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Caffeine (5 mg kg-1) was administered orally to two healthy, non- smoking subjects on three separate occasions-before, and during therapy with the xanthine oxidase inhibitor allopurinol at doses of either 300 or 600 mg daily. Plasma and urinary levels of methylxanthines, endogenous oxypurines and allopurinol and its metabolite oxypurinol were measured using h.p.l.c. analyses. Allopurinol treatment caused a specific, dose-dependent inhibition of the conversion of the caffeine metabolite 1-methylxanthine (1X) to 1- methyluric acid (1U). A good correlation was observed in both subjects between the urinary 1U/1X molar ratio and the ratio of endogenous urate to hypoxanthine + xanthine at the different allopurinol doses, supporting the proposal that the 1U/1X molar ratio after caffeine intake provides an in vivo index of xanthine oxidase activity in man. [ABSTRACT FROM AUTHOR]

A method is presented for the use of caffeine, in the forms commonly ingested by a large proportion of the world's population, to test for the clinically important acetylation polymorphism. Each of 146 subjects provided a spot sample of urine between 2 and 6 h after coffee, tea or cola soft drink consumption, and the molar ratio of 5-acetylamino-6- formylamino −3-methyluracil (AFMU) to 1-methylxanthine (1X) was determined by a simple h.p.l.c. assay. The ratio afforded segregation of three apparent modes of acetylation capacity in this population, in concordance with a standard sulphamethazine phenotyping procedure and with other methods using controlled caffeine intake and urine collections. The day-to-day consistency of the method was established in eight selected subjects. [ABSTRACT FROM AUTHOR]

Domestic abuse often begins or escalates during the perinatal period, increasing the risk of adverse pregnancy outcomes and death of the woman and infant. The hidden nature of domestic abuse, compounded by barriers to disclosure, means many clinicians are likely to have unknowingly encountered a patient who is being abused and missed a vital opportunity for intervention. This educational article presents the experience of a woman who was abused during pregnancy. It describes how to facilitate a disclosure and conduct an assessment and illustrates safeguarding duties alongside interventions.

Growing evidence shows that generation of reactive oxygen species (ROS) derived from antibiotic-induced metabolic perturbation contribute to antibiotic lethality. However, our knowledge of the mechanisms by which antibiotic-induced oxidative stress actually kills cells remains elusive. Here, we show that oxidation of dCTP underlies ROS-mediated antibiotic lethality via induction of DNA double-strand breaks (DSBs). Deletion of mazG -encoded 5-OH-dCTP-specific pyrophosphohydrolase potentiates antibiotic killing of stationary-phase mycobacteria, but did not affect antibiotic efficacy in exponentially growing cultures. Critically, the effect of mazG deletion on potentiating antibiotic killing is associated with antibiotic-induced ROS and accumulation of 5-OH-dCTP. Independent lines of evidence presented here indicate that the increased level of DSBs observed in the ΔmazG mutant is a dead-end event accounting for enhanced antibiotic killing. Moreover, we provided genetic evidence that 5-OH-dCTP is incorporated into genomic DNA via error-prone DNA polymerase DnaE2 and repair of 5-OH-dC lesions via the endonuclease Nth leads to the generation of lethal DSBs. This work provides a mechanistic view of ROS-mediated antibiotic lethality in stationary phase and may have broad implications not only with respect to antibiotic lethality but also to the mechanism of stress-induced mutagenesis in bacteria., Competing Interests: The authors declare no conflict of interest.

Objective: To conduct the cloning identification and characterization of the sequence of human IL-17A promoter so as to analyze the regulatory mechanism of the gene expression of IL-17., Methods: First of all, the potential promoter region of IL-17A was found by means of the bioinformatics methods. Then, it was cloned into the reporter vector with PCR technique. Finally, the activity of the test promoter was determined by dual luciferase reporter system., Results: Two transcriptional start points of the upper region, 600 bp and 1000 bp, of IL-17A were obtained by PCR clone and proved to have certain activities by dual luciferase reporter system. Also, they could be activated by IL-17A activator STAT3, which could start the expression of the reported gene., Conclusions: Clone established the regulatory region of human IL-17A promoter, which provided bases to the subsequent function research., (Copyright © 2016 Hainan Medical College. Production and hosting by Elsevier B.V. All rights reserved.)

Generation of reactive oxygen species and reactive nitrogen species in phagocytes is an important innate immune response mechanism to eliminate microbial pathogens. It is known that deoxynucleotides (dNTPs), the precursor nucleotides to DNA synthesis, are one group of the significant targets for these oxidants and incorporation of oxidized dNTPs into genomic DNA may cause mutations and even cell death. Here we show that the mycobacterial dNTP pyrophosphohydrolase MazG safeguards the bacilli genome by degrading 5-OH-dCTP, thereby, preventing it from incorporation into DNA. Deletion of the (d)NTP pyrophosphohydrolase-encoding mazG in mycobacteria leads to a mutator phenotype both under oxidative stress and in the stationary phase of growth, resulting in increased CG to TA mutations. Biochemical analyses demonstrate that mycobacterial MazG can efficiently hydrolyze 5-OH-dCTP, an oxidized nucleotide that induces CG to TA mutation upon incorporation by polymerase. Moreover, chemical genetic analyses show that direct incorporation of 5-OH-dCTP into mazG-null mutant strain of Mycobacterium smegmatis (Msm) leads to a dose-dependent mutagenesis phenotype, indicating that 5-OH-dCTP is a natural substrate of mycobacterial MazG. Furthermore, deletion of mazG in Mycobacterium tuberculosis (Mtb) leads to reduced survival in activated macrophages and in the spleen of infected mice. This study not only characterizes the mycobacterial MazG as a novel pyrimidine-specific housecleaning enzyme that prevents CG to TA mutation by degrading 5-OH-dCTP but also reveals a genome-safeguarding mechanism for survival of Mtb in vivo.

Introduction: Mammographically dense breast tissue is a strong predictor of breast cancer risk, and is influenced by both mitogens and mutagens. One enzyme that is able to affect both the mitogenic and mutagenic characteristics of estrogens is cytochrome P450 1A2 (CYP1A2), which is principally responsible for the metabolism of 17beta-estradiol., Methods: In a cross-sectional study of 146 premenopausal and 149 postmenopausal women, we examined the relationships between CYP1A2 activity, malondialdehyde (MDA) levels, and mammographic density. In vivo CYP1A2 activity was assessed by measuring caffeine metabolites in urine. Levels of serum and urinary MDA, and MDA-deoxyguanosine adducts in DNA were measured. Mammograms were digitized and measured using a computer-assisted method., Results: CYP1A2 activity in postmenopausal women, but not in premenopausal women, was positively associated with mammographic density, suggesting that increased CYP1A2 activity after the menopause is a risk factor for breast cancer. In premenopausal women, but not in postmenopausal women, CYP1A2 activity was positively associated with serum and urinary MDA levels; there was also some evidence that CYP1A2 activity was more positively associated with percentage breast density when MDA levels were high, and more negatively associated with percentage breast density when MDA levels were low., Conclusion: These findings provide further evidence that variation in the activity level of enzymes involved in estrogen metabolism is related to levels of mammographic density and potentially to breast cancer risk.

Introduction: Breast cancer risk may be determined by various genetic, metabolic, and lifestyle factors that alter sex hormone metabolism. Cytochrome P450 1A2 (CYP1A2) is responsible for the metabolism of estrogens and many exogenous compounds, including caffeine., Methods: In a cross-sectional study of 146 premenopausal and 149 postmenopausal women, we examined the relationships between CYP1A2 activity and known or suspected risk factors for breast cancer. Blood levels of sex hormones, lipids, and growth factors were measured. In vivo CYP1A2 activity was assessed by measuring caffeine metabolites in urine. Stepwise and maximum R regression analyses were used to identify covariates related to CYP1A2 activity after adjustment for ethnicity., Results: In both menopausal groups CYP1A2 activity was positively related to smoking and levels of sex hormone binding globulin. In premenopausal women, CYP1A2 activity was also positively related to insulin levels, caffeine intake, age, and plasma triglyceride levels, and negatively related with total cholesterol levels and body mass index. In postmenopausal women CYP1A2 activity was positively associated with insulin-like growth factor-1, and negatively associated with plasma triglyceride, high-density lipoprotein cholesterol, and age at menarche., Conclusion: These results suggest that CYP1A2 activity is correlated with hormones, blood lipids, and lifestyle factors associated with breast cancer risk, although some of the observed associations were contrary to hypothesized directions and suggest that increased CYP1A2 function may be associated with increased risk for breast cancer.

Aims: To study the potential utility of caffeine based probes of CYP1A2 enzyme activity in predicting the pharmokinetics of tacrine in patients with Alzheimer's disease., Methods: The pharmokinetics of a single 40 mg oral dose of tacrine were measured in 19 patients with Alzheimer's disease. Each patient also received 2 mg kg(-1) [13C-3-methyl] caffeine orally and had breath and urine samples collected., Results: Tacrine oral clearance (CL F(-1) kg(-1)), which varied 15-fold among the patients, correlated significantly with the 2 h total production of 13CO2 in breath (r=0.56, P=0.01), and with each of two commonly used urinary caffeine metabolite ratios: the 'paraxanthine/caffeine ratio' (1,7X + 1, 7U)/1,3,7X) (r=0.76, P=0.0002) and the 'caffeine metabolic ratio' (AFMU + 1X + 1U)/1, 7U)(r=0.76, P=0.0001)., Conclusions: These observations support a central role for CYP1A2 in the in vivo disposition of tacrine and the potential for drug interactions when tacrine treated patients receive known inducers or inhibitors of this enzyme. The magnitude of the correlations we observed, however, are probably not sufficient to be clinically useful in individualizing tacrine therapy.

Previously, one of us (B. K. T.) developed an assay that measures levels of free ethanol and ethanol conjugates in urine and showed that the mean levels of these ethanol markers in confirmed alcoholics were at least 20-fold higher than those levels in control subjects. In this study, we assessed the relationship of these biomarkers with self-reported levels of alcohol intake in a multiethnic sample of Los Angeles County residents who were male and over the age of 35 years (n = 128; 40 non-Hispanic whites, 46 blacks, 17 Chinese, and 25 Japanese). Regardless of race, the mean levels of free, bound, and total (free plus bound) ethanol were lowest in nondrinkers, intermediate in weekly drinkers, and highest in daily drinkers (P = 0.0001 in all three statistical tests of differences in the three biomarkers). Stepwise discriminant analysis showed that of the three potential biomarkers, total ethanol best discriminates between the three classes of drinkers (non, weekly, and daily), and that additional inclusion of either free or bound ethanol in the discriminant function had negligible effect. Overall, mean level of total ethanol was 2.2 times higher in weekly than in nondrinkers; daily drinkers, in turn, showed a 4.2-fold increase in mean total ethanol relative to weekly drinkers. However, there was no correlation between any of the three biomarkers and self-reported level (in grams of ethanol) of average consumption in either weekly or daily drinkers whose mean intake was about 13 and 42 g of ethanol/day, respectively. As the level of urinary free ethanol and ethanol conjugates showed extraordinary differences among racial groups for a given level of self-reported ethanol intake, the data suggest possible interracial differences in the in vivo elimination rate of ethanol; this latter finding needs to be confirmed in larger studies.

Objectives: To examine the effects of occupational exposure to substances contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on cytochrome P-4501A2 activity in a cross sectional medical survey., Methods: The exposed workers had been employed at two chemical plants > 15 years earlier in the manufacture of 2,4, 5-trichlorophenol and its derivatives. The control group consisted of people with no occupational exposure to phenoxy herbicides and who lived within the communities of the exposed workers. A total of 58 workers and 125 unexposed controls participated in the analysis. Cytochrome P-450 activity was assessed with test that measures caffeine metabolites in the urine. A ratio of metabolites of caffeine (CMR) constituted a measure of P-4501A2 activity., Results: Compared with the control group in multivariate logistic regression, raised non-significant associations were found for three of four categories of TCDD in exposed workers (TCDD < 20 pg/g, odds ratio (OR) 1.7, 95% confidence interval (95% CI) 0.6 to 5.0, TCDD 20-66, OR 0.3, 95% CI 0.0 to 1.7; TCDD 67-147, OR 2.3, 95% CI 0.6 to 8.8; TCDD > or = 148, OR 3.1, 95% CI 0.8 to 12.5). We found a strongly significant association of CMR and urinary cotinine, a measure of smoking, and urinary free ethanol. We found weak non-significant associations between P-4501A2 activity and increased serum TCDD among workers., Conclusions: The absence of an association between serum TCDD and cytochrome P-4501A2 may be due to the size of the study, insensitivity of the CMR to assess cytochrome P-4501A2 activity, or inadequate levels of exposure, although these were among the highest in human groups tested.

Four critically injured children receiving large doses of phenobarbitone were studied during hypothermia (30 degrees - 31 degrees C) and at normal body temperature. The volume of distribution of phenobarbitone varied from 0.79 to 1.01 litres per kg and the serum t 1/2 ranged from 36.8 +/- 9.4 to 86.2 +/- 10.5 hrs. The percentage of dose recovered in urine in 16 days ranged from 40.5 to 65.5 per cent: 2.7 to 12.4 per cent as hydroxyphenobarbitone, 1.7 to 19.7 per cent as conjugated hydroxyphenobarbitone, 6.0 to 22.4 per cent as phenobarbitone-N-glucoside and 17.8 to 23.1 per cent as unchanged drug. After the body temperature was allowed to return to normal the rate of excretion of metabolites increased substantially and the rate of excretion of the unchanged drug decreased markedly. It is concluded that reduction in body temperature influences the volume of distribution, rate of metabolism and excretion of phenobarbitone.

The uropygial (preen) gland secretion of the domestic turkey resembles that of the chicken in consisting mainly of a diester wax. The esterified fatty acids are saturated; they include all members of the n-C(10)-C(20) homologous series, the C(17)-C(19) acids together accounting for 60% of the total. There are four major 2,3-n-alkanediols, C(19)-C(23), all having the erythro configuration as determined by thin-layer chromatography on boric acid-silica gel and by gas-liquid chromatography. The chicken uropygiols, by contrast, contain erythro and threo diols. It is suggested that the chicken possesses two biosynthetic enzyme systems for the diols, the turkey only one