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排序方式: 共有260条查询结果,搜索用时 15 毫秒
91.
Khaing Z Kang D Camelio AM Schmidt CE Siegel D 《Bioorganic & medicinal chemistry letters》2011,21(16):4808-4812
The use of small molecule surrogates of growth factors that directly or indirectly promote growth represents an attractive approach to regenerative medicine. With synthetic access to clovanemagnolol, a small molecule initially isolated from the bark of the Bigleaf Magnolia tree, we have examined the small molecule’s ability to promote growth of embryonic hippocampal and cortical neurons in serum-free medium. Comparisons with magnolol, a known promoter of growth, reveals that clovanmagnolol is a potent neurotrophic agent, promoting neuronal growth at concentrations of 10 nM. In addition, both clovanemagnolol and magnolol promote growth through a biphasic dose response. 相似文献
92.
As a renewable non-food resource, lignocellulosic biomass has great potential as an energy source or feedstock for further conversion. However, challenges exist with supply logistics of this geographically scattered and perishable resource. Hydrothermal carbonization treats any kind of biomass in 200 to 260 °C compressed water under an inert atmosphere to produce a hydrophobic solid of reduced mass and increased fuel value. A maximum in higher heating value (HHV) was found when 0.4 g of acetic acid was added per g of biomass. If 1 g of LiCl and 0.4 g of acetic acid were added per g of biomass to the initial reaction solution, a 30% increase in HHV was found compared to the pretreatment with no additives, along with greater mass reduction. LiCl addition also reduces reaction pressure. Addition of acetic acid and/or LiCl to hydrothermal carbonization each contribute to increased HHV and reduced mass yield of the solid product. 相似文献
93.
Aims: To determine incidence and levels of ochratoxin A (OTA) in California raisins and to isolate and characterize OTA‐producing fungi from California raisin vineyard populations. Methods and Results: Forty raisin clusters sampled from four California vineyards in the San Joaquin Valley were analysed for OTA content using immunoaffinity and HPLC methods. OTA was detected in 93% of the samples, at levels from 0·06 to 11·4 ng g?1. From these raisin samples, a total of 400 strains of Aspergillus were isolated and analysed for OTA production. Twelve isolates (3%), from five raisin samples, produced OTA. These isolates were identified as Aspergillus carbonarius, based on morphological characteristics and multilocus sequence analysis. Levels of OTA produced by these isolates on raisin agar ranged from 0·9 to 15 μg g?1. Conclusions: OTA is a common contaminant of raisin vineyards, but average levels are much lower than EU regulatory limits for dried fruit. The primary species responsible for OTA contamination in California raisins is A. carbonarius. Significance and Impact of the Study: This study illustrates that low‐level OTA contamination of raisins occurs in California and that ecological studies of A. carbonarius within the Aspergillus section Nigri population on raisins are warranted to monitor ochratoxigenic potential of the crop. 相似文献
94.
Jacob M. Vasquez Andrew Vu Jerome S. Schultz Valentine I. Vullev 《Biotechnology progress》2009,25(4):906-914
Warfarin is the most common agent used for control and prevention of venous as well as arterial thromboembolism (blood clots). In aqueous media, warfarin forms inclusion complexes with a family of cyclic oligosaccharides, α, β, γ‐cyclodextrins (CD). The formation of these complexes results in enhancement of the fluorescence of warfarin. Such spectroscopic changes offer a venue for the development of bioanalytical methodologies for warfarin quantification in biological liquids. We characterized the photophysical properties of warfarin in solvents with varying polarity and viscosity. The fluorescence quantum yield of warfarin correlated: (1) strongly with the solvent viscosity (R = 0.979) and (2) weakly with the solvent polarity (R = 0.118). These findings indicate that it is the change of the viscosity, rather than polarity, of the microenvironment that causes the fluorescence enhancement of warfarin upon binding to β‐CD. Utilizing the observed fluorescence enhancement in fluorescence titration measurements, the binding constants of warfarin to β‐CD were obtained (2.6 × 102 M?1–3.7 × 102 M?1). Using multivariable linear analysis, we extracted the stoichiometry of warfarin‐β‐CD interaction (1:1). © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 相似文献
95.
The Enemy Release hypothesis holds that exotic plants may have an advantage over native plants because their specialized natural enemies are absent. We tested this hypothesis by measuring leaf damage and plant abundance for naturally-occurring plants in prairies, and by removing natural enemies in an enemy exclusion experiment. We classified plants as invasive exotic, noninvasive exotic, or native, to determine if their degree of invasiveness influenced their relationships with natural enemies. Our field surveys showed that invasive exotic plants generally had significantly lower levels of foliar damage than native species while there was no consistent pattern for noninvasive exotics compared to natives. The relationship between damage and abundance was different for exotic and native plants: foliar damage decreased with increasing abundance for exotic plants while the trend was positive for native plants. While these results from the field surveys supported the Enemy Release Hypothesis, the enemy exclusion experiment did not. There was no relationship between a species?? status as exotic or native and its degree of release from herbivory. Pastinaca sativa, the invasive exotic in this experiment, experienced gains in leaf area and vegetative biomass when treated with pesticides, indicating substantial herbivore pressure in the introduced range. These results show that foliar damage may not accurately predict the amount of herbivore pressure that plants actually experience, and that the Enemy Release hypothesis is not sufficient to explain the invasiveness of P. sativa in prairies. 相似文献
96.
Alvarez-Moya C Silva MR Arámbula AR Sandoval AI Vasquez HC González Montes RM 《Genetics and molecular biology》2011,34(1):127-130
Glyphosate is noted for being non-toxic in fishes, birds and mammals (including humans). Nevertheless, the degree of genotoxicity is seriously controversial. In this work, various concentrations of a glyphosate isopropylamine salt were tested using two methods of genotoxicity assaying, viz., the pink mutation assay with Tradescantia (4430) and the comet assay with nuclei from staminal cells of the same plant. Staminal nuclei were studied in two different forms, namely nuclei from exposed plants, and nuclei exposed directly. Using the pink mutation assay, isopropylamine induced a total or partial loss of color in staminal cells, a fundamental criterion utilized in this test. Consequently, its use is not recommended when studying genotoxicity with agents that produce pallid staminal cells. The comet assay system detected statistically significant (p < 0.01) genotoxic activity by isopropylamine, when compared to the negative control in both the nuclei of treated plants and directly treated nuclei, but only the treated nuclei showed a dose-dependent increase. Average migration in the nuclei of treated plants increased, when compared to that in treated nuclei. This was probably due, either to the permanence of isopropylamine in inflorescences, or to the presence of secondary metabolites. In conclusion, isopropylamine possesses strong genotoxic activity, but its detection can vary depending on the test systems used. 相似文献
97.
Lloyd DJ Helmering J Kaufman SA Turk J Silva M Vasquez S Weinstein D Johnston B Hale C Véniant MM 《PloS one》2011,6(4):e18800
Precise quantification of atherosclerotic plaque in preclinical models of atherosclerosis requires the volumetric assessment of the lesion(s) while maintaining in situ architecture. Here we use micro-computed tomography (microCT) to detect ex vivo aortic plaque established in three dyslipidemic mouse models of atherosclerosis. All three models lack the low-density lipoprotein receptor (Ldlr−/−), each differing in plaque severity, allowing the evaluation of different plaque volumes using microCT technology. From clearly identified lesions in the thoracic aorta from each model, we were able to determine plaque volume (0.04–3.1 mm3), intimal surface area (0.5–30 mm2), and maximum plaque (intimal-medial) thickness (0.1–0.7 mm). Further, quantification of aortic volume allowed calculation of vessel occlusion by the plaque. To validate microCT for future preclinical studies, we compared microCT data to intimal surface area (by using en face methodology). Both plaque surface area and plaque volume were in excellent correlation between microCT assessment and en face surface area (r2 = 0.99, p<0.0001 and r2 = 0.95, p<0.0001, respectively). MicroCT also identified internal characteristics of the lipid core and fibrous cap, which were confirmed pathologically as Stary type III-V lesions. These data validate the use of microCT technology to provide a more exact empirical measure of ex vivo plaque volume throughout the entire intact aorta in situ for the quantification of atherosclerosis in preclinical models. 相似文献
98.
Uhlemann AC Knox J Miller M Hafer C Vasquez G Ryan M Vavagiakis P Shi Q Lowy FD 《PloS one》2011,6(7):e22407
Background
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections are spreading, but the source of infections in non-epidemic settings remains poorly defined.Methods
We carried out a community-based, case-control study investigating socio-demographic risk factors and infectious reservoirs associated with MRSA infections. Case patients presented with CA-MRSA infections to a New York hospital. Age-matched controls without infections were randomly selected from the hospital''s Dental Clinic patient population. During a home visit, case and control subjects completed a questionnaire, nasal swabs were collected from index respondents and household members and standardized environmental surfaces were swabbed. Genotyping was performed on S. aureus isolates.Results
We enrolled 95 case and 95 control subjects. Cases more frequently reported diabetes mellitus and a higher number of skin infections among household members. Among case households, 53 (56%) were environmentally contaminated with S. aureus, compared to 36 (38%) control households (p = .02). MRSA was detected on fomites in 30 (32%) case households and 5 (5%; p<.001) control households. More case patients, 20 (21%) were nasally colonized with MRSA than were control indexes, 2 (2%; p<.001). In a subgroup analysis, the clinical isolate (predominantly USA300), was more commonly detected on environmental surfaces in case households with recurrent MRSA infections (16/36, 44%) than those without (14/58, 24%, p = .04).Conclusions
The higher frequency of environmental contamination of case households with S. aureus in general and MRSA in particular implicates this as a potential reservoir for recolonization and increased risk of infection. Environmental colonization may contribute to the community spread of epidemic strains such as USA300. 相似文献99.
Xiong-jian Luo Ming Li Liang Huang Kwangsik Nho Min Deng Qiang Chen Daniel R. Weinberger Alejandro Arias Vasquez Mark Rijpkema Venkata S. Mattay Andrew J. Saykin Li Shen Guillén Fernández Barbara Franke Jing-chun Chen Xiang-ning Chen Jin-kai Wang Xiao Xiao Xue-bin Qi Kun Xiang Ying-Mei Peng Xiang-yu Cao Yi Li Xiao-dong Shi for the Alzheimer’s Disease Neuroimaging Initiative Lin Gan Bing Su 《PloS one》2012,7(11)
100.
Justin Knox Anne-Catrin Uhlemann Maureen Miller Cory Hafer Glenny Vasquez Peter Vavagiakis Qiuhu Shi Franklin D. Lowy 《PloS one》2012,7(11)