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Biomedical subjects

F Nadal

Publications and source records attributed to F Nadal.

12 recordsLinked to original sources
PubMed2005

Electrically induced microflows probed by fluorescence correlation spectroscopy.

We report on the experimental characterisation of electrically induced flows at the micrometer scale through Fluorescence Correlation Spectroscopy (FCS) measurements. We stress the potential of FCS as a useful characterisation technique in microfluidics devices for transport properties cartography. The experimental results obtained in a model situation are in agreement with previous calculations (F. Nadal, F. Argoul, P. Kestener, B. Pouligny, C. Ybert, A. Ajdari, Eur. Phys. J. E 9, 387 (2002)) predicting the structure and electric-field dependency of the induced flow. Additionally, the present study evidences a complex behaviour of the probe nanobeads under electric field whose precise understanding might prove relevant for situations where nano-objects interact with an external electric field.

Electrochemistry↗
PubMed2002

Electrically induced flows in the vicinity of a dielectric stripe on a conducting plane.

We report a theoretical and experimental study of the hydrodynamic flow induced by an a.c. electric field in the vicinity of a dielectric stripe deposited on a conducting plate. In the theoretical part, we model the stripe as a small change of the surface capacitance of the plate, and a perturbative approach is used to perform the calculations. This approach predicts an outwards rectified electro-osmotic slip along the surface that generates two steady counter-rotating rolls, the size of which decreases with the frequency. In the experimental section, we use tracers to determine the structure of the flow and investigate its dependence on the frequency and the amplitude of the applied voltage. The structure and amplitude of the observed flow compares satisfactorily with the theoretical analysis. This could guide the design of surface-controlled flows and help to understand the collective behavior of colloids near electrodes.

Journal Article↗
PubMed1997

Negative regulation of mitogen-activated protein kinase activation by integrin alphaIIbbeta3 in platelets.

Activation of the mitogen-activated protein (MAP) kinase pathway in nucleated cells is dependent on both growth factor receptors and integrins engaged in cell adhesion. Human platelets are an interesting model for studying cell adhesion and the involvement of integrin engagement on extracellular signal-regulated kinase (ERK) activation, independently from the nuclear-DNA signal pathway. Maximal phosphorylation and activity of ERK2 occurred late during thrombin-induced platelet aggregation (90 s and later), an alphaIIbbeta3 integrin-dependent event. Surprisingly, alphaIIbbeta3 inhibition by the RGDS ligand peptide, or (Fab')2 fragments of the AP-2 monoclonal antibody, resulted in a 2-fold enhancement in ERK2 phosphorylation and activity. A similar 2-fold enhancement of ERK2 activation was observed in thrombasthenic platelets which are defective in alphaIIbbeta3 and do not aggregate. This suggests that ERK2 activation in thrombin-induced platelet aggregation is dependent on thrombin rather than on alphaIIbbeta3 and is down-regulated by alphaIIbbeta3 engaged in ligand (fibrinogen) binding and/or aggregation. Finally, in the absence of stirring which allows fibrinogen binding to alphaIIbbeta3 but prevents aggregation, ERK2 was again overactivated. This overactivation appears to be consecutive to inhibition of aggregation itself and to alphaIIbbeta3 ligand binding. We conclude that in platelets, alphaIIbbeta3 engaged in aggregation down-regulates thrombin-induced ERK2 activation. To our knowledge, this is the first report of a down-regulation of the MAP kinase pathway by integrin engagement.

Blood Platelets↗
PubMed1993

[Delivery after 2 previous cesarean sections. A series of 41 uterine trials].

It has been possible to consider how delivery should be carried out in view of the progress that has been made handling scarred uteruses. Over 21 months 41 tests of uterine function have been authorized in our department out of 67 cases where there were two scars in the uterus (67%). 26 patients delivered vaginally (63.4%) and 5 had Caesarean sections because of failure of the test of the scar. When the relationship between the fetus and the pelvis was satisfactory, the fact that the cervix was not ripe and the presenting part was not engaged, did not prevent carrying out a trial of scar in 78% of cases. It is important to assess conditions continuously during labour and this assessment should include fetal heart monitoring, internal tokometry, fetal pH assessment and ultrasound of the scar at the onset of labour. Oxytocics had to be used in 96.2% of cases because there was at the outset marked dynamic dystocia. Epidural anaesthesia was used in 90.2% of cases. A full obstetric team must be present throughout the whole labour so that the conduct of the labour can be observed, and if necessary corrected quickly if anything in its progress is becoming abnormal. It has become reasonable to carry out tests of uterine scars even after two scars have been made in the uterus because of the absence of any maternal or fetal complications in this series or in the literature.

Anesthesia, Epidural↗
PubMed1992

[Treatment of urinary stress incontinence by a modified Pereyra procedure:Chrub's operation].

The authors report the utility of suspending the cervix by means of the pubo-urethrax ligaments anchored to Cooper's ligaments in treating exercise-related urinary incontinence. A prospective series of 40 female patients gave 97.5% of successful outcomes with regard to the incontinence. The use of the pubo-urethrax ligaments and the absence of subsphincterian dissection confers major urodynamic advantages, particularly with regard to closing pressure. These anatomical and physiological arguments appear to give the procedure an advantage over suspensions using the vagina wall, whether these make use of the upper or lower route. Anchoring to Cooper's ligaments should ensure long-term stability of the outcome.

Adult↗
PubMed1992

[Indications for operative hysteroscopy. A series of 418 interventions].

Over a period of 38 months, from October 1, 1987 to December 31, 1990, 418 surgical hysteroscopies were carried out following systematic pre-operative hysteroscopy. Two-hundred and eighty-two patients presenting with a benign intercavitary lesion were treated by transcervical endo-uterine resection (EUR). The efficacy of the surgical method was assessed from the control of hemorrhagic phenomena, the most frequent sign. 89.7 percent of the patients who presented with menometrorrhagia, had become asymptomatic from the first cycle after EUR and 83.5 percent remained asymptomatic after a mean follow-up period of 28 months, 71 endometrectomies were carried out by EUR during this period, after careful hysteroscopic and histological evaluation of the endometrium. The results after one year of cycles were satisfactory in 82 percent of patients. Twenty-two patients presenting with a uterine septum were treated by endoscopic hysteroplasty. In most cases, the authors used the tip of the Charriere 21 resector. The follow-up period exceeds 1 year in 15 patients, 11 of whom became pregnant, giving birth to 9 live infants, 43 cases of synechia were treated by hysteroscopy in the context of Ashermann's syndrome. The functional results were good in 90 percent of patients, with the restoration of normal cycles. Only limited results were obtained in fertility in cases of muscular or fibrous synechia. The risks linked to surgical hysteroscopy are analysed. They appear to be acceptable, on condition that rigorous methods are used. The quality of sequelae and the short hospitalization make operative hysteroscopy preferable in the selected indications.

Adult↗
PubMed1992

[Conservative treatment of cancer of the ovary].

The authors assess the potential of conservative treatment in a series of cases of ovarian cancer. Surgical evaluation is essential, in order to confirm that the conditions required for conservative treatment are present. The tumor must be a stage IA tumor, with a low histoprognostic score and small in size. Conservative treatment must be proposed in cases of tumors of potential malignancy and tumors of the sexual cords. It is debateable in epithelial tumors. The question of the necessity of further surgery to remove the genital tract after the desired pregnancies may be debateable in cases of epithelial tumors.

Adolescent↗
PubMed1992

[Hysteroscopic endometrial reduction. Analysis of 85 cases].

The authors report the results of their experience of hysteroscopic endometrial reduction through a retrospective series of 85 patients who underwent surgery between October 1988 and February 1991. The indication consisted of hemorrhage (menorrhagia and metrorrhagia) of endometrial origin in women with a group mean age of 46 years who had no intention of becoming pregnant in the future. The pre-treatment assessment was based on diagnostic hysteroscopy and was intended to eliminate neoplasm of the endometrium or its precursors. The endometrial reduction procedure always preserved an isthmic ring of endometrial tissue. No peroperative complication was reported. The mean duration of surgery was about 39 minutes. With a follow-up period of more than one year, bleeding had disappeared in 78% of cases. The authors conclude that the technic of endometrial resection in the treatment of benign lesions of the endometrium, on condition that the possibility of any disorder calling for laparotomy is ruled out and that there is regular postoperative follow-up.

Adult↗
PubMed1992

[Triplet pregnancies in France. Results of a retrospective, multicenter study of two years (1987-1988). Proposals for optimal management].

The explosion of procedures for medically assisted parenthood (MAP) has resulted in a previously little known type of pregnancy: triple pregnancies. In order to assess the current obstetrical and pediatric situation, the authors have carried out a major retrospective, multicenter survey in France concerning the triple pregnancies from 1987 to 1988: 156 case histories have been collected. The finds are compared with those reported in the French and international literature, showing that in France, three-quarters of such pregnancies result from MAP, mainly due to ovulation-inducing agents. Hospitalization is prolonged (averaging 27 days), early (24 WA) and imposed by complications (in 8 out of 10 cases), prophylactic hospitalization being rarely prescribed. The main complications encountered are late miscarriages (1.9%), in-utero death (6.41%), dysgravidia (16.6%), hydramnios (5.12%) and serious cardio-pulmonary complications related to the use of beta-mimetics. A Cesarian is performed in only 87 percent of cases. The mean birth weight was 1,776 g. Neonatal mortality is on the decline, but still equivalent to 80.3 per thousand. Hypotrophy is common (27%). Birth is nearly always premature (99.3%), but very early prematurity (28-32 WA) was reduced. The approach suggested for optimum management is based on the personal experience of the authors, the findings of their survey and of the international literature. It is based on the prevention of prematurity and a fundamentally multidisciplinary approach.

Adult↗
PubMed1992

[Effects of preinduction by mifepristone on therapeutic abortions of the second and third trimesters induced by intravenous sulprostone].

The authors investigate the effects of preinduction by administering 600 mg of mifepristone (RU486) per os before medical termination of pregnancy during the third to ninth months of pregnancy by intravenous sulprostone (Nalador). The study included a population of 35 patients treated with RU486 and then Nalador versus a population of 38 patients treated with Nalador only. The characteristics of the two groups did not show any statistically significant differences (medical, surgical and obstetric difference, indication for termination). The gestational age was lower in the RU486-Nalador group (group mean age : 20.9 weeks of amenorrhea versus 23.3, p less than 0.01). The group receiving RU486 significantly demonstrated the following : reduced time for induction of labour to modifications of the cervix (7.2 h versus 10.9 h, p less than 0.05), a higher number of rapid expulsions (within 10 h in 37.1% versus 15.7%, p less than 0.05) and a reduction of side effects (45.7% versus 71.05%, p less than 0.05). The other parameters analysed (duration of termination, total dose of prostaglandin) appeared to be better with RU486, but the values were not significantly different.

Abortifacient Agents, Nonsteroidal↗
PubMed1990

[The results of urethro-cervicolysis after surgical over-correction of stress urinary incontinence. Apropos of 10 cases].

Between 1985 and 1988, 10 female patients between the ages of 35 and 76 years, suffering from dysuria after surgical correction of urinary stress incontinence (7 sub-urethral bands, 3 colposuspensions) were observed. The abnormality of the course of the urethra compressed anteriorly against the symphysis pubis, observed on clinical examination and on intravenous pyelography as well as urodynamic investigations allowed this dysuria to be attributed to a cervico-urethral obstruction resulting from over correction during the initial surgical operation. The 10 patients were treated by urethro-cervicolysis (9 out of 10) associated with repeated colposuspension in 3 cases. The overall results were disappointing as although 8 of the 10 patients were improved at 3 month, only 4 out of 9 were still improved at 6 months. These poor results raise the question of the value of combining urethro-cervicolysis with colposuspension and possible VY plasty of the bladder neck.

Adult↗