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1.
Emerg Infect Dis ; 28(4): 901-903, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35318924

RESUMO

To determine optimal quarantine duration, we evaluated time from exposure to diagnosis for 107 close contacts of severe acute respiratory syndrome coronavirus 2 Omicron variant case-patients. Average time from exposure to diagnosis was 3.7 days; 70% of diagnoses were made on day 5 and 99.1% by day 10, suggesting 10-day quarantine.


Assuntos
COVID-19 , SARS-CoV-2 , COVID-19/diagnóstico , Humanos , Quarentena , República da Coreia/epidemiologia , SARS-CoV-2/genética
2.
Emerg Infect Dis ; 28(4): 898-900, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35171760

RESUMO

In South Korea, a November 2021 outbreak caused by severe acute respiratory syndrome coronavirus 2 Omicron variant originated from 1 person with an imported case and spread to households, kindergartens, workplaces, restaurants, and hospitals, resulting in 11 clusters within 3 weeks. An epidemiologic curve indicated rapid community transmission of the Omicron variant.


Assuntos
COVID-19 , SARS-CoV-2 , COVID-19/epidemiologia , Surtos de Doenças , Humanos , República da Coreia/epidemiologia
3.
Nanomaterials (Basel) ; 10(10)2020 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-33036223

RESUMO

To inhibit Li-dendrite growth on lithium (Li)-metal electrodes, which causes capacity deterioration and safety issues in Li-ion batteries, we prepared a porous polyimide (PI) sponge using a solution-processable high internal-phase emulsion technique with a water-soluble PI precursor solution; the process is not only simple but also environmentally friendly. The prepared PI sponge was processed into porous PI separators and used for Li-metal electrodes. The physical properties (e.g., thermal stability, liquid electrolyte uptake, and ionic conductivity) of the porous PI separators and their effect on the Li-metal anodes (e.g., self-discharge and open-circuit voltage properties after storage, cycle performance, rate capability, and morphological changes) were investigated. Owing to the thermally stable properties of the PI polymer, the porous PI separators demonstrated no dimensional changes up to 180 °C. In comparison with commercialized polyethylene (PE) separators, the porous PI separators exhibited improved wetting ability for liquid electrolytes; thus, the latter improved not only the physical properties (e.g., improved the electrolyte uptake and ionic conductivity) but also the electrochemical properties of Li-metal electrodes (e.g., maintained stable self-discharge capacity and open-circuit voltage features after storage and improved the cycle performance and rate capability) in comparison with PE separators.

4.
Biomaterials ; 25(18): 4163-73, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15046906

RESUMO

The objectives of this study were (1) to develop a three-dimensional collagen/chitosan/glycosaminoglycan (GAG) scaffold in combination with transforming growth factor-beta1 (TGF-beta 1)-loaded chitosan microspheres, and (2) to evaluate the effect of released TGF-beta 1 on the chondrogenic potential of rabbit chondrocytes in such scaffolds. TGF-beta 1 was loaded into chitosan microspheres using an emulsion-crosslinking method. The controlled release of TGF-beta 1, as measured by enzyme-linked immunosorbent assay (ELISA), was monitored for 7 days. The porous scaffolds containing collagen and chitosan were fabricated by using a freeze drying technique and crosslinked using 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide (EDC) in the presence of chondroitin sulfate (CS), as a GAG component. The TGF-beta 1 microspheres were encapsulated into the scaffold at a concentration of 10 ng TGF-beta 1/scaffold and then chondrocytes were seeded in the scaffold and incubated in vitro for 3 weeks. Both proliferation rate and glycosaminoglycan (GAG) production were significantly higher in the TGF-beta 1 microsphere-incorporated scaffolds than in the control scaffolds without microspheres. Extracellular matrix staining by Safranin O and immunohistochemistry for type II collagen were elevated in the scaffold with TGF-beta 1 microspheres. These results suggest that TGF-beta 1 microspheres when incorporated into a scaffold have the potential to enhance cartilage formation.


Assuntos
Condrócitos/citologia , Condrócitos/fisiologia , Materiais Revestidos Biocompatíveis/administração & dosagem , Sistemas de Liberação de Medicamentos/métodos , Matriz Extracelular/química , Engenharia Tecidual/métodos , Fator de Crescimento Transformador beta/administração & dosagem , Animais , Cartilagem Articular/citologia , Cartilagem Articular/efeitos dos fármacos , Cartilagem Articular/fisiologia , Divisão Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Quitosana/química , Condrócitos/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/química , Colágeno/química , Preparações de Ação Retardada/administração & dosagem , Preparações de Ação Retardada/química , Glicosaminoglicanos/química , Teste de Materiais , Microesferas , Porosidade , Coelhos , Propriedades de Superfície , Fator de Crescimento Transformador beta/química
5.
Arthritis Rheum ; 50(8): 2531-8, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15334467

RESUMO

OBJECTIVE: To investigate the in vivo effects of dehydroepiandrosterone (DHEA) on knee joints during the development of experimentally induced osteoarthritis (OA). METHODS: Twenty-two mature NZW rabbits underwent bilateral anterior cruciate ligament transection (ACLT) and received 0.3-ml intraarticular injections of DHEA (at a concentration of 100 microM in phosphate buffered saline) and control solution in the right and left knees, respectively, beginning 4 weeks after ACLT and continuing once weekly for 5 weeks. All animals were killed 9 weeks after surgery, and the knee joints were assessed by gross morphologic, histologic, histomorphometric, and biochemical methods. RESULTS: Gross morphologic inspection following India ink application showed that the right femoral condyles, which received DHEA, demonstrated less severe cartilage damage than did the contralateral condyles. The thickness, area, and roughness of the DHEA-treated femoral condyles provided evidence of a cartilage-protecting effect of DHEA following ACLT. These results were supported by gene expression analysis. Messenger RNA expression of a proinflammatory cytokine, interleukin-1beta, and catabolic enzymes, matrix metalloproteinases 1 and 3, was reduced in the cartilage of the DHEA-treated knee joints, and expression of tissue inhibitor of metalloproteinase 1 was increased. CONCLUSION: Results of the present study demonstrate a cartilage-protecting effect of DHEA during the development of OA following ACLT in a rabbit model.


Assuntos
Cartilagem Articular/efeitos dos fármacos , Desidroepiandrosterona/farmacologia , Osteoartrite do Joelho/patologia , Animais , Lesões do Ligamento Cruzado Anterior , Cartilagem Articular/metabolismo , Cartilagem Articular/patologia , Desidroepiandrosterona/administração & dosagem , Interleucina-1/análise , Metaloproteases/análise , Coelhos
6.
Artif Organs ; 28(9): 829-39, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15320946

RESUMO

The objectives of this study were (1) to develop a three-dimensional chitosan scaffold in combination with transforming growth factor-beta1 (TGF-beta1)-loaded chitosan microspheres and (2) to evaluate the effect of the TGF-beta1 release on the chondrogenic potential of rabbit chondrocytes in the scaffolds. TGF-beta1 was loaded into chitosan microspheres using an emulsion-crosslinking method, resulting in spherical shapes with a size ranging from 0.3 to 1.5 microm. Controlled release of TGF-beta1, as measured by enzyme-linked immunosorbent assay (ELISA), was observed with chitosan microspheres over 7 days. Chitosan solutions (2% and 3%) were fabricated into two types of scaffolds with different pore morphologies and mechanical properties using a freeze-drying technique, with the result that scaffold with higher concentrations showed smaller pores and lower porosity, leading to a much stronger scaffold. The TGF-beta1 microspheres were incorporated into the scaffolds at a concentration of 10 ng TGF-beta1/scaffold and then chondrocytes seeded into each scaffold and incubated in vitro for 2 weeks. The 2% chitosan scaffolds showed higher cell attachment levels than the 3% chitosan scaffolds (P < 0.01), regardless of the TGF-beta1 microspheres. Both the proliferation rate and glycosaminoglycan (GAG) production were significantly higher for scaffolds incorporating TGF-beta1 microspheres than for the control scaffolds without microspheres 10 days after incubation. Extracellular matrix staining by Safranin O and immunohistochemistry for type II collagen both significantly increased in scaffolds containing TGF-beta1 microspheres. These results suggest that the TGF-beta1 microsphere incorporated in scaffolds have the potential to enhance cartilage formation.


Assuntos
Quitosana/administração & dosagem , Quitosana/metabolismo , Condrócitos/efeitos dos fármacos , Condrócitos/metabolismo , Microesferas , Fator de Crescimento Transformador beta/administração & dosagem , Fator de Crescimento Transformador beta/metabolismo , Animais , Materiais Biocompatíveis/administração & dosagem , Materiais Biocompatíveis/metabolismo , Cartilagem/efeitos dos fármacos , Técnicas de Cultura de Células , Ensaio de Imunoadsorção Enzimática , Coelhos , Fatores de Tempo , Engenharia Tecidual/métodos , Fator de Crescimento Transformador beta1
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