The Effect of Heavy Metals on Nicotinamide \it{N}-methyltransferase Activity \it{In Vitro} Relating to Parkinson\rqs Disease

Objective: The aims of this study were to determine the effects of heavy metals such as manganese on nicotinamide N-methyltransferase (EC 2.1.1.1) (NNMT) activity and to consider the possibility of involvement of NNMT activation in the pathogenesis of heavy metal induced Parkinson’s disease. Methods: NNMT activity in supernatants separated from brain, liver and kidney homogenates of 5 elderly male Wistar rats by centrifugation were measured by high performance liquid chromatography system with fluorescence. NNMT activity under the conditon of 0.5 or 5.0 mM Mn2+, Fe2+, Cu2+ or Cd2+ was compared with control (no metal ion existence). Results: NNMT activities in rat brain, liver and kidneys were significantly decreased by Cu2+, and those in the liver and kidneys were significantly decreased by Cd2+. Mn2+ reduced NNMT activity only in the liver. Fe2+ had no effect on NNMT activity. Conclusions: No metal increased NNMT activity in this study, contrary to our hypothesis. Further study is needed to clarify the reason why the effects of Mn2+ and Fe2+ which have a high relevance to Parkinson’s disease on NNMT activity differ from those of Cu2+ and Cd2+.

The effect of heavy metals on nicotinamideN-methyltransferase activityin vitro relating to Parkinson's disease

<p><b>OBJECTIVE</b>The aims of this study were to determine the effects of heavy metals such as manganese on nicotinamideN-methyltransferase (EC 2.1.1.1) (NNMT) activity and to consider the possibility of involvement of NNMT activation in the pathogenesis of heavy metal induced Parkinson's disease.</p><p><b>METHODS</b>NNMT activity in supernatants separated from brain, liver and kidney homogenates of 5 elderly male Wistar rats by centrifugation were measured by high performance liquid chromatography system with fluorescence. NNMT activity under the conditon of 0.5 or 5.0 mM Mn(2+), Fe(2+), Cu(2+) or Cd(2+) was compared with control (no metal ion existence).</p><p><b>RESULTS</b>NNMT activities in rat brain, liver and kidneys were significantly decreased by Cu(2+), and those in the liver and kidneys were significantly decreased by Cd(2+). Mn(2+) reduced NNMT activity only in the liver. Fe(2+) had no effect on NNMT activity.</p><p><b>CONCLUSIONS</b>No metal increased NNMT activity in this study, contrary to our hypothesis. Further study is needed to clarify the reason why the effects of Mn(2+) and Fe(2+) which have a high relevance to Parkinson's disease on NNMT activity differ from those of Cu(2+) and Cd(2+).</p>

Effects of Decreasing Air Temperature on Peripheral Thermal Reactions in Males and Females

Objectives: This study was performed to determine the effects of decreasing ambient temperature on peripheral blood flow and body temperature of males and females in a thermal neutral zone for references to the thermal standard of office workers. Methods: Peripheral blood flows of the hand and feet, and body temperatures and so on of male and female subjects were measured in a climatic chamber. Air temperature was maintained at 28.5°C at the beginning. After this, air temperature was decreased linearly to 21.0°C over a period of 60 minutes. Finally, air temperature was maintained at 21.0°C. Results: Blood flows and skin temperatures of male and female subjects became similar or showed no significant difference at beginning and the end of the experiment. Skin blood flow of the hand and skin temperatures of the hand and fingers decreased, and these values in females were lower than in males, when air temperature was decreased linearly in a thermal neutral zone. However, there were no remarkable differences between males and females in sublingual and mean skin temperatures during the experiment. Conclusion: Minimum air temperature at the thermal standard for offices in Japan is 17°C, which may be too low to be comfortable or neutral. Even in a neutral thermal condition, it is better that office workers are provided some protection such as a blanket or clothing, to protect peripheral body parts from cooling in winter, as there are individual differences in physiological thermal reactions.

Effects of decreasing air temperature on peripheral thermal reactions in males and females

<p><b>OBJECTIVES</b>This study was performed to determine the effects of decreasing ambient temperature on peripheral blood flow and body temperature of males and females in a thermal neutral zone for references to the thermal standard of office workers.</p><p><b>METHODS</b>Peripheral blood flows of the hand and feet, and body temperatures and so on of male and female subjects were measured in a climatic chamber. Air temperature was maintained at 28.5°C at the beginning. After this, air temperature was decreased linearly to 21.0°C over a period of 60 minutes. Finally, air temperature was maintained at 21.0°C.</p><p><b>RESULTS</b>Blood flows and skin temperatures of male and female subjects became similar or showed no significant difference at beginning and the end of the experiment. Skin blood flow of the hand and skin temperatures of the hand and fingers decreased, and these values in females were lower than in males, when air temperature was decreased linearly in a thermal neutral zone. However, there were no remarkable differences between males and females in sublingual and mean skin temperatures during the experiment.</p><p><b>CONCLUSION</b>Minimum air temperature at the thermal standard for offices in Japan is 17°C, which may be too low to be comfortable or neutral. Even in a neutral thermal condition, it is better that office workers are provided some protection such as a blanket or clothing, to protect peripheral body parts from cooling in winter, as there are individual differences in physiological thermal reactions.</p>