Termination of Living Anionic Polymerization of Butyl Acrylate with α‐(Chloromethyl)acrylate for End‐Functionalization and Application to the Evaluation of Monomer Reactivity

Anionic polymerization of n‐butyl acrylate (nBA) in toluene initiated with a binary initiator, isopropyl α‐lithioisobutyrate/ethylaluminum bis(2,6‐di‐tert‐butylphenoxide) at ?60 °C, is terminated with ethyl α‐(chloromethyl)acrylate (ECMA) to afford a poly(nBA) possessing an acryloyl group at the terminal with 80% of termination efficiency. The reactivity of nBA against a polymer anion of methyl methacrylate formed under identical conditions is estimated relative to the termination with ECMA by reacting a mixture of nBA and ECMA followed by ¹H NMR spectroscopic chain‐end analysis; the relative reactivity of nBA is found 80 times or more higher than ECMA.

     

Feasibility of structural modification of retinoid X receptor agonists to separate blood glucose-lowering action from adverse effects: studies in KKA(y) type 2 diabetes model mice

Retinoid X receptor (RXR) agonists are reported to exhibit blood glucose-lowering action owing to peroxisome proliferator-activated receptor (PPAR)/RXR or liver X receptor (LXR)/RXR activation, but may also cause adverse effects such as blood triglyceride elevation. In order to examine the feasibility of separating the glucose-lowering action from the adverse effects, we examined the effects of RXR agonists (NEt-TMN), NEt-3IB, and NEt-3IP, which have different heterodimer-activating patterns, in KKA(y) type 2 diabetes model mice. We found that NEt-3IB induced lower degrees of hepatomegaly and blood triglyceride (TG) elevation than the other RXR agonists, even though all of them showed similar blood glucose-lowering action on repeated administration. These findings indicate that structural modification of RXR agonists is a potentially effective strategy to reduce adverse effects while retaining desired activities.     

Creation of Fluorescent RXR Antagonists Based on CBTF-EE and Application to a Fluorescence Polarization Binding Assay

Retinoid X receptor (RXR) ligands often bind in modes in which the carboxy group forms a hydrogen bond inside the ligand-binding pocket (LBP). However, our previously reported RXR antagonist, CBTF-EE (4a), binds with its carboxy group directed outside the LBP and its alkoxy side chain located inside the LBP. Here, we examined the binding modes of 4b and 4c bearing a nitrobenzoxadiazole (NBD) or boron-dipyrromethene (BODIPY) fluorophore, respectively, at the end of the alkoxy chain of 4a. Both compounds function as RXR antagonists. 4c, but not 4b, was available for a fluorescence polarization binding assay, indicating that rotation of BODIPY, but not NBD, is restricted in the bound state. The fluorescence findings, supported by docking simulations, suggest the fluorophores are located outside the LBP, so that the binding mode of 4b and 4c is different from that of 4a. The assay results were highly correlated with those of a [³H]9-cis-retinoic acid assay.     

The ATP-hydrolyzing ectoenzyme E-NTPD8 attenuates colitis through modulation of P2X4 receptor–dependent metabolism in myeloid cells

Extracellular adenosine triphosphate (ATP) released by mucosal immune cells and by microbiota in the intestinal lumen elicits diverse immune responses that mediate the intestinal homeostasis via P2 purinergic receptors, while overactivation of ATP signaling leads to mucosal immune system disruption, which leads to pathogenesis of intestinal inflammation. In the small intestine, hydrolysis of luminal ATP by ectonucleoside triphosphate diphosphohydrolase (E-NTPD)7 in epithelial cells is essential for control of the number of T helper 17 (Th17) cells. However, the molecular mechanism by which microbiota-derived ATP in the colon is regulated remains poorly understood. Here, we show that E-NTPD8 is highly expressed in large-intestinal epithelial cells and hydrolyzes microbiota-derived luminal ATP. Compared with wild-type mice, Entpd8^−/− mice develop more severe dextran sodium sulfate–induced colitis, which can be ameliorated by either the depletion of neutrophils and monocytes by injecting with anti–Gr-1 antibody or the introduction of P2rx4 deficiency into hematopoietic cells. An increased level of luminal ATP in the colon of Entpd8^−/− mice promotes glycolysis in neutrophils through P2x4 receptor–dependent Ca²⁺ influx, which is linked to prolonged survival and elevated reactive oxygen species production in these cells. Thus, E-NTPD8 limits intestinal inflammation by controlling metabolic alteration toward glycolysis via the P2X4 receptor in myeloid cells.

The intestinal microbiota contribute to reinforcing epithelial integrity and shaping the immune system via metabolically derived signaling molecules (1–3). However, alterations in microbial metabolites and their translocation following intestinal dysbiosis are implicated in the pathogenesis of chronic disorders, such as inflammatory bowel diseases (IBD) including Crohn’s disease (CD) and ulcerative colitis (UC) (4, 5). Extracellular adenosine triphosphate (ATP) is released by microbes and immune cells in the intestine (6–8) and drives immune responses through the P2X_1-7 and P2Y_{1, 2, 11} receptors (9). To avoid inappropriate immune reactions in the intestine, luminal ATP is strictly controlled by epithelial ATP-hydrolyzing ectoenzymes, such as ectonucleotide pyrophosphatase/phosphodiesterases (E-NPPs) and ectonucleoside triphosphate diphosphohydrolases (E-NTPDases). E-NPP3 on the epithelial cells depresses the apoptosis of plasmacytoid dendritic cells (DCs) in the small intestine and Peyer’s patches (10). In addition, E-NTPD7 in small-intestinal epithelial cells hydrolyzes luminal ATP, thus inhibiting excessive T helper 17 (Th17) responses (11). However, how the concentration of luminal ATP produced by commensal bacteria is regulated in the large intestine remains undetermined.Although intestinal phagocytes such as monocytes, macrophages (Mϕ), DCs, and neutrophils have some protective effects, these cells can also function in pathological conditions (12–14). In patients with IBD, inflamed sites of the intestinal mucosa have more inflammatory DCs and Mϕ, many of which are dysfunctional (15). In addition, an enhanced neutrophil accumulation in the intestinal mucosa of UC patients correlates with disease severity (16–18). Accordingly, experimental murine colitis can be abrogated by inhibiting the recruitment of monocytes and neutrophils to the intestinal lamina propria by using anti-CCR2 (19) or -Gr-1 (20–22) antibody or by the targeted deletion of CCR2 (23) or β7-integrin (24). Thus, the number of intestinal phagocytes and their physiological functions must be tightly tuned to prevent the intestinal inflammation. However, the mechanisms by which the activity of monocytes and neutrophils that have infiltrated into the intestinal mucosa are regulated remain poorly understood.Different immune cell populations have distinct nutrient utilizations and cellular metabolisms (25), which are involved in their differentiation, proliferation, functions, longevity, and epigenetic modification (25–27). Microbial components and metabolites, such as lipopolysaccharide (28) and short chain fatty acids (29), can switch to glycolysis in monocytes and T cells, respectively. The small molecule dimethyl fumarate (DMF), which suppresses glycolysis in lymphocytes and myeloid cells (30), abrogates chemically induced colitis in mice (31, 32), which indicates that inadequate glycolysis activation is involved in the pathogenesis of intestinal inflammation. However, the mechanism underlying the adaptation of intestinal myeloid cells to environmental factors that fuel glycolysis is unclear.In this study, we investigated the immunomodulatory function of ATP-hydrolyzing ectoenzyme E-NTPD8 in maintenance of the gut homeostasis. Mice with Entpd8 deficiency had an increased concentration of luminal ATP in their colons, which led to the prolonged survival of neutrophils owing to the facilitation of glycolysis by the P2X4 receptor (P2X4R), thereby exacerbating dextran sodium sulfate (DSS)-induced colitis. Therefore, the clearance of extracellular ATP by E-NTPD8 is essential for the prevention of innate intestinal pathology by inhibiting a metabolic alteration toward glycolysis in myeloid cells.     

Monte Carlo calculation of patient organ doses from computed tomography

In this study, we aimed to evaluate quantitatively the patient organ dose from computed tomography (CT) using Monte Carlo calculations. A multidetector CT unit (Aquilion 16, TOSHIBA Medical Systems) was modeled with the GMctdospp (IMPS, Germany) software based on the EGSnrc Monte Carlo code. The X-ray spectrum and the configuration of the bowtie filter for the Monte Carlo modeling were determined from the chamber measurements for the half-value layer (HVL) of aluminum and the dose profile (off-center ratio, OCR) in air. The calculated HVL and OCR were compared with measured values for body irradiation with 120 kVp. The Monte Carlo-calculated patient dose distribution was converted to the absorbed dose measured by a Farmer chamber with a ⁶⁰Co calibration factor at the center of a CT water phantom. The patient dose was evaluated from dose-volume histograms for the internal organs in the pelvis. The calculated Al HVL was in agreement within 0.3 % with the measured value of 5.2 mm. The calculated dose profile in air matched the measured value within 5 % in a range of 15 cm from the central axis. The mean doses for soft tissues were 23.5, 23.8, and 27.9 mGy for the prostate, rectum, and bladder, respectively, under exposure conditions of 120 kVp, 200 mA, a beam pitch of 0.938, and beam collimation of 32 mm. For bones of the femur and pelvis, the mean doses were 56.1 and 63.6 mGy, respectively. The doses for bone increased by up to 2–3 times that of soft tissue, corresponding to the ratio of their mass-energy absorption coefficients.     

Modification at the Lipophilic Domain of RXR Agonists Differentially Influences Activation of RXR Heterodimers

相似文献   

Particle-Based Numerical Simulation Study of Solid Particle Erosion of Ductile Materials Leading to an Erosion Model,Including the Particle Shape Effect

Solid particle erosion inevitably occurs if a gas–solid or liquid–solid mixture is in contact with a surface, e.g., in pneumatic conveyors. Having a good understanding of this complex phenomenon enables one to reduce the maintenance costs in several industrial applications by designing components that have longer lifetimes. In this paper, we propose a methodology to numerically investigate erosion behavior of ductile materials. We employ smoothed particle hydrodynamics that can easily deal with large deformations and fractures as a truly meshless method. In addition, a new contact model was developed in order to robustly handle contacts around sharp corners of the solid particles. The numerical predictions of erosion are compared with experiments for stainless steel AISI 304, showing that we are able to properly predict the erosion behavior as a function of impact angle. We present a powerful tool to conveniently study the effect of important parameters, such as solid particle shapes, which are not simple to study in experiments. Using the methodology, we study the effect of a solid particle shape and conclude that, in addition to angularity, aspect ratio also plays an important role by increasing the probability of the solid particles to rotate after impact. Finally, we are able to extend a widely used erosion model by a term that considers a solid particle shape.     

Improving function of cytotoxic T‐lymphocytes by transforming growth factor‐β inhibitor in oral squamous cell carcinoma

Immunotherapy with immune‐checkpoint therapy has recently been used to treat oral squamous cell carcinomas (OSCCs). However, improvements in current immunotherapy are expected because response rates are limited. Transforming growth factor‐β (TGF‐β) creates an immunosuppressive tumor microenvironment (TME) by inducing the production of regulatory T‐cells (Tregs) and cancer‐associated fibroblasts and inhibiting the function of cytotoxic T‐lymphocytes (CTLs) and natural killer cells. TGF‐β may be an important target in the development of novel cancer immunotherapies. In this study, we investigated the suppressive effect of TGF‐β on CTL function in vitro using OSCC cell lines and their specific CTLs. Moreover, TGFB1 mRNA expression and T‐cell infiltration in 25 OSCC tissues were examined by in situ hybridization and multifluorescence immunohistochemistry. We found that TGF‐β suppressed the function of antigen‐specific CTLs in the priming and effector phases in vitro. Additionally, TGF‐β inhibitor effectively restored the CTL function, and TGFB1 mRNA was primarily expressed in the tumor invasive front. Interestingly, we found a significant negative correlation between TGFB1 mRNA expression and the CD8⁺ T‐cell/Treg ratio and between TGFB1 mRNA expression and the Ki‐67 expression in CD8⁺ T‐cells, indicating that TGF‐β also suppressed the function of CTLs in situ. Our findings suggest that the regulation of TGF‐β function restores the immunosuppressive TME to active status and is important for developing new immunotherapeutic strategies, such as a combination of immune‐checkpoint inhibitors and TGF‐β inhibitors, for OSCCs.