The organic–inorganic composite membranes are prepared by inserting poly(styrene sulfonate)-grafted silica particles into a polymer matrix of sulfonated poly(arylene ether sulfone) copolymer. The ...first step consisted in using atom transfer radical polymerization method to prepare surface-modified silica particles grafted with sodium 4-styrenesulfonate, referred to as PSS-g-SiO
2. Ion exchange capacities up to 2.4 meq/g are obtained for these modified silica particles. In a second step, a sulfonated poly(arylene ether sulfone) copolymer is synthesized via nucleophilic step polymerization of sulfonated 4,4′-dichlorodiphenyl sulfone, 4,4′-dichlorodiphenyl sulfone and phenolphthalin monomers in the presence of potassium carbonate. The copolymer is blended with various amounts of silica particles to form organic–inorganic composite membranes. Esterification reaction is carried out between silica particles and the sulfonated polymer chains by thermal treatment in the presence of sodium hypophosphite, which catalyzed the esterification reaction. The water uptake, proton conductivity, and thermal decomposition temperature of the membranes are measured. All composite membranes show better water uptake and proton conductivity than the unmodified membrane. Moreover, the membranes are tested in a commercial single cell at 80 °C and 120 °C in humidified H
2/air under different relative humidity conditions. The composite membrane containing 10%(w/w) of PSS-g-SiO
2 particles, which have ester bonds between polymer chains and silica particles, showed the best performance of 690 mA cm
−2 at 0.6 V, 120 °C and 30 %RH, even higher than the commercial Nafion
® 112 membrane.
► Composite membranes were prepared for high temperature (>100 °C) PEMFCs. ► A poly(arylene ether sulfone) and poly(styrene sulfonate)-grafted silica were used. ► The ester structures of the composite membranes allow higher dimensional stability. ► Composite membrane with 10% silica showed better performance than Nafion 112 at 120 °C.
Lipid accumulation in vascular endothelial cells may play an important role in the pathogenesis of atherosclerosis in obese subjects. We showed previously that alpha-lipoic acid (ALA) activates ...AMP-activated protein kinase (AMPK) and reduces lipid accumulation in skeletal muscle of obese rats. Here, we investigated whether ALA improves endothelial dysfunction in obese rats by activating AMPK in endothelial cells.
Endothelium-dependent vascular relaxation was impaired, and the number of apoptotic endothelial cells was higher in the aorta of obese rats compared with control rats. In addition, triglyceride and lipid peroxide levels were higher, and NO synthesis was lower. Administration of ALA improved all of these abnormalities. AMPK activity was lower in aortic endothelium of obese rats, and ALA normalized it. Incubation of human aortic endothelial cells with ALA activated AMPK and protected cells from linoleic acid-induced apoptosis. Dominant-negative AMPK inhibited the antiapoptotic effects of ALA.
Reduced AMPK activation may play an important role in the genesis of endothelial dysfunction in obese rats. ALA improves vascular dysfunction by normalizing lipid metabolism and activating AMPK in endothelial cells.
Reactive oxygen species (ROS) are implicated in reperfusion injury after transient focal cerebral ischemia. The antioxidant enzyme Cu,Zn-superoxide dismutase (SOD) is one of the major means by which ...cells counteract the deleterious effects of ROS after ischemia. Recently, we reported that denatured Tat-SOD fusion protein is transduced into cells and skin tissue. Moreover, PEP-1 peptide, which has 21 amino acid residues, is a known carrier peptide that delivers full-length native proteins in vitro and in vivo. In the present study, we investigated the protective effects of PEP-1-SOD fusion protein after ischemic insult. A human SOD gene was fused with PEP-1 peptide in a bacterial expression vector to produce a genetic in-frame PEP-1-SOD fusion protein. The expressed and purified fusion proteins were efficiently transduced both in vitro and in vivo with a native protein structure. Immunohistochemical analysis revealed that PEP-1-SOD injected intraperitoneally (i.p.) into mice can have access into brain neurons. When i.p.-injected into gerbils, PEP-1-SOD fusion proteins prevented neuronal cell death in the hippocampus caused by transient forebrain ischemia. These results suggest that the biologically active intact forms of PEP-1-SOD provide a more efficient strategy for therapeutic delivery in various human diseases related to this antioxidant enzyme or to ROS, including stroke.
White spot syndrome virus (WSSV) is a virulent pathogen known to affect penaeid shrimp. It has a bacilliform morphology and a tail-like appendage at one end. The virus particle consists of at least ...four major proteins. VP28 and VP19 reside in the envelope, while VP26 and VP24 are present in the nucleocapsid. Truncated VP28 (TrVP28) gene was fused to a truncated VP19 (TrVP19) to form TrVP28:19. This together with TrVP28, TrVP24, and TrVP26 were expressed in
Escherichia coli. The panel of resulting recombinant proteins was immunoblotted with serum from rabbit anti-glutathione
S-transferase (GST), rabbit anti-WSSV, and normal rabbit serum. TrVP28:19 immunoreacted strongly with rabbit anti-WSSV. When TrVP28:19 was used as an antigen, dramatically increased titres against it were obtained when compared to other antigens for the production of egg yolk antibodies (IgY). The fusion protein was used as an immunogen with chickens. Shrimp used in WSSV neutralization assays was
P. chinensis. Shrimp treated with 0.01 mg/10 μl of IgY exhibited a survival rate of 50% at day 15 post-challenge with WSSV while those treated with 0.1 and 0.5 mg/μl exhibited survival rates of 85% and 83%, respectively. The results showed that WSSV can be neutralized by the IgY against TrVP28:19 and that it has potential for immunotherapeutic application to prevent WSSV infection in
P. chinensis.
Aims: Among 365 Escherichia coli isolated in 2003, 31 cefotaxime‐resistant isolates were obtained from clinical specimens taken from adults hospitalized in Busan, Korea. Six extended‐spectrum ...β‐lactamase (ESBL)‐producing isolates were investigated further to determine the mechanism of resistance.
Methods and Results: These isolates were analysed by antibiotic susceptibility testing, pI determination, plasmid profiles, transconjugation test, PCR‐restriction fragment length polymorphism (RFLP), enterobacterial repetitive consensus (ERIC)‐PCR and DNA sequencing. All six of these isolates were found to contain the CTX‐M‐type ESBL genes. Five clinical isolates and their transconjugants produced CTX‐M‐3. One clinical isolate (K17391) and its transconjugant (trcK17391) produced CTX‐M‐15. Five clinical isolates also produced another TEM‐1. One clinical isolate (K12776) also contained another TEM‐52. CTX‐M‐3 ESBL gene was responsible for the resistance to piperacillin, cephalothin, cefotaxime, cefepime and aztreonam. CTX‐M‐15 or TEM‐52 was especially responsible for the resistance to ceftazidime.
Conclusions: These results appear to represent the in vivo evolution of CTX‐M‐type β‐lactamase genes (blaCTX‐M‐3 → blaCTX‐M‐15) under the selective pressure of antimicrobial therapy (especially ceftazidime). PCR‐RFLP is a reliable method to discriminate CTX‐M‐15 gene from CTX‐M‐3 gene. ERIC‐PCR analysis revealed that dissemination of CTX‐M‐3 was not due to a clonal outbreak of a resistant strain but to the intra‐species spread of resistance to piperacillin, cephalothin, cefotaxime, cefepime and aztreonam in Korea.
Significance and Impact of the Study: This is the first report of the occurrence of CTX‐M‐1 cluster ESBLs in Korea. A more comprehensive survey of these ESBL types from Korea is urgently needed because of the in vivo evolution of CTX‐M‐15 from CTX‐M‐3. The emergence of these CTX‐M‐type ESBLs suggests that diagnostic laboratories should screen for ESBLs with ceftazidime as well as cefotaxime; they should still perform clavulanate synergy tests on resistant isolates.
Purpose The purpose of the present study was to determine whether there was a correlation between basic physical fitness and pulmonary function in Korean school students, to present an alternative ...method for improving their pulmonary function. Subjects and Methods Two hundred forty healthy students aged 6–17 years performed physical fitness tests of hand-grip strength, sit and reach, Sargent jump, single leg stance, and pulmonary function tests of forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) using a Quark PFT. Results Muscle strength and power of boys improved in the late period of elementary school and middle school. Muscle strength of girls improved in the late period of elementary school. Analysis of factors affecting pulmonary function revealed that height, weight, BMI, and body fat significantly correlated with spirometric parameters. Right hand-grip strength, left hand-grip strength, and Sargent jump also significantly correlated with FVC and FEV1. Conclusion In order to improve the pulmonary function of children and adolescents, aerobic exercise and an exercise program to increase muscle strength and power is needed, and it should start in the late period of elementary school when muscle strength and power are rapidly increasing.
Abstract Background Many types of stem cells have been widely used for the treatment of liver diseases. The therapeutic effect of stem cells is predominantly based on the immune regulatory properties ...of these cells. Methods We isolated human liver stem cells (HLSCs), which are considered intrahepatic stem cells, and examined their suppression of T-cell proliferation induced by phytohemagglutinin. Results HLSCs inhibited phytohemagglutinin-induced T-cell proliferation not only in direct co-culture but also in indirect co-culture in a cell number–dependent manner. That is, T-cell proliferation was substantially inhibited by cell-to-cell contact regardless of soluble factor(s). B7-H1, a co-inhibitory molecule that relies on cell-to-cell contact, was found to be constitutively expressed at low levels on HLSCs. Furthermore, its expression was upregulated moderately by tumor necrosis factor-α and dramatically by interferon-γ. Conclusions These results suggest that HLSCs would have therapeutic effects through T-cell suppression in acute liver diseases.
Purpose This study investigated the effects of combined open kinetic chain and closed kinetic chain training using pulley exercise machines on muscle strength, anaerobic power, and blood levels of ...angiogenesis factors. Subjects and Methods Twenty male university students were equally divided between control and pulley training groups. The pulley-training group underwent 8 weeks of combined training. Open kinetic chain training consisted of 2 sets of 10 repetitions at 60% of one repetition maximum; closed kinetic chain training consisted of 2 sets of 10 repetitions of resistance exercise using the subject’s own body weight. Isokinetic strength (trunk and knee), anaerobic power, vascular endothelial growth factor, angiopoietin-1, angiopoietin-2, and follistatin were analyzed. Results After 8 weeks, flexor and extensor muscle strength significantly increased in the trunk and knee; average and peak power also increased significantly. Angiopoietin 1 increased 25% in the control group and 48% in the pulley training group; vascular endothelial growth factor and follistatin increased significantly in the pulley-training group after 8 weeks. Conclusion Eight weeks of combined training using pulley exercise machines effectively increased biochemical factors related to muscle growth, as well as muscle strength in the trunk and knees.
Abstract Although several studies have addressed the engraftment of stem cells into the liver, the exact mechanisms in vivo remain unclear. In this study, we investigated the effects of soluble ...factors on cell migration using purified, expanded human liver stem cells (HLSCs) obtained from a pediatric liver resection. Using a in vitro transwell migration assay, we evaluated the migratory capacity of HLSCs under the influence of the cytokines tumor necross factor- TNF-α, interleukin IL-6, and interferon (IFN)-γ or the growth factors vascular endothelial growth factor VEGF, basic fibroblast growth factor bFGF, and hepatocyte growth factor HGF, which are known to be highly secreted during liver injury. We also evaluated the migratory capacity indirectly influenced by cryopreserved human hepatocytes. The migration across the transwell membrane was promoted by VEGF, bFGF, TNF-α, IFN-γ, or hepatocytes. The cryopreserved human hepatocytes especially induced significant migration. These results suggested the presence of unidentified soluble factors from hepatocytes. This experiment described a reliable system for quantitative migration studies to broaden our understanding of the directional nature of cell migration.
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