Comparative analysis of different feeder layers with 3T3 fibroblasts for culturing rabbits limbal stem cells

AIM： To explore the possibility of human umbilical cord mesenchymal stem cells（h UCMSCs）, human umbilical vein endothelial cells（h UVECs）, human dental pulp stem cells（h DPSCs） and human periodontal ligament stem cells（h PDLSCs） serving as feeder cells in co-culture systems for the cultivation of limbal stem cells.METHODS： Different feeder layers were cultured in Dulbecco＇s modified Eagle＇s medium（DMEM）/F12 and were treated with mitomycin C. Rabbits limbal stem cells（LSCs） were co-cultured on h UCMSCs, h UVECs, h DPSCs, h PDLSCs and NIH-3T3, and then comparative analysis were made between each group to see their respective colony-forming efficiency（CFE） assay and immunofluorescence（IPO13,CK3/12）.RESULTS： The efficiency of the four type cells in supporting the LSCs morphology and its cellular differentiation was similar to that of NIH-3T3 fibroblasts as demonstrated by the immunostaining properties analysis, with each group exhibiting a similar strong expression pattern of IPO13, but lacking CK3 and CK12 expression in terms of immunostaining. But h UCMSCs, h DPSCs and h PDLSCs feeder layers were superior in promoting colony formation potential of cells when compared to h UVECs and feedercell-free culture.CONCLUSION： hUCMSCs, hDPSCs and hPDLSCs can be a suitable alternative to conventional mouse NIH-3T3 feeder cells, so that risk of zoonotic infection can be diminished.

Design and realization of lung organoid cultures for COVID-19 applications

Coronavirus disease 2019(COVID-19),caused by severe acute respiratory syndrome coronavirus 2,has spread globally and threatens public health.Advanced in vitro models that recapitulate the architecture and functioning of specific tissues and organs are in high demand for COVID-19-related pathology studies and drug screening.Since three-dimensional in vitro cultures,such as self-assembled and engineered organoid cultures,surpass conventional two-dimensional cultures and animal models with respect to increased cellular complexity,an environment more relevant to humans,and reduced cost,they are promising platforms for understanding viral pathogenesis and developing new therapeutics.This review highlights the recent advances in self-assembled and engineered organoid technologies that are used for COVID-19 studies.The challenges and future perspectives are also discussed.

选区激光熔化TC4球化飞溅机理及其试验研究

目的提升单熔道、单层面的成形质量和打印精度,通过对球化、飞溅缺陷机理的研究及试验探索,寻找减少其产生的最优工艺路径。方法采用不同激光功率、点间距、线间距的打印策略成形单熔道,通过单熔道的成形质量,初步选取表面质量较好的成形工艺参数范围,进行单层面的成形试验。在单熔道、单层面成形试验中,进行球化、飞溅缺陷产生的研究和分析,探讨其产生机理及对表面质量的影响,并进一步进行单层面试验研究,找到合理的工艺参数取值范围,以此提升单层面表面质量。结果球化、飞溅缺陷对于单熔道、单层面的成形质量及精度都有较大影响。能量密度是影响缺陷产生的主要原因,适当的能量密度可以提升表面质量,线能量密度在0.4~0.6 J/mm、面能量密度在4~6 J/mm^(2)时,所成形的样件表面较为平整,球化、飞溅缺陷明显减少,成形质量好,精度较高。结论当能量密度合适时,球化、飞溅缺陷明显减少,单熔道、单层面的成形效果好,流动均匀且连续。球化、飞溅缺陷有一定的规律性,可以通过最优工艺参数进行避免。

TiN和TiAlN涂层刀具铣削铝锂合金表面质量试验对比研究

目的比较TiN和TiAlN涂层刀具加工铝锂合金的切削性能和表面质量。方法使用硬质合金、TiN涂层和TiAlN涂层三种刀具,对2198-T8型铝锂合金进行干式铣削试验。改变切削因素的水平,比较刀具磨损、铝锂合金的表面粗糙度、切削力和切屑形态。结果铣削铝锂合金时,刀具主要磨损为粘附磨损,TiN涂层的粘附程度最低,硬质合金次之,TiAlN涂层表面粘附最严重,切削效能最低。粘附磨损严重影响铣削成形的表面粗糙度,并使铣削力增加。铣削速度是影响工件表面粗糙度的主要因素,通过提高铣削速度可明显降低材料的粘结程度,降低表面粗糙度与铣削力,TiN涂层在铣削铝锂合金时最小表面粗糙度可达到0.5μm以下。在相同的切削参数下,TiN涂层断屑均匀,切屑表面较为光滑,切屑塑性变形最小。硬质合金刀具产生的切屑尺寸较短,切屑表面有少量带状条纹,TiAlN涂层刀具产生的切屑发生了严重的塑性变形。结论与TiAlN涂层和硬质合金刀具相比,TiN涂层刀具在铣削铝锂合金时的切削效能最好,可以达到最好的表面粗糙度和加工效果。

基质细胞衍生因子-1及其受体CXCR4在翼状胬肉中的表达及意义

目的:探讨基质细胞衍生因子-1(SDF-1)及其受体趋化因子受体(CXCR4)在不同年龄翼状胬肉患者中的表达及意义。方法:收集2018-01/10在中国人民解放军第四七四医院行原发性翼状胬肉切除术的手术标本60例60眼(其中年龄<50岁30眼,年龄>50岁30眼),同时间收集年龄匹配的斜视矫正术和视网膜脱离复位术患者的正常结膜组织30例30眼(其中年龄<50岁15眼,年龄>50岁15眼)。采用HE染色和免疫组织化学法检测SDF-1和CXCR4在翼状胬肉组织标本中的表达和定位,分析SDF-1和CXCR4的表达与患者临床表现的关系。使用IPP 6.0软件定量测定SDF-1和CXCR4的平均光密度。结果:SDF-1和CXCR4在正常结膜上皮基底层细胞显示阳性或无阳性表达,而在翼状胬肉中全层结膜上皮细胞和血管内皮细胞均有阳性表达,其表达水平差异显著,基底层细胞中表达更明显,显示出明显极性。翼状胬肉组织中SDF-1和CXCR4的表达量均高于正常结膜组织(P<0.05);年龄<50岁患者的CXCR4表达量大于年龄>50岁患者的表达量(P<0.05)。结论:SDF-1和CXCR4在翼状胬肉中表达上调,提示SDF-1和CXCR4参与翼状胬肉的形成,抑制SDF-1/CXCR4信号通路,可能抑制翼状胬肉发生,也可能成为翼状胬肉的药物治疗靶点,成为一个新的研究方向。年轻翼状胬肉患者CXCR4的表达更高,提示未来可能实现个体化给药,减少医疗资源的浪费。

Posterior chamber phakic intraocular lens implantation for high myopia

AIM:To evaluate the efficacy,safety and stability of posterior chamber phakic intraocular lens implantation for the correction of high myopia.METHODS:Retrospective case review of 82 eyes(43patients)undergoing implantable Coliamer lens(ICL)placement by a single surgeon(Xiao-Wei Gao)to correct preoperative mean spherical equivalents between-9.00diopter(D)and-23.00D.Main outcome measures included uncorrected visual acuity(UCVA),refraction,best spectacle-corrected visual acuity(BSCVA),endothelial cell density(ECD),intraocular pressure(IOP),lens transparency,postoperative uveitis.Visante anterior segment optical coherence tomography(AS-OCT)was used to measure anterior chamber depth(ACD)and the position of ICL.RESULTS:Mean follow-up was 6.54±3.26 months(range 3-12 months).Predictability of the manifest spherical equivalent(SE)refraction to within±1.OOD was achieved in 88%of eyes and±0.50D in 72.5%of eyes.The mean postoperative manifest SE refraction was-1.85±0.72D,with 96.34%of eyes maintaining or gaining≥1 line(s)of BSCVA.The mean 3-month postoperative ECD decreased but had no statistically difference compared with the preoperative ECD.Of the 7 eyes(8.54%)with a mild transient increase in intraocular pressure(up to 30mmHg),none required a second surgical procedure or prolonged topical medication.There was no loss of lens transparency.Pigmented precipitates were observed in 5 eyes(6.09%).The mean preoperative ACD measured with AS-OCT was 3.28±0.14mm,three months after surgery,the mean ACD was2.45±0.22mm.Anterior chamber depth showed astatistically significant reduction.One eye(1.22%)had ICL spontaneous rotation,81 eyes(98.78%)of the lens remained correctly centered.CONCLUSION:The implantation of ICL is an effective surgical option for the management of high myopia.But its long time effect and safety still need more time to prove.

Inhibition of retinopathy of prematurity in rat by intravitreal injection of sorafenib

AIM:To investigate the effect of intravitreal injection administered sorafenib,a multikinase inhibitor,in a rat model of oxygen-induced retinopathy(OIR).METHODS:Seven-day-old Sprague-Dawley rats(n=144)were randomly assigned to six groups.Group A received normal partial oxygen pressure and groups B,C,D,E and F were exposed to hyperoxia(75±2)%from postnatal 7d(P7)to P12 to induce retinopathy of prematurity.The rats in groups C,D,E and F were received intravitreal injections of either vehicle(DMSO)or sorafenib at P12(5,20 and 80μg,respectively).Then they returned to normoxia after P12.The retinas were whole-mounted and imaged with a confocal microscopy.The vascular branching points were counted to quantify neovascularization at P17.Cross-sections of the retina were stained with hematoxylin and eosin(HE).The nuclei of new vessels breaking the internal limiting membrane were counted to quantify the proliferative neovascular response.RESULTS:The retinal vessel in groups B and C turned into tortuosity and a great deal of neovascularization were observed.Sorafenib-treated rats had significantly less neovascularization as compared with vehicle-treated and control rats in a dose dependent manner(P【0.05).The number of vascular branching points in A,B,C,D,E and F were 16.50±3.90,37.44±6.47,37.08±5.10,30.80±6.85,26.08±5.08 and 19.83±3.51,respectively.The number of the nuclei of retinal new vessel in A,B,C,D,E and F were 0.22±0.42,35.66±4.70,35.30±4.54,27.30±4.28,21.41±3.53,and 7.41±2.87,respectively.There were significant difference between each group(P【0.05)except groups B and C.CONCLUSION:In the rat OIR model,sorafenib could inhibit retinal neovascularization in a dose dependent manner.

Effects of aminoguanidine on retinal apoptosis in mice with oxygen-induced retinopathy

AIM:To explore the protective effects of amino-guanidine(AG) on retinal apoptosis in mice with oxygeninduced retinopathy(OIR).·METHODS:A total of 80 C57BL/6J mice,aged 7 days,were randomly divided into four groups:normal,high oxygen,high oxygen saline and high oxygen treated with AG.In the normal group,mice were housed in normoxic conditions from postnatal day P7 to P17.Mice in the other 3 groups were placed under hyperoxic conditions(75 ±2% O2) in an oxygen-regulated chamber for 5 days and subsequently placed in normoxic conditions for 5days.Mice in the AG group were treated once daily,from P12 to P17,with AG hemisulfate(100mg/kg body weight,intraperitoneally) dissolved in physiological saline.An equivalent amount of 0.9% physiological saline was administered,as above,to mice in the high oxygen saline group.Ten mice were randomly selected from each group on P14 and on P17,euthanized and the retinas examined.Apoptotic cells in the retina were detected using the terminal-deoxynucleoitidyl transferase mediated nick end labeling(TUNEL) method.The expression of nitric oxide synthase(iNOS) in the retina was detected by immunohistochemistry and changes in rod cells were observed using electron microscopy.·RESULTS:TUNEL-positive cells and iNOS immunoreactive neurons were present in the inner nuclear and ganglion cell retinal layers of mice in the high oxygen group.The number of TUNEL-positive cells was significantly greater in the high oxygen group compared with the normal group(t =-20.81,P14d【0.05;t =-15.05,P17d【0.05).However,the number of TUNEL-positive cells in the AG treatment group was significantly lower(t =-13.21,P14d【0.05;t =-6.61,P17d【0.05) compared with thehigh oxygen group.The expression of iNOS was significantly higher in the high oxygen group compared with the normal group(t =-21.95,P14d【0.05;t =-17.30,P17d【0.05).However,the expression of iNOS in the AG treatment group was significantly lower(t =-12.17,P14d【0.05;t =-10.30,P17d【0.05) compared with the high oxygen group.The outer segments of the rods were disorganized and short in the high oxygen group.Rod morphology appeared to be slightly improved in the AG group.·CONCLUSION:AG may protect retinal neurons in OIR by inhibiting apoptosis.The mechanism may be related to iNOS.

Comparative study of modified and conventional secondary hydroxyapatite orbital implantations

AIMTo compare the clinical effects of the modified and conventional secondary hydroxyapatite orbital implantations.

Validation of American Joint Committee on Cancer 8th edition of TNM staging in resected distal pancreatic cancer

BACKGROUND In order to improve risk stratification and clinical management of the pancreatic ductal adenocarcinoma(PDAC),the American Joint Committee on Cancer(AJCC)has published its eighth edition staging manual.Some major changes have been introduced in the new staging system for both T and N categories.Given the rarity of resectable disease,distal pancreatic cancer is likely underrepresented in the published clinical studies,and how the impact of the staging system actually reflects on to clinical outcomes remain unclear.AIM To validate the AJCC 8th edition of TNM staging in distal PDAC.METHODS A retrospective cohort study was performed in seven academic medical centers in the United States.Clinicopathological prognostic factors associated with progression-free survival(PFS)and overall survival(OS)were evaluated through univariate and multivariate analyses.RESULTS Overall,454 patients were enrolled in the study,and were divided into 2 subgroups:Invasive intraductal papillary mucinous neoplasms(IPMN)(115 cases)and non-IPMN associated adenocarcinoma(339 cases).Compared to invasive IPMN,non-IPMN associated adenocarcinomas are more common in relatively younger patients,have larger tumor size,are more likely to have positive lymph nodes,and are associated with a higher tumor(T)stage and nodal(N)stage,lymphovascular invasion,perineural invasion,tumor recurrence,and a worse PFS and OS.The cohort was predominantly categorized as stage 3 per AJCC 7th edition staging manual,and it’s more evenly distributed based on 8th edition staging manual.T and N staging of both 7th and 8th edition sufficiently stratify PFS and OS in the entire cohort,although dividing into N1 and N2 according to the 8th edition does not show additional stratification.For PDAC arising in IPMN,T staging of the 7th edition and N1/N2 staging of the 8th edition appear to further stratify PFS and OS.For PDAC without an IPMN component,T staging from both versions fails to stratify PFS and OS.CONCLUSION The AJCC 8th edition TNM staging system provides even distribution for the T staging,however,it does not provide better risk stratification than previous staging system for distal pancreatic cancer.

Clinical Significance of Preoperative Nutritional Risk Screening and Support in the Perioperative Period of Gastric Cancer Patients

Objective:To investigate the clinical value of using preoperative nutritional risk screening and support in gastric cancer patients.Methods:In this paper,70 gastric cancer patients selected from July 2017 to July 2020 treated in our hospital were grouped concerning the lottery method,and the reference group(n=35)used conventional nutritional support,while the experimental group(n=35)used preoperative dietary risk screening and support,comparing the clinical treatment differences between gastric cancer patients in the experimental group and the reference group.Results:After the intervention,IgA,IgM,IgG,serum albumin,complication rate,NRS score,hospitalization time and anal exhaust time of gastric cancer patients in the experimental group were compared with those in the reference group,P<0.05,and there was statistical validation analysis significance between the data indicators.P<0.05 for the comparison of IgA,IgM,IgG,serum albumin after the intervention and pre-intervention for gastric cancer patients in the experimental group and the reference group,with statistical validation analysis significance between the data indicators.Conclusion:Preoperative nutritional risk screening and support is of significant value in gastric cancer patients and can improve patients’nutritional status.

锂硫电池中的石墨烯掺杂

锂硫电池是以锂为负极,单质硫为正极的二次电池,具有高达1675 mA·h/g的比容量及2600 W·h/kg的比能量密度。理论上讲,相较于现有的锂离子电池,锂硫电池可使容量扩展5倍,这使其成为最有前景的锂离子电池。由于硫正极的绝缘性以及充放电过程中活性物质易溶于电解液,导致其可实现的能量密度远低于理论值。异原子掺杂石墨烯因具有优异的导电性,且对多硫化锂(LiPS)具有强的吸附作用而被广泛应用于锂硫电池,有效缓解了"穿梭效应",提高了电池的循环稳定性。本文主要从单原子掺杂、双原子掺杂两方面综述了异原子(如N,P,S,B)掺杂石墨烯在锂硫电池领域的研究现状,详细分析了其应用于锂硫电池的作用机理,并从掺杂量、掺杂形式、掺杂位置等方面对电池性能的提升进行了梳理和展望。

规则波在岛礁地形上传播的SPH模拟

结合周期性边界条件、水流循环技术以及动量源造波方法,本文建立了一个基于光滑粒子流体动力学(smoothed particle hydrodynamic,SPH)方法的二维无反射数值波浪水槽,模拟了波浪在深海台礁上的传播变形过程,分析了该地形上波高和增水的沿程变化,并与物理模型试验结果进行了对比.结果表明,该数值模型可以较准确地模拟深海台礁上的波浪破碎和增水过程以及礁坪上波高和波浪增水的空间分布特征;在水槽左右两侧采用周期性边界条件和预留水流循环通道,能够有效解决竖向二维数值模型中由于礁坪上波生流引起的潟湖内水面的非物理性雍高及进而导致的礁坪上增水偏大的问题.

CFD-DEM simulation of spouting of corn-shaped particles

Three dimensionally coupled computational fluid dynamics （CFD） and discrete element method （DEM） were used to investigate the flow of corn-shaped particles in a cylindrical spouted bed with a conical base. The particle motion was modeled by the DEM, and the gas motion by the k-ε two-equation turbulent model. A two-way coupling numerical iterative scheme was used to incorporate the effects of gas-particle interactions in terms of momentum exchange. The corn-shaped particles were constructed by a multisphere method. Drag force, contact force, Saffman lift force, Magnus lift force, and gravitational force acting on each individual particle were considered in establishing the mathematical modeling. Calculations were carried out in a cylindrical spouted bed with an inside diameter of 200 mm, a height of 700 mm, and a conical base of 60°. Comparison of simulations with experiments showed the availability of the multi-sphere method in simulating spouting action with corn-shaped particles, but it depended strongly on the number and the arrangement of the spherical elements. Gas-solid flow patterns, pressure drop, particle velocity and particle concentration at various spouting gas velocity were discussed. The results showed that particle velocity reaches a maximum at the axis and then decreases gradually along the radial direction in the whole bed. Particle concentration increases along the radial direction in the spout region but decreases in the fountain region, while it is nearly constant in the annulus region. Increasing spouting gas velocity leads to larger pressure drop, remarkably increased speed of particle moving upward or downward, but decreased particle concentration.

Experimental investigation of regular wave propagation over an idealized reef model

The wave transformation over the deep-sea coral reefs is an essential issue in the analysis of the reef ecosystem and the design of large reef-top structures.Extensive wave flume experiments are conducted to investigate the wave transformation processes over an idealized reef model.Detailed measurements of the wave height,the wave set-up and the wave-generated flow on the reef-top are made with and without the reef-top structure at various submerged depths and under different wave conditions.It is found that the reef-top structure has a significant influence on the wave breaking,the wave set-up and the wave-generated flow.The wave set-up increases with the increasing wave height and the decreasing submergence depth.However,the relationship between the wave set-up and the wave period is complex,influenced by the reef-top structure.

脾血管浸润是胰体尾癌切除术后的不良预后因素

背景:由于较高的远处转移率,胰体尾癌是致死率最高的肿瘤之一。本研究旨在评估脾血管浸润对于胰体尾癌切除术患者的预后价值。方法:在这项回顾性研究中,我们收集了454例胰体尾癌患者的临床病理资料,通过单因素和多因素分析明确本组患者无进展生存(PFS)和总体生存(OS)的预后影响因素,重点关注脾动/静脉浸润的预后价值。结果:单因素分析结果显示,肿瘤较大、非导管内乳头状黏液瘤(non-IPMN)相关的腺癌、低分化、pT3期、淋巴结转移、脉管浸润、神经浸润、病理学脾静脉浸润、影像学脾静脉浸润者PFS和OS均显著缩短(均P<0.05)。多因素分析证实,non-IPMN相关腺瘤、pT3期、pN1-2期及术后辅助化疗是PFS和OS的独立危险因素;此外,肿瘤较大和影像学脾静脉浸润同时也是PFS的独立预后因素。结论:应当就如何检测和报告胰体尾癌手术标本的脾血管状态,形成一个统一的规范。