The Enigma of Tau Protein Aggregation: Mechanistic Insights and Future Challenges.

Tau protein misfolding and aggregation are pathological hallmarks of Alzheimer's disease and over twenty neurodegenerative disorders. However, the molecular mechanisms of tau aggregation in vivo remain incompletely understood. There are two types of tau aggregates in the brain: soluble aggregates (oligomers and protofibrils) and insoluble filaments (fibrils). Compared to filamentous aggregates, soluble aggregates are more toxic and exhibit prion-like transmission, providing seeds for templated misfolding. Curiously, in its native state, tau is a highly soluble, heat-stable protein that does not form fibrils by itself, not even when hyperphosphorylated. In vitro studies have found that negatively charged molecules such as heparin, RNA, or arachidonic acid are generally required to induce tau aggregation. Two recent breakthroughs have provided new insights into tau aggregation mechanisms. First, as an intrinsically disordered protein, tau is found to undergo liquid-liquid phase separation (LLPS) both in vitro and inside cells. Second, cryo-electron microscopy has revealed diverse fibrillar tau conformations associated with different neurodegenerative disorders. Nonetheless, only the fibrillar core is structurally resolved, and the remainder of the protein appears as a "fuzzy coat". From this review, it appears that further studies are required (1) to clarify the role of LLPS in tau aggregation; (2) to unveil the structural features of soluble tau aggregates; (3) to understand the involvement of fuzzy coat regions in oligomer and fibril formation.

Capture Fluorocarbon and Chlorofluorocarbon from Air Using DUT-67 for Safety and Semi-Quantitative Analysis.

Fluoro- and chlorofluorocabons (FC/CFCs) are important refrigerants, solvents, and fluoropolymers in industry while being toxic and carrying high global warming potential. Detection and reclamation of FC/CFCs based on adsorption technology with highly selective adsorbents is important to labor safety and environmental protection. Herein, the study reports an integrated method to combine capture, separation, enrichment, and analysis of representative FC/CFCs (chlorodifluoromethane(R22) and 1,1,1,2-tetrafluoroethane (R134a)) by using the highly stable and porous Zr-MOF, DUT-67. Gas adsorption and breakthrough experiments demonstrate that DUT-67 has high R22/R134a uptake (124/116 cm3 g-1) and excellent R22/R134a/CO2 separation performance (IAST selectivities of R22/CO2 and R134a/CO2 ranging from 51.4 to 33.3, and 31.1 to 25.8), even in rather low concentration and humid conditions. A semi-quantitative analysis protocol is set up to analyze the low concentrations of R22/R134a based on the high selective R22/R134a adsorption ability, fast adsorption kinetics, water-resistant utility, facile regeneration, and excellent recyclability of DUT-67. In situ single-crystal X-ray diffraction, theoretical calculations, and in situ diffuse reflectance infrared Fourier transform spectra have been employed to understand the adsorption mechanism. This work may provide a potential adsorbent for purge and trap technique under room temperature, thus promoting the application of MOFs for VOCs sampling and quantitative analysis.

Microporous Fluorinated MOF with Multiple Adsorption Sites for Efficient Recovery of C2H6 and C3H8 from Natural Gas.

Purifying C2H6/C3H8 from a ternary natural gas mixture through adsorption separation is an important but challenging process in the petrochemical industry. To address this challenge, the industry is exploring effective strategies for designing high-performance adsorbents. In this study, we present two metal-organic frameworks (MOFs), DMOF-TF and DMOF-(CF3)2, which have fluorinated pores obtained by substituting linker ligands in the host material. This pore engineering strategy not only provides suitable pore confinement but also enhances the adsorption capacities for C2H6/C3H8 by providing additional binding sites. Theoretical calculations and transient breakthrough experiments show that the introduction of F atoms not only improves the efficiency of natural gas separation but also provides multiple adsorption sites for C2H6/C3H8-framework interactions.

Metformin pre-treatment of stem cells from human exfoliated deciduous teeth promotes migration and angiogenesis of human umbilical vein endothelial cells for tissue engineering.

BACKGROUND AIMS: Stem cells from human exfoliated deciduous teeth (SHED) play a significant role in tissue engineering and regenerative medicine. Angiogenesis is crucial in tissue regeneration and a primary target of regenerative medicine. As a first-line anti-diabetic drug, metformin demonstrates numerous valuable impacts on stem cells. This study aimed to explore metformin's impact and mechanism of action on SHED-mediated angiogenesis. METHODS: First, cell proliferation; flow cytometry; osteogenic, adipogenic and chondrogenic induction; and proteomics analyses were conducted to explore the role of metformin in SHED. Subsequently, migration and tube formation assays were used to evaluate chemotaxis and angiogenesis enhancement by SHED pre-treated with metformin under co-culture conditions in vitro, and relative messenger RNA expression levels were determined by quantitative reverse transcription polymerase chain reaction. Finally, nude mice were used for in vivo tube formation assay, and sections were analyzed through immunohistochemistry staining with anti-human CD31 antibody. RESULTS: Metformin significantly promoted SHED proliferation as well as osteogenic, adipogenic and chondrogenic differentiation. Proteomics showed that metformin significantly upregulated 124 differentially abundant proteins involved in intracellular processes, including various proteins involved in cell migration and angiogenesis, such as MAPK1. The co-culture system demonstrated that SHED pre-treated with metformin significantly improved the migration and angiogenesis of human umbilical vein endothelial cells. In addition, SHED pre-treated with metformin possessed greater ability to promote angiogenesis in vivo. CONCLUSIONS: In summary, the authors' findings illustrate metformin's mechanism of action on SHED and confirm that SHED pre-treated with metformin exhibits a strong capacity for promoting angiogenesis. This helps in promoting the application of dental pulp-derived stem cells pre-treated with metformin in regeneration engineering.

Association between functional genetic variants in retinoid X receptor-α/γ and the risk of gestational diabetes mellitus in a southern Chinese population.

To clarify the effect of retinoid X receptor-α/γ (RXR-α/γ) genes functional genetic variants (RXR-α rs4842194 G>A, RXR-γ rs100537 A>G and rs2134095 T>C) on the risk of gestational diabetes mellitus (GDM), a case-control study with 573 GDM patients and 740 pregnant women with normal glucose tolerance was performed in Guangxi area of China. An odds ratio (OR) with its corresponding 95% confidence interval (CI) was used to assess the strengths of the association between genetic variation and GDM. After adjustment of age and pre-BMI, the logistic regression analysis showed that the rs2134095 was significantly associated with GDM risk (CC vs. TT/TC: adjusted OR = 0.71, 95% CI = 0.56-0.90) in all subjects, and this result remained highly significant after Bonferroni's correction for multiple testing (P=0.004). The stratified analysis showed that rs2134095 was significantly associated with the risk of GDM among age > 30 years (adjusted OR = 0.61, 95% CI = 0.39-0.97), BMI > 22 kg/m2 (adjusted OR = 0.46, 95% CI = 0.30-0.70), systolic blood pressure (SBP) > 120 mmHg (adjusted OR = 1.96, 95% CI = 1.14-3.36), glycosylated hemoglobin A1c (HbA1c) < 6.5% (adjusted OR = 1.41, 95% CI = 1.11-1.78), TG ≤ 1.7 mmol/l (adjusted OR = 2.57, 95% CI = 1.45-4.53), TC ≤ 5.18 mmol/l (adjusted OR = 1.58, 95% CI = 1.13-2.22), high-density lipoprotein cholesterol (HDL-c) ≤ 1.5 mmol/l (adjusted OR = 1.70, 95% CI = 1.16-2.49) and low-density lipoprotein cholesterol (LDL-c) > 3.12 mmol/l (adjusted OR = 1.47, 95% CI = 1.08-2.00) subjects, under the recessive genetic model. We also found that rs2134095 interacted with age (Pinteraction=0.039), pre-BMI (Pinteraction=0.040) and TG (Pinteraction=0.025) influencing individual's genetic susceptibility to GDM. The rs2134095 T>C is significantly associated with the risk of GDM by effect of a single locus and/or complex joint gene-gene and gene-environment interactions. Larger sample-size and different population studies are required to confirm the findings.

Comparison of hydrability, antioxidants, microstructure, and sensory quality of barley grass powder using ultra-micro-crushing combined with hot air and freeze drying.

To explore the physicochemical characters of barley grass, ultra-micro-crushing (UMC) technology combined with air drying or freeze drying was carried out. After barley grass was air-dried at 70°C or freeze-dried at 15°C, it was grinded for 30, 60, 90, and 120 min using UMC, respectively. After combined processing, moisture content, particle size, odor, color, microstructure, water and oil-holding capacity, the content of flavonoid and chlorophyll, water activity, and sensory qualities were determined. The particle size of barley grass powder decreased, and lightness value was increased; water and oil-holding capacity decreased significantly (p ≤ .05), whereas swelling and dissolving capacity increased in the processed grass powder. On the other hand, the total flavonoid content increased significantly (p ≤ .05). Barley grass odor features sulfide aroma, and its microstructure demonstrates lamellar morphology with some fewer fragmented pieces. The results suggested combined UMC at 90-120 min will be suitable for processing barley grass powder.

Different Types of Family History of Stroke and Stroke Risk: Results Based on 655,552 Individuals.

BACKGROUND: Many studies concentrated on the relationships between different types of family history and stroke, but they have not arrived at an unified conclusion. We conducted a comprehensive systematic review to further evaluate the associations. METHODS: Different databases were searched for related studies published from 1990 to August 2017. The relative risk was considered as the common measure of association across different studies. Heterogeneity of effects across studies was quantified by I2. RESULTS: Sixteen published studies (total participants: 655,552) were eligible in this study. The pooled multifactorial adjusted relative risk (RR) (95% confidence interval [CI]) was 1.40 (1.18, 1.67) for individuals with paternal history, 1.36 (1.20, 1.53) for those with maternal history, and 1.44 (1.17, 1.77) for those with sibling history. Based on cohort studies, the pooled adjusted RRs (95%CIs) for paternal, maternal, and sibling history were 1.33 (1.11-1.59), 1.28 (1.14-1.45), and 1.24 (1.01-1.51), respectively, all of which were smaller than those based on case-control and cross-sectional studies. In studies with large sample size, the respective adjusted RR (95%CI) of stroke for paternal, maternal, and sibling history was 1.30 (1.09, 1.56), 1.30 (1.18, 1.44), and 1.26 (1.02, 1.56), which was lower than that in studies with small sample size. CONCLUSIONS: Each type of family history of stroke was associated with an increased stroke risk. We could not find significant differences among stroke risks relating to different types of family history of stroke. Thus, paternal, maternal, and sibling history require our equal attention in the stroke prevention and control work.

[Effects of Renshenjian decoction on pancreatic metabonomic profiles in insulin resistance rats based on ¹H-NMR metabonomics].

Pancreas metabonomic profiles of the type 2 diabetic rats' induced by streptozotocin(STZ) and high-sugar, high fat diet on the treatment of Renshenjian decoction(RSJD) after 8 weeks were investigated.In this study, 48 Rats were randomly divided into four groups: normal control (NC), Pathological model (PM), Renshenjian decoction(RSJD 3.76 g·kg⁻¹) and glimepiride control (GC 0.04 mg·kg⁻¹). They are induced insulin resistance model of type 2 diabetes mellitus by streptozotocin(STZ) after 4 weeks' high-sugar, high fat diet except for NC. After sucessful modeling, they are given intragastric administration respectively with same amount of saline, RSJD and glimepiride in 4 weeks. At the end of the 8th week, the pancreatic tissue of rats in each group was collected, and the ¹H-NMR spectrum was collected after being treated by certain method, and analyzed by principal component analysis (PCA). Compared with NC's rats, we found PM's a significant elevation in the level of leucine/isoleucine, valine, lactic acid, creatine but reduction in the level of inose and less obvious changes in the level of creatine, cholic acid, taurine in pancreatic extract. After having been recieved RSJD, reduction level in leucine/isoleucine, valine, alanine, creatine, choline, taurine are also found in pancreatic extract of RSJD's rats, together with the increase of creatinine and tryptophan levels. The results showed that RSJD could regulate the level of amino acids in pancreas of IR rats, promoting a recovery in the process of metabolism. It's helpful to simulate the metabolic changes of IR rats via ¹H-NMR for a further understanding to study the mechanism how RSJD treat IR rats.

An Integrated Strategy to Qualitatively Differentiate Components of Raw and Processed Viticis Fructus Based on NIR, HPLC and UPLC-MS Analysis.

Viticis Fructus is a traditional Chinese herbal drug processed by various methods to achieve different clinical purposes. Thermal treatment potentially alters chemical composition, which may impact on effectiveness and toxicity. In order to interpret the constituent discrepancies of raw versus processed (stir-fried) Viticis Fructus, a multivariate detection method (NIR, HPLC, and UPLC-MS) based on metabonomics and chemometrics was developed. Firstly, synergy interval partial least squares and partial least squares-discriminant analysis were employed to screen the distinctive wavebands (4319 - 5459 cm-1) based on preprocessed near-infrared spectra. Then, HPLC with principal component analysis was performed to characterize the distinction. Subsequently, a total of 49 compounds were identified by UPLC-MS, among which 42 compounds were eventually characterized as having a significant change during processing via the semiquantitative volcano plot analysis. Moreover, based on the partial least squares-discriminant analysis, 16 compounds were chosen as characteristic markers that could be in close correlation with the discriminatory near-infrared wavebands. Together, all of these characterization techniques effectively discriminated raw and processed products of Viticis Fructus. In general, our work provides an integrated way of classifying Viticis Fructus, and a strategy to explore discriminatory chemical markers for other traditional Chinese herbs, thus ensuring safety and efficacy for consumers.

The rs2609255 polymorphism in the FAM13A gene is reproducibly associated with silicosis susceptibility in a Chinese population.

BACKGROUND: Two recent genome-wide association studies (GWASs) reported that the FAM13A gene at the 4q22 locus associated with pulmonary fibrosis (defined by rs2609255) overlapping with COPD (defined by rs6837671). We hypothesized that single-nucleotide polymorphisms (SNPs) related to lung disease (especially pulmonary fibrosis) identified in this region are also associated with the risk of silicosis. METHODS: To test this hypothesis, we genotyped these two SNPs (rs2609255 and rs6837671) in a case-control study including 177 silicosis cases and 204 controls with silica dust exposure years similar to the levels for cases in a Chinese population. RESULTS: We found that rs2609255 was significantly associated with increased silicosis risk (dominant model: OR = 1.71; 95% CI = 1.01-2.92; P = 0.047). Additionally, eQTL analysis based on the GTEx database indicated that the rs2609255 polymorphism may alter the expression level of FAM13A in lung tissues (P = 1.8 × 10-4). Furthermore, interaction analyses showed that rs2609255 interacts multiplicatively with years of silica dust exposure to contribute to silicosis risk (interaction P = 0.040). CONCLUSIONS: These results indicate that rs2609255 may modify silicosis susceptibility in the Chinese population.