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Biomedical subjects

D Bonnet

Publications and source records attributed to D Bonnet.

At least 73 records · Page 4Linked to original sources
PubMed2000

Arterial mechanical changes in children with familial hypercholesterolemia.

Atherosclerosis is preceded by a phase of changes in the arterial wall that could have functional consequences even before the appearance of atheromatous changes. We hypothesized that early alterations of the mechanical properties of the arterial wall could precede clinical and echographic modifications. We used an automatic, computerized, ultrasonic procedure to evaluate geometric and mechanical characteristics of the common carotid artery (CCA) in normotensive children with primary familial class IIA hypercholesterolemia (FH; n=30; mean+/-SD age, 11+/-2 years old; mean+/-SD systolic/diastolic blood pressure, 109+/-9/55+/-7 mm Hg). These subjects were compared with age-matched, nonobese control subjects (n=27; 11+/-3 years old; 112+/-10/55+/-7 mm Hg). Noninvasive ultrasonic measurements were performed by the same investigator to measure the CCA luminal systolic and diastolic diameters and intima-media thickness (IMT). The cross-sectional compliance, cross-sectional distensibility, and the incremental elastic modulus of the CCA wall were then calculated. Finally, we assessed the degree of reactive hyperemia in the brachial artery produced after distal cuff occlusion and release. The changes in brachial arterial diameter in response to reactive hyperemia (endothelium-dependent dilation) and to glyceryltrinitrate (endothelium-independent dilation) were then measured. In patients with FH, we observed a significant reduction of systodiastolic variations in diameter (by 20%, P:<0.001) without a significant difference in IMT. Cross-sectional compliance and cross-sectional distensibility were significantly reduced in FH subjects (by 15%, P:<0.05 and 19%, P:<0.01, respectively). In parallel, the incremental elastic modulus was significantly increased (by 27%, P:<0.01) in children with FH. No correlation was evident between the carotid incremental modulus and either IMT or plasma low density lipoprotein cholesterol level. There was no difference in diameter of the brachial artery at rest in control and FH subjects (3.0+/-0.5 versus 3.0+/-0.4 mm). The reactive hyperemia and glyceryltrinitrate dilation were also similar in the 2 groups. However, the flow-mediated dilation of the brachial artery was smaller in the FH subjects (4.2+/-2.9%) than in controls (9.0+/-3.1%, P:<0.001). In FH, endothelium-dependent dilation was negatively correlated with the plasma low density lipoprotein cholesterol level (P:<0.04). These results indicate that increased stiffness of the CCA wall in children with FH is independent of blood pressure and could be related to endothelial dysfunction. Thus, alterations in CCA wall mechanics could be early and easily measurable markers of atheromatous changes in the arterial wall.

Biomechanical Phenomena↗
PubMed2000

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

BACKGROUND AND METHODS: Percutaneous closure of a moderate-to-large sized patent ductus arteriosus using multiple coils or a Rashkind double-umbrella may be technically demanding and raises a significant rate of embolization and residual shunting. This is why we tried a new self-expandable device called Amplatzer Duct Occluder to close transvenously large ductuses in eighteen patients at a median age of 2.8 years (range: 0.7 to 34). They had a patent ductus arteriosus with a minimal diameter > 3 mm (mean: 5 +/- 2 mm). The device had a mean diameter of 9 +/- 2 mm and was delivered through a 6F venous sheath. Aortography was done 5 to 10 minutes after the release and follow-up evaluation was performed with color Doppler echocardiography within 24 h, 1 and 3 to 6 months after the procedure. RESULTS: Placement was successful in all but the first patient (95%). Complete closure was achieved immediately in 4/17 patients (24%) and in 13/17 (76%) 24 h later. Two patients were lost for follow-up. Complete closure was confirmed in 14 of the 15 (93%) reviewed patients at 1 and 3 months. In all patients with a ductal diameter < or = 7.5 mm the closure was complete at 1 month. Embolization occurred in one patient with a 9.7 mm duct and surgery was undertaken. A mild and transient hematuria was observed in one patient. No pulmonary artery stenosis nor aortic obstruction were observed on follow-up. CONCLUSION: The Amplatzer Duct Occluder device offers a safe and effective option to treat patients with a ductus arteriosus which minimal diameter is up to 7.5 mm.

Adolescent↗
PubMed2000

[Three-dimensional reconstruction by transesophageal echocardiography of Amplatzer and CardioSEAL prosthetic devices after percutaneous closure and atrial septal defects].

OBJECTIVE: The Amplatzer and cardioSEAL devices are currently used for percutaneous closure of atrial septal defects. The in vivo morphology of these devices is unknown and this is why we sought to describe their geometric profile by three-dimensional echocardiography. METHODS: Thirteen patients, aged 6 to 18, underwent transcatheter closure of a secundum type atrial septal defect with either the CardioSEAL (n = 8) or the Amplatzer (n = 5) device. Three-dimensional reconstructions of the defect were obtained from transoesophageal bidimensional echocardiographic views. RESULTS: In the Amplatzer group, the stretched diameter of the defect was larger than in the CardioSEAL group (22 +/- 2 vs 18 +/- 1 mm, p = 0.003), but ehocardiographic surfaces were the same (3.3 +/- 1 vs 3.6 +/- 1 cm2, p = 0.3). The surface of the CardioSEAL device was measured at 4.8 +/- 2 cm2 whereas the Amplatzer's surface was 6.8 +/- 2 cm2 (p = 0.03). The Amplatzer device had a volume of 9 +/- 1 cm3 while the CardioSeal's volume was 3.1 +/- 1 cm3 (p < 0.0001). CONCLUSIONS: The CardioSEAL device occupies a small volume but it covers less of the septal defect and this may result in a higher incidence of residual shunting. The Amplatzer device almost always occludes the septum, but it tends to bulge into the atria and may cause mechanical complications.

Adolescent↗
PubMed2000

[Cardiac pacing in children with breath-holding spells].

Breath-holding spells are common and usually benign. However, the authors chose to implant a pacemaker in children presenting with severe symptoms. Over the last 15 years, 11 children with severe breath-holding spells were paced. All had reflex spells with loss of consciousness, spontaneously or after minor trauma, and 6 had seizures. All had a normal ECG with marked bradycardic responses to ocular pressure. The 24 hour ECG showed pauses (12-25 s) in 4 patients, sudden bradycardia (< 30/min) in 3 patients, and sinus arrhythmia in the remaining 4 patients. Medical treatment has been unsuccessful. Pacemaker implantation was decided because of the severity and/or the frequency of the episodes in 10 children, and because of intolerable familial anxiety in the other one. Age at implantation ranged from 14 months to 5.5 years (mean: 16.5 +/- 20 months). The device was implanted by an epicardial (7) or from an endocardial (4) approach. All had a ventricular demand device, except for one who was paced from the atrium. The results were spectacular, with disappearance of spells and restoration of normal activities. Holter monitoring showed normal function of the pacemakers. Recurrences were observed in 3 patients, either due to loss of capture (2 cases) or to the need for explantation because of cutaneous erosion. Follow-up ranged from 10 months to 14 years (mean: 7.9 +/- 4.2 years); 2 patients were lost to follow-up; 4 patients totally recovered and only 5 are still vagotonic. Two pacemakers have been changed at 13 and 15 years respectively. The authors conclude that although psycho-social factors play a part in breath-holding spells, pacemaker implantation is very effective in suppressing symptoms in severely affected children.

Age of Onset↗
PubMed2000

[Therapy and prognosis of infectious complete atrioventricular block in children].

From 1983 to 1997, we have studied ten children with complete atrioventricular block likely due to myocarditis in order to assess its prognosis and to define a therapeutic strategy. Their age ranged from 6 days to 16 years (median: 4.1 years). All were admitted for sudden complete block, with symptoms in seven: syncope or fainting, seizures, collapse. Three had an asymptomatic bradycardia which was detected on routine auscultation in children with fever or already hospitalized; fever was present in 5. The disease was related to infection on biological data in 4 cases (1 listeriosis and 3 seroconversions for Epstein Barr or cytomegalic or Coxsackie B viruses), on a myocardial biposy in 1 case and on scintigraphic data in 1 case. In the remaining 4, indirect arguments were considered such as infectious context, normal recent ECG, favourable outcome. Five children were given intravenous isoprenalin with ventricular tachycardia in 3. Five were treated with steroids and 3 with specific antiviral agents. Seven patients were paced temporarily. One child died, 6 recovered totally and 3 have a permanent block with a definitive pacemaker implanted in 2. In conclusion, sudden acquired complete atrioventricular blocks are often ill-tolerated in children and have to be treated with transient pacing. Recovery occurs as a rule but some of these blocks may be definitive. Infective myocarditis is likely to be the cause of the disease even if the pathogen agent cannot always be identified.

Adolescent↗
PubMed2000

[Prenatal diagnosis of conotruncal heart diseases. Results in 337 cases].

Prenatal diagnosis of conotroncal disease has developed by examination of the great arteries during morphological foetal ultrasonic scanning in the second term of pregnancy. This study reports the results of a series of 337 of these malformations diagnosed in the foetus over five and a half years. Their incidence with respect to all foetal cardiac malformations is 16.2%. Tetralogy of Fallot and pulmonary atresia with ventricular septal defect make up 56% of these cases, vascular malposition 16%, coarctation with or without interruption of the aortic arch 14%, truncus arteriosus 9% and agenesis of the pulmonary valves 5%. A karyotypic anomaly was found in 28 cases (8.2%) and, in the foetus with a normal standard karyotype, deletion of chromosome 22q11 was identified in 54 out of 237 cases. There was an associated polymalformative syndrome in 29 cases (8.3%). The training of obstetricians has increased the number of antenatal diagnoses of conotroncal abnormalities. Prenatal counselling should be given by a pluridisciplinary team because the association of these malformations with chromosomal abnormalities or with syndromes difficult to diagnose is common.

Cardiovascular Abnormalities↗
PubMed2000

[Pseudo-inherited form of left heart obstructive defects revealing maternal phenylketonuria].

If an adequate diet is not given to mothers with phenylketonuria, their offsprings often exhibit intra-uterine growth retardation with associated microcephaly and various malformations. Here, we report two families in whom we observed recurrent left heart malformations associated with microcephaly masquerading as a mendelian condition and revealing a maternal phenylketonuria. These observations suggest that when confronted to recurrent heart malformations with extra-cardiac defects that are not due either to an inherited chromosomal anomaly or to a well characterized mendelian disease, a maternal teratogen should be identified and more particularly maternal hyperphenylalaninemia if an intra-uterine growth retardation or a microcephaly is part of the syndrome.

Female↗
PubMed2000

[Cardiovascular impact of end-stage renal insufficiency in children undergoing hemodialysis].

Cardiac hypertrophy and arterial dysfunction have been described in end-stage renal disease (ESDR) in adults. The incremental elastic modulus (Einc), is a marker of vascular wall material stiffness and an independant predictor of cardiovascular mortality in adults with ESRD on hemodialysis. The relationship between arterial changes and the heart is unknown in the children with ESRD in the same conditions. Using a high-resolution vascular ultrasound and a computerized system of measurement (Iotec), we assessed noninvasively 10 ESRD patients (mean +/- SD, age, 11.5 +/- 4 years; blood pressure [BP], 120 +/- 10/63 +/- 4 mmHg) and 10 age-, sex-, and BP-matched controls (mean +/- SD, age, 11 +/- 4 years; BP, 114 +/- 8/58 +/- 8 mmHg). The systolic and diastolic diameter of the common carotid artery (CCA), the thickness of the wall (intima-media thickness, IMT), the cross sectional compliance (CSC), the cross sectional distensibility (CSD) and the (Einc) were determined. CSC and CSD were evaluated at the same level of pressure. The CCA pressure waveform was obtained by applanation tonometry to assess the reflected wave by the augmentation index (AI). Further the left ventricular mass index was assessed. The flow mediated dilation (FMD) (endothelium-dependent function) and the vasodilation induced by glyceryl-trinitrate (GTNMD) (GTN, an endothelium-independent dilator) were evaluated at the brachial artery site. Compared to control subjects, ESRD patients have mechanical artery dysfunction with lower CSC and CSD (0.11 +/- 0.04 vs 0.18 +/- 0.05 mm2.mmHg-1; p < 0.01; 0.43 +/- 0.10 vs 0.82 +/- 0.20 mmHg-1.10(-2); p < 0.001) and higher Einc (2.60 +/- 1.00 vs 1.40 +/- 0.30 mmHg.10(3); p < 0.001). Furthermore an earlier return of the reflected pulse wave (AI -0.24 +/- 0.08 vs -0.58 +/- 0.06; p < 0.005) is correlated to LV mass index (r = 0.55, P < 0.01) that is significantly increased (134 +/- 63 vs 69 +/- 25 g/m2; p < 0.005). These patients have an impaired FMD (4 +/- 2 vs 7 +/- 1%; p = 0.02) with a normal GTNMD. This study shows that early arterial dysfunction can occur in children with ESRD.

Adult↗
PubMed2000

[An uncommon cause of persistent fever in France].

Miliary tuberculosis is rare and requires rapid diagnosis. Outcome is fatal in 25% of the cases. Since radiography and laboratory tests contribute little to early diagnosis, clinical findings are primordial. Antituberculosis antibiotic therapy is frequently started before microbiological confirmation of the diagnosis.

Adult↗
PubMed1999

Arrhythmias and conduction defects as presenting symptoms of fatty acid oxidation disorders in children.

BACKGROUND: The clinical manifestations of inherited disorders of fatty acid oxidation vary according to the enzymatic defect. They may present as isolated cardiomyopathy, sudden death, progressive skeletal myopathy, or hepatic failure. Arrhythmia is an unusual presenting symptom of fatty acid oxidation deficiencies. METHODS AND RESULTS: Over a period of 25 years, 107 patients were diagnosed with an inherited fatty acid oxidation disorder. Arrhythmia was the predominant presenting symptom in 24 cases. These 24 cases included 15 ventricular tachycardias, 4 atrial tachycardias, 4 sinus node dysfunctions with episodes of atrial tachycardia, 6 atrioventricular blocks, and 4 left bundle-branch blocks in newborn infants. Conduction disorders and atrial tachycardias were observed in patients with defects of long-chain fatty acid transport across the inner mitochondrial membrane (carnitine palmitoyl transferase type II deficiency and carnitine acylcarnitine translocase deficiency) and in patients with trifunctional protein deficiency. Ventricular tachycardias were observed in patients with any type of fatty acid oxidation deficiency. Arrhythmias were absent in patients with primary carnitine carrier, carnitine palmitoyl transferase I, and medium chain acyl coenzyme A dehydrogenase deficiencies. CONCLUSIONS: The accumulation of arrhythmogenic intermediary metabolites of fatty acids, such as long-chain acylcarnitines, may be responsible for arrhythmias. Inborn errors of fatty acid oxidation should be considered in unexplained sudden death or near-miss in infants and in infants with conduction defects or ventricular tachycardia. Diagnosis can be easily ascertained by an acylcarnitine profile from blood spots on filter paper.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1999

Skin elastic fibers in Williams syndrome.

The elastin gene is consistently deleted in Williams syndrome and as this protein represents the major component of the elastic fibers of the dermis, we sought to investigate skin elastic fibers in Williams syndrome as a key to unraveling extracellular matrix disorganization in this condition. Both morphometric parameters analyzed by using automated image analysis and immunofluorescence labeling with monoclonal antibodies against elastin and fibrillin 1 showed a disorganized pre-elastic (oxytalan and elaunin) and mature elastic fibers in the dermis of 10 Williams syndrome patients compared with five healthy children and one patient with isolated supravalvular aortic stenosis. Skin biopsies in Williams syndrome patients provide a simple mean to elucidate extracellular matrix anomalies. Hopefully, this method could give clues to the understanding of the elastic network anomalies in this condition and even to the consequences of these latter on elasticity and resilience of other tissues such as the arterial tree.

Adolescent↗
PubMed1999

CD8(+) minor histocompatibility antigen-specific cytotoxic T lymphocyte clones eliminate human acute myeloid leukemia stem cells.

Effective immunotherapy for human leukemia based on infusions of T lymphocytes requires the identification of effector T cells that target the leukemic stem cell. The transplantation of human acute myeloid leukemia into nonobese diabetic/severe combined immune deficient (SCID) mice has identified a rare leukemic progenitor termed the SCID leukemia-initiating cell, which is present in low frequency in the leukemic population and is essential for establishing leukemic hematopoiesis. Thus, this transplant model may be ideally suited to identify effector T cells with antileukemic activity. We report that CD8(+) cytotoxic T lymphocyte (CTL) clones specific for minor histocompatibility antigens inhibit the engraftment of human acute myeloid leukemia cells in nonobese diabetic/SCID mice and demonstrate that this inhibition is mediated by direct CTL recognition of SCID leukemia-initiating cells. These results indicate that CD8(+) minor histocompatibility antigen-specific CTL may be mediators of the graft-versus-leukemia effect associated with allogeneic hematopoietic cell transplantation and provide an experimental model to identify and select T cell clones for immunotherapy to prevent or treat relapse after allogeneic hematopoietic cell transplantation.

Animals↗
PubMed1999

Bone morphogenetic proteins regulate the developmental program of human hematopoietic stem cells.

The identification of molecules that regulate human hematopoietic stem cells has focused mainly on cytokines, of which very few are known to act directly on stem cells. Recent studies in lower organisms and the mouse have suggested that bone morphogenetic proteins (BMPs) may play a critical role in the specification of hematopoietic tissue from the mesodermal germ layer. Here we report that BMPs regulate the proliferation and differentiation of highly purified primitive human hematopoietic cells from adult and neonatal sources. Populations of rare CD34(+)CD38(-)Lin- stem cells were isolated from human hematopoietic tissue and were found to express the BMP type I receptors activin-like kinase (ALK)-3 and ALK-6, and their downstream transducers SMAD-1, -4, and -5. Treatment of isolated stem cell populations with soluble BMP-2, -4, and -7 induced dose-dependent changes in proliferation, clonogenicity, cell surface phenotype, and multilineage repopulation capacity after transplantation in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. Similar to transforming growth factor beta, treatment of purified cells with BMP-2 or -7 at high concentrations inhibited proliferation yet maintained the primitive CD34(+)CD38(-) phenotype and repopulation capacity. In contrast, low concentrations of BMP-4 induced proliferation and differentiation of CD34(+) CD38(-)Lin- cells, whereas at higher concentrations BMP-4 extended the length of time that repopulation capacity could be maintained in ex vivo culture, indicating a direct effect on stem cell survival. The discovery that BMPs are capable of regulating repopulating cells provides a new pathway for controlling human stem cell development and a powerful model system for studying the biological mechanism of BMP action using primary human cells.

Activin Receptors↗
PubMed1999

Detection of transposition of the great arteries in fetuses reduces neonatal morbidity and mortality.

BACKGROUND: Transposition of the great arteries (TGA) is a life-threatening malformation in neonates, but it is amenable to complete repair. Prenatal detection, diagnosis, and early management may modify neonatal mortality and mortality. METHODS AND RESULTS: Preoperative and postoperative morbidity and mortality were compared in 68 neonates with prenatal diagnosis and in 250 neonates with a postnatal diagnosis of TGA over a period of 10 years. The delay between birth and admission was 2+/-2.8 hours in the prenatal group and 73+/-210 hours in the neonatal group (P<0.01). Clinical condition at arrival, including metabolic acidosis and multiorgan failure, was worse in the neonatal group (P<0.01). Once in the pediatric cardiology unit, the management was identical in the 2 groups (atrioseptostomy, PGE1 infusion, operation date). Preoperative mortality was 15 of 250 (6%; 95% CI, 3% to 9%) in the neonatal group and 0 of 68 in the prenatal group (P<0.05). Postoperative morbidity was not different (25 of 235 versus 6 of 68), but hospital stay was longer in the neonatal group (30+/-17 versus 24+/-11 days, P<0.01). In addition, postoperative mortality was significantly higher in the neonatal group (20 of 235 versus 0 of 68, P<0.01); however, the known risk factors for operative mortality were identical in the 2 groups. CONCLUSIONS: Prenatal diagnosis reduces mortality and morbidity in TGA. Prenatal detection of this cardiac defect must be increased to improve early neonatal management. In utero transfer of fetuses with prenatal diagnosis of TGA in an appropriate unit is mandatory.

Humans↗
PubMed1999

Prenatal detection of a tetralogy of Fallot with origin of the left pulmonary artery from the ascending aorta in a familial 22q11 microdeletion.

Here we report a case of prenatal diagnosis of anomalous origin of the left pulmonary artery from the ascending aorta associated with a tetralogy of Fallot in a familial form of 22q11 deletion. The mother, who had a normal heart and a velo-cardio-facial syndrome, had a first child with a pulmonary atresia plus ventricular septal defect associated with a 22q11 deletion. Prenatal diagnosis during the second pregnancy identified the above-described cono-truncal anomaly and FISH study showed a recurrent 22q11 deletion. This case illustrates the intrafamilial variability of cardiac involvement in 22q11 deletion as well as the possibility of diagnosing complex cono-truncal malformations during fetal life.

Adult↗
PubMed1999

Reactivity of Lys(NH2)-containing peptides toward endopeptidases.

Lys(NH2)-containing peptides were subjected to various proteolytic enzymes which were selected for their well-documented specificity for arginyl and/or lysyl peptide bonds. Lys(NH2)-containing peptides were cleaved more rapidly by clostripain than the corresponding lysyl peptides. On the other hand, they proved to be resistant to Achromobacter protease I hydrolysis. The modified peptides synthesized in this study were more stable than the arginyl and lysyl analogues when incubated with trypsin or thrombin. The same tendency was observed when Lys(NH2)-containing peptides were incubated in diluted human serum, suggesting that the replacement of Arg or Lys by Lys(NH2) could be used to increase the stability of peptides in vivo.

Alcaligenes↗