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951.
Conformational exchange has been demonstrated within the regulatory domain of calcium-saturated cardiac troponin C when bound to the NH2-terminal domain of cardiac troponin I-(1-80), and cardiac troponin I-(1-80)DD, having serine residues 23 and 24 mutated to aspartate to mimic the phosphorylated form of the protein. Binding of cardiac troponin I-(1-80) decreases conformational exchange for residues 29, 32, and 34. Comparison of average transverse cross correlation rates show that both the NH2- and COOH-terminal domains of cardiac troponin C tumble with similar correlation times when bound to cardiac troponin I-(1-80). In contrast, the NH2- and COOH-terminal domains in free cardiac troponin C and cardiac troponin C bound cardiac troponin I-(1-80)DD tumble independently. These results suggest that the nonphosphorylated cardiac specific NH2 terminus of cardiac troponin I interacts with the NH2-terminal domain of cardiac troponin C.  相似文献   
952.
This study investigated the ability of pretreatment variables from three different domains (social-demographic, psychological, and psychophysiological) to predict posttreatment mean arterial pressure (MAP) for 59 unmedicated males with mild hypertension who were participating in a cross-cultural (USA-USSR) comparison of autogenic training and thermal biofeedback to a self-relaxation control. The overall multiple regression equation consisted of two variables and indicated that higher diastolic blood pressures during a cold pressor task were predictive of greater MAP reductions while higher scores on the Irritability subscale of the Buss-Durkee Hostility Scale were predictive of less MAP reductions. Suggestions for future research in this area are provided.  相似文献   
953.
Calcium channel blockers, verapamil, nitrendipin and nifedipin, and cyclosporin A inhibited growth of colonies ofBotrytis cinerea in a concentration-dependent manner and simultaneously induced morphological changes of its hyphal tips. Exogenous calcium at the concentration of 100 mmol/L decreased the growth-inhibitory effects of channel blockers and cyclosporin A; however, at the concentration of 500 mmol/L Ca2+ their inhibitory effects were increased. At the latter concentration, calcium partly reversed the morphogenic effects of the blockers but not of cyclosporin A.  相似文献   
954.
Human umbilical vein endothelial cells were grown to confluence, as first passage cells, on coverslips. Treatment with ionomycin or histamine caused a sustained rise in intracellular Ca2+ (measured by Fura-2 fluorescence), but after treatment with thrombin, only a transient rise in Ca2+ was observed. Furthermore, the addition of thrombin after ionomycin or histamine lowered the raised Ca2+ back to near control levels. This effect of thrombin was concentration dependent, with increasing concentrations producing increases in both the rate and extent of the lowering of Ca2+. A similar effect of thrombin was seen on video imaging of Fura-2-loaded cell monolayers. The Ca2(+)-lowering effect of thrombin was not mimicked by phorbol 12-myristate 13-acetate nor blocked by staurosporine, indicating a lack of involvement of protein kinase C; intracellular pH also does not appear to be involved. The mechanism by which thrombin lowers cytoplasmic Ca2+ is due mainly to inhibition of Ca2+ entry since thrombin prevented the stimulated influx of Mn2+ caused by histamine or ionomycin. It may therefore be that in vivo under certain physiological or pathological conditions, thrombin's effects on intracellular Ca2+ are more transient than those of histamine, and thrombin also may induce transience in histamine's actions.  相似文献   
955.
The involvement of gibberellins in the control of flowering of sunflower was studied by direct application of GA3 to the apex of the plants, analysis of the endogenous levels of gibberellin-like substances at different plant ages, and indirectly by the application of paclobutrazol, an inhibitor of gibberellin synthesis. GA3 speeded-up flower initiation and floral apex development. The time of GA3 application was more critical than the amount of GA3 applied. The endogenous levels of gibberellin-like compounds increased significantly by day 15 after sowing. The application of paclobutrazol markedly delayed floral initiation and this effect was also depedent on plant age. Both GA3 and paclobutrazol had their greatest effects between 10 and 20 days after sowing suggesting that an increase in gibberellins in that time period plays a role in floral initiation.  相似文献   
956.
957.
Arginine vasopressin (AVP) concentrations were determined in plasma and in cerebrospinal fluid (CSF) in 8 adult male patients suffering from hydrocephalus of various etiologies, before and after intravenous administration of 10 mg metoclopramide. Metoclopramide was able to increase the plasma (2.6 +/- 0.2 ng/l in basal conditions and 6.1 +/- 0.6 ng/l at 30 min) but not the CSF AVP levels. The results suggest that the neurons which secrete AVP into the CSF may be functionally different from those secreting into the peripheral circulation.  相似文献   
958.
959.
beta-hydroxypropionaldehyde (3-HPA) can be oxidized to acrylic acid, an industrially important chemical used in the manufacture of synthetic plastics and other polymers. Of 19 genera and 55 strains tested, 3 Klebsiella and 2 Enterobacter strains produced 3-HPA. The most efficient strain was Klebsiella pneumoniae NRRL B-4011. Under optimum conditions (28 degrees C; 40 g of semicarbazide hydrochloride per liter, 70 g of glycerol per liter; and pH 6.0), 3.1 g of B-4011 cells per liter accumulated 22 g of 3-HPA per liter at a specific rate of 0.83 g/g per h; however, 14.5 g of cells per liter accumulated 46 g of 3-HPA per liter at a specific rate of 0.41 g/g per h.  相似文献   
960.
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