This paper presents the autoptical findings of 4 cases of leptospiral cerebral arteritis involving predominantly large arteries at the base of the brain, especially the middle and anterior cerebral arteries. The main pathological change of this basal cerebral polyarteritis is a proliferative endarteritis which may be classified into three types: acute, chronic and oblitero-sclerous. Specific serological tests for leptospirosis were positive in two cases and in one of these two patients spirochetes were found while in the other, immuno-fluorescence positive substance was demonstrated in the involved cerebral arteries. These findings, together with the clinico-epidemiological data, strongly suggest that the cerebral arteritis in our cases should be the result from leptospirochetic infection.

A series of immunological studies has been carried out on various types of viral hepatitis B. The positive cell-mediated immunity to HBsAg and LSP and positive HBsAg immune complex accompanied with a reduction in ER positive lymphocytes and abnormal ADCC were observed in chronic active hepatitis, fulminant hepatitis and subacute liver necrosis. The patients studied also showed reduced suppressor cell activity, positive E rosette inhibitory factor and serum inhibitory factor of interferon induction. Temporary positive findings of these immune responses were detected in convalescent patients of acute hepatitis. On the contrary, asymptomatic carriers showed minimal or negative specific cell-mediated immunity and normal suppressor cell activity. Therefore, a classification of immune response in viral hepatitis B has been suggested.

In this study cytogenetic analysis of 5 cases of acute promyelocytic leukemia (APL) is described and 3 (60%) of them showed t(15; 17) in karyotype. In recent years more than 130 cases of hematological disorders were studied cytogenetically in our laboratory and this kind of translocation has not been found except in APL. As shown in these patients t(l5; l7) might occur in adults as well as in children and likewise in patients with or without DIC. The chromosome study by G-banding technique demonstrated that the breakpoint of chromosome No. 15 was located between q²⁴ and q²⁵, and that of chromosome No. 17 was located at q²¹. The structural rearrangement was reported as rcp(15;17) (q²⁵⁰⁰; q^2102?).