Myricetin alleviates H2O2-induced senescence and apoptosis in rat nucleus pulposus-derived mesenchymal stem cells

Introduction. Transplantation of mesenchymal stem cells (MSCs) has been reported to be a novel promising target for the regeneration of degenerated intervertebral discs (IVDs). However, the culture and survival limitations of MSCs remain challenging for MSC-based biological therapy. Myricetin, a common natural flavonoid, has been suggested to possess antiaging and antioxidant abilities. Therefore, we investigated the biological function of myricetin, and its related mechanisms involving cell senescence in intervertebral disc degeneration (IDD). Material and methods. The nucleus pulposus-derived mesenchymal stem cells (NPMSCs) were isolated from 4-month-old Sprague-Dawley (SD) rats and identified by examining surface markers and multipotent differentiation. Rat NPMSCs were cultured in an MSC culture medium or culture medium with different concentrations of H2O2. Myricetin or the combination of myricetin and EX527 were added to the culture medium to investigate the effects of myricetin. Cell viability was evaluated by cell counting kit-8 assays (CCK-8). The apoptosis rate was determined using Annexin V/PI dual staining. The mitochondrial membrane potential (MMP) was analyzed by a fluorescence microscope after JC-1 staining. The cell senescence was determined by SA-β-Gal staining. MitoSOX green was used to selectively estimate mitochondrial reactive oxygen species (ROS) Apoptosis-associated proteins (Bax, Bcl2, and cleaved caspase-3), senescence markers (p16, p21, and p53), and SIRT1/PGC-1α signaling pathway-related proteins (SIRT1 and PGC-1α) were evaluated by western blotting. Results. The cells isolated from nucleus pulposus (NP) tissues met the criteria for MSCs. Myricetin showed no cytotoxicity up to a concentration of 100 μM in rat NPMSCs cultured for 24 h. Myricetin pretreatment exhibited protective effects against H2O2-induced apoptosis. Myricetin could also alleviate H2O2-induced mitochondrial dysfunctions of increased mitochondrial ROS production and reduced MMP. Moreover, myricetin pretreatment delayed rat NPMSC senescence, as evidenced by decreased senescence indicators and reduced SA-β-Gal activity. Pretreatment of NPMSCs with 10 μM EX527, a selective inhibitor of SIRT1, prior to exposure to 100 μM H2O2, reversed the inhibitory effects of myricetin on cell apoptosis. Conclusions. Myricetin could affect the SIRT1/PGC-1α pathway to protect mitochondrial functions and alleviate cell senescence in H2O2-treated NPMSCs

A novel method for in vivo measurement of dynamic ischiofemoral space based on MRI and motion capture

Purpose: To use a novel in vivo method to simulate a moving hip model. Then, measure the dynamic bone-to-bone distance, and analyze the ischiofemoral space (IFS) of patients diagnosed with ischiofemoral impingement syndrome (IFI) during dynamic activities.Methods: Nine healthy subjects and 9 patients with IFI were recruited to collect MRI images and motion capture data. The motion trail of the hip during motion capture was matched to a personalized 3D hip model reconstructed from MRI images to get a dynamic bone model. This personalized dynamic in vivo method was then used to simulate the bone motion in dynamic activities. Validation was conducted on a 3D-printed sphere by comparing the calculated data using this novel method with the actual measured moving data using motion capture. Moreover, the novel method was used to analyze the in vivo dynamic IFS between healthy subjects and IFI patients during normal and long stride walking.Results: The validation results show that the root mean square error (RMSE) of slide and rotation was 1.42 mm/1.84° and 1.58 mm/2.19°, respectively. During normal walking, the in vivo dynamic IFS was significantly larger in healthy hips (ranged between 15.09 and 50.24 mm) compared with affected hips (between 10.16 and 39.74 mm) in 40.27%–83.81% of the gait cycle (p = 0.027). During long stride walking, the in vivo dynamic IFS was also significantly larger in healthy hips (ranged between 13.02 and 51.99 mm) than affected hips (between 9.63 and 44.22 mm) in 0%–5.85% of the gait cycle (p = 0.049). Additionally, the IFS of normal walking was significantly smaller than long stride walking during 0%–14.05% and 85.07%–100% of the gait cycle (p = 0.033, 0.033) in healthy hips. However, there was no difference between the two methods of walking among the patients.Conclusions: This study established a novel in vivo method to measure the dynamic bone-to-bone distance and was well validated. This method was used to measure the IFS of patients diagnosed with IFI, and the results showed that the IFS of patients is smaller compared with healthy subjects, whether in normal or long stride walking. Meanwhile, IFI eliminated the difference between normal and long stride walking

Mice Deficient in Cyp4a14 Have An Increased Number of Goblet Cells and Attenuated Dextran Sulfate Sodium-Induced Colitis

Background/Aims: Cyp4a14 is a member of cytochrome P450 (Cyp450) enzyme superfamily that possesses NADPH monooxygenase activity, which catalyzes omega-hydroxylation of medium-chain fatty acids and arachidonic acid. Study suggests that down-regulation of Cyp4a14 has an anti-inflammatory response in intestine. The present study was to test the function of Cyp4a14 in dextran sulfate sodium (DSS)-induced colitis. Methods: Female Cyp4a14-knockout (KO) and wild-type (WT) mice were treated with DSS for 6 days to induce colitis. The colon of mice was histologically observed by hematoxylin and eosin (H&E) and periodic acid Schiff (PAS) staining. The serum malondialdehyde (MDA), an endogenous indicator of oxidative stress, was chemically measured. Proinflammatory and NADPH oxidase genes were examined by quantitative polymerase chain reaction (qPCR). Results: Cyp4a14-KO mice had a significantly higher number of goblet cells in the colon and were more resistant to DSS-induced colitis compared with the WT mice. The DSS-treated KO mice had lower levels of MDA. Consistent with the milder inflammatory pathological changes, DSS-treated KO mice had lower levels of IL-1β, IL-6 and TNF-α mRNA in the liver and the colon. Moreover, the colon of DSS-treated Cyp4a14-KO and WT mice had higher mRNA levels of two members of NADPH oxidases, Nox2 and Nox4, suggesting that both Nox2 and Nox4 are inflammatory markers. By contrast, DSS-treated WT and KO mice had drastically decreased epithelium-localized Nox1 and dual oxidase (Duox) 2 mRNA levels, coinciding with the erosion of the mucosa induced by DSS. Conclusion: These results suggests a hypothesis that the increased goblet cell in the colon of Cyp4a14-KO mice provides protection from mucosal injury and Cyp4a14-increased oxidative stress exacerbates DSS-induced colitis. Therefore, Cyp4a14 may represent a potential target for treating colitis

Synergy between loss of NF1 and overexpression of MYCN in neuroblastoma is mediated by the GAP-related domain

Earlier reports showed that hyperplasia of sympathoadrenal cell precursors during embryogenesis in Nf1-deficient mice is independent of Nf1’s role in down-modulating RAS-MAPK signaling. We demonstrate in zebrafish that nf1 loss leads to aberrant activation of RAS signaling in MYCN-induced neuroblastomas that arise in these precursors, and that the GTPase-activating protein (GAP)-related domain (GRD) is sufficient to suppress the acceleration of neuroblastoma in nf1-deficient fish, but not the hypertrophy of sympathoadrenal cells in nf1 mutant embryos. Thus, even though neuroblastoma is a classical “developmental tumor”, NF1 relies on a very different mechanism to suppress malignant transformation than it does to modulate normal neural crest cell growth. We also show marked synergy in tumor cell killing between MEK inhibitors (trametinib) and retinoids (isotretinoin) in primary nf1a-/- zebrafish neuroblastomas. Thus, our model system has considerable translational potential for investigating new strategies to improve the treatment of very high-risk neuroblastomas with aberrant RAS-MAPK activation. DOI: http://dx.doi.org/10.7554/eLife.14713.00

Reductive cyanation of organic chlorides using CO2 and NH3 via Triphos–Ni(I) species

Nitriles are key intermediates in production of pharmaceuticals, agrochemicals and organic materials. Here, the authors report a nickel-catalyzed reductive cyanation of organic chlorides with CO2/NH3 and urea as cyanation reagents to afford a broad range of organic nitriles

Experimental study on flame combustion characteristics of large-bore marine diesel engine based on endoscopic technology

Large-bore marine diesel engines have the characteristics of poor ignition performance and insufficient combustion in the cylinder. This work revealed the combustion and emission performance of large-bore marine diesel engines based on endoscopic visualization technology. The flame temperature and soot distribution were analyzed in radial and axial directions. Results show that the large-bore diesel engine has a poor combustion effect because of the large fuel injection quantity and insufficient fuel-air mixing effect in the cylinder. The temperature in the cylinder rises twice in the late stage of combustion. The average temperature rises by 3.8%, caused by the secondary ignition of part of the unburned diesel. In addition, the large-bore engine produces a large amount of soot due to an insufficient mixing effect. It can be observed from the radial flame visualization images that the propagation speed of the flame is slow. The time required for the flame to propagate to the wall at 50% load is reduced by 31% compared with 25% load. The downward movement of the piston causes the flame tumble flow in the cylinder, resulting in an apparent asymmetric structure of the flame development