Decreased Hepatic Functional Reserve Increases the Risk of Piperacillin/Tazobactam-Induced Abnormal Liver Enzyme Levels: A Retrospective Case-Control Study.

BACKGROUND: Piperacillin/tazobactam (PIPC/TAZ), which is a combination of a beta-lactam/beta-lactamase inhibitor, often causes liver enzyme abnormalities. The albumin-bilirubin (ALBI) score is a simple index that uses the serum albumin and total bilirubin levels for estimating hepatic functional reserve. Although patients with low hepatic reserve may be at high risk for drug-induced liver enzyme abnormalities, the relationship between PIPC/TAZ-induced abnormal liver enzymes levels and the ALBI score remains unknown. OBJECTIVE: This study aimed to elucidate the relationship between PIPC/TAZ-induced abnormal liver enzyme levels and the ALBI score. METHODS: This single-center retrospective case-control study included 335 patients. The primary outcome was PIPC/TAZ-induced abnormal liver enzyme levels. We performed COX regression analysis with male gender, age (≥75 years), alanine aminotransferase level (≥20 IU/L), and ALBI score (≥-2.00) as explanatory factors. To investigate the influence of the ALBI score on the development of abnormal liver enzyme levels, 1:1 propensity score matching between the ≤-2.00 and ≥-2.00 ALBI score groups was performed using the risk factors for drug-induced abnormal liver enzyme levels. RESULTS: The incidence of abnormal liver enzyme levels was 14.0% (47/335). COX regression analysis revealed that an ALBI score ≥-2.00 was an independent risk factor for PIPC/TAZ-induced abnormal liver enzyme levels (adjusted hazard ratio: 3.08, 95% coefficient interval: 1.207-7.835, P = 0.019). After 1:1 propensity score matching, the Kaplan-Meier curve revealed that the cumulative risk for PIPC/TAZ-induced abnormal liver enzyme levels was significantly higher in the ALBI score ≥-2.00 group (n = 76) than in the <-2.00 group (n = 76) (P = 0.033). CONCLUSION AND RELEVANCE: An ALBI score ≥-2.00 may predict the development of PIPC/TAZ-induced abnormal liver enzyme levels. Therefore, frequent monitoring of liver enzymes should be conducted to minimize the risk of severe PIPC/TAZ-induced abnormal liver enzyme levels in patients with low hepatic functional reserve.

A decision tree model for predicting high mono-N-desethylamiodarone concentrations and reducing tissue toxicity in patients with low-dose amiodarone therapy: A multicentral retrospective cohort study.

OBJECTIVE: High plasma levels of mono-N-desethylamiodarone (MDEA), an active amiodarone metabolite, may be associated with tissue toxicity in heart failure (patients with heart rhythm disturbances); therefore, a tool that can identify patients for whom therapeutic drug monitoring (TDM) of MDEA is required. This multicenter study aimed to develop a decision tree (DT) model that can identify patients with heart rhythm disturbances at high MDEA concentrations. MATERIALS AND METHODS: A multicenter retrospective cohort study was conducted, including 157 adult patients with heart failure who received oral amiodarone treatment. A χ2 automatic interaction-detection algorithm was used to construct a DT model. In the DT analysis, the dependent variable was set as an MDEA trough plasma concentration of ≥ 0.6 µg/mL during the steady-state period. Explanatory variables were selected as factors with p < 0.05 in multivariate logistic regression analysis. RESULTS: The adjusted odds ratios for the daily dose of amiodarone and body mass index were 1.01 (95% coefficient interval: 1.008 - 1.021, p < 0.001) and 0.91 (95% confidence interval: 0.834 - 0.988, p = 0.025), respectively. For DT analysis, the risk of reaching plasma MDEA concentrations ≥ 0.6 µg/mL was relatively high, combined with a daily dose of amiodarone > 100 mg and body mass index ≤ 22.3 kg/m2 at 69.0% (20/29), and its trend was also detected in the sensitivity analysis. CONCLUSION: Patients taking a daily amiodarone dose > 100 mg and with a body mass index ≤ 22.3 kg/m2 warrant TDM implementation for MDEA to minimize the risk of MDEA-induced tissue toxicity.

Effect of Ceftriaxone Dosage and Albumin-Bilirubin Score on the Risk of Ceftriaxone-Induced Liver Injury.

The albumin-bilirubin (ALBI) score is an index of hepatic functional reserve and is calculated from serum albumin and total bilirubin levels. However, the relationship between ceftriaxone (CTRX)-induced liver injury and ALBI score remains unknown. Therefore, we aimed to elucidate the risk of CTRX-induced liver injury based on the ALBI scores and CTRX dosage. This was a single-center, retrospective, case-control study of 490 patients and the primary outcome was CTRX-induced liver injury. We performed a COX regression analysis using age ≥75 years, male sex, alanine aminotransferase levels, ALBI score, and CTRX dosage regimen (4 ≥2 or 1 g/d) as explanatory factors. We also performed 1 : 1 propensity score matching between non-liver injury and liver injury groups. The incidence of liver injury was 10.0% (49/490). In COX regression analysis, CTRX 4 g/d was an independent risk factor for liver injury (95% coefficient interval: 1.05-6.96, p = 0.04). Meanwhile, ALBI score ≥-1.61 was an independent factor for liver injury (95% coefficient interval: 1.03-3.22, p = 0.04) with the explanatory factor of ≥2 and 1 g/d. The Kaplan-Meier curve indicated that the cumulative risk for CTRX-induced liver injury was significantly higher in the ALBI score ≥-1.61 group than in the ALBI score <-1.61 group before propensity score matching (p = 0.032); however, no significant differences were observed after propensity score matching (p = 0.791). These findings suggest that in patients treated with CTRX with ALBI score ≥-1.61, frequent liver function monitoring should be considered.

Machine Learning-Based Prediction of Digoxin Toxicity in Heart Failure: A Multicenter Retrospective Study.

Digoxin toxicity (plasma digoxin concentration ≥0.9 ng/mL) is associated with worsening heart failure (HF). Decision tree (DT) analysis, a machine learning method, has a flowchart-like model where users can easily predict the risk of adverse drug reactions. The present study aimed to construct a flowchart using DT analysis that can be used by medical staff to predict digoxin toxicity. We conducted a multicenter retrospective study involving 333 adult patients with HF who received oral digoxin treatment. In this study, we employed a chi-squared automatic interaction detection algorithm to construct DT models. The dependent variable was set as the plasma digoxin concentration (≥ 0.9 ng/mL) in the trough during the steady state, and factors with p < 0.2 in the univariate analysis were set as the explanatory variables. Multivariate logistic regression analysis was conducted to validate the DT model. The accuracy and misclassification rates of the model were evaluated. In the DT analysis, patients with creatinine clearance <32 mL/min, daily digoxin dose ≥1.6 µg/kg, and left ventricular ejection fraction ≥50% showed a high incidence of digoxin toxicity (91.8%; 45/49). Multivariate logistic regression analysis revealed that creatinine clearance <32 mL/min and daily digoxin dose ≥1.6 µg/kg were independent risk factors. The accuracy and misclassification rates of the DT model were 88.2 and 46.2 ± 2.7%, respectively. Although the flowchart created in this study needs further validation, it is straightforward and potentially useful for medical staff in determining the initial dose of digoxin in patients with HF.

Risk evaluation of ampicillin/sulbactam-induced liver injury based on albumin-bilirubin score.

BACKGROUND: Drug-induced liver injury (DILI) is an adverse reaction caused by ampicillin/sulbactam (ABPC/SBT). The albumin-bilirubin (ALBI) score is an index of hepatic functional reserve. However, the relationship between ABPC/SBT-induced DILI and ALBI score remains unknown; therefore, we aimed to elucidate the risk of ABPC/SBT-induced DILI based on the ALBI score. METHODS: This was a single-center, retrospective, case-control study using electronic medical records. A total of 380 patients were enrolled in the present study, and the primary outcome was ABPC/SBT-induced DILI. The ALBI score was calculated using serum albumin and total bilirubin levels. In addition, we performed COX regression analysis using age ≥75 years, dose ≥9 g/day, alanine aminotransferase (ALT) ≥21 IU/L, and ALBI score ≥-2.00 as covariates. We also performed 1:1 propensity score matching between non-DILI and DILI groups. RESULTS: The incidence of DILI was 9.5% (36/380). According to COX regression analysis, the adjusted hazard ratio for ABPC/SBT-induced DILI with an ALBI score ≥-2.00 was 2.55 (95% confidence interval: 1.256-5.191, P = 0.010), suggesting that patients with baseline ALBI score ≥-2.00 may be at high risk for ABPC/SBT-induced DILI. However, significant differences were not observed in cumulative risk for DILI between non-DILI and DILI patients regarding an ALBI score ≥-2.00 after propensity score matching (P = 0.146). CONCLUSION: These findings suggest that ALBI score may be a simple and potentially useful index for predicting ABPC/SBT-induced DILI. In patients with an ALBI score ≥-2.00, frequent liver function monitoring should be considered to prevent ABPC/SBT-induced DILI.

Risk evaluation of carbapenem-induced liver injury based on machine learning analysis.

INTRODUCTION: Information regarding carbapenem-induced liver injury is limited, and the rate of liver injury caused by meropenem (MEPM) and doripenem (DRPM) remains unknown. Decision tree (DT) analysis, a machine learning method, has a flowchart-like model where users can easily predict the risk of liver injury. Thus, we aimed to compare the rate of liver injury between MEPM and DRPM and construct a flowchart that can be used to predict carbapenem-induced liver injury. METHODS: We investigated patients treated with MEPM (n = 310) or DRPM (n = 320) and confirmed liver injury as the primary outcome. We used a chi-square automatic interaction detection algorithm to construct DT models. The dependent variable was set as liver injury from a carbapenem (MEPM or DRPM), and factors including alanine aminotransferase (ALT), albumin-bilirubin (ALBI) score, and concomitant use of acetaminophen were used as explanatory variables. RESULTS: The rates of liver injury were 22.9% (71/310) and 17.5% (56/320) in the MEPM and DRPM groups, respectively; no significant differences in the rate were observed (95% confidence interval: 0.710-1.017). Although the DT model of MEPM could not be constructed, DT analysis showed that the incidence of introducing DRPM in patients with ALT >22 IU/L and ALBI scores > -1.87 might be high-risk. CONCLUSIONS: The risk of developing liver injury did not differ significantly between the MEPM and DRPM groups. Since ALT and ALBI score are evaluated in clinical settings, this DT model is convenient and potentially useful for medical staff in assessing liver injury before DRPM administration.

Impact of antimicrobial stewardship program-driven educational intervention for vancomycin loading dose on mortality.

BACKGROUND: Although the loading dose (LD) of vancomycin (VCM) contributes to its efficacy, it may not be conducted adequately. Herein, the objective was to evaluate the effect of LD on patient prognosis using therapeutic drug monitoring by pharmacists and elucidate the impact of an antimicrobial stewardship program (ASP)-driven educational intervention on the LD implementation rate and patient prognosis. MATERIALS AND METHODS: First, a retrospective cohort study was conducted involving 121 adult patients administered with VCM and compared with 28-day mortality in LD and non-LD groups. To avoid confounding, the propensity score method was employed. Second, post-training with ASP-driven lectures, a questionnaire survey was conducted for healthcare workers, including physicians, nurses, and pharmacists. The rates of VCM LD implementation and 28-day mortality were compared during a period of one year and 9 months between the pre-ASP (n = 38) and post-ASP (n = 33) groups. RESULTS: After propensity score matching, the 28-day mortality in the LD group was significantly improved, suggesting that the early increase in blood levels of VCM due to an LD is an important factor influencing patient prognosis. After the lecture, a questionnaire survey revealed that the understanding rates of "well" and "slightly well" for educational lectures exceeded 80% of all healthcare workers. The rate of LD implementation significantly increased to 63.6% (21/33) in the post-ASP group compared with 31.6% (12/38) in the pre-ASP group (p = 0.007), and the 28-day mortality declined from 23.7% (9/38) to 6.1% (2/33) (p = 0.041). CONCLUSION: This method of ASP-driven educational intervention would facilitate LD implementation, improving patient prognosis.

Distinct effects of orexin A on spontaneous and evoked synaptic currents in the rat nucleus tractus solitarius.

Orexins are produced in hypothalamic areas and orexin-containing neurons are distributed in widespread areas of the central nervous system. Orexins regulate several physiological functions such as arousal, food intake and autonomic control. The presence of orexin-containing neuron terminals and orexin receptors has been confirmed in the nucleus tractus solitarius (NTS), which receives primary afferent fibers from peripheral organs including baroreceptors. However, the neuronal effects of orexin-1 receptor (OX1R) activation were not examined. Here, we aimed to determine the effects of OX1R activation on excitatory synaptic transmission. OX1R activation increased the frequency of spontaneous excitatory synaptic currents (sEPSCs). This effect was blocked by the prior application of L-NAME. In contrast, the amplitude of evoked excitatory postsynaptic currents (eEPSCs) was suppressed by OX1R activation, and this effect was prevented by a cannabinoid receptor 1 blocker, AM251, but not by the pretreatment with L-NAME. Altogether, these results suggest that OX1R activation increases sEPSCs frequency by stimulating NO production, whereas it inhibits eEPSCs by releasing endocannabinoids in the NTS. Thus, OX1R activation had distinct effects on spontaneous and evoked excitatory synaptic transmissions in the NTS.

The Effect of Single-Walled Carbon Nanotubes on UDP-Glucuronosyltransferase 1A Activity in Human Liver.

Single-walled carbon nanotubes (SWCNTs) are made from rolled single graphene sheets with a diameter in the nanometer range and are potential carriers for drug delivery systems. However, their effects on uridine 5'-diphosphate-glucuronosyltransferase (UGT) 1A activities remain unclear. The present study aimed to investigate the effect of two kinds of SWCNTs (EC1.5-P- and FH-P-SWCNTs) and other nanocarbons on human UGT1A activity due to the proposed application of SWCNTs in drug and gene delivery. ß-Estradiol 3-glucuronidation, which is catalyzed mainly by UGT1A1, was inhibited by 99 and 76% in the presence of 0.1 mg/mL EC1.5-P- and FH-P-SWCNTs in human liver microsomes, respectively. The observed decrease of free UGT1A1 protein in the enzyme reaction mixture suggests a higher interaction with SWCNTs, and indicates the inhibition of ß-estradiol 3-glucuronidation. Imipramine N-glucuronidation, which is formed mainly by UGT1A4, was also decreased by SWCNTs. Serotonin glucuronidation, which is mainly responsible for UGT1A6, was only influenced by specific nanocarbons in human liver microsomes. The attenuation of free UGT1A6 protein was observed with SWCNTs and carbon black, indicating that UGT1A6 activity was not influenced by the direct interaction of SWCNTs. We also observed a 127% increase by FH-P-SWCNTs for propofol glucuronidation in human liver microsomes, which is catalyzed mainly by UGT1A9. The values of maximum velocity and intrinsic clearance for propofol glucuronidation in the presence of FH-P-SWCNT were 1.8- and 2.0-fold higher than those of the control in human liver microsomes. These results suggest that the effects of SWCNTs on UGT1A are different among isoforms.

Risk assessment of micafungin-induced liver injury using spontaneous reporting system data and electronic medical records.

INTRODUCTION: There is limited information regarding antifungal-induced liver injuries, which have high mortality rates. Therefore, we used the Japanese Adverse Drug Event Report (JADER) database for signal detection associated with antifungal-induced liver injuries and medical records for risk assessment. METHODS: Reports of antifungal-induced liver injuries from JADER data were analyzed to calculate the reporting odds ratio (ROR) and 95% confidence interval (CI). A medical record-based study involving 109 adult patients treated with micafungin shows liver injury as the primary outcome in patients treated with micafungin. The albumin-bilirubin (ALBI) score was calculated based on albumin and total bilirubin levels. We selected five explanatory factors for multivariable logistic regression: alanine aminotransferase ≥20 IU/L, alkaline phosphatase ≥372 IU/L, aspartate aminotransferase ≥25 IU/L, ALBI score ≥ -1.290, and age ≥65 years. RESULTS: Signal detection for micafungin was observed in both, hepatocellular and cholestatic injuries, as per data from JADER. Univariate analyses performed on medical records suggest that alanine aminotransferase (p = 0.008), aspartate aminotransferase (p = 0.036), alkaline phosphatase (p = 0.045), and ALBI score (p = 0.028) may be factors associated with micafungin-induced liver injury. Based on multivariable logistic regression, the adjusted odds ratio for micafungin-induced liver injury in patients with ALBI score ≥ -1.290 was 2.78 (95% CI: 1.014-7.605, p = 0.047), suggesting that low hepatic functional reserve could be a risk factor for micafungin-induced liver injury. CONCLUSIONS: Careful monitoring of liver function may be necessary for micafungin administration in patients with low hepatic functional reserve.

Changes in uridine 5'-diphospho-glucuronosyltransferase 1A6 expression by histone deacetylase inhibitor valproic acid.

Valproic acid (VPA) is well-known as a histone deacetylase (HDAC) inhibitor. It has been reported that HDAC inhibitors enhance basal and aryl hydrocarbon receptor (AhR) ligand-induced aryl hydrocarbon receptor-responsive gene expression. Other studies suggested that HDAC inhibition might significantly activate the NF-E2-related factor-2 (Nrf2). Moreover, VPA activates mitogen-activated protein kinases (MAPKs). MAPK pathways regulate Nrf2 transactivation domain activity. Uridine 5'-diphospho-glucuronosyltransferase (UGT) 1A6 is one of the important isoforms to affect drug pharmacokinetics. UGT1A6 gene is regulated transcriptionally by AhR and Nrf2. The present study aimed to investigate whether UGT1A6 expression was changed by VPA and to elucidate the mechanism of the alteration. Following VPA treatment for 72 h in Caco-2 cells, UGT1A6 mRNA was increased by 7.9-fold. Moreover, UGT1A6 mRNA was increased by other HDAC inhibitors, suggesting that HDAC inhibition caused the UGT1A6 mRNA induction. AhR and Nrf2 proteins in the nucleus of Caco-2 cells were increased by 1.5- and 1.7-fold, respectively, following the VPA treatment. However, VPA treatment did not activate the extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) pathways in Caco-2 cells. In conclusion, we observed that VPA induced UGT1A6 mRNA expression via AhR and Nrf2 pathways, but not via the ERK or JNK pathways.

Combining maintenance therapy with hydroxychloroquine increases LLDAS achievement rates in individuals with stable systemic lupus erythematosus.

BACKGROUND: Hydroxychloroquine (HCQ) has been positioned as an anchor drug for systemic lupus erythematosus (SLE). There is evidence supporting the benefits of HCQ; however, the effect of additional HCQ in maintenance therapy remains unclear. METHODS: Thirty patients with SLE who visited Juntendo University Hospital were receiving maintenance therapy before HCQ treatment and were able to complete more than 104 weeks of HCQ treatment were analyzed. Anti-DNA antibody titers, IgG and CH50 levels, the maintenance dose of corticosteroids, the SLE disease activity index (SLEDAI), and the achievement of the Lupus Low Disease Activity State (LLDAS) were evaluated at baseline and at 12, 24, 52, and 104 weeks after HCQ initiation. RESULTS: We observed improvements in the anti-DNA antibody titers, IgG and CH50 levels, maintenance dose of corticosteroids, and SLEDAI at week 104 relative to baseline. Moreover, the LLDAS achievement rate increased over time from 10% at baseline to 43% and 80% at week 52 and week 104, respectively. CONCLUSION: Two years of continuous HCQ treatment led to improvements in SLE disease activity and corticosteroid dose and an increase in LLDAS achievement, thereby demonstrating the significance of the maintenance dose of HCQ for the management of SLE.

Evaluation of the Expression Profile of Antibiotic-Induced Thrombocytopenia Using the Japanese Adverse Drug Event Report Database.

Drug-induced thrombocytopenia (DITP) can be triggered by antibiotics; however, the details remain unclear. Here, we evaluated the expression profiles of DITP using the Japanese Adverse Drug Event Report (JADER) database. We analyzed reports of DITP between April 2004 and January 2021 from the JADER database. The reporting odds ratio (ROR) and 95% confidence interval (CI) were used to detect DITP signals. Factors thought to affect DITP, such as male sex and an age of at least 60 years, were added as covariates. We evaluated the time-to-onset profile and hazard type using the Weibull shape parameter. The JADER database contained 1,048,576 reports. Twelve of 60 antibiotics showed signals for DITP; the RORs (95% CIs) for ampicillin/sulbactam, ceftazidime, cefozopran, ciprofloxacin, fluconazole, fos-fluconazole, linezolid, pazufloxacin, piperacillin/tazobactam, teicoplanin, trimethoprim/sulfamethoxazole, and voriconazole were 1.75 (1.41-2.16), 1.77 (1.42-2.18), 1.35 (1.06-1.72), 2.56 (2.19-2.98), 1.93 (1.67-2.23), 2.08 (1.76-2.46), 5.29 (2.73-9.60), 1.92 (1.51-2.41), 1.54 (1.05-2.19), 1.47 (1.16-1.84), 1.92 (1.73-2.14), and 2.32 (1.59-3.30), respectively. In multiple logistic regression analysis, 7 and 6 antibiotics were detected for the factors age and male sex, respectively. The median times-to-onset of DITP for ciprofloxacin (oral treatment), fluconazole, linezolid, piperacillin/tazobactam, and trimethoprim/sulfamethoxazole were 91, 91, 11.5, 10, and 9 days, respectively. Furthermore, the 95% CI of the Weibull shape parameter ß for these antibiotics was above and excluded 1, indicating that the antibiotics were the wear out failure type. We revealed the expression profiles of DITP following treatment with 12 antibiotics.

Expression and activities of sulfotransferase in rat brain.

Sulfotransferase (SULT) has been found in the brain; however, the details of its function remain unclear. The present study aimed to elucidate the regional differences in the expression of SULT1 and SULT2 mRNA and SULT activities in the eight functional regions of the rat brain (cerebellum, cortex, hippocampus, medulla oblongata, midbrain, olfactory bulb, striatum, and thalamus). All SULT1 isoforms were detected in the medulla oblongata and thalamus. SULT2A1 mRNA was not observed in any of the eight regions, whereas SULT2B1a and SULT2B1b were found in all regions. The SULT2B1b mRNA expression level in the medulla oblongata was 1.7-fold higher than that in the liver. The sulfonation of p-nitrophenol and pregnenolone was detected in all regions. The kinetics of p-nitrophenol sulfonation in the cerebellum fitted to the substrate inhibition model (Km = 37.6 nM, Vmax = 2.72 pmol/min/mg, Vinh = 1.60 pmol/min/mg, and Ki = 0.87 µM). The pregnenolone sulfonation also exhibited substrate inhibition kinetics (Km = 0.99 µM, Vmax = 1.53 pmol/min/mg, and Ki = 54.67 µM). We clarified that SULT1 and SULT2 were expressed and had metabolizing capacities in the rat brain, suggesting that brain SULTs may be involved in metabolism of endogenous compounds and drugs.

Effect of status epilepticus on expression of brain UDP-glucuronosyltransferase 1a in rats.

Status epilepticus (SE) involves severe epileptic seizures that cause oxidative stress in the brain. Oxidative stress is known to influence uridine 5'-diposphate-glucuronosyltransferase (UGT) 1A expression. The present study aimed at elucidating the effect of SE on Ugt1a1, Ugt1a6 and Ugt1a7 expression in the rat brain. Kainic acid was used to create an animal model of SE. Sprague-Dawley rats were treated intraperitoneally with 10 mg/kg kainic acid. Ugt1a1 and Ugt1a7 mRNA levels were increased by SE in the cortex and hippocampus (Ugt1a1: 4.0- and 5.3-fold, respectively; Ugt1a7: 2.8- and 2.5-fold, respectively). Moreover, the induction degree of heme oxygenase-1 mRNA, an oxidative stress marker, was high in these regions, suggesting that oxidative stress could be involved in Ugt1a1 and Ugt1a7 induction. Ugt1a6 was elevated by 1.8-fold in the cortex in both SE and non-response (non-epileptic seizure response) rats, implying that Ugt1a6 induction may be independent from SE. An intraperitoneal single administration of 25 mg/kg diazepam (DZP) for the treatment of SE could attenuate heme oxygenase-1 induction in the cortex, whereas Ugt1a1 was decreased in the hippocampus, but not in the cortex, suggesting that there likely exists an alternative mechanism for Ugt1a1 reduction by DZP treatment. Continuous 14-day administration of DZP inhibited Ugt1a1 induction in the cortex, but did not have an effect on Ugt1a7 induction. This study indicated that SE altered the expression of brain Ugt1a1 and Ugt1a7, which could alter glucuronidation in the brain.

Effect of single-walled carbon nanotubes on cytochrome P450 activity in human liver microsomes in vitro.

Single-walled carbon nanotubes (SWCNTs) are made from a rolled single sheet of graphene with a diameter in the nanometer range. SWCNTs are potential carriers for drug delivery systems because antibodies or drugs can be loaded on their surface; however, their effect on the activities of cytochrome P450 (CYP) remains unclear. The aim of this study was to investigate the effect of two kinds of SWCNTs with different lengths (FH-P- and SO-SWCNTs) on human CYP activity. In addition, other nano-sized carbon materials, such as carbon black, fullerene-C60 , and fullerene-C70 were also evaluated to compare their effects on CYP activities. Ten CYP substrates (phenacetin, coumarin, bupropion, paclitaxel, tolbutamide, S-mephenytoin, dextromethorphan, chlorzoxazone, midazolam, and testosterone) were used. Testosterone 6ß-hydroxylation and midazolam 1'-hydroxylation, which are catalysed by both CYP3A4 and CYP3A5 in liver microsomes, were decreased by 25% and 45%, respectively, in the presence of 0.1 mg/ml SO-SWCNT. Dextromethorphan O-demethylation, which is catalysed mainly by CYP2D6, was decreased by 40% in the presence of SO-SWCNT. Other CYP activities, however, were not attenuated by SO-SWCNT. FH-P-SWCNT, carbon black, fullerene-C60 , and fullerene-C70 at 0.1 mg/ml had no effect on CYP activities. The Ki values for testosterone 6ß-hydroxylation, midazolam 1'-hydroxylation, and dextromethorphan O-demethylation in liver microsomes were 136, 34, and 56 µg/ml, respectively. SO-SWCNT was determined to be a competitive inhibitor of CYP3A4, CYP3A5, and CYP2D6. These results suggest that the effect of SO-SWCNT differs among CYP isoforms, and that the inhibition potency depends on the physicochemical properties of the nanocarbons.

Characterization of ß-Estradiol 3-Glucuronidation in Rat Brain.

ß-Estradiol is conjugated by uridine 5'-diphosphate-glucuronosyltransferase (UGT) 1A to 3-glucuronide in the human liver. UGT1A has been found in the brain; therefore, UGT1A may be involved in ß-estradiol 3-glucuronidation in the brain. In the present study, we aimed to characterize the ß-estradiol 3-glucuronidation reaction in the rat brain. ß-Estradiol 3-glucuronidation was detected in eight rat brain regions (cerebellum, frontal cortex, parietal cortex, piriform cortex, hippocampus, medulla oblongata, striatum, and thalamus). ß-Estradiol 3-glucuronidation in the cerebellum was fitted to the Hill equation (S50=8.0 µM, n=1.1). In inhibition experiments, ß-estradiol 3-glucuronidation was inhibited to 73.6% in the cerebellum by 50 µM bilirubin, whereas it was reduced to 20.5% with 5 µM bilirubin in the liver. Unlike in the liver, Ugt1a1 may not be the main isoform catalyzing this glucuronidation in the brain. Serotonin and acetaminophen at 10 mM inhibited glucuronidation to 1.17 and 25.5%, respectively, in the cerebellum. In induction experiments, the administration of ß-naphthoflavone, carbamazepine, and phenobarbital did not increase ß-estradiol 3-glucuronidation in the brain except for phenobarbital in the striatum. In addition, ß-estradiol 3-glucuronidation was not correlated with serotonin or acetaminophen glucuronidation in the brain, suggesting that Ugt1a6 and Ugt1a7 are not major isoforms of ß-estradiol 3-glucuronidation in the rat brain. In the present study, although we were unable to identify the isoform responsible for ß-estradiol 3-glucuronidation, we confirmed that ß-estradiol could be metabolized to glucuronide in the brain under a different metabolic profile from that in the liver.

Species and Tissue Differences in ß-Estradiol 17-Glucuronidation.

Uridine 5'-diphosphate-glucuronosyltransferase (UGT) is expressed in the liver and extrahepatic tissues. One of the major metabolic pathways of ß-estradiol (E2) is glucuronidation at the 17-hydroxy position by UGTs. This study was performed to determine E2 17-glucuronidation kinetics in human and rodent liver, small intestine, and kidney microsomes and to clarify the species and tissue differences. In the human liver and small intestine, Eadie-Hofstee plots exhibited biphasic kinetics, suggesting that E2 17-glucuronide (E17G) formation was catalyzed by more than two UGT isoforms in both tissues. The Km values for E17G formation by the high-affinity enzymes in the human liver and small intestine were 1.79 and 1.12 µM, respectively, and corresponding values for the low-affinity enzymes were 3.72 and 11.36 µM, respectively. Meanwhile, E17G formation in the human kidney was fitted to the Hill equation (S50=1.73 µM, n=1.63), implying that the UGT isoform catalyzing E17G formation in the kidney differed from that in the liver and small intestine. The maximum clearance for E17G formation in the human kidney was higher than the intrinsic clearance in the liver. E17G formation in the rat liver and kidney exhibited biphasic kinetics, whereas that in the small intestine was fitted to the Hill equation. In mice, all 3 tissues exhibited biphasic kinetics. In conclusion, we reported species and tissue differences in E2 17-glucuronidation, which occurred not only in the human liver but also in the extrahepatic tissues particularly the kidney.

Structural, optical, and transport properties of nanocrystalline bismuth telluride thin films treated with homogeneous electron beam irradiation and thermal annealing.

We investigated the effects of homogeneous electron beam (EB) irradiation and thermal annealing treatments on the structural, optical, and transport properties of bismuth telluride thin films. Bismuth telluride thin films were prepared by an RF magnetron sputtering method at room temperature. After deposition, the films were treated with homogeneous EB irradiation, thermal annealing, or a combination of both the treatments (two-step treatment). We employed Williamson-Hall analysis for separating the strain contribution from the crystallite domain contribution in the x-ray diffraction data of the films. We found that strain was induced in the thin films by EB irradiation and was relieved by thermal annealing. The crystal orientation along c-axis was significantly enhanced by the two-step treatment. Scanning electron microscopy indicated the melting and aggregation of nano-sized grains on the film surface by the two-step treatment. Optical analysis indicated that the interband transition of all the thin films was possibly of the indirect type, and that thermal annealing and two-step treatment methods increased the band gap of the films due to relaxation of the strain. Thermoelectric performance was significantly improved by the two-step treatment. The power factor reached a value of 17.2 µW (cm(-1) K(-2)), approximately 10 times higher than that of the as-deposited thin films. We conclude that improving the crystal orientation and relaxing the strain resulted in enhanced thermoelectric performance.

Expression of UGT1A subfamily in rat brain.

UDP-glucuronosyltransferase (UGT) is an enzyme that catalyses a major phase II reaction in drug metabolism. Glucuronidation occurs mainly in the liver, but UGTs are also expressed in extrahepatic tissues, where they play an important role in local metabolism. UGT1A isoforms catalyse the glucuronidation of several drugs, neurotransmitters and neurosteroids that exert pharmacological and physiological effects on the brain. The aim of the current study was to determine UGT1A mRNA expression levels and glucuronidation activities in different regions of the rat brain (namely the cerebellum, frontal cortex, parietal cortex, piriform cortex, hippocampus, medulla oblongata, olfactory bulb, striatum and thalamus). It was found that all UGT1A isoforms were expressed in all the nine regions, but their expression levels differed between the regions. The difference between the regions of the brain where the mRNA levels were highest and those where they were lowest ranged between 2.1- to 7.8-fold. Glucuronidation activities were measured using the UGT substrates such as mycophenolic acid, p-nitrophenol and umbelliferone. Glucuronidation activity was detected in all nine regions of the brain. Activity levels differed between the regions, and were highest in the cerebellum, medulla oblongata and olfactory bulb. Differences in glucuronidation activity between regions with the highest rates and those with the lowest rates ranged from 5.3- to 10.1-fold. These results will contribute to our current understanding of the physiological and pharmacokinetic roles of drug-metabolizing enzymes in the brain. Copyright © 2016 John Wiley & Sons, Ltd.