Telomere biology in heart failure

Cardiac telomere attrition following changes in the expression of shelterin genes in pulmonary hypertensive chickens

1. The alterations of relative telomere length and expression of shelterin genes (TRF1, TRF2, RAP1, POT1, and TPP1) were evaluated from the chickens' right heart ventricle in the early and last stages of cold-induced pulmonary hypertension (PHS) at 21 and 42 d of age.2. The relative telomere length in the right ventricular tissues was significantly shorter in the PHS group of broilers than in the control group at 42 d, but did not statistically change at 21 d of age. There was a significant negative correlation between relative telomere length and RV:TV ratio in the broilers at 42 d of age.3. The relative expression of POT1, RAP1 and TPP1 genes in the right ventricular tissues was significantly lower in the PHS group than in the control group at 21 d. The relative expression of the TRF2 gene was only higher in the PHS group of broilers than control at 42 d. The mRNA level of the TRF2 gene exhibited a significant positive correlation with RV:TV ratio at 42 d.4. It was concluded that most shelterin genes are dysregulated in the early stage of PHS (right ventricular hypertrophy) while telomere attrition occurs only at the last stage (heart dilation/failure).

Influences of Long-Term Exercise and High-Fat Diet on Age-Related Telomere Shortening in Rats

(1) Obesity and exercise are believed to modify age-related telomere shortening by regulating telomerase and shelterins. Existing studies are inconsistent and limited to peripheral blood mononuclear cells (PBMCs) and selected solid tissues. (2) Female Sprague Dawley (SD) rats received either standard diet (ND) or high-fat diet (HFD). For 10 months, half of the animals from both diet groups performed 30 min running at 30 cm/s on five consecutive days followed by two days of rest (exeND, exeHFD). The remaining animals served as sedentary controls (coND, coHFD). Relative telomere length (RTL) and mRNA expression of telomerase (TERT) and the shelterins TERF-1 and TERF-2 were mapped in PBMCs and nine solid tissues. (3) At study end, coND and coHFD animals showed comparable RTL in most tissues with no systematic differences in TERT, TERF-1 and TERF-2 expression. Only visceral fat of coHFD animals showed reduced RTL and lower expression of TERT, TERF-1 and TERF-2. Exercise had heterogeneous effects on RTL in exeND and exeHFD animals with longer telomeres in aorta and large intestine, but shorter telomeres in PBMCs and liver. Telomere-regulating genes showed inconsistent expression patterns. (4) In conclusion, regular exercise or HFD cannot systematically modify RTL by regulating the expression of telomerase and shelterins.

Conventional Risk Factors, Telomere Length, and Ischemic Heart disease: Insights into the Mediation Analysis

Telomere length is regarded as a potential biomarker of biological ageing and is associated with various age-related diseases, such as ischemic heart disease (IHD), myocardial infarction, peripheral vascular disease, and cancer. As there is a paucity of study that deals with this influence, this study aimed to assess how the cardiovascular risk factors influence the risk of IHD by performing mediation analysis. A total of 407 males were included in the study. IHD was diagnosed through echocardiography and coronary angiography by determining the number of coronary vessels involved. Demographic data, clinical history, and laboratory investigations such as random blood sugar (RBS), fasting lipid profile, serum creatinine, and serum urea levels of all the subjects were measured and recorded. Serum uric acid and blood urea nitrogen (BUN) levels were significantly higher in IHD subjects compared to non-IHD subjects (P < 0.05). Body mass index (BMI), glycosylated hemoglobin (HbA1c), RBS, serum uric acid, serum creatinine, BUN, total cholesterol, triglycerides, and telomere length significantly differed between subjects with and without IHD (P < 0.05). Further, telomere length (P < 0.001), BMI (P < 0.001), and total cholesterol level (P < 0.001) were risk factors that significantly affected the incidence of IHD, as proved by logistic regression. It indicates that shorter telomeres contribute to increased risk of IHD, influenced by BMI, HbA1c, BUN, total cholesterol levels, and RBS (P < 0.001). The study established a link between telomere shortening, conventional risk factors, and IHD; moreover, the study takes care in the role of mediation analysis which is a novel idea as little is done in this area of biostatistics with telomere length. Overall, this further establishes that telomeres length might serve as the promising biomarkers in predicting the risk of IHD.

Physical activity, a modulator of aging through effects on telomere biology

Aging is a complex process that is not well understood but involves finite changes at the genetic and epigenetic level. Physical activity is a well-documented modulator of the physiological process of aging. It has been suggested that the beneficial health effects of regular exercise are at least partly mediated through its effects on telomeres and associated regulatory pathways. Telomeres, the region of repetitive nucleotide sequences functioning as a "cap" at the chromosomal ends, play an important role to protect genomic DNA from degradation. Telomeres of dividing cells progressively shorten with age. Leucocyte telomere length (TL) has been associated with age-related diseases. Epidemiologic evidence indicates a strong relationship between physical activity and TL. In addition, TL has also been shown to predict all-cause and cardiovascular mortality. Experimental studies support a functional link between aerobic exercise and telomere preservation through activation of telomerase, an enzyme that adds nucleotides to the telomeric ends. However, unresolved questions regarding exercise modalities, pathomechanistic aspects and analytical issues limit the interpretability of available data. This review provides an overview about the current knowledge in the area of telomere biology, aging and physical activity. Finally, the capabilities and limitations of available analytical methods are addressed.

Emerging role of stem cell-derived extracellular microRNAs in age-associated human diseases and in different therapies of longevity

Organismal aging involves the progressive decline in organ function and increased susceptibility to age-associated diseases. This has been associated with the aging of stem cell populations within the body that decreases the capacity of stem cells to self-renew, differentiate, and regenerate damaged tissues and organs. This review aims to explore how aging is associated with the dysregulation of stem cell-derived extracellular vesicles (SCEVs) and their corresponding miRNA cargo (SCEV-miRNAs), which are short non-coding RNAs involved in post-transcriptional regulation of target genes. Recent evidence has suggested that in aging stem cells, SCEV-miRNAs may play a vital role regulating various processes that contribute to aging: cellular senescence, stem cell exhaustion, telomere length, and circadian rhythm. Hence, further clarifying the age-dependent molecular mechanisms through which SCEV-miRNAs exert their downstream effects may inform a greater understanding of the biology of aging, elucidate their role in stem cell function, and identify important targets for future regenerative therapies. Additionally, current studies evaluating therapeutic role of SCEVs and SCEV-miRNAs in treating several age-associated diseases are also discussed.

Clinical associations with telomere length in chronic spinal cord injury

STUDY DESIGN

Cross-sectional study OBJECTIVES: To determine clinical factors associated with telomere length in persons with chronic spinal cord injury (SCI).

SETTING

Veterans Affairs Medical Center, Boston, MA.

METHODS

Two hundred seventy-eight participants with chronic SCI provided blood samples for measurement of C-reactive protein (CRP), interleukin-6 (IL-6), and telomere length, completed respiratory health questionnaires, underwent dual X-ray absorptiometry (DXA) to assess body fat, and completed spirometry. High-throughput real-time PCR assays were used to assess telomere length in leukocyte genomic DNA. Linear regression models were used to assess cross-sectional associations with telomere length.

RESULTS

Telomere length was inversely related to age (p < 0.0001). In age-adjusted models, gender, race, injury duration, %-total and %-trunk fat, body mass index (BMI), %-predicted forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV₁), chronic cough or phlegm, CRP, IL-6, wheeze, smoking, diabetes, heart disease, chronic obstructive pulmonary disease (COPD), skin ulcer, urinary tract infection (UTI), or chest illness history were not significantly associated with telomere length. There was a suggestive age-adjusted association between persons with the most severe SCI (cervical motor complete and AIS C) and shorter telomere length (p = 0.055), an effect equivalent to ~8.4 years of premature aging. There were similar age-adjusted associations with telomere length between persons using a wheelchair (p = 0.059) and persons with chronic urinary catheter use (p = 0.082) compared to persons without these characteristics.

CONCLUSIONS

Our results suggest that clinical characteristics such as decreased mobility and bladder dysfunction that are common in individuals with more severe SCI are associated with shorter telomere length.

mTOR and Aging: An Old Fashioned Dress

Aging is a physiologic/pathologic process characterized by a progressive impairment of cellular functions, supported by the alterations of several molecular pathways, leading to an increased cell susceptibility to injury. This deterioration is the primary risk factor for several major human pathologies. Numerous cellular processes, including genomic instability, telomere erosion, epigenetic alterations, loss of proteostasis, deregulated nutrient-sensing, mitochondrial dysfunction, stem cell exhaustion, and altered intercellular signal transduction represent common denominators of aging in different organisms. Mammalian target of rapamycin (mTOR) is an evolutionarily conserved nutrient sensing protein kinase that regulates growth and metabolism in all eukaryotic cells. Studies in flies, worms, yeast, and mice support the hypothesis that the mTOR signalling network plays a pivotal role in modulating aging. mTOR is emerging as the most robust mediator of the protective effects of various forms of dietary restriction, which has been shown to extend lifespan and slow the onset of age-related diseases across species. Herein we discuss the role of mTor signalling network in the development of classic age-related diseases, focused on cardiovascular system, immune response, and cancer.

Differential effects of endurance, interval, and resistance training on telomerase activity and telomere length in a randomized, controlled study

Aims

It is unknown whether different training modalities exert differential cellular effects. Telomeres and telomere-associated proteins play a major role in cellular aging with implications for global health. This prospective training study examines the effects of endurance training, interval training (IT), and resistance training (RT) on telomerase activity and telomere length (TL).

Methods and results

One hundred and twenty-four healthy previously inactive individuals completed the 6 months study. Participants were randomized to three different interventions or the control condition (no change in lifestyle): aerobic endurance training (AET, continuous running), high-intensive IT (4 × 4 method), or RT (circle training on 8 devices), each intervention consisting of three 45 min training sessions per week. Maximum oxygen uptake (VO2max) was increased by all three training modalities. Telomerase activity in blood mononuclear cells was up-regulated by two- to three-fold in both endurance exercise groups (AET, IT), but not with RT. In parallel, lymphocyte, granulocyte, and leucocyte TL increased in the endurance-trained groups but not in the RT group. Magnet-activated cell sorting with telomerase repeat-ampliflication protocol (MACS-TRAP) assays revealed that a single bout of endurance training-but not RT-acutely increased telomerase activity in CD14+ and in CD34+ leucocytes.

Conclusion

This randomized controlled trial shows that endurance training, IT, and RT protocols induce specific cellular pathways in circulating leucocytes. Endurance training and IT, but not RT, increased telomerase activity and TL which are important for cellular senescence, regenerative capacity, and thus, healthy aging.

Metabolic Stress, Autophagy, and Cardiovascular Aging: from Pathophysiology to Therapeutics

Recent advances in health care have improved the management of cardiometabolic disorders, and prolonged lifespan. However, the ever-rising prevalence of metabolic stress related to obesity (insulin resistance, diabetes, hypertension, and dyslipidemia) has greatly challenged geriatric care. The ubiquitin-proteasome system and autophagy-lysosomal pathways represent two major, yet distinct cellular machineries, for degradation and removal of damaged or long-lived proteins and organelles; the function of which declines with aging. To seek new strategies for cardiovascular aging under various metabolic diseases, it is imperative to understand the precise role for metabolic stress and protein quality control, in particular autophagy, in premature cardiovascular aging. Targeting metabolic stress and autophagy may offer exciting new avenues for the management of cardiovascular aging.

High glucose condition limited the angiogenic/cardiogenic capacity of murine cardiac progenitor cells in in vitro and in vivo milieu

Murine c-kit⁺ cardiac cells were isolated and enriched by magnetic activated cell sorting technique. c-kit⁺ cells viability and colony-forming activity were evaluated by MTT and clonogenic assay. c-kit⁺ cells were exposed to endothelial, pericyte, and cardiomyocyte induction media containing 30mM glucose for 7 days. We monitored the level of endothelial (VE-cadherin, CD31, and vWF), pericyte (NG₂ , α-SMA, and PDGFR-β), and cardiomyocyte markers (cTnT) using flow cytometry, real-time Polymerase Chain Reaction (PCR), and Enzyme-Linked Immunosorbent Assay (ELISA) analyses. Ultrastructural changes were studied by transmission electron microscopy (TEM) in cells treated with 5-Azacytidine and 30mM glucose. Matrigel plug assay was performed to determine the angio/cardiogenic property of c-kit⁺ cells in a diabetic mouse model. Glucose of 30mM decreased c-kit⁺ cells viability and clonogenicity (P < 0.05). The transdifferentiation capacity of c-kit⁺ cells into the endothelial lineage, pericytes, and cardiomyocytes were reduced through the inhibition of related genes (P < 0.05). TEM analysis revealed cardiomyocyte differentiation rate in c-kit⁺ cells coincided with an increased intracellular lipid accumulation and reduced number of mitochondria. Similar to in vitro condition, the angiogenic capacity of c-kit⁺ cells was aborted in vivo indicated by reduced NG₂ , α-SMA, CD31, and vWF levels. High glucose condition reduces the angio/cardiogenic capacity of cardiac c-kit⁺ cells in vitro and in vivo. SIGNIFICANCE OF THE STUDY: High glucose condition seen in diabetes mellitus could affect the regenerative potential of cardiac tissue. The current experiment showed that the exposure of murine cardiac progenitor cells (CD117⁺ cells) to condition containing 30mM glucose could decrease the differentiation properties into endothelial cells, pericytes, and mature cardiomyocytes in vitro and in vivo. Our finding confirmed that the angiogenic/cardiogenic potential cardiac progenitor cells decrease under treatment with high glucose content as seen in the diabetic condition.

Leukocyte telomere length correlates with hypertrophic cardiomyopathy severity

Telomere length is a marker of biological aging. Short leukocyte telomere length has been associated with various conditions including cardiovascular disorders. Here, we evaluated if patients with hypertrophic cardiomyopathy have altered leukocyte telomere length and whether this is associated with disease severity. A quantitative polymerase chain reaction-based method was used to measure peripheral blood leukocyte telomere length in 59 healthy control subjects and a well-characterized cohort of 88 patients diagnosed with hypertrophic cardiomyopathy: 32 patients with non-obstructive cardiomyopathy (HNCM) and 56 patients with obstructive cardiomyopathy (HOCM). We observed shorter leukocyte telomeres in both HNCM and HOCM patients compared to healthy controls. Furthermore, leukocyte telomere length was inversely associated with HCM even after adjusting for age and sex. Telomere length of HOCM patients was also inversely correlated with left ventricular outflow tract obstruction. Therefore, HOCM patients were categorized by tertiles of telomere length. Patients in the first tertile (shortest telomeres) had a significantly increased left ventricular posterior wall thickness at end-diastole and higher left ventricular outflow tract gradients, whereas the left ventricular end-diastolic diameter was lower compared with patients in the second and third tertile. In summary, telomere length is associated with the severity of the disease in the HOCM subtype.

Stroke increases the risk of hip fracture: a systematic review and meta-analysis

Many studies have investigated the association between stroke and hip fracture risk, but the precise association was still unclear due to insufficient statistical power in single studies with relatively small sample size. Thus, we firstly conducted a meta-analysis of all published studies to precisely estimate the relationship of stroke with hip fracture risk. The strength for this relationship was weighed by pooled relative risks (RRs) with 95 % confidence intervals (95 % CIs) after adjustment for confounding variables. Stratified analyses by study design and ethnicity and sensitivity analysis were also performed. Two investigators independently performed a comprehensive literature search in databases of PubMed, Embase, and Wanfang for eligible articles. A Bayesian meta-analysis was also performed to get a more precise assessment of the relationship. Eleven relevant studies from 10 publications were finally included into our meta-analysis according to the inclusion criteria. Overall, stroke significantly and independently increased the risk of hip fracture (RR = 2.06, 95 % CI 1.68-2.52, P < 0.001). Bayesian meta-analysis showed that stroke was also associated with an over two-fold increased risk of hip fracture (RR = 2.11, 95 % CI 1.62-2.75). In stratified analysis, stroke could increase the risk of hip fracture in Caucasians (RR = 2.36, 95 % CI 1.83-3.05, P < 0.001). These data support the notion that stroke is an independent risk factor for hip fracture, and patients with stroke have a two-fold increased risk of hip fracture than those without stroke.

The influence of oxidative stress induced by iron on telomere length

Oxidative stress can be induced by increased concentrations of iron in the body and consequently can cause shortening of telomeres. Telomeres, called mitotic clocks, are non-coding fragments at the end of chromosomes. During the replication of genetic material they are shortened, playing the role of ageing biomarkers in eukaryotes. In human endothelial cells, oxidative stress causes a decrease in telomerase activity. Shortening of chromosomes in telomeric parts was found in patients with primary hemochromatosis and in patients taking supplements containing iron. Increased level of transferrin saturation is associated with the presence of shorter telomeres in the chromosomes of leukocytes. The relationship between iron status and telomere length is still not fully understood.

Abrogation of Age-Induced MicroRNA-195 Rejuvenates the Senescent Mesenchymal Stem Cells by Reactivating Telomerase

Previously, we reported that a novel subpopulation of young mesenchymal stem cells (YMSCs) existed in old bone marrow, which possessed high antiaging properties as well as excellent efficacy for cardiac repair. MicroRNAs (miRNAs) have emerged as key regulators in post-transcriptional gene expression programs, and however, it is unknown whether miRNAs directly control stem cell senescence. Here we present the first evidence that miR-195 overexpressed in old MSCs (OMSCs) induces stem cell senescence deteriorating their regenerative ability by directly deactivating telomerase reverse transcriptase (Tert), and abrogation of miR-195 can reverse stem cell aging. MiRNAs profiling analysis in YMSCs and OMSCs by microarray showed that miR-140, miR-146a/b, and miR-195 were significantly upregulated in OMSCs, which led us to hypothesize that these are age-induced miRNAs involved in stem cell senescence. Of these miRNAs, we found miR-195 directly targeted 3'-untranslated region of Tert gene by computational target prediction analysis and luciferase assay, and knockdown of miR-195 significantly increased Tert expression in OMSCs. Strikingly, miR-195 inhibition significantly induced telomere relengthening in OMSCs along with reduced expression of senescence-associated β-galactosidase. Moreover, silencing miR-195 in OMSCs by transfection of miR-195 inhibitor significantly restored antiaging factors expression including Tert and Sirt1 as well as phosphorylation of Akt and FOXO1. Notably, abrogation of miR-195 markedly restored proliferative abilities in OMSCs. Transplantation of OMSCs with knocked out miR-195 reduced infarction size and improved LV function. In conclusion, rejuvenation of aged stem cells by miR-195 inhibition would be a promising autologous therapeutic strategy for cardiac repair in the elderly patients.

Increased risk of coronary heart disease in patients with hip fracture: a nationwide cohort study

The study indicates that hip fracture is independently associated with increased risk of coronary heart disease. In addition, the highest risk of coronary heart disease following hip fracture appeared within the first year after hip fracture, indicating the need for multidisciplinary care for the patients.

INTRODUCTION

Bone and vasculature are modulated through numerous common pathways. However, data on the risk of coronary heart disease (CHD) after hip fracture are scarce. Therefore, we investigated whether hip fracture increased the risk of CHD by conducting a large nationwide cohort study.

METHODS

Using universal insurance claims data from 2000 to 2010, we identified a study cohort of 6013 participants newly diagnosed with hip fracture and a control cohort of 23,802 participants. Both cohorts were followed up to the end of 2011 to evaluate the risk of CHD.

RESULTS

The overall incidence of CHD was 1.69-fold higher in the hip fracture cohort than it was in the control cohort (29.2 vs. 17.1 per 1000 person-years) with an adjusted hazard ratio of 1.51 (95 % confidence interval [CI] = 1.39-1.65). Sex-, age-, and comorbidity-specific analyses showed a higher relative risk of CHD for both women and men, all age groups, those with and without comorbidities, and patients with hip fracture compared with the control cohort. The highest risk of CHD was within the first year after hip fracture (adjusted HR = 1.72, 95 % CI = 1.45-2.04), and the risk remained high in the following years.

CONCLUSION

Hip fracture was independently associated with a subsequent risk of CHD.

Leukocyte telomere length and left ventricular function after acute ST-elevation myocardial infarction: data from the glycometabolic intervention as adjunct to primary coronary intervention in ST elevation myocardial infarction (GIPS-III) trial

Background

Telomere length has been associated with coronary artery disease and heart failure. We studied whether leukocyte telomere length is associated with left ventricular ejection fraction (LVEF) after ST-elevation myocardial infarction (STEMI).

Methods and results

Leukocyte telomere length (LTL) was determined using the monochrome multiplex quantitative PCR method in 353 patients participating in the glycometabolic intervention as adjunct to primary percutaneous coronary intervention in STEMI III trial. LVEF was assessed by magnetic resonance imaging. The mean age of patients was 58.9 ± 11.6 years, 75 % were male. In age- and gender-adjusted models, LTL at baseline was significantly associated with age (beta ± standard error; −0.33 ± 0.01; P < 0.01), gender (0.15 ± 0.03; P < 0.01), TIMI flow pre-PCI (0.05 ± 0.03; P < 0.01), TIMI flow post-PCI (0.03 ± 0.04; P < 0.01), myocardial blush grade (−0.05 ± 0.07; P < 0.01), serum glucose levels (−0.11 ± 0.01; P = 0.03), and total leukocyte count (−0.11 ± 0.01; P = 0.04). At 4 months after STEMI, LVEF was well preserved (54.1 ± 8.4 %) and was not associated with baseline LTL (P = 0.95). Baseline LTL was associated with n-terminal pro-brain natriuretic peptide (NT-proBNP) at 4 months (−0.14 ± 0.01; P = 0.02), albeit not independent for age and gender.

Conclusion

Our study does not support a role for LTL as a causal factor related to left ventricular ejection fraction after STEMI.

The influence of the telomere-telomerase system on diabetes mellitus and its vascular complications

INTRODUCTION

The telomere-telomerase system plays an important role in the pathogenesis and disease progression of diabetes mellitus as well as in its vascular complications. Recent studies suggest that telomere shortening and abnormal telomerase activity occur in patients with diabetes mellitus, and targeting the telomere-telomerase system has become a prospective treatment for diabetes mellitus and its vascular complications. This review highlights the significance of the telomere-telomerase system and supports its role as a possible therapeutic target for patients with diabetes mellitus and its vascular complications Areas covered: This review covers the advances in understanding the telomere-telomerase system over the last 30 years and its significance in diabetes mellitus. In addition, it provides knowledge regarding the significance of the telomere-telomerase system in diabetes mellitus and its vascular complications as well as its role and mechanisms in oxidative stress, cell therapy and antioxidant activity Expert opinion: The telomere-telomerase system may be a potential therapeutic target that can protect against DNA damage and apoptosis in patients with diabetes mellitus and its vascular complications. DNA damage and apoptosis are associated with oxidative stress and are involved in the dysfunction of pancreatic β cells, insulin resistance, and its vascular complications. Abnormalities in the telomere-telomerase system may be associated with diabetes mellitus and its vascular complications. Therapies targeting telomere-telomerase system, telomerase reverse transcriptase transfection and alterative telomere lengthening must be identified before gene therapy can commence.

Increased risk of stroke among hip fracture patients: a nationwide cohort study

SUMMARY

Our study indicates that hip fracture is independently associated with increased risk of developing stroke. In addition, the risk of stroke following the incidence of hip fracture is more prominent in younger patients, men, those with cardiovascular comorbidities, and in patients using specific medication, such as diuretics and ABRs.

INTRODUCTION

Hip fractures are associated with increased risk of major morbidity. However, few data are available on the risk of stroke after hip fracture. Therefore, we investigated whether hip fracture increases the risk of stroke in a large nationwide cohort study.

METHODS

Using universal insurance claims data, we identified a study cohort comprising of 6013 newly diagnosed with hip fracture patients from 2000 to 2010 and a non-hip fracture cohort of 23,802 participants. Incidence and risk of stroke were estimated for both cohorts until the end of 2011.

RESULTS

Stroke incidence was 1.69-fold (95% confidence interval [CI]=1.56-1.83) higher in the hip fracture cohort than in the comparison cohort with an adjusted hazard ratio (HR) of 1.54 (95% CI=1.42-1.67) for the hip fracture cohort. The hip fracture patients were at higher risk of developing ischemic stroke (HR=1.55, 95% CI=1.42-1.69) and hemorrhagic stroke (HR=1.55, 95% CI=1.16-1.89), respectively. At an incidence of 64.6 per 1000 person-years, the adjusted HR of stroke increases to 3.10 (95% CI=2.47-3.90) for patients with coexisting diabetes, hypertension, and heart failure compared with those without these three conditions. At an incidence of 60.4 per 1000 person-years, the adjusted HR of stroke increases to 2.92 (95% CI=2.43-3.51) for hip fracture patients prescribed with diuretics and angiotensin II receptor blockers (ARBs) compared with those without hip fracture or prescriptions for diuretics or ARBs.

CONCLUSIONS

Hip fracture is independently associated with a subsequent risk of stroke.

Telomere, aging and age-related diseases

Aging is an inevitable biological process that affects most living organisms. The process of aging is regulated at the level of the organism, as well as at the level of tissues and cells. Despite the enormous consequences associated with the aging process, relatively little systematic effort has been expended on the scientific understanding of this important life process. Many theories have been proposed to explain the aging process, the centerpiece of which is molecular damage. Located at the ends of eukaryotic chromosomes and synthesized by telomerase, telomeres maintain the stabilization of chromosomes. Thus, the loss of telomeres may lead to DNA damage. The relationship between cellular senescence and telomere shortening is well established. Furthermore, telomere attrition occurs with age, and is proposed to be a fundamental factor in the aging process. Here, we review the contemporary literatures to explore the current views on the correlation of telomere loss and telomerase action with aging and age-related diseases.

Genetic variants implicated in telomere length associated with left ventricular function in patients with hypertension and cardiac organ damage

Telomere length has emerged as a biological correlate for ageing, which in turn is a risk factor for the manifestation of cardiovascular diseases. This study investigated the relation between leucocyte telomere length (LTL) and its genetic background to cardiac structure and function in patients with arterial hypertension. We analysed a cohort of 1,106 treated hypertensive patients (83.3% males; mean age, 57.9 ± 9.8 years) with an ejection fraction (EF) over 40% and documented cardiovascular disease or target organ damage. LTL and genotypes of single nucleotide polymorphisms (SNPs), previously implicated in LTL, were determined by real-time PCR. The mean left ventricular mass index (LVMI) and EF were 51.8  ±  21.0 g/H2.7 and 61.1  ±  9.6%, respectively. In multivariate adjusted analysis, a 1.5-fold LTL was positively related with a 2.2% increase of LVMI (CI = 0.1% to 4.2%, p = 0.044) and an absolute increase in EF of 0.6% (CI = 0.1% to 1.1%, p = 0.028). One SNP near TERC (rs16847897) showed a significant absolute difference in EF dependent on allele status (rs16847897, G allele 2.7%; CI = 0.7% to 4.6%; p raw = 0.008, p mt = 0.048, after adjustment for multiple testing). This applied also for two SNPs in BICD1 (rs2630578, C allele −1.8%; CI = −2.8% to −0.7%; p raw = 0.002, p mt = 0.018; rs1151026, G allele −1.9%, CI = −3.0% to −0.8%; p raw < 0.001, p mt = 0.002) with the extension that a frequent haplotype in BICD1 showed an absolute −1.8% (CI = −3.0% to −0.7%; p raw = 0.002, p mt = 0.008) lower EF compared with those lacking this haplotype. Our results point to a role of genetic variants recently implicated in LTL for left ventricular function in hypertensive patients.

Cardiovascular disease: primary prevention, disease modulation and regenerative therapy

Cardiovascular primary prevention and regeneration programs are the contemporary frontiers in functional metabolic vascular medicine. This novel science perspective harnesses our inherent ability to modulate the interface between specialized gene receptors and bioavailable nutrients in what is labeled as the nutrient-gene interaction. By mimicking a natural process through the conveyance of highly absorbable receptor specific nutrients, it is feasible to accelerate cell repair and optimize mitochondrial function, thereby achieving cardiovascular cure. We performed a comprehensive review of PubMed, EMBASE and Cochrane Review databases for articles relating to cardiovascular regenerative medicine, nutrigenomics and primary prevention, with the aim of harmonizing their roles within contemporary clinical practice. We searched in particular for large-scale randomized controlled trials on contemporary cardiovascular pharmacotherapies and their specific adverse effects on metabolic pathways which feature prominently in cardiovascular regenerative programs, such as nitric oxide and glucose metabolism. Scientific research on 'cardiovascular-free' centenarians delineated that low sugar and low insulin are consistent findings. As we age, our insulin level increases. Those who can decelerate the rapidity of this process are prompting their cardiovascular rejuvenation. It is beginning to dawn on some clinicians that contemporary treatments are not only failing to impact on our most prevalent diseases, but they may be causing more damage than good. Primary prevention programs are crucial elements for a better outcome. Cardiovascular primary prevention and regeneration programs have enhanced clinical efficacy and quality of life and complement our conventional endovascular practice.

Oxidative stress-induced telomeric erosion as a mechanism underlying airborne particulate matter-related cardiovascular disease

Particulate matter (PM) pollution is responsible for hundreds of thousands of deaths worldwide, the majority due to cardiovascular disease (CVD). While many potential pathophysiological mechanisms have been proposed, there is not yet a consensus as to which are most important in causing pollution-related morbidity/mortality. Nor is there consensus regarding which specific types of PM are most likely to affect public health in this regard. One toxicological mechanism linking exposure to airborne PM with CVD outcomes is oxidative stress, a contributor to the development of CVD risk factors including atherosclerosis. Recent work suggests that accelerated shortening of telomeres and, thus, early senescence of cells may be an important pathway by which oxidative stress may accelerate biological aging and the resultant development of age-related morbidity. This pathway may explain a significant proportion of PM-related adverse health outcomes, since shortened telomeres accelerate the progression of many diseases. There is limited but consistent evidence that vehicular emissions produce oxidative stress in humans. Given that oxidative stress is associated with accelerated erosion of telomeres, and that shortened telomeres are linked with acceleration of biological ageing and greater incidence of various age-related pathology, including CVD, it is hypothesized that associations noted between certain pollution types and sources and oxidative stress may reflect a mechanism by which these pollutants result in CVD-related morbidity and mortality, namely accelerated aging via enhanced erosion of telomeres. This paper reviews the literature providing links among oxidative stress, accelerated erosion of telomeres, CVD, and specific sources and types of air pollutants. If certain PM species/sources might be responsible for adverse health outcomes via the proposed mechanism, perhaps the pathway to reducing mortality/morbidity from PM would become clearer. Not only would pollution reduction imperatives be more focused, but interventions which could reduce oxidative stress would become all the more important.

Autophagy and cardiovascular aging: lesson learned from rapamycin

The biological aging process is commonly associated with increased risk of cardiovascular diseases. Several theories have been put forward for aging-associated deterioration in ventricular function, including attenuation of growth hormone (insulin-like growth factors and insulin) signaling, loss of DNA replication and repair, histone acetylation and accumulation of reactive oxygen species. Recent evidence has depicted a rather unique role of autophagy as another important pathway in the regulation of longevity and senescence. Autophagy is a predominant cytoprotective (rather than self-destructive) process. It carries a prominent role in determination of lifespan. Reduced autophagy has been associated with aging, leading to accumulation of dysfunctional or damaged proteins and organelles. To the contrary, measures such as caloric restriction and exercise may promote autophagy to delay aging and associated comorbidities. Stimulation of autophagy using rapamycin may represent a novel strategy to prolong lifespan and combat aging-associated diseases. Rapamycin regulates autophagy through inhibition of the nutrient-sensing molecule mammalian target of rapamycin (mTOR). Inhibition of mTOR through rapamycin and caloric restriction promotes longevity. The purpose of this review is to recapitulate some of the recent advances in an effort to better understand the interplay between rapamycin-induced autophagy and decelerating cardiovascular aging.

Age related cardiovascular dysfunction and effects of physical activity

The aim of the present article is to review the principal pathogenetic pathways of age-related cardiovascular changes and the positive effects of physical activity on these changes as well as on related cardiovascular dysfunction. The ageing mechanisms reviewed have been grouped into reduced tolerance of oxidative stress, loss of cardiac stem cells, cardiovascular remodeling and impairment of neurovegetative control. New pathogenetic conditions and their tests are described (sirtuines, telomere length, heart rate variability). Age related cardiovascular changes predispose the individual to arterial hypertension, heart failure and arrythmia. A broad spectrum of tests are available to indentify and monitor the emerging cardiovascular dysfunction. Physical activity influences all age related cardiovascular mechanisms, improves cardiovascular function and even, at moderate intensity can reduce mortality and heart attack risk. It is likely that the translation of laboratory studies to humans will improve understanding and stimulate the use of physical activity to benefit cardiovascular patients.

Molecular mechanisms of cardiomyocyte aging

Western societies are rapidly aging, and cardiovascular diseases are the leading cause of death. In fact, age and cardiovascular diseases are positively correlated, and disease syndromes affecting the heart reach epidemic proportions in the very old. Genetic variations and molecular adaptations are the primary contributors to the onset of cardiovascular disease; however, molecular links between age and heart syndromes are complex and involve much more than the passage of time. Changes in CM (cardiomyocyte) structure and function occur with age and precede anatomical and functional changes in the heart. Concomitant with or preceding some of these cellular changes are alterations in gene expression often linked to signalling cascades that may lead to a loss of CMs or reduced function. An understanding of the intrinsic molecular mechanisms underlying these cascading events has been instrumental in forming our current understanding of how CMs adapt with age. In the present review, we describe the molecular mechanisms underlying CM aging and how these changes may contribute to the development of cardiovascular diseases.

Aging, telomeres and heart failure

During normal aging, the heart undergoes functional, morphological and cellular changes. Although aging per se does not lead to the expression of heart failure, it is likely that age-associated changes lower the threshold for the manifestation of signs and symptoms of heart failure. In patients, the susceptibility, age of onset and pace of progression of heart failure are highly variable. The presence of conventional risk factors cannot completely explain this variability. Accumulation of DNA damage and telomere attrition results in an increase in cellular senescence and apoptosis, resulting in a decrease in the number and function of cells, contributing to the overall tissue and organ dysfunction. Biological aging, characterized by reduced telomere length, provides an explanation for the highly interindividual variable threshold to express the clinical syndrome of heart failure at some stage during life. In this review, we will elaborate on the current knowledge of aging of the heart, telomere biology and its potential role in the development of heart failure.

Healthy aging and disease: role for telomere biology?

Aging is a biological process that affects most cells, organisms and species. Human aging is associated with increased susceptibility to a variety of chronic diseases, including cardiovascular disease, Type 2 diabetes, neurological diseases and cancer. Despite the remarkable progress made during the last two decades, our understanding of the biology of aging remains incomplete. Telomere biology has recently emerged as an important player in the aging and disease process.

Physical exercise prevents cellular senescence in circulating leukocytes and in the vessel wall

BACKGROUND

The underlying molecular mechanisms of the vasculoprotective effects of physical exercise are incompletely understood. Telomere erosion is a central component of aging, and telomere-associated proteins regulate cellular senescence and survival. This study examines the effects of exercising on vascular telomere biology and endothelial apoptosis in mice and the effects of long-term endurance training on telomere biology in humans.

METHODS AND RESULTS

C57/Bl6 mice were randomized to voluntary running or no running wheel conditions for 3 weeks. Exercise upregulated telomerase activity in the thoracic aorta and in circulating mononuclear cells compared with sedentary controls, increased vascular expression of telomere repeat-binding factor 2 and Ku70, and reduced the expression of vascular apoptosis regulators such as cell-cycle-checkpoint kinase 2, p16, and p53. Mice preconditioned by voluntary running exhibited a marked reduction in lipopolysaccharide-induced aortic endothelial apoptosis. Transgenic mouse studies showed that endothelial nitric oxide synthase and telomerase reverse transcriptase synergize to confer endothelial stress resistance after physical activity. To test the significance of these data in humans, telomere biology in circulating leukocytes of young and middle-aged track and field athletes was analyzed. Peripheral blood leukocytes isolated from endurance athletes showed increased telomerase activity, expression of telomere-stabilizing proteins, and downregulation of cell-cycle inhibitors compared with untrained individuals. Long-term endurance training was associated with reduced leukocyte telomere erosion compared with untrained controls.

CONCLUSIONS

Physical activity regulates telomere-stabilizing proteins in mice and in humans and thereby protects from stress-induced vascular apoptosis.

Detection and prognostic impact of renal dysfunction in patients with chronic heart failure and normal serum creatinine

BACKGROUND

Accurate identification of renal dysfunction (RD) is crucial to risk stratification in chronic heart failure (CHF). Patients with CHF are at special risk of having RD despite normal serum creatinine (SCr), owing to a decreased Cr generation. At low levels of SCr, the equations estimating renal function are less accurate. This study was aimed to assess and compare the prognostic value of formulas estimating renal function in CHF patients with normal SCr.

METHODS

We studied 462 patients with systolic CHF and normal SCr. Creatinine clearance was estimated by the Cockcroft-Gault (eCrCl) and glomerular filtration rate by the 4-variable MDRD equation (eGFR); eCrCl normalized for body-surface area (eCrCl(BSA)) was calculated. The primary outcome was all-cause mortality at 2 years.

RESULTS

Seventy five patients died. At multivariate Cox regression analysis, only eCrCl(BSA) was significantly associated with mortality (p = 0.006); eGFR (p = 0.24), eCrCl (p = 0.09) and BUN (p = 0.14) were not statistically significant predictors. The patients in the lowest eCrCl(BSA) quartile had an adjusted 2.1-fold (CI: 1.06-4.1) increased risk of mortality, compared with those in the referent quartile. Two-year survival was 70.4% in the lowest eCrCl(BSA) quartile and 89.7% in the referent quartile. Other independent predictors of mortality were ischemic etiology (RR: 2.16 [CI: 1.3-3.5], p = 0.0017), NYHA III/IV class (RR: 2.45 [CI: 1.51-3.97], p = 0.0003), LVEF <0.25 (RR: 3.38 [CI: 1.69-6.75], p = 0.014), and anemia (RR: 1.86 [CI: 1.16-2.99], p = 0.009).

CONCLUSIONS

A sizeable proportion of CHF patients have prognostically significant RD despite normal SCr. Such patients represent a high-risk subgroup and can more accurately be identified by the CG formula corrected for BSA than the MDRD.

Long-term secondary prevention programs after cardiac rehabilitation for the reduction of future cardiovascular events: focus on regular physical activity

Cardiac rehabilitation/secondary prevention programs are recognized as integral to the comprehensive care of patients with coronary heart disease, and as such are recommended in most contemporary clinical practice guidelines. The interventions are aimed at reducing disability, optimizing cardiovascular risk reduction by drug therapy and promoting healthy behavior. Healthy lifestyle habits must be recognized as capable of substantially reducing the risk for cardiovascular events in patients with coronary heart disease. This review highlights the recommended components of cardiac rehabilitation/secondary prevention programs, with special emphasis on regular physical activity.