Interaction of oxidized low-density lipoprotein and the renin-angiotensin system in coronary artery disease

Updates on the Renin-Angiotensin-Aldosterone System and the Cardiovascular Continuum

The cardiovascular continuum describes how several cardiovascular risk factors contribute to the development of atherothrombosis, ischemic heart disease, and peripheral arteriopathy, leading to cardiac and renal failure and ultimately death. Due to its multiple valences, the renin-angiotensin-aldosterone system plays an important role in all stages of the cardiovascular continuum, starting from a cluster of cardiovascular risk factors, and continuing with the development of atherosclerosis thorough various mechanisms, and culminating with heart failure. Therefore, this article aims to analyze how certain components of the renin-angiotensin-aldosterone system (converting enzymes, angiotensin, angiotensin receptors, and aldosterone) are involved in the underlying pathophysiology of the cardiovascular continuum and the possible arrest of its progression.

Relationship between onset age of type 2 diabetes mellitus and vascular complications based on Propensity score matching analysis

Aims/Introduction

To assess the relationship between type 2 diabetes mellitus onset age and vascular complications in China.

Materials and Methods

A retrospective review of 3,568 patients with type 2 diabetes mellitus using a propensity score‐matched (PSM) cohort analysis was carried out in two different age of onset groups (age 40 and 60 years). These groups were then subdivided into two groups, early‐onset diabetes (EOD40 and EOD60; the onset age before 40 and 60 years, respectively) and late‐onset diabetes (LOD40 and LOD60: the onset age after 40 and 60 years, respectively). Macrovascular and microvascular complications were analyzed before and after PSM.

Results

Patients categorized in both the early‐onset disease (EOD) groups had a higher risk of developing macro‐ and microvascular complications before PSM. After PSM, no differences existed between the EOD and late‐onset disease groups in the risk of macrovascular complications. Compared with the late‐onset disease group, the odds ratio of having a microvascular complication of diabetic retinopathy, chronic kidney disease and diabetic peripheral neuropathy in the 40‐year‐old EOD group increased to 2.906, 1.967 and 1.672 (P < 0.05), respectively. The odds ratio of diabetic retinopathy and diabetic peripheral neuropathy in the 60‐year‐old EOD group was 1.763 and 1.675 (P < 0.05), respectively.

Conclusions

The earlier the onset of type 2 diabetes mellitus, the higher risk of microvascular, but not necessarily macrovascular, complications. It is not too late to prevent diabetes at any age. Pre‐emptive microvascular treatment or preventative measures in EOD patients who do not yet show symptoms, might be beneficial.

Associations of Type 2 Diabetes Onset Age With Cardiovascular Disease and Mortality: The Kailuan Study

OBJECTIVE

We aimed to explore the associations between type 2 diabetes onset age and cardiovascular disease (CVD) and all-cause mortality in the Chinese population.

RESEARCH DESIGN AND METHODS

This study included 101,080 participants free of prevalent diabetes and CVD at baseline from the Kailuan Study. All participants were monitored biennially until 31 December 2017. During follow-up, 11,384 participants were diagnosed as having type 2 diabetes. For each case subject, one control subject was randomly selected, matched for age (± 1 years) and sex. The final analysis comprised 10,777 case-control pairs. Weighted Cox regression models were used to evaluate the average hazard ratios (AHRs) and 95% CIs of incident CVD and all-cause mortality among patients with new-onset type 2 diabetes versus control subjects across age-groups.

RESULTS

During a median follow-up of 5.57 years, 1,794 incident events (907 CVD events, of which there were 725 strokes and 887 deaths) occurred. After adjustment for potential confounders, participants with type 2 diabetes diagnosed at age <45 years had the highest relative risks of CVD and all-cause mortality relative to the matched control subjects, with AHRs of 3.21 (95% CI 1.18-8.72) for CVD, 2.99 (95% CI 1.01-9.17) for stroke, and 4.79 (95% CI 1.95-11.76) for all-cause mortality. The risks gradually attenuated with each decade increase in type 2 diabetes onset age.

CONCLUSIONS

The relative risks of CVD and all-cause mortality differed across type 2 diabetes onset age-groups, and the associations were more evident in younger-onset type 2 diabetes.

The relationship between plasma renin activity and serum lipid profiles in patients with primary arterial hypertension

Introduction:

The aim of the study was to evaluate clinical and biochemical differences between patients with low-renin and high-renin primary arterial hypertension (AH), mainly in reference to serum lipids, and to identify factors determining lipid concentrations.

Materials and methods:

In untreated patients with AH stage 1 we measured plasma renin activity (PRA) and subdivided the group into low-renin (PRA < 0.65 ng/mL/h) and high-renin (PRA ⩾ 0.65 ng/mL/h) AH. We compared office and 24-h ambulatory blood pressure, serum aldosterone, lipids and selected biochemical parameters between subgroups. Factors determining lipid concentration in both subgroups were assessed in regression analysis.

Results:

Patients with high-renin hypertension (N = 58) were characterized by higher heart rate (p = 0.04), lower serum sodium (p < 0.01) and aldosterone-to-renin ratio (p < 0.01), and significantly higher serum aldosterone (p = 0.03), albumin (p < 0.01), total protein (p < 0.01), total cholesterol (p = 0.01) and low-density lipoprotein cholesterol (LDL-C) (p = 0.04) than low-renin subjects (N = 39). In univariate linear regression, only PRA in the low-renin group was in a positive relationship with LDL-C (R² = 0.15, β = 1.53 and p = 0.013); this association remained significant after adjustment for age, sex, and serum albumin and aldosterone concentrations.

Conclusions:

Higher serum levels of total and LDL-C characterized high-renin subjects, but the association between LDL-C level and PRA existed only in low-renin primary AH.

Low triglyceride as a marker for increased risk of cardiovascular diseases in patients with long-term type 2 diabetes: A cross-sectional survey in China

BACKGROUND

There are inconsistent findings regarding associations between triglyceride levels and cardiovascular disease (CVD) in type 2 diabetes mellitus (T2DM). This study aimed to test whether the association between triglycerides and CVD depends upon duration of diabetes.

METHODS

From April 1, 2012, to June 30, 2012, we conducted a cross-sectional survey of 223 612 patients with T2DM from 630 hospitals in China. Cardiovascular disease was defined as having either prior coronary heart disease or stroke, or diabetic foot. Binary logistic regression was used to estimate odds ratios of triglyceride for CVD. Relative excess risk due to interaction, attributable proportion due to interaction, and synergy index were used to estimate effect size of additive interaction between low triglyceride, ie, <1.7 mmol/L, and duration of diabetes, ie, ≥15 years.

RESULTS

Among 223 612 T2DM patients, 31 898 (14.27%) suffered from CVD. A low level of triglyceride was associated with decreased risk of CVD (univariable OR, 0.91, 95% CI, 0.88-0.93; multivariable OR, 0.94, 95% CI, 0.92-0.97) among patients with <15 years of duration of diabetes but increased risk of CVD (univariable OR, 1.12, 95% CI, 1.04-1.21; multivariable OR, 1.18, 95% CI, 1.09-1.27) among those patients with 15 and more years of duration of diabetes with significant additive interactions (relative excess risk due to interaction, 0.39, 95% CI, 0.25-0.52; attributable proportion due to interaction, 0.20, 95% CI, 0.14-0.27; and synergy index, 1.80, 95% CI, 1.43-2.28).

CONCLUSIONS

Whereas a high triglyceride level was associated with increased risk of CVD in short-term T2DM, low triglyceride was associated with increased CVD risk in long-term T2DM. Low triglyceride may be a marker of CVD risk in Chinese patients with long-term T2DM.

Risk of non-fatal cardiovascular diseases in early-onset versus late-onset type 2 diabetes in China: a cross-sectional study

BACKGROUND

The age of onset of type 2 diabetes is decreasing. Because non-Chinese patients with early-onset type 2 diabetes (defined here as diagnosis at <40 years) have increased risk of vascular complications, we investigated effects of early-onset versus late-onset type 2 diabetes on risk of non-fatal cardiovascular diseases in China.

METHODS

We did a cross-sectional survey using data from the China National HbA1c Surveillance System (CNHSS), including 222,773 Chinese patients with type 2 diabetes in 630 hospitals from 106 cities in 30 provinces of China in 2012. We documented demographic information and clinical profiles. Non-fatal cardiovascular disease was defined as non-fatal coronary heart disease or non-fatal stroke. Prevalence of non-fatal cardiovascular diseases was standardised to the Chinese population in 2011. We did logistic regression analysis to obtain odds ratios (ORs) for the risk of cardiovascular disease in patients with early-onset versus late-onset type 2 diabetes. Because the CNHSS did not contain patients on diet or lifestyle treatment alone, and did not capture information on smoking or lipid or antihypertensive treatment, we validated our findings in another dataset from a cross-sectional, multicentre observational study (the 3B study) of outpatients with type 2 diabetes to confirm that exclusion of patients with diet treatment only and non-adjustment for lipid-lowering and antihypertensive drugs did not introduce major biases in the main analysis.

FINDINGS

Of 222,773 patients recruited from April 1, 2012, to June 30, 2012, 24,316 (11%) had non-fatal cardiovascular disease. Patients with early-onset diabetes had a higher age-adjusted prevalence of non-fatal cardiovascular disease than did patients with late-onset diabetes (11·1% vs 4·9%; p<0·0001). After adjustment for age and sex, patients with early-onset type 2 diabetes had higher risk of non-fatal cardiovascular disease than did those with late-onset type 2 diabetes (OR 1·91, 95% CI 1·81-2·02). Adjustment for duration of diabetes greatly attenuated the effect size for risk of non-fatal cardiovascular disease (1·13, 1·06-1·20). Results of the validation study showed that exclusion of patients with diet only and non-adjustment for lipid-lowering and antihypertensive drugs resulted in marginal changes in ORs for risk of non-fatal cardiovascular disease in patients with early-onset versus late-onset type 2 diabetes. Early-onset type 2 diabetes remained associated with increased risk of cardiovascular disease, attributable to longer duration of diabetes.

INTERPRETATION

Chinese patients with early-onset type 2 diabetes are at increased risk of non-fatal cardiovascular disease, mostly attributable to longer duration of diabetes.

FUNDING

Novo Nordisk China (for the China National HbA1c Surveillance System [CNHSS]) and Merck Sharp & Dohme China (for the 3B study).

Drug-subphenotype interactions for cancer in type 2 diabetes mellitus

On the basis of data obtained from a prospective cohort of Chinese patients with type 2 diabetes mellitus (T2DM), we discuss cancer subphenotypes (risk factors) in patients with T2DM, which can lead to drug-cancer subphenotype interactions. These subphenotypes include HDL cholesterol levels <1.0 mmol/l, co-occurrence of LDL cholesterol levels <2.8 mmol/l and triglyceride levels <1.7 mmol/l, and co-occurrence of LDL cholesterol levels <2.8 mmol/l and albuminuria. The increased risk of cancer associated with low levels of HDL cholesterol, low LDL cholesterol levels plus low triglyceride levels, and low levels of LDL cholesterol plus albuminuria can be reduced by treatment with metformin, renin-angiotensin system (RAS) inhibitors and statins, respectively. Mechanistic studies support the hypothesis that dysregulation of the 5'-AMP-activated protein kinase pathway and crosstalk between the RAS and insulin-like growth factor 1-cholesterol pathways create a cancer-promoting milieu in patients with T2DM. These findings highlight that in Chinese individuals, multiple pathways are implicated in the link between T2DM and cancer, which can generate multiple subphenotypes as well as drug-subphenotype interactions.

Hyperglycemia and blood pressure treatment goal: a cross sectional survey of 18350 patients with type 2 diabetes in 77 tertiary hospitals in China

OBJECTIVE

To investigate the association of hyperglycemia with blood pressure control goal in the patients with type 2 diabetes (T2D) cared by tertiary hospitals in China.

STUDY DESIGN AND METHODS

A cross sectional survey of 29442 patients was conducted in 77 tertiary hospitals in 4 major cities in China in 2011 and 18350 of them without known hypertension were used in the analysis. Univariable and multivariable logistic regression analysis stratified on cities and hospitals was performed to obtain odds ratio of factors of interest for achievement of the blood pressure treatment goal, i.e., 140/80 mmHg as recommended by American Diabetes Association (ADA). Sensitivity analysis was performed after re-inclusion of 11902 patients with diagnosed hypertension. Findings from were further replicated in patients with T2D recruited using the same protocol from tertiary hospitals located in other central cities in China.

RESULTS

The mean age was 58.2 (SD: 11.3) years and 53.3% were male, with a median of 4 years of disease duration. A total of 12129 patients (58.2%) did not achieve the ADA recommended goal for BP control. After adjusting for covariables, hyperglycemia was associated with failure to achieve the BP goal (OR of HbA1c at 6.5%-6.9% vs. <6.0%: 1.22, 95%CI: 1.08 to 1.39; OR of 7.0%-7.0% vs. <6.0%: 1.37, 1.21 to 1.54 and OR of ≥ 8.0% vs. <6.0%: 1.22, 95%CI: 1.08 to 1.38). The sensitivity analysis and the replication analysis showed similar results.

CONCLUSIONS

Hyperglycemia defined as HbA1c ≥ 6.5% increased the risk of failure to achieve the BP goal in T2D patients.

Diabetes and cancer: the mechanistic implications of epidemiological analyses from the Hong Kong Diabetes Registry

Diabetes is a disorder of energy metabolism associated with increased cancer risk, but the underlying mechanism is poorly understood. In a prospective cohort of patients enrolled in the Hong Kong Diabetes Registry, we explored risk factors for cancer including drug usage in type 2 diabetes. In a series of published papers, we reported a linear risk association of cancer with glycated haemoglobin with a threshold at 6.0%-6.5% and non-linear risk associations of body mass index, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglyceride and white blood cell (WBC) count in V-shaped or A-shaped manners. Detailed pharmacoepidemiological analysis revealed markedly attenuated cancer risk in patients treated with insulin and oral anti-diabetic drugs compared with non-users of these drugs. We further observed significant drug-subphenotype interactions with attenuated cancer risk in metformin users with low high-density lipoprotein cholesterol, renin-angiotensin system (RAS) inhibitor users with high WBC count and statin users with co-presence of low low-density lipoprotein cholesterol plus albuminuria or low triglyceride. These novel observations corroborate with experimental findings of possible consequences of hyperglycaemia on dysregulation of cholesterol metabolism, renin-angiotensin system and adenosine 5'-monophosphate-activated protein kinase pathways, all of which may be implicated in carcinogenesis. On the basis of these epidemiological and experimental findings, we argue for the strong need to strengthen the health care system to ensure that type 2 diabetes subjects receive appropriate drugs to optimize internal milieu to reduce all events including cancer. Apart from mechanistic studies, large-scale, randomized clinical trials using medications such as statin, renin-angiotensin system inhibitors and metformin in patients with risk-conferring subphenotypes are needed to confirm their anti-cancer effects.

Novel concepts in the genesis of hypertension: role of LOX-1

Hypertension is a common disease and a potent risk factor for cardiovascular disease. Tremendous strides have been made in understanding its genesis in the last 2 decades. Hypertension is often clustered with other cardiovascular risk factors, such as dyslipidemia and diabetes. The state of hypertension is often associated with increased vascular oxidative stress. Oxidative stress promotes proliferation and hypertrophy of vascular smooth muscle cell and collagen deposition, leading to thickening of the vascular media and narrowing of the vascular lumen. Oxidative stress also injures endothelium, impairs endothelium-dependent vascular relaxation and increases vascular contractile activity. Further, oxidative stress also oxidizes LDL-cholesterol. It has been shown that oxidized low-density lipoprotein (ox-LDL) activates renin-angiotensin system (RAS) and angiotensin II via its type 1 receptor activates ox-LDL receptor LOX-1. This mutually facilitative cross-talk between ox-LDL and RAS may be an important component in the development of hypertension. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a receptor for ox-LDL. This review summarizes the role of LOX-1 in the pathogenesis of hypertension.

Oxidative stress and lectin-like ox-LDL-receptor LOX-1 in atherogenesis and tumorigenesis

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) has been identified as a major receptor for oxidized low-density lipoprotein (ox-LDL) in endothelial cells, monocytes, platelets, cardiomyocytes, and vascular smooth muscle cells. Its expression is minimal under physiological conditions but can be induced under pathological conditions. The upregulation of LOX-1 by ox-LDL appears to be important for physiologic processes, such as endothelial cell proliferation, apoptosis, and endothelium remodeling. Pathophysiologic effects of ox-LDL in atherogenesis have also been firmly established, including endothelial cell dysfunction, smooth muscle cell growth and migration, monocyte transformation into macrophages, and finally platelet aggregation-seen in atherogenesis. Recent studies show a positive correlation between increased serum ox-LDL levels and an increased risk of colon, breast, and ovarian cancer. As in atherosclerosis, ox-LDL and its receptor LOX-1 activate the inflammatory pathway through nuclear factor-kappa B, leading to cell transformation. LOX-1 is important for maintaining the transformed state in developmentally diverse cancer cell lines and for tumor growth, suggesting a molecular connection between atherogenesis and tumorigenesis.

Cellular and molecular pathways to myocardial necrosis and replacement fibrosis

Fibrosis is a fundamental component of the adverse structural remodeling of myocardium present in the failing heart. Replacement fibrosis appears at sites of previous cardiomyocyte necrosis to preserve the structural integrity of the myocardium, but not without adverse functional consequences. The extensive nature of this microscopic scarring suggests cardiomyocyte necrosis is widespread and the loss of these contractile elements, combined with fibrous tissue deposition in the form of a stiff in-series and in-parallel elastic elements, contributes to the progressive failure of this normally efficient muscular pump. Cellular and molecular studies into the signal-transducer-effector pathway involved in cardiomyocyte necrosis have identified the crucial pathogenic role of intracellular Ca2+ overloading and subsequent induction of oxidative stress, predominantly confined within its mitochondria, to be followed by the opening of the mitochondrial permeability transition pore that leads to the destruction of these organelles and cells. It is now further recognized that Ca2+ overloading of cardiac myocytes and mitochondria serves as a prooxidant and which is counterbalanced by an intrinsically coupled Zn2+ entry serving as antioxidant. The prospect of raising antioxidant defenses by increasing intracellular Zn2+ with adjuvant nutriceuticals can, therefore, be preferentially exploited to uncouple this intrinsically coupled Ca2+ - Zn2+ dyshomeostasis. Hence, novel yet simple cardioprotective strategies may be at hand that deserve to be further explored.

Use of sulphonylurea and cancer in type 2 diabetes-The Hong Kong Diabetes Registry

BACKGROUND

Hyperglycaemia is a risk factor for cancer and some sulphonylureas have anti-oxidant properties. This study examined associations between use of sulphonylureas and cancer.

METHODS

A consecutive cohort of 6103 Hong Kong Chinese patients with T2DM, free of cancer, was analysed using Cox models. Sulphonylurea usage was defined as use of the drugs at or within 2.5 years before enrolment and/or during follow-up periods. We adjusted for identified risk factors of cancer, use of other drugs, non-linear associations of lipids with cancer and probabilities of use of these drugs at different times and doses where appropriate.

RESULTS

During a median of 4.91 years of follow-up, 271 developed cancer. Glibenclamide, gliclazide and glipizide were ever used in 32.5% (n = 1983), 47.8% (n = 2920) and 13.5% (n = 823). After adjustment for covariates, use of gliclazide and glibenclamide was associated with reduced cancer risk in a dose-dependent manner. In addition, there were interactions between metformin and glibenclamide/glipizide use towards lower adjusted cancer risks.

CONCLUSIONS

In T2DM, use of glibenclamide and gliclazide may be associated with reduced cancer risk.

Congestive heart failure: where homeostasis begets dyshomeostasis

Despite today's standard of care, aimed at preventing homeostatic neurohormonal activation, one in every five patients recently hospitalized with congestive heart failure (CHF) will be readmitted within 30 days of discharge because of a recurrence of their symptoms and signs. In light of recent pathophysiological insights, it is now propitious to revisit CHF with a view toward complementary and evolving management strategies. CHF is a progressive systemic illness. Its features include: oxidative stress in diverse tissues; an immunostimulatory state with circulating proinflammatory cytokines; a wasting of soft tissues; and a resorption of bone. Its origins are rooted in homeostatic mechanisms gone awry to beget dyshomeostasis. For example, marked excretory losses of Ca2+ and Mg2+ accompany renin-angiotensin-aldosterone system activation, causing ionized hypocalcemia and hypomagnesemia that lead to secondary hyperparathyroidism with consequent bone resorption and a propensity to atraumatic fractures. Parathyroid hormone accounts for paradoxical intracellular Ca2+ overloading in diverse tissues and consequent systemic induction of oxidative stress. In cardiac myocytes and mitochondria, these events orchestrate opening of the mitochondrial permeability transition pore with an ensuing osmotic-based destruction of these organelles and resultant cardiomyocyte necrosis with myocardial scarring. Contemporaneous with Ca2+ and Mg2+ dyshomeostasis is hypozincemia and hyposelenemia, which compromise metalloenzyme-based antioxidant defenses, whereas hypovitaminosis D threatens Ca2+ stores needed to prevent secondary hyperparathyroidism. An intrinsically coupled dyshomeostasis of intracellular Ca2+ and Zn2+, representing pro-oxidant and antioxidant, respectively, is integral to regulating the mitochondrial redox state; it can be uncoupled by a Zn2+ supplement in favor of antioxidant defenses. Hence, the complementary use of nutriceuticals to nullify dyshomeostatic responses involving macro- and micronutrients should be considered. Evolving strategies with mitochondria-targeted interventions interfering with their uptake of Ca2+ or serving as selective antioxidant or mitochondrial permeability transition pore inhibitor may also prove efficacious in the overall management of CHF.

Regional vascular response to ProAngiotensin-12 (PA12) through the rat arterial system

ProAngiotensin-12 (PA12) is the most recent peptide to be identified as a functional component of the renin-angiotensin system (RAS). PA12 is reported to constrict rat coronary arteries and the aorta, dependent upon angiotensin II-converting enzyme 1 (ACE1) and chymase. The current study employed myography to determine the direct vascular effects of PA12 on a range of isolated rat arteries extending from the core to periphery. PA12 significantly constricted the descending thoracic aorta, right and left common carotid arteries, abdominal aorta and superior mesenteric artery, with little effect on the femoral and renal arteries. AngII was found to produce similar responses to PA12 when administered at the same dose. A potency gradient in response to PA12 was clearly apparent, with vessels in closest proximity to the heart responding with the greatest constriction; while constrictive potency was lost further form the heart. Inhibition of ACE1 and chymase both significantly attenuated PA12-induced vasoconstriction, with chymostatin displaying lesser potency. We postulate ACE1 primarily regulates RAS activity within the circulation, while chymase may have an important role in local, tissue-based RAS activity.

Uncoupling the coupled calcium and zinc dyshomeostasis in cardiac myocytes and mitochondria seen in aldosteronism

Intracellular [Ca2+]i overloading in cardiomyocytes is a fundamental pathogenic event associated with chronic aldosterone/salt treatment (ALDOST) and accounts for an induction of oxidative stress that leads to necrotic cell death and consequent myocardial scarring. This prooxidant response to Ca2+ overloading in cardiac myocytes and mitochondria is intrinsically coupled to simultaneous increased Zn2+ entry serving as an antioxidant. Herein, we investigated whether Ca2+ and Zn2+ dyshomeostasis and prooxidant to antioxidant dysequilibrium seen at 4 weeks, the pathologic stage of ALDOST, could be uncoupled in favor of antioxidants, using cotreatment with a ZnSO4 supplement; pyrrolidine dithiocarbamate (PDTC), a Zn2+ ionophore; or ZnSO4 in combination with amlodipine (Amlod), a Ca2+ channel blocker. We monitored and compared responses in cardiomyocyte free [Ca2+]i and [Zn2+]i together with biomarkers of oxidative stress in cardiac myocytes and mitochondria. At week 4 of ALDOST and compared with controls, we found (1) an elevation in [Ca2+]i coupled with [Zn2+]i and (2) increased mitochondrial H2O2 production and increased mitochondrial and cardiac 8-isoprostane levels. Cotreatment with the ZnSO4 supplement alone, PDTC, or ZnSO4+Amlod augmented the rise in cardiomyocyte [Zn2+]i beyond that seen with ALDOST alone, whereas attenuating the rise in [Ca2+]i, which together served to reduce oxidative stress. Thus, a coupled dyshomeostasis of intracellular Ca2+ and Zn2+ was demonstrated in cardiac myocytes and mitochondria during 4-week ALDOST, where prooxidants overwhelm antioxidant defenses. This intrinsically coupled Ca2+ and Zn2+ dyshomeostasis could be uncoupled in favor of antioxidant defenses by selectively increasing free [Zn2+]i and/or reducing [Ca2+]i using cotreatment with ZnSO4 or PDTC alone or ZnSO4+Amlod in combination.

Associations of hyperglycemia and insulin usage with the risk of cancer in type 2 diabetes: the Hong Kong diabetes registry

OBJECTIVE Insulin has mitogenic effects, although hyperglycemia may be a risk factor for cancer in type 2 diabetes. It remains uncertain whether use of insulin increases cancer risk because of its effect on cell growth and proliferation or decreases cancer risk because of its glucose-lowering effect. RESEARCH DESIGN AND METHODS A 1:2-matched new insulin user cohort on age (+/-3 years), smoking status, and likelihood of initiating insulin therapy (+/-0.05) was selected from a cohort of 4,623 Chinese patients with type 2 diabetes, free of cancer, and naive to insulin at enrollment. Stratified Cox regression analysis on the matched pairs was used to obtain hazard ratios (HRs) of insulin therapy and A1C for cancer risk. A structured adjustment scheme was used to adjust for covariates. RESULTS Of 973 new insulin users, 971 had matched nonusers (n = 1935). The cancer incidence in insulin nonusers was much higher than that in insulin users (49.2 vs. 10.2, per 1,000 person-years, P < 0.0001). After further adjustment for all other covariates with a P value less than 0.3 and nonlinear associations with cancer, A1C was associated with an increased cancer risk (HR per percentage 1.26, 95% CI 1.03-1.55), whereas use of insulin was associated with a decreased cancer risk (HR of insulin users vs. nonusers: 0.17, 0.09-0.32). Consistent results were found in analyses including all 973 insulin users and 3,650 nonusers. CONCLUSIONS In Chinese patients with type 2 diabetes, hyperglycemia predicts cancer, whereas insulin usage was associated with a reduced cancer risk.

Coupled calcium and zinc dyshomeostasis and oxidative stress in cardiac myocytes and mitochondria of rats with chronic aldosteronism

A dyshomeostasis of extra- and intracellular Ca(2+) and Zn(2+) occurs in rats receiving chronic aldosterone/salt treatment (ALDOST). Herein, we hypothesized that the dyshomeostasis of intracellular Ca(2+) and Zn(2+) is intrinsically coupled that alters the redox state of cardiac myocytes and mitochondria, with Ca(2+) serving as a pro-oxidant and Zn(2+) as an antioxidant. Toward this end, we harvested hearts from rats receiving 4 weeks of ALDOST alone or cotreatment with either spironolactone (Spiro), an aldosterone receptor antagonist, or amlodipine (Amlod), an L-type Ca(2+) channel blocker, and from age/sex-matched untreated controls. In each group, we monitored cardiomyocyte [Ca(2+)]i and [Zn(2+)]i and mitochondrial [Ca(2+)]m and [Zn(2+)]m; biomarkers of oxidative stress and antioxidant defenses; expression of Zn transporters, Zip1 and ZnT-1; metallothionein-1, a Zn(2+)-binding protein; and metal response element transcription factor-1, a [Zn(2+)]i sensor and regulator of antioxidant defenses. Compared with controls, at 4-week ALDOST, we found the following: (a) increased [Ca(2+)]i and [Zn(2+)]i, together with increased [Ca(2+)]m and [Zn(2+)]m, each of which could be prevented by Spiro and attenuated with Amlod; (b) increased levels of 3-nitrotyrosine and 4-hydroxy-2-nonenal in cardiomyocytes, together with increased H(2)O(2) production, malondialdehyde, and oxidized glutathione in mitochondria that were coincident with increased activities of Cu/Zn superoxide dismutase and glutathione peroxidase; and (c) increased expression of metallothionein-1, Zip1 and ZnT-1, and metal response element transcription factor-1, attenuated by Spiro. Thus, an intrinsically coupled dyshomeostasis of intracellular Ca(2+) and Zn(2+) occurs in cardiac myocytes and mitochondria in rats receiving ALDOST, where it serves to alter their redox state through a respective induction of oxidative stress and generation of antioxidant defenses. The importance of therapeutic strategies that can uncouple these two divalent cations and modulate their ratio in favor of sustained antioxidant defenses is therefore suggested.