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Scaffolds play a key role in bone tissue engineering (BTE) as they provide a mechanically and biologically supportive template to treat bone defects. Yet, the ideal scaffold structures are far from certain, leaving a lot to be discovered in terms of the scaffold structure–performance relationships. In this study, we investigated the influence of pore size and internal structure on osteoblast performance in vitro. Three‐dimensional (3D) scaffolds were printed from polycaprolactone (PCL) reinforced with 30% (wt.) nano‐hydroxyapatite (nHAp), with two different internal structures (lattice and staggered) and four pore sizes (0.280, 0.380, 0.420, and 0.550 mm). Scaffolds were seeded with pre‐osteoblast cells (MC3T3‐E1). Metabolic activity of cells, osteoblast differentiation, and capability of osteoblasts to deposit mineralized matrix were examined in vitro. Staggered scaffolds better supported cellular performance. The pore size of 0.280 mm was more favorable to support cell proliferation while the pore size ≥0.420 mm was more effective to promote osteoblast differentiation and mineralization. Findings revealed that osteoblast activities were affected differently by the pore size. Our study further suggests that the structure with a gradient pore size would be better than a single size in terms of supporting cell proliferation, differentiation, and secretion of a mineralized matrix. [ABSTRACT FROM AUTHOR]

Objective(s): Acrylamide (ACR) is an environmental contaminant and neurotoxin. Telmisartan is an AT1 blocker that has neuroprotective properties basically through its anti-oxidant effect. The effect of telmisartan on ACR-induced neurotoxicity was investigated in this study. Materials and Methods: Male Wistar rats were randomly assigned to eight groups (n=6): 1:Control (normal saline), 2:ACR (50 mg/kg, 11 days, IP), 3:ACR+vitamin E (200 mg/kg, every other day, 11 days), 4-6:ACR+telmisartan (0.6, 1.25, and 2.5 mg/kg, 11 days, IP), 7:ACR+telmisartan (0.6 mg/kg, days 3-11), 8:Telmisartan (2.5 mg/kg, 11 days). The behavioral test and blood pressure were assessed after 11 days. Then, the levels of MDA and GSH in brain tissue were measured. The MTT assay was used to evaluate the effect of telmisartan on ACR-induced cytotoxicity. Results: Exposing PC12 cells to ACR decreased cell viability versus the control group. Pretreating PC12 cells with telmisartan (0.0125, 0.025 µM) enhanced cell viability compared with the ACR group. Compared with control samples, ACR significantly caused motor impairment, elevated MDA, and reduced GSH levels. Locomotor abnormalities were significantly ameliorated by telmisartan (0.6, 1.25 mg/kg, 11 days) and vitamin E versus the ACR group. Receiving telmisartan (0.6, 1.25, and 2.5 mg/kg) and vitamin E along with ACR decreased MDA levels and enhanced GSH content compared with the ACR group. There was no significant difference in animal blood pressure between the groups. Conclusion: Oxidative stress has a chief role in the neurotoxicity of ACR. Telmisartan (in doses that do not affect blood pressure) ameliorated ACR-induced toxicity by inhibiting oxidative stress. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the rhetorical structure of written personal narratives in English and Persian. Three types of discourse communities (native Persian speakers, native English speakers, and Iranian EFL learners) were asked to write their personal narratives. The collected narratives were analyzed to elicit their rhetorical structures and especially their moves and steps. The Biber, Upton and Connor (2007) model was used as the theoretical framework for the analysis. The findings showed that the written narratives across the three groups included the same rhetorical moves which comprised (1) introducing the story, (2) sequencing the order of events, (3) resolution, and (4) ending the story. The apparent differences in rhetorical steps were the outcome of social, cultural, and religious factors. It was concluded that EFL learners need explicit instruction to master native English rhetorical moves and steps. [ABSTRACT FROM AUTHOR]

Materials and scaffolds with antimicrobial properties are of great importance in wound dressing and other tissue engineering applications. The objective of the present work was to fabricate scaffolds made from nanocomposites of polycaprolactone (PCL) and quaternary ammonium salt-modified montmorillonite (MMT) by the electrospinning technique, and then characterize their antimicrobial and other properties for wound dressing applications. The effect of MMT on the structure, morphology, and thermal behavior of the electrospun wound dressings was assessed by means of X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM); the swelling capacity, antibacterial activity, and cytotoxicity were also evaluated. The results of XRD and SEM analyses showed MMT was successfully incorporated into the PCL polymeric matrix and its inclusion reduced the size and thickness of the electrospun fibers compared to pure PCL fibers. The TGA results illustrated an increase in the thermal stability of nanocomposites upon incorporation of nanoclay into the PCL matrix. The swelling capacity of the wound dressings was reduced by increasing the amount of MMT in the PCL matrix due to the increased hydrophobicity of the original MMT resulting from its modification with quaternary ammonium salt. The in vitro curcumin (Cur) release profile revealed an initial burst release followed by a sustained release, with the burst release level reduced by the introduction of MMT into the polymeric matrix. Increasing the nanoclay content further reduced the curcumin release, with the PCL/20% MMT/Cur dressings having the lowest curcumin release of all those tested. The beneficial effect of MMT on the antibacterial behavior of electrospun wound dressings based on PCL/MMT nanocomposites was confirmed, with the introduction of both MMT and curcumin into the PCL matrix resulting in lower bacterial viability. PCL/10% MMT/Cur demonstrated higher antimicrobial activity and the greatest bacterial colony reduction compared to both pure PCL and PCL/10% MMT. The cytotoxicity evaluation indicated low toxicity and confirmed the potential of PCL/MMT nanocomposite scaffolds for wound dressing applications. [ABSTRACT FROM AUTHOR]