Unique Binding Sites of Uricosuric Agent Dotinurad for Selective Inhibition of Renal Uric Acid Reabsorptive Transporter URAT1.

Dotinurad was developed as a uricosuric agent, inhibiting urate (UA) reabsorption through the UA transporter URAT1 in the kidneys. Due to its high selectivity for URAT1 among renal UA transporters, we investigated the mechanism underlying this selectivity by identifying dotinurad binding sites specific to URAT1. Dotinurad was docked to URAT1 using AutoDock4, utilizing the AlphaFold2-predicted structure. The inhibitory effects of dotinurad on wild-type and mutated URAT1 at the predicted binding sites were assessed through URAT1-mediated [14C]UA uptake in Xenopus oocytes. Nine amino acid residues in URAT1 were identified as dotinurad-binding sites. Sequence alignment with UA-transporting organic anion transporters (OATs) revealed that H142 and R487 were unique to URAT1 among renal UA-transporting OATs. For H142, IC50 values of dotinurad increased to 62, 55, and 76 nM for mutated URAT1 (H142A, H142E, and H142R, respectively) compared with 19 nM for the wild type, indicating that H142 contributes to URAT1-selective interaction with dotinurad. H142 was predicted to interact with the phenyl-hydroxyl group of dotinurad. The IC50 of the hydroxyl group methylated dotinurad (F13141) was 165 µM, 8420-fold higher than dotinurad, suggesting the interaction of H142 and the phenyl-hydroxyl group by forming a hydrogen bond. Regarding R487, URAT1-R487A exhibited a loss of activity. Interestingly, the URAT1-H142A/R487A double mutant restored UA transport activity, with the IC50 value of dotinurad for the mutant (388 nM) significantly higher than that for H142A (73.5 nM). These results demonstrate that H142 and R487 of URAT1 determine its selectivity for dotinurad, a uniqueness observed only in URAT1 among UA-transporting OATs. SIGNIFICANCE STATEMENT: Dotinurad selectively inhibits the urate reabsorption transporter URAT1 in renal urate-transporting organic ion transporters (OATs). This study demonstrates that dotinurad interacts with H142 and R487 of URAT1, located in the extracellular domain and unique among OATs when aligning amino acid sequences. Mutations in these residues reduce affinity of dotinurad for URAT1, confirming their role in conferring selective inhibition. Additionally, the interaction between dotinurad and URAT1 involving H142 is found to mediate hydrogen bonding.

Role of Organic Anion Transporter NPT4 in Renal Handling of Uremic Toxin 3-indoxyl Sulfate.

Sodium-phosphate transporter NPT4 (SLC17A3) is a membrane transporter for organic anionic compounds localized on the apical membranes of kidney proximal tubular epithelial cells and plays a role in the urinary excretion of organic anionic compounds. However, its physiological role has not been sufficiently elucidated because its substrate specificity is yet to be determined. The present study aimed to comprehensively explore the physiological substrates of NPT4 in newly developed Slc17a3-/- mice using a metabolomic approach. Metabolomic analysis showed that the plasma concentrations of 11 biological substances, including 3-indoxyl sulfate, were more than two-fold higher in Slc17a3-/- mice than in wild-type mice. Moreover, urinary excretion of 3-indoxyl sulfate was reduced in Slc17a3-/- mice compared to that in wild-type mice. The uptake of 3-indoxyl sulfate by NPT4-expressing Xenopus oocytes was significantly higher than that by water-injected oocytes. The calculated Km and Vmax values for NPT4-mediated 3-indoxyl sulfate uptake were 4.52 ± 1.18 mM and 1.45 ± 0.14 nmol/oocyte/90 min, respectively. In conclusion, the present study revealed that 3-indoxyl sulfate is a novel substrate of NPT4 based on the metabolomic analysis of Slc17a3-/- mice, suggesting that NPT4 regulates systemic exposure to 3-indoxyl sulfate by regulating its urinary excretion.

SMARCB1/INI1-deficient intrathoracic neoplasm with rhabdoid/plasmacytoid cytomorphology in a patient with plasma cell myeloma: A case report.

SMARCB1 (INI1) is one of the switch/sucrose nonfermentable (SWI/SNF) complexes whose loss is associated with several tumors. SMARCB1 (INI1)-deficient intrathoracic neoplasms are extremely rare and known to be highly malignant and lethal. This report presents the case of a patient diagnosed with SMARCB1 (INI1)-deficient intrathoracic neoplasm during chemotherapy for plasma cell myeloma. A 77-year-old male patient complained of cough, bloody sputum, and fever with an enlarged right lung mass and pleural effusion. His cytological examination revealed undifferentiated epithelioid and rhabdoid/plasmacytoid cells with bi- or multinucleation, vacuolization, mitosis, and pleomorphism. However, it was difficult to distinguish the relapse of plasma cell myeloma as atypical plasmacytoid cells were detected. Immunohistochemically, the neoplastic cells showed a loss of SMARCB1 (INI1) expression in the cell block of pleural fluid and in the right lung of the autopsy specimen. Further, the patient was diagnosed with SMARCB1 (INI1)-deficient intrathoracic neoplasm of the right lung based on histological and autopsy findings. To the best of our knowledge, this is the first report of cytomorphology in a SMARCB1 (INI1)-deficient intrathoracic neoplasm.

Cytological examination of peripheral blood cell block to diagnose small cell variant ALK-positive anaplastic large cell lymphoma.

In small cell variant ALK-positive anaplastic large cell lymphoma (SC-ALCL), large hallmark cells are few and the preponderance are small- to medium-sized tumour cells. The cell block method is advantageous in SC-ALCL with small numbers of CD30-positive hallmark cells, in order to evaluate cell morphology and marker expression simultaneously. Accurate diagnosis of ALK-positive anaplastic large cell lymphoma (ALK+ ALCL) requires detection of CD30-positive hallmark cells. In small cell variant ALCL (SC-ALCL), large hallmark cells are few with the preponderance being small- to medium-sized tumour cells. The cell block method is advantageous in SC-ALCL with small numbers of CD30-positive hallmark cells in order to evaluate cell morphology and marker expression simultaneously.

Time spent walking and risk of colorectal cancer in Japan: the Miyagi Cohort study.

Higher levels of physical activity have been consistently associated with a lower risk of colon cancer in earlier epidemiological studies. The specific benefits of walking, however, remain relatively unexplored. In 1990, 20 519 men and 21 469 women in Japan completed a self-administered questionnaire including a question on time spent walking per day. During 7 years of follow-up, 260 cases of colorectal cancer were documented in 305 790 person-years. We used the Cox proportional hazards regression model to estimate the relative risk of incident cancer (colorectal, colon, and rectal) according to three levels of walking. Time spent walking was inversely associated with risk of colorectal cancer incidence in men. Compared with men who walked 0.5 h or less per day, the multivariate relative risks were 1.06 (95% confidence interval 0.72-1.57) for men who walked between 0.5 and 1 h per day, and 0.57 (95% confidence interval 0.38-0.83) for men who walked 1 h or more per day (P for trend=0.003). Time spent walking per day was associated with a lower risk of colon cancer in Japanese men but not in women, and there was no association between time spent walking and the risk of rectal cancer.

Joint impact of health risks on health care charges: 7-year follow-up of National Health Insurance beneficiaries in Japan (the Ohsaki Study).

BACKGROUND: The objective of this study was to examine the joint impact of modifiable health-risk factors such as smoking, obesity, and physical inactivity on direct health care charges. METHOD: We conducted a population-based prospective cohort study, with follow-up from 1995 to 2001. The participants were Japanese National Health Insurance (NHI) beneficiaries (26,110 men and women aged 40-79 years). RESULTS: 'No risk' group defined as never-smoking, body mass index (BMI) 20.0-24.9 kg/m(2), and walking for >/=1 h/day had mean health care charges of 171.6 dollars after adjustment for potential confounders. Compared with this group, the presence of smoking (SM; ever-smoking) alone, obesity alone (OB; BMI >/=25.0 kg/m(2)), or physical inactivity (PI; walking for <1 h/day) alone were associated with a 8.3%, 7.1%, or 8.0% increase in health care charges, respectively. The combinations of the risks of SM and OB, SM and PI, OB and PI, and SM and OB and PI were associated with a 11.7%, 31.4%, 16.4%, and 42.6% increase in charges, respectively. CONCLUSION: Interventions to improve modifiable health-risk factors may be a cost-effective approach for reducing health care charges as well as improving people's health.

Follow-up and mortality profiles in the Miyagi Cohort Study.

BACKGROUND: Findings from a large-scale population-based prospective cohort would lead us to better understanding of the relationship between lifestyle and health, thus better provision of strategies for disease prevention and health promotion. METHODS: We conducted a baseline survey with two self-administered questionnaires regarding lifestyle and personality on the residents aged 40 to 64 years in 14 municipalities of Miyagi Prefecture, Japan, during June through August, 1990. Out of the eligible 51,925 residents, 47,605 (91.7%) responded to the lifestyle questionnaire and formed the cohort under study. We then have been following up the subjects for mortality, migration, and incidence of cancer. RESULTS: During the follow-up from June 1990 through March 2001, 2,536 subjects (5.3%) died and 2,166 subjects (4.5%) emigrated. The distribution of the causes of death among the study subjects was quite consistent with the national average. CONCLUSIONS: In this cohort study, both the participation rate and the follow-up rate are satisfactorily high. We expect this Miyagi Cohort Study to provide the society with evidence for health promotion and disease prevention.

Walking and mortality in Japan: the Miyagi Cohort Study.

BACKGROUND: Although many studies in western populations demonstrated that time spent walking was associated with a reduced risk of all-cause mortality, data on Japanese has been sparse. METHODS: In 1990, 20,004 men and 21,159 women in Miyagi Prefecture in rural northern Japan (40-64 year of age) completed a self-administered questionnaire including a question on time spent walking. Cox regression was used to estimate relative risk (RR) of mortality according to three levels of walking (30 minutes or less, between 30 minutes and one hour, and one hour or more), with adjustment for age, education, marital status, past history of diseases, smoking, drinking, body mass index, and dietary variables. During 11 years of follow-up, 1,879 subjects had died. RESULTS: Time spent walking was inversely associated with risk of all-cause mortality: compared with men and women who walked one hour or more per day, multivariate RR (95% confidence intervals) was 1.06 (0.95-1.19) for subjects who walked between 30 minutes and one hour per day, and 1.16 (1.04-1.29) for subjects who walked 30 minutes or less per day (P for trend=0.007). Shorter duration of walking was associated with increased mortality among men who were never smokers (P for trend=0.081) and past smokers (P for trend=0.026), but not among currently smoking men (P for trend=0.751). We observed similar effect modification for women. CONCLUSIONS: Time spent walking was associated with a reduced risk for all-cause mortality, especially among nonsmoking men and women.

Body mass index and mortality in Japan: the Miyagi Cohort Study.

BACKGROUND: The relation between body mass index (BMI) and mortality is not well established. The objective of this study was to examine the association in Japanese adults. METHODS: In 1990, 18,740 men and 20,870 women in Miyagi Prefecture in rural northern Japan (40-64 years of age) completed a self-administered questionnaire including height and weight. Cox regression was used to estimate relative risk (RR) of mortality according to levels of BMI, with adjustment for age, marital status, smoking, drinking, walking, and weight change since 20 years of age. RESULTS: During 11 years of follow-up, 1,121 men and 567 women had died. Compared with the referent BMI category (23.0-24.9), women in the highest BMI category (BMI>30.0) had a RR of death of 1.64 (95% confidence interval (CI), 1.09-2.49) and men and women in the lowest BMI categories (BM1<18.5) had a RR of death of 2.06 (95% CI, 1.49-2.84) and 1.83 (95% CI, 1.17-2.88), respectively, after adjustment for potential confounders and after exclusion of deaths occurring in the first three years of follow-up. We did not observe significant differences in mortality for subjects with wide range of BMI (18.5 or higher in men and 18.5 to 29.9 in women). CONCLUSIONS: The risk of death from all causes increases in lean men and women, and obese women in this cohort.

Health practices and mortality in Japan: combined effects of smoking, drinking, walking and body mass index in the Miyagi Cohort Study.

BACKGROUND: Evidence is limited regarding the association between the combinations of multiple health practices and mortality. METHODS: In 1990, 28,333 men and women in Miyagi Prefecture in rural northern Japan (40-64 year of age) completed a self-administered questionnaire. A lifestyle score was calculated by adding the number of high-risk practices (smoking, consuming > or = 22.8 g alcohol/d, walking < 1 hr/d, body mass index < 18.5 or > or = 30.0). Cox regression was used to estimate relative risk (RR) of mortality according to the lifestyle score, with adjustment for age, education, marital status, past history of diseases, and dietary variables. During 11 years of follow-up, 1,200 subjects had died. RESULTS: We observed linear increase in risk of death associated with increasing number of high-risk practices: compared with men who had no high-risk practices, multivariate RRs for men who had 1 to 4 practices were 1.20, 1.66, 1.94, and 3.96, respectively (P for trend<0.001), and corresponding RRs for women were 1.31, 2.14, 3.98, 5.56, respectively (P for trend<0.001). A unit increase in the number of high-risk practices corresponded to being 2.8 and 4.8 years older for men and women, respectively. CONCLUSIONS: In this prospective cohort study of middle-aged men and women in rural Japan, a larger number of high-risk practices was associated with linear increase in risk of all-cause mortality.