RESUMEN

DNA sequencing is an essential process for determining the nucleotides on a DNA strands and this process is of high importance in medicine and biomedical research. Nanopore based DNA sequencing has been widely researched and analyzed during last years and this is very important to improve all parameters involved in the process of DNA translocating through these nanopours. Ionic current resolution is a key parameter in designing these nanopours for better measuring of this infinitesimal current that is in order of nano A or even pico A. Here by means of molecular dynamics simulation we showed that using fluorinated carbon nanotubes while embedded inside silicon membrane results a higher ionic current compared to pristine carbon nanotubes. We simulated pristine carbon nanotubes (PCNT) and fluorinated carbon nanotubes (FCNT) with chirality of (8,8) and (10,10) which corresponds to diameter of 1.07 nm and 1.34 nm respectively. Ionic current analysis of these inorganic nanopours functionalized with carbon nanomaterials showed that it could double or triple the magnitude of ionic current. For FCNT (8,8) the magnitude of ionic current was 1.984 nA while it was 0.891 nA for PCNT (8,8) embedded in silicon nanopore. Our study introduces the fluorination of carbon nanotubes as potential method for designing high resolution DNA sequencing nanopore devices.

Asunto(s)

Técnicas Biosensibles , Nanoporos , Nanotubos de Carbono , ADN , Simulación de Dinámica Molecular

RESUMEN

Although effects of biochemical modulation of stem cells have been widely investigated, only recent advances have been made in the identification of mechanical conditioning on cell signaling pathways. Experimental investigations quantifying the micromechanical environment of mesenchymal stem cells (MSCs) are challenging while computational approaches can predict their behavior due to in vitro stimulations. This study introduces a 3D cell-specific finite element model simulating large deformations of MSCs. Here emphasizing cell mechanical modulation which represents the most challenging multiphysics phenomena in sub-cellular level, we focused on an approach attempting to elicit unique responses of a cell under fluid flow. Fluorescent staining of MSCs was performed in order to visualize the MSC morphology and develop a geometrically accurate model of it based on a confocal 3D image. We developed a 3D model of a cell fixed in a microchannel under fluid flow and then solved the numerical model by fluid-structure interactions method. By imposing flow characteristics representative of vigorous in vitro conditions, the model predicts that the employed external flow induces significant localized effective stress in the nucleo-cytoplasmic interface and average cell deformation of about 40%. Moreover, it can be concluded that a lower strain level is made in the cell by the oscillatory flow as compared with steady flow, while same ranges of effective stress are recorded inside the cell in both conditions. The deeper understanding provided by this study is beneficial for better design of single cell in vitro studies.

Asunto(s)

Células Madre Mesenquimatosas/citología , Fenómenos Biomecánicos , Diferenciación Celular , Línea Celular , Humanos , Hidrodinámica , Mecanotransducción Celular , Microscopía Confocal , Modelos Anatómicos , Modelos Biológicos , Imagen Óptica , Estrés Mecánico

RESUMEN

BACKGROUND: Multiple sclerosis (MS), a chronic inflammatory demyelinating disorder with neurodegenerative aspects, is more common among young adults, particularly women. METHODS: This molecular study was designed to investigate the IL-7R α chain gene in Iranian MS patients. We studied 60 MS patients, diagnosed based on 2005 R-McDonald criteria and 60 apparently healthy individuals as the control group. DNA was extracted from whole blood cells using MBST/IRAN Extraction kit and all samples were screened for possible sequence variation in three regions including promoter, exon 2 and exon 4 with single strand conformation polymorphism (SSCP). RESULTS: The alterations were confirmed with direct sequencing by ABI 3730XL. Although no mutation was detected in the studied regions, eight single nucleotide polymorphisms (SNPs) consisting of rs71617734 in promoter; rs35967524, rs11567704, rs1494558, rs11567705 and rs969128 in exon 2 as well as rs1494555 and rs2228141 in exon 4 were observed. The rs1494558 in exon 2 and rs1494555 in exon 4 were missense variations. Our results also showed the substitution of isoleucine with threonine in rs1494558 (P.I66T) with this accession number, FR863587 submitted in EMBL bank. The study of exon4 areas revealed two SNPs and two sequence variations, where [p.V138I] Valine substituted with isoleucine (FR863588), as well as a silent nucleotide substitution [P. H165H] in the absence of amino acid alteration. The analysis of the SNP genotype in the controls and the patients, using χ(2) showed no significant association with multiple sclerosis in this group. CONCLUSION: Our study demonstrated the effects of some SNPs on the IL-7R α protein in MS. Further studies are required to reveal the effects of these SNPs on the IL-7R α protein in multiple sclerosis.