Evidence for environmental influence on CYP2D6-catalysed debrisoquine hydroxylation as demonstrated by phenotyping and genotyping of Ethiopians living in Ethiopia or in Sweden

Black Africans show lower rates of CYP2D6- and CYP2C19-dependent drug metabolism compared to Caucasians of the same apparent genotype. To determine if environmental factors are responsible for this difference, the genotypes and phenotypes of CYP2D6 and CYP2C19 among Ethiopians living in Sweden (n = 70) were assessed and compared to our previously published data from Ethiopians living in Ethiopia (n = 114) and Swedish Caucasians (n = 134). There was no significant difference in CYP2C19 genotype or phenotype as assessed by mephenytoin between Ethiopians in Sweden or in Ethiopia. However, Swedes were significantly more rapid for CYP2C19 activity than both Ethiopian groups (P < 0.01). A comparison of the debrisoquine MR among individuals of the same CYP2D6 genotype revealed that Swedes exhibited the highest rate of debrisoquine metabolism, followed by Ethiopians in Sweden and Ethiopians in Ethiopia. The difference between the Ethiopian groups was significant (P < 0.02 using a univariate test ANOVA) and amounted to approximately 50% of the magnitude of the MR difference between Swedes and Ethiopians in Ethiopia. It is tempting to speculate that inhibitory dietary factors may explain the differences seen between the two Ethiopian groups and that these components in the past might have contributed to dietary stress-mediated selection of duplicated and multiduplicated active CYP2D6 genes, as frequently seen in Ethiopians. In conclusion, the results indicate a significant influence of environmental factors as an explanation for the difference in capacity for CYP2D6, but not CYP2C19 metabolism between Caucasians and Black Africans. Additional factors remain to be elucidated to fully explain the interethnic differences in CYP2D6 activity.     

Lack of effect of growth hormone replacement therapy on CYP1A2 and xanthine oxidase activities in growth hormone–deficient children

Background and objectives The recombinant human growth hormone (rhGH) is being increasingly used for a number of metabolic alterations. GH is the main regulator of several hepatic drug metabolizing enzymes in rodents. In addition, GH could play a major role in defining the interface between pharmacogenetics and development. However, little is known about the effect of GH on the activity of hepatic enzymes in children. The aim of this study was to determine the effect of rhGH replacement therapy for 4 weeks on CYP1A2 and xanthine oxidase (XO) activities in children. Methods We used caffeine as a probe drug to assess the enzyme activities at two points in time: before starting GH treatment (day 0) and after 4 weeks on rhGH therapy (day A). A total of 31 GH-deficient children (age range: 4.1–13.1 years, mean age: 9.88±2.89 years) participated. Urinary concentrations of caffeine and metabolites were determined by high-performance liquid chromatography (HPLC) to calculate the metabolite ratios: (AFMU+1X+1U)/17U for CYP1A2 and 1U/(1X+1U) for XO. Results Four weeks of GH substitution did not importantly alter the markers of the enzyme activities measured in this study. Median values and 95% confidence intervals (CI) at baseline were 5.17 (3.87–5.59) for the CYP1A2 ratio and 0.62 (0.56–0.65) for the XO ratio. These values, after treatment, were 4.57 (3.90–5.97) for the CYP1A2 marker and 0.62 (0.59–0.67) for the XO ratio. Data comparison between periods showed lack of statistically significant differences (P>0.05). The relative changes measured by the ratios of medians and 90% CI were 1.14 (0.90–1.31) and 0.99 (0.94–1.06) for CYP1A2 and XO, respectively. Conclusions The absence of significant changes in the markers of enzyme activities CYP1A2 and XO suggests that rhGH replacement therapy of GH-deficient children for 4 weeks could not noticeably modify the efficacy or toxicity of substrates of these metabolic enzymes.     

Xanthine oxidase inhibition by allopurinol affects the reliability of urinary caffeine metabolic ratios as markers for N-acetyltransferase 2 and CYP1A2 activities

Objectives: To evaluate the in vivo effect of xanthine oxidase (XO) inhibition by allopurinol on the determination of polymorphic N-acetyltransferase 2 (NAT2) and cytochrome P450 1A2 (CYP1A2) with urinary caffeine metabolic ratios. Methods: In an open, prospective study involving 21 healthy subjects (eight fast, 13 slow NAT2 acetylators) allopurinol (300 mg perday) was administered orally on trial days 1–8, followed by a wash-out period of 8 days. Urinary caffeine tests (200 mg caffeine p.o.) were performed repetitively. Urine was collected for 8 h and venous blood samples for the determination of allopurinol, oxypurinol and uric acid were drawn. The urinary caffeine metabolites 1-methyluric acid (1MU), 1-methylxanthine (1MX), 1,7-dimethyluric acid (17MU), 1,7-dimethylxanthine (17MX), 5-acetylamino-6-formylamino-3-methyluracil (AFMU), plasma allopurinol and oxypurinol were analysed using high-performance liquid chromatography (HPLC). Results: During XO inhibition by allopurinol, the formation of 1MU from 1MX and therefore the XO ratio 1MU/1MX decreased to 15.9 (1.2)% [mean with (SEM)] of baseline values (P < 0.005). The NAT2 ratio AFMU/1MX decreased likewise to 56.7 (6.3)% (P < 0.005). AFMU/(AFMU + 1MX + 1MU), an alternative NAT2 ratio, remained constant, but the CYP1A2 ratio (AFMU + 1MX + 1MU)/17MU, used to express CYP1A2 activity, transiently increased to 167 (13)% (P < 0.005). The NAT2 phenotype did not influence CYP1A2 and XO ratios or plasma oxypurinol pharmacokinetics. Conclusions: Several caffeine metabolic ratios are commonly used to express the activities of NAT2, CYP1A2 and XO both in healthy volunteers and in polymedicated patients, although their reliability has not been evaluated thoroughly during concurrent drug administration. The findings of this study suggest that NAT2 phenotyping should be performed using the ratio AFMU/(AFMU + 1MX + 1MU) if an XO inhibitor may be present. It also shows that the determination of CYP1A2 activity with caffeine as a metabolic probe is considerably altered under these conditions. Thus, concomitant drug administration may impair the robustness of multiple pathways of the complex caffeine test. This points to the need for alternative probes, designed to assess only the activity of a single enzyme because, in contrast to healthy volunteers, in patients known or unknown drug interactions may often be present. Received: 10 August 1998 / Accepted in revised form: 5 October 1998     

In vivo evaluation of CYP2A6 and xanthine oxidase enzyme activities in the Serbian population

Purpose

The main aim of the study was to investigate the distribution of cytochrome P450 2A6 (CYP2A6) and xanthine oxidase (XO) enzyme activities in the Serbian population. Secondly, we tested the influence of genetics (CYP2A6 polymorphism), sex, and cigarette smoking on both enzymes.

Methods

One hundred forty healthy Serbian volunteers were genotyped for common CYP2A6 alleles. In 100 of them, CYP2A6 and XO activities were determined by the urinary 17U/17X and 1U/(1U?+?1X) ratios, respectively, after oral administration of 100 mg caffeine as a probe.

Results

A 21-fold variation in the 17U/17X ratio was observed (range: 0.49–10.28, mean?=?1.65, 95% CI: 1.49–1.83). The urinary 1U/(1U?+?1X) ratios displayed four-fold variation, ranging from 0.17 to 0.71 (mean?=?0.43, 95% CI: 0.41–0.45). CYP2A6 alleles *1A, *1B1, *9, *4 and *1B1x2 were found with frequencies of 0.579, 0.307, 0.082, 0.029, and 0.004 respectively. CYP2A6*5 was not detected. CYP2A6 genotype influenced interindividual variability in CYP2A6 enzyme activity (P?=?0.04). Cigarette smoking inhibited CYP2A6 enzyme activity (P?=?0.02), but had no effect on activity of XO (P?=?0.16).There was no significant difference between men and women in terms of CYP2A6 or XO activity.

Conclusions

Serbs displayed interindividual variations in CYP2A6 activity. CYP2A6 genotype and cigarette smoking, but not sex, influenced CYP2A6 enzyme activity. Unimodal distribution of XO enzyme activity in Serbs implies the absence of subjects with low enzyme activity in this population. XO activity is not influenced by sex or cigarette smoking.     

Phenotyping of <Emphasis Type="Italic">N</Emphasis>-acetyltransferase type 2 and xanthine oxidase with caffeine: when should urine samples be collected?

Objectives  Individual activities of N-acetyltransferase 2 (NAT2) and of xanthine oxidase (XO) can be assessed using ratios of urinary caffeine metabolites. We investigated how ratios changed over time and which urine collection interval would be the best for NAT2 and XO activity assessments. Methods  On two occasions separated by 14 days, 16 healthy male Caucasians collected urine before and 0–2, 2–4, 4–6, 6–8, 8–12, 12–16 and 16–24 h after a dose of 150 mg caffeine given in the framework of a phenotyping cocktail study. The metabolites 5-acetylamino-6-formylamino-3-methyluracil (AFMU), 5-acetylamino-6-amino-3-methyluracil (AAMU), 1-methylxanthine (1X), and 1-methylurate (1U) were quantified with LC-MS/MS. The molar ratio (AFMU + AAMU)/(1X + 1U + AFMU + AAMU) was used as a NAT2 metric, while the ratio 1U/(1X + 1U) served as XO metric. Results  The NAT2 ratios were stable in the intervals 4–24 h after caffeine dosing. Mean intra-individual coefficients of variation were 11–23% starting 4 h post-dose, while inter-individual variability reached 37–75%. The XO ratios increased gradually by 14% from the 2–4 to the 16–24 h interval. The mean intra- and inter-individual coefficients of variation of XO activity were 3–18 and 7–10% respectively. No significant differences between study occasions were observed. Conclusions  Any sampling interval at least 4 h after caffeine dosing is suitable for NAT2 and XO activity assessments. XO activities can only be compared between volunteers and studies if the same urine collection schedule has been respected. The low intraindividual variability allows for sample sizes of 16 and 6 participants in crossover interaction studies of NAT2 and XO activity respectively.     

Febuxostat,a novel xanthine oxidoreductase inhibitor,improves hypertension and endothelial dysfunction in spontaneously hypertensive rats

Xanthine oxidase (XO) is an enzyme responsible for the production of uric acid. XO produces considerable amount of oxidative stress throughout the body. To date, however, its pathophysiologic role in hypertension and endothelial dysfunction still remains controversial. To explore the possible involvement of XO-derived oxidative stress in the pathophysiology of vascular dysfunction, by use of a selective XO inhibitor, febuxostat, we investigated the impact of pharmacological inhibition of XO on hypertension and vascular endothelial dysfunction in spontaneously hypertensive rats (SHRs). Sixteen-week-old SHR and normotensive Wistar-Kyoto (WKY) rats were treated with tap water (control) or water containing febuxostat (3 mg/kg/day) for 6 weeks. Systolic blood pressure (SBP) in febuxostat-treated SHR (220?±?3 mmHg) was significantly (P?<?0.05) decreased compared with the control SHR (236?±?4 mmHg) while SBP in febuxostat-treated WKY was constant. Acetylcholine-induced endothelium-dependent relaxation in aortas from febuxostat-treated SHR was significantly (P?<?0.05) improved compared with the control SHR, whereas relaxation in response to sodium nitroprusside was not changed. Vascular XO activity and tissue nitrotyrosine level, a representative indicator of local oxidative stress, were considerably elevated in the control SHR compared with the control WKY, and this increment was abolished by febuxostat. Our results suggest that exaggerated XO activity and resultant increase in oxidative stress in this experimental model contribute to the hypertension and endothelial dysfunction, thereby supporting a notion that pharmacological inhibition of XO is valuable not only for hyperuricemia but also for treating hypertension and related endothelial dysfunction in human clinics.     

Effects of sodium nitroprusside on mouse erythrocyte catalase activity and malondialdehyde status

There is controversy about the anti- or pro-oxidative effects of the nitric oxide (NO)-donor sodium nitroprusside (SNP). Hence, the activity of the antioxidant enzyme catalase (CAT) and the status of malondialdehyde (MDA) were investigated after a 2.5?mg/kg dose of SNP had been i.p. administered to different and comparable groups of mice (n?= 48). The drug was administered at two different circadian times (1 and 13 h after light onset [HALO]). There were, irrespectively of sampling time, no significant differences in the means of CAT activity and MDA status between control and SNP-treated groups, no matter the treatment time. However, CAT activity was significantly (Student’s t-test, p?<?0.001) increased 1?h following SNP administration at 1 HALO, whereas the significant (p?<?0.001) increase in the enzyme activity was found only 3?h after injection at 13 HALO. The drug dosing either at 1 or 13 HALO resulted in no significant differences of MDA status between control and treated groups regardless to the sampling time. Two-way analysis of variance (ANOVA) detected a significant (F_0.05(7,88)=?5.3; p?<?0.0006) interaction between sampling time and treatment in mice injected at 1 HALO, suggesting the influence of treatment on sampling-time-related changes in CAT activity. However, ANOVA validated no interaction between the two factors in mice treated at 13 HALO, illustrating that the sampling-time differences in enzyme activity were greater. Furthermore, two-way ANOVA revealed no interaction in the variation of MDA status in animals treated either at 1 or 13 HALO. This study indicates that SNP significantly affected the anti-oxidant system.     

Genistein alters caffeine exposure in healthy female volunteers

Purpose

This study investigated the effect of 1?g genistein daily for 14?days on caffeine-based metrics of cytochrome P4501A2 (CYP1A2), cytochrome P4502A6 (CYP2A6), N-acetyltransferase 2 (NAT2), and xanthine oxidase (XO).

Methods

A single dose of 100?mg caffeine was administered once before and once on the last day of a 14-day treatment regime with 1?g genistein once daily to 18 healthy female volunteers. Urine and blood samples were collected up to 12 and 24?h, respectively, after each caffeine dose. Using high-performance liquid chromatography (HPLC), caffeine and 1,7-dimethylxanthine (17X) were quantified in plasma, whereas 17X, 1,7-dimethylurate (17U), 1-methylxanthine (1X), 1-methylurate (1U), and 5-acetylamino-6-formylamine-3-methyluracil (AFMU) were quantified in urine. Urinary metabolite ratios were calculated to assess enzyme activities and compared between administrations using analysis of variance (ANOVA).

Results

Genistein decreased the urinary caffeine metabolite ratio used to assess CYP1A2 activity by 41% [90% confidence interval (CI) 28?C51%). The urinary ratio indicating XO activity decreased by 29% (90% CI 24?C32%), whereas urinary ratio for CYP2A6 activity increased by 47% (90% CI 29?C66%) after 2?weeks of genistein. The NAT2 urinary caffeine metabolite ratio did not change significantly.

Conclusions

Two weeks of intake of 1?g genistein daily led to decreases in CYP1A2 and XO activity and an increase in CYP2A6 activity, whereas NAT2 activity did not change in healthy Chinese female volunteers. Pharmacokinetics of other substrates of the enzymes investigated here may be influenced in a similar manner.     

Comparison of N-acetyltransferase-2 enzyme genotype-phenotype and xanthine oxidase enzyme activity between swedes and koreans

The aim of this study was to compare xanthine oxidase (XO) and N-acetyltransferase-2 (NAT2) genotype and phenotype between Swedes (n = 113) and Koreans (n = 150), as well as to investigate the effect of sex, smoking, age, and oral contraceptive (OC) use on enzyme activities, using caffeine as a probe. XO and NAT2 activities were estimated by 1U/(1U+1X) and AFMU/(AFMU+1X+1U) urinary ratios, respectively. Participants were genotyped for 191G>A, 341T>C, 590G>A, and 857G>A NAT2 polymorphisms. There was no significant difference in XO activity between Swedes and Koreans. In Swedes, higher XO activity was observed in women (P < .003). There were significant differences in NAT2 genotype and phenotype between Swedes and Koreans. Koreans display significantly higher frequency of NAT2 fast acetylator genotype (89%), whereas the slow acetylator genotype is predominant (62%) in Swedes (P < .0001). Significantly higher NAT2 activity was observed in Koreans compared to Swedes (P < .0001). Having the same NAT2 fast acetylator genotype, Koreans display higher enzyme activity than Swedes (P < .004). OC use significantly increased NAT2 activity in Swedish women. In conclusion, Koreans display higher NAT2 activity than Swedes regardless of NAT2 genotype. Ethnicity, OC use, and genotype determine NAT2 activity, whereas sex is the only determinant of XO activity.     

Bioefficacy of budesonide loaded crosslinked polyeletrolyte microparticles in rat model of induced colitis

A targeted delivery system for inflammatory bowel diseases, chitosan-Ca-alginate microparticles efficiently loaded with budesonide (BDS), were designed using one-step spray-drying process. They were eudragit-coated and examined for in vivo efficacy. Experimental colitis was induced by rectal instillation of 2,4,6-trinitrobenzene sulphonic acid (TNBS) into male Wistar rats. Drugs were administered by oral gavage daily for 5 days. Colon/body weight ratio, gross morphological and histological evaluation, and clinical activity score were determined as inflammatory indices. Individual clinical and histological evaluation showed that colitis severity was suppressed the most greatly in order BDS < BDS/C-Ca-A < E-BDS/C-Ca-A. Clinical activity score decreased in the same order. Statistical analyses of total score points indicate that the incorporation of BDS in microparticles had significant differences in favor of efficacy of designed delivery system with mucoadhesive and controlled release properties (one-way ANOVA, P?<?0.05). The results established the prediction by previous in vitro studies.     

Induction of CYP1A2 by heavy coffee consumption in Serbs and Swedes

Objectives To investigate the influence of coffee consumption on CYP1A2 enzyme activity controlling for the effects of smoking and oral contraceptive (OC) use among Serbs and Swedes and to compare CYP1A2 activity between the two populations. Methods Data on oral contraceptive use, habitual coffee consumption and smoking habits were obtained from 100 Serbian and 149 Swedish healthy volunteers using a detailed questionnaire. CYP1A2 activity was estimated by plasma paraxanthine/caffeine (17X/137X) ratio analysed by reversed-phase HPLC after oral administration of 100 mg caffeine. Results Daily consumption of at least three cups of coffee significantly increased CYP1A2 enzyme activity in both Serbs (P = 0.0002) and Swedes (P < 0.0001). Among non-smokers and non-OC users, heavy coffee consumption significantly increased CYP1A2 activity in Serbs (mean difference 0.11; 95% CI of the mean difference 0.04, 0.18; P = 0.003) and Swedes (mean difference 0.07; 95% CI of the mean difference 0.01, 0.12; P = 0.02). Significantly higher 17X/137X ratio was detected in Serbian smokers compared to non-smokers. There was no significant gender difference in CYP1A2 activity in Serbs. Controlling for the effect of smoking, heavy coffee consumption habit and oral contraceptive use, significantly lower 17X/137X ratio was observed in Serbs than in Swedes (P = 0.0003). Conclusions Habitual heavy coffee consumption increases CYP1A2 activity. Polycyclic aromatic hydrocarbons formed during roasting of coffee beans might partly be responsible for this effect. The reason for the observed lower CYP1A2 activity in Serbs as compared to Swedes remains to be investigated.     

Characterisation of cerivastatin as a P-glycoprotein substrate: studies in P-glycoprotein-expressing cell monolayers and <Emphasis Type="Italic">mdr1a/b</Emphasis> knock-out mice

The aim of this study was to characterise the role of the efflux transporter P-glycoprotein in the disposition of cerivastatin. We investigated directional transport characteristics of [¹⁴C]cerivastatin across cell monolayers expressing P-glycoprotein (Caco-2 and L-MDR1) and disposition of cerivastatin in mice with disrupted mdr1a and mdr1b genes. The mice were given orally 1 mg/kg cerivastatin and plasma and tissue samples for analysis of cerivastatin were obtained 10, 20, or 30 min after drug administration. Four knock-out mice and four wild-type mice were studied at each time point. In addition, the hypothesis that gemfibrozil-mediated inhibition of P-glycoprotein contributes to the interaction between gemfibrozil and cerivastatin was tested in Caco-2 cells. The apparent permeability coefficient (P_app) value for the basal-to-apical transport of cerivastatin in Caco-2 and L-MDR1 cell monolayers was 2.4 times (P<0.001) and 3.8 times (P<0.001) as high as the apical-to-basal P_app value respectively. The P-glycoprotein inhibitor PSC-833 (1 M) inhibited the net basal-to-apical transport of cerivastatin in Caco-2 monolayers by 35% (P<0.01) and the MRP inhibitor MK-571 (10 M) by 50% (P<0.01). At concentrations up to 250 M, gemfibrozil showed no significant effects on the net transport of cerivastatin in Caco-2 cells. The concentration of cerivastatin in the brain at 30 min was 3.1 times higher in the knock-out mice than in the wild-type mice (P<0.05). The brain-to-plasma cerivastatin concentration ratio at 20 min and 30 min was 2.1 (P<0.05) and 3.6 times (P<0.05) higher respectively in the knock-out animals compared with the wild-type animals. Collectively, these results indicate that cerivastatin is a P-glycoprotein substrate, although other transporters probably contribute to cerivastatin transport in humans. As several statins are P-glycoprotein substrates, beneficial as well as adverse effects of the statins might be affected by interindividual differences in P-glycoprotein expression or function caused by, e.g., the MDR1 polymorphism.     

SIMULTANEOUS ACTION OF THE FLAVONOID QUERCETIN ON CYTOCHROME P450 (CYP) 1A2, CYP2A6, N-ACETYLTRANSFERASE AND XANTHINE OXIDASE ACTIVITY IN HEALTHY VOLUNTEERS

• 1 Quercetin, one of the most abundant natural flavonoids, has been reported to modulate the activity of several drug‐metabolising enzymes. The aim of the present study was to investigate the effects of quercetin on cytochrome P450 (CYP) 1A2, CYP2A6, N‐acetyltransferase (NAT2) and xanthine oxidase (XO) activity in healthy volunteers using caffeine as a probe drug.
• 2 Twelve unrelated, healthy volunteers were recruited to the study. There were two phases to the study; in the first phase, each subject was given a single oral dose of caffeine (one 100 mg capsule) with 150 mL water; in the second phase, each subject was give a 500 mg quercetin capsule once daily for 13 continuous days and was coadministered a 100 mg caffeine capsule on the 13th day. Urinary caffeine metabolite ratios were used as indicators of the activity of CYP1A2, CYP2A6, NAT2 and XO. The pharmacokinetics of caffeine and its metabolites were determined by HPLC.
• 3 In the quercetin‐treated group, CYP1A2 activity was decreased by 10.4% (95% confidence interval (CI), 1.1–29.8%; P = 0.039), whereas increases were observed in CYP2A6 (by 25.3%; 95% CI, 6.2–34.5%; P = 0.002), NAT2 (by 88.7%; 95% CI, 7.1–160.2%; P = 0.010) and XO activity (by 15.0%; 95% CI, 1.6–21.6%; P = 0.007). Plasma C_max and the AUC_(0–24 h) of 1,7‐dimethylxanthine were decreased by 17.2% (95% CI, 6.4–28.0%; P = 0.024) and 16.2% (95% CI, 3.9–28.5%; P = 0.032), respectively. The urinary excretion of 1,7‐dimethylxanthine and 1‐methylxanthine was significantly decreased by 32.4% (95% CI, 2.5–62.1%; P = 0.036) and 156.1% (95% CI, 53.3–258.9%; P = 0.004), respectively. The urinary excretion of 1,7‐dimethylurate and 1‐methylurate was increased by 82.9% (95% CI, 56.0–165.4%; P = 0.030) and 97.8% (95% CI, 12.1–183.5%; P = 0.029), respectively. No changes were observed in the urinary excretion of caffeine and 5‐acetylamino‐6‐formylamino‐3‐methyluracil between the two study phases.
• 4 The results of the present study indicate that quercetin inhibits CYP1A2 function, but enhances CYP2A6, NAT2 and XO activity. Simultaneously, some pharmacokinetic parameters relating to 1,7‐dimethylxanthine were affected by quercetin. Thus, we conclude that quercetin affects CYP1A2, CYP2A6, NAT2 and XO activity in vivo.

     

Pseudocholinesterase-Activity Reduction during Cardiopulmonary Bypass: The Role of Dilutional Processes and Pharmacological Agents

• 1.Pseudocholinesterase (ChE) activity is a determinant of the elimination kinetics of several drugs used in anesthesia. The time course of ChE activity was investigated in 16 patients under-going cardiosurgery for a cardiopulmonary bypass (CPB) in normothermia or hypothermia.
• 2.The onset of the CPB was accompanied by a decrease in ChE activity (−37%) (P<0.05) and protein concentration (−24%) (P<0.05). The quotient ChE activity/protein concentration was numerically reduced to a smaller extent (−15%) (P>0.05). After the CPB was finished, ChE activity and the protein concentration remained low for the remaining operation time.
• 3.There was no difference in ChE activity, measured in vitro at 37°C, between the normothermic and hypothermic group (P>0.05).
• 4.There was no correlation between heparin concentration in serum and reduction of ChE activity in vitro (P>0.05). In vitro, the ChE activity was not affected by either heparin in doses as high as 10,000 U/ml or aprotinin in doses as high as 10,000 U/ml (P>0.05).
• 5.Conclusions: (1) ChE activity is reduced by CPB mainly by hemodilution and (2) the pharmacological agents used in the present anesthetic technique (heparin, aprotinin, midazolam, fentanyl, propofol and mivacurium) do not inhibit ChE activity at therapeutic serum concentrations.

     

蛇毒血凝酶联合缩宫素治疗高龄产妇剖宫产术后出血的临床研究

目的探讨蛇毒血凝酶联合缩宫素治疗高龄产妇剖宫产术后出血的临床疗效。方法选取2016年1月—2018年4月宜昌市第二人民医院收治的剖宫产术后出血的高龄产妇376例,随机分为对照组和治疗组,每组各188例。对照组在胎儿娩出后立即向切口上方的子宫肌壁注射缩宫素注射液20 U,然后将20 U缩宫素注射液加入0.9%氯化钠注射液250 mL中,静脉滴注,以后每天静脉滴注缩宫素20U。治疗组在对照组的基础上在胎儿娩出后立即向切口上方的子宫肌壁注射蛇毒血凝酶注射液1 U,以后每天肌肉注射蛇毒血凝酶注射液1 U,两组均连续治疗3 d。观察两组患者的临床疗效,同时比较两组患者的产后出血率、出血量、第三产程时间、恶露持续时间、住院时间、子宫底高度、D-二聚体、血红蛋白(Hb)、血浆纤维蛋白原(FIB)水平发生情况。结果治疗后,对照组和治疗组的总有效率分别是77.13%、89.36%,两组比较差异具有统计学意义(P0.05)。治疗后,治疗组产后出血率、出血量、第三产程时间、恶露持续时间、住院时间、子宫底高度均显著小于对照组,两组比较差异具有统计学意义(P0.05)。治疗后,两组D-二聚体、Hb、FIB水平均显著降低,同组治疗前后比较差异具有统计学意义(P0.05);且治疗后治疗组D-二聚体、Hb、FIB水平明显低于对照组,两组比较差异具有统计学意义(P0.05)。结论蛇毒血凝酶联合缩宫素治疗剖宫产术后出血具有较好的临床疗效,可显著降低术中及术后出血量和出血率,缩短第三产程时间、恶露持续时间,促进子宫复旧。     

Salivary clearance and urinary metabolic pattern of caffeine in healthy children and in pediatric patients with hepatocellular diseases

Measurement of salivary clearance and urinary metabolites of caffeine is an excellent noninvasive tool for assessing liver function, particularly the activity of cytochrome P4501A2 (CYP1A2), N-acetyltransferase (NAT), and xanthine oxidase (XO). This study was undertaken to measure the clearance of caffeine using saliva as a biological fluid and to assess the activities of the above-mentioned enzymes in healthy children and pediatric patients with liver diseases using urinary molar ratios of different caffeine metabolites. The well-established two-sample saliva approach was used to measure the clearance of caffeine in nine pediatric patients with liver diseases (LD) and in nine healthy children. The caffeine metabolites were also measured in the urine of these subjects by high-performance liquid chromatography, and urinary molar ratios of 5-acetylamino-6-formylamino-3-methyluracil (AFMU), 1-methylxanthine (1X), 1-methyluric acid (1U), and 1,7-dimethyluric acid (17U) were employed to estimate the activities of CYP1A2, NAT, and XO. The caffeine salivary clearance and the percentage of the dose excreted in the form of various metabolites were significantly (p < 0.035) smaller in the LD patients than those in healthy children. The urinary molar ratio of [AFMU + 1U + 1X]/17U, which reflects the activity of CYP1A2, was also significantly (p < 0.0005) reduced in these patients. However, there were no significant differences between the two groups in the ratios of AFMU/1X and 1U/1X, which estimate the activities of NAT and XO, respectively. In conclusion, the data obtained suggest that liver disease in pediatric subjects significantly reduces the salivary clearance of caffeine and the activity of cytochrome P4501A2, but it has no impact on the activities of NAT and XO.     

Safety,efficacy, and cost-effectiveness of insulin degludec U100 versus insulin glargine U300 in adults with type 1 diabetes: a systematic review and indirect treatment comparison

Background: Clinical differences between degludec U100 (Deg-100) and glargine U300 (Gla-300) in type 1 diabetes (T1D) were unknown. Aim: To indirectly compare the safety, efficacy, and cost-effectiveness between Deg-100 and Gla-300 in T1D adults via systematic review. Method: Medline, the Cochrane Library, ClinicalTrials.gov, and Google Scholar were searched (October 2021). Randomized controlled trials comparing Deg-100 or Gla-300 vs. glargine U100 in T1D adults (follow-up?≥?12 weeks) were selected and analyzed using a frequentist network meta-analysis. Cost-effectiveness analysis (CEA) was conducted over a 1-year time horizon from societal perspectives. Results: Nine trials were included. Efficacy analysis suggested that Deg-100 was non-inferior to Gla-300 in reducing HbA_1c (MD 0.03 [95% CI???0.09 to 0.15]; P?=?0.60), FPG (MD???1.12 [??2.19 to???0.04]; P?=?0.04), and pre-breakfast SMBG (MD???0.71 [??1.46 to 0.03]; P?=?0.06). Safety analysis suggested that Deg-100 appeared to have lower rates of both severe (HR 0.44 [0.25–0.78]; P?=?0.005) and nocturnal severe (HR 0.19 [0.08–0.44]; P?<?0.001) hypoglycemia, with lower total (MD???0.07 [??0.13 to???0.01]; P?=?0.02) and basal (MD???0.08 [??0.12 to???0.04]; P?<?0.001) insulin doses compared with Gla-300. No significant differences were observed for other hypoglycemia outcomes, adverse events, serious adverse events, bolus insulin dose, and body weight. The CEA showed that Deg-100 appeared to be a dominant treatment in Japan (+?0.0283 QALYs, ¥26,266 [$228] per patient) and the United States (+?0.0267 QALYs, $986 per patient). Conclusion: Low-certainty indirect evidence suggested that Deg-100 appeared to have a favorable reduction in rates of severe hypoglycemia and more cost-effective compared with Gla-300 in T1D adults.

     

Clinical and polysomnographic effects of trazodone CR in chronic insomnia associated with dysthymia

Six middle aged subjects complaining of chronic insomnia associated with dysthymia were investigated in a 2-month single blind study: a 7-day placebo treatment period, followed by a 6-week phase with increasing doses of trazodone controlled release (CR) formulation (50 mg through days 8–10; 75 mg through days 11–13; 150 mg through days 14–49) and then a final 7-day withdrawal period under placebo. Medication was always administered at bedtime. Five polysomnographic recordings were accomplished by each subject (sleep 1: under baseline placebo; sleep 2-3-4: under active treatment; sleep 5: after drug discontinuation). A blind EEG reader analysed the traditional polysomnographic variables (macrostructure of sleep) and the amount and percentage ratio (CAP rate) of cyclic alternating pattern (CAP), the microstructural parameter that measures the instability of arousal during sleep. Visual analogue scales (VAS) for the evaluation of subjective sleep quality and the Hamilton rating scale for depression (HAM-D) were regularly assessed across the study. Statistical analysis was based on an ANOVA test with repeated measures completed by means of Bonferroni adjusted probabilities. No significant differences emerged from the macrostructural parameters referred to sleep initiation and maintenance, while significant overall modifications emerged from stage 2 (P<0.0005), slow wave sleep (P<0.0001), total CAP time (P<0.0001) and CAP rate (P<0.0001). Compared to the placebo baseline night, a significant increase of slow wave sleep (+40 min) and significant reductions of stage 2 (–67 min), CAP time (–90 min) and CAP rate (–23%) were already found on day 4 of treatment (sleep 2). These changes maintained significance throughout the active treatment period (sleep 3 and sleep 4), while a return to the baseline values occurred after drug discontinuation (sleep 5). The course of polysomnographic modifications was consistently associated with significant improvement of VAS and HAM-D scores during the active treatment period and by poor scores of the baseline and withdrawal periods. Trazodone appears to have a high affinity for 5-HT₂ receptors. The availability of an effective slow acting serotonin-related drug with both sedative and antidepressant properties may open new perspectives in the treatment of chronic insomnia.     

Altered xanthine oxidase and N-acetyltransferase activity in obese children

AIMS

It is well established that oxidative and conjugative enzyme activity differs between obese and healthy-weight adults. However, the effect of obesity on drug metabolism in children has not been studied extensively. This study examined whether obese and healthy-weight children vary with respect to oxidative enzyme activity of CYP1A2, xanthine oxidase (XO) and conjugative enzyme activity of N-acetyltransferase 2 (NAT2).

METHODS

In vivo CYP1A2, XO and NAT2 activity was assessed in obese (n = 9) and lean (n = 16) children between the ages of 6–10 years using caffeine (118.3 ml Coca Cola®) as probe. Urine samples were collected in 2-h increments over 8 h. Caffeine and metabolites were measured using LC/MS, and urinary metabolic ratios were determined based on reported methods.

RESULTS

Sixteen healthy-weight and nine obese children were evaluated. XO activity was elevated in paediatric obese volunteers compared with non-obese paediatric volunteers (XO metabolic ratio of 0.7 ± 0.06 vs. 0.6 ± 0.06, respectively, 95% CI 0.046, 0.154, P < 0.001). NAT2 activity was fivefold higher in the obese (1 ± 0.4) as compared with non-obese children (0.2 ± 0.1), 95% CI 0.26, 1.34, P < 0.05. However, no difference was observed in CYP1A2 activity between the groups (95% CI −2.72, 0.12, P > 0.05).

CONCLUSIONS

This study provides evidence that obese children have elevated XO and NAT2 enzyme activity when compared with healthy-weight controls. Further studies are needed to determine how this may impact the efficacy of therapeutic agents that may undergo metabolism by these enzymes.     

Trichloroethylene exposure in vapour degreasing and the urinary excretion of N-acetyl-β-d-glucosaminidase

In order to elucidate the potential nephrotoxicity of low level occupational exposure to trichloroethylene (TRI), urine analysis of the tubular enzyme N-acetyl--dglucosaminidase (U-NAG) was included in a cross-sectional study of metal degreasers in central Sweden. Eightysix percent of 8-h TRI in air measurements were well below 50 mg/m³. Normal levels of NAG were found in morning urine samples from 29 workers compared to a historical reference group. A weak positive correlation (r = 0.48;P <0.01) was observed between U-NAG activity and the concentration of the TRI metabolite trichloroacetic acid in urine but not with other estimates of recent or long-term exposure. In conclusion, TRI does not seem to be nephrotoxic at low exposure levels.