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Background: Polytetrafluoroethylene (PTFE) is poorly biocompatible due to its low surface energy and hydrophobicity, which cause weak cell attachment and proliferation and complicate its use in implants., Objective: NH3 plasma was used for surface modification and binding of amine groups on the PTFE surface. Collagen was immobilized on the plasma-treated PTFE in order to enable it to support enhanced cell adhesion and growth., Methods: PTFE was exposed to NH3 plasma and collagen was immobilized on the NH3 plasma-treated surface. ATR-IR, SEM, EDXA and contact angle were conducted to determine the composition, microstructure and wettability of samples. The cytocompatibility of the samples was assessed via the growth HUVEC cells using MTT assay., Results: Plasma treatment resulted in an incorporation of functional groups, containing N2 and O2 that caused the PTFE surface to become hydrophilic with contact angle 68°. Also, a reduction in F/C ratio was observed after collagen immobilization that indicates the presence of collagen. Cells proliferated in greater numbers on the collagen immobilized-PTFE as compared to the plasma-treated one., Conclusions: Plasma treatment incorporates functional polar moieties on the PTFE surface, causing enhanced wettability, collagen immobilization and cell viability. Collagen-immobilized PTFE may offer a valuable solution in biomedical applications such as vessel grafts.

Background/purpose: Keratoconus is the most common primary corneal ectatic disease and has considerable importance in public health. Corneal collagen crosslinking (CXL) is a procedure to mitigate progression of keratoconus and reduce demand for corneal transplantation. The aim of this study was to evaluate the effect of CXL on corneal topographic and uncorrected distance visual acuity (UDVA) by Oculus Pentacam in the 15-30-year-old population., Methods: In this descriptive-analytic study, we enrolled 38 eyes of 27 patients suffering from progressive keratoconus who were candidates for CXL. UDVA and the anterior and posterior corneal curvatures assessed prior to and 12 months after CXL. Data were analyzed by the paired t test and p < 0.05 was considered significant., Results: One year after the CXL, mean UDVA significantly improved 0.1 ± 0.25 logarithm of the minimal angle of resolution ( p = 0.012). Changes for steep keratometry values, flat keratometry, and mean keratometry on the anterior corneal surface were statistically significant (all p < 0.005). However, the difference observed in maximum keratometry and astigmatism was not significant ( p = 0.421 and p = 0.745, respectively). After 12 months, all four keratometry values on the posterior corneal surface had increased significantly ( p < 0.005), while no significant change observed in astigmatism ( p = 0.303)., Conclusion: Corneal collagen crosslinking has been revealed as an effective and minimally invasive intervention for the treatment of progressive keratoconus that can improve UDVA., Competing Interests: Conflicts of interest: The author declared that they have no competing interests.

Purpose: To assess the anterior segment parameters of keratoconus (KC) eyes at different stages of the disease by a new Scheimpflug camera combined with Placido disk corneal topography (Sirius, CSO, Italy) in a sample of the Iranian population., Methods: A total of 225 eyes of 225 individuals comprising 41 suspect KC, 40 mild KC, 71 moderate KC, 48 severe KC and 25 normal eyes were assessed for the following parameters: corneal thickness at the apex (CTA), thinnest corneal thickness (TCT), anterior chamber depth (ACD), corneal volume (CV), corneal keratometry (K), corneal asphericity (Q), and corneal elevation in the anterior and posterior surface. Also, the Zernike coefficients for the corneal aberrations including total root mean square (RMS), RMS Coma, RMS spherical aberration (SA), RMS Astigmatism, Baiocchi Calossi Versaci front index (BCVf), and BCV back index (BCVb) were noted for all eyes. Data was analyzed using analysis of variance (ANOVA) and post hoc Bonferroni test for comparison of the means of the five groups. P-value was considered significant if it was <0.05., Results: The TCT, CTA and posterior corneal elevation were significantly different between all comparison groups (P < 0.05). ACD values showed inconsistent differences between groups. Mean value of CV in comparing normal eyes vs suspect KC group, normal eyes vs mild KC, and normal eyes vs moderate KC revealed statistically significant change (P < 0.05). Also, weak non-significant positive correlation was demonstrated between K and CV (r = 0.08). There were statistically significant differences in total RMS, RMS coma, BCVf, and BCVb for most groups (P < 0.05)., Conclusion: Posterior corneal elevation, corneal thickness and high order aberrations are important indices that need to be considered to diagnose different grades of keratoconus.

Pyrazinamide (PZA) is one the first line anti-tuberculosis drugs that require activation by the pyrazinamidase (PZase). Most PZA-resistant Mycobacterium tuberculosis strains have mutations in the pncA gene which encoding PZase that result in the reduction or loss of the enzyme activity. Herein, we have examined how various mutations, which have been found from the PZA-resistant M. tuberculosis strains in Iran, modify the PZase activity. To elucidate the possible role of these mutations, namely A143T (MUT1), L151S (MUT2), A143T/T168A/E173K (MUT3), in the bioactivity of the enzyme, the PZase and mutant genes were cloned, functionally expressed and biochemically and computationally characterized. In comparison to the PZase enzyme, the enzymatic efficiency of mutant enzymes was decreased, with MUT2 indicating the largest enzymatic efficiency reduction. Homology models of mutants were constructed based on the PZase X-ray crystal structure. Molecular modeling and substrate docking revealed that the wild-type has much stronger binding affinity to PZA than the mutants whereas MUT2 has the weakest binding affinity. In addition, the molecular dynamics simulations and the essential dynamics results illustrated that the positions of the 51st to 71st residues were more dynamics in MUT2 as compared to the other atoms in PZase, MUT1 and MUT3 which could decrease the K(m) and k(cat) values of the enzymes.

Geographic tongue is a benign lesion at the dorsum and margins of the tongue that sometimes causes pain and burning sensation. This lesion is characterized by an erythematous area with white or yellow folded edges. The predisposing factors of this lesion include heredity, allergies, psoriasis, stress, fissured tongue and consumption of some foods. The present study was conducted to investigate the prevalence of geographic tongue and its related factors among the 7-18 year-old students in Kermanshah, Iran. This descriptive cross-sectional study was carried out in three schools in Kermanshah using multi-stage random cluster sampling method. A total number of 3600 students were examined (1800 girls and 1800 boys). Demographic data and the results of examinations were recorded in a questionnaire. The factors affecting the incidence of geographic tongue were analyzed by the SPSS-20 software and the Chi-square test.The prevalence of geographic tongue was 7.86% (283 individuals). The incidence of this lesion was significantly higher in males than in females (p<0.01). There was no relationship between geographic tongue and psoriasis or fissured tongue.  Pain and discomfort during eating was more prevalent in those with geographic tounge compared to those without this condition (p<0.02). The prevalence of geographic tongue among the studied population was 7.86%, and the prevalence of geographic tongue in male students was higher than in female students.