Yoichi Nagamura

Presence of a lectin-like receptor for D-galactose on rat peritoneal macrophages

Neuraminida~-treated erythrocytes adhere to macrophages in vitro [ 1,2] as well as in vivo [3-51. In vivo desialylated erythrocytes are taken up by macrophages of the liver (Kupffex cells) when injected intravenously [S]. We have found that adhesion of neura~nidase-treated e~throc~es to Kupffer cells is due to a ~a~tose*sFeci~~ Iectin on the macrophage 161. We now report the presence of a similar galactosespecific receptor on rat peritoneal macrophages.

Tryptophan 2,3-dioxygenase activity in rat skin

We have found an enzyme system that catalyzes the conversion of L-tryptophan to L-kynurenine, presumably via L-formylkynurenine, in soluble and insoluble fractions of rat skin. The enzymatic activity was stimulated by hematin, ascorbate, and catalase, but not by methylene blue. Highest activity was located in the skin of the dorsal posterior region and lowest activity in the abdominal region. The activity in plucked (depilated) skin was only about 25% of that obtained from unplucked (depilated) tissue of the same region. D-Tryptophan, 5-hydroxytryptophan, and tryptamine were not degraded by the skin enzyme and the Km for L-tryptophan determined with the crude enzyme was 1 microM. The decycling activity of rat skin and liver for L-tryptophan began to be stimulated after birth and reached the highest level at 6 weeks. But, 1 week later, most of the skin activity suddenly disappeared and the low level continued at least until 12 weeks. In contrast, the hepatic enzyme did not change so drastically. These findings suggest that an enzyme that catalyzes L-tryptophan to L-kynurenine via L-formylkynurenine is present in rat skin.

Cholesterol uptake of isolated rat hepatocytes is accelerated by several kinds of phosphatidylcholine

Cholesterol uptake (Isolated rat hepatocyte) Phosphatidylcholine Unsaturated fatty acid Dioleoylphosphatidylcholine Dipalmitoylphosphatidylcholine