Characterization of a thermophilic L-rhamnose isomerase from Caldicellulosiruptor saccharolyticus ATCC 43494

L-Rhamnose isomerase (EC 5.3.1.14, l-RhI) catalyzes the reversible aldose-ketose isomerization between L-rhamnose and L-rhamnulose. In this study, the L-rhi gene encoding L-RhI was PCR-cloned from Caldicellulosiruptor saccharolyticus ATCC 43494 and then expressed in Escherichia coli. A high yield of active L-RhI, 3010 U/g of wet cells, was obtained after 20 °C induction for 20 h. The enzyme was purified sequentially using heat treatment, nucleic acid precipitation, and ion-exchange chromatography. The purified L-RhI showed an apparent optimal pH of 7 and an optimal temperature at 90 °C. The enzyme was stable at pH values ranging from 4 to 11 and retained >90% activity after a 6 h incubation at 80 °C and pH 7-8. Compared with other previously characterized L-RhIs, the L-RhI from C. saccharolyticus ATCC 43494 has a good thermostability, the widest pH-stable range, and the highest catalytic efficiencies (k(cat)/K(M)) against L-rhamnose, L-lyxose, L-mannose, D-allose, and D-ribose, suggesting that this enzyme has the potential to be applied in rare sugar production.     

Tumor-promoting effect of GGN-MRP extract from the Maillard reaction products of glucose and glycine in the presence of sodium nitrite in C3H10T1/2 cells.

GGN-MRP is an extract from the Maillard reaction products of nitrite with glucose and glycine in the Maillard browning system. No genotoxicity of GGN-MRP in culture hepatocyte was found. A two-stage transformation protocol was used to transform chemically mouse embryo fibroblast C3H10T1/2 cells. To initiate transformation, the cells were treated with benzo[a]pyrene [B(a)P; 0.1 microg/mL], and GGN-MRP (0.01, 0.1, and 1.0 mg/mL) was employed to subsequently complete the transformation process. Malignant transformed foci were formed in B(a)P-initiated and GGN-MRP-promoted C3H10T1/2 cells after 8 weeks. Cells treated with GGN-MRP alone failed to induce transformation. However, cells initiated with B(a)P and promoted by GGN-MRP demonstrated oncogenic properties. Transformed colonies derived from GGN-MRP-treated cells exhibited enhanced growth rate, anchorage independence, and tumorgenicity in animals relative to parent cells. These results indicated that GGN-MRP contains a tumor promoter and may induce tumor promotion by two-stage oncogenesis.     

Spontaneous differentiation of adult rat marrow stromal cells in a long-term culture

It is well recognized that bone marrow stromal cells (MSCs) can differentiate into neuron-like cells when supplemented with growth factors and/or chemical treatments. We demonstrated that primary MSCs obtained from adult rats could spontaneously differentiate into neural precursor cells after long-term culture. During the outset of in vitro culture, less than 0.1% of adult rat primary MSCs expressed nestin, the common protein of neural precursors. These MSCs didn't show neuronal morphology nor express neuronal antigens. In contrast, after continuous maintenance for 6 weeks, a significant subpopulation of MSCs formed cellular clumps and expressed nestin (32.3 +/- 6.3%). Less than 0.1% of cells expressing immature neuron marker betaIII-tubulin could be detected in these prolonged cultured MSCs. After serum deprivation and growth factor supplement, these nestin-positive cells could express neuron-like morphology and neuron-specific markers NF-H, betaIII-tubulin, tau, and neurotransmitter GABA. In contrast, the MSCs without prolonged culture didn't show neuronal morphology nor neuronal markers even after serum withdrawal and growth factors stimulation. These results demonstrated that neural precursors could be obtained from long-term cultured MSCs, and suggested that MSCs should be useful as a potential source for treatment of neurological disease.     

Use of vacuum-assisted closure for management of a large skin wound in a cat

CASE DESCRIPTION: A 9-month-old domestic shorthair cat was evaluated after being struck by a car. CLINICAL FINDINGS: The cat had a fractured tibia and avulsion of the tail base. Motor and deep pain sensation were absent from the tail. The fractured tibia was repaired 2 days after the trauma. On the third day, the cat developed tachypnea, dyspnea, high serum urea nitrogen and total bilirubin concentrations, epistaxis, persistent hypotension, and oliguria. The cat recovered with supportive care but developed extensive necrosis of the skin on the dorsum by 9 days after the initial trauma. TREATMENT AND OUTCOME: The skin was debrided from the caudal portion of the scapula to the anus and down each pelvic limb to the level of the distal portion of the femur. The tail was amputated. Wet-to-dry bandages were applied to the wound for 3 days. Approximately 50% of the wound underwent delayed primary closure, and the remainder was managed with vacuum-assisted closure. A healthy granulation bed was quickly established. Vacuum-assisted closure was also applied after graft application. Graft acceptance was 100%, and use of the vacuum-assisted closure bandage was not associated with the complications associated with the traditional bandage. CLINICAL RELEVANCE: Vacuum-assisted closure is a useful, easily applicable technique for open and grafted wounds, even when wounds are in challenging anatomic locations.     

Fire retardancy and CO/CO2 emission of intumescent coatings on thin plywood panel with waterborne vinyl acetate-acrylic resin

Using intumescent coatings on wood-based materials is an effective method for fire safety. Previous studies have demonstrated that the formulation of components strongly influences the performance of coatings. This study investigated the effect of intumescent formulation of vinyl acetate-acrylic coating on flame retardancy of plywood. The fire retardancy of materials was assessed by both heat release and CO and CO₂ emissions. The CO and CO₂ emissions have not been used frequently to rank materials; the highly toxic CO and CO₂ may cause most fire fatalities. The fire retardancy of coatings on plywood was assessed by a cone calorimeter. Total heat release and time to peak heat release rate were the two primary parameters. The data show that low contents of binder resin (BR) and foam producing substance (FPS) decreased total heat release and lengthened time to peak heat release rate. Additionally, low BR and FPS content can form an ideal char layer. The ideal char layer significantly decreased the CO and CO₂ emission. The mechanism to achieve better fire performance was verified by thermogravimetrical analysis exhibiting lower weight loss. Moreover, evaluated by ³¹P NMR, the low BR and FPS content can extend the survival duration of phosphor-carbonaceous chars. The results provide information for designing vinyl acetate-acrylic emulsion coating.     

Antioxidant Activity and Characterization of Phenolic Compounds from Bacaba ( Oenocarpus bacaba Mart.) Fruit by HPLC-DAD-MS(n)

The phytochemicals in fruits have been shown to be major bioactive compounds with regard to health benefits. Bacaba ( Oenocarpus bacaba Mart.) is a native palm fruit from the Brazilian savannah and Amazon rainforest that plays an important role in the diet of rural communities and is also a source of income for poor people. This paper reports the characterization and analyses of phenolics from bacaba fruit extract. The total phenolic content of bacaba fruit amounted to 1759.27 ± 1.01 mg GAE/100 g, the flavonoid content was 1134.32 ± 0.03 mg CTE/100 g, and the anthocyanin content was 34.69 ± 0.00 mg cyn-3-glc/100 g. The antioxidant activity was evaluated through different assays [ORAC, FRAP, DPPH, TEAC, and cellular antioxidant assay (CAA) assays] and revealed a significant antioxidant capacity for bacaba in comparison to the data available in the literature. The assignment of the phenolic compounds using HPLC-DAD-MS(n) was based on the evaluation of their UV-vis absorption maxima (λ(max)) and mass spectral analyses, and 14 compounds were tentatively identified. The results suggest that bacaba fruits are a promising source of phenolics.