Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
391
result(s) for
"Sun Tzu"
Sort by:
Process of inducing pores in membranes by melittin
Melittin is a prototype of the ubiquitous antimicrobial peptides that induce pores in membranes. It is commonly used as a molecular device for membrane permeabilization. Even at concentrations in the nanomolar range, melittin can induce transient pores that allow transmembrane conduction of atomic ions but not leakage of glucose or larger molecules. At micromolar concentrations, melittin induces stable pores allowing transmembrane leakage of molecules up to tens of kilodaltons, corresponding to its antimicrobial activities. Despite extensive studies, aspects of the molecular mechanism for pore formation remain unclear. To clarify the mechanism, one must know the states of the melittin-bound membrane before and after the process. By correlating experiments using giant unilamellar vesicles with those of peptide-lipid multilayers, we found that melittin bound on the vesicle translocated and redistributed to both sides of the membrane before the formation of stable pores. Furthermore, stable pores are formed only above a critical peptide-to-lipid ratio. The initial states for transient and stable pores are different, which implies different mechanisms at low and high peptide concentrations. To determine the lipidie structure of the pore, the pores in peptide-lipid multilayers were induced to form a lattice and examined by anomalous X-ray diffraction. The electron density distribution of lipid labels shows that the pore is formed by merging of two interfaces through a hole. The molecular property of melittin is such that it adsorbs strongly to the bilayer interface. Pore formation can be viewed as the bilayer adopting a lipid configuration to accommodate its excessive interfacial area.
Journal Article
Effects of blending wheatgrass juice on enhancing phenolic compounds and antioxidant activities of traditional kombucha beverage
Traditional kombucha is a fermented black tea extract and sugar. Sweetened black tea (10% w/v) and wheatgrass juice (WGJ) were mixed in various ratios and used as fermentation substrate for enhancing phenolic compounds and antioxidant activity. Starter, comprising of yeast (Dekkera bruxellensis) and acetic acid bacteria (Gluconacetobacter rhaeticus and Gluconobacter roseus), was inoculated at 20% (v/v), and fermented statically at 29 ± 1°C for 12 days. The results showed that the total phenolic and flavonoid contents and antioxidant activity of the modified kombucha were higher than those of traditional preparations. All WGJ-blended kombucha preparations were characterized as having higher concentrations of various phenolic compounds such as gallic acid, catechin, caffeic acid, ferulic acid, rutin, and chlorogenic acid as compared to traditional ones. Addition of WGJ resulted in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging ability of kombucha being > 90%, while the oxygen radical absorbance capacity increased from 5.0 μmol trolox equivalents/mL to 12.8 μmol trolox equivalents/mL as the ratio of WGJ increased from 0% to 67% (v/v). The highest antioxidant activity was obtained using a 1:1 (v/v) black tea decoction to WGJ ratio and 3 days of fermentation, producing various types of phenolic acids. These results suggest that intake of fermented black tea enhanced with wheatgrass juice is advantageous over traditional kombucha formulas in terms of providing various complementary phenolics and might have more potential to reduce oxidative stress.
Journal Article
Effects of Camphorquinone on Cytotoxicity, Cell Cycle Regulation and Prostaglandin E2 Production of Dental Pulp Cells: Role of ROS, ATM/Chk2, MEK/ERK and Hemeoxygenase-1
Camphorquinone (CQ) is a popularly-used photosensitizer in composite resin restoration. In this study, the effects of CQ on cytotoxicity and inflammation-related genes and proteins expression of pulp cells were investigated. The role of reactive oxygen species (ROS), ATM/Chk2/p53 and hemeoxygenase-1 (HO-1) and MEK/ERK signaling was also evaluated. We found that ROS and free radicals may play important role in CQ toxicity. CQ (1 and 2 mM) decreased the viability of pulp cells to about 70% and 50% of control, respectively. CQ also induced G2/M cell cycle arrest and apoptosis of pulp cells. The expression of type I collagen, cdc2, cyclin B, and cdc25C was inhibited, while p21, HO-1 and cyclooxygenase-2 (COX-2) were stimulated by CQ. CQ also activated ATM, Chk2, and p53 phosphorylation and GADD45α expression. Besides, exposure to CQ increased cellular ROS level and 8-isoprostane production. CQ also stimulated COX-2 expression and PGE2 production of pulp cells. The reduction of cell viability caused by CQ can be attenuated by N-acetyl-L-cysteine (NAC), catalase and superoxide dismutase (SOD), but can be promoted by Zinc protoporphyin (ZnPP). CQ stimulated ERK1/2 phosphorylation, and U0126 prevented the CQ-induced COX-2 expression and prostaglandin E2 (PGE2) production. These results indicate that CQ may cause cytotoxicity, cell cycle arrest, apoptosis, and PGE2 production of pulp cells. These events could be due to stimulation of ROS and 8-isoprostane production, ATM/Chk2/p53 signaling, HO-1, COX-2 and p21 expression, as well as the inhibition of cdc2, cdc25C and cyclin B1. These results are important for understanding the role of ROS in pathogenesis of pulp necrosis and pulpal inflammation after clinical composite resin filling.
Journal Article
Effects of Trait Anxiety on Error Processing and Post-error Adjustments: An Event-Related Potential Study With Stop-Signal Task
The present study aimed to use event-related potentials with the stop-signal task to investigate the effects of trait anxiety on inhibitory control, error monitoring, and post-error adjustments. The stop-signal reaction time (SSRT) was used to evaluate the behavioral competence of inhibitory control. Electrophysiological signals of error-related negativity (ERN) and error positivity (Pe) were used to study error perception and error awareness, respectively. Post-error slowing (PES) was applied to examine the behavioral adjustments after making errors. The results showed that SSRT and PES did not differ significantly between individuals with high trait anxiety (HTA) and those with low trait anxiety (LTA). However, individuals with HTA demonstrated reduced ERN amplitudes and prolonged Pe latencies than those with LTA. Prolonged Pe latencies were also significantly associated with poorer post-error adjustments. In conclusion, HTA led to reduced cortical responses to error monitoring. Furthermore, inefficient conscious awareness of errors might lead to maladaptive post-error adjustments.
Journal Article
Clarifying the impact of product scarcity and perceived uniqueness in buyers' purchase behavior of games of limited-amount version
Purpose
– Different from general goods, games are intangible. Games of limited-amount version are much more expensive. However, the value of games cannot be actually validated, while buyers purchase the intangible goods. This study, therefore, aims to empirically clarify the impact of product scarcity and uniqueness in buyers' purchase of games of limited-amount version.
Design/methodology/approach
– Based on literature review, the survey method was conducted. Data of 204 respondents who recently bought games of limited-amount version were gathered and analyzed with partial least square.
Findings
– The results showed that perceived quality and perceived uniqueness, significantly increased by product scarcity, was shown of significant positive impact on perceived value which significantly enhanced purchase intention.
Research limitations/implications
– The results indicated the importance of high quality and the reflection of uniqueness in buyers' purchase of games of limited-amount version. The results also validated the effect of scarcity on intangible goods. Practically, the results facilitated strategic operation and marketing of game producers and suppliers in designing and marketing game software. The results also facilitated further theoretical development of goods scarcity.
Originality/value
– Nowadays, product scarcity has been an important operation and marketing strategy to enterprises. Games are an industry of growing importance. However, the impact of scarcity in buyers' purchase of games of limited-amount version was still limited. The results validated the importance of scarcity and perceived uniqueness in intangible game goods purchase behavior. The validation of this study can provide references for strategic operation and marketing of the game industry.
Journal Article
Purification and biochemical characterization of an alkaline feruloyl esterase from Penicillium sumatrense NCH-S2 using rice bran as substrate
Feruloyl esterases (FAEs) are essential accessory enzymes in the hydrolysis of plant cell wall structure. A novel FAE was obtained from Penicillium sumatrense NCH-S2. Enzyme purification was conducted by ultrafiltration, ammonium sulfate precipitation, anion exchange, and gel filtration chromatography. This FAE has a molecular mass of 36 kDa. Its optimum temperature and pH were 50°C and pH 9.0-10.0, respectively. The FAE demonstrated high pH stability at the pH ranging from 6.0 to 10.0. After enzymatic hydrolysis with FAE, the DPPH free radical scavenging capacity, ferrous ion chelating ability, and total phenolic content (TPC) of defatted rice bran (DRB) hydrolysate significantly increased. Furthermore, the amount of released FA from DRB under a synergistic interaction of FAE and hemicellulose increased by 18-21% in comparison with that of either enzyme acting alone.
Journal Article
A Novel Fuzzy DBNet for Medical Image Segmentation
When doctors are fatigued, they often make diagnostic errors. Similarly, pharmacists may also make mistakes in dispensing medication. Therefore, object segmentation plays a vital role in many healthcare-related areas, such as symptom analysis in biomedical imaging and drug classification. However, many traditional deep-learning algorithms use a single view of an image for segmentation or classification. When the image is blurry or incomplete, these algorithms fail to segment the pathological area or the shape of the drugs accurately, which can then affect subsequent treatment plans. Consequently, we propose the Fuzzy DBNet, which combines the dual butterfly network and the fuzzy ASPP in a deep-learning network and processes images from both sides of an object simultaneously. Our experiments used multi-category pill and lung X-ray datasets for training. The average Dice coefficient of our proposed model reached 95.05% in multi-pill segmentation and 97.05% in lung segmentation. The results showed that our proposed model outperformed other state-of-the-art networks in both applications, demonstrating that our model can use multiple views of an image to obtain image segmentation or identification.
Journal Article
WWOX and Its Binding Proteins in Neurodegeneration
WW domain-containing oxidoreductase (WWOX) is known as one of the risk factors for Alzheimer’s disease (AD), a neurodegenerative disease. WWOX binds Tau via its C-terminal SDR domain and interacts with Tau phosphorylating enzymes ERK, JNK, and GSK-3β, and thereby limits AD progression. Loss of WWOX in newborns leads to severe neural diseases and early death. Gradual loss of WWOX protein in the hippocampus and cortex starting from middle age may slowly induce aggregation of a protein cascade that ultimately causes accumulation of extracellular amyloid beta plaques and intracellular tau tangles, along with reduction in inhibitory GABAergic interneurons, in AD patients over 70 years old. Age-related increases in pS14-WWOX accumulation in the brain promotes neuronal degeneration. Suppression of Ser14 phosphorylation by a small peptide Zfra leads to enhanced protein degradation, reduction in NF-κB-mediated inflammation, and restoration of memory loss in triple transgenic mice for AD. Intriguingly, tumor suppressors p53 and WWOX may counteract each other in vivo, which leads to upregulation of AD-related protein aggregation in the brain and lung. WWOX has numerous binding proteins. We reported that the stronger the binding between WWOX and its partners, the better the suppression of cancer growth and reduction in inflammation. In this regard, the stronger complex formation between WWOX and partners may provide a better blockade of AD progression. In this review, we describe whether and how WWOX and partner proteins control inflammatory response and protein aggregation and thereby limit AD progression.
Journal Article
The Antimicrobial Effects of Colistin Encapsulated in Chelating Complex Micelles for the Treatment of Multi-Drug-Resistant Gram-Negative Bacteria: A Pharmacokinetic Study
Infections caused by multi-drug-resistant Gram-negative bacteria (MDR-GNB) are an emerging problem globally. Colistin is the last-sort antibiotic for MDR-GNB, but its toxicity limits its clinical use. We aimed to test the efficacy of colistin-loaded micelles (CCM-CL) against drug-resistant
and compare their safety with that of free colistin in vitro and in vivo.
We incorporated colistin into chelating complex micelles (CCMs), thus producing colistin-loaded micelles (CCM-CL), and conducted both safety and efficacy surveys to elucidate their potential uses.
In a murine model, the safe dose of CCM-CL was 62.5%, which is much better than that achieved after the intravenous bolus injection of 'free' colistin. With a slow drug infusion, the safe dose of CCM-CL reached 16 mg/kg, which is double the free colistin, 8 mg/kg. The area under the curve (AUC) levels for CCM-CL were 4.09- and 4.95-fold higher than those for free colistin in terms of AUC0-t and AUC0-inf, respectively. The elimination half-lives of CCM-CL and free colistin groups were 12.46 and 102.23 min, respectively. In the neutropenic mice model with carbapenem-resistant
pneumonia, the 14-day survival rate of the mice treated with CCM-CL was 80%, which was significantly higher than the 30% in the free colistin group (
< 0.05).
Our results showed that CCM-CL, an encapsulated form of colistin, is safe and effective, and thus may become a drug of choice against MDR-GNB.
Journal Article