Objective To study the epidemiology of mycoplasma pneumonia (MP) infection in children and its relationship to meteorological conditions in Guilin. Methods Total of 1 342 hospitalized children with respiratory tract infections from Janu-ary 2011 to December 2012 were recruited, and the serum levels of mycoplasma pneumoniae antibody Ig (MP-Ig) were measured. Meanwhile, monthly meteorological conditions were collected. The relationships between the MP-Ig detection rates and meteoro-logical conditions were analyzed by multiple linear regression analysis. Results The total detection rate of MP-Ig was 23.2%with positive rates as 5.51%, 28.99%, 37.31%and 44.97%for 0-1, 1-3, 3-6 and>6 year-old groups respectively (P<0.01). The positive rate of female was higher than that of male with signiifcant difference (30.08%vs 19.05%, P<0.01). The positive rate of spring, summer, autumn and winter were 18.89%, 17.39%, 23.83%and 33.05%individually (P<0.01). Negative correlation was found be-tween detection rate of MP-Ig and monthly mean air temperature (P=0.001). Conclusion MP is one of the commonest pathogens of respiratory tract infection in children and mostly seen in elder female children with a higher incidence in winter. The main me-teorological factor is the low temperature that affects MP prevalence.

Objective:To explore if there is premature senescence of chondrocytes in patients with Kashin-Beck disease (KBD) and osteoarthritis.Methods:Five knee cartilage samples of KBD, osteoarthritis and control groups were collected, respectively, from the Second Affiliated Hospital of Xi'an Jiaotong University. DNA was then extracted from cartilage samples and DNA methylation was analyzed by Illumina Infinium HumanMethylation450 BeadChip. At the same time, based on genome-wide methylation data, the online DNA methylation aging clock calculator (https://dnamage.genetics.ucla.edu/home) was used to calculate the DNA methylation age (DNAm age) of samples, and the results were compared with their actual ages.Results:In the comparison between KBD group and control group, 1 212 differentially methylated CpG sites were found, including 497 hypermethylated CpG sites and 715 hypomethylated CpG sites, corresponding to 264 hypermethylated genes and 368 hypomethylated genes, respectively. In the comparison between osteoarthritis group and control group, 656 differentially methylated CpG sites were found, including 343 hypermethylated CpG sites and 313 hypomethylated CpG sites, corresponding to 177 hypermethylated genes and 174 hypomethylated genes, respectively. In the above comparison, 367 overlapped CpG sites (corresponding to 182 genes) were found, which were differentially methylated in both KBD and control groups and osteoarthritis and control groups. The results of DNA methylation aging clock showed that the average age acceleration differences between DNAm age and actual age of KBD, osteoarthritis and control groups were 2.549, 0.017, and - 5.364 years, respectively, the DNAm ages of KBD and osteoarthritis groups were greater than the actual ages.Conclusion:The chondrocytes show premature senescence in both KBD and osteoarthritis.

Based on the concept of “imbalance of qi movement with the latent cancer toxin”， it is believed that the development process of tumor pre-metastatic niche （PMN） could be summarized as tumor derived secretory factors， exosomes and other “cancer toxin”， which latent in the body， were diffusion-prone by means of meridians and membrane-sources. Besides， the latent toxin induced the imbalance of qi movement， especially the distant weakest qi， and the local sweat pore and collateral vessels were blocked， which resulted in phlegm and blood stasis， and the cross-aggregation of poison. We also proposed therapeutic principles of PMN as first regulating qi and then clearing and expelling toxin， and tried to discuss the theoretical model of traditional Chinese medicine for PMN based on the theory of qi regulation and detoxification， aimed at providing ideas for the future theory construction of traditional Chinese medicine prevention and treatment for malignant tumor metastasis.

Objective:To investigate the impact of matrix metalloproteinase 13 (MMP13) and low-density lipoprotein receptor-related protein 1 (LRP1) on autophagy of articular chondrocytes in patients with Kashin-Beck disease (KBD).Methods:Human articular cartilage samples obtained from 4 KBD patients and 4 control subjects were collected from Shaanxi Institute for Endemic Disease Prevention and Control, and the expression levels of MMP13 and LRP1 in cartilage tissue were determined using immunohistochemistry (IHC). Chondrocytes were extracted and cultured in vitro, the mRNA and protein expression levels of LRP1 and the autophagy related genes [Beclin 1 (BECN1), microtubule associated protein 1 light chain 3 (LC3)], cartilage injury related genes [MMP13, caspase-3 (CASP3)], chondrocyte differentiation related genes [collagen type Ⅱ alpha 1 chain (COL2A1), and SRY-box transcription factor 9 (SOX9)] were detected by real-time fluorescence quantitative PCR (qRT-PCR) and Western blot (WB), respectively. Chondrocytes from 3 KBD patients were extracted, and MMP13 gene silencing experiment was performed by RNA interference (RNAi) technology, the mRNA and protein expression levels of the above genes were detected by qRT-PCR and WB, respectively. In addition, the antagonist receptor associated protein (RAP) of LRP1 was used to block the LRP1 of human normal chondrocytes (C28/I2 cells), and qRT-PCR and WB were used to detect the mRNA and protein expression levels of LRP1, chondrocyte autophagy, differentiation and cartilage injury related genes, respectively. Results:The IHC results showed that the expression levels of MMP13 (1.67 ± 0.21, 0.59 ± 0.15, 0.51 ± 0.12) in the surface, middle, and deep layers of cartilage tissue of KBD patients were significantly higher than those of control subjects (0.25 ± 0.03, 0.26 ± 0.04, 0.06 ± 0.01), and the differences were statistically significant ( t = - 11.38, P < 0.001; t = - 3.82, - 6.26, P = 0.019, 0.003). The expression levels of LRP1 (0.10 ± 0.02, 0.03 ± 0.01, 0.17 ± 0.03) were significantly lower than those of control subjects (1.63 ± 0.40, 0.44 ± 0.12, 0.34 ± 0.08), and the differences were statistically significant ( t = 6.61, 5.61, 3.64, P = 0.003, 0.005, 0.022). The mRNA and protein expression levels of MMP13, CASP3, SOX9 in chondrocytes of KBD patients were significantly higher than those of control subjects, and the differences were statistically significant ( P < 0.05). The mRNA expression levels of LRP1, LC3, COL2A1 were significantly lower than those of control subjects, and the differences were statistically significant ( P < 0.05). After silencing the MMP13 gene in chondrocytes of KBD patients, there were no significant differences in the mRNA and protein expression levels of LRP1, BECN1, LC3, CASP3, COL2A1, and SOX9 ( P > 0.05). After blocking LRP1 with RAP, the protein expression levels of LRP1, BECN1, LC3, MMP13, COL2A1 and SOX9 in chondrocytes were significantly lower than those in control group ( P < 0.05). Conclusions:There is no direct correlation between MMP13 and abnormal autophagy of articular chondrocytes in KBD patients. After blocking LRP1, the expression of the autophagy related genes BECN1 and LC3 in chondrocytes is decreased.

Objective Aiming at solving the problems of pain on the anteromedial tibia, tibial component loosening and osteoarthritis progression after unicompartmental knee arthroplasty (UKA), the influence of different geometric shapes of tibial component pegs on stress distributions in tibia was analyzed by finite element method. Methods The finite element models with UKA were established and validated. Geometric shapes of tibial component were designed. Under the same loading condition, the tibial components with double-peg, single-keel, double-keel and cross-star were studied for finite element analysis and compared with intact model, so as to evaluate the influence of tibial component with different shapes on stresses of cortical bone in anteromedial tibia, cancellous bone under tibial component and cartilage in contralateral tibia. Results Compared with the intact model, the peak stress of cortical bone in anteromedial tibia with double-peg, single-keel, double-keel and cross-star tibial components increased by 56.1%, 55.9%, 54.5% and 68-4%, respectively. The peak stress of cancellous bone under tibial component with single-keel and double-keels decreased by 8.1% and 15.6% respectively, while the peak stress of cancellous bone under tibial component with double-peg and cross-star increased by 67-9% and 121-5%, which were higher than the fatigue yield stress of cancellous bone. The peak stress of cartilage in contralateral tibia with double-peg, single-keel, double-keel and cross-star tibial components decreased by 42.1%, 26.6%, 24.2% and 28.5%, respectively. ConclusionsThe load distribution of the medial and lateral tibia changed after UKA operation, and a greater load was observed on the replacement side. Single-keel and double-keel tibial components were more effective in reducing stresses on cortical bone in anteromedial tibia and cancellous bone, while the stress distribution in tibia with single-keel tibial component was closer to that of the intact tibia. The research findings can provide theoretical references for designing single-keel tibial component of unicompartmental knee prosthesis which conforms to better mechanical properties of the knee joint.