Recently, environmental chemicals have appeared in daily human life, and these chemicals have been incidentally taken in by humans. The serum concentrations of some of these chemicals have been found ...to be associated with the onset and incidence rate of diabetes mellitus. It has been suggested that one of the environmental chemicals, bisphenol A (BPA), has hormone‐like activity. It has also been demonstrated that some hormones affect insulin resistance and fat distribution in the body. To study the effects of these environmental chemicals on glucose metabolism, the effect of BPA on glucose transport in mouse 3T3‐F442A adipocytes was investigated. The 3T3‐F442A adipocytes were incubated with various concentrations of BPA in a medium. Deoxyglucose uptake assay was performed with and without insulin. Immunoblot analysis was performed with a glucose transporter (GLUT) 4‐specific antibody and antiphosphotyrosine antibody. The BPA treatment enhanced basal and insulin‐stimulated glucose uptake, and caused an increased amount of GLUT4 protein. Thus, the enhanced glucose uptake resulting from the BPA treatment was at least partially due to the increased amount of GLUT4. Tyrosine phosphorylation of insulin receptor substrate‐1 with insulin stimulation was not significantly affected. In conclusion, it was demonstrated that BPA, one of the chemicals that we intake incidentally, affects the glucose transport in adipocytes, and also that the environmental chemicals may be identified as one of the environmental factors that affect diabetes and obesity.
British Journal of Pharmacology (2004) 141, 209–214. doi:10.1038/sj.bjp.0705520
The levator veli palatini (LVP) and superior pharyngeal constrictor muscles (PC) close the velopharynx. However, for the velopharyngeal movements to be understood in detail, each muscle contraction ...must be analyzed precisely. This study was performed to clarify the velopharyngeal movement which was induced by a single muscle contraction, LVP or PC. Using a nasopharyngeal fiberscope, we analyzed the velopharyngeal movement associated with the contraction of the LVP and PC muscles in mongrel dogs. To elicit the maximal contraction of each muscle, we applied repetitive electrical stimulation to each peripheral nerve efferent to the LVP or PC muscle. Stimulation with a frequency of 77 Hz and 83 Hz induced maximal tension in the LVP and PC muscles, respectively, in isometric contraction. In a second series of experiments, fiberscopic views of the velopharyngeal movements associated with each muscle's maximal contraction were recorded. The degree of closure was calculated at several sections. The LVP muscle pulled the caudal fourth of the soft palate, while the PC projected the posterior wall at the level of the caudal end of the soft palate. The PC muscle also projected the lateral wall of the velopharynx. The effect of LVP contraction on the lateral wall was very small. These results show that the velopharyngeal movement associated with LVP contraction is very different from that with PC contraction.
The effects of cacao liquor polyphenols (CLP) on the susceptibility of low-density lipoprotein (LDL) to oxidation in hypercholesterolemic rabbits were examined. Six Japanese white rabbits which had ...been fed a high cholesterol diet (HCD) for 3 weeks were fed HCD containing 1% CLP for the following 10 days. The susceptibility of LDL to oxidation induced by 2-2'-azobis (4-methoxy-2, 4-dimethylvaleronitrile) (V-70) was evaluated by measuring the production of conjugated dienes and thiobarbituric acid reactive substances (TBARS). The lag time was significantly prolonged from 37.7 min before intake of CLP to 42.9, 44.2 and 45.8 min after 4, 7 and 10 days of CLP intake. TBARS production after intake of CLP was also markedly reduced compared with the level before intake. There was no difference in plasma lipid concentrations comparing the levels before and after CLP intake. In conclusion, in hypercholesterolemic rabbits, orally administered CLP was absorbed and distributed to the blood, and the resistance of LDL to oxidation was thereby increased.
•The second magnetization peak (SMP) in La2−xSrxCuO4 single crystals disappears completely in the doping range of well developed static stripe order (x ∼ 1/8) when the external magnetic field is ...perpendicular to the stripe plane.•The SMP evolution with decreasing doping follows the instability of the Bragg vortex glass detected in small-angle neutron scattering experiments.•Our analysis supports the scenario in which the SMP is generated by the pinning-induced disordering of the Bragg vortex glass in the dynamic conditions of dc magnetic measurements.
The occurrence of a second magnetization peak (SMP) on the dc magnetization curves of superconducting single crystals with random quenched disorder in increasing external magnetic field H is quite common. Many models for this intriguing phenomenon have been proposed so far, but its origin is still under strong debate. Optimally doped and overdoped La2−xSrxCuO4 single crystals (x ≥ 0.15) exhibit an SMP over a large temperature interval, up to very close to the critical temperature. By decreasing doping, it was found that with H oriented along the c axis the SMP completely disappears in the doping domain of well developed static charge and spin stripes (x ∼ 1/8), reappearing for x ≤ 0.10. This behaviour follows the instability of the Bragg vortex glass generated by the static stripe order (as revealed by small-angle neutron scattering experiments), which is confirmed by our magnetization relaxation measurements. If H is along the (a, b) planes, the SMP is observed for all investigated specimens. The presented analysis supports the scenario in which the SMP is generated by the pinning-induced disordering of the low-field Bragg vortex glass in the dynamic conditions of dc magnetic measurements.
Ultra violet (UV) screens and preservatives are widely and increasingly used in cosmetics and pharmaceuticals. In the present study, we examined the estrogenicity of 4-methyl-benzylidene camphor ...(4-MBC), octyl-methoxycinnamate (OMC), and propyl paraben (
n-propyl-
p-hydroxy-benzoate; PP), among UV screens and preservatives, using male medaka (
Oryzias latipes), in regard to production of vitellogenin (VTG) and choriogenin (CHG) which are known to be estrogen-responsive gene products. First, using a VTG enzyme-linked immunosorbent assay (ELISA) system, we determined the increase in VTG plasma concentration in medaka due to exposure to 4-MBC, OMC, and PP, and compared this concentration to the non-treated control. Next, we found increases in mRNA expression levels of VTG subtypes VTG-1 and VTG-2, and CHG subtypes CHG-L and CHG-H, in liver due to exposure to 4-MBC, OMC, and PP compared to the non-treated control. In addition, we also found increased mRNA expression levels of estrogen receptor (ER) α, among sex hormone receptors in the liver, due to exposure to 4-MBC, OMC, and PP compared to the non-treated control. In this study, we showed that 4-MBC, OMC, and PP have estrogenic activity in fish.
A thiamin-binding protein (TBP) was isolated from maize (
Tripsacum zea) seeds. It was estimated to have a molecular mass of 96 kDa, and consist of two 46-kDa subunits. The protein contained a large ...amount of glutamine or glutamic acid (14.4 mol%) and glycine (10.6 mol%). The levels of methionine (0.1 mol%) and tryptophan (0.6 mol%) in the protein were low. The optimum pH for its thiamin-binding activity was 8.0. It bound free thiamin specifically, not thiamin phosphates. The apparent dissociation and maximum bound values for thiamin-binding were 0.42 μM and 22.2 nmol·mg
–1 protein, respectively. These properties of thiamin-binding protein from maize seeds were similar to those of the thiamin-binding protein from rice seeds, not from buckwheat, sesame, sunflower or spruce seeds. Also, the TBP from maize seeds had immunological homology with the TBP from rice seeds, but not the other plant seed TBPs. Further, it was accumulated only in the seeds in the same manner as TBP of rice seeds.
We report a new series of hepatitis C virus NS5B RNA polymerase inhibitors containing a conformationally constrained tetracyclic scaffold. SAR studies led to the identification of ...6,7-dihydro-5H-benzo5,61,4diazepino7,1-aindoles (19 and 20) bearing a basic pendent group with high biochemical and cellular potencies. These compounds displayed a very small shift in cellular potency when the replicon assay was performed in the presence of human serum albumin.
The cytoskeletal stress fiber structure plays essential roles in various kinds of cellular functions such as shape maintenance, active motility and mechanosensing, and its structure is dynamically ...reorganized under each functional process. In known reorganization mechanisms of the stress fibers, a change in its mechanical condition has been suggested as one of the key mediators that affect the reorganization process. Some experimental studies have clarified that tension release in the stress fibers induces fiber depolymerization that is considered to be the initial phase of the reorganization process. However, quantitative mechanical values such as strain or stress that induce depolymerization have still not been evaluated. This study is aimed at the quantitative evaluation of the mechanical value that induces stress fiber depolymerization, to gain a basic understanding of the reorganization phenomenon from a mechanical viewpoint. Osteoblastic cells (MC3T3-E1) were cultured on prestretched silicone rubber substrate. Compressive deformation was applied to the cells by uniaxially releasing the prestretched substrate strain and change in the stress fiber structure was observed. The results indicated that the compressive strain magnitude, not in the whole cell body but in the stress fiber itself, is important to induce disassembly of the stress fiber structure. The existence of a threshold strain magnitude for initiating fiber disassembly was also suggested; the threshold strain magnitude was evaluated as approximately −0.20.
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