Spatiotemporal distribution of ground-level ozone in China at a city level.

In recent years, ozone (O3) pollution in China has shown a worsening trend. Due to the vast territory of China, O3 pollution is a widespread and complex problem. It is vital to understand the current spatiotemporal distribution of O3 pollution in China. In this study, we collected hourly data on O3 concentrations in 338 cities from January 1, 2016, to February 28, 2019, to analyze O3 pollution in China from a spatiotemporal perspective. The spatial analysis showed that the O3 concentrations exceeded the limit in seven geographical regions of China to some extent, with more serious pollution in North, East, and Central China. The O3 concentrations in the eastern areas were usually higher than those in the western areas. The temporal analysis showed seasonal variations in O3 concentration, with the highest O3 concentration in the summer and the lowest in the winter. The weekend effect, which occurs in other countries (such as the USA), was found only in some cities in China. We also found that the highest O3 concentration usually occurred in the afternoon and the lowest was in the early morning. The comprehensive analysis in this paper could improve our understanding of the severity of O3 pollution in China.

Mining sequential patterns of PM2.5 pollution between 338 cities in China.

Serious PM2.5 air pollution has persistently plagued and endangered most urban areas in China in recent years, and targeted policies are necessary to improve urban air quality ranging from macro policy (national level) to medium policy (city level) to micro policy (site specific). However, the macro-pattern study of air pollution between Chinese cities is inadequate, and not conducive to the formulation of macro-policy. To bridge this gap, we applied a sequential pattern mining algorithm to analyze the spatial-temporal patterns of PM2.5 pollution across Chinese cities during the period 2015 to 2018. The sequential patterns were collected from three levels of granularity on geographic areas and ten temporal scenarios covering time intervals from 10 to 100 h. Many underlying associative relationships were revealed between different cities by the mined patterns. The patterns were heterogeneous and presented five characteristics (i.e., clustering, symmetry, imbalance, decay, and stability). Each of the urban areas under investigation at different granularities was analyzed to identify the occurrence of associative relationships between it and other urban areas; moreover, we determined the degree of severity of such relationships. Our research results provide solid data that can be used as a reference by the various levels of Chinese governments for decision-making; overall, they can be used to improve the design of joint policies to prevent and control PM2.5 pollution in Chinese urban areas.

Detection of Serotype Distribution and Drug Resistance of Streptococcus Pneumoniae Isolated From Pediatric Patients.

OBJECTIVE: To analyze the serotype distribution and drug resistance of Streptococcus pneumoniae isolated from pediatric patients in a Chinese hospital. METHODS: From October 2011 to May 2014, we collected 284 isolates (including 217 noninvasive and 67 invasive strains). We tested the antimicrobial susceptibility of these specimens using the Epsilomer test and disk diffusion method, and the expression of macrolide resistant genes ermB and mefA by polymerase chain reaction. RESULTS: The most common serotype for 217 noninvasive strains was 19F (31.3%). The coverage rates of the 7-, 10-, and 13-valent pneumococcal conjugate vaccines (PCV7, PCV10, and PCV13) were 53.9%, 53.9%, and 86.2%, respectively. For 67 invasive strains, the most common serotype was 23F (22.4%). The coverage rates of PCV7, PCV10, and PCV13 for invasive strains were 77.6%, 82.1%, and 91.0%, respectively. The susceptibility of strains isolated from nonmeningitis specimens to penicillin (PEN) was 97.2%. The rate of multidrug resistance in 284 isolates was 98.7%. All of these isolates were resistant to erythromycin (ERY) and had the ermB gene; 38.6% of those isolates had the mefA gene. CONCLUSIONS: Compared with PCV7 and PCV10, the coverage rate of PCV13 was relatively higher for the S. pneumoniae isolates from pediatric patients. This finding suggests that PCV13 probably plays the strongest role in prevention of pneumococcal diseases and control of multidrug resistance. Because pneumococci were sensitive to PEN, this drug is still the preferred choice for clinical treatment of pediatric pneumococcal diseases.

Identification and molecular characterization of Escherichia coli blaSHV genes in a Chinese teaching hospital.

Escherichia coli (E. coli) commonly reside in human intestine and most E. coli strains are harmless, but some serotypes cause serious food poisoning. This study identified and molecularly characterized blaSHV genes from 490 E. coli strains with multi-drug resistance in a hospital population. PCR and molecular cloning and southern blot were performed to assess functions and localizations of this resistant E. coli gene and the pulsed-field gel electrophoresis (PFGE) was utilized to demonstrate the clonal relatedness of the positive E. coli strains. The data showed that 4 of these 490 E. coli strains (4/499, 0.8%) carried blaSHV genes that included EC D2485 (blaSHV-5), EC D2487 (blaSHV-5), EC D2684 (blaSHV-11) and EC D2616 (blaSHV-195, a novel blaSHV). Analysis of blaSHV open-reading frame showed that blaSHV-5 had a high hydrolysis activity to the broad-spectrum penicillin (ampicillin or piperacillin), ceftazidime, ceftriaxone, cefotaxime and aztreonam. blaSHV-195 and blaSHV-11 had similar resistant characteristics with high hydrolysis activities to ampicillin and piperacillin, but low activities to cephalosporins. Moreover, the two blaSHV-5 genes were located on a transferable plasmid (23kb), whereas the other two blaSHV variants (blaSHV-11 and blaSHV-195) seemed to be located in the chromosomal material. Both EC D2485 and EC D2487 clones isolated in 2010 had the same DNA finger printing profile and they might be the siblings of clonal dissemination. The data from the current study suggest that the novel blaSHV and clonal dissemination may be developed, although blaSHV genes were infrequently identified in this hospital population. The results of the work demonstrate the necessity for molecular surveillance in tracking blaSHV-producing strains in large teaching hospital settings and emphasize the need for epidemiological monitoring.

Correlation of PDK1 expression with clinicopathologic features and prognosis of hepatocellular carcinoma.

OBJECTIVE: To explore the clinical significance of 3-phosphoinositide-dependent protein kinase-1 (PDK1) expression in hepatocellular carcinoma (HCC) and its association with clinicopathologic features and prognosis in HCC patients. MATERIALS AND METHODS: A total of 128 HCC patients who received radical resection were enrolled from Wenling Maternal and Child Health Care Hospital between May 2005 and December 2008, and tumor and adjacent tissue samples were collected. Expression of PDK1 was detected by immunohistochemistry method. Correlation of PDK1 expression with clinicopathological features and prognosis was determined by Spearman's correlation analysis. Impact of expression of PDK1 on overall survival and recurrence was determined by Kaplan-Meier analysis. RESULTS: Immunohistochemistry results showed that PDK1 expression in HCC tissues was significantly higher than that in the corresponding adjacent cancer tissues. Univariate analysis showed that PDK1 messenger RNA expression can predict time to recurrence with diagnostic significance (P=0.001). Univariate analysis showed that alpha-fetoprotein level, tumor number, tumor encapsulation, microvascular invasion, and tumor-node-metastasis stage were also unfavorable prognostic variables for recurrence (P<0.05). Kaplan-Meier analysis showed that overexpression of PDK1 correlates with significantly shorter postoperative overall survival and higher recurrence rates (hazard ratio =2.68; 95% confidence interval: 2.46-4.42, P=0.001) in HCC patients after curative resection. CONCLUSION: Our study indicated that PDK1 may serve as a candidate pro-oncogene and a potential prognostic biomarker for HCC.