Pioglitazone, a peroxisome proliferator-activated receptor-gamma agonist, attenuates myocardial ischemia-reperfusion injury in mice with metabolic disorders

Although considerable attention has focused on obesity, insulin resistance and abnormal lipid metabolism as coronary risk factors, it remains unclear how these pathogenic factors affect the inflammatory response after myocardial ischemia-reperfusion. This study was conducted to evaluate whether these metabolic disorders exacerbate myocardial ischemia-reperfusion injury, and to determine if ischemia-reperfusion injury could be modified with the thiazolidinedione, pioglitazone. Experiments were performed in KK-A^y and C57BL/6J mice subjected to 40 min of ischemia followed by reperfusion. Infiltration of inflammatory cells in ischemic myocardium, and infarct size 3 days after reperfusion were significantly higher in KK-A^y than C57BL/6J mice (p < 0.05 and p < 0.001, respectively). Furthermore, expression of chemokines, inflammatory cytokines and extracellular matrix proteins in ischemic myocardium was significantly higher in KK-A^y than C57BL/6J mice 1 day after reperfusion. Pioglitazone treatment of KK-A^y mice for 14 days significantly reduced the accumulation of inflammatory cells in ischemic myocardium, and infarct size 3 days after reperfusion compared to vehicle treatment (p < 0.05 and p < 0.05, respectively). Pioglitazone also attenuated expression of chemokines, inflammatory cytokines and extracellular matrix proteins in ischemic myocardium 1 day after reperfusion. In vitro experiments demonstrated that tumor necrosis factor-α (TNF-α) was significantly higher in cultured peritoneal macrophages from KK-A^y than C57BL/6J mice, and pioglitazone significantly reduced TNF-α in macrophages from both types of mice. These findings suggest that metabolic disorders exacerbate ischemia-reperfusion injury as a result of overexpression of inflammatory mediators, and this effect might be improved, in part by the anti-inflammatory effects of pioglitazone.     

Prostaglandin prevents alterations in DNA,RNA, and protein in damaged gastric mucosa

Fasted rats were given either 16,16-dimethyl-PGE2 (dmPGE2) (1 microgram/kg) or normal saline subcutaneously followed by the oral administration of 1 ml of 100% ethanol or saline 30 min later. At 1, 3, 6, and 24 hr later, animals were sacrificed, their stomachs examined for necrotic ulcerations, and the incorporation of [3H]thymidine into DNA as well as tissue levels of DNA, RNA, and protein content of glandular mucosa determined. Compared with control animals, severe ulcerations of 70-80% of the glandular mucosa were observed in rats given 100% ethanol at all time periods. Accompanying these ulcerations were marked depressions in tissue levels of DNA and RNA at 1, 3, 6, and 24 hr after exposure to ethanol, and protein at 1, 3, and 6 hr following ethanol. In rats pretreated with dmPGE2 before ethanol administration, these alterations in tissue levels of DNA, RNA, and protein were prevented as were ulcerations of the glandular stomach at each time period. Synthesis of mucosal DNA was not significantly different from control rats in any of the groups studied. It is concluded that (1) gastric mucosal damage by alcohol is associated with a decrease in tissue levels of DNA, RNA, and protein; (2) dmPGE2 maintains normal tissue levels of DNA, RNA, and protein by preventing the shedding of mucosal cells by alcohol; and (3) the ability of dmPGE2 to prevent gastric damage by alcohol is not mediated through stimulation of DNA synthesis.     

Effects of methylprednisolone administration in acute myocardial infarction

Methylprednisolone sodium succinate, 50 mg/kg body weight, was given as an intravenous bolus injection to 15 dogs with acute myocardial infarction and the results were compared with data in control animals. Methylprednisolone was thought to improve the critical oxygen balance of the infarcted heart by two mechanisms: (1) by diminishing heart rate, afterload and preload in the initial 15 minutes after its administration and thereby decreasing the oxygen need of the heart, and (2) by increasing coronary arterial blood flow. Both mechanisms were believed to contribute to the increase in cardiac output, efficiency and ventricular performance. This improvement in performance was presumably not due to a positive inotropic effect, since studies in isolated heart muscle showed no effect of methylprednisolone on contractility. Regional circulations other than the coronary circulation seemed to be little affected by administration of methylprednisolone except for blood pressure-related increases in superior mesenteric and femoral arterial blood flow.     

Effects of the antioxidative beta-blocker celiprolol on endothelial progenitor cells in hypertensive rats

BackgroundEndothelial progenitor cells (EPCs) derived from bone marrow migrate to areas of endothelial damage and repair them. EPC function is impaired by oxidative stress. We examined the effects of an antioxidative beta(1)-adrenoceptor blocker on the number and function of EPCs in hypertensive rats.MethodsSpontaneously hypertensive rats (SHRs) and Wistar-Kyoto (WKY) rats were fed diets loaded with high salt. The SHRs were treated with celiprolol or atenolol for 2 weeks. Peripheral blood mononuclear cells (MNCs) were separated, subjected to flow cytometric analysis to determine the number of circulating EPCs, and cultured to quantify EPC colony formation. EPC migration was evaluated in migration assay chambers. EPC senescence was evaluated using beta-galactosidase assay. Oxidative stress of EPCs was evaluated using thiobarbituric acid-reactive substance (TBARS) assay. The expression of nicotinamine adenine dinucleotide phosphate (NAD(P)H) oxidase component mRNAs in the renal cortex, aorta, and heart were evaluated by real-time PCR.ResultsThe number, colony formation, and migration of EPCs in SHRs were significantly lower than those in WKY rats. TBARS scores in EPCs from SHRs were significantly higher than those from WKY rats. Celiprolol increased the number of circulating EPCs and stimulated EPC colony formation and migration, while decreasing EPC senescence. Celiprolol inhibited oxidation in EPCs from SHRs, and decreased the expression of NAD(P)H oxidase component mRNAs in the renal cortex, aorta, and heart.ConclusionEPCs are impaired in SHRs in response to oxidative stress. Celiprolol decreases oxidative stress in hypertension in vivo and improves EPC numbers and function. It appears, therefore, that celiprolol may exert beneficial cardiovascular effects through its antioxidative properties.American Journal of Hypertension (2008). doi 10.1038/ajh.2008.233American Journal of Hypertension (2008); 21, 9, 1062-1068. doi 10.1038/ajh.2008.233.     

Osteoblasts induce Ca2+ oscillation-independent NFATc1 activation during osteoclastogenesis

Intercellular cross-talk between osteoblasts and osteoclasts is important for controlling bone remolding and maintenance. However, the precise molecular mechanism by which osteoblasts regulate osteoclastogenesis is still largely unknown. Here, we show that osteoblasts can induce Ca(2+) oscillation-independent osteoclastogenesis. We found that bone marrow-derived monocyte/macrophage precursor cells (BMMs) lacking inositol 1,4,5-trisphosphate receptor type2 (IP(3)R2) did not exhibit Ca(2+) oscillation or differentiation into multinuclear osteoclasts in response to recombinant receptor activator of NF-kappaB ligand/macrophage colony-stimulating factor stimulation. IP(3)R2 knockout BMMs, however, underwent osteoclastogenesis when they were cocultured with osteoblasts or in vivo in the absence of Ca(2+) oscillation. Furthermore, we found that Ca(2+) oscillation-independent osteoclastogenesis was insensitive to FK506, a calcineurin inhibitor. Taken together, we conclude that both Ca(2+) oscillation/calcineurin-dependent and -independent signaling pathways contribute to NFATc1 activation, leading to efficient osteoclastogenesis in vivo.     

Association of Gln222Arg polymorphism in the deoxyribonuclease I (DNase I) gene with myocardial infarction in Japanese patients.

AIMS: We have recently reported that serum deoxyribonuclease I (DNase I) activity, which may be involved in apoptosis, increases abruptly in the early phase of acute myocardial infarction (MI) [Kawai Y, Yoshida M, Arakawa K, Kumamoto T, Morikawa N, Masamura K, Tada H, Ito S, Hoshizaki H, Oshima S, Taniguchi K, Terasawa H, Miyamori I, Kishi K, Yasuda T. Diagnostic use of serum deoxyribonuclease I activity as a novel early-phase marker in acute myocardial infarction. Circulation 2004;109:2398-2400]. Death of vascular smooth muscle cells, in part because of apoptosis, is postulated to heighten susceptibility to disruption of vulnerable plaque, resulting in onset of MI. The present study evaluated the possibility that Gln222Arg polymorphism of the DNase I gene may be one of the factors involved in predisposition to MI. METHODS AND RESULTS: We assessed 611 Japanese patients: 311 with MI and 300 with stable angina pectoris (AP). Three common phenotypes determined by two common codominant alleles, DNASE1*1 and *2, whose corresponding gene products exhibit different properties, were found in these patient groups. The prevalence of DNASE1*2 was significantly higher in patients with MI than in those with AP (0.543 vs. 0.428, P < 0.001), being confirmed by phenotyping of the second study population. Multiple logistic regression analysis showed that the odds ratio of DNASE1*2 was 1.51 [95% confidence interval (CI) 1.04-2.18]. The association of the DNASE1*2 allele with MI was statistically significant, being independent of other conventional risk factors. CONCLUSION: Our data demonstrate that Gln222Arg polymorphism in the DNase I gene is associated with MI in the Japanese patients.     

Heart failure with silent coronary artery spasm exhibiting microscopic focal myocardial necrosis and amyloid-deposition

We report a 67-year-old Japanese man who presented with worsening heart failure with asymptomatically transient ischemic ST-segment depression. Left ventriculography showed diffuse hypokinesis; asymptomatic coronary artery spasm was evoked by the acetylcholine provocation test. Endomyocardial biopsy exhibited hypertrophic cardiomyocytes and scattered microscopic focal myocardial necrosis with amyloid-deposition. Transient ST-segment depression improved after treatment with a calcium antagonist, but cardiac contraction was still impaired. We hypothesize that asymptomatic coronary spasm may cause irreversible cardiac damage and heart failure with amyloid-deposition; the presence or absence of coronary spasm in heart failure patients should be clarified in order to determine therapeutic strategy.     

Detection of ploidy in colorectal tumors

Parallel investigations of ploidy by flow cytometry and cytogenetics were performed in 20 colorectal tumors. Flow cytometry detected an aneuploidy in 13 tumors with DNA indices ranging from 1.13 to 2.21. The other samples exhibited an apparent diploid DNA content. Cytogenetic analyses revealed an abnormal chromosome count in 14 cases and a frequent implication of numerical or structural changes in chromosomes 1, 7, 12, 17, 18, and 20. DNA content evaluated by both techniques was generally concordant with minor discrepancies not exceeding 10%. In six cases, cytogenetics failed to find the cell populations detected by flow cytometry. These results indicate that flow cytometry and cytogenetics are reliable and complementary techniques, particularly in near-diploid tumors, where flow cytometry has some difficulties in detecting variations from diploidy below to 8%.