Prognostic role of high TET1 expression in patients with solid tumors: A meta-analysis

BACKGROUND

Recently, increased expression of TET1 has been shown to inhibit tumor development in many studies. Therefore, a meta-analysis was conducted to assess the prognostic role of TET1 in solid tumors.

METHODS

PubMed, Embase, and the Web of Science (last updated on June 13, 2019) were searched and 16 eligible studies involving 3100 patients were eventually taken forward into the meta-analysis.

RESULTS

Pooled results indicated that higher TET1 expression in cancer tissues was associated with improved overall survival (OS) [hazard ratio (HR) = 0.736, 95% confidence interval (95% CI) = 0.542-0.998, P = .049]. In the subgroup analysis, higher TET1 expression in respiratory tumors (HR = 0.778, 95% CI = 0.639-0.946, P = .012) and breast cancer in Asian patients (HR = 0.326, 95% CI = 0.199-0.533, P < .001) were significantly associated with better OS. In addition, the association between high TET1 expression and prolonged OS was also statistically significant in the following subgroups; data source from samples (HR = 0.561, 95% CI = 0.384-0.819, P = .003), reported in text (HR = 0.539, 95% CI = 0.312-0.931, P = .027), TET1 protein (HR = 0.635, 95% CI = 0.409-0.984, P = .042), Asians (HR = 0.563, 95% CI = 0.376-0.844, P = .005).

CONCLUSION

This meta-analysis displays that high expression levels of TET1 in tissues is significantly associated with better survival in patients with solid tumors. This finding can be used as evidence to the tone that TET1 may be a useful target for the treatment of patients with solid tumors in the future.

Variant analysis of HPD genes from two families showing elevated tyrosine upon newborn screening by tandem mass spectrometry (MS/MS)

Background Alterations in the structure and activity of 4-hydroxyphenylpyruvate dioxygenase (HPD) are causally related to two different metabolic disorders: recessively inherited tyrosinemia type III and dominantly inherited hawkinsinuria. The aim of this study was to provide a new perspective for the clinical understanding of the pathogenesis of tyrosinemia type III or hawkinsinuria. Case presentation A full-term newborn baby born after a safe pregnancy and childbirth with a birth weight of 3200 g and another full-term baby born after a safe pregnancy and childbirth with a birth weight of 2800 g are reported and analysed. DNA extraction, next-generation sequencing, bioinformatics analysis, Sanger sequencing and biochemical analysis were performed. One patient with a heterozygous HPD gene (NM_002150.2) c.460G > A mutation and one patient with a heterozygous HPD gene (NM_002150.2) c.248delG mutation showing elevated tyrosine levels upon newborn screening by tandem mass spectrometry (MS/MS) are reported. Conclusions The HPD gene may not be a strictly autosomal recessive pathogenic gene, which provides a new perspective for the clinical understanding of the pathogenesis of tyrosinemia type III or hawkinsinuria.

DNA Hydroxymethylation Levels Are Altered in Blood Cells From Down Syndrome Persons Enrolled in the MARK-AGE Project

Down syndrome (DS) is caused by the presence of part or an entire extra copy of chromosome 21, a phenomenon that can cause a wide spectrum of clinically defined phenotypes of the disease. Most of the clinical signs of DS are typical of the aging process including dysregulation of immune system. Beyond the causative genetic defect, DS persons display epigenetic alterations, particularly aberrant DNA methylation patterns that can contribute to the heterogeneity of the disease. In the present work, we investigated the levels of 5-hydroxymethylcytosine and of the Ten-eleven translocation dioxygenase enzymes, which are involved in DNA demethylation processes and are often deregulated in pathological conditions as well as in aging. Analyses were carried out on peripheral blood mononuclear cells of DS volunteers enrolled in the context of the MARK-AGE study, a large-scale cross-sectional population study with subjects representing the general population in eight European countries. We observed a decrease in 5-hydroxymethylcytosine, TET1, and other components of the DNA methylation/demethylation machinery in DS subjects, indicating that aberrant DNA methylation patterns in DS, which may have consequences on the transcriptional status of immune cells, may be due to a global disturbance of methylation control in DS.

Reduced mRNA and Protein Expression Levels of Tet Methylcytosine Dioxygenase 3 in Endothelial Progenitor Cells of Patients of Type 2 Diabetes With Peripheral Artery Disease

Endothelial progenitor cells (EPCs) with immunological properties repair microvasculature to prevent the complications in patients with diabetes. Epigenetic changes such as DNA methylation alter the functions of cells. Tet methylcytosine dioxygenases (TETs) are enzymes responsible for the demethylation of cytosine on genomic DNA in cells. We hypothesized that EPCs of diabetic patients with peripheral artery disease (D-PAD) might have altered expression levels of TETs. Subjects who were non-diabetic (ND, n = 22), with diabetes only (D, n = 29) and with D-PAD (n = 22) were recruited for the collection of EPCs, which were isolated and subjected to analysis. The mRNA and protein expression levels of TET1, TET2, and TET3 were determined using real-time PCR and immunoblot, respectively. The TET1 mRNA expression level in ND group was lower than that in the D and D-PAD groups. The TET3 mRNA level in the ND group was higher than that in the D group, which was higher than that in the D-PAD group. The TET1 protein level in the D-PAD group, but not the D group, was higher than that in the ND group. The TET2 protein level in the D-PAD group, but not the D group, was lower than that in the ND group. The TET3 protein level in the ND group was higher than that in the D group, which was higher than that in the D-PAD group, which is the lowest among the three groups. The changes of TETs protein levels were due to the alterations of their transcripts. These probably lead to epigenetic changes, which may be responsible for the reductions of EPCs numbers and functions in patients with the D-PAD. The expression pattern of TET3 mRNA and TET3 protein in EPCs may be a biomarker of angiopathy in diabetic patients.

A rare case of sterol-C4-methyl oxidase deficiency in a young Italian male: Biochemical and molecular characterization

Inborn defects of cholesterol biosynthesis are metabolic disorders presenting with multi-organ and tissue anomalies. An autosomal recessive defect involving the demethylating enzyme C4-methyl sterol (SC4MOL) has been reported in only 4 patients so far. In infancy, all patients were affected by microcephaly, bilateral congenital cataracts, growth delay, psoriasiform dermatitis, immune dysfunction, and intellectual disability. Herein, we describe a new case of SC4MOL deficiency in which a 19-year-old Italian male was affected by bilateral congenital cataracts, growth delay and learning disabilities, behavioral disorders and small stature, but not microcephaly. Our patient had abundant scalp dandruff, without other skin manifestations. Analysis of the blood sterol profile showed accumulation of C4-monomethyl and C4-dimethyl sterols suggesting a deficiency of the SC4MOL enzyme. Sequencing of the MSMO1 gene (also known as the "SC4MOL" gene) confirmed mutations in each allele (c.731A>G, p.Y244C, which is already known, and c.605G>A, p.G202E, which is a novel variant). His father carried c.731A>G mutation, whereas his mother carried c.605G>A. Thus, the combination of multiple skills and methodologies, in particular, blood sterol profiling and genetic analysis, led to the diagnosis of a new case of a very rare defect of cholesterol biosynthesis. Consequently, we suggest that these two analyses should be performed as soon as possible in all undiagnosed patients affected by bilateral cataracts and developmental delay.

The Effect of Selenium Supplementation on Glucose Homeostasis and the Expression of Genes Related to Glucose Metabolism

The aim of the study was to evaluate the effect of selenium supplementation on the expression of genes associated with glucose metabolism in humans, in order to explain the unclear relationship between selenium and the risk of diabetes. For gene expression analysis we used archival samples of cDNA from 76 non-diabetic subjects supplemented with selenium in the previous study. The supplementation period was six weeks and the daily dose of selenium was 200 µg (as selenium yeast). Blood for mRNA isolation was collected at four time points: before supplementation, after two and four weeks of supplementation, and after four weeks of washout. The analysis included 15 genes encoding selected proteins involved in insulin signaling and glucose metabolism. In addition, HbA1c and fasting plasma glucose were measured at three and four time points, respectively. Selenium supplementation was associated with a significantly decreased level of HbA1c but not fasting plasma glucose (FPG) and significant down-regulation of seven genes: INSR, ADIPOR1, LDHA, PDHA, PDHB, MYC, and HIF1AN. These results suggest that selenium may affect glycemic control at different levels of regulation, linked to insulin signaling, glycolysis, and pyruvate metabolism. Further research is needed to investigate mechanisms of such transcriptional regulation and its potential implication in direct metabolic effects.

[Prognostic significance of indices of endogenous intoxication and of a monooxygenase system on the stages of surgical treatment in patients, suffering abdominal sepsis]

Some indices of endogenous intoxication and lymphocytic monooxygenase activity in the blood of patients, suffering abdominal sepsis (AS), were investigated, their prognostic significance was determined. In 28 patients the signs of AS were revealed, in 14 of a severe sepsis, in 11--of a septic shock. For peritoneal AS there were operated 37 patients, and for a pancreatogenic one--15. Relaparotomy "on demand" was performed in 12, and "the programmed" one--in 15 patients. A 30-days lethality in AS was 10.7%, in severe shock--28.6%, and in a septic one--63.6%. While AS occurrence a rising of metabolic activity of the monooxygenase system were registered in certain terms, and significant inhibition of this index--while severe state of the patients in a refractory shock occurrence. A safety correlational connections of indices in the blood and the lymphocytic monooxygenase system activity were determined in patients, who died.

[Dynamics of antipirin test at patients with alcoholic liver disease on the background of metadoksin drug receiving]

AIM

To study the effect of the drug metadoxin on drug-metabolizing liver function in patients with liver lesions alcoholic etiology (ALD).

MATERIALS AND METHODS

36 patients with ALD, of which 16 patients were diagnosed with hepatitis, while 20 - with the liver cirrhosis. All the patients underwent biochemical blood analysis and the study of drug-metabolizing liver function according to the pharmacokinetics of antipyrine in saliva before and after treatment with metadoxin. Metadoxin was administered at a dose of 500 mg once a day for 28 days. Concentrations of antipyrine in saliva samples were determined by HPLC. RESULTS. It was shown that of 36 patients examined in the 28-patients with ALD (group 2) there was a significant decrease in activity of liver enzymes according to the test with antipyrine (T1/2 = 28.7 +/- 3.4, CL = 17,9 +/- 5.2; p < 0,01 vs normal), whereas in 8 patients (group 1) was noted the typical for alcohol inductive influence on the activity of liver monooxygenases (T1/2 = 7.8 +/- 1.5, CL = 39.1 +/- 6.8; p < 0,05 vs normal). As a result of the 28-day therapy with metadoxin was a normalization of the pharmacokinetic parameters of AP in Gr. 1 (12.6 +/- 1.8; p < 0.05; NS vs normal) and a significant improvement of it in patients of Gr. 2 (17.9 +/- 5.2, vs N, p <0.05). Biochemical markers of ALD (AST/ALT, GGT, ALP) also demonstrated a positive dynamics in patients of both study groups. Correlation analysis of changes in CL and GGT (r1) and changes in AST/ALT and T1/2 (r2) showed a fairly high degree of correlation between these parameters (r1 = 0.58, r2 = 0.65).

CONCLUSION

The results showed marked improvement of drug-metabolizing liver function according to the test with antipyrine in patients with ALD after treatment with metadoxin.

CYP2A6 genotype, phenotype, and the use of nicotine metabolites as biomarkers during ad libitum smoking

CYP2A6 inactivates nicotine to cotinine and cotinine to 3-hydroxycotinine. We investigated which of plasma nicotine and metabolites were most related to CYP2A6 genotype and smoking levels. We assessed demographic and smoking histories in 152 Caucasian ad libitum smokers, measured breath carbon monoxide (CO) levels, and determined plasma nicotine, cotinine, and 3-hydroxycotinine by high-performance liquid chromatography and CYP2A6 genotypes by PCR. Cigarettes per day was most closely related to CO (r = 0.60, P < 0.001) followed by plasma cotinine (r = 0.53, P < 0.001), whereas plasma cotinine was most strongly correlated with CO levels (r = 0.74, P < 0.001), confirming that cotinine is a good indicator of smoking levels; this was not limited by CYP2A6 variants. 3-Hydroxycotinine/cotinine is reported to be a good marker of CYP2A6 activity, and we found that the 3-hydroxycotinine/(cotinine + nicotine) ratio was most correlated with CYP2A6 genotype (r = 0.38, P < 0.001). Inclusion of the CYP2A6*12A allele strengthened the correlation (r = 0.46, P < 0.001), suggesting that the identification of novel alleles will continue to improve this relationship. Nicotine metabolism is slower in smokers, and we have shown that CYP2A6 is reduced by nicotine treatment in monkeys. Here, we found that plasma nicotine levels were inversely correlated with CYP2A6 activity (3-hydroxycotinine/cotinine, r = -0.41, P < 0.001) among those without CYP2A6 variants, suggesting a reduction in metabolism with higher nicotine levels. Together, these findings (a) confirm the use of plasma cotinine and CO as indicators of Caucasians' smoking levels, and that this is not limited by CYP2A6 genetic variation; (b) indicate that 3-hydroxycotinine/cotinine and 3-hydroxycotinine/(cotinine + nicotine) are moderately good indicators of the CYP2A6 genotype; and (c) support that nicotine exposure may reduce its own metabolism.

Fenugreek (Trigonella foenum graecum) seed polyphenols protect liver from alcohol toxicity: a role on hepatic detoxification system and apoptosis

The present study investigates the hepatoprotective effect of fenugreek seed polyphenolic extract (FPEt) against ethanol-induced hepatic injury and apoptosis in rats. Chronic ethanol administration (6 g/kg/day x 60 days) caused liver damage that was manifested by the elevation of markers of liver dysfunction--aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), bilirubin and gamma-glutamyl transferase (GGT) in plasma and reduction in liver glycogen. The effects on alcohol metabolizing enzymes such as alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) were studied and found to be altered in the alcohol-treated group. Ethanol administration resulted in adaptive induction of the activities of cytochrome p450 (cyt-p-450) and cytochrome-b5 (cyt-b5) and reduction in cytochrome-c-reductase (cyt-c-red) and glutathione-S-tranferase (GST), a phase II enzyme. Further, ethanol reduced the viability of isolated hepatocytes (ex vivo) as assessed by the trypan blue exclusion test and increased hepatocyte apoptosis as assessed by propidium iodide staining (PI). Treatment with FPEt restored the levels of markers of liver injury and mitigated the alterations in alcohol metabolizing and detoxification enzymes and the electron transport component cytochrome-c reductase. Increased hepatocyte viability and reduced apoptotic nuclei were observed in FPEt-treated rats. These findings demonstrate that FPEt acts as a protective agent against ethanol-induced abnormalities in the liver. The effects of FPEt are comparable with those of a known hepatoprotective agent, silymarin.

Contribution of CYP2C9 to variability in vitamin K antagonist metabolism

CYP2C9 is the third most important cytochrome P450 (CYP) in terms of number of drugs metabolised. A considerable amount of information on this isoform is now available with respect to its structural biology, the mechanisms by which it can be induced and the existence of a range of variant alleles, which are often functionally significant. CYP2C9 makes a very important contribution to metabolism of vitamin K antagonist anticoagulants, and is the main oxidising enzyme for S-warfarin and S-acenocoumarol as well as contributing to phenprocoumon metabolism. A large number of studies have now shown that CYP2C9 genotype predicts dose requirement for both warfarin and acenocoumarol, with a possible contribution for phenprocoumon. Patients with variant alleles are likely to require a lower dose and may be at risk of overcoagulation and resultant bleeding, especially during the induction phase of therapy. Although CYP2C9 genotype is clearly a predictor of vitamin K antagonist dose requirement, especially in Caucasian populations in whom variant alleles are common, a number of recent studies have shown that age, genotype for the gene encoding the target gene vitamin K epoxide reductase and concomitant drugs are equally important factors in determining dose. There is a need for prospective studies to assess the value of predicting dose requirement on the basis of all these factors, including the CYP2C9 genotype.

Plasma peptidylglycine alpha-amidating monooxygenase (PAM) and ceruloplasmin are affected by age and copper status in rats and mice

In an attempt to identify a sensitive and improved marker of mammalian copper status during neonatal development experiments compared two plasma cuproenzymes, peptidylglycine alpha-amidating monooxygenase (PAM ), an enzyme involved in peptide posttranslational activation, to ceruloplasmin (Cp), a ferroxidase involved in iron mobilization. Dietary Cu deficiency (Cu-) was studied in dams and offspring at postnatal age 3 (P3), P12, and P28. Rodent Cp activity rose during lactation whereas PAM activity fell. Reduction in Cp activity was more severe than reduction in PAM activity in Cu- offspring and dams. Cp activity was greater in rats than mice whereas PAM activity was similar in adults but greater in mouse than rat pups. Both cuproenzymes changed during neonatal development and when dietary copper was limiting. With proper controls, each enzyme can be used to assess copper status.

The pharmacokinetics of escitalopram in patients with hepatic impairment

The effect of hepatic impairment on the pharmacokinetics of escitalopram was determined by means of nonlinear mixed effect modeling, considering both the Child-Pugh classification (and its components) and cytochrome P450 2C19 (CYP2C19) activity. Twenty-four subjects were grouped according to their Child-Pugh score as healthy, with mild hepatic impairment or with moderate hepatic impairment. The subjects were administered a single oral dose of escitalopram 20 mg, and blood was sampled up to 168 hours after dosage. The serum concentration of escitalopram was determined and the pharmacokinetics assessed by nonlinear mixed effect modeling. The CYP2C19 activity was measured from the urinary excretion ratio of S/R-mephenytoin. All subjects tolerated the treatment well, and no serious adverse events were reported. Predicted mean area under the curve from zero to infinity (AUC(inf)) values were 51% and 69% higher for patients with mild and moderate hepatic impairment (Child-Pugh classification), respectively, compared with healthy subjects. The best-fitting model showed an influence of CYP2C19 activity on clearance and body weight on the volume of distribution for escitalopram. CYP2C19 activity is a better predictor of escitalopram clearance than is Child-Pugh classification.

Effect of kynurenine 3-hydroxylase inhibition on the dyskinetic and antiparkinsonian responses to levodopa in Parkinsonian monkeys

Homeostatic interactions between dopamine and glutamate are central to the normal physiology of the basal ganglia. This relationship is altered in Parkinsonism and in levodopa-induced dyskinesias (LID), resulting in an upregulation of corticostriatal glutamatergic function. Kynurenic acid (KYNA), a tryptophan metabolite with antagonist activity at ionotropic glutamate receptors and the capability to inhibit glutamate release presynaptically, might therefore be of therapeutic value in LID. To evaluate this hypothesis, we used a pharmacological tool, the kynurenine 3-hydroxylase inhibitor Ro 61-8048, which raises KYNA levels acutely. Ro 61-8048 was tested in MPTP cynomolgus monkeys with a stable parkinsonian syndrome and reproducible dyskinesias after each dose of levodopa. Serum and CSF concentrations of KYNA and its precursor kynurenine increased dose-dependently after Ro 61-8048 administration, alone or in combination with levodopa. Coadministration of Ro 61-8048 with levodopa produced a moderate but significant reduction in the severity of dyskinesias while maintaining the motor benefit. These results suggest that elevation of KYNA levels through inhibition of kynurenine 3-hydroxylase constitutes a promising novel approach for managing LID in Parkinson's disease.

Pharmacogenetics and herb???drug interactions

OBJECTIVE

Ginkgo biloba was found to exert a significant inductive effect on CYP2C19 activity. This study was designed to investigate the potential herb-drug interaction between G. biloba and omeprazole, a widely used CYP2C19 substrate, in subjects with different CYP2C19 genotypes.

METHODS

Eighteen healthy Chinese subjects previously genotyped for CYP2C19 were selected. All subjects received a single omeprazole 40 mg at baseline and then at the end of a 12-day treatment period with G. biloba (140 mg, bid). Multiple blood samples were collected over 12 h, and 24 h urine was collected post omeprazole dosing. Plasma and urine concentrations of omeprazole and its metabolites, 5-hydroxyomeprazole and omeprazole sulfone, were determined, and their pharmacokinetics calculated non-compartmentally.

RESULTS

Plasma concentrations of omeprazole and omeprazole sulfone were significantly decreased, and 5-hydroxyomeprazole significantly increased following G. biloba administration in comparison to baseline. A significant decrease in the ratio of area under the plasma concentration-time curve (AUC) of omeprazole to 5-hydroxyomeprazole was observed in the homozygous extensive metabolizers, heterozygous extensive metabolizers, and poor metabolizers, respectively. The decrease was greater in PMs than EMs. No significant changes in the AUC ratios of omeprazole to omeprazole sulfone were observed. Renal clearance of 5-hydroxyomeprazole was significantly decreased after G. biloba, but the change was not significantly different among the three genotype groups.

CONCLUSION

Our results show that G biloba can induce omeprazole hydroxylation in a CYP2C19 genotype-dependent manner and concurrently reduce the renal clearance of 5-hydroxyomeprazole. Co-administration of G. biloba with omeprazole or other CYP2C19 substrates may significantly reduce their effect, but further studies are warranted.

St John's wort induces both cytochrome P450 3A4-catalyzed sulfoxidation and 2C19-dependent hydroxylation of omeprazole

OBJECTIVE

St John's wort, an extract of the medicinal plant Hypericum perforatum, is widely used as an herbal antidepressant. Although the ability of St John's wort to induce cytochrome P450 (CYP) 3A4-mediated reaction has been well established, the effect on CYP2C19 is still not determined. Thus the objective of this study was to determine the impact of St John's wort on the pharmacokinetic profiles of omeprazole and its metabolites.

METHODS

Twelve healthy adult men (6 CYP2C19*1/CYP2C19*1, 4 CYP2C19*2/CYP2C19*2 and 2 CYP2C19*2/CYP2C19*3) were enrolled in a 2-phase randomized crossover design. In each phase the volunteers received placebo or a 300-mg St John's wort tablet 3 times daily for 14 days. Then all subjects took a 20-mg omeprazole capsule orally. Blood samples were collected up to 12 hours after omeprazole administration. Omeprazole and its metabolites were quantified by use of HPLC with ultraviolet detection.

RESULTS

Omeprazole and its metabolites all exhibit CYP2C19 genotype-dependent pharmacokinetic profiles. After a 14-day treatment with St John's wort, substantial decreases in plasma concentrations of omeprazole were observed. The peak plasma concentration (C(max)) significantly decreased by 37.5% +/- 13.3% (P =.001) in CYP2C19*2/CYP2C19*2 or *3 and by 49.6% +/- 20.7% (P =.017) in CYP2C19*1/CYP2C19*1; the area under the concentration-time curve extrapolated to infinity [AUC(0- infinity )] decreased by 37.9% +/- 21.3% (P =.014) and 43.9% +/- 23.7% (P =.011) in CYP2C19 mutant and wild genotypes, respectively. Moreover, the C(max) and AUC(0- infinity ) of omeprazole sulfone increased by 160.3% +/- 45.5% (P =.001) and by 136.6% +/- 84.6% (P =.014), 155.5% +/- 58.8% (P =.001), and 158.7% +/- 101.4% (P =.017) in mutant and wild genotypes, respectively. St John's wort increased the C(max) of 5-hydroxyomeprazole by 38.1% +/- 30.5% (P =.028) and the AUC(0- infinity ) by 37.2% +/- 26% (P =.005) in CYP2C19 wild-type subjects, whereas it did not produce any significant alterations to the corresponding pharmacokinetic parameters in subjects with variant genotypes.

CONCLUSION

St John's wort induces both CYP3A4-catalyzed sulfoxidation and CYP2C19-dependent hydroxylation of omeprazole and enormously decreases the plasma concentrations of omeprazole. Clinically relevant interactions with other drugs may occur and must be taken into account when St John's wort is being taken.

Enantioselective Analysis of Citalopram and its Metabolites in Postmortem Blood and Genotyping For CYD2D6 and CYP2C19

Citalopram, a selective serotonin reuptake inhibitor, is one of the most commonly found drugs in Swedish forensic autopsy cases. Citalopram is a racemic drug with 50:50 of the S- and R- enantiomers. Enantioselective analysis of citalopram and its metabolites desmethylcitalopram and didesmethylcitalopram were performed in femoral blood from 53 autopsy cases by a chiral high-performance liquid chromatography (HPLC) method. The mean (+/- standard deviation) S/R ratio for citalopram was 0.67 +/- 0.25 and for desmethylcitalopram, 0.68 +/- 0.20. We found increasing S/R ratios with increasing concentrations of citalopram. We also found that high citalopram S/R ratios were associated with a high parent drug-to-metabolite ratio and may be an indicator of recent intake. Citalopram is metabolized by cytochrome P450 (CYP) 3A4, 2C19, and 2D6. Genotyping for the polymorphic CYP2C19 and CYP2D6 revealed no poor metabolizers regarding CYP2C19 and only 2 (3.8%) poor metabolizers regarding CYP2D6. The presence of drugs metabolized by and/or inhibiting these enzymes in several of the cases suggests that such pharmacokinetic interactions are a more important (practical) problem than metabolic deficiency. Enantioselective analysis of citalopram and its metabolites can provide additional information when interpreting forensic toxicology results and might be a necessity in the future.

Adrenocortical adenoma associated with inadequately treated congenital adrenal hyperplasia

We report a 6 year-old boy with the simple virilizing form of 21-hydroxylase deficiency in whom an adrenal adenoma developed following 5 years of steroid treatment. Extremely high levels of basal serum 17alpha-hydroxyprogesterone as well as an exaggerated response of 17alpha-hydroxyprogesterone to adrenocorticotropic hormone confirmed congenital adrenal hyperplasia at 7 years of age. Initially elevated serum steroid levels were restrained by high dose hydrocortisone therapy, but he chronically tended to take inadequate doses of glucocorticoid. At 12 years of age an adenoma was found in the cortex of the hyperplastic right adrenal gland. The importance of early diagnosis and compliance with medication in the simple virilizing form of 21-hydroxylase deficiency is stressed.

Contributions of CYP2D6, CYP2C9 and CYP2C19 to the biotransformation of E- and Z-doxepin in healthy volunteers

In-vitro data indicated a contribution of cytochrome P450 enzymes 1A2, 3A4, 2C9, 2C19 and 2D6 to biotransformation of doxepin. We studied the effects of genetic polymorphisms in CYP2D6, CYP2C9 and CYP2C19 on E- and Z-doxepin pharmacokinetics in humans. Doxepin kinetics was studied after a single oral dose of 75 mg in healthy volunteers genotyped as extensive (EM), intermediate (IM) and poor (PM) metabolizers of substrates of CYP2D6 and of CYP2C19 and as slow metabolizers with the CYP2C9 genotype *3/*3. E-, Z-doxepin and -desmethyldoxepin were quantified in plasma by HPLC. Data were analyzed by non-parametric pharmacokinetics and statistics and by population pharmacokinetic modeling considering effects of genotype on clearance and bioavailability. Mean E-doxepin clearance (95% confidence interval) was 406 (390-445), 247 (241-271), and 127 (124-139) l h(-1) in EMs, IMs and PMs of CYP2D6. In addition, EMs had about 2-fold lower bioavailability compared with PMs indicating significant contribution of CYP2D6 to E-doxepin first-pass metabolism. E-doxepin oral clearance was also significantly lower in carriers of CYP2C9*3/*3 (238 l h(-1) ). CYP2C19 was involved in Z-doxepin metabolism with 2.5-fold differences in oral clearances (73 l h(-1) in CYP2C19 PMs compared with 191 l h(-1) in EMs). The area under the curve (0-48 h) of the active metabolite -desmethyldoxepin was dependent on CYP2D6 genotype with a median of 5.28, 1.35, and 1.28 nmol l h(-1) in PMs, IMs, and EMs of CYP2D6. The genetically polymorphic enzymes exhibited highly stereoselective effects on doxepin biotransformation in humans. The CYP2D6 polymorphism had a major impact on E-doxepin pharmacokinetics and CYP2D6 PMs might be at an elevated risk for adverse drug effects when treated with common recommended doses.

[Determination of rhein in plasma of rat by HPLC/MS]

A HPLC/MS method has been established for the determination of rhein in rat plasma, using an Alltima C18 column (4.6 x 250 mm, 5 microns) and a mixture of ACN-water (60:40) as the mobile phase, at the flow rate of 0.8 ml/min with the column temperature at 25 degrees C. The results showed that the level of rhein distributed in plasma reached the max value 0.5 h after the oral administration, and maintained a relatively high value from 0.25 h to 1.5 h. The method possessed high selectivity and sensitivity.

Effects of whole deletion of CYP2A6 on nicotine metabolism in humans

We investigated the effects of CYP2A6 genotypes on nicotine metabolism, focused from nicotine to cotinine and its additional 3'-hydroxylating resulted in trans-3'-hydroxycotinine formation. In the subjects genotyped by PCR-RFLP method, one cigarette smoking experiment was performed and urine samples were collected for 24 h. In all subjects who smoked, we detected nicotine, cotinine and trans-3'-hydroxycotinine in urine by GC-MS analysis. In whole deletion of CYP2A6, urinary excretion amounts of cotinine and trans-3'-hydroxycotinine were significantly smaller than those in the wild-type of CYP2A6*1. A lack of CYP2A6 reduces the formation of cotinine and trans-3'-hydroxycotinine, but not entirely reduces the trans-3'-hydroxycotinine formation. Unknown cotinine 3'-hydroxylating activity except CYP2A6 are suspected in humans.

Environmental and genetic determinants of aflatoxin-albumin adducts in the Gambia

Aflatoxins together with chronic hepatitis B virus (HBV) infection contribute to the high incidence of hepatocellular carcinoma in developing countries. An understanding of the mechanism of interaction between these factors would provide a strong rationale for developing effective prevention strategies. In this study in The Gambia we examined the effect of environmental (place of residence and timing of sample collection) and host factors (age, sex, HBV status and interindividual variations in carcinogen metabolising enzymes) in determining blood aflatoxin-albumin adduct levels in 357 individuals of whom 181 were chronic HBV carriers. Samples were analysed for aflatoxin-albumin adducts, HBV status and genotypes of glutathione S-transferase (GST) M1, GSTT1, GSTP1 and epoxide hydrolase (EPXH). Urine samples were analysed for 6beta-hydroxycortisol:cortisol ratio as a marker of cytochrome P450 (CYP) 3A4 activity. Adduct levels were significantly higher in subjects resident in rural [geometric mean adduct level 34.9 pg aflatoxin B1-lysine equivalent (28.5-42.8; 95%CI)/mg albumin] than in periurban areas [22.2 pg (14.9-33.4)/mg] and were approximately twice as high in the dry season [mid-February to March; 83.2 pg (53.3-130.8)/mg] than the wet [July to August; 34.9 pg (28.5-42.8)/mg]. In contrast, HBV status, CYP3A4 phenotype, GSTT1, GSTP1 and EPXH genotypes were not associated with aflatoxin-albumin adduct level. However, mean adduct levels were significantly higher in non-HBV infected subjects with GSTM1 null genotype. The main factors which affect aflatoxin-albumin adduct levels in this population are environmental, notably place of residence and timing of sample collection. This study further emphasises the priority to reduce aflatoxin exposure in these communities by primary prevention measures.

Environmental and genetic determinants of aflatoxin-albumin adducts in the Gambia

Aflatoxins together with chronic hepatitis B virus (HBV) infection contribute to the high incidence of hepatocellular carcinoma in developing countries. An understanding of the mechanism of interaction between these factors would provide a strong rationale for developing effective prevention strategies. In this study in The Gambia we examined the effect of environmental (place of residence and timing of sample collection) and host factors (age, sex, HBV status and interindividual variations in carcinogen metabolising enzymes) in determining blood aflatoxin-albumin adduct levels in 357 individuals of whom 181 were chronic HBV carriers. Samples were analysed for aflatoxin-albumin adducts, HBV status and genotypes of glutathione S-transferase (GST) M1, GSTT1, GSTP1 and epoxide hydrolase (EPXH). Urine samples were analysed for 6beta-hydroxycortisol:cortisol ratio as a marker of cytochrome P450 (CYP) 3A4 activity. Adduct levels were significantly higher in subjects resident in rural [geometric mean adduct level 34.9 pg aflatoxin B1-lysine equivalent (28.5-42.8; 95%CI)/mg albumin] than in periurban areas [22.2 pg (14.9-33.4)/mg] and were approximately twice as high in the dry season [mid-February to March; 83.2 pg (53.3-130.8)/mg] than the wet [July to August; 34.9 pg (28.5-42.8)/mg]. In contrast, HBV status, CYP3A4 phenotype, GSTT1, GSTP1 and EPXH genotypes were not associated with aflatoxin-albumin adduct level. However, mean adduct levels were significantly higher in non-HBV infected subjects with GSTM1 null genotype. The main factors which affect aflatoxin-albumin adduct levels in this population are environmental, notably place of residence and timing of sample collection. This study further emphasises the priority to reduce aflatoxin exposure in these communities by primary prevention measures.

The effects of grapefruit juice on sertraline metabolism: an in vitro and in vivo study

Grapefruit juice is an inhibitor of cytochrome P-450 3A4 (CYP3A4). This study was designed to assess the in vitro and in vivo effects of grapefruit juice on sertraline metabolism. The in vitro assay involved analysis of sertraline metabolism by CYP3A4 using CYP3A4-expressed human beta-lymphoblast microsomes. The in vivo study involved high-performance liquid chromatographic analysis of serum trough levels of sertraline and desmethylsertraline in 5 patients who had been taking their usual dose of sertraline for > or =6 weeks, followed by concurrent use of sertraline with grapefruit juice for 1 week. The in vitro assay demonstrated that grapefruit juice inhibited the formation of desmethylsertraline in a dose-dependent manner. In the in vivo study, mean serum sertraline levels were determined in 5 patients with a history of depression (4 males and 1 female). The mean age of the patients was 68.6 years, their mean weight was 69.6 kg, and their mean sertraline dosage was 55 mg/d. The results of the in vivo study appeared to be consistent with the in vitro findings, in that mean (+/- SD) serum sertraline trough levels increased significantly from 13.7+/-4.9 microg/L before to 20.2+/-4.4 microg/L (P = 0.047) after administration of grapefruit juice. Thus the in vitro study demonstrated that grapefruit juice can inhibit the metabolism of sertraline. A larger study is warranted to substantiate the clinical significance of the in vivo findings.

Mibefradil but not isradipine substantially elevates the plasma concentrations of the CYP3A4 substrate triazolam

BACKGROUND

The calcium channel blockers mibefradil and isradipine inhibit CYP3A4 in vitro. However, their in vivo inhibitory effects on CYP3A4 are not known in detail, although mibefradil was recently withdrawn from the market because of serious drug interactions.

METHODS

The effects of mibefradil and isradipine on the pharmacokinetics and pharmacodynamics of oral triazolam, a model substrate of CYP3A4, were studied in a randomized, double-blind crossover study with three phases. Nine healthy subjects took 50 mg mibefradil, 5 mg isradipine, or placebo orally once a day for 3 days. On day 3, each subject received a single 0.25 mg oral dose of triazolam. Thereafter, blood samples were collected up to 18 hours, and pharmacodynamic effects of triazolam were measured up to 8 hours.

RESULTS

Mibefradil increased the total area under the plasma triazolam concentration-time curve [AUC(0 - infinity)] 9-fold compared with placebo (P < .001). The peak plasma concentration of triazolam was increased 1.8-fold (3.4+/-0.1 ng/mL versus 1.8+/-0.2 ng/mL [mean +/- SEM]; P < .001), and the elimination half-life (t 1/2) was increased 4.9-fold (18.5+/-1.9 hours versus 4.0+/-0.5 hours; P < .001) by mibefradil. In addition, mibefradil was associated with increased pharmacodynamic effects of triazolam. In contrast to mibefradil, isradipine reduced the AUC(0 - infinity) and t 1/2 of triazolam by about 20% (P < .05) and had no significant effects on the pharmacodynamics of triazolam.

CONCLUSION

Mibefradil but not isradipine markedly increases the plasma concentrations of triazolam and thereby enhances and prolongs its pharmacodynamic effects, consistent with potent inhibition of CYP3A4.

In vivo inhibition of peptidylglycine-alpha-hydroxylating monooxygenase by 4-phenyl-3-butenoic acid

Peptidylglycine-alpha-hydroxylating monooxygenase (PHM; EC 1.14.17. 3) catalyzes the first and rate-limiting reaction in the two-step process that alpha-amidates neural and endocrine peptides. The substrate analog 4-phenyl-3-butenoic acid (PBA) was shown in vitro to selectively inhibit PHM without affecting the activity of peptidyl-alpha-hydroxyglycine alpha-amidating lyase, the enzyme that mediates the second reaction in alpha-amidation. Inhibition of PHM activity by PBA lowered the V(max) of the enzyme without altering its K(m). Administration of PBA in vivo profoundly inhibited serum PHM activity in a dose- and time-related fashion. Maximal reductions to less than 5% of control levels were observed 3 h after a single administration (500 mg/kg). Inhibition of serum PHM activity by PBA was short-lived, being fully reversed by 24 h postinjection. PHM activity in cardiac atrium, hypothalamus, and anterior and neurointermediate lobes of the pituitary were also decreased by PBA treatment but to a lesser extent than with serum. Inhibition of PHM activity by PBA was not cumulative over time when assessed 24 h after the last of 10 daily injections (500 mg/kg). The role of protein synthesis in maintaining PHM activity in blood was demonstrated by treatment with cycloheximide, which reduced serum PHM activity and retarded the recovery of PHM activity after PBA administration. It is concluded that the metabolism and/or clearance of PBA is rapid and that de novo protein synthesis has an important role in mediating the rapid restoration of PHM activity after PBA administration.

N-acylglycine amidation: implications for the biosynthesis of fatty acid primary amides

Bifunctional peptidylglycine alpha-amidating enzyme (alpha-AE) catalyzes the O2-dependent conversion of C-terminal glycine-extended prohormones to the active, C-terminal alpha-amidated peptide and glyoxylate. We show that alpha-AE will also catalyze the oxidative cleavage of N-acylglycines, from N-formylglycine to N-arachidonoylglycine. N-Formylglycine is the smallest amide substrate yet reported for alpha-AE. The (V/K)app for N-acylglycine amidation varies approximately 1000-fold, with the (V/K)app increasing as the acyl chain length increases. This effect is largely an effect on the KM,app; the KM,app for N-formylglycine is 23 +/- 0.88 mM, while the KM,app for N-lauroylglycine and longer chain N-acylglycines is in the range of 60-90 microM. For the amidation of N-acetylglycine, N-(tert-butoxycarbonyl)glycine, N-hexanoylglycine, and N-oleoylglycine, the rate of O2 consumption is faster than the rate of glyoxylate production. These results indicate that there must be the initial formation of an oxidized intermediate from the N-acylglycine before glyoxylate is produced. The intermediate is shown to be N-acyl-alpha-hydroxyglycine by two-dimensional 1H-13C heteronuclear multiple quantum coherence (HMQC) NMR.

Effects of chronic pulmonary overcirculation on pulmonary vasomotor tone

BACKGROUND

A model of shunt-induced pulmonary hypertension was used to study the effects of pulmonary overcirculation on endothelial nitric oxide synthase (eNOS) and cytochrome P450-4A (cP450-4A) vasodilatory mechanisms and related hemodynamic responses.

METHODS

An aortopulmonary shunt was constructed in 6-week-old piglets (n = 7, sham-operated controls n = 8). Hemodynamic measurements were made 4 weeks later under serial experimental conditions: baseline (fractional concentration of oxygen, 0.4); inhaled nitric oxide, 25 ppm (INO); hypoxia (fractional concentration of oxygen, 0.14); hypoxia + INO; N(omega)-nitro-L-arginine methylester (L-NAME 30 mg/kg intravenously, competitive NOS inhibitor); and L-NAME + INO. Lung protein levels of eNOS and cP450-4A and NOS activity were compared between groups.

RESULTS

Shunted animals had a higher baseline pulmonary artery pressure (p < 0.05). L-NAME resulted in a greater increase in pulmonary vascular resistance in shunted animals (150% +/- 26% shunt versus 69% +/- 14% control; p = 0.01). The INO administered during baseline conditions decreased pulmonary vascular resistance only in control animals (p < 0.05). Protein levels of eNOS and NOS activity were similar in both groups; however, cP450-4A protein levels were decreased in the shunted group (p = 0.02).

CONCLUSIONS

The NO production was preserved in shunted animals but they demonstrated greater vasodilatory dependence on NO, evidenced by an exaggerated increase in pulmonary vascular resistance after NOS inhibition. Loss of the cP450-4A vasodilatory system may be the driving force for NO dependency in the shunted pulmonary circulation.

[Low serum dopamine -- beta-hydroxylase activity in patients with panic disorder]

Serum dopamine-beta-hydroxylase (DBH) activity was determined in the following diagnostic groups of patients (DSM-III-R criteria): panic disorder (n = 16), generalized anxiety disorder (n = 10), hypochondrical disorder (n = 16). Twenty healthy persons constituted the control group. Enzyme activity in the group of panic disorder (9.3 +/- 12.5 IU/l) was statistically significantly lower as compared to the groups: control (20.1 +/- 8.1 IU/l), generalized anxiety disorder (17.6 +/- 13.5 IU/l) and hypochondrical disorder (13.6 +/- 10.6 IU/l). Possible relationship between low serum DBH activity and panic disorder is not clear.

Fatty acid omega- and (omega-1)-hydroxylation in experimental alcoholic liver disease: relationship to different dietary fatty acids

Arachidonic acid concentrations in liver are decreased in response to ethanol administration. In addition, the oxygenated products of arachidonic acid metabolites could affect the severity of alcoholic liver injury. Selective utilization of arachidonic acid by the cytochrome P-450 system could, in part, account for the decrease in arachidonic acid. To evaluate this pathway further, male Wistar rats were fed different dietary fats: medium chain triglycerides, palm oil, and corn oil or fish oil with either ethanol or isocaloric amounts of dextrose. Histopathology, cytochrome P-4502E1 (CYP2E1) and cytochrome P-4504A (CYP4A), and omega- and (omega-1)-hydroxylation products of lauric and arachidonic acids were evaluated. Ethanol induction of CYP2E1 was related to the concentration of polyunsaturated fatty acids in the diet; induction of CYP4A by ethanol was seen in all groups. The highest levels of 11-hydroxy-lauric acid and 19-hydroxyarachidonic acid (omega-1) were seen in rats fed ethanol with palm oil and corn oil. Highly significant correlations were seen between the (omega-1)-hydroxylation products and CYP2E1 activity. No correlation was seen between the omega-hydroxylation products and CYP2E1 activity. In contrast, the levels of omega-hydroxylation products correlated with CYP4A. The overall results showed a significant increase in (omega-1)-hydroxylation products in rats fed diets containing significant amounts of linoleic acid (i.e., palm oil and corn oil).

In vitro copper stimulation of plasma peptidylglycine alpha-amidating monooxygenase in Menkes disease variant with occipital horns

We determined the concentrations of copper, the activities of ceruloplasmin and peptidylglycine alpha-amidating monooxygenase (PAM), and the stimulation index of PAM by the in vitro addition of copper in plasma samples obtained from three male patients with occipital horns and a milder Menkes disease phenotype, having severe copper deficiency due to the defect in copper transport. We found a decreased plasma ceruloplasmin activity and an increased copper stimulation index of plasma PAM in these patients compared with healthy control subjects. The combination of these two determinations may provide a means for the assessment of copper nutriture in humans using blood samples obtained in a single microhematocrit tube. Further investigation is warranted to evaluate whether these noninvasive measurements can be used for the diagnosis of mild copper deficiency in humans with sufficient specificity and sensitivity.

The characterization of potent novel warfarin analogs

Racemic sodium warfarin, Coumadin, is widely used in the prevention of thromboembolic disease. The present study was undertaken to characterize three novel classes of warfarin analogs, and to compare them with the warfarin enantiomers. All three classes of compounds inhibit vitamin K epoxide reductase, the enzyme inhibited by racemic warfarin. The alcohol and the ester analogs have reduced protein binding compared with R-(+)-warfarin. The ester and the fluoro-derivatives have similar in vivo anticoagulant activity in the rat to that of S-(-)-warfarin. Thus, it is possible to synthesize novel warfarin analogs that differ from racemic warfarin or its enantiomers in certain selected properties.

Effects of horminone on liver mixed function mono-oxygenases and glutathione enzyme activities of Wistar rat

The present study reports on the effects of horminone on serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, on hepatic cytochrome P450 (P450) and cytochrome b5 (cyt b5) contents and on the activities of NADPH-cytochrome P450 reductase (NR), mixed function mono-oxygenases (MFO), glutathione-S-transferase (GST) and glutathione reductase (GR) of Wistar male rat. Horminone is a diterpenoid quinone (7,12-dihydroxyabiet-8,12-diene-11,14-dione) present in several species of the Labiatae family and used as medicinal plants in folk medicine. In this study, horminone was administered by the intraperitoneal route (i.p.) at a concentration of 1 or 10 mg/kg to each group of six mice, using water as a vehicle. On the one hand, results showed that horminone increased serum ALT and AST levels and cyt b5 content and induced the activities of ethylmorphine N-demethylase (EMD). On the other hand, horminone decreased P450 content and inhibited the activities of 7-ethoxyresorufin O-deethylase (ERD), 7-ethoxycoumarin O-deethylase (ECD), aniline 4-hydroxylase (AH) and NR. Based on these results, the possibility of toxic effects occurring after administration of plant extracts containing horminone must be considered.

Role of intestinal P-glycoprotein (mdr1) in interpatient variation in the oral bioavailability of cyclosporine

Interpatient differences in the oral clearance of cyclosporine (INN, ciclosporin) have been partially attributed to variation in the activity of a single liver enzyme termed CYP3A4. Recently it has been shown that small bowel also contains CYP3A4, as well as P-glycoprotein, a protein able to transport cyclosporine. To assess the importance of these intestinal proteins, the oral pharmacokinetics of cyclosporine were measured in 25 kidney transplant recipients who each had their liver CYP3A4 activity quantitated by the intravenous [14C-N-methyl]-erythromycin breath test and who underwent small bowel biopsy for measurement of CYP3A4 and P-glycoprotein. Forward multiple regression revealed that 56% (i.e., r2 = 0.56) and 17% of the variability in apparent oral clearance [log (dose/area under the curve)] were accounted for by variation in liver CYP3A4 activity (p < 0.0001) and intestinal P-glycoprotein concentration (p = 0.0059), respectively. For peak blood concentration, liver CYP3A4 activity accounted for 32% (p = 0.0002) and P-glycoprotein accounted for an additional 30% (p = 0.0024) of the variability. Intestinal levels of CYP3A4, which varied tenfold, did not appear to influence any cyclosporine pharmacokinetic parameter examined. We conclude that intestinal P-glycoprotein plays a significant role in the first-pass elimination of cyclosporine, presumably by being a rate-limiting step in absorption. Drug interactions with cyclosporine previously ascribed to intestinal CYP3A4 may instead be mediated by interactions with intestinal P-glycoprotein.

Selective mechanism-based inactivation of peptidylglycine alpha-hydroxylating monooxygenase in serum and heart atrium vs. brain

Peptidylglycine alpha-hydroxylating monooxygenase (PHM; EC 1.14.17.3) catalyses the rate-limiting step in the post-translational activation of substance P, among other neuropeptides, from its glycine-extended precursor. Comparative kinetic studies were performed, using trans-styrylacetic acid or trans-styrylthioacetic acid as known mechanism-based inhibitors, of PHM isolated from rat, horse or human blood serum. Distinctive species differences with respect to PHM inactivation were observed: the efficiency of inactivation decreased in the order of horse >> rat > human. Trans-styrylacetic acid was more active than its thioether derivative. Moreover, we studied the differential sensitivity towards mechanism-based inactivation, of soluble PHM from rat blood serum and rat brain by trans-styrylacetic acid or benzylhydrazine, as well as the membrane-associated enzymes from rat brain and heart atrium. For the heart atrium membrane PHM or the soluble PHM from blood serum, inactivation rate constants k(inact)/K(I) of approximately 100 M(-1)sec(-1) were found with trans-styrylacetic acid. However, neither of the two tested compounds, at 100 microM or 12 mM, respectively, could inactivate the soluble or membranous PHMs from rat brain during a 15-min pre-incubation period. Instead, under conditions of reversible inhibition, trans-styrylacetic acid competitively inhibited the soluble or membrane-associated brain PHM with inhibition constants K(I) = 0.6 microM and 1.0 microM, respectively. Organ-selective, time-dependent inactivation of PHM with compounds of the above types might be an important pharmacological tool to control peripheral neuropeptide activation.

[O2 sensitive L-lactate biosensors with enzyme membranes based on L-lactate-2-monooxygenase and L-lactate-oxidase with electroanalytic comparison]

O2-sensitive biosensors using oxidase membranes have acquired considerable electro-analytical importance. Since some of these O2-converting enzymes also produce H2O2, the use of additive reagents for the O2-free breakdown of the H2O2 in the second reaction has repeatedly been reported. In contrast to L-lactate oxidase, L-lactate-2-monooxygenase converts its substrate without producing H2O2. Employing reference sera, tests with L-lactate showed that bioelectrochemical membrane electrodes with H2O2-producing enzymes of high purity, require no additive reagents to ensure reliable analysis. Continuous measurements with citrated blood using the principle of intermediate carrier analysis are demonstrated.

Prevention of ethanol-induced changes in reactive oxygen parameters by alpha-tocopherol

Rats were given a 200 mg/kg body weight daily dose of alpha-tocopherol by i.p. injection for 15 days. This resulted in elevated levels of glutathione in both liver and brain, and in a reduced hepatic rate of generation of reactive oxygen species. The depression of hepatic and cerebral glutathione levels in ethanol-consuming rats was prevented by simultaneous treatment with alpha-tocopherol. Other putative indices of hepatic pro-oxidant events, namely levels of mixed function oxidase and proteolytic activity, were elevated by alpha-tocopherol both in the presence and absence of ethanol. In addition, levels of enzymes especially susceptible to oxidative degradation, glutamine synthetase and creatine kinase, were depressed in the liver following treatment with ethanol or alpha-tocopherol. Parameters rapidly responsive to oxidative changes revealed the antioxidant property of alpha-tocopherol, while protein-based indices reflecting more extended events suggested a pro-oxidant effect of this vitamin. Results suggest that high levels of alpha-tocopherol can simultaneously lead to a more reduced intracellular environment and yet to localized evidence of enhanced oxidative events.

In vivo induction of cytochrome P450 CYP3A expression in rat leukocytes using various inducers

Although the induction of cytochromes P450 3A (CYP3A) is relatively well characterized in liver, its inducibility in an easily available tissue such as the peripheral leukocytes is not known. The purpose of this study was, therefore, to determine if CYP3A is inducible in vivo in peripheral leukocytes. Microsomes from rat leukocytes and liver were examined for CYP3A protein expression using Western blotting with a rabbit polyclonal antibody against rat CYP3A. Although CYP3A was not detected in control leukocytes, in vivo treatment with known CYP3A inducers (dexamethasone, clotrimazole, phenobarbital, pregnenolone-16 alpha-carbonitrile) resulted in CYP3A leukocyte levels of 0.2-0.8 pmol/mg protein. This leukocyte induction was approximately 1000-fold lower than in induced liver. Interestingly, there was an apparent linear relationship between leukocyte and liver CYP3A contents (r2 = 0.748, n = 29). These results not only demonstrate for the first time that CYP3A is inducible in rat leukocytes after in vivo treatment with various CYP3A inducers, but also suggest that peripheral leukocytes could be used to assess induction in vivo.

Ambiguous genitalia

The newborn whose genitalia are ambiguous presents a challenge to the pediatrician and the family. A clear understanding of the basis of sex differentiation and timely consultation with a pediatric endocrinologist is critical in the evaluation and determination of sex of rearing in a newborn who has ambiguous genitalia. Sex karyotype and a 17-OHP level may suffice in the initial evaluation of female pseudohermaphroditism because most patients will have virilizing CAH. If male pseudohermaphroditism is suspected on the basis of palpable gonads, we routinely obtain a karyotype, basal adrenal steroid levels, and levels of hCG-stimulated serum testosterone and DHT, then consider a testosterone treatment trial. Physicians who care for children who have ambiguous genitalia must appreciate the family's cultural, religious, and psychological needs and avoid determining sex of rearing before accurate diagnosis is reached.

Peptide amidating activity and gastrin processing in the developing sheep pancreas

Gastrin is a regulator of both gastric acidity and gastrointestinal growth and is expressed transiently in the neonatal ovine and human pancreas. C-terminal amidation of glycine extended gastrin (G-gly) to gastrin amide (G-amide) by peptidylglycine alpha-amidating mono-oxygenase (PAM) is the final processing step. To investigate the relationship between PAM and gastrin synthesis in the developing pancreas, we measured PAM activity and the concentrations of gastrins in ovine pancreatic extracts from 95 days of gestation onwards. Pancreatic PAM activity was highest in the 95-day-old fetus (138 +/- 29 pmol/h/mg protein, mean +/- S.E.M.) and decreased to 9.5 +/- 3.7 pmol/h/mg protein in the adult. The circulating enzyme was also highest in the youngest fetus (1840 +/- 165 pmol/h/ml plasma) decreasing to approximately 50% in the 135-day-old fetus, with no further significant changes. The concentration of bioactive G-amide in the pancreas was 2.0 +/- 0.6 pmol/g at 95 days of gestation, 3.4 +/- 0.9 pmol/g at 135 days and decreased to 0.7 +/- 0.1 pmol/g in the adult. The precursor G-gly followed a similar pattern but its concentration was less than 10% of G-amide. These results show that: (a) there are high levels of PAM activity in the ovine fetal pancreas and in the fetal circulation, (b) PAM activity is apparently not rate-limiting in the bioactivation of pancreatic gastrin and (c) the dual expression of both PAM and gastrin in the fetal pancreas is similar to that observed in peptide-secreting tumours of the adult.

Increased peptidylglycine alpha-amidating monooxygenase activity in cerebrospinal fluid of patients with multiple sclerosis

Peptidylglycine alpha-amidating monooxygenase (PAM) plays a key role in the biosynthesis of many biologically active neuronal and endocrine peptides that possess alpha-amide function at their C-terminus. Using D-Tyr-Val-Gly as the substrate, we measured PAM activity levels in the cerebrospinal fluid (CSF) and serum of patients with a variety of neurological diseases. PAM activity in the CSF was significantly increased in patients with multiple sclerosis (MS), especially during the active stage, compared with that in patients with other neurological diseases (p < 0.05). Levels of CSF PAM activity were not correlated with protein levels in CSF or with level of serum PAM activity. Since PAM is present not only in neurons but also in oligodendroglia, it is possible that the increase in CSF PAM activity in patients with MS may stem from massive demyelination and oligodendroglial destruction.