Springer Science and Business Media LLCActa Medica Okayama1352-47392024The optimum quantity of debt for an aging Japan: welfare and demographic dynamicsENAkiraOkamotoFaculty of Economics, Okayama UniversityJapan’s government is heavily indebted, and the current net debt tends to increase. This paper uses an extended life-cycle general equilibrium model with endogenous fertility to investigate an optimal size of government debt from two viewpoints: individual welfare and future demographic dynamics. A simulation analysis finds that the level of net government debt, which maximizes per-capita utility, is negative at − 220% of Japan’s gross domestic product (GDP). The results also indicate that the net debt-to-GDP ratio of − 220% produces a considerable per-capita welfare gain; however, compared to the baseline simulation with a debt-to-GDP ratio of 150%, it substantially decreases the total population in the long run.No potential conflict of interest relevant to this article was reported.岡山大学経済学会Acta Medica Okayama2433-4146512-32020Silver Democracy and Electoral System : Political Feasibility of Policy Reform Plans in an Aging Japan123129ENAkiraOkamotoGraduate School of Humanities and Social Sciences, Okayama University10.18926/OER/58075No potential conflict of interest relevant to this article was reported.岡山大学経済学会Acta Medica Okayama0386-30693222000所得分布と高齢化社会における税制改革5998ENAkiraOkamoto10.18926/OER/41467This paper examines the effects of changes in the variance of income distribution on both capital accumulation and social welfare in Japan, the
society with an aging population. To analyze the problem, we adopt a simulation approach for an extended life-cycle general equilibrium model
of overlapping generations with continuous income distribution. The simulation results indicate that the changes in the variance affect economic variables under a progressive tax scheme but they do not under a proportional tax scheme. The results also show that social welfare greatly increases as the variance shrinks. Therefore, the recent shift in Japan, where the taxation system has tended in effect to become flat, may cause a significant damage to social welfare.No potential conflict of interest relevant to this article was reported.岡山大学経済学会Acta Medica Okayama0386-30693212000労働異質性と高齢化社会における税制改革―累進税制の選択と資産格差への影響―148ENAkiraOkamoto10.18926/OER/41456This paper examines the effects of a progressive labor income tax scheme and a progressive consumption tax scheme on capital stock and on
intragenerational wealth distribution in Japan, the society with an aging population. To analyze the problem, we adopt a simulation approach for
an extended life-cycle general equilibrium model of overlapping generations. As a progressive tax is likely to mitigate the inequality of resource distribution, it is crucial to allow for the existence of heterogeneous labor. This is incorporated by assuming that each cohort
has three representative individuals with equal tastes but unequal annual labor endowments, corresponding to three income classes, namely,
low, middle, and high income classes. As the simulation results indicate, a progressive labor income tax shrinks the inequality in the distribution of wealth, while a progressive consumption tax furthers slightly.No potential conflict of interest relevant to this article was reported.岡山大学経済学会Acta Medica Okayama0386-30693642005Introduction of Progressive Expenditure Taxation to Japan193201ENAkiraOkamoto10.18926/OER/40545With a population that is aging faster than any other in the world, Japan faces serious public finance problems, particularly when it comes to tax and social security issues. The structural reforms are urgently needed to accommodate the impending demographic change. We look at the Japanese tax and social security systems through a life−cycle general equilibrium simulation model. We aim to establish guidelines for fiscal
reform in Japan’s graying society and use such advanced modeling techniques to permit the calculation of the effects of alternative tax policies on capital accumulation and economic welfare. We also examine the impact of
progressive expenditure taxation, coming to the novel conclusion that this form of taxation may hold the key to overcoming the large welfare loss Japan faces as its society ages under the current tax system. Furthermore, we present the concrete measures of implementing progressive expenditure taxation.No potential conflict of interest relevant to this article was reported.Okayama University Medical SchoolActa Medica Okayama0386-300X5762003Pathophysiological functions of CD30+ CD4+ T cells in rheumatoid arthritis.267277ENAkiraOkamotoMasahiroYamamuraMitsuhiroIwahashiTetsushiAitaAkikoUenoMasanoriKawashimaJiroYamanaHidetoshiKagawaHirofumiMakinoArticle10.18926/AMO/32814<p>High levels of soluble CD30 (sCD30) were detected in the serum and synovial fluid of patients with rheumatoid arthritis (RA), indicating the involvement of CD30+ T cells in the pathogenesis. We investigated the induction of CD30 and its functions in CD4+T cells from patients with established RA (disease duration >_2 years). CD4+ T cells from both the peripheral blood (PB) and synovial tissue (ST) of RA patients expressed surface CD30 when stimulated with anti-CD3 antibody (Ab) and anti-CD28 Ab, but their CD30 induction was slower and weaker compared with PB CD4+ T cells of healthy controls (HC). Immunohistochemical analysis showed that only a small proportion of lymphocytes expressed CD30 in the ST (-1%). RA PB CD4+ T cells, after recovery from 6-day stimulation with anti-CD3 Ab and anti-CD28 Ab, showed in intracellular cytokine staining that CD30+ T cells could produce more interleukin-4 (IL-4) but less interferon-gamma. In the culture of RA PB CD4+ T Cells with anti-CD3 Ab and anti-CD28 Ab, blocking anti-CD30 Ab similarly inhibited the cell proliferation and activation of nuclear factor-kappaB on day 4 in RA and HC, but inhibited the apoptotic cell death on day 6 only in RA. These results indicate that despite high-level expression of sCD30, the anti-inflammatory activity of IL-4-producing CD30+ CD4+ T cells may be limited in the ST due to a poor induction of surface CD30 and a susceptibility to CD30-mediated cell death.</p>No potential conflict of interest relevant to this article was reported.Acta Medica Okayama2003Pathophysiological functions ofCD30+CD4+ T cells in rheumatoid arthritisENAkiraOkamotoNo potential conflict of interest relevant to this article was reported.