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Biomedical subjects

M Leclercq

Publications and source records attributed to M Leclercq.

At least 19 recordsLinked to original sources

Three electrophoretic techniques comparison for des-gamma-carboxyprothrombin detection.

Des-gamma-carboxyprothrombin (DCP) is a marker that appears in the blood when modifications of vitamin K-dependent proteins carboxylation cycle occur. About 280 human plasma samples of diverse origins were tested by three different electrophoretic techniques for the evaluation of DCP: rocket immunoelectrophoresis (RIE) before and after barium carbonate adsorption, crossed affinoimmunoelectrophoresis (CAIE) and polyacrylamide gel electrophoresis in presence of calcium lactate followed by immunoblotting (PAGE-blot). A good correlation was found between CAIE and PAGE-blot in the CAIE detection limit, but not between RIE and the two other techniques. PAGE-blot was more sensitive than RIE and CAIE and allowed reliable quantification of abnormal prothrombin in plasma.

Adsorption

Hepatic concentration of vitamin K active compounds after application of phylloquinone to chickens on a vitamin K deficient or adequate diet.

Liver and serum concentrations of vitamin K active compounds were measured in two groups of (deficient and normal) broilers after administration of phylloquinone 1 mg/kg. Assays were performed by HPLC after extraction and purification of these compounds. The only menaquinone found in the chicken was menaquinone-4. In the deficient group, the chickens exhibited hepatic concentrations of vitamin K1, vitamin K1 epoxide and menaquinone-4 markedly lower than those of the control group. After administration of phylloquinone, vitamin K and vitamin K epoxide levels fell sharply. There is no hepatic storage of vitamin K comparable to that of vitamin A. However, while menaquinone levels were found to be stable in the control group, they rose significantly in the deficient group after vitamin K injection. The question is: is there a transformation of vitamin K into menaquinone and/or is there a preferential utilization of one of the vitamin K active compounds?

Animals

Impairment of gamma carboxylation of circulating osteocalcin (bone gla protein) in elderly women.

Osteocalcin, also called bone gla protein, is a unique noncollagenous protein of the extracellular matrix of bone that circulates in blood. Oseteocalcin contains three residues of the vitamin K-dependent gamma-carboxyglutamic acid (gla) responsible for the affinity of osteocalcin for bone mineral. In animals treated with the vitamin K antagonist warfarin, the osteocalcin content of bone is markedly reduced and the fraction of osteocalcin released into the circulation is increased. Most studies have shown that osteocalcin increases with aging in women, reflecting an increase in bone turnover, especially after the menopause. To determine if this increase in osteocalcin could be associated with impaired carboxylation, we measured total and noncarboxylated osteocalcin in the serum of 72 women of various ages: 22 premenopausal (31 +/- 7 years old), 20 early postmenopausal (54 +/- 3 years), and 30 elderly women (85 +/- 8 years). As previously reported, total serum osteocalcin was significantly increased in early postmenopausal and elderly women. Noncarboxylated serum osteocalcin was slightly increased in early postmenopausal women (0.95 +/- 0.4 versus 0.65 +/- 0.5 ng/ml in premenopausal women), markedly elevated in elderly women (1.59 +/- 1.1 ng/ml, p less than 0.001), and correlated with age (r = 0.47, p less than 0.001). Elderly women had values of the same magnitude as in 10 patients on chronic warfarin therapy (1.94 +/- 1.1 ng/ml). As a consequence, the increase in carboxylated serum osteocalcin was significant in early postmenopausal women but not in elderly women. Serum levels of vitamin K1 and of menaquinones 6, 7, and 8 were measured in some of the young and elderly women.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult

Humoral antibody response to bovine leukemia virus infection in cattle and sheep.

In this study, 345 cattle from 7 herds with a history of lymphosarcoma were tested for antibody to BLV antigens by three serological methods, namely immunodiffusion using a bovine leukemia virus glycoprotein with a molecular weight of 60,000 as antigen, and radioimmunoassay using a bovine leukemia virus glycoprotein with a molecular weight of 60,000 and a bovine leukemia virus protein with a molecular weight of 24,000 as antigen. The three tests under comparison agreed for 335 animals, 240 being negative in the three tests, and 95 being positive. Results were variable in ten cases only. Glycoprotein with a molecular weight of 60,000 antibody titers were systematically higher than were protein with a molecular weight of 24,000 antibody titers in bovine sera and milk, as well as in sera of experimentally infected sheep. In the latter case, antibodies to bovine leukemia virus antigens reached maximal values at the animal death in the tumor phase of the disease. Ratios of serum antiglycoprotein titer to milk titer varied between 4 and 117, showing that, if milk pools are to be used in surveys of bovine leukemia virus infection, use of very sensitive techniques of detection is mandatory.

Animals

The different electrophoretic forms of post gamma-globulin their antigenic identity and their structural variability.

Post gamma-globulin, first described as a constant component of protein of cerebrospinal fluid and urine from patients with tubular disorders has also been found in other biological fluids. Post gamma-globulin from a single individual always migrated as several bands after storage. Three electrophoretic forms, immunochemically identical, have been isolated by gel chromatography, preparative continuous flow electrophoresis and ion-exchange chromatography. Their molecular weight was found to be approximately between 11 000 to 12 000. No difference between the three forms could be detected. The N-terminal amino acids were found to be Lys, Arg and Leu respectively for the three forms of post gamma-globulin. The "slow" and "fast" forms of post gamma-globulin seemed to differ by elimination of small basic peptides or amino acids from the N-terminal end of the protein. No enzymatic activity of post gamma-globulin was found, but this requires further investigations.

Amino Acids