Haemoglobins of the foetal and adult rat: sites of synthesis and the effects of erythropoietin

Early studies on rat haemoglobins indicated the existence of several components (Gratzer & Allison, 1960). Seven components were found in the blood of adult random-bred Wistar rats by CM-cellulose chromatography; their rates of synthesis appeared unaltered during erythroid cell maturation (Brada & Tobiska, 1964). A 5-component electrophoretic pattern found in some randombred Wistar rats was considered to be a combination of two 4-component patterns observed in two inbred strains (Marinković, Martinović & Kanazir, 1967). A 4-component electrophoretic pattern was also reported by Cole, Hunter & Paul (1968). During gestation the number of components resolved in this buffer system increased from 1 at 13 days to 4 at 15 days; the pattern appeared identical to that of the adult from 18 days onward.

Erythropoietin stimulates stem cells to mature to erythrocytes (Filmanowicz & Gurney, 1961; Orlic, Gordon & Rhodin, 1965; Nakao, Miura & Takaku, 1966).

Carcinogenesis: A current appraisal

During the past decade the carcinogens responsible for many individual kinds of cancer have been identified, but these discoveries have not greatly altered our general concepts of factors which predispose to, or initiate cancer. The most substantial advances have been in our understanding of the phenomena associated with cancer. These have led to more sophisticated speculations about mechanisms; we may now be within sight of understanding the nature of the disease.

Factors influencing glucose flux and the effect of insulin in cultured human cells

Uptake of glucose-(3)H into cultured HLM cells was measured. Equilibration of intracellular and extracellular pools occurred after 25 min. Glucose influx was determined subsequently by measuring the glucose-(3)H entering in precisely 1 min. Although saturation kinetics were demonstrated these were not of the simple Michaelis-Menten type. The K(m) of the glucose carrier system is probably about 60 mM glucose. Galactose did not compete with glucose. Insulin stimulated glucose flux without increasing the value of V(max). The stimulation was fully demonstrable after 10 min, could be elicited at concentrations of 10(-4) units/ml, and was absent 2-4 hr after removal. Increasing pH had little or no effect in stimulating glucose flux. Increasing osmotic pressure caused a marked increase and reduced the effect of insulin. Glucose influx was unaffected by anoxia. Glucose influx was increased and the effect of insulin abolished in the absence of K(+). Glucose influx was increased by mercuric chloride, iodoacetate, and fluoride which abolished the effect of insulin. Dinitrophenol decreased the rate of glucose uptake but did not alter the effect of insulin. Phlorizin reduced the rate of glucose uptake and abolished the effect of insulin. ATP and AMP enhanced the rate of glucose uptake. These findings are discussed in relation to the mode of action of insulin.