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21.
The emotional reactivity of rats with lesions of the dorsal portion of medial prefrontal cortex (mPFC) was examined using a classical fear conditioning paradigm. Conditioned fear behavior (freezing responses) was measured during both the acquisition and extinction phases of the task. Lesions enhanced fear reactivity to both the conditioned stimulus (CS) and contextual stimuli during both phases, suggesting that dorsal mPFC lesions produce a general increase in fear reactivity in response to fear conditioning. M. A. Morgan, L. M. Romanski, and J. E. LeDoux (1993) found that lesions just ventral to the present lesions had no effect during acquisition of the same task and prolonged the fear response to the CS (but not the context) during extinction. Thus, both dorsal and ventral regions of mPFC are involved in the fear system, but each modulates different aspects of fear responsivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
22.
The ability of cells to traverse pores in a biocompatible filter provides means for examining cell chemoattraction. Filter-based assays also permit rapid, quantitative assessment of the in vitro migratory and invasive potential of tumor cells. Scoring migration has relied on visual counting of stained cells which appear on the underside of the filter and determining a true percentage score involves arduous counting of cells on both filter surfaces. Visual counting of random fields may be unreliable, and counting all fields is laborious. In the present study we developed and compared two alternative methods for scoring cell numbers in filter-based assays, a colorimetric assay of toluidine blue binding, and a radioassay of cells prelabeled with [3H]thymidine. Each method was evaluated for sensitivity, variability, ease of use and efficiency, and suitability for use in assays of cell migration and invasion. The radiolabeling method proved to be sensitive and reliable and was the most efficient technique. Although less sensitive and specific, the colorimetric dye method offered a rapid and reliable, nonradioactive alternative with the distinct advantage of preserving intact cultures for follow-up visual assessments. We conclude that colorimetric and radiolabel scoring of filter-based assays are reliable and efficient semiautomated methods which provide means to obtain more complete assessments of cell migration and invasion. 相似文献
23.
Susana Criado Norman A. García Maria I. Gutirrez Vicente Avila Sonia G. Bertolotti Rio Cuarto 《European Journal of Lipid Science and Technology》1996,98(5):172-175
The ability of mono-, di-, tri-and tetra-hydroxyflavones (7-and 3-hy-droxyflavones, 7, 8-dihydroxyflavone, baicalein and fisetin) to act as photoprotectors against singlet molecular oxygen [O2(Δg)]-initiated photooxidation of fats has been established by a kinetic study. The overall quenching rate constants for a series of five hydroxyflavones perfectly parallel their respective behaviour as inhibitors of the sensitized photooxidation of linoleic acid. The best antioxidative effect was exerted by 7-hydroxyflavone which does not chemically react with O2(1Δg). Nevertheless for the remaining flavonoids of the series, the physical deactivation of O2(1Δg) largely prevails over the chemical process. As for the cases of phenols and related hydroxy-aromatic derivatives, the ionization of the -OH group in the flavones, dramatically accelerates the rate of photooxidation. Under these conditions, the 7-hydroxyflavone also reacts effectively with O2(1Δg). Given that flavonoids are natural oil components, this medium effect should be taken into account during the oil-refining process, in order to avoid the flavonoid photodestruction. 相似文献
24.
The bulk modification of SBS rubber with maleic anhydride in a mixing chamber of a Haake rheomixer was studied. The effect of temperature, maleic anhydride, and benzoyl peroxide concentrations on the grafting efficiency was evaluated. High grafting efficiency was achieved when the ratio of peroxide and maleic anhydride concentration was high. On the other hand, on this condition high insoluble fraction was generated. The addition of a diamine, 4,4′‐diaminediphenylmethane to the reaction mixture minimizes the amount of insoluble polymer. However, the grafted MAH content also decreases. The graft copolymer was characterized by infrared spectroscopy and the grafting extension was determined by titration. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2953–2960, 2002; DOI 10.1002/app.10355 相似文献
25.
Ionomeric composites based on sepiolite and hydrogenated poly(styrene butadiene) block copolymer were obtained and characterized from a microstructural and electrical point of view. Before blending, because of the high silanol group concentration in the sepiolite, the latter could be organophilized with suitable coupling agents. The resulting materials were easily processed into thin films or membranes 0.2–0.4 mm thick, their conductivity in some cases approaching 10?1 S/cm. Their suitability for film formation and good electrical properties indicate potential applications as electrolytes in polymer fuel cells. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3512–3519, 2002 相似文献
26.
P Casolo D Mosca C Amorotti B Drei A Raspadori P Di Blasio E Ganz G De Luca G Colli R De Maria D Amuso 《Canadian Metallurgical Quarterly》1997,68(2):207-11; discussion 212
Primary and sole breast lymphoma is a very rare disease. With the review of our series of 616 cases operated on for breast cancer, only 3 cases (0.48%) of primary breast non-Hodgkin lymphoma (LNH) have been observed. The authors outline the problems concerning diagnosis and therapy of this rare disease: pathological and immunohistochemical aspects are discussed. They stress the importance of staging in order to plan a correct multidisciplinary approach. 相似文献
27.
Sandra Aparecida de Assis Pedro Fernandes Bruno Sommer Ferreira Joaquim MS Cabral Olga Maria Mascarenhas Faria Oliveira 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2004,79(3):277-280
A partially purified extract of pectinmethylesterase (PME) from acerola fruit was immobilized on various supports: glass, celite, chrysotile, agarose, concanavalin A Sepharose 4B, egg shell, polyacrylamide and gelatin. In addition, reticulation with glutaraldehyde was assessed, as well as the use of gelatin in the presence of celite, glass and silica. The highest immobilization yields were obtained when the pectinmethylesterase was immobilized in concanavalin A Sepharose 4B (81.7%) and in gelatin‐water (78.0%). Copyright © 2004 Society of Chemical Industry 相似文献
28.
Daniela D'Amato Maria Rosaria Corbo Matteo Alessandro Del Nobile & Milena Sinigaglia 《International Journal of Food Science & Technology》2006,41(10):1152-1157
In enology, alcoholic fermentation is a complex process involving several mechanisms. Slow and incomplete alcoholic fermentation is a chronic problem for the wine industry and factors leading to sluggish and stuck fermentations have been extensively studied and reviewed. The most studied cause of sluggish and stuck fermentation is the nitrogen content limitation. Nevertheless, other factors, such as temperature of fermentation and sugar concentration can affect the growth of yeasts. In this study we modelled the yeast growth‐cycle in wine model system as a function of temperature, sugar and ammonium concentrations; the individual effects and the interaction of these factors were analysed by means of a quadratic response surface methodology. Cell concentrations and weight loss were monitored in the whole wine fermentation process. The results of central composite design show that lower is the availability of nitrogen, higher is the cell growth rate; moreover, initial nitrogen concentration also influences survival time of Saccharomyces cerevisiae. 相似文献
29.
Summary
In this paper thermal behavior of some HNBR blends with CPE, PVC, CR and NBR at three temperatures, 150, 170 and 190°C is
presented. Changes in characteristic IR bands, gel fraction, and chlorine content were assessed. Some mechanistic differences
between the studied systems, regarding the involvement the depletion of chlorine and modification in gel content, were pointed
out. Cyclization of nitrile structure was also observed by means of 2240 cm−1 band ascribed to >C=NH. Kinetic considerations are presented.
Received: 3 June 2002/Revised version: 14 November 2002/ Accepted 20 November 2002
Correspondence to Traian Zaharescu 相似文献
30.