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991.
Objective: Retinol binding protein‐4 (RBP4) has been reported to impair insulin sensitivity throughout the body. We investigated the relationship between serum RBP4 levels and adiposity indices as well as metabolic risk variables. Research Methods and Procedure: We recruited a total of 102 healthy women 21 to 67 years old. We assessed body composition by computed tomography and divided the study population into four groups based on body weight and visceral fat area (non‐obese without visceral adiposity, non‐obese with visceral adiposity, obese without visceral adiposity, and obese with visceral adiposity). Serum RBP4 levels were measured by radioimmunoassay. Results: Despite similar levels of total body fat, non‐obese women had lower systolic blood pressure, total cholesterol, triglyceride (TG), low‐density lipoprotein (LDL)‐cholesterol levels, insulin resistance indices, and RBP4 levels than non‐obese women with visceral adiposity and had higher high‐density lipoprotein‐cholesterol levels. Similarly, obese women without visceral adiposity had lower blood pressure, total cholesterol, TG levels, insulin resistance indices, and RBP4 levels than obese women with visceral adiposity. In addition, despite having increased body fat, obese women without visceral adiposity had lower TGs, insulin resistance indices, and serum RBP4 levels than non‐obese women with visceral adiposity. By step‐wise multiple regression analysis, visceral fat areas and LDL‐cholesterol levels independently affected RBP4 levels. Discussion: We determined that serum RBP4 levels are independently associated with visceral fat and LDL‐cholesterol levels. These results suggest that, irrespective of body weight, visceral obesity is an independent predictor of serum RBP4 levels, and RBP4 may represent a link between visceral obesity and cardiovascular disease. 相似文献
992.
Yuno Do Jeong Bae Kim JeongHee Shim Chang‐Jun Kim Ohseok Kwon Moon Bo Choi 《Entomological Research》2019,49(10):456-461
We analyzed the research topics and public concern on Vespa velutina as an invasive species in Asian and European countries quantitatively though digitized texts such as scientometrics and conservation culturomics. We collected 126 scientific publications of V. velutina published during the last three decades, and 423 news articles on V. velutina in South Korea. In total, 22 countries have contributed to scientific research on V. velutina. Research topics were clearly classified to studies on taxonomy and invasion of V. velutina. In South Korea, people have recognized the ecological and health impact of V. velutina. Although scientific and public interest in V. velutina has increased since 2000, research topics may be narrow and information of news articles may be simple. To achieve the sustainable management of V. velutina, multilateral studies including environmental, social, and economic research on V. velutina are necessary. 相似文献
993.
Koji Inaba Toshiaki Nakashima Toshihide Shim Hironori Mitsuyoshi Yoshikuni Sakamoto Takeshi Okanoue Kei Klisfiima Mitsouki Hashiba Hiroyasu Nishikawa Hiroshi Watari 《Free radical research》1997,27(1):37-43
To determine the role of the liver in the elimination of free radicals from the body, the clearance rate (K) of nitroxide radicals (Tempol) at the hepatic domain was compared with that at the pelvic domain of live mice, using L-band ESR spectroscopy. The reduction of Ternpol in biopsy specimens (liver tissue and femoral muscle) and blood obtained from Tempol-treated mice was also monitored using X-band ESR spectroscopy. Results indicated that the reduction of nitroxide radicals was delayed in both the liver and peripheral tissues when the liver was damaged. The decrease in both blood supply and reductants in the damaged liver might be involved in delaying the reduction in the whole body, because the liver can reduce the radicals supplied via the blood from the peripheral tissues, and the reductants such as reduced glutathione in the peripheral tissues are supplied from the liver. 相似文献
994.
Genevieve Tan Winston Shim Yacui Gu Ling Qian Ying Ying Chung Sze Yun Lim Pearly Yong Eugene Sim Philip Wong 《Differentiation; research in biological diversity》2010,79(4-5):260-271
Dysregulation of matrix synthesis during myocardial fibrosis in post-infarct ventricular remodeling contributes to ventricular dysfunction. Bone marrow stem cell transplantation prevents functional deterioration following myocardial infarction. However, effect of myocardial extracellular matrix (ECM) on stem cell differentiation is poorly understood. We investigate the role of collagen matrices and integrin system in cardiac differentiation and engraftment of stem cells in infarcted myocardium. Sternum-derived bone marrow mesenchymal stem cells (MSCs) were differentiated into cardiomyocyte-like cells (CLCs). They were characterized using RT-PCR, immunofluorescence, flow cytometry and functional integrin neutralization assays. CLCs were injected into peri-infarct borders of injured myocardium of Wistar rats one week following left anterior descending (LAD) artery ligation. Cardiac function was analyzed via pressure-volume relationships. Cardiac differentiated CLCs displayed collagen V specificity, which was absent in undifferentiated MSCs. Collagen V, but not collagen I matrix, promoted attachment, proliferation and cardiac differentiation of CLCs. In contrast to β1, αv integrin contributed minimally in the attachment of CLCs on collagen matrices. However, inhibition of αvβ3, but not α2β1 integrin, selectively attenuated troponin T, sarcomeric α-actin and ryanodine 2 receptor gene expression in CLCs. Both MSC and CLC transplantation prevented chamber dilatation and improved contractile function. However, systolic activity in MSC transplanted animals was accompanied by heightened wall stress as demonstrated by elevated myocardial end-diastolic pressure and prolonged tissue relaxation time. Localization of CLCs in the vicinity of collagen V-expressing myofibers promoted their integration into cardiac syncytium. CLCs may facilitate hemodynamic recovery by preserving tissue elasticity in the peri-infarct borders that sustains contractile efficiency for functional recovery in an actively remodeling infarcted myocardium. 相似文献
995.
996.
Joong-Youn Shim 《Biophysical journal》2009,96(8):3251-3262
Brain cannabinoid (CB1) receptors are G-protein coupled receptors and belong to the rhodopsin-like subfamily. A homology model of the inactive state of the CB1 receptor was constructed using the x-ray structure of β2-adrenergic receptor (β2AR) as the template. We used 105 ns duration molecular-dynamics simulations of the CB1 receptor embedded in a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer to gain some insight into the structure and function of the CB1 receptor. As judged from the root mean-square deviations combined with the detailed structural analyses, the helical bundle of the CB1 receptor appears to be fully converged in 50 ns of the simulation. The results reveal that the helical bundle structure of the CB1 receptor maintains a topology quite similar to the x-ray structures of G-protein coupled receptors overall. It is also revealed that the CB1 receptor is stabilized by the formation of extensive, water-mediated H-bond networks, aromatic stacking interactions, and receptor-lipid interactions within the helical core region. It is likely that these interactions, which are often specific to functional motifs, including the S(N)LAxAD, D(E)RY, CWxP, and NPxxY motifs, are the molecular constraints imposed on the inactive state of the CB1 receptor. It appears that disruption of these specific interactions is necessary to release the molecular constraints to achieve a conformational change of the receptor suitable for G-protein activation. 相似文献
997.
Seung Namkoong Chun-Ki Kim Young-Lai Cho Ji-Hee Kim Hansoo Lee Kwon-Soo Ha Jongseon Choe Pyeung-Hyeun Kim Moo-Ho Won Young-Geun Kwon Eun Bo Shim Young-Myeong Kim 《Cellular signalling》2009,21(6):906-915
Forskolin, a potent activator of adenylyl cyclases, has been implicated in modulating angiogenesis, but the underlying mechanism has not been clearly elucidated. We investigated the signal mechanism by which forskolin regulates angiogenesis. Forskolin stimulated angiogenesis of human endothelial cells and in vivo neovascularization, which was accompanied by phosphorylation of CREB, ERK, Akt, and endothelial nitric oxide synthase (eNOS) as well as NO production and VEGF expression. Forskolin-induced CREB phosphorylation, VEGF promoter activity, and VEGF expression were blocked by the PKA inhibitor PKI. Moreover, phosphorylation of ERK by forskolin was inhibited by the MEK inhibitor PD98059, but not PKI. The forskolin-induced Akt/eNOS/NO pathway was completely inhibited by the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002, but not significantly suppressed by PKI. These inhibitors and a NOS inhibitor partially inhibited forskolin-induced angiogenesis. The exchange protein directly activated by cAMP (Epac) activator, 8CPT-2Me-cAMP, promoted the Akt/eNOS/NO pathway and ERK phosphorylation, but did not induce CREB phosphorylation and VEGF expression. The angiogenic effect of the Epac activator was diminished by the inhibition of PI3K and MEK, but not by the PKA inhibitor. Small interfering RNA-mediated knockdown of Epac1 suppressed forskolin-induced angiogenesis and phosphorylation of ERK, Akt, and eNOS, but not CREB phosphorylation and VEGF expression. These results suggest that forskolin stimulates angiogenesis through coordinated cross-talk between two distinct pathways, PKA-dependent VEGF expression and Epac-dependent ERK activation and PI3K/Akt/eNOS/NO signaling. 相似文献
998.
In semi-arid regions, where plants using both C3 and C4 photosynthetic pathways are common, the stable C isotope ratio (δ13C) of ecosystem respiration (δ13CR) is strongly variable seasonally and inter-annually. Improved understanding of physiological and environmental controls over
these variations will improve C cycle models that rely on the isotopic composition of atmospheric CO2. We hypothesized that timing of precipitation events and antecedent moisture interact with activity of C3 and C4 grasses to determine net ecosystem CO2 exchange (NEE) and δ13CR. Field measurements included CO2 and δ13C fluxes from the whole ecosystem and from patches of different plant communities, biomass and δ13C of plants and soils over the 2000 and 2001 growing seasons. NEE shifted from C source to sink in response to rainfall events,
but this shift occurred after a time lag of up to 2 weeks if a dry period preceded the rainfall. The seasonal average of δ13CR was higher in 2000 (−16‰) than 2001 (20‰), probably due to drier conditions during the 2000 growing season (79.7 mm of precipitation
from April up to and including July) than in 2001 (189 mm). During moist conditions, δ13C averaged −22‰ from C3 patches, −16‰ from C4 patches, and −19‰ from mixed C3 and C4 patches. However, during dry conditions the apparent spatial differences were not obvious, suggesting reduced autotrophic
activity in C4 grasses with shallow rooting depth, soon after the onset of dry conditions. Air and soil temperatures were negatively correlated
with δ13CR; vapor pressure deficit was a poor predictor of δ13CR, in contrast to more mesic ecosystems. Responses of respiration components to precipitation pulses were explained by differences
in soil moisture thresholds between C3 and C4 species. Stable isotopic composition of respiration in semi-arid ecosystems is more temporally and spatially variable than
in mesic ecosystems owing to dynamic aspects of pulse precipitation episodes and biological drivers. 相似文献
999.
1000.