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•Bio-based aromatic polyketones (PKs) and polyetherketones (PEKs) were synthesized.•Molecular weights of the PKs were 2.6–15.0 × 103, and those of the PEKs were 1.0 × 103.•The PKs ...exhibited high glass transition temperatures in the range 250–297 °C.
Bio-based aromatic polyketones (PKs) and polyetherketones (PEKs) were synthesized by the electrophilic substitution reaction of alkoxylated divanillic acid (R-DVA) and 2,2′-dimethoxybiphenyl or diphenylether. Alkoxy side-chains were introduced at the hydroxyl groups of DVA prior to polymerization. Polymerizations were carried out in a phosphorus pentoxide (P2O5)/methanesulfonic acid (MsOH) system. DVA-based PKs and PEKs were soluble in common organic solvents including chloroform and dimethylsulfoxide, and their chemical structures were determined by 1H and 13C NMR. The weight-average molecular weights (Mw) of the PKs were 2.6–15.0 × 103 g/mol, and those of all PEKs were approximately 1.0 × 103. The 10% degradation temperatures of the PKs and PEKs were 340–400 °C. Dynamic mechanical analysis showed that the PKs and PEKs were amorphous. The PKs with methyl to butyl side-chains exhibited high glass transition temperatures (Tg) in the range 250–297 °C, while Tg of PK (octyl side-chain) was 157 °C and those of the PEKs were 73–127 °C.
Random-coil and triple-helix curdlan hydrogels cross-linked with ethylene glycol diglycidyl ether were fabricated using curdlan alkaline solutions with different concentrations. Triple-helix ...hydrogels had higher tensile strengths than random-coil hydrogels. Small-angle-X-ray scattering analyses revealed that triple-helix hydrogels contained aggregates, which were likely bundles of triple helices. Moreover, in situ small-angle-X-ray scattering analyses indicated orientation of these triple-helix bundles during elongation. Cross-linked curdlan hydrogels were stretched up to 3 times and subsequently dried to prepare stretched, dried gel-films. Triple-helix dried gel-films exhibited a maximum strength of 200 MPa, which was markedly higher than that of random-coil dried gel-films. Triple-helix curdlan hydrogels and dried gel-films exhibited higher tensile strengths than their random-coil counterparts, suggesting that triple-helix bundles underwent crystallization and orientation.
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•Curdlan hydrogels with random coils or triple helices were chemically cross-linked.•SAXS analysis revealed that triple-helix hydrogels comprised triple-helix bundles.•In situ SAXS analysis showed orientation of triple-helix bundles during elongation.•Stretched, dried gel-films were prepared by elongating and drying hydrogels.•Triple-helix hydrogels and stretched, dried gel-films had the best tensile strength.
This work synthesized a series of symmetrical methylated dialkoxydivanillic acid monomers (Me-RDVAs) with different side-chain lengths (meaning the number of carbons, n, in alkoxy groups, where ...n = 1, 2, 3 or 4) and methyl (Me), ethyl, propyl or butyl R groups. Homopolyesters were obtained from Me-RDVAs and 1,4-benzenedimethanol, 1,4-cyclohexanedimethanol and 4,4ʹ-biphenyldimethanol, with the aim of producing improved thermal properties. Copolyesters composed of Me-MeDVA together with aliphatic linear diols and cyclic diols were also synthesized. The weight average molecular weights of the resulting polyesters ranged from 1.5 to 11.0 × 104 g/mol and all were thermally stable. Glass transition temperatures varied from 58 to 134 °C. A semi-crystalline polyester with a high melting point of 220 °C was obtained from Me-MeDVA and trans-1,4-cyclohexanedimethanol, and was assessed using polarized optical microscopy and one-dimensional wide-angle X-ray diffraction. Self-standing films of several high molecular weight polyesters were prepared and their mechanical properties assessed.
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•A series of symmetrical methylated dialkoxydivanillic acid (DVA) monomers with varied side-chain lengths were synthesized.•Homo- and copolyesters composed of DVA monomers and cyclic diols (and aliphatic diols for copolyesters) were synthesized.•A semi-crystalline DVA polyester with a melting point of 220 °C was first obtained.•Cast or thermopressing films of DVA polyesters were prepared and their mechanical properties assessed.
Sodium-glucose transporter 2 (SGLT2) inhibitors are antidiabetic drugs affecting SGLT2. Recent studies have shown various cancers expressing SGLT2, and SGLT2 inhibitors attenuating tumor ...proliferation. We evaluated the antitumor activities of canagliflozin, a SGLT2 inhibitor, on glioblastoma (GBM). Three GBM cell lines, U251MG (human), U87MG (human), and GL261 (murine), were used. We assessed the expression of SGLT2 of GBM through immunoblotting, specimen-use, cell viability assays, and glucose uptake assay with canagliflozin. Then, we assessed phosphorylation of AMP-activated protein kinase (AMPK), p70 S6 kinase, and S6 ribosomal protein by immunoblotting. Concentrations of 5, 10, 20, and 40 μM canagliflozin were used in these tests. We also evaluated cell viability and immunoblotting using U251MG with siRNA knockdown of SGLT2. Furthermore, we divided the mice into vehicle group and canagliflozin group. The canagliflozin group was administrated with 100 mg/kg of canagliflozin orally for 10 days starting from the third days post-GBM transplant. The brains were removed and the tumor volume was evaluated using sections. SGLT2 was expressed in GBM cell and GBM allograft mouse. Canagliflozin administration at 40 μM significantly inhibited cell proliferation and glucose uptake into the cell. Additionally, canagliflozin at 40 μM significantly increased the phosphorylation of AMPK and suppressed that of p70 S6 kinase and S6 ribosomal protein. Similar results of cell viability assays and immunoblotting were obtained using siRNA SGLT2. Furthermore, although less effective than in vitro, the canagliflozin group significantly suppressed tumor growth in GBM-transplanted mice. This suggests that canagliflozin can be used as a potential treatment for GBM.
Paramylon, which is a β-(1,3)-D-glucan photosynthesized by Euglena, was chemically modified by esterification. Various paramylon triesters with different alkyl chain lengths (carbon numbers 2–12) ...were successfully prepared. All of the paramylon triesters have higher thermal degradation temperatures than that of neat paramylon. Moreover, it was found that the paramylon triesters with C2–C6 alkyl chains are crystalline polymers with melting temperatures from 281 °C to 114 °C, and those with C8–C12 alkyl chains are amorphous polymers, confirmed by both DSC and X-ray diffraction analysis. Paramylon triesters with C3–C12 alkyl chains could shape self-sustaining films by both solvent-casting and melt-quench methods with high optical transmittance and sufficient tensile strength or elongation at break. Thermal and mechanical properties of paramylon triesters can be controlled freely from hard to soft by substituted acyl length. In the cases of the crystalline paramylon triesters, highly oriented and crystallized films could be fabricated by the thermally stretched method, and their tensile strengths have been obviously improved. Well-oriented X-ray fiber diagrams of the stretched and crystallized films suggest that all of the paramylon triesters have rare 5-fold helix conformation of molecular chains in crystal.
Aims: We aimed to determine the association between acute platelet reactivity and clinical outcome in acute ischemic stroke (AIS) or transient ischemic attack (TIA) with large-artery atherosclerosis ...(LAA).Methods: In this prospective, 16-multicenter study, we enrolled AIS/TIA patients with LAA receiving clopidogrel. We assessed the association of P2Y12 reaction units (PRU) 24 hours after initiation of antiplatelets with the CYP2C19 genotype and recurrent ischemic stroke within 90 days, and the difference between acute (≤ 7 days) and subacute (8–90 days) phases.Results: Among the 230 AIS/TIA patients enrolled, 225 with complete outcome data and 194 with genetic results were analyzed. A higher PRU was significantly associated with recurrent ischemic stroke within 90 days (frequency, 16%), and within 7 days (10%). Twenty-nine patients (15%) belonged to a CYP2C19 poor metabolizer group (CYP2C19＊2/＊2, ＊2/＊3, or ＊3/＊3). Multivariable receiver-operating characteristic analysis showed a greater area-under-the-curve (AUC) in predicting recurrence within 7 days, compared to 8–90 days (AUC, 0.79 versus 0.64; p=0.07), with a cut-off PRU of 254. Multivariable analysis showed high PRU (≥ 254), which had a comparable predictive performance for recurrent ischemic stroke within 7 days (odds ratio, 6.82; 95% CI, 2.23–20.9; p＜0.001) to the CYP2C19 poor metabolizer genotype. The net reclassification improvement, calculated by adding high PRU (≥ 254) to a model including the CYP2C19 poor metabolizer genotype in the prediction of recurrence within 7 days, was 0.83 (p＜0.001).Conclusions: Acute PRU evaluation possesses predictive value for recurrent ischemic stroke, especially within 7 days in AIS/TIA with LAA.
Polysaccharides are promising renewable alternatives to petroleum-based plastics, and are high-value-added materials in various industries. In this work, we synthesized dextran (α-1,6-glucan) ester ...derivatives substituting acyl groups with different carbon numbers from acetate to laurate. We found that the thermal stability of dextran was improved by esterification. Moreover, using differential scanning calorimetry and X-ray diffraction, we revealed that dextran ester derivatives were amorphous. Self-standing, transparent, solvent-cast films of dextran ester derivatives were prepared. Dextran ester derivatives adhered to various materials, including polyvinyl alcohol (PVA) films, wood, glass, and aluminum. In addition, the adhesive interfaces were transparent, which is important for practical applications. The adhesive strength for PVA films increased with concentration, exceeding the breaking strength of the PVA film at 0.3 g/mL. Moreover, dextran valerate and dextran hexanoate behaved as hot-melt-type adhesives. These results demonstrate the potential of dextran ester derivatives as biomass-based adhesives.
This study aimed to evaluate the effects of nafamostat, a serin protease inhibitor, in the management of subarachnoid hemorrhage (SAH). SAH was induced by endovascular perforation in male mice. ...Nafamostat was administered intraperitoneally four times immediately after SAH induction. Cerebral blood flow, neurological behavior tests, SAH grade and protein expression were evaluated at 24 h after SAH induction. In the in vitro model, human brain microvascular endothelial cells (HBMVECs), HBVECs were exposed to thrombin and hypoxia for 24 h; nafamostat was administered and the protein expression was evaluated.
Eighty-eight mice were included in the in vivo study. Fifteen mice (17%) were excluded because of death or procedure failure. Nafamostat exerted no significant effect on the SAH grade or cerebral blood flow; however, it improved the neurological behavior and suppressed the thrombin and MMP-9 expression. In addition, nafamostat suppressed the ICAM-1 expression and p38 phosphorylation in the in vitro study.
Nafamostat has a protective effect against HBMVEC after exposure to thrombin and hypoxia, suggesting its role in improving the neurological outcomes after SAH. These findings indicate that nafamostat has the potential to be a novel therapeutic drug in the management of SAH.
Objective: This study aimed to determine the status of perioperative antiplatelet therapy in stent-assisted coil embolization (SAC) in Japan.Methods: The questionnaire consisted of 13 questions and ...used Google forms, and was sent to institutions where endovascular specialists were employed. The results were analyzed.Results: The responses from 307 centers indicated that the timing of initiation of antiplatelet therapy was 14 days–1 month before treatment in half of centers, and 7–14 days before treatment in the other half. Platelet function tests were performed at 165 centers (56.2%), of which 136 centers (46.3%) performed these tests for all patients, with the VerifyNow system being the most widely used tool. The duration of postoperative dual antiplatelet therapy was 6, 3, and 12 months in 169 (57.7%), 70 (23.5%), and 42 (14.3%) centers, respectively. The antiplatelet agents used for monotherapy were P2Y12 receptor antagonists or aspirin, with a postoperative period of up to 12 months in 139 centers (47.3%), 24 months in 68 centers (23.1%), and longer than 24 months in 50 centers (17%).Conclusion: Current antiplatelet therapy for SAC in Japan varies widely among institutions. Moreover, each center has its own empirical rules for SAC. Therefore, the findings of this survey suggest the need to establish guidelines for optimal periprocedural antiplatelet therapy for SAC.
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