Protective effect of ß-sitosterol against high-fructose diet-induced oxidative stress, and hepatorenal derangements in growing female sprague-dawley rats.

BACKGROUND: Chronic consumption of a high-fructose diet causes oxidative stress that compromises kidney and liver health. ß-sitosterol (Bst), a phytosterol, is a functional nutrient with health benefits. ß-sitosterol antioxidant activity protects the liver and kidney from ROS-mediated damage and lipid peroxidation. We evaluated the potential renoprotective and hepatoprotective effects of orally administrated ß-sitosterol in high-fructose diet-fed growing female rats. Thirty-five 21-day old female Sprague-Dawley rat pups were randomly assigned to and administered the following treatments for 12 weeks: group I- standard rat chow (SRC) + plain drinking water (PW) + plain gelatine cube (PC); group II- SRC + 20% w/v fructose solution (FS) as drinking fluid + PC; group III- SRC + FS + 100 mg/kg body mass (BM) fenofibrate in gelatine cube; group IV- SRC + FS + 20 mg/kg BM ß-sitosterol gelatine cube (Bst) and group V- SRC + PW + Bst. The rats were fasted overnight, weighed then euthanised. Blood was collected, centrifuged and plasma harvested. Livers and kidneys were excised, weighed and samples preserved for histological assessments. Plasma biomarkers of oxidative stress, liver and kidney function and renal tubular injury were assessed. RESULTS: High fructose diet fed rats had increased plasma KIM-1, NGAL (p < 0.001) and MDA levels (p < 0.05). Dietary fructose caused microvesicular and macrovesicular steatosis, and reduced glomerular density, Bowman's capsule area and urinary space. ß-sitosterol protected against the high-fructose diet-induced hepatic steatosis and glomerular disturbances without adverse effects on liver and kidney function. CONCLUSIONS: ß-sitosterol, as a dietary supplement, could potentially be exploited to prevent high-fructose diet-induced NAFLD and to protect against high-fructose diet-induced renal tubular injury.

Neonatal administration of fenofibrate had no developmental programming effect on the lipid profile and relative leucocyte telomere lengths of adolescent rats fed a high-fructose diet postnatally.

Telomere length, a marker of ageing, is susceptible to developmental programming that may cause its accelerated attrition. Metabolic syndrome triggers telomere attrition. Fenofibrate, a peroxisome proliferator-activated receptor-alpha agonist, is protective against telomere attrition. We investigated the impact of fenofibrate administered during suckling on the lipid profile and leucocyte telomere lengths of rats fed a high-fructose diet post-weaning. Suckling Sprague-Dawley pups (n = 119) were allocated to four groups and gavaged with either 10 mL·kg-1 body mass 0.5% dimethyl sulfoxide, 100 mg·kg-1 body mass fenofibrate, fructose (20%, w / v), or a combination of fenofibrate and fructose for 15 days. Upon weaning, each of the initial groups was split into two subgroups: one had plain water while the other had fructose solution (20%, w / v) to drink for 6 weeks. Blood was collected for DNA extraction and relative leucocyte telomere length determination by real-time PCR. Plasma triglycerides and cholesterol were also quantified. The treatments had no effect (p > 0.05) on body mass, cholesterol concentration, and relative leucocyte telomere lengths in both sexes. Post-weaning fructose increased triglyceride concentrations (p < 0.05) in female rats. Fenofibrate administered during suckling did not affect ageing nor did it prevent high fructose-induced hypertriglyceridaemia in female rats.

ß-Sitosterol Shows Potential to Protect Against the Development of High-Fructose Diet-Induced Metabolic Dysfunction in Female Rats.

Metabolic syndrome (MetS) is a combination of risk factors that include insulin resistance, obesity, dyslipidemia, and hypertension. The consumption of high-fructose diets contributes to the development of MetS. ß-sitosterol a naturally occurring phytosterol possesses antiobesogenic and antidiabetic effects. This study evaluated the potential protective effect of ß-sitosterol against the development of metabolic dysfunction in growing female rats fed a high-fructose diet, mimicking children fed obesogenic diets. Thirty-five 21-day-old female Sprague Dawley rat pups were randomly allocated to and administered the following treatments: group 1-standard rat chow (SRC) + plain drinking water (PW) + plain gelatine cube (PC); group 2-SRC + 20% w/w fructose solution (FS) as drinking fluid + PC; group 3-SRC + FS + 100 mg/kg fenofibrate in gelatine cubes; group 4-SRC + FS + 20 mg/kg ß-sitosterol gelatine cube (Bst); and group 5-SRC + PW + Bst. Following 12 weeks of feeding, the rats were fasted overnight, weighed, and then euthanized. Plasma cholesterol, insulin, glucose, triglyceride, and adiponectin concentrations were determined. Visceral fat was dissected out and weighed. The high-fructose diet increased (P < .05) visceral adiposity and plasma triglyceride concentration but decreased (P < .05) plasma adiponectin concentration. ß-sitosterol prevented the high-fructose diet-induced visceral obesity, hypertriglyceridemia, and hypoadiponectinemia. ß-sitosterol alone increased plasma adiponectin concentration and reduced plasma insulin concentration and homeostatic model assessment index. In conclusion, ß-sitosterol could be potentially used to prevent high-fructose diet-induced metabolic dysfunction.

ß-Sitosterol mitigates the development of high-fructose diet-induced nonalcoholic fatty liver disease in growing male Sprague-Dawley rats.

Fructose contributes to the development of nonalcoholic fatty liver disease (NAFLD). ß-Sitosterol (Bst), a naturally occurring phytosterol, has antihyperlipidaemic and hepatoprotective properties. This study interrogated the potential protective effect of ß-sitosterol against NAFLD in growing rats fed a high-fructose diet, modelling children fed obesogenic diets. Forty-four 21 day old male rat pups were randomly allocated to and administered the following treatments for 12 weeks: group I, standard rat chow (SRC) + plain drinking water (PW) + plain gelatine cube (PC); group II, SRC + 20% w/v fructose solution (FS) as drinking fluid + PC; group III, SRC + FS + 100 mg/kg fenofibrate in a gelatine cube; group IV, SRC + FS + 20 mg/kg ß-sitosterol gelatine cube (Bst); group V, SRC + PW + Bst. Terminally, the livers were dissected out, weighed, total liver lipid content determined, and histological analyses done. Harvested plasma was used to determine the surrogate biomarkers of liver function. The high-fructose diet caused increased (p < 0.05) hepatic lipid (total) accretion (>10% liver mass), micro- and macrovesicular hepatic steatosis, and hepatic inflammation. ß-Sitosterol and fenofibrate prevented the high-fructose diet-induced macrovesicular steatosis and prevented the progression of NAFLD to steatohepatitis. ß-Sitosterol can prospectively be used to mitigate diet-induced NAFLD.

Telomere length, endothelial activation and carotid atherosclerosis in black and white African patients with rheumatoid arthritis.

OBJECTIVES: Our objective was to examine associations of traditional and non-traditional cardiovascular risk factors with relative leukocyte telomere length and confounder adjusted relationships of relative telomere length with endothelial activation and carotid atherosclerosis in black and white African patients with rheumatoid arthritis (RA). METHODS: Relative telomere length of leukocyte DNA in whole blood was determined using quantitative RT-PCR in 205 (101 black) African patients with RA. RESULTS: In demographic characteristic adjusted analysis, relative telomere length tended to be larger in black compared to white patients (median (IQR)=0.54 (0.42-0.54) and 0.48 (0.37-0.60) (p=0.07), respectively). In black patients, waist circumference, systolic, diastolic and mean blood pressure were associated with relative telomere length (ß (SE)=-0.00270 (0.00114) (p=0.02), -0.00185 (0.00060) (p=0.003), -0.00243 (0.00112) (p=0.03) and -0.00225 (0.00075) (p=0.003), respectively); in white patients, age, anti-cyclic citrullinated antibody positivity, biologic agent use, a cholesterol-HDL cholesterol ratio of >4 and the number of major traditional risk factors were related to relative telomere length (ß (SE) =-0.00242 (0.00113) (p=0.03), 0.06629 (0.03374) (p=0.05), -0.09321 (0.04310) (p=0.03), 0.08225 (0.03420) (p=0.02) and 0.04046 (0.01719) (p=0.02), respectively). One SD increase in relative telomere length was associated with carotid plaque (OR (95% CI)=1.65 (0.99-2.75) (p=0.05)) and vascular cell adhesion molecule-1 concentrations (ß (SE)=-0.05031 (0.02480) (p=0.04)) in black and white patients, respectively. CONCLUSIONS: This study disclosed paradoxically direct relationships between relative telomere length and cardiovascular risk factors in white and atherosclerosis in black African RA patients. The role of relative telomere length in cardiovascular risk and its stratification in RA requires longitudinal investigation.

Ethanol-Associated Cardiomyocyte Apoptosis and Left Ventricular Dilation Are Unrelated to Changes in Myocardial Telomere Length in Rats.

AIM: The aim of this work was to determine whether ethanol-associated myocardial apoptosis and cardiac dilation are related to myocardial telomere shortening in rats. METHODS AND RESULTS: Sprague-Dawley (SD) rats received either drinking water with (ethanol: n = 19) or without (control: n = 19) 5% (v/v) ethanol ad libitum, for 4 months. Left ventricular (LV) dimensions and function (echocardiography and isolated perfused heart preparations), cardiomyocyte apoptosis (terminal deoxynucleotide transferase-mediated dUTP nick-end labeling), and leukocyte and myocardial telomere length (real-time polymerase chain reaction) were determined at the end of the study. Ethanol administration resulted in a marked increase in cardiomyocyte apoptosis (ethanol 0.85 ± 0.13% vs control 0.36 ± 0.06%; P = .0021) and LV dilation (LV end-diastolic diameter: ethanol 8.20 ± 0.14 mm vs control 7.56 ± 0.11 mm [P = .0014]; volume intercept at 0 mm Hg (V0) of the LV end-diastolic pressure-volume relationship: ethanol 0.40 ± 0.03 mL vs control 0.31 ± 0.02 mL [P = .020]). However, there were no changes in systolic chamber function as indexed by LV endocardial fractional shortening or the slope of the LV systolic pressure-volume relationship (end systolic elastance). The percentage of myocardial apoptosis was correlated with the degree of LV dilation (% apoptosis vs LV EDD: r = 0.39; n = 38; P = .021; vs V0: r = 0.44; n = 19; P = .046). No differences in leukocyte or cardiac telomere length were noted between the ethanol and control groups. Furthermore, cardiac telomere length was not associated with indexes of LV dilation (LVEDD and V0) or cardiomyocyte apoptosis. CONCLUSIONS: Chronic ethanol-associated myocardial apoptosis and adverse remodeling occurs independently from changes in cardiac telomere length. Telomere shortening may not be a critical mechanism responsible for cardiomyocyte apoptosis and adverse cardiac remodeling.

Impact of gender and menopausal status on relationships between biological aging, as indexed by telomere length, and aortic stiffness.

BACKGROUND: Telomere length predicts cardiovascular disease (CVD) possibly through an impact of telomere attrition on aortic stiffness. Whether reduced biological aging and a lack of telomere length-aortic stiffness relationships in women contribute to the lower prevalence of CVD in women, prior to menopause, is uncertain. METHODS: We evaluated the relationship between telomere length and carotid-femoral (aortic) pulse wave velocity (PWV) in 580 randomly recruited participants of Black African descent (age = 44 ± 19 years; women: n = 361; premenopausal: n = 195). PWV was determined using carotid and femoral applanation tonometry (SphygmoCor). Relative leukocyte telomere length (T/S) was measured using quantitative real-time polymerase chain reaction assays. RESULTS: Men and women had similar T/S. T/S was inversely correlated with age (r = -0.14, P < 0.001) and this association was similar in all (r = -0.14, P < 0.01) and premenopausal (r = -0.17, P < 0.05) women as in men (r = -0.14, P < 0.05). An inverse relationship between T/S and PWV was noted both before (r = -0.20, P < 0.0001) and after (partial r = -0.14, P < 0.001) adjustments for confounders. No interaction between T/S and either sex or menopausal status was independently associated with PWV, and T/S was independently correlated with PWV in all (partial r = -0.14, P < 0.01) and premenopausal (partial r = -0.18, P < 0.05) women and in men (partial r = -0.15, P < 0.05). CONCLUSIONS: Gender and premenopausal status do not affect age-related decreases in T/S and associations between T/S and PWV. In participants of African descent in whom telomere length did not differ by gender, the impact of gender prior to menopause on CVD is unlikely to be attributed to differences in the effect of biological aging on aortic stiffness.

Intrafamilial aggregation and heritability of left ventricular geometric remodeling is independent of cardiac mass in families of African ancestry.

BACKGROUND: Whether left ventricular (LV) geometric remodeling, as indexed by relative wall thickness (RWT), aggregates in families and is inherited independent of LV mass (LVM) and additional confounders is uncertain. METHODS: We determined whether RWT as assessed from 2D targeted M-mode echocardiography shows intrafamilial aggregation and heritability independent of LVM in 181 nuclear families (73 spouse pairs, 403 parent-child pairs, and 177 sibling-sibling pairs) with 16 families including 3 generations from an urban developing community of black Africans. Intrafamilial aggregation and heritability estimates (S.A.G.E. software) were assessed independent of confounders, including central aortic systolic blood pressure (SBPc) (radial applanation tonometry and SphygmoCor software). RESULTS: Independent of confounders including SBPc, LV RWT was correlated in parent-child (r = 0.32, P < 0.0001) and sibling-sibling (r = 0.29, P < 0.0001), but not in spouse (r = 0.11, P = 0.33) pairs. The relationships between parent-child (r = 0.28, P < 0.0001) and sibling-sibling (r = 0.24, P < 0.001) pairs persisted with further adjustments for LVM or LVM indexed to height(2.7) (LVMI). Similarly, independent of confounders, LV RWT showed significant heritability (h(2) ± SEM = 0.56 ± 0.09, P < 0.0001) and this persisted with further adjustments for LVM (h(2) ± SEM = 0.48 ± 0.09, P < 0.0001) or LVMI (h(2) ± SEM = 0.49 ± 0.09, P < 0.0001). CONCLUSIONS: In a group of African ancestry, independent of LVM, LV geometric remodeling shows significant intrafamilial aggregation and heritability. Genetic factors may in-part determine the LV geometric remodeling process independent of the extent of cardiac hypertrophy.

Telomere length and adrenergic-induced left ventricular dilatation and systolic chamber dysfunction in rats.

PURPOSE: The mechanisms responsible for telomere shortening in heart failure are uncertain. We evaluated whether left ventricular (LV) dilatation and systolic chamber dysfunction produced by chronic ß-adrenergic receptor (ß-AR) activation is associated with leukocyte or cardiac telomere shortening. METHODS: Following 6 months of daily injections of the ß-AR agonist, isoproterenol (0.02 mg/kg/day) or the saline vehicle to rats, the extent of LV dilatation and LV systolic chamber dysfunction were determined using echocardiography and isolated perfused heart procedures, and relative telomere length of leukocyte (LTL) and cardiac (CTL) deoxyribonucleic acid were determined using a quantitative real-time polymerase chain reaction assay. RESULTS: ß-AR activation resulted in LV dilatation as indexed by increased LV diastolic diameters (9.2 ± 0.6 vs. 8.4 ± 0.9 mm, P = 0.01) and increased diastolic volume intercepts at zero pressure of the LV diastolic pressure-volume relationship (isolated, perfused heart preparation) (0.40 ± 0.06 vs. 0.37 ± 0.08 ml, P = 0.03). Moreover, ß-AR activation resulted in LV systolic chamber dysfunction as indexed by reductions in LV endocardial fractional shortening (0.40 ± 0.05 vs. 0.45 ± 0.06, P = 0.01) and the slope of the LV systolic pressure-volume relation (609 ± 176 vs. 901 ± 230, P = 0.01). Although LTL decreased with age in rats receiving either the ß-AR agonist or the saline vehicle (P < 0.05), neither CTL (-0.10 ± 0.14 vs. -0.15 ± 0.12, P = 0.3) nor LTL (-0.11 ± 0.19 vs. -0.15 ± 0.18, P = 0.5) were modified by ß-AR activation. CONCLUSION: In conclusion, chronic ß-AR activation sufficient to produce LV dilatation and systolic chamber dysfunction is not associated with alterations in leukocyte or cardiac telomere length. Telomere shortening in chronic heart failure is unlikely to be attributed to chronic ß-AR activation.

Isolated increases in in-office pressure account for a significant proportion of nurse-derived blood pressure-target organ relations.

AIMS: We determined the extent to which relationships between nurse-derived blood pressures (BPs) and cardiovascular damage may be attributed to isolated increases in in-office SBP independent of ambulatory BP. METHODS: In 750 participants from a community sample, nurse-derived office BP, ambulatory BP, carotid-femoral pulse wave velocity (PWV; applanation tonometry and SphygmoCor software; n=662), and left ventricular mass indexed to height (LVMI; echocardiography; n=463) were determined. RESULTS: Nurse-derived office BP was associated with organ changes independent of 24-h BP (LVMI; partial r=0.15, P<0.005, PWV; partial r=0.21, P<0.0001) and day BP. However, in both unadjusted (P<0.0001 for both) and multivariate adjusted models (including adjustments for 24-h BP; LVMI; partial r=0.14, P<0.01, PWV; partial r=0.21, P<0.0001), nurse office-day SBP (an index of isolated increases in in-office BP) was associated with target organ changes independent of ambulatory BP and additional confounders, with the highest quartile (≥15 mmHg) showing the most marked increases in LVMI (P<0.0005) and PWV (P<0.0001) as compared to the lowest quartile (<-5 mmHg). These relationships were reproduced in those with normotensive day BP values and the quantitative effect of nurse office-day BP on target organ changes was at least equivalent to that of ambulatory BP. CONCLUSION: Nurse-elicited isolated increases in in-office BP account for a significant proportion of the relationship between nurse-derived BP and target organ changes independent of ambulatory BP. Therefore, high quality nurse-derived BP measurements do not approximate the impact of BP effects per se on cardiovascular damage.

Relations between white coat effects and left ventricular mass index or arterial stiffness: role of nocturnal blood pressure dipping.

BACKGROUND: Whether independent relationships between white coat effects (office minus day (office-day blood pressure (BP))) and organ damage or arterial stiffness may be explained by associations with an attenuated nocturnal BP dipping, has not been determined. METHODS: In 750 participants from a sample of African ancestry, office and 24-hour BP, carotid-femoral pulse wave velocity (PWV) (applanation tonometry and SphygmoCor software) (n = 662), and left ventricular mass indexed to height(2.7) (LVMI) (echocardiography) (n = 463) were determined. RESULTS: Office-day systolic BP (SBP) was correlated with day minus night (day-night) SBP, percentage night divided by day (night/day) SBP, and night SBP (P < 0.0005), and these relationships persisted with adjustments for confounders, including day SBP (P < 0.005). With adjustments for 24-hour SBP and additional confounders, office-day SBP was associated with LVMI (P < 0.01) and PWV (P < 0.0001). With adjustments for day SBP and additional confounders, day-night SBP, percentage night/day SBP, and night SBP were related to PWV (P < 0.05) but not to LVMI (P > 0.44). The relationships between office-day SBP and LVMI or PWV persisted with adjustments for either day-night or percentage night/day SBP (LVMI: P = 0.01; PWV: P < 0.0001) or night SBP (LVMI: P < 0.01; PWV: P = 0.0001), and in product of coefficient mediation analysis with appropriate adjustments, neither indexes of nocturnal BP dipping nor nocturnal BP per se contributed toward the impact of office-day BP on LVMI or PWV (P > 0.09). CONCLUSIONS: In a group of African ancestry, although white coat effects are independently associated with an attenuated nocturnal decrease in SBP, neither decreased BP dipping nor nocturnal BP contribute toward the independent relationships between white coat effects and LVMI or arterial stiffness.

Insulin resistance and the relationship between urinary Na(+)/K(+) and ambulatory blood pressure in a community of African ancestry.

BACKGROUND: Although groups of African descent are particularly sensitive to blood pressure (BP) effects of salt intake, the role of obesity and insulin resistance in mediating this effect is uncertain. We determined whether obesity or insulin resistance is independently associated with urinary Na(+)/K(+)-BP relationships in a community sample of African ancestry. METHODS: We measured 24-hour urinary Na(+)/K(+), homeostasis model assessment of insulin resistance (HOMA-IR), and nurse-derived conventional and 24-hour ambulatory BP in 331 participants from a South African community sample of black African descent not receiving treatment for hypertension. RESULTS: With adjustments for diabetes mellitus and the individual terms, an interaction between waist circumference and urinary Na(+)/K(+) was associated with day diastolic BP (P < 0.05) and an interaction between log HOMA-IR and urinary Na(+)/K(+) was associated with 24-hour and day systolic (P < 0.05) and 24-hour, day, and night diastolic (P < 0.002; P < 0.001) BP. The multivariable-adjusted relationship between urinary Na(+)/K(+) and night diastolic BP increased across tertiles of HOMA-IR (tertile 1: ß-coefficient = -0.79 ± 0.47; tertile 2: ß-coefficient = 0.65 ± 0.35; tertile 3: ß-coefficient = 1.03 ± 0.46; P < 0.05 tertiles 3 and 2 vs. 1). The partial correlation coefficients for relationships between urinary Na(+)/K(+) and 24-hour (partial r = 0.19; P < 0.02), day (partial r = 0.17; P < 0.05), and night (partial r = 0.18; P < 0.02) diastolic BP in participants with log HOMA-IR greater than or equal to the median were greater than those for relationships between urinary Na(+)/K(+) and 24-hour (partial r = -0.08; P = 0.29), day (partial r = -0.10; P < 0.22), and night (partial r = -0.06; P = 0.40) diastolic BP in participants with log HOMA-IR less than the median (comparisons of r values: P < 0.05). CONCLUSIONS: Insulin resistance may modify the relationship between salt intake, indexed by urinary Na(+)/K(+), and ambulatory BP in groups of African descent.

Relationship between inappropriate left ventricular hypertrophy and ejection fraction independent of absolute or indexed mass in a community sample of black African ancestry.

AIM: We determined whether left ventricular hypertrophy (LVH) which exceeds that predicted from workload [inappropriate LV mass (LVM(inappr))] is associated with reduced left ventricle (LV) systolic chamber function independent of and more closely than absolute or indexed left ventricular mass (LVM). METHODS: In 626 randomly selected adult participants from a community sample of black Africans, using echocardiography we assessed absolute LVM, LVM indexed to height(2.7) (LVMI), LVM(inappr), LV wall stress, ejection fraction, and midwall fractional shortening (FSmid). LVM(inappr) was determined as percentage of observed/predicted LVM. Predicted LVM was calculated from a previously validated formula that incorporates stroke work. LVMI(inappr) more than 150% was considered to be inappropriate LVH. This threshold was identified from the upper 95% confidence interval for LVMI(inappr) determined in 140 healthy participants. RESULTS: A total of 21.7% of participants had LVH (LVMI > 51 g/m(2.7)) and 18.5% had inappropriate LVH. With adjustments for LV stress and other confounders there was a strong inverse relationship between LVM(inappr) and ejection fraction (partial r = -0.41, P < 0.0001), whereas only modest inverse relations between LVM or LVMI and ejection fraction were noted (partial r = -0.07 to -0.09, P < 0.05-0.09) (P < 0.0001, comparison of partial r values). The independent relationship between LVM(inappr) and ejection fraction persisted with further adjustments for LVM or LVMI (partial r = -0.52, P < 0.0001). LVM(inappr) and FSmid were similarly inversely related (P < 0.0001) and these relations were also stronger and independent of LVM or LVMI. CONCLUSION: Inappropriate LVH is strongly and inversely related to variations in ejection fraction independent of and more closely than LVM or LVMI in a community sample of black African ancestry. These data suggest that LVH is a compensatory response to workload, but when exceeding that predicted by workload, is associated with LV systolic chamber decompensation.

Relationship between average leucocyte telomere length and the presence or severity of idiopathic dilated cardiomyopathy in black Africans.

AIMS: A reduced average leucocyte telomere length is associated with ischaemic heart failure. Whether this relationship represents a cause or consequence of heart failure or is attributed to associated risk factors and coronary artery disease is uncertain. We evaluated if average leucocyte telomere length is associated with idiopathic dilated cardiomyopathy (IDC) or its severity. METHODS AND RESULTS: We compared average leucocyte telomere length in 223 patients with heart failure due to IDC and 227 healthy controls of black African ancestry. We also evaluated the relationship between average leucocyte telomere length and left ventricular ejection fraction (LVEF). LVEF was determined using echocardiography and radionuclide multiple-gated acquisition (MUGA) scan in patients with IDC. Relative leucocyte telomere length (T/S) was measured using a quantitative real-time polymerase chain reaction assay. Log T/S was negatively correlated with age in patients with IDC (P = 0.0007) and in controls (P = 0.030), and with alcohol consumption (P = 0.032) and regular smoking (P = 0.021) in patients with IDC. Log T/S did not differ between IDC and control groups either before (P = 0.11) or after (IDC = 0.071 ± 0.187, control = 0.071 ± 0.187, P = 0.99) adjustments for confounders. Log T/S was not associated with echocardiographic (P = 0.47) or MUGA (P = 0.99) LVEF or LV end-diastolic diameter (LVEDD) (P = 0.34) in patients with IDC. With adjustments for age, sex, alcohol consumption, and smoking, log T/S was similarly not associated with echocardiographic (P = 0.60) or MUGA (P = 0.91) LVEF or LVEDD (P = 0.53) in patients with IDC. CONCLUSIONS: Average relative leucocyte telomere length is not associated with IDC or its severity in groups of black African ancestry.

Relationship between urinary salt excretion and pulse pressure and central aortic hemodynamics independent of steady state pressure in the general population.

Although central pulse pressure (PPc) is strongly related to central mean arterial pressure (MAPc), PPc predicts cardiovascular outcomes beyond MAPc. Whether modifiable risk factors for hypertension contribute to PPc and its determinants, independent of MAPc, is uncertain. In 635 randomly recruited participants, we assessed the independent relationship between 24-hour urinary sodium (Na(+)) or potassium (K(+)) excretion and brachial artery PP (in office or 24-hour; n = 487), PPc, the forward (P1) and augmented (Paug) pressure wave components of PPc, central augmentation index, and determinants of central pressure waves, including aortic pulse wave velocity, effective reflecting distance, and reflective wave transit time. Central dynamics were determined using applanation tonometry of the carotid, femoral, and radial arteries. With adjustments for potential confounders, urinary Na(+)/K(+) was independently associated with in-office, central, and 24-hour PP, as well as Paug, P1, and central augmentation index (P<0.05 to P<0.005). With further adjustments for MAPc (or diastolic BP), urinary Na(+)/K(+) was independently associated with PPc, 24-hour PP, Paug, P1, and central augmentation index (P<0.05 to P = 0.005) but not with in-office PP, pulse wave velocity, effective reflecting distance, or reflective wave transit time. In conclusion, in a population of African ancestry, urinary salt excretion is independently related to central and 24-hour PP independent of MAPc or diastolic BP, effects that are attributed to increases in both P1 and Paug but not to pulse wave velocity. Hence, modifying salt intake could influence cardiovascular risk through effects on 24-hour and central PPs, as well as P1 and Paug, independent of steady-state pressure (MAP or diastolic BP) or pulse wave velocity.

Impact of aldosterone receptor blockade on the deleterious cardiac effects of adrenergic activation in hypertensive rats.

Although in hypertension beta-adrenoreceptor activation promotes the transition from cardiac hypertrophy to pump dysfunction, the use of beta-blockers is controversial. As adrenergic activation may mediate adverse effects on the heart through the renin-angiotensin-aldosterone system, we evaluated the effects of the aldosterone receptor blocker, spironolactone (SPIRO), on isoproterenol (ISO)-induced changes in left ventricular cavity size and pump function and the determinants thereof in spontaneously hypertensive rats (SHR). ISO administered for 4.5 months resulted in increases in left ventricular dimensions and a decrease in pump function in SHR but not in normotensive rats, changes that, without affecting blood pressure, were abolished by SPIRO. In SHR, 4-5 days of ISO increased myocardial matrix metalloproteinase-2 activity, which was associated with matrix metalloproteinase-2 but not tissue inhibitor of MMP expression; persisted at 4.5 months; and was prevented by SPIRO. Moreover, after 4.5 months, ISO increased non-cross-linked myocardial collagen concentrations in SHR, which was abolished by SPIRO. Although after 4.5 months, ISO was not associated with increased cardiomyocyte apoptosis, an early (4-5 days) ISO-induced apoptotic effect was noted, which was prevented by SPIRO. Hence, aldosterone receptor blockade may be sufficient to prevent those adverse effects of beta-adrenoreceptor activation responsible for the transition from concentric cardiac hypertrophy to pump dysfunction in hypertension.

Gene variants of the renin-angiotensin system and hypertension: from a trough of disillusionment to a welcome phase of enlightenment?

There is substantial evidence to suggest that BP (blood pressure) is an inherited trait. The introduction of gene technologies in the late 1980s generated a sharp phase of over-inflated prospects for polygenic traits such as hypertension. Not unexpectedly, the identification of the responsible loci in human populations has nevertheless proved to be a considerable challenge. Common variants of the RAS (renin-angiotensin system) genes, including of ACE (angiotensin-converting enzyme) and AGT (angiotensinogen) were some of the first shown to be associated with BP. Presently, ACE and AGT are the only gene variants with functional relevance, where linkage studies showing relationships with hypertension have been reproduced in some studies and where large population-based and prospective studies have demonstrated these genes to be predictors of hypertension or BP. Nevertheless, a lack of reproducibility in other linkage and association studies has generated scepticism that only a concerted effort to attempt to explain will rectify. Without these explanations, it is unlikely that this knowledge will translate into the clinical arena. In the present review, we show that many of the previous concerns in the field have been addressed, but we also argue that a considerable amount of careful thought is still required to achieve enlightenment with respect to the role of RAS genes in hypertension. We discuss whether the previously identified problems of poor study design have been completely addressed with regards to the impact of ACE and AGT genes on BP. In the context of RAS genes, we also question whether the significance of 'incomplete penetrance' through associated environmental, phenotypic or physiological effects has been duly accounted for; whether appropriate consideration has been given to epistatic interactions between genes; and whether future RAS gene studies should consider variation across the gene by evaluating 'haplotypes'.

Contribution of central and general adiposity to abnormal left ventricular diastolic function in a community sample with a high prevalence of obesity.

The relative independent contribution of excess adiposity, as indexed by measures of central, general, or peripheral adiposity, toward abnormal cardiac diastolic chamber function at a community level is unclear. In 377 randomly selected participants >16 years old from a community sample with a high prevalence of excess adiposity ( approximately 25% overweight and approximately 43% obese), we assessed the independent contribution of the indexes of adiposity to the variation in early-to-late (atrial) transmitral velocity (E/A). After adjustments for a number of confounders, including age, gender, pulse rate, conventional diastolic (or systolic) blood pressure, antihypertensive treatment, left ventricular mass index, and the presence of diabetes mellitus or a hemoglobin A1c level >6.1%; waist circumference was an independent predictor of a reduced E/A (p = 0.0038). Body mass index (p = 0.07), waist-to-hip ratio (p = 0.23), and skinfold thickness (p = 0.37) were not independently associated with E/A, whereas waist circumference was independently associated with E/A, even after adjustments for other adiposity indexes, including body mass index (p <0.05 to 0.005). In contrast to the effects on diastolic function, the waist circumference did not correlate with the left ventricular ejection fraction (p = 0.23). The independent relation between the waist circumference and E/A (standardized beta coefficient -0.14 +/- 0.05, p = 0.0038) was second only to age (standardized beta coefficient -0.57 +/- 0.05, p <0.0001) and similar to blood pressure (standardized beta coefficient -0.11 +/- 0.04, p = 0.0075) in the magnitude of the independent effect on E/A. The inclusion of the relative wall thickness rather than the left ventricular mass index in the regression equation produced similar outcomes. The exclusion of the left ventricular mass index and relative wall thickness from the regression equations or the inclusion of carotid-femoral pulse wave velocity or 24-hour blood pressure as confounders failed to modify the relation between waist circumference and E/A. In conclusion, the waist circumference was second only to age in the impact on an independent association with E/A in a population sample with a high prevalence of excess adiposity. This effect was not accounted for by left ventricular hypertrophy or remodeling, the 24-hour blood pressure, or arterial stiffness.

Nurse-recorded auscultatory blood pressure at a single visit predicts target organ changes as well as ambulatory blood pressure.

AIM: To determine whether high-quality nurse-recorded auscultatory blood pressure (BP) values obtained at a single visit predict cardiovascular target organ changes as closely as ambulatory BP measurements. METHODS: In a randomly selected population sample (n = 458, 21% receiving antihypertensive treatment; approximately 40% hypertensive), we compared high-quality single visit nurse-recorded auscultatory BP values to same-day 24-h ambulatory BP in their ability to predict multiple target organ changes [left ventricular mass index (LVMI), left ventricle (LV) mean wall thickness (MWT), early-to-late transmitral velocity ratios (E/A), (echocardiography); log of urinary albumin-to-creatinine ratios (log ACR) (24-h urine samples); large artery dysfunction [carotid-femoral pulse wave velocity (PWV) and central augmentation index (Alc) (applanation tonometry)]. RESULTS: Nurse-recorded systolic BP (SBP) measurements obtained at a single visit were as closely associated with LVMI (r = 0.44), LV MWT (r = 0.44), E/A (r = -0.55), log ACR (r = 0.20), PWV (r = 0.62) and AIc (r = 0.41) (P < 0.0001 for all relations) as was 24-h SBP (LVMI; r = 0.33, LV MWT; r = 0.37, E/A; r = -0.35, log ACR; r = 0.24, PWV; r = 0.41, and AIc; r = 0.18, P < 0.001 for all relations) and either day or night SBP. On multivariate regression analysis with both nurse-recorded SBP and 24-h SBP in the same model, nurse-recorded SBP was independently associated with LVMI (P = 0.006), LV MWT (P = 0.03), E/A (P < 0.02), PWV (P < 0.0001) and AIc (P = 0.0002), and 24-h SBP was independently and positively associated with log ACR (P < 0.005), and PWV (P = 0.01). CONCLUSION: One or more, high-quality single visit nurse-recorded auscultatory BP measurements may be equally as effective as ambulatory BP in predicting target organ damage in a population sample of African ancestry.