Good adaptability of freshmen in medical universities under the Coronavirus 2019 pandemic: a questionnaire-based single center study in China.

OBJECTIVE: To investigate the adaptability of freshmen in medical universities to the Coronavirus Disease 2019 (COVID-19) pandemic and to understand the relevant factors affecting their adaptation in medical university. METHODS: Freshmen in a medical university in Guangdong Province were selected and surveyed using a self-administered general questionnaire and a college student adjustment scale prepared by Fang Xiaoyi et al. The results were analyzed statistically. RESULTS: A total of 741 questionnaires were collected and 736 valid questionnaires were recovered. The adaptation level of freshmen in the medical university was moderately high. There were no differences in gender, age, family geographical location, or higher education level, but there were significant differences in major, type of household, only children (yes/no), and voluntary enrollment in medicine (yes/no). The survey showed that 30.3% of the students had discomfort at the beginning of the semester, 92.5% chose medical university voluntarily, and 83.4% expressed their enhanced motivation to study medicine after the COVID-19 outbreak, but 65.1% exhibited influence in study and life caused by COVID-19, which were statistically significant factors affecting the adaptation score. CONCLUSIONS: Freshmen in the medical university are generally well-adjusted with many influencing factors. Medical schools should strengthen adaptability management in order to timely identify the adaptation challenges of the students.

Hydrolysis of lignocellulose to succinic acid: a review of treatment methods and succinic acid applications.

Succinic acid (SA) is an intermediate product of the tricarboxylic acid cycle (TCA) and is one of the most significant platform chemicals for the production of various derivatives with high added value. Due to the depletion of fossil raw materials and the demand for eco-friendly energy sources, SA biosynthesis from renewable energy sources is gaining attention for its environmental friendliness. This review comprehensively analyzes strategies for the bioconversion of lignocellulose to SA based on the lignocellulose pretreatment processes and cellulose hydrolysis and fermentation principles and highlights the research progress on acid production and SA utilization under different microbial culture conditions. In addition, the fermentation efficiency of different microbial strains for the production of SA and the main challenges were analyzed. The future application directions of SA derivatives were pointed out. It is expected that this research will provide a reference for the optimization of SA production from lignocellulose.

Intuitive Analysis of the Microtribological Behavior of Copper-Coated Graphite-Graphite/Cu Composites with High Graphite Contents.

To improve the combination of graphite and copper, the friction and wear of a graphite/copper composite with a high content of graphite (50 wt %), copper-coated graphite were used to modify it. To observe the distribution law of each phase in the material and the change of composite surface structure after the friction and wear experiment, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the micro-structure, friction film, debris, and friction cross section of the composites. The results show that the large particle size of copper-coated graphite is anisotropic in the material, which helps to form a friction film with a high graphite content on the contact surface. TEM images of the friction film and debris directly reflect the structure changes of graphite and copper during friction; under normal load and shear force, interlamellar detachment and interlamellar fracture of graphite occur, and its edge is folded and crimped, resulting in the loss of an ordered state in some regions, which results in the instability of crystal lattice and the transition from an ordered to disordered state of graphite, resulting in the (002) halo ring in FFT results. Severe plastic deformation and oxidation reactions occur in copper, and copper oxides are formed, forming a high-strength and smooth oxide film in the metal-rich area and improving the wear resistance of the material. TEM images of the friction section directly show that an inverted triangular deformation zone is formed on the surface of the sample after friction and wear experiments. The edge of the deformation zone is stepped, consisting of a drag zone and an accumulation zone, and the surface of the contact zone is covered by a carbon film.

Pre-existing chromatin accessibility of switchable repressive compartment delineates cell plasticity.

Cell plasticity endows differentiated cells with competence to be reprogrammed to other lineages. Although extrinsic factors driving cell-identity conversion have been extensively characterized, it remains elusive which intrinsic epigenetic attributes, including high-order chromatin organization, delineate cell plasticity. By analysing the transcription-factor-induced transdifferentiation from fibroblasts to hepatocytes, we uncovered contiguous compartment-switchable regions (CSRs) as a unique chromatin unit. Specifically, compartment B-to-A CSRs, enriched with hepatic genes, possessed a mosaic status of inactive chromatin and pre-existing and continuous accessibility in fibroblasts. Pre-existing accessibility enhanced the binding of inducible factor Foxa3, which triggered epigenetic activation and chromatin interaction as well as hepatic gene expression. Notably, these changes were restrained within B-to-A CSR boundaries that were defined by CTCF occupancy. Moreover, such chromatin organization and mosaic status were detectable in different cell types and involved in multiple reprogramming processes, suggesting an intrinsic chromatin attribute in understanding cell plasticity.

Cross-resistance, fitness costs, and biochemical mechanism of laboratory-selected resistance to tenvermectin A in Plutella xylostella.

BACKGROUND: Tenvermectin A is a new avermectin derivative that has good insecticidal and acaricidal effects. In order to study the resistance of Plutella xylostella to tenvermectin A, a sensitive strain (SS) and a laboratory-selected tenvermectin A-resistant strain (RS, 33.57-fold) were used to evaluate cross-resistance and fitness costs as well as to determine the resistance mechanism. RESULTS: There was no cross-resistance with common pesticides except for moderate cross-resistance with cypermethrin (resistance ratio = 10.26-fold) observed in RS. The activities of metabolic enzymes were measured, and the results showed that mixed function oxidase (MFO) and carboxylate esterase (CarE) in RS increased significantly by 2.92- and 2.86-fold, respectively, compared with SS. In addition, there was no obvious difference in glutathione-S-transferase (GST), which indicated that enhanced MFO and CarE activities may be the main mechanisms of detoxification. In the four typical resistance-related genes, expression of GluCl (4.86-fold), ABCC2 (3.85-fold), and CYP6 (2.94-fold) in RS were significantly promoted, but expression of GST was not. The clone and sequence of the PxGluClα subunit displayed six mutations that could lead to changes in the amino acid residues. CONCLUSION: High suitability related to tenvermectin A resistance was observed in RS, and it was found that the developmental stages of RS were significantly shortened and the survival rate of females was reduced. In addition, the mechanism of resistance to tenvermectin A may be regulated by the glutamate-gated chloride channel, ATP-binding cassette transporter, and MFO. In general, the study of resistance and biochemical mechanisms can provide beneficial and rational information for the management of resistance in P. xylostella. © 2021 Society of Chemical Industry.

A Homeostatic Arid1a-Dependent Permissive Chromatin State Licenses Hepatocyte Responsiveness to Liver-Injury-Associated YAP Signaling.

Following injury, differentiated epithelial cells can serve as a stem cell-independent source for tissue regeneration by undergoing reprogramming into other cell types. The intrinsic molecular basis underlying plasticity of differentiated cells remains largely unaddressed. Here we show that Arid1a, a key component of the SWI/SNF chromatin remodeling complex, controls liver regeneration and gene expression associated with emergence of injury-induced liver-progenitor-like cells (LPLCs). Hepatocyte-specific Arid1a ablation reduces LPLC gene expression in several models of periportal liver injury and impairs liver regeneration, leading to organ dysfunction. Arid1a establishes a permissive chromatin state at LPLC-enriched genes during homeostasis, suggesting it endows hepatocytes with competence to respond to injury-induced signals. Consistently, Arid1a facilitates binding of YAP, a critical regeneration signaling pathway, to LPLC-enriched genes, and Arid1a deletion prevents their YAP-associated induction following injury. Together, these findings provide a framework for studying the contributions of injury-induced LPLCs to periportal liver regeneration.

An emm5 Group A Streptococcal Outbreak Among Workers in a Factory Manufacturing Telephone Accessories.

Ranked among the top10 infectious causes of death worldwide, group A Streptococcus (GAS) causes small- and large-scale outbreaks, depending on the trigger as transmission of a GAS strain or expansion of predominant clones. In China, GAS infections other than scarlet fever are not notifiable. In Shanghai, an epidemiological investigation was initiated after two successive severe pneumonia cases with one death in a digital factory, from where outbreaks are less widely reported. The investigation was performed using emm typing, pulsed-field gel electrophoresis (PFGE) typing, superantigen profiling, and genome analysis. This enabled characterization of relatedness among the outbreak isolates and identification of the mobile genetic elements present. Among 57 patients with respiratory symptoms investigated in the factory, emm5 GAS strains were isolated from 8 patients. The eight GAS infection cases comprising one fatal severe pneumonia case, six influenza-like illness cases, and one pharyngitis case. Two risk factors were identified: adult with an age of 18-20 years and close contact with a GAS patient or carrier. GAS attack rate was 14.0% (8/57), and GAS carriage rate was probably around 2.7% (14/521) based on surveys in two nearby districts. All the 10 outbreak associated isolates were assigned to emm5 and sequence type ST-99 (emm5/ST-99), harbored superantigen genes speC, speG, and smeZ, and were assigned to two similar PFGE patterns (clones). Among the outbreak associated isolates, all carried ermA with resistance to erythromycin and inducible resistance to clindamycin, and eight (80%) carried a tetM gene with resistance to tetracycline. Among the 14 carriage isolates, 12 were emm12/ST-36, and 2 were emm1/ST-28, all with superantigen genes speC, speG, ssa, and smeZ. All the carriage isolates harbored ermB and tetM with resistance to erythromycin, clindamycin, and tetracycline. Genome analysis showed the two outbreak clones were closely related and possessed new prophages carrying virulence gene sdc and antibiotic resistance genes of ermA and tetM, which were not found in the emm5 reference strain Manfredo. This is the first report of a GAS outbreak in this type of workplace. The outbreak was caused by two closely related emm5 clones that differed from the predominant emm types circulating in China.

Baf60b-mediated ATM-p53 activation blocks cell identity conversion by sensing chromatin opening.

Lineage conversion by expression of lineage-specific transcription factors is a process of epigenetic remodeling that has low efficiency. The mechanism by which a cell resists lineage conversion is largely unknown. Using hepatic-specific transcription factors Foxa3, Hnf1α and Gata4 (3TF) to induce hepatic conversion in mouse fibroblasts, we showed that 3TF induced strong activation of the ATM-p53 pathway, which led to proliferation arrest and cell death, and it further prevented hepatic conversion. Notably, ATM activation, independent of DNA damage, responded to chromatin opening during hepatic conversion. By characterizing the early molecular events during hepatic conversion, we found that Baf60b, a member of the SWI/SNF chromatin remodeling complex, links chromatin opening to ATM activation by facilitating ATM recruitment to the open chromatin regions of a panel of hepatic gene loci. These findings shed light on cellular responses to lineage conversion by revealing a function of the ATM-p53 pathway in sensing chromatin opening.

An outbreak of acute GII.17 norovirus gastroenteritis in a long-term care facility in China: The role of nursing assistants.

More than 30 residents and nursing assistants in a geriatric nursing hospital developed acute gastroenteritis from December 7th to December 18th, 2014 in Shanghai, China. An immediate epidemiological investigation was conducted to identify the etiological agent of the outbreak, mode of transmission and the risk factors. Cases were investigated according to an epidemiological questionnaire. Samples from cases, highly transmissible environmental surfaces and drinking water were collected for pathogens detection. A retrospective cohort study was conducted to explore the transmission mode. A total of 34 cases were affected in this acute gastroenteritis outbreak, including 23 residents, 9 nursing assistants and 2 doctors. 13 out of 30 samples were positive for GII.17 norovirus, no other pathogen was detected. Nursing assistants who developed gastroenteritis symptoms had a higher attack rate in residents they cared than those who did not develop any gastroenteritis symptoms (p<0.001). The acute gastroenteritis outbreak was caused by GII.17 norovirus. Person-to-person close contact and contaminated environmental surfaces were the probable transmission route. Nursing assistants were considered to play an important role in the secondary spread of norovirus. The poor medical skill and personal hygiene habits of nursing assistants in China should be paid attention and improved urgently which is critically important to prevent hospital infections.

The novel norovirus genotype GII.17 is the predominant strain in diarrheal patients in Shanghai, China.

In the winter of 2014-2015, a novel norovirus (NoV) strain (GII.17) was reported to be the major cause of gastroenteritis outbreaks in East Asia. To determine the time course of gastroenteritis infections associated with the GII.17 strain and whether GII.17 was the main epidemic strain in diarrheal patients in Shanghai, 2169 stool samples were collected and tested. The detection rate of NoV GI and GII NoV strains was 0.83 and 24.02%, respectively. Phylogenetic analysis confirmed that there were seven NoV genotypes, among which GII.4 and GII.17 were the main genotypes. The GII.17 strain was first detected in a sample collected on August 14th, 2014, and beginning in January 2015, the novel GII.17 strain replaced the GII.4 strain as the dominant NoV genotype causing acute gastroenteritis in patients in Shanghai.

Epidemiological characteristics and pathogens attributable to hand, foot, and mouth disease in Shanghai, 2008-2013.

INTRODUCTION: Hand, foot, and mouth disease (HFMD) is a common childhood illness caused by enteroviruses. A passive surveillance system has been implemented in Shanghai Pudong since 2008 and etiology surveillance since 2009.We characterized the epidemiology and the etiology of HFMD in Pudong from 2008-2013. METHODOLOGY: Health care providers were required to report any clinically diagnosed HFMD to Pudong District Center for Disease Control and Prevention. For all severe cases and randomly selected mild HFMD cases, throat or rectal swabs or feces were collected for enterovirus detection by real time reverse transcription polymerase chain reaction. RESULTS: A total of 50,149 cases were reported, with average 8,508 per year (range: 3,577-13,202) and average incidence of 167.5/100,000 persons (range: 81.4-254.1/100,000 persons). HFMD was more likely to occur in children under five years of age (85.6%), while severe cases were more likely to happen in children under three years of age (63.9%). Every year in May or June, HFMD peaked in the region; two peaks were observed from 2011 to 2013.The most common etiologic agents are EV71 and CA16.Different types of enterovirus circulate in different years. EV71 was the predominant pathogen in severe cases. The proportions of EV71 in severe cases was higher than in mild cases at the children's medical center (p<0.001). CONCLUSIONS: HFMD remains an important public health issue in Shanghai. HFMD pathogen surveillance is required for more types of enteroviruses besides EV71 and CA16, which would give a better picture of the etiology of HFMD.

[Infection status and virulent genes of Aeromonas in diarrhea patients in Pudong New Area, Shanghai].

OBJECTIVE: To investigate the infection status and virulent genes of Aeromonas in patients with acute diarrhea in Pudong New Area, Shanghai. METHODS: In 2012, stool samples were collected from diarrhea patients in 12 sentinel hospitals in Pudong for the detections of 13 pathogens causing diarrhea, and the detections of 5 diarrhea related virulent genes were conducted for Aeromonas isolates. RESULTS: A total of 101 patients were infected with Aeromonas in 2533 patients (4.0%). A total of 101 Aeromonas strains were isolated, including 17 Aeromonas hydrophila strains (18.8%), 44 Aeromonas veronii biovar sobria strains (52.5%) and 12 Aeromonas caviae strains (29.7%). And 44 coinfections with other pathogens were detected. Aeromonas infection mainly occurred in summer and in people aged ≥20 years. Among the patients infected with Aeromonas, 71 (70.3%) had watery diarrhea, 20 (19.8%) had vomiting and 11 (10.9%) had fever. Virulent genes detection showed that 95.0% of the Aeromonas. strains carried virulent genes, and the detection rates of hlyA, aerA, act, alt, and ast genes were 5.9%, 6.9%, 67.3%, 42.6% and 13.9%, respectively. CONCLUSIONS: High incidence of Aeromonas infection was found in the patients with acute diarrhea in Pudong, and a high proportion of coinfections with other pathogens was detected too. Most Aeromonas strains carried virulent genes, and the distribution varied.

The clinical and etiological characteristics of influenza-like illness (ILI) in outpatients in Shanghai, China, 2011 to 2013.

INTRODUCTION: Clinical and etiological characteristics of influenza-like illness (ILI) in outpatients is poorly understood in the southern temperate region of China. We conducted laboratory-based surveillance of viral etiology for ILI outpatients in Shanghai from January 2011 to December 2013. MATERIALS AND METHODS: Clinical and epidemiological data from ILI outpatients, both children and adults, were collected. A total of 1970 nasopharyngeal swabs were collected and tested for 12 respiratory viruses using multiplex RT-PCR, and the data were analyzed anonymously. RESULTS: All 12 respiratory viruses were detected in the specimens. At least one virus was detected in 32.4% of 1970 specimens analyzed, with 1.1% showing co-infections. The most frequently detected agents were influenza A (11.7%), influenza B (9.6%), and rhinoviruses (3.1%).Other viruses were present at a frequency less than 3.0%. We observed a winter peak in the detection rate in ILI patients during 3 years of surveillance and a summer peak in 2012. HCoV, HADV, and HMPV were detected more frequently in children than in adults. Patients infected with influenza virus experienced higher temperatures, more coughs, running noses, headaches and fatigue than patients infected with other viruses and virus-free patients (p<0.001). CONCLUSIONS: The spectrum, seasonality, age distribution and clinical associations of respiratory virus infections in children and adults with influenza-like illness were analyzed in this study for the first time. To a certain extent, the findings can provide baseline data for evaluating the burden of respiratory virus infection in children and adults in Shanghai. It will also provide clinicians with helpful information about the etiological patterns of outpatients presenting with complaints of acute respiratory syndrome, but further studies should be conducted, and longer-term laboratory-based surveillance would give a better picture of the etiology of ILI.

An outbreak of acute norovirus gastroenteritis in a boarding school in Shanghai: a retrospective cohort study.

BACKGROUND: More than 200 students and teachers at a boarding school in Shanghai developed acute gastroenteritis in December, 2012. The transmission mode remained largely unknown. An immediate epidemiological investigation was conducted to identify it. METHODS: Using a retrospective cohort design, we investigated demographic characteristics, school environment, and previous contacts with people who had diarrhea and/or vomiting, drinking water conditions, recalls of food consumption in the school cafeteria, hand-washing habits and eating habits. Rectal swabs of the new cases and food handlers as well as water and food samples were collected to test potential bacteria and viruses. Norovirus was detected by real-time reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: A total of 278 cases developed gastrointestinal symptoms in this outbreak, and the overall attack rate was 13.9%. The main symptoms included vomiting (50.0%), abdominal cramps (40.3%), nausea (27.0%), diarrhea (6.8%) and fever (6.8%). Twenty rectal swab samples were detected as Norovirus-positive, including 11 from student cases and 9 from asymptomatic food handlers (non-cases). Among environmental surface samples from the kitchen, 8 samples were also detected as Norovirus-positive. The genotypes of viral strains were the same (GII) in patients, asymptomatic food handlers and environmental surfaces. Other samples, including rectal swabs, water samples and food samples were negative for any bacteria and other tested viruses. Asymptomatic food handlers may have contaminated the cooked food during the food preparation. CONCLUSION: The study detected that the outbreak was caused by Norovirus and should be controlled by thorough disinfection and excluding asymptomatic food handlers from food preparation. Early identification of the predominant mode of transmission in this outbreak was necessary to prevent new cases. Furthermore, good hygiene practices such as regular hand washing and efficient daily disinfection should be promoted to prevent such infection and outbreaks.

[Purification of Taq DNA polymerase expressed in Escherichia coli].

Taq DNA polymerase is one of the most commonly thermostable DNA polymerases in molecular biological researches, which shares its basic characters with others of the family, thereby its purifying strategy could be used not only in itself production but also in the extraction of the others as a reference. At present, the protocols reported for large scale preparation of Taq DNA are high cost, so a cheaper method was described here. In this protocol, by heat denaturation, ammonium sulfate precipitation and cation exchange chromatography of 724 resin, about 18 g powder of Na form resin could recover about 27.07 mg of Taq enzyme. The total activity and specific activity were approximately 2.2 × 105 U and 8131.98 U/mg. The total yield was about 48.92% with 59.35 of purification folds. Analysis of quality of purified enzyme indicated that only one protein 94 kDa was identified against SDS-PAGE and the remnant of DNA nuclease was not detected. For PCR reaction, The amplification ability of purified Taq polymerase was not different from that of the commercially avail-able ones. This method reported in the present study is effective and low cost, making it suitable for general purification in laboratories or business production.

Use of 1-alkyl-3-methylimidazolium-based ionic liquids as background electrolytes in capillary electrophoresis for the analysis of inorganic anions.

Separation of inorganic anions in CE is often a challenging task because the electrophoretic mobilities of inorganic anions are comparable to or even greater than the EOF mobility. In this study, we present the use of ionic liquids (ILs) as background electrolytes (BGEs) in CE of inorganic anions. The 1-alkyl-3-methylimidazolium-based ILs as BGEs dynamically coated the capillary wall and induced a reversed EOF. This allowed the anions to comigrate with the EOF and yielded a rapid separation. Increasing the alkyl chain length of the ILs and BGE concentration can significantly improve the separation resolution. With 40 mM 1-butyl-3-methylimidazolium tetrafluoroborate as BGE, good separations of five model anions (Br-, I-, NO2(-), NO3(-), and SCN-) were achieved in a range of buffer pH values. The separation efficiency was as high as 34 600-155 000, and the RSDs of the migration times were less than 0.8% (n = 5).