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1.
Vet Pathol ; 45(2): 207-11, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18424836

RESUMO

A case of xanthogranulomatous inflammation of the small bowel in a 12-year-old male American Staffordshire Terrier is described. Disseminated yellow-white nodules 2 to 3 mm in diameter bulging on the serosal surface of the small bowel, as well as on mesenteric tissue, were detected. Histopathologic examination revealed a nodular collection of foamy cells, mainly involving serosal and muscular layers, associated with necrotic areas, hemorrhages, neovascularization, variable numbers of reactive spindle cells, neutrophils, lymphocytes, plasma cells, and rare multinucleated giant cells. Transmural lymphangectasia and mucosal lymphoplasmacytic inflammation were also observed. Both Oil Red O stain and ultrastructural study revealed lipid droplets in the cytoplasm of foamy cells. Lysozyme immunoreactivity was detected in single as well as in clustered foamy cells, while smooth muscle actin was positive in spindle cells and scattered foamy elements. Lymphangectasia associated with lymphoplasmacytic enteritis suggests a component of lymphatic fluid stasis in the pathogenesis of such lesions.


Assuntos
Doenças do Cão/patologia , Granuloma/veterinária , Enteropatias/veterinária , Xantomatose/veterinária , Animais , Doenças do Cão/cirurgia , Cães , Evolução Fatal , Granuloma/patologia , Granuloma/cirurgia , Histocitoquímica/veterinária , Enteropatias/patologia , Enteropatias/cirurgia , Masculino , Xantomatose/patologia , Xantomatose/cirurgia
2.
Cell ; 101(7): 801-11, 2000 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-10892750

RESUMO

Interactions between transcription factors bound to separate operator sites commonly play an important role in gene regulation by mediating cooperative binding to the DNA. However, few detailed structural models for understanding the molecular basis of such cooperativity are available. The c1 repressor of bacteriophage lambda is a classic example of a protein that binds to its operator sites cooperatively. The C-terminal domain of the repressor mediates dimerization as well as a dimer-dimer interaction that results in the cooperative binding of two repressor dimers to adjacent operator sites. Here, we present the x-ray crystal structure of the lambda repressor C-terminal domain determined by multiwavelength anomalous diffraction. Remarkably, the interactions that mediate cooperativity are captured in the crystal, where two dimers associate about a 2-fold axis of symmetry. Based on the structure and previous genetic and biochemical data, we present a model for the cooperative binding of two lambda repressor dimers at adjacent operator sites.


Assuntos
Conformação Proteica , Proteínas Repressoras/química , Sequência de Aminoácidos , Bacteriófago lambda , Cristalografia por Raios X , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Dados de Sequência Molecular , Ligação Proteica , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Proteínas Virais/química , Proteínas Virais/genética , Proteínas Virais/metabolismo , Proteínas Virais Reguladoras e Acessórias
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