Hypothesis: pulse pressure and human longevity

The biological age model for evaluating the degree of aging in centenarians

BACKGROUND

Biological age (BA) has been used to assess individuals' aging conditions. However, few studies have evaluated BA models' applicability in centenarians.

METHODS

Important organ function examinations were performed in 1798 cases of the longevity population (80∼115 years old) in Hainan, China. Eighty indicators were selected that responded to nutritional status, cardiovascular function, liver and kidney function, bone metabolic function, endocrine system, hematological system, and immune system. BA models were constructed using multiple linear regression (MLR), principal component analysis (PCA), Klemera and Doubal method (KDM), random forest (RF), support vector machine (SVM), extreme gradient boosting (XGBoost), and light gradient boosting machine (lightGBM) methods. A tenfold crossover validated the efficacy of models.

RESULTS

A total of 1398 participants were enrolled, of whom centenarians accounted for 49.21%. Seven aging markers were obtained, including estimated glomerular filtration rate, albumin, pulse pressure, calf circumference, body surface area, fructosamine, and complement 4. Eight BA models were successfully constructed, namely MLR, PCA, KDM1, KDM2, RF, SVM, XGBoost and lightGBM, which had the worst R2 of 0.45 and the best R2 of 0.92. The best R2 for cross-validation was KDM2 (0.89), followed by PCA (0.62).

CONCLUSION

In this study, we successfully applied eight methods, including traditional methods and machine learning, to construct models of biological age, and the performance varied among the models.

Antihypertensive therapy prevents new-onset atrial fibrillation in patients with isolated systolic hypertension: the LIFE study

Aims: Atrial fibrillation (AF) is associated with increased cardiovascular risk and the incidence increases with age, hypertension and left ventricular hypertrophy (LVH). Reducing in-treatment systolic blood pressure (SBP) prevents new-onset AF but has previously not been studied in patients with isolated systolic hypertension (ISH). We aimed to investigate the effect on preventing new-onset AF by decreased in-treatment SBP in patients with ISH compared to patients with non-ISH. Methods and results: Double-blind, randomized, parallel-group study of 1320 patients with ISH and electrocardiographic (ECG) LVH, included among the 9193 patients in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study. Annual ECGs were Minnesota coded centrally, and new-onset AF was evaluated in 1248 ISH patients and compared with 7583 non-ISH patients during mean 4.8 ± 0.9 years follow-up. Cox regression analyses were used to assess the effect of reduced in-treatment SBP. New-onset AF occurred in 61 (4.9%) ISH patients and 292 (3.9%) non-ISH patients. In multivariate analysis lower in-treatment SBP was associated with 17% risk reduction (p = 0.008) for new-onset AF in ISH patients and 9% risk reduction (p = 0.006) in non-ISH patients per 10 mmHg decrease in in-treatment SBP, independent of treatment modality, baseline risk factors, baseline SBP and in-treatment heart rate and ECG-LVH. There was a significant interaction (p = 0.041) in favor of SBP reduction and AF prevention in ISH vs. non-ISH patients. Conclusion: Our data suggest that the effect of in-treatment SBP reduction in preventing new-onset AF is stronger in ISH compared to non-ISH patients with hypertension and ECG-LVH. However, the principal findings were the same in ISH and non-ISH patients.

Rationale, design, methods and baseline characteristics of the Asklepios Study

The Asklepios Study is a longitudinal population study focusing on the interplay between ageing, cardiovascular haemodynamics and inflammation in (preclinical) cardiovascular disease. The 2524 participants (1301 women) are a representative cohort of 35-55-year-old individuals, free from overt cardiovascular disease at study initiation, randomly sampled from the twinned Belgian communities of Erpe-Mere and Nieuwerkerken. Baseline examinations (all single-observer, single-device, single-site, single 2-year consecutive timeframe) include: questionnaires, conventional risk factors and biochemistry. Additional phenotypes under study include: (a) vascular structure and function: carotid and femoral atherosclerosis (intima-media thickness, plaque), arterial distension and pressure curves (brachial, carotid, femoral; wall-tracking and applanation tonometry); (b) cardiac structure and function. A novel aspect of the study is 'integrated' non-invasive biomechanical assessment of cardiac, arterial and ventriculovascular function through a combination of modeling, fundamental hydraulical measurements and system identification techniques. Integrated phenotypes result from combining at least two sets of curves (flow/pressure/distension). The value of this 'integrated' haemodynamic phenotype in the detection, prediction and prevention of clinical cardiovascular pathology (atherosclerosis progression, atherothrombosis, development of heart failure) will be tested. A second novel aspect is the systematic determination of peripheral blood leukocyte telomere length as a marker for biological ageing. During follow-up, baseline examinations will be repeated and the incidence of cardiovascular events will be monitored. Sex-specific baseline risk factor and biochemical data are provided in the current analyses. The primary aim is to build a combined dataset that will act as a tool to answer a cluster of questions about ageing, haemodynamics and the emergence of cardiovascular disease, especially the incidence of atherothrombotic events and the development of adverse haemodynamic profiles (arterial stiffening, heart failure). The study will reassess current risk factors and provide a long-term base for the detection of novel (epi)genetic and non-genetic risk factors and for more performant risk stratification modalities. Within these broader goals, a constant will be to strive towards more fundamental mechanistic-haemodynamic insights into cardiovascular disease processes.

The age-related hemodynamic changes of blood pressure and their impact on the incidence of cardiovascular disease and stroke: new evidence

There is a linear change in blood pressure (BP) with the advancement of age from predominantly diastolic BP (DBP) in the young to predominantly systolic BP (SBP) in the old. This change is caused by the stiffening of the large arteries and the loss of elastic recoil as a result of replacement of the elastic fibers with collagen fibers. The result of this ageing process leads to an increase in pulse wave velocity and widening of pulse pressure. These hemodynamic changes are associated with an increased incidence in cardiovascular diseases (CVDs) and strokes. Recently, an inverse relationship with stroke risk was noted when the DBP was <71 mm Hg in persons older than 60 years. Accordingly, when treating SBP in the elderly, care should be taken not to lower the DBP below this level in order to minimize the risk for CVD and stoke.

The correlation between peripheral leukocyte telomere length and indicators of cardiovascular aging

OBJECTIVES

To investigate the relationship between telomere length in peripheral blood white cells and cardiovascular function in a healthy, aging Han Chinese population.

METHODS

In 2012, peripheral blood leukocytes were obtained from 139 healthy individuals in Beijing, China, and telomere restriction fragment (TRF) length was assayed using a digoxigenin-labeled hybridization probe in Southern blot assays. Indicators of cardiovascular function were also evaluated, including electrocardiograms (ECG), (RR, P, PR, QRS, ST and T intervals); blood pressure (BP), (SBP, DBP, PP, PPI); cardiovascular ultrasound (left ventricular ejection fraction, LVEF); mitral early and late diastolic peak flow velocity (MVE and MVA); and lipid indices (TC, TG, HDL, LDL, LCI). The relationships of these cardiovascular indictors to telomere length were evaluated.

RESULTS

No correlations were found between telomere length and ECG, BP or lipid indices even after adjustment for age. Correlations were found between TFR length and some cardiovascular ultrasound indictors (D, MVEA, MVEDT, MVES, MVEL, MVEI, IMT), but these were not seen after adjusting for age.

CONCLUSIONS

We did not find that leukocyte TFR length was associated with cardiovascular ultrasound indictors, ECG, BP, or lipid indices in this population of healthy Han Chinese individuals. Telomere length may serve as a genetic factor in biological aging.

Fetal origin of vascular aging

Aging is increasingly regarded as an independent risk factor for development of cardiovascular diseases such as atherosclerosis and hypertension and their complications (e.g. MI and Stroke). It is well known that vascular disease evolve over decades with progressive accumulation of cellular and extracellular materials and many inflammatory processes. Metabolic syndrome, obesity and diabetes are conventionally recognized as risk factors for development of coronary vascular disease (CVD). These conditions are known to accelerate ageing process in general and vascular ageing in particular. Adverse events during intrauterine life may programme organ growth and favour disease later in life, popularly known as, 'Barker's Hypothesis'. The notion of fetal programming implies that during critical periods of prenatal growth, changes in the hormonal and nutritional milieu of the conceptus may alter the full expression of the fetal genome, leading to permanent effects on a range of physiological.

Early vascular phenotypes in the genesis of hypertension

Cardiovascular complications occurring in adults find their roots in risk factors operating early in life. Among the factors influencing cardiovascular risk, blood pressure values in children represent an important measurable marker of the level of potential cardiovascular risk later in life because the levels are both the cause and the consequence of early vascular alterations. Early vascular phenotypes represent a field of great interest, and they can be studied through indirect assessment using non-invasive techniques. Estimations of blood pressure components, pulse wave velocity, and reflecting waves provide valuable information that can be easily recorded and repeated overtime. A direct assessment, carried out by examining the umbilical vessels, can add further valuable information. In this review, we discuss the potential application of surrogate markers of early vascular alterations and describe the information provided by umbilical cord vessels.

"Predicting" parental longevity from offspring endophenotypes: data from the Long Life Family Study (LLFS)

While there is evidence that longevity runs in families, the study of long-lived families is complicated by the fact that longevity-related information is available only for the oldest old, many of whom may be deceased and unavailable for testing, and information on other living family members, primarily descendents, is censored. This situation requires a creative approach for analyzing determinants of longevity in families. There are likely biomarkers that predict an individual's longevity, suggesting the possibility that those biomarkers which are heritable may constitute valuable endophenotypes for exceptional survival. These endophenotypes could be studied in families to identify human longevity genes and elucidate possible mechanisms of their influence on longevity. In this paper, we analyze data collected in the Long Life Family Study (LLFS) investigating whether indicators of physiological state, cognitive functioning and health/well-being among offspring predict longevity in parents. Good predictors can be used as endophenotypes for exceptional survival. Our analyses revealed significant associations between cumulative indices describing physiological state, as well as a number of offspring phenotypes, and parental lifespan, supporting both their familial basis and relevance to longevity. We conclude that the study of endophenotypes within families is a valid approach to the genetics of human longevity.

Effect of intrauterine fetal programming on response to postnatal shaker stress in endothelial nitric oxide knockout mouse model

OBJECTIVE

To determine whether the intrauterine environment affects the postnatal vascular response to stress in a model of fetal programming induced by endothelial nitric oxide synthase deficiency.

STUDY DESIGN

Homozygous nitric oxide synthase knockout and wild-type controls were crossbred to obtain maternally and paternally derived heterozygous offspring. At 14 weeks of age, in vivo blood pressure measurements by telemetry, and in vitro carotid arteries vascular reactivity studies were performed in male offspring after subjecting them to shaker stress.

RESULTS

Maternally derived heterozygous offspring, compared with paternally derived heterozygous offspring, had significantly higher systolic blood pressure, mean arterial blood pressure, and pulse pressure before, as well as after introduction of the shaker stress. The difference in the latter between maternally and paternally derived heterozygous offspring was accentuated after stress. Maternally derived heterozygous offspring also had significantly higher contractile responses to phenylephrine when compared with paternally derived heterozygous offspring, and this was abolished after incubation with L-NAME.

CONCLUSION

The adverse uterine environment affects the postnatal vascular response to stress.

Hypertension in the elderly and the very old

High systolic blood pressure represents a challenge for the modern world. Epidemiologists are in the best position to appreciate the importance of systolic hypertension and its cardiovascular consequences. Although the label of hypertension seems to have lower importance in the elderly, and above all in the very old, than in younger people, high systolic and high pulse pressure are risk factors for cardiovascular events and necessitates treatment. Unfortunately, due to indolence and lack of aggressiveness, only a limited fraction of elderly hypertensive patients receives adequate therapy.

Inflammation, aging, and cancer: tumoricidal versus tumorigenesis of immunity: a common denominator mapping chronic diseases

Acute inflammation is a highly regulated defense mechanism of immune system possessing two well-balanced and biologically opposing arms termed apoptosis ('Yin') and wound healing ('Yang') processes. Unresolved or chronic inflammation (oxidative stress) is perhaps the loss of balance between 'Yin' and 'Yang' that would induce co-expression of exaggerated or 'mismatched' apoptotic and wound healing factors in the microenvironment of tissues ('immune meltdown'). Unresolved inflammation could initiate the genesis of many age-associated chronic illnesses such as autoimmune and neurodegenerative diseases or tumors/cancers. In this perspective 'birds' eye' view of major interrelated co-morbidity risk factors that participate in biological shifts of growth-arresting ('tumoricidal') or growth-promoting ('tumorigenic') properties of immune cells and the genesis of chronic inflammatory diseases and cancer will be discussed. Persistent inflammation is perhaps a common denominator in the genesis of nearly all age-associated health problems or cancer. Future challenging opportunities for diagnosis, prevention, and/or therapy of chronic illnesses will require an integrated understanding and identification of developmental phases of inflammation-induced immune dysfunction and age-associated hormonal and physiological readjustments of organ systems. Designing suitable cohort studies to establish the oxido-redox status of adults may prove to be an effective strategy in assessing individual's health toward developing personal medicine for healthy aging.

Is schizophrenia a syndrome of accelerated aging?

Schizophrenia is associated with a number of anatomical and physiological abnormalities outside of the brain, as well as with a decrease in average life span estimated at 20% in the United States. Some studies suggest that this increased mortality is not entirely due to associated causes such as suicide and the use of psychotropic medications. In this article, in order to focus greater attention on the increased mortality associated with schizophrenia, we present a special case of the hypothesis that physiological abnormalities associated with schizophrenia make a contribution to the increased mortality of schizophrenia: specifically, the hypothesis that schizophrenia is a syndrome of accelerated aging. Evidence consistent with this hypothesis comes from several areas. The biological plausibility of the hypothesis is supported by the existence of established syndromes of accelerated aging and by the sharing of risk factors between schizophrenia and other age-related conditions. We propose methods for testing the hypothesis.

Transgenerational effect of fetal programming on vascular phenotype and reactivity in endothelial nitric oxide synthase knockout mouse model

OBJECTIVE

The objective of the study was to investigate the transgenerational effect of fetal vascular programming

STUDY DESIGN

Homozygous NOS3 knockout and wild type controls (NOS3+/+WT) were cross-bred to obtain heterozygous offspring that developed in (KO-/-) mothers lacking a functional NOS3 (KOM) vs wild-type control mothers (KOP). The first-generation KOM(+/-) and KOP(+/-) female mice were then bred with WT(+/+) males to obtain a second generation (F2). F2 offspring were genotyped and WT(+/+)-F2 mice were then used for in vivo blood pressure and in vitro vascular reactivity studies.

RESULTS

WT-F2 mice born to KOM mothers (KOM-F2WT) had significantly higher systolic blood pressure, mean arterial pressure, and pulse pressure, compared with WT-F2 born to KOP mothers. Male KOM-F2WT offspring had significantly increased response to phenylephrine (PE), compared with male KOP-F2WT. Male offspring had increased contractile responses to PE when compared with female. Acetylcholine responses were decreased in female KOM-F2WT, compared with female KOP-F2WT, but the difference was not statistically significant

CONCLUSION

Our findings support a transgenerational effect of fetal programming on the vascular phenotype and suggest possible gender specific adaptation.

Effect of losartan, compared with atenolol, on endothelial function and oxidative stress in patients with type 2 diabetes and hypertension

OBJECTIVE

It has been shown that angiotensin-converting enzyme inhibition or angiotensin receptor blockade may improve endothelial dysfunction, an early manifestation of atherosclerosis, in patients with diabetes. Whether this protective effect is mediated through blood pressure-lowering effects or other specific mechanisms such as a reduction in oxidative stress is not clear. We investigated the influence of losartan, compared with atenolol, on endothelial function and oxidative stress in patients with type 2 diabetes and hypertension.

METHODS

Thirteen patients were included in this randomized, double-blind, crossover study; they received losartan 50 mg twice daily for 4 weeks followed by atenolol 50 mg twice daily or vice versa. Concomitant medication with renin-angiotensin blocking agents or beta-blockers was withdrawn, whereas other medication remained unchanged. At baseline and after each treatment period, flow-mediated dilation of the brachial artery and oxidative stress were measured in serum samples.

RESULTS

Flow-mediated dilation was increased significantly after 4 weeks' treatment with losartan (3.4 +/- 0.44%) compared with atenolol (2.58 +/- 0.42%; P = 0.01). 8-Isoprostanes, a marker of oxidative stress, were significantly reduced in the losartan group compared with baseline (0.039 +/- 0.007 versus 0.067 +/- 0.006 ng/ml; P = 0.01), but did not differ from baseline with atenolol. Glucose, hemoglobin A1c, highly sensitive C-reactive protein, lipids and systolic blood pressure remained unaltered, whereas diastolic blood pressure tended to be lower in the atenolol group.

CONCLUSIONS

This study demonstrates that losartan significantly improved endothelial function in type 2 diabetes patients with hypertension compared with atenolol. This must be independent of the blood pressure-lowering effect of losartan and is probably caused by an antioxidative effect of the angiotensin receptor blocker.

Variation of skeletal biomarkers of biological aging in a Chuvashian population: a longitudinal study

Osseographic score (OSS) is a skeletal biomarker of biological aging, based on assessment of the hand's radiographic features. The aims of the present cross-sectional and follow-up study were: 1) to evaluate age-related changes of OSS in a large Chuvashian cohort, and 2) to evaluate sex differences in age-related changes of OSS. This study reports on intersexual differences in the pattern of skeletal aging. The most prominent difference was in the rate of skeletal change, measured as average OSS difference per year. However, no differences were found in the age at which the first skeletal change occurred. The mean values of OSS were higher in males than in females in decades 3-5 of life, but afterwards they reversed. In a follow-up study, we found that sex differences regarding the rate of OSS change began in the fifth decade, but became statistically significant only in the sixth and seventh decades. Thereafter, the rate of OSS change again became virtually equal between sexes.

Pulse pressure and mortality from cerebrovascular diseases in type 2 diabetic patients: the Verona Diabetes Study

BACKGROUND/OBJECTIVE

Previous studies conducted both in the general and diabetic population have shown that pulse pressure (PP) can predict mortality from cardiovascular diseases. The aim of the present study was to investigate the relationship between PP and specific cardiovascular mortality, i.e. from cerebrovascular and ischemic heart diseases, in a well-characterized cohort of type 2 diabetic patients.

METHODS

A cohort of 1,128 known type 2 diabetic patients 56 to 74 years of age with at least 2 blood pressure measurements for each year between 1984-1986 was followed-up for ten years to assess specific causes of death. The analyses were carried out by using the mean and the coefficient of variation (CV) of PP.

RESULTS

By the end of the 10-year follow-up period, 375 patients (178 male, 197 female) had died (33%). The mean PP resulted as an independent predictor of all causes and cardiovascular mortality. Remarkably, the mean PP, but not the CV of PP, was highly predictive of mortality from cerebrovascular diseases. The risk of cerebrovascular mortality rose by 86% with a 10 mm Hg increase in mean PP. PP turned out to be the most important predictor of cerebrovascular mortality among various pressure indexes (mean, systolic and diastolic pressure).

CONCLUSION

The mean pulse pressure, but not the coefficient of variation is a strong predictor of cardiovascular mortality, mainly from cerebrovascular diseases, in type 2 diabetic patients.

Hypertension artérielle chez la femme ménopausée

Menopause coincides with an increase in the incidence of hypertension in women. A direct role of estrogen deprivation in this increased blood pressure remains a topic of debate. Menopause probably accelerates the arterial changes related to aging. Hormone replacement therapy does not influence blood pressure significantly and is not contraindicated in hypertensive women. The effect of hormone replacement treatment on cardiovascular risk was recently the object of controversy. It does not increase risk except in cases of late treatment in older women who already have atherosclerosis. Hypertension management in women is otherwise similar to management in men.

Can we improve cardiovascular risk prediction beyond risk equations in the physician's office?

BACKGROUND AND OBJECTIVES

Beyond a global estimation of the cardiovascular risk through the assessment of major risk factors and their integration in dedicated risk scales or equations, the use of specific markers provides additive prognostic information at an individual level, including predisposing factors, which are not included in the risk equations as well as the individual susceptibility to their long-term exposure. However, the majority of these markers require specific devices and skills, which are not widely available in primary care.

METHODS

Some clinical and/or "low-cost" parameters are shown to be valuable risk markers, and their use could refine the risk estimation in a physician's office. Several epidemiologic studies suggest the heart rate, the pulse pressure and the ankle-brachial index are effective cardiovascular risk markers. The arms systolic pressure asymmetry could also be a useful marker of risk.

RESULTS AND CONCLUSIONS

Through a general review, the authors evaluate the potential of these clinical markers, including their use in combination for more accurate risk determination.

Essential hypertension seems to result from melatonin-induced epigenetic modifications in area postrema

Essential hypertension is a complex multifactorial disorder with epigenetic and environmental factors contributing to its prevalence. Epigenetic system is a genetic regulatory mechanism that allows humans to maintain extraordinarily stable patterns of gene expression over many generations. Sympathetic nervous system plays a major role in the maintenance of hypertension and the rostral ventrolateral medulla is the main source of this sympathetic activation. A possible mechanism to explain the sympathetic hyperactivity in the rostral ventrolateral medulla is an action of the area postrema. Area postrema seems to be the region where a shift of the set-point to a higher operating pressure occurs resulting in hypertension. But, how can a shift occur in the area postrema. We propose that melatonin-induced epigenetic modifications in the neurons of area postrema plays a role in this shift. Area postrema is reported to contain high levels of melatonin receptors that play a role in the epigenetic modifications in certain cells. Environmental stressors cause epigenetic modifications in the neurons of area postrema via the pineal hormone melatonin and these changes lead to a shift in the set-point to a higher operating pressure. This signal is then sent via efferent projections to key medullary sympathetic nuclei in rostral ventrolateral medulla resulting in increases in sympathetic nerve activity. This model may explain the long-term alterations in sympathetic activity in essential hypertension.

A forkhead in the road to longevity: the molecular basis of lifespan becomes clearer

OBJECTIVE

Although the quest for longevity is as old as civilization itself, only recently have technical and conceptual advances in genomics research brought us to the point of understanding the precise molecular events that make us age. This heralds an era when manipulations of these will enable us to live longer, healthier lives. The present review describes how recent experimental strategies have identified key genes and intracellular pathways that are responsible for ageing and longevity.

FINDINGS

In diverse species transcription factors belonging to the forkhead/winged helix box gene, group O (FOXO) subfamily have been found to be crucial in downstream suppression of the life-shortening effects of insulin/insulin-like growth factor-I receptor signalling pathways that, when upregulated, accelerate ageing by suppression of FOXO. The various adverse processes activated upon FOXO suppression include increased generation of reactive oxygen species (ROS). ROS are pivotal for the onset of various common conditions, including hypertension, atherosclerosis, type 2 diabetes, cancer and Alzheimer's disease, each of which shortens lifespan. In humans, FOXO3a, as well as FOXO1 and -4, and their downstream effectors, could hold the key to counteracting ageing and common diseases. An understanding of the processes controlled by these FOXOs should permit development of novel classes of agents that will more directly counteract or prevent the damage associated with diverse life-threatening conditions, and so foster a life of good health to a ripe old age. Just like caloric restriction, lifespan can be increased in various species by plant-derived polyphenols, such as resveratrol, via activation of sirtuins in cells. Sirtuins, such as SIRT1 in mammals, utilize FOXO and other pathways to achieve their beneficial effects on health and lifespan.

CONCLUSION

Lifespan is tractable and basic mechanisms are now known. Longevity research complements and overlaps research in most major medical disciplines. Current progress bodes well for an ever-increasing length of healthy life for those who adapt emerging knowledge personally (so-called 'longevitarians').

Developmental determinants of blood pressure in adults

Over the past 20 years a large and varied body of research has attempted to make the case for the developmental origins of elevated adult blood pressure (BP). Experimental animal research has identified plausible biological mechanisms through which fetal nutritional insufficiency may affect adult BP. The majority of human epidemiologic studies demonstrate an inverse association of birth weight (the most commonly used marker of fetal nutrition) with adult BP and higher risk of hypertension among individuals with lower weight at birth. The most adverse BP outcomes occur among individuals who were small at birth but relatively large as adults, a finding that suggests a role for postnatal growth. We critically review the literature on proposed mechanisms and epidemiologic evidence for developmental origins of adult BP and hypertension, considering associations with birth weight, maternal nutrition during pregnancy, child growth patterns, and infant feeding.

Disentangling the genetic determinants of human aging: biological age as an alternative to the use of survival measures

The choice of a phenotype is critical for the study of a complex genetically regulated process, such as aging. To date, most of the twin and family studies have focused on broad survival measures, primarily age at death or exceptional longevity. However, on the basis of recent studies of twins and families, biological age has also been shown to have a strong genetic component, with heritability estimates ranging from 27% to 57%. The aim of this review is twofold: first, to summarize growing consensus on reliable methods of biological age assessment, and second, to demonstrate validity of this phenotype for research in the genetics of aging in humans.

Systolic and pulse hypertension

Epidemiology, genetic analysis and clinical studies are of help in understanding how, to what extent and why systolic blood pressure increases with age (at least in Western societies), while diastolic blood pressure increases only until the age of 60–65 years. Systolic blood pressure is a predictor of outcome in humans, but pulse pressure (systolic minus diastolic) is a better predictor, particularly in the elderly. Although the cardiovascular risk pattern is different in older patients, antihypertensive treatment remains useful in the elderly and even in the very old. Nevertheless, excessive reduction of diastolic blood pressure should be avoided in order to prevent increasing pulse pressure. Although all therapeutic regimens tend to reduce systolic more than diastolic blood pressure (reducing pulse pressure), the need for antihypertensive drugs acting selectively on systolic values remains very strong.

Prevalence, pathophysiology and treatment of isolated systolic hypertension in the elderly

Isolated systolic hypertension is the predominant type of hypertension in the elderly and is associated with cardiovascular complications such as stroke, coronary heart disease and heart failure. In this review, the role of arterial stiffness, endothelial function, atherosclerosis and oxidative stress in the pathogenesis of isolated systolic hypertension is extensively discussed. Placebo-controlled intervention trials such as the Systolic Hypertension in Europe Trial and the Systolic Hypertension in the Elderly Program have clearly shown that pharmacological treatment of isolated systolic hypertension improves outcome in the elderly. Nevertheless, isolated systolic hypertension remains the major subtype of untreated and uncontrolled hypertension.

The impact of birth weight on pulse pressure during adolescence

BACKGROUND

The objective was to study the influence of birth weight on office and ambulatory pulse pressure.

METHODS AND RESULTS

Three hundred healthy children (176 girls), aged 10-18 years, born at term after a normotensive pregnancy were included. The subjects were divided according to birth weight: 2.000-2.500 kg, 2.501-3.000 kg, 3.001-3.500 kg and >3.500 kg. For each subject, office and 24-h ambulatory blood pressure monitoring were performed according to the protocol designed. There were significant differences among groups in 24-h ambulatory systolic blood pressure, and pulse pressure (PP). No differences were observed in terms of sex, current age, weight and height. Using a multiple linear regression analysis, sex, but not birth weight was the only independent factor related to office PP after controlling for current age, weight and height. Twenty-four hour pulse pressure was significantly related not only to current weight but also inversely to birth weight after controlling for sex, current age, and height.

CONCLUSIONS

The results disclose a relationship between birth weight and ambulatory pulse pressure while seeking to advance knowledge about the possible associations between birth weight and cardiovascular risk.

EFFECT OF MAGNESIUM ON MECHANICAL PROPERTIES OF PRESSURIZED MESENTERIC SMALL ARTERIES FROM OLD AND ADULT RATS

The purpose of the present study was to determine the effects of magnesium (Mg) on the mechanical properties of resistance arteries in adult and old rats. Studies were performed in adult (17 weeks) and old (104 weeks) male Wistar rats. The vasodilatory response and the passive mechanical properties of the wall of isolated perfused and pressurized arterial segments of mesenteric small arteries were investigated after Mg and verapamil application, both known for their calcium antagonistic properties. Mesenteric resistance arteries from old rats exhibited an outward hypertrophic remodelling, with enlargment of the lumen, thickening of the media and enlarged media cross-sectional area. The vasodilatory response induced by the application of increasing extracellular concentrations of Mg and verapamil was significantly smaller in preconstricted mesenteric arteries of old rats than in those of adult rats. Incremental distensibility in response to increasing intravascular pressures did not change. However, the stress-strain curve was shifted to the left in pressurized mesenteric arteries from old rats, indicating arterial wall stiffness. Verapamil (3 micro mol/L) did not modify the stress-strain curves in either adult or aged rats. However, Mg (4.8 mmol/L) significantly shifted the curve to the right in mesenteric arteries from adult rats and, to a greater degree, in those from old rats. Although Mg-induced vasodilatation is impaired in aged rats, increased Mg concentration improved the mechanics of pressurized mesenteric resistance arteries. The fact that Mg decreases arterial stiffness in arteries from old rats suggests that Mg has a beneficial effect on age-related changes to the vascular wall.

Effect of age on mechanical properties of rat mesenteric small arteries

With aging, large arteries become stiffer and systolic blood pressure consequently increases. Less is known, however, about the age-related change in mechanics of small resistance arteries. The aim of this study was to determine whether aging plays a role in the stiffening of the small mesenteric arteries of rats. Intra-arterial systolic, diastolic, mean and pulse pressures were measured in male Wistar rats aged 2, 4, 15 and 26 months. The passive mechanical properties of the wall of isolated perfused and pressurized arterial segments of mesenteric small arteries were also investigated. Intra-arterial systolic, diastolic and mean blood pressures tended to decrease with age and were significantly lower in the oldest rats (26-month-old group). Pulse pressure was significantly higher in the 15- and 26-month-old groups than in the two younger groups. Under isobaric conditions, increasing age is associated with an outward hypertrophic remodeling of the mesenteric arteries. Under relaxed conditions, incremental distensibility in response to increasing intravascular pressure did not change with aging. As a function of strain (under isometric conditions), stress shifted to the left as age increased, indicating an age-related vascular stiffening. Under isobaric conditions or in relation to wall stress, the elastic modulus was greater in the adult 15-month-old rats than in the younger rats. These findings suggest that distensibility seems to be preserved with aging, despite stiffness of the wall components, probably by arterial wall geometric adaptation, which limits the pulse pressure damage. It is interesting to note that elastic modulus in mesenteric arteries from the oldest rats (26-month-old), examined in relation to wall stress and intravascular pressure, did not differ from that of the youngest rats, thus suggesting that elasticity of wall components had been restored.Key words: age, arteries, elastic modulus, stiffness, pressure.

What is the most important component of blood pressure: systolic, diastolic or pulse pressure?

PURPOSE OF REVIEW

Diastolic blood pressure has traditionally been considered the most important component of blood pressure and the primary target of antihypertensive therapy. However, over 30 years ago important epidemiological studies pointed out the importance of systolic blood pressure, and research during the 1990s has strengthened this view. Unlike diastolic blood pressure, systolic blood pressure increases progressively with age, and in the ageing societies elevated systolic pressure is the most common form of hypertension. The characteristic changes of systolic and diastolic blood pressure with age lead to increases in pulse pressure (systolic minus diastolic), which has emerged as a new, potentially independent risk factor. In this review we compare the relative importance of various blood pressure components.

RECENT FINDINGS

Generally, in studies in which readings of systolic and diastolic blood pressure have been compared, systolic blood pressure has been a better predictor of risk. Moreover, isolated systolic hypertension predicts risk better than isolated diastolic hypertension, and the treatment of both isolated systolic hypertension and combined hypertension has reduced cardiovascular events. There are no treatment studies of isolated diastolic hypertension. Pulse pressure reflects stiffening of large arteries and is associated with several cardiovascular risk factors. Pulse pressure also predicts events in epidemiologic studies, but elucidation of an independent role is hampered by the close correlation between pulse pressure and systolic blood pressure.

SUMMARY

Epidemiological and treatment studies suggest that systolic blood pressure should be the primary target of antihypertensive therapy, although consideration of systolic and diastolic pressure together improves risk prediction. The greatest practical concern at the moment is the undertreatment of hypertension, especially systolic, and total cardiovascular risk.

Genetic determination of biological age in the Mennonites of the Midwestern United States

Numerous studies have shown that longevity is moderately heritable in human populations. Longevity, however, contains limited information on functional status, since individuals may exhibit differential survival patterns. In this study, we employed a stepwise multiple regression approach to estimate biological aging in a Mennonite population, using chronological age as a dependent variable and various predictors of chronological age including subphenotypes related to diabetes, coronary heart disease, hypertension, renal function, and markers of functional ability. The residual (the difference between chronological and predicted ages) is considered a marker of biological age. In fact, two different data sets were used to obtain residuals due to the availability of data. In each analysis, chronological age was regressed on predictor variables in a stepwise manner, retaining the variables significant at the 5% level. The first analysis (N=729) included 6 significant predictors (R(2)=44.3%): glucose, blood urea nitrogen (BUN), cholesterol, albumin, systolic blood pressure (SBP), and ln potassium, and the second analysis (N=232) included 9 significant predictors (R(2)=71.5%): BUN, albumin, SBP, low-density lipoprotein cholesterol, forced expiratory volume in 1 sec (FEV1), grip strength, trunk flexibility, reaction time, and FEV1xsex. Using a variance components approach, we found that the data set-specific residuals were significantly heritable (h(2)+/-SE): first analysis=0.265+/-0.106, and second analysis=0.469+/-0.180. The residuals from the second data set appear to be more informative for biological aging, perhaps due to the inclusion of functional ability-related phenotypes in addition to the blood chemistry variables. In summary, we have shown that markers of biological aging in Mennonites are under substantial additive genetic influences.