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Biomedical subjects

C Lévêque

Publications and source records attributed to C Lévêque.

At least 19 recordsLinked to original sources
PubMed2006

Magnesium sulphate given before very-preterm birth to protect infant brain: the randomised controlled PREMAG trial*.

OBJECTIVE: To evaluate whether magnesium sulphate (MgSO(4)) given to women at risk of very-preterm birth would be neuroprotective in preterm newborns and would prevent neonatal mortality and severe white-matter injury (WMI). DESIGN: A randomised study. SETTING: Eighteen French tertiary hospitals. Population Women with fetuses of gestational age < 33 weeks whose birth was planned or expected within 24 hours were enrolled from July 1997 to July 2003 with follow up of infants until hospital discharge. METHODS Five hundred and seventy-three mothers were randomly assigned to receive a single 40-ml infusion of 0.1 g/ml of MgSO(4) (4 g) solution or isotonic 0.9% saline (placebo) over 30 minutes. This study is registered as an International Standard Randomised Controlled Trial, number 00120588. MAIN OUTCOME MEASURES: The primary endpoints were rates of severe WMI or total mortality before hospital discharge, and their combined outcome. Analyses were based on intention to treat. RESULTS: After 6 years of enrolment, the trial was stopped. Data from 688 infants were analysed. Comparing infants who received MgSO(4) or placebo, respectively, total mortality (9.4 versus 10.4%; OR: 0.79, 95% CI 0.44-1.44), severe WMI (10.0 versus 11.7%; OR: 0.78, 95% CI 0.47-1.31) and their combined outcomes (16.5 versus 17.9%; OR: 0.86, 95% CI 0.55-1.34) were less frequent for the former, but these differences were not statistically significant. No major maternal adverse effects were observed in the MgSO(4) group. CONCLUSION: Although our results are inconclusive, improvements of neonatal outcome obtained with MgSO(4) are of potential clinical significance. More research is needed to assess the protective effect of MgSO(4) alone or in combination with other neuroprotective molecules.

Adult↗
PubMed2004

Survival of very preterm infants: Epipage, a population based cohort study.

OBJECTIVE: To evaluate the outcome for all infants born before 33 weeks gestation until discharge from hospital. DESIGN: A prospective observational population based study. SETTING: Nine regions of France in 1997. PATIENTS: All births or late terminations of pregnancy for fetal or maternal reasons between 22 and 32 weeks gestation. MAIN OUTCOME MEASURE: Life status: stillbirth, live birth, death in delivery room, death in intensive care, decision to limit intensive care, survival to discharge. RESULTS: A total of 722 late terminations, 772 stillbirths, and 2901 live births were recorded. The incidence of very preterm births was 1.3 per 100 live births and stillbirths. The survival rate for births between 22 and 32 weeks was 67% of all births (including stillbirths), 85% of live births, and 89% of infants admitted to neonatal intensive care units. Survival increased with gestational age: 31% of all infants born alive at 24 weeks survived to discharge, 78% at 28 weeks, and 97% at 32 weeks. Survival among live births was lower for small for gestational age infants, multiple births, and boys. Overall, 50% of deaths after birth followed decisions to withhold or withdraw intensive care: 66% of deaths in the delivery room, decreasing with increasing gestational age; 44% of deaths in the neonatal intensive care unit, with little variation with gestational age. CONCLUSION: Among very preterm babies, chances of survival varies greatly according to the length of gestation. At all gestational ages, a large proportion of deaths are associated with a decision to limit intensive care.

Birth Weight↗
PubMed2002

[Efficacy and safety of inhalation premixed nitrous oxide and oxygen for the management of procedural diagnostic pain in neuropediatrics].

AIM: We studied the use of premixed nitrous oxide and oxygen in 80 patients with neurologic diseases. PATIENTS AND METHODS: Mean ages ranged 10 +/- 5 yrs. Twenty-three patients (29%) were mentally retardated among which 17 of them presented with severe epilepsy. Painful procedures consisted of: lumbar punctures (80%), intravenous access (7), gastric endoscopy (6), skin biopsy (4), gastrostomy tube management (3). High-risk children were continuously monitored using ECG, non invasive blood pressure and transcutaneous oxygen saturation. We studied acceptation of the inhalation, vital signs, satisfaction of children, parents, medical and nursing staffs; side effects were compared with a group of healthy children undergoing venous access before induction of anesthesia. RESULTS AND DISCUSSION: Acceptation increased with age. No significant changes in vital signs variables were observed. Satisfaction rate regarding the method was 88% for all children, parents, physicians and nurses. No serious undesirable event (as respiratory depression, seizure, inhalation of gastric content) occurred in these patients. The more frequent side-effects were: drowsiness during and after inhalation (35 and 9% respectively in the handicapped patients); nausea and vomiting (8%), headaches (3%), were more frequent than reported in literature but there were 25% of meningitis among our patients. CONCLUSION: Premixed nitrous oxide and oxygen was effective for reducing procedural pain and anxiety in children with neurological disorders, even in severely handicapped patients, with minor side-effects.

Administration, Inhalation↗
PubMed2002

[Morphological imagery of the occipital lobe].

After reviewing the anatomical and functional aspects of the occipital lobe, the authors detail its gyral and sulcal anatomy using MRI in the three planes, with particular attention given to the localization of the calcarine fissure.

Humans↗
PubMed2000

[Metastasis in pulmonary arteries].

We report two cases of pulmonary tumor emboli. The first patient had a chondroblastic osteosarcoma of the pelvis while the second patient had a seminoma. The possibility of tumor emboli should be entertained in patients with prior history of malignancy presenting with enlargement of the pulmonary arteries and thrombus enhancement on delayed scans.

Adult↗
PubMed2000

[Clinical application of functional MRI: a strategic tool for neurosurgery].

The purpose was to incorporate preoperative functional imaging data into anatomic data of operative microscope for neurosurgical procedures of patients suffering from lesions contiguous to eloquent brain areas. The day before surgery, patients bearing scalp markers underwent fMRI, just before anatomical contrast-enhanced MR images. FMRI data analysis were realised using a t test (p<0.0001). The resulting functional-anatomical images were downloaded onto a surgical neuronavigation computer in order to outline tumoral target and functional areas. At surgery, cortical stimulation has been used to confirm functional data. Functional image-guided surgery of lesions abutting functional cortex can be safely performed.

Adult↗
PubMed2000

Functional MR imaging and traumatic paraplegia: preliminary report.

PURPOSE: To evaluate residual activity in the sensorimotor cortex of the lower limbs in paraplegia. METHODS: 5 patients suffering from a complete paralysis after traumatic medullar lesion (ASIA=A). Clinical evaluation of motility and sensitivity. 1. Control functional MR study of the sensorimotor cortex during simultaneous movements of hands, imaginary motor task and passive hands stimulation. 2. Concerning the lower limbs, 3 fMRI conditions: 1-patient attempts to move his toes with flexion-extension, 2-mental imagery task of the same movement, 3-peripheral passive proprio-somesthesic stimulation (squeezing) of the big toes. RESULTS: Activations were observed in the primary sensorimotor cortex (M1), premotor regions and in the supplementary motor area (SMA) during movement and mental imaginary tasks in the control study and during attempt to move and mental imaginary tasks in the study concerning the lower limbs. Passive somesthesic stimulation generated activation posterior to the central sulcus for 2 patients. CONCLUSION: Activations in the sensorimotor cortex of the lower limbs can be generated either by attempting to move or mental evocation. In spite of a clinical evaluation of complete paraplegia, fMRI can show a persistence of sensitive anatomic conduction, confirmed by Somesthesic Evoked Potentials.

Adult↗
PubMed1999

Interactions between proteins implicated in exocytosis and voltage-gated calcium channels.

Neurotransmitter release from synaptic vesicles is triggered by voltage-gated calcium influx through P/Q-type or N-type calcium channels. Purification of N-type channels from rat brain synaptosomes initially suggested molecular interactions between calcium channels and two key proteins implicated in exocytosis: synaptotagmin I and syntaxin 1. Co-immunoprecipitation experiments were consistent with the hypothesis that both N- and P/Q-type calcium channels, but not L-type channels, are associated with the 7S complex containing syntaxin 1, SNAP-25, VAMP and synaptotagmin I or II. Immunofluorescence confocal microscopy at the frog neuromuscular junction confirmed that calcium channels, syntaxin 1 and SNAP-25 are co-localized at active zones of the presynaptic plasma membrane where transmitter release occurs. Experiments with recombinant proteins were performed to map synaptic protein interaction sites on the alpha 1A subunit, which forms the pore of the P/Q-type calcium channel. In vitro-translated 35S-synaptotagmin I bound to a site located on the cytoplasmic loop linking homologous domains II and III of the alpha 1A subunit. This direct link would target synaptotagmin, a putative calcium sensor for exocytosis, to a microdomain of calcium influx close to the channel mouth. Cysteine string proteins (CSPs) contain a J-domain characteristic of molecular chaperones that cooperate with Hsp70. They are located on synaptic vesicles and thought to be involved in modulating the activity of presynaptic calcium channels. CSPs were found to bind to the same domain of the calcium channel as synaptotagmin, and also to associate with VAMP. CSPs may act as molecular chaperones in association with Hsp70 to direct assembly or dissociation of multiprotein complexes at the calcium channel.

Animals↗
PubMed1999

[Exposure and good practice in helical computed tomography].

Helical CT is the imaging modality that delivers the highest exposure to patients. For each acquisition, the average radiation dose is between 20 and 30 mGy. This dose can potentially be reduced by decreasing the intensity or voltage and by increasing the pitch. Helical data can be reformatted to obtain images with smaller increment or multiplanar reconstructions, hence reducing the need for additional acquisitions. Hardware and software devices designed for dose reduction must be systematically used. Operators of CT units should be aware of the radiation dose delivered with helical CT and must carefully assess the need of each additional acquisition. Obsolete protocols such as angulation of the gantry for lumbar CT, which increases patient exposure, should no longer be used. Rational use of helical CT decreases radiation exposure and is faster, whereas improper use increases radiation exposure without added benefit.

Filtration↗
PubMed1999

[Proper technics and the reduction of radiation in helical computed tomography].

Helical computed tomography is the main source of ionizing radiation delivery in diagnostic radiology. For each series, average radiation dose is between 20 and 30 mGy. This dose can potentially be reduced by decreasing intensity or voltage and by increasing pitch. Helical acquisition allows reformating of images with smaller increment or different obliquity, and avoids additional irradiation. Hardware and software devices designed for dose reduction must be systematically used. Users of CT systems should be aware of radiation dose delivered with CT and must carefully assess the need of each additional acquisition. Obsolete habits, as gantry tilting for lumbar CT, which increases patient exposure, must be given up. Rational use of helical CT decreases radiation exposure and gains time, whereas thoughtless use increases radiation exposure without real benefit.

Computer Systems↗
PubMed1998

IL-12 indirectly enhances proliferation of 5-FU-treated human hematopoietic peripheral blood CD34+ cells.

Interleukin-12 (IL-12) or natural killer cell stimulatory factor (NKSF), has multiple effects on T lymphocytes and natural killer cells. In this study, the effect of IL-12 on human hematopoiesis was studied by analyzing the growth of CD34+ peripheral blood stem cells (PBSC), in steady state. In the presence of Epo, IL-12 alone or in combination with IL-3 or SCF had no effect on the formation of colonies from CD34+ cells. In culture with Epo, G-CSF, and IL-3, the effect of Flt3-ligand (FL) on CD34+ PBSC was investigated in the presence or absence of IL-12. No additional effect of IL-12 was observed when combined with FL. We evaluated 5-FU-treated human CD34+ PBSC proliferation in cultures with Epo, G-CSF, and IL-3, in the presence or absence of IL-12. No cytokine combination enhanced colony formation from 5-FU-treated CD34+ cells. However, in cultures of 5-FU-treated human CD34+ cells, the most efficient combination was IL-3 + Epo + G-CSF + Accessory cells (CD34-). Furthermore, IL-12 enhanced this colony formation significantly. To investigate whether immature CD34+ cells were responsible for FL or SCF, 5-FU-treated human CD34+ cells were cultured with or without IL-12. Whereas no synergistic effect was observed in combination with IL-12, SCF alone significantly enhanced colony formation. However, the colony number was found to be smaller than with the potent combination of accessory cells in the presence of IL-12. These results indicate that accessory cells, lost in CD34+ cell purification, could be partly responsible for an IL-12 effect on immature human PBSC proliferation.

Adult↗
PubMed1998

Regulation of interleukin 3 receptor alpha chain (IL-3R alpha) on human monocytes by interleukin (IL)-4, IL-10, IL-13, and transforming growth factor beta (TGF-beta).

Human interleukin 3 receptor (IL-3R) is constitutively expressed on committed haematopoietic stem cells, where it mediates proliferation and differentiation. This receptor is also expressed by monocytes and may induce functional activation. Interleukin (IL)-4, IL-10, IL-13, and transforming growth factor beta (TGF-beta) have different effects on human monocytes. As IL-3R may be regulated by different cytokines, whether the above-mentioned cytokines were able to modulate the alpha chain of IL-3R (IL-3R alpha) on monocytes was examined. Effects on IL-3R alpha antigen (Ag) expression were analysed by direct immunofluorescence and flow cytometry. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect variations in IL-3R alpha mRNA expression. IL-10 and TGF-beta were found to downregulate IL-3R alpha Ag. In contrast, IL-4 and IL-13 both caused a dose- and time-dependent increase. A maximum effect was observed at 1 ng/ml of IL-4 for 18 h. Furthermore, in RT-PCR, IL-4 was found to slightly up-regulate IL-3R alpha mRNA expression. These observations suggest that IL-4 and IL-13 play a role in the regulation of IL-3R alpha expression and the effects of cytokines on human monocytes may be mediated, in part, through the regulation of IL-3R.

Antigens↗
PubMed1998

MR of cerebral malaria.

In three cases of cerebral malaria, MR imaging disclosed either cortical infarcts (one case) or hyperintense areas of white matter (two cases) on T2-weighted and fluid-attenuated inversion-recovery sequences. These white matter abnormalities were, in one case, sharply limited, symmetrical, hyperintense, and unenhanced; in the other case, they were diffuse, hyperintense, and had a more limited focus. The diffuse hyperintensity was probably due to edema, whereas focal lesions were probably associated with gliosis.

Adolescent↗