Assessment of the aluminum overload and of its possible toxicity in asymptomatic uremic patients: evidence for a depressive effect on bone formation.
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Adult↗
Biomedical subjects
J Gueris
Publications and source records attributed to J Gueris.
[Inorganic pyrophosphates and parathormone in hypophosphatasia. Study of a family].
The serum concentration of parathormone is usually normal in hypophosphatasia, a rare disease with a defect of bone mineralisation and low serum alkaline phosphatase activity. Nevertheless there are three cases in the literature presenting a hyperparathyroidism with or without hypercalcemia. No anomaly of parathyroid was found at autopsy. The authors describe the first cases of hypophosphatasia with low serum concentration of parathormone and raise the possibility of a trouble in the calcium-parathormone feed-back. They also emphasize the interest of the urinary pyrophosphate excretion. Its increase seem to be the most constant and the most specific biological disorder.
Adult↗
Influence of biochemical and hormonal factors on the bone histomorphometric features of uraemic patients.
A multidimensional analysis was used to evaluate, the influence on bone histology of various biochemical and hormonal factors in 20 uraemic patients on chronic haemodialysis or haemofiltration. A positive relationship (p less than 0.1) was found between PTH and osteoclastic and osteoblastic surfaces but not with mineral apposition and bone formation rates. The mineral appositional rate which reflects the cellular activity of osteoblasts was positively related to D metabolites 25(OH)D3 and 1,25(OH)2D3 and to phosphate (p less than 0.1). Mineral appositional rate and bone formation rate were negatively related to bone aluminium (p less than 0.05). These data indicate that: 1) PTH simulates bone turnover but has no direct effect on the bone cellular activity of osteoblasts which is mainly dependent on D metabolites and phosphate; 2) mild aluminium overload not severe enough to cause osteomalacia decreases bone formation in uraemic patients. This study evaluates the role of various simultaneously measured biochemical and hormonal factors on bone histological parameters in uraemic patients.
Adult↗
[Primary hyperparathyroidism. Lack of effect of cimetidine on plasma levels of parathyroid hormone and calcium].
Because of the contradictory results formerly published as regards the effect of cimetidine in primary hyperparathyroidism, we have studied the effect of cimetidine at the daily dose of 1200 mg in 14 cases of primary hyperparathyroidism. The diagnosis was ascertained in all cases by the coexistence of an otherwise unexplained hypercalcemia and of a concomitantly elevated plasma concentration of immunoreactive parathyroid hormone (PiPTH) measured by 2 different antibodies and confirmed in 10 cases by surgical neck exploration. In 5 cases with severe hypercalcemia (greater than 12.0 mg/l) cimetidine was discontinued after 5 days because of its lack of effect on both plasma concentrations of calcium and PiPTH, and the patients were successfully operated. In 8 cases with milder hypercalcemia, cimetidine was given for 1.5-6 months. There was no significant change in both plasma concentrations of calcium (PCa) and PiPTH but a regression analysis showed that PCa was negatively correlated to time with a correlation coefficient which would have become significant if the follow-up had been 9 months. In the last patient severe hypercalcemia was controlled by simultaneous administration of phosphate, indomethacin and cimetidine without concomitant decrease of PiPTH; and 6 weeks after cimetidine discontinuation no significant increase of PCa and PiPTH occurred. These data show that cimetidine has no clinically therapeutic value in primary hyperparathyroidism.
Adolescent↗
[Inhibin and cyberning].
Inhibin is a peptidic gonadal hormone which preferentially suppresses FSh secretion and synthesis. As its purification is not yet achieved, only bioassays are available, performed with testicular extracts or follicular fluid. Its secretion by granulosa cells and Sertoli cells is partly spontaneous, partly stimulated by androgens and FSH. In women, folliculogenesis is controlled by inhibin induced FSH fluctuations. But inhibin acts also at the gonadal level like the cybernis, peptidic substances secreted by the ovary, which modulate ovarian effects of gonadotrophins. Five of them have been identified : the oocyte maturation inhibitor, the luteinization inhibitor, the FSH binding inhibitor (implied in follicular atresia), the LH receptor binding inhibitor (involved in luteolysis), and gonadocrinins (which bind to ovarian LHRH-receptors). The discovery of these ovarian peptides leads to new concepts in folliculogenesis and luteolysis and may provide a new therapeutic approach in contraception and sterility fields.
Animals↗
Evidence for defective osteoblastic function. A role for alcohol and tobacco consumption in osteoporosis in middle-aged men.
In a group of 11 men ranging in age from 35 to 50 years with idiopathic osteoporosis, most were mild alcoholics and heavy smokers. Two had absorptive hypercalciuria. Histomorphometry showed that the patients had low trabecular bone volume and mean trabecular thickness when compared with age-matched control subjects. Mean wall thickness was also markedly reduced in patients as compared with control subjects. The quantity of resorbed bone was extrapolated from the calculated mean interstitial bone thickness. Resorption was not significantly different in patients and control subjects. Consequently, in this group of patients with severe osteoporosis, the pathogenesis was characterized by markedly decreased bone formation.
Adult↗
[Exploration by high-resolution real-time ultrasonography of the parathyroid glands in 60 chronic hemodialysis. Preliminary results and comparison with other indices of secondary hyperparathyroidism].
Systematic study by high resolution real time ultrasonography of the parathyroïd glands unequivocally showed parathyroid hyperplasia in 13% of 60 patients on chronic hemodialysis. Hyperplasia was associated with greater severity of hyperparathyroidism, as demonstrated by subperiostal bone resorption and increased serum levels of alkaline phosphatase, parathormone and calcium. Correlation between ultrasonographic and surgical findings in 5 patients was excellent, and actual weights of removed hyperplastic glands were correlated to calculated volumes. The demonstration of hyperplastic parathyroid glands by ultrasonography was of great help for surgical indication in cases where the classical biochemical and radiological parameters were unavailable or of uncertain significance. In absence of hypercalcemia and/or of hyperphosphoremia which may hinder "medical parathyroidectomy" by vitamin D metabolites, ultrasonographic demonstration of hyperplastic glands represents an unresolved problem as to the choice of surgical or medical parathyroidectomy.
Adult↗
Substitution of aluminium hydroxide by high doses of calcium carbonate in patients on chronic haemodialysis: disappearance of hyperaluminaemia and equal control of hyperparathyroidism.
Al(OH)3 was discontinued in 26 patients on chronic haemodialysis as well as vitamin D metabolites in eight. Oral CaCO3 was progressively increased from 4 +/- 3 to 10 +/- 5g/d to keep plasma PO4 less than 6.0mg/dl and P Ca less than 10.5mg/dl. This treatment had to be discontinued in three cases because of diarrhoea and/or uncontrolled hyperphosphataemia. In the remaining patients the control of hyperphosphataemia and of PTH values was as good or even better. Hyperaluminaemia disappeared in most patients demonstrating the role of oral Al(OH)3 in the induction of hyperaluminaemia. Because of frequent transient hypercalcaemia and of the occurrence of vascular calcification in two patients, high doses of CaCO3 after discontinuation of Al(OH)3 are advised only in cases of hyperaluminaemia.
Aluminum↗
Effects of oral cimetidine on parathyroid hormone and calcitonin plasma levels in uremic patients.
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Administration, Oral↗
Nonosteomalacic osteopathy associated with chronic hypophosphatemia.
We studied bone histomorphometry in 19 patients with chronic hypophosphatemia related to an idiopathic renal phosphate wasting and without histological osteomalacia. Nine patients had renal lithiasis (group 1), three had radiological osteoporosis (group 2), and seven had lumbar pain (group 3). In the whole group of 19 patients, serum phosphate levels were low (24.9 +/- 2.1 mg/l), calcium in blood was normal, calcium in urine was increased, and iPTH was low. Histomorphometric data showed decreased osteoblastic surfaces with normal resorption surfaces, normal osteoid volume and calcification front. There was no correlation between serum phosphate level and histomorphometric parameters. There was no statistical difference between the data of the 3 groups of hypophosphatemic patients. We concluded that chronic hypophosphatemia in the adult doses not always lead to osteomalacia but to an unusual osteopathy characterized by an osteopenia due to an isolated decrease in bone formation. The respective importance of phosphate deficiency and of decreased iPTH level in the pathogenesis of this osteopathy is uncertain.
Adult↗
Possible link between changes in plasma 24,25-dihydroxyvitamin D and healing of bone resorption in dialysis osteodystrophy.
Histomorphometric studies of bone biopsies were performed on 12 hemodialyzed patients before and after six months of treatment with 25-(OH) and 1 alpha-(OH) vitamin D3. Patients could be classified into three groups according to bone resorption: Group I with normal bone resorption; Group II with elevated initial bone resorption unresponsive to vitamin D treatment; group III with elevated initial bone resorption sensitive to vitamin D treatment. None of the patients had histological signs of osteomalacia. In Group I, plasma concentrations of 24,25-(OH)2D and the ratio of 24,25-(OH)2D to 25-(OH) D remained in the normal range throughout the study; in Group II these parameters were subnormal initially and did not increase above normal except in one case; in Group III, plasma concentrations of 24,25-(OH)2D were high before or at the beginning of vitamin D administration and normal at the time of the second biopsy and wide variations were observed in the ratio of 24,25-(OH)2D to 25-(OH)D. No difference was found between these last two groups with regard to the cumulative dose of vitamin D derivatives administered or the changes in plasma PTH, CT, calcium and phosphate. These observations suggest a specific regulation of plasma 24,25-(OH)2D concentrations in hemodialyzed patients and a possible link (independent of circulating PTH, CT, or phosphate) between this regulation and healing of bone resorption. However, no correlation was found between plasma 24,25-(OH)2D and either one of the simultaneously measured biochemical or histological parameters.
24,25-Dihydroxyvitamin D 3↗
Calcium phosphate metabolism and bone disease in patients with homozygous thalassemia.
Calcium and phosphate metabolism were studied in 22 patients with homozygous thalassemia. The overall results showed no significant difference for serum calcium, phosphorus, alkaline phosphatase, immunoreactive parathyroid hormone, or 25-hydroxyvitamin D between thalassemic and control children. However, during the winter, serum 25-hydroxycholecalciferol levels were very significantly decreased in thalassemic children. A study of the hands showed thin metacarpal cortices related to increased resorption. Histomorphometric study of four iliac bone biopsies showed normal osteoclastic resorption and decreased bone formation. Prussian blue staining and x-ray electron microprobe analysis showed iron deposits inside the bone. Whether this finding is critical in the pathogenesis of the bone disease in unknown.
Adolescent↗
[Inhibin and cybernins].
Inhibin is a peptidic gonadal hormone which preferentially suppresses FSH secretion and synthesis. As its purification is not yet achieved, only bioassays are available, performed with testicular extracts or follicular fluid. Its secretion by granulosa cells and Sertoli cells is partly spontaneous, partly stimulated by androgens and FSH. In women, folliculogenesis is controlled by inhibin induced FSH fluctuations. But inhibin acts also at the gonadal level like the cybernins, peptidic substances secreted by the ovary, which modulate ovarian effects of gonadotrophins. Five of them have been identified: the oocyte maturation inhibitor, the luteinization inhibitor, the FSH binding inhibitor (implied in follicular atresia), the LH receptor binding inhibitor (involved in luteolysis), and gonadocrinins (which bind to ovarian LHRH-receptors). The discovery of these ovarian peptids leads to new concepts in folliculogenesis and luteolysis and may provide a new therapeutic approach in contraception and sterility fields.
Animals↗
Effects of vitamin D3 dihydroxylated metabolites on parathyroid hormone in the rat. 'In vitro' studies with dispersed rat parathyroid cells.
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24,25-Dihydroxyvitamin D 3↗
[Role of histaminergic H1 and H2 receptors in prolactin release in humans].
Histamine is considered as a neurotransmitter, since it is present in hypothalamus and pituitary gland. It has been reported to stimulate prolactin (PRL) release in rats and humans; it seems to be involved in the control of LH release in rats. But cimetidine, an H2 antagonist also induces PRL release in humans. To investigate the relationship between the PRL secretion and possible histaminergic pathways, the response of PRL and LH was studied for 180 minutes in 10 normal subjects (5 men, 5 women) after H1 antagonist (diphenhydramine 50 mg iv), H2 antagonist (cimetidine 300 mg iv) and placebo. Diphenhydramine and placebo injection resulted in a decrease of PRL from 0800 until 11.00 hours, suggesting a spontaneous diurnal variation. Cimetidine induced a short but significant rise of PRL before a similar diurnal secretory pattern. LH levels were unaffected by H1 and H2 antagonists. These data suggest that PRL and LH secretion in humans is unresponsive to H1 histaminergic pathways. The specific action of cimetidine remains to be defined.
Adult↗
Cimetidine and circulating calciotropic hormone levels in uremic patients: evidence for a suppressive effect on calcitonin secretion.
The effect of oral cimetidine on parathyroid hormone and calcitonin plasma levels was evaluated in 12 uremic patients on chronic hemodialysis. Compliance to treatment was monitored by measuring cimetidine plasma concentrations. Plasma cimetidine was measurable in 7 patients and undetectable in 5. In compliant patients, there was no change in plasma concentration of calcium and parathyroid hormone but a significant fall of 75% in plasma calcitonin levels during treatment, followed by an increase towards initial values after cimetidine discontinuation. No significant change occurred in the other 5 patients. Cimetidine therefore appears to be of little value in the treatment of uremic hyperparathyroidism.
Adult↗
[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↗