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41.
Su-Mi Woo Hae-Soon Lim Kyung-Yi Jeong Seon-Mi Kim Won-Jae Kim Ji-Yeon Jung 《Molecules and cells》2015,38(7):604-609
The active metabolite of vitamin D such as 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3) is a well-known key regulatory factor in bone metabolism. However, little is known about the potential of vitamin D as an odontogenic inducer in human dental pulp cells (HDPCs) in vitro. The purpose of this study was to evaluate the effect of vitamin D3 metabolite, 1α,25(OH)2D3, on odontoblastic differentiation in HDPCs. HDPCs extracted from maxillary supernumerary incisors and third molars were directly cultured with 1α,25(OH)2D3 in the absence of differentiation-inducing factors. Treatment of HDPCs with 1α,25(OH)2D3 at a concentration of 10 nM or 100 nM significantly upregulated the expression of dentin sialophosphoprotein (DSPP) and dentin matrix protein1 (DMP1), the odontogenesis-related genes. Also, 1α,25(OH)2D3 enhanced the alkaline phosphatase (ALP) activity and mineralization in HDPCs. In addition, 1α,25(OH)2D3 induced activation of extracellular signal-regulated kinases (ERKs), whereas the ERK inhibitor U0126 ameliorated the upregulation of DSPP and DMP1 and reduced the mineralization enhanced by 1α,25(OH)2D3. These results demonstrated that 1α,25(OH)2D3 promoted odontoblastic differentiation of HDPCs via modulating ERK activation. 相似文献
42.
Rhabdomyolysis-induced renal failure represents up to 15% of all cases of acute renal failure. Many studies over the past 4 decades have demonstrated that accumulation of myoglobin in the kidney is central in the mechanism leading to kidney injury. However, some discussion exists regarding the mechanism mediating this oxidant injury. Although the free-iron-catalyzed Fenton reaction has been proposed to explain the tissue injury, more recent evidence strongly suggests that the main cause of oxidant injury is myoglobin redox cycling and generation of oxidized lipids. These molecules can propagate tissue injury and cause renal vasoconstriction, two of the three main conditions associated with acute renal failure. This review presents the evidence supporting the two mechanisms of oxidative injury, describes the central role of myoglobin redox cycling in the pathology of renal failure associated with rhabdomyolysis, and discusses the value of therapeutic interventions aiming at inhibiting myoglobin redox cycling for the treatment of rhabdomyolysis-induced renal failure. 相似文献
43.
Arsenic-induced oxidative stress and its reversibility 总被引:2,自引:0,他引:2
Flora SJ 《Free radical biology & medicine》2011,51(2):257-281
44.
M.?Bertamini K.?Muthuchelian M.?Rubinigg R.?Zorer N.?NedunchezhianEmail author 《Photosynthetica》2005,43(4):551-557
Photoinhibition of photosynthesis was investigated in control (C) and chilling night (CN) leaves of grapevine under natural
photoperiod at different sampling time in a day. The degree of photoinhibition was determined by means of the ratio of variable
to maximum chlorophyll fluorescence (Fv/Fm) and photosynthetic electron transport measurements. When the potential efficiency of photosystem (PS) 2, Fv/Fm was measured at midday, it markedly declined with significant increase of F0 in CN leaves. In isolated thylakoids, the rate of whole chain and PS2 activity were markedly decreased in CN leaves than
control leaves at midday. A smaller inhibition of PS1 activity was also observed in both leaf types. Later, the leaves reached
maximum PS2 efficiencies similar to those observed in the morning during sampling at evening. The artificial exogenous electron
donors diphenyl carbazide, NH2OH, and Mn2+ failed to restore the PS2 activity in both leaf types at midday. Thus CN enhanced inactivation on the acceptor side of PS2
in grapevine leaves. Quantification of the PS2 reaction centre protein D1 following midday exposure of leaves showed pronounced
differences between C and CN leaves. The marked loss of PS2 activity in CN leaves noticed in midday samples was mainly due
to the marked loss of D1 protein of the PS2 reaction centre. 相似文献
45.
A Comparison of Bone Mineral Density and Its Predictors in HIV-Infected and HIV-Uninfected Older Men
《Endocrine practice》2021,27(12):1225-1231
ObjectiveBone health in older individuals with HIV infection has not been well studied. This study aimed to compare bone mineral density (BMD), trabecular bone score (TBS), and bone markers between HIV-infected men and age- and body mass index (BMI)-matched HIV-uninfected men aged ≥60 years. We investigated the associations of risk factors related to fracture with BMD, TBS, and bone markers in HIV-infected men.MethodsThis cross-sectional study included 45 HIV-infected men receiving antiretroviral therapy and 42 HIV-uninfected men. Medical history, BMD and TBS measurements, and laboratory tests related to bone health were assessed in all the participants. HIV-related factors known to be associated with bone loss were assessed in the HIV-infected men.ResultsThe mean BMD, TBS, and osteopenia or osteoporosis prevalence were similar among the cases and controls. The HIV-infected men had significantly higher mean N-terminal propeptide of type 1 procollagen and C-terminal cross-linking telopeptide of type I collagen levels. Stepwise multiple linear regression analysis demonstrated that low BMI (lumbar spine, P = .015; femoral neck, P = .018; and total hip, P = .005), high C-terminal cross-linking telopeptide of type I collagen concentration (total hip, P = .042; and TBS, P = .010), and low vitamin D supplementation (TBS, P = .035) were independently associated with low BMD and TBS.ConclusionIn older HIV-infected men with a low fracture risk, the mean BMD and TBS were similar to those of the age- and BMI-matched controls. The mean bone marker levels were higher in the HIV group. Traditional risk factors for fracture, including low BMI, high C-terminal cross-linking telopeptide of type I collagen level, and low vitamin D supplementation, were significant predictors of low BMD and TBS. 相似文献
46.
Structure-functional characterization of vitamin D receptor (VDR) requires identification of structurally distinct areas of VDR-ligand-binding domain (VDR-LBD) important for biological properties of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3). We hypothesized that covalent attachment of the ligand into VDR-LBD might alter ‘surface structure’ of that area influencing biological activity of the ligand. We compared anti-proliferative activity of three affinity alkylating derivatives of 1,25(OH)2D3 containing an alkylating probe at 1,3 and 11 positions. These compounds possessed high-affinity binding for VDR; and affinity labeled VDR-LBD. But, only the analog with probe at 3-position significantly altered growth in keratinocytes, compared with 1,25(OH)2D3. Molecular models of these analogs, docked inside VDR-LBD tentatively identified Ser237 (helix-3: 1,25(OH)2D3-1-BE), Cys288 (β-hairpin region: 1,25(OH)2D3-3-BE,) and Tyr295 (helix-6: 1,25(OH)2D3-11-BE,) as amino acids that are potentially modified by these reagents. Therefore, we conclude that the β-hairpin region (modified by 1,25(OH)2D3-3-BE) is most important for growth inhibition by 1,25(OH)2D3, while helices 3 and 6 are less important for such activity. 相似文献
47.
Effects of coumarin and 7OH-coumarin on bcl-2 and Bax expression in two human lung cancer cell lines in vitro 总被引:1,自引:0,他引:1
Coumarin and its derivative 7-hydroxycoumarin (7-OHC) have antitumor and antimetastatic properties. The purpose of this study was to investigate the possible effects of these compounds on expression of the bcl-2 and Bax oncoproteins in two human lung cancer cell lines, A427 and Calu-1. The cells were cultured in vitro for 24 h in RPMI 1640 with 1.5% (v/v) ethanol, 1.0 mM ethanolic coumarin or 1.0 mM ethanolic 7-OHC. Viability was determined in each cell line by an MTT assay. Total protein was extracted from cell lysates and the bcl-2 and Bax oncoproteins were identified. Western blotting showed a decrease in bcl-2 and an increase in Bax in A427 cells cultured with coumarin or 7-OHC. Neither drug changed bcl-2 expression in Calu-1 cells compared to solvent controls, and Bax expression was only slightly increased by coumarin. We conclude that 7-OHC is a more potent inhibitor of cell proliferation than coumarin and has more marked effects on oncoprotein expression. Also, the A427 cell line was more sensitive to the drugs than Calu-1. 相似文献
48.
Bradley B. Stocks 《Journal of molecular biology》2010,398(2):362-158
The current work employs a novel approach for characterizing structural changes during the refolding of acid-denatured cytochrome c (cyt c). At various time points (ranging from 10 ms to 5 min) after a pH jump from 2 to 7, the protein is exposed to a microsecond hydroxyl radical (·OH) pulse that induces oxidative labeling of solvent-exposed side chains. Most of the covalent modifications appear as + 16-Da adducts that are readily detectable by mass spectrometry. The overall extent of labeling decreases as folding proceeds, reflecting dramatic changes in the accessibility of numerous residues. Peptide mapping and tandem mass spectrometry reveal that the side chains of C14, C17, H33, F46, Y48, W59, M65, Y67, Y74, M80, I81, and Y97 are among the dominant sites of oxidation. Temporal changes in the accessibility of these residues are consistent with docking of the N- and C-terminal helices as early as 10 ms. However, structural reorganization at the helix interface takes place up to at least 1 s. Initial misligation of the heme iron by H33 leads to distal crowding, giving rise to low solvent accessibility of the displaced (native) M80 ligand and the adjacent I81. W59 retains a surprisingly high level of accessibility long into the folding process, indicating the presence of packing defects in the hydrophobically collapsed core. Overall, the results of this work are consistent with previous hydrogen/deuterium exchange studies that proposed a foldon-mediated mechanism. The structural data obtained by ·OH labeling monitor the packing and burial of side chains, whereas hydrogen/deuterium exchange primarily monitors the formation of secondary structure elements. Hence, the two approaches yield complementary information. Considering the very short time scale of pulsed oxidative labeling, an extension of the approach used here to sub-millisecond folding studies should be feasible. 相似文献
49.
Andrew J. Annalora David B. Goodin Qinghai Zhang C. David Stout 《Journal of molecular biology》2010,396(2):441-451
Cytochrome P450 (CYP) 24A1 catalyzes the side-chain oxidation of the hormonal form of vitamin D. Expression of CYP24A1 is up-regulated to attenuate vitamin D signaling associated with calcium homeostasis and cellular growth processes. The development of therapeutics for disorders linked to vitamin D insufficiency would be greatly facilitated by structural knowledge of CYP24A1. Here, we report the crystal structure of rat CYP24A1 at 2.5 Å resolution. The structure exhibits an open cleft leading to the active-site heme prosthetic group on the distal surface that is likely to define the path of substrate access into the active site. The entrance to the cleft is flanked by conserved hydrophobic residues on helices A′ and G′, suggesting a mode of insertion into the inner mitochondrial membrane. A docking model for 1α,25-dihydroxyvitamin D3 binding in the open form of CYP24A1 that clarifies the structural determinants of secosteroid recognition and validates the predictive power of existing homology models of CYP24A1 is proposed. Analysis of CYP24A1's proximal surface identifies the determinants of adrenodoxin recognition as a constellation of conserved residues from helices K, K″, and L that converge with an adjacent lysine-rich loop for binding the redox protein. Overall, the CYP24A1 structure provides the first template for understanding membrane insertion, substrate binding, and redox partner interaction in mitochondrial P450s. 相似文献
50.
Shade effect alters leaf pigments and photosynthetic responses in Norway spruce (Picea abies L.) grown under field conditions 总被引:1,自引:0,他引:1
The contents of chlorophyll (Chl) and carotenoids (Car) per fresh mass were lower in shade needles than in sun needles. Ribulose-1,5-bisphosphate
carboxylase (RuBPC) activity and contents of soluble proteins were also significantly lower in shade needles. In isolated
thylakoids, a marked lower rate of whole chain and photosystem (PS) 2 activities were observed in shade needles. Smaller lower
rate of PS1 activity was also observed in shade needles. The artificial exogenous electron donors, diphenyl carbazide (DPC)
and NH2OH, significantly restored the loss of PS2 activity in shade needles. Similar results were obtained when Fv/Fm was evaluated by Chl fluorescence measurements. The marked lower rate of PS2 activity in shade needles was due to the lower
contents of 47, 33, 28–25, 23, and 17 kDa polypeptides. This conclusion was confirmed by immunological studies showing that
the content of the 33 kDa protein of the watersplitting complex was diminished significantly in shade needles. 相似文献