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Biomedical subjects

A Fontaine

Publications and source records attributed to A Fontaine.

At least 19 recordsLinked to original sources
PubMed2003

[Evaluating the effectiveness of child lead poisoning prevention programs].

PROBLEM: A multi annual screening and prevention program against lead poisoning was implemented in a suburb of the Paris area. We attempted to assess the effectiveness of this program based on data available from children screening and follow-up. METHODS: Indicators of effectiveness included the evolution of blood lead levels at screening and the frequency of secondary increases in blood lead levels. Buildings inclusion dates were used to control for the increasing selection of less exposed children. RESULTS: A total of 3,660 children were screened between 1992 and 2000. We observed a regular decrease in blood lead levels at screening, in the highest blood lead levels obtained for each child and in the proportion of children whose blood lead levels increased after screening: the proportion of children with initial blood lead levels >=15 micro g/dl fell from 17.4% in the 1992-1996 period to 4.1% in the 1997-2000 period. A multivariate analysis taking into account the first year that children were screened in a given building showed that less exposed children were included over time, but found also an additional independent decrease in blood lead levels that can be related to the effectiveness of prevention efforts. A "building by building" analysis of 30 buildings where more than 20 children were located over the whole study period confirmed that the incidence of lead poisoning decreased within most of these buildings. CONCLUSIONS: Taking into account buildings'inclusion dates makes it possible to distinguish program effectiveness from the consequences of including less exposed children The effectiveness of preventive actions is associated with several interacting factors, including the participation of families and the active involvement of local technical staff and policy makers. The finding that the decrease in blood lead levels leveled off after 1997 calls for further actions.

Child↗
PubMed2002

Anatomical study of the blood supply of the coxal bone: radiological and clinical application.

The aim of this work was to study the arterial blood supply of the coxal bone in order to optimize radiological embolization and to minimize the risk of postoperative osteonecrosis. Ten fresh cadavers were dissected after intra-arterial injection of colored resin. All the collateral vessels running to this bone were described and counted. On 25 dry bones, the vascular foramina were measured with the aid of a millimetric gauge and a vascular map was created. The posterior part of the ilium appears to be twice as well vascularized as the anterior part. Fractures of the posterior arch of the pelvis are theoretically more hemorrhagic. The presence of the iliolumbar artery in contact with the sacroiliac joint increases the risk with open book or shearing fractures. The artery of the ischium, a collateral of the pudendal artery, supplies the posterior and lateral parts of the acetabulum and the artery of the roof of the acetabulum, its superior and lateral parts. The branches of the anterior and posterior divisions of the obturator artery supply the superior part of the surroundings of the obturator foramen and the antero-inferior and postero-inferior parts of the acetabulum. The Kocher approach may injure the artery of the ischium. Letournel's extended lateral approach and Mears' triradiate approach may injure the artery of the ischium and the artery of the roof of the acetabulum. The risk of osteonecrosis appears to be theoretically increased if one adds an endopelvic approach. The anterior approach to the acetabulum appears to be that which theoretically leads to the least devascularization. The French version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer Link server located at http://dx.doi.org/10.1007/s00276-002-0029-2.

Arteries↗
PubMed2001

Element-selective nanosecond magnetization dynamics in magnetic heterostructures.

We have developed a new original technique to study the magnetization reversal dynamics of thin films with element selectivity in the nanosecond time scale. X-ray magnetic circular dichroism measurements in pump-probe mode are carried out taking advantage of the time structure of synchrotron radiation. The dynamics of the magnetization reversal of each of the layers of complex heterostructures (like spin valves or tunnel junctions) can be probed independently. The interlayer coupling in the studied systems has been shown to play a key role in the determination of the magnetization reversal of each individual layer.

Journal Article↗
PubMed2001

X-ray magnetic circular dichroism in FeZrB amorphous alloys: the influence of the tensile stress.

We present X-ray Magnetic Circular Dichroism experiments (XMCD) on the Fe K edge of FeZrB metallic glasses performed under tensile stress. In these compounds the application of tensile stresses produces a large increase of the Curie Temperature. The XMCD signal presents the features expected for a weak ferromagnet but a gradual enhancement of the ferromagnetism is observed as boron and zirconium concentrations increase. The main effect of the tensile stress is to increase the density of states at the Fermi level as deduced from the increment of the amplitude of the XMCD signal with the stress.

Journal Article↗
PubMed2001

Ehlers-Danlos syndrome mimicking mesenteric vasculitis: therapy, then diagnosis.

The etiology of acute intraabdominal bleeding is often unclear at the time emergent arteriography is performed. During localization and embolization, the arteriogram may suggest the diagnosis of vasculitis. However, controlling the bleeding remains the priority. Connective tissue diseases such as Ehlers-Danlos syndrome (EDS) may also cause bleeding and mimic vasculitis and must be included in the differential diagnosis. We present such a case in which the initial findings were misleading.

Adult↗
PubMed2001

Integrating particle image velocimetry and laser Doppler velocimetry measurements of the regurgitant flow field past mechanical heart valves.

This study investigates the transient regurgitant flow downstream of a prosthetic heart valve using both laser Doppler velocimetry (LDV) and particle image velocimetry (PIV). Until now, LDV has been the more commonly used tool in investigating the flow characteristics associated with mechanical heart valves. The LDV technique allows point-by-point velocity measurements and provides enough information about the temporal variations in the flow. The main drawback of this technique is the time consuming nature of the data acquisition process in order to assess an entire flow field area. The PIV technique, on the other hand, allows measurement of the entire flow field in space in a plane at a given instant. In this study, PIV with spatial resolution of 0 (1 mm) and LDV with a temporal resolution of 0 (1 ms) were used to measure the regurgitant flow proximal to the Björk-Shiley monostrut (BSM) valve in the mitral position. With PIV, the ability to measure 2 velocity components over an entire plane simultaneously provides a very different insight into the flow field compared to a more traditional point-to-point technique like LDV. In this study, a picture of the effects of occluder motion on the fluid flow in the atrial chamber is interpreted using an integration of PIV and LDV measurements. Specifically, fluid velocities in excess of 3.0 m/s were recorded in the pressure-driven jet during valve closure, and a 1.5 m/s sustained regurgitant jet was observed on the minor orifice side. Additionally, the effects of the impact and subsequent rebound of the occluder on the flow also were clearly recorded in spatial and temporal detail by the PIV and LDV measurements, respectively. The PIV results provide a visually intuitive way of interpreting the flow while the LDV data explore the temporal variations and trends in detail. This analysis is an integrated flow description of the effects of valve closure and leakage on the pulsatile regurgitation flow field past a tilting-disc mechanical heart valve (MHV). It further reinforces the hypothesis that the planar flow visualization techniques, when integrated with traditional point-to point techniques, provide significantly more insight into the complex pulsatile flow past MHVs.

Blood Flow Velocity↗
PubMed2000

[Undergraduate medical education. Students' perspective and medical school policy].

OBJECTIVES: Student attendance to lectures in French medical schools is often poor. We surveyed undergraduate medical students in our medical school, repeating a similar survey conducted ten years earlier. The results are presented with the conclusions of the faculty seminar that followed this survey. METHODS: A closed item questionnaire was distributed in June, 1998, through the hospital wards where the students were posted. After two reminders, the final response rate was 71% (247/348). RESULTS: Overall, 71% of the students declared that they never, or only occasionally, attended lectures in the medical school. Reasons included lack of time (75%), the curriculum diverging from the program of the selective examination that gives access to graduate specialization programs (59%), or insufficient practical clinical content (36%); 46% believed that this teaching prepared them to practice family medicine (11% some specially), and 92% that the way it was organized was not compatible with preparing for the selective examination. On the other hand, 75% of the students in the final two years of the curriculum declared that attending regularly special preparation seminars for the selective examination, to succeed at this test (91%), but also to prepare for family practice (25%). Respectively, 75%, 68% and 66% declared that undergraduate medical courses should, ideally, prepare them for the selective examination, but also for the practice of family medicine, and for graduate medical education. CONCLUSIONS: These results echoed the difficulties of the faculty of the medical school to reconcile preparing students both for their future medical practice and for the selective examination. Two working groups were asked to identify independently appropriate educational objectives according to each perspective: their conclusions appeared to be quite compatible. Based on these conclusions, institutional objectives were ratified to guide the educational policy of our medical school, including the following: to reinforce the consistency and progressiveness of the curriculum; to promote active and autonomous student learning approaches; to develop faculty teaching skills, curriculum evaluation and recognition of teaching activities.

Curriculum↗
PubMed2000

Fluid dynamics of a pediatric ventricular assist device.

The number of pediatric patients requiring some form of mechanical circulatory assistance is growing throughout the world because of new surgical procedures and the success of pediatric cardiac transplantation. However, the salvage rate for those patients requiring circulatory support may be as low as 25%. Despite the fact that Penn State's 70 cc pneumatic ventricular assist device has been used with a success rate of over 90% in more than 250 patients worldwide, efforts to scale down the pump have encountered difficulties. Animal experiments with a 15 cc version were unsuccessful, with explanted pumps showing extensive thrombus deposition within the pumping chamber. The materials used to fabricate the smaller pump as well as the basic operating principles are identical to the successful adult-sized version. It is therefore believed that reducing the size of the pump altered the internal flow field, and that fluid dynamic factors were responsible for the high degree of thrombus observed with the implanted devices. A dimensional analysis was conducted that revealed significant differences in both Reynolds (Re) and Strouhal (St) numbers between the successful and unsuccessful pumps. Two component laser Doppler velocimetry was then used to characterize the internal flow field quantitatively. Comparison with data from the 70 cc pump showed a reduction in wall shear stress and turbulence levels in the 15 cc pump that would yield an environment conducive to clot formation.

Adult↗
PubMed2000

MRI analysis of brain atrophy after severe closed-head injury: relation to clinical status.

The purpose of this study was to determine the clinical correlates of supratentorial ventricular dilations and of corpus callosal atrophy at the subacute stage after a severe closed-head injury (CHI). Thirty-three CHI patients underwent MRI 2 months or more after injury. Morphometric measures were compared to clinical data (coma score, coma duration and Glasgow Outcome Scale). There were numerous significant correlations between clinical data and mid-third ventricle and frontal horns measurements. Fewer significant correlations were found with the lateral ventricle bodies and the corpus callosal body. There was no significant correlation with the posterior part of the corpus callosum and of the ventricles. Corpus callosum atrophy correlated significantly with anterior and deep ventricular dilatation. In conclusion, the best indicator of clinical status was ventriculomegaly, and particularly third ventricle enlargement, which probably reflects the extent of both anterior and deep white matter lesions.

Adult↗
PubMed2000

Flow visualization in mechanical heart valves: occluder rebound and cavitation potential.

High density particle image velocimetry, with spatial resolution of O(1 mm), was used to measure the effect of occluder rebound on the flow field near a Bjork-Shiley Monostrut tilting-disk mitral valve. The ability to measure two velocity components over an entire plane simultaneously provides a very different insight into the flow compared to the more traditional point to point techniques (like Laser Doppler Velocimetry) that were utilized in previous investigations of the regurgitant flow. A picture of the effects of occluder rebound on the fluid flow in the atrial chamber is presented. Specifically, fluid velocities in excess of 1.5 m/s traveling away from the atrial side were detected 3 mm away from the valve seat in the local low pressure region created by the occluder rebound on the major orifice side where cavitation has been observed. This analysis is the first spatially detailed flow description of the effects of occluder rebound on the flow field past a tilting-disk mechanical heart valve and further reinforces the hypothesis that the rebound effect plays a significant role in the formation of cavitation, which has been implicated in the hemolysis and wear associated with tilting-disk valves in vivo.

Biomedical Engineering↗
PubMed2000

Multicenter prospective study of ventilator-associated pneumonia during acute respiratory distress syndrome. Incidence, prognosis, and risk factors. ARDS Study Group.

We investigated the incidence, risk factors for, and outcome of ventilator-associated pneumonia (VAP) in patients with acute respiratory distress syndrome (ARDS). We compared 134 patients with ARDS with 744 patients without ARDS on mechanical ventilation. Fiberoptic bronchoscopic examination and quantitative bacterial cultures (protected brush or catheter sampling [threshold: 10(3) cfu/ml], or bronchoalveolar lavage [threshold: 10(4) cfu/ml]) were used to diagnose pneumonia. VAP occurred in 49 patients (36.5%). The incidence of pneumonia was 23% (173 of 744 patients) among patients without ARDS (p < 0.002). Nonfermenting gram-negative rods caused significantly more pneumonia in ARDS patients. Mortality rates were identical in ARDS patients with (28 of 49 patients, 57%) and without (50 of 85 patients, 59%) pulmonary infection (p = 0.8). VAP resulted in a considerable increase in attributable time on mechanical ventilation of both the overall population of ARDS patients and of survivors. Both the use of sucralfate (adjusted odds ratio [OR]: 4. 42; 95% confidence interval [CI]: 2.01 to 9.7, p = 0.0002) and the duration of exposure to sucralfate (adjusted OR: 1.206; 95% CI: 1. 095 to 1.328, p = 0.0002) were associated with an increased risk of VAP during ARDS. VAP considerably prolongs the time on mechanical ventilation without affecting survival. Patients given sucralfate may be at greater risk of developing pulmonary infection during ARDS.

Adult↗
PubMed2000

[Length of stay in maternity wards after normal delivery: diverging point of views].

OBJECTIVES: To compare maternity ward professionals' and patients' views regarding the length of stay in the maternity after a normal delivery and to explore working relationships with ambulatory health professionals. METHODS: Three surveys RESULTS: General professional agreement on a minimum of 4 days; few contacts with ambulatory health professionals. One third of the women found their length of stay excessive. Most did not appear to gain new skills after 3 days, nor to encounter major difficulties once they returned to their home. DISCUSSION: and conclusion. It will be essential to organize effective working relationships between the maternity ward and ambulatory health professionals to ensure appropriate follow-up after an earlier discharge from the hospital, in agreement with the capabilities and expectations of a majority of women.

Adult↗
PubMed1999

Functional anatomy of neuropsychological deficits after severe traumatic brain injury.

BACKGROUND: Neurobehavioral disorders after severe traumatic brain injury (TBI) are poorly correlated with focal lesions detected by structural neuroimaging techniques such as CT scan or MRI. OBJECTIVE: To explore the relationships between regional cerebral glucose metabolism at rest, as measured by PET, and neurobehavioral status after severe TBI at the subacute stage. METHODS: Thirteen patients without focal structural lesion on MRI were studied. Neuropsychological assessment included tests of memory, attention and speed of information processing, and executive functions, and a global neurobehavioral assessment. Regional cerebral glucose metabolism at rest was measured with (18F)-fluorodeoxyglucose and PET. RESULTS: A close link was found between cognitive and behavioral disorders and decreased cortical metabolism in prefrontal and cingulate cortex. Tests of memory and executive functions significantly correlated with regional metabolism in the mesial and lateral prefrontal cortex and the cingulate gyrus. Behavioral disorders correlated significantly with mesial prefrontal and cingulate metabolisms. CONCLUSION: These results suggest a predominant role of prefrontal and cingulate dysfunction in cognitive and behavioral disorders of patients with severe traumatic brain injury, even in the absence of focal structural lesion of the brain. Further cognitive functional activation research using PET or functional MRI might help clarify the relative contributions of both areas to dysfunction.

Adolescent↗
PubMed1999

[Access to health services: difficulties encountered by refugees residing on Ile-de-France. Charity and full-coverage health care: two divergent concepts?].

Theoretically, since 1992, 100% of socially underprivileged persons residing in France have unlimited access to health care. However, before they become fully integrated into the society, many refugees in various legal situations do not have access to health care. The mechanisms behind this exclusion unmask the difficulties the health care system has in managing the underprivileged population. This work was conducted at the Comede health care facility specially designed to care for refugees. According to the current French legislation, health care protection and medical insurance coverage is a right of all persons living in France. Although the establishment of a large number of centers specifically designated for the underprivileged population has improved access to health care, repeat visits and uninterrupted care cannot be assured unless the patient has been awarded 100% free health care status. There are several obstacles to acquiring this status: complexity of the legal procedures, recipients unaware of their rights and the procedures of the health care system, information limited to specialized journals, restrictive or illegal action by the health protection services. All of these obstacles can be overcome if the patients are given precise information, notably by their physician. Instead of effectively applying the procedures concerning patients rights to health care, the system has developed free health care facilities which do not necessarily provide uninterrupted care. To provide the universal health care coverage promised by the legislators, the only criteria for access to care must be residence in France. Acquiring this status should be considerably simplified and requires the active participation of the entire health care community.

Health Services Accessibility↗
PubMed1999

Physicians' recognition of the symptoms experienced by HIV patients: how reliable?

To assess how well physicians recognize common symptoms in HIV patients and identify factors associated with symptom recognition, a multicenter cross-sectional survey was performed in a random sample of 118 hospitalized and 172 ambulatory HIV patients, and their attending physicians. Patients' reports of 16 different symptoms were compared to physicians' reports of whether each symptom was present and/or specific treatments prescribed. Overall, fatigue, anxiety, skin problems, fever, and weight loss were more often recognized by physicians than other symptoms. Agreement between patients and physicians was poor to moderate, with Kappa statistics ranging from 0.17 (dry mouth) to 0.58 (fever). Recognition was independently more likely for ambulatory patients (adjusted odds ratio 1.69, P < 0.001) and for patients seen as sicker (adjusted odds ratio 1.88, P < 0.001). Appropriate symptom management requires improved symptom recognition. More systematic clinical examinations, including attentive patient interview, are needed.

Adult↗
PubMed1999

Diurnal variations in keratometry and refraction with intracorneal ring segments.

PURPOSE: To study refraction variations during the day in eyes with intrastromal corneal ring segments (ICRS) to correct low myopia. SETTING: Monticelli Clinic, Marseille, France. METHODS: Thirteen eyes with ICRS were included in the study; the ICRS was explanted from 3 eyes because of undercorrection. The minimum follow-up in all eyes was 1 year. The same observer measured refraction and keratometry at 9:00 AM, 1:00 PM, and 7:00 PM with the same autokeratorefractometer. To validate the analysis method, these eyes were compared with a group of emmetropic control eyes that had not had surgery and with a group of eyes that had photorefractive keratectomy for a similar degree of myopia. All measurements were done under the same conditions. RESULTS: After 1 year, the ICRS eyes showed a tendency toward an evening myopic shift. This was confirmed by the objective keratometry study, which showed variations closely correlated with the myopia observed. These phenomena were not observed in the other groups. CONCLUSION: The ICRS had satisfactory predictability in eyes with up to -3.50 diopters of myopia. However, the evening myopic shift appeared similar to that observed after radial keratotomy.

Adult↗
PubMed1999

Evolution of the French public's knowledge and attitudes regarding postoperative pain, cancer pain, and their treatments: two national surveys over a six-year period.

UNLABELLED: Pain management has become a notable feature of public health policy and mass media communication in France over the past few years. To assess the evolution of the knowledge and attitudes of the French population with respect to pain management and morphine use, telephone surveys using similar questionnaires were conducted in 1990 (n = 1001) and 1996 (n = 1006). The proportion of respondents who would take pain management adequacy into consideration when selecting a surgical facility increased from 52% to 81% (P < 0.001), as did the proportion who associated morphine with pain treatment (from 44% to 80%; P < 0.001) or who would not be afraid of becoming addicted to morphine after it had been prescribed for pain relief (from 26% to 69%; P < 0.001). However, the proportion of respondents who agreed that morphine can be prescribed to patients with pain increased only slightly. In 1996, 58% of the respondents believed that their knowledge had improved over the past 5 yr and associated this improvement first with television, followed by written press articles and by interaction with physicians. Increased awareness of pain management possibilities among the public may generate increased demand on health professionals to provide adequate and precise information addressing each patient's needs. IMPLICATIONS: The results of two representative surveys conducted over a 6-yr interval show significant improvements of knowledge and attitudes regarding pain and its management in the French general population. However, these results point to the need for additional specific information that should be provided through patient-physician interactions.

Adolescent↗