[Effects of M-nifedipine on contractile responses in isolated atria and coronary vessels: a comparison with nifedipine].
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Animals↗
Biomedical subjects
X Zou
Publications and source records attributed to X Zou.
Protein changes associated with ionizing radiation-induced apoptosis in human prostate epithelial tumor cells.
Ionizing radiation (IR) is an important component in the therapy of localized prostate cancer. Identification of protein alterations during IR-induced apoptosis prostate cancer cells is an important step toward understanding the new metabolic status of the dying cell. In the present study, we report changes in protein profile that define the execution phase of the apoptotic response in the in vitro model of tumorigenic radiation-transformed SV40-immortalized human prostate epithelial cells (267B1-XR), induced to undergo programmed cell death by IR. We employed an approach that involves use of analytical two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) coupled with Western blotting with specific antisera. Our results point out that apoptotic cells experience significant reduction in the levels of the intermediate filament proteins, keratins-18, 19, vimentin and the associated 14-3-3 adapter proteins. At the same time, molecular chaperones such as glucose-regulated protein 94, calreticulin, calnexin, and protein disulfide isomerase exhibit marked accumulation in these dying cells. The present data indicate that apoptosis-associated processes in prostate epithelial cells include solubilization of the rigid intermediate filament network by specific proteolysis as well as increased levels of endoplasmic reticulum (ER) proteins with chaperone functions.
Apoptosis↗
Thermolysis of coenzymes B12 at physiological temperatures: activation parameters for cobalt-carbon bond homolysis and a quantitative analysis of the perturbation of the homolysis equilibrium by the ribonucleoside triphosphate reductase from Lactobacillus leichmannii.
The kinetics of the thermolysis of 5'-deoxyadenosylcobalamin (AdoCbl, coenzyme B12) in aqueous solution, pH 7.5, have been studied in the temperature range 30-85 degrees C using AdoCbl tritiated at the adenine C2 position and the method of initial rates. Combined with a careful analysis of the distribution of adenine-containing products, the results permit the dissection of the competing rate constants for carbon-cobalt bond homolysis and heterolysis. After correction for the temperature-dependent occurrence of the much less reactive base-off species of AdoCbl, the activation parameters for homolysis of the base-on species were found to be delta H++homo,on = 33.8 +/- 0.2 kcal mol-1 and delta S++homo,on = 13.5 +/- 0.7 cal mol-1 K-1, values not significantly different from those determined by Hay and Finke (J. Am. Chem. Soc. 108 (1986) 4820), in the temperature range 85-115 degrees C. In contrast, the heterolysis of base-on AdoCbl was characterized by a much smaller enthalpy of activation (delta H++het,on = 18.5 +/- 0.2 kcal mol-1) and a negative entropy of activation (delta S++het,on = -34.0 +/- 0.7 cal mol-1 K-1) so that heterolysis, which is minor pathway at elevated temperatures, is the dominant pathway for AdoCbl decomposition at physiological temperatures. Using literature values for the rate constant for the reverse reaction, the equilibrium constant for AdoCbl homolysis at 37 degrees C was calculated to be 7.9 x 10(-18). Comparison with the equilibrium constant for this homolysis at the active site of the ribonucleoside triphosphate reductase from Lactobacillus leichmannii shows that the enzymes shifts the equilibrium constant towards homolysis products by a factor of 2.9 x 10(12) (17.7 kcal mol-1) by binding the thermolysis products with an equilibrium constant of 7.1 x 10(16) M-2, compared to the bonding constant for AdoCbl of 2.4 x 10(4) M-1.
Binding Sites↗