ABSTRACT
Objective To provide a system for warning, preventing and controlling emerging infectious diseases from a macroscopic perspective, using the COVID-19 epidemic data and effective distance model. Methods The dates of hospitalization/isolation treatment of the first confirmed cases of COVID-19 and the cumulative numbers of confirmed cases in different provinces in China reported as of 23 February, 2020 were collected. The Location Based Service (LBS) big data platform of 'Baidu Migration' was employed to obtain the data of the proportion of the floating population from Wuhan to all parts of the country. Effective distance models and linear regression models were established to analyze the relationship between the effective distance and the arrival time of the epidemic as well as the number of cumulative confirmed cases at provincial and municipal levels. Results The arrival time of the epidemic and the cumulative number of confirmed cases of COVID-19 had significant linear relationship at both provincial and municipal levels in China, and the regression coefficients of each linear model were significant ( P <0.001). At the provincial level, the effective distance could explain about 71% of the variation of the model with arrival time along with around 90% of the variation for the model in the cumulative confirmed case magnitude; at the municipal level, the effective distance could explain about 66% of the variation for the model in arrival time, and about 85% of the variation of the model with the cumulative confirmed case magnitude. Conclusions The fitting degree of the models are good. The LBS big data and effective distance model can be used to estimate the track, time and extent of epidemic spread to provide useful reference for early warning, prevention and control of emerging infectious diseases.
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Objective To investigate the effect of Nestin gene silencing on the proliferation of human esophageal cancer ECA109 cells and possible mechanism .Methods Lenti-Nestin was constructed and transfected into ECA109 cells to establish a stable Nestin-silencing cell line Lenti-Nestin.Blank group , scrambled group , Lenti-Nestin group were set up .The expressions of Nestin , c-myc and cyclin D1 mRNA and protein levels were detected by qRT-PCR and Western blot .The cell proliferation was analyzed by CCK 8 assay .Results The stable Nestin-si-lencing cell line was successfully established .The expression of Nestin mRNA ( P<0.01 ) and protein ( P<0.05 ) levels were reduced significantly and the downregulation evidently suppressed cell proliferation ( P<0.01 ) and col-ony forming capacity ( P<0.05 ) compare with the scrambled group and blank group .However ,The c-myc and cy-clin D1 expression levels in ECA 109 cells in Lenti-Nestin group were significantly lower than that of scrambled group and blank group ( P<0.05 ) .Conclusions Knockdown Nestin expression significantly inhibits the level of esophageal cancer ECA109 cells proliferation,which may act via influencing the expression of c-myc, cyclin D1.
ABSTRACT
Background Ocular alkali burns leads to corneal ulcer and angiogenesis and even corneal opacity.There is still no ideal treatment method.Studies showed that mesenchymal stem cells (MSCs) can repair corneal wound in vivo,but the specific mechanism is still not clear.Objective This study aimed to observe the histopathological change after the early transplatation of bone marrow MSCs (BMSCs) for corneal alkali burn model in rabbits and explore the anti-inflammatory effects of MSCs after corneal alkali burn.Methods Bone marrow of 4 ml was collected from 2-3 month-old Japanese rabbit.BMSCs were isolated and cultured from the bone marrow of rabbits,and the third generation of cells were used in this study.Cultured cells were identified by morphology and the expressions of surface markers.Corneal alkali burn models were extablished in the right eyes of 24 rabbits by attaching the filter paper with 0.1％ NaOH at the central cornea for 30 seconds,and then the models were randomized into 2 groups.BMSCs suspension of 300 μl (concentration 5×l06/μl) was subconjunctivally injected 1 hour after modeling in the BMSCs group,and equal volume of PBS was used in the same way in the PBS group.Corneal opacification was scored under the slim lamp microscope in 3,14 and 28 days after injection.The polymorphonuclear neutrophils (PMNs) were counted by histopathological examination,and the expression of matrix metalloproteinase-2 (MMP-2) in the corneal tissue was evaluated by immunochemistry in various time points.The use and care of the rabbits followed the statement of ARVO.Results The rabbit BMSCs were plastic-adherent cells that exhibited a fibroblastlike shape.Cultrued cells highly expressed surface adhesion molecular markers CD29 and CD90 (99.18％ and 97.94％) and lowly expressed hematopoietic cell markers CD34 and CD31 (0.74％ and 0.15％).Opacification of cornea,defect of corneal epithelium,stromal edema and neovascularization appeared after modeling.In 14 days and 28 days after modeling,the opacification scores in the BMSCs group were 2.37±0.52 and 2.25±0.50,which were significantly lower than 3.00±0.53 and 3.25 ±0.50 in the PBS group (t =2.376,2.828,both at P＜0.05).After subconjunctival injection,the number of PMNs was (34.17 ±1.85) /12 fields and (25.64 ±3.86)/12 fields in the BMSCs group,showing significant decrease in comparison with (42.70 ±1.54) /12 fields and (32.67 ±1.42)/12 fields in the PBS group (t=10.021,4.832,both at P=0.000).The expression levels of MMP-2 (A value) in cornea were 0.388±0.016 and 0.384±0.006 in the BMSCs group,with considerable decreases in comparison with 0.438± 0.006 and 0.412± 0.005 in the PBS group (t=10.205,13.514,both at P=0.000).Conclusions Early transplantation of BMSCs can arrest the occurrance of corneal ulcer by suppressing the infiltration of PMNs,alleviateing the inflammation reaction,downregulating the expression of MMP-2 in cornea and inhibiting the degradation of stromal collagen fibers.