Nonparametric methods for the estimation of the conditional distribution of an interval-censored lifetime given continuous covariates

Cette thèse contribue au développement de l'estimation non paramétrique de la fonction de survie conditionnelle étant donné une covariable continue avec données censurées. Elle est basée sur trois articles écrits avec mon directeur de thèse, le professeur Thierry Duchesne. Le premier article, intitulé "Une généralisation de l'estimateur de Turnbull pour l'estimation non paramétrique de la fonction de survie conditionnelle avec données censurées par intervalle, " a été publié en 2011 dans Lifetime Data Analysis, vol. 17, pp. 234 - 255. Le deuxième article, intitulé "Sur la performance de certains estimateurs nonparamétriques de la fonction de survie conditionnelle avec données censurées par intervalle, " est parru en 2011 dans la revue Computational Statistics & Data Analysis, vol. 55, pp. 3355-3364. Le troisième article, intitulé "Estimation de la fonction de survie conditionnelle d'un temps de défaillance étant donné une covariable variant dans le temps avec observations censurées par intervalles", sera bientôt soumis à la revue Statistica Sinica

Hearing loss etiology in patients referring to Isfahan cochlear implantation center

Introduction: Hearing loss is the most common congenital disorders occurring among newborn. Identifying the factors affecting it would reduce the incidence of this disorder. Therefore, the aim of this study was to examine the etiology of congenital hearing loss in patients referring to Isfahan Cochlear implantation center. Materials and Method: This study was performed on 689 patients with cochlear implantation. Demographic data and relative frequency of different causes of congenital hearing loss (acquired and genetic) were determined and recorded. T-test, Chi-Square and Mann-Whitney tests were used to compare the variables studied. Results: Our findings showed that 50 patients (7.7%) had history of drug use, 9 (1.3%) had history of taking ototoxic drugs, 99 (14.3%) had history of kernicterus, 157 patients (22.8%) had a history of hyperbilirubinemia, 15 (2.1%) history of meningitis, 57 (8.3%) had a history of seizure, one (0.1%) had a birth weight less than 1500 grams, 4 cases (0.06%) had history of hypoxia, 18 cases (2.6%) had history of trauma, one (0.1%) had CMV history, and one (0.1%) hearing loss due to syndromicity. On the other hand, it was determined that the probable causes of hearing loss were not related to the severity of hearing loss and age of the patients (p <0.05) Conclusion: Although the prevalence of congenital hearing loss is low, it is important to identify and screen for postnatal congenital hearing loss, especially in people with risk factors known in this study, including patients with kernicterus.

Pars Plana Vitrectomy with Internal Limiting Membrane Peeling for Refractory Diffuse Diabetic Macular Edema

Purpose: To evaluate the effect of pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling for management of refractory diffuse diabetic macular edema (DME). Methods: In this prospective interventional case series, eyes with refractory diffuse DME unresponsive to macular photocoagulation and/or intravitreal bevacizumab, and best corrected visual acuity (BCVA) ≥20/200 and ≤20/60 underwent triamcinoloneassisted PPV with ILM peeling. Pre- and postoperative evaluations included a complete ophthalmologic examination, fluorescein angiography and optical coherence tomography (OCT). Main outcome measures were BCVA and central macular thickness (CMT). Results: Twelve eyes of 12 patients with mean age of 59.6±3.9 (range, 55-68) years were operated and followed for a mean period of 4.9±1.0 (range, 4-6) months. Mean BCVA at final examination was 0.82 ± 0.18 logMAR which was not significantly better than its preoperative value of 1.00 ± 0.80 logMAR (P=0.959). Visual acuity improved by at least 2 lines in 3 eyes (25%), remained stable in 7 eyes (58%) and decreased by at least 2 lines in 2 eyes (17%). Mean CMT at final examination was 315±95 μm, which was significantly less than its preoperative value of 467±107 μm (P=0.004). Complications included vitreous hemorrhage in 2 and cataract progression in 5 eyes. Conclusion: PPV with ILM peeling for refractory diffuse DME seems to reduce macular thickness, but does not significantly improve visual acuity as observed after an intermediate-term follow up of about 6 months

Antimicrobial Activity of Calcium Hydroxide and Betamethasone on Enterococcus faecalis; An in vitro Assessment

Introduction: Calcium hydroxide (CH) is one of the most common intracanal medications. Corticosteroids (CS) are used in endodontics because of their anti-inflammatory activity. This study aimed to evaluate the antimicrobial effect of CH+betamethasone and CH+saline against Enterococcus faecalis (E. faecalis) using agar diffusion test and measuring the microbial zone of inhibition (ZOI). Methods and Materials: Four plates containing Mueller-Hinton broth and E. faecalis culture media, were prepared. In each plate, 5 holes (5×3 mm) were created and a creamy mixture of CH+betamethasone was inserted into the holes (10 holes for each material). Two holes with ampicillin disks and two empty holes were used as negative and positive controls, respectively. Plates were incubated for 24 h and then the diameter of microbial ZOI was measured. The pH of each mixture was measured by pH meter. Data were analyzed using the Mann-Whitney U test. Results: The mean diameter of ZOI for CH+betamethasone and CH+saline was 3.4 and 3 mm, respectively. The difference was not significant (P=0.143). The pH was 12.5 for CH+saline and 12.3 CH+betamethasone, respectively. Conclusion: The mixture of CH+betamethasone had good antimicrobial effects against E. faecalis. Further studies are needed to confirm the value of this mixture in clinical settings.Keywords: Antimicrobial Activity; Betamethasone; Calcium Hydroxide; Enterococcus faecalis; Intracanal Medicatio

Diversity and relationship between Iranian ethnic groups: Human dopamine transporter gene (DAT1) VNTR genotyping

The 40-bp VNTR polymorphism in the 3′ untranslated region of the human DAT1 (dopamine transporter 1) was analyzed in the Iranian ethnic groups in order to examine the influence of geographical and linguistic affiliation on the genetic affinities among the Iranian population. A total of 449 subjects belonging to nine ethnic groups from the Iranian population were included in the study. The screening of 898 chromosomes showed five alleles (6, 7, 8, 9, 10, and 11), of which allele 10 revealed the highest frequency in most regions. Allele 8 was predominant in one ethnicity and occurred more frequently in the center of Iran. This study shows that the DAT1 distribution in Iran has a different pattern from those in other studies, which can contribute to an understanding of differentiation and diversity of Iranian ethnic groups. This polymorphism could represent the genetic diversity among the various ethnic groups of Iran. © 2007 Wiley-Liss, Inc

Childhood Pars Planitis; Clinical Features and Outcomes

Purpose: To evaluate the demographic and clinical features of childhood pars planitis, and to determine the therapeutic and visual outcomes of the disease. Methods: Medical records of pediatric patients (less than 16 years of age at diagnosis) with pars planitis and at least 6 months of follow-up who were referred to Labbafinejad Medical Center, Tehran, Iran over a 22 year period were reviewed. Results: Overall, 117 eyes of 61 patients including 51 (83.6%) male subjects were included. Mean age at the time of diagnosis was 7.8΁3.2 (range, 3-16) years. Mean best corrected visual acuity (BCVA) was 0.88΁0.76 logMAR at presentation which improved to 0.39΁0.51 logMAR at final visit (P<0.001). Endotheliitis was present in 23 (19.6%) eyes and was significantly more prevalent in subjects younger than 9 years (P=0.025). Cataract formation (41.9%) and cystoid macular edema (19.7%) were the most prevalent complications. Univariate regression analysis showed that better baseline visual acuity (OR=0.38, 95%CI 0.21-0.70, P=0.002), age older than 5 years at disease onset (OR=0.36, 95%CI 0.14-0.9, P=0.029), absence of endotheliitis (OR=0.39, 95%CI 0.15-0.99, P=0.047) and female gender (OR=3.77, 95%CI 1.03-13.93, P=0.046) were significantly associated with final BCVA of 20/40 or better. Conclusion: Childhood pars planitis was much more common among male subjects. Endotheliitis may be a sign of inflammation spillover and is more prevalent in younger patients. Visual prognosis is favorable in most patients with appropriate treatment

Outcomes of Retinal Detachment Surgery in Eyes with Chorioretinal Coloboma

Purpose: To report the anatomical and functional outcomes of surgery for retinal detachment associated with chorioretinal colobomas. Methods: In this retrospective interventional case series, 28 eyes of 28 patients (including 18 male subjects) who had undergone surgery for retinal detachment associated with chorioretinal colobomas were evaluated regarding the type of intervention, final visual acuity and anatomical outcomes, as well as complications. Cases with less than 3 months of follow-up were excluded. Results: Primary surgery included vitrectomy in 25 (89.3%) and scleral buckling in 3 (10.7%) eyes. The internal tamponade used in eyes undergoing vitrectomy was silicone oil in 23 (92%) eyes and 20% sulfur hexafluoride (SF6) in 2 (8%) eyes. Silicone oil was removed in 11 eyes (45.8%). The mean number of operations per eye was 1.57±0.74, mean follow-up was 40±36 months, and the retina remained attached in 26 eyes (92.9%) at final follow-up. Mean preoperative visual acuity was 2.33±0.55 (range, 1.15-2.9) logMAR which significantly improved to 1.72±0.9 (range, 0.09-3.1) logMAR postoperatively (P < 0.001), however, final median visual acuity was counting fingers at 2 m. The most common complications were cataracts (100%) and ocular hypertension (46.4%). Conclusion: The most prevalent surgical procedure for treatment of retinal detachment associated with chorioretinal coloboma was pars plana vitrectomy and the most frequently used tamponade was silicone oil. Although anatomical success was satisfactory, functional outcomes were not encouraging which reflects the complexity of the condition and associated abnormalities

A Combination of Prebiotic Inulin and Oligofructose Improve Some of Cardiovascular Disease Risk Factors in Women with Type 2 Diabetes: A Randomized Controlled Clinical Trial

Purpose: This trial was conducted to evaluate the effects of oligofructose-enriched inulin on some of cardiovascular disease risk factors in women with type 2 diabetes. Methods: 52 females (25<BMI<35 kg/m2) with type 2 diabetes were randomly assigned to two groups. Participants received 10g/d oligofructose-enriched inulin (n=27) or 10g/d placebo (n=25) for 8 weeks. Fasting blood samples were taken to measure metabolic profiles, malondialdehyd and antioxidant enzymes at baseline and after the 8 weeks intervention. Paired, unpaired sample t-test and analysis of covariance were used to comparison of quantitative variables. Results: After 8 weeks, in the oligofructose-enriched inulin group there was a significant increase in total antioxidant capacity (0.2 mmol/l, 20.0%) and a significant decrease in fasting plasma glucose (19.2 mg/dL, 9.4%) HbA1c (0.5%, 8.4%), total cholesterol (TC) (28.0 mg/dL, 14.1%), low-density lipoprotein cholesterol (LDL-c) (22.0 mg/dL, 21.7%), TC/HDL-c ratio (0.73, 20.7%), LDL-c/HDL-c ratio (0.55, 27.5%) and malondialdehyd (1.7 nmol/ml, 39.7%) compared to the placebo group. Changes in concentrations of triglycerides, high-density lipoprotein cholesterol (HDLc), superoxide dismutase, catalase and glutathione peroxidase were not significant in oligofructose-enriched inulin group compared to the placebo group. Conclusion: Oligofructose-enriched inulin may improve glycemic indices, lipid profile, antioxidant status and malondialdehyd in women with type 2 diabetes