Supplementation with psyllium seed husk reduces myocardial damage in a rat model of ischemia/reperfusion

BACKGROUND/OBJECTIVES: Myocardial infarction (MI) is caused by extensive myocardial damage attributed to the occlusion of coronary arteries. Our previous study in a rat model of ischemia/reperfusion (I/R) demonstrated that administration of arabinoxylan (AX), comprising arabinose and xylose, protects against myocardial injury. In this study, we undertook to investigate whether psyllium seed husk (PSH), a safe dietary fiber containing a high level of AX (> 50%), also imparts protection against myocardial injury in the same rat model. MATERIALS/METHODS: Rats were fed diets supplemented with PSH (1, 10, or 100 mg/kg/d) for 3 d. The rats were then subjected to 30 min ischemia through ligation of the left anterior descending coronary artery, followed by 3 h reperfusion through release of the ligation. The hearts were harvested and cut into four slices. To assess infarct size (IS), an index representing heart damage, the slices were stained with 2,3,5-triphenyltetrazolium chloride (TTC). To elucidate underlying mechanisms, Western blotting was performed for the slices. RESULTS: Supplementation with 10 or 100 mg/kg/d of PSH significantly reduces the IS. PSH supplementation (100 mg/kg/d) tends to reduce caspase-3 generation and increase BCL-2/BAX ratio. PSH supplementation also upregulates the expression of nuclear factor erythroid 2-related factor 2 (NRF2), and its target genes including antioxidant enzymes such as glutathione S-transferase mu 2 (GSTM2) and superoxide dismutase 2 (SOD2). PSH supplementation upregulates some sirtuins (NAD+-dependent deacetylases) including SIRT5 (a mitochondrial sirtuin) and SIRT6 and SIRT7 (nuclear sirtuins). Finally, PSH supplementation upregulates the expression of protein kinase A (PKA), and increases phosphorylated cAMP response element-binding protein (CREB) (pCREB), a target protein of PKA. CONCLUSIONS: The results from this study indicate that PSH consumption reduces myocardial I/R injury in rats by inhibiting the apoptotic cascades through modulation of gene expression of several genes located upstream of apoptosis. Therefore, we believe that PSH can be developed as a functional food that would be beneficial in the prevention of MI.

Protection of the brain through supplementation with larch arabinogalactan in a rat model of vascular dementia

BACKGROUND/OBJECTIVES: Vascular dementia (VaD) caused by reduced blood supply to the brain manifests as white matter lesions accompanying demyelination and glial activation. We previously showed that arabinoxylan consisting of arabinose and xylose, and arabinose itself attenuated white matter injury in a rat model of VaD. Here, we investigated whether larch arabinogalactan (LAG) consisting of arabinose and galactose could also reduce white matter injury. MATERIALS/METHODS: We used a rat model of bilateral common carotid artery occlusion (BCCAO), in which the bilateral common carotid arteries were exposed and ligated permanently with silk sutures. The rats were fed a modified AIN-93G diet supplemented with LAG (100 mg/kg/day) for 5 days before and 4 weeks after being subjected to BCCAO. Four weeks after BCCAO, the pupillary light reflex (PLR) was measured to assess functional consequences of injury in the corpus callosum (cc). Additionally, Luxol fast blue staining and immunohistochemical staining were conducted to assess white matter injury, and astrocytic and microglial activation, respectively. RESULTS: We showed that white matter injury in the the cc and optic tract (opt) was attenuated in rats fed diet supplemented with LAG. Functional consequences of injury reduction in the opt manifested as improved PLR. Overall, these findings indicate that LAG intake protects against white matter injury through inhibition of glial activation. CONCLUSIONS: The results of this study support our hypothesis that cell wall polysaccharides consisting of arabinose are effective at protecting white matter injury, regardless of their origin. Moreover, LAG has the potential for development as a functional food to prevent vascular dementia.

Apple pectin, a dietary fiber, ameliorates myocardial injury by inhibiting apoptosis in a rat model of ischemia/reperfusion

BACKGROUND/OBJECTIVE: Myocardial cell death due to occlusion of the coronary arteries leads to myocardial infarction, a subset of coronary heart disease (CHD). Dietary fiber is known to be associated with a reduced risk of CHD, the underlying mechanisms of which were suggested to delay the onset of occlusion by ameliorating risk factors. In this study, we tested a hypothesis that a beneficial role of dietary fiber could arise from protection of myocardial cells against ischemic injury, manifested after occlusion of the arteries. MATERIALS/METHODS: Three days after rats were fed apple pectin (AP) (with 10, 40, 100, and 400 mg/kg/day), myocardial ischemic injury was induced by 30 min-ligation of the left anterior descending coronary artery, followed by 3 hr-reperfusion. The area at risk and infarct area were evaluated using Evans blue dye and 2,3,5-triphenyltetrazolium chloride (TTC) staining, respectively. DNA nicks reflecting the extent of myocardial apoptosis were assessed by TUNEL assay. Levels of cleaved caspase-3, Bcl-2, and Bax were assessed by immunohistochemistry. RESULTS: Supplementation of AP (with 100 and 400 mg/kg/day) resulted in significantly attenuated infarct size (IS) (ratio of infarct area to area at risk) by 21.9 and 22.4%, respectively, in the AP-treated group, compared with that in the control group. This attenuation in IS showed correlation with improvement in biomarkers involved in the apoptotic cascades: reduction of apoptotic cells, inhibition of conversion of procaspase-3 to caspase-3, and increase of Bcl-2/Bax ratio, a determinant of cell fate. CONCLUSIONS: The findings indicate that supplementation of AP results in amelioration of myocardial infarction by inhibition of apoptosis. Thus, the current study suggests that intake of dietary fiber reduces the risk of CHD, not only by blocking steps leading to occlusion, but also by protecting against ischemic injury caused by occlusion of the arteries.

Apple pectin, a dietary fiber, ameliorates myocardial injury by inhibiting apoptosis in a rat model of ischemia/reperfusion

BACKGROUND/OBJECTIVE: Myocardial cell death due to occlusion of the coronary arteries leads to myocardial infarction, a subset of coronary heart disease (CHD). Dietary fiber is known to be associated with a reduced risk of CHD, the underlying mechanisms of which were suggested to delay the onset of occlusion by ameliorating risk factors. In this study, we tested a hypothesis that a beneficial role of dietary fiber could arise from protection of myocardial cells against ischemic injury, manifested after occlusion of the arteries. MATERIALS/METHODS: Three days after rats were fed apple pectin (AP) (with 10, 40, 100, and 400 mg/kg/day), myocardial ischemic injury was induced by 30 min-ligation of the left anterior descending coronary artery, followed by 3 hr-reperfusion. The area at risk and infarct area were evaluated using Evans blue dye and 2,3,5-triphenyltetrazolium chloride (TTC) staining, respectively. DNA nicks reflecting the extent of myocardial apoptosis were assessed by TUNEL assay. Levels of cleaved caspase-3, Bcl-2, and Bax were assessed by immunohistochemistry. RESULTS: Supplementation of AP (with 100 and 400 mg/kg/day) resulted in significantly attenuated infarct size (IS) (ratio of infarct area to area at risk) by 21.9 and 22.4%, respectively, in the AP-treated group, compared with that in the control group. This attenuation in IS showed correlation with improvement in biomarkers involved in the apoptotic cascades: reduction of apoptotic cells, inhibition of conversion of procaspase-3 to caspase-3, and increase of Bcl-2/Bax ratio, a determinant of cell fate. CONCLUSIONS: The findings indicate that supplementation of AP results in amelioration of myocardial infarction by inhibition of apoptosis. Thus, the current study suggests that intake of dietary fiber reduces the risk of CHD, not only by blocking steps leading to occlusion, but also by protecting against ischemic injury caused by occlusion of the arteries.

The Effect of Extract of Paeonia lactiflora on the Improvement of Ischemic Acute Renal Failure / 대한신장학회지

PURPOSE:The present study was undertaken to investigate whether the extract or the ethyl acetate fraction of Paeonia lactiflora, which improves cell survival under ischemic condition by inhibiting apoptosis, can prevent ischemic acute renal failure, using rats as an animal model. METHODS:In the control group, ischemia/reperfusion (I/R) injury was induced in male Sprague-Dawley rats by clamping of left renal pedicle for 45 minutes after removal of the right kidney, and subsequent reperfusion of the pedicle for 24 hours. In the experimental group, the water extract or ethyl acetate fraction of methanol extract Paeonia lactiflora was injected 1 hour prior to ischemia/reperfusion injury. We measured serum concentrations of creatinine at 24 hours after I/R injury. And the kidneys were extracted, fixed in a 10 % neutral-buffered formalin solution, embedded in paraffin and used for histopathological examination. RESULTS:Rats in the experimental group, treated with water extract or ethyl acetate fraction of methanol extract of Paeonia lactiflora, exhibited significant decrease in the serum concentrations of creatinine (approx. 2.0 mg/dL), compared with those in the control group (approx. 4.0 mg/dL). Finally, the cell morphology of the kidney of rats treated with ethyl acetate fraction of Paeonia lactiflora was well preserved, when judged from histopathological point of view. CONCLUSION:Pretreatment of rats with the water extract or ethyl acetate fraction of Paeonia lactiflora might be beneficial for the treatment of acute renal failure in humans.

Effect of Combination of Anticancer Agents and Nitroimidazoles on the Survival of Human Hepatocellular Carcinoma Cells under Hypoxic Conditions

PURPOSE: In a previous study, we have shown that anticancer agents inhibiting topoisomerases improve survival of tumor cells under hypoxic condition. In the present study, we evaluated whether and how cell survival effect of the anticancer agents under hypoxic conditions could be eliminated by the addition of nitroimidazoles, a class of bioreductive agents. METHODS: Human hepatocellular carcinoma cells (HepG2) were incubated with different combinations of pimonidazole (1~1,000 microg/ml) and doxorubicin (0.1 or 1 microg/ml) concentrations under different O2 concentrations [1, 3, 5, 10 and 21 O2]. Then cell numbers, glucose concentrations and lactic acid concentrations in the medium were measured, and DNA fragmentation assay was performed. Finally, different combinations of nitroimidazoles, such as pimonidazole, misonidazole, etanidazole, tinidazole, metronidazole, ornidazole or dimetridazole, and anticancer agents, such as doxorubicin, campothecin, epirubicin, dactinomycin, etoposide or mitomycin C was added to the cell culture medium under hypoxic conditions (1% O2). RESULTS: Pimonidazole at a concentration of 100 microg/ml eliminated cell survival effect of doxorubicin at the concentrations of 0.1 and 1 microg/ml under hypoxic condition (1% O2) by promoting apoptosis. Almost all the cells died even after 24 hours of incubation for all the oxygen concentrations at a combination of 100 microg/ml pimonidazole and 1 microg/ml doxorubicin. Finally, pimonidazole at a concentration of 100 microg/ml, and misonidazole or etanidazole at a concentration of 1,000 microg/ml eliminated cell survival effect of all the anticancer agents tested under hypoxic condition. CONCLUSION: Combination therapy of doxorubicin (adriamycin) with pimonidazole can maximize dororubicin efficacy by eliminating cell survival effect of doxorubicin under hypoxic conditions in treating solid tumors, such as breast cancer.

Effect of antitumor agents on the survival of human hepatocellular carcinoma cells under hypoxic conditions / 대한내과학회지

BACKGROUND: In a previous study, we have shown that quinolones, antibiotics inhibiting topoisomerases, improve survival of tumor cells under hypoxic conditions. In this study, we tested whether antitumor agents such as doxorubicin that inhibit topoisomerases can also improve survival of tumor cells under hypoxic conditions. METHODS: Human hepatocellular carcinoma cells (HepG2) were grown in 4 mL of the culture medium at 2.5x10(5) cells/60 mm culture dish under normoxic conditions for 2 days before being transferred to fresh culture medium with different concentrations of doxorubicin or other antitumor agents under normoxic or hypoxic (1% oxygen concentration in air) conditions. Cell viability and the concentration of glucose and lactic acid in the medium were measured during cell culture. At the same time, the cells in the 60 mm dishes were lysed, and chromosomal DNA was isolated and loaded onto a 1.5% agarose gel for the DNA fragmentation assay. RESULTS: Doxorubicin inhibited cell growth under normoxic condition in a concentration-dependent manner for the 0~100 microgram/mL concentration range. However, doxorubicin improved cell viability under hypoxic conditions for a 0.1~10 microgram/mL concentration range by inhibiting apoptosis. Similar phenomena were observed for other antitumor agents that inhibit topoisomerases. CONCLUSIONS: Solid tumors usually have hypoxic regions in the tumor, under which conditions antitumor agents that inhibit topoisomerases may function to delay tumor cell death. This can reduce the efficacy of the antitumor agents.

Effect of Antibiotics on the Survival of Human Hepatocellular Carcinoma Cells under Hypoxic Conditions

PURPOSE: Antibiotics that kill or suppress the growth of bacteria also affect tumors directly or indirectly. The authors aimed to show whether some antibiotics can improve cancer cell survival under hypoxic conditions, and how the antibiotics improve the cells under hypoxic conditions. METHODS: Human hepatocellular carcinoma cells (HepG2) were grown at 1% oxygen concentration. Cell numbers, glucose concentrations and lactic acid concentrations in the medium were measured at different incubation times, in the absence or presence of aminoglycosides, tetracyclines, quinolones, penicillins, cephalosporins, sulfonamides, or chloramphenicols. DNA fragmentation assay was performed to study the mechanism how some antibiotics improve the cell survival under hypoxic conditions. RESULTS: Of the antibiotics tested, only aminoglycosides, tetracyclines, quinolones and the chloramphenicol improved cell survival under hypoxic conditions. Geneticin (G418), an aminoglycoside chosen as an example, improved cell survival even if glucose in the medium was completely consumed. At the same time, the appearance of DNA ladder was delayed in the presence of geneticin, which was also the same for the other antibiotics that improved cell survival under hypoxic conditions. CONCLUSION: Some antibiotics improved hepatocellular carcinoma cells under ischemic conditions by inhibiting apoptosis. The results implies that the antibiotics might adversely affect solid tumors, by improving cancer cell growth where hypoxic or ischemic conditions occur in the core region. Therefore, we might be cautious in choosing antibiotics for cancer patients with solid tumors, especially when the patients should be treated with antibiotics for a long time.

The Effect of Doxycycline on the Survival of the Cells under Hypoxic Condition / 신경정신의학

OBJECTIVES: Cerebrovascular diseases seriously effect patient's quality of life, and the treatment has, its limitation to bring functional recovery unless a patient is brought to a hospital within several hours from the onset. In this study, we tried to find a way to prolong the survival cells under hypoxic conditions using cell culture. METHODS: Cultured rat glioma cells grew in normal and high glucose medium under hypoxic conditions, with or without doxycycline. Cell viability, glucose and lactic acid concentration were measured. RESULTS: The cells died after 1 day of culture under hypoxic conditions in normal glucose medium without doxycycline due to the total consumption of glucose. On the contrary, the cells still survived even after 3 days of culture under the same hypoxic conditions in normal glucose medium with doxycycline despite the total consumption of all glucose. For both cases, the cause of death was not, at least, due to the decrease of pH as the pH was kept neutral during the whole period of culture. In this case, doxycycline was the cell survival factor by suppressing apoptosis, which was proved by DNA fragmentation assay. On the other hand, the cells died after 60 hours of culture under hypoxic conditions in high glucose medium without doxycycline due to the decrease of pH. The cells still survived even after 70 hours of culture under the same hypoxic conditions in high glucose medium with doxycycline due to the inhibition of decreased pH. For both cases, the cause of death was not, at least, due to the consumption of total glucose because some glucose remained in the medium at the end culture. CONCLUSION: Doxycycline increased cell viability both in normal glucose and high glucose medium under hypoxic conditions, which might have an application for the treatment of patients with ischemic stroke.

The Effect of Geneticin on the Survival of a Human Breast Cancer Cells under Hypoxic Condition / 한국유방암학회지

PURPOSE: In solid tumor, there is a region where oxygen supply is insufficient. Under this hypoxic condition, cancer cells became more resistant than normal cells. In this study, we found that one of the aminoglycoside antibiotics, geneticin, made a human breast cancer cell, MCF-7, even more resistant to hypoxia. METHODS: On normoxic (21% O2) condition, MCF-7 cells (1.5x10(6) cells/60 mm culture dish) were grown in low glucose (1 g/l) MEM (with 10% FBS) supplemented with 0, 1, 10, 100, and 1000 microgram/dl geneticin, respectively, for one day. Then, the cells were transferred to hypoxic (1% O2) incubator and grown for 3 days. We examined the viability of cells, the concentration of glucose and lactate and DNA fragmentation assay in each groups. RESULTS: When the cells were grown in low glucose medium under hypoxia (1% O2), all the cells became dead after 2 days of culture in the absence of geneticin whereas the cells still survived even after 3 days of culture in the presence of geneticin (10 microgram/ml). In the presence of geneticin, the cells survived despite of consumption of all glucose in the medium, whereas the cells became dead once all glucose was consumed in the absence of geneticin. In this case, geneticin made cells survive by suppressing apoptosis, which was proved by DNA fragmentation assay. CONCLUSION: The results might have some implications in treating solid tumor; if cancer patients should be treated for infection with antibiotics, aminoglycoside antibiotics can aggravate the patient's condition by making cancer cells more resistant to hypoxia. Therefore, the results strongly suggest that we should be careful in choosing antibiotics when they are used for cancer patients.