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1.
Wilderness Environ Med ; 30(2): 191-194, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31005608

RESUMO

INTRODUCTION: Understanding patterns of avalanche fatalities can aid prevention and rescue strategies. In 2007, we published a report reviewing avalanche deaths in Utah between the 1989-1990 and 2005-2006 winter seasons. In the current report, we discuss Utah avalanche fatalities from the 2006-2007 to 2017-2018 seasons. METHODS: Avalanche fatality data were obtained from the Utah Avalanche Center and Utah State Office of the Medical Examiner. Autopsy reports were reviewed to determine demographic information, type of autopsy (external vs internal), injuries, and cause of death. RESULTS: Thirty-two avalanche deaths occurred in Utah during the study period. The mean (±SD) age of victims was 32±13 (8-54) y. Thirty victims (94%) were male and 2 (6%) were female. Seventy-two percent of deaths were from asphyxiation, 19% from trauma alone, and 9% from a combination of asphyxiation and trauma. Snowmobilers accounted for the largest percentage of avalanche fatalities (15 victims; 47%) during the 2007-2018 period. CONCLUSIONS: Asphyxia continues to be the most prevalent killer in avalanche burial. Patterns of ongoing avalanche deaths continue to suggest that rapid recovery and techniques that prolong survival while buried may decrease fatality rates. Trauma is a significant factor in many avalanche fatalities. Education and technologies focused on reducing traumatic injuries such as improved education in techniques for avalanche risk avoidance and/or use of avalanche airbags may further decrease fatality rates. Snowmobilers represent an increasing percentage of Utah avalanche deaths and now make up the majority of victims; increased education targeting this demographic in the basics of avalanche rescue gear and avalanche rescue may also reduce fatalities.


Assuntos
Asfixia/mortalidade , Avalanche/mortalidade , Causas de Morte , Ferimentos e Lesões/mortalidade , Adolescente , Adulto , Asfixia/epidemiologia , Autopsia/estatística & dados numéricos , Criança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Veículos Off-Road/estatística & dados numéricos , Utah/epidemiologia , Ferimentos e Lesões/epidemiologia
2.
J Surg Oncol ; 117(8): 1679-1686, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29790169

RESUMO

BACKGROUND AND OBJECTIVES: Although MET amplification/overexpression was observed in a subset of gastric cancer (GC) patients, the relationship between MET amplification/overexpression in primary GC and liver metastasis was unclear. METHODS: GC samples and matched liver metastases (N = 47) were analyzed by fluorescence/silver in-situ hybridization (FISH/SISH) and by immunohistochemistry for MET amplification and MET expression, respectively. MET-copy number (CN) and Met expression data from The Cancer Genome Atlas Stomach Adenocarcinoma (TCGA-STAD, N = 356) were also analyzed. RESULTS: Significant overlap existed between MET amplification and Met expression in both primary stomach tumors (P = 0.013) and liver metastasis (P = 0.001). In TCGA-STAD, MET-CN (≥4 copies) and MET expression were also positively correlated (r = 0.761; P = 0.017). Comparative analysis revealed a strong association between MET expression and MET amplification (85% concurrence) in primary stomach tumors and matched liver metastasis. MET status in synchronous liver metastasis (N = 36) was correlated with primary stomach tumors. However, a significant correlation between primary tumors and liver metastases was not observed in patients with metachronous liver metastasis. Survival analyses revealed that both MET amplification and MET overexpression were prognostic of poor outcomes. CONCLUSIONS: MET amplification and Met overexpression were positively correlated in GC. MET status should be re-evaluated in GC patients with liver metastasis, especially for metachronous metastasis.


Assuntos
Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/mortalidade , Proteínas Proto-Oncogênicas c-met/metabolismo , Neoplasias Gástricas/metabolismo , Neoplasias Gástricas/mortalidade , Feminino , Amplificação de Genes , Expressão Gênica , Humanos , Imuno-Histoquímica , Hibridização in Situ Fluorescente , Neoplasias Hepáticas/secundário , Masculino , Pessoa de Meia-Idade , Prognóstico , Proteínas Proto-Oncogênicas c-met/genética , República da Coreia/epidemiologia , Neoplasias Gástricas/patologia
3.
Bioorg Med Chem Lett ; 24(1): 173-6, 2014 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-24342239

RESUMO

l-Arabinitol 4-dehydrogenase (LAD) from Hypocrea jecorina (HjLAD) was cloned and overexpressed in Escherichia coli BL21 (DE3). The kinetics of l-arabinitol oxidation by NAD(+), catalyzed by HjLAD, was studied within the pH range of 7.0-9.5 at 25°C. The turnover number (kcat) and the catalytic efficiency (kcat/Km) were 4200min(-1) and 290mM(-1)min(-1), respectively. HjLAD showed the highest turnover number and catalytic efficiency among all previously characterized LADs. In further application of HjLAD, rare l-sugar l-xylulose was produced by the enzymatic oxidation of arabinitol to give a yield of approximately 86%.


Assuntos
Hypocrea/enzimologia , Desidrogenase do Álcool de Açúcar/metabolismo , Xilulose/biossíntese , Biocatálise , Concentração de Íons de Hidrogênio , Cinética , Modelos Moleculares , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Desidrogenase do Álcool de Açúcar/isolamento & purificação , Xilulose/química
4.
J Dent Educ ; 88(4): 403-410, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38269493

RESUMO

PURPOSE/OBJECTIVES: The objectives of this study were to assess the influence of learner- and education-related factors on standardized in-service examination performance and determine whether in-service examination scores predict residency outcomes. METHODS: American Academy of Periodontology (AAP) In-service Examination (AIE) scores from 10 periodontics residency classes at a single center were recorded and compared against a panel of learner- and education-related variables using multiple linear regression models. Defined residency outcome measures were analyzed against AIE scores using binomial logistic regression. RESULTS: No evaluated learner- or education-related variable was a statistically significant predictor of AIE score in this study sample. Likewise, AIE score was not a statistically significant predictor of any assessed residency outcome. CONCLUSIONS: The AAP has performed a tremendous service to periodontics residents and programs by marshaling the leadership and expertise necessary to offer a professionally constructed assessment instrument. However, in the current study, no relationship could be identified between AIE score and any outcome, including first-attempt board certification. The AAP In-service Committee appears well situated to provide additional leadership focusing on exam implementation, which may enhance AIE value in competency decision making.


Assuntos
Internato e Residência , Estados Unidos , Educação de Pós-Graduação em Medicina , Periodontia , Avaliação Educacional , Competência Clínica
5.
Bioprocess Biosyst Eng ; 36(10): 1417-25, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23297068

RESUMO

In this study, a microbial fuel cell (MFC) was used to control malodorous hydrogen sulfide compounds generated from domestic wastewaters. The electricity production demonstrated a distinct pattern of a two-step increase during 170 h of system run: the first maximum current density was 118.6 ± 7.2 mA m⁻² followed by a rebound of current density increase, reaching the second maximum of 176.8 ± 9.4 mA m⁻². The behaviors of the redox potential and the sulfate level in the anode compartment indicated that the microbial production of hydrogen sulfide compounds was suppressed in the first stage, and the hydrogen sulfide compounds generated from the system were removed effectively as a result of their electrochemical oxidation, which contributed to the additional electricity production in the second stage. This was also directly supported by sulfur deposits formed on the anode surface, which was confirmed by analyses on those solids using a scanning electron microscope equipped with energy dispersive X-ray spectroscopy as well as an elemental analyzer. To this end, the overall reduction efficiencies for HS⁻ and H2S(g) were as high as 67.5 and 96.4 %, respectively. The correlations among current density, redox potential, and sulfate level supported the idea that the electricity signal generated in the MFC can be utilized as a potential indicator of malodor control for the domestic wastewater system.


Assuntos
Fontes de Energia Bioelétrica , Sulfeto de Hidrogênio/metabolismo , Odorantes , Microscopia Eletrônica de Varredura , Espectrometria por Raios X
6.
Blood ; 115(5): 1049-53, 2010 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-19965645

RESUMO

To elucidate whether tyrosine kinase inhibitor (TKI) resistance in chronic myeloid leukemia is associated with characteristic genomic alterations, we analyzed DNA samples from 45 TKI-resistant chronic myeloid leukemia patients with 250K single nucleotide polymorphism arrays. From 20 patients, matched serial samples of pretreatment and TKI resistance time points were available. Eleven of the 45 TKI-resistant patients had mutations of BCR-ABL1, including 2 T315I mutations. Besides known TKI resistance-associated genomic lesions, such as duplication of the BCR-ABL1 gene (n = 8) and trisomy 8 (n = 3), recurrent submicroscopic alterations, including acquired uniparental disomy, were detectable on chromosomes 1, 8, 9, 17, 19, and 22. On chromosome 22, newly acquired and recurrent deletions of the IGLC1 locus were detected in 3 patients, who had previously presented with lymphoid or myeloid blast crisis. This may support a hypothesis of TKI-induced selection of subclones differentiating into immature B-cell progenitors as a mechanism of disease progression and evasion of TKI sensitivity.


Assuntos
Resistencia a Medicamentos Antineoplásicos/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Polimorfismo de Nucleotídeo Único , Inibidores de Proteínas Quinases/uso terapêutico , Benzamidas , Aberrações Cromossômicas , Cromossomos Humanos Par 1/genética , Cromossomos Humanos Par 17/genética , Cromossomos Humanos Par 19/genética , Cromossomos Humanos Par 22/genética , Cromossomos Humanos Par 8/genética , Cromossomos Humanos Par 9/genética , Dasatinibe , Proteínas de Fusão bcr-abl/genética , Perfilação da Expressão Gênica , Regulação Leucêmica da Expressão Gênica , Humanos , Mesilato de Imatinib , Mutação , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Piperazinas/farmacologia , Piperazinas/uso terapêutico , Inibidores de Proteínas Quinases/farmacologia , Proteínas Tirosina Quinases/antagonistas & inibidores , Proteínas Tirosina Quinases/genética , Pirimidinas/farmacologia , Pirimidinas/uso terapêutico , Tiazóis/farmacologia , Tiazóis/uso terapêutico
7.
Nanomaterials (Basel) ; 12(4)2022 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-35215030

RESUMO

Graphene quantum dots (GQDs) were synthesized using watermelon rind waste as a photoluminescent (PL) agent for ferric ion (Fe3+) detection and in vitro cellular bio-imaging. A green and simple one-pot hydrothermal technique was employed to prepare the GQDs. Their crystalline structures corresponded to the lattice fringe of graphene, possessing amide, hydroxyl, and carboxyl functional groups. The GQDs exhibited a relatively high quantum yield of approximately 37%. Prominent blue emission under UV excitation and highly selective PL quenching for Fe3+ were observed. Furthermore, Fe3+ could be detected at concentrations as low as 0.28 µM (limit of detection), allowing for high sensitivity toward Fe3+ detection in tap and drinking water samples. In the bio-imaging experiment, the GQDs exhibited a low cytotoxicity for the HeLa cells, and they were clearly illuminated at an excitation wavelength of 405 nm. These results can serve as the basis for developing an environment-friendly, simple, and cost-effective approach of using food waste by converting them into photoluminescent nanomaterials for the detection of metal ions in field water samples and biological cellular studies.

8.
Bioresour Technol ; 331: 125060, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33798863

RESUMO

Fly ash (FA), obtained as waste materials from industrial power plants, is generated in large quantities and low recycling. In this study, re-generation of waste FA as cost-effective materials with adsorbent and antibacterial applications was assessed. Alkaline/zinc-activated fly ash nanocomposite (A-FA/Zn) was prepared using one-pot hydrothermal technique. Those nanocomposites are characterized by high surface area and negatively surface charge, which are important influences contributing to an enhancement in adsorption capacity via increase in the number of adsorptive sites and electrostatic interaction between dye molecules-nanocomposites. Additionally, the presence of Zn ions in the prepared nanocomposites represents a key advantage with respect to enhancing antibacterial activity. The feasibility of further enhancing adsorption and antibacterial mechanisms was also examined. It is anticipated that the findings of this study will provide useful information with respect to the development of simple, eco-friendly and low-cost A-FA/Zn with multifunctional applications as organic dye removal and antibacterial purposes.


Assuntos
Nanocompostos , Poluentes Químicos da Água , Adsorção , Álcalis , Antibacterianos/farmacologia , Cinza de Carvão , Poluentes Químicos da Água/análise , Zinco
9.
J Hazard Mater ; 402: 123760, 2021 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-33254773

RESUMO

Although it has recently been reported that notable amounts of rare earth elements (REEs) are present in the residual coal ash, little is currently known regarding the association of these elements with the coal ash matrix, thereby limiting the potential for extraction of REEs from coal ash. In this study, we analyzed the binding characteristics of REEs within coal ash via sequential extraction and examined REE recovery during a coal ash recycling process. Major components of coal ash were found to be mineral oxides, mainly composed of Si, Fe, Al, and Ca, and residual carbons. Bottom and fly ashes were found to contain 185.8 mg/kg and 179.2 mg/kg of REEs, respectively. Tessier sequential extraction confirmed that 85 % of REEs are included in the residual fraction of both bottom and fly ashes. Furthermore, BCR sequential extraction revealed that 60-70 % of REEs are contained within the residual fraction, thereby indicating that REEs are strongly bound in both bottom and fly ashes and the use of very strong acids is required for the thorough extraction of REEs from coal ash. Additionally, it was found that 46.3 % of REEs can be recovered from the wastewaters produced during the process of coal ash-derived zeolite synthesis.

10.
Bioresour Technol ; 307: 123201, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32220822

RESUMO

A new type of biocatalyst was developed to facilitate the biochemical decomposition of 4-chlorophenol (4-CP) in this study. Oxydoreductases that catalyze the initial steps of 4-CP biodegradation were immobilized on a synthetic inorganic enzyme support. Type-X zeolite, a high-surface area support, was synthesized from coal fly ash, on which nickel ions were plated by impregnation (Ni-zeolite), followed by the effective immobilization (77.5% immobilization yield) of recombinant monooxygenase (CphC-I), dioxygenase (CphA-I), and flavin reductase (Fre) isolated from Pseudarthrobacter chlorophenolicus A6 and Escherichia coli K-12, respectively. The retained catalytic activity of the enzymes immobilized on Ni-zeolite was as high as 64% of the value for the corresponding free enzymes. The Michaelis-Menten kinetic parameters vmax and KM of the immobilized enzymes were determined to be 0.20 mM·min-1 and 0.44 mM, respectively. These results are expected to provide useful information with respect to the development of novel enzymatic treatments for phenolic hydrocarbon contaminants.


Assuntos
Clorofenóis , Escherichia coli K12 , Zeolitas , Carvão Mineral , Cinza de Carvão
11.
J Health Popul Nutr ; 27(1): 4-13, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19248643

RESUMO

Vivax malaria is a significant cause of morbidity due to malaria in northern Thailand, accounting for approximately 50% of all malaria cases. The objective of this study was to determine the behavioural factors associated with adherence to the standard 14-day course of chloroquine and primaquine, prescribed from malaria clinics, among patients with vivax malaria. A retrospective study was conducted among 206 patients living in Muang and Mae Sa Riang districts of Mae Hon Son province in northern Thailand. Data on adherence and potential behavioural factors relating to adherence were collected using a structured interviewer-administered questionnaire and supplemented with qualitative data from focus-group interviews. The results indicated that 76.21% of the 206 patients with vivax malaria did not complete the medication course. The adherence of the patients was associated with knowledge scores of malaria (adjusted odds ratio [AOR]=2.2, 95% confidence interval [CI] 1.1-4.5) and accessing drug prescription scores (AOR=5.6, 95% CI 2.13-15.3). Therefore, further effort is needed to educate patients with vivax malaria on knowledge of malaria and its treatment with simple health messages and encourage them to adhere to their treatment.


Assuntos
Antimaláricos/uso terapêutico , Conhecimentos, Atitudes e Prática em Saúde , Malária Vivax/tratamento farmacológico , Cooperação do Paciente , Educação de Pacientes como Assunto , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Intervalos de Confiança , Feminino , Grupos Focais , Humanos , Malária Vivax/epidemiologia , Malária Vivax/psicologia , Malária Vivax/transmissão , Masculino , Pessoa de Meia-Idade , Razão de Chances , Estudos Retrospectivos , Inquéritos e Questionários , Tailândia/epidemiologia , Resultado do Tratamento , Adulto Jovem
12.
Environ Sci Pollut Res Int ; 26(33): 34047-34057, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30244447

RESUMO

In this study, the catalytic activity and kinetic characteristics of the aromatic hydrocarbon dioxygenase system and the possibility of substituting its ferredoxin and ferredoxin reductase components were evaluated. The genes encoding toluene dioxygenase and toluene dihydrodiol dehydrogenase were cloned from Pseudomonas putida F1, and the corresponding enzymes were overexpressed and purified to homogeneity. Oxidative hydroxylation of toluene to cis-toluene dihydrodiol was catalyzed by toluene dioxygenase, and its subsequent dehydrogenation to 3-methylcatechol was catalyzed by toluene dihydrodiol dehydrogenase. The specific activity of the dioxygenase was 2.82 U/mg-protein, which is highly remarkable compared with the values obtained in previous researches conducted with crude extracts or insoluble forms of enzymes. Kinetic parameters, as characterized by the Hill equation, were vmax = 497.2 µM/min, KM = 542.4 µM, and nH = 2.2, suggesting that toluene dioxygenase has at least three cooperative binding sites for toluene. In addition, the use of alternative ferredoxins and reductases was examined. Ferredoxin cloned from CYP153 could transfer electrons to the iron sulfur protein component of toluene dioxygenase. The ferredoxin could be reduced by ferredoxin, rubredoxin, and putidaredoxin reductases of CYP153, alkane-1 monooxygenase, and camphor 5-monooxygenase, respectively. The results provide useful information regarding the effective enzymatic biotreatment of hazardous aromatic hydrocarbon contaminants.


Assuntos
Biodegradação Ambiental , Dioxigenases/química , Ferredoxinas/química , Oxirredutases/metabolismo , Oxigenases/genética , Catálise , Dioxigenases/metabolismo , Monitoramento Ambiental , Cinética , Oxirredução , Oxigenases/metabolismo , Pseudomonas putida/metabolismo , Tolueno/metabolismo
13.
Environ Pollut ; 152(1): 106-15, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17629603

RESUMO

Variations in the soil/sediment organic matter (SOM)-hydrophobic organic contaminant (HOC) bindings upon microbially mediated redox conditions were examined. While the extractability of pyrene associated with soil declined after its biodegradation began during aerobic incubation, its variations were almost constant (+/-3.0-4.4%) during anoxic/anaerobic incubations. The dissolved organic matter released from the soil incubated under highly reduced conditions became more humified and aromatic, had a higher average molecular weight, and was more polydispersed compared to that obtained from oxic incubation, similar to the SOM alterations in the early stage of diagenesis (humification). The concentrations of pyrene in the aqueous phase increased significantly during the soil incubations under highly reduced conditions due to its favorable interaction with the altered DOM. Our results suggest that the microbially mediated redox conditions have significant impacts on SOM and should be considered for the transport, fate, bioavailability, and exposure risk of HOCs in the geo-environments.


Assuntos
Pirenos/química , Microbiologia do Solo , Poluentes do Solo/química , Poluentes Químicos da Água/química , Aerobiose , Anaerobiose , Biodegradação Ambiental , Ecologia , Monitoramento Ambiental/métodos , Substâncias Húmicas , Oxirredução , Tamanho da Partícula , Pirenos/análise , Solo/análise , Poluentes do Solo/análise , Poluentes Químicos da Água/análise
14.
Bioresour Technol ; 259: 268-275, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29571170

RESUMO

A biodegradation facilitator which catalyzes the initial steps of 4-chlorophenol (4-CP) oxidation was prepared by immobilizing multiple enzymes (monooxygenase, CphC-I and dioxygenase, CphA-I) onto a natural inorganic support. The enzymes were obtained via overexpression and purification after cloning the corresponding genes (cphC-I and cphA-I) from Arthrobacter chlorophenolicus A6. Then, the recombinant CphC-I was immobilized onto fulvic acid-activated montmorillonite. The immobilization yield was 60%, and the high enzyme activity (82.6%) was retained after immobilization. Kinetic analysis indicated that the Michaelis-Menten model parameters for the immobilized CphC-I were similar to those for the free enzyme. The enzyme stability was markedly enhanced after immobilization. The immobilized enzyme exhibited a high level of activity even after repetitive use (84.7%) and powdering (65.8%). 4-CP was sequentially oxidized by a multiple enzyme complex, comprising the immobilized CphC-I and CphA-I, via the hydroquinone pathway: oxidative transformation of 4-CP to hydroxyquinol followed by ring fission of hydroxyquinol.


Assuntos
Arthrobacter , Clorofenóis , Bentonita , Estabilidade Enzimática , Enzimas Imobilizadas , Cinética
15.
World J Gastroenterol ; 23(22): 4127-4131, 2017 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-28652666

RESUMO

We present a case of a 56-year-old man with 3 synchronous gastric tumors. The patient presented with melena, and 3 gastric abnormalities were detected on gastroduodenoscopic examination, including a small ulcerative lesion in the gastric antrum, a submucosal mass in the gastric body, and severe erosion in the fundus. Histological examination of biopsy samples yielded respective diagnoses of gastric adenocarcinoma, gastritis, and mucosa-associated lymphoid tissue (MALT) lymphoma. The patient first received medication to eradicate any underlying Helicobacter pylori infection, which might have been a cause of the MALT lymphoma. Four weeks later, after examination of repeat biopsy samples revealed that the MALT lymphoma had resolved, the patient underwent subtotal gastrectomy. Further histological examination of resected tissue confirmed the antrum lesion as adenocarcinoma and the body lesion as schwannoma. To our knowledge, this is the first reported case of synchronous triple primary gastric adenocarcinoma, MALT lymphoma, and schwannoma.


Assuntos
Adenocarcinoma/patologia , Linfoma de Zona Marginal Tipo Células B/patologia , Neoplasias Primárias Múltiplas/patologia , Neurilemoma/patologia , Neoplasias Gástricas/patologia , Adenocarcinoma/cirurgia , Antibacterianos/uso terapêutico , Biópsia , Duodenoscopia , Gastrectomia , Gastroscopia , Humanos , Linfoma de Zona Marginal Tipo Células B/tratamento farmacológico , Masculino , Microscopia Eletrônica , Pessoa de Meia-Idade , Neoplasias Primárias Múltiplas/tratamento farmacológico , Neoplasias Primárias Múltiplas/cirurgia , Neurilemoma/cirurgia , Neoplasias Gástricas/tratamento farmacológico , Neoplasias Gástricas/cirurgia , Resultado do Tratamento
16.
Bioresour Technol ; 240: 123-129, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28343861

RESUMO

In this study, cphC-I and cphB, encoding a putative two-component flavin-diffusible monooxygenase (TC-FDM) complex, were cloned from Arthrobacter chlorophenolicus A6. The corresponding enzymes were overexpressed to assess the feasibility of their utilization for the oxidative decomposition of 4-chlorophenol (4-CP). Soluble CphC-I was produced at a high level (∼50%), and subsequently purified. Since CphB was expressed in an insoluble form, a flavin reductase, Fre, cloned from Escherichia coli was used as an alternative reductase. CphC-I utilized cofactor FADH2, which was reduced by Fre for the hydroxylation of 4-CP. This recombinant enzyme complex exhibited a higher specific activity for the oxidation of 4-CP (45.34U/mg-protein) than that exhibited by CphC-I contained in cells (0.18U/mg-protein). The Michaelis-Menten kinetic parameters were determined as: vmax=223.3µM·min-1, KM=249.4µM, and kcat/KM=0.052min-1·µM-1. These results could be useful for the development of a new biochemical remediation technique based on enzymatic agents catalyzing the degradation of phenolic contaminants.


Assuntos
Arthrobacter , Clorofenóis/metabolismo , Oxigenases de Função Mista , Biodegradação Ambiental , Escherichia coli
17.
Bioresour Technol ; 245(Pt B): 1800-1807, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28522197

RESUMO

This study aimed to clarify the initial 4-chlorophenol (4-CP) biodegradation pathway promoted by a two-component flavin-diffusible monooxygenase (TC-FDM) consisting of CphC-I and CphB contained in Arthrobacter chlorophenolicus A6 and the decomposition function of CphC-I. The TC-FDM genes were cloned from A. chlorophenolicus A6, and the corresponding enzymes were overexpressed. Since CphB was expressed in an insoluble form, Fre, a flavin reductase obtained from Escherichia coli, was used. These enzymes were purified using Ni2+-NTA resin. It was confirmed that TC-FDM catalyzes the oxidation of 4-CP and the sequential conversion of 4-CP to benzoquinone (BQN)→hydroquinone (HQN)→HQL. This indicated that CphC-I exhibits substrate specificity for 4-CP, BQN, and HQN. The activity of CphC-I for 4-CP was 63.22U/mg-protein, and the Michaelis-Menten kinetic parameters were vmax=0.21mM/min, KM=0.19mM, and kcat/KM=0.04mM-1min-1. These results would be useful for the development of a novel biochemical treatment technology for 4-CP and phenolic hydrocarbons.


Assuntos
Arthrobacter , Clorofenóis , Biodegradação Ambiental , Oxigenases de Função Mista
18.
J Am Coll Health ; 55(1): 17-26, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16889311

RESUMO

The sample of students completing the National College Health Assessment (NCHA) Survey at the University of Utah differs from the national reference group for the NCHA 2003 in age, employment, residence, and marital status. The purpose of this study is to determine if the defining characteristics of a commuter school increase the risk for suicidal thoughts. During the fall semester of 2004, the University of Utah implemented a randomized electronic survey assessing the student body's health status in several areas. The authors compared 88 respondents who endorsed seriously considered suicide in the previous 12 months were with the remaining 954 respondents to identify discriminating variables. Those students who seriously considered suicide more likely lived off campus, indicated they were emotionally abused, were in only fair health, experienced being assaulted, experienced unwanted sexual touching, or were not heterosexual. Students who were employed were significantly less likely to consider suicide.


Assuntos
Instituições Acadêmicas , Estudantes/psicologia , Suicídio/psicologia , Meios de Transporte , Adolescente , Adulto , Coleta de Dados , Feminino , Humanos , Masculino , Medição de Risco , Fatores de Risco , Utah
19.
Environ Sci Pollut Res Int ; 23(2): 1015-24, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25655752

RESUMO

The decomposition of various aromatic hydrocarbon intermediates was examined using a recombinant oxidative enzyme immobilized on single-walled carbon nanotubes (SWCNTs). Hydroxyquinol 1,2-dioxygenase (CphA-I), which catalyzes ring cleavage of catechol and its analogues, was obtained from Arthrobacter chlorophenolicus A6 via cloning, overexpression, and subsequent purification. This recombinant enzyme was immobilized on SWCNTs by physical adsorption and covalent coupling in the absence and presence of N-hydroxysuccinimide. The immobilization yield was as high as 52.1%, and a high level of enzyme activity of up to 64.7% was preserved after immobilization. Kinetic analysis showed that the substrate utilization rates (vmax) and catalytic efficiencies (kcat/KM) of the immobilized enzyme for all substrates evaluated were similar to those of the free enzyme, indicating minimal loss of enzyme activity during immobilization. The immobilized enzyme was more stable toward extreme pH, temperature, and ionic strength conditions than the free enzyme. Thus, the oxidative enzyme immobilized on SWCNTs can be used as an effective and stable biocatalyst for the biochemical remediation process if further investigations would be carried out under field conditions.


Assuntos
Enzimas Imobilizadas/metabolismo , Hidrocarbonetos Aromáticos/metabolismo , Nanotubos de Carbono , Oxigenases/metabolismo , Adsorção , Arthrobacter/metabolismo , Biodegradação Ambiental , Dioxigenases/metabolismo , Nanotubos de Carbono/química , Succinimidas , Temperatura
20.
Bioresour Technol ; 210: 61-7, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26818576

RESUMO

This study reports that the obligate anaerobic microorganism, Desulfovibrio desulfuricans, a predominant sulfate-reducing bacterium (SRB) in soils and sediments, can produce nanoscale bacterial appendages for extracellular electron transfer. These nanofilaments were electrically-conductive (5.81S·m(-1)) and allowed SRBs to directly colonize the surface of insoluble or solid electron acceptors. Thus, the direct extracellular electron transfer to the insoluble electrode in the microbial fuel cell (MFC) was possible without inorganic electron-shuttling mediators. The production of nanofilaments was stimulated when only insoluble electron acceptors were available for cellular respiration. These results suggest that when availability of a soluble electron acceptor for SRBs (SO4(2-)) is limited, D. desulfuricans initiates the production of conductive nanofilaments as an alternative strategy to transfer electrons to insoluble electron acceptors. The findings of this study contribute to understanding of the role of SRBs in the biotransformation of various substances in soils and sediments and in the MFC.


Assuntos
Fontes de Energia Bioelétrica/microbiologia , Desulfovibrio desulfuricans/metabolismo , Condutividade Elétrica , Nanopartículas/química , Sulfatos/metabolismo , Desulfovibrio desulfuricans/crescimento & desenvolvimento , Eletrodos , Elétrons , Microscopia de Força Atômica , Oxirredução
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