RESUMO
Reflectance and fluorescence spectroscopies have shown great promise for early detection of epithelial dysplasia. We have developed a clinical reflectance spectrofluorimeter for multimodal spectroscopic diagnosis of epithelial dysplasia. This clinical instrument, the FastEEM, collects white light reflectance and fluorescence excitation-emission matrices (EEM's) within a fraction of a second. In this paper we describe the FastEEM instrumentation, designed for collection of multi-modal spectroscopic data. We illustrate its performance using tissue phantoms with well defined optical properties and biochemicals of known fluorescence properties. In addition, we discuss our plans to develop a system that combines a multi-spectral imaging device for wide area surveillance with this contact probe device.
Assuntos
Carcinoma/diagnóstico , Epitélio/patologia , Análise Espectral/instrumentação , Tecnologia de Fibra Óptica , Humanos , Óptica e Fotônica , Imagens de Fantasmas , Software , Espectrometria de Fluorescência/instrumentaçãoRESUMO
In eukaryotic cells, both soluble transport factors and components of the nuclear pore complex mediate protein and RNA trafficking between the nucleus and the cytoplasm. Here, we investigated whether caspases, the major execution system in apoptosis, target the nuclear pore or components of the nuclear transport machinery. Four nucleoporins, Nup153, RanBP2, Nup214 and Tpr are cleaved by caspases during apoptosis. In contrast, the nuclear transport factors, Ran, importin alpha and importin beta are not proteolytically processed, but redistribute across the nuclear envelope independently and prior to caspase activation. Also, mRNA accumulates into the nucleus before caspases become active. Microinjection experiments further revealed that early in apoptosis, the nucleus becomes permeable to dextran molecules of 70 kD molecular weight. Redistribution of import factors and mRNA, as well as nuclear permeabilisation, occur prior to caspase-mediated nucleoporin cleavage. Our findings suggest that the apoptotic programme includes modifications in the machinery responsible for nucleocytoplasmic transport, which are independent from caspase-mediated degradation of nuclear proteins.
Assuntos
Apoptose , Caspases/metabolismo , Membrana Nuclear/metabolismo , Complexo de Proteínas Formadoras de Poros Nucleares , Proteínas Nucleares/metabolismo , Transporte Ativo do Núcleo Celular/efeitos dos fármacos , Apoptose/efeitos dos fármacos , Inibidores de Caspase , Proteínas de Ligação a DNA/metabolismo , Dactinomicina/farmacologia , Ativação Enzimática/efeitos dos fármacos , Feminino , Células HeLa , Humanos , Imuno-Histoquímica , Carioferinas , Microscopia de Fluorescência , Chaperonas Moleculares , Membrana Nuclear/efeitos dos fármacos , Poro Nuclear/química , Poro Nuclear/efeitos dos fármacos , Poro Nuclear/metabolismo , Permeabilidade/efeitos dos fármacos , Proteínas Proto-Oncogênicas/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Transdução de Sinais/efeitos dos fármacos , Estaurosporina/farmacologia , Proteína ran de Ligação ao GTP/metabolismoRESUMO
The vortex-lattice melting transition in Bi(2)Sr(2)CaCu(2)O(8 + delta) single crystals was studied using in-plane resistivity measurements in magnetic fields tilted away from the c axis to the ab plane. In order to avoid the surface barrier effect which hinders the melting transition in the conventional transport measurements, we used the Corbino geometry of electric contacts. The complete H(c) - H(ab) phase diagram of the melting transition in Bi(2)Sr(2)CaCu(2)O(8 + delta) is obtained for the first time. The c-axis melting field component H(c)(melt) exhibits the novel, stepwise dependence on the in-plane magnetic fields H(ab) which is discussed on the basis of the crossing vortex-lattice structure. The peculiar resistance behavior observed near the ab plane suggests the change of phase transition character from first to second order.
