Co-metabolic degradation and metabolite detection of hexabromocyclododecane by Shewanella oneidensis MR-1.

Hexabromocyclododecane (HBCD) is a widely used brominated flame retardant; however, it is a persistent organic pollutant as well as affects the human thyroid hormones and causes cancer. However, the degradation of HBCD has received little attention from researchers. Due to its bioaccumulative and hazardous properties, an appropriate strategy for its remediation is required. In this study, we investigated the biodegradation of HBCD using Shewanella oneidensis MR-1 under optimized conditions. The Box-Behnken design (BBD) was implemented for the optimization of the physical degradation parameters of HBCD. S. oneidensis MR-1 showed the best degradation performance at a temperature of 30 °C, pH 7, and agitation speed of 115 rpm, with an HBCD concentration of 1125 µg/L in mineral salt medium (MSM). The strain tolerated up to 2000 µg/L HBCD. Gas chromatography-mass spectrometry analysis identified three intermediates, including 2-bromo dodecane, 2,7,10-trimethyldodecane, and 4-methyl-1-decene. The results provide an insightful understanding of the biodegradation of HBCD by S. oneidensis MR-1 under optimized conditions and could pave the way for further eco-friendly applications. KEY POINTS: • HBCD biodegradation by Shewanella oneidensis • Optimization of HBCD biodegradation by the Box-Behnken analysis • Identification of useful metabolites from HBCD degradation.

Molecular epidemiology analysis of symptomatic and asymptomatic norovirus infections in Chinese infants.

BACKGROUND: Norovirus is a leading cause of acute gastroenteritis among children. Previous studies based on symptomatic infections indicated that mutations, rather than recombination drove the evolution of the norovirus ORF2. These characteristics were found in hospital-based symptomatic infections, whereas, asymptomatic infections are frequent and contribute significantly to transmission. METHODS: We conducted the first norovirus molecular epidemiology analysis covering both symptomatic and asymptomatic infections derived from a birth cohort study in the northern China. RESULTS: During the study, 14 symptomatic and 20 asymptomatic norovirus infections were detected in 32 infants. Out of the 14 strains that caused symptomatic infections, 12 strains were identified as GII.3[P12], and others were GII.4[P31]. Conversely, 17 asymptomatic infections were caused by GII.4[P31], two by GII.2[P16], and one by GII.4[P16]. Regardless of symptomatic and asymptomatic infections, the mutations were detected frequently in the ORF2 region, and almost all recombination were identified in the RdRp-ORF2 region. The majority of the mutations were located around the predefined epitope regions of P2 subdomain indicating a potential for immune evasion. CONCLUSION: The role of symptomatic as well as asymptomatic infections in the evolution of norovirus needs to be evaluated continuously.

Genetic characterization of two G8P[8] rotavirus strains isolated in Guangzhou, China, in 2020/21: evidence of genome reassortment.

BACKGROUND: The G8 rotavirus genotype has been detected frequently in children in many countries and even became the predominant strain in sub-Saharan African countries, while there are currently no reports from China. In this study we described the genetic characteristics and evolutionary relationship between rotavirus strains from Guangzhou in China and the epidemic rotavirus strains derived from GenBank, 2020-2021. METHODS: Virus isolation and subsequent next-generation sequencing were performed for confirmed G8P[8] specimens. The genetic characteristics and evolutionary relationship were analyzed in comparison with epidemic rotavirus sequences obtained from GenBank. RESULTS: The two Guangzhou G8 strains were DS-1-like with the closest genetic distance to strains circulating in Southeast Asia. The VP7 genes of the two strains were derived from a human, not an animal G8 rotavirus. Large genetic distances in several genes suggested that the Guangzhou strains may not have been transmitted directly from Southeast Asian countries, but have emerged following reassortment events. CONCLUSIONS: We report the whole genome sequence information of G8P[8] rotaviruses recently detected in China; their clinical and epidemiological significance remains to be explored further.

Repair of Bone Defects With Endothelial Progenitor Cells and Bone Marrow-Derived Mesenchymal Stem Cells With Tissue-Engineered Bone in Rabbits.

PURPOSE: This study aimed to investigate the repair of bone defects in rabbits with tissue-engineered bones using cocultured endothelial progenitor cells (EPCs) and bone marrow mesenchymal stem cells (BMSCs) as seeding cells. METHODS: Endothelial progenitor cells and BMSCs were isolated and purified from the peripheral blood and bone marrow, respectively, of New Zealand rabbits. The third passage of BMSCs was cultured alone or with EPCs. Cells were characterized using specific markers and then seeded on partially deproteinized biologic bones from pigs as a scaffold. The engineered bones were used to repair bone defects in rabbits. Hematoxylin and eosin and Masson staining were performed to examine vascularization and osteogenesis in the engineered bone. RESULTS: The cocultured EPCs and BMSCs grew well on the surface of the scaffold. Compared with monocultured BMSCs, cocultured EPCs and BMSCs promoted the formation of blood vessels and bone on the scaffold, in addition to accelerating the repair of bone defects. The collagen content was significantly increased in the scaffold with cocultured EPCs and BMSCs, compared with the scaffold seeded with mono-cultured BMSCs. CONCLUSIONS: Tissue-engineered bones seeded with cocultured EPCs and BMSCs may be used effectively for the repair of bone defects.

Melatonin attenuates nicotine-induced autophagy and neurological changes by decreasing the production of reactive oxygen species.

Purpose: The aim of this study was to explore the mechanism of neurological changes underlying the toxicity of nicotine.Materials and methods: Rat pheochromocytoma 12 (PC12) cells and human neuroglia (HM) cells were used. The ROS levels of the cells were detected by the FACScan. Autophagy flux was monitored by a tandem monomeric RFP-GFP-tagged LC3 lentivirus. The autophagic proteins LC3, SQSTM1/p62 and Beclin1 were detected by western blot assay. In order to evaluate the effects of nicotine and melatonin on the morphological changes of neurons, primary cortical neurons were obtained and immunocytochemistry of TUBB3 tubulin were conducted.Results: Nicotine increased the levels of reactive oxygen species (ROS) in PC12 and HM cells in a concentration-dependent manner. Microscopy showed increased autophagic flux in nicotine-treated PC12 cells. Subsequent western blotting results showed that nicotine induced increase in the levels of LC3B-II and Beclin1, and decreased SQSTM1/p62 in a concentration-dependent manner. Finally, nicotine treatment reduced the length of TUBB3-positive axons and dendrites. Melatonin, a mitochondrially targeted antioxidant, reduced the ROS level, and blocked autophagy activation and the morphologic structural changes induced by nicotine.Conclusions: Our results suggested that the role of nicotine in neuronal toxicity maybe through the induction of ROS and the subsequent activation of autophagy. These effects could be restored by melatonin.

Evidence that TP_0144 of Treponema pallidum is a thiamine-binding protein.

Thiamine pyrophosphate (TPP), the biologically active form of thiamine (also known as vitamin B1), is an essential cofactor for several important enzymes involved in carbohydrate metabolism, and therefore, it is required for all living organisms. We recently found that a thiamine-binding protein (TDE_0143) is essential for the survival of Treponema denticola, an important bacterial pathogen that is associated with human periodontitis. In this report, we provide experimental evidence showing that TP_0144, a homolog of TDE_0143 from the syphilis spirochete Treponema pallidum, is a thiamine-binding protein that has biochemical features and functions that are similar to those of TDE_0143. First, structural modeling analysis reveal that both TDE_0143 and TP_0144 contain a conserved TPP-binding site and share similar structures to the thiamine-binding protein of Escherichia coli. Second, biochemical analysis shows that these two proteins bind to TPP with similar dissociation constant (Kd) values (TDE_0143, Kd of 36.50 nM; TP_0144, Kd of 32.62 nM). Finally, heterologous expression of TP_0144 in a ΔTDE_0143 strain, a previously constructed TDE_0143 mutant of T. denticola, fully restores its growth and TPP uptake when exogenous thiamine is limited. Collectively, these results indicate that TP_0144 is a thiamine-binding protein that is indispensable for T. pallidum to acquire exogenous thiamine, a key nutrient for bacterial survival. In addition, the studies shown in this report further underscore the feasibility of using T. denticola as a platform to study the biology and pathogenicity of T. pallidum and probably other uncultivable treponemal species as well.

The construction and validation of a frailty risk prediction model for older adults with lung cancer: A cross-sectional study.

OBJECTIVE: We aimed to construct and internally validate a frailty risk prediction model in older adults with lung cancer. METHOD: In total, 538 patients were recruited in a grade A tertiary cancer hospital in Tianjin, and patients were randomly divided into the training group (n = 377) and the testing group (n = 166) at a ratio of 7:3. The Frailty Phenotype scale was used to identify frailty and logistic regression analysis was used to identify the risk factors and establish a frailty risk prediction model. RESULTS: In the training group, logistic regression showed that age, fatigue-related symptom cluster, depression, nutritional status, D-dimer level, albumin level, presence of comorbidities, and disease course were independent risk factors for frailty. The areas under the curve (AUCs) of the training and testing groups were 0.921 and 0.872, respectively. A calibration curve of P = 0.447 validated model calibration. The decision curve analysis demonstrated greater clinical benefit when the threshold probability was >20%. CONCLUSION: The prediction model had a favorable prediction power for determining the risk of frailty, contributing to the prevention and screening of frailty. Patients with a frailty risk score of more than 0.374 should be regularly monitored for frailty and receive personalized preventive interventions.

Cost-of-illness of gastroenteritis caused by rotavirus in Chinese children less than 5 years.

Acute gastroenteritis (AGE) caused by rotavirus (RV) remains a public health issue in China. To accelerate the mass rotavirus vaccination, it is important to inform the policy maker, and the public of the economic burden caused by rotavirus infection. A meta-analysis was conducted applying standardized algorithms. Articles published before January 1, 2023, in English and Chinese were searched through PubMed, CNKI, and WanFang Data. Studies with cost analysis of RV AGE were included. A random-effects model was applied to synthesize the total cost of RV AGE from the societal perspective. A prospective survey aimed to measure the cost of RV AGE was conducted in 2021 and 2022 in Shaoxing city, Zhejiang province, that can represent the developed region. The cost data was applied as deviation indicator, in comparison with the pooled estimate generated from meta-analysis. Totally 286 articles were identified, and eventually 12 studies were included. The pooled total social cost of RV AGE was US$282.1 (95%CI: US$213.4-350.7). The pooled private cost of RV AGE was US$206.4 (95%CI: US$155.2-257.5). RV AGE hospitalized and RV AGE incurred in developed regions caused remarkable higher burden (US$631.2 [95%CI: US$512.6-749.8], and US$333.6 [95%CI: US$234.1-433.2] respectively), compared to RV AGE treated at outpatient, and incurred in less developed regions. Our study demonstrates that RV AGE causes a significant economic burden in China. Given the promising effectiveness and highly cost-effective, introduction of rotavirus vaccines in national immunization programs could substantially reduce the economic burden in China.

Prevalence and Evolution of Noroviruses between 1966 and 2019, Implications for Vaccine Design.

Noroviruses (NoVs), a group of single-stranded RNA viruses causing epidemic acute gastroenteritis in humans, are highly diverse, consisting of multiple genogroups with >30 genotypes. Their continual evolutions make NoV vaccine design and development difficult. Here, we report a study of NoV sequences obtained from a population-based diarrhea surveillance in Zhengding County of Hebei Province spanning from 2001 to 2019 and those available in the GenBank database from 1966 to 2019. NoV genotypes and/or variants that may evade immunity were screened and identified based on primary and conformational structures for vaccine design. We selected 366, 301, 139, 74 and 495 complete VP1-coding nucleotide sequences representing the predominant genotypes of GII.4, GII.2, GII.3, GII.6 and GII.17, respectively. A total of 16 distinct GII.4 variants were identified, showing a typical linear evolutionary pattern of variant replacement, while only 1-4 variants of the other genotypes were found to co-circulate over the 40-50-year period without typical variant replacement. The vaccine strain GII.4c is close to variant Sydney_2012 (0.053) in their primary structure, but they are distinct at epitopes A and E in conformations. Our data suggested GII.4 variant Sydney_2012, GII.2 variant A, a GII.3 strain, GII.6 variants B and C and GII.17 variant D are primary candidate strains for NoV vaccine development.

Burden and etiology of moderate and severe diarrhea in children less than 5 years of age living in north and south of China: Prospective, population-based surveillance.

BACKGROUND: Diarrhea remains the leading cause of childhood illness in China. Better understanding of burden and etiology of diarrheal diseases is important for development of effective prevention measures. METHODS: Population-based diarrhea surveillance was conducted in Sanjiang (southern China) year-round and Zhengding (northern China) in autumn/winter. Stool specimens were collected from children < 5 years of age experiencing diarrhea. The TaqMan Array Card (TAC), based on multiplex real-time PCR, was applied to detect multiple enteric microbial agents simultaneously. Results using these methods were compared to those derived from conventional PCR assays. RESULTS: During the study period, 6,380 children in Zhengding and 3,581 children in Sanjiang < 5 years of age participated. Three hundred and forty (31.2%) and 279 (22.9%) diarrhea episodes were identified as moderate-to-severe in the two counties, with incidence of 60.4 and 88.3 cases per 1,000 child-years in Zhengding and Sanjiang, respectively. The five most frequently detected bacterial and viral agents in Sanjiang were adenovirus, enterovirus, enteroaggregative Escherichia coli (EAEC), rotavirus, and sapovirus all the year round, while the most common viral agents in Zhengding were rotavirus, followed by astrovirus and adenovirus during the cool season. Compared to conventional PCR assay, the average incremental detection via the TAC method was twofold. CONCLUSION: Our study demonstrated high diversity and prevalence of multiple major bacterial and viral agents, including rotavirus and calicivirus, among children in China. Further studies are needed to define the public health significance of neglected but frequently detected pathogens such as EAEC, enterotoxigenic E. coli, Campylobacter, adenovirus, and enterovirus.

Genetic susceptibility to rotavirus infection in Chinese children: a population-based case-control study.

Rotaviruses (RVs) are the leading cause of acute gastroenteritis in children, while histo-blood group antigens (HBGAs) are believed to be host attachment and susceptibility factors of RVs. A large case-control study nested in a population-based diarrhea surveillance targeting children <5 y of age was performed in rural Hebei province, north China. Saliva and serum samples were collected from all participants to determine HBGA phenotyping, FUT2 mutations, and RV IgG antibody titers. A logistic model was employed to assess the association between host HBGA secretor status and risk of RV infection. Among 235 RV cases and 680 non-diarrhea controls studied, 82.4% of participants were IgG positive by an average age of 77 months. Out of the 235 RV cases, 216 (91.9%) were secretors, whereas the secretor rate was 76.3% in the non-diarrhea controls, resulted in an adjusted OR of 3.0 (95%CI: 1.9-4.7, P < .0001) between the two groups. Our population-based case-control study indicated a strong association between host HBGA secretor status and risk of RV infection in Chinese children. The high prevalence of Lewis-positive secretor status strongly suggests that Chinese children may be genetically susceptible to current co-circulating RV strains, and thus, a universal childhood immunization program against RV disease should be successful in China.

Burden of viral gastroenteritis in children living in rural China: Population-based surveillance.

BACKGROUND: Despite the considerable disease burden caused by the disease, rotavirus vaccine has not been introduced into routine national immunization schedule, and norovirus vaccines are being developed without a comprehensive understanding of gastroenteritis epidemiology. To bridge this knowledge gap, we investigated the disease burden of viral gastroenteritis in rural China. METHODS: Between October 2011 and December 2013, population-based surveillance was conducted in Zhengding and Sanjiang counties in China. Stool samples were collected from children <5 years of age with diarrhea. All specimens were tested for rotaviruses, noroviruses, sapoviruses, enteric adenoviruses, and astroviruses. RESULTS: The most common pathogen causing diarrhea was rotavirus (54.7 vs 45.6 cases/1,000 children/year in Zhengding and Sanjiang, respectively), followed by norovirus (28.4 vs 19.3 cases/1,000 children/year in Zhengding and Sanjiang, respectively). The highest incidence of these viruses was observed in children 6-18 months of age. Among the 5 viral pathogens, rotaviruses caused the most severe illness, followed by noroviruses. CONCLUSION: Rotavirus and norovirus are the 2 most important viral pathogens causing childhood diarrhea in both northern and southern China; they should be the major targets for viral gastroenteritis prevention strategies among children in China.

Inhibitory effect of dimeric beta peptide on the recurrence and metastasis of hepatocellular carcinoma in vitro and in mice.

AIM: To block the adhesion of tumor cells to the extracellular matrix, and prevent tumor metastasis and recurrence, the dimer of the beta peptide (DLYYLMDLSYSMKGGDLYYLMDLSYSMK, beta2) was designed and synthesized and its anti-adhesion and anti-invasion effects on hepatocellular carcinoma cells were assessed. Additionally, its influence on the metastasis and recurrence of mouse hepatocellular carcinoma was measured. METHODS: The anti-adhesion effect of beta2 on the highly metastatic hepatocellular carcinoma cell line HCCLM6 cells and fibronectin (FN) was assayed by the MTT assay. The inhibition of invasion of HCCLM6 cells by beta2 was observed using a Transwell (modified Boyden chamber) and matrigel. Using the hepatocellular carcinoma metastasis model and LCI-D20 nude mice, the influence of beta2 on the metastasis and recurrence of hepatocellular carcinoma after early resection was investigated. RESULTS: HCCLM6 cells co-incubated with 100 mumol/L, 50 micromol/L, 20 micromol/L or 10 micromol/L beta2 for 3 h showed an obvious decrease in adhesion to FN. The adhesion inhibition ratios were 11.8%, 21.7%, 29.6% and 48.7%, respectively. Additionally, HCCLM6 cells cultured with 100 mumol/L beta2 had a dramatic decrease in cell invasion. beta2 was also observed to inhibit the incisal edge recurrence and the distant metastasis of nude mice hepatocellular carcinoma after early resection (P < 0.05). CONCLUSION: The beta2 peptide can specifically block the adhesion and invasion of HCCLM6 cells, and can inhibit HCC recurrence and metastasis of LCI-D20 model posthepatectomy in vivo. Thus, beta2 should be further studied as a new anti-tumor drug.

Differentiation of smooth muscle progenitor cells in peripheral blood and its application in tissue engineered blood vessels.

BACKGROUND: A major shortcoming in tissue engineered blood vessels (TEBVs) is the lack of healthy and easily attainable smooth muscle cells (SMCs). Smooth muscle progenitor cells (SPCs), especially from peripheral blood, may offer an alternative cell source for tissue engineering involving a less invasive harvesting technique. METHODS: SPCs were isolated from 5-ml fresh rat peripheral blood by density-gradient centrifugation and cultured for 3 weeks in endothelial growth medium-2-MV (EGM-2-MV) medium containing platelet-derived growth factor-BB (PDGF BB). Before seeded on the synthesized scaffold, SPC-derived smooth muscle outgrowth cell (SOC) phenotypes were assessed by immuno-fluorescent staining, Western blot analysis, and reverse transcription polymerase chain reaction (RT-PCR). The cells were seeded onto the silk fibroin-modified poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (SF-PHBHHx) scaffolds by 6x10(4) cells/cm2 and cultured under the static condition for 3 weeks. The growth and proliferation of the seeded cells on the scaffold were analyzed by 3-(4,5-dimethylthiazol-2-yl)-diphenyltetrazolium bromide (MTT) assay, scanning electron microscope (SEM), and 4,6-diamidino-2-phenylindole (DAPI) staining. RESULTS: SOCs displayed specific "hill and valley" morphology, expressed the specific markers of the SMC lineage: smooth muscle (SM) alpha-actin, calponin and smooth muscle myosin heavy chain (SM MHC) at protein and messenger ribonucleic acid (mRNA) levels. RT-PCR results demonstrate that SOCs also expressed smooth muscle protein 22alpha (SM22alpha), a contractile protein, and extracellular matrix components elastin and matrix Gla protein (MGP), as well as vascular endothelial growth factor (VEGF). After seeded on the SF-PHBHHx scaffold, the cells showed excellent metabolic activity and proliferation. CONCLUSION: SPCs isolated from peripheral blood can be differentiated into the SMCs in vitro and have an impressive growth potential in the biodegradable synthesized scaffold. Thus, SPCs may be a promising cell source for constructing TEBVs.

Prevalence and distribution of human papillomavirus genotypes in Chinese women between 1991 and 2016: A systematic review.

BACKGROUND: Human papillomavirus (HPV) associated cervical cancer is one of the most common cancers and ranked as the eighth most common killer for Chinese women. A dozen of HPV vaccines are being developed in China without a solid China-specific distribution of carcinogenic HPV types, thus, we performed this systematic review to explore the China-specific spectrum of high-risk types causing cancer. METHODS: Studies on HPV infection among Chinese women were searched. All retrieved articles were screened and reviewed by a standardized algorithm. Distribution of carcinogenic HPV types and age-specific prevalence were analyzed using random-effects model. RESULTS: A total of 303 articles were included in the final analysis. The top 10 common HPV types detected in ICC patients, in descending order of frequency, were HPV 16 (62.5%), 18 (12.4%), 58 (8.6%), 52 (5.7%), 33 (4.6%), 31 (3.5%), 55 (2.4%), 68 (2.4%), 53 (2.2%) and 45 (2.0%) respectively. Similar spectrum was found in women with precancer. The prevalence of HPV infection peaked between 20 and 24 years with a rate of 24.3%, thereafter declined substantially and stabilized at middle-ages. Compared to women living in the developed provinces, the second peak was observed among women aged 45-55 years in less developed regions. CONCLUSION: In general, the spectrum of HPV types in women with precancer/cancer and the pattern of age-specific prevalence were consistent with that of elsewhere worldwide. However, some distinguished characteristics could also be concluded, and these imprinting should be considered and integrated when developing vaccines and strategy for disease control in China.

Immune memory at 17-years of follow-up of a single dose of live attenuated hepatitis A vaccine.

BACKGROUND: In recent years, hepatitis A virus (HAV) infection has declined considerably in China, associated with wide deployment of HAV vaccines and improvement in socio-economic indicators. Towards the elimination of HA in the country, we assessed the duration and characteristics of immunity conferred by the widely used, locally manufactured HAV vaccine. METHODS: This is a longitudinal cohort study that followed recipients of a live attenuated HAV vaccine 17 years after the initial administration. Blood samples were collected from participants pre- and two-week post-booster HAV vaccine dose. Serum anti-HAV antibody was measured by ELISA method. Memory B and T cells were determined by ELISPOT and Flow Cytometry assays, respectively. RESULTS: A robust anamnestic response was observed two-week post-challenge. Both HAV-specific memory B cell and T cells remained, and responded quickly when re-encountering HAV. The magnitude of recall responses was present, regardless of the status of the serum anti-HAV antibody pre-booster. CONCLUSIONS: We demonstrated long-term immunity from the live attenuated HAV vaccine, including antibody persistence and immunological memory. Considering the conditions that make elimination of infectious diseases feasible, following polio, hepatitis A could be targeted for elimination in China.

Construction of tissue-engineered heart valves by using decellularized scaffolds and endothelial progenitor cells.

BACKGROUND: Tissue-engineered heart valves have the potential to overcome the limitations of present heart valve replacements. This study was designed to develop a tissue engineering heart valve by using human umbilical cord blood-derived endothelial progenitor cells (EPCs) and decellularized valve scaffolds. METHODS: Decellularized valve scaffolds were prepared from fresh porcine heart valves. EPCs were isolated from fresh human umbilical cord blood by density gradient centrifugation, cultured for 3 weeks in EGM-2-MV medium, by which time the resultant cell population became endothelial in nature, as assessed by immunofluorescent staining. EPC-derived endothelial cells were seeded onto the decellularized scaffold at 3 x 10(6) cells/cm(2) and cultured under static conditions for 7 days. Proliferation of the seeded cells on the scaffolds was detected using the MTT assay. Tissue-engineered heart valves were analyzed by HE staining, immunofluorescent staining and scanning electron microscopy. The anti-thrombogenic function of the endothelium on the engineered heart valves was evaluated by platelet adhesion experiments and reverse transcription-polymerase chain reaction (RT-PCR) analysis for the expression of endothelial nitric oxide synthase (eNOS) and tissue-type plasminogen activator (t-PA). RESULTS: EPC-derived endothelial cells showed a histolytic cobblestone morphology, expressed specific markers of the endothelial cell lineage including von Willebrand factor (vWF) and CD31, bound a human endothelial cell-specific lectin, Ulex Europaeus agglutinin-1 (UEA-1), and took up Dil-labeled low density lipoprotein (Dil-Ac-LDL). After seeding on the decellularized scaffold, the cells showed excellent metabolic activity and proliferation. The cells formed confluent endothelial monolayers atop the decellularized matrix, as assessed by HE staining and immunostaining for vWF and CD31. Scanning electron microscopy demonstrated the occurrence of tight junctions between cells forming the confluent monolayer. Platelets adhesion experiments suggested that the neo-endothelium was non-thrombogenic. The expression levels of eNOS and t-PA genes in the neo-endothelium were quite similar to those in human umbilical vein endothelial cells. CONCLUSIONS: EPCs isolated from the human umbilical cord blood can differentiate into endothelial cells in vitro and form a functional endothelium atop decellularized heart valve scaffolds. Thus, EPCs may be a promising cell source for constructing tissue-engineered heart valves.

Burden of acute gastroenteritis caused by norovirus in China: A systematic review.

BACKGROUND: To understand the epidemiology and disease burden of norovirus (NoVs) gastroenteritis in China, a systematic review was conducted. METHODS: Studies on acute gastroenteritis (AGE) caused by NoVs from mainland China, published before 2017 were searched. All retrieved articles were screened and reviewed by a standardized algorithm. NoVs detection rates as well as strain variations by ages, seasonal variations and geographic locations were analyzed using random-effects model. RESULTS: A total of 225 articles were included in the final analysis. Similar detection rates at 21.0% and 19.8% were obtained from the North and the South, respectively. NoVs infection occurred year round, with a peak between October and January in the North and between August and November in the South. High detection rates (∼29%) of NoVs were found in adults and the elderly and in children aged 6-35 months (∼22%). The predominant strains were GII.4 (70.4%), followed by GII.3 (13.5%). CONCLUSION: NoVs cause significant disease burden in China which warrants development of vaccines against NoVs, particularly for children and the elderly who are vulnerable to gastroenteritis diseases. To achieve a broad protection, continual monitoring NoV epidemics and strain variations for selection of proper vaccine strains is critical.

Variation analysis of norovirus among children with diarrhea in rural Hebei Province, north of China.

To understand the distribution of genotyping, as well as evolution of norovirus circulating among children<5yrs., a population-based diarrhea surveillance targeted children<5yrs. was conducted in rural Zhengding County, Hebei Province, China between October 2011 and March 2012. RT-PCR was used to amplify the capsid-encoding region of GI and GII norovirus to identify norovirus infection. All PCR products were sequenced and analyzed for genotyping and constructing phylogenetic tree. Dynamic distribution network was constructed by TempNet to illustrate the genetic relationships at two different time points. Bayesian evolutionary inference techniques were applied by BEAST software to study the norovirus evolution rate. During the 6-month surveillance period, 1091 episodes of diarrhea were reported from 5633 children under 5years of age lived in catchment area. 115 of 1091 stool specimens were detected as norovirus positive (10.54%). Five genotypes based on capsid gene sequences were identified, including GII.2 (11), GII.3 (52), GII.4 (47), GII.6 (4) and GII.7 (1). An identical haplotype of GII.4 circulated between 2006 and 2011 in Hebei Province. A mean rate of 6.29×10-2 nucleotide substitutions/site/year (s/s/y) was obtained for GII.3 viruses in Hebei, while the GII.4 viruses evolved at a mean rate of 3.67×10-2s/s/y. In conclusions, GII.3 (45.22%) and GII. 4(40.87%) are the predominant strain in Hebei Province in the winter season of 2011 and 2012. Different from the current consensus, our study shows that GII.3 noroviruses in Hebei Province evolved at a faster rate than GII.4 viruses.