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排序方式: 共有1586条查询结果,搜索用时 31 毫秒
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Mahsa Zahiri Maryam Babaei Khalil Abnous Seyed Mohammad Taghdisi Mohammad Ramezani Mona Alibolandi 《Journal of cellular physiology》2020,235(2):1036-1050
In this study, the chemical features of dendritic mesoporous silica nanoparticles (DMSNs) provided the opportunity to design a nanostructure with the capability to intelligently transport the payload to the tumor cells. In this regard, doxorubicin (DOX)-encapsulated DMSNs was electrostatically surface-coated with polycarboxylic acid dextran (PCAD) to provide biocompatible dextran-capped DMSNs (PCAD-DMSN@DOX) with controlled pH-dependent drug release. Moreover, a RNA aptamer against a cancer stem cell (CSC) marker, CD133 was covalently attached to the carboxyl groups of DEX to produce a CD133-PCAD-DMSN@DOX. Then, the fabricated nanosystem was utilized to efficiently deliver DOX to CD133+ colorectal cancer cells (HT29). The in vitro evaluation in terms of cellular uptake and cytotoxicity demonstrated that the CD133-PCAD-DMSN@DOX specifically targets HT29 as a CD133 overexpressed cancer cells confirmed by flow cytometry and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay. The potentially promising intelligent-targeted platform suggests that targeted dextran-capped DMSNs may find impressive application in cancer therapy. 相似文献
3.
Lead is a heavy metal widely distributed in the environment. Lead is a ubiquitous environmental toxin that is capable of causing numerous acute and chronic illnesses. Human and animal exposure demonstrates that lead is nephrotoxic. However, attempts to reduce lead-induced nephrotoxicity were not found suitable for clinical use. Recently, flaxseed oil (FXO), a rich source of ω-3 fatty acids and lignans, has been shown to prevent/reduce the progression of certain types of cardiovascular and renal disorders. In view of this, the present study investigates the protective effect of FXO on lead acetate (PbAc)-induced renal damage. Rats were pre-fed normal diet and the diet rich in FXO for 14 days, and then, four doses of lead acetate (25 mg/kg body weight) were administered intraperitoneally while still on diet. Various serum parameters, enzymes of carbohydrate metabolism, brush border membrane (BBM), and oxidative stress were analyzed in rat kidney. PbAc nephrotoxicity was characterized by increased serum creatinine and blood urea nitrogen. PbAc increased the activities of lactate dehydrogenase and NADP-malic enzyme, whereas it decreased malate and glucose-6-phosphate dehydrogenase, glucose-6-phosphatase, fructose-1, 6-bisphosphatase, and BBM enzyme activities. PbAc caused oxidant/antioxidant imbalances as reflected by increased lipid peroxidation and decreased activities of superoxide dismutase, glutathione peroxidase, and catalase. In contrast, FXO alone enhanced the enzyme activities of carbohydrate metabolism, BBM, and antioxidant defense system. FXO feeding to PbAc-treated rats markedly enhanced resistance to PbAc-elicited deleterious effects. In conclusion, dietary FXO supplementation ameliorated PbAc-induced specific metabolic alterations and oxidative damage by empowering antioxidant defense mechanism and improving BBM integrity and energy metabolism. 相似文献
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Cells of S. cerevisiae strain "14-12" of different ages were immobilized in sodium alginate and used for conversion of glucose to ethanol. Immobilized cells of 48 hr old were the most potential. Employment of high counts of alginate-entrapped cells shortened the period required for production of the maximal alcohol yield. However, the percentage surviving cells decreased with increasing initial cell counts. Maximal accumulation of ethanol (4.18 g/100 ml) was obtained after 4 days of static fermentation with 1.8 X 10(8) immobilized yeast cells. The residual viable cell count was found to represent 3-fold the surviving percentage in a control experiment using an inoculum of the free yeast cells. Immobilized yeast cells could convert about 85% of the available sugars to ethanol over 28 days of the repeated-batch fermentation. The immobilized cells retained 50% of their viability for 16 days. After 48 days of repeated fermentation only 6% of the yeast cells were viable, and on the 52nd day no viable cells could be detected. 相似文献
6.
Arthur H. L. From Dwight S. Fullerton Khalil Ahmed 《Molecular and cellular biochemistry》1990,94(2):157-165
The structure-activity relationships of the genin moieties of digitalis glycosides are commonly elucidated by determining the inhibitory potency of a variety of genins toward the plasma membrane Na+, K+-ATPase; qualitatively these relationships appear to be fairly independent of the specific Na+, K+-ATPase preparation utilized for the analysis. To determine whether this is the case with regard to the sugar moieties of glycosides, the inhibitory effects of 12 monoglycosides of digitoxigenin toward four Na+, K+-ATPase preparations of different origin were measured. It was found that while recognition of the major structural determinants of sugar activity appeared to be independent of enzyme source, recognition of the minor structural determinants of activity showed some source dependence. It was also observed that the intrinsic sensitivity to sugar potentiation may be source dependent and unrelated to intrinsic sensitivity to inhibition by digitoxigenin. These observations are compatible with a model of the Na+, K+-ATPase sugar binding site(s) in which intrinsic sensitivity to sugar attachment as well as recognition characteristics (for sugar structural features) both determine the extent to which a sugar moiety may contribute to the activity of monoglycosides. Further, in these studies one of the Na+, K+-ATPase preparations employed was obtained from rat brain, a tissue known to contain a mixture of ouabain sensitive and insensitive isoforms. We have observed that the rigorous purification techniques employed appear to have selectively removed from or denatured the less ouabain sensitive al isoform found in this enzyme preparation. 相似文献
7.
Ethanol tolerance ofSaccharomyces cerevisiae and its relationship to lipid content and composition 总被引:2,自引:0,他引:2
Saccharomyces cerevisiae strain 14-12 is a highly ethanol-tolerant organism. It can grow in the presence of 13% ethanol but growth is completely prevented at 14% ethanol. A relationship was detected between yeast lipids and ethanol tolerance. A gradual decrease of lipid content was recorded as the concentration of supplemented ethanol increased. Moreover, free fatty acids were comparatively decreased in these lipid extracts. When separately added to media with 14% ethanol different lipids produced varied stimulatory effects on yeast growth. Maximum yield of yeast growth was obtained at 14% ethanol in the presence of lecithin, palmitic acid and cholesterol. Yeast lipids produced in the presence of these fractions are characterized by a relatively high percentage of free fatty acids. The change in the percentage of free fatty acids was shown to be the controlling factor in ethanol tolerance. 相似文献
8.
J H Romaldini C S Farah R S Werner R P Dall'Antonia Júnior R S Camargo 《Hormones et métabolisme》1988,20(8):510-512
The TSH effect on slice and the incubation medium cyclic AMP levels and T3 and T4 released from 8 autonomously functioning thyroid nodules (AFTN) and their respective perinodular (PN) tissues were examined. The thyroid slices were incubated in Eagle's Medium containing TSH (5 to 100 mU/ml) for 60 min and 300 min for tissue cyclic AMP generation and for cyclic AMP, T3 and T4 release, respectively. Basal cyclic AMP levels were not different either in AFTN and in PN slices or into the incubation medium. In both tissues TSH produced a similar cyclic AMP generation. In contrast, cyclic AMP released into the incubation medium was significantly higher in AFTN than in PN tissues, after TSH stimulation. Basal T3 values and TSH-stimulated T3 release in AFTN were not different from PN tissue. However, basal T4 levels were significantly higher in AFTN than in PN tissue as well as T4 released in response to TSH. In addition, T3/T4 ratio was lower in AFTN than in PN tissues. The cyclic AMP released into the incubation medium correlated with both T3 and T4 release in PN tissue but in the AFTN tissue no correlations were found. These findings suggest that the adenylate cyclase-cyclic AMP system is more sensitive to TSH-stimulation in AFTN when compared with PN tissue and that AFTN tissue has a preferential T4 secretion. 相似文献
9.
Antigenic relatedness between human lecithin-cholesterol acyltransferase and phospholipases of the A2 family 总被引:1,自引:0,他引:1
A monoclonal antibody, B10, generated against pure human lecithin-cholesterol acyltransferase (EC 2.3.1.43) caused the inhibition of the esterolytic and cholesterol esterifying activities of the enzyme. This antibody also reacted with a number of pancreatic and snake venom phospholipases A2 species but not phospholipase A1. A concentration-dependent inhibition of phospholipase A2 was also seen in the presence of B10. Treatment of lecithin-cholesterol acyltransferase or B10-reacting phospholipases with phenacyl bromide, a reagent known to interact with the active site of phospholipase A2, inhibited both their esterolytic activity and their capacity to bind to B10. A dimeric phospholipase A2 species with a known occluded active site did not cross-react with B10. Thus, lecithin-cholesterol acyltransferase and some enzymes of the phospholipase A2 family share a common antigenic determinant which is probably located near or at their esterolytic active site. 相似文献
10.
Glucocorticoid inhibition of immunoreactive beta-endorphin release from the anterior lobe of the rat pituitary: in vitro and in vivo studies 总被引:1,自引:0,他引:1
G P Mueller D J Pettibone J M Farah D Sapun-Malcolm 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1985,179(3):338-347
Glucocorticoid control of pituitary beta-endorphin (beta-END) release was investigated in vitro and in vivo. Cultured cells of both rat anterior (AL) and neurointermediate (NIL) lobe released beta-END-like immunoreactivity (beta-END-LI) in response to epinephrine (10(-7) M); however, only the response of AL cells was prevented by corticosterone (10(-8)-10(-6) M) or dexamethasone (10(-9)-10(-7) M). Gel chromatographic analysis (Sephadex G-50) revealed that the major forms of beta-END-LI released by AL cells corresponded to beta-END and beta-lipotropin (beta-LPH) in molecular size, whereas virtually all of the immunoreactivity released by NIL cells resembled beta-END. In vivo administration of dexamethasone attenuated the stress-induced release of beta-END-LI in a dose- and time-related fashion, having a more pronounced effect on plasma levels of beta-END-LI corresponding to beta-LPH in molecular size. Metyrapone (100 mg/kg), an inhibitor of glucocorticoid synthesis, evoked a rapid (20-40 min) four- to sixfold increase in total plasma beta-END-LI and 75% of this rise was due to immunoreactivity resembling beta-LPH in size. This response was diminished by coadministration of either dexamethasone (0.05-1.25 mg/kg) or corticosterone (0.05-1.25 mg/kg) and completely prevented by 4-hr pretreatment with dexamethasone (50 micrograms/kg). The briskness of the plasma beta-END-LI response to acute changes in glucocorticoid status suggests that a "rapid" feedback mechanism operates in the physiologic control of pituitary beta-END-LI secretion. Moreover, the ability of glucocorticoids to selectively inhibit AL release of beta-END-LI in vitro and their pronounced effect on plasma levels of beta-END-LI resembling beta-LPH, a marker of AL secretion, together indicate that glucocorticoids exert a selective influence over the secretion of AL corticotrophs in vivo. This demonstration of differential regulation of the AL versus IL secretion of beta-END-LI in vivo most likely reflects a phenomena having biologic importance related to the different physiologic actions of the several molecular forms of beta-END-LI secreted by the two tissues. 相似文献