the regio- and stereoselectivity in the 2- and 3-hydroxylation of the chiral non-steroidal antiinflammatory drug ibuprofen were characterized in human liver microsomes. The rates of formation of both the 2- and 3-hydroxy metabolites exhibited monophasic (N = 2; N is the number of microsomal preparations) and biphasic (N = 2) substrate concentration dependence for both enantiomers of ibuprofen. The high affinity enzyme class parameters for S-ibuprofen (N = 4) were: 2-hydroxylation, Vmax = 566 +/- 213 pmol/min/mg, Km = 38 +/- 13 microM; 3-hydroxylation, Vmax = 892 +/- 630 pmol/min/mg, Km = 21 +/- 6 microM. For R-ibuprofen, the corresponding parameters were: 2-hydroxylation, Vmax = 510 +/- 117 pmol/min/mg, Km = 47 +/- 20 microM; 3-hydroxylation, Vmax = 593 +/- 113 pmol/min/mg, Km = 29 +/- 8 microM. cDNA-expressed CYP2C9 (Arg 144 and Cys 144) favored S-2- and S-3-hydroxyibuprofen formation, but CYP2C8 favored R-2-hydroxyibuprofen formation. Sulfaphenazole, retinol, and arachidonic acid competitively inhibited the rate of formation of all hydroxyibuprofens; Ki values (N = 3) for sulfaphenazole on the 2- and 3-hydroxylations of S-ibuprofen were 0.12 +/- 0.05 and 0.07 +/- 0.04 and of R-ibuprofen were 0.11 +/- 0.07 and 0.06 +/- 0.03 microM, respectively. Sulfaphenazole also competitively inhibited ibuprofen hydroxylation by cDNA-expressed CYP2C9 (Arg 144 and Cys 144) with Ki values in the range of 0.05 to 0.18 microM and CYP2C8 in the range of 0.36 to 0.55 microM. In a bank of 14 human liver microsome samples, significant correlations (r = 0.72 to 0.90; P < 0.01) were observed between the rates of formation of all four hydroxyibuprofens, and for each hydroxyibuprofen and prototypical CYP2C8/9 biotransformations. The regio- and stereoselectivities observed in vitro were consistent with those noted in vivo. The relative levels of both CYP2C8 and CYP2C9 and the expression of the corresponding variants may influence the disposition of ibuprofen in vivo.

Stereoselective sulfoxidation of sulindac sulfide by flavin-containing monooxygenases. Comparison of human liver and kidney microsomes and mammalian enzymes.

The stereoselective sulfoxidation of the pharmacologically active metabolite of sulindac, sulindac sulfide, was characterized in human liver, kidney, and cDNA-expressed enzymes. Kinetic parameter estimates (pH = 7.4) for sulindac sulfoxide formation in human liver microsomes (N = 4) for R- and S-sulindac sulfoxide were V(max) = 1.5 +/- 0.50 nmol/min/mg, K(m) = 15 +/- 5.1 microM; and V(max) = 1.1 +/- 0.36 nmol/min/mg, K(m) = 16 +/- 6.1 microM, respectively. Kidney microsomes (N = 3) produced parameter estimates (pH = 7.4) of V(max) = 0.9 +/- 0.29 nmol/min/mg, K(m) = 15 +/- 2.9 microM; V(max) = 0.5 +/- 0.21 nmol/min/mg, K(m) = 22 +/- 1.9 microM for R- and S-sulindac sulfoxide, respectively. In human liver and flavin-containing monooxygenase 3 (FMO3) the V(max) for R-sulindac sulfoxide increased 60-70% at pH = 8.5, but for S-sulindac sulfoxide was unchanged. In fourteen liver microsomal preparations, significant correlations occurred between R-sulindac sulfoxide formation and either immunoquantified FMO or nicotine N-oxidation (r = 0.88 and 0.83; P < 0.01). The R- and S-sulindac sulfoxide formation rate also correlated significantly (r = 0.85 and 0.75; P < 0.01) with immunoquantified FMO in thirteen kidney microsomal samples. Mild heat deactivation of microsomes reduced activity by 30-60%, and a loss in stereoselectivity was observed. Methimazole was a potent and nonstereoselective inhibitor of sulfoxidation in liver and kidney microsomes. n-Octylamine and membrane solubilization with lubrol were potent and selective inhibitors of S-sulindac sulfoxide formation. cDNA-expressed CYPs failed to appreciably sulfoxidate sulindac sulfide, and CYP inhibitors were ineffective in suppressing catalytic activity. Purified mini-pig liver FMO1, rabbit lung FMO2, and human cDNA-expressed FMO3 efficiently oxidized sulindac sulfide with a high degree of stereoselectivity towards the R-isomer, but FMO5 lacked catalytic activity. The biotransformation of the sulfide to the sulfoxide is catalyzed predominately by FMOs and may prove to be useful in characterizing FMO activity.

In vitro evaluation methods for Clostridium botulinum type C and D vaccines.

Reagents were prepared for use in ELISAs to determine the concentration of the antigenic components of Clostridium botulinum type C and D. The results obtained were compared with the L+dose assay and a good correlation was found between the two assays for measurement of the C and D neurotoxin concentration. These ELISAs were also used to determine the concentration of the neurotoxins in toxoid form. The relationship between the C neurotoxin dose, in toxoid form, and the immune response in guinea pigs could be deduced from the data obtained. The relationship for the D neurotoxin was not that clear, as the same concentration of the antigen resulted in variable potency values. However, these ELISAs can be used to formulate the concentration of the C and D components in the final bivalent vaccine. Replacement of the preliminary potency assay on the monovalent components after production with the in vitro assays will shorten the total production time of the vaccine by about 60 days. The economical and ethical implications are the reduction in the use of animals to evaluate the vaccine.

The Influence of Misoprostol on the Adverse Renal Effects and Stereospecific Pharmacokinetics of Ibuprofen in Chronic Renal Insufficiency.

The use of nonsteroidal anti-inflammatory drugs in patients with chronic renal insufficiency (CRI) may be complicated by renal functional abnormalities due to the inhibition of renal prostaglandins. We tested the hypothesis that administration of the oral PGE1 analog, misoprostol, could attenuate the adverse renal effects of ibuprofen in patients with CRI. Because the metabolism of misoprostol and the stereoinversion of R- to S-ibuprofen involve the same metabolic pathway, the stereospecific pharmacokinetics of ibuprofen were also evaluated. In a randomized, crossover trial of six stable CRI patients (Clcr 25--67 ml min(minus sign1)), in sodium balance on a 150 mEq Na(+) per day metabolic diet, we compared the effects of ibuprofen 600 mg qid with and without misoprostol 200 &mgr;g qid upon Clcr, Clinulin, Clpah, Na(+), and K(+) excretion during 4-h clearance studies. We also assessed stereospecific ibuprofen kinetics following single dose (acute) and after 7 days on drug(s) (chronic). Daily weights, supine blood pressures, electrolytes, osmolality, BUN, creatinine and 24-h urine collections for Clcr and Na(+) and K(+) excretions were obtained during chronic dosing. Supine and upright plasma renin activities were obtained prior to dosing and during chronic dosing for both treatment limbs. Ibuprofen alone resulted in an approximately 20% transient reduction in GFR, occurring 2--2.5 h following dosing in both the acute and chronic clearance studies. This was not affected by misoprostol. There was a greater degree of stimulation of PRA with the upright posture with misoprostol plus ibuprofen than with ibuprofen alone. There was a significant weight gain in both study limbs, but no effect of misoprostol (1.2 plus minus 0.2 kg ibuprofen alone and 1.0 plus minus 0.2 kg ibuprofen plus misoprostol, p = 0.13). Otherwise no clinically significant alteration in renal function occurred in either treatment limb. The presence of misoprostol did not alter the stereospecific pharmacokinetics of ibuprofen. We conclude that misoprostol does not significantly alter the renal effects of ibuprofen in patients with mild to moderate CRI.

The effects of midodrine on the natriuretic response to furosemide in cirrhotics with ascites.

BACKGROUND: Resistance to loop diuretics is common in patients with ascites. Diminished glomerular filtration rate (GFR) is thought to mediate resistance to loop diuretics. Midodrine, a commonly used alpha-1 agonist, has been shown to improve GFR in non-azotemic patients with cirrhosis. AIM: To conduct a randomized, double-blind, placebo-controlled, cross-over study to test the hypothesis that midodrine significantly increases natriuretic response of IV furosemide in non-azotemic cirrhotics with ascites. METHODS: All subjects participated in both phases, which were (i) furosemide IV infusion + oral midodrine 15 mg administered 30 min before furosemide (ii) furosemide IV infusion + oral placebo administered 30 min before furosemide. Primary outcomes were 6-h urine sodium excretion and 6-h total urine volume. RESULTS: A total of 15 patients (men: 8; age: 52.7 ± 7.6 years; serum creatinine: 1.06 ± 0.2 mg/dL) were studied. Total 6-h urine sodium excretion was 109 ± 42 mmol in the furosemide + midodrine treatment phase and was not significantly different from that in the furosemide + placebo treatment phase (126 ± 69 mmol, P = 0.6). Similarly, mean 6-h total urine volume was not significantly different between two groups (1770 ± 262 mL vs. 1962 ± 170 mL, P = 0.25). CONCLUSIONS: Oral midodrine does not increase the natriuretic response to furosemide in non-azotemic cirrhotic patients with ascites. Orally administered midodrine does not increase natriuretic response to furosemide in non-azotemic cirrhotic patients with ascites.

Cytochrome P450 3A5 genotype is associated with verapamil response in healthy subjects.

We hypothesized that CYP3A5 genotype contributes to the interindividual variability in verapamil response. Healthy subjects (n=26) with predetermined CYP3A5 genotypes were categorized as expressers (at least one CYP3A5(*)1 allele) and nonexpressers (subjects without a CYP3A5(*)1 allele). Verapamil pharmacokinetics and pharmacodynamics were determined after 7 days of dosing with 240 mg daily. There was a significantly higher oral clearance of R-verapamil (165.1+/-86.4 versus 91.2+/-36.5 l/h; P=0.009) and S-verapamil (919.4+/-517.4 versus 460.2+/-239.7 l/h; P=0.01) in CYP3A5 expressers compared to nonexpressers. Consequently, CYP3A5 expressers had significantly less PR-interval prolongation (19.5+/-12.3 versus 44.0+/-19.4 ms; P=0.0004), and had higher diastolic blood pressure (69.2+/-7.5 versus 61.6+/-5.1 mm Hg; P=0.036) than CYP3A5 nonexpressers after 7 days dosing with verapamil. CYP3A5 expressers display a greater steady-state oral clearance of verapamil and may therefore experience diminished pharmacological effect of verapamil due to a greater steady state oral clearance.

Diltiazem inhibits human intestinal cytochrome P450 3A (CYP3A) activity in vivo without altering the expression of intestinal mRNA or protein.

AIMS: To determine the effect of diltiazem on intestinal CYP3A activity and protein and mRNA expression in vivo in healthy subjects. METHODS: Intestinal biopsies were obtained from ten healthy controls and from ten healthy subjects after receiving diltiazem 120 mg bid for 7 days. Intestinal CYP3A activity, CYP3A4 protein and mRNA concentrations were quantified in both groups. Intestinal CYP3A activity was determined by incubation of small bowel homogenate with midazolam (25 microM) and NADPH for 5 min and the rate of formation of 1'-hydroxymidazolam was quantified. RESULTS: All subjects in the treatment group had detectable diltiazem concentration in the serum. While there was no significant difference in CYP3A4 protein and mRNA expression between the control and treatment groups, the formation of 1'-hydroxymidazolam (446 pmol min(-1) mg(-1) 6 (control) vs. 170 (CI 112, 228) pmol min(-1) mg(-1) 95% confidence interval (CI 269, 623) (diltiazem group)) was significantly reduced (P < 0.05). CONCLUSION: Diltiazem decreased small bowel CYP3A activity by 62% as a result of irreversible inhibition with no corresponding change in intestinal CYP3A4 mRNA or protein concentrations.

Quantification of dextromethorphan and metabolites: a dual phenotypic marker for cytochrome P450 3A4/5 and 2D6 activity.

A sensitive and selective liquid chromatographic procedure using fluorimetric detection was developed to quantify dextromethorphan (DTM), 3-methoxymorphinan (3MM), dextrorphan (DT), 3-hydroxymorphinan (3OH) and two internal standards, codeine (COD) and ethylmorphine (ETM), in urine. Precision and accuracy of the assay were determined over a concentration range of 5-3200 ng/ml urine for DTM, 5-400 ng/ml urine for 3MM, 400-40 000 ng/ml urine for DT and 200-16 000 ng/ml urine for 3OH, by assaying freshly prepared calibration standards and replicates of six quality control (QC) samples on separate days. All of the inter-day and intra-day coefficients of variation (C.V.s) were less than 20% except for a low QC for 3MM. The inter-day and intra-day accuracies were less than 20% for the low QCs, less than 15% for the medium QCs and less than 12% for the high QCs, for all compounds. The limit of quantification (LOQ) was 2 ng/ml urine for DTM and 3MM, 250 ng/ml urine for DT, and 100 ng/ml urine for 3OH. Absolute recovery was 76% for DTM, 74% for 3MM, 77% for DT, 46% for 3OH, 73% for ETM, and 57% for COD. The frequency distribution of the CYP2D6 metabolic ratio (DTM/DT) illustrated a bimodal distribution whereas, the CYP3A metabolic ratio (DTM/3MM) exhibited a unimodal distribution in overnight urine samples of volunteers who ingested 30 mg dextromethorphan hydrobromide. The CYP2D6 metabolic ratio significantly correlated with 3MM/3OH (r=0.82) and DTM/3OH (r=0.95) but did not correlate with the CYP3A metabolic ratio (r=0.27).

Diltiazem inhibition of cytochrome P-450 3A activity is due to metabolite intermediate complex formation.

Diltiazem (DTZ) N-demethylation occurs by cytochrome P-450 (CYP) 3A based on the following observations: 1) a single enzyme Michaelis-Menten model of metabolite formation, 2) high correlations of DTZ N-demethylation activity to other CYP3A activities, 3) inhibition of DTZ N-demethylation activity by triacetyloleandomycin, and 4) DTZ N-demethylation activity by expressed CYP3A enzymes only. The mean K(m)s for DTZ N-demethylation in human liver microsomes and expressed CYP3A4(+b(5)) were 53 and 16 microM, respectively. A 30-min preincubation of DTZ in expressed CYPs inhibited CYP3A4(+b(5)) by 100%, of which 55% was due to formation of a metabolite intermediate complex (MIC), which is an inactive form of CYP. MIC was observed in human liver microsomes and cDNA-expressed CYP3A only. In experiments to assess simultaneous MIC formation and loss of CYP3A activity, DTZ caused greater than 80% inhibition of midazolam hydroxylation after a 60-min preincubation in human liver microsomes. The rate constants for MIC formation and loss of midazolam hydroxylation activity were equivalent for the line of best fit for both data sets, which illustrates that MIC formation causes the inhibition of CYP3A activity. The mechanistic inhibition was characterized in expressed CYP3A4(+b(5)), which exhibited a concentration-dependent formation of MIC by DTZ (1-100 microM) with an estimated k(inact) of 0.17 min(-1) and K(I) of 2.2 microM. The partition ratio for expressed CYP3A4(+b(5)) was substrate concentration dependent and varied from 13 to 86. This study showed that DTZ inhibition of CYP3A substrate metabolism occurs primarily by MIC formation.

Biotransformation of alprazolam by members of the human cytochrome P4503A subfamily.

1. To aid in the prediction of drug interactions with alprazolam, the human CYP involved in the 1'- and 4-hydroxylation of alprazolam were characterized using human liver microsomes, expressed enzymes and selective chemical inhibitors. 2. The formation of 4-hydroxyalprazolam and 1'-hydroxyalprazolam at an alprazolam concentration of 62.5 microM were reduced by the prototypic CYP3A inhibitor, troleandomycin (50 microM), by 97 and 9900 respectively. Only microsomes from B-lymphoblastoid cells expressing CYP3A4 were capable of catalysing the 1'- and 4-hydroxylation of alprazolam. 3. The formation rates of 1'-hydroxyalprazolam and 4-hydroxyalprazolam at an alprazolam concentration of 1 mM were significantly correlated (n = 19, r = 0.95, p<0.01) indicating that the same enzyme(s) mediated these biotransformations. A significant (p<0.01) correlation was observed between alprazolam 4- and 1'-hydroxylase activity and CYP3A-mediated midazolam 4-hydroxylase, midazolam 1'-hydroxylase, dextromethorphan N-demethylase and erythromycin N-demethylase activities. 4. In conclusion, in adult human liver the CYP3A subfamily members are the principal enzymes involved in the 1'- and 4-hydroxylation of alprazolam. Thus, clinically significant drug drug interactions between alprazolam and other CYP3A substrates are to be expected.

Serological cloning of PARIS-1: a new TBC domain-containing, immunogenic tumor antigen from a prostate cancer cell line.

Identifying immunogenic tumor antigens plays a critical role in developing efficient diagnostic and therapeutic strategies for treatment of cancer. Using a recently developed technology, serological identification of antigens by recombinant expression cloning (SEREX), we identified a total of 8 genes whose expression elicited antibody responses in prostate cancer patients. Of the 8 genes, 5 represented known genes in the GenBank database, 2 were previously uncharacterized genes, and 1 showed sequence homology to a mouse gene. The sequence feature and the expression of one of the novel genes, prostate antigen recognized and identified by SEREX (PARIS-1), are determined in this study. The PARIS-1 cDNA is 3257 bp in length and contains a complete open reading frame of 2751 bp encoding for a primary translation product of 917 amino acids. Using Northern blot hybridization assay, we detected a single species of approximately 3.3 kb PARIS-1 mRNA that is differentially expressed in prostate normal and cancer cells. Western blot analysis confirmed the expression of the PARIS-1 protein in these cells. Structure analysis revealed that PARIS-1 protein contains a TBC domain that is conserved in the family of cell cycle-regulatory and Rab GTPase-activating proteins (Rab-GAP). Thus, the PARIS-1 protein may play a role in regulation of cell differentiation and growth or represent a new member of the Rab-GAP family.

Identification of the human cytochromes P450 responsible for the in vitro formation of the major oxidative metabolites of the antipsychotic agent olanzapine.

The formation kinetics of 2-hydroxymethyl olanzapine (2-OH olanzapine), 4'-N-oxide olanzapine (N-O olanzapine) and 4'-N-desmethyl olanzapine (NdM olanzapine) were analyzed in vitro. Biphasic kinetics were observed for formation of 2-OH and NdM olanzapine. The high-affinity enzyme responsible for 2-OH olanzapine formation by two human liver samples exhibited an intrinsic clearance (CLint) of 0.2 microliter/min/mg. NdM olanzapine formation by two human liver samples exhibited a CLint of 1.0 microliter/min/mg for the high affinity enzyme. The formation of N-O olanzapine was linear up to 300 microM olanzapine, yielding a CLint of 0.32 to 1.70 microliters/min/mg. The formation of 7-hydroxy olanzapine (7-OH olanzapine) exhibited an apparent Km of 24.2 microM. The rates of 2-OH olanzapine formation correlated with CYP2D6 levels and activity, and it was formed to the greatest extent by cDNA-expressed CYP2D6. N-O olanzapine formation correlated with human liver flavin-containing monooxygenase (FMO3) levels and activity. NdM olanzapine and 7-OH olanzapine formation correlated with CYP1A2 catalytic activities and they were formed to the greatest extent by expressed CYP1A2. These results suggest that CYP1A2 catalyzes NdM olanzapine and 7-OH olanzapine formation, CYP2D6 catalyzes 2-OH olanzapine formation and FMO3 catalyzes N-O olanzapine formation.