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OBJECTIVE@#We propose a novel region- level self-supervised contrastive learning method USRegCon (ultrastructural region contrast) based on the semantic similarity of ultrastructures to improve the performance of the model for glomerular ultrastructure segmentation on electron microscope images.@*METHODS@#USRegCon used a large amount of unlabeled data for pre- training of the model in 3 steps: (1) The model encoded and decoded the ultrastructural information in the image and adaptively divided the image into multiple regions based on the semantic similarity of the ultrastructures; (2) Based on the divided regions, the first-order grayscale region representations and deep semantic region representations of each region were extracted by region pooling operation; (3) For the first-order grayscale region representations, a grayscale loss function was proposed to minimize the grayscale difference within regions and maximize the difference between regions. For deep semantic region representations, a semantic loss function was introduced to maximize the similarity of positive region pairs and the difference of negative region pairs in the representation space. These two loss functions were jointly used for pre-training of the model.@*RESULTS@#In the segmentation task for 3 ultrastructures of the glomerular filtration barrier based on the private dataset GlomEM, USRegCon achieved promising segmentation results for basement membrane, endothelial cells, and podocytes, with Dice coefficients of (85.69 ± 0.13)%, (74.59 ± 0.13)%, and (78.57 ± 0.16)%, respectively, demonstrating a good performance of the model superior to many existing image-level, pixel-level, and region-level self-supervised contrastive learning methods and close to the fully- supervised pre-training method based on the large- scale labeled dataset ImageNet.@*CONCLUSION@#USRegCon facilitates the model to learn beneficial region representations from large amounts of unlabeled data to overcome the scarcity of labeled data and improves the deep model performance for glomerular ultrastructure recognition and boundary segmentation.
Subject(s)
Humans , Electrons , Endothelial Cells , Learning , Podocytes , Kidney DiseasesABSTRACT
Objective To investigate the potential of polylactic acid glycolic acid copolymer (PLGA) composite ordered multi tunnel collagen scaffold in fabricating a biomimetic artificial nerve graft to repair the sciatic nerve defects in rats.Methods The ordered multi tunnel collagen scaffold was prepared by vacuum freeze-drying and directional drawing method to simulate the epineurium;the outer conduit was prepared by PLGA to simulate the epineurium;and then,the ordered multi tunnel collagen scaffolds were loaded in the PLGA conduit (5∶1) under a stereomicroscope to develop a novel biomimetic artificial nerve.Sixty-four rats were randomly divided into four groups:artificial nerve group,PLGA group,peripheral nerve group,and non-graft control group (n=16);rats in the artificial nerve group,PLGA group,and peripheral nerve group were repaired with artificial nerve graft,hollow PLGA conduit and allogeneic sciatic nerve to bridge the sciatic nerve defect,while the sciatic nerve with the gap in rats of the control group was without any grafting.After 11 weeks of operation,the hind limbs of rats in each group were detected by behavioral test,electrophysiological examination and Fluoro-Gold retrograde tracing method.The changes of muscle tissues (gastrocnemius) were observed by hematoxylin staining and TMR-α-BTX staining,and the regenerated axons were observed by immunohistochemical staining with NF200 and the regenerative spinal anterior horn motor neurons were observed by Nissl fluorescence staining 12 weeks after operation.Results After 11 weeks of operation,the recoveries of the motor functions (the distance between the injured hindlimb and forelimb,the rotation angle of the injured foot) in the peripheral nerve group,artificial nerve group,PLGA group and control group were significantly deteriorated in turn,and the differences were statistically significant (P＜0.05).Electrophysiological examination showed that the recovery effect of peripheral nerve group was the best in both latency and amplitude of the compound muscle action potential,followed by artificial nerve group.The latency of PLGA group was the longest and the amplitude of compound action potential was the smallest;significant differences were noted between each two groups (P2＜0.05).At 12 weeks after operation,the wet weight ratio of muscle fibers,area of muscle fibers and neuromuscular junction area were significantly different between each two groups (P＜0.05);the degree of gastrocnemius atrophy in the artificial nerve group was significantly improved than that in the PLGA group,but not yet reached the level of peripheral nerve group.NF200 immunohistochemical staining showed that a large number of NF200-positive axons were seen in the grafts of the artificial nerve group,but the number was slightly smaller than that of the peripheral nerve group;the number of regenerated axons in the PLGA group was the smaller and mainly distributed near the proximal side.In the PLGA group,only (19.33 ±6.73)％ regenerated spinal anterior horn motor neurons were labeled with Fluoro-Gold,while the positive rates of Fluoro-Gold in the artificial nerve group and peripheral nerve group were (42.67±7.45)％ and (50.13±4.33)％;the differences between each two groups were statistically significant (P＜0.05).Conclusion The biomimetic artificial nerve made of PLGA conduit and ordered multi tunnel collagen scaffold can efficiently reconstruct the defected peripheral nerve with guiding axonal regeneration and promoting functional restoration in rats;however,its effect is poor than peripheral nerve grafting.
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We proposed a new stitching method based on sift features to obtain an enlarged view of transmission electron microscopic (TEM) images with a high resolution. The sift features were extracted from the images, which were then combined with fitted polynomial correction field to correct the images, followed by image alignment based on the sift features. The image seams at the junction were finally removed by Poisson image editing to achieve seamless stitching, which was validated on 60 local glomerular TEM images with an image alignment error of 62.5 to 187.5 nm. Compared with 3 other stitching methods, the proposed method could effectively reduce image deformation and avoid artifacts to facilitate renal biopsy pathological diagnosis.
Subject(s)
Humans , Algorithms , Artifacts , Image Processing, Computer-Assisted , Methods , Kidney Glomerulus , Microscopy, Electron, Transmission , MethodsABSTRACT
Objective To observe the effect of Sanqi Oral Liquid on the podocytes and the expression of slit diaphragm-associated molecules (including Nephrin, Podocin and CD2AP proteins) of diabetes mellitus (DM) rats after unilateral nephrectomy, so as to explore its mechanism for protecting renal function. Methods SD male rats were randomized into sham operation group, model group and Chinese medicine group. The experimental diabetes mellitus ( DM) model was given unilateral nephrectomy and intraperitoneal injection of 35 mg/kg of streptozocin (STZ). And then the model rats were given intragastric administration of Sanqi Oral Liquid (2.5 g· kg-1·d-1) and the same volume distilled water respectively for 8 weeks. After treatment, the density of podocytes and the podocytic foot process width of different groups were measured. Immunohistochemistry was used to observe the changes of the expression of Nephrin, Podocin and CD2AP in renal tissues of different groups. Results After treatment with Sanqi Oral Liquid, the density of podocytes was increased, the foot process lesion was relieved, and the expression levels of Nephrin, Podocin and CD2AP proteins were increased (P<0.05 or P<0.01 as compared with those in the model group). Conclusion The protective mechanism of Sanqi Oral Liquid for renal function of unilateral nephrectomy DM rats is possibly related with the alleviation of podocyte injury and with the regulation of the expression of Nephrin, Podocin and CD2AP proteins in podocytes.
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The expression of microRNA (miRNA) is closely related to radio-chemosensitivity in glioma stem cells (GSCs).Moreover,the growth of glioma stem cells could be inhibited comprehensively by increasing radio-chemosensitivity and apoptosis,simultaneously with the regulation of a single miRNA,which has been confirmed by some researches.Thereby microRNA is prospective for the adoption as a specific agent in targeted therapy of glioma,so as to increase the radio-chemosensitivity in glioma stem cells.
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Objective To study the calcium metabolism in tacrolimus(FK506)induced rats nephrotoxicity and the preventive effect of calcium channel blocker.Methods Twenty-four Spragueinduced or FK506-induced nephropathy model.Blood creatinine,blood electrolytes,renal tissue histopathology(HE stain)and the change of ultrastructural organization in renal cells by transmission electron microscope were observed.Results The blood creatinine levels of both CsA and FK506 groups [(36.00±2.61)and(34.17±4.54)μmol/L] were significantly higher than those of the FK506+Dilgroup and control group(all P＜0.05).The blood calcium levels of both CsA and FK506 groups (2.00±0.04 and 2.05±0.04 mmol/L) were significantly lower than those of the FK506+Dil group and control group(all P＜0.05).The blood creatinine and calcium levels of FK506+Dil group were not significantly different with those of control group(P＞O.05).Histopathology examination showed cloudy swelling and vacuolization of the renal tubular epithelial cells and intra-cellular mitochondria swelling and vacuolization in the CsA and FK506 groups.However,the pathological changes of the FK506+Dil group were remarkably milder in comparison with the CsA and FK506 groups.Concluum channel blocker,Dil,could prevent the FK506-induced nephrotoxicity.
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<p><b>OBJECTIVE</b>To cultivate human mesenchymal stem cells (MSC) derived from fetal bone marrow and examine their pluripotentiality.</p><p><b>METHODS</b>Bone marrow mononuclear cells from human fetal femur were collected by Percoll gradient centrifugation. The low density cells including MSCs were cultivated and expanded in MSCGM media. The characteristics of the multipotent MSCs were observed by implanting them into nude mice for 4 weeks.</p><p><b>RESULTS</b>Human fetal marrow MSCs were successfully cultivated and differentiated in vivo into many kinds of tissues such as bone, cartilage, adipose, skeletal muscle and tendon-like tissue.</p><p><b>CONCLUSION</b>Human fetal marrow MSCs were multipotent stem cells.</p>