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Biomedical subjects

Pascal Vincent

Publications and source records attributed to Pascal Vincent.

10 recordsLinked to original sources
PubMed2006

High rate of Helicobacter pylori reinfection in children and adolescents.

AIMS: Primary Helicobacter pylori infection occurs predominantly in childhood. The aims of this study were to establish the rate of H. pylori reinfection after successful eradication in children and adolescents and to determine the risk factors associated with reinfection. PATIENTS AND METHODS: This retrospective study involved 45 children (20 girls, 25 boys) who met the following criteria: eradication of H. pylori confirmed at least 4 weeks after the completion of therapy, and the search for reinfection at least one year after control of eradication of H. pylori. Demographic data, socioeconomic status and living conditions were recorded. RESULTS: Forty-five children aged 1.2-17.6 years (median, 10.9 years) at the time of H. pylori treatment were reviewed 1 to 9 years after H. pylori eradication. Eight children (18%) had been reinfected (5.4% to 6% per patient-year). Six of 25 (24%) children older than 10 years at the time of diagnosis became reinfected. None of the studied risk factors was associated with reinfection. However, having a sibling younger than 5 years was found in four of seven (57%) reinfected children versus five of 24 (21%) nonreinfected children (p = .08). CONCLUSION: Children become reinfected more frequently than adults. Adolescents become reinfected, whereas acquisition of primary H. pylori infection occurs predominantly in early childhood. Close contact with young children, especially siblings, younger than 5 years could be a more important risk factor than the age of the patient at the time of treatment for the high rate of reinfection in childhood.

Adolescent↗
PubMed2005

Achieving high-current carbon nanotube emitters.

When a carbon nanotube emitter is operated at high currents (typically above 1 microA per emitter), a small voltage drop ( approximately few volts) along its length or at its contact generates a reverse/canceling electric field that causes a saturation-like deviation from the classical Fowler-Nordheim behavior with respect to the applied electric field. We present a correction to the Fowler-Nordheim equation to account for this effect, which is experimentally verified using field emission and contact electrical measurements on individual carbon nanotube emitters. By using rapid thermal annealing to improve both the crystallinity of the carbon nanotubes and their electrical contact to the substrate, it is possible to reduce this voltage drop, allowing very high currents of up to 100 microA to be achieved per emitter with no significant deviation from the classical Fowler-Nordheim behavior.

Journal Article↗
PubMed2004

Gastroesophageal reflux disease and Helicobacter pylori infection in neurologically impaired children: inter-relations and therapeutic implications.

BACKGROUND: The aim of this retrospective study was to assess the relationship between Helicobacter pylori infection and gastroesophageal reflux disease in a high-risk population of children. METHODS: Forty-three neurologically impaired pediatric patients with H. pylori had upper gastrointestinal endoscopy between 1990 and 2000. Infection was confirmed by positive H. pylori culture or by identification of organisms in gastric biopsy specimens (fundus, n = 2; antrum, n = 3). Reflux esophagitis was diagnosed by ulceration of the esophageal mucosa at endoscopy. Four to 6 weeks after the completion of antibiotic treatment of H. pylori, a second endoscopy was performed and the gross appearance of the esophagus was recorded. RESULTS: At the first endoscopy, esophagitis was noted in 14 of 43 patients. After treatment, H. pylori infection was eradicated in all 14 patients with esophagitis but in only 19 of 29 (66%) of those with normal esophagus (P = 0.01). Esophagitis was still present in 4 of 14 (29%) patients who had esophagitis at the first endoscopy. Persistent esophagitis was only related to the presence of esophagitis before treatment (P = 0.02). In 29 patients with a normal esophagus at the first endoscopy, only one case of esophagitis was observed after H. pylori eradication. CONCLUSION: The data suggest that treatment of H. pylori infection should be considered in children with concomitant GERD, and such treatment is unlikely to either induce or exacerbate peptic esophagitis.

Adolescent↗
PubMed2004

Learning eigenfunctions links spectral embedding and kernel PCA.

In this letter, we show a direct relation between spectral embedding methods and kernel principal components analysis and how both are special cases of a more general learning problem: learning the principal eigenfunctions of an operator defined from a kernel and the unknown data-generating density. Whereas spectral embedding methods provided only coordinates for the training points, the analysis justifies a simple extension to out-of-sample examples (the Nyström formula) for multidimensional scaling (MDS), spectral clustering, Laplacian eigenmaps, locally linear embedding (LLE), and Isomap. The analysis provides, for all such spectral embedding methods, the definition of a loss function, whose empirical average is minimized by the traditional algorithms. The asymptotic expected value of that loss defines a generalization performance and clarifies what these algorithms are trying to learn. Experiments with LLE, Isomap, spectral clustering, and MDS show that this out-of-sample embedding formula generalizes well, with a level of error comparable to the effect of small perturbations of the training set on the embedding.

Algorithms↗
PubMed2003

Epirubicin and paclitaxel (EPI-TAX regimen) for advanced ovarian cancer after failure of platinum-containing regimens.

BACKGROUND: The place of anthracyclines in the treatment of advanced ovarian cancer remains a matter of debate. We have assessed the feasibility and evaluated the tolerance of epirubicin (EPI) combined with paclitaxel (TAX) in heavily pretreated ovarian cancer patients. METHODS: Between March 1996 and March 1998, 34 patients with ovarian cancer in relapse after platinum-based chemotherapy received EPI (75 mg/m(2)/day, iv) and TAX (175 mg/m(2)/day, 3-h infusion). Cycles were repeated every 3 weeks. This treatment was second-line for 10 patients and third/fourth-line for 24. RESULTS: Of the 34 assessable patients, 15 (44%) (95% confidence interval 27-60%) achieved objective response (3 complete and 12 partial responses). The number of previous lines of chemotherapy or previous anthracycline treatments did not influence response rates. Responders to previous paclitaxel-based regimens had a significantly higher response rate to EPI-TAX combination (57%) than nonresponders (11%) (P = 0.05). Median response duration was 40 weeks (range 12-94). Median survival from inclusion was 10.7 months (range 1-40). Myelosuppression was the most frequent side effect. Grade 3/4 neutropenia occurred in 31 patients (91%), febrile neutropenia episodes in 17%, and grade 3/4 anemia and thrombopenia in 27 and 24%, respectively. The main nonhematological toxicities included alopecia and grade 2 peripheral neuropathy (12%). Cardiac dysfunction was observed in one patient after the fourth treatment cycle. CONCLUSIONS: Toxicity of the EPI-TAX regimen was acceptable in this population of heavily pretreated ovarian cancer patients. The regimen was effective and it is considered an option for patients previously responding to paclitaxel-based therapy.

Adult↗
PubMedDate not supplied

[Standards, Options and Recommendations 2000: non metastatic endometrial cancer].

CONTEXT: The "Standards, Options and Recommendations" (SOR) project, started in 1993, is a collaboration between the Federation of French Cancer Centers (FNCLCC), the 20 French Cancer Centers, and specialists from French Public Universities, General Hospitals and Private Clinics, and some specialists learned societies. The main objective is the development of clinical practice guidelines to improve the quality of health care and the outcome of cancer patients. The SORs are developed using a methodology based on a literature review and critical appraisal by a multidisciplinary group of experts, with feedback from specialists in cancer care delivery. OBJECTIVES: To develop clinical practice guidelines for the management of patients with carcinoma of the endometrium according to the definitions of the Standards, Options and Recommendations project. METHODS: Data were identified by searching Medline , web sites, and using the personal reference lists of members of the expert groups. Once the guidelines were defined, the document was submitted for review to 63 independent reviewers. RESULTS: The main recommendations for the management of carcinoma of the endometrium are: 1) The diagnosis of carcinoma of the endometrium is based on biopsy and histological examination. However, as first intention, the first elements for diagnosis can be obtain from a hysterography, or particularly, a endovaginal ultrasound examination. Ultrasound allows locoregional metastases to be detected, the CT scan allows the lymph node involvement to be assessed and magnetic resonance imaging allows the myometrium invasion to be evaluated. 2) For the majority of patients, surgery is the initial treatment, both for localised and advanced-stage carcinomas. The excised sample can be used for pathological analysis and tumour staging, using the FIGO (Fédération internationale de gynécologie obstétrique) classification. Surgery for patients with stage I and II carcinomas involves total extrafascial hysterectomy with bilateral salpingo-oophorectomy., In patients with stage III and IV carcinomas radical surgery should be performed, when possible. If this is not possible, then surgery should be as complete as possible and be associated with a complementary treatment. In patients with the most advanced carcinomas, tumour reduction by surgery should be performed. 3) Complementary treatment includes external-beam radiotherapy and brachytherapy. The decision concerning the extent and type of irradiation should be taken taking into consideration the stage and the prognostic factors present. For patients with stage I and II carcinoma, complementary treatment with brachytherapy can be performed, if the myometrium invasion is not deep, or if the carcinoma is grade 2 or 3. Patients with stage III carcinomas can be treated with pelvic or abdominal-pelvic complementary irradiation. In patients that cannot undergo surgery, exclusive radiotherapy can be performed. 4) In the absence of any symptoms, surveillance should include a general clinical and gynaecological examination. All patients with symptoms should undergo an additional work-up.

Endometrial Neoplasms↗