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Biomedical subjects

M Gruson

Publications and source records attributed to M Gruson.

At least 19 recordsLinked to original sources
PubMed1988

Osteocalcin and bone morphometric parameters in adults without bone disease.

Serum bone Gla-protein (s-BGP or osteocalcin) and other serum biochemical parameters were measured in 19 subjects (8 women and 11 men, aged 20-82 years) without any bone disease. Each subject simultaneously underwent an iliac crest biopsy; tetracycline double-labeling was performed in 11 subjects, allowing correlations between s-BGP and bone histomorphometric parameters. s-BGP was significantly correlated with static bone parameters: trabecular bone volume (r = 0.74; P less than 0.001), osteoid surfaces (r = 0.69; P less than 0.001), osteoblastic surfaces (r = 0.68; P less than 0.002); dynamic bone formation parameters: total labeled surfaces (r = 0.72; P less than 0.01); and the bone formation rate (r = 0.69; P less than 0.01). We conclude that s-BGP is a valuable marker for evaluating bone formation in healthy adult subjects.

Adult↗
PubMed1986

Relationship between bone GLA-protein (BGP) and calcidiol (25-hydroxycalciferol) in serum of breast-fed infants.

The aim of this investigation was to study the bone metabolism in early infancy by establishing the relationship between serum osteocalcin levels and the hormonal vitamin D status of exclusively breast-fed infants during their first month of life. Calcium, phosphorus, alkaline phosphatase, 25-hydroxycalciferol (calcidiol), 1,25-dihydroxycalciferol (calcitriol) and osteocalcin (BGP or GLA-protein) were measured in 22 healthy lactating women and their paired breast-fed infants before and after supplementation (400 IU vitamin D per day). Prior to supplementation calcidiol, calcitriol and osteocalcin remained unchanged. Following supplementation there was an increase in all the parameters with the exception of calcitriol. The administration of vitamin D to breast-fed infants should in fact have an effect on bone activity as reflected by the increase in osteocalcin levels.

25-Hydroxyvitamin D 2↗
PubMed1983

Effect of 1 alpha, 24 R,25-trihydroxycholecalciferol on isolated parathyroid cells secretion.

In this work we have studied the action of the trihydroxylated vitamin D metabolite (1 alpha, 24 R,25(OH)3D3) on parathyrin secretion by isolated parathyroid cells. In contrast with the results obtained with mono and dihydroxylated vitamin D, 1 alpha, 24 R,25(OH)3D3 increased the secretion of parathyrin. The effective concentration of this metabolite was 1.54 X 10(-9)M for cells rat and 1.54 X 10(-10)M for human cells.

Animals↗
PubMed1982

Comparative effects of some hydroxylated vitamin D metabolites on parathyrin secretion by dispersed rat parathyroid cells in vitro.

We have previously discussed the action of 1 alpha,25-(OH)2D3, (24R) 24,25-(OH)2 D3 and (25S) 25,26-(OH)2D3 on parathyrin secretion by isolated rat parathyroid cells. In this work, we have compared these effects with those obtained with 1 alpha-OH D3, 25-OH D3 and 1 alpha-OH D2. In decreasing order, the activities were: 1 alpha,25-(OH)2D3 greater than 1 alpha-OH D3 greater than (24R) 24,25-(OH)2D3 greater than 25-OH D3 greater than (25S) 25,26(OH)2D3 greater than 1 alpha-OH D2. The presence of two hydroxyl groups with one hydroxyl group in alpha position seems to have the higher activity to inhibit the parathyroid secretion. At least, the nature of the side chain conformation also plays a part upon the effect of PTH release.

24,25-Dihydroxyvitamin D 3↗
PubMed1981

[Effects of the dihydroxyl metabolites of vitamin D3 and their ethanol solvent on parathyroid secretion: in vivo study in the rat].

The regulation of parathyroid secretion by the vitamin D3 dihydroxylated metabolites was studied by differents authors. In vitro experiments showed that 1 alpha (OH)2 D3 and 24 R 25 (OH)2 D3 inhibited the PTH release. In Rats maintained in a normal calcium diet or calcium and/or vitamin D deficient diet, 1 alpha 25(OH)2 D3 and 24 R 25 (OH)2 D3 inhibited the PTH release, whereas 24 S 25 (OH)2 D3, 25 S 26 and 25 R 26(OH)2 D3 had no effect.

Animals↗
PubMed1981

Metabolism of human femoral head cartilage in osteoarthrosis and subcapital fracture.

The cell density and incorporation of 35SO4 and 3H-glycine into human articular cartilage from 8 osteoarthrotic and 7 normal (subcapital fracture) femoral heads were studied. It was found that osteoarthrotic cartilage incorporates on a per cell basis about twice as much 35SO4 and 2--5 times as much 3H-glycine as normal cartilage. There was no relationship between the intensity of incorporation and either the location of the cartilage (weight-bearing versus non weight-bearing areas) in normal cartilage or the degree of damage (normal-like, fibrillated, and ulcerated) in osteoarthrotic articular cartilage. In the latter tissue the increased synthetic capacity of the cells seems to be a diffuse rather than a localised process, for it was also found in cartilage from peripheral osteophytes. Histo-autoradiographic studies showed that the osteoarthrotic chondrocytes are metabolically hyperactive all over the femoral head, including wedge-shaped margins of the zone of exposed bone. These results support the hypothesis that much of the articular cartilage from osteoarthrotic femoral heads is of an immature chondroblastic type. It is suggested that de-novo synthesis of articular cartilage occurs during the process of regional remodelling of the femoral head, which would account for the observed hyperactivity.

Aged↗
PubMed1978

Increased metabolic activity of rabbit articular cartilage in vitro.

The metabolic, histochemical and ultrastructural modifications induced in rabbit articular cartilage during in vitro incubation at 37 degrees C, for various periods (10 min to 18 h), using Krebs phosphate-glucose nutrient medium, were studied. It was found that after only 10 min of incubation, the chondrocytes increase their synthesis of matrix macromolecules for, at least, the next 6 h. This was suggested by: 1. Increased incorporation 35S-sulfate and 3H-glycine during the first 6 h of incubation. 2. An intensification of metachromasia, which also spread out into the superficial layer that is normally orthochromatic. Only the most superficial layer corresponding to one or two rows of the cells, retained its staining pattern throughout the incubation; 3. A rapidly acquired abundant rough endoplasmic reticulum, enlarged Golgi area and numerous newly synthesized proteoglycan molecules. This study poses fundamental questions about the mechanisms that regulate matrix synthesis by the chondrocytes.

Animals↗
PubMed1975

[Strontium and calcium metabolism. Interaction of strontium and vitamin D].

Oral administration of strontium to calcium wellfed rats blocks the intestinal absorption of calcium. When high doses of vitamine D are given over long period, the inhibition of calcium intestinal absorption disapears. Under these conditions the absorption of strontium is increased. It is suggested that there is only one absorption mechanism for these two cations. An overdose of the vitamine D increases the renal elimination of strontium but under these conditions the plasma concentration of the strontium is unchanged. Vitamine D brings about the some action on the bone fixation of the strontium as it does on the bone fixation of calcium. The bone fixation is increased with low dosages. The bone fixation is decreased with high dosages.

Animals↗