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Biomedical subjects

D Bonnet

Publications and source records attributed to D Bonnet.

At least 19 recordsLinked to original sources
PubMed2002

Idebenone and reduced cardiac hypertrophy in Friedreich's ataxia.

BACKGROUND: Friedreich's ataxia encodes a protein of unknown function, frataxin. The loss of frataxin is caused by a large GAA trinucleotide expansion in the first intron of the gene, resulting in deficiency of a Krebs cycle enzyme, aconitase, and of three mitochondrial respiratory chain complexes (I-III). This causes oxidative stress. Idebenone, a short chain quinone acting as an antioxidant, has been shown to protect heart muscle against oxidative stress in some patients. OBJECTIVE: To assess the efficiency of idebenone on cardiac hypertrophy in Friedreich's ataxia. DESIGN: Prospective, open trial. SETTING: Tertiary care centre. METHODS: Idebenone (5 mg/kg/day) was given orally to 38 patients with Friedreich's ataxia aged 4-22 years (20 males, 18 females). Cardiac ultrasound indices were recorded before and after idebenone treatment. RESULTS: After six months, cardiac ultrasound indicated a reduction in left ventricular mass of more than 20% in about half the patients (p < 0.001). The shortening fraction was initially reduced in six of the 38 patients (by between 11-26%) and it improved in five of these. In one patient, the shortening fraction only responded to 10 mg/kg/day of idebenone. No correlation was found between responsiveness to idebenone and age, sex, initial ultrasound indices, or the number of GAA repeats in the frataxin gene. CONCLUSIONS: Idebenone is effective at controlling cardiac hypertrophy in Friedreich's ataxia. As the drug has no serious side effects, there is a good case for giving it continuously in a dose of 5-10 mg/kg/day in patients with Friedreich's ataxia at the onset of hypertrophic cardiomyopathy.

Adolescent↗
PubMed2001

Presence of increased stiffness of the common carotid artery and endothelial dysfunction in severely obese children: a prospective study.

BACKGROUND: Epidemiological studies suggest that obesity-induced atherosclerosis may start in childhood, but this process has never been demonstrated. We looked for arterial changes and investigated their relation to cardiovascular risk factors in obese children. METHODS: Non-invasive ultrasonographic measurements were made in 48 severely obese children and 27 controls to investigate arterial mechanics and endothelial function. Plasma lipid concentrations, indices of insulin resistance, and body composition were assessed in the obese children. FINDINGS: The obese children had significantly lower arterial compliance than the healthy controls (median 0.132 [0.022-0.273] vs 0.143 [0.112-0.237] mm(2).mm Hg; p=0.02) and lower distensibility (0.60 [0.10-1.00] vs 0.70 [0.50-1.10] mm Hg(-1).10(-2); p=0.0001). Conversely, the obese children had higher values than the controls for wall stress (3.36 [2.00-5.01] vs 2.65 [2.13-3.54] mm Hg.10(2); p=0.0001) and incremental elastic modulus (1.68 [0.72-10.8] vs 0.96 [0.64-1.47]; p=0.0001). Endothelium-dependent and independent function were also lower in the obese than in the control children. An android fat distribution was positively correlated with indices of insulin resistance and plasma triglyceride concentrations and was negatively correlated with plasma HDL-cholesterol concentration and arterial compliance. Endothelial dysfunction was correlated with low plasma apolipoprotein A-I and with insulin resistance indices. INTERPRETATION: Severe obesity in children is associated with arterial wall stiffness and endothelial dysfunction. Low plasma apolipoprotein A-I, insulin resistance, and android fat distribution may be the main risk factors for these arterial changes, which are of considerable concern as possible early events in the genesis of atheroma.

Adolescent↗
PubMed2001

Carma1, a CARD-containing binding partner of Bcl10, induces Bcl10 phosphorylation and NF-kappaB activation.

Bcl10, a caspase recruitment domain (CARD)-containing protein identified from a breakpoint in mucosa-associated lymphoid tissue (MALT) B lymphomas, is essential for antigen-receptor-mediated nuclear factor kappaB (NF-kappaB) activation in lymphocytes. We have identified a novel CARD-containing protein and interaction partner of Bcl10, named Carma1. Carma1 is predominantly expressed in lymphocytes and represents a new member of the membrane-associated guanylate kinase family. Carma1 binds Bcl10 via its CARD motif and induces translocation of Bcl10 from the cytoplasm into perinuclear structures. Moreover, expression of Carma1 induces phosphorylation of Bcl10 and activation of the transcription factor NF-kappaB. We propose that Carma1 is a crucial component of a novel Bcl10-dependent signaling pathway in T-cells that leads to the activation of NF-kappaB.

Amino Acid Sequence↗
PubMed2001

Equine herpesvirus protein E10 induces membrane recruitment and phosphorylation of its cellular homologue, bcl-10.

v-E10, a caspase recruitment domain (CARD)-containing gene product of equine herpesvirus 2, is the viral homologue of the bcl-10 protein whose gene was found to be translocated in mucosa-associated lymphoid tissue (MALT) lymphomas. v-E10 efficiently activates the c-jun NH(2)-terminal kinase (JNK), p38 stress kinase, and the nuclear factor (NF)-kappaB transcriptional pathway and interacts with its cellular homologue, bcl-10, via a CARD-mediated interaction. Here we demonstrate that v-E10 contains a COOH-terminal geranylgeranylation consensus site which is responsible for its plasma membrane localization. Expression of v-E10 induces hyperphosphorylation and redistribution of bcl-10 from the cytoplasm to the plasma membrane, a process which is dependent on the intactness of the v-E10 CARD motif. Both membrane localization and a functional CARD motif are important for v-E10-mediated NF-kappaB induction, but not for JNK activation, which instead requires a functional v-E10 binding site for tumor necrosis factor receptor-associated factor (TRAF)6. Moreover, v-E10-induced NF-kappaB activation is inhibited by a dominant negative version of the bcl-10 binding protein TRAF1, suggesting that v-E10-induced membrane recruitment of cellular bcl-10 induces constitutive TRAF-mediated NF-kappaB activation.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Temporal bone anomaly proposed as a major criteria for diagnosis of CHARGE syndrome.

The acronym CHARGE defines a non-random clustering of congenital malformations of unknown origin. Classical diagnostic criteria include: 1) one major feature namely coloboma/microphthalmia or choanal atresia, and 2) four of the six features designated in the CHARGE acronym. Interestingly, all CHARGE patients hitherto reported had partial or complete semicircular canal hypoplasia on temporal bone CT-scan. We report on semicircular canal agenesis/hypoplasia in three patients with three to four features of the CHARGE syndrome and neither coloboma nor choanal atresia and we propose to include temporal bone malformations as a major criteria for diagnosis of CHARGE syndrome.

Abnormalities, Multiple↗
PubMed2001

Synthesis by chemoselective ligation and biological evaluation of novel cell-permeable PKC-zeta pseudosubstrate lipopeptides.

The ability of lipopeptides to passively cross the cell membrane opens new opportunities for the intracellular delivery of bioactive peptides. However, the production of large series of cell-permeable lipopeptides is not trivial due to their generally low solubility. We have evaluated the possibility of associating the fatty acid to the functional cargo using generally applicable ligation chemistries. To this end, we have designed an amphiphilic shuttle in which arginine residues served to solubilize the lipid part in aqueous media, during both the assembly of the lipopeptide and the cellular assays. Our model peptide, the pseudosubstrate sequence of protein kinase C-zeta (PKC-zeta), was associated to the pentapeptide Gly-Arg-Gly-Arg-Lys(Pam)-NH2 through thiazolidine, thioether, disulfide, or hydrazone linkages. The cytoplasm import of the resulting constructs was monitored through the quantification of the apoptosis specifically induced by PKC-zeta inhibition. Our observations suggested the interest of this noninvasive cellular import method to modulate the activity of an intracytoplasmic pharmacological target and showed the influence of a non-amide link created between the functional peptide and the lipidic vector: optimal results, in terms of both specific activity and low basal cytotoxicity, were obtained with the thiazolidine ligation product.

Apoptosis↗
PubMed2001

Chemoselective acylation of fully deprotected hydrazino acetyl peptides. Application to the synthesis of lipopetides.

Fully deprotected N-terminal alpha-hydrazino acetyl peptides were synthesized and chemoselectively acylated on the hydrazine moiety with various fatty acid succinimidyl esters or N-(cholesterylcarbonyloxy) succinimide to give lipopeptides of high purity. The buffer and pH were adjusted in order to minimize the oxidation of the hydrazine moiety and to achieve the best conversion and selectivity. The acylation was performed in a citrate-phosphate buffer/2-methylpropan-2-ol mixture of pH 5.1. The pKa of the alpha-hydrazino acetyl group on our model peptide was found to be 6.45, i.e., about 2 units lower than the pKa of a glycyl residue. The reaction was subsequently applied to the synthesis of a 38AA peptide derivatized by a palmitoyl group.

Acylation↗
PubMed2001

Elliptic flow in Au+Au collisions at square root(S)NN = 130 GeV.

Elliptic flow from nuclear collisions is a hadronic observable sensitive to the early stages of system evolution. We report first results on elliptic flow of charged particles at midrapidity in Au+Au collisions at square root(S)NN = 130 GeV using the STAR Time Projection Chamber at the Relativistic Heavy Ion Collider. The elliptic flow signal, v2, averaged over transverse momentum, reaches values of about 6% for relatively peripheral collisions and decreases for the more central collisions. This can be interpreted as the observation of a higher degree of thermalization than at lower collision energies. Pseudorapidity and transverse momentum dependence of elliptic flow are also presented.

Journal Article↗
PubMed2001

Selective coronary angiography in patients younger than 1 year of age.

Precise assessment of coronary artery anatomy is needed in congenital coronary malformations and acquired coronary obstruction in children. The aim of the study was to describe our experience of selective coronary angiography (SCA) in newborns and infants. One hundred and three patients younger than 1 year of age underwent SCA. Indications were preoperative screening for coronary artery lesions or anomalous pattern (41 patients), signs of myocardial ischemia (43 patients), surgical difficulties during the reimplantation of the coronary arteries without signs of ischemia (15 patients), and other indications (4 patients). Success rate of selective injection was 100% with no significant complication. In the presence of clinical suspicion of myocardial ischemia, abnormalities of coronary artery pattern was found in 17 of 43 patients. Precious information for the surgical management was obtained in 13 of 41 patients. SCA can be performed safely even in newborns and small infants. Skills in catheterization and knowledge about the coronary artery anatomy are needed to perform SCA.

Coronary Angiography↗
PubMed2001

Absorbable pulmonary artery banding in tricuspid atresia.

A child with tricuspid atresia, concordant ventriculoarterial connections, large ventricular septal defect, and elevated pulmonary artery pressure underwent pulmonary artery banding with a polydioxanone ribbon. This procedure was successful in this patient as the ventricular septal defect became restrictive while the banding was fully absorbed after 5 months. This technique could be included in the panel of surgical strategies for patients with single ventricle physiology and potential but insufficient subpulmonary stenosis in early infancy.

Absorbable Implants↗
PubMed2001

Acquired right heart outflow tract anomaly without systemic hypertension in recipient twins in twin-twin transfusion syndrome.

Significant hemodynamic changes are commonly observed in both fetuses in twin-twin transfusion syndrome. In the recipient twin there is cardiac dysfunction with hypertrophy of both ventricles and overall enlargement of the heart. We describe five cases of recipient twins in twin-twin transfusion syndrome with right ventricle hypertrophy, pulmonary stenosis and tricuspid regurgitation acquired in utero. These symptoms developed with no signs of systemic hypertension. Three of the five recipient twins survived and were developing normally at 3-30 months of age. Postnatal outcome is likely to have improved as a result of prenatal diagnosis of right ventricle outflow tract obstruction and timed delivery. These acquired anomalies of the right heart might be related to the particular hemodynamic conditions of the recipient twin. A global heart dilatation is logically expected, but this hypertrophy without dilatation is probably related to the shared plasma of fetuses with opposite hemodynamic conditions. This is what we consider as the hemodynamic-hormonal paradox. These acquired anomalies, though severe, are accessible to neonatal treatment if treated early.

Adult↗
PubMed2001

Normal and leukemic CD34-negative human hematopoietic stem cells.

Considerable progress has been made in recent years in purifying human and murine hematopoietic stem cells. The essential marker identified is the sialomucin CD34, which is expressed on primitive cells and downregulated as they differentiate into more abundant mature cells. CD34 is not unique to stem cells, however, as it is also expressed on clonogenic progenitors and some endothelial cells. Nevertheless, all clinical and experimental protocols are targeted to CD34+ cells enriched by a variety of selection methods. Recent studies in both the murine and human systems have indicated that some stem cells capable of multilineage repopulation do not express detectable levels of cell surface CD34. These studies challenge the dogma that all human repopulating cells are found in the CD34+ subset. However, the precise relationship between CD34- and CD34+ stem cells is still not well understood. In this review, the results on the discovery of the CD34- repopulating cell are summarized and the impacts this discovery may have, both clinically and in our understanding of the organization of the human hematopoietic system, are examined.

Animals↗
PubMed2001

Prevalence of 22q11 deletion in fetuses with conotruncal cardiac defects: a 6-year prospective study.

OBJECTIVES: Conotruncal malformations (CTMs) are a major feature of 22q11 microdeletion (22qdel). The prevalence of 22qdel in fetuses harboring these defects is unknown. We assessed the prevalence of 22qdel in a population of fetuses with conotruncal cardiac defects. STUDY DESIGN: Consecutive fetuses (n = 261) with a CTM and a normal karyotype were included in the study. All fetuses were screened for 22qdel by means of fluorescent in situ hybridization. RESULTS: A 22qdel was found in 54 fetuses (20.7%). The proportion of 22qdel for each CTM was: tetralogy of Fallot (14/100), pulmonary atresia with ventricular septal defect (11/61), tetralogy of Fallot with absent pulmonary valves (6/16), interrupted aortic arch (10/22), truncus arteriosus (9/29), and complex transpositions of the great arteries (4/33). Additional vascular anomalies were present in 75%. Typical abnormal facial appearance at birth or at autopsy was observed in 80%, and thymus hypoplasia, in 76%. The pregnancy was terminated in 41 of 54 cases, including an intrauterine death in one case. The 22qdel was inherited in 7.7%. CONCLUSION: Prevalence of the 22qdel is high in fetuses with CTMs. The risk of mental retardation associated with the respective risk of cardiac surgery for each type of CTM may strongly influence prenatal counseling.

Abortion, Therapeutic↗