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B.M. Austen R. Lorenz M. Spitz R. Thorpe 《Biochemical and biophysical research communications》1983,116(2):527-533
Two monoclonal antibodies were found to give enhanced affinity for β-lipotropin when mixed, as evidenced by competitive radioimmunoassay. Both monoclonals were found to react with a pentapeptide Ala-Glu-Leu-Glu-Tyr, which is a sequence of high local hydrophilicity within the N-terminal section of β-lipotropin. 相似文献
3.
Preparation of oligodeoxyribonucleoside methylphosphonates on a polystyrene support. 总被引:11,自引:8,他引:3
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P S Miller C H Agris A Murakami P M Reddy S A Spitz P O Ts'o 《Nucleic acids research》1983,11(18):6225-6242
An efficient procedure is described for synthesizing deoxyribonucleoside methylphosphonates on polystyrene polymer supports which involves condensing 5'-dimethoxytrityldeoxynucleoside 3'-methylphosphonates. The oligomers are removed from the support and the base protecting groups hydrolyzed by treatment with ethylenediamine in ethanol, which avoids hydrolysis of the methylphosphonate linkages. Two types of oligomers were synthesized: those containing only methylphosphonate linkages, d-Np(Np)nN, and those which terminate with a 5' nucleotide residue, dNp (Np)nN. The latter oligomers can be phosphorylated by polynucleotide kinase, and are separated by polyacrylamide gel electrophoresis according to their chain length. Piperdine randomly cleaves the oligomer methylphosphonate linkages and generates a series of shorter oligomers whose number corresponds to the length of the original oligomer. Apurinic sites introduced by acid treatment spontaneously hydrolyze to give oligomers which terminate with free 3' and 5' OH groups. These reactions may be used to characterize the oligomers. 相似文献
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A novel experimental method was developed which allows the determination of the threshold concentration of sucrose by use of a linear sucrose gradient in water. With this method a continuous tasting of the test-liquid is possible. A panel of 15 persons experienced in taste-testing was used. Three gradients of different steepness were applied: 0 to 1.5% (w/w) sucrose in 2 min (I), 3 min (II) and 4 min (III). The results of the new method were compared with those of the standard method (DIN). With gradients I and II we found values which were significantly higher than those of the standard method (I: 0.49% (w/w); II: 0.46% (w/w); DIN: 0.31% (w/w)), whereas with gradient III the same threshold value was found as with the DIN-Method (III: 0.32% (w/w)). 相似文献
6.
D R Spitz D T Adams C M Sherman R J Roberts 《Archives of biochemistry and biophysics》1992,292(1):221-227
An H2O2-resistant variant (OC14) of the HA1 Chinese hamster fibroblast cell line which demonstrates a 20-fold increase in catalase activity was utilized in the study of mechanisms responsible for cellular resistance to hydrogen peroxide, oxygen, and 4-hydroxy-2-nonenal toxicity. HA1 and OC14 cells were treated with 9 mM aminotriazole which resulted in a 60 to 80% reduction in catalase activity. Pretreatment with aminotriazole resulted in significant sensitization to the toxicity of 1-h exposures to exogenously applied H2O2, which was proportional to the reduction in catalase activity. Treatment with aminotriazole produced significant sensitization to the toxicity of 95% O2 after 45 h of O2 exposure but no sensitization to the toxicity of a 1-h exposure to 50 microM 4-hydroxy-2-nonenal. Inhibition of catalase activity by aminotriazole had no effect on the metabolism of 4-hydroxy-2-nonenal by either cell line tested. These results support the conclusion that in H2O2-resistant cells, catalase activity is a major determinant of cellular resistance to H2O2 toxicity, whereas catalase activity has a limited role in cellular resistance to an acute exposure to 95% O2 and is unrelated to cellular resistance to 4-hydroxy-2-nonenal. 相似文献
7.
Douglas R. Spitz Michael T. Kinter Robert J. Roberts 《Journal of cellular physiology》1995,165(3):600-609
An H2O2-resistant variant (OC14) of the HA1 Chinese hamster fibroblast cell line, which demonstrates cross resistance to 95% O2 and a 2-fold increase in total glutathione content, was utilized to investigate mechanisms responsible for cellular resistance to H2O2- and O2-toxicity. OC14 and HA1 cells were pretreated with buthionine sulfoximine (BSO) to deplete total cellular glutathione. Following BSO pretreatment, cells were either placed in 250 μM BSO to maintain the glutathione depleted condition and challenged with 95% O2, or challenged with hydroged peroxide in the absence of BSO. Total glutathione and the activities of CuZn superoxide dismutase, Mn superoxide dismutase, catalase, glutathione peroxidase, and glutathione transferase were evaluated immediately following the BSO pretreatment as well as following 39 to 42 hr of exposure to 250 μM BSO. BSO treatment did not cause significant decreases in any cellular antioxidant tested, except total glutathione depletion resulted in significant (P < 0.05) sensitization to O2-toxicity and H2O2-toxicity in both cell lines at every time point tested. However, glutathione depletion did not completely abolish the resistance to either O2- or H2O2-toxicity demonstrated by OC14 cells, relative to HA1 cells. Also, glutathione depletion did not effect the ability of OC14 cells to metabolize extracellular H2O2. These data indicate that glutathione dependent processes significantly contribute to cellular resistance to acute H2O2- and O2-toxicity, but are not the only determinants of resistance in cell lines. The contribition of aldehydes formed by lipid peroxidation in mechanisms involved with the sensitization to O2-toxicity in glutathione depleted cells was tested by measuring the lipid peroxidation byproduct, 4-hydroxy-2-nonenal (4HNE), bound in Schiff-base linkages or in its free form in cell homogenates at 49 hr of 95% O2-exposure. No significant increase in 4HNE was detected in glutathione depleted cells relative to glutathione competent cells, indicating that glutathione depletion does not sensitize these cells to O2-toxicity by altering the intracellular accumulation of free or Schiff-base bound 4HNE. © 1995 Wiley-Liss Inc. 相似文献
8.
The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs. 相似文献
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Elke EM Brouwers Alwin DR Huitema Jos H Beijnen Jan HM Schellens 《BMC clinical pharmacology》2008,8(1):7