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Biomedical subjects

F Pierre

Publications and source records attributed to F Pierre.

At least 19 recordsLinked to original sources
PubMed2003

Magnetic-field-dependent quasiparticle energy relaxation in mesoscopic wires.

In order to find out if magnetic impurities can mediate interactions between quasiparticles in metals, we have measured the effect of a magnetic field B on the energy distribution function f(E) of quasiparticles in two silver wires driven out of equilibrium by a bias voltage U. In a sample showing sharp distributions at B=0, no magnetic field effect is found, whereas, in the other sample, rounded distributions at low magnetic field get sharper as B is increased, with a characteristic field proportional to U. Comparison is made with recent calculations of the effect of magnetic-impurities-mediated interactions taking into account Kondo physics.

Journal Article↗
PubMed2003

[Medical-legal aspects: the obstetrician as a defendant or as an expert].

Most claims ab out term intrapartum fetal asphyxia (or cerebral palsy presumed to be in relation with it) are based on abnormal intrapartum fetal heart rate patterns, and presumed excessive delay from decision-to-delivery and/or inadequate care. For the obstetrician, whether as a defendant or a judicial expert, the difficulty lies in data interpretation which should not be reduced to an analysis of fetal monitoring, but should consider the context, the explorations used to be sure of abnormal fetal heart rate interpretation, and appropriate delay for delivery in light of the findings.

Asphyxia Neonatorum↗
PubMed2002

Dephasing by extremely dilute magnetic impurities revealed by Aharonov-Bohm oscillations.

We have probed the magnetic field dependence of the electron phase coherence time tau(phi) by measuring the Aharonov-Bohm conductance oscillations of mesoscopic Cu rings. Whereas tau(phi) determined from the low-field magnetoresistance saturates below 1 K, the amplitude of Aharonov-Bohm h/e oscillations increases strongly on a magnetic field scale proportional to the temperature. This provides strong evidence that a likely explanation for the frequently observed saturation of tau(phi) at low temperature in weakly disordered metallic thin films is the presence of extremely dilute magnetic impurities.

Journal Article↗
PubMed2001

Cytokine mRNA expression in mouse colon: IL-15 mRNA is overexpressed and is highly sensitive to a fibre-like dietary component (short-chain fructo-oligosaccharides) in an Apc gene manner.

On the basis of studies using the Min mouse model of colon carcinogenesis, we have recently proposed that a fibre-like food (short-chain fructo-oligosaccharides, sc-FOS) fermented in the colon may stimulate a mechanism of cancer immunosurveillance. In the present paper, we have investigated the expression of cytokines as potential effector molecules. Interleukin (IL-)4, IL-5, IL-13, IL-15 and interferon (INF)-gamma mRNAs were detected by a multi-probe ribonuclease protection assay in C57BL/6J and Min mouse colons. IL-15 mRNA expression was significantly amplified (P=0.01) by the sc-FOS-enriched diet in the colon of Min mice.

Animals↗
PubMed2001

Electrodynamic dip in the local density of states of a metallic wire.

We have measured the differential conductance of a tunnel junction between a thin metallic wire and a thick ground plane, as a function of the applied voltage. We find that near zero voltage, the differential conductance exhibits a dip, which scales as 1/square root of [V] down to voltages V approximately 10k(B)T/e. The precise voltage and temperature dependence of the differential conductance is accounted for by the effect on the tunneling density of states of the macroscopic electrodynamics contribution to electron-electron interaction, and not by the short-ranged screened-Coulomb repulsion at microscopic scales.

Journal Article↗
PubMed2001

Multiple Andreev reflections revealed by the energy distribution of quasiparticles.

We have performed the tunnel spectroscopy of the energy distribution function of quasiparticles in 5-microm-long silver wires connected to superconducting reservoirs biased at different potentials. The distribution function f(E) presents several steps, which are manifestations of multiple Andreev reflections at the NS interfaces. The rounding of the steps is well explained by electron-electron interactions.

Journal Article↗
PubMed2001

[Complications of laparoscopy in gynecology].

In the field of surgery the development of operative laparoscopy has been one of the most important steps forward over the past fifteen years. This technique has become the surgical treatment of choice for a number of indications in gynaecology. The advantages of laparoscopy as compared with laparotomy are weil known, and assessment of the risk of complications is essential. A multicentric study was carried out in seven top French centres for laparoscopic gynaecological surgery. This series runs over a period of nine years and covers 29,966 diagnostic and operative laparoscopies. The risk of complications has been assessed according to the complexity of the laparoscopic procedure in question. The means of diagnosis and treatment of the complications have been analysed together with the importance of the surgeon's degree of experience. The mortality rate is 3.33 per hundred thousand laparoscopies. The overall complication rate is 4.64 per thousand laparoscopies (139 cases). The rate of complications requiring laparotomy is 3.20 per thousand (96 cases). The complication rate is significantly correlated with the complexity of the laparoscopic procedure (p = 0.0001). One out of three complications (34.1%; 43 cases) occurred while setting up for laparoscopy, and one out of four complications (28.6%) were not diagnosed during the operation. As new indications for laparoscopic surgery in gynaecology have appeared, there has been a parallel and statistically significant increase in the rate of urological complications (p = 0.001). Increased experience of the surgeons has had three consequences: a statistically significant drop in the number of bowel injuries (p = 0.0003), a drop in the rate of complications requiring laparotomy for those laparoscopic surgical procedures which are weil-defined (p = 0.01) and a change in the way complications are treated, with a significant increase in the proportion of incidents treated by laparoscopy (p = 0.0001). Laparoscopic surgery is a reliable technique. The risk of complications exists whatever the indication for laparoscopy. None of the phases in the operation must be neglected. The risk of accidents being overlooked means that the methods for postoperative follow-up must be adapted, bearing in mind the shorter hospital stay. The part played by the surgeon's experience raises the major problem of practitioner training.

Female↗
PubMed2001

[Torsion of the accessory spleen: an atypical etiology for acute abdomen].

The accessory spleen is often a incidental discovery. The accessory post-accidental spleen are unusual. The torsion of a movable spleen is possible and represent about 0.2 to 0.3% of splenectomy. But the torsion of an accessory spleen is exceptional. A case of acute torsion of an accessory spleen is reported. In a 26-year-old women was admitted with acute abdominal pain. The abdominal ultrasound and the abdominal X-Ray are no specific. In the face of the acute pain, a laparoscopy was necessary. At laparoscopy, the patient was found to have torsion and infarction of an accessory spleen in the pelvis. The treatment was a splenectomy and the evolution was favorable.

Abdominal Pain↗
PubMed2001

Only fibres promoting a stable butyrate producing colonic ecosystem decrease the rate of aberrant crypt foci in rats.

BACKGROUND: Dietary fibres have been proposed as protective agents against colon cancer but results of both epidemiological and experimental studies are inconclusive. AIMS: Hypothesising that protection against colon cancer may be restricted to butyrate producing fibres, we investigated the factors needed for long term stable butyrate production and its relation to susceptibility to colon cancer. METHODS: A two part randomised blinded study in rats, mimicking a prospective study in humans, was performed using a low fibre control diet (CD) and three high fibre diets: starch free wheat bran (WB), type III resistant starch (RS), and short chain fructo-oligosaccharides (FOS). Using a randomised block design, 96 inbred rats were fed for two, 16, 30, or 44 days to determine the period of adaptation to the diets, fermentation profiles, and effects on the colon, including mucosal proliferation on day 44. Subsequently, 36 rats fed the same diets for 44 days were injected with azoxymethane and checked for aberrant crypt foci 30 days later. RESULTS: After fermentation had stabilised (44 days), only RS and FOS produced large amounts of butyrate, with a trophic effect in the large intestine. No difference in mucosal proliferation between the diets was noted at this time. In the subsequent experiment one month later, fewer aberrant crypt foci were present in rats fed high butyrate producing diets (RS, p=0.022; FOS, p=0.043). CONCLUSION: A stable butyrate producing colonic ecosystem related to selected fibres appears to be less conducive to colon carcinogenesis.

Animals↗
PubMed2001

[Management of premature rupture of the membranes at term: how long to delay? Results of a prospective multicentric study in 713 cases].

OBJECTIVE: The aim of our study was to define he best delay for management of spontaneous rupture of the membranes at term. MATERIALS AND METHODS: We conducted a prospective multicentric study in western France defining 3 groups of expectancy (6, 12 and 24 hours) to assess obstetrical, neonatal and maternal outcomes. RESULTS: We included 713 patients. There was no significant difference in neonatal and maternal morbidity between the 3 groups. The rate of cesarean section was statistically higher in the 6-hour group (12%). There was no statistical difference between 12 and 24 hours but the rate was lower in the 12-hour group (5.5 versus 7.9%). CONCLUSION: Based on our findings and a review of the literature, we have decided that in cased of premature rupture of the membranes at term, a 12 hour delay is best. At most two prostaglandin maturations can be performed in unfavorable cervixes.

Adult↗
PubMed2001

Biochemical and physiological studies of the small heat shock protein Lo18 from the lactic acid bacterium Oenococcus oeni.

The small heat shock protein (smHSP) family has been extensively studied in eukaryotic cells. SmHSP assemble into large multimeric structures and possess chaperone activity that can prevent protein aggregation in vitro. Few studies on prokaryotic smHSP are actually available and no smHSP from lactic acid bacteria has been characterized at a biochemical level to date. Here we report on the Lo18 membrane-associated smHSP from the lactic acid bacterium Oenococcus oeni. Using size exclusion chromatography, nondenaturing pore-exclusion PAGE and in vitro and in vivo cross-linking experiments, the multimeric structure of Lol8 from O. oeni or expressed in Escherichia coli was investigated. In vitro, Lo18 is able to form a trimer and a higher oligomer which could be a dodecamer. Experiments strongly suggest that the same structures exist in vivo. First, Lo18 prevented thermal aggregation of citrate synthase and lactate dehydrogenase even at 60degreesC. These findings showed that the prokaryotic smHSP Lo18 can function as a molecular chaperone in vitro. Second, Lo18 did not protect lactate dehydrogenase from thermal inactivation and did not assist in enzymatic activity restoration after thermal aggregation, suggesting that other components may be needed for the refolding of the enzyme in an active conformation. Third, we showed that membrane association of Lo18 depends on the temperature upshift. Moreover, expression of this smHSP was induced by administration of a membrane fluidiser, the benzyl alcohol, suggesting that Lo18 expression could be regulated by the level of membrane fluidity.

Bacterial Proteins↗
PubMed2001

[Neonatal bacterial infection by maternal-fetal contamination: for a change in approach? 1. Detection of Streptococcus agalactiae infection: methods and evaluation of results].

Perinatal group B streptococcal infection has been the subject of numerous studies and despite guidelines established during the last decade remains a frequent disease with high mortality. The basic aim of the guidelines is to screen for Streptococcus agalactiae during the antepartum period in order to institute antibiotic therapy during delivery. A critical review of the literature highlights the real impact and adverse effect of these guidelines: difficult application (only two-thirds of all maternity units have a protocol and compliance is only 75%), maternal risks of antibiotic therapy (especially the emergence of resistant Gram negative bacteria), fetal risks (accentuation of neonatal sepsis with resistant strains, retarded neonatal infections, frequent use of antibiotics with a broader spectrum, higher frequency of nosocomial sepsis).

Anti-Bacterial Agents↗
PubMed2001

[Neonatal bacterial infection by maternal-fetal contamination: for a change in approach? 2. Uncertainties and proposals].

Based on a critical analysis of the literature, it is clear that even though mortality has decreased to 10-15%, the prevalence of neonatal bacterial infections remains dramatically stable. Precise risk factors can be identified in most cases of neonatal infection, but remain uncertain in many others: Streptococcus agalactiae is found in only 40% of the cases of sepsis; Escherichia coli, Haemophilus influenzae, Pneumococcus, and group A Streptococcus strains should also be considered for a real prophylactic strategy; context (prematurity), lack of a consensual attitude for intrapartum strategies; management schemes for asymptomatic neonates. Based on these observations, we make proposals for a realistic attitude for everyday practice based on risk factors, maternal and neonatal bacterial sampling procedures, and modalities for neonatal antibiotic therapy.

Anti-Bacterial Agents↗
PubMed2000

Prenatal diagnosis of Gaucher's disease type 2. Ultrasonographic, biochemical and histological aspects.

We report on the early prenatal diagnosis of fetal Gaucher disease type 2 by ultrasound examination and beta-glucosidase activity assay on amniocytes from a fetus of 15 weeks' gestation whose first sibling fetus had previously been affected with hydrops fetalis. These cases emphasize the importance of the pathological examination of all fetuses presenting with hydrops fetalis and also stress that minimal and precocious echographic signs can be suggestive of such a lysosomal storage disease.

Adult↗