Farmer's lung is a form of hypersensitivity pneumonitis, which is manifested mainly as an occupational disease among dairy farmers exposed to organic dusts from moldy hay and compost in silos and lofts. In Europe and America, it has been known for many years. In Japan, it frequently occurs in Hokkaido, Iwate and Hokuriku districts during winter months from November to March. The culprit antigens are spores of actinomycetes thermophilus such as Micropolyspora faeni and Thermoactinomyces vulgaris. In recent years, various preventive measures have been taken. For instance, in order to prevent hay from heating by fermentation and the thermophile from thriving, farmers desiccate hay as much as possible and keep it in air-tight plastic containers. The result is a notable decrease in the prevalence rate of this ailment. Nonetheless, with graying the rural population, pulmonary fibrosis caused by chronic exposure to low levels of organic dust is posing a grave health problem in the dairy farming communities. As a prophylactic measure against chronic fibrotic lung disease, there is a need to implement a comprehensive heath control program consisting of continual sanitary checkups at workplace and counseling at an early stage in addition to periodic health examinations. Another health threat which has more recently loomed up in the dairy farming communities is environmental pollution.

In conventional pharmacological research in the field of mental disorders, pharmacological effect and dose have been estimated by ethological approach and in vitro data of affinity to the site of action. In addition, the frequency of administration has been estimated from drug kinetics in blood. However, there is a problem regarding an objective index of drug effects in the living body. Furthermore, the possibility that the concentration of drug in blood does not necessarily reflect the drug kinetics in target organs has been pointed out. Positron emission tomography (PET) techniques have made progress for more than 20 years, and made it possible to measure the distribution and kinetics of small molecule components in living brain. In this article, we focused on rational drug dosing using receptor occupancy and proof-of-concept of drugs in the drug development process using PET.
Brain ; Central Nervous System ; Drug Evaluation ; Electrons ; Kinetics ; Mental Disorders ; Norepinephrine Plasma Membrane Transport Proteins ; Positron-Emission Tomography ; Receptors, Dopamine D2 ; Serotonin Plasma Membrane Transport Proteins