Staging liver fibrosis with various diffusion-weighted magnetic resonance imaging models

BACKGROUND Diffusion-weighted imaging(DWI)has been developed to stage liver fibrosis.However,its diagnostic performance is inconsistent among studies.Therefore,it is worth studying the diagnostic value of various diffusion models for liver fibrosis in one cohort.AIM To evaluate the clinical potential of six diffusion-weighted models in liver fibrosis staging and compare their diagnostic performances.METHODS This prospective study enrolled 59 patients suspected of liver disease and scheduled for liver biopsy and 17 healthy participants.All participants underwent multi-b value DWI.The main DWI-derived parameters included Mono-apparent diffusion coefficient(ADC)from mono-exponential DWI,intravoxel incoherent motion model-derived true diffusion coefficient(IVIM-D),diffusion kurtosis imaging-derived apparent diffusivity(DKI-MD),stretched exponential model-derived distributed diffusion coefficient(SEM-DDC),fractional order calculus(FROC)model-derived diffusion coefficient(FROC-D)and FROC model-derived microstructural quantity(FROC-μ),and continuous-time random-walk(CTRW)model-derived anomalous diffusion coefficient(CTRW-D)and CTRW model-derived temporal diffusion heterogeneity index(CTRW-α).The correlations between DWI-derived parameters and fibrosis stages and the parameters’diagnostic efficacy in detecting significant fibrosis(SF)were assessed and compared.RESULTS CTRW-D(r=-0.356),CTRW-α(r=-0.297),DKI-MD(r=-0.297),FROC-D(r=-0.350),FROC-μ(r=-0.321),IVIM-D(r=-0.251),Mono-ADC(r=-0.362),and SEM-DDC(r=-0.263)were significantly correlated with fibrosis stages.The areas under the ROC curves(AUCs)of the combined index of the six models for distinguishing SF(0.697-0.747)were higher than each of the parameters alone(0.524-0.719).The DWI models’ability to detect SF was similar.The combined index of CTRW model parameters had the highest AUC(0.747).CONCLUSION The DWI models were similarly valuable in distinguishing SF in patients with liver disease.The combined index of CTRW parameters had the highest AUC.

Fabrication, microstructure, friction and wear properties of SiC3D/Al brake disc-graphite/Si C pad tribo-couple for high-speed train

The friction and wear properties of interpenetrating phase composites(IPC) SiC3D/Al sliding against graphite/SiC(G/SiC) composites were investigated using a sub-scale brake dynamometer. The testing conditions included a braking pressure of 1.25 MPa and an initial braking speed(IBS) of 200-350 km/h in a braking process of high-speed train according to the scale-conversion rules. The tribo-couple materials were characterized using scanning electron microscopy(SEM), X-ray diffractometry(XRD), and energy-dispersive X-ray spectrometry(EDS). It is found that the matching tribo-couple features low friction surface temperature, reliable friction factor, and high durability. The continuous lubricating mechanically-mixed layer(MML) forms gradually on the worn surfaces of ring in the friction process. The MML is heterogeneous, which greatly controls wear rate and coefficient of friction(COF) of the composites. The wear mechanism of SiC3D/Al is typically abrasive wear at an IBS of 200-300 km/h. When the IBS increases to 350 km/h, oxidation wear and delamination are observed. The friction behavior of the tribo-couple predicted using Solidwork simulation software agrees well with the experimental results. The tribo-couple meets the requirement of emergency braking of high-speed train.

miR-124 is upregulated in diabetic mice and inhibits proliferation and promotes apoptosis of high-glucose-inducedβ-cells by targeting EZH2

BACKGROUND Diabetes is a chronic metabolic disease,and a variety of miRNA are involved in the occurrence and development of diabetes.In clinical studies,miR-124 is highly expressed in the serum of patients with diabetes and in pancreatic isletβ-cells.However,few reports exist concerning the role and mechanism of action of miR-124 in diabetes.AIM To investigate the expression of miR-124 in diabetic mice and the potential mechanism of action in isletβ-cells.METHODS The expression levels of miR-124 and enhancer of zeste homolog 2(EZH2)in pancreatic tissues of diabetic mice were detected.The targeted relationship between miR-124 and EZH2 was predicted by Targetscan software and verified by a double luciferase reporter assay.Mouse isletβ-cells Min6 were grown in a high glucose(HG)medium to mimic a diabetes model.The insulin secretion,proliferation,cell cycle and apoptosis of HG-induced Min6 cells were detected after interference of miR-124a and/or EZH2.RESULTS The expression of miR-124 was upregulated and EZH2 was downregulated in the pancreatic tissue of diabetic mice compared with control mice,and the expression of miR-124 was negatively correlated with that of EZH2.miR-124 was highly expressed in HG-induced Min6 cells.Inhibition of miR-124 promoted insulin secretion and cell proliferation,induced the transition from the G0/G1 phase to the S phase of the cell cycle,and inhibited cell apoptosis in HG-induced Min6 cells.EZH2 was one of the targets of miR-124.Co-transfection of miR-124 inhibitor and siRNA-EZH2 could reverse the effects of the miR-124 inhibitor in HG-induced Min6 cells.CONCLUSION miR-124 is highly expressed in diabetic mice and HG-induced Min6 cells and regulates insulin secretion,proliferation and apoptosis of isletβ-cells by targeting EZH2.