Hydrothermal alteration of kimberlite by convective flows of external water.

Kimberlite volcanism involves the emplacement of olivine-rich volcaniclastic deposits into volcanic vents or pipes. Kimberlite deposits are typically pervasively serpentinised as a result of the reaction of olivine and water within a temperature range of 130-400 °C or less. We present a model for the influx of ground water into hot kimberlite deposits coupled with progressive cooling and serpentisation. Large-pressure gradients cause influx and heating of water within the pipe with horizontal convergent flow in the host rock and along pipe margins, and upward flow within the pipe centre. Complete serpentisation is predicted for wide ranges of permeability of the host rocks and kimberlite deposits. For typical pipe dimensions, cooling times are centuries to a few millennia. Excess volume of serpentine results in filling of pore spaces, eventually inhibiting fluid flow. Fresh olivine is preserved in lithofacies with initial low porosity, and at the base of the pipe where deeper-level host rocks have low permeability, and the pipe is narrower leading to faster cooling. These predictions are consistent with fresh olivine and serpentine distribution in the Diavik A418 kimberlite pipe, (NWT, Canada) and with features of kimberlites of the Yakutian province in Russia affected by influx of ground water brines. Fast reactions and increases in the volume of solid products compared to the reactants result in self-sealing and low water-rock ratios (estimated at <0.2). Such low water-rock ratios result in only small changes in stable isotope compositions; for example, δO18 is predicted only to change slightly from mantle values. The model supports alteration of kimberlites predominantly by interactions with external non-magmatic fluids.

[The obstetrics and gynaecology departments in the French public hospitals: an updated overview]. / État des lieux des services de gynécologie-obstétrique dans les centres hospitaliers publics français.

Restructuring the surgery and gynecology-obstetrics departments taking place now raise many interrogations. It appears as a mandatory necessity to some people and as a tribute to financial strategies to others to the detriment of quality and accessibility of care. Its effect is to clarify a good amount of socioeconomical and medical indicators. The plans of perinatality for the obstetrical aspect and the thresholds of activity for the surgical aspect constitute the major lines of these restructurings. A survey soliciting all the French public hospitals was used to assess the state of obstetrics and gynecology departments in the light of these recent restructurings. Medical demography, preserving and improving the quality and continuity of care, efficiency of the technical supports are discriminating criteria of the involved challenges. Such restructurings have an impact on the doctor's lives, which looks globally positive and a good omen to complete this remodeling process. The activity was safeguarded by a redistribution and a refocusing of institutions. One should not minimize the social impact of these changes, with a potential deterioration of working conditions (internal professional reclassifications, mobility obligation towards other sites). It thus appears that the deep changes which affect the small size institutions will be able to achieve well only if they are clearly done (information) and truly integrated in their medical project.

[Fetal maternal anti-HLA sensitization. Its relationship with the pathology of pregnancy and/or the neonate (author's transl)]. / Immunisation foeto-maternelle anti-HLA et pathologie gravidique et/ou néo-natale.

The frequency of maternal anti HLA sensitization was studied in 1401 normal and pathological pregnancies. The analysis of the obstetrical history showed in patients with sensitization, a stabilical highs indications of preceding abortion and premature labors and of actual anemies and premature labors. The signification of such, an association remains to be found.

[Diagnosis of fetal distress during labor with the aid of the Hammacher cardio-tocographic score and fetal pH determination]. / Diagnostic de la souffrance foetale au course du travail à l'aide due score cardio-tocographique de Hammacher et de la mesure du pH foetal

The authors study the value of the Hammacher tocographic scoring system in the diagnosis of fetal distress in labour. This score gives equal value to three components of the fetal heart rate: the base line, transient variations (dips) and fluctuations (oscillations). There is a statistically very significant (p less than 0.001) relationship between the cardio-tocographic score and the fetal pH as has been found in 106 labours with a coefficient of correlation of 0.67. The score can only be carried out usefully when a "beat to beat" to heart rate is registered and when this is not influenced by the administration of drugs to the mother. The score has been demonstrated to be particularly useful in the diagnosis of fetal distress when the membranes are still intact.

[Poland's syndrome in a sterile woman]. / Syndrome de Poland chez une femme stérile

In a woman aged 32, who came for consultation regarding her sterility, a case of Poland's syndrome was diagnosed in view of a brachysyndactylia and a homolateral agenesia of the large pectoral. The possible connexion between her sterility and this syndrome is discussed.

[Fetal cephalometry and thoracometry during pathological pregnancies]. / Céphalométrie et thoracométrie foetales au cours des grossesses pathologiques.

Cephalometry and thoracometry by means of ultrasound represent two useful methods of foetal biometry. Cephalometry, the technique of which is simple and well documented, is irreplaceable as a method of monitoring high risk pregnancies and as a means of detecting anomalies of foetal growth. However, when there is evidence of chronic foetal distress, thoracometry can compensate for the diagnostic shortcomings of cephalometry. In cases of diabetic pregnancy only thoracometry is able to detect foetal oedema. Combination of the two parameters makes possible, when only one measurement is made, a good approximation of the weight of the foetus even in pathological pregnancies.

[Echographic investigation of the placenta during normal and pathological pregnancies]. / L'exploration echographique du placenta au cours des grossesses normales et pathologiques.

Echographic investigation of the placenta has proved to be very valuable in monitoring pathological pregnancies. Precise localization of the placental area has led to a considerable increase in the practice of amniocentesis; placentography has enabled the authors to carry out biopsies of the placenta successfully. Diagnosis of gravidic metrorrhagia is greatly facilitated by echotomography, as long as the examination is carried out under good conditions, after filling of the bladder. A negative result may avoid the need for prolonged hospitalization. Systematic measurement of placental thickness at about the 36th week of pregnancy can detect unsuspected placental oedema or placental hypotrophy responsible for reduced intrauterine growth.