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Biomedical subjects

C Faure

Publications and source records attributed to C Faure.

At least 73 records · Page 4Linked to original sources
PubMed1996

Comparative effects of cholesterol and cholesterol sulfate on hydration and ordering of dimyristoylphosphatidylcholine membranes.

The comparative effect of cholesterol (CH) versus cholesterol sulfate (CS) on dimyristoylphosphatidylcholine (DMPC) membranes has been investigated by optical microscopy, freeze-fracture electron microscopy, x-ray diffraction, and solid state 2H and 31P nuclear magnetic resonance (NMR). The sulfate analogue extends the lamellar phase domain toward high water contents, and substitution of 30 mol % CH by CS in DMPC lamellae induces the trapping of 30 wt % additional water. The greater swelling of the CS-containing systems is evidenced by determination of lamellar repeat distances at maximal hydration: 147 +/- 4 A and 64 +/- 2 A in the presence of CS and CH, respectively. 2H-NMR of heavy water demonstrates that CS binds approximately 12 more water molecules at the interface than CH whereas NMR of deuterium-labeled DMPC chains reveals that 30 mol % CS orders the membrane as 15 mol % CH at high temperature and disorders much more than CH at low temperatures. The various effects of CS versus CH are discussed by taking into account attractive Van der Waals forces and repulsive steric/electrostatic interactions of the negatively charged sulfate group.

Binding Sites↗
PubMed1996

Resting energy expenditure before and after surgical resection of gut lesions in pediatric Crohn's disease.

In pediatric Crohn's disease (CD), resection of gut lesions is necessary to remove stenoses and when frequent relapses occur despite nutritional support and medical treatment. After surgery, improved nutritional status and accelerated growth usually follow increased nutritional intake and lower doses of steroids. The aim of this study was to compare energy balance before and after surgery while nutritional intake and steroid therapy were unchanged. Eleven patients, aged 14.5 +/- 2.5 years and with mildly active CD, were explored 1 week before and 1 month after gut resection for stenosis (n = 7) and medical treatment failure (n = 4). Eleven matched children participated in the study as controls. Disease activity was assessed by the Pediatric Crohn's Disease Activity Index and serum orosomucoid concentration. Resting energy expenditure (REE) was measured by indirect calorimetry, and fat-free body mass (FFM) was measured by anthropometry. The patients' mean REE decreased from 46.6 +/- 10.5 kcal/kg FFM/day before surgery to 42.6 +/- 10.3 kcal/kg FFM/day after surgery, while the controls' mean REE was 39 +/- 7 kcal/kg FFM/day (analysis of variance, p = 0.02). After surgery, body weights were not significantly different, but the mean protein oxidation rate was reduced and arm muscle area was increased. Changes in REE per kilogram of FFM per day were not correlated with changes in orosomucoid serum concentrations (r2 = 0.35; p = 0.4). In conclusion, in children with mildly active CD, while nutritional intake and steroid therapy were maintained at preoperative levels, a significant decrease in REE and improved nitrogen utilisation were observed 1 month after resection of the CD gut lesion. This finding suggests better use of energy substrates when CD lesions are removed.

Adolescent↗
PubMed1996

Current concepts and issues in the management of regurgitation of infants: a reappraisal. Management guidelines from a working party.

Regurgitation in infants is a common problem. Recent issues, such as the increased risk of sudden infant death in the prone sleeping position, the finding of persisting occult gastro-oesophageal reflux with feed thickeners, and the increasing awareness of the cost-benefit ratio of medications may challenge the currently recommended management approach. A round table was organized to elaborate on the impact of (i) the pro supine sleeping campaigns in relation to sudden infant death and (ii) advancement in medical treatment on therapeutic strategies in regurgitating infants. The participants were opinion leaders from Europe and North America (Belgium, Canada, France, UK, Italy, Switzerland and The Netherlands). The importance of parental reassurance is stressed. As a consequence of the supine sleeping campaigns aiming to decrease the incidence of sudden infant death syndrome, the "prone elevated sleeping position" is no longer advised as a first-line therapeutic approach, although it is still recommended in "complicated reflux". It is emphasized that milk thickeners are an adequate therapeutic tool for regurgitation, but not in reflux disease. According to the literature, the efficacy of (alginate )antacids, although very popular in some countries, is questionable. These recommendations will be of interest to first-line paediatricians, since about 40% of their patients, according to the literature, present because of regurgitation.

Anti-Ulcer Agents↗
PubMed1996

[Systemic granulomatous reaction in hip prosthesis. Apropos of 2 anatomoclinical cases].

PURPOSE OF THE STUDY: The production of particulate wear debris is a recognised complication of joint arthroplasty. Focus was made on local tissue reactions. Systemic distribution of wear debris are less know. We report two new cases of distant granulomatous reaction. MATERIAL: The first case concerned a 71-year-old man with lymph node histiocytosis incidentally discovered during the staging of a prostatic carcinoma. The second case concerned a 61-year-old man with a visceral granulomatosis reaction (liver, spleen and lymph node) associated to hepatic ans splenic enlargement. METHODS: We realised an histological analysis of several tissue specimens for these two patients and for one case an inductively coupled plasma-mass spectrometry technique (ICPMS). RESULTS: In all specimens we identified a foreign body granulomatous reaction characterized by the presence of particles coming from hip arthroplasty. The ICPMS identified titanium in spleen. DISCUSSION: Distant granulomatous reaction are generally localised in regional lymph nodes and discovered by accident. A systemic granulomatous reaction attributable to wear particles raises the question of long term biocompatibility of prosthetic materials. CONCLUSION: Besides local reaction, it is of utmost importance that physicians involved in prosthetic field take into consideration the possible systemic adverse effect of wear particles from arthroplasty.

Aged↗
PubMed1995

Quantification of alpha 1-adrenoceptor subtypes in human tissues by competitive RT-PCR analysis.

Alpha 1-Adrenoceptors are a heterogeneous subfamily of receptors comprising at least three pharmacologically- and structurally- distinct subtypes named alpha 1a-, alpha 1b- and alpha 1d-adrenoceptors. A competitive reverse transcription-polymerase chain reaction methodology using subtype selective competitor RNAs as reference internal standards was adopted to determine the absolute amounts of each of the three cloned to date alpha 1-adrenoceptor subtype encoding mRNAs in selected human tissues. Our data demonstrated that each of these alpha 1-adrenoceptor subtypes exhibits a distinctive tissular expression pattern.

Base Sequence↗
PubMed1995

MRI of intramedullary cavernous haemangiomas.

We reviewed 11 cases of intramedullary cavernous haemangiomas (IMCH) studied by MRI, to assess its diagnostic value in these lesions. Follow-up MRI was obtained in five patients 7 days-2 years following the initial study. In one case a postoperative examination was obtained. The diagnosis was pathologically proven in ten cases, and supported in the last by a family and personal history of cavernous haemangiomas. A reticulate appearance with areas of mixed signal intensity in both T1- and T2-weighted images was the most common finding. Homogeneous high, low or intermediate signal intensity was each found in one case. Two small lesions gave low signal. A rim of low signal was less common than in cerebral cavernous haemangiomas. In one case, the brain showed more than 20 lesions with the MRI appearances of cavernous haemangiomas. In two of five patients, serial preoperative MRI showed progressive disappearance of high-signal areas on both T1- and T2-weighted images. To find a haemorrhagic intramedullary lesion on MRI is not rare. Although the appearances are not pathognomonic, an IMCH can be suggested. We suggest that the following characteristics may help: (1) a personal and/or family history of cavernous haemangiomas; (2) typical MRI appearances of mixed acute, subacute and chronic haemorrhage; (3) a tendency for signal intensity to decrease on follow-up; (4) normal spinal angiography; and (5) associated brain lesions.

Adult↗
PubMed1995

[Treatment of gastroesophageal reflux].

Several therapeutic means are available for the treatment of pathological gastroesophageal reflux (GOR): positional therapy, thickening the feedings, dietetic modifications, antacids, mucosa-protecting agents, gastrokinetic drugs, antisecretory drugs, and surgery. In uncomplicated GOR, simple measures must be used first, associating positional therapy, thickening the feedings and a mucosa-protecting agent or an antacid; a gastrokinetic drug will be added if these measures are insufficient after 2 or 3 weeks. Peptic esophagitis requires a more drastic treatment, using antacid, prekinetic and antisecretory drugs; in addition, its cure should be assessed by esophagoscopy. When GOR is associated with life-threatening events, treatment may be completed with an atropine derivative in case of vagal hypertonia, and its efficiency must be verified by monitoring of oesophageal pH under treatment. In infants, the medical treatment should be maintained until complete cure, which usually occurs when walking is achieved. Surgery is indicated in complicated GOR (esophagitis, life-threatening event, pulmonary complication) with failure of the medical treatment, or as first-line treatment in the case of severe esophagitis in children with severe psychomotor impairment.

Child↗
PubMed1995

Structure and expression of endogenous retroviral sequences in the permanent LMH chicken cell line.

From DNA mapping data, four endogenous proviral loci have been observed in the chicken permanent cell line LMH. The locus corresponding to endogenous virus (ev) ev1 is present in duplicate whereas the locus corresponding to ev3 is present in one copy. The other loci are probably ev6 and a solitary long terminal repeat. A RNA Northern blot analysis revealed both ev3 and ev6 transcripts but no ev1 transcript was detected. Using avian leukosis virus (ALV)-based vectors, transcomplementing assays were performed. They demonstrate the correct expression and maturation of endogenous env proteins and the absence of production of functional gag and pol components, indicating that these cells are not competent for viral production.

Animals↗
PubMed1995

Modulation of the gamma-aminobutyric acid type A receptor by the antiepileptic drugs carbamazepine and phenytoin.

We report here that carbamazepine and phenytoin, two widely used antiepileptic drugs, potentiate gamma-aminobutyric acid (GABA)-induced Cl- currents in human embryonic kidney cells transiently expressing the alpha 1 beta 2 gamma 2 subtype of the GABAA receptor and in cultured rat cortical neurons. In cortical neuron recordings, the current induced by 1 microM GABA was enhanced by carbamazepine and phenytoin with EC50 values of 24.5 nM and 19.6 nM and maximal potentiations of 45.6% and 90%, respectively. The potentiation by these compounds was dependent upon the concentration of GABA, suggesting an allosteric modulation of the receptor, but was not antagonized by the benzodiazepine (omega) modulatory site antagonist flumazenil. Carbamazepine and phenytoin did not modify GABA-induced currents in human embryonic kidney cells transiently expressing binary alpha 1 beta 2 recombinant GABAA receptors. The alpha 1 beta 2 recombinant is known to possess functional barbiturate, steroid, and picrotoxin sites, indicating that these sites are not involved in the modulatory effects of carbamazepine and phenytoin. When tested in cells containing recombinant alpha 1 beta 2 gamma 2, alpha 3 beta 2 gamma 2, or alpha 5 beta 2 gamma 2 GABAA receptors, carbamazepine and phenytoin potentiated the GABA-induced current only in those cells expressing the alpha 1 beta 2 gamma 2 receptor subtype. This indicates that the nature of the alpha subunit isoform plays a critical role in determining the carbamazepine/phenytoin pharmacophore. Our results therefore illustrate the existence of one or more new allosteric regulatory sites for carbamazepine and phenytoin on the GABAA receptor. These sites could be implicated in the known anticonvulsant properties of these drugs and thus may offer new targets in the search for novel antiepileptic drugs.

Animals↗
PubMed1995

[In vitro study of the properties of bioresorbable lactic acid polymer materials].

PURPOSE OF THE STUDY: The potential applications of biodegradable osteosynthesis implants present many advantages over conventional metallic devices. Polyesters of the poly and hydroxy-acid type were recognized early as serious candidates. These polymers have demonstrated a very good biocompatibility and are biodegradable in vivo. After biological and chemical testing poly L. lactic acid 98 (PLA 98) was selected as a candidate. We used a static and dynamic investigation in vitro to assess firstly the material properties of PLA 98 and secondly how its characteristics could be modified within a physiological environment. MATERIAL: Michel Vert and colleagues have shown that polymers of lactic acid have a similar time to resorption providing they contain 98 per cent of the "L" form of the polymer. In vitro studies were assessed on bars made in PLA 98. METHODS: In a first time in vitro studies in traction and flexion on bars allowed an assessment of mechanical properties of PLA 98. In a second time stresses were applied on bars using a physiological environment (Haemacel - 37 degrees C). In a third time we assessed the mechanical properties at the temperature of 37 degrees C with dynamic tests on bars in traction and flexion. RESULTS: The stress-strain curves on bars showed that the material is fragile. Sterilisation with ethylene-oxide did not affect the mechanical properties. When bars were placed in a thermostatically controlled (37 degrees C) physiological environment, the stress-strain curve showed that the material became ductile. With a temperature of 37 degrees C and with a frequency better than one hertz, the dynamic tests on bars showed that the material endurance is good up to 20,000 cycles. At 37 degrees C and at the end of one month, the Young modulus and the maximal strain before breaking lose 50 per cent of their initial value. DISCUSSION: All things considered and as the digital value showed, the PLA 98 appear to be ten times less strong than steel. In a physiological environment the mechanical properties improved due to hydratation of the polymer. The material become quickly ductile or malleable. This allowed transient loading without causing breakage. CONCLUSION: The mechanical properties of bioresorbable materials are very different from those of stainless steel and there is a learning curve in their utilisation. The PLA 98 polymer has demonstrated a very good biocompatibility and is totally biodegradable in vivo. With these results we think that PLA 98 can be used in clinical practice. Indications and clinical use should remain limited to bones regions with low applied stresses.

Biocompatible Materials↗
PubMed1995

[Primary amyloidosis of bones. MRI aspects].

Primary systemic amyloidosis is a rare cause of vertebralcollapse. We describe a patient who presented multiplecollapsed vertebrae. Magnetic resonance imaging (MRI) demonstrated a diffuse bone marrow abnormality. A diffuse low signal throughout the vertebral bodies on T1 and T2 weighted spin-echo images were observed. A bone biopsy confirmed the suspected diagnosis of vertebral involvementby amyloid. MR imaging can be of interest to evaluate the bone spreading of a known amyloidosis and to help in the diagnosis of amyloidosis in the case of non traumatical vertebral fractures.

Amyloidosis↗
PubMed1994

Expression of alpha 1-adrenoceptor subtypes in rat tissues: implications for alpha 1-adrenoceptor classification.

We report here the mapping of the mRNA distribution of three different alpha 1-adrenoceptor subtypes (alpha 1b, alpha 1c and alpha 1d) in various rat tissues. cDNA fragments covering the region from the fifth to seventh putative transmembrane spanning domains of these three alpha 1-adrenoceptor subtypes were generated from rat hippocampus using reverse transcription coupled to polymerase chain reaction (PCR). These three alpha 1-adrenoceptor cloned cDNA fragments were then used as subtype-selective cDNA probes in Northern blot analysis. Of the three specific DNA probes only the rat alpha 1b-adrenoceptor probe hybridized to mRNA of rat liver. The rat alpha 1c-adrenoceptor probe hybridized to a mRNA species of 3.7 kb in tissues that have been reported to contain the classical pharmacologically-defined alpha 1A-adrenoceptor such as hippocampus, vas deferens, lung and salivary gland. Also, a major mRNA transcript of 2.7 kb was detected in hippocampus, vas deferens and lung, using the rat alpha 1d-adrenoceptor probe. In addition, pharmacological characterization of [3H]prazosin binding to three stably transfected mammalian cell-lines expressing one of the three alpha 1-adrenoceptor subtypes cloned to date (namely, alpha 1b--of the hamster smooth muscle DDT1-MF2 cell-line, the bovine brain alpha 1c--and the rat cerebral cortical alpha 1d-adrenoceptors) was performed. Of the three cloned alpha 1-adrenoceptor subtypes that alpha 1c-adrenoceptor showed a similar pharmacological profile to that of the classical alpha 1A-adrenoceptor of rat salivary gland. Our data on the pharmacological profile and expression pattern of the alpha 1c-adrenoceptor indicate, in contrast to earlier claims (Schwinn et al., J. Biol. Chem. 265, 1990), that this subtype is in fact the classical pharmacologically-defined alpha 1A-adrenoceptor subtype.

Amino Acid Sequence↗
PubMed1994

Pharmacokinetics of intravenous omeprazole in children.

This study was undertaken to define the pharmacokinetics of omeprazole in children and included 13 patients, heterogeneous in terms of age (0.3 to 19 years), underlying disease and biological constants, indication of omeprazole administration and associated therapy. The dose administered ranged from 36.9 to 139 mg.1.73 m-2. The pharmacokinetic parameters of omeprazole were: systemic clearance, 0.23 l.kg-1.h-1; volume of distribution, 0.45 l.kg-1; elimination half life 0.86 h; but were highly variable between individuals. Dosage, differences in hepatic and renal function and associated therapy may contribute to inter-individual variability. Within the range of doses administered, the pharmacokinetic parameters were similar to those reported in adults. The drug has been well tolerated in all children.

Adolescent↗
PubMed1994

Identification of alpha 1-adrenoceptor subtypes present in the human prostate.

alpha 1-Adrenoceptors (ARs) play an important role in mediating human prostatic smooth muscle contraction. In the present study cDNA fragments covering different domains of 3 alpha 1-AR subtypes (alpha 1b, alpha 1c and alpha 1d) were generated from human prostate by reverse transcription coupled to the polymerase chain reaction (RT-PCR). The reconstituted partial sequence (349 amino acids) of the human prostatic alpha 1c-AR PCR products showed 94% identity at the amino acid level with that of the corresponding region of the cloned bovine brain alpha 1c-AR. Using human alpha 1-AR subtype selective cDNA probes in Northern blot analysis, the co-expression of mRNA transcripts corresponding to alpha 1b-, alpha 1c- and alpha 1d-AR subtypes was detected in 4 different regions (apex, base, periurethra and lateral lobe) of the human prostate. Competitive inhibition experiments of [3H]-prazosin binding to membrane preparations of human prostate revealed that the non-selective alpha 1-subtype antagonist, alfuzosin, produced a monophasic inhibition curve, whereas oxymetazoline produced a 2-component inhibition curve with pKi values of 8.54 and 5.46. The high-affinity alpha 1-AR component of the oxymetazoline inhibition curve was predominant (57%-66%) and showed an affinity for oxymetazoline comparable to that of the alpha 1c-AR subtype. As such our results illustrate the expression of different alpha 1-AR subtypes in human prostate and importantly that alpha 1c represents the predominant alpha 1-AR subtype present in this tissue.

Adenoma↗