Gene selection for microarray data classification via multi-objective graph theoretic-based method.

In recent decades, the improvement of computer technology has increased the growth of high-dimensional microarray data. Thus, data mining methods for DNA microarray data classification usually involve samples consisting of thousands of genes. One of the efficient strategies to solve this problem is gene selection, which improves the accuracy of microarray data classification and also decreases computational complexity. In this paper, a novel social network analysis-based gene selection approach is proposed. The proposed method has two main objectives of the relevance maximization and redundancy minimization of the selected genes. In this method, on each iteration, a maximum community is selected repetitively. Then among the existing genes in this community, the appropriate genes are selected by using the node centrality-based criterion. The reported results indicate that the developed gene selection algorithm while increasing the classification accuracy of microarray data, will also decrease the time complexity.

Integration of multi-objective PSO based feature selection and node centrality for medical datasets.

In the past decades, the rapid growth of computer and database technologies has led to the rapid growth of large-scale medical datasets. On the other, medical applications with high dimensional datasets that require high speed and accuracy are rapidly increasing. One of the dimensionality reduction approaches is feature selection that can increase the accuracy of the disease diagnosis and reduce its computational complexity. In this paper, a novel PSO-based multi objective feature selection method is proposed. The proposed method consists of three main phases. In the first phase, the original features are showed as a graph representation model. In the next phase, feature centralities for all nodes in the graph are calculated, and finally, in the third phase, an improved PSO-based search process is utilized to final feature selection. The results on five medical datasets indicate that the proposed method improves previous related methods in terms of efficiency and effectiveness.

Effect of hydroxyapatite nanoparticles on enamel remineralization and estimation of fissure sealant bond strength to remineralized tooth surfaces: an in vitro study.

BACKGROUND: The management of noncavitated caries lesions before sealant therapy is a clinical challenge when the tooth needs sealant application. Sealing noncavitated carious lesions in pits and fissures may lead to failure of the fissure sealant (FS) due to incomplete sealing. Therefore the use of remineralizing agents such as nanoparticles has been suggested. This study investigated the ability of hydroxyapatite nanoparticles (nano-HA) to remineralize enamel, and their effect on sealant microleakage and shear bond strength (SBS). METHODS: A total of 192 third molars were demineralized and pretreated with two concentrations of nano-HA with and without sodium hexametaphosphate (SHMP), followed by phosphoric acid etching and resin FS application. The study groups were 1) etching + FS, 2) etching + nano-HA 0.15% + FS, 3) etching + nano-HA 0.03% + FS, 4) etching + mixture of nano-HA 0.15% and SHMP 0.05% + FS, 5) etching + mixture of nano-HA 0.03% + SHMP 0.01% + FS. The laboratory tests included microleakage in 50 teeth, scanning electron microscopy (SEM) evaluation in 10 samples, and SBS in 100 samples. Enamel remineralization changes were evaluated in 32 teeth with energy-dispersive X-ray spectroscopy (EDS) and field emission scanning electron microscope (FESEM). RESULTS: Nano-HA enhanced the SBS to remineralized enamel in a large percentage of nanoparticles. Mean SBS in group 2 was significantly greater than in groups 1, 3 and 4 (all P < 0.05). SBS was related to nano-HA concentration: nano-HA 0.15% yielded greater SBS (16.8 ± 2.7) than the 0.03% concentration (14.2 ± 2.1). However, its effect on microleakage was not significant. Nano-HA with or without SHMP led to enhanced enamel remineralization; however, the Calcium (Ca)/Phosphate (P) weight percent values did not differ significantly between the groups (P > 0.05). SEM images showed that SHMP did not affect sealant penetration into the deeper parts of fissures. FESEM images showed that adding SHMP led to increased nanoparticle dispersal on the tooth surface and less cluster formation. CONCLUSIONS: The ultraconservative approach (combining nano-HA 0.15% and SHMP) and FS may be considered a minimal intervention in dentistry to seal demineralized enamel pits and fissures.

Shear bond strength and scanning electron microscopy characteristics of universal adhesive in primary tooth dentin: An in vitro study.

BACKGROUND: The aim of the study was to evaluate the adhesion of Scotchbond Universal Adhesive to primary tooth dentin by measuring shear bond strength (SBS) and observing morphological changes with scanning electron microscopy (SEM). MATERIALS AND METHODS: In this in vitro study, a total of 60 primary canine teeth were randomly divided into 5 groups (n = 12). The study groups were (1) Phosphoric acid etching + Adper Single Bond 2 (control), (2) phosphoric acid etching + Scotchbond Universal (etch-and-rinse), (3) Scotchbond Universal (self-etch), (4) phosphoric acid etching + Scotchbond Universal + resin, and (5) Scotchbond Universal + resin. Composite cylinders were built on the tooth surface, and 10 samples in each group were selected for SBS testing and identification of the failure modes. Two samples from each group were observed by SEM. One-way ANOVA and Tukey honestly significant difference post hoc test were used for data analysis P value < 0.05 was considered statistically significant. RESULTS: The results showed that SBS in Group 1 was significantly lower than in Groups 2, 3, and 4 (all P < 0.001). There was no significant difference between Groups 2 and 3 (P = 0.98), or between Groups 3 and 4 (P = 0.97). There was no significant difference between Groups 2 and 4 (P = 0.999) or between Groups 1 and 5 (P = 0.156). Mixed and cohesive failures were more frequent in Groups 2, 3 and 4. SEM observations showed that applying phosphoric acid to the dentin before Scotchbond Universal adhesive resulted in more open dentinal tubules and more resin tag impregnation. CONCLUSION: There was no significant difference in SBS between Scotchbond Universal Adhesive in etch-and-rinse and self-etching modes. The SBS of Scotchbond Universal Adhesive in etch-and-rinse mode was greater than Adper Single Bond 2.

Respiratory problems among cotton textile workers.

BACKGROUND: Long term occupational exposure to cotton dust is associated with respiratory symptoms and loss of pulmonary function. AIM: This study was conducted to explore respiratory symptoms, pulmonary function tests and chest radiography of workers, and to evaluate the findings of high resolution computed tomographyand its correlation with pulmonary function tests (PFT). MATERIAL AND METHODS: The study was conducted on 100 cotton workers as exposed group and 100 unexposed subjects. Smokers were excluded from the study. All workers were interviewed and examined by the pulmonologist. PFT and chest radiography were conducted for all subjects. HRCT was performed for those with abnormal PFT or chest radiography. RESULTS: A total of 51% and 31% of the cotton textile workers had one or more respiratory symptoms and respiratory signs respectively. 28% of subjects in the exposed group and 5% of subjects in unexposed group had obstructive pattern. Bronchia wall thickening and air trapping were the most frequent chest radiography and HRCT abnormalities respectively. There was a significant correlation between HRCT and the results of PFT. CONCLUSION: We conclude that long term exposure to cotton dust is associated with obstructive disease that increase with duration of exposure (history of working years), also use of HRCT as a sensitive tool in the assessment of pathologic changes and it's correlation with PFT, confirms the expected pathophysiology of airway obstruction in cotton workers.