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Microcellular poly(vinyl alcohol) (PVA) foams were prepared by combing the thermoplastic processing technology and solid-state supercritical CO 2 foaming technology. The compound polyol plasticizers that may partially destroy intra- and inter-molecular hydrogen bonding within PVA and improve the flowability during processing were developed to pave the way for PVA thermoplastic processing with lower processing temperature and wider processing window. In order to ease the collapse of bubbles and improve the foaming performances, nano silica was introduced into the system. The influences of processing parameters (foaming temperature and saturation pressure) and nano silica content on the foaming behavior and cell structure were systematically studied. The resultant PVA/SiO 2 nanocomposite foams exhibited a cellular structure with smaller cell size, larger cell density and relative density compared to PVA foam. It was also found that cell density increased with decreasing foaming temperature or increasing saturation pressure. Further investigation suggested that improvement of stiffness as well as the decrease of crystallinity were thought as the main reasons to explain the interesting effect of SiO 2 addition on the foaming behavior of PVA. [ABSTRACT FROM AUTHOR]

Mucoadhesive drug delivery systems stick to mucosal tissues and prolong the local retention time of drugs. Since the colon is covered by a mucosal layer, mucoadhesive rectal formulations may improve treatment of such diseases as hypertension or colon cancer. Ulcerative colitis (UC) is an inflammatory bowel disease characterized by chronic inflammation of the colonic mucosa. It is commonly treated with sulfasalazine (SSZ), which is metabolized by the intestinal flora into the therapeutic 5-aminosalicylic acid (5-ASA) and a toxic by-product sulfapyridine (SP). SSZ can be administered orally or rectally. The latter route avoids unintended absorption of the drug or its degradation products in the upper gastrointestinal tract, but often fails due to limited retention time. Here, we propose a mucoadhesive hydrogel to improve the efficacy of rectal SSZ administration. The gel is made of catechol modified-chitosan (Cat-CS) crosslinked by genipin. After loading the gel with SSZ, we evaluated its efficacy in a mouse model of UC. Compared to oral SSZ treatment, rectal SSZ/Cat-CS delivery was more therapeutic, showed equivalent histological scores, and induced a lower plasma concentration of the potentially toxic SP by-product. These results show SSZ/Cat-CS rectal hydrogels are more effective and safer formulations for UC treatment than oral SSZ. Statement of Significance Ulcerative colitis affects the colon by causing chronic inflammation on the mucosa. One of the most common drugs to treat mild to moderate UC is sulfasalazine, which can be administrated both orally and rectally. Rectal formulations are preferable, since their therapeutic effect happens topically, and they prevent side effects related to absorption of the drug in the small intestine. However, the efficacy of rectal sulfasalazine formulations is decreased by their limited colon residence time. Here we propose a chitosan-catechol mucoadhesive gel that allows delivering sulfasalazine more effectively and safely than oral administration. Our results bring new insights into the field of mussel-inspired catechol hydrogels, showing their potential as drug delivery systems to treat a widespread disease such as ulcerative colitis. [ABSTRACT FROM AUTHOR]

Drug administration via buccal mucosa is an attractive drug delivery strategy due to good patient compliance, prolonged localized drug effect, and avoidance of gastrointestinal drug metabolism and first-pass elimination. Buccal drug delivery systems need to maintain an intimate contact with the mucosa lining in the wet conditions of the oral cavity for long enough to allow drug release and absorption. For decades, mucoadhesive polymers such as chitosan (CS) and its derivatives have been explored to achieve this. In this study, inspired by the excellent wet adhesion of marine mussel adhesive protein, we developed a buccal drug delivery system using a novel catechol-functionalized CS (Cat-CS) hydrogel. We covalently bonded catechol functional groups to the backbone of CS, and crosslinked the polymer with a non-toxic crosslinker genipin (GP). We achieved two degrees of catechol conjugation (9% and 19%), forming Cat9-CS/GP and Cat19-CS/GP hydrogels, respectively. We confirmed covalent bond formation during the catechol functionalization and GP crosslinking during the gel formation. The gelation time and the mechanical properties of Cat-CS hydrogels are similar to those of CS only hydrogels. Catechol groups significantly enhanced mucoadhesion in vitro (7 out of the 10 Cat19-CS hydrogels were still in contact with porcine mucosal membrane after 6 h, whereas all of the CS hydrogels lost contact after 1.5 h). The new hydrogel systems sustained the release of lidocaine for about 3 h. In-vivo, we compared buccal patches made of Cat19-CS/GP and CS/GP adhered to rabbit buccal mucosa. We were able to detect lidocaine in the rabbit's serum at concentration about 1 ng/ml only from the Cat19-CS patch, most likely due to the intimate contact provided by mucoadhesive Cat19-CS/GP systems. No inflammation was observed on the buccal tissue in contact with any of the patches tested. These results show that the proposed catechol-modified CS hydrogel is a promising mucoadhesive and biocompatible hydrogel system for buccal drug delivery. [ABSTRACT FROM AUTHOR]

Fluxapyroxad, a broad-spectrum and high-efficiency succinate dehydrogenase inhibitor (SDHI) fungicide, can control plant pathogens on many crops. However, no data about the fungicidal activity of fluxapyroxad against Stemphylium solani and its resistance risk are available. In this study, the mycelial growth inhibition method was used to determine the sensitivity of 99 S. solani strains to fluxapyroxad. The EC 50 values ranged from 0.0183 to 0.3017 μg/mL, with an average EC 50 value of 0.0839 ± 0.0051 μg/mL. The results indicated that fluxapyroxad exhibited an excellent inhibitory efficacy against S. solani. Six resistant mutants were obtained by laboratory fungicide taming. The resistance ratio of each mutant was greater than 50 and the resistance of the mutants to fluxapyroxad was steadily inheritable through 10 successive culture transfers to fungicide-free PSA plates. We found that fluxapyroxad resistance not only affected mycelial growth in S. solani , but was also temperature dependent. Moreover, fluxapyroxad resistance caused markedly decreased virulence of S. solani on detached tomato leaves, indicating that the resistant mutants suffered a fitness penalty. Cross-resistance analysis showed that no cross-resistance was observed between fluxapyroxad and fludioxonil, iprodione, azoxystrobin or fluazinam, while a positive cross-resistance was observed between fluxapyroxad and pydiflumetofen. We concluded that the resistance of S. solani to fluxapyroxad was moderate risk. Therefore, fluxapyroxad is recommended as a potential candidate for controlling tomato gray leaf spot caused by S. solani. • Fluxapyroxad exhibited an excellent in vitro antifungal activity against Stemphylium solani. • The resistance of Stemphylium solani to fluxapyroxad was classified as moderate risk. • There was a positive cross-resistance between fluxapyroxad and pydiflumetofen against Stemphylium solani. • Fluxapyroxad is recommended as a potential candidate for controlling tomato gray leaf spot caused by Stemphylium solani. [ABSTRACT FROM AUTHOR]

This study intended to investigate the role of microRNA-27b (miR-27b) in proliferation of oral squamous cell carcinoma (OSCC) cells and to explore the potential molecular mechanism. Cell proliferation was detected by MTT assay. The expression levels of miR-27b, Frizzled7 ( FZD7 ), cyclin D1 and c-myc were detected by quantitative real time polymerase chain reaction (qRT-PCR). The protein expression level of FZD7 was detected by western blot analysis. The relationship between miR-27b and FZD7, and the activity of Wnt signaling pathway were determined using luciferase reporter assay. The miR-27b expression in OSCC cell lines was significantly decreased compared with control. Overexpression of miR-27b remarkably inhibited OSCC cell proliferation. Additionally, miR-27b could target and inhibit FZD7 expression and decrease the activity of Wnt signaling pathway.miR-27b could inhibit OSCC cell proliferation through inhibiting FZD7 and FZD7-mediated Wnt signaling pathway. [ABSTRACT FROM AUTHOR]