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排序方式: 共有410条查询结果,搜索用时 15 毫秒
1.
M Magnani L Chiarantini E Vittoria U Mancini L Rossi A Fazi 《Biotechnology and applied biochemistry》1992,16(2):188-194
The use of adjuvants is usually required to induce strong immunological responses to protein antigens. However, in many cases these adjuvants cannot be extensively applied in human and veterinary vaccinations because of associated inflammatory reactions or granuloma formation. We show here that protein antigens (bovine serum albumin, hog liver uricase, and yeast hexokinase), coupled to autologous red blood cells by way of a biotin-avidin-biotin bridge, elicit an immunological response in mice similar to or higher than that obtained by the use of Freund's adjuvant. Quantities as low as 0.5 micrograms/mouse are high enough to generate these immunological responses. Furthermore, splenocytes of mice immunized by red blood cell-coupled antigens can be used to generate hybridomas secreting monoclonal antibodies. Thus, the delivery of antigens by autologous red blood cells is an effective way to avoid the use of adjuvants for producing anti-peptide antibodies and possibly to generate peptide vaccines. 相似文献
2.
The mechanism by which 2,3'-dideoxycytidine, an inhibitor of HIV-I infectivity, permeates the cell membrane was investigated. The influx of ddCyd into human erythrocytes was nonconcentrative. The initial velocity of both ddCyd influx and efflux was, in contrast to compounds that permeate the cell membrane via the nucleoside transporter, a linear function of nucleoside concentration in the 1 microM to 10 mM range and relatively insensitive to temperature. Furthermore, potent inhibitors of nucleoside transporter and other nucleosides were found to inhibit ddCyd influx only partially or not at all suggesting that ddCyd permeates the human erythrocyte membrane predominantly by nonfacilitated diffusion. This unusual characteristic seems to be due to the lack of 3'-hydroxyl moiety of ddCyd which appears to be an important determinant for the nucleoside carrier specificity rather than to lipid solubility itself. As far as permeation of the cell membrane is concerned ddCyd shares these properties with 2',3'-dideoxythymidine and 3'-azido-3'-deoxythymidine. 相似文献
3.
V Stocchi G Piccoli M Magnani F Palma B Biagiarelli L Cucchiarini 《Analytical biochemistry》1989,178(1):107-117
A simple and fast reversed-phase high-performance liquid chromatographic method has been developed for the complete separation of 35 dimethylaminoazobenzene sulfonyl (DABS)-amino acids and by-products. This method allows simultaneous determination of primary and secondary amino acids which can be present in protein and peptide hydrolysates and also detects the presence of cysteic acid, S-sulfocysteine, hydroxyproline, taurine, norleucine, cystine, and delta-hydroxylysine. The precolumn derivatization of amino acids with dimethylaminoazobenzene sulfonyl chloride (DABS-Cl) is simple and quick (10 min at 70 degrees C) and allows the complete reaction of primary and secondary amino acids. The separation of the compounds under investigation is achieved in 25 min using a reversed-phase 3-microns Supelcosil LC-18 column at room temperature. The versatility of the proposed method is documented by amino acid determination on protein samples obtained using different hydrolysis techniques (HCl, methane-sulfonic acid, and NaOH), with attention given to the detection of tryptophan in protein samples with high sugar concentration. Furthermore, we have reported the experimental conditions necessary to apply this method to the amino acid analysis of very low amount of proteins (1 to 5 micrograms) electroeluted from a stained band after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The stability of DABS-derivatives, the short time of analysis, the high reproducibility and sensitivity of the system, and the complete resolution of all compounds of interest make this method suitable for routine analysis. Furthermore, we have also developed a fast reversed-phase high-performance liquid chromatographic method for the complete separation of dimethylaminoazobenzene thiohydantoin (DABTH)-amino acids. The separation of the compounds under investigation is obtained, at room temperature, in less than 18 min using a reversed-phase Supelcosil LC-18 DB column, 3-micron particles, and also allows the complete separation of DABTH-Ile, DABTH-Leu, and DABTH-Norleu. The short time of analysis, together with the high reproducibility of the system and its sensitivity at picomole levels, make this method very suitable for the identification of DABTH-amino acids released during microsequencing studies of proteins and peptides with the dimethylaminoazobenzene isothiocyanate reagent. In addition, we have shown that it is possible to obtain complete separation of DABTH-amino acids also under isocratic conditions.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
4.
Neurotransmitter, opiodergic system, steroid-hormone interaction and involvement in the replacement therapy of sexual disorders 总被引:1,自引:0,他引:1
G Frajese R Lazzari A Magnani C Moretti V Sforza D Nerozzi 《The Journal of steroid biochemistry and molecular biology》1990,37(3):411-419
Dopamine (DA) and serotonin (5-HT) are the neurotransmitters most directly involved in sexual activity. DA plays a stimulatory role while 5-HT has an inhibitory effect. The two monoaminergic systems modulate the secretion of many hormones (GnRH, LH, testosterone, prolactin and endorphins) involved in sexual functional capacity. Furthermore, hormones influence synthesis and storage of brain neurotransmitters. Impotence can often be associated to clinical depression and altered neurotransmitter function. Moreover, stress represents an unbalance between various neurotransmitter systems and can induce impotence especially when disorders of the endorphinic system are present. Replacement therapy is based upon the understanding of these basic concepts. Impotence due to an underlying depressive illness must be treated with dopaminergic antidepressant drugs; while in stressful conditions a good response to the naloxone test is the preliminary criterion to subsequent naltrexone treatment. When a hormonal deficiency has been proved, the hormone replacement therapy is of course highly effective (gonadotropins in hypogonadotropic syndromes, testosterone in aging, etc.). Finally, idiopathic impotence could be treated by DA agonist and/or 5-HT antagonist drugs either alone or better yet in association with psychotherapy. 相似文献
5.
EPITHELIAL CELL PENETRATION AS AN ESSENTIAL STEP IN THE PATHOGENESIS OF BACILLARY DYSENTERY. 总被引:148,自引:11,他引:137
LaBrec, Eugene H., Herman Schneider, Thomas J. Magnani, and Samuel B. Formal. Epithelial cell penetration as an essential step in the pathogenesis of bacillary dysentery. J. Bacteriol. 88:1503-1518. 1964.-A parent strain of Shigella flexneri 2a and a colonial mutant derived from it were studied in three animal models. Both strains were equally virulent for mice when living cells suspended in hog gastric mucin were injected by the intraperitoneal route. Feeding the parent strain to starved guinea pigs, followed by the intraperitoneal injection of opium, resulted in the formation of ulcerative lesions in the intestinal tract and in the death of these animals. When the colonial variant was fed to similarly prepared animals, the animals survived and the intestinal tract remained normal. The parent produced diarrheal symptoms and intestinal lesions after its oral administration to rhesus monkeys; the variant caused neither symptoms nor pathology in this species. Studies were carried out to define the characteristics present in the parent strain and absent in the colonial mutant, which would enable the parent to produce ulcerative lesions of the bowel and death in the guinea pig model or intestinal lesions and diarrheal symptoms in the monkey. Neither serological studies nor growth studies conducted both in vitro and in vivo offered a clue to explain this difference. The virulent parent strain was shown to penetrate the bowel epithelium and enter the lamina propria; the avirulent mutant did not do this. Entrance to the lamina propria was by way of the epithelial cell of the mucosa. The avirulent mutant did not possess the capacity to penetrate this cell. This observation was extended to show that the virulent parent possesses the ability to infect and multiply within HeLa cells; furthermore, the organisms are able to penetrate epithelial cells of the guinea pig cornea, causing ulcerative lesions. The avirulent variant possesses neither of these capacities. It is suggested that epithelial cell penetration is a major factor in determining the pathogenicity of dysentery bacilli. 相似文献
6.
F. Solimano G. I. Bischi M. Bianchi L. Rossi M. Magnani 《Bulletin of mathematical biology》1990,52(6):785-796
A non-linear three-compartment model is proposed to describe a new strategy for the administration of 2′,3′-dideoxycytidine
(ddCyd) in the treatment of HIV infections. The drug is injected after having been encapsulated in a non-diffusible form (ddCMP)
into erythrocytes. Nummerical solutions show that by this treatment the highest ddCyd blood concentration is strongly reduced
and in turn its toxicity, while long-lasting therapeutic effect is assured. The model is compared with experimental data in
vitro. 相似文献
7.
The effects of the trichothecene mycotoxins (acetyl T-2 toxin, T-2 toxin, HT-2 toxin, palmityl T-2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON), and T-2 tetraol) on bovine platelet function were examined in homologous plasma stimulated with platelet activating factor (PAF). The mycotoxins inhibited platelet function with the following order of potency: acetyl T-2 toxin > palmityl T-2 toxin = DAS > HT-2 toxin = T-2 toxin. While T-2 tetraol was completely ineffective as an inhibitor, DON exhibited minimal inhibitory activity at concentrations above 10×10?4M. The stability of the platelet aggregates formed was significantly reduced in all mycotoxin treated platelets compared to that of the untreated PAF controls. It is suggested that the increased sensitivity of PAF stimulated bovine platelets to the more lipophilic mycotoxins may be related to their more efficient partitioning into the platelet membrane compared to the more hydrophilic compounds. 相似文献
8.
Magnani P. Paganelli G. Siccardi A. G. Songini C. Colombo P. Faglia G. Fazio F. 《Cell biochemistry and biophysics》1994,24(1-3):307-313
For various pituitary adenomas, it has been demonstrated that somatostatin receptor can be present. Pilot studies have shown
that radio-indium labeled pentetreotide allows very good scintigraphic localization of somatostatin receptor-bearing cell
masses. Recently, the presence of CgA in pituitary adenomas has also been demonstrated. MAb A11, raised against CgA, has been
successfully used with a three-step ISG for the diagnosis of neuroendocrine tumors. Therefore the combined use of three-step
ISG with MAb A11 and radiolabeled somatostatin can be useful in the diagnosis of pituitary adenomas. Twelve patients, 5 secreting
(group A) and 7 nonsecreting (group B) pituitary adenomas, were enrolled in the study. All patients underwent three-step ISG,
and, 2 wk later, scintigraphy with111In-labeled pentetreotide (Octreoscan). Three-step ISG consisted of iv injection of 1 mg of biotinylated MAb A11 (first step),
followed by 10 mg of avidin (second step) and [99mTc]PnAO-biotin (third step). Tomographic imaging were acquired for three-step ISG and Octreoscan at 2 and 4 h after radiotracer
injection, respectively. The results are the following: 2 patients of group A (secreting tumors) had a positive three-step
ISG, whereas all the patients but one of the same group had a positive pentetreotide study; all the patients of group B (nonsecreting
tumors) had a positive three-step ISG and 4 had a positive pentetreotide scintigraphy. These data suggest the utility of the
combined use of these techniques for a better diagnosis of pituitary adenomas. 相似文献
9.
Laura Chiarantini Luigia Rossi Alessandra Fraternale Mauro Magnani 《Molecular and cellular biochemistry》1995,144(1):53-59
Human and murine blood cells treated with ZnCl2 and bis(sulfosuccinimidyl)suberate (BS3) (a cross linking agent) undergo band 3 clustering and binding of hemoglobin to red blood cell membrane proteins. These clusters induce autologous IgG binding and complement fixation, thus favouring the phagocytosis of ZnCl2/BS3 treated cells by macrophages. The extension of red blood cell opsonization can be easily modulated by changing the ZnCl2 concentration in the 0.1–1.0 mM range thus providing an effective way to affect blood cell recognition by macrophages. In fact, murine erythrocytes treated with increasing ZnCl2 concentrations have proportionally reduced survivals when reinjected into the animal. Furthermore, the organ sequestration of ZnCl2/BS3 treated cells strongly resembles the typical distribution of the senescent cells. Since the ZnCl2/BS3 treatment can also be performed on red blood cells loaded with drugs or other substances, this procedure is an effective drug-targeting system to be used for the delivery of molecules to peritoneal, liver and spleen macrophages. 相似文献
10.
Mauro Magnani Vilberto Stocchi Marina Dachà Giorgio Fornaini 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1984,804(2):145-153
The true level of hexokinase in rabbit erythrocytes was determined by three different methods, including the spectrophotometric glucose-6-phosphate dehydrogenase coupled assay and a new radioisotopic assay. The value found at 37°C (pH 7.2) was 10.23±1.90 μmol/h per ml red blood cells, which is lower than previously reported values. More than 40 cellular components of the rabbit erythrocytes were tested for their effects on the enzyme. Their intracellular concentrations were also determined. Several of these compounds were found to be competitive inhibitors of the enzyme with respect to Mg·ATP2?. Furthermore, reduced glutathione at a concentration of 1 mM was able to maintain hexokinase in the reduced state with full catalytic activity. The ability of orthophosphate to remove the inhibition of some phosphorylated compounds was examined under conditions similar to cellular (pH 7.2 and 50 μM of orthophosphate) and found to be of no practical interest. In contrast, the binding of ATP4? and 2,3-diphosphoglycerate to the rabbit hemoglobin significantly modifies their intracellular concentrations and the formation of the respective Mg complexes. The pH-dependence of the reaction velocity and of the kinetic properties of the enzyme in different buffer systems were also considered. This information was computerized, and the rate of glucose phosphorylation in the presence of the mentioned compounds was determined. The value obtained, 1.94±0.02 μmol/h per ml red blood cells, is practically identical to the measured rate of glucose utilization by intact rabbit erythrocytes (1.92±0.3 μmol/h per ml red blood cells). These results provide further evidence for the central role of hexokinase in the regulation of red blood cell glycolysis. 相似文献