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Biomedical subjects

A Michaud

Publications and source records attributed to A Michaud.

At least 55 records · Page 3Linked to original sources
PubMed1985

Renal growth retardation in children: sign suggestive of vesicoureteral reflux?

Of 141 children undergoing surgery for vesicoureteral reflux detected by voiding cystourethrography, preoperative excretory urography demonstrated signs suggestive of vesicoureteral reflux in 154 (67.5%) of 228 refluxing ureter. In 48 refluxing ureters (21%) renal growth retardation was the only sign; the latter was appreciated by applying the index described by Hodson, that is, the ratio of bipolar parenchymal thickness to total renal length. It was concluded that it is important to systematically calculate this simple index from every child's excretory urogram.

Child↗
PubMed1984

Involvement of hemostasis during an autoimmune glomerulonephritis induced by mercuric chloride in brown Norway rats.

Mercuric chloride (HgCl2) induces in Brown Norway (BN) rats an autoimmune disease characterized by a biphasic glomerulonephritis (GN). A transient nephrotic syndrome occurs during the third and fourth weeks after the first HgCl2 injection. Related to nephrotic syndrome, an hypercoagulable state develops with decreased factor XII and anti-thrombin III (AT III) levels and increased factor V activity and fibrinogen concentration. Moreover, during the same period, most of the rats were found thrombocytopenic. The presence of soluble fibrin monomer complexes and of fibrin degradation products (FDP) in the plasma of these rats associated with fibrin thrombi in glomerular capillary lumen proved the occurrence of disseminated intravascular coagulation (DIC). DIC was responsible for the death of several rats but most of these survived and clotting abnormalities were no longer found. Numerous factors can explain the occurrence of DIC in this model: anti glomerular basement membrane antibodies, circulating immune complexes, complement activation and/or glomerular endothelial cell detachment. The HgCl2 induced autoimmune disease appears as a good experimental model to study the relation between coagulation process and glomerulonephritis.

Animals↗
PubMed1984

Mineralocorticoid receptors in the epithelial cells of human colon and ileum.

Specific binding of [3H]aldosterone to the cytosolic fraction of epithelial cells was studied in the human colon and terminal ileum. Analysis of [3H]aldosterone binding to the epithelial cells of ascending colon, caecum and ileum as a function of [3H]aldosterone concentration revealed only one class of specific receptors with an affinity constant of about 2 nmol/l. [3H]aldosterone binding was approximately the same in the sigmoid, descending and transverse colon and in the caecum, but slightly lower in the ascending colon and ileum. The specificity of the [3H]aldosterone binding was the same along the colon. The relative order of potency in inhibiting [3H]aldosterone binding was: aldosterone = SC 26304 = dexamethasone much greater than dihydrotestosterone greater than estradiol = RU 26988.

Aldosterone↗
PubMed1984

Aldosterone binding in the human colon carcinoma cell line HT29: correlation with cell differentiation.

The purpose of the present study is to investigate aldosterone binding to human colon carcinoma HT29 cells. These cells grow as undifferentiated epithelial cells when cultured under standard conditions (Dulbecco's MEM; 10% FCS). Modification of the culture medium induced two types of differentiation: (1) enterocytic differentiation when glucose (25 mM) is replaced by galactose (5 mM) (2) mucus secreting cells in FCS free medium. Aldosterone specific binding was detected in the cytosolic fraction of enterocyte-differentiated cells. This binding corresponded to a single class of sites with affinity, specificity and anion-exchange chromatographic behaviour similar to those observed in the epithelial crypts of human colon. These putative aldosterone receptors were also detected in mucus secreting cells that are derived from the enterocyte-differentiated cells. Enterocytic differentiation appears thus to be a necessary step for the "induction" of aldosterone receptors in HT29 cells.

Aldosterone↗
PubMed1984

Modulation of aldosterone receptors in rat kidney: effects of steroid treatment and potassium diet.

The numbers of type I and type II aldosterone receptors in the kidney cytosol of adrenalectomized rats were estimated after animals were treated with various steroids, or fed with high or low potassium diets. Oestradiol and 5 beta-pregnane-3,20 dione, which exhibited no affinity for aldosterone receptors, did not modify the levels of type I or type II receptors. Cortisol, corticosterone, progesterone and spirolactones, which all competed with aldosterone for both types of receptor, reduced the number of type I sites, as does aldosterone itself. Steroid treatment has no appreciable effect on type II receptors. We conclude that type I receptors are modulated by steroids able to bind to aldosterone receptors and that steroid-receptor interaction is an essential step in the receptor modulation process. The effects of potassium on aldosterone receptor modulation were tested in adrenalectomized rats on hypo- or hyperkalaemic diets. No change in receptor levels was observed in the rats on a low potassium diet, but the number of type I receptors increased in animals on a high potassium diet. However, the effects of potassium on receptor modulation were of lesser magnitude than those of aldosterone agonists and antagonists.

Adrenal Cortex Hormones↗
PubMed1984

Low molecular weight (LMW) heparin derivatives in experimental extra-corporeal circulation (ECC).

Low molecular weight (LMW) heparin has been shown to prevent experimental venous thrombosis. In order to investigate its biological action and its potential use in open heart surgery, we have conducted an experimental study using extracorporeal circulation (ECC) in sheep as an experimental model. 18 sheep were randomly selected to receive either LMW heparin (2 mg/kg), high dose heparin (HD; 160 U/kg), or low dose heparin (LD; 60 U/kg). The HD heparin yielded the same circulating anti-activated factor X (anti-Xa) activities as the LMW heparin and the LD heparin yielded the same anti-thrombin activity. LMW heparin and HD heparin were both effective in preventing blood clotting in the ECC circuit, demonstrating the antithrombotic activity of the LMW heparin. Clotting in the circuit was observed following LD heparin administration showing that the efficacy of LMW heparin does not only rely upon its weak anti-activated partial thromboplastin time (APTT) and anti-thrombin activity. Fibrinogen, fibrinogen degradation products (FDP), factor V (FV), platelet count, antithrombin III (AT III), fast acting antiplasmin (AP) were evaluated during and after ECC. The defects in hemostasis were similar in the three groups. Conclusions were: (1) heparin chain depolymerization diminishes the anti-APTT activity without altering the anti-thrombotic property; (2) LMW heparin is an effective alternative to heparin in cardiac surgery; (3) the absence of postoperative circulating anti-APTT activity might be associated with a reduced incidence of hemorrhagic complication, but we were not able to demonstrate it.

Animals↗
PubMed1984

[Computerized retrospective study of 141 children operated on for vesico-ureteral reflux].

Follow-up study of 141 cases of vesico-ureteric reflux (less than 10 years old) treated by Cohen's method. Computerized study, 5 years after treatment, with analysis of the influence of different parameters (type of VUR, age, sex, urinary infection or not, space of time between diagnosis and treatment) on the renal parenchymal radiographic measurements ( Hodson 's method). The youngest is the child when he is treated, the best is the functional result.

Age Factors↗
PubMed1981

Effect of adrenalectomy and aldosterone on the modulation of mineralocorticoid receptors in rat kidney.

Adrenalectomized rat kidney is commonly used for the study of mineralocorticoid mechanism of action in mammals. In this model, aldosterone is known to bind to two classes of binding sites: type I (mineralocorticoid) and type II (glucocorticoid). The study of the aldosterone binding in normal rat kidney requires the elimination of endogenous hormones bound to each type of receptor. Thus, a suitable technique was developed using in situ perfusion of the kidneys. The efficacy of this method was of about 85 to 90% at the level of both cytoplasm and nucleus. Aldosterone binding capacity was checked in normal rat kidney after in situ perfusion and was found to be 300 to 500% lower than in adrenalectomized rat kidney, both in cytoplasm and nuclei. Computer analysis of aldosterone binding parameters in the cytoplasm (30,000 X g supernatant) of rat kidney suggested that adrenalectomy might induce an important rise in the number of mineralocorticoid receptors (congruent to 260%). An increase in the number of glucocorticoid receptors was also observed but appeared to be lower. Aldosterone, when perfused during 24 h in adrenalectomized rats, lowered the number of type I sites to the same level as observed in normal rat kidney. This effect was fully reversible after interruption of aldosterone perfusion. These results suggested an aldosterone-induced down regulation of mineralocorticoid receptors.

Adrenalectomy↗
PubMed1981

[Postoperative gas gangrene. Apropos of 22 cases].

The authors report twenty two cases of post-operative gas gangrene. In the series studied mortality was 40.9 p. 100, independent of age and sex. Rapidly progressive forms were the most severe. The delay before effective treatment was prescribed influenced prognosis. In clinical terms, shock and associated renal insufficiency were grave, as well as a picture of respiratory distress which led, in certain cases, to contra-indication of one of the therapeutic possibilities, i.e. that of hyperbaric oxygen. Responsible organisms could be isolated in nineteen cases from local samples. There was a marked predominance (15 cases) of clostridium perfringens. Contamination with aerobic flora was common. Examination to assess favourizing circumstances led essentially to a conclusion of the role of microbial contamination, ischemia, broad spectrum antibiotics, absence of appropriate antibiotics and underlying immuno-depression. Treatment was based in the majority of cases on the triple combination of antibiotics, surgery and hyperbaric oxygen, as well as the correction of any general systemic disorders. Mortality was markedly reduced (31 p. 100) in patients receiving complete and early treatment. The gravity and recrudescence of disorders due to anaerobic organisms lead the authors to review current therapeutic possibilities. Appropriate treatment should be prescribed in all situations where an infection due to anaerobic organisms is feared, and should cover the risk of clostridial infection (penicillin 200,000 mu/kg/24 h) as well as the risk of bacteroides (metronidazole 25 mg/kg/24 h). Curative treatment should be prescribed, even in the absence of bacteriological proof, on the basis of presumptive clinical evidence, this being a true emergency which should not be delayed under any circumstances.

Adolescent↗
PubMed1979

Are mineralocorticoid receptors present in human renal adenocarcinoma?

1. The presence of high-affinity sites for [3H]-aldosterone was shown in the normal human renal tissue. 2. [3H]Aldosterone and [3H]dexamethasone binding were studied in human renal adenocarcinoma and in uninvolved external cortex, in 22 patients undergoing nephrectomy for renal adenocarcinoma. Tissue incubations were performed with either [3H]aldosterone (5 x 10(-10) mol/l; 5 x 10(-9) mol/l in the presence of unlabelled glucocorticoids) or [3H]dexamethasone (5 x 10(-9) mol/l). 3. Cytosol [3H]aldosterone binding was six- to seven-fold lower (P less than 0.001) in neoplastic than normal tissue. [3H]Dexamethasone binding was about twofold higher in neoplastic than in normal tissue. This difference was not significant. 4. Nuclear uptake experiments showed that, both in cytosol fractions and nuclei, [3H]aldosterone binding was lower in adenocarcinoma than in normal cortex. 5. The very low binding of [3H]aldosterone suggests that mineralocorticoid receptors are absent in renal adenocarcinoma, an hypothesis in line with the proximal origin of these tumours.

Adenocarcinoma↗