RESUMO
The Shwachman-Diamond Syndrome (SDS) is a disorder arising from mutations in the genes encoding for the Shwachman-Bodian-Diamond Syndrome (SBDS) protein and the GTPase known as Elongation Factor Like-1 (EFL1). Together, these proteins remove the anti-association factor eIF6 from the surface of the pre-60S ribosomal subunit to promote the formation of mature ribosomes. SBDS missense mutations can either destabilize the protein fold or affect surface epitopes. The molecular alterations resulting from the latter remain largely unknown, although some evidence suggest that binding to EFL1 may be affected. We further explored the effect of these SBDS mutations on the interaction with EFL1, and showed that all tested mutations disrupted the binding to EFL1. Binding was either severely weakened or almost abolished, depending on the assessed mutation. In higher eukaryotes, SBDS is essential for development, and lack of the protein results in early lethality. The existence of patients whose only source of SBDS consists of that with surface missense mutations highlights the importance of the interaction with EFL1 for their function. Additionally, we studied the interaction mechanism of the proteins in solution and demonstrated that binding consists of two independent and cooperative events, with domains 2â»3 of SBDS directing the initial interaction with EFL1, followed by docking of domain 1. In solution, both proteins exhibited large flexibility and consisted of an ensemble of conformations, as demonstrated by Small Angle X-ray Scattering (SAXS) experiments.
Assuntos
GTP Fosfo-Hidrolases/metabolismo , Mutação de Sentido Incorreto/genética , Proteínas/genética , Polarização de Fluorescência , Humanos , Cinética , Modelos Biológicos , Fatores de Alongamento de Peptídeos , Ligação Proteica , Domínios Proteicos , Proteínas/química , Proteínas/metabolismo , Ribonucleoproteína Nuclear Pequena U5 , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Espalhamento a Baixo Ângulo , Difração de Raios XRESUMO
Films obtained by casting, starting from conventional emulsions (CE), nanoemulsions (NE) or their gels, which led to different structures, with the aim of explore the relationship between structure and physical properties, were prepared. Sodium caseinate was used as the matrix, glycerol as plasticizer, glucono-delta-lactone as acidulant to form the gels, and TiO2 nanoparticles as reinforcement to improve physical behavior. Structural characterization was performed by SAXS and WAXS (Small and Wide Angle X-ray Scattering, respectively), combined with confocal and scanning electron microscopy. The results demonstrate that the incorporation of the lipid phase does not notably modify the mechanical properties of the films compared to solution films. Films from NE were more stable against oil release than those from CE. Incorporation of TiO2 improved mechanical properties as measured by dynamical mechanical analysis (DMA) and uniaxial tensile tests. TiO2 macroscopic spatial distribution homogeneity and the nanostructure character of NE films were confirmed by mapping the q-dependent scattering intensity in scanning SAXS experiments. SAXS microscopies indicated a higher intrinsic homogeneity of NE films compared to CE films, independently of the TiO2 load. NE-films containing structures with smaller and more homogeneously distributed building blocks showed greater potential for food applications than the films prepared from sodium caseinate solutions, which are the best known films.
Assuntos
Caseínas/química , Nanocompostos/química , Nanopartículas/química , Fenômenos Físicos , Titânio/química , Emulsões/química , Manipulação de Alimentos , Glicerol , Fenômenos Mecânicos , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Permeabilidade , Plastificantes/química , Espalhamento a Baixo Ângulo , Resistência à Tração , Termogravimetria , Difração de Raios XRESUMO
OBJECTIVE: To examine the significance of eccentric hyperpigmentation (EH), central hyperpigmentation (CH), multifocal hyper/hypopigmentation (MH/HP), and the multicomponent pattern (MCP) in melanocytic lesions lacking specific dermoscopic features of melanoma. DESIGN: A total of 3367 benign and malignant melanocytic lesions (n = 341 melanomas, excluding lentigo maligna and lentigo maligna melanoma) were examined to identify those lesions lacking specific dermoscopic features of melanoma but having any of the global patterns of EH, CH, MH/HP, and MCP. SETTING: Dermoscopic images were collected from lesions excised or undergoing sequential digital monitoring from the Sydney Melanoma Diagnostic Centre, a tertiary referral institution located in Sydney, Australia. MAIN OUTCOME MEASURE: The odds ratio (OR) for melanoma of EH, CH, MH/HP, and MCP. RESULTS: While EH (OR, 3.3; 95% confidence interval [CI], 2.5-4.6) and MCP (OR, 15.4; 95% CI, 11.9-19.9) were significant predictors of melanoma when total melanomas vs nevi were analyzed, there was no significant difference between the frequency of any of the global patterns in melanomas vs benign nevi lacking specific dermoscopic features of melanoma. CONCLUSION: Based on our study results and previous prevalence data on these global patterns in benign nevi, we do not believe that lesions with EH or MCP require closer observation than other benign nevi lacking specific dermoscopic features of melanoma.