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1.
Biomed Eng Lett ; 14(2): 255-265, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38374912

RESUMEN

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique for modulating neuronal excitability by sending a weak current through electrodes attached to the scalp. For decades, the conventional tDCS electrode for stimulating the superficial cortex has been widely reported. However, the investigation of the optimal electrode to effectively stimulate the nonsuperficial cortex is still lacking. In the current study, the optimal tDCS electrode montage that can deliver the maximum electric field to nonsuperficial cortical regions is investigated. Two finite element head models were used for computational simulation to determine the optimal montage for four different nonsuperficial regions: the left foot motor cortex, the left dorsomedial prefrontal cortex (dmPFC), the left medial orbitofrontal cortex (mOFC), and the primary visual cortex (V1). Our findings showed a good consistency in the optimal montage between two models, which led to the anode and cathode being attached to C4-C3 for the foot motor, F4-F3 for the dmPFC, Fp2-F7 for the mOFC, and Oz-Cz for V1. Our suggested montages are expected to enhance the overall effectiveness of stimulation of nonsuperficial cortical areas. Supplementary Information: The online version contains supplementary material available at 10.1007/s13534-023-00335-2.

2.
Bioeng Transl Med ; 8(1): e10362, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36684086

RESUMEN

Adoptive cell therapy (ACT) with antigen-specific T cells is a promising treatment approach for solid cancers. Interleukin-2 (IL-2) has been utilized in boosting the efficacy of ACT. However, the clinical applications of IL-2 in combination with ACT is greatly limited by short exposure and high toxicities. Herein, a complex coacervate was designed to intratumorally deliver IL-2 in a sustained manner and protect against proteolysis. The complex coacervate consisted of fucoidan, a specific IL-2 binding glycosaminoglycan, and poly-l-lysine, a cationic counterpart (FPC2). IL-2-laden FPC2 exhibited a preferential bioactivity in ex vivo expansion of CD8+T cells over Treg cells. Additionally, FPC2 was embedded in pH modulating injectable gel (FPC2-IG) to endure the acidic tumor microenvironment. A single intratumoral administration of FPC2-IG-IL-2 increased expansion of tumor-infiltrating cytotoxic lymphocytes and reduced frequencies of myeloid populations. Notably, the activation and persistency of tumor-reactive T cells were observed only in the tumor site, not in the spleen, confirming a localized effect of FPC2-IG-IL-2. The immune-favorable tumor microenvironment induced by FPC2-IG-IL-2 enabled adoptively transferred TCR-engineered T cells to effectively eradicate tumors. FPC2-IG delivery system is a promising strategy for T-cell-based immunotherapies.

3.
J Neural Eng ; 19(5)2022 09 06.
Artículo en Inglés | MEDLINE | ID: mdl-36066021

RESUMEN

Objective. Temporal interference stimulation (TIS) has shown the potential as a new method for selective stimulation of deep brain structures in small animal experiments. However, it is challenging to deliver a sufficient temporal interference (TI) current to directly induce an action potential in the deep area of the human brain when electrodes are attached to the scalp because the amount of injection current is generally limited due to safety issues. Thus, we propose a novel method called epidural TIS (eTIS) to address this issue; in this method, the electrodes are attached to the epidural surface under the skull.Approach. We employed finite element method (FEM)-based electric field simulations to demonstrate the feasibility of eTIS. We first optimized the electrode conditions to deliver maximum TI currents to each of the three different targets (anterior hippocampus, subthalamic nucleus, and ventral intermediate nucleus) based on FEM, and compared the stimulation focality between eTIS and transcranial TIS (tTIS). Moreover, we conducted realistic skull-phantom experiments for validating the accuracy of the computational simulation for eTIS.Main results. Our simulation results showed that eTIS has the advantage of avoiding the delivery of TI currents over unwanted neocortical regions compared with tTIS for all three targets. It was shown that the optimized eTIS could induce neural action potentials at each of the three targets when a sufficiently large current equivalent to that for epidural cortical stimulation is injected. Additionally, the simulated results and measured results via the phantom experiments were in good agreement.Significance. We demonstrated the feasibility of eTIS, facilitating more focalized and stronger electrical stimulation of deep brain regions than tTIS, with the relatively less invasive placement of electrodes than conventional deep brain stimulation via computational simulation and realistic skull phantom experiments.


Asunto(s)
Estimulación Encefálica Profunda , Estimulación Transcraneal de Corriente Directa , Animales , Encéfalo/fisiología , Simulación por Computador , Electrodos , Estudios de Factibilidad , Humanos , Cuero Cabelludo , Estimulación Transcraneal de Corriente Directa/métodos
4.
Saf Health Work ; 13(1): 3-8, 2022 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-35936202

RESUMEN

Background: This study aims to allow the development of efficient measures to improve occupational health of shift-working nurses focusing on job stress, health promotion behavior, resilience, and sleep disturbance. Methods: It was conducted on a subject panel of 137 nurses who were aware of the purpose of the study and agreed to participate. They worked three shifts at a tertiary hospital or a general hospital located in metropolitan city B. The collected data were analyzed by the independent t test and one-way analysis of variance and post-tested by Scheffe's test, Pearson's correlation coefficients, and multiple linear regression analysis using SPSS/WIN 25.0. Results: The significant influencing factors on sleep disturbance were of those whose subjective health status was 'normal' (ß = 0.29, p < .001), 'not healthy' (ß = .40, p < .001), who have job stress (ß = .22, p = .003), and who have health promotion behavior (ß = -0.17, p = .023). The overall explanatory power was 31.1% (F = 16.31, p < .001). Conclusion: Through this study, nurses' subjective health status and job stress of working shifts were found to be important factors influencing the sleep disturbance level, and the most influencing factor was identified as the subjective health status.

5.
Mol Ther ; 30(8): 2800-2816, 2022 08 03.
Artículo en Inglés | MEDLINE | ID: mdl-35526096

RESUMEN

Several preclinical studies demonstrate that antitumor efficacy of programmed cell death-1 (PD-1)/programmed death-ligand 1 (PD-L1) blockade can be improved by combination with other checkpoint inhibitors. Lymphocyte-activation gene 3 (LAG-3) is an inhibitory checkpoint receptor involved in T cell exhaustion and tumor immune escape. Here, we describe ABL501, a bispecific antibody targeting LAG-3 and PD-L1 in modulating immune cell responses against tumors. ABL501 that efficiently inhibits both LAG-3 and PD-L1 pathways enhances the activation of effector CD4+ and CD8+ T cells with a higher degree than a combination of single anti-LAG-3 and anti-PD-L1. The augmented effector T cell responses by ABL501 resulted in mitigating regulatory-T-cell-mediated immunosuppression. Mechanistically, the simultaneous binding of ABL501 to LAG-3 and PD-L1 promotes dendritic cell (DC) activation and tumor cell conjugation with T cells that subsequently mounts effective CD8+ T cell responses. ABL501 demonstrates its potent in vivo antitumor efficacy in a humanized xenograft model and with knockin mice expressing human orthologs. The immune profiling analysis of peripheral blood reveals an increased abundance of LAG-3hiPD-1hi memory CD4+ T cell subset in relapsed cholangiocarcinoma patients after gemcitabine plus cisplatin therapy, which are more responsive to ABL501. This study supports the clinical evaluation of ABL501 as a novel cancer immunotherapeutic, and a first-in-human trial has started (NCT05101109).


Asunto(s)
Anticuerpos Biespecíficos , Antígenos CD , Antígeno B7-H1 , Neoplasias , Animales , Anticuerpos Biespecíficos/farmacología , Anticuerpos Biespecíficos/uso terapéutico , Antígeno B7-H1/metabolismo , Linfocitos T CD8-positivos , Células Dendríticas , Ratones , Neoplasias/tratamiento farmacológico , Receptor de Muerte Celular Programada 1 , Escape del Tumor , Proteína del Gen 3 de Activación de Linfocitos
6.
Comput Biol Med ; 143: 105337, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-35220075

RESUMEN

Temporal interference stimulation (TIS) has been proved to be effective in stimulating deep brain regions while avoiding the stimulation of neocortical regions in animal experiments. In the traditional TIS, two alternating currents are injected with different frequencies via two electrode pairs attached to the scalp. In the human brain, however, it is difficult to achieve a focal stimulation of deep brain structures due to the high complexity of human brain structures. In this study, we hypothesized that the use of multiple electrode pairs may contribute to the more focalized delivery of temporal interference (TI) currents to the target site in the deep area of the brain. Based on this hypothesis, we proposed a novel multipair TIS method that employs more than two electrode pairs for improved focalized stimulation of the deep brain region (in this study, the head of the right hippocampus). Three realistic finite element models were used to validate the feasibility of the proposed multipair TIS. Additional electrode pairs were sequentially added to the conventional two-electrode pairs with the aim of maximizing the delivery of TI currents to the target while minimizing TI currents in the neocortical regions. The results confirmed that the multipair TIS provides better focalized stimulation than the conventional two-pair TIS for all three head models. It is expected that the proposed multipair TIS can be used to enhance the effectiveness of noninvasive deep brain stimulation.

7.
J Clin Virol ; 141: 104910, 2021 08.
Artículo en Inglés | MEDLINE | ID: mdl-34273861

RESUMEN

BACKGROUND: Hepatitis C virus (HCV) infection is a major cause of liver diseases in Korea. Anti-HCV assays are used to screen for HCV infection. Here, we assessed the agreement and diagnostic performances of three different anti-HCV assays. METHODS: We analyzed 1180 samples using three assay systems-Elecsys Anti-HCV II (Roche Diagnostics), Atellica IM aHCV (Siemens Healthineers), and Alinity s Anti-HCV (Abbott Diagnostics)-and evaluated the agreements between the results and diagnostic performances. RESULTS: The Cohens kappa coefficients between the Roche and Siemens, Siemens and Abbott, and Roche and Abbott systems were 0.837, 0.961, and 0.849, respectively. The Fleiss kappa coefficient among the three systems was 0.883. The sensitivities and positive predictive values were 86.5 and 89.8 for Roche, 97.5 and 98.1 for Siemens, and 99.4 and 98.2 for Abbott, respectively. The area under the curves of the anti-HCV signal to cutoff (S/Co) ratios or cutoff index for predicting viremia in the Roche, Siemens, and Abbott systems were 0.432, 0.641, and 0.676, respectively; the optimal S/Co ratio was 14.715 for Siemens and 14.42 for Abbott. CONCLUSIONS: All three assays showed excellent diagnostic performance; however, anti-HCV values need to be used with caution to predict viremia; therefore, supplementary tests are necessary to confirm viremia status, especially for samples with low values.


Asunto(s)
Anticuerpos contra la Hepatitis C , Hepatitis C , Hepacivirus , Hepatitis C/diagnóstico , Humanos , Sensibilidad y Especificidad , Pruebas Serológicas , Viremia
8.
Cancer Lett ; 510: 37-47, 2021 07 10.
Artículo en Inglés | MEDLINE | ID: mdl-33872695

RESUMEN

Aberrant activation of cytokine and growth factor signal transduction pathways confers enhanced survival and proliferation properties to acute myeloid leukemia (AML) cells. However, the mechanisms underlying the deregulation of signaling pathways in leukemia cells are unclear. To identify genes capable of independently supporting cytokine-independent growth, we employed a genome-wide CRISPR/Cas9-mediated loss-of-function screen in GM-CSF-dependent human AML TF-1 cells. More than 182 genes (p < 0.01) were found to suppress the cytokine-independent growth of TF-1 cells. Among the top hits, genes encoding key factors involved in sialylation biosynthesis were identified; these included CMAS, SLC35A1, NANS, and GNE. Knockout of either CMAS or SLC35A1 enabled cytokine-independent proliferation and survival of AML cells. Furthermore, NSG (NOD/SCID/IL2Rγ-/-) mice injected with CMAS or SLC35A1-knockout TF-1 cells exhibited a shorter survival than mice injected with wild-type cells. Mechanistically, abrogation of sialylation biosynthesis in TF-1 cells induced a strong activation of ERK signaling, which sensitized cells to MEK inhibitors but conferred resistance to JAK inhibitors. Further, the surface level of α2,3-linked sialic acids was negatively correlated with the sensitivity of AML cell lines to MEK/ERK inhibitors. We also found that sialylation modulated the expression and stability of the CSF2 receptor. Together, these results demonstrate a novel role of sialylation in regulating oncogenic transformation and drug resistance development in leukemia. We propose that altered sialylation could serve as a biomarker for targeted anti-leukemic therapy.


Asunto(s)
Repeticiones Palindrómicas Cortas Agrupadas y Regularmente Espaciadas/genética , Leucemia Mieloide Aguda/genética , Animales , Carcinogénesis , Línea Celular Tumoral , Humanos , Leucemia Mieloide Aguda/patología , Ratones , Transducción de Señal
9.
Biomol Ther (Seoul) ; 28(6): 569-575, 2020 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-32536619

RESUMEN

Crotamiton is an anti-scabies drug, but it was recently found that crotamiton also suppresses non-scabietic itching in mice. However, the underlying mechanism is largely unclear. Therefore, aim of the study is to investigate mechanisms of the anti-pruritic effect of crotamiton for non-scabietic itching. Histamine and chloroquine are used as non-scabietic pruritogens. The effect of crotamiton was identified using fluorometric intracellular calcium assays in HEK293T cells and primary cultured dorsal root ganglion (DRG) neurons. Further in vivo effect was evaluated by scratching behavior tests. Crotamiton strongly inhibited histamine-induced calcium influx in HEK293T cells, expressing both histamine receptor 1 (H1R) and transient receptor potential vanilloid 1 (TRPV1), as a model of histamine-induced itching. Similarly, it also blocked chloroquine-induced calcium influx in HEK293T cells, expressing both Mas-related G-protein-coupled receptor A3 (MRGPRA3) and transient receptor potential A1 (TRPA1), as a model of histamine-independent itching. Furthermore, crotamiton also suppressed both histamine- and chloroquine-induced calcium influx in primary cultures of mouse DRG. Additionally, crotamiton strongly suppressed histamine- and chloroquine-induced scratching in mice. Overall, it was found that crotamiton has an anti-pruritic effect against non-scabietic itching by histamine and chloroquine. Therefore, crotamiton may be used as a general anti-pruritic agent, irrespective of the presence of scabies.

10.
Angew Chem Int Ed Engl ; 59(37): 15886-15890, 2020 09 07.
Artículo en Inglés | MEDLINE | ID: mdl-32495457

RESUMEN

Inspired by natural photosynthesis, biocatalytic photoelectrochemical (PEC) platforms are gaining prominence for the conversion of solar energy into useful chemicals by combining redox biocatalysis and photoelectrocatalysis. Herein, we report a dual biocatalytic PEC platform consisting of a molybdenum (Mo)-doped BiVO4 (Mo:BiVO4 ) photoanode and an inverse opal ITO (IO-ITO) cathode that gives rise to the coupling of peroxygenase and ene-reductase-mediated catalysis, respectively. In the PEC cell, the photoexcited electrons generated from the Mo:BiVO4 are transferred to the IO-ITO and regenerate reduced flavin mononucleotides to drive ene-reductase-catalyzed trans-hydrogenation of ketoisophrone to (R)-levodione. Meanwhile, the photoactivated Mo:BiVO4 evolves H2 O2 in situ via a two-electron water-oxidation process with the aid of an applied bias, which simultaneously supplies peroxygenases to drive selective hydroxylation of ethylbenzene into enantiopure (R)-1-phenyl-1-hydroxyethane. Thus, the deliberate integration of PEC systems with redox biocatalytic reactions can simultaneously produce valuable chemicals on both electrodes using solar-powered electrons and water.


Asunto(s)
Técnicas Electroquímicas/métodos , Procesos Fotoquímicos , Energía Solar , Biocatálisis , Bismuto/química , Espectroscopía Dieléctrica , Hidrógeno/química , Oxidación-Reducción , Espectrofotometría Ultravioleta , Vanadatos/química
11.
Cancer Immunol Res ; 8(7): 912-925, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32265229

RESUMEN

Clinical trials are evaluating the efficacy of anti-TIGIT for use as single-agent therapy or in combination with programmed death 1 (PD-1)/programmed death-ligand 1 blockade. How and whether a TIGIT blockade will synergize with immunotherapies is not clear. Here, we show that CD226loCD8+ T cells accumulate at the tumor site and have an exhausted phenotype with impaired functionality. In contrast, CD226hiCD8+ tumor-infiltrating T cells possess greater self-renewal capacity and responsiveness. Anti-TIGIT treatment selectively affects CD226hiCD8+ T cells by promoting CD226 phosphorylation at tyrosine 322. CD226 agonist antibody-mediated activation of CD226 augments the effect of TIGIT blockade on CD8+ T-cell responses. Finally, mFOLFIRINOX treatment, which increases CD226hiCD8+ T cells in patients with pancreatic ductal adenocarcinoma, potentiates the effects of TIGIT or PD-1 blockade. Our results implicate CD226 as a predictive biomarker for cancer immunotherapy and suggest that increasing numbers of CD226hiCD8+ T cells may improve responses to anti-TIGIT therapy.


Asunto(s)
Antineoplásicos Inmunológicos/farmacología , Linfocitos T CD8-positivos/inmunología , Inmunoterapia/métodos , Neoplasias/terapia , Receptores Inmunológicos/antagonistas & inhibidores , Receptores Inmunológicos/inmunología , Animales , Antígenos de Diferenciación de Linfocitos T/inmunología , Antígenos de Diferenciación de Linfocitos T/metabolismo , Biomarcadores de Tumor/inmunología , Biomarcadores de Tumor/metabolismo , Linfocitos T CD8-positivos/metabolismo , Línea Celular Tumoral , Modelos Animales de Enfermedad , Femenino , Humanos , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Neoplasias/inmunología , Neoplasias/metabolismo
12.
J Control Release ; 315: 65-75, 2019 12 10.
Artículo en Inglés | MEDLINE | ID: mdl-31669264

RESUMEN

Clinical data from diverse cancer types shows that the increased T cell infiltration in tumors correlates with improved patient prognosis. Acidic extracellular pH is a major attribute of the tumor microenvironment (TME) that promotes immune evasion and tumor progression. Therefore, antagonizing tumor acidity can be a powerful approach in cancer immunotherapy. Here, Pluronic F-127 is used as a NaHCO3 releasing carrier to focally alleviate extracellular tumor acidity. In a mouse tumor model, intratumoral treatment with pH modulating injectable gel (pHe-MIG) generates immune-favorable TME, as evidenced by the decrease of immune-suppressive cells and increase of tumor infiltrating CD8+T cells. The combination of pHe-MIG with immune checkpoint inhibitors, anti-PD-1 and anti-TIGIT antibodies, increases intratumoral T cell function, which leads to tumor clearance. Mechanistically, extracellular acidity was shown to upregulate co-inhibitory immune checkpoint receptors and inhibit mTOR signaling pathways in memory CD8+T cells, which impaired effector functions. Furthermore, an acidic pH environment increased the expression and engagement of TIGIT and its ligand CD155, which suggested that the extracellular pH can regulate the suppressive function of TIGIT pathway. Collectively, these findings suggest that pHe-MIG holds potential as a new TME modulator for effective immune checkpoint inhibitor therapies.


Asunto(s)
Linfocitos T CD8-positivos/inmunología , Inmunoterapia/métodos , Neoplasias/terapia , Microambiente Tumoral/inmunología , Animales , Portadores de Fármacos/química , Geles , Humanos , Concentración de Iones de Hidrógeno , Masculino , Ratones , Ratones Endogámicos C57BL , Neoplasias/inmunología , Poloxámero/química , Receptor de Muerte Celular Programada 1/inmunología , Receptores Inmunológicos/inmunología , Serina-Treonina Quinasas TOR/inmunología
13.
Angew Chem Int Ed Engl ; 57(42): 13825-13828, 2018 10 15.
Artículo en Inglés | MEDLINE | ID: mdl-30062834

RESUMEN

Light-driven activation of redox enzymes is an emerging route for sustainable chemical synthesis. Among redox enzymes, the family of Old Yellow Enzyme (OYE) dependent on the nicotinamide adenine dinucleotide cofactor (NADH) catalyzes the stereoselective reduction of α,ß-unsaturated hydrocarbons. Here, we report OYE-catalyzed asymmetric hydrogenation through light-driven regeneration of NADH and its analogues (mNADHs) by N-doped carbon nanodots (N-CDs), a zero-dimensional photocatalyst. Our spectroscopic and photoelectrochemical analyses verified the transfer of photo-induced electrons from N-CDs to an organometallic electron mediator (M) for highly regioselective regeneration of cofactors. Light triggered the reduction of NAD+ and mNAD+ s with the cooperation of N-CDs and M, and the reduction behaviors of cofactors were dependent on their own reduction peak potentials. The regenerated cofactors subsequently delivered hydrides to OYE for stereoselective conversions of a broad range of substrates with excellent biocatalytic efficiencies.


Asunto(s)
Biocatálisis , Carbono/química , NAD/química , Nanoestructuras/química , Electrones
14.
Angew Chem Int Ed Engl ; 57(27): 7958-7985, 2018 07 02.
Artículo en Inglés | MEDLINE | ID: mdl-29194901

RESUMEN

Biocatalytic transformation has received increasing attention in the green synthesis of chemicals because of the diversity of enzymes, their high catalytic activities and specificities, and mild reaction conditions. The idea of solar energy utilization in chemical synthesis through the combination of photocatalysis and biocatalysis provides an opportunity to make the "green" process greener. Oxidoreductases catalyze redox transformation of substrates by exchanging electrons at the enzyme's active site, often with the aid of electron mediator(s) as a counterpart. Recent progress indicates that photoinduced electron transfer using organic (or inorganic) photosensitizers can activate a wide spectrum of redox enzymes to catalyze fuel-forming reactions (e.g., H2 evolution, CO2 reduction) and synthetically useful reductions (e.g., asymmetric reduction, oxygenation, hydroxylation, epoxidation, Baeyer-Villiger oxidation). This Review provides an overview of recent advances in light-driven activation of redox enzymes through direct or indirect transfer of photoinduced electrons.


Asunto(s)
Luz , Oxidorreductasas/metabolismo , Biocatálisis , Sistema Enzimático del Citocromo P-450/química , Sistema Enzimático del Citocromo P-450/metabolismo , Electrones , NAD/química , Nanoestructuras/química , Oxidación-Reducción , Oxidorreductasas/química , Fármacos Fotosensibilizantes/química , Proteínas del Complejo del Centro de Reacción Fotosintética/química , Proteínas del Complejo del Centro de Reacción Fotosintética/metabolismo
15.
Angew Chem Int Ed Engl ; 56(30): 8681-8685, 2017 07 17.
Artículo en Inglés | MEDLINE | ID: mdl-28544039

RESUMEN

Enoate reductases from the family of old yellow enzymes (OYEs) can catalyze stereoselective trans-hydrogenation of activated C=C bonds. Their application is limited by the necessity for a continuous supply of redox equivalents such as nicotinamide cofactors [NAD(P)H]. Visible light-driven activation of OYEs through NAD(P)H-free, direct transfer of photoexcited electrons from xanthene dyes to the prosthetic flavin moiety is reported. Spectroscopic and electrochemical analyses verified spontaneous association of rose bengal and its derivatives with OYEs. Illumination of a white light-emitting-diode triggered photoreduction of OYEs by xanthene dyes, which facilitated the enantioselective reduction of C=C bonds in the absence of NADH. The photoenzymatic conversion of 2-methylcyclohexenone resulted in enantiopure (ee>99 %) (R)-2-methylcyclohexanone with conversion yields as high as 80-90 %. The turnover frequency was significantly affected by the substitution of halogen atoms in xanthene dyes.

16.
Foodborne Pathog Dis ; 12(9): 741-8, 2015 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-26219023

RESUMEN

In South Korea, few reports have indicated the occurrence and characteristics of extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli in food-producing animals, particularly in poultry slaughterhouses. In this study, we investigated the occurrence and antibiotic resistance of ESBL-producing E. coli from whole chicken carcasses (n=156) and fecal samples (n=39) of chickens obtained from 2 slaughterhouses. Each sample enriched in buffered peptone water was cultured on MacConkey agar with 2 mg/L cefotaxime and ESBL agar. ESBL production and antibiotic susceptibility were determined using the Trek Diagnostics system. The ESBL genotypes were determined by polymerase chain reaction (PCR) using the bla(SHV), bla(TEM), and bla(CTX-M) gene sequences. Subtyping using a repetitive sequence-based PCR system (DiversiLab™) and multilocus sequence typing (MLST) were used to assess the interspecific biodiversity of isolates. Sixty-two ESBL-producing E. coli isolates were obtained from 156 samples (39.7%). No bla(SHV) genes were detected in any of the isolates, whereas all contained the bla(TEM) gene. Twenty-five strains (40.3%) harbored the CTX-M group 1 gene. The most prevalent MLST sequence type (ST) was ST 93 (14.5%), followed by ST 117 (9.7%) and ST 2303 (8.1%). This study reveals a high occurrence and ß-lactams resistance rate of E. coli in fecal samples and whole chickens collected from slaughterhouses in South Korea.


Asunto(s)
Mataderos , Pollos/microbiología , Escherichia coli/enzimología , beta-Lactamasas/aislamiento & purificación , Animales , Heces/enzimología , Tipificación de Secuencias Multilocus , Reacción en Cadena de la Polimerasa , República de Corea , Resistencia betalactámica/genética , Resistencia betalactámica/inmunología , beta-Lactamasas/genética
17.
J Food Sci ; 80(6): M1266-70, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25950845

RESUMEN

Korean fermented soybean products, such as doenjang, kochujang, ssamjang, and cho-kochujang, can harbor foodborne pathogens such as Bacillus cereus sensu lato (B. cereus sensu lato). The aim of this study was to characterize the toxin gene profiles, biochemical characteristics, and antibiotic resistance patterns of B. cereus sensu lato strains isolated from Korean fermented soybean products. Eighty-eight samples of Korean fermented soybean products purchased from retails in Seoul were tested. Thirteen of 26 doenjang samples, 13 of 23 kochujang samples, 16 of 30 ssamjang samples, and 5 of 9 cho-kochujang samples were positive for B. cereus sensu lato strains. The contamination level of all positive samples did not exceed 4 log CFU/g of food (maximum levels of Korea Food Code). Eighty-seven B. cereus sensu lato strains were isolated from 47 positive samples, and all isolates carried at least one enterotoxin gene. The detection rates of hblCDA, nheABC, cytK, and entFM enterotoxin genes among all isolates were 34.5%, 98.9%, 57.5%, and 100%, respectively. Fifteen strains (17.2%) harbored the emetic toxin gene. Most strains tested positive for salicin fermentation (62.1%), starch hydrolysis (66.7%), hemolysis (98.9%), motility test (100%), and lecithinase production (96.6%). The B. cereus sensu lato strains were highly resistant to ß-lactam antibiotics such as ampicillin, penicillin, cefepime, imipenem, and oxacillin. Although B. cereus sensu lato levels in Korean fermented soybean products did not exceed the maximum levels permitted in South Korea (<10(4) CFU/g), these results indicate that the bacterial isolates have the potential to cause diarrheal or emetic gastrointestinal diseases.


Asunto(s)
Antibacterianos/farmacología , Bacillus cereus , Toxinas Bacterianas , Enterotoxinas , Fermentación , Microbiología de Alimentos , Alimentos de Soja/microbiología , Bacillus cereus/efectos de los fármacos , Bacillus cereus/genética , Bacillus cereus/crecimiento & desarrollo , Bacillus cereus/metabolismo , Toxinas Bacterianas/genética , Alcoholes Bencílicos/metabolismo , Reactores Biológicos , Enterotoxinas/genética , Enfermedades Gastrointestinales/microbiología , Glucósidos/metabolismo , Humanos , Incidencia , República de Corea , Glycine max/microbiología
18.
J Mater Chem B ; 3(22): 4483-4486, 2015 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-32262391

RESUMEN

We report the first hematite-based photoelectrochemical (PEC) biosensor platform to detect NADH under visible-light irradiation. To enhance the electrical signal of photoanodes, we employed mussel-inspired polydopamine which immobilizes redox mediators on hematite. The enzymatic PEC biosensor enabled the detection of glucose, ethanol, and lactate, and even showed successful detection of glucose in human plasma, suggesting the practical usefulness of our platform.

19.
Angew Chem Int Ed Engl ; 54(3): 969-73, 2015 Jan 12.
Artículo en Inglés | MEDLINE | ID: mdl-25430544

RESUMEN

Cytochromes P450 can catalyze various regioselective and stereospecific oxidation reactions of non-functionalized hydrocarbons. Here, we have designed a novel light-driven platform for cofactor-free, whole-cell P450 photo-biocatalysis using eosin Y (EY) as a photosensitizer. EY can easily enter into the cytoplasm of Escherichia coli and bind specifically to the heme domain of P450. The catalytic turnover of P450 was mediated through the direct transfer of photoinduced electrons from the photosensitized EY to the P450 heme domain under visible light illumination. The photoactivation of the P450 catalytic cycle in the absence of cofactors and redox partners is successfully conducted using many bacterial P450s (variants of P450 BM3) and human P450s (CYPs 1A1, 1A2, 1B1, 2A6, 2E1, and 3A4) for the bioconversion of different substrates, including marketed drugs (simvastatin, lovastatin, and omeprazole) and a steroid (17ß-estradiol), to demonstrate the general applicability of the light-driven, cofactor-free system.


Asunto(s)
Sistema Enzimático del Citocromo P-450/metabolismo , Luz , Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Biocatálisis , Sistema Enzimático del Citocromo P-450/química , Transporte de Electrón , Escherichia coli/metabolismo , Estradiol/química , Estradiol/metabolismo , Fluoresceína/química , Fluoresceína/metabolismo , Hemo/química , Hemo/metabolismo , Humanos , Lovastatina/química , Lovastatina/metabolismo , Omeprazol/química , Omeprazol/metabolismo , Oxidación-Reducción , Fármacos Fotosensibilizantes/química , Fármacos Fotosensibilizantes/metabolismo , Estructura Terciaria de Proteína , Simvastatina/química , Simvastatina/metabolismo
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