The Critical Role of microRNA-21 in Non-alcoholic Fatty Liver Disease Pathogenesis.

Nonalcoholic fatty liver disease (NAFLD) has received worldwide scientific attention because of its rapidly increasing prevalence, and it has emerged as a serious public health problem in end-stage liver disease. Many factors are involved in the multifactorial development and progression of liver disease by influencing multiple signaling and metabolic pathways. Currently, many studies have demonstrated the critical role of microRNA- 21 (miR-21) in NAFLD pathogenesis. In addition, many studies have found that miR-21 is highly expressed in inflammatory bowel disease, which is associated with intestinal barrier dysfunction and altered gut microbiota. In this paper, we focus on the regulatory role of miR-21 in the progression of NAFLD and its effect on the gut microbiota, summarize the involvement of miR-21 through a variety of signaling pathways and metabolic pathways, as well as discuss some predicted miR-21 target genes and miR-21 pathways for future experimental identification.

The Relationship between Family Functioning and Pathological Internet Use among Chinese Adolescents: The Mediating Role of Hope and the Moderating Role of Social Withdrawal.

This study constructed a moderated mediation model based on problem behavior theory to explore the psychological mechanism of family functioning interaction with pathological internet use. We used the Adolescent Pathological Internet Use Scale, General Functioning Scale, Trait Hope Scale, and Social Withdrawal Scale to measure internet use in 1223 middle school students. The results showed that (1) pathological internet use was negatively correlated with family functioning and hope, and positively correlated with social withdrawal; family functioning was positively correlated with hope, and negatively correlated with social withdrawal; hope was negatively correlated with social withdrawal; (2) family functioning could not only directly predict pathological internet use, but also indirectly predict pathological internet use through hope; and (3) the mediating effect of family functioning on pathological internet use was moderated by social withdrawal, which was stronger for individuals with low social withdrawal but not significant for individuals with high social withdrawal. This study revealed the internal mechanism of the relation between family functioning and adolescents' pathological internet use, which has theoretical significance for improving adolescents' hope and reducing their pathological internet use.

Mental Health of Parents of Special Needs Children in China during the COVID-19 Pandemic.

We assessed the mental health of parents (N = 1450, Mage = 40.76) of special needs children during the COVID-19 pandemic. We conducted an online survey comprising items on demographic data; two self-designed questionnaires (children's behavioral problems/psychological demand of parents during COVID-19); and four standardized questionnaires, including the General Health Questionnaire, Perceived Social Support, Parenting Stress Index, and Neuroticism Extraversion Openness Five Factor Inventory. The results showed that there were significant differences among parents of children with different challenges. Parents of children with autism spectrum disorder were more likely to have mental health problems compared to parents whose children had an intellectual disability or a visual or hearing impairment. Behavioral problems of children and psychological demands of parents were common factors predicting the mental health of all parents. Parent-child dysfunctional interactions and parenting distress were associated with parents of children with autism spectrum disorder. Family support, having a difficult child, and parenting distress were associated with having children with an intellectual disability. It is necessary to pay attention to the parents' mental health, provide more social and family support, and reduce parenting pressures.

The Influence of Factors Such as Parenting Stress and Social Support on the State Anxiety in Parents of Special Needs Children During the COVID-19 Epidemic.

OBJECTIVES: The study aims to investigate the state anxiety of parents of special needs children during the 2019 coronavirus disease (COVID-19) epidemic and the influence of parental stress, social support, and other related variables on the anxiety of parents. METHODS: Bespoke questionnaires of children's and parent's mental and behavioral problems during the epidemic were used in the study. We also used the State Anxiety Inventory (S-AI), the Parenting Stress Index-Short Form-15 (PSI-SF-15), the NEO Five-Factor Inventory (NEO-FFI), and the Multidimensional Scale of Perceived Social Support (MSPSS). The data used in the study were pooled from an online survey of parents of special needs children and analyzed by one-way analysis of variance (ANOVA) and multiple linear regression. RESULTS: Overall, 1,451 individuals were included, of which 402 were fathers (27.71%) and 1,049 were mothers (72.29%). ANOVA results showed that educational background, family monthly income, and type of their child's disability made parents' state anxiety significantly different. The results of multiple linear regression showed that during the epidemic, social support negatively predicted parents' state anxiety (B = -0.15, p < 0.001), whereas parenting stress (B = 0.07, p = 0.001) and parental mental and behavioral problems (B = 0.37, p < 0.001) positively predicted parents' state anxiety. CONCLUSIONS: During the outbreak of COVID-19, parents of special needs children suffered mental and behavioral problems, together with parenting stress and social support, which influenced their state anxiety. These findings can be used to develop relevant psychological interventions to improve the mental health of vulnerable groups during a pandemic like COVID-19.

Construction of Polyarylenes with Various Structural Features via Bergman Cyclization Polymerization.

Synthetic polymer chemistry is a fundamental part of polymer science, and highly efficient polymerization reactions are essential for the synthesis of high-performance polymers. Development of new synthetic methods for emerging polymer science is of great importance in this regard. Bergman cyclization is a chemical process in which highly reactive aryl diradicals form from enediyne precursors, having a strong impact in a number of fields including pharmaceutics, synthetic chemistry, and materials science. Diradical intermediates stemming from enediynes can cause DNA cleavage under physiological conditions, leading to the strong cytotoxicity of many naturally occurring enediyne antibiotics. Meanwhile, diradical intermediates can quickly couple with each other to construct polyarylenes, providing a novel method to synthesize these conjugated polymers with the advantages of facile and catalyst-free operation, high efficiency, and tailored structure. Moreover, conjugated polymers generated by Bergman cyclization exhibit many remarkable properties, such as excellent thermal stability and good solubility and processability, enabling their further processing into carbon-rich materials. This review presents a brief overview of the trajectory of Bergman cyclization in polymer science, followed by an introduction to research advances, mainly from our group, in developing polymerization methods based on Bergman cyclization, taking advantages of its catalyst-free, byproduct-free, in situ polymerization mechanism to synthesize new polymeric materials with various structures and morphologies. These synthetic strategies include fabrication of rod-like polymers with polyester, dendrimer, and chiral imide side chains, functionalization of carbon nanomaterials by surface-grafting conjugated polymers, formation of nanoparticles by intramolecular collapse of single polymer chains, and construction of carbon nanomembranes on the external and internal surface of inorganic nanomaterials. These polymers with novel structural features have been used in a variety of fields, such as energy transformation, energy storage, catalyst support, and fluorescent detection. Finally, the outlook for future developments of Bergman cyclization in polymer science is presented.

First succinyl-proteome profiling of extensively drug-resistant Mycobacterium tuberculosis revealed involvement of succinylation in cellular physiology.

Protein lysine succinylation, an emerging protein post-translational modification widespread among eukaryotic and prokaryotic cells, represents an important regulator of cellular processes. However, the extent and function of lysine succinylation in Mycobacterium tuberculosis, especially extensively drug-resistant strain, remain elusive. Combining protein/peptide prefractionation, immunoaffinity enrichment, and LC-MS/MS analysis, a total of 686 succinylated proteins and 1739 succinylation sites of M. tuberculosis were identified, representing the first global profiling of M. tuberculosis lysine succinylation. The identified succinylated proteins are involved in a variety of cellular functions such as metabolic processes, transcription, translation, and stress responses and exhibit different subcellular localization via GO, protein interaction network, and other bioinformatic analysis. Notably, proteins involved in protein biosynthesis and carbon metabolism are preferred targets of lysine succinylation. Moreover, two prevalent sequence patterns: EK(suc) and K*****K(suc), can be found around the succinylation sites. There are 109 lysine-succinylated homologues in E. coli, suggesting highly conserved succinylated proteins. Succinylation was found to occur at the active sites predicted by Prosite signature including Rv0946c, indicating that lysine succinylation may affect their activities. There is extensive overlapping between acetylation sites and succinylation sites in M. tuberculosis. Many M. tuberculosis metabolic enzymes and antibiotic resistance proteins were succinylated. This study provides a basis for further characterization of the pathophysiological role of lysine succinylation in M. tuberculosis.

Emergence of carbapenem-resistant clinical Enterobacteriaceae isolates from a teaching hospital in Shanghai, China.

Carbapenems such as imipenem and meropenem are first-line agents for the treatment of serious nosocomial infections caused by multidrug-resistant clinical isolates of bacteria belonging to the family Enterobacteriaceae. However, resistance to carbapenems has increased dramatically among members of the family Enterobacteriaceae isolated from a teaching hospital in Shanghai, China. In the present study, we investigated the prevalence and molecular characteristics of carbapenem-resistant clinical isolates of Enterobacteriaceae. None of the 77 clinical isolates collected from 2002 to 2009 were susceptible to ertapenem and only 6.5 % and 1.3 % of isolates were susceptible to imipenem and meropenem, respectively. Colistin and tigecycline were found to be the most active agents against carbapenem-resistant Enterobacteriaceae isolates, inhibiting 90 % of isolates at a concentration of 1 µg ml(-1) and 4 µg ml(-1), respectively. The results of PFGE analysis suggested that many of the KPC-2-producing isolates of Citrobacter freundii and Klebsiella pneumoniae were clonally related. Most of these isolates were isolated from the same ward, namely the neurosurgical ward, suggesting horizontal transfer of the KPC-2-encoding gene in these isolates. Of the 77 isolates, 84.4 % were found, by PCR, to be capable of carbapenemase production. SDS-PAGE analysis revealed that 75.3 % (58/77) of the isolates had lost at least one porin protein. Our results suggested that the prompt detection of carbapenemase-producing strains is critical for the containment of nosocomial transmission. As no novel antimicrobials have been identified for use in the treatment of these pan-drug-resistant isolates, further studies should focus on the rational use of available antibiotics, the implementation of active antibiotic resistance surveillance and the strict implementation of infection control measures to avoid the rapid spread or outbreak of carbapenemase-producing Enterobacteriaceae in health-care facilities.

Occurrence of false positive results for the detection of carbapenemases in carbapenemase-negative Escherichia coli and Klebsiella pneumoniae isolates.

Adequate detection of the production of carbapenemase in Enterobacteriaceae isolates is crucial for infection control measures and the appropriate choice of antimicrobial therapy. In this study, we investigated the frequency of false positive results for the detection of carbapenemases in carbapenemase-negative Escherichia coli and Klebsiella pneumoniae clinical isolates by the modified Hodge test (MHT). Three hundred and one E. coli and K. pneumoniae clinical isolates were investigated. All produced extended spectrum ß-lactamases (ESBLs) but were susceptible to carbapenems. Antimicrobial susceptibility testing was performed by the disk diffusion and agar dilution methods. The MHT was performed using the standard inoculum of test organisms recommended by the CLSI. Genes that encoded ESBLs and carbapenemases were identified by PCR and DNA sequencing. Among the 301 clinical isolates, none of the isolates conformed to the criteria for carbapenemase screening recommended by the CLSI. The susceptibility rates for imipenem, meropenem, and ertapenem all were 100.0%, 100.0%, and 100.0%, respectively. Of the 301 E. coli and K. pneumoniae isolates, none produced carbapenemase. The MHT gave a positive result for 3.3% (10/301) of the isolates. False positive results can occur when the MHT is used to detect carbapenemase in ESBL-producing isolates and clinical laboratories must be aware of this fact.

Prevalence of plasmid-mediated quinolone resistance determinants in Citrobacter freundii isolates from Anhui province, PR China.

This study was conducted to detect and analyse the presence of plasmid-mediated quinolone resistance (PMQR) determinants [qnr, aac(6')-Ib-cr and qepA] among Citrobacter freundii isolates from patients in Anhui province, PR China. During 2009-2010, 31 C. freundii strains were collected from various hospital units and patient specimens. Using PCR, qnr genes were detected in eight isolates, but aac(6')-Ib-cr and qepA genes were not found. The genes qnrA1, qnrB1, qnrB2, qnrB4, qnrB10 and qnrB24 were present in 6.5, 3.2, 6.5, 3.2, 3.2 and 3.2% of C. freundii isolates, respectively. A new subgene of qnrB variant (qnrB24) was found and identified for what we believe to be the first time. PFGE after XbaI digestion of genomic DNA indicated that qnr-positive strains were not clonally related. Conjugation experiments were conducted to determine whether the qnr-carrying plasmids were self-transferable, and plasmids of transconjugants were extracted and analysed. The qnr genes were transferred from three clinical isolates to their transconjugants. Two qnrA1 genes transferred quinolone resistance with a plasmid of ~11 kb, whilst the size of the plasmid carrying the qnrB4 gene was ~64 kb. The susceptibility of positive isolates and transconjugants was tested using an agar dilution method according to Clinical and Laboratory Standards Institute guidelines, and the MICs of ciprofloxacin and levofloxacin were determined using Etest strips. Most isolates with qnr genes were resistant to fluoroquinolones and other antimicrobial agents. The MICs of transconjugants showed reduced susceptibility to fluoroquinolones.

Detection and spread of carbapenem-resistant Citrobacter freundii in a teaching hospital in China.

BACKGROUND: We examined the detection and spread of carbapenem-resistant Citrobacter freundii in Huashan Hospital, Shanghai, China between 2005 and 2008. METHODS: Twenty-three isolates of carbapenem-resistant C freundii collected in our hospital underwent resistant gene amplification by polymerase chain reaction, followed by minimal inhibitory concentration (MIC) analysis. Molecular epidemiologic analyses included pulsed-field gel electrophoresis and case study. RESULTS: Analysis of MICs with amikacin, gentamicin, cefotaxime, ceftazidime, cefepime, imipenem, meropenem, ertapenem, cefoxitin, piperacillin-tazobactam, and ciprofloxacin characterized the isolates as highly resistant to antimicrobials. Colistin, tigecycline, minocycline, and doxycycline to all C freundii isolates had lower MICs than the other antimicrobials tested, with MIC(50)/MIC(90) values of 0.5/1, 1/1, 4/8, and 4/4 mg/L, respectively. Molecular typing using pulsed-field gel electrophoresis classified the isolates into 4 groups, of which 15 isolates belonged to a single clone. In total, all of the isolates produced KPC-2-type carbapenemase, of which most were likely to couple with CTX-M-type extended-spectrum ß-lactamases and plasmid-mediated CMY-2-type AmpC enzyme. Subsequent clinical investigations involving the general status of patients, the ward, and antimicrobial and therapeutic outcomes showed that a carbapenem-resistant clone had spread critically in the Department of Neurosurgery. Potential risk factors were identified, including invasive procedures, surgical operations, use of indwelling urine catheters, and number of sickbed changes. CONCLUSION: The spread of carbapenem-hydrolyzing C freundii isolates has emerged in regional hospitals in China. Multidrug-resistant mechanisms of strains severely hamper control efforts. Our findings should alert clinicians to issues involved with preventing the spread of carbapenem-resistant C freundii.

Synthesis and evaluation of (S,S)-N,N'-bis-[3-(2,2',6,6'-tetramethylbenzhydryloxy)-2-hydroxy-propyl]-ethylenediamine (S2824) analogs with anti-tuberculosis activity.

In order to identify new and potent candidate drugs to treat tuberculosis, a library of compounds was screened, and (S,S)-N,N'-bis-[3-(2,2',6,6'-tetramethylbenzhydryloxy)-2-hydroxy-propyl]-ethylenediamine (S2824) was identified as a hit in the screen. This research discusses our efforts to synthesize and test 30 analogs of this hit for activity against Mycobacterium tuberculosis. Two compounds with homopiperazine ring possess high in vitro activity against drug sensitive and resistant M. tuberculosis with MICs 0.78-3.13 microg/mL (or 1.22-4.88 microM).

Expression and characterization of two functional methionine aminopeptidases from Mycobacterium tuberculosis H37Rv.

Methionine aminopeptidase (MetAP) carries out an essential posttranslational modification of nascent proteins by removing the N-terminal methionine and is a potential target for discovering antibacterial agents. To characterize and compare the two MetAPs in Mycobacterium tuberculosis, Rv0734 and Rv2861c genes encoding MetAPs from genome of Mycobacterium tuberculosis H37Rv were cloned and expressed in Escherichia coli. Comparative analysis showed that the two recombinant Mycobacterium tuberculosis MetAPs (MtMetAPs, with 6His-tag being cleaved) have different activities in their substrate specificity, divalent ion requirement, and temperature optima. The temperature for MtMetAP1a and MtMetAP1c were 55 and 37 degrees C, respectively, and MtMetAP1a was found to have good temperature stability. The activities of MtMetAPs were increased by Co2+ ions, but were strongly inhibited by Cu2+, Fe2+, and Ni2+. In addition, the MtMetAP1a and MtMetAP1c activities were stimulated by Mg2+ and Zn2+, respectively. Transcriptional comparative analysis of these two genes revealed that, in both H37Ra and H37Rv, there was approximately a 2-fold decrease of Rv0734 transcripts in 60-day-old stationary phase culture comparing to that in 14-day-old log phase bacilli. On the other hand, the transcription level of Rv2861c in tested mycobacteria in log phase culture was nearly 1.5 times lower than that in stationary phase culture. The result suggests that the two MtMetMAPs may perform important function in different growth phases of Mycobacterium tuberculosis.

Expression, purification, and characterization of a functionally active Mycobacterium tuberculosis UDP-glucose pyrophosphorylase.

Tuberculosis, which is caused by Mycobacterium tuberculosis, remains to be a global health problem. The thick and complex cell envelope has been implicated in many aspects of the pathogenicity of M. tuberculosis. M. tuberculosis UDP-glucose pyrophosphorylase (UGP, coded by galU, Rv0993) is involved in cell envelope precursor synthesis. UGP catalyzes the reversible formation of UDP-glucose and inorganic pyrophosphate from UTP and glucose 1-phosphate (Glc-l-P). Bacterial UGPs are completely unrelated to their eukaryotic counterparts. This enzyme is recognized as a virulence factor in several bacterial species and is conserved among mycobacterial species, which makes it a good target for mycobacterial pathogenicity research. The recombinant M. tuberculosis UGP (rMtUGP) was purified in Escherichia coli and found to be stable and catalytically active. The effects of pH, temperature and Mg2+ on enzyme activity were characterized. In addition, subcellular localization studies revealed that most of M. tuberculosis UGP protein was located in the cell wall. The purification and characterization of M. tuberculosis UGP may help to decipher the pathogenicity of M. tuberculosis.