Exploring the interconnectivity of biomimetic hierarchical porous Mg scaffolds for bone tissue engineering:Effects of pore size distribution on mechanical properties,degradation behavior and cell migration ability

Interconnectivity is the key characteristic of bone tissue engineering scaffold modulating cell migration,blood vessels invasion and transport of nutrient and waste.However,efforts and understanding of the interconnectivity of porous Mg is limited due to the diverse architectures of pore struts and pore size distribution of Mg scaffold systems.In this work,biomimetic hierarchical porous Mg scaffolds with tailored interconnectivity as well as pore size distribution were prepared by template replication of infiltration casting.Mg scaffold with better interconnectivity showed lower mechanical strength.Enlarging interconnected pores would enhance the interconnectivity of the whole scaffold and reduce the change of ion concentration,pH value and osmolality of the degradation microenvironment due to the lower specific surface area.Nevertheless,the degradation rates of five tested Mg scaffolds were no different because of the same geometry of strut unit.Direct cell culture and evaluation of cell density at both sides of four typical Mg scaffolds indicated that cell migration through hierarchical porous Mg scaffolds could be enhanced by not only bigger interconnected pore size but also larger main pore size.In summary,design of interconnectivity in terms of pore size distribution could regulate mechanical strength,microenvironment in cell culture condition and cell migration potential,and beyond that it shows great potential for personalized therapy which could facilitate the regeneration process.

Ultrasonic Characteristics and Severity Assessment of Lung Ultrasound in COVID-19 Pneumonia:A Retrospective,Observational Study

The clinical application of lung ultrasound(LS)in the assessment of coronavirus disease 2019(COVID-19)pneumonia severity remains limited,Herein,we investigated the role of LUS imaging in CoVID-19pneumonia patients and the relationship between LUS findings and disease severity.This was a retro-spective,observational study at Tongji Hospital,on 48 recruited patients with COVID-19 pneu-monia,including 32 non-critically ill patients and 16critically ill patients.LUS was performed and the respiratory rate oxygenation(ROX)index,disease severity,and confusion,blood urea nitrogen,respira-tory rate,blood pressure,and age(CURB-65)score were recorded on days 0-7,8-14,and 15-21 after symptomonset.Lung images were divided into 12 regions,and the luS score(0-36 points)was calcu-lated.hestcomputed tomography(CT)scores(0-20 points)were also recorded on days O-7.Coelations between the LUS score,ROX index,and CURB-65 scores were examined.LUS detected COVID-19 pneumonia in 38patients.LUS signs included B lines(34/38,89.5%),consolidations(6/38,15.8%),and pleural effusions(2/38,5.3%).Most cases showed more than one lesion(32/38,84.2%)and involved both lungs(28/38,73.7%).Compared with non-critically ill patients,the LUS scores of critically ill patients were higher(12(10-18)vs 2(0-5),p<0.001).The LUS score showed significant negative cor-relations with the ROX indexon days O-7(r=-0.85,p<0.001),days 8-14(r=-0.71,p<0.001),and days 15-21(r=-0.76,p<0.001)after symptom onset.However,the LUS score was positively correlated with the CT score(r=0.82,p<0.001).The number of patients with LUS-detected lesions decreased from 27 cases(81.8%)to 20 cases(46.5%),and the lus scores significantly decreased from 4(2-10)to 0(0-5),(p<0.001) from days O-7 to 17-21.We conclude that LUS can detect lunglesions in COVID-19 pneumo-nia patients in a portable,real-time,and safe manner.Thus,LUS is helpful in assessing COVID-19 pneu-monia severity in critically ill patients.

A four-compartment model for the COVID-19 infection—implications on infection kinetics,control measures,and lockdown exit strategies

Objective:To analyse the impact and repercussions of the surge in healthcare demand in response to the COVID-19 pandemic,assess the potential effectiveness of various infection/disease control measures,and make projections on the best approach to exit from the current lockdown.Design:A four-compartment model was constructed for SARS-CoV-2 infection based on the Wuhan data and validated with data collected in Italy,the UK,and the US.The model captures the effectiveness of various disease suppression measures in three modifiable factors:(a)the per capita contact rate(β)that can be lowered by means of social distancing,(b)infection probability upon contacting infectious individuals that can be lowered by wearing facemasks,personal hygiene,etc.,and(c)the population of infectious individuals in contact with the susceptible population,which can be lowered by quarantine.The model was used to make projections on the best approach to exit from the current lockdown.Results:The model was applied to evaluate the epidemiological data and hospital burden in Italy,the UK,and the US.The control measures were identified as the key drivers for the observed epidemiological data through sensitivity analyses.Analysing the different lockdown exit strategies showed that a lockdown exit strategy with a combination of social separation/general facemask use may work,but this needs to be supported by intense monitoring whichwould allowre-introduction/tightening of the controlmeasures if the number of newinfected subjects increases again.Conclusions and relevance:Governments should act early in a swift and decisive manner for containment policies.Any lockdown exit will need to be monitored closely,with regards to the potential of lockdown reimplementation.This mathematical model provides a framework for major pandemics in the future.

Evaluation of the efficacy and safety of hydroxychloroquine in comparison with chloroquine in moderate and severe patients with COVID-19

Dear Editor,Since December 2019,severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has been rapidly spreading worldwide.Hydroxychloroquine and chloroquine are candidates for the treatment of coronavirus disease 2019(COVID-19)owing to its antiviral effect and immunomodulation properties.