My research on rural health began in 1953 when I was involved in a survey of the actual living environment and health conditions of residents where there were no practicing physicians. From the findings of subsequent surveys, I noticed how badly poor living environments in rural areas can affect the health of the residents. In 1962, I engaged in a study of environmental pollution in rural areas caused by industrial development and contributed to significant achievements of mine ; namely, I was the first person in the world to discover that not only does air pollution due to fluoride destroy plants, but also fluoride can accumulate in crops causes fluorosis when ingested by animals and humans. For this work, I received The Kiyoshi Saito Award from the Japan Society of Air Pollution in 1976.
Next, Our research began with occupational health in dairy farming. We were able to establish a labor management system which is acceptable to all dairy farmers. R ecently, I surveyed changes of the physical constitution of pupils in a farming village which occurred over the last 40 years. In the last forty years, in pupils in the rural area, the thorax has flattened, the head has become rounded and the face has elongated. I can only attribute this change to the significant improvement in the diet and living environment of the children in the rural area.
The medical technologies used in my research on rural health were not necessarily advanced ; rather I tried to used an approach which guaranteed the reproducibility of data even if the method was old. I hope my stance toward medical research will be of some help to young member of this society studying rural medicine.

Objectives: Cytokines are critical regulatory molecules that circulate in blood at measurable levels. However, the epidemiology of serum cytokine levels in healthy populations is still limited, particularly for Japanese populations. The objective of this study was to examine the relation between serum cytokine levels and common laboratory tests in a healthy Japanese population. Methods: We studied serum levels of six cytokines (interleukin-4 (IL-4), IL-5, IL-6, IL-10, interferon-γ (IFN-γ), granulocyte-macrophage colony-stimulating factor (GM-CSF)) in a healthy Japanese population using a sensitive chemiluminescence ELISA (CL-ELISA). We examined the relations between serum cytokine levels and common laboratory tests using multiple regression analysis. We were particularly interested in potential relations between serum cytokine levels and C-reactive protein (CRP) in light of its relation to the risk of cardiovascular events. We also investigated the relation between cytokine levels, alcohol consumption and smoking. Results: After adjusting for the influence of other cytokines and laboratory tests, the serum level of IL-4 was associated with IL-5 and GM-CSF. In addition to IL-4, IL-5 was also associated with IL-10 and IFN-γ. IL-6 was associated with IL-10 and IFN-γ, and IL-10 and IFN-γ were associated with GM-CSF. CRP was significantly negatively associated with serum IL-4 level. IL-6 was weakly correlated with alcohol consumption level in this population. IL-5 among smokers tended to be lower than that among nonsmokers. Conclusions: Close relations among serum cytokine levels were observed in a healthy population. It is interesting that the level of IL-4, an anti-inflammatory cytokine, was inversely related to CRP level, suggested to be a marker of inflammation.
Serum ; Cytokines ; Interleukin-4 ; Japanese language ; Interleukin-10

OBJECTIVESCytokines are critical regulatory molecules that circulate in blood at measurable levels. However, the epidemiology of serum cytokine levels in healthy populations is still limited, particularly for Japanese populations. The objective of this study was to examine the relation between serum cytokine levels and common laboratory tests in a healthy Japanese population.

METHODSWe studied serum levels of six cytokines (interleukin-4 (IL-4), IL-5, IL-6, IL-10, interferon-γ (IFN-γ), granulocyte-macrophage colony-stimulating factor (GM-CSF)) in a healthy Japanese population using a sensitive chemiluminescence ELISA (CL-ELISA). We examined the relations between serum cytokine levels and common laboratory tests using multiple regression analysis. We were particularly interested in potential relations between serum cytokine levels and C-reactive protein (CRP) in light of its relation to the risk of cardiovascular events. We also investigated the relation between cytokine levels, alcohol consumption and smoking.

RESULTSAfter adjusting for the influence of other cytokines and laboratory tests, the serum level of IL-4 was associated with IL-5 and GM-CSF. In addition to IL-4, IL-5 was also associated with IL-10 and IFN-γ. IL-6 was associated with IL-10 and IFN-γ, and IL-10 and IFN-γ were associated with GM-CSF. CRP was significantly negatively associated with serum IL-4 level. IL-6 was weakly correlated with alcohol consumption level in this population. IL-5 among smokers tended to be lower than that among nonsmokers.

CONCLUSIONSClose relations among serum cytokine levels were observed in a healthy population. It is interesting that the level of IL-4, an anti-inflammatory cytokine, was inversely related to CRP level, suggested to be a marker of inflammation.