Preparation and characterizations of three-dimensional porous collagen/graphene oxide/hydroxyapatite nanocomposite scaffolds for bone tissue engineering

Studies have reported that the incorporation of graphene oxide (GO) and hydroxyapatite (HA) into biocompatible polymers (such as collagen (Col), chitosan, alginate, etc) results in enhanced structural and mechanical properties respectively. The objective of this study was to prepare and characterize three-dimensional (3D) porous Col/GO/HA nanocomposite scaffolds and to investigate cytocompatibility and osteogenic differentiation potential of rat bone marrow mesenchymal stem cells (rBMSCs) on the as-prepared scaffolds. The SEM images revealed that the scaffolds were porous with the pore diameter inversely proportional to the concentration of HA. XRD results were able to depict the characteristic peaks for HA which shows that HA was incorporated into the scaffolds. The rBMSCs which were cultured on the scaffolds were able to attach and proliferate during the 21 days of the experiment which indicates that the as-prepared scaffolds are cytocompatible. The Alizarin red staining demonstrated the presence of calcium deposits as there were orange-red stains on the samples after culturing the cells using the osteogenic differentiation medium. These results demonstrate the promising potential of the 3D porous Col/GO/HA nanocomposite scaffolds for applications in bone tissue engineering

NO signaling and S-nitrosylation regulate PTEN inhibition in neurodegeneration

<p>Abstract</p> <p>Background</p> <p>The phosphatase PTEN governs the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway which is arguably the most important pro-survival pathway in neurons. Recently, PTEN has also been implicated in multiple important CNS functions such as neuronal differentiation, plasticity, injury and drug addiction. It has been reported that loss of PTEN protein, accompanied by Akt activation, occurs under excitotoxic conditions (stroke) as well as in Alzheimer's (AD) brains. However the molecular signals and mechanism underlying PTEN loss are unknown.</p> <p>Results</p> <p>In this study, we investigated redox regulation of PTEN, namely S-nitrosylation, a covalent modification of cysteine residues by nitric oxide (NO), and H₂O₂-mediated oxidation. We found that S-nitrosylation of PTEN was markedly elevated in brains in the early stages of AD (MCI). Surprisingly, there was no increase in the H₂O₂-mediated oxidation of PTEN, a modification common in cancer cell types, in the MCI/AD brains as compared to normal aged control. Using several cultured neuronal models, we further demonstrate that S-nitrosylation, in conjunction with NO-mediated enhanced ubiquitination, regulates both the lipid phosphatase activity and protein stability of PTEN. S-nitrosylation and oxidation occur on overlapping and distinct Cys residues of PTEN. The NO signal induces PTEN protein degradation via the ubiquitin-proteasome system (UPS) through NEDD4-1-mediated ubiquitination.</p> <p>Conclusion</p> <p>This study demonstrates for the first time that NO-mediated redox regulation is the mechanism of PTEN protein degradation, which is distinguished from the H₂O₂-mediated PTEN oxidation, known to only inactivate the enzyme. This novel regulatory mechanism likely accounts for the PTEN loss observed in neurodegeneration such as in AD, in which NO plays a critical pathophysiological role.</p

Correlation Between Bioelectrical Impedance Analysis and Chest CT-Measured Erector Spinae Muscle Area: A Cross-Sectional Study

BackgroundSkeletal muscle mass (SMM) plays an important part in diverse health and disease states. Bioelectrical impedance analysis (BIA) and computed tomography (CT) are available for its assessment. However, muscle mass assessed by BIA may be influenced by multiple factors. The erector spinae muscle area (ESA) on chest CT is recently presumed to be representative of SMM. This study aimed to derive BIA from the ESA and evaluate the magnitude of association (between ESA measured from chest CT) and BIA.MethodsSubjects hospitalized for health checkups between December 2020 and December 2021, having undergone both BIA (50 kHz, 0.8 mA) and chest CT, were included. ESA was quantified at the level of the 12th thoracic vertebra (T12-ESA) by a standardized semi-automated segmentation algorithm. Low SMM was defined using the Asian Working Group for Sarcopenia criteria. The association between T12-ESA and BIA was then evaluated. Stratified analyses by sex and BMI were also performed.ResultsAmong 606 included subjects (59.7 ± 16.6 years, 63.5% male), 110 (18.2%) had low SMM. BMI in low and normal SMM groups was 20.1 and 24.7 kg/m2, respectively. Current smoking, drinking, chronic obstructive pulmonary disease, and chronic renal dysfunction were more frequently seen in the low SMM group than in the normal SMM group. The final regression model included T12-ESA, weight, BMI, and age, and had an adjusted R2 of 0.806 with BIA. In the validation group, the correlation between T12-ESA-derived BIA and BIA remained high (Pearson correlation = 0.899). Stratified analysis disclosed a stronger correlation between T12-ESA and BIA in male subjects than in female subjects (adjusted R2 = 0.790 vs. adjusted R2 = 0.711, p &lt; 0.05), and a better correlation was observed in obese (BMI ≥ 30 kg/m2) compared with underweight (BMI &lt; 18.5 kg/m2) subjects (adjusted R2 = 0.852 vs. adjusted R2 = 0.723, p &lt; 0.05). Additional analysis revealed a significant correlation between T12-ESA and skeletal muscle cross-sectional area at the 3rd lumbar vertebra (L3-CSA) (adjusted R2 = 0.935, p &lt; 0.001).ConclusionsCT-based assessment of ESA at the T12 level is feasible and correlated well with BIA, especially in male subjects and obese subjects

Competing Interface and Bulk Effect-Driven Magnetoelectric Coupling in Vertically Aligned Nanocomposites.

Room-temperature magnetoelectric (ME) coupling is developed in artificial multilayers and nanocomposites composed of magnetostrictive and electrostrictive materials. While the coupling mechanisms and strengths in multilayers are widely studied, they are largely unexplored in vertically aligned nanocomposites (VANs), even though theory has predicted that VANs exhibit much larger ME coupling coefficients than multilayer structures. Here, strong transverse and longitudinal ME coupling in epitaxial BaTiO3:CoFe2O4 VANs measured by both optical second harmonic generation and piezoresponse force microscopy under magnetic fields is reported. Phase field simulations have shown that the ME coupling strength strongly depends on the vertical interfacial area which is ultimately controlled by pillar size. The ME coupling in VANs is determined by the competition between the vertical interface coupling effect and the bulk volume conservation effect. The revealed mechanisms shed light on the physical insights of vertical interface coupling in VANs in general, which can be applied to a variety of nanocomposites with different functionalities beyond the studied ME coupling effect.The work at Los Alamos National Laboratory was supported by the NNSA's Laboratory Directed Research and Development Program and was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy Office of Science. Los Alamos National Laboratory, an affirmative action equal opportunity employer, is managed by Triad National Security, LLC for the U.S. Department of Energy's NNSA, under contract 89233218CNA000001. Angular‐dependent magnetization studies (L.C.) were partially supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Materials Sciences, and Engineering Division

Saponins Extracted from Tea (Camellia Sinensis) Flowers Induces Autophagy in Ovarian Cancer Cells

Tea flower saponins (TFS) possess effective anticancer properties. The diversity and complexity of TFS increases the difficulty of their extraction and purification from tea flowers. Here, multiple methods including solvent extraction, microporous resin separation and preparative HPLC separation were used to obtain TFS with a yield of 0.34%. Furthermore, we revealed that TFS induced autophagy&mdash;as evidenced by an increase in MDC-positive cell populations and mCherry-LC3B-labeled autolysosomes and an upregulation of LC3II protein levels. 3-MA reversed the decrease in cell viability induced by TFS, showing that TFS induced autophagic cell death. TFS-induced autophagy was not dependent on the Akt/mTOR/p70S6K signaling pathway. TFS-induced autophagy in OVCAR-3 cells was accompanied by ERK pathway activation and reactive oxygen species (ROS) generation. This paper is the first report of TFS-mediated autophagy of ovarian cancer cells. These results provide new insights for future studies of the anti-cancer effects of TFS

音强斜率特性区别同卵双胞胎语音的实验研究

为了寻找司法话者识别中区别同卵双胞胎语音的有效参量，该文利用音节音强的斜率特性对同卵双胞 胎语音进行了实验研究。结果发现，在 90% 的置信度下，所有实验的双胞胎语音均能够被音节音强斜率予以 区别，并且音强下降斜率的区别力明显高于音强上升斜率的区别力。因此得出结论，音节音强的斜率特性具有 比音节间相对音强与相对时长二者联合检验更强的区别力，可以作为区别同卵双胞胎语音的有效参量。 In this paper, the slope characteristics of syllable intensity are used to find effective parameters to distinguish identical twins’ speech in forensic speaker comparison. It is found that at 90% confidence, the twins’ speech of all experiments can be distinguished by the syllable intensity slopes, and the difference in the negative slope is significantly higher than the difference in the positive slope. Therefore, it is concluded that the slope characteristics of the syllable intensity have a stronger discriminating power than the joint test of the relative intensity and the relative duration between the syllables, and can be used as an effective parameter for distinguishing the identical twins’ voices