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951.
Advanced glycation end products (AGEs) are a class of complex heterogeneous compounds which accumulate with age and is known to be involved in the pathogenesis of several diseases from diabetes to atherosclerosis. AGEs serve as ligands for multiple receptors including scavenger receptor (SR-A), CD36, and SR-BIota. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) plays an important role in both atherosclerosis and is found to be an endothelial cell receptor for AGEs. To explore the binding characterization of AGEs to LOX-1, AGEs were prepared by three different reducing sugars (d-glucose, d-fructose, and d-ribose) and the biochemical characterization including, free amino groups, free amine content, fructosamine residues, carbonyl content, fluorescence, and absorbance were determined. The binding activity was determined by FITC labeled AGEs using Chinese hamster ovary-K1 cells stably transfected with human LOX-1 gene. The obtained AGEs showed significant differences in the extent of side chain modifications, carbonyl content, fluorescence, and absorption models. All of the AGEs showed specific and saturable binding to hLOX-1-CHO-K1 cells. Furthermore, dose-dependent binding processes were observed. However, the maximal cellular binding of AGEs differs between the sugars (glucose > ribose > fructose). In addition, oxidized low-density lipoprotein (ox-LDL) could significantly inhibit the binding of AGEs to LOX-1 with different inhibitory efficiency. LOX-1 serves as receptor for AGEs which may give some insight into the role of LOX-1 in the pathogenesis of diabetes and related disorders. 相似文献
952.
The head lice, Pediculus humanus capitis (Phthiraptera:Pediculidae), is an obligate ectoparasite of humans that causes pediculosis capitis, a nuisance for millions
of people worldwide, with high prevalence in children. Pediculosis capitis has been treated by methods that include the physical
remotion of lice, various domestic treatments and conventional insecticides. None of these methods render complete protection,
and there is clear evidence for the evolution of resistance and cross-resistance to conventional insecticides. Non-toxic alternative
options are hence needed for head lice treatment and/or prevention, and natural products from plants, especially essential
oils (EOs), are good candidates for safer control agents that may provide good anti-lice activity and low levels of evolved
resistance. A few EOs have been tested as repellents with promissory results, although often in vitro tests and clinical trials
produce contradictory results. A handful of fixed extracts and several EOs and their individual components have also been
tested as contact pediculicides or fumigants. The studies have focused mainly on plant families characterized for the production
of EOs. While many EOs and individual compounds showed pediculicide activity, comparing results is difficult due to the diverse
bioassay methodologies. Studies of anti-lice activity of individual EO components provide the basis for preliminary conclusions
of structure–activity relationships, although no clear patterns can yet be drawn. We here attempt to provide a concise compilation
of the available information on anti-lice activity of plant extracts and plant-derived compounds, which we hope may be of
help for future developments in this area.
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953.
The mechanism of the spontaneous initiation of the polymerization of methyl methacrylate (MMA) was investigated theoretically.
The six minimum energy paths (MEP) of the possible reactions were calculated using the density functional theory (DFT) in
conjunction with the B3LYP functional and 6-31G* basis set. The Diels-Alder initiation mechanism (path (I) and path (II))
with remarkably high energy barriers is not applicable to MMA. Four favorable paths were found (path (III), path (IV), path
(V) and path (VI)), which are supporting the Flory mechanism. Path (V) has the lowest active energy. Therefore this path is
considered as the main path for the spontaneous polymerization of MMA.
Figure The mechanism of the spontaneous initiation of the polymerization of methyl methacrylate (MMA) was investigated theoretically.
The six minimum energy paths (MEP) of the possible reactions were calculated using the density functional theory (DFT) in
conjunction with the B3LYP functional and 6-31G* basis set. 相似文献
954.
The oxidation of the hexacarbonyl(1,3-dithiolato-S,S')diiron complexes 4a-4c with varying amounts of dimethyldioxirane (DMD) was systematically studied. The chemoselectivity of the oxidation products depended upon the substituent R (R=H, Me, 1/2 (CH2)(5)). For R=H, four oxidation products, 6a-6d, have been obtained. In the case of R=Me, three products, 7a-7c, were formed, and for R=1/2 (CH2)(5), only complex 8 was observed. These observations are due to steric and electronic effects caused by the substituent R. Additionally, oxidation of the triiron complex 5 with DMD was performed to yield the products 9a and 9b. X-Ray diffraction analyses were performed for 6a-6d, 7a, and 7c, as well as for 9a and 9b. The electronic properties were determined by density-functional theory (DFT) calculations. 相似文献
955.
Prourokinase (scu-PA), a thrombolytic agent, was inserted between Gly118 and Ile119 with foreign antithrombosis functional motif (Lys-Gly-Asp-Trp-motif)
to construct a multi-functional chimeric molecule. The molecular model of a chimera was simulated and predicted. The recombinant
chimeric protein was expressed by the baculovirus-insect cell expression system and purified by affinity chromatography. The
physico-chemical characteristics of the chimeric molecule were assayed. The thrombolytic activity was determined to be 90000
IU/mg of fibrinolytic special activity by the fibrin-plate method. The anti-thrombosis activities were also assayed with IC50 of 9.6 μM by an inhibition test of ADP-induced platelet aggregation. 相似文献
956.
目的:本文着重研究利用石墨炉原子吸收光谱法测定虾产品中铝,对测定条件进行优化选择,达到快速、准确,以弥补国家标准检测方法中没有虾产品中铝检测方法的不足。方法:利用混合酸硝酸-高氯酸对样品进行消化处理,无基体改进剂,利用石墨炉原子吸收光谱仪进行定量检测。结果:在优化干燥、灰化、原子化、除残四个步骤的时间和温度的实验条件后,铝含量在0.0-50.0μg/L范围内呈线性关系,相关系数达到r=0.9990,最低检出限为0.54 ng/mL,铝的特征质量为5.0 pg。相对标准偏差为3.83%-6.42%,虾产品中铝含量测定回收率为90.7%-105.6%。结论:本法方便准确,灵敏度高,并有较高的回收率,可作为日常检测使用。 相似文献
957.
Yunhuan Liu Yong Li Tiequan Shao Zhixin Zhu Wanqian Zhang Zhuo Wang Weixian Yang Rongxi Li 《生物学前沿》2008,3(1):106-112
The Meishucun stage is the prelude in decipher-ing the Cambrian Explosion. In this prominent stage, rapid radioactive evolution and body-plan innovation have taken place and different associations of organism have been shaped. In this paper we report several 3D-preserved rare star-like fossils with finely preserved soft tissues which were recovered from the Kuanchuanpu Member of the Dengying Formation in South Shaanxi, China in 2003. By studying on functional morphology and analogy with mouthpart of Punctatus, there are evidences that this star-like organism approaches the coelenterates in systematic classification and the centre of star-like organism is its mouth. The appearance of coelenterates marks the real beginning of metazoan evolution. Therefore, it has the prominent position in the origin and evolutionary history of organisms. Perhaps the star-like organism represents the early types of coelenterate with original tentacles. These new materials provide new evidence for the origin, evolution and the functional evolution of the metazoan during the early stage of the Cambrian Explosion. 相似文献
958.
Trophic functional groups and trophic levels of the macrobenthic community at the eastern tidal flat of Lingkun Island, China 总被引:1,自引:0,他引:1
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A total of 33 taxa, including 21 families, 8 classes and 7 phyla, were found at the eastern tidal flat of Lingkun Island, Wenzhou Bay. Most of them were mollusks, crustaceans and polychaetes. The species numbers found at 3 tidal flats (high, middle and low) were 25, 30 and 14, respectively. It was shown that the high tidal flat had the highest value of diversity indices, followed by middle and low tidal flats. The species belonged to 5 different trophic functional groups: Phytophagous, Camivorous, Omnivorous, Planktophagous and Detritivorous in qualitative samplings. Then 3, 8, 5, 3 and 2 species belonged to Planktophagous, Phytophagous, Camivorous, Omnivorous and Detritivorous groups, respectively, in quantitative samplings. The density and species number of each functional group did not display seasonal variation by the two-way ANOVA method. Regardless of seasonal variation, density of the Phytophagous group and Camivorous group had distinct difference among different zones of tidal flats, and the species number of the Phytophagous group and Omnivorous group had obvious difference among different zones of tidal flats. Results show that there was variation of functional groups among habitats. Change in components of the macrobenthic community reflected different food sources in different zones of tidal flats. 相似文献
959.
Recently, a mechanism for the energy-dependent component (qE) of non-photochemical quenching (NPQ), the fundamental photo-protection mechanism in green plants, has been suggested. Replacement of violaxanthin by zeaxanthin in the binding pocket of the major light harvesting complex LHC-II may be sufficient to invoke efficient chlorophyll fluorescence quenching. Our quantum chemical calculations, however, show that the excited state energies of violaxanthin and zeaxanthin are practically identical when their geometry is constrained to the naturally observed structure of violaxanthin in LHC-II. Therefore, since violaxanthin does not quench LHC-II, zeaxanthin should not either. This theoretical finding is nicely in agreement with experimental results obtained by femtosecond spectroscopy on LHC-II complexes containing violaxanthin or zeaxanthin. 相似文献
960.
Christopher J. Vinyard Nayuta Yamashita Chia Tan 《International journal of primatology》2008,29(6):1421-1439
A realistic understanding of primate morphological adaptations requires a multidisciplinary approach including experimental
studies of physiological performance and field studies documenting natural behaviors and reproductive success. For primate
feeding, integrative efforts combining experimental and ecological approaches are rare. We discuss methods for collecting
maximum bite forces in the field as part of an integrated ecomorphological research design. Specifically, we compare maximum
biting ability in 3 sympatric bamboo lemurs (Hapalemur simus, H. aureus, and H. griseus) at Ranomafana National Park, Madagascar to determine if biting performance contributes to the observed partitioning of a
shared bamboo diet. We assessed performance by recording maximum bite forces via jaw-muscle stimulations in anesthetized subjects
from each species. Behavioral observations and food properties testing show that the largest species, Hapalemur simus, consumes the largest and most mechanically challenging foods. Our results suggest that Hapalemur simus can generate larger bite forces on average than those of the 2 smaller species. However, the overlap in maximum biting ability
between Hapalemur simus and H. aureus indicates that biting performance cannot be the sole factor driving dietary segregation. Though maximum bite force does not
fully explain dietary segregation, we hypothesize that size-related increases in both maximum bite force and jaw robusticity
provide Hapalemur simus with an improved ability to process routinely its more obdurate diet. We demonstrate the feasibility of collecting physiological,
ecological, and morphological data on the same free-ranging primates in their natural habitats. Integrating traditionally
laboratory-based approaches with field studies broadens the range of potential primate species for physiological research
and fosters improved tests of hypothesized feeding adaptations. 相似文献