Design and evaluation of an MRI-compatible linear motion stage.

PURPOSE: To develop and evaluate a tool for accurate, reproducible, and programmable motion control of imaging phantoms for use in motion sensitive magnetic resonance imaging (MRI) appli cations. METHODS: In this paper, the authors introduce a compact linear motion stage that is made of nonmagnetic material and is actuated with an ultrasonic motor. The stage can be positioned at arbitrary positions and orientations inside the scanner bore to move, push, or pull arbitrary phantoms. Using optical trackers, measuring microscopes, and navigators, the accuracy of the stage in motion control was evaluated. Also, the effect of the stage on image signal-to-noise ratio (SNR), artifacts, and B0 field homogeneity was evaluated. RESULTS: The error of the stage in reaching fixed positions was 0.025 ± 0.021 mm. In execution of dynamic motion profiles, the worst-case normalized root mean squared error was below 7% (for frequencies below 0.33 Hz). Experiments demonstrated that the stage did not introduce artifacts nor did it degrade the image SNR. The effect of the stage on the B0 field was less than 2 ppm. CONCLUSIONS: The results of the experiments indicate that the proposed system is MRI-compatible and can create reliable and reproducible motion that may be used for validation and assessment of motion related MRI applications

Providing a conceptual model of metropolises waste management (Case study: Tehran, Iran)

Urbanization and excessive resources consumption including risk of improper waste management are global health and environmental challenge especially in metropolises. Purpose of this study was to provide a conceptual model of metropolises waste management in Tehran, capital of Iran, as a model. Data collection was done through a 25-items questionnaire to examine the people awareness and attitude as well as analyze current and desired situations of wastes management and recycling in 2013. Four hundred fifty residents of Tehran were selected randomly to participate in the study. . Data were analyzed using descriptive and inferential statistics methods by SPSS software and P < 0.05 was set as the significance level. The SWOT matrix was used to formulate waste management strategies considering all aspects of comprehensive waste management. Results showed that the awareness level of 90.4 of people was good and the attitude of 81.3 of them was supportive towards recycling. Moreover, more media coverage on this issue and using award and encouragement strategies are the most important factors increasing people participation in the waste management. Furthermore based on the quantitative strategic planning matrix, priorities of waste management strategies are sustainable, social, economic, and environmental development. © 2015, Journal of Pure and Applied Microbiology. All rights reserved

Aberrant expression of breast development-related microRNAs, miR-22, miR-132, and miR-212, in breast tumor tissues

Purpose: MicroRNAs (miRNAs) are a major class of small endogenous RNA molecules that posttranscriptionally regulate the expression of most genes in the human genome. miRNAs are often located in chromosomal fragile sites, which are susceptible to amplification or deletion. Chromosomal deletions are frequent events in breast cancer cells. Deletion and loss of heterozygosity at 17p13.3 have been reported in 49 of breast cancers. The aim of the current study was to evaluate potential expression alterations of miR-22, miR-132, and miR-212, which are located on the 17p13.3 locus and are required for mammary gland development. Methods: A matched case-control study was conducted, which included 36 pairs of tumor and matched nontumor surgical specimens from patients diagnosed with breast invasive ductal carcinoma. Formalin-fixed paraffin-embedded samples from archival collections at the pathology department of Shariati Hospital were prepared for RNA extraction using the xylene-ethanol method before total RNA was isolated with TRIzol Reagent. Specific primers were designed for cDNA synthesis and miRNA amplification. The expression of miRNAs was then evaluated by real-time polymerase chain reaction (RTPCR). Results: According to our RT-PCR data, the miR-212/ miR-132 family was downregulated in breast cancer (0.328-fold, p<0.001), and this reduced expression was the most prominent in high-grade tumors. In contrast, miR-22 exhibited a significant upregulation in breast tumor samples (2.183-fold, p=0.040). Conclusion: Consistent with the frequent deletion of the 17p13.3 locus in breast tumor cells, our gene expression data demonstrated a significant downregulation of miR-212 and miR-132 in breast cancer tissues. In contrast, we observed a significant upregulation of miR-22 in breast tumor samples. The latter conflicting result may have been due to the upregulation of miR-22 in stromal/cancer-associated fibroblasts, rather than in the tumor cells. © 2016 Korean Breast Cancer Society. All rights reserved

Effects of Rewash on the Accuracy of Stone Dies Produced by Putty-Wash Technique

Abstract: Background and Aims: An accurate impression of teeth and supporting structure is necessary to restore a lost tooth structure or to replace a tooth with crown and bridge. Although there are various methods for making impression, putty-wash technique is currently preferred since it is simple and does not require a special tray. Silicone elastomeric impression materials have suitable consistency for putty-wash technique and are thus widely used. Considering the existing controversies over the effects of impression technique on the accuracy of restoration, we evaluated the effects of rewash on the accuracy of stone dies produced by a putty-wash technique. Methods: In this laboratory study, a model with two metallic dies was used. One die had a horizontal notch as an undercut. Ten impressions were made with spacer and ten impressions with rewash technique. A profile meter with accuracy of one micron was used to measure the dimensions of the produced stone models. The original and produced models were compared by t-test. Results: The mean height of dies without undercut decreased significantly in both groups (11.69 with spacer, P 0.05) and decreased with rewash technique (10.21; P < 0.001). The mean height of dies above the undercut decreased significantly in both groups (9.99 with spacer P < 0.001 and 10.21 with rewash P < 0.001). Conclusion: The impression technique with spacer was more accurate in all dimensions as compared to rewash technique. Keywords: Impression technique, Dimensional accuracy of impression, Impression materials, Condensation silicone Keywords: Impression technique, Dimensional accuracy of impression, Impression materials, Condensation silicon

Magnetic resonance imaging compatible remote catheter navigation system with 3 degrees of freedom

Purpose: To facilitate MRI-guided catheterization procedures, we present an MRI-compatible remote catheter navigation system that allows remote navigation of steerable catheters with 3 degrees of freedom. Methods: The system consists of a user interface (master), a robot (slave), and an ultrasonic motor control servomechanism. The interventionalist applies conventional motions (axial, radial and plunger manipulations) on an input catheter in the master unit; this user input is measured and used by the servomechanism to control a compact catheter manipulating robot, such that it replicates the interventionalist’s input motion on the patient catheter. The performance of the system was evaluated in terms of MRI compatibility (SNR and artifact), feasibility of remote navigation under real-time MRI guidance, and motion replication accuracy. Results: Real-time MRI experiments demonstrated that catheter was successfully navigated remotely to desired target references in all 3 degrees of freedom. The system had an absolute value error of \u3c 1 mm in axial catheter motion replication over 30 mm of travel and 3 ± 2 for radial catheter motion replication over 180 . The worst case SNR drop was observed to be \u3c 3 %; the robot did not introduce any artifacts in the MR images. Conclusion: An MRI-compatible compact remote catheter navigation system has been developed that allows remote navigation of steerable catheters with 3 degrees of freedom. The proposed system allows for safe and accurate remote catheter navigation, within conventional closed-bore scanners, without degrading MR image quality. ∘ ∘

A comprehensive review of HVS-I mitochondrial DNA variation of 19 Iranian populations

Iran is located along the Central Asian corridor, a natural artery that has served as a cross-continental route since the first anatomically modern human populations migrated out of Africa. We compiled and reanalyzed the HVS-I (hypervariable segment-I) of 3840 mitochondrial DNA (mtDNA) sequences from 19 Iranian populations and from 26 groups from adjacent countries to give a comprehensive review of the maternal genetic variation and investigate the impact of historical events and cultural factors on the maternal genetic structure of modern Iranians. We conclude that Iranians have a high level of genetic diversity. Thirty-six haplogroups were observed in Iran’s populations, and most of them belong to widespread West-Eurasian haplogroups, such as H, HV, J, N, T, and U. In contrast, the predominant haplogroups observed in most of the adjacent countries studied here are H, M, D, R, U, and C haplogroups. Using principal component analysis, clustering, and genetic distance-based calculations, we estimated moderate genetic relationships between Iranian and other Eurasian groups. Further, analyses of molecular variance and comparing geographic and genetic structures indicate that mtDNA HVS-I sequence diversity does not exhibit any sharp geographic structure in the country. Barring a few from some culturally distinct and naturally separated minorities, most Iranian populations have a homogenous maternal genetic structure