[Characteristics of amino acid metabolism in myeloid-derived suppressor cells in septic mice].

OBJECTIVE: To explore the amino acid metabolomics characteristics of myeloid-derived suppressor cells (MDSCs) in mice with sepsis induced by the cecal ligation and puncture (CLP). METHODS: The sepsis mouse model was prepared by CLP, and the mice were randomly divided into a sham operation group (sham group, n = 10) and a CLP model group (n = 10). On the 7th day after the operation, 5 mice were randomly selected from the surviving mice in each group, and the bone marrow MDSCs of the mice were isolated. Bone marrow MDSCs were separated to measure the oxygen consumption rate (OCR) by using Agilent Seahorse XF technology and to detect the contents of intracellular amino acids and oligopeptides through ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) technology. Different metabolites and potential biomarkers were analyzed by univariate statistical analysis and multivariate statistical analysis. The major metabolic pathways were enriched using the small molecular pathway database (SMPDB). RESULTS: The proportion of MDSCs in the bone marrow of CLP group mice (75.53% ± 6.02%) was significantly greater than that of the sham group (43.15%± 7.42%, t = 7.582, P < 0.001), and the basal respiratory rate [(50.03±1.20) pmol/min], maximum respiration rate [(78.07±2.57) pmol/min] and adenosine triphosphate (ATP) production [(25.30±1.21) pmol/min] of MDSCs in the bone marrow of CLP group mice were significantly greater than the basal respiration rate [(34.53±0.96) pmol/min, (t = 17.41, P < 0.001)], maximum respiration rate [(42.57±1.87) pmol/min, (t = 19.33, P < 0.001)], and ATP production [(12.63±0.96) pmol/min, (t = 14.18, P < 0.001)] of sham group. Leucine, threonine, glycine, etc. were potential biomarkers of septic MDSCs (all P < 0.05). The increased amino acids were mainly enriched in metabolic pathways, such as malate-aspartate shuttle, ammonia recovery, alanine metabolism, glutathione metabolism, phenylalanine and tyrosine metabolism, urea cycle, glycine and serine metabolism, ß-alanine metabolism, glutamate metabolism, arginine and proline metabolism. CONCLUSION: The enhanced mitochondrial oxidative phosphorylation, malate-aspartate shuttle and alanine metabolism in MDSCs of CLP mice may provide raw materials for mitochondrial aerobic respiration, thereby promoting the immunosuppressive function of MDSCs. Blocking the above metabolic pathways may reduce the risk of secondary infection in sepsis and improve the prognosis.

[Accuracy of Xpert® MTB/RIF for the detection of tuberculosis and rifampicin-resistance tuberculosis in China: A systematic review and meta-analysis].

OBJECTIVE: To systematically review the diagnostic accuracy of Xpert® Mycobacterium tuberculosis/rifampicin (Xpert® MTB/RIF) for the detection of active tuberculosis (TB) and rifampicin-resistance TB in Chinese patients. METHODS: Four Chinese databases (SinoMed, CNKI, WanFang database, and VIP) and three English databases (PubMed, Embase, and The Cochrane Library) were searched from January 1, 2000 to September 15, 2017, to identify diagnostic tests about the accuracy of Xpert® MTB/RIF in Chinese patients. Two investigators screened the articles and extracted the information independently, and then the quality of each included study was evaluated by Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2. Bivariate random-effects meta-analysis was conducted to pool the sensitivity and specificity. In addition, subgroup analyses were performed based on patient type (TB patient and TB suspected patient), sample type (sputum, bronchoalveolar lavage fluid and others). All statistical analyses were conducted with Stata version 13.0. RESULTS: A total of 47 articles were included in this systematic review. Most of them (38 articles) were in Chinese and only 9 articles were in English. All the articles were published during 2014 to 2017, and the sample size ranged from 31 to 3 151. Forty articles including 42 comparisons about TB were finally included with the pooled sensitivity of 0.94 (95%CI: 0.92, 0.95) and the pooled specificity of 0.87 (95%CI: 0.84, 0.91). Subgroup analysis showed that different patient and specimen types had no significant differences on sensitivity, but the specificity of sputum group was higher than that of bronchoalveolar lavage fluid. As for the detection of rifampicin-resistant TB, 33 articles (38 comparisons) were analyzed, the pooled sensitivity and specificity were 0.92 (95%CI: 0.89, 0.94) and 0.98 (95%CI: 0.97, 0.99) respectively. There were no significant differences between the patient and specimen in the subgroup analyses. The Deeks funnel plot showed a possible publication bias for detecting active tuberculosis (P=0.08) and no publication bias for rifampicin-resistant TB (P=0.24). The likelihood ratio scatter gram showed that in clinical applications, Xpert® MTB/RIF had a good diagnostic ability for detecting active tuberculosis, and it had good clinical diagnostic value in detecting rifampicin-resistant TB. CONCLUSION: Xpert® MTB/RIF has good sensitivity and specificity in detecting TB and rifampicin-resistant TB in Chinese people. In particular, it has good clinical value in diagnosing rifampicin-resistance TB.

[Epidemiological study of bone and joint injury based on urban medical insurance database].

OBJECTIVE: To estimate the prevalence rate of bone and joint injury in China and to describe the three-dimension distribution of the disease (area, time and people). METHODS: Based on a cross-sectional design, a retrospective study was conducted by using Chinese basic medical insurance database from January 1, 2013 to December 31, 2017 to analyze the epidemiological characteristics of bone and joint injury. The prevalence rate of bone and joint injury in each city was calculated, and then using meta-analyses to estimate the pooled prevalence of each area and the whole country. The pooled prevalence rates were compared among the different groups of populations, in terms of geographical area, time and population characteristics (age and gender). RESULTS: A total of 28 419 264 subjects were included in this study, including 705 793 patients with bone and joint injury. From 2013 to 2017, in Chinese basic medical insurance database, the overall prevalence rate of bone and joint injury was 141.5(95%CI: 90.4－203.7) per 10 000 population, and the prevalence rates of non-specific or polyarticular disease, knee disease, and shoulder disease were 101.6 (95%CI: 63.5－148.4)per 10 000 population, 22.5(95%CI:15.1－31.4)per 10 000 population and 10.9 (95%CI: 6.4－16.4)per 10 000 population. The prevalence rates varied across the areas, the highest rate was observed in North China, with the prevalence of 310.6 (95%CI: 12.6－989.7) per 10 000 population, and the lowest rate was observed in Southwest China, with the prevalence of 59.0 (95%CI: 37.5－85.2) per 10 000 population. The prevalence rate of bone and joint injury increased over the study period, from 111.1 (95%CI: 56.0－182.5)per 10 000 population in 2013 to 175.5 (95%CI: 116.8－245.5)per 10 000 population in 2017. The prevalence of bone and joint injury in the female population was 149.1 (95%CI: 94.2－215.9) per 10 000 population, which was higher than that of men [133.6(95%CI: 86.2－190.9) per 10 000 population]. The higher prevalence of knee disease, unspecified or polyarticular disease, and bone and joint injury were observed in people aged 60 years and older, while the prevalence of shoulder disease peaked in 40－59 years old people [20.6 (95%CI: 12.5－30.5) per 10 000 population]. CONCLUSION: This study reported a relative low prevalence of bone and joint injury in China from 2013 to 2017. The prevalence increased over the study period, and the highest prevalence rate was observed in North China. The prevalence rate showed differences among different groups of populations, and higher rates were observed in females and people aged 60 years and older.

Temperature effects on atomic pair distribution functions of melts.

Using molecular dynamics simulations, we investigate the temperature-dependent evolution of the first peak position/shape in pair distribution functions of liquids. For metallic liquids, the peak skews towards the left (shorter distance side) with increasing temperature, similar to the previously reported anomalous peak shift. Making use of constant-volume simulations in the absence of thermal expansion and change in inherent structure, we demonstrate that the apparent shift of the peak maximum can be a result of the asymmetric shape of the peak, as the asymmetry increases with temperature-induced spreading of neighboring atoms to shorter and longer distances due to the anharmonic nature of the interatomic interaction potential. These findings shed light on the first-shell expansion/contraction paradox for metallic liquids, aside from possible changes in local topological or chemical short-range ordering. The melts of covalent materials are found to exhibit an opposite trend of peak shift, which is attributed to an effect of the directionality of the interatomic bonds.

Parallel, self-organizing, hierarchical neural networks with continuous inputs and outputs.

Parallel, self-organizing, hierarchical neural networks (PSHNN's) are multistage networks in which stages operate in parallel rather than in series during testing. Each stage can be any particular type of network. Previous PSHNN's assume quantized, say, binary outputs. A new type of PSHNN is discussed such that the outputs are allowed to be continuous-valued. The performance of the resulting networks is tested in the problem of predicting speech signal samples from past samples. Three types of networks in which the stages are learned by the delta rule, sequential least-squares, and the backpropagation (BP) algorithm, respectively, are described. In all cases studied, the new networks achieve better performance than linear prediction. A revised BP algorithm is discussed for learning input nonlinearities. When the BP algorithm is to be used, better performance is achieved when a single BP network is replaced by a PSHNN of equal complexity in which each stage is a BP network of smaller complexity than the single BP network.