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1.
Biomech Model Mechanobiol ; 20(3): 1003-1011, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33515313

RESUMO

Stress fibers (SFs) in cells transmit external forces to cell nuclei, altering the DNA structure, gene expression, and cell activity. To determine whether SFs are involved in mechanosignal transduction upon intraluminal pressure, this study investigated the SF direction in smooth muscle cells (SMCs) in aortic tissue and strain in the SF direction. Aortic tissues were fixed under physiological pressure of 120 mmHg. First, we observed fluorescently labeled SFs using two-photon microscopy. It was revealed that SFs in the same smooth muscle layers were aligned in almost the same direction, and the absolute value of the alignment angle from the circumferential direction was 16.8° ± 5.2° (n = 96, mean ± SD). Second, we quantified the strain field in the aortic tissue in reference to photo-bleached markers. It was found in the radial-circumferential plane that the largest strain direction was - 21.3° ± 11.1°, and the zero normal strain direction was 28.1° ± 10.2°. Thus, the SFs in aortic SMCs were not in line with neither the largest strain direction nor the zero strain direction, although their orientation was relatively close to the zero strain direction. These results suggest that SFs in aortic SMCs undergo stretch, but not maximal and transmit the force to nuclei under intraluminal pressure.


Assuntos
Aorta/patologia , Miócitos de Músculo Liso/patologia , Pressão , Fibras de Estresse/patologia , Estresse Mecânico , Animais , Elasticidade , Masculino , Camundongos , Microscopia de Fluorescência por Excitação Multifotônica
2.
Australas Phys Eng Sci Med ; 36(3): 347-54, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23797765

RESUMO

To improve the safety of the use of a power injector for pediatric contrast CT, we newly developed a saline test injection mode for a power injector and investigated its usefulness. We used an injection route and investigated the relationship of the injection pressure to the injection rate of saline and the contrast medium. From this relationship, we investigated it was possible to estimate the change of pressure injection of contrast medium from the pressure change of saline injection. The correlation between the saline test injection pressure and the contrast medium injection pressure was investigated in 64 clinical cases. The detection rate of side effects from the saline test injection was investigated in 473 patients. Regarding the correlation between the injection rate and pressure for both saline and contrast, the pressure rose as the rate increased. The contrast medium injection pressure could be estimated from the correlation observed with saline. The clinical data were obtained had a relationship similar to that with phantom data. The detection rate of side effects from the saline test injection was 4.4% in the clinical cases. In these cases, examinations were completed by re-establishing an injection route or administering hypnotics. Our results suggest that contrast medium pressure can be estimated from a saline test injection, thus aiding in prediction of the risk of injection abnormality. Reactions to injections could be observed in the present study, facilitating the prevention of examination failure. Countermeasures can be taken against the cause of the reaction, and the examination can be performed after confirming the absence of a reaction to injection. Therefore, a saline test injection may be useful in pediatric contrast CT.


Assuntos
Meios de Contraste/administração & dosagem , Meios de Contraste/efeitos adversos , Extravasamento de Materiais Terapêuticos e Diagnósticos/etiologia , Injeções a Jato/efeitos adversos , Injeções a Jato/instrumentação , Cloreto de Sódio/efeitos adversos , Tomografia Computadorizada por Raios X/efeitos adversos , Adolescente , Criança , Pré-Escolar , Desenho de Equipamento , Análise de Falha de Equipamento , Extravasamento de Materiais Terapêuticos e Diagnósticos/diagnóstico por imagem , Extravasamento de Materiais Terapêuticos e Diagnósticos/prevenção & controle , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Pressão , Reprodutibilidade dos Testes , Estudos Retrospectivos , Sensibilidade e Especificidade , Cloreto de Sódio/administração & dosagem , Tomografia Computadorizada por Raios X/instrumentação , Tomografia Computadorizada por Raios X/métodos
3.
Nihon Hoshasen Gijutsu Gakkai Zasshi ; 58(8): 1073-9, 2002 Aug.
Artigo em Japonês | MEDLINE | ID: mdl-12514559

RESUMO

The essential factors for an immobilization device in pediatric CT are 1) absence of artifacts, 2) safety, 3) no disturbance of the patient's sedation, and 4) ease of handling. We evaluated the suitability of a commercially available vacuum-type immobilization device designed for radiation therapy (Vac-Lok) that meets these requisites. There were no artifacts in scans of the water phantom. The device easily immobilized the patient, was quick to release, and was superior to previous immobilization systems, according to replies to a questionnaire administered to physicians, technologists, and nurses. Schedule delays were reduced by using this device to examine sedated patients (up to 1 year of age). Despite these advantages, the device was too small to immobilize both extremities together when examining older patients. In order to overcome this problem, we invented a special immobilization device for pediatric CT. The new device could be applied to taller patients, up to 85 cm in height(the average height of 2-year-old infants), and was able to contribute to efficient utilization of the examination room.


Assuntos
Imobilização , Tomografia Computadorizada por Raios X/instrumentação , Artefatos , Pré-Escolar , Humanos , Lactente , Vácuo
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