Ageing of the conduit arteries

Perforin-independent extracellular granzyme B activity contributes to abdominal aortic aneurysm

Granzyme B (GZMB) is a serine protease that is abundantly expressed in advanced human atherosclerotic lesions and may contribute to plaque instability. Perforin is a pore-forming protein that facilitates GZMB internalization and the induction of apoptosis. Recently a perforin-independent, extracellular role for GZMB has been proposed. In the current study, the role of GZMB in abdominal aortic aneurysm (AAA) was assessed. Apolipoprotein E (APOE)(-/-) x GZMB(-/-) and APOE(-/-) x perforin(-/-) double knockout (GDKO, PDKO) mice were generated to test whether GZMB exerted a causative role in aneurysm formation. To induce aneurysm, mice were given angiotensin II (1000 ng/kg/min) for 28 days. GZMB was found to be abundant in both murine and human AAA specimens. GZMB deficiency was associated with a decrease in AAA and increased survival compared with APOE-KO and PDKO mice. Although AAA rupture was observed frequently in APOE-KO (46.7%; n = 15) and PDKO (43.3%; n = 16) mice, rupture was rarely observed in GDKO (7.1%; n = 14) mice. APOE-KO mice exhibited reduced fibrillin-1 staining compared with GDKO mice, whereas in vitro protease assays demonstrated that fibrillin-1 is a substrate of GZMB. As perforin deficiency did not affect the outcome, our results suggest that GZMB contributes to AAA pathogenesis via a perforin-independent mechanism involving extracellular matrix degradation and subsequent loss of vessel wall integrity.

Importance of pulsatility in hypertensive carotid artery growth and remodeling

Arteries experience marked variations in blood pressure and flow during the cardiac cycle that can intensify during exercise, in disease, or with aging. Diverse observations increasingly suggest the importance of such pulsatility in arterial homeostasis and adaptations. We used a transverse aortic arch banding model to quantify chronic effects of increased pulsatile pressure and flow on wall morphology, composition, and biaxial mechanical properties in paired mouse arteries: the highly pulsatile right common carotid artery proximal to the band (RCCA-B) and the nearly normal left common carotid artery distal to the band (LCCA-B). Increased pulsatile mechanical stimuli in RCCA-B increased wall thickness compared with LCCA-B, which correlated more strongly with pulse (r* = 0.632; P < 0.01) than mean (r* = 0.020; P = 0.47) or systolic (r* = 0.466; P < 0.05) pressure. Similarly, inner diameter at mean pressure increased in RCCA-B and correlated slightly more strongly with a normalized index of blood velocity pulsatility (r* = 0.915; P < <0.001) than mean flow (r* = 0.834; P < 0.001). Increased wall thickness and luminal diameter in RCCA-B resulted from significant increases in cell number per cross-sectional area (P < 0.001) and collagen-to-elastin ratio (P < 0.05) as well as a moderate (1.7-fold) increase in glycosaminoglycan content, which appears to have contributed to the significant decrease (P < 0.001) in the in-vivo axial stretch in RCCA-B compared with LCCA-B. Changes in RCCA-B also associated with a signficant increase in monocyte chemoattractant protein-1 (P < 0.05) whereas LCCA-B did not. Pulsatile pressure and flow are thus important stimuli in the observed three-dimensional arterial adaptations, and there is a need for increased attention to the roles of both axial wall stress and adventitial remodeling.

A comprehensive histopathological evaluation of vascular medial fibrosis: insights into the pathophysiology of arterial stiffening

OBJECTIVE

Medial vascular fibrosis contributes to arterial stiffening and reduced compliance, increasing the risk of cardiovascular events. We undertook the first comprehensive histopathologic study of medium-to-large caliber blood vessels (carotid, coronary, dorsalis pedis, internal mammary, iliac, mesenteric, pulmonary, and renal arteries) in 100 autopsy subjects to characterize medial fibrosis in relation to cardiovascular risk factors.

METHODS AND RESULTS

Masson Trichrome staining of vascular tissue microarrays (TMAs) was digitally analyzed to determine the percent fibrosis (% collagen) of over 700 vascular segments. The percent fibrosis of the tunica media was strongly correlated within subjects across all systemic blood vessels (average r=0.53), suggesting that fibrosis is a global process independent of the predilection of the vessel towards the development of atherosclerosis. Hypertension, diabetes, age and poor renal function were significantly associated with increased systemic vascular fibrosis (p< or =0.03). By multivariable analysis, only poor renal function (p=0.003) was an independent predictor of higher levels of fibrosis. Finally, in a subset of 13 individuals we observed a significant correlation between pre-mortem pulse pressure and systemic vascular fibrosis (p<0.001).

CONCLUSIONS

This study demonstrates that vascular fibrosis is a global process associated with diseases of aging and elevated pulse pressures.

The effect of aging on deformations of the superficial femoral artery resulting from hip and knee flexion: potential clinical implications

PURPOSE

Vessel deformations have been implicated in endoluminal device fractures, and therefore better understanding of these deformations could be valuable for device regulation, evaluation, and design. The purpose of this study is to describe geometric changes of the superficial femoral artery (SFA) resulting from hip and knee flexion in older subjects.

MATERIALS AND METHODS

The SFAs of seven healthy subjects aged 50-70 years were imaged with magnetic resonance angiography with the legs straight and with hip and knee flexion. From geometric models constructed from these images, axial, twisting, and bending deformations were quantified.

RESULTS

There was greater shortening in the bottom third of the SFA than in the top two thirds (top, 5.9% +/- 3.0%; middle, 6.7% +/- 2.1%; bottom, 8.1% +/- 2.0% [mean +/- SD]; P < .05), significant twist in all sections (top, 1.3 degrees /cm +/- 0.8; middle, 1.8 degrees /cm +/- 1.1; bottom, 2.1 degrees /cm +/- 1.3), and greater curvature increase in the bottom third than in the top two thirds (top, 0.15 cm(-1) +/- 0.06; middle, 0.09 cm(-1) +/- 0.07; bottom, 0.41 cm(-1) +/- 0.22; P < .001).

CONCLUSIONS

The SFA tends to deform more in the bottom third than in the other sections, likely because of less musculoskeletal constraint distal to the adductor canal and vicinity of knee flexion. The SFAs of these older subjects curve off axis with normal joint flexion, probably resulting from known loss of arterial elasticity with age. This slackening of the vessel enables a method for noninvasive quantification of in vivo SFA strain, which may be valuable for treatment planning and device design. In addition, the spatially resolved arterial deformations quantified in this study may be useful for commercial and regulatory device evaluation.

Tissue elasticity and the ageing elastic fibre

The ability of elastic tissues to deform under physiological forces and to subsequently release stored energy to drive passive recoil is vital to the function of many dynamic tissues. Within vertebrates, elastic fibres allow arteries and lungs to expand and contract, thus controlling variations in blood pressure and returning the pulmonary system to a resting state. Elastic fibres are composite structures composed of a cross-linked elastin core and an outer layer of fibrillin microfibrils. These two components perform distinct roles; elastin stores energy and drives passive recoil, whilst fibrillin microfibrils direct elastogenesis, mediate cell signalling, maintain tissue homeostasis via TGFβ sequestration and potentially act to reinforce the elastic fibre. In many tissues reduced elasticity, as a result of compromised elastic fibre function, becomes increasingly prevalent with age and contributes significantly to the burden of human morbidity and mortality. This review considers how the unique molecular structure, tissue distribution and longevity of elastic fibres pre-disposes these abundant extracellular matrix structures to the accumulation of damage in ageing dermal, pulmonary and vascular tissues. As compromised elasticity is a common feature of ageing dynamic tissues, the development of strategies to prevent, limit or reverse this loss of function will play a key role in reducing age-related morbidity and mortality.

Medial arterial calcification in diabetes and its relationship to neuropathy

Calcification of the media of arterial walls is common in diabetes and is particularly associated with distal symmetrical neuropathy. Arterial calcification also complicates chronic kidney disease and is an independent risk factor for cardiovascular and all-cause mortality. The term calcification is not strictly accurate because the morphological changes incorporate those of new bone formation, i.e. ossification. The processes are complex, but are closely related to those involved in bone homeostasis, and it is relevant that calcification of the arterial wall and osteopenia often co-exist. One particular factor linked to the development of arterial calcification is distal symmetrical neuropathy; indeed, it has been suggested that neuropathy explains the distal distribution of arterial calcification in diabetes. It has also been suggested that the link with neuropathy results from loss of neuropeptides, such as calcitonin gene-related peptide, which are inherently protective. The association between distal symmetrical neuropathy and calcification of the arterial wall highlights the fact that neuropathy may be an independent risk factor for cardiovascular mortality.

Noninvasive assessment of arterial stiffness should discriminate between systolic and diastolic pressure ranges

Arterial stiffening plays an important role in the development of hypertension and cardiovascular diseases. The intrinsically nonlinear (ie, pressure-dependent) elastic behavior of arteries may have serious consequences for the accuracy and interpretation of arterial stiffness measurements and, ultimately, for individual patient management. We determined aortic pressure and common carotid artery diameter waveforms in 21 patients undergoing cardiac catheterization. The individual pressure-area curves were described using a dual exponential analytic model facilitating noise-free calculation of incremental pulse wave velocity. In addition, compliance coefficients were calculated separately in the diastolic and systolic pressure ranges, only using diastolic, dicrotic notch, and systolic data points, which can be determined noninvasively. Pulse wave velocity at systolic pressure exhibited a much stronger positive correlation with pulse pressure (P<0.001) and age (P=0.012) than pulse wave velocity at diastolic pressure. Patients with an elevated systolic blood pressure (>140 mm Hg) had a 2.5-times lower compliance coefficient in the systolic pressure range than patients with systolic blood pressures <140 mm Hg (P=0.002). Most importantly, some individuals, with comparable age or pulse pressure, had similar diastolic but discriminately different systolic pulse wave velocities and compliance coefficients. We conclude that noninvasive assessment of arterial stiffness could and should discriminate between systolic and diastolic pressure ranges to more precisely characterize arterial function in individual patients.

Vascular endothelial ageing, heartbeat after heartbeat

The vascular endothelium starts to age at the first heartbeat. There is no longer a need to demonstrate that an increased resting heart rate--above 70 b.p.m.--is associated with the onset of cardiovascular events and reduces lifespan in humans. Each cardiac cycle imposes a mechanical constraint on the arteries, and we would like to propose that this mechanical stress damages the vascular endothelium, its dysfunction being the prerequisite for atherogenesis. Consequently, reducing heart rate could protect the endothelium and slow the onset of atherosclerosis. The potential mechanisms by which reducing heart rate could be beneficial to the endothelium are likely a combination of a reduction in mechanical stress and tissue fatigue and a prolongation of the period of steady laminar flow, and thus sustained shear stress, between each systole. With age, irreparable damage accumulates in endothelial cells and leads to senescence, which is characterized by a pro-atherogenic phenotype. In the body, the highest mechanical stress occurs in the coronary vessels, where blood only flows during diastole and even reverses during systole; thus, coronary arteries are the prime site of atherosclerosis. All classical risk factors for cardiovascular diseases add up, to accelerate atherogenesis, but hypertension, which further raises mechanical stress, is likely the most damaging. By inducing flow through the arteries, the heart rate determines shear stress and its stability: mechanical stress and the associated damage induced by each systole are efficiently counteracted by the repair capacities of a healthy endothelium. The maintenance of a physiological, low heart rate may be key to prolonging the endothelial healthy lifespan and thus, vascular health.

Arginase inhibition restores NOS coupling and reverses endothelial dysfunction and vascular stiffness in old rats

There is increasing evidence that upregulation of arginase contributes to impaired endothelial function in aging. In this study, we demonstrate that arginase upregulation leads to endothelial nitric oxide synthase (eNOS) uncoupling and that in vivo chronic inhibition of arginase restores nitroso-redox balance, improves endothelial function, and increases vascular compliance in old rats. Arginase activity in old rats was significantly increased compared with that shown in young rats. Old rats had significantly lower nitric oxide (NO) and higher superoxide (O2(-)) production than young. Acute inhibition of both NOS, with N(G)-nitro-l-arginine methyl ester, and arginase, with 2S-amino- 6-boronohexanoic acid (ABH), significantly reduced O2(-) production in old rats but not in young. In addition, the ratio of eNOS dimer to monomer in old rats was significantly decreased compared with that shown in young rats. These results suggest that eNOS was uncoupled in old rats. Although the expression of arginase 1 and eNOS was similar in young and old rats, inducible NOS (iNOS) was significantly upregulated. Furthermore, S-nitrosylation of arginase 1 was significantly elevated in old rats. These findings support our previously published finding that iNOS nitrosylates and activates arginase 1 (Santhanam et al., Circ Res 101: 692-702, 2007). Chronic arginase inhibition in old rats preserved eNOS dimer-to-monomer ratio and significantly reduced O2(-) production and enhanced endothelial-dependent vasorelaxation to ACh. In addition, ABH significantly reduced vascular stiffness in old rats. These data indicate that iNOS-dependent S-nitrosylation of arginase 1 and the increase in arginase activity lead to eNOS uncoupling, contributing to the nitroso-redox imbalance, endothelial dysfunction, and vascular stiffness observed in vascular aging. We suggest that arginase is a viable target for therapy in age-dependent vascular stiffness.

Accelerated lung aging: a novel pathogenic mechanism of chronic obstructive pulmonary disease (COPD)

An enhanced or abnormal inflammatory response to the lungs to inhaled particles and gases, usually from cigarette smoke, is considered to be a general pathogenic mechanism in COPD (chronic obstructive pulmonary disease). Activation of leucocytes and the development of oxidant-antioxidant and protease-anti-protease imbalances are thought to be important aspects of this enhanced inflammatory response to cigarette smoke. The mechanisms involved in the perpetuation of the inflammatory response in the lungs in patients who develop COPD, even after smoking cessation, are not fully established and are key to our understanding of the pathogenic mechanisms in COPD and may be important for the development of new therapies. There is a relationship between chronic inflammatory diseases and aging, and the processes involved in aging may provide a novel mechanism in the pathogenesis of COPD. There is good evidence linking aging and COPD. During normal aging, pulmonary function deteriorates progressively and pulmonary inflammation increases, accompanied in the lungs by the features of emphysema. These features are accelerated in COPD. Emphysema is associated with markers of accelerated aging in the lungs, and COPD is also associated with features of accelerated aging in other organs, such as the cardiovascular and musculoskeletal systems. Cigarette smoke and other oxidative stresses result in cellular senescence and accelerate lung aging. There is also evidence that anti-aging molecules such as histone deacetylases and sirtuins are decreased in the lungs of COPD patients, compared with smokers without COPD, resulting in enhanced inflammation and further progression of COPD. The processes involved in accelerated aging may provide novel targets for therapy in COPD. The present article reviews the evidence for accelerated aging as a mechanism in the pathogenesis of COPD.

Open Problems in Computational Vascular Biomechanics: Hemodynamics and Arterial Wall Mechanics

The vasculature consists of a complex network of vessels ranging from large arteries to arterioles, capillaries, venules, and veins. This network is vital for the supply of oxygen and nutrients to tissues and the removal of carbon dioxide and waste products from tissues. Because of its primary role as a pressure-driven chemomechanical transport system, it should not be surprising that mechanics plays a vital role in the development and maintenance of the normal vasculature as well as in the progression and treatment of vascular disease. This review highlights some past successes of vascular biomechanics, but emphasizes the need for research that synthesizes complementary advances in molecular biology, biomechanics, medical imaging, computational methods, and computing power for purposes of increasing our understanding of vascular physiology and pathophysiology as well as improving the design of medical devices and clinical interventions, including surgical procedures. That is, computational mechanics has great promise to contribute to the continued improvement of vascular health.

Lupin protein isolate and cysteine-supplemented casein reduce calcification of atherosclerotic lesions in apoE-deficient mice

Protein from lupin is supposed to have anti-atherogenic effects due to its lipid-lowering properties in laboratory animals. It is further suggested that the amino acid cysteine plays a crucial role in this aspect. The objective of the present study was to compare the effects of lupin protein and cysteine-supplemented casein with those of casein on atherosclerotic lesion development in apoE-deficient mice. For that purpose, thirty mice were fed an egg albumin-based Western-type diet containing test protein (100 g/kg) for 4 months. ApoE-deficient mice fed the lupin protein or the cysteine-supplemented casein had more than 50 % less aortic calcification than mice fed casein (P < 0.05). The quantified lesion area as a percentage of the total surface area, as well as the collagen and fat content of the lesions were not different between the three groups of mice. The concentration of VLDL TAG was higher in mice fed the lupin protein and the cysteine-supplemented casein than in mice fed casein (P < 0.05). The cholesterol concentrations of VLDL, LDL and HDL from mice fed the lupin protein and cysteine-supplemented casein were not different compared with the mice fed casein. Also, the plasma concentrations of homocysteine, Ca, inorganic phosphate, and the activity of glutathione peroxidase in plasma and liver did not differ between the three groups of mice. The present study shows that lupin protein and cysteine-supplemented casein compared with casein reduce the calcification of atherosclerotic lesions in apoE-deficient mice. This effect seems not to be mediated by effects on plasma lipoproteins, homocysteine and circulating minerals.

Stress-induced premature senescence of endothelial cells: a perilous state between recovery and point of no return

PURPOSE OF REVIEW

To discuss most recently published studies on morphologic patterns and molecular mechanisms of stress-induced premature senescence (SIPS) of vascular endothelial cells.

RECENT FINDINGS

Lysosomal dysfunction and impaired autophagy, which have been well established in replicative senescence, were also described in SIPS induced by advanced glycation end products (AGEs). Recently, strides were made to prevent and reverse senescence. The role of lysosomal dysfunction and Lamp-2A deficiency has been demonstrated in aging. Molecular analyses identified the role of sirtuin 1 in preventing cell senescence; shed light on the role of polycomb group (PcG) protein Bmi-1 in senescence. Additionally, intriguing data on the role of caveolin-1 in cell senescence have emerged.

SUMMARY

In aging organisms and chronic diseases properly functioning tissue is replaced by senescent cells. Comparison between replicative senescence and SIPS indicates that replicative senescence is almost exclusively associated with the reduction of telomerase activity and attrition of telomeres, whereas SIPS does not require these events, thus conferring potential reversibility onto this process.

Some mechanical aspects of arterial aging: physiological overview based on pulse wave analysis

Aging has a striking impact on the arterial structure and function. The principal structural change with age is medial degeneration that leads to a progressive stiffening of the large elastic arteries. Large artery stiffening increases aortic systolic and pulse pressures through an increase in the forward incident wave and an early return of the backward reflected wave. Peripheral muscular arteries/arterioles are only minimally affected in structure by aging itself, but impaired vasomotor function can alter their impedance properties and thereby increase reflection magnitude. An augmented aortic pressure due to enhanced wave reflection increases wasted left ventricular effort and causes cardiac hypertrophy. Increased pulsatile pressure and flow stresses extend to the vulnerable microcirculation of vasodilated organs such as the brain and kidneys, and can predispose to cerebral lacunar infarction and albuminuria. Although most currently available vasodilators appear to have little direct effect on degenerated elastic arteries, they can act instead on less-degenerated muscular arteries to markedly reduce peripheral wave reflection magnitude and central aortic pressure, and thus contribute to the regression of left ventricular hypertrophy. Further studies are necessary to examine whether the effect of vasodilator therapy on reducing wave reflection contributes similarly to the prevention of microvascular damage in the brain and kidneys.

Mechanics of carotid arteries in a mouse model of Marfan Syndrome

Mouse models of Marfan Syndrome (MFS) provide insight into the type and extent of vascular abnormalities manifested in this disease. Inclusion of the mgR mutation causes the otherwise normal extracellular matrix glycoprotein fibrillin-1 to be under-expressed at 15-25% of its normal level, a condition seen in MFS. Aortas in patients with MFS are generally less distensible and may experience dissecting aneurysms that lead to premature death, yet little is known about effects on other large arteries. In this study, common carotid arteries from mice heterozygous (R/+) and homozygous (R/R) for the mgR mutation were studied under biaxial loading and compared to results from wild-type controls (+/+). Carotids from +/+ and R/+ mice exhibited similar biomechanical behaviors whereas those from R/R mice were slightly stiffer in the circumferential direction while dramatically different in the axial direction. That is, R/R carotids were stiffer axially and had lower in vivo axial prestretches. Biaxial stress-stretch data were fit with a four-fiber family constitutive model. The fitted data yielded a lower value of an isotropic parameter for the R/R carotids, which reflects a compromised elastin-dominated amorphous matrix. Overall, it appeared that changes in axial mechanical properties afforded R/R carotids a means to compensate, at least early in maturity (9 weeks of age), for the loss of an important structural constituent as they attempted to maintain structural integrity in response to normal mean arterial pressures and thereby maintain mechanical homeostasis.

Serum carboxymethyl-lysine, an advanced glycation end product, is associated with increased aortic pulse wave velocity in adults

BACKGROUND

The relationship between advanced glycation end products and arterial stiffness has previously been examined in highly selected groups of patients with diabetes or hypertension. Our aim was to determine whether elevated serum advanced glycation end products are associated with increased arterial stiffness in relatively healthy, community-dwelling adults.

METHODS

Aortic pulse wave velocity (PWV), an index of aortic stiffness, and serum advanced glycation end products (AGEs), as represented by the specific AGE, serum carboxymethyl-lysine (CML), were measured in 493 adults, aged 26-93 years, who participated in the Baltimore Longitudinal Study of Aging (BLSA).

RESULTS

Mean (s.d.) PWV (m/s) was 6.6 (1.8) m/s. Mean CML was 0.47 (0.13) microg/ml. Serum CML (per 1 s.d.) was associated with PWV (beta = 0.16, s.e. = 0.07, P = 0.02), adjusting for age, sex, body mass index, mean arterial pressure, fasting plasma glucose, high-density lipoprotein cholesterol, smoking, and other covariates. After excluding all diabetic patients, serum CML (per 1 s.d.) was associated with PWV (beta = 0.18, s.e. = 0.07, P = 0.009), adjusting for the same covariates.

CONCLUSIONS

Elevated AGEs are associated with increased arterial stiffness, a known predictor of adverse cardiovascular outcomes, among relatively healthy community-dwelling adults. Interventions to lower levels of AGEs, such as altering the pattern of dietary intake, warrant examination as putative novel strategies to lower arterial stiffness in adults.

Does senescence give rise to disease?

The distinctions between senescence and disease are blurred in the literature of evolutionary biology, biodemography, biogerontology and medicine. Theories of senescence that have emerged over the past several decades are based on the concepts that organisms are a byproduct of imperfect structural designs built with imperfect materials and maintained by imperfect processes. Senescence is a complex mixture of processes rather than a monolithic process. Senescence and disease have overlapping biological consequences. Senescence gives rise to disease, but disease does not give rise to senescence. Current data indicate that treatment of disease can delay the age of death but there are no convincing data that these interventions alter senescence. An understanding of these basic tenets suggests that there are biological limits to duration of life and the life expectancy of populations and reveal biological domains where the development of interventions and/or treatments may modulate senescence.

Assessment of carotid compliance using real time vascular ultrasound image analysis in Marfan syndrome

BACKGROUND

Fibrillin-1 deficiency, dysregulated cytokine transforming growth factor-beta, and increased collagen deposition related to fibrillin-1 gene mutations could predispose to impaired carotid compliance (CC) in Marfan syndrome (MFS). We sought to detect any alterations in CC using the vascular image analysis system (VIA).

METHODS AND RESULTS

Thirty-two MFS patients, 20 men and 12 women (mean age 34.2 +/- 12.05 years), and 29 controls matched for age, sex, and body surface area (BSA) were recruited. The entire length of each carotid system was initially scanned longitudinally using a 14 MHz linear transducer. Then, a stereotactic clamp held the transducer in contact with the carotid artery. Arterial diameter changes during the cardiac cycle were recorded for 1 minute from both right (RCCA) and left common carotid arteries (LCCA) separately using the VIA system. RCCA and LCCA compliance and distensibility measurements were significantly reduced in MFS patients when compared to controls, P < 0.05. RCCA and LCCA intima-media thickness did not differ between patients and controls, P > 0.05. MFS diagnosis and age were associated with reduced CC in both carotid arteries after adjusting for variables such as, sex, BSA, heart rate, beta-blockade, intima-media thickness, and aortic root size.

CONCLUSIONS

Our findings showed a reduction in CC in adult patients with MFS. This could be attributed to fibrillin-1 deficiency resulting in structural abnormalities in the carotid arterial wall.

Arterial calcification in race horses

Calcification of large arteries has been sporadically reported in horses. The pathogenesis is still unknown, but recent studies in humans suggest that this is a regulated biomineralizing process. This study surveyed the prevalence, distribution, and severity of vascular calcification in Thoroughbred and Standardbred racehorses. Histopathologic, ultrastructural imaging, and energy dispersive X-ray elemental analyses were used to examine the lesions. Calcification of the tunica media, predominantly the pulmonary artery, was found in 82% of horses (83/101). Young adult horses (mean [SD] age in years, 4.44 +/- 2.17) of both breeds and sexes were similarly affected. Lesions appeared as white-to-yellowish, hard, and gritty plaques of variable size. On microscopic examination, elastic fibers within the tunica media were thinned, fragmented, and calcified, and surrounded by dense collagen matrix. Elemental analysis showed distinct peaks for calcium and phosphorus, consistent with hydroxyapatite mineral. The frequent occurrence of calcification in the tunica media of large pulmonary arteries of young racing horses indicates the need to investigate its pathogenesis and potential clinical implications.

Cardiovascular aging and exercise in healthy older adults

OBJECTIVE

Physical inactivity in an aging population is a major contributing factor to the rising numbers of older persons with chronic illnesses and disabilities. The purpose of this article is to review the relationship between physical inactivity and age-associated changes to the cardiovascular system, and provide guidance on prescribing exercise to healthy older persons in order to mitigate the adverse effects of cardiovascular aging.

DESIGN

Interpretive review of the literature.

RESULTS

A number of structural and functional changes occur in the cardiovascular system with advancing age, many of which are mediated by changes in vascular stiffness. These changes lead not only to cardiovascular events and strokes, but also to frailty, functional decline, and cognitive impairment. A substantial proportion of the decline in aerobic capacity with age may result from physical inactivity. Guidelines for the prescription of aerobic, resistance, and balance training for otherwise healthy older persons are provided.

CONCLUSIONS

Lack of physical activity is a major risk factor for the epidemic of chronic disease and disability facing an aging population. Many age-associated changes in cardiovascular function result from physical inactivity. The benefits of regular exercise include prevention of cardiovascular events, disability, and cognitive impairment. Age is not a contraindication to exercise, which can usually be initiated safely in older persons.

Age-related medial elastocalcinosis in arteries: mechanisms, animal models, and physiological consequences

With age, the calcium content of the arterial wall increases. Calcification occurs at two main levels: intimal plaques and the medial elastic fiber network. The latter has been referred to as medial elastocalcinosis and is the subject of this review. The mechanisms involved in elastocalcinosis are complex and involve polar, apolar, and active processes. Vascular calcification may be species specific to humans. As laboratory animals, such as the rat, grow old, they suffer from only very mild arterial calcification. Different animal models of induction of massive arterial calcification by pharmacological and other means exist. Although extrapolation from such models to the clinical situation in terms of etiology is difficult, such models could be useful in the nonclinical study of the pathophysiological consequences of vascular calcification. Vascular calcification modifies arterial wall stiffness, and this could have clinically significant consequences on cardiac function and downstream circulatory control.

Aging and induced senescence as factors in the pathogenesis of lung emphysema

Classically, the development of emphysema in chronic obstructive pulmonary disease is believed to involve inflammation induced by cigarette smoke and leukocyte activation, including oxidant-antioxidant and protease-antiprotease imbalances. While there is substantial evidence for this, additional aspects have been suggested by a number of clinical and experimental observations. Smokers exhibit signs of premature aging, particularly obvious in the skin. The link between aging and chronic disease is well-known, e.g., for the brain and musculoskeletal or cardiovascular system, as well as the clinical link between malnutrition and emphysema, and the experimental link to caloric restriction. Interestingly, this intervention also increases lifespan, in parallel with alterations in metabolism, oxidant burden and endocrine signaling. Of special interest is the observation that, even in the absence of an inflammatory environment, lung fibroblasts from patients with emphysema show persistent alterations, possibly based on epigenetic mechanisms. The importance of these mechanisms for cellular reprogramming and response patterns, individual risk profile and therapeutic options is becoming increasingly recognized. The same applies to cellular senescence. Recent findings from patients and experimental models open novel views into the arena of gene-environment interactions, including the role of systemic alterations, cellular stress, telomeres, CDK inhibitors such as p16, p21, pRb, PI3K, mTOR, FOXO transcription factors, histone modifications, and sirtuins. This article aims to outline this emerging picture and to stimulate the identification of challenging questions. Such insights also bear implications for the long-term course of the disease in relation to existing or future therapies and the exploration of potential lung regeneration.

Arterial stiffness in diabetes and the metabolic syndrome: a pathway to cardiovascular disease

Increased arterial stiffness associated with diabetes and the metabolic syndrome may in part explain the increased cardiovascular disease risk observed in these conditions. Arterial stiffness can be estimated by quantifying pulse pressure but is better described by distensibility and compliance coefficients, pulse wave velocity and wave reflection. The most common non-invasive methodologies used to quantify these estimates of arterial stiffness (e.g. ultrasonography and applanation tonometry) are also described. We then review and summarise the current data on the associations between diabetes, the metabolic syndrome and insulin resistance on the one hand and greater arterial stiffness on the other, and identify and discuss some unresolved issues such as differential stiffening of central vs peripheral arterial segments, the impact of sex, and the pathobiology of increased arterial stiffness in diabetes and the metabolic syndrome. Finally, some considerations with regard to treatment options are presented. At present the most powerful therapy available for reducing arterial stiffness is to vigorously treat hypertension using pharmacological agents. New pharmacological strategies to reduce arterial stiffness are likely to be especially relevant to individuals with diabetes.

Involvement of advanced glycation end products in the pathogenesis of diabetic complications: the protective role of regular physical activity

Advanced glycation end products (AGEs) may play an important role in the pathogenesis of chronic diabetic complications and in the natural process of biological aging. In fact, maintained hyperglycaemia favours the formation of AGEs at the tissue level in diabetic patients, which may influence the triggering of different chronic pathologies of diabetes such as retinopathy, nephropathy, neuropathy and macro- and micro-vascular diseases. Moreover, the literature has also demonstrated the involvement of AGEs in biological aging, which may explain the accelerated process of aging in diabetic patients. The practice of regular physical activity appears to positively influence glycaemic control, particularly in type 2 diabetes mellitus patients. This occurs through the diminution of fasting glycaemia, with a consequent reduction of glycation of plasmatic components suggested by the normalisation of HbA1c plasmatic levels. This exercise-induced positive effect is evident in the blood of diabetic patients and may also reach the endothelium and connective tissues of different organs, such as the kidneys and eyes, and systems, such as the cardiovascular and nervous systems, with a local reduction of AGEs production and further deceleration of organ dysfunction. The aim of this paper was to review the literature concerning this topic to coherently describe the harmful effects of AGEs in organ dysfunction induced by diabetes in advanced age as well as the mechanisms behind the apparent protection given by the practice of regular physical activity.

Echocardiographic left ventricular hypertrophy in hypertension: marker for future events or mediator of events?

PURPOSE OF REVIEW

To discuss the most relevant studies on the prognostic impact of echocardiographic left ventricular hypertrophy in hypertension.

RECENT FINDINGS

There is abundant evidence from epidemiological studies that increased left ventricular mass identifies hypertensive patients at increased risk of major cardiac and cerebrovascular events. Looking at the geometric patterns of the left ventricle, concentric remodelling and concentric left ventricular hypertrophy carry the highest risk for adverse events. Patients with left ventricular hypertrophy reversal as an effect of treatment are exposed to a lesser risk of events as compared with patients with persistence of left ventricular hypertrophy. Reversal of concentric remodelling predicts a lesser risk of adverse events compared with persistence of remodelling. Experimental evidence is accumulating that several haemodynamic and nonhaemodynamic factors which are able to promote progression of atherosclerosis through plaque growth and destabilization may also induce left ventricular hypertrophy by acting on myocyte and interstitium. Increased left ventricular mass may also be a causative factor for reduced pumping performance and arrhythmias.

SUMMARY

Increased left ventricular mass is a marker of cardiovascular risk because it reflects and integrates the long-term level of activity of factors inducing progression of atherosclerosis. Increased left ventricular mass may also mediate myocardial ischaemia with potential evolution towards heart failure and arrhythmias.

Renal ageing

The function of the kidney, as well as its morphology, changes markedly with age. The glomerular filtration rate falls progressively, independent of overt pathology. Glomerular, vascular and accompanying parenchymal changes occur and other disorders associated with ageing, such as diabetes and hypertension, have a stochastic deleterious effect on both form and function. Declining renal function with age has important implications, not only for individual homeostasis but also for the use of drug therapy and for the receipt and donation of organs for transplantation. Molecular mechanisms and cellular changes underlying some of the functional and structural changes associated with ageing are becoming clearer, as are some of the ways in which genetic background, age and disease can combine to produce functional damage.

The pathology of ageing: concepts and mechanisms

The rising numbers and proportion of aged individuals in the population is a global demographic trend. The diseases associated with ageing are becoming more prevalent, and the associated healthcare costs are having a significant economic impact in all countries. With these changes have come great advances in our understanding of the mechanisms of ageing. The mechanisms of cellular ageing at a genetic, protein and organelle level are becoming clearer, as are some of the more complex associations between environment and ageing. System ageing is also becoming better understood, and the potential biological advantages of ageing are being explored. Many of the advances in these fields are opening up the prospect of targeted therapeutic intervention for ageing and age related disease.