RESUMO

Myeloid differentiation-2 (MD-2) is an essential component of the CD14-TLR4/MD-2 receptor complex involved in microbial cell wall component recognition during infection. Genetic variations in the MD-2 gene may influence human susceptibility to infectious diseases. To date, a predisposition of MD-2 gene variants to contract tuberculosis has not been reported. We investigated whether MD-2 gene polymorphisms were associated with the development of tuberculosis in a Chinese population. The six common polymorphisms (rs11465996, rs1809442, rs1809441, rs1809440, rs16938754, and rs7842342) within the MD-2 gene promoter region were all detected in 259 patients with tuberculosis and 276 healthy control subjects by DNA sequencing. None of the allelic frequencies, haplotype patterns or genotype distributions of the assayed polymorphisms was found to be significantly different between patients and controls (P > 0.05). We conclude that these gene variants in the MD-2 gene promoter region are not associated with tuberculosis, and apparently do not play a role in susceptibility to tuberculosis in the Chinese population.

Assuntos

Predisposição Genética para Doença/genética , Antígeno 96 de Linfócito/genética , Tuberculose/genética , Adolescente , Adulto , Idoso , Povo Asiático/genética , Feminino , Frequência do Gene/genética , Genótipo , Haplótipos/genética , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo Genético/genética , Regiões Promotoras Genéticas/genética , Adulto Jovem

RESUMO

In the Brazil nut problem (BNP), hard spheres with larger diameters rise to the top. There are various explanations (percolation, reorganization, convection), but a broad understanding or control of this effect is by no means achieved. A theory is presented for the crossover from BNP to the reverse Brazil nut problem based on a competition between the percolation effect and the condensation of hard spheres. The crossover condition is determined, and theoretical predictions are compared to molecular dynamics simulations in two and three dimensions.