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Introduction: Tuberculosis (TB) is an infectious disease caused by a bacterium called Mycobacterium tuberculosis (Mtb). Previous studies have primarily focused on the transmissibility of multidrug-resistant (MDR) or extensively drug-resistant (XDR) Mtb. However, variations in virulence across Mtb lineages may also account for differences in transmissibility. In Mtb, polyketide synthase (PKS) genes encode large multifunctional proteins which have been shown to be major mycobacterial virulence factors. Therefore, this study aimed to identify the role of PKS mutations in TB transmission and assess its risk and characteristics. Methods: Whole genome sequences (WGSs) data from 3,204 Mtb isolates was collected from 2011 to 2019 in China. Whole genome single nucleotide polymorphism (SNP) profiles were used for phylogenetic tree analysis. Putative transmission clusters (≤10 SNPs) were identified. To identify the role of PKS mutations in TB transmission, we compared SNPs in the PKS gene region between "clustered isolates" and "non-clustered isolates" in different lineages. Results: Cluster-associated mutations in ppsA, pks12, and pks13 were identified among different lineage isolates. They were statistically significant among clustered strains, indicating that they may enhance the transmissibility of Mtb. Conclusion: Overall, this study provides new insights into the function of PKS and its localization in M. tuberculosis. The study found that ppsA, pks12, and pks13 may contribute to disease progression and higher transmission of certain strains. We also discussed the prospective use of mutant ppsA, pks12, and pks13 genes as drug targets.
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This work aimed to compare the stress distribution and mechanical properties of our bridge combined fixation system and commonly used metal locking plate screw system by finite element analysis and by using the Zwick/Z100 testing machine. In addition, we also investigated the clinical outcome of our bridge combined fixation system for femoral fractures in 59 patients from June 2005 to January 2013. As a result, the stress distribution in the bone plate and screws of metal locking plate screw system during walking and climbing stairs was significantly lower than that of metal locking plate screw system. No significant difference in the displacement was observed between two systems. The equivalent bending stiffness of bridge combined fixation system was significantly lower than that of metal locking plate screw system. There were no significant differences in the bending strength, yield load, and maximum force between two systems. All the cases were followed up for 12-24 months (average 18 months). The X-ray showed bone callus was formed in most patients after 3 months, and the fracture line was faint and disappeared at 6-9 months postoperatively. No serious complications, such as implant breakage and wound infection, occurred postoperatively. According to self-developed standard for bone healing, clinical outcomes were rated as excellent or good in 55 out of 59 patients (success rate: 93.2%). Therefore, our findings suggest that our bridge combined fixation system may be a promising approach for treatment of long-bone fractures.
Assuntos
Fraturas do Fêmur/cirurgia , Fêmur/fisiologia , Fêmur/cirurgia , Fixação Interna de Fraturas/instrumentação , Fixação Interna de Fraturas/métodos , Adulto , Idoso , Fenômenos Biomecânicos/fisiologia , Placas Ósseas , Parafusos Ósseos , Feminino , Análise de Elementos Finitos , Humanos , Masculino , Pessoa de Meia-Idade , Estresse Mecânico , Caminhada/fisiologia , Adulto JovemRESUMO
OBJECTIVE: Growing evidence has shown that vitamin D deficiency can cause lower bone mineral density (BMD) and an increased risk of osteoporosis. Vitamin D receptor (VDR) BsmI polymorphism (rs1544410) can affect BMD variation and circulating osteocalcin levels. To date, a wide range of epidemiological studies have been carried out to evaluate the association between VDR BsmI polymorphism and susceptibility to osteoporosis. Conflicting results, however, were obtained. The aim of this study was to evaluate the effect of VDR BsmI polymorphism on osteoporosis risk using a meta-analysis. METHODS: Twenty-six publications were identified by searching PubMed and Embase databases. The association between VDR BsmI polymorphism and osteoporosis was estimated by calculating pooled odds ratios (ORs) with corresponding 95% confidence intervals (CIs). RESULTS: The bb genotype was associated with a significantly decreased risk of osteoporosis in overall comparison (bb vs. BB: OR=0.61, 95% CI, 0.40-0.92; bb vs. BB/Bb: OR=0.70, 95% CI, 0.52-0.95, respectively). Subgroup analyses showed that the bb genotype had a decreased risk of developing osteoporosis in postmenopausal women (bb vs. BB/Bb: OR=0.68, 95% CI, 0.46-0.98) and Africans (Bb/bb vs. BB: OR=0.18, 95% CI, 0.09-0.37). CONCLUSION: The VDR BsmI polymorphism may have a protective role against the development of osteoporosis.