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Biomedical subjects

C Rey

Publications and source records attributed to C Rey.

At least 55 records · Page 3Linked to original sources
PubMed2001

Spontaneous closure of congenital coronary artery fistulas.

Six cases of full spontaneous closure of congenital coronary artery fistulas, and one case of near closure, as seen by colour Doppler echocardiography, are presented. It is worth reconsidering the classical view that nearly all cases of spontaneous closure are eligible for surgical or percutaneous correction to prevent the development of significant and potentially fatal complications. As the natural course of coronary artery fistulas is still poorly defined, asymptomatic patients, especially those under 7 years old with small shunts, should be periodically followed up by echocardiography rather than be subjected to operative closure, even by catheterisation.

Coronary Disease↗
PubMed2001

Leukemia inhibitory factor antagonizes gonadotropin induced-testosterone synthesis in cultured porcine leydig cells: sites of action.

In the present report, the action of leukemia inhibitory factor (LIF) on testicular steroid hormone formation was studied. For this purpose, the direct effects of LIF were evaluated on basal and human (h)CG-stimulated testosterone synthesis by cultured, purified Leydig cells isolated from porcine testes. LIF reduced (more than 60%) hCG-stimulated testosterone synthesis. This inhibitory effect was exerted in a dose- and time-dependent manner. The maximal and half-maximal effects were obtained with, respectively, 10 ng/ml (0.5 nM ) and 2.5 ng/ml (0.125 nM ) of LIF after a 48-h treatment of the Leydig cells. Such an effect of the cytokine was not a cytotoxic effect, because it was reversible and Leydig cells recovered most of their steroidogenic activity after the removal of LIF. Considering the sites of action of LIF in inhibiting gonadotropin-stimulated testosterone formation, it was shown that LIF significantly (P < 0.002) reduced, in a comparable range (about 60% decrease), testosterone synthesis stimulated with LH/hCG or with pharmacological agents that enhance cAMP levels (cholera toxin, forskolin, and PG E2), and testosterone synthesis stimulated with 8-bromo-cAMP. Such an observation indicates that the antigonadotropic action of the cytokine is exerted in a predominant manner at a step (or steps) located beyond cAMP formation. Furthermore, incubation of Leydig cells with 22R-hydroxycholesterol (5 microg/ml, 2 h), a cholesterol substrate derivative that does not need an assisted process to be delivered to the inner mitochondrial membrane, reversed most of the inhibitory effect of LIF on the steroid hormone formation. Such results indicate that LIF acts by reducing cholesterol substrate availability in the mitochondria. Consequently, LIF action was tested on steroidogenic acute regulatory protein and PBR (peripheral benzodiazepine receptor) shown to be potentially involved in such a cholesterol transfer. LIF reduced, in a dose- and time-dependent manner, LH/hCG-induced steroidogenic acute regulatory protein messenger RNA levels. The maximal inhibitory effect was obtained with 6.6 ng/ml of LIF after 48 h of treatment. In contrast, LIF had no effect on PBR messenger RNA expression or PBR binding. This inhibitory effect of LIF on Leydig cell steroidogenesis is probably exerted via an auto/paracrine action of the cytokine. Indeed, by immunohistochemistry, LIF and LIF receptor proteins were identified in Leydig and Sertoli cells but not in other testicular cell types, except for LIF receptor in spermatogonia. Furthermore, the presence of LIF and its receptor in Leydig cells at the neonatal and adult periods suggests that the inhibitory effect of LIF on androgen formation reported here probably occurs in both the fetal and the adult Leydig cell populations during testicular development.

Androstenedione↗
PubMed2001

[Percutaneous closure of patent ductus arteriosus with the Amplatzer duct occluder. Results of 29 patients].

The authors report their experience of percutaneous closure of large patent ductus arteriosus with the Amplatzer duct occluder. The age of the patients ranged from 3 months to 72 years (average 24 months) with body weights of 3.9 to 74 Kg (average 16 Kg). The smallest angiographic diameter of the ductus was 4.0 +/- 1.3 mm at angiography (range 1.8 to 6 mm). The occluder was inserted under local anaesthetic with control aortography in all but one case who required general anaesthesia. In two small babies, the implantation was performed after venous puncture alone with transthoracic echocardiographic monitoring. The implantation was successful in all but one case in which there was a distensible duct. Early angiographic control showed suppression of the shunt in 61% of patients. Secondary haemolysis was observed in one case and was corrected by a second catheterisation 4 days later, with occlusion of the duct with a balloon catheter. The patients were followed up clinically, radiologically and echocardiographically. Doppler echocardiography showed absence of a residual shunt in 24 patients (86%) one month after the procedure, in 25 patients (89%) 3 months after the procedure and in 26 patients (93%) one year after the procedure. Two patients were left with mild or moderate shunts 12 and 16 months after the attempted occlusion. No cases of aortic or pulmonary obstruction were observed. The authors conclude that the Amplatzer duct occluder is a reliable device for closing large patent ductus arteriosus. It may be proposed in young symptomatic children over 4 Kg in body weight. A high rate of occlusion is obtained with a minimal risk of complications.

Adolescent↗
PubMed2001

[Left monoplegia revealing pulmonary arteriovenous fistual in an adolescent: occclusion with an Amplatzer occluder].

A 16 year old adolescent was admitted to hospital for investigation of a transient left monoplegia. The clinical, electric and radiological examinations were all normal. Echocardiography showed no abnormality of cardiac structures or function. Contrast echocardiography was performed and showed a right-to-left shunt suggesting a pulmonary arteriovenous fistula which was confirmed at angiography. The fistula was closed at catheterisation by a detachable balloon: in a second procedure, the balloon was deflated and contrast studies showed a recurrence of the right-to-left shunt. An Amplatzer 8/6 duct occluder was implanted with excellent results and no recurrence at 3 months.

Adolescent↗
PubMed2001

[Value of an implantable EKG monitor for the diagnosis of arrhythmic syncope in children].

The value of an implantable ECG monitor (Reveal TM Plus) is reported in a 12 year old child with unexplained syncopal episodes despite extensive investigations. Twenty-seven days after the implantation, ventricular tachycardia at 450/min was recorded at the first recurrence. This case shows that this type of monitoring can be particularly useful when an arrhythmia is thought to be the cause of syncope in a child and the initial investigation is negative.

Arrhythmias, Cardiac↗
PubMed2001

Odour and VOC confining in large enclosures using air curtains.

Experiments were conducted on a two stream air-curtain prototype designed for VOC and odour confinement in a truck unloading area. The emphasis was placed on the air supply device. Measurements using tracer gas techniques were performed to assess the effectiveness of the system in terms of air tightness. Leakage flow rate was estimated for various feeding arrangements. Flow visualisations and particle image velocimetry measurements were carried out for a better understanding of the flow dynamics. Evidence was given of the improvements brought by the herein referred to, 'double flux' configuration in comparison to traditional designs. After a brief description of the experimental facility and the basic principle underlying the approach developed, the main results are reported and discussed and recommendations are drawn. Considerations about where the effort will be directed in future works are provided.

Air Movements↗
PubMed2000

Up-regulation of mitochondrial peripheral benzodiazepine receptor expression by tumor necrosis factor alpha in testicular leydig cells. Possible involvement in cell survival.

Porcine Leydig cells in primary cultures are resistant to tumor necrosis factor alpha (TNFalpha) cytotoxicity. Here we report that these cells can be rendered sensitive to TNFalpha killing by treatment with the translational inhibitor cycloheximide, suggesting the existence of proteins that can suppress the death stimulus induced by the cytokine. In search of these cytoprotective proteins, we focused on the constituents of the mitochondrial permeability transition pore (PT pore), whose opening has been shown to play a critical role in the TNFalpha-mediated death pathway. We found that TNFalpha up-regulated mRNA and protein expression of the mitochondrial peripheral benzodiazepine receptor (PBR), an outer membrane-derived constituent of the pore. A strong correlation was established between the resistance of the cells to TNFalpha killing and the density of PBR-binding sites. Concomitantly, TNFalpha down-regulated Bcl-2 mRNA and protein expression. As Bcl-2 has been shown to be an endogenous inhibitor of the PT pore, we hypothesize that the TNFalpha-induced up-regulation of PBR expression may compensate for the decrease in Bcl-2 levels to prevent the opening of the PT pore.

Animals↗
PubMed2000

Behavior of human osteoblastic cells on stoichiometric hydroxyapatite and type A carbonate apatite: role of surface energy.

To determine the role of physicochemical characteristics of the surface of dense ceramics on osteoconduction, we studied the proliferation and differentiation of human trabecular (HT) osteoblastic cells, extracellular collagenous matrix production, and biologic apatite formation on stoichiometric hydroxyapatite (HA) and type A carbonate apatite (CA). The surface physicochemical characteristics (composition, roughness) of HA and CA carefully were determined by Fourier-transformed infrared, X-ray photoelectron, and Raman spectroscopies, and by FTIR microscopy, before and after cell culture. On both HA and CA substrates, HT cells attached, proliferated, and differentiated. Cell proliferation did not differ on HA and CA. However, the initial cell attachment and spreading of HT cells were much lower on CA compared to HA. Physicochemical and biologic analyses showed that collagenous synthesis by HT cells after 6 weeks of culture also was lower on CA than on HA. Quantitative histologic analysis confirmed that the collagenous matrix production was lower on CA than on HA. Measurement of wettability showed that the polar interaction energy with water was significantly lower on CA than on HA. The lower cell attachment and collagen production on CA compared to HA clearly were related to the low affinity of HT cells for the CA surface. This study shows that the surface energy of the biomaterial greatly influences the initial cell attachment and spreading of human osteoblastic cells at the surface and affects collagenous matrix deposition on the biomaterial. This suggests that the enhancement of polar components of the surface of dense biomaterials may improve osteoblastic cell attachment and, thereby, osteoconduction.

Apatites↗
PubMed2000

Echocardiographic follow-up after Ross procedure in 100 patients.

The Ross procedure could provide an ideal aortic valve replacement method in children and young adults. We evaluated midterm echocardiographic results to assess pulmonary homograft function as well as pulmonary autograft dimensions and function. In all, 105 patients (26 women and 79 men) underwent the Ross procedure; median age at implant was 29 years. All patients underwent free root replacement. Transvalvular gradients and autograft dimensions were measured at 3 levels (annulus, sinuses of Valsalva, and proximal aorta) at discharge, at 6 months, and annually thereafter. Perioperative mortality was 4.7%. The mean period for echocardiographic follow-up in 100 patients was 32.7 months (range 0.5 to 7 years), during which 4 noncardiac-related deaths occurred. Two patients underwent late reintervention. No moderate or severe regurgitation was recorded. There was 1 case of mild homograft regurgitation and 4 of mild autograft regurgitation at late follow-up. Autograft peak gradients were low and reproducible (5 +/- 2.8 mm Hg at discharge vs 5.5 +/- 3.5 mm Hg at last follow-up, p = NS). Homograft peak gradients increased significantly without severe obstruction (7.8 +/- 5.7 mm Hg at discharge vs 15.8 +/- 9.2 mm Hg at last follow-up). The diameter of the autograft annulus was stable during follow-up, whereas autograft dimensions at sinuses and proximal aorta increased significantly. One group of patients was identified with sinus diameter increases >20% (group A). The 90 remaining patients were classified into group B. The only parameter significantly different between the 2 groups was the sinus diameters measured at discharge (1.74 cm/m2 (group A) vs 1.92 cm/m2 (group B); p = 0.036). In 100 patients and with echocardiographic follow-up for up to 7 years, the Ross procedure showed excellent results. For 10% of patients, we observed a 20% dilation of sinus diameters, but in only 3 patients (3%) was this beyond the upper normal limit.

Adolescent↗
PubMed2000

MR-guided balloon angioplasty of stenosed aorta: in vivo evaluation using near-standard instruments and a passive tracking technique.

The purpose of this study was to assess the feasibility of magnetic resonance (MR)-guided balloon angioplasty of a stenosed aorta on an open low-field magnet using a passive tracking technique. Visualization of vessels and position of instruments were realized by using a fast low-angle shot (FLASH) sequence. Catheters and guidewire were prepared for susceptibility-based MR visualization. Standard balloon catheters were inflated with diluted gadolinium, and nitinol guidewires were modified by incorporation of iron oxide markers into their walls. After validation on a flow phantom, balloon angioplasty was performed on an in vivo model of arterial stenosis. Creation of abdominal aorta stenosis was realized in five piglets. MR-guided balloon angioplasty of the aorta was performed with success in all but one. In one of them, stent implantation was achieved in the descending aorta. Balloon angioplasty using a passive tracking technique is a simple concept that can be realized with near-standard instruments and any MR imaging system. This represents an advance toward MR-guided vascular interventions in the future.

Angioplasty, Balloon↗
PubMed2000

Thin film of low-crystalline calcium phosphate apatite formed at low temperature.

Surface modification of biomaterials to improve biocompatibility without changing their bulk properties is desired for many clinical applications and has become an emerging technology in biomaterial research and industry. In the present study, a simple method of coating the solid surfaces of metals, organic tissue matrices, glasses, inorganic ceramics as well as organic polymers with a thin film of low-crystalline apatite crystals (LCA) was developed. Acidic solution containing calcium and phosphate ions was neutralized with alkaline solution to form calcium phosphate precipitates at low temperature. Precipitates of solid calcium phosphate particles were, then, removed by filtration. Concentration of free ions in the filtered ion solution which were not involved in the formation of calcium phosphate precipitate was high enough to induce the heterogeneous nucleation on the solid surfaces at low temperature. Thin layers of calcium phosphate crystals were formed on the surfaces of metals, glasses, inorganic ceramics, organic polymers including hydrophobic ones, and biological tissue matrices with this solution. The thin layer of crystals consisted of poorly crystalline calcium phosphate apatite crystals which contain high amount of labile ions like bone crystals and did not dissolve in the physiologic solutions. Various cells attached to this crystal layer and proliferated well.

Biocompatible Materials↗
PubMed2000

Results of transvenous occlusion of secundum atrial septal defects with the fourth generation buttoned device: comparison with first, second and third generation devices. International Buttoned Device Trial Group.

OBJECTIVES: The purpose of this study was to assess safety and effectiveness of the fourth generation buttoned device in dosing atrial septal defects (ASDs) and to test the hypothesis that introduction of double button reduces unbuttoning rate without reducing effectiveness. BACKGROUND: Because of the high unbuttoning rate (7.2%) with first, second and third generation buttoned devices, the device was modified (fourth generation) so that there were two radiopaque spring buttons 4 mm apart on the button loop attached to the occluder. METHODS: During a four-year period ending in September 1997, 423 patients, ages 1.5 to 80 years (median 16 years), underwent closure of ASD at 40 medical centers around the world. RESULTS: The ASD size varied between 5 and 30 mm (median 17 mm). The device size varied between 25 and 60 mm. Unbuttoning occurred in 4 (0.9%) of 423 patients. Effective occlusion, defined as no (n = 343) or trivial (n = 34) residual shunt on echo-Doppler studies performed within 24 h of the procedure, was demonstrated in 377 patients (90%). Thus, the unbuttoning rate (0.9 vs. 7.2%) decreased (p<0.01) while effective occlusion rate (90 vs. 92%) remained unchanged (p>0.1) with this device, compared with earlier generation devices. During follow-up from one month to five years (23+/-15 months), 21 (5%) of 417 patients required surgical (n = 12) or transcatheter (n = 9) reintervention, mostly to treat significant residual shunt. In the remaining patients there was gradual reduction and disappearance of the residual shunt. No wire integrity problems were observed. CONCLUSIONS: These data suggest that the fourth generation buttoned device is as effective as earlier generation devices, but without significant unbuttoning. Follow-up results remained good, with a reintervention-free rate of 89% at five years.

Adolescent↗
PubMed2000

[Arm ischemia revealing Kawasaki disease].

UNLABELLED: An aneurysm of the medium arteries is one of the major complications of Kawasaki syndrome. Eleven cases of giant coronary aneurysm have been reported. CASE REPORT: We report a new case in a nine-month-old child. Ischemia of the left hand was the first symptom. Diagnosis was made 30 days later. Anticoagulant and fibrinolytic treatments did not prevent necrosis of four fingers. CONCLUSION: The prognosis of Kawasaki disease depends on early diagnosis and management. Infants younger than seven months of age are more susceptible to developing coronary and midartery aneurysms, which therefore justifies a close observation during the acute phase and later on. In the case of a coronary artery aneurysm, Doppler echography of the upper and lower limbs is mandatorily recommended. Anticoagulant therapy should be started once the diagnosis of mid-artery aneurysms is made. Ischemia of the extremities can lead to necrosis and amputation. Until now, anticoagulants, vasodilators and fibrinolytic agents were not proven to be effective.

Amputation, Surgical↗
PubMed2000

Evidence of hydroxyl-ion deficiency in bone apatites: an inelastic neutron-scattering study.

The novelty of very large neutron-scattering intensity from the nuclear-spin incoherence in hydrogen has permitted the determination of atomic motion of hydrogen in synthetic hydroxyapatite and in deproteinated isolated apatite crystals of bovine and rat bone without the interference of vibrational modes from other structural units. From an inelastic neutron-scattering experiment, we found no sharp excitations characteristic of the vibrational mode and stretch vibrations of OH ions around 80 and 450 meV (645 and 3630 cm(-1)), respectively, in the isolated, deproteinated crystals of bone apatites; such salient features were clearly seen in micron- and nanometer-size crystals of pure hydroxyapatite powders. Thus, the data provide additional definitive evidence for the lack of OH(-) ions in the crystals of bone apatite. Weak features at 160-180 and 376 meV, which are clearly observed in the apatite crystals of rat bone and possibly in adult mature bovine bone, but to a much lesser degree, but not in the synthetic hydroxyapatite, are assigned to the deformation and stretch modes of OH ions belonging to HPO(4)-like species.

Animals↗
PubMed2000

Characterization of the trabecular rat bone mineral: effect of ovariectomy and bisphosphonate treatment.

Bisphosphonates, potent inhibitors of bone resorption, have been used clinically to correct the continued loss of bone mass in osteoporosis and in other conditions. However, there has been some concern that long-term treatment with these compounds, as well as more recently developed drugs, may also decrease the rate of bone formation. Bisphosphonates, which are strongly bound to hydroxyapatite crystals, may alter the structure and reactivity of the crystals, interfere with new crystal nucleation and growth, as well as alter the short-range order of newly formed crystals. We have investigated the chemistry and structure of the solid calcium-phosphate mineral phase of lumbar vertebrae of ovariectomized, 6.5-month-old rats treated with bisphosphonates for 1 year after onset of osteopenia. Appropriate control groups were used for comparison. The techniques used to assess the mineral phase were chemical analyses, Fourier transform-infrared (FT-IR) and FT-Raman spectroscopy, FT-IR microspectroscopy, and phosphorus-31 magic-angle-sample spinning nuclear magnetic resonance spectroscopy ((31)P MAS NMR). The (31)P MAS NMR spectra of trabecular bone of lumbar vertebrae of control, ovariectomized, and treated animals were similar. However, there were several significant differences in the results obtained by FT-IR spectroscopy of the whole tissue samples, FT-IR microspectroscopy of sections of bone, and chemical analyses. For example, whereas chemical analyses demonstrated that the CO(3) content of the mineral phase of the ovariectomized animals was decreased compared with controls, FT-IR microspectroscopy of bone sections showed no changes in the relative CO(3) content, but some changes in the environment of the CO(3) groups. However, chemical analyses of the crystals, combined with data from all three spectroscopic methods and with data from serum analysis, did indicate small changes in the mineral phase after ovariectomy, corrected after treatment with bisphosphonates. In any event, the chemical and structural data in the present studies demonstrate that the bisphosphonate, tiludronate, does not significantly alter the mineral components of bone after 1 year of treatment during the course of which bone loss was reversed.

Animals↗
PubMed2000

Experience in one centre using the buttoned device for occlusion of atrial septal defect: comparison with the Amplatzer septal occluder.

We report our experience using the buttoned device to close defects within the oval fossa and probe-patent oval foramens, comparing the findings with those obtained with the Amplatzer septal occluder. From 1992 to 1997, we used the buttoned device to close defects in 73 consecutive patients, 64 with defects in the oval fossa and nine with patent foramens. We compared this experience with a further series of 62 patients seen from 1997 to 1999 in whom the Amplatzer septal occluder was used. Successful implantation was achieved in three-quarters of those with septal defects in whom the buttoned device was used, in all of those in whom the buttoned device was used for patent foramens, and in nine-tenths of those in whom closure was attempted using the Amplatzer occluder. Immediate surgery was needed in 3 patients in whom a buttoned device was used, one because of embolization and two with residual shunts and a straddling device. Similar immediate surgery was needed to retrieve one embolized Amplatzer occluder. During follow-up, surgery was needed in a further 7 patients, all having had insertion of a buttoned device, because of atrial perforation in one and a significant residual shunt in the remainder. At late follow-up, the rate of complete occlusion was 69% in the patients in whom the buttoned device was used to close a septal defect, 100% when the buttoned device was used for patent foramens, and 95% in those treated with the Amplatzer occluder. Our experience shows that the Amplatzer occluder produced a significantly higher rate of occlusion for larger defects, and with a shorter fluoroscopy time than the buttoned device. The Amplatzer septal occluder, therefore, is our preferred device for closure of defects within the oval fossa.

Adolescent↗