Hb J-Cordoba [alpha 2A beta 2(95)(FG2)Lys----Met]. A new Hb variant found in Argentina.

Hb J-Cordoba [alpha 2A beta 2(95)(FG2)Lys----Met], is one of the few hemoglobin variants discovered in Argentina. The structure and functional abnormalities are described. Hb J-Cordoba exhibits a slightly increased oxygen affinity, low cooperativity, and normal interaction with heterotropic cofactors.

Particle-counting immunoassay of human somatotropin.

Human somatotropin was assayed by a novel automated nonradioisotopic technique, "particle-counting immunoassay," that requires a 45-min incubation and only 60 microL of 10-fold diluted sample. The principle of the assay is agglutination of antibody-coated latex particle by somatotropin, the reaction being measured by the (instrumented) counting of residual non-agglutinated particles. The dynamic range in serum extends from 0.

Uptake of lactoferrin by the liver. III. Critical role of the protein moiety.

Three possible modes of recognition of human lactoferrin (Lf), which is avidly taken up by the mouse liver, were examined. First, Lf has terminal galactosyl residues for which a receptor exists on hepatocytes. However, when large amounts of Lf were injected with 125I-asialoorosomucoid, no inhibition of asialoorosomucoid uptake by the liver was observed.

Uptake of lactoferrin by the liver. II. Endocytosis by sinusoidal cells.

Because of the controversy on the cell type involved in lactoferrin (Lf) uptake by the liver we localized injected Lf by immunofluorescence, light microscopic autoradiography, and light and electron microscope cytochemistry with Lf-peroxidase conjugates. These conjugates were essentially taken up by their Lf moiety as shown by competition experiments. By any procedure, Lf was almost exclusively found in the sinusoidal cells as well as in the wall of the central veins.

Uptake of lactoferrin by the liver. I. Role of the reticuloendothelial system as indicated by blockade experiments.

When 125I-labeled human lactoferrin was injected intravenously into mice it was rapidly taken up by the liver, where 75% of the dose was recovered after 15 minutes. The inhibition curve with unlabeled lactoferrin showed that the fates of labeled and unlabeled protein were similar and that the uptake capacity was saturable by milligram quantities of protein per gram of liver, suggesting the existence of numerous specific binding sites. The presence of these sites on the reticuloendothelial system was indicated by the blocking effect of dextran sulfate and latex particles.