Evolutionarily conserved protein motifs drive interactions between the plant nucleoskeleton and nuclear pores

The nucleoskeleton forms a filamentous meshwork under the nuclear envelope and contributes to the regulation of nuclear shape and gene expression. To understand how the Arabidopsis (Arabidopsis thaliana) nucleoskeleton physically connects to the nuclear periphery in plants, we investigated the Arabidopsis nucleoskeleton protein KAKU4 and sought for functional regions responsible for its localization at the nuclear periphery. We identified 3 conserved peptide motifs within the N-terminal region of KAKU4, which are required for intermolecular interactions of KAKU4 with itself, interaction with the nucleoskeleton protein CROWDED NUCLEI (CRWN), localization at the nuclear periphery, and nuclear elongation in differentiated tissues. Unexpectedly, we find these motifs to be present also in NUP82 and NUP136, 2 plant-specific nucleoporins from the nuclear pore basket. We further show that NUP82, NUP136, and KAKU4 have a common evolutionary history predating nonvascular land plants with KAKU4 mainly localizing outside the nuclear pore suggesting its divergence from an ancient nucleoporin into a new nucleoskeleton component. Finally, we demonstrate that both NUP82 and NUP136, through their shared N-terminal motifs, interact with CRWN and KAKU4 proteins revealing the existence of a physical continuum between the nuclear pore and the nucleoskeleton in plants.

In Depth Topological Analysis of Arabidopsis Mid-SUN Proteins and Their Interaction with the Membrane-Bound Transcription Factor MaMYB

Mid-SUN proteins are a neglected family of conserved type III membrane proteins of ancient origin with representatives in plants, animals, and fungi. Previous higher plant studies have associated them with functions at the nuclear envelope and the endoplasmic reticulum (ER). In this study, high-resolution confocal light microscopy is used to explore the localisation of SUN3 and SUN4 in the perinuclear region, to explore topology, and to study the role of mid-SUNs on endoplasmic reticulum morphology. The role of SUN3 in the ER is reinforced by the identification of a protein interaction between SUN3 and the ER membrane-bound transcription factor maMYB. The results highlight the importance of mid-SUNs as functional components of the ER and outer nuclear membrane.

Investigation of Nuclear Periphery Protein Interactions in Plants Using the Membrane Yeast Two-Hybrid (MbY2H) System

Identification of membrane protein interactomes is a key issue to better understand how these molecules carry out their functions. However, protein-protein interactions using conventional interaction assays are particularly challenging for integral membrane proteins, because of their hydrophobic nature. Here we describe the membrane yeast two-hybrid (MbY2H) system, a powerful tool for identifying the interactors of membrane and membrane-associated proteins.

The LINC complex contributes to heterochromatin organisation and transcriptional gene silencing in plants

The linker of nucleoskeleton and cytoskeleton (LINC) complex is an evolutionarily well-conserved protein bridge connecting the cytoplasmic and nuclear compartments across the nuclear membrane. While recent data support its function in nuclear morphology and meiosis, its involvement in chromatin organisation has not been studied in plants. Here, 3D imaging methods have been used to investigate nuclear morphology and chromatin organisation in interphase nuclei of the model plant Arabidopsis thaliana in which heterochromatin clusters in conspicuous chromatin domains called chromocentres. Chromocentres form a repressive chromatin environment contributing to transcriptional silencing of repeated sequences, a general mechanism needed for genome stability. Quantitative measurements of the 3D position of chromocentres indicate their close proximity to the nuclear periphery but that their position varies with nuclear volume and can be altered in specific mutants affecting the LINC complex. Finally, we propose that the plant LINC complex contributes to proper heterochromatin organisation and positioning at the nuclear periphery, since its alteration is associated with the release of transcriptional silencing as well as decompaction of heterochromatic sequences.

Primary cilia expression in bone marrow in response to mechanical stimulation in explant bioreactor culture

Bone marrow contains a multitude of mechanically sensitive cells that may participate in mechanotransduction. Primary cilia are sensory organelles expressed on mesenchymal stem cells (MSCs), osteoblasts, osteocytes, and other cell types that sense fluid flow in monolayer culture. In marrow, cilia could similarly facilitate the sensation of relative motion between adjacent cells or interstitial fluid. The goal of this study was to determine the response of cilia to mechanical stimulation of the marrow. Bioreactors were used to supply trabecular bone explants with low magnitude mechanical stimulation (LMMS) of 0.3 ×g at 30 Hz for 1 h/d, 5 d/week, inducing shear stresses in the marrow. Four groups were studied: unstimulated (UNSTIM), stimulated (LMMS), and with and without chloral hydrate (UNSTIM+CH and LMMS+CH, respectively), which was used to disrupt cilia. After 19 days of culture, immunohistochemistry for acetylated α-tubulin revealed that more cells expressed cilia in culture compared to in vivo controls. Stimulation decreased the number of cells expressing cilia in untreated explants, but not in CH-treated explants. MSCs represented a greater fraction of marrow cells in the untreated explants than CH-treated explants. MSCs harvested from the stimulated groups were more proliferative than in the unstimulated explants, but this effect was absent from CH treated explants. In contrast to the marrow, neither LMMS nor CH treatment affected bone formation as measured by mineralising surface. Computational models indicated that LMMS does not induce bone strain, and the reported effects were thus attributed to shear stress in the marrow. From a clinical perspective, genetic or pharmaceutical alterations of cilia expression may affect marrow health and function.

Structure and Function of Centromeric and Pericentromeric Heterochromatin in Arabidopsis thaliana

The centromere is a specific chromosomal region where the kinetochore assembles to ensure the faithful segregation of sister chromatids during mitosis and meiosis. Centromeres are defined by a local enrichment of the specific histone variant CenH3 mostly at repetitive satellite sequences. A larger pericentromeric region containing repetitive sequences and transposable elements surrounds the centromere that adopts a particular chromatin state characterized by specific histone variants and post-translational modifications and forms a transcriptionally repressive chromosomal environment. In the model organism Arabidopsis thaliana centromeric and pericentromeric domains form conspicuous heterochromatin clusters called chromocenters in interphase. Here we discuss, using Arabidopsis as example, recent insight into mechanisms involved in maintenance and establishment of centromeric and pericentromeric chromatin signatures as well as in chromocenter formation.

Multiscale Modeling of Trabecular Bone Marrow: Understanding the Micromechanical Environment of Mesenchymal Stem Cells During Osteoporosis

Mechanical loading directs the differentiation of mesenchymal stem cells (MSCs) in vitro and it has been hypothesized that the mechanical environment plays a role in directing the cellular fate of MSCs in vivo. However, the complex multicellular composition of trabecular bone marrow means that the precise nature of mechanical stimulation that MSCs experience in their native environment is not fully understood. In this study, we developed a multiscale model that discretely represents the cellular constituents of trabecular bone marrow and applied this model to characterize mechanical stimulation of MCSs in vivo. We predicted that cell-level strains in certain locations of the trabecular marrow microenvironment were greater in magnitude (maximum ε12 = ∼24,000 με) than levels that have been found to result in osteogenic differentiation of MSCs in vitro (>8000 με), which may indicate that the native mechanical environment of MSCs could direct cellular fate in vivo. The results also showed that cell–cell adhesions could play an important role in mediating mechanical stimulation within the MSC population in vivo. The model was applied to investigate how changes that occur during osteoporosis affected mechanical stimulation in the cellular microenvironment of trabecular bone marrow. Specifically, a reduced bone volume (BV) resulted in an overall increase in bone deformation, leading to greater cell-level mechanical stimulation in trabecular bone marrow (maximum ε12 = ∼48,000 με). An increased marrow adipocyte content resulted in slightly lower levels of stimulation within the adjacent cell population due to a shielding effect caused by the more compliant behavior of adipocytes (maximum ε12 = ∼41,000 με). Despite this reduction, stimulation levels in trabecular bone marrow during osteoporosis remained much higher than those predicted to occur under healthy conditions. It was found that compensatory mechanobiological responses that occur during osteoporosis, such as increased trabecular stiffness and axial alignment of trabeculae, would be effective in returning MSC stimulation in trabecular marrow to normal levels. These results have provided novel insight into the mechanical stimulation of the trabecular marrow MSC population in both healthy and osteoporotic bone, and could inform the design three-dimensional (3D) in vitro bioreactor strategies techniques, which seek to emulate physiological conditions.

[Physical fitness in children with asthma]

The exercise limitation in a child with asthma is the result of several factors: the lack of ventilatory reserve, muscle deconditioning, and cardiac limitation. The severity of the airway obstruction is a major determinant of physical fitness. Aerobic and anaerobic fitness are equally affected. Both types of fitness can be improved by specific training programs.

[Medium and long-term results of anatomical correction of transposition of the great arteries in Marseille]

The object of this study was to evaluate the results of anatomical correction of transposition of the great arteries (TGA) in an inter-regional centre. The characteristics of 220 patients operated between 1985 and 2002 were analysed. Prenatal diagnosis of TGA was made in 38 patients (17%) including 36 of the 109 patients operated since 1995 (33%) and leading to earlier atrial septostomy in this situation (p= 0.046). Since 1995, the global early mortality of 12.3% has been significantly reduced to 5.5% (N= 6) including 4.4% (3/68 cases) of simple TGA (p= 0.002). In multivariate analysis, the only independent risk factor for early mortality was the occurrence of a major per-operative complication (p< 0.0001). The average follow-up was 4.8 +/- 4.5 years with an 86% survival at 5, 10 and 15 years and 97% survival at 5 years for patients operated after 1995. There were 22 reoperations including 14 on the right ventricular outflow tract. The non-reoperation rate at 10 years was 80% for simple TGA versus 70% in complex TGA (p= 0.0001). Survivors are asymptomatic with a normal ECG and normal LV function on echocardiography. Five patients have significant pulmonary stenosis and 4 have mild aortic regurgitation. The exercise stress tests performed between the ages of 7 and 10 were all normal. The authors conclude that that modern and reproducible management of TGA is possible in an inter-regional centre with results comparable to those of surgical centres of reference.

Genetic Clines in the Bay of Biscay Provide Estimates of Migration for Sardina pilchardus

Nine allozymic loci in 1,635 individuals of Sardina pilchardus obtained at 33 sites ranging from the North to the South limits of the Bay of Biscay were analyzed to provide a description of the genetic structure of the sardine population. Individual body size and age were also recorded and analyzed. In the study population, weak but significant genetic differences were found, and a cline was observed between multilocus heterozygosity and longitude. The cline was predominantly driven by allelic frequencies of two loci, PGM-1* and PEP-lt*, and using a cline model, we estimated a migration rate of 103.1 km/gen (dispersal distance per generation). In addition, we observed that the cline was linked to biological data such as mean length and mean age of the fish. Two hypotheses may explain this cline: mixing of two different populations in the Bay of Biscay or a selective process. The weak genetic differences, the important dispersal distance per generation, and the link between genetic and biological data suggest that selection is likely to be the primary factor that maintains the cline.

Haemodynamic features during high-frequency oscillatory ventilation in preterms

AIM

To compare the haemodynamic status during high-frequency oscillatory ventilation and conventional mechanical ventilation in very preterm infants with respiratory distress syndrome.

METHODS

Thirty-two neonates of less than 30 wk gestation randomly assigned to high-frequency oscillatory ventilation (n = 15) or conventional mechanical ventilation (n = 17) had three echocardiographies and one cerebral Doppler-echography under the same ventilation during the first 48 h of life.

RESULTS

Mean airway pressure was 2 cm H2O higher in infants ventilated with high-frequency oscillatory ventilation at the different echocardiographies. Comparable right ventricular indexes were observed in the two groups. Reduction of the ductus arteriosus diameter and ductal closure were significant only in neonates ventilated conventionally. Left ventricular performance and left ventricular contractility did not differ between the groups. The high-frequency group had lower end diastolic velocity and a higher resistance index in the anterior cerebral artery.

CONCLUSION

Compared with conventional mechanical ventilation, high-frequency oscillatory ventilation was achieved without altering cardiac function. However, the inability of the left ventricle to improve its performance in the presence of a significant ductal shunt suggests a narrow range of optimal pressures under this ventilatory mode.

[Rehabilitation of hypoplastic pulmonary arteries and anatomic correction of pulmonary atresia with interventricular communication]

Conventional treatment of pulmonary atresia with ventricular septal defect (VSD), hypoplastic pulmonary arteries (PA) and major aorto-pulmonary collaterals (MAPCAs) is controversial: from symptomatic and palliative treatment for some authors to surgery with unifocalisation of collaterals for others. These treatments never use native pulmonary arteries as only source of pulmonary flow, but create "neo-pulmonary arteries". Nine cases of pulmonary atresia with VSD, hypoplastic PA and MAPCAs were treated by rehabilitation of native PA through a staged approach: 1) surgical neonatal connection between right ventricule (RV) and hypoplastic PA, 2) evaluation and interventionnal catheterism with angioplasty of PA stenosis and closure of collaterals, 3) complete surgical correction with reconstruction of right outflow track and PA and closure of VSD. After first surgical stage of RV-PA connection at the mean age of 4.8 months (+/- 5.6 months), 8 patients were alive and underwent 22 cardiac catheterisms (mean of 2.7 per patient), with angioplasty of PA, and occlusion of MAPCAs in 6 and 2 patients respectively. Seven patients underwent complete anatomical correction at the mean age of 28.8 months (+/- 17.7 months) with one late death. The 6 remaining patients had encouraging hemodynamic status (RV pressure/LV pressure ratio at 0.6 +/- 0.26; mean left and right distal pulmonary pressure at 15.2 mmHg (+/- 9.1 mmHg)), and good functionnal status (3 in NYHA functionnal class 1, and 3 in class 2), for a mean follow-up of 79.5 months (+/- 41.4 months). One patient had reoperation on right outflow track stenosis, 6 years after correction. This small series enhances the feasibility of a staged approach with rehabilitation of small PA, allowing complete surgical correction with the native PA with good hemodynamic and functional results in pulmonary atresia, with VSD, hypoplastic PA and MAPCAs.

Anaerobic fitness in children with asthma: adaptation to maximal intermittent short exercise

Nineteen asthmatic boys (aged 13.4 years, 25-75 percentile: 11.5-15.1 years) performed short bouts of maximal exercise (force-velocity test) to test their anaerobic fitness and tolerance of maximal anaerobic exercise. Fourteen healthy boys (aged 13.9 years, 25-75 percentile: 11.6-15.7 years) matched for anthropometric characteristics including lean body mass (LBM), pubertal stage, and weekly physical activity formed a control group. The maximal anaerobic power (W(ana)) was measured during the force-velocity test. The maximal oxygen uptake (V'(O2max)) was assessed during a standard graded exercise test. Pre- and post-exercise pulmonary function was measured by body plethysmography. The asthmatic children exhibited lower W(ana) than the control group (8.2 watt.kg(-1) LBM, 25-75 percentile: 7.55-10.6 vs. 11.3 watt.kg(-1) LBM, 25-75 percentile: 9.46-14.1; P = 0.01). V'(O2max) was also diminished in the asthmatic group (P = 0.01). Multiple stepwise regression models revealed that Tanner's score (P < 0.001) and the diagnosis of asthma (P < 0.01) were the best predictors of W(ana). In conclusion, a diminished anaerobic fitness could contribute to the overall exercise limitation in asthmatic children.

[Association of severe bronchial disease (bronchial casts, bronchiectasis) and partial abnormal pulmonary venous drainage in 2 children with Turner's syndrome]

The prevalence of cardiovascular malformation is high in Turner's syndrome. We report two cases of partial anomalous pulmonary venous drainage associated with a severe bronchial disease.

CASE REPORTS

Case 1: a 5-year-old girl with monosomy X presented with acute respiratory failure. The chest X-ray showed an atelectasis of the left lower lobe. The patient improved following bronchoscopic removal of a bronchial cast. During hospitalization, an anomalous pulmonary venous drainage of the right lung was discovered. In spite of complete surgical repair of the cardiac malformation, several episodes of respiratory failure occurred several years after the operation. Case 2: a 9-year-old girl with monosomy X and coarctation of the aorta underwent pre-operative cardiac catheterization. She had a history of bronchiectasis, leading to a lobectomy. Her respiratory condition improved following surgery. A partial anomalous pulmonary venous return was discovered during the cardiac angiography. The coarctation was repaired surgically. The correction of the left-to-right shunt was not necessary.

CONCLUSION

The partial anomalous pulmonary venous return is frequently reported in Turner's syndrome. The possible respiratory disease associated with this cardiac malformation is usually described as a consequence of the increase in pulmonary blood flow. Our two cases did not match this hypothesis.

[Congenital atrioventricular block]

Congenital atrioventricular block is defined (Yater) as a documented conduction defect in a young subject with unquestionable bradycardia in the absence of a history of infection which might have caused the condition after birth. It is a rare condition (1 out of 20,000 births) and may be isolated or associated with another congenital malformation. Four cardiac malformations are classically associated: endomyocardial fibrosis, morphological abnormalities close to the conduction system: corrected transposition, left isomerism; patent ductus arteriosus and atrial septal defect apparently unrelated but the most common; the association of mitral regurgitation in adults, although the significance is not very clear. Isolated block is often observed in patients with mothers suffering from autoimmune disease, often clinically latent. Anti Ro/SS-A and La/SS-B antibodies cross into the foetal circulation and cause inflammation of the conduction tissues but the causal mechanism is not known. The diagnosis of the conduction defect is sometimes made during foetal life by echocardiography. After birth, the diagnosis is made by electrocardiography but the block is not always complete or permanent, its degree often increasing with time. In addition, in advanced degrees of block, the escape rhythm tends to slow down. Long-term follow-up studies have revised the previously considered good prognosis of isolated congenital atrioventricular block but advances in cardiac pacing provide satisfactory treatment. In the foetus, isolated atrioventricular block is usually associated with an escape rhythm > 60/min and enables normal vaginal delivery; a low heart rate < 55/min and anasarca carry a poor prognosis. In the neonate, pacing is indicated in babies with cardiac failure and a heart rate < 55/min. Follow-up by Holter monitoring, exercise testing and echocardiography is justified in children and adolescents; the patients may become symptomatic at any age. Pacing is essential in symptomatic cases (malaise, ventricular dysfunction) and useful in cases with long QT intervals, frequent ventricular extrasystoles and wide ventriculogrammes. Pacing is not always easy in children. Epicardial pacing by thoracotomy or an epigastric approach is possible but endocavitary pacing is to be preferred using thin pacing catheters introduced via the subclavian vein and small pacemakers implanted in a sub or prepectoral site. A pacing mode which restores the normal atrioventricular sequence is theoretically superior to single ventricular pacing even if rate responsive frequency.

Anatomic repair of corrected transposition or atrio-ventricular discordance: report of 8 cases

BACKGROUND

It is well recognized that a right ventricle (RV) may eventually fail if working as systemic. This has led to arterial switch operation for transposition of the great arteries (TGA), but more recently to anatomic correction of 'corrected transposition' or atrio-ventricular discordance (AVD) combining an atrial switch and a ventricular outflow repair (arterial switch or Rastelli type).

METHODS

We report here 8 cases of such anatomic correction of AVD in patients from 3 months to 10 years. Of these patients, 6 had situs solitus, and 2 situs inversus; 7 patients had a ventricular septal defect (VSD); 5 had an increased pulmonary flow, and 3 had a decreased pulmonary flow with pulmonary stenosis (PS) or pulmonary atresia (PA). In all, 6 had discordant and 1 had concordant ventriculo-arterial (VA) relations, and 1 had double-outlet RV, 2 had an associated coarctation, and 1 had a cor triatriatum. Of the 8 patients, 5 had pulmonary artery hypertension, 3 a moderate to severe tricuspid insufficiency and 6 had undergone one or more previous operations. Correction was done between 3 months and 10 years of age, with 7 having a Senning procedure (twice left-sided) and 1 a Mustard type operation. VA outflows were repaired with: 4 arterial switches, 1 left ventricle to aorta rerouting, 1 right ventricular outflow tract (RVOT) repair and 2 Rastelli. A tricuspid annuloplasty was done once.

RESULTS

All patients survived the operation, but 2 patients needed a reoperation (both successful): late obstruction of pulmonary venous channel after a left-sided Senning, and residual VSD closure. Mean follow-up is 45 months (3-122). Of the 8 patients, 6 patients are in sinus rhythm, 2 have junctional rhythm. A patient with junctional rhythm and occasional tachycardia died suddenly 18 months after surgery 1 week after satisfactory evaluation. All have a normal left ventricle function as evidenced by echocardiography.

CONCLUSIONS

Despite a more demanding procedure, the 'anatomic repair' of hearts with AVD is possible, even in infancy, with good early and mid-term result. Despite the potential late rhythmic problems of the Senning operation (somehow more frequent with AVD in our experience), it may become, with increasing experience, the procedure of choice in corrected transposition.

Cells and mediators from pharyngeal secretions in infants with acute wheezing episodes

An acute wheezing episode is the most common feature of severe lower respiratory tract infection during infancy. Respiratory syncytial virus (RSV) is the major causative agent. In order to study inflammation during acute wheezing episodes in infants, we wanted to assess the feasibility and contribution of induction of pharyngeal secretions. We therefore compared inflammatory markers in the pharyngeal secretions of 27 infants suffering from acute wheezing episodes with an RSV infection (RSV+) and 18 infants suffering with acute wheezing episodes without RSV infection (RSV-). Pharyngeal secretions were recovered by physiotherapy using isotonic saline. The safety of the procedure was carefully checked. Pharyngeal secretions were homogenized with dithiothreitol. Total cells and eosinophils were counted and levels of eosinophil cationic protein (ECP) and histamine were measured. Induction of pharyngeal secretion was always well tolerated. Eosinophils were present in five RSV+ and seven RSV- patients. ECP levels were not significantly different between the groups. Histamine levels after protein adjustment were significantly increased in RSV+ patients (p<0.01) in comparison to RSV- patients. In this study, we have shown, that pharyngeal secretion can be safely recovered from infants suffering from acute wheezing episodes, and that it can be analysed for enumeration of inflammatory cells and measurement of inflammatory mediators.

[Carbamazepine and vigabatrin in epileptic pregnant woman and side effects in the newborn infant]

BACKGROUND

Carbamazepine (Tegretol) is frequently prescribed to pregnant epileptic women. Various congenital malformations constitute the most described side-effects in their newborns.

CASE REPORTS

Case 1. Esteban was born by caesarean section at 39 weeks of gestation, weighing 3,860 g. His Apgar score was 8, 9, 10 at 1, 3 and 5 minutes. His mother was given phenobarbital until 1.5 months of pregnancy then carbamazepine 400 mg LP x 2/day, raised to 600 mg LP x 2/day at the 25th week of gestation because of epileptic crisis. The newborn was transferred at day 4 for drowsiness, mild jaundice, persistent vomiting and bouts of hypotonia/hypertonia, tremors and hyperexcitability. His plasma Tegretol level was 5.9 micrograms/mL and severe hypocalcemia (1.35 mmol/L) was noted. Hypocalcemia disappeared within 48 hours and gastric and neurologic troubles by day 6. The patient left the hospital at day 14. Case 2. Matheo, Esteban's brother, was born by caesarean section after 39 weeks of gestation, weighing 3,210 g. His Apgar score was 9, 10, 10 at first, third and fifth minutes. The mother's anti-epieptic treatment associated carbamazepine LP 400 mg x 3/day and vigabatrin four tablets of 500 mg/d until the 6th month of pregnancy and five tablets by day thereafter. The newborn presented vomiting from the first feeding; tremors were noted on day 2. His plasma Tegretol level was 5.7 micrograms/mL (N = 4-8 micrograms/mL) and the baby was transferred. Upon arrival, persistent vomiting and succession of hypotonia/hypertonia with intermittent opisthotonos were noted. Blood and urine tests showed: low calcemia (2.19 mmol/L), negative Brand reaction and DNPH test, normal urinary and blood amino acid chromatography. The course was spontaneously favourable and the child went home at day 11.

CONCLUSION

Newborns of epileptic mothers treated with carbamazepine and/or vigabatrin during pregnancy should be placed under clinical observation during their first postnatal week. Calcemia monitoring is suggested for infants whose mothers were not supplemented with vitamin D during pregnancy. With a follow up of respectively 26 and 7 months, both brothers have normal milestones, confirming the transitory and benign character of reported side-effects.

Determinants of the tension-time index of inspiratory muscles in children with cystic fibrosis

Nutritional status and chronic pulmonary hyperinflation can alter respiratory muscle function in cystic fibrosis (CF). This study investigated: 1) whether inspiratory muscle function is reduced in children with stable CF in comparison with healthy controls; and 2) the mechanisms leading to inspiratory muscle weakness, which probably predispose to respiratory muscle fatigue. We determined the tension-time index of the inspiratory muscles (TTMUS) noninvasively at rest in 16 children with mild to moderate CF (mean age, 11 +/- 2 years) and 10 healthy controls (mean age, 11 +/- 2 years). The TTMUS was determined as follows: TTMUS = TI/TTOT.PI/PIMAX, where PI is the mean inspiratory pressure estimated from the measure of mouth occlusion pressure (P0.1), PIMAX is the maximal inspiratory pressure, and TI/TOT is the duty cycle. The results showed similar nutritional status in both groups, as well as mild to moderate airway obstruction, hyperinflation, and trapped gas in the CF group. In this group only, a significant inverse relationship was found between TI/TOT and PI/PIMAX[TITTOT = 0.482 - (0.388PI/PIMAX), r = -0.53; p < 0.05]. These patients also had greater TTMUS (TTMUS = 0.087 +/- 0.030 in CF vs. 0.056 +/- 0.014 in controls, P < 0.01) that increased with decreasing lean body mass (r = -0.70, P < 0.005), with increasing percent predicted functional residual capacity (r = 0.70, P < 0.05), and increasing volumes of trapped gas (r = 0.77, P < 0.01). The multiple linear regression analysis for these factors was significant (R2 = 0.84, P < 0.01); however, the partial regression coefficient was significant only for lean body mass (r2 = 0.60, P < 0.05). Therefore, muscle mass appeared as the strongest determinant of TTMUS in CF. This study used a noninvasive method to assess the inspiratory muscle performance in children with CF. The results suggest impairment in inspiratory muscle function in these children despite good nutritional status and only mild to moderate alteration in pulmonary function tests. In addition, we were able to investigate some of the determinants of inspiratory muscle weakness, namely, muscle mass, hyperinflation, and trapped gas, and found that muscle mass played a predominant role.

Wingate test performance in children with asthma: aerobic or anaerobic limitation?

To investigate the anaerobic capacity in children with bronchial asthma, eight male children with atopic asthma (age: 12 +/- 1.7 yr) and seven healthy control subjects (age: 12 +/- 1 yr) performed a 30-s all-out exercise test: the Wingate anaerobic test (WanT). Post-exercise plasma epinephrine (E), norepinephrine (NE), venous blood lactate (La), and blood pH levels were determined. Peak power (Ppeak), mean power (Pm), and total energy expenditure (Wtot) during the WanT were assessed. The relative importance of aerobic (WO2) and anaerobic (Wana) energy release during the WanT was also evaluated. In comparison with control subjects, the children with asthma exhibited lower Ppeak (W.kg-1): 6 +/- 1.14 vs 7.3 +/- 0.5, P < 0.05; lower Pm (W.kg-1): 4.7 +/- 0.8 vs 5.9 +/- 0.5, P < 0.05; and lower Wtot (Jg-1): 140.3 +/- 25 vs 176.9 +/- 19, P < 0.05. The relative contribution of WO2 (26%) and Wana (74%) to the Wtot was identical in both groups. Blood lactate and pH kinetics revealed significantly lower La values and less acidosis in the asthmatic group (P < 0.001). Lastly, E (pg.ml-1) concentrations were lower in the asthmatic group: 274.96 +/- 84.58 vs 901.28 +/- 604.76, P < 0.05. These results suggest a reduced anaerobic capacity in children with asthma. A diminished adrenergic response to exhausting exercise, leading to a decreased anaerobic glycolysis, could partly account for this phenomenon.

[Cardiac adaptation to muscular exercise in children after complete repair of tetralogy of Fallot]

The aim of this study was to assess cardiac adaptation to muscular exercise in children operated for tetralogy of Fallot. Eight children with a history of tetralogy of Fallot were studied and compared with ten control children. The basal evaluation consisted of an electrocardiogram, spirometry in all cases. Chest X-ray and echocardiography in all operated children. A muscular exercise stress test with incremental load on a bicycle ergometer was carried out with measurement of the cardiac output by CO2 rebreathing (experimental method). Under resting conditions, the two groups were comparable with respect to anthropometrical parameters and respiratory function. The cardiovascular data confirmed the good postoperative results of the children with a history of tetralogy of Fallot; cardiothoracic index of 0.49 to 0.55; sinus rhythm on the electrocardiogram; right ventricular pressures within normal limits; residual instantaneous right ventricular-pulmonary artery pressure gradient less than 25 mmH. On exercise, there was no significant difference with respect to VO2max, maximal heart rate, maximal cardiac output and maximal ventilation. The relationship between cardiac output and oxygen consumption was linear in two groups: y = 8.17x + 1.95 in the control group, y = 8.57x + 2.82 in the operated children. The change in cardiac output on exercise was comparable in the two groups. These observations seemed to be related to the good postoperative haemodynamic result: absence of pulmonary sequellae and right ventricular dysfunction. Despite the normality of the results obtained in this series, exercise stress testing with analysis of cardiac and respiratory adaptation would seem to be necessary in the follow-up of children operated for tetralogy of Fallot to exclude a ventilatory or circulatory limitation.

Familial non-syndromic conotruncal defects are not associated with a 22q11 microdeletion

Molecular studies have shown microdeletions in region q11 of chromosome 22 in nearly all patients with DiGeorge, velocardiofacial and conotruncal anomaly face syndromes (DGS, VCFS and CTAFS, respectively) and in a high percentage of non-syndromic familial cases of conotruncal defects (CTD). CTD account for roughly a fourth to a third of all non-syndromic congenital heart defects (CHD), thus, 22q11 could harbor a major genetic factor of CHD. We searched for a 22q11 microdeletion in familial cases of non-syndromic CTD. Thirty-six cases of various isolated CTD, that is without history of hypocalcemia, immune deficiency, absent thymus, and dysmorphic appearance, were selected. With 48F8, a cosmid probe localized in the smallest deleted region of the DiGeorge critical region (DGCR), we found no deletions by fluorescence in situ hybridization in these 36 affected individuals of 16 families with recurrent CTD. Moreover, D22S264, a microsatellite localized at the distal part of the largest deleted region, was used to genotype the patients. Thirty-two patients out of 37 were heterozygous and hence not deleted at this locus, whereas 5 were uninformative. In conclusion, there are no large deletions in familial cases of various CTD, whether these defects are identical or not within a family. This result does not rule out other minor anomalies in this chromosomal region.

[Ventricular tachycardia in children]

Ventricular tachycardia (VT) in children is different to that observed in the adult because ischemic heart disease is exceptionally rare in this age group. The arrhythmia sometimes presents with cardiac failure or loss of consciousness. VT complicates the outcome of operated Tetralogy of Fallot, arrhythmogenic right ventricular dysplasia and some cardiac tumours. Cardiomyopathies are also a cause of VT but it must be noted that ventricular dysfunction may be the result of a prolonged arrhythmia and will disappear after return to sinus rhythm. Many cases of childhood VT occur without any patent cardiac disease even after extensive investigations. Some are benign with a good prognosis, such as salvoes of VT or sustained attacks of so-called ventricular Bouveret. Others carry a more reserved prognosis and require active treatment. Incessant tachycardia of the newborn is difficult to stop may be cured without sequellae. Torsades de pointes is sometimes iatrogenic complicating congenitally long QT syndromes with or without deafness or familial nature, and which may be likened to adrenergic VT. Amiodarone and betablockers are the best antiarrhythmic agents. Investigations with a diagnostic or therapeutic objective are easier in older children but these techniques, whilst not being systematic, do not exclude the very young children. Ablation techniques progress and the limited indications of surgery and implantable defibrillators have to be considered case by case.

[Neuroblastoma, factor of early decompensation of tetralogy of Fallot]

The authors report the case of a tetralogy of Fallot associated with a neuroblastoma secreting large quantities of noradrenaline. Anoxic decompensation of the tetralogy of Fallot occurred early at the age of 4 months with cyanotic crises associated with an impression of abdominal pain. A systemic-pulmonary anastomosis was performed and the cyanosis regressed but the crises persisted and investigations showed the presence of a neuroblastoma. The tumour was treated by surgery and chemotherapy and has not recurred after 2 years' follow-up. Complete repair of the tetralogy of Fallot was performed secondarily at the age of 2. In this case, the high concentration of circulating catecholamines was probably a factor of early decompensation of the tetralogy of Fallot by infundibular spasm. A review of the literature revealed 26 cases of cardiac disease with a peripheral neurogenic tumour. Two pathogenic mechanisms are suggested: an embryological abnormality of cardiac cell migration from the neural crest and chronic stimulation of neuroblastic cells by chronic hypoxia.

[Evaluation of the left-to-right shunt in interatrial septal defects (ostium secundum) using Doppler echocardiography. Apropos of 12 cases]

In 12 patients with inter-atrial communication (ostium secundum) (IAC-OS), and ages ranging between 8 and 63 years (mean = 21 years), the ratio between pulmonary and systemic flow (QP/QS) was evaluated with the use of Doppler ultrasonography and compared with the QP/QS obtained by oxymetric measurement during catheterization. The pulmonary or systemic flow is evaluated from the diameter of the opening (d) and the velocity curve (ITV) recorded by pulsated Doppler in the aorta and the pulmonary artery; Q = d2/4 x ITV x heart rate both examinations (sonogram and catheterization) are performed in less than 24 hours. The results show a good correlation between both methods (R = 0.948) (Y = 0.756 X + 0.692). There is no significant variation between intra- or inter-observer. The findings of this study are comparable to those already published; the main difficulty in evaluating of the QP/QS by Doppler sonography are related to the measurement of the pulmonary diameter and there recording of good velocity curves. The QP/QS evaluated by Doppler sonography from a simplified calculation method advocated by Oloez et al. (QP/QS = d2 Ap x V max Ap/d2 Ao x V max Ao were compared, in retrospect, to the data provided by catheterization. The correlation is also satisfactory (R = 0.893). The Doppler ultrasonography is therefore a reliable and reproducible method in as far as the measurement of QP/QS in young or adults subjects affected with IAC OS.

[Extracardiac malformations in tetralogy of Fallot]

The purpose of our study was to determine the incidence and type of malformations associated with tetralogy of Fallot (TF). Among 133 patients followed up for 12 years, 30 who had either complete TF (n = 26) or pulmonary atresia and interventricular septal defect (n = 4) presented with another, extracardiac malformation. These malformations were part of a malformative syndrome in 21/30 patients, including 4 trisomies 21, 6 embryofoetopathies unquestionably (antiepileptics n = 2, alcohol n = 1) or possibly (hormonal treatment n = 1) of environmental origin, 6 branchial arch pathologies and 5 miscellaneous syndromes. The extracardiac malformation was isolated in the remaining 9 patients, including 5 cases of skeletal anomaly and one case each of omphalocele and microcephaly. Altogether, in these 30 patients skeletal and neurosensory anomalies were largely predominant. Skeletal anomalies involved the vertebral column in 8 cases (cervical 3, thoracic 4, lumbar 1) and the limbs in 5 cases (2 of which were phocomelias). The 4 patients with pulmonary atresia and interventricular septal defect also presented with an early embryopathy: Shprinzen's velocardiofacial syndrome (n = 2), DiGeorge syndrome (n = 1) and situs inversus (n = 1). We compared TF with other congenital heart diseases in our population and found that the incidence of associated malformations was about average. The various associations are discussed. In genetic syndromes, trisomy 21 predominates and TF is less frequent than atrioventricular canal. In syndromes of environmental origin, the role of antiepileptic drugs (chiefly phenytoin and trimethadione) is well-known, alcohol is less often responsible and the TF-phocomelia association is suggestive of progesterone. In branchial arch syndromes, TF is the usual cardiopathy.(ABSTRACT TRUNCATED AT 250 WORDS)

[Bronchiolitis in infants. Respiratory functional exploration in the acute phase]

Respiratory function tests were performed in infants hospitalized for bronchiolitis immediately after the acute stage, in order to appreciate the function of the respiratory muscles. A study of the ventilatory mechanics, of the transdiaphragmatic pressure, of the ventilatory rate and of the blood gases was performed. Results were compared with those obtained in 10 "healthy" infants. They showed: a decrease in the dynamic compliance (DYN.C) (p less than 0.001) and an increase in the total pulmonary resistances (TPR) (p less than 0.05) providing evidence for the intensity of bronchial and bronchiolar obstruction; an increase in the abdominal and intrathoracic pressures difference (Pdi) (p less than 0.01) which may reach 3 times the normal value and which is proportional to the decrease in DYN.C. (r = 0.74; p less than 0.001), providing evidence for the intensification of the inspiratory diaphragmatic effort and of its adjustment to the degree of obstruction; a reverse of the abdominal pressure curve with respect to that in normal subjects, with an increased pressure level, providing evidence for abdominal distension and increased pressure during all the expiration, suggesting the active participation of the abdominal muscle to expiration; a change in the ventilatory rate, characterized by a high respiratory frequency, a decreased tidal volume, a shortened inspiratory time and a normal inspiratory time/total time ratio. this rate is opposed to that observed in older children with bronchial obstruction. It might optimize the respiratory muscles output, as at this age, they have not yet reached all their contractile capacity.

[Congenital heart diseases and urinary malformations]

The purpose of this study was to evaluate the advisability of a systematic search for uropathy in patients with malformative heart disease. Thirty-three cases of urinary tract malformation associated with congenital cardiopathy are reported. These cases represent 2.8 p. 100 of all cardiac patients seen during the same period. The congenital heart diseases were varied, with a predominance of ventricular septal defect (48 p. 100) followed by dextrocardia, single ventricle and coarctation of the aorta. UT abnormalities included vesico-ureteral reflux (36 p. 100), renal agenesis (5 cases), renal dysplasia or hypoplasia (4 cases), upper UT obstruction (4 cases), hypospadias (3 cases), renal ectopia (3 cases), lower UT obstruction (2 cases), polycystic kidney, megaloureter, horseshoe kidney and supernumerary kidney (1 case each). A study of the literature showed that the two uropathies with a risk of associated cardiopathy are renal agenesis and horseshoe kidney. The cardiopathy-uropathy association was found in isolation (11 cases) or combined with cryptorchidism (2 cases) or with multiple malformations (20 cases). The malformations were diverse, the most frequent being neurosensorial malformations (70 p. 100), followed by skeletal malformations (55 p. 100) equally divided between apine and limbs, genital malformations (35 p. 100) and digestive tract malformations (25 p. 100). A study of the cardiopathy-uropathy concordances failed to elicit any predominant association; in the literature, ventricular septal defect is usually associated with horseshoe kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

[Oral occlusion pressure in scoliosis and neuromuscular syndromes]

Oral occlusion pressure, a neuro-muscular index of the activity of the respiratory centers, was measured in 2 groups of children: one of 43 "healthy" children, in order to establish a predictive equation according to age (Y = 1.23 + 8.30 X A-1) and another of children presenting with respiratory failure, either due to an impairment of the thoracic cavity (10 dorsal scoliosis) or to an impairment of the respiratory muscles (29 children with muscular dystrophy or spinal muscular atrophy). The occlusion pressure increases with the degree of the ventilation deficiency in children with scoliosis. It remains paradoxically normal in children with neuro-muscular disease, irrespective of the ventilation deficiency. In the latter, the respiratory centers activity being considered as normal, this situation would indicate their muscular incapacity to correctly express this activity. It would show a severe muscular deficiency with a high risk of occurrence of respiratory distress accidents.

[Alveolar microlithiasis in children. Contribution of bronchoalveolar lavage]

This case of pulmonary alveolar microlithiasis emphasizes the rarity of the disease and its exceptional diagnosis in infants which relies on the pulmonary pathologic study. Besides allowing for diagnosis, the study of the alveolar brushing fluid permitted to describe for the first time pictures of post-necrotic cellular calcification which is probably responsible for the disease.

[Intestinal malformations and congenital heart diseases]

A series of 21 patients with both congenital heart disease and intestinal malformation seen over a 12-year period is reported. The intestinal malformations were: anorectal malformations (11 cases), duodenal atresia (5), omphalocele (4) and common mesentery (1). Congenital heart diseases consisted of: atrial septal defect (ASD) (10 cases), ventricular septal defect (VSD) (2), tetralogy of Fallot (2) and miscellaneous cardiopathies. In patients with anorectal malformations ASD and VSD predominated (6/11 cases) and multiple malformations syndromes were present in 8 cases, including trisomy 13, Vater syndrome, skeletal (4), neurological (3) and renal abnormalities (3); 3 children died. Duodenal atresia was always associated with left-to-right shunt: VSD (3), ductus arteriosus (2), complete atrioventricular canal (1) and trisomy 21 (2); one child died. Omphalocele coexisted with VSD (2), tetralogy of Fallot (1), dual outlet right ventricle (1), trisomy 21 (1) and multiple malformations syndromes (3); 2 children died. The patient with common mesentery had left-to-right shunt. Comparison of this series with data from the literature showed that children with congenital heart disease have a much higher incidence of intestinal malformations than those with normal heart and that they frequently present with multiple malformations (chromosome aberrations or multiple organ lesions). This multiple malformation complex is particularly common in anorectal malformations where the incidence of congenital heart diseases is 9 to 14%, with predominance of VSD and tetralogy of Fallot. In patients with duodenal atresia trisomy 21 is extremely frequent, and the incidence of cardiopathies is 18%; in the absence of trisomy 21 the cardiopathy is complex.(ABSTRACT TRUNCATED AT 250 WORDS)

[Congenital neuropathy caused by hypomyelination]

A 9 year-old girl with congenital hypomyelination neuropathy is reported. Clinical features were delayed motor development, disturbances of gait, deep sensory defect, areflexia and mild distal palsy with claw feet. E.M.G. revealed dramatically diminished motor conduction velocities. C.S.F. protein was normal. Histological examination of the right sural nerve revealed a severe loss of myelinated fibers. On electron microscopy, poorly myelinated and large amyelinated axons were enclosed by normal Schwann cells and surrounded by multiple single or double layered basement membranes which were concentrically arranged in an onion bulb pattern. This case of congenital hypomyelination neuropathy is compared with ten similar cases in the literature.