[A retrospective cohort study on the correlation between early energy management and bronchopulmonary dysplasia in premature infants]

Objective: To investigate the correlation between early energy supplement and bronchopulmonary dysplasia (BPD) in very preterm and very low birth weight infants. Methods: A retrospective cohort study design was used. A total of 939 preterm infants who were admitted to the Department of Neonatology of the West China Second Hospital of Sichuan University within 24 h after birth from January 2019 to December 2021 were enrolled in the study. They were born with a gestational age of <32 weeks and (or) a birth weight of <1 500 g. Of them, 250 preterm infants who developed BPD were enrolled in the BPD group, and each of them was matched to a preterm infant who did not develop BPD (matched for gestational age and birth weight) in the order of priority after calculating propensity score. Their total energy, enteral energy, parenteral energy, total fluid intake and energy per unit of fluid per week were collected within the first 2 weeks of life. The independent sample t-test or Mann Whitney U test was used for continuous variables, and the χ2 test for between-group comparisons of categorical variables. Univariate and multivariate Logistic regression analyses were used to explore the association between total energy and total fluid and BPD incidence, respectively. The dose-response relationship between parenteral energy and BPD was investigated by a generalized additive model, and the threshold effect of parenteral energy on BPD used a two-piecewise linear regression model. Results: The gestational age was (28.4±1.9) weeks in the BPD group and (29.5±1.3) weeks in the control group; the birth weight was (1 107±258) g in the BPD group and (1 324±261) g in the control group; and there were 140 males (56.0%) and 131 males (52.4%) in each group, respectively. An increase in energy per unit of fluid in the second week of life was associated with a reduced risk of BPD (OR=0.32, 95%CI 0.12-0.84, P=0.021), and an increase in total energy in the second week of life was also associated with a reduced risk of BPD, with total energy of >418-502 kJ/(kg·d) was significantly lower than when total energy was ≤334 kJ/(kg·d) (OR=0.15, 95%CI 0.03-0.85, P=0.033). There was no association between the average total fluid intake and BPD incidence (both P>0.05) in the first and second week. The increase in the proportion of parenteral energy to total energy in the second week of life was associated with an increased incidence of BPD (OR=8.45, 95%CI 2.14-33.32, P=0.003); specifically, the risk of BPD significantly increased when the parenteral energy was ≥305 kJ/(kg·d) (OR=1.02, 95%CI 1.01-1.03, P=0.003). Conclusions: Maintaining a high total energy supply in the early postnatal period in preterm infants may reduce the risk of BPD, but continued reliance on high parenteral energy to meet total energy requirements increases the risk of BPD, so enteral feeds should be initiated as early as possible and maximized as tolerated.

[Analysis of HONO Concentration and Source in Typical Rural Area of North China]

Nitrous acid (HONO) is easily photolyzed with the production of·OH, which plays an important role in the formation of regional secondary pollution. In China, research of HONO observation is concentrated mainly in urban areas and is rarely reported in rural areas. In our study, a one-month HONO field observation was conducted at the Station of Rural Environment, Chinese Academy of Sciences (Dongbaituo Village, Wangdu County, Hebei Province) in November 2017 using the long path absorption photo meter (LOPAP). The concentration, variety characteristics, and budget of HONO was studied. During the observation period, HONO exhibited pronounced diurnal variation with low concentrations in the day and high concentration in the evening. The highest concentration at night was about 3.70×10^-9, and the lowest concentration at noon was about 0.10×10^-9, indicating the presence of a strong source of HONO in rural areas. The CO concentration increased significantly before and after heating, whereas the HONO concentration did not change significantly, indicating that heating combustion contributed less to HONO, Direct emission of motor vehicles at night contributed 23.20% and 31.20% to HONO in polluted and clean weather conditions, respectively, indicating the presence of strong sources of HONO in polluted weather conditions. The average formation rate of HONO at night from homogeneous reaction of·OH and NO could reach 0.40×10^-9 h^-1, which is 0.67 times higher than that of heterogeneous reaction of NO₂ (0.24×10^-9 h^-1), indicating that the homogeneous reaction of·OH and NO is the main source of HONO at night. HONO has a strong unknown source in the daytime with an intensity reaching 1.37×10^-9 h^-1, which contributes about 50% to HONO.

[Characteristics of molecular typing and drug resistance of 67 Salmonella paratyphi A isolated in Zhengzhou from 2013 to 2015]

Objective: To investigate the antimicrobial resistance and pulsed field gel electrophoresis (PFGE) patterns of S.paratyphi A strains in Zhengzhou city isolated from sentinel hospitals in 2013-2015. Methods: According to Salmonella molecular typing and K-B drug susceptibility testing method published by international PulseNet bacterial infectious disease monitoring network and USA Clinical and Laboratory Standards Institute (CLSI2015), we analyzed drug sensitivity and PFGE molecular characteristics of 67 S.paratyphi A strains(11 strains in 2013, 7 strains in 2014, 49 strains in 2015) isolated from blood and stool samples in two sentinel hospitals of fever with rash syndrome surveillance system established in Zhengzhou city in 2013-2015. Results: The results showed 67 strains of S.paratyphi A had different levels of resistance to 13 kinds of antibiotics, 65 strains were multi-drug resistant strains (97.0%), 5 isolates were resistant to 2-3 kinds of antibiotics (7.5%), 41 isolates were resistant to 5-8 kinds of antibiotics (61.2%),11 isolates were resistant to 9-10 kinds of antibiotics(16.4%),8 isolates were resistant to 11-12 kinds of antibiotics(11.9%). 67 strains of S.paratyphi A were divided into 10 molecular patterns(PTYA1-PTYA10) by digestion with XbaⅠ restriction endonuclease and pulsed field gel electrophoresis, each pattern contains 1-48 strains with similarity ranged from 94.31%-100%. PTYA3 contained 48 strains, which was predominant band type; PTYA1, 9 contained 6 strains; PTYA 2, 4, 5, 6, 7, 8, 10 contained 1 strains among them. Conclusion: The status of drug resistance of clinical isolates of S.paratyphi A in Zhengzhou city was rather serious, PFGE patterns showed diversity and dominant characteristics. The PFGE patterns of partial strains and its corresponding anti-drug spectrum have certain relevance and cluster relationship.

[Distribution and molecular type of Salmonella from external environment in Henan province]

Objective: To understand the distribution of Salmonella in external environment in Henan province, and explore the distribution of different serotypes of the Salmonella and their homology. Methods: A total of 4 488 samples were collected form animal dung, meat products and kitchen utensils, and identified by biochemical tests and serotyped by serum agglutination reaction. The predominant serotypes were further typed by PFGE. Results: A total of 324 Salmonella strains were detected in these samples, the detection rate was 7.21%. The 324 Salmonella isolates belonged to 39 serotypes, S. enteritidis (24.07%, 78/324) and S. derby (20.37%, 66/324) were predominant. Forty six strains of S. enteritidis and 30 strains of S. derby were divided into 12 and 17 molecular patterns by digestion with Xba Ⅰ, while chicken and swine were the predominant animal hosts. Conclusions: Serotyping of external environment Salmonella were phenotypically diverse and the serotype of Salmonella from different sources were different. The same clone was prevalent in same area. It is necessary to strengthen supervision and surveillance to ensure food safety.

[Etiology and drug resistance of non-typhi Salmonella in Henan province, 2011-2015]

Objective: To analyze the serotypes and antibiotic resistance phenotypes of non-typhi Salmonella strains in Henan province from 2011 to 2015. Methods: The stool samples were collected from diarrhea patients, and enriched with SBG enrichment broth and the pathogen isolation was conducted with CHROMAgar selective culture medium at 37 ℃ for 18-24 hours using KIA/MIU biochemical action and API20E biochemical system slab to identify Salmonella strains. The serotypes of all the positive strains were detected with SSI Salmonella typing sera. According to K-B drug susceptibility testing method published by USA clinical and Laboratory Standards Institute (CLSI), the antibiotics resistant phenotype of the positive strains were analyzed. Results: A total of 1 351 strains of non-typhi Salmonella were isolated, in which 811 were from males, 540 were from females. The ratio of men to women was 1.5∶1. Children and young adults were mainly affected. The pathogen isolation was mainly in May-October during a year. The 1 351 strains of non-typhi Salmonlla were divided into 58 serotypes. S. enteritidis, S. typhimurium, S. agona, S. derby, S. indiana, S. senftenberg and S. thompson ranked 1^st-7^th. The drug-resistance rate of the 1 351 strains was 46.1% to synthetic broad-spectrum penicillin ampicillin (AMP), 19.5% and 21.2% to the three generation cephalosporin ceftazidime (CAZ) and cefotaxime (CTX), 8.8% to the four generation cephalosporins cefepime (FEP), 58.7% to the one generation of quinolones nalidixic acid (NAL), 14.7% to the three generation fluoroquinolone ciprofloxacin (CIP) and norfloxacin (NOR), 25.0% and 35.6% to aminoglycoside antibiotic gentamicin (GEN) and streptomycin (STR), 35.4% to amphenicols (CHL), 31.7% to sulfonamide trimethoprim (TMP) and 37.8% to tetracycline (TET). Totally 879 strains were multidrug resistant (65.1%): 350 strains were resistant to 3-4 kinds of antibiotics (25.9%), 309 strains were resistant to 5-7 kinds of antibiotics (22.9%), 174 strains were resistant to 8-10 kinds of antibiotics (12.9%) and 48 strains were resistant to 11-12 kinds of antibiotics (3.6%). Conclusion: The serotypes of non-typhi Salmonella strains isolated from Henan province varied, some strains were resistant to 12 kinds of antibiotics commonly used in clinical treatment and the multidrug resistance has become serious.

[The etiological and molecular typing research of diarrheagenic Escherichia coli in Henan province in 2013]

OBJECTIVE

To analyze the distribution and pulsed field gel electrophoresis (PFGE) patterns of five kinds of diarrheagenic Escherichia coli (DEC) in infected diarrhea population of Henan province in 2013.

METHODS

Gathering 1 037 strains of E. coli of 1 037 diarrhea patients from four sentinel hospitals of multi-pathogen monitoring system in Henan province in 2013. Stool samples were cultured with Mac agar plates and using KIA/MIU biochemical action as the preliminary method to identify E. coli strains; preparation of DNA template with thermal cracking method and using multiplex PCR to detect five kinds of DEC. According to molecular typing method published by the international PulseNet bacterial infectious disease monitoring network, the PFGE molecular characteristics of DEC strains were analyzed.

RESULTS

125 DEC positive strains were detected in 1 037 strains of E. coli, the total detection rate was 12.05%. 90 strains were enteroaggregative E.coli (EAEC), detection rate was 8.68% (n=90); 24 strains were enteropathogenic E.coli (EPEC), detection rate was 2.31%; 7 strains were enteroinvasive E.coli (EIEC), detection rate was 0.68%; 4 strains were enterotoxigenic E.coli (ETEC), detection rate was 0.39%; enterohemorrhagic E.coli (EHEC) was not detected. 639 cases of diarrhea samples were collected from male patients, 398 cases were from female patients, 94 positive cases were from male patients, the detection rate was 14.71%.The positive number of female cases were 31 cases, the detection rate was 7.79%. 97 positive cases were detected from 782 countryside cases and 28 positive cases were detected from 255 urban area cases, with detection rate 12.40% and 10.98% respectively. In 125 cases of DEC positive samples, children below 5 years old were 83 cases, accounting for 66.4%; 53 strains of EAEC were divided into 52 molecular patterns by digestion with XbaⅠ and pulsed field gel electrophoresis, each pattern contained 1-2 strains with similarity ranged from 66.3%-100%; 18 strains of EPEC were divided into 18 molecular patterns, each pattern contains 1 strain with similarity ranged from 72.6%-94.8%; 5 strains of EIEC were divided into 5 molecular patterns, each pattern contains 1 strain with similarity ranged from 71.9%-98.5%. 2 strains of ETEC were divided into 2 molecular patterns and similarity below 70%.

CONCLUSION

Through the research we could find that four kinds of DEC as a pathogenic bacteria took an important component in pathogenic spectrum of bacterial diarrhea of Henan province in 2013. Four kinds of DEC carrying different virulence genes and taking multiple PFGE patterns showed diversity and complexity characteristics.

[N2O exchange fluxes from wheat-maize crop rotation system in the North China Plain]

N2O exchange fluxes from the intensively cultivated winter wheat-summer maize crop rotation system in the North China Plain were measured by the static chamber technique under normal fertilization treatment and normal fertilization combined with straw returning treatment. The results indicated that the cumulative emissions of N2O from normal fertilization treatment and normal fertilization combined with straw returning treatment were 7.61 kg x hm(-2) and 12.6 kg x hm(-2), respectively. The increased N2O from the straw returning mainly occurred during the maize growing season. The N2O emission during the maize growing season from the two fertilization treatments accounted for 57% - 86% of the annual N2O cumulative emission, which indicated that the annual emission of N2O mainly occurred during the maize growing season. Total N2O emission after 10 days of each fertilization accounted for about 71% - 88% of the annual emission. It is obvious that the application of existing chemical fertilizers greatly promoted the N2O emissions in the North China Plain.

Effect of pyrene on denitrification activity and abundance and composition of denitrifying community in an agricultural soil

Toxicity of pyrene on the denitrifiers was studied by spiking an agricultural soil with pyrene to a series of concentrations (0-500 mg kg(-1)) followed by dose-response and dynamic incubation experiments. Results showed a positive correlation between potential denitrification activity and copy numbers of denitrifying functional genes (nirK, nirS and nosZ), and were both negatively correlated with pyrene concentrations. Based on the comparison of EC(50) values, denitrifiers harboring nirK, nirS or nosZ gene were more sensitive than denitrification activity, and denitrifiers harboring nirS gene were more sensitive than that harboring nirK or nosZ genes. Seven days after spiking with EC(50) concentration of pyrene, denitrifiers diversity decreased and community composition changed in comparison with the control. Phylogenetic analyses of three genes showed that the addition of pyrene increased the proportion of Bradyrhizobiaceae, Rhodospirillales, Burkholderiales and Pseudomonadales. Some species belonging to these groups were reported to be able to degrade PAHs.

[Measurement of near-UV absorption cross sections of CS2]

The UV-absorption cross sections of CS2 are reported. The absorption spectra were measured by using a diode array spectrometer over the wavelength range of 220-380 nm at room temperature (298 +/- 3)K. The maximum absorption cross section appeared around 315 nm with the value of sigma (315 nm) = 7.184 x 10(-20) cm2 x molecule(-1). The measured data by this study were in good agreement with that reported in the literature, and used to estimate the photolysis of the CS2 in the atmosphere.

[Contribution of isoprene emitted from vegetable to atmospheric formaldehyde in the ambient air of Beijing city]

Methacrolein (MACR) and methyl vinyl ketone (MVK), which are the characteristic products of isoprene photooxidation in the atmosphere, as well as formaldehyde, were determined during March to November of 2006 in the ambient air of Beijing city. Cartridges coated with 2, 4-dinitrophenylhenylhydrazine (DNPH) were used to collect those carbonyls in ambient air and a high pressure liquid chromatography (HPLC) was used for quantification. Distinct amounts of MACR and MVK were detected during vegetable growing seasons from April to October with ambient levels in ranges of 0.11 x 10(-9) - 0.67 x 10(-9) and 0.19 x 10(-9) - 1.36 x 10(-9), respectively, with their maximal concentrations appearing in August. MACR and MVK were measured under the detecting limit in March and November, which may be ascribed to low isoprene emission from the broadleaf trees without leaves during two months. According to the stoichiometric coefficients among MVK, MACR, isoprene and formaldehyde, the concentrations of the reacted isoprene due to photo-oxidation can be calculated derived from the concentrations of the measured MVK and MACR. Then, the monthly (April to October) average concentrations of formaldehyde produced by the photo-oxidation of reacted isoprene were roughly estimated to be in the range of 0.35 x 10(-9) - 2.5 x 10(-9), which accounted for 4.6%-11.5% of total atmospheric formaldehyde. During the period with active atmospheric photo-oxidation (June to August), the contribution of biogenic isoprene to formaldehyde was predominant. Therefore, the biogenic isoprene is an important source to local photo-oxidant formation in Beijing and should be considered of.

[Methane emission from aquatic vegetation zones of Wuliangsu Lake, Inner Mongolia]

To quantify the variations of methane fluxes from different aquatic vegetation zones, two-year measurements were measured at different aquatic vegetation zones and water depths using static chamber technique during two growing season from April to October in 2003 and 2004. Results showed that the average emission flux of CH4 from Potamogeton pectinatus (submerged macrophyte) growing zones was (3.44 +/- 1.60) mg x (m2 x h)(-1), 78.06% lower than that from Phragmites australis (emergent macrophyte). Significant seasonal and diurnal variations of CH4 emission were observed for Phragmites community; however, the variations were minor for P. pectinatus. Sediment temperature at 5 cm and photosynthesis active radiation were important factors influencing seasonal and diurnal variations of CH4 fluxes from Phragmites zone. Annual methane flux from the lake was 1 024.6 t and 1 156.7 t in 2003 and 2004, respectively.