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Biomedical subjects

C Colette

Publications and source records attributed to C Colette.

At least 91 records · Page 5Linked to original sources
PubMed1982

The influence of indomethacin and possible role of prostaglandins on calcium renal excretion.

Our aim was to evaluate the possible role of prostaglandins (PG) on renal calcium excretion in humans through the PG inhibitory effects of indomethacin. Renal calcium excretion was evaluated by a technique of impulse analysis which gives a function W(t) specific of the tubular calcium transport. Several parameters were derived from this function: (1) the fractional excretion of filtered calcium as % of total dose (FECa % TD); (2) the peak excretion rate, and (3) the mean transit time (MTT, min). The aforementioned parameters were determined in 7 healthy subjects in basal conditions and again after 10 days of treatment with 100 mg indomethacin daily. FECa was significantly (p less than 0.02) higher with indomethacin (8.18 +/- 0.97) than under basal conditions (5.02 +/- 0.57). The peak excretion rate and MTT remained unchanged after indomethacin. These results indicate that indomethacin increases renal calcium excretion. As indomethacin did not produce any significant change in glomerular filtration rate (125 +/- 7 ml/min before vs. 129 +/- 9 ml/min after) one can assume that PG play a role in tubular calcium reabsorption. However, the mechanism remains to be elucidated: direct action or mediated through the cyclic AMP system.

Adolescent↗
PubMed1982

Restored synergistic entero-hormonal response after addition of dietary fibre to patients with impaired glucose tolerance and reactive hypoglycaemia.

Although some dietary fibres (DF) improve glucose tolerance by slowing carbohydrate absorption, other mechanisms are certainly involved. Some of the entero-hormonal responses after DF were investigated in six patients with impaired glucose tolerance and reactive hypoglycaemia. All patients received two different breakfasts, each containing 25 g of starch supplied either as white bread (WB) or a fibre-enriched bread preparation (FB): 4 g hemicellulose and 4 g guar. Metabolic and hormonal responses were evaluated over 5 hours. Compared to WB, the FB had a blunting effect on the resulting blood glucose peak (116 +/- 9 mg/100 ml with FB vs. 148 +/- 15 with WB P less than 0.025) or trough (88 +/- 3 mg/100 ml with FB vs. 79 +/- 5 with WB), and upon the insulin response at 60 min (20 +/- 4 micro U/ml with FB vs. 70 +/- 20 with WB). Gut glucagon immunoreactivity was diminished with FB at 90 min (185 +/- 39 vs. 242 +/- 42 P less than 0.05) and 150 min (180 +/- 39 vs. 242 +/- 40). Pancreatic glucagon was initially similar after FB and WB, but a significant rise was observed with FB at 180 min (116 +/- 17 pg/ml vs. 67 +/- 18 P less than 0.05). The improvement of the blood glucose pattern with DF, especially the suppression of reactive hypoglycaemia, seems to depend partly on reduced and delayed response of the entero-hormonal axis. This in turn results in a better synergistic secretion of insulin and glucagon in the late post-prandial period.

Adult↗
PubMed1982

[The influence of indomethacin and possible role of prostaglandin on renal calcium excretion (author's transl)].

Our aim was to evaluate the possible role of prostaglandins (PG) on renal calcium excretion in humans through the PG inhibitory effects of indomethacin. Renal calcium excretion was evaluated by a technique of impulse analysis which gives a specific index of tubular calcium transport. Several parameters were derived from this specific transport function W(t): 1) the fractional excretion of filtered calcium as % of total dose (FECa % TD); 2) the peak excretion rate; 3) the mean transit time (MTT, min). The aforementioned parameters were determined in 7 healthy subjects in basal conditions and again after 10 days of treatment with 100 mg indomethacin daily. FECa was significantly (P less than 0.02) higher with indomethacin (8.18 +/- 0.97) than under basal conditions : (5.02 +/- 0.57). The peak excretion rate and MTT remained unchanged after indomethacin. These results indicate that indomethacin increases renal calcium excretion. As indomethacin did not produce any significant change in glomerular filtration rate (125 +/- 7 ml/min before v.s. 129 +/- 9 after) one can assume that PG play a role in tubular calcium reabsorption. However the mechanism remains to be elucidated : direct action of mediated through the cyclic AMP system.

Adolescent↗
PubMed1981

[The treatment of certain cases of sterility of infertility associated with an abnormal rise in urinary 17-ketosteroids by using cortisone derivatives (author's transl)].

45 women who were infertile with primary or secondary infertility were studied. The only abnormality that was found was biological, and it was a 24-hour excretion of urinary 17-ketosteroids higher than 35 micromoles. Treatment with cortisone derivatives resulted in 56 pregnancies, which were studied to their term whether it was abortion or delivery. The theoretical and practical aspects, as well as the diagnoses and treatments, are discussed.

17-Ketosteroids↗
PubMed1980

Effects of somatostatin on intestinal calcium absorption in man with primary hyperparathyroidism.

Eight patients suffering from primary hyperparathyroidism were studied in basal conditions, i.e. during a saline infusion and under somatostatin administration (a 250 micrograms bolus injection followed by continuous infusion of 500 micrograms per hour over 240 min). The calcium metabolism was estimated from (i) concentrations of plasma calcium, phosphorus, 25-hydroxyvitamin D (25-OH-D), iPTH and (ii) intestinal calcium absorption determined by a double radiotracer technique using oral 47Ca and IV 45Ca. The results show that somatostatin produced no significant change in calcium, phosphorus, 25-OH-D or iPTH levels. On the contrary, the fractional absorption of calcium (FA Ca), expressed as a percentage of the total oral dose and measured at 30 minute intervals over 240 min, was significantly depressed with somatostatin during the first 2 hours. Beyond the second hour FA Ca remained slightly depressed with somatostatin, but was not significantly different from the basal conditions. From the present results, we conclude that somatostatin slows down calcium absorption, while the total amount of calcium absorbed at the completion of the absorption process is not significantly diminished. Furthermore, as 25-OH-D and iPTH remained unchanged, somatostatin seems to have no effect on the hormonal control of calcium absorption. Therefore, we suggest that somatostatin has only a mechanical effect on calcium absorption, slowing down the intestinal transit.

Calcifediol↗
PubMed1980

Evidence and mechanism for pectin-reduced intestinal inorganic iron absorption in idiopathic hemochromatosis.

The intestinal absorption of iron was measured in 13 patients suffering from idiopathic hemochromatosis by using a double radiotracer technique. For each patient, iron absorption was determined in the fasting state, i.e., under basal conditions, and after an oral indigestible fiber load (9 g/m2 of body surface) with either pectin (group I: eight patients) or cellulose (group II: five patients). The results were compared with those from a group of seven normal control subjects investigated under basal conditions. The patients with haemochromatosis (groups I and II) had a significant increase in the basal value of fractional iron absorption as compared with controls. In the patients of group I, the pectin induced a significant fall in fractional iron absorption (P less than 0.02). In group II, iron absorption rates remained unchanged whether or not cellulose was given. Furthermore, we found in vitro that pectin had a high iron binding activity, while cellulose bound none. From the present study, we conclude that pectin but not cellulose reduces iron absorption by forming unabsorbable complexes with dietary iron. Thus, enrichment of the diet with foods providing significant amounts of noncellulosic dietary fibers, such as pectin, may be useful in the management of hemochromatosis patients.

Adult↗
PubMed1980

Evidence for 25-hydroxyvitamin D deficiency as a factor contributing to osteopenia in diabetic patients with idiopathic haemochromatosis.

Osteopenia is frequently encountered in the course of idiopathic haemochromatosis. In order to establish the mechanism of this bone disorder, the following parameters were studied in nine diabetic patients wih idiopathic haemochromatosis: (i) the intestinal calcium absorption measured by using a double radiotracer technique; (ii) the bone mineral content (BMC, mg/cm2) determined on the forearm by the Cameron's absorptiometric technique, (iii) the plasma 25 hydroxyvitamin D (25-OH-D ng/ml) by a competitive protein-binding radioassay. The results were compared to those obtained in ten controls and in eight diabetics without haemochromatosis. The patients suffering from haemochromatosis had a significant fall in total fractional absorption of calcium and BMC as compared with controls and diabetics without haemochromatosis. Furthermore plasma 25-OH-D was significantly lower in haemochromatosis patients (5.1 +/- 0.6 ng/ml) than in controls (16.4 +/- 1.3 ng/ml, P less than 0.01) and in diabetics without haemochromatosis (14.2 +/- 1.4 ng/ml, P less than 0.02). These results indicate that haemochromatosis patients exhibit important disturbances in calcium homeostasis, i.e. low concentration of plasma 25-OH-D and reduced intestinal absorption of calcium. The latter abnormalities may well be related to the bone rarefaction observed in these patients.

Adult↗
PubMed1980

[Recent advances on vitamin D (author's transl)].

Our knowledge of vitamin D metabolism has undergone major advances within the last few years. The vitamin D3 produced by the skin or absorbed across the intestine is converted successively to 25-hydroxyvitamin D3 by the liver and to 1,25-hydroxyvitamin D3 (1,25-(OH)2D3) by the kidney. The latter metabolite is also the most active on three types of target tissue: gut, bone and kidney. The mechanism of action of 1,25-(OH2D3 has been investigated mostly in the intestinal tract, where it increased calcium absorption by stimulating the synthesis of such transfer proteins as the calcium binding protein (Ca BP). Although the level of 1,25 (OH)2D3 is regulated by vitamin D intake, it depends mainly on renal hydroxylation, the limiting step which controls 1,25-(OH)2D3 production. Both parathyroid hormone and calcium or phosphorus depletion stimulate renal 1-alpha-hydroxylase; 1,25-(OH)2D3 is also regulated directly or indirectly (through its action on the parathyroid glands) by a feedback system. In some diseases such as hepatic insufficiency and chronic renal failure, a profound impairment in endogenous synthesis of the biologically active metabolites of vitamin D results in sever calcium and skeletal disese. During the last decade, the therapeutic possibilities in vitamin D deficiency have been greatly improved by the synthesis of new derivatives of vitamin D and by a better knowledge of their bioavailability

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1978

Intestinal and renal handling of calcium in human diabetes mellitus: influence of acute oral glucose loading and diabetic control.

The intestinal absorption and the urinary excretion of calcium were compared in two groups of diabetic patients during periods of satisfactory and poor control. In a first group of ten patients, periods of isolated high glycosuria were obtained by giving an oral glucose load. The second group consisted of ten patients with a severe endogenous insulin deficiency. The subjects of this latter group were investigated before and after a few days of insulin therapy. In group I, the oral glucose load induced a significant increase in the intestinal calcium absorption and had a tendency to lower the urinary calcium excretion. Furthermore, an inverse relationship was found between the changes in the intestinal calcium absorption and the variations of the urinary calcium excretion. In group II, both intestinal absorption and urinary excretion of calcium fell significantly after recovery of satisfactory metabolic control by insulin therapy. From the results as obtained in group I one can conclude that glucose enhances the calcium transfer from the luminal to the serosal pole of both intestinal and renal tubular cells. During severe ketosis as observed in group II, calcium metabolism is considerably accelerated and the increase in the intestinal calcium absorption rate may be interpreted as compensatory mechanism for the high urinary loss of calcium.

Adolescent↗
PubMed1977

[Dynamic study of tissue circulation in the cervix uteri and the prognosis of the newborn infant].

A new machine has been developed to measure heat dissipated in the tissues especially by convection linked to the blood flow. Its use is simple and without any danger as far as application to the pregnant cervix goes. New discoveries are presented. A new concept of the micro-circulation is considered together with the consequences. The practitioner may be able to draw conclusions as to the prognosis, as to whether a small-for-dates fetus together with or without premature labour is likely. This depends on the tracings obtained which register the intrinsic activity of the periarteriolar muscles.

Cervix Uteri↗
PubMed1975

[Study of soluble proteins from human amniotic fluid by fraction chromatography (author's transl].

The nature and origin of soluble proteins from human amniotic fluid have been investigated by gel filtration chromatography on Sepharose 6B and ion-exchange chromatography on Ecteola-cellulose. Each fraction has been studied by immunoelectrophoresis. Specific antisera against serum proteins, amniotic fluid proteins, fetal proteins and salivary proteins have been used. These various antisera showed that the amniotic fluid contains maternal proteins, but also more specific proteins from fetal origin such as beta2-microglobulin, urinary mucopolysaccharides, salivary proteins and carcinoembryonic antigen. These results not only confirm that amniotic proteins are essentially from maternal origin, but prove the important fetal contribution and emphasize the importance of the fetoplacental unit in the monitoring of high risk pregnancies.

Amniotic Fluid↗