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1.
Langmuir ; 32(33): 8436-41, 2016 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-27466084

RESUMO

The pentamode structure is a type of mechanical metamaterial that displays dramatically different bulk and shear modulus responses. In this study, a face-centered cubic (FCC) polymeric microstructure was fabricated by using SU8 negative-type photoresists and multibeam interference exposure. Isotropic plasma etching is used to control the solid-volume fraction; for the first time, we obtained a structure with the minimum solid-volume fraction as low as 15% that still exhibited high structural integrity. Using this method, we reduced the width of atom-to-atom connections by up to 40 nm. We characterize the effect of the connection area on the anisotropy of the mechanical properties using simulations. Nanoindentation measurements were also conducted to evaluate the energy dissipation by varying the connection area. The Young's/shear modulus ratio is 5 times higher for the etched microstructure than that of the bulk SU8 materials. The use of interference lithography may enable the properties of microscale materials to be engineered for various applications, such as MEMS.

2.
J Oral Maxillofac Surg ; 74(11): 2252-2260, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27403878

RESUMO

PURPOSE: Few studies have evaluated the relapse pattern of intraoral vertical ramus osteotomy (IVRO) for the correction of mandibular prognathism with a high angle. The aim of this study was to measure the association between vertical facial types (high and normal mandibular plane angle) and relapse after IVRO for the management of mandibular prognathism. MATERIALS AND METHODS: The retrospective cohort study sample (skeletal Class III patients) was divided into 2 groups according to the angle of the sella-nasion plane relative to the mandibular plane (SN-MP) at the initial examination. Lateral cephalograms were analyzed for the predictor (facial type) and outcome (cephalometric changes over time) variables before surgery, 7 days after surgery, and 12 months after surgery. The 2 groups were matched for sample size (n = 20 in each). Data were analyzed using repeated-measures analysis of variance with Bonferroni correction. RESULTS: The normal-angle group (group N, SN-MP from 27° to 37°) and high-angle group (group H, SN-MP >37°) were not significantly different in terms of gender and age at the initial examination. Seven days after surgery, the mandibles in group H moved 2.5 mm more superiorly than those in group N (P = .013); consequently, the amount of overbite correction in group H was approximately 2 mm greater than that in group N (P = .002). Nevertheless, 12 months after surgery, there was no statistically significant difference in relapse of the maxilla and mandible between the 2 groups. In the 2 groups, the mandible moved approximately 0.7 mm superiorly during retention. CONCLUSIONS: These findings suggest that IVRO is a clinically acceptable and stable treatment modality for mandibular prognathism with a high angle.


Assuntos
Má Oclusão Classe III de Angle/cirurgia , Mandíbula/anatomia & histologia , Osteotomia Sagital do Ramo Mandibular , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Cefalometria , Feminino , Seguimentos , Humanos , Masculino , Mandíbula/cirurgia , Pessoa de Meia-Idade , Recidiva , Estudos Retrospectivos , Resultado do Tratamento , Dimensão Vertical , Adulto Jovem
3.
J Craniofac Surg ; 26(3): e240-4, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25974822

RESUMO

This case report describes the beneficial effects of the interdisciplinary treatment of an adult patient with severe skeletal periodontal problems. A 30-year-old female patient presented with anterior open bite, gummy smile, and facial asymmetry. The patient had chronic generalized severe periodontitis with pathologic maxillary anterior teeth migration and mild intellectual disability. Treatment included 6 months of periodontal treatment, followed by presurgical orthodontic treatment, a Le Fort I osteotomy with anterior segmental osteotomy, a bilateral sagittal split ramus osteotomy, and postsurgical orthodontic treatment. After treatment completion, the patient exhibited functional and aesthetic improvements. Her periodontal condition improved and was maintained after the treatment. Here, we demonstrate a successful treatment outcome in a complicated case following a systematic interdisciplinary approach performed with the correct diagnosis and treatment planning.


Assuntos
Deficiência Intelectual/complicações , Mordida Aberta/terapia , Ortodontia Corretiva/métodos , Osteotomia Sagital do Ramo Mandibular/métodos , Periodontite/terapia , Adulto , Cefalometria , Feminino , Humanos , Mordida Aberta/complicações , Periodontite/complicações
4.
Chem Pharm Bull (Tokyo) ; 62(11): 1119-24, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25196129

RESUMO

2H-[1,2,3]Triazolo[4,5-g]isoquinoline-4,9-diones and 2H-[1,2,3]triazolo[4,5-g]quinoline-4,9-diones were synthesized and tested for in vitro antifungal activity against pathogenic fungi. Many of those synthesized showed potent antifungal activity. Compounds 3a, 3b, 3g, and 3h completely inhibited the growth of all fungal species tested at the MIC level of 0.8-12.5 µg/mL. The results suggest that 2H-[1,2,3]triazolo[4,5-g]isoquinoline-4,9-diones could be antifungal agents.


Assuntos
Antifúngicos/química , Antifúngicos/farmacologia , Fungos/efeitos dos fármacos , Isoquinolinas/química , Isoquinolinas/farmacologia , Triazóis/química , Triazóis/farmacologia , Antifúngicos/síntese química , Desenho de Fármacos , Humanos , Isoquinolinas/síntese química , Testes de Sensibilidade Microbiana , Micoses/tratamento farmacológico , Relação Estrutura-Atividade , Triazóis/síntese química
5.
Am J Orthod Dentofacial Orthop ; 145(1): 72-84, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24373657

RESUMO

Distraction osteogenesis is an alternative treatment option for patients with facial asymmetry and mandibular hypoplasia. New bone is formed between bone segment surfaces that are gradually separated by incremental traction. The purpose of this article is to report the treatment of a 22-year-old man with hemifacial microsomia, facial asymmetry, and a skeletal Class II profile. The patient's left mandibular ramus was lengthened with distraction osteogenesis, and miniscrew-assisted rapid palatal expansion was used to correct the maxillary transverse deficiency. Postoperative orthodontic treatment achieved tooth alignment and closure of the posterior open bite. The total treatment period was 27 months. These therapeutic treatments improved the patient's facial appearance.


Assuntos
Assimetria Facial/cirurgia , Síndrome de Goldenhar/cirurgia , Má Oclusão Classe II de Angle/terapia , Osteogênese por Distração/métodos , Parafusos Ósseos , Cefalometria/métodos , Queixo/anormalidades , Queixo/cirurgia , Estética , Assimetria Facial/terapia , Seguimentos , Síndrome de Goldenhar/terapia , Humanos , Masculino , Mandíbula/anormalidades , Mandíbula/cirurgia , Côndilo Mandibular/anormalidades , Osteotomia Mandibular/métodos , Mordida Aberta/terapia , Desenho de Aparelho Ortodôntico , Técnica de Expansão Palatina/instrumentação , Planejamento de Assistência ao Paciente , Técnicas de Movimentação Dentária/métodos , Adulto Jovem
6.
Am J Orthod Dentofacial Orthop ; 145(4 Suppl): S125-35, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24680021

RESUMO

To reduce a large amount of mandibular setback and to prevent pharyngeal airway space narrowing when correcting a severe anteroposterior skeletal discrepancy, a mandibular step osteotomy is often combined with 2-stage orthognathic surgery. This case report describes a successful 2-stage orthognathic treatment combined with a mandibular step osteotomy. A 20-year-old man had severe mandibular protrusion, facial asymmetry, and macroglossia. Phase 1 surgery included the mandibular step osteotomy and a partial glossectomy; then we performed phase 2 surgery with a 2-piece LeFort I segmental osteotomy and a bilateral intraoral vertical ramus osteotomy to correct the patient's mandibular protrusion and facial asymmetry. The total treatment period was 30 months, and the final result was improvement of the patient's facial appearance.


Assuntos
Má Oclusão Classe III de Angle/cirurgia , Osteotomia Mandibular/métodos , Osteotomia de Le Fort/métodos , Osteotomia Sagital do Ramo Mandibular/métodos , Glossectomia/métodos , Humanos , Masculino , Má Oclusão Classe III de Angle/diagnóstico por imagem , Radiografia , Adulto Jovem
7.
Langmuir ; 29(4): 1192-8, 2013 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-23308367

RESUMO

Inverse opal carbon materials were used as anodes for lithium ion batteries. We applied particulate inverse opal structures and their dispersion in the formation of anode electrodes via solution casting. We prepared aminophenyl-grafted inverse opal carbons (a-IOC), inverse opal carbons with mesopores (mIOC), and bare inverse opal carbons (IOC) and investigated the electrochemical behavior of these samples as anode materials. Surface modification by aminophenyl groups was confirmed by XPS measurements. TEM images showed mesopores, and the specific area of mIOC was compared with that of IOC using BET analysis. A half-cell test was performed to compare a-IOC with IOC and mIOC with IOC. In the case of the a-IOC structure, the cell test revealed no improvement in the reversible specific capacity or the cycle performance. The mIOC cell showed a reversible specific capacity of 432 mAh/g, and the capacity was maintained at 88%-approximately 380 mAh/g-over 20 cycles.

8.
Cyberpsychol Behav Soc Netw ; 26(4): 273-278, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36930840

RESUMO

This study conducted a two-condition between-subjects laboratory experiment (N = 147) to examine the effects of textual disaster news combined with a 360° video in different modes (virtual reality [VR] vs. two dimensional screen) on cognitive/affective empathy and fear. Additionally, the mediating role of presence (social and spatial presence) was considered. Results indicated that the news article presented through an immersive VR mode directly led to greater levels of presence and cognitive empathy but not affective empathy and fear. The effects on social presence further resulted in greater cognitive and affective empathy, not fear. Meanwhile, spatial presence enhanced by VR led to greater levels of emotions (affective empathy and fear) but not cognitive empathy. These findings suggest the dynamic mechanisms of how an immersive VR modality can function as a complementary tool for traditional news to improve audience engagement, which centers on emotion-related outcomes in tandem with cognitive responses.


Assuntos
Desastres , Realidade Virtual , Humanos , Empatia , Emoções
9.
Microbiol Spectr ; 11(4): e0182623, 2023 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-37367300

RESUMO

Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) genes are widely recognized as bacterial adaptive immune systems against invading viruses and bacteriophages. The oral pathogen Streptococcus mutans encodes two CRISPR-Cas loci (CRISPR1-Cas and CRISPR2-Cas), and their expression under environmental conditions is still under investigation. In this study, we investigated the transcriptional regulation of cas operons by CcpA and CodY, two global regulators that contribute to carbohydrate and (p)ppGpp metabolism. The possible promoter regions for cas operons and the binding sites for CcpA and CodY in the promoter regions of both CRISPR-Cas loci were predicted using computational algorithms. We found that CcpA could directly bind to the upstream region of both cas operons, and detected an allosteric interaction of CodY within the same region. The binding sequences of the two regulators were identified through footprinting analysis. Our results showed that the promoter activity of CRISPR1-Cas was enhanced under fructose-rich conditions, while deletion of the ccpA gene led to reduced activity of the CRISPR2-Cas promoter under the same conditions. Additionally, deletion of the CRISPR systems resulted in a significant decrease in fructose uptake ability compared to the parental strain. Interestingly, the accumulation of guanosine tetraphosphate (ppGpp) was reduced in the presence of mupirocin, which induces a stringent response, in the CRISPR1-Cas-deleted (ΔCR1cas) and both CRISPR-Cas-deleted (ΔCRDcas) mutant strains. Furthermore, the promoter activity of both CRISPRs was enhanced in response to oxidative or membrane stress, while the CRISPR1 promoter activity was reduced under low-pH conditions. Collectively, our findings demonstrate that the transcription of the CRISPR-Cas system is directly regulated by the binding of CcpA and CodY. These regulatory actions play a crucial role in modulating glycolytic processes and exerting effective CRISPR-mediated immunity in response to nutrient availability and environmental cues. IMPORTANCE An effective immune system has evolved not only in eukaryotic organisms but also in microorganisms, enabling them to rapidly detect and neutralize foreign invaders in the environment. Specifically, the CRISPR-Cas system in bacterial cells is established through a complex and sophisticated regulatory mechanism involving specific factors. In this study, we demonstrate that the expression of two CRISPR systems in S. mutans can be controlled by two global regulators, CcpA and CodY, which play critical roles in carbohydrate metabolism and amino acid biosynthesis. Importantly, our results show that the expression of the CRISPR-Cas system in S. mutans influences (p)ppGpp production during the stringent response, which is a gene expression regulatory response that aids in environmental stress adaptation. This transcriptional regulation by these regulators enables a CRISPR-mediated immune response in a host environment with limited availability of carbon sources or amino acids, while ensuring efficient carbon flux and energy expenditure to support multiple metabolic processes.


Assuntos
Sistemas CRISPR-Cas , Streptococcus mutans , Streptococcus mutans/genética , Streptococcus mutans/metabolismo , Guanosina Pentafosfato/metabolismo , Regiões Promotoras Genéticas , Frutose/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo
10.
Langmuir ; 28(17): 7033-8, 2012 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-22475456

RESUMO

We investigated the fabrication of inverse opal carbon counter electrodes using a colloidal templating method for DSSCs. Specifically, bare inverse opal carbon, mesopore-incoporated inverse opal carbon, and graphitized inverse opal carbon were synthesized and stably dispersed in ethanol solution for spray coating on a FTO substrate. The thickness of the electrode was controlled by the number of coatings, and the average relative thickness was evaluated by measuring the transmittance spectrum. The effect of the counter electrode thickness on the photovoltaic performance of the DSSCs was investigated and analyzed by interfacial charge transfer resistance (R(CT)) under EIS measurement. The effect of the surface area and conductivity of the inverse opal was also investigated by considering the increase in surface area due to the mesopore in the inverse opal carbon and conductivity by graphitization of the carbon matrix. The results showed that the FF and thereby the efficiency of DSSCs were increased as the electrode thickness increased. Consequently, the larger FF and thereby the greater efficiency of the DSSCs were achieved for mIOC and gIOC compared to IOC, which was attributed to the lower R(CT). Finally, compared to a conventional Pt counter electrode, the inverse opal-based carbon showed a comparable efficiency upon application to DSSCs.

11.
J Craniofac Surg ; 23(6): e531-5, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23172466

RESUMO

Nongrowing adult patients with skeletal open bite have been considered among the most difficult to treat. This case report describes the surgical-orthodontic treatment of a blind 20-year-old woman who presented with skeletal class II malocclusion with vertical maxillary excess, anterior open bite, and transverse maxillary deficiency.After the transverse maxillary deficiency was corrected with miniscrew-assisted rapid palatal expansion, Le Fort I osteotomy with anterior segmental osteotomy and bilateral sagittal split ramus osteotomy with advancement genioplasty were used to correct the vertical maxillary excess and the anterior open bite. The patient's facial appearance was markedly improved, and she achieved a functional and stable occlusion after these treatments.This case report demonstrates the efficiency of miniscrew-assisted rapid palatal expansion for a patient with transverse maxillary deficiency and the benefit of a team approach using effective orthodontic mechanics in orthognathic surgery to correct a severe dentofacial deformity.


Assuntos
Má Oclusão Classe II de Angle/cirurgia , Maxila/anormalidades , Maxila/cirurgia , Mordida Aberta/cirurgia , Parafusos Ósseos , Feminino , Mentoplastia , Humanos , Osteotomia de Le Fort , Osteotomia Sagital do Ramo Mandibular , Técnica de Expansão Palatina , Adulto Jovem
12.
Anal Chem ; 83(9): 3343-51, 2011 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-21466170

RESUMO

Gravitational field-flow fractionation (GrFFF) is a useful technique for fast separation of micrometer-sized particles. Different sized particles are carried at different velocities by a flow of fluid along an unobstructed thin channel, resulting in a size-based separation. They are confined to thin focused layers in the channel thickness where force due to gravity is exactly opposed by hydrodynamic lift forces (HLF). It has been reported that the HLF are a function of various parameters including the flow rate (or shear rate), the size of the particles, and the density and viscosity of the liquid. The dependence of HLF on these parameters offers a means of altering the equilibrium transverse positions of the particles in GrFFF, and hence their elution times. In this study, the effect of the viscosity of the carrier fluid on the elution behavior (retention, zone broadening, and resolution) of micrometer-sized particles in GrFFF was investigated using polystyrene (PS) latex beads as model particles. In order to change the carrier liquid viscosity without affecting its density, various amounts of (hydroxypropyl) methyl cellulose (HPMC) were added to the aqueous carrier liquid. It was found that particles migrate at faster rates as the carrier viscosity is increased, which confirms the dependence of HLF on viscosity. At the same time, particle size selectivity decreased but peak shape and symmetry for the more strongly retained particles improved. As a result, separation was improved in terms of both the separation time and resolution with increase of carrier viscosity. A theoretical model for plate height in GrFFF is also presented, and its predictions are compared to experimentally measured values.

13.
Scand J Trauma Resusc Emerg Med ; 29(1): 145, 2021 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-34602084

RESUMO

BACKGROUND: Sepsis is a life-threatening organ dysfunction and a major healthcare burden worldwide. Although sepsis is a medical emergency that requires immediate management, screening for the occurrence of sepsis is difficult. Herein, we propose a deep learning-based model (DLM) for screening sepsis using electrocardiography (ECG). METHODS: This retrospective cohort study included 46,017 patients who were admitted to two hospitals. A total of 1,548 and 639 patients had sepsis and septic shock, respectively. The DLM was developed using 73,727 ECGs from 18,142 patients, and internal validation was conducted using 7774 ECGs from 7,774 patients. Furthermore, we conducted an external validation with 20,101 ECGs from 20,101 patients from another hospital to verify the applicability of the DLM across centers. RESULTS: During the internal and external validations, the area under the receiver operating characteristic curve (AUC) of the DLM using 12-lead ECG was 0.901 (95% confidence interval, 0.882-0.920) and 0.863 (0.846-0.879), respectively, for screening sepsis and 0.906 (95% confidence interval (CI), 0.877-0.936) and 0.899 (95% CI, 0.872-0.925), respectively, for detecting septic shock. The AUC of the DLM for detecting sepsis using 6-lead and single-lead ECGs was 0.845-0.882. A sensitivity map revealed that the QRS complex and T waves were associated with sepsis. Subgroup analysis was conducted using ECGs from 4,609 patients who were admitted with an infectious disease, and the AUC of the DLM for predicting in-hospital mortality was 0.817 (0.793-0.840). There was a significant difference in the prediction score of DLM using ECG according to the presence of infection in the validation dataset (0.277 vs. 0.574, p < 0.001), including severe acute respiratory syndrome coronavirus 2 (0.260 vs. 0.725, p = 0.018). CONCLUSIONS: The DLM delivered reasonable performance for sepsis screening using 12-, 6-, and single-lead ECGs. The results suggest that sepsis can be screened using not only conventional ECG devices but also diverse life-type ECG machines employing the DLM, thereby preventing irreversible disease progression and mortality.


Assuntos
COVID-19 , Aprendizado Profundo , Sepse , Eletrocardiografia , Humanos , Estudos Retrospectivos , SARS-CoV-2 , Sepse/diagnóstico
14.
Artigo em Inglês | MEDLINE | ID: mdl-33227952

RESUMO

Plasticizers are added to diverse consumer products including children's products. Owing to their potential for endocrine disruption, the use of phthalate plasticizers is restricted in many children's products. In this study, exposure to five phthalate esters (dibutylphthalate, di(2-ethylhexyl) phthalate (DEHP), diethyl phthalate, di-isobutyl phthalate, and diisononyl phthalate (DINP)) and an alternative (di-ethylhexyl adipate) was assessed by the use of children's products based on chemical analysis of 3345 products purchased during 2017 and 2019 in Korea. Plasticizers were found above the detection limits in 387 products, and DEHP and DINP were the two most predominantly detected plasticizers. Deterministic and probabilistic estimation of the margin of exposure at a screening level revealed that the use of children's products might be an important risk factor. However, it is also highly likely that the exposure could be overestimated, because the migration rate was estimated based solely on the content of plasticizers in children's products. Chemical migration is a key process determining the absorption of plasticizers from products; thus, further refinements in experimental determination or model estimation of the migration rate are required.


Assuntos
Exposição Ambiental , Ácidos Ftálicos , Qualidade de Produtos para o Consumidor , Ésteres/análise , Ésteres/química , Humanos , Ácidos Ftálicos/análise , Ácidos Ftálicos/química , Plastificantes/análise , Plastificantes/química , República da Coreia
15.
Artigo em Inglês | MEDLINE | ID: mdl-32942613

RESUMO

Human exposure to microplastics contained in food has become a significant concern owing to the increasing accumulation of microplastics in the environment. In this paper, we summarize the presence of microplastics in food and the analytical methods used for isolation and identification of microplastics. Although a large number of studies on seafood such as fish and shellfish exist, estimating the overall human exposure to microplastics via food consumption is difficult owing to the lack of studies on other food items. Analytical methods still need to be optimized for appropriate recovery of microplastics in various food matrices, rendering a quantitative comparison of different studies challenging. In addition, microplastics could be added or removed from ingredients during processing or cooking. Thus, research on processed food is crucial to estimate the contribution of food to overall human microplastic consumption and to mitigate this exposure in the future.


Assuntos
Plásticos , Poluentes Químicos da Água , Animais , Monitoramento Ambiental , Humanos , Microplásticos , Alimentos Marinhos/análise , Espectroscopia de Infravermelho com Transformada de Fourier , Poluentes Químicos da Água/análise
16.
Scand J Trauma Resusc Emerg Med ; 28(1): 17, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32131867

RESUMO

BACKGROUND: In emergency medical services (EMSs), accurately predicting the severity of a patient's medical condition is important for the early identification of those who are vulnerable and at high-risk. In this study, we developed and validated an artificial intelligence (AI) algorithm based on deep learning to predict the need for critical care during EMS. METHODS: We conducted a retrospective observation cohort study. The algorithm was established using development data from the Korean national emergency department information system, which were collected during visits in real time from 151 emergency departments (EDs). We validated the algorithm using EMS run sheets from two EDs. The study subjects comprised adult patients who visited EDs. The endpoint was critical care, and we used age, sex, chief complaint, symptom onset to arrival time, trauma, and initial vital signs as the predicted variables. RESULTS: The number of patients in the development data was 8,981,181, and the validation data comprised 2604 EMS run sheets from two hospitals. The area under the receiver operating characteristic curve of the algorithm to predict the critical care was 0.867 (95% confidence interval, [0.864-0.871]). This result outperformed the Emergency Severity Index (0.839 [0.831-0.846]), Korean Triage and Acuity System (0.824 [0.815-0.832]), National Early Warning Score (0.741 [0.734-0.748]), and Modified Early Warning Score (0.696 [0.691-0.699]). CONCLUSIONS: The AI algorithm accurately predicted the need for the critical care of patients using information during EMS and outperformed the conventional triage tools and early warning scores.


Assuntos
Inteligência Artificial , Cuidados Críticos , Serviços Médicos de Emergência , Triagem/métodos , Algoritmos , Estudos de Coortes , Aprendizado Profundo , Serviço Hospitalar de Emergência , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , República da Coreia , Estudos Retrospectivos
17.
Microb Drug Resist ; 25(8): 1142-1148, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31161952

RESUMO

The objectives of this study were to evaluate the performance of the BD Phoenix™ M50 system with two antimicrobial susceptibility testing (AST) panels against clinical isolates in South Korea and the accuracy of determining carbapenem and colistin susceptibility compared with reference methods. A total of 825 nonduplicated clinical isolates were included in this study. Bacterial identification was performed using Bruker Biotyper and 16S rDNA sequencing. Antimicrobial susceptibilities were tested by disk diffusion, broth microdilution, and agar dilution methods. AST with the Phoenix system was performed following the manufacturer's instructions. The categorical agreement (CA), very major error (VME), major error (ME), and minor error (mE) rates were calculated for each antibiotic. CA rates between the results of the Phoenix system and reference methods were more than 90% for most antibiotics except for ciprofloxacin in enterococci (82.7%, 163/197) and cefepime in Acinetobacter species (88.9%, 88/99). VME and ME rates were less than 3% for all the antibiotics tested in this study. Minimum inhibitory concentration (MIC) values for carbapenem and colistin determined by the Phoenix system were highly correlated with those of dilution methods, exhibiting 99.2% (384/387), 96.7% (374/387), and 98.5% (129/131) of the agreement rate within onefold dilution difference for imipenem, meropenem, and colistin, respectively. The BD Phoenix M50™ system showed reliable performance for AST in clinical microbiology laboratories and for detecting carbapenem and colistin resistance in Gram-negative clinical isolates.


Assuntos
Antibacterianos/farmacologia , Automação Laboratorial/métodos , Acinetobacter/efeitos dos fármacos , Enterococcus/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana/métodos , RNA Ribossômico 16S/genética , República da Coreia
18.
J Chromatogr A ; 1209(1-2): 206-11, 2008 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-18805537

RESUMO

Gravitational field-flow fractionation (GrFFF) has been shown to be useful for separation and characterization of various types of micrometer-sized particles. It has been recognized however that GrFFF is less versatile than other members of FFF because the external field (Earth's gravity) in GrFFF is relatively weak and is not tunable (constant), which makes the force acting on the particles constant. A few approaches have been suggested to control the force acting on particles in GrFFF. They include (1) changing the angle between the Earth's gravitational field and the longitudinal axis of the channel, and (2) the use of carrier liquid having different densities. In the hyperlayer mode of GrFFF, the hydrodynamic lift force (HLF) also act on particles. The existence of HLF allows other means of changing the force acting on the particles in GrFFF. They include (1) the flow rate programming, or (2) the use of channels having non-constant cross-section. In this study, with polystyrene latex beads used as model particles, the channel angle was varied to study its effect on elution parameters (such as selectivity, band broadening and resolution) in the steric or in the hyperlayer mode of GrFFF. In addition, the effects of the channel thickness and the flow rate on the elution parameters were also investigated. It was found that, in the steric mode, the resolution decreases as the flow rate increases due to increased zone broadening despite of the increase in the selectivity. At a constant volumetric flow rate, both the zone broadening and the selectivity increase as the channel thickness increases, resulting in the net increase in the resolution. It was also found that the retention time decreases as the channel angle increases in both up- and down-flow positions. The zone broadening tends to increase almost linearly with the channel angle, while no particular trends were found in selectivity. As a result, the resolution decreases as the channel angle increases.


Assuntos
Fracionamento por Campo e Fluxo/métodos , Modelos Teóricos
19.
Front Microbiol ; 9: 571, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29651277

RESUMO

This study was carried out to investigate the epidemiological time-course of New Delhi metallo-beta-lactamase- (NDM-) mediated carbapenem resistance in Enterobacteriaceae in South Korea. A total of 146 non-duplicate NDM-producing Enterobacteriaceae recovered between 2010 and 2015 were voluntarily collected from 33 general hospitals and confirmed by PCR. The species were identified by sequences of the 16S rDNA. Antimicrobial susceptibility was determined either by the disk diffusion method or by broth microdilution, and the carbapenem MICs were determined by agar dilution. Then, multilocus sequence typing and PCR-based replicon typing was carried out. Co-carried genes for drug resistance were identified by PCR and sequencing. The entire genomes of eight random selected NDM producers were sequenced. A total of 69 Klebsiella pneumoniae of 12 sequence types (STs), 34 Escherichia coli of 15 STs, 28 Enterobacter spp. (including one Enterobacter aerogenes), nine Citrobacter freundii, four Raoultella spp., and two Klebsiella oxytoca isolates produced either NDM-1 (n = 126), NDM-5 (n = 18), or NDM-7 (n = 2). The isolates co-produced CTX-M-type ESBL (52.1%), AmpCs (27.4%), additional carbapenemases (7.1%), and/or 16S rRNA methyltransferases (4.8%), resulting in multidrug-resistance (47.9%) or extensively drug-resistance (52.1%). Among plasmids harboring blaNDM, IncX3 was predominant (77.4%), followed by the IncFII type (5.8%). Genome analysis revealed inter-species and inter-strain horizontal gene transfer of the plasmid. Both clonal dissemination and plasmid transfer contributed to the wide dissemination of NDM producers in South Korea.

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