Biomedical therapeutic compression textiles: Physical-mechanical property analysis to precise pressure management.

Biomedical therapeutic compression textiles (TCTs) have been extensively applied in the prevention and treatment of chronic venous insufficiency of lower extremities. An efficiency and operable development strategy to achieve the morphologic control and pressure fitness of TCTs needs to be proposed to improve the medical precision and patient adherence. Therefore, the present study qualitatively explored the influencing mechanisms of each knitting variable on physical-mechanical properties and pressure behaviors of TCTs. Then constructed the quantitative models to digitalize the knitting variables for determination of yarn-machinery setting design values. The results revealed that the feeding velocity of elastic inlay yarn materials and loop size settings impacted the pressure values owing to the diversities of fabric dimensions and mechanical tensile properties, respectively. Simultaneously, the derivation ratios of proposed circumferential and pressure models evaluated by experimental validated trials were approximately 1.1% and 10.8%, respectively. This study provided the fundamental references for the design, manufacturing, and property controlling of compression textiles to improve the biomedical therapeutic effectiveness for targeted users.

A novel optimization approach for bio-design of therapeutic compression stockings with pressure fit.

For physical-based compression therapeutic modalities, especially compression stockings (CSs), their pressure performances are necessarily evaluated by the standardized cylinder leg mannequins before biological applications. However, the insufficient pressure supply caused by morphological shape diversities between circular leg mannequins and irregular bio-bodies limits the clinical effectiveness and user compliance of CSs. Therefore, an operable and efficiency approach for optimization bio-design and digital development of CSs with enhanced compression performances needs to be proposed. The present study has adopted three-dimensional (3D) body scanning and reverse engineering technologies for lower limb cross-sectional geometric characterization and morphological classification. The irregularity of biological leg circumferential slices was determined and clustered as four levels relating to individual curvature variations. Sequentially, a new pressure prediction model was constructed through characterized geometric variations for bio-based bodies, then its acceptability was validated with good agreement by wearing trials (mean prediction accuracy was 2.53 ± 0.52 mmHg). Thus, the digital pressure reshaped development guidance was obtained based on the classified irregular levels and established pressure prediction models. Consequently, this study provides a novel reliable optimization bio-design solution for manufacturing of therapeutic compression textiles and facilitates the medical efficacy and precision of compression therapy in practical use.

Synergistic effects of fluid shear stress and adhesion morphology on the apoptosis and osteogenesis of mesenchymal stem cells.

Mechanical microenvironments, such as characteristics defining mechanical environments and fluid flow play an important role in steering the fate of mesenchymal stem cells (MSCs). However, the synergistic effect of adhesion morphology and fluid flow on the biological behavior of MSCs is seldom investigated. In this article, 0.5 or 0.8 Pa fluid shear stress (FSS) was applied to the MSCs on micropatterned substrates, and the apoptosis and osteogenic differentiation of MSCs were measured by double fluorescent staining. Results showed that the cellular adhesion patterns with low circularity and large area are beneficial to the osteogenic differentiation of individual MSCs. Meanwhile, FSS facilitated osteogenic differentiation of MSCs, as shown by the expression of alkaline phosphatase, osteocalcin, and collagen I. In addition, nuclear transfer of Yes-associated protein, a transcriptional regulator in MSCs, was enhanced after being exposed to FSS. These results demonstrated the synergistic effects of FSS and adhesion morphology in directing the fate of MSCs, and these effects may be adopted to design bio-functional substrates for cell transplantation in tissue engineering.

Finite element analysis on mechanical state on the osteoclasts under gradient fluid shear stress.

Mechanical loading, such as fluid shear stress (FSS), is regarded as the main factor that regulates the biological responses of bone cells. Our previous studies have demonstrated that the RAW264.7 osteoclast precursors migrate toward the low-FSS region under the gradient FSS field by a cone-and-plate flow chamber, in which the FSS in the outer region is larger than that in the inner region along the radial direction. Whether the FSS distribution on a cell depends on the gradient direction of FSS field should be clarified to explain this experimental observation. In this study, the finite element models of the discretely distributed or closely packed cells adherent on the bottom plate in a cone-and-plate flow chamber were constructed, and cells were regarded as compressible isotropic Hookean solid. Results showed that the average FSS of each discretely distributed cell at the quarter sector far from the center (SFC) was about 0.1% greater than that at the quarter sector near the center (SNC). In the bands with different orientations for a cell, the relative difference between the average FSS in the SFC and the SNC becomes smaller with increased band height. For the hexagonal closely packed cells, the relative value of SFC and SNC increases with increasing cell spacing. The difference between the local wall FSS in the SFC and the SNC may activate mechanosensitive ion channels and further regulate the migration of osteoclast precursors toward the low-FSS region under the gradient FSS field.

[Analysis of gastrointestinal symptoms in 80 patients with coronavirus disease 2019].

OBJECTIVE: To investigate the clinical characteristics of gastrointestinal symptoms in patients with coronavirus disease 2019 (COVID-19) during the whole disease process, and provide reference for etiological diagnosis and treatment. METHODS: The clinical data of patients with COVID-19 admitted in the Infectious Diseases Branch of the First Affiliated Hospital of University of Science and Technology of China from January 22nd, 2020 to March 8th, 2020 were analyzed retrospectively. According to whether there were gastrointestinal symptoms (poor appetite, nausea/vomiting and diarrhea), all patients were divided into gastrointestinal symptom group and asymptomatic group. The characteristics of gastrointestinal symptoms, such as poor appetite, nausea, vomiting and diarrhea were counted and analyzed, and the correlation between gastrointestinal symptoms and gender, age, basic diseases, disease severity, laboratory examination and drug treatment were analyzed. RESULTS: A total of 80 COVID-19 patients were involved, 43 cases (53.8%) presented with poor appetite, 17 cases (21.3%) had nausea and vomiting, and 33 cases (41.3%) had diarrhea. Among them, 5 cases, 1 case and 4 cases respectively preformed poor appetite, nausea/vomiting and diarrhea before admission, while the others experienced gastrointestinal symptoms within 48 hours after admission. Duration of poor appetite, nausea/vomiting and diarrhea (days) of all patients were 5.3±2.1, 2.2±1.0 and 1.4±0.9, respectively. The patients with poor appetite were older than those without symptoms (years old: 48.2±17.6 vs. 39.3±15.1), albumin (Alb) level and the lymphocytes ratio were lower than those in asymptomatic group [Alb (g/L): 39.8 (35.7, 45.1) vs. 46.1 (42.6, 49.4), lymphocytes ratio: 0.19 (0.09, 0.28) vs. 0.28 (0.17, 0.35)], while the neutrophil ratio, the levels of C-reactive protein (CRP), D-dimer, and lactate dehydrogenase (LDH) were higher than those in asymptomatic group [the neutrophil ratio: 0.74 (0.61, 0.85) vs. 0.64 (0.52, 0.76), CRP (mg/L): 21.4 (3.9, 52.9) vs. 5.6 (2.4, 14.0), D-dimer (mg/L): 0.2 (0.2, 0.5) vs. 0.2 (0.1, 0.3), LDH (µmol×s-1×L-1): 4.49 (3.59, 5.19) vs. 3.12 (2.77, 4.90)]; at the same time, more traditional Chinese medicine was used in the patients with gastrointestinal symptoms [65.1% (28/43) vs. 40.5% (15/37), all P < 0.05]. In addition, 14 cases of 18 patients with cardiovascular diseases presented with poor appetite, 7 patients had nausea and vomiting symptoms. All of the 3 patients with chronic kidney disease presented with poor appetite, nausea and vomiting, and 2 of them had diarrhea. CONCLUSIONS: The gastrointestinal symptoms in patients with COVID-19 are common. Whether it is caused by the virus or related drugs, diet and mental conditions, clinicians should analyze the causes of these symptoms timely, and then provide a better treatment for patients with COVID-19.

LncRNA CYTOR attenuates sepsis-induced myocardial injury via regulating miR-24/XIAP.

This work aims to investigate the function and mechanism of long non-coding RNA (lncRNA) cytoskeleton regulator RNA (CYTOR) in myocardial injury induced by sepsis. The sepsis-induced myocardial injury model in mice was established by intraperitoneal injection of LPS (10 mg/kg) in vivo, and cardiomyocyte H9c2 was treated with LPS to mimic sepsis in vitro. CYTOR expression and miR-24 expression were detected by qRT-PCR. After up-regulation or down-regulation of CYTOR and miR-24 expression in the H9c2 cells, and the viability of the cells was detected via MTT assay, and cell apoptosis was detected by TUNEL assay. Western blot was applied to determine the expression level of caspase 3, Bax and X-chromosome-linked inhibitor of apoptosis (XIAP). Interaction between CYTOR and miR-24 was determined by bioinformatics analysis, RT-PCR and dual luciferase reporter assay. Interaction between miR-24 and XIAP was determined through bioinformatics analysis, RT-PCR, western blot and dual luciferase reporter assay. CYTOR was markedly down-regulated. CYTOR interacted with miR-24, and negatively regulated its expression level. Over-expression of CYTOR or transfection of miR-24 inhibitors significantly promoted viability and inhibited apoptosis of H9c2 cells, while the knockdown of CYTOR and transfection of miR-24 mimics had opposite effects. CYTOR suppressed the expression level of apoptosis-related proteins, but miR-24 increased them. miR-24 directly targeted the 3'UTR of XIAP, and suppressed it, and XIAP was modulated indirectly by CYTOR. Down-regulation of CYTOR aggravates sepsis-induced cardiac injury via regulating miR-24 and XIAP.

Migration and differentiation of osteoclast precursors under gradient fluid shear stress.

The skeleton can adapt to mechanical loading through bone remodeling, and osteoclasts close to microdamages are believed to initiate bone resorption. However, whether local mechanical loading, such as fluid flow, regulates recruitment and differentiation of osteoclast precursors at the site of bone resorption has yet to be investigated. In the present study, finite element analysis first revealed the existence of a low-fluid shear stress (FSS) field inside microdamage. Based on a custom-made device of cone-and-plate fluid chamber, finite element analysis and particle image velocimetry measurement were performed to verify the formation of gradient FSS flow field. Furthermore, the effects of gradient FSS on the migration, aggregation, and fusion of osteoclast precursors were observed. Osteoclast precursor RAW264.7 cells migrated along a radial direction toward the region with decreased FSS during exposure to gradient FSS stimulation for 40 min, thereby deviating from the direction of actual fluid flow indicated by fluorescent particles. When calcium signaling pathway was inhibited by gadolinium and thapsigargin, cell migration toward a low-FSS region was significantly reduced. For the other cell lines MC3T3-E1, PDLF, rat mesenchymal stem cells, and Madin-Darby canine kidney epithelial cells, gradient FSS stimulation did not lead to low-FSS inclined migration. After being cultured under gradient FSS stimulation for 6 days, RAW264.7 cells showed significantly higher density and ratio of TRAP-positive multinucleated osteoclasts in the low-FSS region to those in the high-FSS region. Therefore, osteoclast precursor cells may exhibit the special ability to sense FSS gradient and tend to actively migrate toward low-FSS regions, which are regulated by calcium signaling pathway.

Novel cone-and-plate flow chamber with controlled distribution of wall fluid shear stress.

Fluid flow in blood vessels or interstitial fluid flow within tissue cavities plays important roles in tissue regeneration. One of the fundamental issues for in vitro study of the effects of fluid shear stress (FSS) on cells is the development of a flow chamber that can provide a controlled FSS field. In this study, we developed a novel cone-and-plate flow chamber based on viscometry technology, in which the cone's shape was optimized to produce a uniform wall FSS field on the surface of a standard six-well cell culture plate. By using a FSS finite element method, the effects of different geometric parameters of cone and plate, viscosity coefficient of fluid, and angular velocity on wall FSS at the bottom surface of the culture plate were investigated. Results of the simulation demonstrated that the cone with polyline or truncated generatrix (TG) could produce wall FSS as high as 1 or 2 Pa with uniform distribution, in which the area of the identical region for the cone with TG accounts for more than 69% of the total area. In addition, with the cone in close proximity to the plate surface, a gap distance of 0.1 mm can produce a uniform FSS field with a magnitude as high as 2 Pa over the majority of the plate. Furthermore, particle image velocimetry was utilized to measure the distribution of wall FSS, through which the numerical simulation results were experimentally demonstrated. This study presents a powerful new device for in vitro fluid flow loading at the cellular level.