Ivan Nikolic

Improving Education in Medical Statistics: Implementing a Blended Learning Model in the Existing Curriculum

Background Although recent studies report on the benefits of blended learning in improving medical student education, there is still no empirical evidence on the relative effectiveness of blended over traditional learning approaches in medical statistics. We implemented blended along with on-site (i.e. face-to-face) learning to further assess the potential value of web-based learning in medical statistics. Methods This was a prospective study conducted with third year medical undergraduate students attending the Faculty of Medicine, University of Belgrade, who passed (440 of 545) the final exam of the obligatory introductory statistics course during 2013–14. Student statistics achievements were stratified based on the two methods of education delivery: blended learning and on-site learning. Blended learning included a combination of face-to-face and distance learning methodologies integrated into a single course. Results Mean exam scores for the blended learning student group were higher than for the on-site student group for both final statistics score (89.36±6.60 vs. 86.06±8.48; p = 0.001) and knowledge test score (7.88±1.30 vs. 7.51±1.36; p = 0.023) with a medium effect size. There were no differences in sex or study duration between the groups. Current grade point average (GPA) was higher in the blended group. In a multivariable regression model, current GPA and knowledge test scores were associated with the final statistics score after adjusting for study duration and learning modality (p<0.001). Conclusion This study provides empirical evidence to support educator decisions to implement different learning environments for teaching medical statistics to undergraduate medical students. Blended and on-site training formats led to similar knowledge acquisition; however, students with higher GPA preferred the technology assisted learning format. Implementation of blended learning approaches can be considered an attractive, cost-effective, and efficient alternative to traditional classroom training in medical statistics.

Neural network control approach for a two-tank system

This paper describes two different approaches in a two tank-system control using neural networks - the NARMA-L2 Control and the Model Reference Control. Knowing that the process control has had the most satisfying results using a standard PID controller, this paper compares the two approachespsila results one to another but also every one of them with the PID controllerpsilas results. The goal was to increase the system response speed without heavily increasing the two other relevant parameters - the overshoot and the steady state error. All of the experiments, measurements and simulations were conducted in Matlab/RT Simulink.

Meta-analysis of the changes in correlations between depression instruments used in longitudinal studies.

BACKGROUNDnCorrelations between instruments measuring the same construct reflect their concurrent validity. Little is known about changes in correlations between such instruments employed in studies with repeated assessment. The aim of this meta-analysis was to examine the changes in correlations between depression instruments in the course of longitudinal studies.nnnMETHODSnA literature search was conducted using MEDLINE and PsycINFO for the period from 1960 to 2013. The total number of collected articles was 3723, of which 61 were included. Three meta-analyses were performed for the changes in correlations between each pair of the three depression scales: Hamilton Rating Scale for Depression (HAMD), Montgomery-Asberg Depression Rating Scale (MADRS) and Beck Depression Inventory (BDI). The effect size in these meta-analyses was obtained by the z-transformation of correlation coefficients.nnnRESULTSnCorrelations between depression scales increased over time in 52 studies. Significant changes in correlation coefficients were found for correlations between HAMD and BDI (p<0.001) and for correlations between HAMD and MADRS (p<0.001). An increase in correlations between the scales was associated with a decrease in depression scores and increase in their variability.nnnLIMITATIONSnUnivariable and multivariable meta-regression models were not obtained in all three meta-analyses because of the lack of data.nnnCONCLUSIONSnA finding that correlations between depression instruments tended to increase over time has significant implications for assessment of the concurrent validity of these instruments. In longitudinal designs it is important to estimate correlations between depression scales over time because different thresholds for scale correlations indicate acceptable concurrent validity at different times.

First Report of Pseudomonas syringae pv. aptata Causing Bacterial Leaf Spot on Sugar Beet in Serbia

A severe bacterial leaf spot was observed during June and July 2013 on commercial cultivars of sugar beet (Beta vulgaris var. saccharifera) in the Vojvodina Province of Serbia. Serbia is a major sugar beet production area in southeastern Europe, with 62,895 ha and 3 million tons of sugar beet yield in 2013. A foliar leaf spot observed in 25 commercial sugar beet fields surveyed ranged from 0.1 to 40% severity. Symptoms were characterized as circular or irregular, 5- to 20-mm diameter, white to light brown necrotic spots, each with a dark margin. Diseased leaves were rinsed in sterilized, distilled water (SDW) and dried at room temperature, and leaf sections taken from the margin of necrotic tissue were macerated in SDW. Isolations from 48 symptomatic leaves onto nutrient agar with 5% (w/v) sucrose (NAS) produced bacterial colonies that were whitish, circular, dome-shaped, and Levan-positive. Representative isolates (n = 105) were Gram negative; aerobic; positive for catalase, fluorescence on Kings medium B, and tobacco hypersensitivity; and negative for oxidase, potato rot, and arginine dehydrolase. These reactions corresponded to LOPAT group Ia, which includes Pseudomonas syringae pathovars (2). Repetitive extragenic palindromic sequence (rep)-PCR was used for genetic fingerprinting the isolates using the REP, ERIC, and BOX primers. Twenty-five different profiles were obtained among the strains. From each profile group, one representative strain was sequenced for the gyrB gene (1). Four heterogenic groups were observed, and representative gyrB gene sequences of each group were deposited in the NCBI GenBank (Accession Nos. KJ950024 to KJ950027). The sequences were compared with those of pathotype strain P. syringae pv. aptata CFBP 1617 deposited in the PAMDB database; one strain was 100% homologous, and the other three were 99% homologous. To fulfill identification of the Serbian sugar beet isolates, gltA and rpoD partial gene sequences were determined (1), and the sequences were deposited as Accession Nos. KM386838 to KM386841 for gltA and KM386830 to KM38683033 for rpoD. The sequences were 100% homologous with those of pathotype strain CFBP 1617. Pathogenicity of each of four representative bacterial strains was tested on 3-week-old plants of the sugar beet cultivars Marinela, Serenada, and Jasmina (KWS, Belgrade, Serbia) and Lara (NS Seme, Novi Sad, Serbia) by atomizing a bacterial suspension of ~106 CFU/ml of the appropriate isolate onto the abaxial leaf surface of three plants per cultivar until water-soaking of the leaf surface was observed. Three plants of each cultivar atomized similarly with P. syringae pv. aptata CFBP 2473 and SDW served as positive and negative control treatments, respectively. Inoculated plants were kept in a clear plastic box at 80 to 100% RH and 17 ± 1°C and examined for symptom development over 3 weeks. For all test isolates and the control strain, inoculated leaves first developed water-soaked lesions 7 days after inoculation (DAI). By 10 to 14 DAI, lesions were necrotic and infection had spread to the petioles. By 21 DAI, wilting was observed on more than 50% of inoculated plants. Negative control plants were symptomless. Bacteria re-isolated onto NAS from inoculated leaves had the same colony morphology, LOPAT results, and gyrB partial gene sequences as described for the test strains. No bacteria were re-isolated from negative control plants. Based on these tests, the pathogen causing leaf spot on sugar beet in Serbia was identified as P. syringae pv. aptata. References: (1) P. Ferrente and M. Scortichini. Plant Pathol. 59:954, 2010. (2) R. A. Lelliott et al. J. Appl. Bacteriol. 29:470, 1966.

Genetic diversity and pathogenicity of Pseudomonas syringae pv. aptata isolated from sugar beet

Pseudomonas syringae pv. aptata is the causal agent of bacterial leaf spot disease of sugar beet (Beta vulgaris). During 2013, 250 samples were collected from leaf lesions with typical symptoms of bacterial leaf spot in commercial fields of sugar beet in Serbia, and 104 isolates of P.xa0syringae pv. aptata were obtained. Identification and characterization was performed using biochemical, molecular and pathogenicity tests. Identification included LOPAT tests and positive reactions using primers Papt2F and Papt1R specific for P.xa0syringae pv. aptata. Repetitive (rep) sequence‐based PCR typing with ERIC, REP and BOX primers revealed high genetic variability among isolates and distinguished 25 groups of different fingerprinting profiles. Pulse‐field gel electrophoresis (PFGE) and multilocus sequence analysis (MLSA) of representative isolates showed higher genetic variability than in rep‐PCR analysis and distinguished three and four major genetic clusters, respectively. A pathogenicity test performed with 25 representative isolates on four cultivars of sugar beet confirmed the occurrence of leaf spot disease and showed correlation between the most aggressive isolates and the genetic clusters obtained in MLSA. All these findings point to the existence of several lines of P.xa0syringae pv. aptata infection in Serbia that are genetically and pathologically different.

The association of arachnoid cysts and focal epilepsy: Hospital based case control study

OBJECTIVEnArachnoid cysts (ACs) are common findings in brain MRI. Our aim was to examine frequency and distribution of ACs in patients with focal epilepsy, compared to healthy control subjects, and to investigate the association of AC and electro-clinical features of focal epilepsy.nnnPATIENTS AND METHODSnWe performed a retrospective case-control study, using data from 180 patients that underwent video-EEG monitoring between 2009 and 2012, and of 114 healthy controlled subjects. Analysis of electro-clinical data and structural MRI images was conducted.nnnRESULTSnA significantly higher proportion of ACs in the focal epilepsy group (19/180; 10.5%) compared to healthy control subjects (3/114; 2.6%) (p=0.012) was identified. Significant congruence of semiological features or interictal and ictal EEG with AC localization was identified in only one MRI nonlesional patient with temporal cyst localization.nnnCONCLUSIONnACs are seen more often in patients with focal epilepsy. Explicit association between focal epilepsy and AC is possible but exceptional. More likely, focal epilepsy and AC share a common etiological ancestor but represent distant and distinct entities.

Biological control of Pseudomonas syringae pv. aptata on sugar beet with Bacillus pumilus SS-10.7 and Bacillus amyloliquefaciens (SS-12.6 and SS-38.4) strains

Assessment of biological control of Pseudomonas syringae pv. aptata using crude lipopeptide extracts (CLEs) of two Bacillus amyloliquefaciens strains (SS‐12.6 and SS‐38.4) and one Bacillus pumilus strain (SS‐10.7).

Leaf spot disease on Philodendron scandens, Ficus carica and Actinidia deliciosa caused by Pseudomonas syringae pv. syringae in Serbia

During the spring of 2014 and 2015, a leaf spot disease was observed on heart-leaf philodendron (Philodendron scandens Koch & Sello) plants grown in a several house gardens near city of Jagodina, Moravički region of Serbia. Diseased leaves were covered with watersoaked leaf spots with surrounded by yellow halos. Based on biochemical and molecular tests Pseudomonas syringae pv. syringae was identified as causing agent of bacterial leaf spot of heart-leaf philodendron and is in humid season accountable for appearence of disease. The genetic diversity within this pathogen isolated from different hosts in central Serbia, was studied to obtain insights into disease etiology. Therefore, kiwi fruit and fig tree leaves, with disease symptoms that were similar to those observed on heart-leaf philodendron plants, were collected and bacteria were isolated on NAS medium. Isolates were identified as P. syringae pv. syringae by detection of syrB gene, biochemical, pathogenicity tests and sequencing of gyrB gene. In cross inoculation tests on potted host plants, each strain induced leaf spot symptoms on heart-leaf philodendron and fig tree leaves, apart of the host of origin, and no significant symptoms in kiwi fruit leaves. Genomic profiles generated with rep-PCR analysis revealed that all strains originated from diseased heart-leaf philodendron, kiwi fruit and fig tree leaves had similiar DNA fingerprints. Overall, the data demonstrate P. syringae pv. syringae as a causing agent of leaf spot disease of heart-leaf philodendron and fig tree in Moravički region of Serbia. This research is the first study that identified P. syringae pv. syringae associated with leaf spot disease on P. scandens, and also a starting point for investigation of the epidemiology of leaf spot disease on fruit trees that could be infected by the same bacterial strains.