Effects of acarbose on the acceleration of postprandial hyperglycemia-induced pathological changes induced by intermittent hypoxia in lean mice.

Postprandial hyperglycemia (PPH) and intermittent hypoxia related to the sleep apnea syndrome are important predictors of cardiovascular disease. We investigated the effects of intermittent hypoxia on pathological changes in the left ventricular (LV) myocardium caused by PPH in lean mice and evaluated the influence of acarbose, an α-glucosidase inhibitor. Male C57BL/6J mice aged 8 weeks were exposed to intermittent hypoxia (8 h/day during the daytime) or kept under normoxia. PPH was induced by restriction of feeding to 1-h periods twice a day, with the restricted diet (RD) mice receiving either standard chow or chow containing 0.02% acarbose. Another group of mice were fed standard chow ad libitum (AL). Plasma glucose levels after food intake were significantly elevated in RD but not in AL mice, and glucose levels were suppressed by acarbose. Intermittent hypoxia exacerbated cardiomyocyte hypertrophy and interstitial fibrosis in the LV myocardium of RD mice. Superoxide production and expression of 4-hydroxy-2-nonenal in the LV myocardium with intermittent hypoxia were increased in RD mice, but not AL mice. In addition, expression of tumor necrosis factor α (TNF-α) mRNA was increased in hypoxic RD mice. Treatment with acarbose inhibited oxidative stress and TNF-α mRNA expression and preserved the histological architecture of the LV myocardium.

Bottom-up synthesis of titanophosphate nanosheets by the aqueous solution process.

The synthesis of titanophosphate nanosheets in aqueous sols was examined by the bottom-up process. The nanosheets were formed by mixing titanium iso-propoxide, phosphoric acid, and tetraalkylammonium hydroxide (NR4OH) aqueous solutions, followed by diluting with water and heating at 80 °C, forming translucent aqueous sols of titanophosphate nanosheets with the same crystal structure as layered titanium phosphate Ti2O3(H2PO4)2·2H2O. Whether the nanosheets were crystallized depended on the reactions during the mixing of reagents before the water dilution. By controlling the acid-base reactions between the Ti species, phosphoric acid, and the hydroxides of bulky cations in the aqueous sols, the one-pot process yielded highly water-dispersible, flake-like titanophosphate nanosheets. Under some synthetic conditions, nanosheets formed even in weakly basic aqueous sols. These nanosheets can be coated on a substrate with low alkali-resistance, or used for the removal of metal ions from neutral aqueous solutions.

Angiotensin II receptor blocker reduces oxidative stress and attenuates hypoxia-induced left ventricular remodeling in apolipoprotein E-knockout mice.

Elevated superoxide formation in cardiac extracts of apolipoprotein E-knockout (apoE-KO) mice has been reported. In addition, we previously reported that hypoxia increased oxidative stress in the aortas of apoE-KO mice, although we did not examine the effect of hypoxia on the heart. The aim of this study was to investigate the effect of chronic hypoxia on the left ventricular (LV) remodeling in apoE-KO mice treated with or without an angiotensin II receptor blocker. Male apoE-KO mice (n=83) and wild-type mice (n=34) at 15 weeks of age were kept under hypoxic conditions (oxygen, 10.0+/-0.5%) and treated with olmesartan (3 mg/kg/day) or vehicle for 3 weeks. Although LV pressure was not changed, hypoxia caused hypertrophy of cardiomyocytes and increased interstitial fibrosis in the LV myocardium. Furthermore, nuclear factor-kappaB (NF-kappaB) and matrix metalloproteinase (MMP)-9 activities were increased in apoE-KO mice exposed to chronic hypoxia. Olmesartan effectively suppressed the 4-hydroxy-2-nonenal protein expression and NF-kappaB and MMP-9 activities, and preserved the fine structure of the LV myocardium without affecting the LV pressure. In conclusion, olmesartan reduced oxidative stress, and attenuated the hypoxia-induced LV remodeling, in part through the inhibition of NF-kappaB and MMP-9 activities, in apoE-KO mice.

Chronic hypoxia accelerates the progression of atherosclerosis in apolipoprotein E-knockout mice.

The aim of this study was to investigate the effect of chronic hypoxia on the development and progression of atherosclerosis in apolipoprotein E-knockout (apoE-KO) mice. Male and female apoE-KO mice (6 weeks old) and age- and sex-matched wild-type mice were kept under hypoxic conditions (10.0 +/- 0.5% O2) in a gas chamber or in room air for 3 weeks. Aortic atherosclerotic plaque was not observed in wild-type mice under normoxic or hypoxic conditions. In the apoE-KO mice, however, hypoxia induced proliferation of smooth muscle cells and plaque formation in the aorta, which were not observed under normoxic conditions. Although sexual dimorphism of the response to hypoxia was not observed, these hypoxia-induced atherogenic changes were accompanied by a significant increase of plasma low density lipoprotein (LDL) cholesterol and NADPH-dependent vascular superoxide (O2-) production. Furthermore, matrix metalloproteinase (MMP)-9 was activated in the aorta of apoE-KO mice. In conclusion, chronic hypoxia accelerated the development of atherosclerosis in apoE-KO mice, along with increased O2- production and activated MMP-9 in the aorta.

Coordinated but depressed expression of human leukocyte antigen-DR, intercellular adhesion molecule-1, and CD14 on peritoneal macrophages in women with pelvic endometriosis.

OBJECTIVE: To investigate the macrophage response in endometriosis, we determined the expression of human leukocyte antigen (HLA)-DR, intercellular adhesion molecule (ICAM)-1, and CD14 on peritoneal macrophages. DESIGN: Case-control study of immunologic markers. SETTING: University hospital. PATIENT(S): Forty-five Japanese women with endometriosis were compared with 48 control subjects with other laparoscopic diagnoses. INTERVENTION(S): Venipuncture and laparoscopic peritoneal fluid (PF) collection. MAIN OUTCOME MEASURE(S): Expression of HLA-DR, ICAM-1, and CD14 on peripheral blood (PB) monocytes and PF macrophages were quantitated as mean fluorescence intensities by flow cytometry. Expression of each marker on PF macrophages was divided by that on PB monocytes, as an index of macrophage activation (macrophage activation ratio). RESULT(S): In women with endometriosis, PF macrophages showed significant positive correlations between expression of HLA-DR and ICAM-1, HLA-DR and CD14, and ICAM-1 and CD14. However, expression of individual markers on PF macrophages and their activation ratios were significantly lower than in control. CONCLUSION(S): Coordinated but relatively low expression of HLA-DR, ICAM-1, and CD14 on PF macrophages indicates a positive but limited immune response to events in the peritoneal cavity in women with endometriosis, which may induce immune tolerance to implanted or metaplastic endometrial tissue.

Impact of the renin-angiotensin-aldosterone-system on cardiovascular and renal complications in diabetes mellitus.

Diabetes mellitus is a leading cause of morbidity and mortality because of its cardiovascular complications. It has been suggested that hyperglycemia, hyperinsulinemia and insulin resistance, glycation of proteins, oxidative stress, inflammation, and many other factors may be related to atherogenesis in diabetes. The metabolic abnormalities associated with diabetes lead to activation of the renin-angiotensin-aldosterone system (RAAS), with a subsequent increase of angiotensin II and aldosterone levels, which might alter the insulin signaling pathway and promote the formation of reactive oxygen species that induce endothelial dysfunction as well as cardiovascular disease and renal disease. Synthesis of angiotensin II is not only catalyzed by angiotensin-converting enzyme, but also by chymase. Recently, angiotensin II produced by chymase was reported to be involved in vascular proliferation and atherosclerosis. Chymase also activates matrix metalloproteinase-9, leading to extracellular matrix degradation, and promotes cardiovascular remodeling. Many studies have shown that angiotensin-II blockade significantly reduces the levels of proinflammatory mediators and suppresses oxidative stress. In clinical trials, RAAS blockade has been found to delay or prevent the onset of type 2 diabetes, and it also prevents cardiovascular and renal events in diabetic patients. Thus, RAAS inhibition represents first-line treatment for hypertensive and diabetic target organ damage, as well as preventing the progression of cardiovascular disease and kidney disease. This review presents the available information about the role of the RAAS in the cardiovascular and renal complications of diabetes.

Pitavastatin reduces oxidative stress and attenuates intermittent hypoxia-induced left ventricular remodeling in lean mice.

We have reported previously that intermittent hypoxia related to sleep apnea induces cardiovascular remodeling secondary to the oxidative stress. The aim of this study was to examine the effect of pitavastatin as an antioxidant to prevent intermittent hypoxia-induced left ventricular (LV) remodeling in mice without hypercholesterolemia. Eight-week-old male C57BL/6J mice (n=35) were exposed to intermittent hypoxia (30 s exposure to 5% oxygen, followed by 30 s exposure to 21% oxygen) for 8 h per day during the daytime or maintained under normoxic conditions; in addition, they were either treated with pitavastatin (3 mg kg(-1) per day) or vehicle for 10 days. After cardiac catheterization and blood sampling, the LV myocardium was examined. The systemic blood pressure and plasma level of total cholesterol were similar among the four groups. Intermittent hypoxia significantly increased the expression levels of 4-hydroxy-2-nonenal (4-HNE) proteins, TNF-alpha and TGF-beta mRNA, and also the number of terminal deoxynucleotidyl transferase-mediated dUTP-biotin end labeling (TUNEL)-positive myocardial cells in the LV myocardium. In addition, enhanced hypertrophy of the cardiomyocytes, perivascular fibrosis and histological degeneration were observed in the mice exposed to hypoxic stress. Treatment with pitavastatin significantly suppressed the expression levels of the 4-HNE proteins, cytokines, superoxide production and TUNEL-positive myocardial cells in the LV myocardium, consequently attenuating the hypoxia-induced histological changes. Pitavastatin preserved, at least partially, the morphological structure of the LV myocardium in lean mice exposed to intermittent hypoxia, through its antioxidant effect.

Efficacy of olmesartan and nifedipine on recurrent hypoxia-induced left ventricular remodeling in diabetic mice.

AIMS: Recurrent hypoxia due to sleep apnea syndrome is implicated in cardiovascular events, especially in diabetic patients, but the underlying mechanisms remain controversial. We previously reported that angiotensin II receptor blockers can improve hypoxia-induced left ventricular remodeling. The aim of this study was to examine the effect on left ventricular remodeling of adding a calcium channel blocker to angiotensin II receptor blocker therapy in diabetic mice exposed to recurrent hypoxia. MAIN METHODS: Male db/db mice (8-week-old) and age-matched control db/+ mice were fed a Western diet and subjected to recurrent hypoxia (oxygen at 10+/-0.5% for 8h daily during the daytime) or normoxia for 3weeks. Hypoxic db/db mice were treated with the vehicle, olmesartan (3mg/kg/day), nifedipine (10mg/kg/day), or both drugs. KEY FINDINGS: Recurrent hypoxia caused hypertrophy of cardiomyocytes, interstitial fibrosis, and a significant increase in expression of the oxidative stress marker 4-hydroxy-2-nonenal (4-HNE) in the left ventricular myocardium. Treatment with olmesartan, nifedipine, or both drugs had no effect on systolic blood pressure, and each treatment achieved similar suppression of 4-HNE expression. Olmesartan and the combination with olmesartan and nifedipine significantly prevented cardiomyocyte hypertrophy more than treatment with nifedipine alone. On the other hand, olmesartan combined with nifedipine significantly reduced cytokine expression, superoxide production and matrix metalloproteinase (MMP)-9 activity, and significantly suppressed interstitial fibrosis in the left ventricular myocardium. SIGNIFICANCE: The combination with olmesartan and nifedipine, as well as a monotherapy with olmesartan, exerts preferable cardioprotection in diabetic mice exposed to recurrent hypoxia.

Chymase plays an important role in left ventricular remodeling induced by intermittent hypoxia in mice.

Intermittent hypoxia caused by sleep apnea is associated with cardiovascular disease. Chymase has been reported to play an important role in the development of cardiovascular disease, but it is unclear whether chymase is involved in the pathogenesis of left ventricular remodeling induced by intermittent hypoxia. The aim of this study was to evaluate the effect of a novel chymase inhibitor (NK3201) on hypoxia-induced left ventricular remodeling in mice. Male C57BL/6J mice (9 weeks old) were exposed to intermittent hypoxia or normoxia and were treated with NK3201 (10 mg/kg per day) or the vehicle for 10 days. Left ventricular systolic pressure showed no significant differences among all of the experimental groups. Exposure to intermittent hypoxia increased left ventricular chymase activity and angiotensin II expression, which were both suppressed by treatment with NK3201. Intermittent hypoxia also increased the mean cardiomyocyte diameter, perivascular fibrosis, expression of inflammatory cytokines, oxidative stress, and NADPH-dependent superoxide production in the left ventricular myocardium. These changes were all suppressed by NK3201 treatment. Therefore, chymase might play an important role in intermittent hypoxia-induced left ventricular remodeling, which is independent of the systemic blood pressure.

Regulation of oxidative stress and cardioprotection in diabetes mellitus.

Analysis of the Framingham data has shown that the risk of heart failure is increased substantially among diabetic patients, while persons with the metabolic syndrome have an increased risk of both atherosclerosis and diabetes mellitus. Sleep apnea may be related to the metabolic syndrome and systemic inflammation through hypoxia, which might also cause the cardiac remodeling by increased oxidative stress. On the other hand, the renin-angiotensin system is activated in diabetes, and local angiotensin II production may lead to oxidative damage via the angiotensin II type 1 receptor. Basic and clinical data indicate that angiotensin II receptor blockers have the potential to preserve left ventricular function and prevent cardiac remodeling that is exaggerated by oxidative stress in patients with diabetes. Thus, alleviation of oxidative stress might be one possible strategy in the treatment of diabetic patients associated with sleep apnea.

Exaggerated renal pathology of partial ablation-induced chronic renal failure in eNOS deficient mice.

We investigated the role of endothelial nitric oxide synthase (eNOS) in the remnant kidney model of chronic renal failure, by using eNOS-deficient (eNOS-/-) and wild-type mice. There were significant increments of blood urea nitrogen level, plasma creatinine concentration and proteinuria in both wild-type and eNOS-/- mice at 8 weeks after 5/6 nephrectomy, but observed changes were more prominent in eNOS-/- mice. Only 7 out of 30 eNOS-/- mice were alive during 8-week experimental period, whereas survival rate in the wild-type mice was 69%. The glomerular size distribution indicated that the glomeruli of 5/6 nephrectomized eNOS-/- mice tended to be larger compared with cases of wild-type mice. It seems likely that eNOS-derived NO is protective against renal injuries in this disease model.

Decreased human leukocyte antigen-DR expression in the lipid raft by peritoneal macrophages from women with endometriosis.

OBJECTIVE: To investigate the macrophage response in endometriosis by determining the expression and localization of human leukocyte antigen (HLA)-ABC and HLA-DR by the peritoneal fluid (PF) macrophages and PF concentrations of interferon (IFN)-gamma that regulate HLA expression. DESIGN: Case-control study. SETTING: University hospital. PATIENT(S): 64 Japanese endometriosis patients, and 65 women with other laparoscopic diagnoses. INTERVENTION(S): Venipuncture and laparoscopic peritoneal fluid collection. MAIN OUTCOME MEASURE(S): Expression and localization of HLA-ABC and HLA-DR in PF macrophages were determined by flow cytometry and confocal microscopy. The concentration of IFN-gamma in PF was determined by enzyme-linked immunosorbent assay. RESULT(S): In women with endometriosis, expression of HLA-ABC and HLA-DR by PF macrophages, and the IFN-gamma concentrations in PF were statistically significantly lower than in controls. Women with endometriosis showed a statistically significant positive correlation between HLA expression and IFN-gamma concentration. By confocal microscopy, HLA-ABC was distributed homogenously on the macrophage surface whereas HLA-DR expression on these cells corresponded to the lipid raft. CONCLUSION(S): In women with endometriosis, low HLA expression and particularly reduced HLA-DR in the lipid raft may be influenced by low IFN-gamma and may compromise antigen presentation, limiting the immune response to peritoneal cavity antigens such as implanted or metaplastic endometrial tissue.

Role of gp91phox-containing NADPH oxidase in left ventricular remodeling induced by intermittent hypoxic stress.

Intermittent hypoxia due to sleep apnea syndrome is associated with cardiovascular diseases. However, the precise mechanisms by which intermittent hypoxic stress accelerates cardiovascular diseases are largely unclear. The aim of this study was to investigate the role of gp91(phox)-containing NADPH oxidase in the development of left ventricular (LV) remodeling induced by intermittent hypoxic stress in mice. Male gp91(phox)-deficient (gp91(-/-)) mice (n = 26) and wild-type (n = 39) mice at 7-12 wk of age were exposed to intermittent hypoxia (30 s of 4.5-5.5% O(2) followed by 30 s of 21% O(2) for 8 h/day during daytime) or normoxia for 10 days. Mean blood pressure and LV systolic and diastolic function were not changed by intermittent hypoxia in wild-type or gp91(-/-) mice, although right ventricular systolic pressure tended to be increased. In wild-type mice, intermittent hypoxic stress significantly increased the diameter of cardiomyocytes and interstitial fibrosis in LV myocardium. Furthermore, intermittent hypoxic stress increased superoxide production, 4-hydroxy-2-nonenal protein, TNF-alpha and transforming growth factor-beta mRNA, and NF-kappaB binding activity in wild-type, but not gp91(-/-), mice. These results suggest that gp91(phox)-containing NADPH oxidase plays a crucial role in the pathophysiology of intermittent hypoxia-induced LV remodeling through an increase of oxidative stress.

Killer immunoglobulin-like receptor and human leukocyte antigen expression as immunodiagnostic parameters for pelvic endometriosis.

PROBLEM: We investigated host immunologic responses to endometriosis by comparing immune cell surface antigens in peripheral blood (PB) and peritoneal fluid (PF) from women with endometriosis with those in PB and PF from other patients. METHOD OF STUDY: Japanese women with endometriosis (n = 56) were compared with controls with other laparoscopic diagnoses (n = 68). PB and PF were collected at the time of laparoscopy for flow cytometry. RESULTS: No significant difference in phenotypic parameters of T cells (CD3, CD4, and CD8), B cells (CD19), natural killer (NK) cells (CD56), or monocytes/macrophages (CD14) was seen between women with and without endometriosis. However, increased killer immunoglobulin-like receptor (CD158a) expression by NK cells and decreased human leukocyte antigen (HLA)-ABC and -DR expression by macrophages, all suggesting decreased functional activation were found in endometriosis. These markers showed significant association with endometriosis by odds ratio, logistic regression, and decision tree analyses. CONCLUSIONS: Increased CD158a(+) NK cells in PB and PF indicated decreased NK cell cytotoxicity in endometriosis, while decreased HLA expression on PF macrophages suggested impaired antigen presentation. Thus, aberrant immune responses by NK cells and macrophages may represent risk factors for endometriosis.

Angiotensin-II receptor blocker exerts cardioprotection in diabetic rats exposed to hypoxia.

BACKGROUND: Hypoxia caused by sleep apnea might be associated with an increased risk of cardiovascular events in subjects with metabolic syndrome. The aim of this study was to examine the effect of hypoxia on the left ventricular (LV) myocardium and evaluate the cardioprotective effect of an angiotensin-II receptor blocker (ARB) in diabetic rats. METHODS AND RESULTS: Male Otsuka Long-Evans Tokushima Fatty (OLETF) rats at 30 weeks of age (n=30) were divided into 2 groups that were treated with vehicle or candesartan 0.2 mg x kg(-1) x day (-1). The animals were housed in a hypoxic gas chamber (oxygen, 10.0+/-0.5%, mean +/- standard deviation) for 2 weeks. Hypoxia increased right ventricular (RV) systolic pressure (hypoxia; 78+/-14 mmHg vs control; 22+/-5, p<0.05), but did not increase LV systolic pressure (131+/-23 mmHg vs 121+/-10). Hypoxia exacerbated the degeneration of cardiomyocytes, and accelerated the expression of hypoxia inducible factor-1alpha (HIF-1 alpha) and vascular endothelial growth factor (VEGF) in the myocardium. Treatment with ARB decreased RV and LV pressures (46+/-7 and 100+/-18 mmHg, respectively), suppressed the expression of HIF-1alpha and VEGF, and preserved the fine structure of the LV myocardium. CONCLUSIONS: ARB exhibited cardioprotection under hypoxia, in part through the reduction of blood pressure and cytokine expression, in OLETF rats. Thus, ARB might be a potent agent for the treatment of diabetic patients with the complication of sleep apnea.

Expression of inhibitory-motif killer immunoglobulin-like receptor, KIR2DL1, is increased in natural killer cells from women with pelvic endometriosis.

PROBLEM: We investigated inhibitory and activation motif expression of killer immunoglobulin-like receptor (KIR) by natural killer (NK) cells, which may be pathogenetically involved in endometriosis. METHOD OF STUDY: We compared cells from 24 Japanese women laparoscopically diagnosed with endometriosis, to cells from 25 women with other laparoscopic diagnoses. KIR expression by NK cells was assessed in peripheral blood (PB) and peritoneal fluid (PF) by flow cytometry. Intracellular immunoreceptor tyrosine-based (IT) inhibitory and activation motifs (ITIM and ITAM) of KIR in PB was assessed by Western blotting. RESULTS: ITIM-KIR expression by PB NK cells was significantly and similarly greater than ITAM-KIR expression in women with and without endometriosis. Percentages of CD56(+) NK cells in PB and PF did not differ significantly between women with and without endometriosis; however, the percentage of CD158a(+) cells among CD56(+) NK cells in PB and PF was significantly higher in women with than without endometriosis. CONCLUSIONS: ITIM-KIR expressing NK cells might confer tolerance to peritoneal endometriotic implants.

Killer inhibitory receptor CD158a overexpression among natural killer cells in women with endometriosis is undiminished by laparoscopic surgery and gonadotropin releasing hormone agonist treatment.

PROBLEM: Natural killer (NK) dysfunction is considered to contribute to the pathogenesis of endometriosis. In this study, we investigated the host immune response to endometriosis in terms of killer inhibitory receptor (KIR) expression by NK cells. METHOD OF STUDY: We compared cells from Japanese women laparoscopically diagnosed with endometriosis and treated with laparoscopic surgery (n = 98), 1 month after laparoscopic surgery (n = 36), and 12 weeks after gonadotropin releasing hormone agonist (GnRHa) treatment (n = 18) to cells from 104 women with other laparoscopic diagnoses. KIR expression by NK cells was assessed in peripheral blood and peritoneal fluid samples by flow cytometry. RESULTS: In women with endometriosis, the percentage of CD158a-expressing cells among CD16-expressing NK (CD158a(+)NK) cells in both peritoneal fluid and peripheral blood was significantly higher than in control subjects. No significant differences in proportion of CD158a(+)NK cells were identified between peripheral blood NK cells sampled before and 1 month after laparoscopic surgery, or 12 weeks after initiating GnRHa treatment. CONCLUSIONS: Increased percentage of CD158a(+)NK cells in peripheral blood from women with endometriosis was undiminished by laparoscopic surgery and GnRHa treatment; the persistence of CD158a(+)NK cell excess is probably related to NK cell suppression in endometriosis. This overexpression may represent a risk factor for development of endometriosis and its recurrence after treatments.