Xanthine oxidase and aldehyde oxidase contribute to allopurinol metabolism in rats.

BACKGROUND: Allopurinol is used to treat hyperuricemia and gout. It is metabolized to oxypurinol by xanthine oxidase (XO), and aldehyde oxidase (AO). Allopurinol and oxypurinol are potent XO inhibitors that reduce the plasma uric acid levels. Although oxypurinol levels show large inter-individual variations, high concentrations of oxypurinol can cause various adverse effects. Therefore, it is important to understand allopurinol metabolism by XO and AO. In this study we aimed to estimate the role of AO and XO in allopurinol metabolism by pre-administering Crl:CD and Jcl:SD rats, which have known strain differences in AO activity, with XO inhibitor febuxostat. METHODS: Allopurinol (30 or 100 mg/kg) was administered to Crl:CD and Jcl:SD rats with low and high AO activity, respectively, after pretreatment with or without febuxostat. The serum concentrations of allopurinol and oxypurinol were measured, and the area under the concentration-time curve (AUC) was calculated from the 48 h serum concentration-time profile. In vivo metabolic activity was measured as the ratio AUCoxypurinol /AUCallopurinol. RESULTS: Although no strain-specific differences were observed in the AUCoxypurinol/AUCallopurinol ratio in the allopurinol (30 mg/kg)-treated group, the ratio in Jcl:SD rats was higher than that in Crl:CD rats after febuxostat pretreatment. Contrastingly, the AUC ratio of allopurinol (100 mg/kg) was approximately 2-fold higher in Jcl:SD rats than that in Crl:CD rats. These findings showed that Jcl:SD rats had higher intrinsic AO activity than Crl:CD rats did. However, febuxostat pretreatment substantially decreased the activity, as measured by the AUC ratio using allopurinol (100 mg/kg), to 46 and 63% in Crl:CD rats and Jcl:SD rats, respectively, compared to the control group without febuxostat pretreatment. CONCLUSIONS: We elucidated the role of XO and AO in allopurinol metabolism in Crl:CD and Jcl:SD rats. Notably, AO can exert a proportionately greater impact on allopurinol metabolism at high allopurinol concentrations. AO's impact on allopurinol metabolism is meaningful enough that individual differences in AO may explain allopurinol toxicity events. Considering the inter-individual differences in AO activity, these findings can aid to dose adjustment of allopurinol to avoid potential adverse effects.

Molecular epidemiological and pharmaceutical studies of methicillin-resistant Staphylococcus aureus isolated at hospitals in Kure City, Japan.

Introduction: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the major pathogens of nosocomial infections throughout the world. In the medical field, it is extremely important to this pathogen's trends when considering infection control. Hypothesis/Gap Statement: We hypothesized that clarifying the characteristics of clinically isolated MRSA would contribute to infection control and proper use of antimicrobial agents against MRSA. Aim: The purpose of this study is to elucidate the genetic and biological characteristics of the MRSA isolates found at our hospital and to reveal changes in the spread of this pathogen in the local area where we live. Methodology: Pulse-field gel electrophoresis (PFGE) and polymerase chain reaction were used for the genetic analyses of MRSA isolates. Toxin production by each isolate was examined using toxin-specific detection systems. Results: During the 3 years from 2017 through 2019, over 1000 MRSA strains were isolated at our hospital. Genomic analysis of 237 of these clinical isolates by PFGE revealed 12 PFGE types (types A to L), each consisting of five or more MRSA clinical strains with over 80% genetic similarity. Examination of the SCCmec genotypes found that 219 of 237 isolated MRSA strains (approximately 92%) were SCCmec genotype II or IV and that only four of the isolates carried the Panton-Valentine leukocidin (PVL) gene. Examination of the toxin production of the isolates using staphylococcal enterotoxin detection kits found that most isolates carrying the SCCmec genotype II produced enterotoxin B and/or C, and that most isolates carrying the SCCmec genotype IV produced enterotoxin A. Conclusion: The present results revealed that MRSA isolates with common properties were isolated at certain rates throughout the 3 year study period, suggesting that relatively specific MRSA clones may have settled in the local area around our hospital. We also examine the relationship between antimicrobial usage over time and changes in MRSA isolation rates.

Developmental changes of aldehyde oxidase activity and protein expression in human liver cytosol.

Aldehyde oxidase (AO) plays a role in metabolizing many drugs, such as methotrexate and 6-mercaptopurine. We previously showed that AO activity in rat liver rapidly increases from birth, reaching a plateau within 4 weeks, and is regulated at the protein expression level. However, developmental changes of AO activity and protein expression in human liver have not been reported. Here, we investigated the developmental changes and variability of AO in 16 human livers (13 children ranging from 13 days to 12 years old and 3 adults, 17, 34 and 45 years old). Young children (13 days to 4 months after birth) showed little liver AO activity, evaluated in terms of the activities for oxidation of N-1-methylnicotinamide to N-1-methyl-2-pyridone-5-carboxamide and N-1-methyl-4-pyridone-3-carboxamide in liver cytosol. However, these oxidase activities were markedly increased after 4 months, reaching the adult level by about 2 years of age. The AO band density in immunoblotting analysis was well correlated with the AO activity among all subjects (p < 0.01, r(2) = 0.771). Therefore, AO activity in the liver of young children is regulated at the AO protein expression level. Thus, as in rats, the AO activity in humans rapidly increases soon after birth, and is regulated at the protein expression level.

Effect of tea beverages on aldehyde oxidase activity.

Aldehyde oxidase (AO) plays an important role in metabolizing antitumor and antiviral drugs, including methotrexate, cyclophosphamide and acyclovir. Green tea and its catechins have been shown to modulate the activities of various xenobiotic-metabolizing cytochrome P450 species, both in vivo and in vitro, but their effect on AO has not been studied. Therefore, we evaluated the effect of tea beverages on AO activity in rat and human liver cytosol. We also investigated the influence of several catechins on AO activity in rat liver cytosol. AO activity was evaluated in terms of oxidation of N-1-methylnicotinamide to N-1-methyl-2-pyridone-5-carboxamide and N-1-methyl-4-pyridone-3-carboxamide. Bottled green tea beverages at 10% (vol/vol) inhibited AO activity by 90.0-93.5%, while at 1.0% (vol/vol), they reduced AO activity by 73.9-90.0%. At 0.1% (vol/vol), green tea II and III, which have high contents of catechins and their derivatives, inhibited AO activity by 24.3% and 38.8%, respectively. Bottled mineral water had no effect. AO activity was inhibited potently by epicatechin and epicatechin gallate. These results indicate that the AO-inhibitory activity of tea beverages is predominantly due to catechins and their derivatives. Thus, consumption of tea beverages may cause a decrease of AO activity, which may result in reduced clearance of drugs that are AO substrates.

Current situation of drug information in the kindergarten and nursery teacher: a pilot study.

Because children cannot be expected to take medications correctly by themselves, parents are responsible for administering drugs based on the information provided by pharmacists. It has been reported that 90% of children aged 3-5 years in Japan attend kindergarten or nursery school, where teachers are responsible for the administration of some drugs to children. This study evaluated the types of information that teachers receive from parents. We conducted a questionnaire-based survey on drug information imparted to 144 teachers working in kindergarten or nursery schools in Hiroshima and Kure. The teachers reported that drug information from parents mainly comprised dosage and usage. However, little information was provided concerning the drug name, adverse drug reactions, and interaction with food items. To administer drugs to children safely, kindergarten and nursery teachers considered the information regarding adverse drug reactions (111/123 teachers), interaction with foods (106/123 teachers), and effective means of administering drugs (117/123 teachers) as important. The pharmacists' prescription notes have information on dosage, usage, drug name, adverse drug reactions, and interaction with food items. However, the teachers receive drug information from parents in the order of oral communication, a written note, and via the pharmacists' prescription note. Seventy-two percent of teachers (89/123 teachers) insisted on needing the pharmacists' prescription note. These results suggest that teachers are uncomfortable administering medications to children primarily due to inadequate information. Pharmacists should instruct parents to provide teachers with prescription notes to prevent grave medication errors.

[Influence of tacrolimus and ciprofloxacin on glucose metabolism].

Tacrolimus is an immunosuppressive drug that causes glucose intolerance. On the other hand, ciprofloxacin, which is widely used in the treatment of infectious diseases, is known to cause hypoglycemia as a side effect. We investigated the effects of tacrolimus and ciprofloxacin on serum glucose and insulin levels in rats, as well as on insulin secretion and the viability of HIT-T15 cells. The rats received intraperitoneal injections of tacrolimus and/or ciprofloxacin for 1 week, and their arterial blood was sampled after the administration of glucose. HIT-T15 cells were cultured in the presence of tacrolimus and/or ciprofloxacin, and the insulin level in the supernatant was measured. Ciprofloxacin did not show a significant effect on serum glucose and insulin levels after multiple administrations in the rats. In contrast, rats in the tacrolimus treatment group showed low serum insulin and high serum glucose levels. Moreover, the coadministration of ciprofloxacin and tacrolimus resulted in higher glucose levels compared with tacrolimus alone 0.5 h after glucose stimulation. In addition, we observed that the rats administered tacrolimus and/or ciprofloxacin had low body weight and food intake. Tacrolimus caused a dose-dependent decrease in the viability of the HIT-T15 cells. Furthermore, both drugs were highly toxic to HIT-T15 cells. In contrast, tacrolimus alone and coadministration of the drugs resulted in no significant difference in insulin secretion. These results suggest that the cytotoxic effects of ciprofloxacin and tacrolimus cause a decrease in insulin secretion, leading to glucose intolerance.