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Despite being highly effective for newly diagnosed chronic myeloid leukemia (CML), imatinib not only is inactive against quiescent CML stem cells, but also has limited activity against blast crisis (BC) CML. The relative activity of Bcr-Abl and the expression levels of antiapoptotic proteins in proliferating and quiescent CD34+ BC CML progenitor cells and the effects of targeting antiapoptotic proteins in these cells are unknown. Here we report higher levels of p-CrkL in quiescent than in proliferating CD34+ progenitor cells and comparable expression levels of Bcl-2, Bcl-xL, Mcl-1 and XIAP in the two populations in BC CML. Inhibition of Bcl-2/Bcl-xL by ABT-737 in cells from patients with tyrosine kinase inhibitor (TKI)-resistant BC CML promoted apoptosis in quiescent CD34+ progenitor cells with an efficacy similar to that in proliferating cells. Combination of ABT-737 with imatinib (which decreases Mcl-1 levels) or triptolide (which decreases Mcl-1 and XIAP) synergistically induced death of both proliferating and quiescent CD34+ progenitor cells obtained from TKI-resistant BC CML patients. These results suggest that antiapoptotic proteins are critical targets in BC CML and that activation of apoptosis signaling can eliminate both proliferating and quiescent CD34+ progenitor cells in BC CML, independent of response to TKIs. [ABSTRACT FROM AUTHOR]

In order to investigate the pharmacological basis of 'Yang-invigorating' action, the effect of oral treatment with the methanolic extract of 'Yang-invigorating' herbs on ATP-generation capacity was examined, using heart homogenates prepared from herb-pretreated mice. Tonifying (i.e., health-promoting) herbs of other functional categories were also included for comparison. The results indicated that 'Yang-invigorating' Chinese tonifying herbs could invariably enhance myocardial ATP-generation capacity, with the extent of stimulation varying among the herbs. In contrast, 'Yin-nourishing' herbs either did not stimulate or even decreased myocardial ATP-generation capacity. While 'Qi-invigorating' herbs produced variable effects on myocardial ATP-generation capacity, most of the 'blood-enriching' herbs did not cause any significant changes. The results obtained from studies using myocardial mitochondrial fractions isolated from herb-pretreated mice suggest that 'Yang-invigorating' herbs might speed up ATP generation by increasing mitochondrial electron transport. The ensemble of results has provided evidence for the first time to support the pharmacological basis of 'Yang invigoration' in Chinese medicine.

The effects of short-term (2-week) diabetes on myocardial ischemia-reperfusion (I-R) injury and associated changes in myocardial non-enzymatic antioxidant level were examined. Isolated-perfused hearts prepared from control and diabetic rats were subjected to increasing periods of ischemia and reperfusion, and myocardial I-R injury was assessed by measuring the extent of lactate dehydrogenase (LDH) leakage and contractile force recovery. While a brief period (20 min) of post-ischemic reperfusion caused a smaller extent of LDH leakage, the prolonged period (40 min) of reperfusion produced a greater degree of I-R injury in diabetic hearts, as indicated by the impaired recovery of contractile force. The apparent protection against I-R injury in diabetic hearts during the early phase of post-ischemic reperfusion was associated with increases in myocardial reduced glutathione/ascorbic acid and a-tocopherol levels, with the effect on a-tocopherol being most prominent. Insulin treatment could reverse the diabetes-associated changes in susceptibility to myocardial I-R injury and antioxidant response. The ensemble of results indicates that the myocardium isolated from short-term diabetic rat can produce a beneficial antioxidant response to I-R challenge, which may, in turn, be attributable to the decreased susceptibility to I-R injury observable during the early phase of reperfusion.

The streptozotocin-induced short-term (2 week) diabetic rats showed an increase in susceptibility to carbon tetrachloride (CCl4)-induced hepatocellular damage. This diabetes-induced change was associated with a marked impairment in the hepatic glutathione antioxidant/detoxification response to CCl4 challenge, as indicated by the abrogation of the increases in hepatic reduced glutathione (GSH) level, glucose-6-phosphate dehydrogenase and microsomal glutathione S-transferases (GST) activities upon challenge with increasing doses of CCl4. While the hepatic GSH level was increased in diabetic rats, the hepatic mitochondrial GSH level and Se-glutathione peroxidase activity were significantly reduced. Insulin treatment could reverse most of the biochemical alterations induced by diabetes. Both insulin and schisandrin B (Sch B) pretreatments protected against the CCl4 hepatotoxicity in diabetic rats. The hepatoprotection was associated with improvement in hepatic glutathione redox status in both cytosolic and mitochondrial compartments, as well as the increases in hepatic ascorbic acid level and microsomal GST activity. The ensemble of results suggests that the diabetes-induced impairment in hepatic mitochondrial glutathione redox status may at least in part be attributed to the enhanced susceptibility to CCl4 hepatotoxicity. Sch B may be a useful hepatoprotective agent against xenobiotics-induced toxicity under the diabetic conditions.

Effects of Schisandrin B (Sch B) and alpha-tocopherol (alpha-TOC) on ferric chloride (Fe3+) induced oxidation of erythrocyte membrane lipids in vitro and carbon tetrachloride (CCl4) induced lipid peroxidation in vivo were examined. While alpha-TOC could produce prooxidant and antioxidant effect on Fe(3+)-induced lipid peroxidation, Sch B only inhibited the peroxidation reaction. Pretreatment with alpha-TOC (3 mmol/kg/day x 3) did not protect against CCl4-induced lipid peroxidation and hepatocellular damage in mice, whereas Sch B pretreatment (0.3 mmol/3.0 mmol/kg/day x 3) produced a dose-dependent protective effect on the CCl4-induced hepatotoxicity. The ensemble of results suggests that the ability of Sch B to inhibit lipid peroxidation, while in the absence of pro-oxidant activity, may at least in part contribute to its hepatoprotective action.

Changes in tissue glutathione antioxidant system in streptozotocin-induced diabetic rats for a period of 15 weeks were examined. Total glutathione level was significantly increased in kidney tissue, but were slightly decreased and increased in liver and heart tissues, respectively. The small changes in total glutathione level in the liver and heart, though not statistically significant, were associated with reciprocal alterations in the activity of gamma-glutamylcysteine synthetase (GCS). While the GCS activity was not changed in kidney tissue, the activity of gamma-glutathione peroxidase was significantly increased in kidney tissue. Insulin treatment could completely or partly normalize almost all of these changes induced by diabetes. However, the decrease in hepatic glutathione S-transferases activity in diabetic rats was not reversed by the insulin treatment. The ensemble of results suggests that the diabetes-induced alterations in tissue glutathione antioxidant system may possibly reflect an inter-organ antioxidant response to a generalized increase in tissue oxidative stress associated with diabetes.

Effects of Sheng Mai San (SMS), a traditional Chinese medicine used for the treatment of coronary heart disease, and the lignan-enriched extract of Fructus Schisandrae (FS), an antioxidant component of SMS, were examined in an in vivo model of myocardial infarction and an ex vivo model of myocardial ischemia-reperfusion injury in rats. Pretreatment with SMS (12 g/kg/day × 3, p. o.) or FS extract (0.8 g/kg/day × 3, p. o.) was found to protect against the isoproterenol-induced myocardial injury in rats and the ischemia-reperfusion injury in isolated perfused hearts prepared from the pretreated animals. Pretreatment with α-tocopherol (0.8 g/kg/day × 3, p. o.) produced similar beneficial effect on the myocardium. The myocardial protection afforded by SMS pretreatment is likely, at least in part, mediated by the FS-derived antioxidant activity., (Copyright © 1996 Gustav Fischer Verlag · Stuttgart · Jena · New York. Published by Elsevier GmbH.. All rights reserved.)

Treatment of rats with a lignan-enriched extract of the fruit of Schisandra chinensis could enhance hepatic antioxidant/detoxification system, as indicated by increases in hepatic reduced glutathione (GSH) level as well as hepatic glutathione reductase and glutathione S-transferase activities. The hepatoprotective action was evident after aflatoxin beta 1 or cadmium chloride (Cd) challenge. Schisandra chinensis pretreatment protected against aflatoxin B1-or Cd-induced hepatocellular damage in rats. However, pretreating rats with alpha-tocopherol acetate (vitamin E) did not protect against hepatic damage induced by both toxins. Results from the present as well as our previous studies demonstrate that the hepatoprotection afforded by Schisandra chinensis pretreatment is not hepatotoxin specific. Schisandra chinensis seems to be more effective than vitamin E in protecting against aflatoxin B1 and Cd toxicity. The mechanism of hepatoprotection afforded by Schisandra chinensis pretreatment may involve facilitation of both antioxidant and detoxification processes in the liver.

Exposure of liver homogenates to an in vitro tert-butyl hydroperoxide challenge can be used as a means for measuring the reduced glutathione regeneration capacity (GRC) of hepatic tissues. Pretreatment of rats with a lignan-enriched extract of Fructus Schisandrae (FS) caused a moderate enhancement of hepatic GRC in control rats, but the GRC enhancing effect of FS pretreatment on hepatic tissues was greatly exaggerated after CCl4 challenge. This in vitro bioassay can be used for investigating the hepatic GRC promoting action of orally active agents.