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Biomedical subjects

C Simon

Publications and source records attributed to C Simon.

At least 325 records · Page 18Linked to original sources
PubMed1980

Serum concentrations of vitamin E in healthy infants fed commercial milks.

Serum vitamin E concentrations were determined in 60 term and 26 premature infants during the first 2 months of life. All infants received commercial milk formula containing vitamin E. In addition, premature infants older than 10 days were given vitamin E orally as a multivitamin preparation. Thus, daily intake of vitamin E was nearly 1.2 mg/kg body weight in term infants and 2--3 mg/kg body weight in premature infants. In term infants serum levels of vitamin E rose from 2.6 mg/l (cord blood) to 7.0 mg/l (3rd--13th day) and 9.1 mg/l (16th--25th day) and remained at 10 mg/l (in the second month of life). Hemoglobin concentration and red cell number decreased continuously due to physiological anemia of infancy. In premature infants mean values of vitamin E were the same as in term infants. Vitamin E deficiency with hemolytic anemia could be demonstrated in a 2 months old infant suffering from cystic fibrosis.

Anemia, Hemolytic↗
PubMed1980

Association of an axonally transported polypeptide (H) with 100-A filaments. Use of immunoaffinity electron microscope grids.

Polypeptide H (mol wt 195,000) is axonally transported in rabbit retinal ganglion cells at a velocity of 0.7--1.1 mm/d, i.e., in the most slowly moving of the five transport groups described in these neurons. To identify the organelle with which H is associated, we purified H, prepared antibodies directed against it, and adsorbed the antibodies onto Formvar-coated electron microscope grids. When the resulting "immuno-affinity grids" were incubated with extracts of spinal cord and then examined in the electron microscope, they contained as many as 100 times more 100-A filaments than did grids coated similarly with nonimmune IgG. The ability of the anti-H IgG to specifically adsorb filaments to grids was completely blocked by incubating the IgG with polypeptide H. The 100-A filaments adsorbed to anti-H immunoaffinity grids could be specifically decorated by incubating them with anti-H IgG. These observations demonstrate that H antigens (and most likely H itself) are associated with 100-A neurofilaments. In addition, they suggest that the use of immunoaffinity grids may be a useful approach for determining the organelle associations of polypeptides.

Animals↗
PubMed1980

Inhibitory effects of tunicamycin and 2-deoxyglucose on thyroglobulin synthesis.

The kinetic incorporation of labelled sugars and amino acids by rat thyroid hemilobes was measured in the presence of 2-deoxyglucose and tunicamycin, inhibitors of the glycosylation of glycoproteins. With either inhibitor the carbohydrate content of exocytosed thyroglobulin was only slightly decreased (less than 20% of control) whereas the rate of exocytosis was strongly inhibited (by 60-80%). As no intracellular accumulation or proteolysis of non-glycosylated molecules was detected, the reduced rate of thyroglobulin release seems essentially due to a decrease in protein synthesis. In a whole cell system (hemilobes), it is impossible to uncouple glycosylation and protein synthesis by incubation with tunicamycin; 50 micrograms/ml tunicamycin for 270 min inhibited total [3H]-glucosamine and 14C-labelled amino acid incorporation by 65% and 33% respectively. This can be contrasted with cell-free incubation of thyroid rough microsomes where glycosylation was blocked by the same tunicamycin concentration (90% inhibition of N-[3H]acetylglucosamine transfer from UDP-N-[3H]acetylglucosamine) whilst ongoing protein synthesis was not significantly modified (less than 4% inhibition). This clearly suggests that, in thyroid follicular cells, a regulatory link exists between the synthesis of the peptide moiety of a glycoprotein and its glycosylation.

Amino Acids↗
PubMed1980

Occlusion pressure-response in patients with chronic obstructive lung disease.

Occlusion pressure (P100) at rising inspiratory CO2 concentration was measured in 9 healthy adults and in two groups of patients with chronic obstructive lung disease, of which 29 had an arterial CO2 tension (PaCO2) of less than 43 mm Hg and 15 a PaCO2 of more than 43 mm Hg. Statistically the three groups could be separated significantly from each other in terms of occlusion pressure at rising alveolar CO2 tensions (PACO2). At a standard endexpiratory PACO2 of 60 mm Hg the absolute values of P100 of the obstructive patients with a normal PaCO2 are significantly higher than those of the two other groups. The differences in ventilatory response between the three groups are discussed.

Adult↗
PubMed1980

Intrafollicular re-cycling of organic iodine in the hypophysectomized rat as observed by a long-term kinetic study.

A long-term kinetic study was started 8 days after hypophysectomy in rats previously adapted to receive 5 micrograms iodide daily, and maintained on the same diet after surgery. At each time, the renewed fraction for thyroglobulin (Tg) and lysosomes in the gland, and hormones in the plasma was calculated by the method of isotropic equilibrium. All the pools studied are renewed very slowly, but with different kinetics. Between time zero and the 25th day of the experiment, the renewed fraction in plasma hormones always exceeds that of Tg. Thus, in hypophysectomized rats, Tg pool is composed of at least two compartments with different turn-over rates. Tg molecules of both compartments are endocytosed, but that of the faster compartment participate in secretion in a preferential way. Peeling of the data for the 60-day period of experiment confirms these results. In addition, peeling demonstrates a 15-day delay in the turn-over of the second compartment. Such a delay was not found in the turn-over of this compartment in lysosomes. Thus, we may again postulate, in hypophysectomized rats, a recycling of iodine in organic form from the lysosomes back to the luminal colloid, as previously porposed for control rats.

Animals↗