I chose this subject for the chairman's lecture without a moment's hesitation. During the four years at the graduate school, I studied virology and enjoyed a wide range of researches from molecular biology and electron microscopy to field work on the wintering of Japanese encephalitis viruses, etc. Then, I was engaged in research in the field of tropical medicine in Kenya, Africa. Half a year after I returned to Japan, still obsessed by Africanism, I came to Oita on a three-year contract. I found Oita blessed with nature and rich in wonderful food, However, the first thing I came across here was a parasite that is much larger than viruses. It was Paragonimus which would infect humans not through crab meat but raw boar meat. I also discovered the 12th case in Japan of pulmonary dirofilariasis in the human lungs that is an infection with filaria immitis. Later, I had opportunities to diagnose a variety of zoonosis, but I realized wrong diagnosis had been made for each of those infections. I came to Oita as a doctor of pulmonary medicine, but living in Africa had changed my view of life and my clinical view. In Africa, illesses were greatly affected by the natural environment and socio-economic factors in local areas. To present my experiences in discovering rare diseases in local areas, to talk about how I discovered them, and to mention the present situation and future themes are thought to be suitable for the Rural Medicine Congress which will be held in Kyushu for the first time in 22 years. In Japan, we have to keep zoonosis always in mind, when making diagnoses, because of an increasing number of people going overseas, the pet boom, the gourmet boom, the increase in imported foods, etc. Also zoonses, both new and reviving ones, are told to break our by unusual changes in this modern society. Now is the time to reexamine agriculture in Japan. I believe this is the task for people who are associated with the cause of rural medicine.
The recent development of molecular biology enables us to identify three abnormal insulins (insulin Chicago, insulin LosAngeles and insulin Wakayama). In Japan, three pedigrees in which affected individuals secrete [LeuA3] insulin (insulin Wakayama) have been identified. In each family, hyperinsulinemia associated with an abnormally elevated insulin to C-peptide molar ratio was demonstrated to occur in an autosomal dominant pattern of inheritance. In accordance with in vivo observations, semisynthetic [LeuA3] insulin demonstrated reduced in vitro receptor binding and biological activity relative to the human standard. The development of diabetes mellitus in affected family members was not uniform, was influenced by aging, and was different among families. Patients with impaired glucose tolerance demonstrated reduced insulin secretory reserve. Some of these features are thought to resemble the nature of noninsulin dependent diabetes mellitus (NIDDM). Therefore, insulin Wakayama may be an useful model for the study of the development of NIDDM.