With the increasing understanding of the cytotoxicity of free radicals and other reactive oxygen species as a major cause of human disease and aging, the roles of endogenous antioxidants have drawn attentions. Uric acid, 1) vitamin E, 2) vitamin C, 3) ubiquinone, 4) SH-compounds, 5) bilirubin, 6) and pyruvate 7) are recognized as endogenous non-enzymatic antioxidants, while catalase, superoxide dismutase and glutathione peroxidase are known to be enzymatic antioxidants.Dopamine is the immediate metabolic precursor of norepinephrine and epinephrine. Dopamine interacts with dopamine receptors, then exerts its pharmacological effects.In human and experimental animals, dopamine is present almost entirely as a sulfate conjugated form in the circulation, 8,9) and very little of the free form is presented in the plasma.10) The physiological roles of sulfate conjugated dopamine are still unclear. Pharmacologically, conjugated dopamine has convulsive effects, 11) inhibits aldosterone secretion from cultured bovine adrenal cells, 12) and induces a constriction of some vascular beds. 13) One study, however, found that sulfate conjugated dopamine has no physiological activity. 14)From the viewpoint of free radical chemistry, dopamine can serve electrons via its oxidation pathway (Chart 1). This enables dopamine to act as both an antioxidant and a prooxidant. It acts as an antioxidant by scavenging free radicals. [15][16][17] Recently, it was found that dopamine spontaneously react with molecular oxygen to produce reactive oxygen species and semiquinone dopamine radical, 18,19) which are toxic to catecholamine neurons. [20][21][22][23] However, there is no evidence that sulfate conjugated dopamine acts as an antioxidant or a prooxidant. Therefore, in the present report, we compared dopamine and dopamine-4-O-sulfate for susceptibility to enzymatic and non-enzymatic oxidization in vitro using alkaline solution, horseradish peroxidase, UV irradiation, hydroxyl radical, superoxide anion radical, and sodium periodate. ExperimentalChemicals Dopamine, hypoxanthine, xanthine oxidase (from butter milk), and peroxidase (from horseradish) were purchased from Sigma Chemical Co., (MO, U.S.A.), hydrogen peroxide from Wako Pure Chemical Industries Ltd. (Osaka, Japan), and sodium metaperiodate from Acros Organics (NJ, U.S.A.). Dopamine-4-O-sulfate was kindly donated by Kyowa Hakko Kogyo Co., Ltd. (Tokyo, Japan). Other reagents were of the highest quality available from Wako Pure Chemical Industries Ltd.Free Radical Analysis Using EPR Spectroscopy The free radical metabolites of dopamine and dopamine-4-O-sulfate were examined with an EPR spectrometer (JES-TE 300, JEOL Co., Ltd., Tokyo, Japan) equipped with a cavity and an aqueous quartz flat cell (JEOL Co., Ltd., Tokyo, Japan) at X-band (9.5 GHz). EPR data were analyzed by a computer (HP Apollo 9000 Series 400) with the software, ESPRIT 432 ( JEOL Co., Ltd., Tokyo, Japan). Typical operating conditions of the EPR spectrometer were: power, 5 mW; center field, 3360 G; sweep width, 20 G; modulat...

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We investigate the relationship between management practices and long working hours by combining large-scale establishment panel data on management practices with the corresponding employee data on overtime hours in the manufacturing sector. We find that the adoption of more structured bonus and promotion practices is correlated with an increasing probability of workers working more than short-to-medium overtime hours. In addition, the adoption of more structured production monitoring and targeting practices is associated with a lower probability of workers working long overtime hours, resulting in narrowing disparities in overtime hours across workers within establishments.

Recent studies on fiscal policy use cross-sectional data and estimate local fiscal multipliers along with spillovers. This paper estimates local fiscal multipliers with spillovers using Japanese prefectural data comparable with the national accounts. We estimate the local fiscal multiplier on output to be 1.7 at the regional level. The regional fiscal multiplier consists of the prefecture-specific components and a component common across prefectures within the same region, which we interpret as the region-wide effect. Converting the latter component into the spillover, we find that the spillover is positive and small in size. We decompose the regional fiscal multiplier on output into multipliers on expenditure components. The regional fiscal multiplier on absorption exceeds 2.0 because of the crowding-in effect on consumption and investment. Moreover, we find that the spillover to absorption is considerable in contrast to the spillover to output.