RESUMO
Members of the mitogen-activated protein kinase (MAPK) cascade such as extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 are implicated as important regulators of cardiomyocyte hypertrophic growth in culture. However, the role that individual MAPK pathways play in vivo has not been extensively evaluated. Here we generated nine transgenic mouse lines with cardiac-restricted expression of an activated MEK1 cDNA in the heart. MEK1 transgenic mice demonstrated concentric hypertrophy without signs of cardiomyopathy or lethality up to 12 months of age. MEK1 transgenic mice showed a dramatic increase in cardiac function, as measured by echocardiography and isolated working heart preparation, without signs of decompensation over time. MEK1 transgenic mice and MEK1 adenovirus-infected neonatal cardiomyocytes each demonstrated ERK1/2, but not p38 or JNK, activation. MEK1 transgenic mice and MEK1 adenovirus-infected cultured cardiomyocytes were also partially resistant to apoptotic stimuli. The results of the present study indicate that the MEK1-ERK1/2 signaling pathway stimulates a physiologic hypertrophy response associated with augmented cardiac function and partial resistance to apoptotsis.
Assuntos
Sistema de Sinalização das MAP Quinases , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Actinina/metabolismo , Adenoviridae/metabolismo , Fatores Etários , Animais , Animais Recém-Nascidos , Apoptose , Peso Corporal , Cardiomegalia/metabolismo , Caspase 3 , Caspases/metabolismo , Células Cultivadas , Fragmentação do DNA , DNA Complementar/metabolismo , Ecocardiografia , Eletroforese em Gel de Poliacrilamida , Imuno-Histoquímica , Marcação In Situ das Extremidades Cortadas , Leucina/metabolismo , MAP Quinase Quinase 1 , Camundongos , Camundongos Transgênicos , Proteína Quinase 3 Ativada por Mitógeno , Proteína Quinase 8 Ativada por Mitógeno , Miocárdio/metabolismo , Tamanho do Órgão , Plasmídeos/metabolismo , RNA/metabolismo , Ratos , Traumatismo por Reperfusão , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de SinaisRESUMO
The transmission of torquing forces between three types of preadjusted bracket was investigated. 0.022-inch Roth prescription 'A'-Company (stainless steel), Silkon (reinforced polycarbonate), and Allure III (polycrystalline ceramic) brackets were used. A selection of stainless steel archwires were chosen, 0.018 x 0.025, 0.019 x 0.025, and 0.021 x 0.025 inch. The brackets were torqued with respect to the archwire and force v. angular deflection was recorded on an Instron machine. The dimension of angular change was in part dependent on the ability of the bracket to elastically or plastically deform. There were no significant differences between bracket types with the 0.018 x 0.025-inch archwire. 'A'-Company brackets demonstrated a significantly lower resistance to loading compared to Silkon brackets in the 0.019 x 0.025-inch group. The greatest amount of distortion was seen in Silkon brackets with an 0.021 x 0.025-inch archwire. Allure III brackets demonstrated the greatest resistance to loading in all groups. As no apparent distortion under loading is seen in Allure III brackets, it is assumed that the load is largely transmitted to the tooth. Full thickness stainless steel rectangular wires should be avoided with these brackets, in order to prevent overloading.
Assuntos
Análise do Estresse Dentário , Desenho de Aparelho Ortodôntico , Braquetes Ortodônticos , Fios Ortodônticos , Óxido de Alumínio , Análise de Variância , Cerâmica , Elasticidade , Cimento de Policarboxilato , Rotação , Aço Inoxidável , Resistência à TraçãoRESUMO
Planar static frictional phenomena were investigated for two types of ceramic and one type of stainless steel orthodontic bracket against rectangular stainless steel archwire. The brackets studied were 'Starfire' (single crystal aluminium oxide), 'Allure III' (polycrystalline aluminium oxide), and 'Dentaurum' (stainless steel). The investigative parameters were: bracket material, force of ligation and whether the brackets were new or 'worn'. Without exception, both types of ceramic bracket produced greater frictional resistance than the stainless steel brackets throughout testing. At a ligation force of 500 g, the Starfire bracket gave the greatest frictional resistance. At ligation forces of 200 and 50 g, the greatest frictional resistance was seen with Allure III. After a period of simulated wear, frictional resistance of Starfire tended to increase at the greatest ligation load while that of both ceramics decreased slightly at the two lower ligation loads. The ceramic brackets caused abrasive wear of the archwire surfaces and the consequent wear debris may have contributed to the changes in frictional resistance seen with Starfire and Allure III. Dentaurum brackets produced minimal frictional resistance in any test and negligible change with wear.
Assuntos
Óxido de Alumínio/química , Braquetes Ortodônticos , Fios Ortodônticos , Aço Inoxidável/química , Cristalografia , Análise do Estresse Dentário , Teste de Materiais , Movimento , Desenho de Aparelho Ortodôntico , Estresse Mecânico , Propriedades de Superfície , Resistência à TraçãoRESUMO
Skin tests have been applied to 161 asthmatic children seen consecutively at a paediatric respiratory clinic. To demonstrate whether a child's asthma is associated with a positive skin test it is suggested that only four extracts need be applied: house dust, house dust mite (D. farinae), grass pollens and a control.