Social determinants of self-reported health for Canada's indigenous peoples: a public health approach.

OBJECTIVE: In Canada, indigenous peoples suffer from a multitude of health disparities. To better understand these disparities, this study aims to examine the social determinants of self-reported health for indigenous peoples in Canada. STUDY DESIGN: This study uses data from Statistics Canada's Aboriginal Peoples Survey 2012. METHODS: Multinomial logistic regression models were used to examine how selected social determinants of health are associated with self-reported health among off-reserve First Nations and Métis peoples in Canada. RESULTS: Our analysis shows that being older, female, and living in urban settings were significantly associated with negative ratings of self-reported health status among the indigenous respondents. Additionally, we found that higher income and levels of education were strongly and significantly associated with positive ratings of self-reported health status. Compared with indigenous peoples with an education level of grade 8 or lower, respondents with higher education were 10 times (5.35-22.48) more likely to report 'excellent' and 'very good' health. Respondents who earned more than $40,000 annually were three times (2.17-4.72) more likely to report 'excellent' and 'very good' health compared with those who earned less than $20,000 annually. When interacted with income, we also found that volunteering in the community is associated with better self-reported health. CONCLUSIONS: There are known protective determinants (income and education) and risk determinants (location of residence, gender, and age) which are associated with self-reported health status among off-reserve First Nations and Métis peoples. For indigenous-specific determinants, volunteering in the community appears to be associated with self-perceived health status. Thus, addressing these determinants will be necessary to achieve better health outcomes for indigenous peoples in Canada. Next steps include developing indigenous-specific social determinants of health indicators that adequately measure culture, connection, and community.

SERUM LEVELS OF FIBROBLAST GROWTH FACTOR 21 IN TYPE 2 DIABETIC PATIENTS.

BACKGROUND AND PURPOSE: Fibroblast growth factor 21 (FGF21) has recently been identified as a metabolic regulator, but its physiological role is still not completely known. The aim of this study was to evaluate serum FGF21 levels in an Iranian population with type 2 diabetes. MATERIALS AND METHODS: This cross-sectional study was conducted in patients with type 2 diabetes. All patients were evaluated for fasting serum levels of glucose, glycated hemoglobin (HbA1c), lipids, urea and creatinine. Participants were divided into two groups with poorly-controlled and well-controlled diabetes based on their HbA1c levels. Healthy non-diabetic subjects (matched with patients in terms of age, sex and body mass index [BMI]) were also recruited as control group. Serum FGF21 concentrations were determined in all subjects using ELISA. RESULTS: Of the evaluated 141 subjects, 49 (34.8%) were categorized as having well-controlled diabetes, 66 (46.8%) had poorly-controlled diabetes, and there were 26 subjects in the normal control group. Mean serum FGF-21 concentration was 337.89±283.67 ng/L in the diabetic group and 237.25±43.22 ng/mL in the non-diabetic group (p<0.001). Mean serum FGF21 level was 237.25 ± 43.22 ng/mL in the control group, 309.81 ± 301.68 ng/mL in the well-controlled diabetic group, and 358.73 ± 269.98 ng/mL in the poorly controlled diabetic group. Serum FGF21 level in the poorly controlled diabetic group was significantly higher than that in the well-controlled diabetic and the healthy control groups (p=0.02) but there was no significant difference between the well-controlled and healthy groups. There was no significant association between serum FGF21 levels with lipid levels, presence of diabetic complications and BMI (p > 0.05). CONCLUSIONS: The present results suggested an association between elevated serum levels of FGF21 and poor control of diabetes. Future studies are warranted to elucidate the prognostic role of these elevated levels of FGF21 in diabetic subjects.

Comparison of angiographic with myocardial perfusion scintigraphy findings in cardiac syndrome X (CSX).

OBJECTIVE: Cardiac syndrome X (CSX) is defined by an angina-like chest pain, a positive response to stress testing and normal or near normal coronary angiogram. We evaluated the angiographic findings in patients with cardiac syndrome X and compared it with myocardial perfusion scintigraphy findings. PATIENTS AND METHODS: The study included 39 females aged 40-58 years (mean, 49.79 +/- 4.69 [SD] and 13 males ranging from 40 to 54 years (mean, 47.54 +/- 3.76 [SD] with CSX. By reviewing the angiographic film, some variables including stenosis (less than 30% of vessel diameter), delay run off, delay wash out, calcification and tortuosity were evaluated. Thirty-two had been undergone on myocardial perfusion imaging (MPI). RESULTS: The most frequent abnormal angiographic finding in three territories was stenosis item. Overall, 22 of 32 (68.75%) CSX patients had ischemia on MPI. The result of the myocardial perfusion imaging was not concordant with five angiographic findings. CONCLUSION: We suggest that the presence of angiographic coronary findings such as stenosis, delay run off, delay wash out, calcification and tortuosity are not invariably associated with atherosclerosis, and also seen in CSX patients.

Decreased sensitivity to nitric oxide in the aorta of severely hypercholesterolemic apolipoprotein E-deficient mice.

A normal response to nitric oxide donors has been cited as evidence that impaired endothelium-dependent vasodilation during hypercholesterolemia is due to decreased synthesis of nitric oxide. This tenet was examined by determining responses to nitric oxide gas as well as to acetylcholine and sodium nitroprusside in the isolated aorta of apolipoprotein E-deficient mice fed normal or Western-type cholesterol-rich diet until 21 or 35 weeks of age. In mice fed normal chow, relaxation to all agents remained comparable to that obtained in wild-type mice. In mice fed Western diet, the relaxation to acetylcholine as well as to nitric oxide was decreased at 35 weeks of age. At 21 weeks of age, decreased sensitivity to nitric oxide was observed despite a normal response to acetylcholine. The response to sodium nitroprusside was normal in all groups. A decrease in aortic superoxide dismutase activity as well as an increase in aortic superoxide anion generated in the presence of NADH as measured by lucigenin chemiluminescence was observed in the group fed Western diet at 35 weeks. This provides evidence that altered superoxide anion could contribute to the deterioration in nitric oxide sensitivity that underlies the impaired endothelium-dependent relaxation. These data indicate that decreased sensitivity to nitric oxide may contribute to the development of impaired endothelium-dependent relaxation in hypercholesterolemia. The response to sodium nitroprusside appears not to reflect the decreased sensitivity of vascular smooth muscle to authentic nitric oxide.

Endothelial dysfunction in a murine model of mild hyperhomocyst(e)inemia.

Homocysteine is a risk factor for the development of atherosclerosis and its thrombotic complications. We have employed an animal model to explore the hypothesis that an increase in reactive oxygen species and a subsequent loss of nitric oxide bioactivity contribute to endothelial dysfunction in mild hyperhomocysteinemia. We examined endothelial function and in vivo oxidant burden in mice heterozygous for a deletion in the cystathionine beta-synthase (CBS) gene, by studying isolated, precontracted aortic rings and mesenteric arterioles in situ. CBS(-/+) mice demonstrated impaired acetylcholine-induced aortic relaxation and a paradoxical vasoconstriction of mesenteric microvessels in response to superfusion of methacholine and bradykinin. Cyclic GMP accumulation following acetylcholine treatment was also impaired in isolated aortic segments from CBS(-/+) mice, but aortic relaxation and mesenteric arteriolar dilation in response to sodium nitroprusside were similar to wild-type. Plasma levels of 8-epi-PGF(2alpha) (8-IP) were somewhat increased in CBS(-/+) mice, but liver levels of 8-IP and phospholipid hydroperoxides, another marker of oxidative stress, were normal. Aortic tissue from CBS(-/+) mice also demonstrated greater superoxide production and greater immunostaining for 3-nitrotyrosine, particularly on the endothelial surface. Importantly, endothelial dysfunction appears early in CBS(-/+) mice in the absence of structural arterial abnormalities. Hence, mild hyperhomocysteinemia due to reduced CBS expression impairs endothelium-dependent vasodilation, likely due to impaired nitric oxide bioactivity, and increased oxidative stress apparently contributes to inactivating nitric oxide in chronic, mild hyperhomocysteinemia.

Mechanism of nitric oxide-induced vasodilatation: refilling of intracellular stores by sarcoplasmic reticulum Ca2+ ATPase and inhibition of store-operated Ca2+ influx.

The precise mechanisms by which nitric oxide (NO) decreases free [Ca2+]i, inhibits Ca2+ influx, and relaxes vascular smooth muscle are poorly understood. In rabbit and mouse aorta, agonist-induced contractions and increases in [Ca2+]i were resistant to nifedipine, suggesting Ca2+ entry through non-L-type Ca2+ channels. Relaxations to NO were inhibited by thapsigargin (TG) or cyclopiazonic acid (CPA) indicating the involvement of sarcoplasmic reticulum ATPase (SERCA). Studies of the effect of NO on [Ca2+]i and the rate of Mn2+ influx with fura-2 fluorometry in rabbit aortic smooth muscle cells in primary culture were designed to test how SERCA is involved in mediating the response to NO. When cells were stimulated with angiotensin II (AII), NO accelerated the removal of Ca2+ from the cytoplasm, decreased [Ca2+]i, and inhibited Ca2+ and Mn2+ influx. Inhibition of SERCA abolished all the effects of NO. In contrast, inhibition of the Na+/Ca2+exchanger or the plasma membrane Ca2+ ATPase had no influence on the ability of NO to decrease [Ca2+]i. NO maximally decreased [Ca2+]i within 5 s, whereas significant inhibition of AII-induced Ca2+ and Mn2+ influx required more than 15 s. The inhibition of cation influx strictly depended on [Ca2+]o and functional SERCA, suggesting that during the delay before NO inhibits Ca2+ influx, the influx of Ca2+ and the uptake into intracellular stores are required. In the absence of [Ca2+]o, NO diminished the AII-induced [Ca2+]i transient by a SERCA-dependent mechanism and increased the amount of Ca2+ in the stores subsequently released by ionomycin. The present study indicates that the initial rapid decrease in [Ca2+]i caused by NO in vascular smooth muscle is accounted for by the uptake of Ca2+ by SERCA into intracellular stores. It is proposed that the refilling of the stores inhibits store-operated Ca2+ influx through non-L-type Ca2+ conducting ion channels and that this maintains the decrease in [Ca2+]i and NO-induced relaxation.

Evidence that additional mechanisms to cyclic GMP mediate the decrease in intracellular calcium and relaxation of rabbit aortic smooth muscle to nitric oxide.

1. The role of cyclic GMP in the ability of nitric oxide (NO) to decrease intracellular free calcium concentration [Ca2+]i and divalent cation influx was studied in rabbit aortic smooth muscle cells in primary culture. In cells stimulated with angiotensin II (AII, 10(-1) M), NO (10(-10) - 10(-6) M) increased cyclic GMP levels measured by radioimmunoassay and decreased [Ca2+]i and cation influx as indicated by fura-2 fluorimetry. 2. Zaprinast (10(-4) M), increased NO-stimulated levels of cyclic GMP by 3-20 fold. Although the phosphodiesterase inhibitor lowered the level of [Ca2+]i reached after administration of NO, the initial decreases in [Ca2+]i initiated by NO were not significantly different in magnitude or duration from those that occurred in the absence of zaprinast. 3. The guanylyl cyclase inhibitor, H-(1,2,4) oxadiazolo(4,3-a) quinoxallin-1-one (ODQ, 10(-5) M), blocked cyclic GMP accumulation and activation of protein kinase G, as measured by back phosphorylation of the inositol trisphosphate receptor. ODQ and Rp-8-Br-cyclic GMPS, a protein kinase G inhibitor, decreased the effects of NO, 10(-10) - 10(-8) M, but the decrease in [Ca2+]i or cation influx caused by higher concentrations of NO (10(-7) - 10(-6) M) were unaffected. Relaxation of intact rabbit aorta rings to NO (10(-7) - 10(-5) M) also persisted in the presence of ODQ without a significant increase in cyclic GMP. Rp-8-Br-cyclic GMPS blocked the decreases in cation influx caused by a cell permeable cyclic GMP analog, but ODQ and/or the protein kinase G inhibitor had no significant effect on the decrease caused by NO. 4. Although inhibitors of cyclic GMP, protein kinase G and phosphodiesterase can be shown to affect the decrease in [Ca2+]i and cation influx via protein kinase G, these studies indicate that when these mechanisms are blocked, cyclic GMP-independent mechanisms also contribute significantly to the decrease in [Ca2+]i and smooth muscle relaxation to NO.