John C. Stevenson

17β-Oestradiol enhances release of matrix metalloproteinase-2 from human vascular smooth muscle cells

Vascular remodelling occurs during all stages of atherosclerotic progression. Anti-atherosclerotic drugs may function by restoring regulation of the processes involved in remodelling of the extracellular matrix. A key group of enzymes involved . in these processes are the matrix metalloproteinases MMPs . Oestrogens have been demonstrated to possess anti-athero- sclerotic properties at low concentrations while being associated with lesion formation at high concentrations. We examined . the effect of 17b-oestradiol on MMP-2 expression in human coronary artery CAVSMC and umbilical artery vascular . smooth muscle cells UAVSMC . MMP-2 expression was measured by chemiluminescent immunoblotting and quantified by laser densitometry. pro-MMP-2 was secreted by VSMCs and increasing levels of 17b-oestradiol, from physiological through supraphysiological, were associated with significant dose-dependent increases in MMP-2 levels in culture media. This effect was dependent on de novo protein synthesis and could be antagonised by the oestrogen receptor antagonist, tamoxifen, and the specific receptor antagonist ICI 182,780. 17b-Oestradiol appears to be a specific stimulator of MMP-2 release from human vascular cells. The concentration dependence of this effect suggests a basis for the differential effects of low and high oestrogen levels on vascular integrity. q 1998 Elsevier Science B.V.

Is there a menopausal metabolic syndrome

Estradiol-17 beta has beneficial effects on a range of metabolic risk factors for coronary heart disease and the decline in estrogen concentrations at the menopause would be expected to have adverse effects. Review of the literature on effects of the menopause and of estradiol-17 beta provides evidence for the following changes occurring at or after the menopause: increased total cholesterol and triglycerides; decreased high density lipoprotein (HDL) and HDL subfraction 2; increased low density lipoprotein, particularly in the small, dense subfraction; increased lipoprotein (a); increased insulin resistance; decreased insulin secretion; decreased insulin elimination; increased android fat distribution; impaired vascular function; increased factor VII and fibrinogen, and reduced sex-hormone binding globulin. Many of these changes will themselves have adverse effects on other metabolic risk factors. This complex of inter-correlated adverse changes in metabolic risk factors justifies identification of a distinct menopausal metabolic syndrome which originates in estrogen deficiency and which could contribute to the increased risk of coronary heart disease seen in postmenopausal women. Estrogen replacement can diminish the expression of this syndrome.

Hormone replacement therapy with dydrogesterone and 17β‐oestradiol: effects on serum lipoproteins and glucose tolerance during 24 month follow up

Objective To assess serum lipid and lipoprotein concentrations and oral glucose tolerance in postmenopausal women treated with 17β‐oestradiol (2 mg/day) and cyclical dydrogesterone (10 mg/day for 14 days per 28 day cycle).

Associations of smoking, alcohol and physical activity with risk factors for coronary heart disease and diabetes in the first follow‐up cohort of the Heart Disease and Diabetes Risk Indicators in a Screened Cohort study (HDDRISC‐1)

Godsland IF, Levya F, Walton C, Worthington M, Stevenson JC (Imperial College School of Medicine, London, UK). Associations of smoking, alcohol and physical activity with risk factors for coronary heart disease and diabetes in the first follow‐up cohort of the Heart Disease and Diabetes Risk Indicators in a Screened Cohort study. J Intern Med 1998; 244: 33–41.

Relation between serum uric acid and lower limb blood flow in patients with chronic heart failure.

OBJECTIVE: To determine whether lower limb blood flow is related to serum uric acid concentrations in patients with chronic heart failure, taking into account the hyperuricaemic effects of diuretic treatment and insulin resistance. DESIGN: Lower limb blood flow was measured at rest and after maximum exercise followed by a five minute period of ischaemia (maximum blood flow) using strain gauge venous occlusion plethysmography. All patients underwent a metabolic assessment, which included an intravenous glucose tolerance test (IVGTT)-to obtain an index of insulin sensitivity- and measurement of serum uric acid. SETTING: University and hospital departments specialising in cardiology and metabolic medicine. SUBJECTS: 22 patients with chronic heart failure. RESULTS: Mean (SEM) resting and maximum blood flow values were 2.87 (0.23) and 24.00 (1.83) ml/100 ml/min, respectively. Patients in the upper tertile of serum uric acid had lower maximum blood flow than those in the lowest tertile (15.6 (2.2) v 31.0 (2.1) ml/100 ml/min, P = 0.003). Serum uric acid correlated with maximum blood flow (r = -0.86, P < 0.001), but not with resting blood flow. In stepwise regression analysis, uric acid emerged as the only predictor of maximum blood flow (standardised coefficient = -0.83 (P < 0.001), R2 = 0.68 (P < 0.001)), independently of diuretic dose, age, body mass index, plasma creatinine, fasting and IVGTT glucose and insulin, insulin sensitivity, maximum oxygen uptake and exercise time during the treadmill exercise test, and alcohol intake. CONCLUSIONS: There is a strong inverse relation between serum uric acid concentrations and maximum leg blood flow in patients with chronic heart failure. Further studies are needed to determine whether serum uric acid can be used as an index of vascular function in cardiovascular diseases.

The Prevention of Osteoporosis Using Sequential Low-Dose Hormone Replacement Therapy with Estradiol-17β and Dydrogesterone

Abstract: Low-dose hormone replacement therapy (HRT) in postmenopausal women may produce fewer side-effects but its efficacy in the prevention of bone loss and osteoporosis is not established. To address this we compared the effect of 1 mg estradiol-17β with a 2 mg dose, in combination with cyclical dydrogesterone, in the prevention of postmenopausal bone loss. We conducted a multicenter double-masked prospective randomized, placebo-controlled study in 595 apparently healthy postmenopausal women randomized to either placebo, or continuous oral estradiol-17β 1 mg or 2 mg with sequential dydrogesterone for 2 years. The primary endpoint was the percentage change from baseline in bone mineral density (BMD) in the lumbar spine (LS) and femoral neck (FN) of actively treated groups compared with placebo. Women taking either 1 mg or 2 mg estradiol-17β showed a significant increase in BMD of the LS (mean ± SD, 5.2 ± 3.8% and 6.7 ± 4.0% respectively, both p <0.001) whilst BMD in the placebo group decreased (–1.9 ± 4.0%). Increases were also observed in FN BMD in both treated groups (2.7 ± 4.2% and 2.5 ± 5.2% respectively, both p <0.001) in contrast to the placebo group (–1.8 ± 4.8%). The oldest women showed the greatest treatment response. One milligram estradiol-17β in combination with dydrogesterone is effective in conserving LS and proximal femur bone mass, both of which are clinically important sites of osteoporotic fracture, and is as effective as 2 mg in preventing FN bone. The lower dose of estradiol-17β is a particularly suitable treatment for osteoporosis management in older women since it should minimize side-effects and improve the acceptability of HRT.

Factors of the Metabolic Syndrome: Baseline Interrelationships in the First Follow-up Cohort of the HDDRISC Study (HDDRISC-1)

Syndromes of risk factor disturbance may contribute to the development of coronary heart disease and non-insulin-dependent diabetes mellitus, but their definition and quantification remain problematic. Using factor analysis, constellations of risk factor variables that could indicate distinct syndromes of metabolic disturbance were explored in the baseline data of the first follow-up cohort of 742 men from the Heart Disease and Diabetes Risk Indicators in a Screened Cohort (HDDRISC) study. The primary analysis considered 16 intercorrelated variables measured in more than 90% of cohort participants. A missing-values estimation routine was used to ensure inclusion of all participants in the analysis. Subanalyses were undertaken, including a repeat of the primary analysis on the 522 individuals who had received measurement of HDL cholesterol, an oblique rather than orthogonal factor rotation procedure performed on primary and HDL subset analyses, a repeat of these two primary and HDL subset analyses using only those participants with complete measurements, and a repeat of these six analyses including only the seven variables conventionally associated with the metabolic syndrome. The principal factor that emerged in all analyses undertaken comprised oral glucose tolerance test insulin and glucose response, serum uric acid, and body mass index. Fasting serum triglyceride concentration was included in this factor in 11 of the 12 analyses undertaken, fasting plasma insulin in 8, fasting plasma glucose in 5, and mean arterial pressure in 3. HDL cholesterol factored in isolation from insulin in all analyses undertaken. These findings provide strong support for a core metabolic cluster, which is unlikely to include blood pressure and does not include HDL. The factor scores relating to this cluster will provide a means of assessing its quantitative importance in prospective analysis of the development of CHD and diabetes in this cohort.

Randomized trial of effect of transdermal continuous combined hormone replacement therapy on cardiovascular risk markers.

Whether hormone replacement therapy (HRT) is beneficial for coronary heart disease (CHD) is controversial. We hypothesized that continuous combined transdermal HRT may have benefits on CHD risk markers without the potential adverse effects seen with certain other HRT regimens. Sixty apparently healthy postmenopausal women, aged 40–65 years, entered a prospective, double‐blind, randomized, placebo‐controlled clinical trial; 55 women completed the 6‐month study. Women received either transdermal oestradiol 17β 0·05 mg and norethisterone acetate 0·125 mg daily, or identical placebo. Circulating markers of vascular function and remodelling, forearm blood flow, lipids and lipoproteins, glucose and insulin, and haemostatic safety parameters were measured at baseline and after treatment. Compared with placebo after 6 months, HRT administration resulted in decreased E‐selectin (P < 0·01), and angiotensin‐converting‐enzyme (ACE; P = 0·05). Cholesterol (P < 0·05), low‐density lipoproteins (LDL; P < 0·05), high‐density lipoprotein3 (HDL3; P < 0·05) and apolipoproteins AII (P < 0·05) and B (P < 0·05), and fasting insulin (P < 0·05) also decreased in the HRT group. Factor VII coagulation activity decreased (P < 0·01) and plasminogen activator inhibitor‐1 and fibrin D‐dimer increased (P < 0·05) in the HRT group, whilst prothrombin fragment 1 + 2 (P < 0·05) decreased, more so in the placebo group. There were no changes in matrix metalloproteinase (MMP)‐2, or in LDL particle size. This transdermal HRT had beneficial effects on vascular function and CHD risk markers.

The effect of menopause on serum uric acid levels in non-obese healthy women

Elevated circulating serum uric acid concentrations may be linked with an increased risk of coronary heart disease (CHD). We measured serum uric acid levels in 50 premenopausal and 88 postmenopausal non-obese white women who underwent an intravenous glucose tolerance test. The uric acid concentration was significantly higher in postmenopausal versus premenopausal women. Adjustment of the data to take into account a number of confounding variables, including the age and body mass index (BMI), revealed a highly significant independent difference between the groups. BMI was found to be a significant independent predictor of the uric acid concentration, but this was confined to premenopausal women. Postmenopausal women were found to be more insulin-resistant, and significant correlations were observed between components of the insulin resistance syndrome and uric acid in both groups. We conclude that increases in serum acid in postmenopausal women may result from changes in metabolism as a consequence of the menopause, and may be associated with the increased risk of CHD seen in these women.

The glycolytic pathway to coronary heart disease: A hypothesis

Coronary heart disease (CHD) is pathogenetically linked to numerous metabolic disturbances. These are inextricably interrelated, constituting identifiable clusters or syndromes of cardiovascular risk. Prominent among these is the insulin resistance syndrome, whose components, including hyperuricemia, have all been linked to CHD pathogenesis. Many mechanisms have been put forward to account for the emergence of this syndrome, but none offer a satisfactory explanation for the involvement of hyperuricemia. Possible explanations relate to the observation of glycolytic disturbances in insulin-resistant and hyperuricemic states. This might be expected from the fact that uric acid production is linked to glycolysis and that glycolysis is controlled by insulin. Phosphoribosylpyrophosphate (PPRP) is an important metabolite in this respect. Its availability depends on ribose-5-phosphate (R-5-P), the production of which is governed by glycolytic flux. Diversion of glycolytic intermediates toward R-5-P, PPRP, and uric acid will follow if there is diminished activity of glyceraldehyde-3-phosphate dehydrogenase (GA3PDH), which is regulated by insulin. Serum triglyceride concentrations may also increase, as might be expected from accumulation of glycerol-3-phosphate. Thus, intrinsic defects in GA3PDH and a loss of its responsiveness to insulin, by causing accumulation of glycolytic intermediates, may explain the association between insulin resistance, hyperuricemia, and hypertriglyceridemia. This scenario raises the possibility that disturbances of a single glycolytic enzyme may be pivotal in the modulation of metabolic risk factors for CHD.