* The reason for the fall in death rates from stroke in industrialised countries is unclear * In this study blood pressure and smoking were independent risk factors for stroke in both sexes and serum cholesterol concentration was also a risk factor in men * Mortality fell by 62% in men and 63% in women over 20 years * Changes in risk factors explained 71% ofthe fall in men and 54% in women * Continued emphasis on promoting healthier lifestyles and effective treatment for hypertension are essential to maintain the fall in deaths representative of development in the entire country. It should not be taken for granted that the decreasing trend will automatically continue. Our data show that the fall will continue only if preventive measures targeted on the primary risk factors, particularly on blood pressure, are effective.

We investigated in vitro a mechanism by which particulate debris may induce bone resorption and cause implant loosening. We first studied two standard particles: latex, which is considered to be inert, and zymosan, which is inflammatory. Macrophages that phagocytosed either particle became activated, and stimulated 15 times as much bone resorption as did control macrophages. For activation to occur, 100 times more latex than zymosan had to be phagocytosed. We also found that bone cement and polyethylene particles activated macrophages in a similar manner, and that the necessary amounts of these were intermediate between those of latex and zymosan. None of the particles were toxic. It was concluded that implant loosening may result from bone resorption stimulated by mediators released by macrophages that have phagocytosed particles of bone cement or polyethylene.