共查询到20条相似文献，搜索用时 62 毫秒
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以淮山为试材,采用微波法提取其多糖,设计L9(34)正交实验考察提取时间、提取功率、料液比、提取次数对淮山多糖提取率的影响,并通过分光光度法考察其清除羟基自由基的能力。结果表明:淮山多糖的最佳提取工艺为提取时间为6min、提取功率为400W、料液比为1∶20g/mL、提取次数为3次。在此条件下,多糖的提取率最高,达6.32%,试验结果还表明淮山多糖具有较好的清除羟基自由基的能力,且其清除能力与多糖浓度有明显的量效关系。 相似文献
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杏鲍菇多糖抗氧化作用研究 总被引：1，自引：0，他引：1
采用恒温水浴振荡方法提取杏鲍菇水溶性粗多糖,再经分离纯化得固体杏鲍菇多糖.以对氧自由基的清除率为评价指标,采用邻苯三酚自氧化法和邻二氮菲-Fe2+-H2O2氧化法研究了杏鲍菇多糖对氧自由基的清除能力.结果表明:杏鲍菇多糖对羟自由基和超氧阴离子自由基均有清除作用.在一定的多糖浓度范围内随着多糖浓度的增加对羟自由基和超氧阴离子自由基的清除作用亦增强,并呈良好的线性关系;杏鲍菇多糖浓度在0.7 mg/mL对羟自由基的清除率可达98.65％,对超氧阴离子自由基的清除率可达37.66％. 相似文献
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以款冬叶片为试材,采用微波辅助法提取总黄酮,在单因素试验的基础上,采用正交实验法优化款冬叶片总黄酮提取工艺,同时以分光光度法测定提取物对1,1-二苯基-2-三硝基苯肼自由基(1,1-diphenyl-2-picrylhydrazyl,DPPH·)、羟基自由基(·OH)和超氧阴离子自由基(O-·2)的清除作用。结果表明:款冬叶片总黄酮最佳提取条件为乙醇体积分数70%,微波提取时间3 min,微波功率500 W,料液比1∶15 g·mL^-1,在该条件下,总黄酮的提取率为0.91%。款冬叶片总黄酮的质量浓度与抗氧化活性呈一定的线性关系,当总黄酮质量浓度为0.069 8 mg·mL^-1时,对DPPH·、·OH和O-·2的清除率分别达84.21%、84.10%和68.32%,表明款冬叶片具有良好的抗氧化能力,可作为天然的抗氧化剂进一步的开发和利用。 相似文献
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以双孢蘑菇为原料,用热水浸提双孢蘑菇多糖并研究其在抗衰老方面的功效;首先通过响应面试验对双孢蘑菇多糖的提取工艺进行优化,得到最佳提取条件,进一步将最佳提取条件下提取到的多糖进行浓缩、醇沉,冻干得到双孢蘑菇多糖干品,最后,测定双孢蘑菇多糖的抗氧化功效,包括对DPPH自由基、羟自由基以及超氧阴离子自由基的清除能力测定。结果表明:热水浸提双孢蘑菇多糖的最佳工艺条件是料液比为1∶50,温度为79.79℃,提取时间为2.6h,提取率可达到2.25%。得到的双孢蘑菇多糖干品为棕色粉末,易溶于温水,平均分子量为1.697×10^6(±1.992%)Da,并且双孢蘑菇多糖对DPPH自由基和羟自由基的清除效果存在一定的量效关系,其中对DPPH自由基的清除效果最好,当多糖浓度为2mg/mL时清除率达70%。 相似文献
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裂盖马鞍菌粗多糖清除自由基活性研究 总被引：2，自引：0，他引：2
采用热水浸提法提取裂盖马鞍菌(Helvella leucopus Pers.)子实体粗多糖,然后分别采用DPPH 法、水杨酸法、邻苯三酚自氧化法测定粗多糖清除二苯代苦味酰基自由基(DPPH·)、羟自由基(·OH)和超氧阴离子自由基(·O-2)的活性.结果表明,裂盖马鞍菌子实体水溶性粗多糖得率为21.92 mg/g(干重);在试验条件下,粗多糖对DPPH·、·OH和·O-2最高清除率分别为96.88%(5 mg/mL)、94.48%(10 mg/mL)和92.82%(10 mg/mL),对DPPH·、·OH和·O-2清除作用的EC50分别为0.68 mg/mL、0.85 mg/mL和0.59 mg/mL;裂盖马鞍菌子实体粗多糖具有一定的体外抗氧化活性. 相似文献
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以秦巴山区野生槐花为试材,以pH 6.0柠檬酸盐酸性缓冲溶液作为浸提溶剂,采用单因素试验结合正交实验方法研究了纤维素酶-超声辅助提取槐花多糖的工艺条件,并考察其对羟基自由基、超氧阴离子自由基和ABTS自由基正离子的清除活性及还原能力。结果表明:槐花多糖的最佳提取工艺为提取温度60℃、提取时间20min、料液比1∶25kg·L~(-1)、纤维素酶10mg·g~(-1),该条件下槐花多糖的提取率为17.1%,槐花多糖对ABTS自由基正离子、羟基自由基和超氧阴离子自由基的清除IC_(50)值为0.047、0.75、0.87g·L~(-1),优于同浓度条件下天然抗氧化剂维生素C。 相似文献
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AIM: Although endovascular radiotherapy inhibits neointimal hyperplasia, the exact alterations induced by β-particles irradiation remain to be elucidated. The objective of this study was to investigate the ability and the cellular mechanism of local β-particles emission from 188Re to inhibit vascular smooth muscle cells (SMCs). METHODS: The SMCs in vitro were irradiated by 188Re with single doses of 2.6 Gy-25.8 Gy. The effects of β-particles on SMCs, such as effective irradiate doses, the period of inhibition for SMCs proliferation, the changes of cell proliferation rate and DNA synthesis rate, cell cycle progression and related gene expression, were investigated by cell count, [3H]-TdR incorporation, cell cycle progression analysis, cell viability and immunocytochemistry, respectivecy. RESULTS: β-particles irradiation with dose of 5.2 Gy could inhibit significantly SMCs proliferation. At dose of 20.6 Gy DNA synthesis inhibitory rate was 92%, SMCs proliferation rate was only 3%. Renoval of 188Re did not abolish the inhibitory effects of β-particles on SMCs proliferation. The expression of P53 was up regulation and PCNA was down regulation after irradiation. CONCLUSION: β-particles from 188 Re was significantly effective and permanent in inhibiting SMCs proliferation, and inhibitory effect was in dose-dependet manner ED50was 5 Gy, the best dose to inhibit SMCs proliferation was 20 Gy. β-particles irradiation induced SMCs to occur G0/G1 arrest, damaged the ability of SMCs reproliferation and led to cell clonogenic death. P53 and PCNA had regulatiory effects on SMCs proliferation after β-particles irradiation. 相似文献
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多效唑对猕猴桃离体试管苗生长及内源激素的影响 总被引：18，自引：0，他引：18
多效唑（ＰＰ３３３）处理猕猴桃试管苗，降低了其生长强度；植株体内的ＧＡ３、ＩＡＡ和ＺＴ含量下降，ＡＢＡ的含量上升，乙烯释放率增加；并且能降低外源的ＧＡ３和ＩＡＡ促进生长的作用，而外源的ＧＡ３和ＩＡＡ又能不同程度地逆转多效唑的抑制作用，使植株恢复生长。 相似文献
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HU Zhi-cheng ZHU Jia-yuan ZHU Bin GUO Dong CHEN Bin ZHANG Kai HU Kun-hua LI Ming-tao TANG Bing 《园艺学报》2011,27(9):1802-1806
AIM: To investigate and screen the sensitive proteins in the formation mechanism of pathological scars by comparing the results of differential proteomic analysis between pathological scars and normal skin.METHODS: Two-dimensional gel electrophoresis was used to detect the protein expression profiles in 8 keloid patients, 8 hypertrophic scar patients and 3 matched normal skin patients.The proteins that showed differential expression of over 4-fold change were cut and analyzed by MALDI-TOF/TOF mass spectrometry.RESULTS: A two-dimensional protein profiling comparison between pathological scars and normal skin was successfully established.On average, 2 978 spots in keloid, 2 975 spots in hypertrophic scar and 3 053 spots in normal skin were identified using gel analysis software.Compared with normal skin, there were totally 36 differentially-expressed proteins in keloid and hypertrophic scar identified from the spots of over 4-fold change, including 16 proteins in both keloid and hypertrophic scar (8 up-regulated and 8 down-regulated), 11 only in keloid (9 up-regulated and 2 down-regulated) and 9 only in hypertrophic scar (4 up-regulated and 5 down-regulated).CONCLUSION: Proteomic analysis can identify the proteins with variance of pathological scars versus normal skin, thus providing probable new clues to reveal the formation mechanism of pathological scars. 相似文献
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Duncan Brean W. Boyle Shannon Breininger David R. Schmalzer Paul A. 《Landscape Ecology》1999,14(3):291-309
Historic landcover dynamics in a scrubby flatwoods (Tel-4) and scrub landscape (Happy Creek) on John F. Kennedy Space Center were measured using aerial images from 1943, 1951, 1958, 1969, 1979, and 1989. Landcover categories were mapped, digitized, geometrically registered, and overlaid in ARC/INFO. Both study sites have been influenced by various land use histories, including periods of range management, fire suppression, and fire management. Several analyses were performed to help understand the effects of past land management on the amount and spatial distribution of landcover within the study sites. A chi-squared analysis showed a significant difference between the frequency of landcover occurrence and management period. Markov chain models were used to project observed changes over a 100-year period; these showed current management practices being effective at Tel-4 (restoring historic landscape structure) and much less effective at Happy Creek. Documenting impacts of past management regimes on landcover has provided important insight into current landscape composition and will provide the basis for improving land management on Kennedy Space Center and elsewhere. 相似文献
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AIM: Previous studies performed with XBP-01 in vitro indicated that XBP-01 could inhibit vascular smooth muscle cells from being transformed into foam cell and could eliminate the atherosclerotic plaque in C57BL/6J mouse. This experiment is to investigate its mechanism of eliminating plaques in vitro. METHODS: The cultured porcine artery smooth muscle cells incubated with XBP-01 of 0.1 mg/L for 24 h after preincubated with oxidized low density lipoprotein of 15 mg/L for 72 h in vitro. The samples were analyzed by fluorescence microscope, confocal microscope system and flow cytometry. RESULTS: Apoptosis was triggered by being incubated with oxidized low density lipoprotein and this process was accelerated additionally by being incubated with XBP-01. CONCLUSION: XBP-01 can be effective in eliminating atherosclerotic plaque by accelerating the process in which oxidized low density lipoprotein induced smooth muscle cell apoptosis. 相似文献
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Species distribution models (SDMs) often use elevation as a surrogate for temperature or utilise elevation sensitive interpolations
from weather stations. These methods may be unsuitable at the landscape scale, especially where there are sparse weather stations,
dramatic variations in exposure or low elevational ranges. The goal of this study was to determine whether radiation, moisture
or a novel estimate of exposure could improve temperature estimates and SDMs for vegetation on the Illawarra Escarpment, near
Sydney, Australia. Forty temperature sensors were placed on the soil surface of an approximately 12,000 ha study site between
November 2004 and August 2006. Linear regression was used to determine the relationship with environmental factors. Elevation
was correlated more with moderate temperatures (winter maximums, summer minimums, spring and autumn averages) than extreme
temperatures (summer maximums, winter minimums). The correlation (r
2) between temperature and environmental factors was improved by up to 0.38 by incorporating exposure, moisture and radiation
in the regressions. Summer maximums and winter minimums were predominately determined by exposure to the NW and coastal influences
respectively, while exposure to the NE and SW was important during other seasons. These directions correspond with the winds
that are most influential in the study area. The improved temperature estimates were used in Generalised Additive Models for
37 plant species. The deviance explained by most models was increased relative to elevation, especially for moist rainforest
species. It was concluded that improving the accuracy of seasonal temperature estimates could improve our ability to explain
the patchy distribution of many species.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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AIM: To detect the expression of cytoplasmic inhibitor of apoptosis protein 2 (c-IAP2) and growth arrest-specific gene 1 (GAS1) in Hodgkin's lymphoma (HL) and anaplastic large cell lymphoma (ALCL) and to investigate the role of two genes in the pathogenesis of HL and ALCL.METHODS: HE staining, the antibodies CD30, CD15, CD45RO and CD20 were used to screen the cases of HL and ALCL from 288 cases of lymphoma. The clarified HL and ALCL were subjected for immunohistochemical staining by SP and ABC methods to analyze the expression of c-IAP2 and GAS1. RESULTS: ①The positive rate of c-IAP2 in HL was 25/26(96.1%) while that in ALCL was 6/19(31.6%), there presented statistic significance between HL and ALCL groups(P<0.05), meanwhile the positive rate of GAS1 showed statistic significance between HL and ALCL groups(P<0.05). ②Two cases were showed to be a mixed type combined with large tumor cells of HL and relatively smaller tumor cells of ALCL.CONCLUSION: ①The different expression of c-IAP2 and GAS1 in HL and ALCL implied a different mechanism of oncogenesis and the different defects in the pathway of signal transduction of apoptosis in HL and ALCL;②Few cases showed an overlap and a likely transitional state between HL and ALCL; ③The different expressing manner of GAS1 and c-IAP2 in HL and ALCL implied the potential marks for the differential dignosis of two kinds of lymphoma. 相似文献
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Effects of patch attributes, barriers, and distance between patches on the distribution of a rock-dwelling rodent (Lagidium viscacia) 总被引：1，自引：0，他引：1
We tested whether size of habitat patches and distance between patches are sufficient to predict the distribution of the mountain
vizcacha Lagidium viscacia a large, rock-dwelling rodent of the Patagonian steppe Argentina, or whether information on other patch and landscape characteristics
also is required. A logistic regression model including the distance between rock crevices and depth of crevices, distance
between a patch and the nearest occupied patch, and whether or not there was a river separating it from the nearest occupied
patch was a better predictor of patch occupancy by mountain vizcachas than was a model based only on patch size and distance
between patches. Our results indicate that a simple metapopulation analysis based on size of habitat patches and distance
between patches may not provide an accurate representation of regional population dynamics if patches vary in habitat quality
independently of patch size and features in the matrix alter connectivity.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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β3-adrenergic receptor is the third subtype of β-adrenergic receptors. The genetic structure and pharmacological property of β3-adrenergic receptor are markedly distinguished from β1-and β2-adrenergic receptor subtypes. Recently studies show that myocardial β3-adrenergic receptor mediates negative inotropic effect through Gi-protein/NO/cGMP pathway, the expression of β3-adrenergic receptor and negative inotropic effect mediated by β3-adrenergic receptor are increased in heart failure. However, because of the low expression of β3-adrenergic receptor in the heart, the actual pathophysiological significance of β3-adrenergic receptor remains unknown. 相似文献