Evaluation of the probiotic potential of yeast isolated from kombucha in New Zealand.

The current study investigated the in vitro probiotic potential of yeast isolated from kombucha, a tea beverage fermented with a symbiotic culture of acetic acid bacteria and yeast. A total of 62 yeast strains were previously isolated from four different commercial kombucha samples sold in New Zealand. Fifteen representative isolates belonging to eight different species were evaluated for their growth under different conditions (temperature, low pH, concentrations of bile salts, and NaCl). Cell surface characteristics, functional and enzymatic activities of the selected strains were also studied in triplicate experiments. Results showed that six strains (Dekkera bruxellensis LBY1, Sachizosaccharomyces pombe LBY5, Hanseniaspora valbyensis DOY1, Brettanomyces anomalus DOY8, Pichia kudraivzevii GBY1, and Saccharomyces cerevisiae GBY2) were able to grow under low-acid conditions (at pH 2 and pH 3) and in the presence of bile salts. This suggests their potential to survive passage through the human gut. All 15 strains exhibited negative enzymatic activity reactions (haemolytic, gelatinase, phospholipase, and protease activities), and thus, they can be considered safe to consume. Notably, two of the fifteen strains (Pichia kudraivzevii GBY1 and Saccharomyces cerevisiae GBY2) exhibited desirable cell surface hydrophobicity (64.60-83.87%), auto-aggregation (>98%), co-aggregation, resistance to eight tested antibiotics (ampicillin, chloramphenicol, colistin sulphate, kanamycin, nalidixic acid, nitrofurantoin, streptomycin, and tetracycline), and high levels of antioxidant activities (>90%). Together, our data reveal the probiotic activities of two yeast strains GBY1 and GBY2 and their potential application in functional food production.

Self-healing FBG sensor network fault-detection based on a multi-class SVM algorithm.

We propose a three-layer ring architecture with enhanced reconfigurable capabilities for fiber Bragg grating (FBG) sensor networks. The proposed network is capable of self-healing when three fiber links fail. In addition to self-healing, soft faults in the FBG sensors can be detected using a multi-classification support vector machine (multi-class SVM) algorithm. The detection accuracy reached 99%. Additionally, we used an artificial neural network (ANN) reliability estimation model to estimate the reliability of the FBG self-healing network. The results show that the ANN reliability analysis model can accurately estimate the reliability of the architecture at a reasonable cost.

Microbiological and Physico-Chemical Characteristics of Black Tea Kombucha Fermented with a New Zealand Starter Culture.

Kombucha is a popular sparkling sugared tea, fermented by a symbiotic culture of acetic acid bacteria (AAB) and yeast. The demand for kombucha continues to increase worldwide, mainly due to its perceived health benefits and appealing sensory properties. This study isolated and characterised the dominant AAB and yeast from a starter culture and kombucha broth after 0, 1, 3, 5, 7, 9, 11, and 14 days of fermentation at ambient temperature (22 °C). Yeast and AAB were isolated from the Kombucha samples using glucose yeast extract mannitol ethanol acetic acid (GYMEA) and yeast extract glucose chloramphenicol (YGC) media, respectively. The phenotypic and taxonomic identification of AAB and yeast were determined by morphological and biochemical characterisation, followed by a sequence analysis of the ribosomal RNA gene (16S rRNA for AAB and ITS for yeast). The changes in the microbial composition were associated with variations in the physico-chemical characteristics of kombucha tea, such as pH, titratable acidity, and total soluble solids (TSS). During fermentation, the acidity increased and the TSS decreased. The yield, moisture content, and water activity of the cellulosic pellicles which had developed at the end of fermentation were attributed to the presence of AAB. The dominant AAB species in the cellulosic pellicles and kombucha broth were identified as Komagataeibacter rhaeticus. The yeast isolates belonged to Debaryomyces prosopidis and Zygosaccharomyces lentus.

Baicalein ameliorates polymyxin B-induced acute renal injury by inhibiting ferroptosis via regulation of SIRT1/p53 acetylation.

The polypeptide antibiotic Polymyxin B (PMB) can cause acute kidney injury (AKI), we found that ferroptosis is one of the main mechanisms of renal injury caused by PMB. It was reported that baicalein can inhibit ferroptosis. Therefore, in this study we examined whether baicalein could attenuate PMB-induced renal injury by inhibiting ferroptosis. We confirmed that baicalein could reduce PMB-induced renal injury in vivo and in vitro studies. In the in vitro study, baicalein significantly increased the survival rate of human HK2 tubular epithelial cells. The results of HE staining and electron microscopy in mice also showed that baicalein reduced PMB-induced renal injury, and significantly decreased the levels of BUN and Scr. By detecting ferroptosis-related indicators, we found that pre-incubation of baicalein in HK2 cells down-regulated Fe2+ level, lipid peroxidation, MDA and HO-1 which had been increased by PMB. Furthermore, baicalein up-regulated the levels of SCL7A11, GPX4 and GSH that were decreased by PMB. Moreover, intraperitoneal injection of baicalein in the animal model down-regulated kidney iron level, PTGS2 and 4HNE, and increased the GSH level, which suggested that baicalein could inhibit PMB-induced ferroptosis. Finally, by detecting changes in levels of p53 and p53 K382 acetylation, baicalein was observed to decrease elevated p53 K382 acetylation after PMB treatment, further confirming that baicalein inhibits ferroptosis by reducing p53 K382 acetylation via upregulation of SIRT1 expression. In conclusion, these results suggest that baicalein decreases p53 acetylation level by elevating SIRT1, which can then inhibit PMB-induced ferroptosis and ultimately attenuates AKI.

Ferroptosis is involved in polymyxin B-induced acute kidney injury via activation of p53.

Polymyxin B (PMB) is one of the most effective drugs for the treatment of multi-resistant and pan-resistant gram-negative infections. However, it can induce acute kidney injury (AKI), the mechanism of which has not yet been fully elucidated. In this study, RNA sequencing and in vitro and in vivo experiments demonstrated that PMB induced AKI by promoting ferroptosis. Moreover, the metallothionein-1 (MT-1) level was significantly increased in the AKI group and clinical cases revealed that iron and MT-1 levels in urine were significantly higher in patients with AKI than in those without AKI. To explore the mechanism of PMB induced ferroptosis, we silenced p53 in human kidney-2 (HK2) cells according to RNA sequencing, which showed that p53 was obviously enhanced in the PMB treated group. While PMB significantly enhanced Fe2+, lipid peroxidation, malondialdehyde (MDA), transferrin receptor protein 1 (TFR1), and arachidonate 12-lpoxygenase (ALOX12), decreased the survival rate, solute carrier family 7 member 11 (SLC7A11), glutathione peroxidase 4 (GPX4), and glutathione (GSH), downregulation of p53 reversed these effects, suggesting PMB induced ferroptosis by activating p53. Studies have shown p53 can promote ferroptosis by regulating the downstream factors SLC7A11 or TFR1. Further, we verified that silencing TFR1 expression as well as overexpression of SLC7A11 inhibited ferroptosis and significantly increased the survival rate of HK2 cells. Overall, PMB induces ferroptosis in renal tubular cells by activating p53 to reduce SLC7A11 expression and elevate TFR1, leading to AKI; MT-1 and iron levels in urine were significantly increased when PMB induced ferroptosis.

Piezo-phototronic effect regulated broadband photoresponse of a-Ga2O3/ZnO heterojunction.

Amorphous Ga2O3 (a-Ga2O3) films have attracted considerable attention in the field of photodetectors due to their excellent optical absorption response and photoelectric properties. However, there are few studies that have utilized the piezo-phototronic effect to regulate the broadband photoresponse of Ga2O3-based photodetectors. Here, a flexible a-Ga2O3/ZnO heterojunction was constructed, which demonstrated a broadband response range from deep ultraviolet (265 nm) to the near-infrared (1060 nm) and realized a bidirectional adjustable photocurrent response via the piezo-phototronic effect. Under 265 nm illumination and 0.5 V bias, the responsivity and detectivity of the a-Ga2O3/ZnO heterojunction reached up to 12.19 A W-1 and 4.71 × 1011 Jones under 0.164% compressive strain, corresponding to enhancements of 67.7% and 66.8% compared to those under a strain-free state, respectively. Moreover, the broadband photoresponse of the a-Ga2O3/ZnO heterojunction beyond the bandgap limit was tunable under bidirectional strain. The working mechanism of photoresponse performance for the a-Ga2O3/ZnO heterojunction at different wavelengths was elucidated in detail. Oxygen vacancy-assisted carrier generation was found to be influenced by the wavelength of incident light, which mainly determined the broadband photoresponse of the heterojunction. The modulation of the a-Ga2O3/ZnO heterojunction photodetector was interpreted in light of the strain-induced regulation of the barrier height. This work represents an important step toward the development of adjustable broadband photodetectors based on a-Ga2O3 films.

Kombucha: Production and Microbiological Research.

Kombucha is a sparkling sugared tea commonly prepared using a sugared tea infusion and fermented at ambient temperature for several days using a cellulose pellicle also called tea fungus that is comprised of acetic acid bacteria and yeast. Consumption of Kombucha has been reported as early as 220 B.C. with various reported potential health benefits and appealing sensory properties. During Kombucha fermentation, sucrose is hydrolysed by yeast cells into fructose and glucose, which are then metabolised to ethanol. The ethanol is then oxidised by acetic acid bacteria (AAB) to produce acetic acid which is responsible for the reduction of the pH and also contributes to the sour taste of Kombucha. Characterisation of the AAB and yeast in the Kombucha starter culture can provide a better understanding of the fermentation process. This knowledge can potentially aid in the production of higher quality products as these microorganisms affect the production of metabolites such as organic acids which are associated with potential health benefits, as well as sensory properties. This review presents recent advances in the isolation, enumeration, biochemical characteristics, conventional phenotypic identification system, and modern genetic identification techniques of AAB and yeast present in Kombucha to gain a better understanding of the microbial diversity of the beverage.

Significantly Enhanced Breakdown Strength and Energy Density in Nanocomposites by Synergic Modulation of Structural Design and Low-Loading Nanofibers.

Polymer-based dielectric nanocomposites have attracted great attention due to the advantages of high-power density and stability. However, due to the limited breakdown strength (Eb) of the dielectrics, the unsatisfactory energy density becomes the bottleneck that restricts their applications. Here, newly designed sandwich-structured nanocomposites are proposed, which includes the introduction of low-loading 0.4BiFeO3-0.6SrTiO3 (BFSTO) nanofibers into the poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) matrix as the polarization layer (B-layer) to offer high permittivity and the selection of poly(methylmethacrylate) (PMMA)/P(VDF-HFP) all-organic blend film as the insulation layer (P-layer) to improve Eb of the nanocomposites. The optimized sandwich-structured PBP nanocomposite exhibits significant enhancement in Eb (668.6 MV/m), generating a discharged energy density of 17.2 J/cm3. The dielectric and Kelvin probe force microscope results corroborate that the outer P-layer has a low surface charge density, which can markedly impede the charge injection from the electrode/dielectric interface and thereby suppress the leakage current inside the nanocomposite. Furthermore, both the finite element simulations and capacitive series models demonstrate that the homogenized distribution of electric field in the PBP sandwich-structured nanocomposite favors the improvement of energy storage performance. This work not only provides insightful guidance into the in-depth understanding of the dielectric breakdown mechanism in sandwich-structured nanocomposites but also offers a novel paradigm for the development of polymer-based nanocomposites with high Eb and discharged energy density.

Connexin32 regulates expansion of liver cancer stem cells via the PI3K/Akt signaling pathway.

Liver cancer stem cells (LCSCs) are responsible for liver cancer recurrence, metastasis, and drug resistance. Previous studies by the authors demonstrated that upregulated expression of connexin 32 (Cx32) reversed doxorubicin resistance and reduced invasion and metastasis of liver cancer cells. However, the role of Cx32 in expansion of LCSCs remains unclear. A total of 85 patients were enrolled in the present study and followed­up for 5 years. The expression of Cx32 in hepatocellular carcinoma (HCC) tissues and corresponding paracancerous tissues were detected by immunohistochemistry (IHC). Cx32 was silenced in HepG2 cells and overexpressed in HCCLM3 cells and the stemness of liver cells was examined by detecting the expression of LCSC markers (EpCAM, CD133, Nanog, Oct4, Sox9, c­Myc), sphere formation, and xenograft tumorigenesis. Finally, the effect of the phosphoinositide 3­kinase (PI3K)/protein kinase B (Akt) pathway on Cx32­regulated LCSC expansion was investigated. Cx32 was downregulated in LCSCs and HCC tissues, and predicted poor prognosis in patients with HCC. Overexpression of Cx32 in HCCLM3 cells significantly inhibited LCSC expansion, tumorigenesis, and phosphoinositide 3­kinase/protein kinase B (PI3K/Akt) pathway activity. By contrast, silencing of Cx32 in HepG2 cells upregulated expansion of LCSCs and PI3K/Akt pathway activity. Modulating the activity of the PI3K/Akt pathway by SC­79 and LY294002 in HepG2 and HCCLM3 cells, respectively, confirmed that Cx32 could affect the expansion of LCSCs through PI3K/Akt signaling. In conclusion, the present study demonstrated that Cx32 regulated the expansion of LCSCs, and increased expression of Cx32 significantly inhibited the expansion of LCSCs, suggesting that Cx32 may be an optimal target for intervention of HCC.

Isolation and characterisation of dominant acetic acid bacteria and yeast isolated from Kombucha samples at point of sale in New Zealand.

The demand for Kombucha, a sparkling sugared tea beverage fermented by a symbiotic culture of acetic acid bacteria (AAB) and yeast is increasing worldwide. Despite the popularity of the beverage which is mainly due to its perceived health benefits and appealing sensory properties, the microbial composition of the products at the time of consumption is unknown. Such information is important to both manufacturers and consumers. Therefore, this study characterised the dominant AAB and yeast present in six commercial Kombucha samples sold in New Zealand which comprised of three domestic and three imported samples. Acetic acid bacteria and yeast were isolated from the Kombucha samples using glucose yeast extract peptone mannitol (GYPM) and yeast extract glucose chloramphenicol (YGC) media, respectively. Phenotypic and taxonomic identification of AAB and yeast were achieved by morphological and biochemical characterisation, followed by sequence analysis of ribosomal RNA genes (16S rRNA for AAB and 26S rRNA for yeast). Viable AAB and yeast were only found in domestically produced Kombucha samples and not in the imported products. The dominant AAB species were identified as Acetobacter musti and Gluconobacter potus. The yeast isolates belonged to Dekkera bruxelensis, Schizosaccharomyces pombes, Hanseniaspora valbyensis, Brettanomyces anamalus, Pichia kudriavzevii, Starmerella vitis and Saccharomyces cerevisiae. The yeast communities were more complex and variable than the AAB communities in the analysed Kombucha samples.

EM-test for homogeneity in a two-sample problem with a mixture structure.

In many applications such as case-control studies with contaminated controls, or the test of a treatment effect in the presence of nonresponders in biological experiments or clinical trials, a two-sample problem with one of the samples having a mixture structure often arises. Due to the importance and wide applications of scale mixtures and location mixtures, we consider in this paper the case that the component densities differ only in scale parameters and the case that the component densities differ only in location parameters, and further construct an EM-test for the two-sample problem under each case. We show that both the EM-tests possess a chi-squared null limiting distribution. The local power analysis and sample size calculations are also investigated. Finally, the simulation studies and real data analysis demonstrate that the proposed EM-tests have better performance than the existing methods.

[Effects of hydrogen-rich saline on Akt/GSK3ß signaling pathways and cardiac function during myocardial ischemia-reperfusion in rats].

OBJECTIVE: To explore the effects of hydrogen-rich saline on Akt/GSK3ß signaling pathways and cardiac function during myocardial ischemia-reperfusion (I/R) in rats. METHODS: A total of 150 healthy male Sprague-Dawley rats were selected and divided randomly into 5 groups of normal control (I), sham operation (II), myocardial ischemia-reperfusion (III), hydrogen-rich saline (IV) and normal saline group (V) (n = 30 each). Group I had no treatment at all. In group II, anterior descending branch was merely exposed but not ligated. Myocardial I/R was induced by 30-min occlusion of anterior descending branch of left coronary artery followed by 12/24 h reperfusion of Bimbaum. Hydrogen-rich saline 1 ml/100 g were injected intraperitoneally 5 min before reperfusion in group IV. Normal saline 1 ml/100 g was injected intraperitoneally 5 min before reperfusion in group V. The values of ± dp/dt max, left ventricular diastolic pressure (LVDP) and left ventricular systolic pressure (LVSP) during the procedure were recorded by BL-420 biological function experimental system at pre-ischemia, ischemia 30 min, 60 min and 120 min of reperfusion. The animals were sacrificed at 60 min, 120 min of reperfusion and hearts harvested. The pathological changes of myocardial tissue were detected by hematoxylin and eosin staining. And the expressions of Akt and GSK3ß in myocardial tissue were examined by Western blot. RESULTS: Compared with groups I and II, the values of ± dp/dt max, LVDP and LVSP significantly increased. And the expressions of Akt and GSK3ß in myocardial tissue significantly increased in groups III, IV and V. Compared with groups III and V, the values of ± dp/dt max, LVDP and LVSP significantly decreased. And the expressions of Akt and GSK3ß in myocardial tissue significantly decreased in group IV. Compared with T0, the values of ± dp/dt max, LVDP and LVSP significantly decreased at T(1-3) in groups III, IV and V. Compared with T(1), the values of ± dp/dt max, LVDP and LVSP significantly increased at T(2-3) in group IV. Compared with T(2), the expressions of Akt and GSK3ß in myocardial tissue significantly decreased at T(3) in group IV. CONCLUSION: Hydrogen-rich saline can reduce myocardial reperfusion injury and improve heart function. The mechanism may be due to associated with the down-regulated expressions of Akt and GSK3ß in myocardial tissue.

[The application of multi-slice CT and MRI on maxillofacial region soft tissue measurement].

PURPOSE: To evaluate the value of multi-slice CT and MRI on maxillofacial region soft tissue measurement. METHODS: A total of 12 cases of dentofacial orthodontic underwent X-ray photograph, multi-slice CT and MRI scanning. The angle and distance of maxillofacial region soft tissue were measured respectively. All data were analyzed statistically for ANOVA with SPSS11.0 software package. RESULTS: There was no significant difference among the three measurement methods: X-ray photograph, multi-slice CT and MRI(P>0.05). MRI had advantages on depicting hierarchical structure of maxillofacial region, especially soft tissues, while multi-slice CT had advantages on depicting structure of maxillofacial region, both hard and soft tissues. CONCLUSIONS: Multi-slice CT and MRI are useful on maxillofacial region soft tissues measurement. MRI is superior to multi-slice CT and X-ray photograph on maxillofacial region soft tissue measurement.