Characterization of messenger RNA for aldolase B in adult and fetal human liver

High molecular weight cellular RNA was isolated from adult and fetal human liver tissue by a procedure of ethanol precipitation in concentrated guanidine-HCl solutions. About 5 mg of RNA were obtained from one gram of liver. RNA was fractionated by sucrose gradient ultracentrifugation. Aldolase B neosynthesized in a reticulocyte lysate cell-free system under the direction of total or fractionated RNA was purified by immunoaffinity microchromatography. Messenger RNA specifying synthesis of aldolase B exhibited a sedimentation coefficient of 16 S both in adult and fetal liver. This enzyme represented 1.3 % of the total neosynthesized proteins in adult liver, 0.1 % in the liver of a 6-month-old fetus and less than 0.01 % in the liver of a 4.5 month-old fetus.     

Iodine intakes assessed by urinary iodine concentrations in healthy children aged ten months,two years,and four years

Urinary iodine excretion was assessed in 642 healthy children aged 10 mo (n=243), 2 yr (n=183), and 4 yr (n=216) living in the Paris area and originating from continental France (60.3%), North Africa (13.8%), the West Indies (9.1%), West Africa (8.3%), Southeast Asia (4.8%), and southern Europe (3.8%). Mild impairment of neurological (reflexes, tone, audiometry) and intellectual development (Brunet-Lézine scale) was assessed in relation to iodine status. Iodine excretions (median values) were 18.4, 11.9, and 10.9 μg/100 mL at 10 mo, 2 yr, and 4 yr, respectively, and risk of mild iodine deficiency (5–10 μg/100 mL) was 18.1%, 34.8%, and 38.3% for the same age groups. No relationship was found between anthropometry, global development quotient, and iodine status. High hearing thresholds were more commonly associated with lower iodine excretion, suggesting mild hearing defects. In spite of iodine prophylaxis, the risk of mild to moderate iodine deficiency still exists in France and in a number of European countries. Evaluation of neurological sequels of borderline iodine status is a major public health problem in European communities.     

Decreased heme content and cessation of cell growth in cultured chick embryo fibroblasts in the presence of horse serum: Stimulation of heme synthesis and cell growth by iron

A new spectrofluorometric method for heme quantitation in cultured fibroblasts is described. The method includes: (1) heme extraction by methanol/sulfuric acid, (2) partial purification of heme by a microchromatographic method, and (3) treatment of the purified heme by oxalic acid followed by fluorometric quantitation. Using this method, heme concentration was determined in chick embryo fibroblasts cultured in a medium supplemented with either 7% fetal bovine serum (FBS) or 10% horse serum (HS). In the presence of FBS, cultured cells actively divided and cells contained 34–55 pmol heme/mg protein. In contrast, cultures maintained in HS proliferated at a slower rate and contained 23–25 pmol heme/mg protein. The addition of 40 μM FeSO₄ to cultures maintained in the presence of HS stimulated cell proliferation, and the cellular heme concentration increased to 37–51 pmol/ mg protein. These findings suggest that the cessation of growth in the presence of HS may be due to decreased heme content in the cells and that the stimulation of cell growth by iron is mediated by its stimulation of heme synthesis.     

Correlation between cell density,membrane fluidity,and the availability of transferrin receptors in friend erythroleukemic cells

Undifferentiated Friend erythroleukemic cells (FL cells) acquire membrane microviscosity ( ), in accord with the culture cell density. At low cell density poise, whereas at confluency it increases to poise. Concomitantly, the total number of available transferrin receptors per cell decreases by about 80% upon increase in cell density. Modulation of membrane microviscosity, by artificial alteration of the membrane cholesterol level, mediates similar modulations of the availability of the transferrin receptors. The correlation between the availability of the transferrin receptors and the membrane lipid fluidity may take part in the overt decrease in iron uptake by erythroid cells along the erythropoiesis pathway.     

Stereospecific activity of 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphocholine and comparison of analogs in the degranulation of platelets and neutrophils

1-O-Hexadecyl-2-O-acetyl-$\text{sn}$-glycero-3-phosphocholine (platelet activating factor) stimulated the degranulation of rabbit platelets and human neutrophils, whereas the enantiomer, 3-O-hexadecyl-2-O-acetyl-$\text{sn}$-glycero-1-phosphocholine, was inactive. The analogs compared had the following relative potencies in degranulating platelets and neutrophils: 1-O-hexadecyl-2-O-acetyl-$\text{sn}$-glycero-3-phosphocholine > 1-O-hexadecyl-2-O-ethyl-$\text{sn}$-glycero-3-phosphocholine >$\text{rac}$-1-O-octadecyl-2-O-ethylglycero-3-phosphocholine = 1-O-hexadecyl-2-O-methyl-$\text{sn}$-glycero-3-phosphocholine >$\text{rac}$-1-O-dodecyl-2-O-ethyl-glycero-3-phosphocholine. The deacetylated compound, 1-O-hexadecyl-2-lyso-$\text{sn}$-glycero-3-phosphocholine, and 1-O-hexadecyl-2,2-dimethylpropanediol-3-phosphocholine were inactive. The active analogs selectively desensitized the response to each other in the neutrophils. It is suggested that these compounds may activate cells through interaction with a stereospecific receptor.     

Effects of ion-pairing on calculations of ionic activities of major ions in freshwater

Ion-pairing has little effect on ionic activity calculations for weakly mineralized natural water (ionic strength < 2 mM). However, for more strongly mineralized freshwaters, corrections for ion-pairing are necessary if highly accurate ionic activities are required.     

Study of the mechanism of Corynebacterium parvum antitumour activity: Protective effect in mice submitted to sublethal doses of irradiation

Summary The antitumour activity of C. parvum against two different tumours, a lymphosarcoma grafted in XVII mice and a mammary carcinoma grafted in C₃H mice, was a radiosensitive phenomenon. A dose of X-rays as low as 100 rads was sufficient to abrogate the C. parvum-induced protection. The duration of this inhibition increased with augmentation of the X-ray dose. The stimulation of macrophage-phagocytic activity induced by C. parvum was not inhibited by a dose of 500 rads. A chronological parallelism has been demonstrated in the recovery of the C. parvum antitumour effect and the restoration of antibody responsiveness after the suppression of these two activities by 500 rads of X-rays in the case of the C₃H mice grafted with mammary carcinoma cells. No such concomitant recovery has been observed in XVII mice. In these mice, the recovery of C. parvum antitumour activity took place before the restoration of antibody responsiveness.