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911.
912.
913.
The p53 pathway and apoptosis. 总被引:17,自引:0,他引:17
914.
S. M. Al-Zahrani 《Bioprocess and biosystems engineering》1999,21(1):57-60
The effects of mixing, the sodium alginate concentration, and calcium chloride concentration on the release of sulphamethoxazole (model drug) impregnated in calcium alginate beads were investigated and evaluated. The release behaviour of the sulphamethoxazole from the calcium alginate beads was studied in a 0.1N HCl aqueous solution at 37v°C. The release rate of the sulphamethoxazole depends heavily on the type of mixers during the formation of the drug-alginate beads. The highest release rate was achieved when four-bladed rectangular agitator was used while the lowest release was achieved when magnetic stirrer was used. The amount of the released sulphamethoxazole varies slightly with the variation of the alginate concentration. The total release of sulphamethoxazole when 1% w/v solution of sodium alginate was used found to be 80% of the total drug content while 72% and 68% of the total drug content for 1.5% and 2% sodium alginate solutions. Three different calcium chloride concentrations were used (i.e., 5%, 10%, and 15% CaCl2). The effect of the calcium chloride concentration on the release of the sulphamethoxazole is very pronounced. 相似文献
915.
The elucidation of the multiple signaling cascades coupled to the TSH receptor has offered new approaches in the understanding of the pathogenesis of Graves' disease. Here we review findings showing that immunoglobulins from Graves' patients are heterogeneous, bind to different epitopes and, similarly to TSH, activate different signaling pathways, including adenylyl cyclase, phospholipase C and phospholipase A2. Evidence that the multiplicity of signals correlates with the different manifestations of the disease is also summarized. We believe that the dissection of the molecular mechanisms involved in the pathogenesis of Graves' disease offers the basis for developing novel therapeutical approaches to this disease. 相似文献
916.
917.
The different banding patterns produced by restriction endonuclease digestion in mitotic chromosomes of the American and European eel 总被引:1,自引:0,他引:1
S. Salvadori † A. M. Deiana E. Coluccia A. Milia ‡ A. Cau 《Journal of fish biology》1997,50(3):668-671
The detection of three classes of C-heterochromatin by in situ restriction endonuclease digestion allowed a karyotype differentiation between the American and the European eel. 相似文献
918.
Effect of precursors on biosynthesis of monensins A and B 总被引:1,自引:0,他引:1
Precursors of monensins (acetate, propionate, butyrate, isobutyrate) affect the total production and the relative proportion of monensins A and B. Addition of propionate into the fermentation medium causes a prevalence of monensin B whereas butyrate and isobutyrate stimulate the production of monensin A and suppress the production of monensin B. 相似文献
919.
920.
D C Rideout M Lambert D A Kendall G R Moe D G Osterman H P Tao I B Weinstein E T Kaiser 《Journal of cellular physiology》1985,124(3):365-371
Four amphiphilic peptides, each with net charges of +2 or more at neutrality and molecular weights under 4 kilodaltons, were found to mediate the adhesion of normal rat kidney fibroblasts to polystyrene surfaces. Two of these peptides, a model for calcitonin (peptide 1, MCT) and melittin (peptide 2, MEL), form amphiphilic alpha-helical structures at aqueous/nonpolar interfaces. The other two, a luteinizing hormone-releasing hormone model (peptide 3, LHM) and a platelet factor model (peptide 4, MPF) form beta-strand structures in amphiphilic environments. Although it contains only 10 residues, LHM mediated adhesion to surfaces coated with solutions containing as little as 10 pmoles/ml of peptide. All four of these peptides were capable of forming monolayers at air-buffer interfaces with collapse pressures greater than 20 dynes/cm. None of these four peptides contains the tetrapeptide sequence Arg-Gly-Asp-Ser, which has been associated with fibronectin-mediated cell adhesion. Ten polypeptides that also lacked the sequence Arg-Gly-Asp-Ser but were nonamphiphilic and/or had net charges less than +2 at neutrality were all incapable of mediating cell adhesion (Pierschbacher and Ruoslahti, 1984). The morphologies of NRK cells spread on polystyrene coated with peptide LHM resemble the morphologies on fibronectin-coated surfaces, whereas cells spread on surfaces coated with MCT or MEL exhibit strikingly different morphologies. The adhesiveness of MCT, MEL, LHM, and MPF implies that many amphiphilic cationic peptides could prove useful as well defined adhesive substrata for cell culture and for studies of the mechanism of cell adhesion. 相似文献