Drug­resistant Acinetobacter baumannii: From molecular mechanisms to potential therapeutics (Review).

Bacterial drug resistance is increasingly becoming an important problem that needs to be solved urgently in modern clinical practices. Infection caused by Acinetobacter baumannii is a serious threat to the life and health of patients. The drug resistance rate of Acinetobacter baumannii strains is increasing, thus research on the drug resistance of Acinetobacter baumannii has also seen an increase. When patients are infected with drug-resistant Acinetobacter baumannii, the availability of suitable antibiotics commonly used in clinical practices is becoming increasingly limited and the prognosis of patients is worsening. Studying the molecular mechanism of the drug resistance of Acinetobacter baumannii is fundamental to solving the problem of drug-resistant Acinetobacter baumannii and potentially other 'super bacteria'. Drug resistance mechanisms primarily include enzymes, membrane proteins, efflux pumps and beneficial mutations. Research on the underlying mechanisms provides a theoretical basis for the use and development of antibiotics and the development of novel treatment methods.

Effect of extrusion parameters on the interaction between rice starch and glutelin in the preparation of reconstituted rice.

Reconstituted rice produced by extrusion has been attracted attention due to nutritional fortification and convenient production. Nevertheless, how to achieve desirable qualities and physicochemical properties of reconstituted rice nearly to natural rice by regulating extrusion process parameters is difficult. Herein, rice starch/glutelin mixture as raw material of reconstituted rice was extruded at varying extrusion conditions. Specific mechanical energy (SME) and sectional expansion index (SEI) dropped with rise in density (R2 = 0.9117 and 0.8207). Solubility was enhanced with increase in product temperature (R2 = 0.9085), color darkened and shifted to reddish and yellowish as extrusion temperature increased (R2 = 0.8577). These trends were well fitted by sigmoid models. Furthermore, SME enhanced hydrophobic and electrostatic interactions between rice starch and glutelin and caused the reduction in crystallinity and thermal stability, promoting the formation of a bi-continuous matrix of protein aggregates with rice starch. The obtained results can be applied to guide the production of reconstituted rice with desirable qualities.

Insights into the interaction mechanism of glutelin and rice starch during extrusion processing: The role of specific mechanical energy.

Extruded glutelin/rice starch composites were prepared using twin-screw extrusion at various specific mechanical energies (SME), and the interaction mechanism of glutelin and rice starch was investigated at the molecular level. The results indicated that the structure of glutelin was destroyed, hydrophobic interactions and hydrogen bonds between rice starch and glutelin were formed and enhanced as the SME increased, and new hydrogen bonds were formed at the carbonyl (δ- and γ-carbons of glutelin) and C-1 of Tyr. Molecular docking studies confirmed that SME promoted the simultaneous occurrence of the Millard reaction and non-covalent reaction between glutelin and small molecular sugars produced by starch degradation, providing information on binding sites. Additionally, scanning electron microscopy (SEM) revealed dense and uniform flake-like structures induced by these binding interactions. Overall, insights into the interaction mechanism of rice starch and glutelin provide theoretical references for generating reconstituted rice products using extrusion processing.

Impact of calcium ions and degree of oxidation on the structural, physicochemical, and in-vitro release properties of resveratrol-loaded oxidized gellan gum hydrogel beads.

Oxidized gellan gum (OGG) hydrogel beads as delivery systems for resveratrol were fabricated by ionic cross-linking with calcium chloride (CaCl2). The degree of oxidation (DO) and CaCl2 concentration had significant influences on the formation and functional properties of hydrogel beads. The resveratrol encapsulation efficiency (66.43%-79.84%) and loading capacity (4.15%-5.05%) of OGG hydrogel beads were enhanced as DO increased. The hydrogel beads exhibited a uniform spherical shape as observed by scanning electron microscope. Fourier transform infrared spectroscopy analysis confirmed that hydrogen bonds and ionic interaction participated in the formation of hydrogel beads. X-ray diffraction analysis revealed that the physical state of resveratrol was changed from crystalline to amorphous form after encapsulation. Furthermore, the physical stability and antioxidant capacity evaluation demonstrated that the hydrogel bead fabricated with DO80 OGG and CaCl2 concentration of 1.0 M could provide high protection for resveratrol against degradation by environmental stresses and maintain its antioxidant capacity. The DO and CaCl2 concentrations could modulate the in-vitro release behaviors of hydrogel beads and obtain a good small intestinal-targeted release of resveratrol at high DO and medium CaCl2 concentration. These findings suggested that a promising delivery system for encapsulating bioactive ingredients can be fabricated by rational design.

Preparation, physicochemical characterization and in vitro release behavior of resveratrol-loaded oxidized gellan gum/resistant starch hydrogel beads.

Hydrogel beads composed of oxidized gellan gum (OGG) and resistant starch (RS) were successfully fabricated by ionic cross-linking and used as delivery carriers for resveratrol. Firstly, OGG with different degrees of oxidation were prepared through 2, 2, 6, 6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation, and characterized by Fourier transform infrared spectroscopy and carbon-13 nuclear magnetic resonance to prove that carboxyl groups were successfully introduced into the gellan gum molecules. Molecular weight, thermal stability, zeta potential and gelation temperature of OGG were also investigated. Subsequently, resveratrol was encapsulated into OGG/RS hydrogel beads in the form of resveratrol/ß-cyclodextrins inclusion complexes. The addition of RS significantly influenced the morphological structure and swelling capacity of OGG/RS hydrogel beads. The OGG/RS hydrogel beads exhibited a pH-sensitivity and high encapsulation efficiency of resveratrol (84.95 %-90.73 %). Furthermore, the in-vitro release behaviors demonstrated that OGG/RS hydrogel beads showed good stability in simulated gastric fluids and sustained release of resveratrol in simulated intestinal fluids. The obtained results indicate that OGG/RS hydrogel beads show a potential as delivery system for resveratrol in the food industry.

Lipase-catalyzed Synthesis of Feruloylated Lysophospholipid in Toluene-Ionic Liquids and Its Antioxidant Activity.

In this study, Novozym 435-catalyzed interesterification of ethyl ferulate (EF) with phosphatidylcholine (PC) in a two-phase system consisting of an ionic liquid (IL) and toluene was optimized to prepare feruloylated lysophospholipids (FLPs). Optimum conditions for the interesterification process were found to be [Bmim][Tf2N]/toluene ratio of 1:1 (v/v), solvent volume of 4 mL, molecular sieves (4 Å) concentration of 80 mg/mL, reaction temperature of 55°C, substrate molar ratio of 5:1 (PC/EF), Novozym 435 concentration of 50 mg/mL. Under these conditions, two FLPs products (1-FLP and 2-FLP) with total conversion rate of 50.79% were obtained. Because the formation of 1-FLP was significantly higher than 2-FLP, 1-FLP was purified and characterized by LC-MS and NMR. In addition, 1-FLP showed DPPH scavenging activity comparable with those of EF and BHT. Therefore, this study provides a good method for transformation of ferulic acid to improve its solubility and promote its application as functional ingredient in the food and pharmaceutical industries.

CXCR4/TGF-ß1 mediated hepatic stellate cells differentiation into carcinoma-associated fibroblasts and promoted liver metastasis of colon cancer.

Background: Liver metastasis of colon cancer is strongly affected by the tumor microenvironment (TME), with interactions between tumor cells and cancer-associated fibroblasts (CAFs) in particular. TGF-ß is well known for its ability to mediate the CAF phenotype, and CXCR4 expression is closely correlated to poor prognosis in CRC. The relationship between these two signaling pathways remains to be delineated in liver metastasis of colon cancer.Methods: Immunohistochemistry was employed to investigate CXCR4 expression in 45 human specimens of primary colorectal cancer (CRC) and liver metastasis. The functions of SDF-1 released by hepatic stellate cells (HSCs) on CXCR4 and TGF-ß1 in CRC cells were investigated in vitro. The effects of CRC on HSCs differentiation into CAFs were confirmed using co-culture technology and expression analysis of CAFs markers by qPCR, western blot and immunofluorescence. The involvement of CXCR4 and TGF-ß1 was verified with addition of CXCR4 inhibitor AMD3100 and TGF-ß1 inhibitor cyclophosphamide (Cy) both in vitro and in vivo.Results: There were more CXCR4-positive cells at the liver metastatic tissues compared to the primary sites. CRC cells activated and transformed HSCs to CAFs after co-cultivating with HSCs. Activated HSCs stimulated TGF-ß1 secretion from CRC cells after co-culture with CRC cells in vitro. Moreover, the expression of CAFs markers was increasing in the activated HSCs. In a mouse hepatic metastasis model, treated with AMD3100 or Cy blocked the metastatic potential of HCT116 cells and the hepatic CAFs differentiation.Conclusions: These results indicated that CXCR4/TGF-ß1 axis plays an important role in CRC liver metastasis through mediating HSCs differentiation into CAFs, providing preclinical evidences that blockade of the axis might be beneficial for anti-metastasis therapy in CRC.

CXCR4/TGF-ß1 mediated self-differentiation of human mesenchymal stem cells to carcinoma-associated fibroblasts and promoted colorectal carcinoma development.

Background: Tumor microenvironment (TME) is a crucial part of tumor hallmarks. Mesenchymal stem cells (MSCs), important components of TME, are the main source of Carcinoma-associated fibroblasts (CAFs), but the mechanism of transformation regulation is still unclear. Transforming growth factor-ß1 (TGF-ß1), chemokine Stromal cell-derived factor-1 (SDF-1) and its endogenous receptor CXCR4 may play important roles during this process.Methods: Co-culture technique was used to explore the effects of MSCs on the proliferation, migration and invasion of colorectal carcinoma (CRC) cells and how they induced MSCs to differentiate into CAFs. The expression of α-SMA, Vimentin, S100A4 and FAP were detected as CAFs markers. Inhibitors AMD3100 and cyclophosphamide (Cy) were pre-treated in MSCs to verify the functions of CXCR4/TGF-ß1. Finally, the xenograft models in nude mice were generated to further verify this process in vivo.Results: MSCs promoted the CRCs proliferation, invasion and migration, and induced SDF-1 expression and secretion, which dramatically up-regulated CXCR4 and TGF-ß1 expression in MSCs. The levels of CAFs markers elevated in MSCs, indicating CAFs differentiation occurred in MSCs. AMD3100 and Cy treatment significantly blocked this differentiation process of MSCs by suppressing CXCR4 expression and TGF-ß1 secretion. In vivo xenograft experiments also demonstrated that MSCs promoted differentiation into CAFs through CXCR4/TGF-ß1 signaling in either primary tumor tissues or hepatic metastatic tissues of CRC.Conclusion: Our studies have revealed the essential role of CXCR4/TGF-ß1 axis playing in the transformation of tumor microenvironment by mediating MSCs differentiation into CAFs, promoting CRCs growth and metastasis.

[Effects of Rehmannia glutinosa consecutive monoculture on the community structure and diversity of phyllosphere bacteria]. / åœ°é»„è¿žä½œå¯¹å¶é™ ç»†èŒç¾¤è½ç»“æž„åŠå¤šæ ·æ€§çš„å½±å“.

Rehmannia glutinosa, a perennial herbaceous species, belongs to the family Scrophularia-ceae. As a staple medicinal material, its tuberous roots are highly valued in traditional Chinese medicine. However, R. glutinosa suffers from serious consecutive monoculture problems in production, which leads to a decline in both productivity and quality. Phyllosphere bacteria, the most abundant component of phyllosphere microorganisms, play crucial roles in plant growth and health. Characterization of phyllosphere bacteria could provide new insights into the mechanisms of consecutive monoculture problems and their control measures. Meanwhile, the varied taxa could be served as an important indicator of consecutive monoculture problems. The barcoded pyrosequencing of 16S rDNA genes combined with a culture-dependent approach was applied to characterize the shifts of bacterial community structure and diversity in the phyllosphere under consecutive monoculture of R. glutinosa. The results showed that consecutive monoculture clearly affected bacterial community structure in the phyllosphere. The phyllosphere bacterial communities of the two-year monocultured (TY) and the diseased plants (DP) were more similar, and different from the one-year monocultured (OY). The evenness, Shannon and Simpson diversity indices were significantly lower in TY and DP than in OY. Species annotation showed that bacterial community in R. glutinosa phyllosphere mainly consisted of Proteobacteria (91.2%), Firmicutes (5.1%) and Actinobacteria (3.7%). There was no significant difference in the number of detected bacterial taxa. However, Proteobacteria was significantly increased while Firmicutes and Actinobacteria were significantly decreased under consecutive monoculture. At the genus level, the relative abundances of genera Exiguobacterium, Bacillus and Arthrobacter, potentially beneficial microorganisms, were significantly higher in OY than that in TY and DP, but it was opposite for the genus Pseudomonas. The results from the culture-dependent approach and pathogenicity test showed that Pseudomonas plecoglossicida D9, widely isolated from the diseased leaves, was highly pathogenic to leaves. In conclusion, R. glutinosa monoculture resulted in distinct phyllosphere bacterial community variation with the accumulation of pathogen loads at the expense of beneficial microorganisms, which could contribute to the occurrence of leaf disease symptoms,and aggravate R. glutinosa replant disease in a monoculture regime.

Fine structure, crystalline and physicochemical properties of waxy corn starch treated by ultrasound irradiation.

As a simple and effective physical method, ultrasound irradiation has been used to modify starch. Native waxy corn starch was treated by ultrasound irradiation at 100 and 400 W in this study. Compared with native waxy corn starch, lower proportion of B1, B2, and B3, higher proportion of A chain were observed in ultrasonicated waxy corn starch. 1H NMR combined with HPSEC-MALLS-RI data showed that lower degree of branching was observed in ultrasonicated waxy corn starch, and α-1,4 glycosidic linkages were more stable than α-1,6 glycosidic linkages in waxy corn starches. 13C NMR data indicated that the content of double helices was decreased, and single helix and amorphous components were increased after ultrasound irradiation. The A-type crystal structure was scarcely affected according to X-ray diffraction (XRD) analysis. The granule surface of ultrasonicated waxy corn starch became notch and rough fragment, and lower particle diameter was observed in ultrasonicated waxy corn starch. These results demonstrated that ultrasound irradiation affected chain length distribution, double helices, single helices and amorphous state, especially α-1,4 glycosidic linkages and α-1,6 glycosidic linkages, of waxy corn starch.

Comparative Structural Characterization of Spiral Dextrin Inclusion Complexes with Vitamin E or Soy Isoflavone.

In this study, the preparation and structural properties of spiral dextrin (SD)/vitamin E and SD/soy isoflavone inclusion complexes were studied. SD was obtained from debranched normal maize starch using isoamylases. After fractionation using a novel method of gradient ethanol precipitation, SD was separated into different fractions, among which SD-40 was found to be the optimal host molecule to prepare SD inclusion complexes with vitamin E or soy isoflavone. X-ray diffraction (XRD) and 13C cross-polarization magic angle spinning nuclear magnetic resonance (NMR) suggested that the crystalline structures of SD-40/vitamin E and SD-40/soy isoflavone were V6II and V6III types, respectively. Small-angle X-ray scattering revealed that the SD-40/vitamin E inclusion complex formed a tighter and more compact crystallite than the SD-40/soy isoflavone inclusion complex. Furthermore, the connection structures of inclusion complexes were investigated by two-dimensional nuclear Overhauser effect spectroscopy NMR, indicating that part of vitamin E with an alkyl chain was encapsulated in the helix cavity of SD-40, whereas the aromatic ring B of the soy isoflavone molecule was complexed by the helix cavity and screw of SD.

Clinical significance of microRNA-93 downregulation in human colon cancer.

AIM: MicroRNA-93 (miR-93) has been shown to suppress proliferation and colony formation of colon cancer stem cells. The aim of this study was to examine the expression pattern and prognostic value of miR-93 in patients with colon cancer. MATERIALS AND METHODS: A quantitative real-time PCR analysis was carried out to detect the expression levels of miR-93 in 138 paired samples of tumoral and nontumoral colon tissues diagnosed with colon cancer. Associations of miR-93 expression with clinicopathological parameters and survival were also examined. RESULTS: miR-93 expression was significantly decreased in tumoral compared with nontumoral colon tissues (P<0.001). Low miR-93 expression was significantly correlated with advanced tumor stage (P=0.02), positive nodal metastasis (P=0.006), and positive distant metastases (P=0.01). In addition, Kaplan-Meier survival analysis by Cox regression showed that low miR-93 expression [hazard ratio (HR), 10.2; 95% confidence interval (CI), 1.9-42.8, P=0.003] was associated closely with poor overall survival in patients with colon cancer. Moreover, multivariate analysis showed that miR-93 decreased expression (HR, 4.3; 95% CI, 0.8-17.2, P=0.02), advanced tumor stage (HR, 3.1; 95% CI, 0.2-13.9, P=0.04), positive nodal metastasis (HR, 4.1; 95% CI, 0.7-16.8, P=0.02), and positive distant metastases (HR, 3.7; 95% CI, 0.5-14.1, P=0.03) were independent risk factors for overall survival in patients with colon cancer. CONCLUSION: Our data show for the first time that the downregulation of miR-93 was significantly correlated with unfavorable clinicopathologic features and short overall survival in patients with colon cancer, suggesting that decreased expression of miR-93 be used as a novel prognostic factor for this disease.

[Diagnosis and treatment of slow transit constipation complicated with adult megacolon].

OBJECTIVE: To summarize the experience in the management of slow transit constipation complicated with adult megacolon. METHODS: The clinical data of 32 above patients admitted between October 2007 and June 2011 were retrospectively studied. RESULTS: Thirty-two patients were diagnosed as slow transit constipation according to the Roman III criteria. There were 15 males and 17 females aging from 18 to 56 years old. Sitz marker study showed prolonged colon transit time. Barium enema and defecography suggested bowel stricture locating in the transverse colon (n=3), descending colon (n=4), rectum (n=20), and concurrent transverse colon or descending colon and rectum (n=5). Anal manometry showed that anorectal inhibitory reflex was absent in 23 patients, while the other 9 patients were normal. Procedures performed included segmental colectomy and side-to-side anastomosis (n=1), subtotal colectomy and modified Duhamel anastomosis (n=16), total colectomy and ileal J-pouch Duhamel anastomosis (n=9). There were no postoperative complications. During the follow-up ranging from 3 to 47 months, defacatory function was excellent in 18, good in 9, and moderate in 5 patients. CONCLUSIONS: Adult megacolon should be considered differential diagnosis of slow transit constipation. Detailed history taking and thorough evaluation of testing is the key to obviate misdiagnosis. Extent of resection should include the diseased dilated colon and slow transit colon.