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81.
Karonen M Leikas A Loponen J Sinkkonen J Ossipov V Pihlaja K 《Phytochemical analysis : PCA》2007,18(5):378-386
Mountain birch leaves contain large amounts of structurally variable polymeric proanthocyanidins. Their isolation procedure was enhanced by the addition of liquid-liquid extractions prior to column chromatography over Sephadex LH-20. Isolated polymeric proanthocyanidins were depolymerised by acid-catalysis in the presence of benzyl mercaptan or phloroglucinol in order to study their composition. The resulting degradation products, flavan-3-ols and flavan-3-ol adducts, were analysed with reversed-phase high-performance liquid chromatography using UV photodiode array detection for quantification and electrospray ionisation mass spectrometry for identification. The results showed that polymeric proanthocyanidins contained (epi)gallocatechins and (epi)catechins as the extension units and, mainly, (+)-catechin as the terminal unit. The mean degree of polymerisation was found to be 26 based on thiolysis and 31 based on phloroglucinol degradation. 相似文献
82.
James S. Farris Mari Källersjö Victor A. Albert Marc Allard Arne Anderberg Brunella Bowditch Carol Bult James M. Carpenter Timothy M. Crowe Jan De Laet Kirk Fitzhugh Darryl Frost Pablo Goloboff Christopher J. Humphries Ulf Jondelius Darlene Judd Per Ola Karis Diana Lipscomb Melissa Luckow David Mindell Jyrki Muona Kevin Nixon William Presch Ole Seberg Mark E. Siddall Lena Struwe ers Tehler John Wenzel Quentin Wheeler Ward Wheeler 《Cladistics : the international journal of the Willi Hennig Society》1995,11(2):211-218
83.
After drainage of natural boreal peatlands, the decomposition of organic matter increases and peat soil may turn into a net source of CO2 and N2O, whereas CH4 emission is known to decrease. Afforestation is a potential mitigation strategy to reduce greenhouse gas emission from organic agricultural soils. A static chamber technique was used to evaluate the fluxes of CH4, N2O and CO2 from three boreal organic agricultural soils in western Finland, afforested 1, 6 or 23 years before this study. The mean emissions of CH4 and N2O during the growing seasons did not correlate with the age of the tree stand. All sites were sources of N2O. The highest daily N2O emission during the growing season, measured in the oldest site, was as high as 29 mg N2O m–2d–1. In general, organic agricultural soils are sinks for methane. Here, the oldest site acted as a small sink for methane, whereas the two youngest afforested organic soils were sources for methane with maximum emission rates (up to 154 mg m–2d–1) similar to those reported for minerogenous natural peatlands. Soil respiration rates decreased with the age of the forest. The high soil respiration in the younger sites, probably resulted from the high biomass production of herbs, could create soil anaerobiosis and increase methane production. Our results show that afforestation of agricultural peat soils does not abruptly terminate the N2O emissions during the first two decades, and afforestation can even enhance methane emission for a few years. The carbon accumulation in the developing tree stand can partly compensate the carbon loss from soil. 相似文献
84.
85.
Jyrki Rasku Martti Juhola Esko Toppila Ilmari Pyykk 《Biomedical signal processing and control》2007,2(1):1-8
The objective of the present research was to investigate whether hidden Markov models can be used to recognise and classify balance signals extracted from two subject groups, the healthy and patients suffering from otoneurological vertiginous diseases. Two different testing protocols were applied: arising from a chair and standing on the force platform. Signals recorded according to these protocols were trained for models with different numbers of states to find the best choices as model structures. We found that these models with 7–15 states were able to recognise the healthy subjects from the patients with the accuracy between 70 and 90% although their balance measurements were visually very similar and difficult to separate between two groups. 相似文献
86.
Cervera MF Heinämäki J Krogars K Jörgensen AC Karjalainen M Colarte AI Yliruusi J 《AAPS PharmSciTech》2004,5(1):109-114
The film-forming ability of chitosan and binary mixtures of chitosan and native amylose corn starch (Hylon VII) was evaluated
with free films prepared by a casting/solvent evaporation method. Unplasticized and plasticized free chitosan films in aqueous
acetic acid and respective films containing a mixture of chitosan and native amylose starch in acetic acid were prepared.
Glycerol, sorbitol, and i-erythritol were used as plasticizers. Solid-state and mechanical properties of the films were studied
by powder x-ray diffractometry (XPRD), differential scanning calorimetry (DSC), and a materials testing machine. The films
composed of a mixture of chitosan and native amylose starch in acetic acid were clear and colorless. A plasticizer concentration
of 20% wt/wt (of the polymer weight) ws sufficient to obtain flexible films with all samples tested. X-ray diffraction patterns
and DSC thermograms indicated an amorphous state of the films independent of the type of plasticizer used. In conclusion,
incorporation of native amylose com starch into chitosan films improves the consistency and the mechanical properties of the
films. 相似文献
87.
Heidi Teppola Jertta-Riina Sarkanen Tuula O. Jalonen Marja-Leena Linne 《Neurochemical research》2016,41(4):731-747
Human SH-SY5Y neuroblastoma cells maintain their potential for differentiation and regression in culture conditions. The induction of differentiation could serve as a strategy to inhibit cell proliferation and tumor growth. Previous studies have shown that differentiation of SH-SY5Y cells can be induced by all-trans-retinoic-acid (RA) and cholesterol (CHOL). However, signaling pathways that lead to terminal differentiation of SH-SY5Y cells are still largely unknown. The goal of this study was to examine in the RA and CHOL treated SH-SY5Y cells the additive impacts of estradiol (E2) and brain-derived neurotrophic factor (BDNF) on cell morphology, cell population growth, synaptic vesicle recycling and presence of neurofilaments. The above features indicate a higher level of neuronal differentiation. Our data show that treatment for 10 days in vitro (DIV) with RA alone or when combined with E2 (RE) or CHOL (RC), but not when combined with BDNF (RB), significantly (p < 0.01) inhibited the cell population growth. Synaptic vesicle recycling, induced by high-K+ depolarization, was significantly increased in all treatments where RA was included (RE, RC, RB, RCB), and when all agents were added together (RCBE). Specifically, our results show for the first time that E2 treatment can alone increase synaptic vesicle recycling in SH-SY5Y cells. This work contributes to the understanding of the ways to improve suppression of neuroblastoma cells’ population growth by inducing maturation and differentiation. 相似文献
88.
Zhang L Koivisto L Heino J Uitto VJ 《Biochemical and biophysical research communications》2004,319(4):1088-1095
Exogenous heat shock proteins may modify cell behavior of infected epithelium. The effect of heat shock protein 60 (hsp60) of Actinobacillus actinomycetemcomitans and Escherichia coli, and human recombinant hsp60 on migration of HaCaT skin keratinocytes was studied using the Boyden chamber assay. Hsp60 from different species increased cell migration by two- to fivefold and this effect was inhibited by ERK inhibitor PD 98059, p38 inhibitor SB 203580, and a function-blocking epidermal growth factor receptor (EGFR) antibody. Hsp60 reduced the expression of alpha6-integrin mRNA and its protein levels on the cell surface but had no effect on the expression of beta4, beta1, alpha1, alpha5 or alphav integrin subunits. Hsp60 also significantly inhibited cell adhesion to laminin-5, a ligand of alpha6beta4 integrin. These results suggest that exogenous hsp60 released from bacteria or inflammatory cells may promote epithelial cell migration through activation of EGFR and MAP kinases, and inhibition of alpha6beta4 integrin expression. 相似文献
89.
Xing L Huhtala M Pietiäinen V Käpylä J Vuorinen K Marjomäki V Heino J Johnson MS Hyypiä T Cheng RH 《The Journal of biological chemistry》2004,279(12):11632-11638
Integrins are cell surface receptors for several microbial pathogens including echovirus 1 (EV1), a picornavirus. Cryo-electron microscopy revealed that the functional domain (alpha(2)I) of human alpha(2)beta(1) integrin binds to a surface depression on the EV1 capsid. This three-dimensional structure of EV1 bound to alpha(2)I domain provides the first structural details of an integrin interacting with a picornavirus. The model indicates that alpha(2)beta(1) integrin cannot simultaneously bind both EV1 and the physiological ligand collagen. Compared with collagen binding to the alpha(2)I domain, the virus binds with a 10-fold higher affinity but in vitro uncoating of EV1 was not observed as a result of attachment of alpha(2)I. A molecular model, constructed on the basis of the EV1-integrin complex, shows that multiple alpha(2)beta(1) heterodimers can bind at adjacent sites around the virus 5-fold symmetry axes without steric hindrance. In agreement with this, virus attachment to alpha(2)beta(1) integrin on the cell surface was found to result in integrin clustering, which can give rise to signaling and facilitate the initiation of the viral entry process that takes place via caveolae-mediated endocytosis. 相似文献
90.