New insights into functional divergence and adaptive evolution of uncultured bacteria in anammox community by complete genome-centric analysis

Anaerobic ammonium-oxidation (anammox) bacteria play a crucial role in global nitrogen cycling and wastewater nitrogen removal, but they share symbiotic relationships with various other microorganisms. Functional divergence and adaptive evolution of uncultured bacteria in anammox community remain underexplored. Although shotgun metagenomics based on short reads has been widely used in anammox research, metagenome-assembled genomes (MAGs) are often discontinuous and highly contaminated, which limits in-depth analyses of anammox communities. Here, for the first time, we performed Pacific Biosciences high-fidelity (HiFi) long-read sequencing on the anammox granule sludge sample from a lab-scale bioreactor, and obtained 30 accurate and complete metagenome-assembled genomes (cMAGs). These cMAGs were obtained by selecting high-quality circular contigs from initial assemblies of long reads generated by HiFi sequencing, eliminating the need for Illumina short reads, binning, and reassembly. One new anammox species affiliated with Candidatus Jettenia and three species affiliated with novel families were found in this anammox community. cMAG-centric analysis revealed functional divergence in general and nitrogen metabolism among the anammox community members, and they might adopt a cross-feeding strategy in organic matter, cofactors, and vitamins. Furthermore, we identified 63 mobile genetic elements (MGEs) and 50 putative horizontal gene transfer (HGT) events within these cMAGs. The results suggest that HGT events and MGEs related to phage and integration or excision, particularly transposons containing tnpA in anammox bacteria, might play important roles in the adaptive evolution of this anammox community. The cMAGs generated in the present study could be used to establish of a comprehensive database for anammox bacteria and associated microorganisms. These findings highlight the advantages of HiFi sequencing for the studies of complex mixed cultures and advance the understanding of anammox communities.

[Clinical characteristics of children with severe SARS-CoV-2 infection in Yunnan]

Objective: To investigate the clinical characteristics of 130 children with severe SARS-CoV-2 infection in Yunnan province after the relaxation of non-pharmaceutical interventions, and analyze the risk factors for mortality. Methods: This study is a retrospective case summary that analyzed the demographic data, underlying diseases, clinical diagnoses, disease outcomes, and laboratory results of 130 children with severe COVID-19 infections admitted to nine top-tier hospitals in Yunnan Province from December 2022 to March 2023. According to the prognosis, the patients were divided into survival group and death group. The clinical and laboratory data between the two groups were compared, and the risk factors of death were evaluated. The χ2 test and Mann-Whitney U test were employed to compare between groups, while Spearman correlation test and multiple Logistic regression were used to analyze the risk factors for death. The predictive value of independent risk factors was evaluated by receiver operating characteristic curve. Results: The 130 severe patients included 80 males and 50 females with an onset age of 28.0 (4.5, 79.5) months. There were 97 cases in the survival group and 33 cases in the death group with no significant differences in gender and age between the two groups (P>0.05). Twenty-five cases (19.2%) out of the 130 patients had underlying diseases, and the number with underlying diseases was significantly higher in death group than in survival group (36.4% (12/33) vs. 13.4%(13/97), χ2=8.36, P=0.004). The vaccination rate in the survival group was significantly higher than that in the death group (86.1% (31/36) vs. 7/17, χ2=9.38, P=0.002). A total of 42 cases (32.3%) of the 130 patients were detected to be infected with other pathogens, but there was no significant difference in the incidence of co-infection between the death group and the survival group (39.3%(13/33) vs. 29.9% (29/97), χ2=1.02, P>0.05). Among the 130 cases, severe respiratory cases were the most common 66 cases (50.8%), followed by neurological severe illnesses 34 cases (26.2%) and circulatory severe 13 cases (10%). Compared to the survival group, patients in the death group had a significantly higher levels of neutrophil, ferritin, procalcitonin, alanine aminotransferase, lactate dehydrogenase, creatine kinase isoenzyme, B-type natriuretic peptide, interleukin-6 and 10 (6.7 (4.0, 14.0) vs. 3.0 (1.6, 7.0)×109/L, 479 (298, 594) vs. 268 (124, 424) μg/L, 4.8 (1.7, 10.6) vs. 2.0 (1.1, 3.1) μg/L, 66 (20, 258) vs. 23 (15, 49) U/L, 464 (311, 815) vs. 304 (252, 388) g/L, 71(52, 110) vs. 24(15, 48) U/L, 484 (160, 804) vs. 154 (26, 440) ng/L, 43 (23, 102) vs. 19 (13, 27) ng/L, 216 (114, 318) vs. 86 (45, 128) ng/L, Z=-4.21, -3.67, -3.76, -3.31, -3.75, -5.74, -3.55, -4.65, -5.86, all P<0.05). The correlated indexes were performed by multivariate Logistic regression and the results showed that vaccination was a protective factor from death in severe cases (OR=0.01, 95%CI 0-0.97, P=0.049) while pediatric sequential organ failure assessment (PSOFA) (OR=3.31, 95%CI 1.47-7.47, P=0.004), neutrophil-to-lymphocyte ratio (NLR) (OR=1.56, 95%CI 1.05-2.32, P=0.029) and D dimer (OR=1.49, 95%CI 1.00-1.02, P=0.033) were independent risk factors for death (all P<0.05). The area under the curve of the three independent risk factors for predicting death were 0.86 (95%CI 0.79-0.94), 0.89 (95%CI 0.84-0.95) and 0.87 (95%CI 0.80-0.94), all P<0.001, and the cut-off values were 4.50, 3.66 and 4.69 mg/L, respectively. Conclusions: Severe SARS-CoV-2 infection can occur in children of all ages, primarily affecting the respiratory system, but can also infect the nervous system, circulatory system or other systems. Children who died had more severe inflammation, tissue damage and coagulation disorders. The elevations of PSOFA, NLR and D dimer were independent risk factors for death in severe children.

Biosynthetic potential of uncultured anammox community bacteria revealed through multi-omics analysis

Microbial secondary metabolites (SMs) and their derivatives have been widely used in medicine, agriculture, and energy. Growing needs for renewable energy and the challenges posed by antibiotic resistance, cancer, and pesticides emphasize the crucial hunt for new SMs. Anaerobic ammonium-oxidation (anammox) systems harbor many uncultured or underexplored bacteria, representing potential resources for discovering novel SMs. Leveraging HiFi long-read metagenomic sequencing, 1,040 biosynthetic gene clusters (BGCs) were unearthed from the anammox microbiome with 58% being complete and showcasing rich diversity. Most of them showed distant relations to known BGCs, implying novelty. Members of the underexplored lineages (Chloroflexota and Planctomycetota) and Proteobacteria contained lots of BGCs, showcasing substantial biosynthetic potential. Metaproteomic results indicated that Planctomycetota members harbored the most active BGCs, particularly those involved in producing potential biofuel-ladderane. Overall, these findings underscore that anammox microbiomes could serve as valuable resources for mining novel BGCs and discovering new SMs for practical application.

[Clinical characteristics of hospitalized children with respiratory syncytial virus infection and risk prediction of severe illness during the post-COVID-19 era in Kunming]

Objective: To compare the epidemiological and clinical characteristics of hospitalized children with respiratory syncytial virus (RSV) infection in Kunming among the pre-and post-COVID-19 era, and to establish a prediction model for severe RSV infection in children during the post-COVID-19 period. Methods: This was a retrospective study. Clinical and laboratory data were collected from 959 children hospitalized with RSV infection in the Department of Pulmonary and Critical Care Medicine at Kunming Children's Hospital during January to December 2019 and January to December 2023. Patients admitted in 2019 were defined as the pre-COVID-19 group, while those admitted in 2023 were classified as the post-COVID-19 group. Epidemiological and clinical characteristics were compared between the two groups. Subsequently, comparison of the clinical severity among the two groups was performed based on propensity score matching (PSM). Furthermore, the subjects in the post-COVID-19 group were divided into severe and non-severe groups based on clinical severity. Chi-square test and Mann-Whitney U test were used for pairwise comparison between groups, and multivariate Logistic regression was applied for the identification of independent risk factors and construction of the prediction model. The receiver operating characteristic (ROC) curve and calibration curve were employed to evaluate the predictive performance of this model. Results: Among the 959 children hospitalized with RSV infection, there were 555 males and 404 females, with an onset age of 15.4 (7.3, 28.5) months. Of which, there were 331 cases in the pre-COVID-19 group and 628 cases in the post-COVID-19 group. The peak period of RSV hospitalization in the post-COVID-19 group were from May to October 2023, and the monthly number of inpatients for each of these months were as follows: 72 cases (11.5%), 98 cases (15.6%), 128 cases (20.4%), 101 cases (16.1%), 65 cases (10.4%), and 61 cases (9.7%), respectively. After PSM for general data, 267 cases were matched in each group. The proportion of wheezing in the post-COVID-19 group was lower than that in the pre-COVID-19 group (109 cases (40.8%) vs. 161 cases (60.3%), χ2=20.26, P<0.001), while the incidences of fever, tachypnea, seizures, severe case, neutrophil-to-lymphocyte ratio (NLR), C-reactive protein and interleukin-6 levels were all higher than those in the pre-COVID-19 group (146 cases (54.7%) vs. 119 cases (44.6%), 117 cases (43.8%) vs. 89 cases (33.3%), 37 cases (13.9%) vs. 14 cases (5.2%), 69 cases (25.8%) vs. 45 cases (16.9%), 3.6 (1.9, 6.4) vs. 2.3 (1.8, 4.6), 9.9 (7.1, 15.2) vs. 7.8 (4.5, 13.9) mg/L, 20.5 (15.7, 30.4) vs. 17.2 (11.0, 26.9) ng/L, χ2=5.46, 6.36, 11.47, 6.42, Z=4.13, 3.06, 2.96, all P<0.05). There were 252 cases and 107 cases with co-infection in the post-and pre-COVID-19 groups, respectively. The proportion of triple and quadruple infection in the post-COVID-19 group was higher than that in the pre-COVID-19 group (59 cases (23.4%) vs. 13 cases (12.1%), 30 cases (11.9%) vs. 5 cases (4.7%), χ2=5.94, 4.46, both P<0.05). Among the 252 cases with co-infection in post-COVID-19 group, the most prevalent pathogens involving in co-infections, in order, were Mycoplasma pneumoniae 56 cases (22.2%), Influenza A virus 53 cases (21.0%), Rhinovirus 48 cases (19.0%), Parainfluenza virus 35 cases (13.9%), and Adenovirus 28 cases (11.1%).The result of multivariate Logistic regression showed that age (OR=0.70, 95%CI 0.62-0.78, P<0.001), underlying diseases (OR=10.03, 95%CI 4.10-24.55, P<0.001), premature birth (OR=6.78, 95%CI 3.53-13.04, P<0.001), NLR (OR=1.85, 95%CI 1.09-3.15, P=0.023), and co-infection (OR=1.28, 95%CI 1.18-1.38, P<0.001) were independently associated with the development of severe RSV infection in the post-COVID-19 group. The ROC curve of the prediction model integrating the above five factors indicated an area under the curve of 0.85 (95%CI 0.80-0.89, P<0.001), with an optimal cutoff of 0.21, a sensitivity of 0.83 and a specificity of 0.80. The calibration curve showed that the predicted probability in this model did not differ significantly from the actual probability (P=0.319). Conclusions: In the post-COVID-19 era in Kunming, the peak in pediatric hospitalizations for RSV infection was from May to October, with declined incidence of wheezing and increased incidence of fever, tachypnea, seizures, severe cases, and rates of triple and quadruple co-infections. Age, underlying diseases, premature birth, NLR, and co-infection were identified as independent risk factors for severe RSV infection in the post-COVID-19 period. In this study, a risk prediction model for severe pediatric RSV infection was established, which had a good predictive performance.

Motility behavior and physiological response mechanisms of aerobic denitrifier, Enterobacter cloacae strain HNR under high salt stress: Insights from individual cells to populations

The motility behaviors at the individual-cell level and the collective physiological responsive behaviors of aerobic denitrifier, Enterobacter cloacae strain HNR under high salt stress were investigated. The results revealed that as salinity increased, electron transport activity and adenosine triphosphate content decreased from 15.75 μg O2/g/min and 593.51 mM/L to 3.27 μg O2/g/min and 5.34 mM/L, respectively, at 40 g/L, leading to a reduction in the rotation velocity and vibration amplitude of strain HNR. High salinity stress (40 g/L) down-regulated genes involved in ABC transporters (amino acids, sugars, metal ions, and inorganic ions) and activated the biofilm-related motility regulation mechanism in strain HNR, resulting in a further decrease in flagellar motility capacity and an increase in extracellular polymeric substances secretion (4.08 mg/g cell of PS and 40.03 mg/g cell of PN at 40 g/L). These responses facilitated biofilm formation and proved effective in countering elevated salt stress in strain HNR. Moreover, the genetic diversity associated with biofilm-related motility regulation in strain HNR enhanced the adaptability and stability of the strain HNR populations to salinity stress. This study enables a deeper understanding of the response mechanism of aerobic denitrifiers to high salt stress.

Fate of iron nanoparticles in anammox system: Dissolution, migration and transformation

Iron nanoparticles (FeNPs) are commonly used in various industrial processes, leading to their release into the environment and eventual entrance into wastewater treatment plants (WWTPs). FeNPs undergo dissolution, migration, and transformation in WWTPs, which can potentially affect the stable operation of anaerobic ammonia oxidation (anammox) systems and may be discharged with wastewater or biomass. To better understand the fate of FeNPs in anammox systems, exposure experiments were conducted using anammox granular sludges (AnGS) and FeNPs. Results demonstrated that FeNPs released Fe2+ upon contact with water, with a portion being bound to functional groups in extracellular polymeric substances (EPS) and the rest entering the bacteria to form highly absorbable substances. A significant amount of FeNPs was observed to cover the surface of AnGS or aggregate and deposit at the bottom of the reactor, eventually converting into Fe3O4 and stably existing within the anammox system. The findings of this study clarify the fate of FeNPs in anammox systems and provide important insights into the stable operation of anammox systems under FeNPs exposure.

[Clinical characteristics of children with SARS-CoV-2 Omicron variant infection in Kunming]

Objective: To investigate the clinical characteristics of hospitalized children infected with the Omicron variant in Kunming after the withdrawal of non-pharmaceutical interventions (NPI) and analyze the risk factors of severe cases. Methods: Clinical data was retrospectively collected from 1 145 children with SARS-CoV-2 Omicron infection who were hospitalized in six tertiary grade A hospitals in Kunming from December 10th, 2022 to January 9th, 2023. According to clinical severity, these patients were divided into the general and severe SARS-CoV-2 groups, and their clinical and laboratory data were compared. Between-group comparison was performed using t-test, chi-square test and Mann-Whitney U test. Spearman correlation test and multivariate Logistic regression analysis were used to determine the risk factors of severe illness. Results: A total of 1 145 hospitalized patients were included, of whom 677 were male and 468 female. The age of these patients at visit was 1.7 (0.5, 4.1) years. Specifically, there were 758 patients (66.2%) aged ≤3 years at visit and 387 patients (33.8%) aged >3 years. Of these children, 89 cases (7.8%) had underline diseases and the remaining 1 056 cases (92.2%) had no combined diseases. Additionally, of all the patients, 319 cases (27.9%) were vaccinated with one or two doses of SARS-CoV-2 vaccine, 748 cases (65.3%) had acute upper respiratory tract infection (AURTI), and six cases died (0.5%). A total of 1 051 cases (91.8%) were grouped into general SARS-CoV-2 group and 94 cases (8.2%) were grouped into severe SARS-CoV-2 group. Compared with the general cases, the severe cases showed a lower rate of SARS-CoV-2 vaccination and younger median age, lower lymphocyte count, as well as proportions of CD8+T lymphocyte (36 cases (38.3%) vs. 283 cases (26.9%), 0.5 (2.6, 8.0) vs. 1.6 (0.5, 3.9) years, 1.3 (1.0, 2.7) ×109 vs. 2.7 (1.3,4.4)×109/L, 0.17 (0.12, 0.24) vs. 0.21 (0.15, 0.16), respectively, χ2=4.88, Z=-2.21,-5.03,-2.53, all P<0.05). On the other hand, the length of hospital stay, proportion of underline diseases, ALT, AST, creatine kinase isoenzyme, and troponin T were higher in the severe group compared to those in the general group ((11.6±5.9) vs. (5.3±1.8) d, 41 cases (43.6%) vs. 48 cases (4.6%), 67 (26,120) vs. 20 (15, 32) U/L, 51 (33, 123) vs. 44 (34, 58) U/L、56.9 (23.0, 219.3) vs. 3.6 (1.9, 17.9) U/L, 12.0 (4.9, 56.5) vs. 3.0 (3.0, 7.0) ×10-3 pg/L,respectively, t=-20.43, χ2=183.52, Z=-9.14,-3.12,-6.38,-3.81, all P<0.05). Multivariate regression analysis indicated that increased leukocyte count (OR=1.88, 95%CI 1.18-2.97, P<0.01), CRP (OR=1.18, 95%CI 1.06-1.31, P<0.01), ferritin (OR=1.01, 95%CI 1.00-1.00, P<0.01), interleukin (IL)-6 (OR=1.05, 95%CI 1.01-1.08, P=0.012), D-dimer (OR=2.56, 95%CI 1.44-4.56, P<0.01) and decreased CD4+T lymphocyte (OR=0.84, 95%CI 0.73-0.98, P=0.030) were independently associated with the risk of severe SARS-CoV-2 in hospitalized children with Omicron infection. Conclusions: After the withdrawal of NPI, the pediatric inpatients with Omicron infection in Kunming were predominantly children younger than 3 years of age, and mainly manifested as AURTI with relatively low rate of severe SARS-CoV-2 infection and mortality. Elevated leukocyte counts, CRP, ferritin, IL-6, D-dimer, and decreased CD4+T lymphocytes are significant risk factors for developing severe SARS-CoV-2 infection.

Unraveling the structure and function of bacterioferritin in Candidatus Kuenenia stuttgartiensis: Iron storage sites maintain cellular iron homeostasis

Anammox bacteria rely heavily on iron and have many iron storage sites. However, the biological significance of these iron storage sites has not been clearly defined. In this study, we explored the properties and location of iron storage sites to better understand their cellular function. To do this, the Candidatus Kuenenia stuttgartiensis iron storage protein, bacterioferritin (K.S Bfr), was successfully expressed and purified. In vitro, correctly assembled globulins were observed by transmission electron microscopy. The self-assembled K.S Bfr has active redox and can bind Fe²⁺ and mineralize it in the protein cavity. In vivo, engineered bacteria with K.S Bfr showed good adaptability to Fe²⁺, with a survival rate of 78.9% when exposed to 5 mM Fe²⁺, compared with only 66.0% for wild-type bacteria lacking K.S Bfr. A potential iron regulatory strategy similar to that of Anammox was identified in transcriptomic analysis of engineered bacteria. This system may be controlled by the iron uptake regulator Furto transport Fe²⁺ via FeoB and store excess Fe²⁺ in K.S Bfr to maintain cellular homeostasis. K.S Bfr has superior iron storage capacity both intracellularly and in vitro. The discovery of K.S Bfr reveals the storage location of iron-rich nanoparticles, increases our understanding of the adaptability of iron-dependent bacteria to Fe²⁺, and suggests possible iron regulation strategies in Anammox bacteria.

Biofilm formation during wastewater treatment: Motility and physiological response of aerobic denitrifying bacteria under ammonia stress based on surface plasmon resonance imaging

A bacterial image analysis system based on surface plasmon resonance imaging was established to investigate the effect of bacterial motility on biofilm formation under high ammonia nitrogen at the single-cell level. The results showed that the bacterial mean rotation speed and vertical motility distance decreased with the increasing concentration of ammonia nitrogen. Ammonia nitrogen inhibited the metabolic activity of the bacteria, decreasing bacterial motility. Bacterial motility was negatively correlated with the biofilm-formation ability. The biofilm formation ability of Enterobacter cloacae strain HNR exposed to ammonia nitrogen was enhanced by reducing its movement and promoting EPS secretion. Genes related to the tricarboxylic acid cycle and oxidative phosphorylation were down-regulated, indicating inhibition of microbial energy metabolism. Genes related to bacterial secretion and lipopolysaccharide synthesis were up-regulated, facilitating the formation of biofilms and enabling the bacteria to resist ammonia nitrogen stress. This study provides new insights into the biofilm formation under ammonia stress.

Acceleration of start-up of moving bed biofilm reactor at low temperature by adding specialized quorum sensing bacteria

This study aims to accelerate biofilm formation and operational performance of moving bed biofilm reactor (MBBR) at 5 ℃ by adding specialized Quorum Sensing bacteria (sphingomonas rubra BH3^T). Results showed that bio augmented MBBR (R_S) achieved a higher chemical oxygen demand and NH₄⁺-N removal rate (93% and 75%), which in accordance with its increased biofilm thickness, higher biofilm activity, and nitrifying bacteria abundance (Nitrospira). The increased biofilm thickness (60.23 %) during the whole operating time, accompanied by more potent adhesion force (61.59 %), was related to increased polysaccharides and proteins in the biofilm. Pyrosequencing analysis indicated that BH3^T contributed to higher species richness and triggered the rapid growth of precursor microorganisms (Nakamurella, Micropruina, and Zoogloea) and the enrichment of multifunctional microorganisms (Pseudomonas, Aeromonas, Arcobacter, Dechloromonas, and Flavobacterium) at low temperatures. This study provides an economical and practical new insight into accelerating start-up of MBBR system at low temperature.

[Epidemiological characteristics of adenovirus infection in hospitalized children with acute respiratory tract infection in Kunming during 2019]

Objective: To investigate the epidemiology and clinical characteristics of adenovirus (ADV)-caused acute respiratory tract infection among hospitalized children in Kunming, China. Methods: Clinical and laboratory data were collected from 467 children with adenovirus infection who were hospitalized from January 1, 2019 to December 31, 2019 in 6 grade A class Ⅲ hospitals in Kunming area. The basic characteristics, epidemiology, mixed infection and adenovirus genotypes of the patients were retrospectively analyzed. The patients diagnosed with adenovirus pneumonia (AP) were divided into two groups, severe AP (SAP) group and general AP(GAP) group according to the severity of illness. Mann-Whitney U test or χ² test was used for comparison between groups, while multivariate regression was applied to analyze the risk factors of SAP. Results: Among 15 635 hospitalized children with respiratory tract infection, 467 cases were adenovirus positive, with a detection rate of 2.99%. Of the 467 patients with adenovirus infection, 284 were male and 183 female, the age was 2.4 (1.1,3.9) years, including 44 cases (9.4%) < 0.5 years, 59 cases (12.6%) of 0.5 to<1.0 years, 176 cases (37.7%) of 1.0 to <3.0 years, 150 cases (32.1%) of 3.0 to <7.0 years, and 38 cases (8.1%) of 7.0 to 14.0 years. Adenovirus infection was common in autumn and winter, and the high incidence months were October to December, which accounted for 51.6% (241/467) of the whole year cases. Co-infection was detected in 226 cases (48.4%) out of 467 patients, in which one pathogen co-infection was the most frequent form (172 cases, 76.1%). Of the 262 pathogen detected 108 (41.2%) were Mycoplasma pneumoniae. In 144 of ADV-positve cases (30.8%) were taken geno-typing was done by PCR amplification, the results showed that 74 cases (51.4%) were ADV 3, 7 subtypes and 65 cases (45.1%) of ADV 1, 2,6 subtypes. Of the 467 cases of ADV infection, 320 (68.5%) were diagnosed with pneumonia, 82 (17.6%) with upper respiratory tract infection and pharyngeal tonsillitis, and 65 (13.9%) with bronchitis, laryngeal bronchitis, and asthmatic bronchitis. Among the 320 patients with AP, 56 cases were severe and 264 cases were general. Two cases (3.6%) in severe group died. Compared with the GAP group, the age was young [17 (11,42) months vs. 24 (14,44) months, Z=2.222, P=0.026], the fever duration was long [8 (5,14) days vs. 6 (3,9) days, Z=3.380, P<0.01], and the proportions of preterm birth and having underlying diseases were high [respectively 19.6% (11/56) vs. 6.1% (16/264), 26.8% (15/56) vs. 10.2% (27/264), χ²=8.965,11.109, P<0.05] in SAP group. Referring to laboratory markers, white blood cell count, C-reactive protein, creatine kinase-MB and lactate dehydrogenase were significantly increased in SAP group as compared to GAP group(all P<0.05). Multivariate Logistic regression analysis showed that preterm birth (OR=3.284, 95%CI 1.079-9.993, P=0.036), underlying disease (OR=3.284, 95%CI 1.079-9.993, P=0.036), fever duration ≥10 d (OR=2.523,95%CI 1.195-5.328, P=0.015) and C-reactive protein ≥50 mg/L (OR=3.156, 95%CI 1.324-7.524, P=0.010) were positively correlated with the risk of SAP. Conclusions: The incidence of adenovirus infection among hospitalized children in Kunming was lower than the national level, and no outbreak occurred in 2019. Subtype 3 and 7 of ADV are the predominant strains for infection, which usually occurs in autumn and winter and mainly causes pneumonia. Premature birth, underlining diseases, long fever duration and markedly increased C-reactive protein are the risk factors for developing into severe pneumonia. This paper presents the prevalence and clinical characteristics of adenovirus infection in children at high altitude area.

Potential role of nanobubbles in dynamically modulating the structure and stability of anammox granular sludge within biological nitrogen removal process

The generation of visible macrobubbles considerably affects the structure and function of anammox granules in the anammox granular sludge (AnGS) system. However, the existence of nanobubbles (NBs) and their role in maintaining the AnGS structure and stability are unclear because of the complexity of the system and lack of effective analytical methods. In this study, methods for NB analysis and assessment of their effects were developed to investigate the formation and characteristics of NBs in an AnGS system and the effects of NBs on the properties and function of AnGS. The results indicated that dissolved gas supersaturation caused by AnGS generated NBs of 2.75 × 10⁸ bubbles/mL inside an AnGS reactor after running for 300 min at 30 °C. The increasing absolute value of the zeta potential of NBs with time indicated that the NBs in the AnGS system were gradually stable. The size of the stable NBs ranged from 150 nm to 400 nm. NB formation also increased the space and pressure between cells, leading to the breakage of the cell cluster and causing structural changes in granules. Changes in the local granular microstructure caused by NBs were favorable for the porous structure of granules to avoid granular disintegration and flotation caused by the excessive secretion of extracellular polymeric substances blocking gas channels. The formation and stability of NBs penetrating the cell clusters played a crucial role in the formation and stability of nanopores around or inside the cell clusters, further providing a basis for the formation of high-porosity structures and efficient mass transfer of AnGS.

Effects of lung-protective ventilation strategy on lung aeration loss and postoperative pulmonary complications in moderate-risk patients undergoing abdominal surgery

BACKGROUND

There is a controversy about whether the use of a lung-protective ventilation strategy(LPVS) can reduce the incidence of postoperative pulmonary complications (PPCs) and improve the clinical outcomes in moderate-risk patients were assessed by the Assess Respiratory Risk in Surgical Patients in Catalonia(ARISCAT).

METHODS

One hundred moderate-risk patients predicted by the ARISCAT, scheduled to undergo abdominal surgery were randomized into two groups: conventional ventilation strategy group (G<inf>0</inf>) and lung-protective ventilation strategy group (G<inf>1</inf>). Lung ultrasonography (LUS) and the LUS score were performed before induction of anesthesia (T<inf>0</inf>), 30min after extubation (T<inf>1</inf>), and 24h (T<inf>2</inf>), 72h (T<inf>3</inf>) after surgery. The incidence and severity of PPCs within the postoperative 7 days, the duration of postoperative oxygen supplementation, and postoperative hospital stay (PHS) were recorded.

RESULTS

The LUS score of both groups at T<inf>1-3</inf> was higher than those at T<inf>0</inf> (P<0.05), moreover, the LUS score of G<inf>1</inf> was lower than that of G<inf>0</inf> at T<inf>1-3</inf>. The incidence of PPCs of G<inf>1</inf> (10.9%) was lower than that of G<inf>0</inf> (29.8%) (relative risk, 0.37; 95% confidence interval [CI], 0.14 to 0.93; P=0.02) and the severity of PPCs of G<inf>1</inf> were lower than those of G<inf>0</inf> (P<0.05). The PHS of G<inf>1</inf> was less than that of G<inf>0</inf> (8[7-10] vs. 9[8-11], P<0.05).

CONCLUSIONS

The LPVS can decrease lung aeration loss assessed by LUS and reduce the incidence of PPCs in moderate-risk patients.

Acute hypoxic stress: Effect on blood parameters, antioxidant enzymes, and expression of HIF-1alpha and GLUT-1 genes in largemouth bass (Micropterus salmoides)

Dissolved oxygen (DO) plays a crucial role in survival, growth, and normal physiological functions of aquatic organisms. Nevertheless, the mechanisms involved in hypoxic stress and adaptation have not been fully elucidated in Largemouth bass (Micropterus salmoides). To reveal the effect of acute hypoxia on Largemouth bass, we simulated acute hypoxia (DO: 1.2 ± 0.2 mg/L) in the laboratory and analyzed physiological parameters (RBCs, Hb, SOD, CAT, NA⁺/K⁺-ATPase, GPx, and MDA) and gene expression (HIF-1alpha and GLUT-1) in Largemouth bass exposed to various durations of acute hypoxia (0, 1, 2, 4, 8, 12, and 24 h). Our results indicated that acute hypoxic exposure significantly increased RBCs but decreased Hb. In addition, antioxidant enzyme activity was enhanced significantly in the liver and muscles at the initial stage of acute hypoxic exposure, but decreased significantly in gills during the entire process of hypoxic exposure. Furthermore, the expression levels of HIF-1alpha and GLUT-1 mRNA were significantly up-regulated in Largemouth bass under acute hypoxic exposure. In conclusion, our study provides a valuable basis for further elucidation of hypoxic adaptation and facilitates husbandry for an economically valuable species.

Ultrafast degradation of azo dyes catalyzed by cobalt-based metallic glass

Reactivity and mass loss are considered mutually exclusive in conventional zero-valent metal (ZVM) technology to treat environmental contaminants. Here, we report the outstanding performance of Co-based metallic glass (MG) in degrading an aqueous solution of azo dye, thus eliminating this trade-off. Ball-milled Co-based MG powders completely degrade Acid Orange II at an ultrafast rate. The surface-area-normalized rate constant of Co-based MG powders was one order of magnitude higher than that of Co-based crystalline counterparts and three orders of magnitude higher than that of the widely studied Fe⁰ powders. The coordinatively unsaturated local structure in Co-based MG responds to the catalysis for degradation, resulting in very low mass loss. Wide applicability and good reusability were also present. Co-based MG is the most efficient material for azo dye degradation reported thus far, and will promote the practical application of MGs as functional materials.

Atomic interaction mechanism for designing the interface of W/Zr-based bulk metallic glass composites

The interaction between active element Zr and W damages the W fibers and the interface and decreases the mechanical properties, especially the tensile strength of the W fibers reinforced Zr-based bulk metallic glass composites (BMGCs). From the viewpoint of atomic interaction, the W-Zr interaction can be restrained by adding minor elements that have stronger interaction with W into the alloy. The calculation about atomic interaction energy indicates that Ta and Nb preferred to segregate on the W substrate surface. Sessile drop experiment proves the prediction and corresponding in-situ coating appears at the interface. Besides, the atomic interaction mechanism was proven to be effective in many other systems by the sessile drop technique. Considering the interfacial morphology, Nb was added into the alloy to fabricate W/Zr-based BMGCs. As expected, the Nb addition effectively suppressed the W-Zr reaction and damage to W fibers. Both the compressive and tensile properties are improved obviously.

Prevalence of polyclonal mefA-containing isolates among erythromycin-resistant group A streptococci in Southern Taiwan

A total of 204 nonrepetitive isolates of group A streptococci (GAS), including 107 randomly collected between 1992 and 1995 and 66 and 31 consecutively collected in 1997 and 1998, respectively, from a university hospital in southern Taiwan were examined to determine the prevalence and mechanisms of erythromycin resistance among these isolates. Resistance to erythromycin was detected in 129 isolates (63.2%) by the agar dilution test. Of these, 42 isolates (32.6%) were assigned to the constitutive macrolide, lincosamide, and streptogramin B resistance (cMLS) phenotype, and all carried the ermB gene; 4 (3.1%) were assigned to the inducible MLS resistance (iMLS) phenotype, and all harbored the ermTR gene; and 83 (64.3%) were erythromycin resistant but susceptible to clindamycin (M phenotype), and all possessed the mefA gene. Distributed by years, the rates of erythromycin resistance and different phenotypes were 61.7% (53.0% cMLS, 6.1% iMLS, and 40.9% M phenotype) between 1992 and 1995, 62.1% (12.2% cMLS and 87.8% M phenotype) in 1997, and 71. 0% (9.1% cMLS and 90.9% M phenotype) in 1998. Pulsed-field gel electrophoresis showed that all but 2 cMLS isolates were clonal in origin, and 17 clones were detected among the M-phenotype isolates. These results indicate that the high incidence and increasing rate of erythromycin-resistant GAS in southern Taiwan are due to the prevalence of multiple M-phenotype clones and that clindamycin may be the drug of choice for the treatment of infections with GAS in penicillin-hypersensitive patients in this area.

Protective effect of bisoprolol on beta-1 adrenoceptor peptide-induced autoimmune myocardial damage in rabbits

Idiopathic dilated cardiomyopathy is a severe disease of unknown etiology. Accumulating evidence suggests that agonist-like autoantibodies against the beta 1 adrenoceptor in the circulation of dilated cardiomyopathy may play an important role. The aim of this study was to evaluate the effects of the selective beta 1-adrenoceptor blocker, bisoprolol, on beta 1-adrenoceptor peptide induced autoimmune myocardial damage. In the animal model of autoimmune cardiomyopathy induced by active immunization of rabbits with beta 1-adrenoceptor peptide, bisoprolol was given at a dose of 3 mg/day throughout the study period. Our results showed high titer of anti-beta 1-adrenoceptor antibody in the immunized group throughout the study but not in the group receiving only bisoprolol. Cross-reactivity to beta 2 adrenoceptors was observed in some of the immunized rabbits, but disappeared almost entirely after 6 months. As compared to the beta 1-adrenoceptor peptide immunized group without bisoprolol treatment, bisoprolol treated beta 1-receptor peptide immunized group showed increase in the wall thickness and decreases in cavity dimension in anatomical measurements and only mild alterations in macro- and microscopic examinations. Thus, our study clearly demonstrated a beneficial effect of bisoprolol in rabbits who have developed autoimmune myocardial damage.

Autoantibodies against M2 muscarinic receptors in patients with cardiomyopathy display non-desensitized agonist-like effects

Circulating autoantibodies against the human M2 muscarinic receptors have been previously shown in 38% of patients with idiopathic dilated cardiomyopathy. The functional properties of these autoantibodies are reported herein. They were able to decrease the cell beating frequency of myocytes in cultured neonatal rat heart cells in a dose-dependent manner without desensitization over a period of more than 5 hours whereas the non-specific muscarinic receptor agonist carbachol also inhibited the heart cell beating frequency but was desensitized within 1 hour. In the same cell culture, anti-M2 muscarinic receptor autoantibodies were not able to induce internalization of muscarinic receptor whereas carbachol did. These results demonstrate for the first time that anti-M2 muscarinic receptor autoantibodies from patients with idiopathic dilated cardiomyopathy have stimulatory muscarinic activity in vitro, which differ from normal muscarinic agonists by non-desensitization.

DNA hybridization and electrokaryotype study of some Candida species

Some Candida species which were similar to each other in phenotypic characteristics were studied by chemotaxonomic and molecular taxonomic comparison including the ubiquinone systems, electrophoretic karyotypes, DNA base composition and DNA relatedness. Candida viswanathii and Candida lodderae showed similar electrophoretic karyotypes and DNA base composition and demonstrated 89 to 91% DNA relatedness, confirming their synonymy.

[Qing-shen tiao-zhi tablet in the treatment of hyperlipemia in the middle and old aged]

The effect of Qing-Shen Tiao-Zhi (QSTZ) tablet which consisted of Rheum palmatum and Alismatis orientale etc. on serum TC, TG, HDL-C, LDL-C and atherogenic index (AI) was reported in 73 senile hyperlipemic patient, while another 21 patients took Yue Jian Cao (YJC) oil capsule. The results showed that total effective rate was 91.7% in QSTZ group, and 71.43% in the YJC group (P < 0.05). The levels of TC, TG and LDL-C before and after medication showed significant difference, P < 0.01 in QSTZ group and that there was only a few persons those P < 0.05 in control group. About AI, it revealed in QSTZ and control group as P < 0.01 and > 0.05 respectively.

Urinary excretion of N-nitrosamino acids and nitrate by inhabitants of high- and low-risk areas for esophageal cancer in Northern China: endogenous formation of nitrosoproline and its inhibition by vitamin C

A total of 238 samples of 24-h urine were collected from inhabitants of high-risk (Lin-xian) and low-risk (Fan-xian) areas for esophageal cancer in northern China, according to three protocols: (a) from undosed subjects; (b) from subjects who had ingested 100 mg L-proline three times a day 1 h after each meal; and (c) from subjects in Lin-xian who had ingested 100 mg ascorbic acid together with 100 mg L-proline three times a day 1 h after each meal. As an index of individual exposure to N-nitroso compounds or their precursors, ingested in food and/or formed endogenously, the levels of four urinary N-nitrosamino acids and nitrate were determined. The amounts of N-nitrosoproline, N-nitrosothiazolidine 4-carboxylic acid, N-nitrososarcosine, and nitrate excreted in the 24-h urine of undosed subjects in Lin-xian were significantly higher than those in Fan-xian, indicating a higher exposure of the inhabitants in the high-risk area to N-nitroso compounds and their precursors. Ingestion of L-proline resulted in a marked increase in urinary N-nitrosoproline levels in inhabitants from both areas, suggesting that endogenous nitrosation may occur to a larger extent when appropriate amine precursors are ingested in foods. Intake of moderate doses of ascorbic acid by high-risk subjects effectively reduced the urinary levels of N-nitrosamino acids to those found in undosed subjects in the low-risk area. If N-nitroso compounds formed in vivo are among the causative factors for esophageal cancer in this area of northern China, ascorbic acid appears to be effective in lowering the body burden of these carcinogenic compounds, thus offering a rational basis for long-term intervention studies in this area.