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181.
The influence of lipid peroxidation on 5-HT2 receptor binding was examined in prefrontal cortex membranes from sheep brain. Lipid peroxidation was induced with ascorbic acid and ferrous sulphate and measured by the thiobarbituric acid method. In lipid-peroxidized membranes, [3H]ketanserin specific binding was inhibited. The Bmax values decreased by 80%, from 50.1±3.5 fmol/mg protein in control membranes to 10.1±2.0 fmol/mg protein in peroxidized membranes, indicating a decrease in the number of 5-HT2 binding sites. However, the KD values for the [3H]ketanserin specific binding did not significantly change. In order to further characterize [3H]ketanserin binding, the inhibition potency (IC50 values) of antagonists or agonists of serotonin and dopamine receptors for [3H]ketanserin specific binding was determined. In control membranes, the order of the inhibition potency of the drugs tested was the following: ketanserin (−log [IC50] = 8.56±0.70) ritanserin (−log [IC50] = 8.13±0.30) methysergide (−log [IC50] = 7.42±0.50) spiperone (−log [IC50] = 7.23±0.18) serotonin (−log [IC50] = 6.99±0.65) haloperidol (−log [IC50] = 6.95±0.65) dopamine (−log [IC50] = 5.82±0.76). After membrane lipid peroxidation, the IC50 value for ritanserin was significantly increased, suggesting a decreased capacity for displacing [3H]ketanserin specific binding. Other antagonists of 5-HT2 receptors showed apparent increases in IC50 values upon peroxidation, whereas spiperone was shown to be the most potent drug (−log [IC50] = 7.19±1.06) in inhibiting [3H]ketanserin specific binding. A decrease in polyunsaturated fatty acids, namely docosahexaenoic acid (22:6) was also observed in peroxidized membranes. These results indicate a modulating role of the surrounding lipids and of the physical properties of the membranes on the binding activity of 5-HT2 receptors upon the lipid peroxidation process, which can be involved in the tissue impairment that occurs during the aging process and in post-ischemic situations. 相似文献
182.
Ana Cristina Rego Maria S. Santos Catarina R. Oliveira 《Journal of neurochemistry》1996,66(6):2506-2516
Abstract: The aim of this study was to elucidate the mechanisms by which retinal cells release endogenous amino acids in response to ascorbate/Fe2+ -induced oxidative stress, as compared with chemical hypoxia or ischemia. In the absence of stimulation, oxidative stress increased the release of aspartate, glutamate, taurine, and GABA only when Ca2+ was present. Under hypoxia or ischemia, the release of aspartate, glutamate, glycine, alanine, taurine, and GABA increased mainly by a Ca2+ -independent mechanism. The increased release observed in N -methyl- d -glucamine+ medium suggested the reversal of the Na+ -dependent amino acid transporters. Upon oxidative stress, the release of aspartate, glutamate, and GABA, occurring through the reversal of the Na+ -dependent transporters, was reduced by about 30%, although the release of taurine was enhanced. An increased release of [3 H]arachidonic acid and free radicals seems to affect the Na+ -dependent transporters for glutamate and GABA in oxidized cells. All cell treatments increased [Ca2+ ]i (1.5 to twofold), although no differences were observed in membrane depolarization. The energy charge of cells submitted to hypoxia or oxidative stress was not changed. However, ischemia highly potentiated the reduction of the energy charge, as compared with hypoglycemia or hypoxia alone. The present work is important for understanding the mechanisms of amino acid release that occur in vivo upon oxidative stress, hypoxia, or ischemia, frequently associated with the impairment of energy metabolism. 相似文献
183.
Correlation between patterns of DNase I-hypersensitive sites and upstream promoter activity of the human epsilon-globin gene at different stages of erythroid development. 总被引:4,自引:2,他引:2 下载免费PDF全文
DNA 5' to the human epsilon-globin gene exhibits unique patterns of DNase I-hypersensitive sites (DHS) in three human erythroleukemic cell lines which represent the embryonic (K562), fetal (HEL), and adult (KMOE) stages of erythroid development. We have mapped 10 epsilon-globin DHS in K562 cells, in which the epsilon-globin gene is maximally active. Major sites are located -11.7, -10.5, -6.5, -2.2 kilobase pairs (kbp) and -200 base pairs (bp) upstream of the gene and directly over the major cap site. Minor sites are located -5.5, -4.5, and -1.48 kbp and -900 bp upstream of the cap site. In HEL cells, in which the epsilon-globin gene is expressed at extremely low levels, the -11.7-, -10.5-, -5.5-, -4.5-, and -2.2-kbp DHS are no longer detectable; the -200-bp site is approximately 300-fold less sensitive to DNase I; and the -1.48-kbp, -900-bp, and major cap site DHS are 3- to 4-fold less sensitive. Only the DHS located -6.5 kbp relative to the major cap site is detectable at all three stages of erythroid development, including KMOE cells in which epsilon-globin synthesis is undetectable. We suggest that this site may be implicated in maintaining the entire beta-globin cluster in an active chromatin conformation. The five DHS downstream of the -6.5-kbp element possess associated promoters. Thus two distinct types of DHS exist--promoter positive and promoter negative. In HEL cells, all the upstream promoters are inactivated, although the -1.48-kbp and -900- and -200-bp DHS are still present. This suggests that the maintenance of DHS and regulation of their associated promoters occur by independent mechanisms. The inactivation of the upstream promoters in HEL cells while the major cap site remains active represents a unique pattern of expression and suggests that HEL cells possess regulatory factors which specifically down regulate the epsilon-globin upstream promoters. 相似文献
184.
J E Paz-Miguel R Flores P Sánchez-Velasco G Ocejo-Vinyals J Escribano de Diego J López de Rego F Leyva-Cobián 《Journal of immunology (Baltimore, Md. : 1950)》1999,163(10):5399-5410
Down's syndrome (DS) is one of the most frequent genetic disorders in humans. It has been suggested that overexpression of copper-zinc superoxide dismutase (SOD-1) in DS may be involved in some of the abnormalities observed, mainly neurodegenerative and immunopathological processes. One of the consequences is early thymic involution. Recently, Ts(1716)65Dn mice (Ts65Dn mice), made segmentally trisomic for a chromosome 16 segment, fulfill the criteria for a DS model. To study the possible role of SOD-1 overexpression in thymocyte biology, we analyzed the role of reactive oxygen intermediates during in vivo and in vitro programmed cell death (PCD) induced in the thymus of Ts65Dn mice. Our main findings can be summarized as follows. Ts65Dn thymuses exhibit greater PCD activity than controls, as ascertained by a combination of morphological, histochemical, and ultrastructural procedures. Ts65Dn thymocytes were highly susceptible to PCD induced by both LPS (in vivo) and dexamethasone, a synthetic glucocorticoid agonist (both in vivo and in vitro). Thymus abnormalities were probably caused by SOD-1 hyperexpression in Ts65Dn cells, in that reactive oxygen intermediate generation (specifically H2O2 production) is enhanced in thymocytes and clearly correlates with apoptosis. Similarly, oxidative injury correlated with the formation of lipid peroxidation by-products and antioxidants which partly inhibit PCD in thymocytes. 相似文献
185.
Sabrine Alila Ana Maria Ferraria Ana Maria Botelho do Rego Sami Boufi 《Carbohydrate polymers》2009,77(3):553-562
Surface grafting of different amino derivatives was carried on under mild condition using N,N′-carbonyldiimidazole (CDI) as an activator. The action of a diamine or a triamine on previously activated cellulose fibres proceeds by the reaction of one amine function giving rise to a carbamate derivative. The other terminal amino groups remained available for further reaction. In particular, their activation with CDI generates a reactive carboxamide able to condense with an aliphatic amine through a urea linkage. Evidence for the occurrence of the reaction at each modification step was confirmed by Fourier Transform Infrared Spectroscopy (FTIRS) and X-ray photoelectron spectroscopy (XPS). The contact angle measurement, using water as a probe, was used to explore the evolution of the surface wettability for the different modification sequences. It was shown that the contact angle value is determined by the ratio between polar and methylene groups and by the spatial arrangement of the molecule on the surface. 相似文献
186.
Kodjo KM Contesse V Do Rego JL Aklikokou K Titrikou S Gbeassor M Vaudry H 《The Journal of steroid biochemistry and molecular biology》2006,100(4-5):202-208
Previous studies conducted in guinea pig, rat and rabbit have revealed that crude extracts from Parkia biglobosa, Stereospermum kunthianum and Biophytum petersianum exert hypotensive and/or hypoglycemic activities. Since corticosteroids are involved in the control of arterial blood pressure and glycemia, we have investigated the possible effects of these plant extracts on rat adrenal tissue in vitro. Short-term administration of crude semi-ethanolic extracts of P. biglobosa and S. kunthianum to perifused rat adrenal tissue did not induce any significant changes in corticosteroid output. Conversely, the B. petersianum extract caused a dose-dependent increase in corticosterone and aldosterone secretion. Repeated infusions or prolonged administration of B. petersianum extract did not produce any apparent attenuation of the steroid response. Altogether, these data indicate that a semi-ethanolic extract of B. petersianum dose-dependently stimulates corticosterone and aldosterone secretion in rat without any desensitization phenomenon. 相似文献
187.
Maria Cristina Duarte Francisco Rego Maria Manuel Romeiras Ilídio Moreira 《Biodiversity and Conservation》2008,17(3):453-466
Plant species richness in the Cape Verde archipelago is examined relative to island eco-geographical factors. Species-area and species-area-habitat relationships are analysed using the classical species-area model and the recently proposed species-choros model. The number of floristic zones (used to estimate the choros parameter) provides an adequate estimate of the potential habitat diversity, and the species-choros model achieved a better fit with both total flora and endemic species. In addition to area and habitat diversity, longitude also emerges as an important determinant of species diversity, whereas latitude, minimum distance to the nearest island, and total rural population do not display any correlation. As in other insular ecosystems, the species richness (about 140 per 100 km2) is lower than in nearby mainland regions; the proximity to the desert areas of the Sahel can also be seen as related with this low value. The floristic heterogeneity in Cape Verde is high, as is usual in island ecosystems. In a comparative analysis of the species richness on the different islands (using α-values), Brava stands out as having the highest total flora species densities, while for endemic flora Brava and São Nicolau jointly occupy the leading position. The high diversity for both total and endemic species on Santo Antão, São Vicente, São Nicolau, Fogo and Brava reinforces their importance in conservation terms - in the case of most of them, something that is already recognized in the established network of protected areas. 相似文献
188.
Mercedes Fernndez-Moreno Ignacio Rego Vanessa Carreira-Garcia Francisco J Blanco 《Current Genomics》2008,9(8):542-547
Osteoarthritis is a degenerative articular disease with complex pathogeny because diverse factors interact causing a process of deterioration of the cartilage. Despite the multifactorial nature of this pathology, from the 50’s it´s known that certain forms of osteoarthritis are related to a strong genetic component. The genetic bases of this disease do not follow the typical patterns of mendelian inheritance and probably they are related to alterations in multiple genes. The identification of a high number of candidate genes to confer susceptibility to the development of the osteoarthritis shows the complex nature of this disease. At the moment, the genetic mechanisms of this disease are not known, however, which seems clear is that expression levels of several genes are altered, and that the inheritance will become a substantial factor in future considerations of diagnosis and treatment of the osteoarthritis. 相似文献
189.
de Castro JA de Andrade HM do Monte SJ da Silva AS Gomes KC de Brito e Amaral LF Cipriano Fde O do Rego JV Araújo MA Faustino SK Nogueira RM Schatzmayr HG Miagostovich MP 《Memórias do Instituto Oswaldo Cruz》2003,98(8):1021-1023
The present paper reports a laboratory investigation performed between the years of 2000 and 2002 to study a virological surveillance program introduced in the state of Piauí to support an epidemiological survey of the disease. Dengue virus type 3 (DENV-3) existence in the state was detected in May 2002 when a high number of dengue cases due to DENV-1 and DENV-2 were reported. An assessment on the population knowledge about the disease and its transmission showed that almost 50% of the population were still unaware of the epidemiological features of dengue. 相似文献
190.
Mitochondrial Dysfunction and Reactive Oxygen Species in Excitotoxicity and Apoptosis: Implications for the Pathogenesis of Neurodegenerative Diseases 总被引:24,自引:0,他引:24
In recent years we have witnessed a major interest in the study of the role of mitochondria, not only as ATP producers through oxidative phosphorylation but also as regulators of intracellular Ca2+ homeostasis and endogenous producers of reactive oxygen species (ROS). Interestingly, the mitochondria have been also implicated as central executioners of cell death. Increased mitochondrial Ca2+ overload as a result of excitotoxicity has been associated with the generation of superoxide and may induce the release of proapoptotic mitochondrial proteins, proceeding through DNA fragmentation/condensation and culminating in cell demise by apoptosis and/or necrosis. In addition, these processes have been implicated in the pathogenesis of many neurodegenerative diseases, which share several features of cell death: selective brain areas undergo neurodegeneration, involving mitochondrial dysfunction (mitochondrial complexes are affected), loss of intracellular Ca2+ homeostasis, excitotoxicity, and the extracellular or intracellular accumulation of insoluble protein aggregates in the brain. 相似文献