Stream Nitrate Variations Explained by Ground Water Head Fluctuations in a Pyrite-Bearing Aquifer

In the context of agricultural nitrogen excesses in northwestern France, pyrite-bearing weathered schist aquifers represent important hydrological compartments due to their capacity to eliminate nitrate (NO3-). Under oxygen-free conditions, nitrate is reduced simultaneously with the oxidation of pyrite leading to the release of sulfate (SO4/2-). The aim of the present study is to identify the hydrological conditions under which the weathered schist ground water influences the stream water chemistry, leading to a decrease in NO3- concentration. We measured the ground water head on a small catchment over weathered schist, near the bank and under the streambed, and analyzed the chemical composition of the ground water as well as the stream water on both seasonal and storm-event timescales. Using SO4/2- as a tracer of the weathered schist ground water, we showed that ground water inflow caused a decrease of NO3- concentration in the stream during the autumn as well as during storm events in spring and summer. In summer, the NO3- concentration was controlled by the sources of the stream, and in winter by the shallow ground water inflow. The effect of the weathered schist ground water on the NO3- depletion remained relatively limited in time. This effect persisted into late autumn as long as the NO3(-) -rich shallow ground water did not feed the stream. The duration and intensity of the effect would be extended by decreasing the shallow ground water inflow, which depends on climate as well as the presence of landscape features such as hedges and buffer zones.

Linear insertion of atrioventricular valves without septal defect: a new anatomical landmark for Down's syndrome?

Our objective was to explore whether minor anatomical abnormalities of the septal insertion of tricuspid and mitral valves could be a feature of trisomy 21 in fetuses with an otherwise normal heart. Postmortem examinations were performed in 41 fetuses affected by Down's syndrome and in 52 controls. Adjoining the standard postmortem procedure, an apex-to-base section of the crux of the heart was made on a plane corresponding to the sonographic four-chamber view. This allowed gross and histological examination of the hinge points of tricuspid and mitral leaflets, showing the usual apical displacement of the tricuspid valve in all controls. Of 41 fetuses affected by Down's syndrome, 18 had a structural heart defect. Of the 23 Down syndrome fetuses without a patent heart defect, 16 (i.e., 69% of those considered as having 'normal hearts') had nevertheless a linear insertion of atrioventricular valves at autopsy. Prospective clinical studies are required to evaluate if these postmortem findings can be transposed to the clinical setting of 2nd-trimester sonographic screening.

[Congenital heart disease and nuchal translucency with normal karyotype. Report of 3 cases]

We report three pregnancies where enlarged nuchal translucency was discovered at the first trimester transvaginal ultrasound examination; congenital heart disease developed later. Two cases of hypoplastic left heart were diagnosed prenatally at the mid-trimester sonographic examination. The pregnancies were terminated. In the third case, a supravalvular pulmonary stenosis was discovered on the second day of life. Further investigations demonstrated a mutation on the elastin locus, thus confirming the diagnosis of Williams-Beuren syndrome. The role of nuchal translucency as a risk marker for congenital heart disease is discussed.

[Microdeletion of the chromosome 22q11 in children: apropos of a series of 49 patients]

Most of the children with Di George syndrome and 60% of patients with velocardiofacial syndrome exhibit a microdeletion within chromosome 22q11. The phenotypic expression of this chromosomal abnormality is highly variable.

PATIENTS

Forty-nine children, 0 to 15 years of age, were demonstrated as carriers of a 22q11 microdeletion. The main referral diagnoses were: Di George syndrome (19 cases), velocardiofacial syndrome (14 cases); congenital heart defect with dysmorphism (9 cases); hypoparathyroidism (2 cases). The microdeletion was detected by fluorescent in situ hybridization with probes specific of the 22q11 region.

RESULTS

Facial dysmorphism was the only constant feature. A congenital heart defect was present in 84% of cases. Significant hypocalcemia was documented in 51% of cases and thymic hypo or agenesis in 83%. Significant immune deficiency was documented in nine cases. The most frequent associated defects were urinary tract malformations (8 cases). A cleft palate was present in height enfants but velopharyngeal insufficiency was almost constant. Two-thirds of children had psychomotor delay, and five children exhibited behavioral problems. Of the 35 couples of parents tested, eight mothers were found to be carriers of the deletion.

CONCLUSION

For the pediatrician, it is essential to know the variability of the clinical picture. The long-term prognosis is conditioned by the possibility of mental retardation and learning disabilities. Parents should be tested for the presence of the deletion. The occurrence of the microdeletion in asymptomatic relatives raises difficult problems in genetic counselling.

Clinical and molecular study of DiGeorge sequence

DiGeorge sequence (DGS) is a developmental field defect of the third and fourth pharyngeal pouches. The cardinal features of the syndrome are hypo- or aplasia of the thymus and parathyroids, congenital heart defect of the conotruncal type and characteristic facial dysmorphism. Such a pattern of malformations has been associated with various conditions but it is now well established that most cases of DGS are due to haplo-insufficiency of the chromosome 22q11 region. We report here a series of 16 patients, including a familial case. Minimal criteria for inclusion in this series were two or more of the following features: conotruncal heart defect, hypocalcaemia, hypoplastic/absent thymus and typical facial dysmorphism. Molecular analysis with specific probes of the 22q11 region was conducted in all patients according to two methods, fluorescent in situ hybridization and DNA dosage analysis. A deletion was found at the molecular level in all patients. We emphasize the fact that clinical analysis remains an important step of the diagnosis. The implication of these molecular techniques on diagnosis, prognosis and genetic counselling of DGS are discussed.

[Behçet's disease in a 2-year-old girl]

The authors report a case of gangrenous stomatitis with lingual and anal ulcers and pericarditis in a 2-year-old girl. They propose the diagnosis of Behçet's syndrome for this patient despite the absence of uveitis.

[Physiological basis of fetal and neonatal circulation]

The extremely reduced nature of the pulmonary circulation, the parallel arrangement of the right and left sides of the heart, and the mixture of oxygenated umbilical blood with the rest of the venous return in the right atrium endow the foetal circulation with its "relatively protected" nature. Thus the majority of cardiac and pulmonary malformations have no effect or cause only minor circulatory disturbances. The transfer of respiratory function from the placenta to the lungs which becomes necessary as soon as the cord is clamped is a highly disturbing event. The pulmonary circulation must be established, the communications of foetal life close (Botal's foramen, ductus arteriosus), and the right and left heart function in series. Such adaptations, certain of which are essential to immediate survival, may require several weeks before completion. Any disease in the newborn, congenital or acquired, respiratory, circulatory, metabolic or other, is accompanied by numerous interwoven consequences. In particular, return to a foetal type circulation by increase or absence of pulmonary resistances could induce a right-left shunt through a fossa ovale which is only asking to open, or even through a ductus arteriosus which is only asking to reopen. Congenital diaphragmatic hernia is no exception is no exception to this rule.

Cardiac catheterization by percutaneous femoral venous approach in infants weighing less than 5 kg: observations in 97 cases

The technique of cardiac catheterization after percutaneous introduction of a catheter can now be accomplished in neonates thanks to the refinement of the equipment and to the physicians' experience. In 100 catheterizations performed in infants of less than 5 kg, the new technique was utilized 97 times. Thanks to the utilization of introducers it permits Rashkind atrioseptostomy. Its main advantage is the preservation of venous integrity and this allows repeat investigations through the same route.

Transposition of the great arteries. New technique for anatomical correction

We describe a new technique for the correction of transposition of the great arteries by "detransposition". An aortopulmonary window is created and a patch placed over this and the coronary ostia so that the coronary arteries arisen from the new aorta. Thus, direct surgery on the coronary arteries is avoided with all the complications which may result from this in neonates and infants. A 4.2 kg infant, with transposition and ventricular septal defect, was successfully operated on using this technique. We discuss the indications for this type of operation and conclude that, until we have more experience, it should be used only in children with a left ventricular pressure at least half systemic.