In this study, we investigate how Wilks’ lambda, Pillai’s trace, Hotelling’s trace, and Roy’s largest root test statistics can be affected when the normal and homogeneous variance assumptions of the MANOVA method are violated. In other words, in these cases, the robustness of the tests is examined. For this purpose, a simulation study is conducted in different scenarios. In different variable numbers and different sample sizes, considering the group variances are homogeneous σ12=σ22=⋯=σg2 and heterogeneous (increasing) σ12<σ22<⋯<σg2, random numbers are generated from Gamma(4-4-4; 0.5), Gamma(4-9-36; 0.5), Student’s t(2), and Normal(0; 1) distributions. Furthermore, the number of observations in the groups being balanced and unbalanced is also taken into account. After 10000 repetitions, type-I error values are calculated for each test for α = 0.05. In the Gamma distribution, Pillai’s trace test statistic gives more robust results in the case of homogeneous and heterogeneous variances for 2 variables, and in the case of 3 variables, Roy’s largest root test statistic gives more robust results in balanced samples and Pillai’s trace test statistic in unbalanced samples. In Student’s t distribution, Pillai’s trace test statistic gives more robust results in the case of homogeneous variance and Wilks’ lambda test statistic in the case of heterogeneous variance. In the normal distribution, in the case of homogeneous variance for 2 variables, Roy’s largest root test statistic gives relatively more robust results and Wilks’ lambda test statistic for 3 variables. Also in the case of heterogeneous variance for 2 and 3 variables, Roy’s largest root test statistic gives robust results in the normal distribution. The test statistics used with MANOVA are affected by the violation of homogeneity of covariance matrices and normality assumptions particularly from unbalanced number of observations.

Colistin is active against most multidrug-resistant, aerobic Gram-negative bacteria. Because of the reported nephrotoxicity during the first years of use of colistin, there were concerns of its use in pediatrics where there was limited experience The aim of this study is to document the clinical characteristics and outcomes of use of colistin in pediatric patients at a pediatric intensive care unit in Turkey. We reviewed the medical and laboratory records of 29 critically ill children who were treated with colistin for 38 courses between January 2011 and December 2011 at the Department of Pediatric Intensive Care Unit in Ankara University Medical School, Turkey. The median age was 17 months (range 3-217 months). Male-to-female ratio was 1:1.37. Ventilator-associated pneumonia (21 courses) was the leading diagnosis followed by catheter-related blood stream infection (6 courses), bacteremia (4 courses), ventriculoperitoneal shunt infection, peritonitis and pneumonia (1 course). The most commonly isolated microorganisms were Acinetobacter baumanni, Pseudomonas aeruginosa, Klebsiella pneumoniae, Serratia marcescens, Stenotrophomonas maltophilia, and Enterobacter cloacae. Two colistin formulations were used. Colimycin (Kocak Farma) was used in 21 colistin treatment episodes. The median dosage of colistin in this group was 5.0 mg/kg/d (2.3-5.6 mg/kg/d). Colomycin (Forest Laboratories) was used in 17 colistin treatment episodes. The median dosage of colistin in the second group was 75,000 International Unit/kg/d (50,000-80,000 International Unit/kg/d). Thirty colistin treatment episodes (79%) had a good or partial clinical response and 8 (21%) had a poor clinical response. Of the 8 colistin treatment episodes with poor clinical response, 3 were in the Colimycin group and 5 were in the Colomycin group. Ten patients died. There was no evidence of neurotoxicity in this study. Nephrotoxicity was observed in 1 patient but was not attributed to colistin because the patient had multiorgan failure at the same time. This study in a small cohort of patients suggests that the use of colistin in severe nosocomial infections caused by multidrug-resistant Gram-negative bacteria is well-tolerated and efficacious.

Objective: : To evaluate the effects of fixed orthodontic treatment with steel-ligated conventional brackets and self-ligating brackets on halitosis and periodontal health. Materials and Methods: : Sixty patients, at the permanent dentition stage aged 12 to 18 years, who had Angle Class I malocclusion with mild-to-moderate crowding were randomly selected. Inclusion criteria were nonsmokers, without systematic disease, and no use of antibiotics and oral mouth rinses during the 2-month period before the study. The patients were subdivided into three groups randomly: the group treated with conventional brackets (group 1, n = 20) ligated with steel ligature wires, the group treated with self-ligating brackets (group 2, n = 20), and the control group (group 3, n = 20). The periodontal records were obtained 1 week before bonding (T1), immediately before bonding (T2), 1 week after bonding (T3), 4 weeks after bonding (T4), and 8 weeks after bonding (T5). Measurements of the control group were repeated within the same periods. The volatile sulfur components determining halitosis were measured with the Halimeter at T2, T3, T4, and T5. A two-way repeated measures of analysis of variance (ANOVA) was used to compare the groups statistically. Results: : No statistically significant group × time interactions were found for plaque index, gingival index, pocket depth, bleeding on probing, and halitosis, which means three independent groups change like each other by time. The risk of tongue coating index (TCI) being 2 was 10.2 times higher at T1 than at T5 ( P < .001). Therefore, the probability of higher TCI was decreased by time in all groups. Conclusions: : The self-ligating brackets do not have an advantage over conventional brackets with respect to periodontal status and halitosis.