Artificial ultraviolet whole-body radiation does not modify serum lipoprotein, plasma fibrinogen, plasminogen or antithrombin III concentrations in post-myocardial infarction patients.

The relationship of ischaemic heart disease (IHD) to seasonal and latitude variation has prompted speculation that exposure to the ultraviolet component of solar radiation may reduce IHD risk. This hypothesis was partially tested by exposing 14 post-myocardial infarction patients to a 6 week course of artificial whole-body ultraviolet radiation (UVR). Serum lipoprotein and plasma coagulation factor concentrations were measured before and after the course of UVR. Results were compared with similar measurements from a placebo-controlled group of 13 post-myocardial patients. Despite a more than two-fold rise in mean serum 25-OHD, serum lipoprotein and plasma fibrinogen, antithrombin III and plasminogen concentrations did not change significantly in the UVR group. Significant but minor change in prothrombin time and thrombin time in the placebo group appear unlikely to be of biological significance. Seasonal and latitude variation in these IHD risk factors appear unrelated to corresponding variation in solar UVR exposure.

Effects of postmenopausal hormone replacement therapy on lipoproteins including lipoprotein(a) and LDL subfractions.

The purpose of this study was to examine the effects on lipoprotein risk markers for CHD of oestradiol given alone and in combination with the androgenic progestogen, norethisterone. Eighty postmenopausal women were randomly allocated to receive oestradiol (2 mg/day) alone or with continuous norethisterone (1 mg/day). Serum lipoprotein levels, including lipoprotein(a), were monitored during 12 months on treatment in all the women, and in a sub-set of 32 patients cholesterol was measured in the two major density subfractions of LDL. Oestradiol caused a transient rise in triglycerides, a small decrease in LDL cholesterol (significant only at 3 and 6 months, P < 0.05) and a consistent significant increase in HDL cholesterol (16%, P < 0.01). There was a downward trend in lipoprotein(a) levels which did not achieve statistical significance. The combined preparation caused significant, sustained decreases in triglycerides (31%, P < 0.01), total cholesterol (15%, P < 0.001), VLDL (42%, P < 0.01), LDL (9%, P < 0.05) and HDL (11%, P < 0.001). Lipoprotein(a) was also reduced (39%, P < 0.05). In the sub-set of patients in which LDL subfractions were measured, the reduction in LDL induced by oestradiol monotherapy was significant only at the 3-month visit (6%, P < 0.05). This was due to a decrease in the 'light' (1.025 < d < 1.044 g/ml) subfraction (10%, P < 0.05) and resulted in an apparent shift in subfraction distribution towards the 'heavy' (1.044 < d < 1.060 g/ml) subfraction, although there was no absolute increase in the latter. None of these changes was statistically significant at 12 months. Oestradiol/norethisterone caused sustained decreases in both 'light' (15%, P < 0.05) and 'heavy' (29%, P < 0.05) subfractions, with no significant change in the relative amounts. The changes in 'light' and 'heavy' LDL in this group were highly correlated with changes in triglyceride levels (r = -0.57, P < 0.05 and r = 0.82, P < 0.01 respectively). Therefore, at the end of 1 year's treatment with unopposed oestradiol the only statistically significant change was an increase in HDL cholesterol. Addition of norethisterone to the preparation reversed this potentially beneficial change, but favourably influenced triglycerides, VLDL, LDL subfraction profile and lipoprotein(a), which may counteract the adverse effect on HDL.

Effects of tibolone on serum lipoprotein and apolipoprotein levels compared with a cyclical estrogen/progestogen regimen.

OBJECTIVE: The purpose of the study was to examine the effects of tibolone, a synthetic steroid that alleviates climacteric symptoms and prevents bone loss without inducing monthly bleeds, on lipoprotein cardiovascular risk markers and to compare the effects with those of a standard combined estrogen/progestogen preparation. DESIGN: Ninety-seven postmenopausal women were randomly allocated to receive either tibolone 2.5 mg/day or conjugated equine estrogens 0.625 mg/day with norgestrel 0.15 mg/day for 12 of each 28 days. Fasting serum levels of lipids, lipoproteins, and apolipoproteins (Apo) were monitored during 18 months of treatment. Women on the cyclical preparation had levels determined during both estrogen-only and combined phases. RESULTS: Tibolone caused reductions in triglycerides (33%, p < 0.001), very low density lipoprotein (VLDL) cholesterol (43%, p < 0.001), and high density lipoprotein (HDL) cholesterol (18%, p < 0.001). The HDL2/HDL3 ratio fell by 22% (p < 0.001). Levels of Apo AI and AII were reduced by 18 and 8%, respectively (p < 0.001). The combined preparation caused reductions in VLDL cholesterol (23%, p < 0.001) and low density lipoprotein cholesterol (15%, p < 0.001). There were small reductions in HDL3 cholesterol and in Apo AII and Apo B. All parameters, except for Apo AII and Apo B and lipoprotein (a) [Lp (a)], showed cyclical changes. Lp (a) levels were reduced significantly by both treatments. CONCLUSIONS: The cyclical preparation had potentially beneficial effects on LP risk markers. The reduction in HDL induced by tibolone constitutes a potentially adverse change, which may be offset by the substantial falls in triglycerides, VLDL cholesterol, and Lp (a).

Chemical and kinetic study of the lipoproteins in abetalipoproteinaemic plasma.

Abetalipoproteinaemic plasma lipoproteins were fractionated by molecular sieve chromatography into two classes on the basis of size. Each class had the same chemical and immunochemical composition and seemed to be interconvertible in vitro, presumably as a result of aggregation/disaggregation. The low levels of circulating apolipoprotein A-I found in abetalipoproteinaemic subjects have been shown by kinetic analysis to result from reduced synthesis of the apoprotein and not from increased catabolism or redistribution between vascular and extravascular compartments.

Metabolism of apolipoprotein A-I in healthy young adults.

The metabolism of 125I-labeled apolipoprotein A-I bound to high-density lipoproteins by an in vitro transfer procedure was studied in 10 healthy young adults (5 males and 5 females). Both sexes handled the labeled apolipoprotein similarly, and no statistically significant differences were found in the derived kinetic data. The mean (+/- 1 SD) plasma apolipoprotein A-I concentrations (males, 105 +/- 19 mg/dl; females, 111 +/- 13.8 mg/dl) and half-lives (males, 4.46 +/- 0.45 days; females, 4.64 +/- 0.70 days) were similar, as were the fractional rates of catabolism (FCR) of the apoprotein derived from the above data (FCR in males, 27% of intravascular pool/day; FCR in females, 25% of intravascular pool/day). The absolute catabolic rate of the apoprotein, equivalent under steady-state conditions to the synthetic rate, was 12.1 +/- 1.6 mg/kg/day in males and 11.9 +/- 2.4 mg/kg/day in females.

Effects of ranitidine and cimetidine on plasma lipoproteins in healthy subjects.

Serum lipoproteins were monitored in 24 healthy subjects receiving either ranitidine or cimetidine for four weeks. Ranitidine produced a significant (P less than .05) reduction in high-density lipoprotein (HDL)-cholesterol in both men and women. Cimetidine caused a nonsignificant increase in HDL-cholesterol and a reduction in LDL-cholesterol that was significant (P less than .05) only in women. As these drugs had opposite effects on HDL-cholesterol levels, the mechanism of action is unlikely to be medicated by H2-receptor blockade.

Plasma apolipoprotein A levels in healthy human adults.

The apolipoprotein A concentration in the plasma of ten healthy human subjects was measured immunologically on three occasions at monthly intervals and the following results recorded. 1. There was no difference between fasting and non-fasting apoprotein A concentrations. 2. Apoliportein A levels were higher in females than in males (p less than 0.001). 3. The correlation coefficient calculated for high density lipoprotein cholesterol and apolipoprotein A was 0.62. 4. The apoprotein values varied widely between subjects and ther were considerable concentration differences from month to month in the plasma of each individual.

Lipoprotein and apoprotein levels in postmenopausal women during treatment with norethisterone.

Lipoprotein and apolipoprotein levels were monitored in 21 postmenopausal women during 6 months' treatment with norethisterone. There was no significant change in low density lipoprotein (LDL) cholesterol but apoprotein B levels rose significantly (p less than 0.001) thus increasing the apoprotein:cholesterol ratio in LDL. High density lipoprotein (HDL) cholesterol levels decreased significantly (p less than 0.001) in the first two months and did not change significantly thereafter. The HDL2 subfraction was reduced to a greater extent than the HDL3 subfraction. Apoprotein AI and AII levels were both reduced as was the apoprotein AI:AII ratio. The ratios of apoproteins AI and AII to HDL cholesterol were increased. We conclude that norethisterone has an adverse effect on the important risk factors for cardiovascular disease.

A long-term study of the effects of norethisterone on lipoprotein metabolism in menopausal women.

Long-term effects of the androgenic progestogen norethisterone on lipoprotein metabolism were studied by measuring lipoprotein concentrations in 21 women during one year on treatment for the relief of climacteric symptoms. There were significant reductions in total serum triglyceride (p less than 0.01), very low density lipoprotein (VLDL) cholesterol (p less than 0.01) and high density lipoprotein (HDL) cholesterol (p less than 0.001) after two months on treatment, all of which were still in evidence after one year. Low density lipoprotein (LDL) cholesterol levels climbed gradually becoming significantly higher than baseline after one year on treatment (p less than 0.01). Comparison of cholesterol concentrations in HDL subfractions in the one year treated subjects with those in a control group of untreated subjects suggests that the fall in HDL cholesterol is due to reductions in both the HDL2 and HDL3 fractions. We conclude that norethisterone adversely affects the important lipoprotein risk factors for coronary heart disease.

Changes in the bone and liver isoenzymes of alkaline phosphatase in postmenopausal women being treated with norethisterone.

The effects of norethisterone therapy on alkaline phosphatase isoenzyme activities were studied in a group of postmenopausal women. There was a significant fall in total alkaline phosphatase activity after 8 wk which was still in evidence after 24 wk. Both bone and liver alkaline phosphatase isoenzyme activities were decreased during the first 16 wk on treatment, but after 24 wk only the bone phosphatase activity was significantly lower than the pretreatment level. The other biochemical indices of bone metabolism and liver function were also measured during the study. The results indicate that bone specific alkaline phosphatase activity is a more sensitive index of bone activity than total alkaline phosphatase and that monitoring of total activity may in some instances be misleading.

Measurement of capillary cholesterol as an aid to the management of hypertensive patients with hyperlipidaemia--an assessment of the Reflotron.

The Reflotron dry chemistry method of capillary cholesterol measurement has been widely adopted as a rapid means of population screening. We attempted to use it to monitor changes in cholesterol in a trial of intensive dietary intervention in hyperlipidaemic hypertensives. Four hundred and eighty-nine capillary cholesterol levels measured by the Reflotron were compared with levels for venous samples obtained simultaneously and assayed by the Biochemistry Department using conventional laboratory methods. The mean difference between them was 0.3 mmol/l +/- 0.8 (SD). Approximately one-third of the variability in the difference between the two methods was explained by the variables, Reflotron machine used and time (R2 = 54%, adjusted R2 = 34%). We conclude that the Reflotron is not suitable for accurate assessment of the modest changes in cholesterol which occur in individual patients during dietary intervention.

Effects of nicardipine on the metabolic responses to food and exercise.

In a placebo-controlled, double-blind, randomised, cross-over study the metabolic and hormonal responses to standard food and exercise challenge have been evaluated in seven patients with mild to moderate essential hypertension after treatment with nicardipine 30 mg three times daily for four weeks. There were no significant differences between nicardipine and placebo for any of the measured hormonal and metabolic indices following food or exercise. These results indicate that nicardipine has no clinically important effects on serum lipids or hormonal or metabolic responses to food and exercise.

Combined lipid-lowering and antihypertensive treatment as part of a strategy of multiple risk factor intervention.

Thirty-six patients with treated mild to moderate hypertension and hypercholesterolaemia (greater than 6.5 mmol/l) entered a 12 week study to evaluate the efficacy and patient tolerability of combined lipid-lowering and antihypertensive treatment as part of a strategy of multiple risk factor intervention. The principal effects on the plasma lipid profiles were significant reductions of 30-40% in total and LDL cholesterol. These reductions were achieved without loss of blood pressure control. There was no significant impact on HDL cholesterol or on lipoprotein Lp(a). These preliminary results suggest that substantial reductions in total and LDL cholesterol can be achieved without compromising blood pressure control which remained satisfactory at 144/82 supine and 143/80 mmHg standing. Furthermore, these changes were achieved without any problems of patient tolerability or interference with patient compliance with drug treatment. Overall, therefore, substantial reductions in CHD risk can be achieved with an acceptable combination of lipid lowering and antihypertensive treatments.

Short-term changes in lipoproteins and apoproteins during cyclical oestrogen-progestogen replacement therapy.

Lipoproteins and apoproteins were measured weekly in a group of 18 post-menopausal women treated with a cyclical hormone replacement regimen comprising 28 days on conjugated equine oestrogens (0.625 mg/day) with the addition of norgestrel (0.15 mg/day) for the last 12 days of the cycle. There were no significant changes in total triglyceride, very low-density-lipoprotein (VLDL) cholesterol or high-density-lipoprotein (HDL) cholesterol levels. Low-density lipoprotein (LDL) and total cholesterol levels fell, the differences being significant after two weeks. The LDL/HDL cholesterol ratio also fell significantly over 1 week of treatment. There were no significant changes in either HDL2 or HDL3 cholesterol. The HDL2/HDL3 cholesterol ratio did, however, alter significantly, increasing during the oestrogen-only phase. Apart from this ratio, none of the parameters measured showed any significant differences as between the oestrogen-only phases and the oestrogen/norgestrel phases. There were no significant changes from baseline values in the levels of apoproteins AI, AII or B. The apoprotein AI/AII ratio was significantly increased, the levels being higher during the oestrogen phase of the cycle. There was no significant change in the apoprotein B/AI ratio. The apoprotein B/LDL cholesterol ratio showed a statistically significant increase after 4 weeks. There was no evidence of any cyclical changes. We conclude that the results of this study are generally favourable with regard to coronary heart disease risk but that the change in the apoprotein B/LDL ratio merits further investigation.

A comparison of the effects of lipoproteins of two progestogens used during cyclical hormone replacement therapy.

Lipoprotein levels were measured in 11 women who had been treated with 0.625 mg/day conjugated equine oestrogens with the addition of 0.15 mg/day DL-norgestrel for the last 12 days of each 28 day cycle for 48 wk. Treatment was then changed to an identical oestrogen regimen with dydrogesterone, 10 mg/day, as progestogen and monitoring continued for a further 24 wk. The oestrogen plus norgestrel regimen caused a significant reduction in low density lipoprotein (LDL) cholesterol levels. During the 24 wk after the change of therapy, levels of high density lipoprotein (HDL) increased significantly due to an increase in the HDL2 fraction and there was an upward trend in LDL cholesterol which did not attain statistical significance. We conclude that, when used in combination with conjugated equine oestrogens, changing from norgestrel, 0.15 mg/day, to dydrogesterone, 10 mg/day, does not lead to any significant improvement in lipoprotein profile.

Effects of tibolone on lipoprotein(a) and HDL subfractions.

OBJECTIVE: To determine the effects of tibolone, a synthetic steroid used to alleviate climacteric symptoms and prevent osteoporosis, on lipoprotein metabolism, with particular reference to lipoprotein(a) levels and HDL subfraction profiles. DESIGN: Thirty nine postmenopausal women were treated with tibolone (Livial) 2.5 mg/day for 6 months and fasting serum lipoprotein levels were estimated at 0, 2, 4 and 6 months. RESULTS: Lipoprotein(a) levels were reduced significantly over the 6 months from a median level of 245 (range < 60-780) mg/l to 152 (range < 60-530) mg/l, a reduction of 39% in the median level. A decrease was observed in approximately two thirds of the women. Reductions were noted in all 6 subjects whose pretreatment levels were high, although concentrations remained at a level associated with increased risk in all but one. There were significant decreases in triglycerides and VLDL cholesterol and no significant change in LDL cholesterol. There was a significant reduction of 18% in HDL cholesterol and a 26% reduction in the HDL2-HDL3 ratio. CONCLUSION: The reduction in lipoprotein(a) levels may have a beneficial effect on cardiovascular risk, which could go some way towards balancing the potentially adverse effect on the cardiovascular system caused by the reduction in HDL cholesterol.

Effects of conjugated equine oestrogens with and without the addition of cyclical norgestrel on serum and urine electrolytes, and the biochemical indices of bone metabolism and liver function.

Serum and urine electrolytes, and biochemical indices of bone metabolism and liver function were measured in 51 post-menopausal women treated with two hormone replacement therapy regimens for 24 wk. Twenty-six of the women were treated continuously with conjugated equine oestrogens (0.625 mg/day) and the remainder were treated as above with the addition of norgestrel (0.15 mg/day) during the last 12 days of each 28-day cycle. Both treatment regimens affected electrolytes in a similar manner. The most consistent effect was a reduction in serum sodium levels and a reduction in urinary sodium/creatinine ratios. The combined regimen appeared to have a greater effect on sodium reabsorption. Both regimens decreased all the biochemical indices of bone metabolism measured, viz serum calcium (corrected for albumin), phosphate and alkaline phosphatase and urinary calcium/creatinine and hydroxyproline/creatinine ratios. The preparations used decreased the parameters by similar amounts over the 24 wk indicating that both were equally effective in reducing bone turnover. The data suggested, however, that the combined regimen had a more profound effect on bone metabolism during the early phase of treatment. The two treatment regimens had broadly the same effects on the biochemical indices of liver function, reducing albumin levels and all the liver enzymes. Judging by these indices neither regimen had a deleterious effect on liver function. We conclude that the two hormone replacement regimens have similar effects on the biochemical indices measured, but there are subtle differences between the two treatments which merit further research.

Ten years post-menopausal hormone replacement therapy--effect on lipoproteins.

Serum lipoproteins were measured in 72 post-menopausal women, 40 of whom had been taking the synthetic oestrogen, mestranol, for a period of 10 yr and 32 of whom had been taking identical placebo tablets. Mestranol therapy was found to increase serum triglycerides, decrease low density lipoprotein (LDL) cholesterol and increase high density lipoprotein (HDL) cholesterol. The increase in HDL cholesterol was due principally to a marked increase in the cardioprotective HDL2 fraction. It is concluded that long-term mestranol therapy has a beneficial effect on serum lipoproteins which may help to protect post-menopausal women against fatal ischaemic heart disease.

Effect on lipoproteins of Trisequens, a combined hormone preparation.

Lipoprotein concentrations were measured in 31 post-menopausal women during 1 yr of treatment with Trisequens, a natural oestrogen-progestogen preparation. Serum triglyceride, high density lipoprotein and very low density lipoprotein cholesterol concentrations did not change significantly, but low density lipoprotein cholesterol concentrations fell over the first 6 mth. After 1 yr none of the lipoprotein fractions differed significantly in concentration from pre-treatment levels.

Hypercholesterolaemia in treated hypertensives: a controlled trial of intensive dietary advice.

We evaluated dietary counselling by dietitians in hypercholesterolaemic hypertensives over 6 months. A total of 141 patients were randomly assigned to intensive advice or usual care. Body weight fell significantly in the intervention group, but did not in the controls. There was a modest but significant fall in total cholesterol from 7.1 to 6.8 and 7.1 to 6.9 mmol/l in the diet and the control groups, respectively (4 and 3%). A similar pattern emerged from the triglyceride measurements. Low-density lipoprotein fell in both groups, but only achieved significance (P less than 0.05) in the intervention group. High-density lipoprotein did not change. There was a more marked change in cholesterol when serum levels during the study were compared with the previous annual review. These falls occurred after selection for the study but before random allocation to groups. They are unlikely to reflect regression to the mean as the lipids were stable for 2 or more years before the study, but may reflect spontaneous changes in diet after the patients were labelled hypercholesterolaemic. Dietary advice can lower total cholesterol but the magnitude of this decrease is small. Additional approaches are likely to be required to reduce plasma cholesterol to a normal range.