Testosterone and acute stress are associated with fibrinogen and von Willebrand factor in African men: The SABPA study

Leptin and the Retinal Microvasculature in Young Black and White Adults: The African-PREDICT Study

BACKGROUND

Leptin is a vasoactive peptide that has been linked to diseases associated with macrovascular deterioration. What is still uncertain is its involvement in the microvasculature. Since microvascular changes are presumed to precede macrovascular deterioration, we examined whether measures of the retinal microvasculature are associated with leptin in healthy, young Black and White individuals.

METHOD

We included 283 Black and 289 White men and women (aged 20-30 years). We determined serum leptin, calculated central retinal artery and vein equivalents and arterio-venous ratio. We also measured retinal vessel responses to light flicker provocation.

RESULTS

Black men were leaner and had lower leptin than White men, whereas Black women had increased adiposity and leptin compared to White women (all p<0.001). Black groups had narrower retinal arteries, and greater maximum arteriolar and venular dilations in response to light flicker than the White groups (p<0.001). Arterio-venous ratio associated negatively with leptin (all p≤0.044) in all groups (except Black women), but was lost upon adjustment for body mass index and other covariates. We found an inverse association between maximal venular dilation and leptin only in Black men in single and multiple regression analyses (Std β= -0.22; R²=0.05; p=0.035). No associations were found between other retinal measures with leptin in the other groups.

CONCLUSION

We found an independent, negative association between retinal vein dilation with leptin in healthy, young Black men, suggesting a potential detrimental role for leptin in regulating microvascular responses in a population group known to be at greater risk of cardiovascular disease development.

Associations between Peripheral Thromboembolic Vascular Disease and Androgen Deprivation Therapy in Asian Prostate Cancer Patients

This study aimed to investigate the risks of thromboembolic vascular disease following androgen deprivation therapy (ADT) administered to prostate cancer (PCa) patients. A total of 24,464 men with newly diagnosed PCa during 2000–2008 were recruited through a longitudinal health insurance database in Taiwan. All PCa patients were stratified into two: ADT and non-ADT groups. Patients with ADT treatment were grouped into three: surgical castration, chemical castration, and anti-androgen alone. The risks of pulmonary embolism (PE), peripheral arterial occlusion disease (PAOD), and deep vein thrombosis (DVT) were assessed in multiple Cox proportional-hazards regression with time-dependent covariates. During the 12-year follow-up period, incidence rates per 1000 person-years in ADT and non-ADT groups were 2.87 and 1.62 for DVT, 1.00 and 0.52 for PE, and 1.03 and 0.70 for PAOD, respectively. The DVT and PE risks were significantly increased in patients receiving combined androgen blockade (CAB) compared with the counterpart ADT non-recipients. After adjusting for potential risk factors, PCa patients receiving CAB had the highest PE risk (HR = 3.11), followed by DVT risk (HR = 2.53). The DVT risk remained elevated throughout the entire duration of chemical castration. However, high PE risk was observed in patients with ≤720-day treatment duration. No association was found between ADT and PAOD risks. Overall, the risks of PE and DVT were considerably heightened in Asian men subjected to CAB for PCa, whereas PAOD risk was unrelated to such treatments.

The Association between Serum Testosterone and Risk Factors for Atherosclerosis

Objective

To study the associations between serum testosterone and risk factors for atherosclerosis in 119 men from general population.

Methods

Systolic pressure, body mass index (BMI), testosterone, fasting glucose, glucose tolerance test, apolipoprotein A-1 (ApoA-1), apolipoprotein B (ApoB), and ApoB/ApoA-1 ratio were assessed. Subjects classified into hypogonadal (testosterone ≤ 12 nmol/l), and eugonadal men (testosterone > 12 nmol/l).

Results

BMI (28 vs. 26 kg/ m², p = 0.01), systolic pressure (129 vs. 123 mmHg, p = 0.03), fasting glucose (5.9 vs. 5.5 mmol/l, p = 0.03), ApoB (1.1 vs. 1.0 g/l, p = 0.03), and ApoB/ApoA-1 ratio (0.8 vs. 0.7, p = 0.03) were higher in hypogonadal compared to eugonadal men, respectively. In adjusted multivariate regression analysis model, testosterone showed negative associations with BMI (β = -1.832, p = 0.030, 95% CI = -3.485--0.180), fasting glucose (β = -0.394, p = 0.011, 95% CI = -0.696--0.091), glucose tolerance test (β = -0.957, p = 0.045, 95% CI = -1.892--0.022), ApoB (β = -0.157, p = 0.017, 95% CI = -0.286--0.029), and ApoB/ApoA-1 ratio (β = -0.118, p = 0.046, 95% CI = -0.234--0.002).

Conclusions

These results suggest an inverse association between testosterone levels and risk factors for atherosclerosis.

Prospective Study of Endogenous Hormones and Incidence of Venous Thromboembolism: The Atherosclerosis Risk in Communities Study

Exogenous hormone treatments in women (oral contraceptives and hormone replacement therapy [HRT]) are established risk factors for venous thromboembolism (VTE), but less is known about associations between plasma levels of endogenous hormones and VTE risk. We examined the association of baseline dehydroepiandrosterone sulphate (DHEAS), testosterone and sex hormone-binding globulin (SHBG) with risk of future VTE in men and post-menopausal women in the Atherosclerosis Risk in Communities Study. Testosterone, DHEAS and SHBG were measured in plasma samples collected in 1996 to 1998. Cox proportional hazards models were used to estimate hazard ratios for incident VTE adjusting for age, race/ethnicity, body mass index, height, smoking, estimated glomerular filtration rate and C-reactive protein. All analyses were stratified by sex and by current HRT use in women. Among 3,051 non-HRT-using women, 1,414 HRT-using women and 3,925 men at risk at baseline, 184, 62 and 206 experienced incident VTE after a median follow-up of 17.6 years. Plasma hormones were not associated with incidence of VTE among men and non-HRT-using women, although lower plasma DHEAS, when modelled using quartiles or restricted cubic splines, was associated with higher risk of VTE among HRT-using women. This study does not support the existence of an important association between plasma concentrations of endogenous testosterone, DHEAS or SHBG with risk of VTE in middle-aged to older men or post-menopausal women not using HRT.

The protective role of oestradiol against silent myocardial ischemia and hypertension risk in South African men: The SABPA study

BACKGROUND

Oestradiol has a protective effect on coronary artery health in women but the effect it has on men, is controversial. A translational approach was followed to assess whether sex hormone levels are associated with silent myocardial ischemia (SMI) and hypertension risk over a 3year period.

METHODS

Participants included 89 Black and 91 White men (aged 21-63years) participating in both phases of the Sympathetic activity and Ambulatory Blood Pressure in Africans prospective study. Fasting blood samples, ambulatory blood pressure and 2-lead ECG recordings were obtained.

RESULTS

No difference in the levels of the various baseline serum T fractions between the two ethnic groups occurred. Oestradiol of the Black men increased by 54.2% compared to a decrease of 24.1% in the White men. Changes in total oestradiol (adjusted R²=0.33, β=-0.31, p=0.023) and free oestradiol (adjusted R²=0.34, β=-0.33, p=0.019) were inversely associated with changes in SMI in the Black men but not in White men. Baseline serum nitric oxide metabolites were inversely associated with ΔSMI in the Blacks only (adjusted R²=0.33, β=-0.28, p=0.047). Chronic SMI was associated with 24h hypertension in Blacks [cut point 1.5 events: Area under the curve 0.71 (95% CI: 0.60, 0.82); p=0.006; with sensitivity/specificity 44%/94%].

CONCLUSIONS

Chronic SMI events facilitated future ischemic heart disease in Black men. Up-regulated free oestradiol seems to be involved in the protection of the heart against SMI and hypertension risk in Black but not in White men. A similar protective role for testosterone could however not be shown.

Comparison Between Thromboelastography and Conventional Coagulation Tests in Surgical Patients With Localized Prostate Cancer

We aimed to examine hypercoagulable and hypocoagulable conditions in patients with prostate cancer using thromboelastography (TEG) and correlate TEG parameters with conventional coagulation test. The t test was used for comparing TEG parameters and routine coagulation results. Spearman rank-order correlation was used to describe the relationship of TEG and conventional tests. Sensitivity, specificity, positive predictive values, and negative predictive values were determined for bleeding and thrombosis. Totally, 20 patients had active bleeding postoperatively, 16 of whom showed hypocoagulation on TEG test and 9 of whom showed hypocoagulation by routine coagulation test ( P = .024). Overall, 60 patients did not have active bleeding postoperatively, 51 of whom showed hypercoagulation detected by TEG test and 42 of whom showed hypercoagulation found by routine coagulation test ( P = .040). Remarkably, patients had a little higher fibrinogen (FIB) compared to controls. There was no statistical difference in any of the conventional coagulation indexes between the groups. Correlation analysis showed that reaction time (R) and coagulation time (K) were positively correlated with the prothrombin time-international normalized ratio (PT-INR) and negatively correlated with FIB ( P < .001). Contrarily, α-angle and maximum amplitude (MA) were negatively correlated with PT-INR but positively correlated with FIB. Significantly, MA showed the strongest correlation with FIB and R exhibited the strongest correlation with PT-INR. Sensitivity and specificity for bleeding and thrombosis in TEG were higher than those in conventional coagulation test. Accordingly, TEG might be superior in evaluating hypercoagulation and detecting the risk of bleeding in patients with prostate cancer.

Effects of androgen-deprivation therapy on hypercoagulability in prostate cancer patients: A prospective, longitudinal study

INTRODUCTION

Androgen-deprivation therapy (ADT) is the mainstay of systemic therapy for advanced prostate cancer (PCa), but has significant adverse effects, including increasing concern for cardiovascular (CV) and thromboembolic (TE) complications. This study carefully investigates any relationship between ADT use and hypercoagulability as a possible mechanism of these adverse effects.

METHODS

We performed a prospective, longitudinal study in a cohort of patients with advanced PCa initiating ADT (n=18). Controls included men with biochemical failure after local therapy on watchful waiting (n=10), as well as healthy controls (n=8). Global hemostasis was evaluated using the sensitive global hemostasis assay, thromboelastography (TEG). Patients were evaluated at baseline and every three months for a minimum of 12 months.

RESULTS

The results of the TEG studies demonstrated 14/18 (78%) of advanced PCa patients had evidence of a hypercoagulable state before initiating therapy. Significant baseline hypercoagulability was documented in this cohort compared to the two control groups. ADT did not appear to exacerbate hypercoagulability over time as a whole: only 10/18 (56%) patients had TEG findings consistent with hypercoagulability at the end of study. However, 3/18 (17%) PCa patients initiating ADT had significantly new hypercoagulable TEG changes on treatment compared to baseline.

CONCLUSIONS

This prospective pilot study demonstrates a complex interaction between ADT and hypercoagulable state in men with advanced PCa. TEG abnormalities were mostly associated with volume of cancer as compared to ADT use; however, it is possible that ADT may lead to hypercoagulability in a subset of men, suggesting that sensitive monitoring of coagulation of men on ADT could help identify those at risk of developing CV/TE complications. Study limitations include the relatively small cohort of men followed after initiating ADT and these results require confirmation in a larger trial to rule out subtle effects on hypercoagulability.

Cohort Profile: Sympathetic activity and Ambulatory Blood Pressure in Africans (SABPA) prospective cohort study

Adapting to an over-demanding stressful urban environment may exhaust the psychophysiological resources to cope with these demands, and lead to sympathetic nervous system dysfunction. The evidence that an urban-dwelling lifestyle may be detrimental to the cardiometabolic health of Africans motivated the design of the Sympathetic activity and Ambulatory Blood Pressure in African Prospective cohort study. We aimed to determine neural mechanistic pathways involved in emotional distress and vascular remodelling. The baseline sample included 409 teachers representing a bi-ethnic sex cohort from South Africa. The study was conducted in 2008–09 and repeated after 3-year follow-up in 2011–12, with an 87.8% successful follow-up rate. Seasonal changes were avoided and extensive clinical assessments were performed in a well-controlled setting. Data collection included sociodemographics, lifestyle habits, psychosocial battery and genetic analysis, mental stress responses mimicking daily life stress (blood pressure and haemostatic, cardiometabolic, endothelial and stress hormones). Target organ damage was assessed in the brain, heart, kidney, blood vessels and retina. A unique highly phenotyped cohort is presented that can address the role of a hyperactive sympathetic nervous system and neural response pathways contributing to the burden of cardiometabolic diseases in Africans.