Association of low total testosterone levels and prevalent carotid plaques: result of the study of health in Pomerania

Genome-wide identification and expression analysis of the CLC superfamily genes in tea plants (Camellia sinensis)

The voltage-gated chloride channel (CLC) superfamily is one of the most important anion channels that is widely distributed in bacteria and plants. CLC is involved in transporting various anions such as chloride (Cl^-) and fluoride (F^-) in and out of cells. Although Camellia sinensis is a hyper-accumulated F plant, there is no studies on the CLC gene superfamily in the tea plant. Here, 8 CLC genes were identified from C. sinensis and they were named CsCLC1-8. The structure of CsCLC genes and the proteins were not conserved; the number of exons varied from 3 to 24, and the number of transmembrane domains contained 2 to 10. Furthermore, phylogenetic analysis revealed that CsCLC4-8 in subclass I contained the typical conserved domains GxGIPE (I), GKxGPxxH (II) and PxxGxLF (III), and CsCLC1-3 in subclass II did not contain any of the three conserved residues. We measured the expression levels of CsCLCs in roots, stems and leaves to assess the responses to different concentrations of Cl^- and F^-. The result indicated that CsCLCs participated in subfunctionalization in response to Cl^- and F^-, and CsCLC1-3 was more sensitive to F^- treatments than CsCLC4-8, CsCLC6 and CsCLC7 may participate in absorption and long-distance transport of Cl^-.

Associations of Endogenous Estradiol and Testosterone Levels With Plaque Composition and Risk of Stroke in Subjects With Carotid Atherosclerosis

RATIONALE

Sex steroids may play a role in plaque composition and in stroke incidence.

OBJECTIVES

To study the associations of endogenous estradiol and testosterone with carotid plaque composition in elderly men and postmenopausal women with carotid atherosclerosis, as well as with risk of stroke in this population.

METHODS AND RESULTS

Data of 1023 postmenopausal women and 1124 men (≥45 years) with carotid atherosclerosis, from prospective population-based RS (Rotterdam Study), were available. At baseline, total estradiol (TE) and total testosterone (TT) were measured. Carotid atherosclerosis was assessed by ultrasound, whereas plaque composition (presence of calcification, lipid core, and intraplaque hemorrhage) was assessed by magnetic resonance imaging. TE and TT were not associated with calcified carotid plaques in either sex. TE was associated with presence of lipid core in both sexes (in women odds ratio, 1.48 [95% confidence interval [CI], 1.02-2.15]; in men odds ratio, 1.23 [95% CI, 1.03-1.46]), whereas no association was found between TT and lipid core in either sex. Higher TE (odds ratio, 1.58 [95% CI, 1.03-2.40]) and lower TT (odds ratio, 0.82 [95% CI, 0.68-0.98]) were associated with intraplaque hemorrhage in women but not in men. In women, TE was associated with increased risk of stroke (hazard ratio, 1.98 [95% CI, 1.01-3.88]), whereas no association was found in men. TT was not associated with risk of stroke in either sex.

CONCLUSIONS

TE was associated with presence of vulnerable carotid plaque as well as increased risk of stroke in women, whereas no consistent associations were found for TT in either sex.

L-Arginine and SDMA Serum Concentrations Are Associated with Subclinical Atherosclerosis in the Study of Health in Pomerania (SHIP)

Objective

Even though ˪-arginine (ARG) derivatives can predict cardiovascular mortality, their role as atherosclerotic biomarkers is unclear. We tested the hypothesis if asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA) and the sum of both (DMA) are positively, while ARG and ARG/ADMA ratio are inversely associated with carotid intima-media thickness (cIMT) and atherosclerotic plaque in the carotid artery.

Approach and Results

Cross-sectional data of 1999 subjects (age: 45–81 years; 48.2% ♀) from the population-based Study of Health in Pomerania (SHIP-0) was used. Analysis of variance and logistic regression models were calculated and all adjusted models were corrected for sex, age, smoking status, waist-to-hip ratio and estimated glomerular filtration rate. Increased cIMT (>75^th age-sex specific percentile) was found in 517 subjects (25.7%), while atherosclerotic plaque was detected in 1413 subjects (70.4%). SDMA tertiles were significantly positively associated with larger cIMT among subjects with high SDMA levels [>66^th: 0.82 (95%-CI 0.80; 0.85) mm]. High SDMA levels were related to a higher odds ratio (OR) of increased cIMT [OR 1.39 (95%-CI 1.08; 1.79)]. Furthermore, ARG was positively associated with atherosclerotic plaques [OR 1.41 (95%-CI 1.07; 1.85)]. No relation was found for ADMA and atherosclerosis.

Conclusions

In conclusion, the hypothesis of a positive association between SDMA with an increased cIMT was confirmed. Unexpectedly, ARG was positively related to atherosclerotic plaque. In view of these inconsistent findings, the impact of ARG derivatives as atherosclerotic biomarkers deserves further research.

Testosterone, dihydrotestosterone and estradiol are differentially associated with carotid intima-media thickness and the presence of carotid plaque in men with and without coronary artery disease

Clarifying the relationship of sex hormones to preclinical atherosclerosis could illuminate pathways by which androgens are associated with cardiovascular events and mortality. Our aim was to determine hormone profiles associated with carotid intima-media thickness (CIMT) and carotid atheroma, in men with and without known coronary artery disease (CAD). We included 492 community-based men aged 20-70 years (Group A) and 426 men with angiographically proven CAD aged <60 years (Group B). Fasting early morning sera were assayed for testosterone (T), dihydrotestosterone (DHT) and estradiol (E2) using mass spectrometry. CIMT and carotid plaque were assessed ultrasonographically. Mean (±SD) age was Group A: 53.8±12.6 and Group B: 49.6±5.1 years. Higher T was associated with reduced CIMT (-0.011 mm per 1-SD increase, p=0.042) and lower prevalence of carotid plaque (odds ratio [OR] per 1-SD increase, 0.68, p=0.012) in Group A, but not B. E2 was associated with increased CIMT in Group A (0.013 mm, p=0.011) but not B. Higher DHT and E2 were associated with reduced carotid plaque in Group B (DHT: OR=0.77, p=0.024; E2: OR=0.75, p=0.008), but not A. In community-dwelling men, higher T is associated with favourable CIMT and lower prevalence of carotid plaque, while higher E2 is associated with worse CIMT. In men with CAD, higher DHT or E2 are associated with less carotid plaque. T, DHT and E2 are differentially associated with preclinical carotid atherosclerosis in a cardiovascular phenotype-specific manner. Interventional studies are needed to examine effects of exogenous T and its metabolites DHT and E2, on atherogenesis.

The relationship between testosterone, metabolic syndrome, and mean carotid intima-media thickness in aging men

We studied relationships between testosterone, metabolic syndrome, and mean carotid intima-media thickness (IMT) in aging men. We enrolled 935 men who had participated in a health examination. The median age was 57.0 years. Mean IMT showed a significant and negative linear correlation with testosterone (correlation co-efficiency = -0.067, p = 0.039). There was a significant increase in the percentage of men with hypogonadism in the second and third tertiles of mean IMT (p trend = 0.022). Logistic regression revealed a greater likelihood of hypogonadism in the third tertile mean IMT group when compared to the first tertile mean IMT group after adjusting for age and metabolic syndrome (OR = 1.700, p = 0.044). After adjusting for age and testosterone level, mean IMT was significantly higher in metabolic syndrome group as compared to non-metabolic syndrome group (0.733 mm versus 0.764 mm; p < 0.001). Mean testosterone level was significantly lower in metabolic syndrome group as compared to non-metabolic syndrome group after adjusting for age and mean IMT (5.52 ng/mL versus 4.89 ng/mL; p < 0.001). Mean IMT, testosterone, and metabolic syndrome were significantly and independently correlated with each other in aging male. Further studies are needed to confirm our results and to elucidate their causative relationship.

Do low testosterone levels contribute to ill-health during male ageing?

Testosterone regulates male sexual development and body composition. In adult men, testosterone levels exhibit a gradual decline with increasing age. Whether it is age per se or health and behaviour related factors that are responsible for this decline, and the implications thereof for subsequent health remain controversial. Observational studies report associations of lower testosterone levels with poorer health outcomes in ageing men, including frailty, reduced sexual activity, insulin resistance and cardiovascular events and mortality. However, outcome data from randomised clinical trials of testosterone are limited, and are lacking for major endpoints such as cardiovascular events. The risks and benefits of testosterone intervention in older men require further clarification. This article will review the role of testosterone in men, discuss epidemiological and interventional data illuminating its potential role to preserve health during male ageing, consider the limitations of the evidence base and implications for clinical practice, and explore future directions for research in this topical area.

Mendelian randomization suggests non-causal associations of testosterone with cardiometabolic risk factors and mortality

Prospective studies showed that low serum testosterone concentrations are associated with various cardiometabolic risk factors and mortality. However, the causal nature of these associations is controversial. We studied 1 882 men aged 20-79 years with serum testosterone concentrations and genotyping data from the longitudinal population-based Study of Health in Pomerania. Testosterone concentrations were cross-sectionally associated with cardiometabolic risk factors, including anthropometric, lipid, blood pressure and glycaemic parameters; and prospectively with all-cause mortality (277 deaths, 14.7%) during the 10-year follow-up. To overcome problems of residual confounding, reverse causation, or regression dilution bias in the investigated testosterone-outcome associations, we used two-stage least square regression models with previously identified polymorphisms at the SHBG gene (rs12150660) and X chromosome (rs5934505) as multiple genetic instruments in an instrumental variable (IV) approach, also known as Mendelian randomization. In standard regression analyses, testosterone was robustly associated with a wide range of cardiometabolic risk factors. In subsequent IV analyses, no such significant associations were observed. Similarly, prospective analyses showed a consistent association of low testosterone concentrations with increased all-cause mortality risk, which was not apparent in subsequent IV analyses. The present Mendelian randomization analyses did not detect any evidence for causal associations of testosterone concentrations with cardiometabolic risk factors and mortality, suggesting that previously reported associations might largely result from residual confounding or reverse causation. Although testosterone assessment might improve risk prediction, implementation of testosterone replacement therapy requires further evidence of a direct effect on cardiometabolic outcomes from double-blinded randomized controlled trials and large-scale Mendelian randomization meta-analyses.

Low plasma testosterone and elevated carotid intima-media thickness: importance of low-grade inflammation in elderly men

CONTEXT AND OBJECTIVE

An inverse correlation between plasma testosterone levels and carotid intima-media thickness (IMT) has been reported in men. We investigated whether this association could be mediated or modified by traditional cardiovascular risk factors as well as inflammatory status.

METHODS

In the Three-City population-based cohort study, 354 men aged 65 and over had available baseline data on hormones levels and carotid ultrasonography. Plasma concentrations of testosterone (total and bioavailable), estradiol and sex hormone-binding globulin (SHBG), together with cardiovascular risk factors were measured. IMT in plaque-free site and atherosclerotic plaques in the extracranial carotid arteries were determined using a standardized protocol. Multiple linear regression models were used to analyze this association and interaction study.

RESULTS

Analyses with and without adjustment for cardiovascular risk factors showed that carotid IMT was inversely and significantly correlated with total and bioavailable testosterone levels but not with SHBG and estradiol levels. This association depended on C-reactive protein (CRP) levels (p for interaction <0.05). Among men with low-grade inflammation (CRP ≥2 mg/L), mean IMT was higher in subjects with bioavailable testosterone ≤ 3.2 ng/mL than in those with bioavailable testosterone > 3.2 ng/mL (0.76 mm and 0.70 mm respectively, p < 0.01). By contrast, among men with CRP ≤ 2 mg/L, mean IMT was similar in both groups (0.72 mm and 0.71 mm respectively, p = 0.77). Similar results were found for total testosterone although not significant. No association was found between plasma hormones levels and atherosclerotic plaques.

CONCLUSION

In elderly men, low plasma testosterone is associated with elevated carotid intima-media thickness only in those with low-grade inflammation. Traditional risk factors have no mediator role.

Relation between sex hormone concentrations, peripheral arterial disease, and change in ankle-brachial index: findings from the Framingham Heart Study

OBJECTIVE

Our objective was to investigate cross-sectional and longitudinal associations of sex hormone concentrations with ankle-brachial index (ABI) and peripheral arterial disease (PAD).

METHODS AND RESULTS

We used data from 3034 (1612 women) participants of the Framingham Heart Study. ABI was measured and PAD defined as ABI below 0.90, intermittent claudication, or lower extremity revascularization. Sex hormone concentrations were measured by liquid chromatography-tandem mass spectrometry [total testosterone (T), total estradiol, and estrone], immunofluorometric assay (SHBG), or calculated (free T). Sex-specific multivariable linear and logistic regression models were conducted for each sex hormone separately. Cross-sectional multivariable analyses revealed that men with lower free T and higher estrone (E1) concentrations had a significantly lower ABI [for free T, lowest vs. higher quartiles, β = -0.02, with 95% confidence interval (CI) = -0.04 to -0.001; and for E1, highest vs. lower quartiles, β = -0.02, with 95% CI = -0.04 to -0.002, respectively). Lower total T and SHBG concentrations were also associated with prevalent PAD in age-adjusted [odds ratio (OR) = 2.24, 95% CI = 1.17-4.32; and OR = 2.06; 95% CI = 1.07-3.96, lowest vs. highest quartile, respectively), but not in multivariable logistic regression models. Longitudinal multivariable analyses showed an association of lower SHBG with ABI change (decline ≥ 0.15; n = 69) in men [OR for SHBG quartiles 1, 2, and 3 as compared with quartile 4 were 2.56 (95% CI = 1.01-6.45), 2.28 (95% CI = 0.98-5.32), and 2.93 (95% CI = 1.31-6.52), respectively]. In women, none of the investigated associations yielded statistically significant estimates.

CONCLUSION

Our investigation of a middle-aged community-based sample suggests that sex hormone concentrations in men but not in women may be associated with PAD and ABI change.

Cardiovascular and metabolic influences of fetal smoke exposure

Many epidemiological studies showed associations of low birth weight with cardiovascular disease, type 2 diabetes and obesity. The associations seem to be consistent and stronger among subjects with a postnatal catch up growth. It has been suggested that developmental changes in response to adverse fetal exposures might lead to changes in the fetal anatomy and physiology. These adaptations may be beneficial for short term, but may lead to common diseases in adulthood. Maternal smoking during pregnancy is one of the most important adverse fetal exposures in Western countries, and is known to be associated with a 150-200 g lower birth weight. An accumulating body of evidence suggests that maternal smoking during pregnancy might be involved in pathways leading to both low birth weight and common diseases, including cardiovascular disease, type 2 diabetes and obesity, in adulthood. In this review, we discuss epidemiological studies focused on the associations of maternal smoking with fetal growth and development and cardiovascular and metabolic disease in later life. We also discuss potential biological mechanisms, and challenges for future epidemiological studies.

Cardiovascular and metabolic influences of fetal smoke exposure

Many epidemiological studies showed associations of low birth weight with cardiovascular disease, type 2 diabetes and obesity. The associations seem to be consistent and stronger among subjects with a postnatal catch up growth. It has been suggested that developmental changes in response to adverse fetal exposures might lead to changes in the fetal anatomy and physiology. These adaptations may be beneficial for short term, but may lead to common diseases in adulthood. Maternal smoking during pregnancy is one of the most important adverse fetal exposures in Western countries, and is known to be associated with a 150–200 g lower birth weight. An accumulating body of evidence suggests that maternal smoking during pregnancy might be involved in pathways leading to both low birth weight and common diseases, including cardiovascular disease, type 2 diabetes and obesity, in adulthood. In this review, we discuss epidemiological studies focused on the associations of maternal smoking with fetal growth and development and cardiovascular and metabolic disease in later life. We also discuss potential biological mechanisms, and challenges for future epidemiological studies.

Prospective association of low total testosterone concentrations with an adverse lipid profile and increased incident dyslipidemia

BACKGROUND

Earlier studies have suggested that total testosterone concentrations influence the lipid metabolism. Whether these concentrations are prospectively associated with an adverse lipid profile and an increased risk of incident dyslipidemia has not yet been investigated.

METHODS AND RESULTS

Our study population consisted of 1468 men, aged 20–79 years, who were repeatedly examined as part of the population-based Study of Health in Pomerania. Serum total testosterone concentrations measured by the chemiluminescent enzyme immunoassays were categorized into age-specific quartiles. We used generalized estimating equations models to assess the prospective association between total testosterone concentrations and lipid profile components including total cholesterol (TC), low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride (TG) concentrations, as well as incident dyslipidemia after 5 years of follow-up. Multivariate models revealed that total testosterone concentrations in the lowest quartile were associated with higher TC and TG concentrations in both cross-sectional [TC: 0.23 mmol/l (95% confidence interval, CI, 0.02–0.42); TG: 0.73 mmol/l (95% CI, 0.53–0.94)] and longitudinal analyses [TC: 0.20 mmol/l (95% CI, 0.03–0.27); TG: 0.62 mmol/l (95% CI, 0.43–0.80)], but not with high-density lipoprotein cholesterol or low-density lipoprotein cholesterol concentrations. Baseline prevalence of dyslipidemia was 57.1% with a crude incidence rate of 46.6 per 1000 person-years. Total testosterone concentrations in the lowest quartile predicted dyslipidemia; age-adjusted relative risks (RR) for men in quartiles 1, 2, and 3 as compared to quartile 4 (highest, reference) were 1.28 (95% CI, 1.06–1.54), 1.10 (95% CI, 0.91–1.33), and 1.05 (95% CI, 0.86–1.29), respectively. This effect was particularly strong among men aged 20–39 years (relative risk, 1.51; 95% CI, 1.08–2.10).

CONCLUSION

Low total testosterone concentrations are prospectively associated with an adverse lipid profile and increased risk of incident dyslipidemia. These findings are particularly interesting and may contribute to an explanation for the higher cardiovascular disease risk in men with lower total testosterone concentrations.

The Rotterdam Study: 2012 objectives and design update

The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, oncological, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. The findings of the Rotterdam Study have been presented in over a 1,000 research articles and reports (see www.erasmus-epidemiology.nl/rotterdamstudy ). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods.

Low serum testosterone is associated with increased mortality in men with stage 3 or greater nephropathy

BACKGROUND

Chronic kidney disease (CKD) and low serum total testosterone (TT) concentrations are independent predictors of mortality risk in the general population, but their combined potential for improved mortality risk stratification is unknown.

METHODS

We used data of 1,822 men from the population-based Study of Health in Pomerania followed- up for 9.9 years (median). The direct effects of kidney dysfunction (estimated glomerular filtration rate <60 ml/min/ 1.73 m(2)), albuminuria (urinary albumin-creatinine ratio ≥2.5 mg/mmol) and their combination (CKD) on all-cause and cardiovascular mortality were analyzed using multivariable Cox regression models. Serum TT concentrations below the age-specific 10th percentile (by decades) were considered low and were used for further risk stratification.

RESULTS

Kidney dysfunction (hazard ratio, HR, 1.40; 95% confidence interval, CI, 1.02-1.92), albuminuria (HR, 1.38; 95% CI, 1.06-1.79), and CKD (HR, 1.42; 95% CI, 1.09-1.84) were associated with increased all-cause mortality risk, while only kidney dysfunction (HR, 2.01; 95% CI, 1.21-3.34) was associated with increased cardiovascular mortality risk after multivariable adjustment. Men with kidney dysfunction and low TT concentrations were identified as high-risk individuals showing a more than 2-fold increased all-cause mortality risk (HR, 2.52; 95% CI, 1.08-5.85). Added to multivariable models, nonsignificant interaction terms suggest that kidney dysfunction and low TT are primarily additive rather than synergistic mortality risk factors.

CONCLUSION

In the case of early loss of kidney function, measured TT concentrations might help to detect high-risk individuals for potential therapeutic interventions and to improve mortality risk assessment and outcome.

The Shanghai Changfeng Study: a community-based prospective cohort study of chronic diseases among middle-aged and elderly: objectives and design

The Shanghai Changfeng Study is a community-based prospective cohort study of chronic diseases ongoing since February 2009 in Shanghai, China. The study focuses on multiple chronic diseases, including obesity and metabolic syndrome, diabetes, osteoporosis, liver diseases, cardiovascular diseases and neurologic diseases. 15,000 subjects of 40 years or over are planned to be recruited. The rationale, objectives and design of this study are described in this paper.

Testosterone therapy: treatment of metabolic disturbances in heart failure

Heart failure (HF) is a complex progressive multisystem disease state with significant morbidity and mortality, which is not solely defined by pathology of the cardiovascular system but also is influenced by neurohormonal regulatory adjustments, peripheral cytokines, as well as hormonal and musculoskeletal dysfunction. Recent attention to the catabolic state found in patients with chronic heart failure has sparked interest in new potential targets for medical therapy. In particular, as many as 26% to 37% of men affected with HF have been found to be testosterone deficient. The severity of androgen deficiency has been shown to correlate with symptoms, functional class, and prognosis in patients with heart failure. Testosterone supplementation has been an accepted therapy in hypogonadal men with fatigue, muscle wasting, and sexual dysfunction for some time. Patients with severe HF show a similar constellation of symptoms and hypothetically would benefit from androgen replacement. Recent clinical studies have confirmed that functional, biochemical, and cardiopulmonary status in patients with HF have significant improvements when treated with testosterone supplementation. Symptomatic improvements may be obtainable in hypogonadal patients with HF who receive supplemental testosterone. This review seeks to outline the cardiovascular and peripheral effects of testosterone supplementation in patients with chronic HF.

The Generation R Study: design and cohort update 2010

The Generation R Study is a population-based prospective cohort study from fetal life until young adulthood. The study is designed to identify early environmental and genetic causes of normal and abnormal growth, development and health during fetal life, childhood and adulthood. The study focuses on four primary areas of research: (1) growth and physical development; (2) behavioural and cognitive development; (3) diseases in childhood; and (4) health and healthcare for pregnant women and children. In total, 9,778 mothers with a delivery date from April 2002 until January 2006 were enrolled in the study. General follow-up rates until the age of 4 years exceed 75%. Data collection in mothers, fathers and preschool children included questionnaires, detailed physical and ultrasound examinations, behavioural observations, and biological samples. A genome wide association screen is available in the participating children. Regular detailed hands on assessment are performed from the age of 5 years onwards. Eventually, results forthcoming from the Generation R Study have to contribute to the development of strategies for optimizing health and healthcare for pregnant women and children.

Androgens and cardiovascular disease

PURPOSE OF REVIEW

There is increasing interest in age-related changes in sex hormone levels as a potentially treatable cause of ill-health in men. Relationships between androgens and cardiovascular disease will be discussed, with particular attention to more recently published research.

RECENT FINDINGS

In middle-aged and older men, lower testosterone levels are associated with insulin resistance, metabolic syndrome and diabetes, interrelated conditions that predispose to cardiovascular disease. The relationship between androgens and preclinical atherosclerosis requires confirmation. Nevertheless, lower testosterone levels predict cardiovascular events, such as stroke and transient ischaemic attack, in older men and are associated with higher cardiovascular and overall mortality. Testosterone is aromatized to oestradiol, and both higher and lower oestradiol levels have been associated with cardiovascular risk. Randomized trials have shown that testosterone supplementation in men with existing coronary artery disease can be protective against myocardial ischaemia. However, additional interventional studies are needed with endpoints of cardiovascular events.

SUMMARY

Observational studies continue to relate reduced circulating testosterone to cardiovascular risk, atherosclerosis and mortality in men. The role of oestradiol as a marker for cardiovascular disease requires clarification. Larger randomized trials are needed to establish whether hormonal therapy would reduce the burden of cardiovascular disease in ageing men.