Vitisin B, a resveratrol tetramer from Vitis thunbergii var. taiwaniana, ameliorates impaired glucose regulations in nicotinamide/streptozotocin-induced type 2 diabetic mice.

Background and aim: In Taiwan, Vitis thunbergii var. taiwaniana (VTT) is used in traditional medicine and as a local tea. VTT rich in resveratrol and resveratrol oligomers have been reported to exhibit anti-obesity and anti-hypertensive activities in animal models; however, no studies have investigated type 2 diabetes mellitus (T2DM) treatments. This study aimed to investigate the anti-T2DM effects of resveratrol tetramers isolated from the VTT in nicotinamide/streptozotocin (STZ)-induced Institute of Cancer Research (ICR) mice. Experimental procedure: The oral glucose tolerance test (OGTT) was used to imitate postprandial blood glucose (BG) regulations in mice by pre-treatment with VTT extracts, resveratrol tetramers of vitisin A, vitisin B, and hopeaphenol 30 min before glucose loads. Vitisin B (50 mg/kg) was administered to treat T2DM-ICR mice once daily for 28 days to investigate its hypoglycemic activity. Results and conclusion: Mice pre-treated with VTT-S-95EE, or vitisin B (100 mg/kg) 30-min before glucose loading showed significant reductions (P < 0.001) in the area under the curve at 120-min (BG-AUC0-120) than those without pre-treatment with VTT-S-95 E E or vitisin B. Vitisin B-treated T2DM mice showed hypoglycemic activities via a reduction in plasma dipeptidyl peptidase (DPP)-IV activities to maintain insulin actions and differed significantly than those of untreated T2DM mice (P < 0.05), and also reduced BG-AUC0-120 and insulin-AUC0-120 in the OGTT.These in vivo results showed that VTT containing vitisin B would be beneficial for developing nutraceuticals and/or functional foods for glycemic control in patients with T2DM, which should be investigated further.

Increasing trend of healthcare-associated infections due to vancomycin-resistant Enterococcus faecium (VRE-fm) paralleling escalating community-acquired VRE-fm infections in a medical center implementing strict contact precautions: An epidemiologic and pathogenic genotype analysis and its implications.

OBJECTIVE: To clarify whether there were clandestine intra-hospital spreads of vancomycin-resistant Enterococcus faecium (VRE-fm) isolates that led to specific strain of VRE lingering in the hospital and/or developing outbreaks that rendered a progressively increasing trend of healthcare-associated infections due to VRE-fm (VRE-fm-HAIs). SETTING: Despite implementing strict contact precautions for hospitalized patients with VRE-fm-infection/colonization, number of VRE-fm-HAIs in a medical centre in southern Taiwan were escalating in 2009-2019, paralleling an increasing trend of community-acquired VRE-fm- infections. METHODS: We analyzed epidemiologic data and genotypes of non-duplicate VRE-fm isolates each grown from a normally sterile site of 89 patients between December 2016 and October 2018; multilocus sequence typing (MLST) and pulse-field gel electrophoresis (PFGE) typing were performed. RESULTS: Totally 13 sequence types (STs) were found, and the 3 leading STs were ST17 (44％), ST78 (37％), and ST18 (6％); 66 pulsotypes were generated by PFGE. Four VRE-fm isolates grouped as ST17/pulsotype S, 2 as ST17/pulsotype AS, 2 as ST17/pulsotype AU, and 3 as ST78/pulsotype V grew from clinical specimens sampled less than one week apart from patients staying at different wards/departments and/or on different floors of the hospital. CONCLUSIONS: Despite possible small transitory clusters of intra-hospital VRE-fm spreads, there was no specific VRE-fm strain lingering in the hospital leading to increasing trend of VRE-fm-HAIs during the study period. Strict contact precautions were able to curb intra-hospital VRE-fm spreads, but unable to curb the increasing trend of VRE-fm-HAIs with the backdrop of progressively increasing VRE-fm-infections/colorizations in the community.

Air Sampling for Fungus around Hospitalized Patients with Coronavirus Disease 2019.

The risk of developing coronavirus disease 2019 (COVID-19)-associated pulmonary aspergillosis (CAPA) depends on factors related to the host, virus, and treatment. However, many hospitals have modified their existing rooms and adjusted airflow to protect healthcare workers from aerosolization, which may increase the risk of Aspergillus exposure. This study aimed to quantitatively investigate airborne fungal levels in negative and slightly negative pressure rooms for COVID-19 patients. The air in neutral pressure rooms in ordinary wards and a liver intensive care unit with high-efficiency particulate air filter was also assessed for comparison. We found the highest airborne fungal burden in recently renovated slightly negative air pressure rooms, and a higher airborne fungal concentration in both areas used to treat COVID-19 patients. The result provided evidence of the potential environmental risk of CAPA by quantitative microbiologic air sampling, which was scarcely addressed in the literature. Enhancing environmental infection control measures to minimize exposure to fungal spores should be considered. However, the clinical implications of a periodic basis to determine indoor airborne fungal levels and further air sterilization in these areas remain to be defined.

A booster dose of Delta × Omicron hybrid mRNA vaccine produced broadly neutralizing antibody against Omicron and other SARS-CoV-2 variants.

BACKGROUND: With the continuous emergence of new SARS-CoV-2 variants that feature increased transmission and immune escape, there is an urgent demand for a better vaccine design that will provide broader neutralizing efficacy. METHODS: We report an mRNA-based vaccine using an engineered "hybrid" receptor binding domain (RBD) that contains all 16 point-mutations shown in the currently prevailing Omicron and Delta variants. RESULTS: A booster dose of hybrid vaccine in mice previously immunized with wild-type RBD vaccine induced high titers of broadly neutralizing antibodies against all tested SARS-CoV-2 variants of concern (VOCs). In naïve mice, hybrid vaccine generated strong Omicron-specific neutralizing antibodies as well as low but significant titers against other VOCs. Hybrid vaccine also elicited CD8+/IFN-γ+ T cell responses against a conserved T cell epitope present in wild type and all VOCs. CONCLUSIONS: These results demonstrate that inclusion of different antigenic mutations from various SARS-CoV-2 variants is a feasible approach to develop cross-protective vaccines.

Epidemiological and Clinical Characteristics, Antifungal Susceptibility, and MLST-Based Genetic Analysis of Cryptococcus Isolates in Southern Taiwan in 2013-2020.

Cryptococcal meningoencephalitis (CM) is a treatable condition, but it leads to excessive morbidity and mortality. We collected 115 non-duplicated Cryptococcus clinical isolates during 2013−2020 in southern Taiwan to perform antifungal susceptibility testing. Multi-locus sequence typing was performed on 96 strains from patients with CM (n = 47) or cryptococcemia (n = 49). In addition, the epidemiological and clinical characteristics of patients with CM during 2013−2020 (n = 47) were compared with those during 2000−2010 (n = 46). During 2013−2020, only one C. neoformans isolate (0.9%) had a fluconazole minimum inhibitory concentration of >8 µg/mL. Amphotericin B (AMB), flucytosine (5FC), and voriconazole were highly active against all C. neoformans/C. gattii isolates. The most common sequence type was ST5. Among these 47 patients with CM, cerebrospinal fluid cryptococcal antigen (CSF CrAg) titer >1024 was a significant predictor of death (odds ratio, 48.33; 95% CI, 5.17−452.06). A standard induction therapy regimen with AMB and 5FC was used for all patients during 2013−2020, but only for 2.2% of patients in 2000−2010. The in-hospital CM mortality rate declined from 39.1% during 2000−2010 to 25.5% during 2013−2020, despite there being significantly younger patients with less CSF CrAg >1024 during 2000−2010. The study provides insight into the genetic epidemiology and antifungal susceptibility of Cryptococcus strains in southern Taiwan. The recommended antifungal drugs, AMB, 5FC, and FCZ, remained active against most of the Cryptococcus strains. Early diagnosis of patients with CM and adherence to the clinical practice guidelines cannot be overemphasized to improve the outcomes of patients with CM.

Rapid generation of mouse model for emerging infectious disease with the case of severe COVID-19.

Since the pandemic of COVID-19 has intensely struck human society, small animal model for this infectious disease is in urgent need for basic and pharmaceutical research. Although several COVID-19 animal models have been identified, many of them show either minimal or inadequate pathophysiology after SARS-CoV-2 challenge. Here, we describe a new and versatile strategy to rapidly establish a mouse model for emerging infectious diseases in one month by multi-route, multi-serotype transduction with recombinant adeno-associated virus (AAV) vectors expressing viral receptor. In this study, the proposed approach enables profound and enduring systemic expression of SARS-CoV-2-receptor hACE2 in wild-type mice and renders them vulnerable to SARS-CoV-2 infection. Upon virus challenge, generated AAV/hACE2 mice showed pathophysiology closely mimicking the patients with severe COVID-19. The efficacy of a novel therapeutic antibody cocktail RBD-chAbs for COVID-19 was tested and confirmed by using this AAV/hACE2 mouse model, further demonstrating its successful application in drug development.

CpG-adjuvanted stable prefusion SARS-CoV-2 spike protein protected hamsters from SARS-CoV-2 challenge.

The COVID-19 pandemic presents an unprecedented challenge to global public health. Rapid development and deployment of safe and effective vaccines are imperative to control the pandemic. In the current study, we applied our adjuvanted stable prefusion SARS-CoV-2 spike (S-2P)-based vaccine, MVC-COV1901, to hamster models to demonstrate immunogenicity and protection from virus challenge. Golden Syrian hamsters immunized intramuscularly with two injections of 1 µg or 5 µg of S-2P adjuvanted with CpG 1018 and aluminum hydroxide (alum) were challenged intranasally with SARS-CoV-2. Prior to virus challenge, the vaccine induced high levels of neutralizing antibodies with 10,000-fold higher IgG level and an average of 50-fold higher pseudovirus neutralizing titers in either dose groups than vehicle or adjuvant control groups. Six days after infection, vaccinated hamsters did not display any weight loss associated with infection and had significantly reduced lung pathology and most importantly, lung viral load levels were reduced to lower than detection limit compared to unvaccinated animals. Vaccination with either 1 µg or 5 µg of adjuvanted S-2P produced comparable immunogenicity and protection from infection. This study builds upon our previous results to support the clinical development of MVC-COV1901 as a safe, highly immunogenic, and protective COVID-19 vaccine.

Azole resistance in Aspergillus species in Southern Taiwan: An epidemiological surveillance study.

Poor clinical outcomes for invasive aspergillosis are associated with antifungal resistance. Performing antifungal susceptibility tests on clinically relevant Aspergillus isolates from patients and environmental regions with known azole resistance is recommended. The aim of the study was to assess the presence of azole resistance in clinical Aspergillus spp. isolates and those from hospital environments and farmlands within a 40 km radius of the hospital. Clinical Aspergillus spp. isolates were cultured, as well as environmental Aspergillus spp. isolates obtained from air samples. Samples were subcultured in azole-containing agar plates. Isolates with a positive screening test were subjected to YeastOne methods to determine their minimum inhibitory concentrations of antifungals. Resistance mechanisms were investigated in the azole-resistant Aspergillus spp. isolates. No azole-resistant clinical or environmental A flavus, A oryaze, A niger or A terreus isolates were found in the present study. All A fumigatus clinical isolates were azole-susceptible. Seven A fumigatus environmental isolates were associated with cyp51A mutations, including two that harboured TR34 /L98H mutations with S297T/F495I substitutions, two with TR34 /L98H mutations and three with TR46 /Y121F/T289A mutations. One of these isolates was collected from farmland, one was from A ward and five were from B ward. The proportion of azole-resistant A fumigatus was 10.2% (6/59) and 3.2% (1/31) in the hospital environments and the farmlands near the hospital, respectively. The results showed that azole-resistant A fumigatus existed within hospital environments. This emphasises the importance of periodic surveillance in hospital environments and monitoring for the emergence of azole-resistant A fumigatus clinical isolates.

5-Episinuleptolide Decreases the Expression of the Extracellular Matrix in Early Biofilm Formation of Multi-Drug Resistant Acinetobacter baumannii.

Nosocomial infections and increasing multi-drug resistance caused by Acinetobacter baumannii have been recognized as emerging problems worldwide. Moreover, A. baumannii is able to colonize various abiotic materials and medical devices, making it difficult to eradicate and leading to ventilator-associated pneumonia, and bacteremia. Development of novel molecules that inhibit bacterial biofilm formation may be an alternative prophylactic option for the treatment of biofilm-associated A. baumannii infections. Marine environments, which are unlike their terrestrial counterparts, harbor an abundant biodiversity of marine organisms that produce novel bioactive natural products with pharmaceutical potential. In this study, we identified 5-episinuleptolide, which was isolated from Sinularia leptoclados, as an inhibitor of biofilm formation in ATCC 19606 and three multi-drug resistant A. baumannii strains. In addition, the anti-biofilm activities of 5-episinuleptolide were observed for Gram-negative bacteria but not for Gram-positive bacteria, indicating that the inhibition mechanism of 5-episinuleptolide is effective against only Gram-negative bacteria. The mechanism of biofilm inhibition was demonstrated to correlate to decreased gene expression from the pgaABCD locus, which encodes the extracellular polysaccharide poly-ß-(1,6)-N-acetylglucosamine (PNAG). Scanning electron microscopy (SEM) indicated that extracellular matrix of the biofilm was dramatically decreased by treatment with 5-episinuleptolide. Our study showed potentially synergistic activity of combination therapy with 5-episinuleptolide and levofloxacin against biofilm formation and biofilm cells. These data indicate that inhibition of biofilm formation via 5-episinuleptolide may represent another prophylactic option for solving the persistent problem of biofilm-associated A. baumannii infections.

Synthesized Peptides from Yam Dioscorin Hydrolysis in Silico Exhibit Dipeptidyl Peptidase-IV Inhibitory Activities and Oral Glucose Tolerance Improvements in Normal Mice.

RRDY, RL, and DPF were the top 3 of 21 peptides for inhibitions against dipeptidyl peptidase-IV (DPP-IV) from the pepsin hydrolysis of yam dioscorin in silico and were further investigated in a proof-of-concept study in normal ICR mice for regulating glucose metabolism by the oral glucose tolerance test (OGTT). The sample or sitagliptin (positive control) was orally administered by a feeding gauge; 30 min later, the glucose loads (2.5 g/kg) were performed. RRDY, yam dioscorin, or sitagliptin preload, but not DPF, lowered the area under the curve (AUC0-120) of blood glucose and DPP-IV activity and elevated the AUC0-120 of blood insulin, which showed significant differences compared to control (P < 0.05 or 0.001). These results suggested that RRDY and yam dioscorin might be beneficial in glycemic control in normal mice and need further investigations in diabetic animal models.

Protective Effects of Minor Components of Curcuminoids on Hydrogen Peroxide-Treated Human HaCaT Keratinocytes.

Hydrogen peroxide, one of the reactive oxygen species (ROS), can cause intracellular oxidative stress associated with skin aging and/or photoaging. Curcumin, a polyphenol in turmeric, has been reported to exhibit biological activity. In this study, five naturally occurring curcuminoids [curcumin, demethoxycurcumin (DMC), bisdemethoxycurcumin (BDMC), monohydroxy-DMC, and monohydroxy-BDMC] were used to investigate their protective roles against hydrogen peroxide-induced oxidative stress in the immortalized human keratinocyte cell lines (HaCaT cells). These five curcuminoids at 10 µM, but not at 5 µM, were shown to exhibit cytotoxicities toward HaCaT keratinocytes. Therefore, a 5 µM concentration of the five curcuminoids was selected for further investigations. Cells were pretreated with or without curcuminoids for 2.5 h before 24-h hydrogen peroxide (150 µM) treatments. Pretreatments with the minor components monohydroxy-DMC or monohydroxy-BDMC, but not curcumin, DMC, and BDMC, showed protective activity, elevating cell viability compared to cells with direct hydrogen peroxide treatments. Pretreatments with monohydroxy-DMC and monohydroxy-BDMC showed the best protective effects, reducing apoptotic cell populations and intracellular ROS, as demonstrated by flow cytometry, as well as reducing the changes of the mitochondrial membrane potential compared to cells with direct hydrogen peroxide treatments. The pretreatments with monohydroxy-DMC and monohydroxy-BDMC reduced c-jun and c-fos mRNA expression and p53 tumor suppressor protein expression and increased HO-1 protein expression and glutathione peroxidase (GPx) activity, respectively, compared to cells with direct hydrogen peroxide treatments. The five curcuminoids exhibited similar hydrogen peroxide-scavenging activity in vitro. It was proposed that monohydroxy-DMC and monohydroxy-BDMC could induce antioxidant defense systems better than curcumin, DMC, or BDMC could against hydrogen peroxide-induced oxidative stress and apoptosis of HaCaT keratinocytes and that they may have potential as ingredients in antiaging cosmetics for skin care.

Vitis thunbergii var. taiwaniana Extracts and Purified Compounds Ameliorate Obesity in High-Fat Diet-Induced Obese Mice.

The increasing prevalence of obesity continues to gain more attention worldwide. In this study, diet-induced obese mice were used to evaluate the antiobesity effects of extracts, fractions, and purified compounds from Vitis thunbergii var. taiwaniana (VTT). The C57BL/6J mice were fed a 5-week high-fat diet (HF) concurrently with ethanol extracts (Et-ext, 80 mg/kg) from roots (R), stems (S), and leaves (L) by oral gavage daily. Only R-Et-ext interventions showed significant weight reduction in mice compared with those in the HF group; however, mouse plasma contents of total cholesterols (TC), total triglycerides (TG) and low-density lipoproteins (LDL) of all three Et-ext intervened groups showed significant reductions compared with those in the HF group. Furthermore, intervention with the ethyl acetate-partitioned fraction (EA-fra, 60 mg/kg) from R-Et-ext but not the n-butanol-partitioned fraction or water fraction from R-Et-ext showed significant weight reduction in mice compared with those in the HF group. The same molecular weights of three resveratrol tetramers, (+)-hopeaphenol, (+)-vitisin A, and (-)-vitisin B, were isolated from the EA-fra of VTT-R. The (+)-vitisin A and fenofibrate (25 mg/kg) but not the (+)-hopeaphenol and (-)-vitisin B interventions showed significant weight reduction in mice compared with those in the HF group. The total feed intake among the HF groups with or without interventions showed no significant differences. The mouse plasma contents of TC, TG, LDL, free fatty acid, and plasma lipase activity of the three resveratrol tetramer-intervened groups showed reductions in the mice compared with those in the HF group. It was proposed that the lipase inhibitory activities of VTT extracts and purified resveratrol tetramers might contribute in part to the antiobesity effect, and these results suggested that VTT may be developed as functional food for achieving antiobesity objectives and requires further investigation.

Anti-α-glucosidase and Anti-dipeptidyl Peptidase-IV Activities of Extracts and Purified Compounds from Vitis thunbergii var. taiwaniana.

Ethanol extracts (Et) from the stem (S) and leaf (L) of Vitis thunbergii var. taiwaniana (VTT) were used to investigate yeast α-glucosidase and porcine kidney dipeptidyl peptidase-IV (DPP-IV) inhibitory activities. Both VTT-Et showed complete α-glucosidase inhibition at 0.1 mg/mL; VTT-S-Et and VTT-L-Et showed 26 and 11% DPP-IV inhibition, respectively, at 0.5 mg/mL. The VTT-Et interventions (20 and 50 mg/kg) resulted in improvements in impaired glucose tolerance of diet-induced obese rats. (+)-Hopeaphenol, (+)-vitisin A, and (-)-vitisin B were isolated from the ethyl acetate fractions of S-Et and showed yeast α-glucosidase inhibition (IC50 = 18.30, 1.22, and 1.02 µM) and porcine kidney DPP-IV inhibition (IC50 = 401, 90.75, and 15.3 µM) compared to acarbose (6.39 mM) and sitagliptin (47.35 nM), respectively. Both (+)-vitisin A and (-)-vitisin B showed mixed noncompetitive inhibition against yeast α-glucosidase and porcine kidney DPP-IV, respectively. These results proposed that VTT extracts might through inhibitions against α-glucosidase and DPP-IV improve the impaired glucose tolerance in diet-induced obese rats.

Effects of yam dioscorin interventions on improvements of the metabolic syndrome in high-fat diet-induced obese rats.

BACKGROUND: The metabolic syndrome (MS) is termed a cluster of multiple metabolic risk criteria which is positively correlated with cardiovascular disease and type 2 diabetes mellitus (DM). Yam dioscorins have been reported to exhibit biological activities, however, little is known their preventive effects on the MS. Therefore, a high-fat (HF) diet was used to induce Wistar rat obesity and then yam dioscorin (50 mg/kg, dio50) was intervened daily concurrent HF diet (HF diet + dio50) for five weeks to check the changes of weights of body and tissues, blood pressures, and impaired glucose tolerances. The in vitro peptic hydrolysates of dioscorin with molecular mass between 3 kDa and 10 kDa and less than 3 kDa were used to determine dipeptidyl peptidase IV (DPP IV) inhibitory activities which DPP IV inhibitor has been reported to prevent and treat type 2 DM. RESULTS: There were no significant difference in body weights, feed intakes, feed conversion, and weights of adipose tissues of obese rats in groups of HF and (HF diet + dio50). However, the systolic blood pressures in obese rats of 2-, 3- and 4-week dioscorin interventions were showed significantly lower (P < 0.05) compared to the HF group. The dioscorin intervention (HF+ dio50) was showed significantly different (P < 0.05) and improved the impaired glucose tolerances compared to HF group in obese rats by the oral glucose tolerance tests. It was also found that the fraction with different molecular mass of dioscorin peptic hydrolysates (5 mg/ml) showed inhibitory activities against DPP IV using sitagliptin phosphate as positive controls. CONCLUSIONS: Yam dioscorins exhibit improved MS activities in obese rats which the related mechanisms may need further investigations.

Effects of hot-water extracts from Ganoderma lucidum residues and solid-state fermentation residues on prebiotic and immune-stimulatory activities in vitro and the powdered residues used as broiler feed additives in vivo.

BACKGROUND: Large amounts of Ganoderma lucidum (GL) commercial products are provided in the worldwide market such as powders, tea bags, or capsules as dietary supplements which contained triterpenoids and/or polysaccharides. Therefore, it was estimated that several thousand tons of GL residues (GLR) are produced and discarded. For recycling uses, the aim of this study was to evaluate the benefits of two hot-water extracts from GLR (HWP_GLR) and solid-state fermentation GLR inoculated with GL mycelia (HWP_GLRF) on the growths of Lactobacillus rhamnosus and Bifidobacterium longum. The RAW264.7 cells were used to investigate the effects of HWP_GLR and HWP_GLRF on nitric oxide productions, phagocytic activities against FITC-labeled E. coli, and to lower lipopolysaccharide (LPS)-binding capacities. The powders of GLR and GLRF were used as additives in the commercial feeds for feeding broiler chicks in vivo to evaluate the immune-stimulatory and prebiotic activities. RESULTS: HWP_GLR and HWP_GLRF with molecular size 5 to 8 kDa were showed to stimulate growths of L. rhamnosus and B. longum. It was found that in the presence of polymyxin B HWP_GLR and HWP_GLRF could stimulate nitric oxide productions, elevate phagocytic activities against FITC-labeled E. coli, and to lower lipopolysaccharide-binding capacities in RAW264.7 cells. The broiler chicks were selected for feedings in vivo. The 1-day-old chicks were fed commercial feeds for 1 week, and then were fed without or with 4 or 8 % of GLR and GLRF additives for 3 weeks. There was no significant weight difference among feeding groups. However, the phagocytosis and natural killer cytotoxicity in the peripheral bloods, and prebiotic activities of bifidobacteria in feces of GLR and/or GLRF groups were significantly different compared to the control (P < 0.05). CONCLUSIONS: The GLR, GLRF, and their hot-water extracts with beneficial activities could be processed as feed additives which could increase the waste-recycling.

Glycine hydroxamate inhibits tyrosinase activity and melanin contents through downregulating cAMP/PKA signaling pathways.

Among the eight amino acid hydroxamates tested, Glycine hydroxamate (GH) was the best inhibitor of mushroom tyrosinase (TYR). With L-tyrosine as substrate, the GH inhibition of the monophenolase activity of the mushroom TYR was noncompetitive. GH decreased not only TYR protein expression, but also melanin content, tyrosinase-related protein (TRP)-1, TRP-2, and microphthalmia-associated transcription factor (MITF) expression in B16F10 melanoma cells while in the presence of α-melanocyte-stimulating hormone (α-MSH). GH also significantly decreased the isobutylmethylxanthine (IBMX)-induced increase in melanin content, which was not prevented by the ERK inhibitor PD98059. These results suggest GH has the potential for use in cosmetic hypopigmentation.

The contribution of antibiotic resistance mechanisms in clinical Burkholderia cepacia complex isolates: an emphasis on efflux pump activity.

Due to the limited information of the contribution of various antibiotic resistance mechanisms in clinical Burkholderia cepacia complex isolates, Antibiotic resistance mechanisms, including integron analysis, identification of quinolone resistance-determining region mutations, measurement of efflux pump activity, and sequence analysis of efflux pump regulators, were investigated in 66 clinical B. cepacia complex isolates. Species were identified via recA-RFLP and MALDI-TOF. Four genomovars were identified by recA-RFLP. B. cenocepacia (genomovar III) was the most prevalent genomovar (90.1%). Most isolates (60/66, 90.9%) were correctly identified by MALDI-TOF analysis. Clonal relatedness determined by PFGE analysis revealed 30 pulsotypes, including two major pulsotypes that comprised 22.7% and 18.2% of the isolates, respectively. Seventeen (25.8%) isolates harboured class 1 integron with various combinations of resistance genes. Among six levofloxacin-resistant isolates, five had single-base substitutions in the gyrA gene and three demonstrated efflux pump activities. Among the 42 isolates exhibiting resistance to at least one antimicrobial agent, 94.4% ceftazidime-resistant isolates (17/18) and 72.7% chloramphenicol-resistant isolates (16/22) demonstrated efflux pump activity. Quantitation of efflux pump RNA level and sequence analysis revealed that over-expression of the RND-3 efflux pump was attributable to specific mutations in the RND-3 efflux pump regulator gene. In conclusion, high-level expression of efflux pumps is prevalent in B. cepacia complex isolates. Mutations in the RND-3 efflux pump regulator gene are the major cause of efflux pump activity, resulting in the resistance to antibiotics in clinical B. cepacia complex isolates.

Asn-Trp dipeptides improve the oxidative stress and learning dysfunctions in D-galactose-induced BALB/c mice.

The oral administration of Asn-Trp (NW) or carnosine (ß-alanyl-L-histidine) dipeptides to D-galactose (Gal)-induced BALB/c mice was used to evaluate antioxidant activities in vivo. D-Galactose (Gal) was subcutaneously injected into the dorsal necks of mice daily for eight weeks to induce oxidative stress (Gal group). From the beginning of the fifth week, groups of NW10, NW40 (10 or 40 mg NW kg(-1)) or carnosine40 (40 mg carnosine kg(-1)) were administered orally concurrent Gal injection until the end of studies. It was found that the malondialdehyde (MDA) contents in these intervention groups were much lower than the Gal group. The mice in the NW40 group showed significant improvements compared to the Gal group in a reference memory task and probe trial test evaluated by Morris water maze. Mice in the intervention groups showed higher GSH levels and oxygen radical antioxidant capacity activities and lower MDA levels in the brain or liver tissues compared to the Gal group. The levels of advanced glycation end-products, including N(ε)-(carboxymethyl)lysine (CML) and argpyrimidine, in the brain tissues of the NW40 interventions are significantly lower compared to the Gal group. These results suggest that NW may be useful in developing functional foods for antioxidant and anti-aging purposes.

Effects of yam tuber protein, dioscorin, on attenuating oxidative status and learning dysfunction in d-galactose-induced BALB/c mice.

The yam tuber is a traditional Chinese medicine used in long-term treatment as a juvenescent substance. The purified yam tuber's major water-soluble protein, dioscorin, and its protease hydrolysates have been reported to have several biological activities. In this study, d-galactose (Gal) was subcutaneously injected into the dorsal necks of BALB/c mice daily for 10weeks (Gal group) to induce oxidative stress. By the fifth week, 20 or 80mg dioscorin/kg was orally administered daily combined with a daily Gal injection until the end of the study. The plasma malondialdehyde (MDA) level and advanced glycation end-products obtained after dioscorin oral administrations were lower compared to the Gal group. In addition, the latency and swimming distance in the mice that received dioscorin administration were significantly improved compared to the Gal group in the Morris water maze. Dioscorin administration resulted in higher GSH levels and oxygen radical antioxidant capacity (ORAC) activity and lower MDA and inducible nitric oxide synthase (iNOS) levels in the brain compared to mice in the Gal group. These elevated antioxidant activities following oral administration of yam dioscorin in vivo may reflect traditional juvenescent uses with the potential for anti-aging treatments.

Antioxidant and antiglycation activities of the synthesised dipeptide, Asn-Trp, derived from computer-aided simulation of yam dioscorin hydrolysis and its analogue, Gln-Trp.

Previous studies have shown that the Trp residue contributes to a high oxygen radical absorbance capacity (ORAC). Therefore, in this study, a Trp-containing dipeptide derived from a computer-aided simulation of pepsin hydrolysis of the yam tuber, dioscorin-namely, Asn-Trp (NW), and its analogue, Gln-Trp (QW)-were synthesised to compare their antioxidant and antiglycation activities with carnosine, homocarnosine, or glutathione (GSH). The antioxidant assays included hydroxyl radical-scavenging activity, anti-AAPH-induced hemolysis, and ORAC activity. NW had a significantly higher antioxidant activity than had QW and performed much better than carnosine, homocarnosine, or GSH. Using bovine serum albumin (BSA)/galactose or BSA/glucose as experimental models, NW had better antiglycation effects than had QW, as detected by an anti-N(ε)-(carboxymethyl)lysine (anti-CML) antibody. Moreover, NW and QW (50-200 µM) showed protection against methylglyoxal-induced cell deaths in human umbilical vein endothelial cells. These results suggest that NW, derived from computer-aided simulation of dioscorin hydrolysis, exhibits antioxidant and antiglycation activities, which thus shows the benefits of the yam tuber as an antioxidant-rich food.