Keita Kamei

Trade Liberalization, Division of Labor and Welfare under Oligopoly

ABSTRACT Incorporating explicitly division of labor into a two-country general oligopolistic equilibrium model, we examine the effects of trade liberalization on firm productivity and welfare. We show that a tariff reduction increases the firm productivity of the trading industries but decreases that of the non-trading industries. An expansion of the trading industries, in contrast, decreases the firm productivity of both the trading and non-trading industries. We then find that a tariff reduction necessarily reduces welfare while the welfare effect of expansion of trading industries is ambiguous.

The Association between Glomerular Filtration Rate Estimated Using Different Equations and Mortality in the Japanese Community-Based Population: The Yamagata (Takahata) Study

Background To evaluate renal function, the indices of estimated glomerular filtration rate (eGFR) obtained using several equations, including the Japanese versions of the serum creatinine-based MDRD equation (eGFRcreat), Chronic Kidney Disease Epidemiology Collaboration equation (eGFR-EPI), and serum cystatin C-based equation (eGFRcys), are utilized. This study prospectively examined the association between these eGFR values and all-cause mortality during a 12-year observational period in a community-based population. Methods and Results The subjects of this study were 1312 participants undergoing a health checkup, aged ≥40 years. In the total population, the mean eGFR values (mL·min−1·1.73 m−2) were 81.5 for eGFRcreat, 78.1 for eGFR-EPI, and 76.6 for eGFRcys. There were 141 deaths during the observation period, and the area under the receiver operating characteristic curve for predicting mortality was 0.59 for eGFRcreat, 0.67 for eGFR-EPI, and 0.70 for eGFRcys (all P < 0.01). In the Cox proportional analysis adjusted for age and sex, eGFRcys, but not eGFRcreat and eGFR-EPI, showed a significant association with all-cause mortality (per 15 mL·min−1·1.73 m−2 decrease: hazard ratio 1.40, 95% confidence interval 1.18–1.67). Conclusions This study revealed that eGFRcys showed lower values than eGFRcreat and eGFR-EPI and was significantly associated with all-cause mortality in the Japanese community-based population.

The Association between Serum Uric Acid and Renal Damage: The Takahata Study - New Insights

BACKGROUND Hyperuricemia is a risk factor for causing end-stage kidney disease and cardiovascular disease in the general population; however, several aspects, such as the site of kidney damaged by hyperuricemia and the threshold levels of serum uric acid for the development of renal damage, have not been fully clarified. SUMMARY To examine these aspects, we analyzed data from the Takahata study, a community-based cohort study involving participants of an annual health check-up, and used urinary albumin creatinine ratio (UACR) and urinary β2-microglobulin creatinine ratio (UBCR) in spot urine as indices of glomerular and tubular damage respectively. In cross-sectional analysis, increased serum uric acid levels were accompanied by higher UACR values and lower UBCR values. Multivariate analysis revealed that albuminuria (UACR ≥30 mg/g), but not elevated UBCR, was independently associated with increased uric acid (≥7 mg/dL for males, ≥6 mg/dL for females). In longitudinal analysis, uric acid at baseline was an independent factor for a 1-year increase in the UACR. Cox-proportional hazard model analysis with adjustment for possible confounders including age, renal function, and comorbidities revealed that hyperuricemia was an independent risk factor for all-cause and cardiovascular mortality in females. Key Messages: Our results revealed that elevated uric acid is an independent risk factor for glomerular damage, but not tubular damage, and that the risk for renal damage and mortality might be increased at the high-normal range of uric acid in the community-based population.

Agricultural Productivity, Infrastructures and the Optimal Timing of Opening Trade

This study develops a dynamic Ricardian trade model that incorporates productive infrastructures into the manufacturing sector. The costs of building infrastructures are financed by tax. We investigate the relationship between the timing of opening trade and total welfare. The main results are as follows: (1) there is the optimal tax rate maximizing the total welfare; (2) an increase in agricultural productivity can accelerate the timing of opening trade, which, however, does not necessarily improve total welfare; and (3) total welfare under specialization in manufacturing can be higher than that under specialization in agriculture depending on the prevailing conditions.