Sex hormones, lipoproteins, and vascular reactivity

Contraceptive Counseling for the Transgender Patient Assigned Female at Birth

Although almost 0.7% of the Brazilian population identifies as transgender, there is currently no training for healthcare professionals to provide comprehensive care to these patients, including the discussion of reproductive planning. The use of testosterone promotes amenorrhea in the first months of use; however, this effect does not guarantee contraceptive efficacy, and, consequently, increases the risks of unplanned pregnancy. The present article is an integrative review with the objective of evaluating and organizing the approach of contraceptive counseling for the transgender population who were assigned female at birth. We used the PubMed and Embase databases for our search, as well as international guidelines on care for the transgender population. Of 88 articles, 7 were used to develop the contraceptive counseling model. The model follows the following steps: 1. Addressing the information related to the need for contraception; 2. Evaluation of contraindications to the use of contraceptive methods (hormonal and nonhormonal); and 3. Side effects and possible discomfort associated with the use of contraception. The contraceptive counseling model is composed of 18 questions that address the indications and contraindications to the use of these methods, and a flowchart to assist patients in choosing a method that suits their needs.

Metabolic and cardiovascular outcomes in a group of adult patients with Turner's syndrome under hormonal replacement therapy

OBJECTIVE

Turner's syndrome (TS) is a rare genetic disorder caused by complete or partial X chromosome monosomy in a phenotypic female, and it is associated with increased morbidity and mortality for cardiovascular diseases, impaired glucose tolerance, and dyslipidemia.

SUBJECTS AND METHODS

In 30 adult TS patients under chronic hormonal replacement therapy (HRT), 17β-estradiol (E(2)), body mass index (BMI), waist circumference, fasting glucose and insulin, homeostatic model assessment (HOMA) index, serum lipids, oral glucose tolerance test (OGTT), 24 h ambulatory blood pressure monitoring (ABPM), and intima-media thickness (IMT) were evaluated and compared with those in 30 age- and sex-matched controls (CS).

RESULTS

No difference was found between TS and CS in E(2) and BMI, whereas waist circumference was higher (P<0.05) in TS (77.7±2.5 cm) than in CS (69.8±1.0 cm). Fasting glucose in TS and in CS was similar, whereas fasting insulin, HOMA index, and 2 h glucose after OGTT were higher (P<0.0005) in TS (13.2±0.8 mUI/l, 2.5±0.2, and 108.9±5.5 mg/dl respectively) than in CS (9.1±0.5 mUI/l, 1.8±0.1, and 94.5 ± 3.8 mg/dl respectively). Total cholesterol was higher (P<0.05) in TS (199.4 ± 6.6 mg/dl) than in CS (173.9±4.6 mg/dl), whereas no significant differences in high-density lipoprotein, low-density lipoprotein, and triglycerides were found between the two groups. In 13% of TS, ABPM showed arterial hypertension, whereas IMT was <0.9 mm in all TS and CS. A negative correlation between insulin levels, HOMA index, or 2 h glucose after OGTT and E(2) was present in TS.

CONCLUSIONS

Our results indicate that adult patients with TS under HRT are connoted by higher frequency of central obesity, insulin resistance, hypercholesterolemia, and hypertension.

An open-label study of subdermal implants of estradiol-only versus subdermal implants of estradiol plus nomegestrol acetate: effects on symptom control, lipid profile and tolerability

OBJECTIVE

To compare the effects of continuous 17-beta estradiol-only silastic implants with those of continuous 17-beta estradiol plus continuous nomegestrol acetate silastic implants on symptom control, lipid profile and tolerability in postmenopausal women.

METHODS

This was an open-label, parallel-group study. Women with and without uterus and no contraindications to hormone therapy (HT) in this study, we consider as HT the replacement of Estrogens-only and Estrogens + Progestogens Therapy, were enrolled. Each subject was assigned to receive four 17-beta estradiol-only silastic implants (women without uterus), or four 17-beta estradiol plus one nomegestrol acetate silastic implant (women with intact uterus), for 1 year.

RESULTS

A total of 40 subjects were enrolled and received, the silastic implants of which 40 (100.0%) subjects completed the study (n = 20, estradiol only; n = 20, estradiol plus nomegestrol acetate). The incidence of postmenopausal symptoms decreased significantly. No significant decreases in total cholesterol (1.3%), low-density lipoprotein cholesterol (1.1%), triglycerides (1.2%) and fasting glucose ((1.3%) serum levels were observed in both groups, whereas high-density lipoprotein (HDL) cholesterol increased significantly (2.8%), during the study in both groups. The incidences of adverse events were similar in both treatment groups.

CONCLUSIONS

Women treated with 17-beta estradiol-only silastic implants or 17-beta estradiol plus nomegestrol acetate silastic implants showed significant improvement of postmenopausal symptoms, including urogenital and sexual health symptoms and a significant increase in HDL cholesterol and no significant differences in other lipid profiles and tolerability.

Common inflammatory mediators orchestrate pathophysiological processes in rheumatoid arthritis and atherosclerosis

RA is characterized by a systemic inflammatory state, in which immune cells and soluble mediators play a crucial role. These inflammatory processes resemble those in other chronic inflammatory diseases, such as atherosclerosis. The chronic systemic inflammation in RA can be considered as an independent risk factor for the development of atherosclerosis, and represents an important field to investigate the reasons of the increase of acute cardiovascular events in RA. In the present review, we focused on several mediators of autoimmunity, inflammation and endothelial dysfunction, which can be considered the most promising targets to prevent atherogenesis in RA. Among several mediators, the pro-inflammatory cytokine TNF-alpha has been shown as a crucial factor to induce atherosclerosis in RA patients.

Associations of usual sleep duration with serum lipid and lipoprotein levels

STUDY OBJECTIVES

We examined the individual association between sleep duration and a high serum triglyceride, low HDL cholesterol, or high LDL cholesterol level.

DESIGN AND SETTING

The present study analyzed data from the National Health and Nutrition Survey that was conducted in November 2003 by the Japanese Ministry of Health, Labour and Welfare. This survey was conducted on residents in the districts selected randomly from all over Japan.

PARTICIPANTS

The subjects included in the statistical analysis were 1,666 men and 2,329 women aged 20 years or older.

INTERVENTION

N/A.

MEASUREMENTS AND RESULTS

Among women, both short and long sleep durations are associated with a high serum triglyceride level or a low HDL cholesterol level. Compared with women sleeping 6 to 7 h, the relative risk of a high triglyceride level among women sleeping <5 h was 1.51 (95% CI, 0.96-2.35), and among women sleeping > or =8 h was 1.45 (95% CI, 1.00-2.11); the relative risk of a low HDL cholesterol level among women sleeping <5 h was 5.85 (95% CI, 2.29-14.94), and among women sleeping > or =8 h was 4.27 (95% CI, 1.88-9.72). On the other hand, it was observed that the risk of a high LDL cholesterol level was lower among men sleeping > or =8 h. These analyses were adjusted for the following items: age, blood pressure, body mass index, plasma glucose level, smoking habit, alcohol consumption, dietary habits, psychological stress, and taking cholesterol-lowering medications.

CONCLUSIONS

Usual sleep duration is closely associated with serum lipid and lipoprotein levels.

The influence of sex hormones on ocular blood flow in women

PURPOSE

To investigate the influence of sex hormones on ocular haemodynamics, blood flow velocities in the ophthalmic and central retinal arteries and serum levels of sex hormones were measured in pre- and postmenopausal women.

METHODS

Colour Doppler imaging (CDI) was used to determine the flow velocities (peak systolic velocity [PSV] and end-diastolic velocity [EDV]) and the resistive index (RI) in the ophthalmic and central retinal arteries in 22 premenopausal and 32 postmenopausal women, who had never received hormone replacement therapy. Serum levels were measured for oestradiol, free testosterone and follicle-stimulating hormone. The CDI parameters were compared between the two groups and the influence of serum levels of oestradiol and testosterone on blood flow velocities and the resistive indices were analysed.

RESULTS

After correcting for age and mean arterial blood pressure, an analysis of covariance disclosed a significantly lower EDV (p=0.02) and a significantly higher RI (p=0.01) in the central retinal artery of postmenopausal women compared with premenopausal women. Partial correlation analysis, controlling for age, revealed significant correlations between the CDI parameters and serum levels of oestradiol and testosterone. For premenopausal women, PSV (r=0.58, p=0.04) and EDV (r=0.73, p=0.006) in the ophthalmic artery correlated positively with serum oestradiol levels. The RI in the central retinal artery decreased with increasing oestradiol levels in both groups (premenopausal r= -0.40, p=0.04; postmenopausal r= -0.32, p=0.05). Peak systolic velocity in the central retinal artery correlated negatively (r= -0.49, p=0.04), whereas the RI correlated positively (r=0.53, p=0.02) with testosterone levels in the premenopausal group. Postmenopausal women with higher testosterone levels had lower EDV (r= -0.53, p=0.007) in the central retinal artery and higher RI in both vessels (ophthalmic artery r=0.48, p=0.01; central retinal artery r=0.61, p=0.002).

CONCLUSION

Our data provide evidence of a relationship between serum sex hormone levels and blood flow velocities and resistive indices in retrobulbar arteries. Oestradiol appears to have beneficial effects on ocular haemodynamics, whereas testosterone may act as an antagonistic to the effects of oestrogen.

Cytokines, acute-phase proteins, and hormones: IL-1 and TNF-alpha production in contact-mediated activation of monocytes by T lymphocytes

The cytokine network is a homeostatic system that has to be perceived in an analogous fashion to the acid/base equilibrium. The level of any cytokine in biological fluids can be interpreted correctly only by taking into account the levels of other synergistic cytokines, of their respective inhibitors, and of each cytokine receptor. Due to their potent activities in many different processes (including cell growth and differentiation, development, and repair processes leading to the restoration of homeostasis), the cytokine activities have to be tightly controlled by natural inhibitory mechanisms. Since one of the main functions of cytokines is to mediate interactions between the immune and inflammatory system, it is thought that chronic immuno-inflammatory diseases might be caused in part by the uncontrolled production of cytokines. Depending on the stage of inflammation or the biological effect determined, the same cytokine might be pro- or anti-inflammatory. This applies, for instance, to IL-4, IL-10, and TGFbeta. An important mechanism that triggers the production of pro-inflammatory cytokines in chronic inflammatory diseases is the direct cellular contact between stimulated T cells and monocyte-macrophages. This mechanism is blocked at the systemic level by the "negative" acute-phase protein apolipoprotein A-I (apo A-I). The levels of expression of cytokines and cytokine inhibitors and acute-phase proteins are ruled by hormones. Estrogens as well as androgens inhibit the production of IL-1beta and TNF-alpha on monocyte-macrophages. However, androgens antagonize estrogen stimulatory effects on apo A-I synthesis by the liver. Other studies suggest that estradiol is more inhibitory to Thl cytokines (e.g., IFNgamma, IL-2), while testosterone is inhibitory to Th2 cytokines (e.g., IL-4). Cytokines also control the axis of the hypothalamic-hypophyseal-adrenal glands as well as the sexual hormones. The discrepancy between studies would suggest that the mechanisms are different in physiological and pathophysiological conditions.

Effects on serum lipid profiles of continuous 17beta-estradiol, intermittent norgestimate regimens versus continuous combined 17beta-estradiol/norethisterone acetate hormone replacement therapy

OBJECTIVE

To compare the effects of a daily oral 1-mg dose of continuous 17beta-estradiol (E2) plus intermittent (3 days off, 3 days on) norgestimate (NGM) 90 microg (n = 221), an oral 2-mg dose of continuous E2 plus intermittent NGM 180 microg (n = 219), and an oral 2-mg dose of continuous E2 plus continuous norethisterone acetate (NETA) 1 mg (n = 217) on blood lipids and lipoproteins in postmenopausal women.

BACKGROUND

The present study was undertaken because some progestins have adverse effects on lipid profiles, thereby negating the favorable effects of estrogens.

METHODS

This was a multicenter, randomized, parallel-group trial that focused primarily on the 2 marketed regimens--E2 1 mg/NGM 90 microg and E2/NETA. Both subjects and investigators were blinded to the intermittent regimens; the continuous combined regimen was administered open-label. After a minimum 12-hour overnight fast, blood samples were collected at baseline and during months 7 and 12 to determine lipid and lipoprotein concentrations using validated methods.

RESULTS

E2 1 mg/NGM 90 microg was associated with significant (ie, the 95% CI did not include 0) increases in high-density lipoprotein cholesterol (HDL-C) (6.8% [95% CI = 4.7%, 9.0%] and 4.8% [2.3%, 7.2%] at months 7 and 12, respectively) and high-density lipoprotein 2 cholesterol (HDL2-C) (10.8% [6.2%, 15.3%] and 24.1% [18.9%, 29.4%]) concentrations, and decreases in total cholesterol (-7.7% [-9.0%, -6.3%] and -9.2% [-10.5%, -7.9%]), low-density lipoprotein cholesterol (-14.3% [-16.3%, -12.4%] and -14.9% [-16.7%, -13.2%]), and lipoprotein(a) (-30.6% [-41.4%, -20.0%] at month 12) concentrations. A significant difference (P < 0.001 by analysis of variance) between the E2 1-mg/NGM 90-microg and NETA regimens was seen for HDL-C and HDL2-C concentrations, which were elevated in subjects receiving E2 1 mg/NGM 90 microg but reduced (-9.1% [-11.1%, -7.1%] and -12.3% [-14.3%, -10.3%] for HDL-C at months 7 and 12, respectively; -14.2% [-18.0%, -10.4%] and -2.5% [-7.8%, +2.8%] for HDL2-C at months 7 and 12, respectively) in those receiving E2/NETA.

CONCLUSIONS

In the present study, continuous E2 1 mg/NGM 90 microg was associated with beneficial effects on lipids and lipoproteins in healthy postmenopausal women, effects that were greater at least for HDL-C and HDL2-C than those observed with continuous combined E2/NETA. The applicability of the study results to women with preexisting cardiovascular disease or dyslipidemia, or those who are overweight, remains to be investigated.

Lp(a) and lipids in adult Turner's syndrome: impact of treatment with 17beta-estradiol and norethisterone

Turner's syndrome is associated with a high incidence of cardiovascular disease and hypothyreosis; conditions which are associated with abnormal lipid metabolism. To test whether alterations of lipid metabolism is present in healthy Turner's women, we compared lipids in a group of adult women with Turner's syndrome with an age matched group of healthy women. In addition the impact of sex steroid replacement therapy was studied in the women with Turner's syndrome. Patients were studied before and during treatment with hormonal replacement therapy, consisting of either oral 17beta-estradiol or transdermal 17beta-estradiol, and oral norethisterone. Control subjects were studied once in the early follicular stage of the menstrual cycle. The study group consisted of 26 (33.2+/-7.9 years) patients with Turner's syndrome and an age matched control group of 24 (32.7+/-7.6 years) normal women. Body composition measures, apolipoprotein (apo) B and apo A-I, Lp(a), cholesterol, HDL, LDL, triglycerides, thyroxine (TT4), free thyroxine (FT4), triiodothyronine (TT3), free triiodothyronine (FT3), TSH, and leptin were determined. Apo A-I levels were higher in Turner's patients (P45 g/l) Lp(a), more women with Turner's syndrome had high levels of Lp(a) than controls (P=0.024), while all other measures of lipid metabolism were comparable to controls. The level of TSH, FT3, and FT4 were significantly higher in Turner's patients, while TT4, TT3 and adjusted 24h energy expenditure were comparable to controls. Lp(a) (P=0.005), HDL (P=0.045) and apo A-I (P=0.039) decreased significantly, while there was a tendency towards a decrease in apo B (P=0.063) during treatment with sex hormones. In conclusion more women with Turner's syndrome than controls have high levels of apolipoprotein A-I and Lp(a), but only after dichomitization, while other markers of lipid metabolism are normal. Replacement therapy with female sex hormones lowered Lp(a), HDL cholesterol and apolipoprotein A-I.

A novel intermittent regimen of norgestimate to preserve the beneficial effects of 17beta-estradiol on lipid and lipoprotein profiles

OBJECTIVE

This study was undertaken to evaluate the effects of 3 dosage levels of intermittent norgestimate plus a constant dose of 17beta-estradiol on blood lipid and lipoprotein concentrations in 236 postmenopausal women.

STUDY DESIGN

In this multicenter, double-blind, parallel-group trial the subjects were randomly assigned to receive 1 mg estradiol daily or 1 mg estradiol daily plus intermittent (3 days off and 3 days on) doses of 30 microg, 90 microg, or 180 microg norgestimate for 360 days.

RESULTS

The regimens of 1 mg estradiol plus 30 microg norgestimate and 1 mg estradiol plus 90 microg norgestimate increased concentrations of high-density lipoprotein cholesterol, HDL(2) high-density lipoprotein cholesterol, HDL(3) high-density lipoprotein cholesterol (except the regimen of 1 mg estradiol plus 30 microg norgestimate at 7 months), and apolipoprotein apo A-I. They decreased total cholesterol concentration, low-density lipoprotein cholesterol concentration, low-density lipoprotein/high-density lipoprotein ratio, apolipoprotein apo B concentration, and Lp(a) lipoprotein concentration, and they attenuated estradiol-induced increases in triglyceride concentrations. In contrast, the regimen of 1 mg estradiol plus 180 microg norgestimate reduced concentrations of high-density lipoprotein cholesterol, high-density lipoprotein HDL(3) cholesterol, and apolipoprotein apo A-I at 7 months and increased the low-density lipoprotein/high-density lipoprotein ratio at 7 months.

CONCLUSIONS

An intermittent regimen of norgestimate at 30 or 90 microg daily administered for 3 days off followed by 3 days on preserved the beneficial lipid and lipoprotein changes induced by continuous therapy with 1 mg 17beta-estradiol daily; however, 180 microg norgestimate did not do so.

Comparison between moexipril and atenolol in obese postmenopausal women with hypertension

The present study investigated the effect of the new ACE-inhibitor moexipril versus the beta 1-adrenergic blocker atenolol on metabolic parameters, adverse events (AEs) and sitting systolic (SSBP) and sitting diastolic blood pressure (SDBP) in obese postmenopausal women with hypertension (stage I and II). After a 4-week placebo run-in phase, 116 obese, postmenopausal women with primary hypertension were randomised into two treatment groups receiving once daily dosages of either moexipril 7.5 mg or atenolol 25 mg initially (mean age: 57 +/- 7 years in both groups; mean weight: 94 kg in the moexipril group and 89 kg in the atenolol group, corresponding to a body mass index (BMI) of 35.2 kg/m2 and 34.1 kg/m2 in both groups, respectively). After 4 and 8 weeks, the dosages were uptitrated to moexipril 15 mg, or if necessary to moexipril 15 mg/hydrochlorothiazide (HCTZ) 25 mg, or to atenolol 50 mg and atenolol 50 mg/HCTZ 25 mg, in patients whose blood pressure was not sufficiently controlled. At endpoint, metabolic parameters (total cholesterol, triglycerides, LDL, HDL, glucose, insulin) were not significantly altered in either treatment group. Most frequent adverse events under monotherapy (moexipril/atenolol) were asthenia (5.3/13.0%), headache (13.2/21.7%), cough (7.9/6.5%), pharyngitis (21.1/8.7%) and peripheral oedema (5.3/13.0%). Overall at least one AE was reported in 66% of the patients treated with moexipril and in 78% of those treated with atenolol. Reduction of SSBP/SDBP at endpoint was 14.7 +/- 1.9/10.0 +/- 1.1 and 8.7 +/- 1.9/8.4 +/- 1.1 mmHg after treatment with moexipril and atenolol, respectively. The results showed that moexipril and atenolol are equally effective in reducing blood pressure without adversely affecting blood lipids and carbohydrate metabolism.

Effect of thyroid hormone replacement on lipoprotein(a), lipids, and apolipoproteins in subjects with hypothyroidism

OBJECTIVE

To study the effect of thyroid hormone replacement on total cholesterol, low-density lipoprotein cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C), apolipoprotein A-I and B-100, and lipoprotein(a) [Lp(a)] in subjects with hypothyroidism.

MATERIAL AND METHODS

In 17 patients with clinical primary hypothyroidism, studies were done before and after thyroid hormone replacement therapy. Free thyroxine and thyrotropin were determined by chemiluminescent assay. Total cholesterol and triglycerides were measured by enzymatic methods, and HDL-C was measured after dextran sulfate-MgCl2 precipitation. Apolipoprotein A-I and B-100 were assayed by immunonephelometry. For measurement of Lp(a), we used a sequential sandwich enzyme-linked immunosorbent assay.

RESULTS

After levothyroxine treatment, the mean concentration of thyrotropin decreased from 91.4 to 3.7 microIU/mL, and free thyroxine increased from 0.5 to 1.2 ng/ dL. Total cholesterol, triglycerides, HDL-C, low-density lipoprotein cholesterol, and apolipoprotein A-I and B-100 decreased after thyroid hormone replacement therapy. Lp(a) levels also decreased significantly (P<0.05) after treatment, from a mean of 33.4 to 25.6 mg/dL.

CONCLUSION

Hypothyroidism is associated with an increase in total cholesterol, triglycerides, HDL-C, apolipoprotein A-I and B-100, and Lp(a). A reduction in lipid and lipoprotein levels after thyroid hormone replacement in our study cohort resulted in a less atherogenic profile.

Estradiol stimulates apolipoprotein A-I- but not A-II-containing particle synthesis and secretion by stimulating mRNA transcription rate in Hep G2 cells

Estrogen therapy increases plasma HDL levels, which may reduce cardiovascular risk in postmenopausal women. The mechanism of action of estrogen in influencing various steps in hepatic HDL and apolipoprotein (apo) A-I synthesis and secretion are not fully understood. In this study, we have used the human hepatoblastoma cell line (Hep G2) as an in vitro model system to delineate the effect of estradiol on multiple regulatory steps involved in hepatic HDL metabolism. Incubation of Hep G2 cells with estradiol resulted in the following statistically significant findings: (1) increased accumulation of apoA-I in the medium without affecting uptake/removal of radiolabeled HDL-protein; (2) accelerated incorporation of [3H]leucine into apoA-I; (3) selective increase in [3H]leucine incorporation into lipoprotein (LP) A-I but not LP A-I+A-II HDL particles (HDL particles without and with apoA-II, respectively); (4) increased ability of apoA-I-containing particles to efflux cholesterol from fibroblasts; (5) stimulated steady state apoA-I but not apoA-II mRNA expression; and (6) increased newly transcribed apoA-I mRNA message without effect on apoA-I mRNA half-life. The data indicate that estradiol stimulates newly transcribed hepatic apoA-I mRNA, resulting in a selective increase in LP A-I, a subfraction of HDL that is associated with decreased atherosclerotic cardiovascular disease, especially in premenopausal women.

A study of the interactive effects of oral contraceptive use and dietary fat intake on blood pressure, cardiovascular reactivity and glucose tolerance in normotensive women

OBJECTIVE

To investigate the interactive effects of oral contraceptive pill use and dietary fat intake on cardiovascular haemodynamics and metabolic parameters in young normotensive women.

DESIGN

Thirty-two women participated, of whom 16 were taking oral contraceptive pills (ethinyl-oestradiol plus levonorgestrel) and 16 were age-matched and weight-matched controls not taking such pills. Subjects consumed either a high-fat or a low-fat diet for 2 weeks in an open, randomized, crossover study lasting 6 weeks. Investigations were performed at the end of each diet during the luteal phase of the menstrual cycle.

METHODS

Blood pressure was measured by 24 h ambulatory recording; cardiovascular reactivity was determined by examining blood pressure responses to systemic infusions of noradrenaline and angiotensin II and to the cold pressor test; and carbohydrate metabolism was investigated by an intravenous glucose-tolerance test.

RESULTS

Plasma triglyceride levels were significantly higher in women taking oral contraceptive pills compared with non-users on both diets; however, responses of lipoprotein levels to the two diets did not differ between study groups (total and low-density lipoprotein cholesterol levels decreased by 15 and 17% in oral contraceptive pill users and by 14% each in non-users, on the low-fat compared with the high-fat diet). Fasting plasma insulin levels, the insulin-production response to administration of glucose (insulin area under the curve) and resting clinic and night-time systolic blood pressures were all significantly reduced on the low-fat diet, but only in non-users. Blood pressure responses to noradrenaline and maximal heart rate response to cold were significantly attenuated during the low-fat diet in oral contraceptive pill users. During the low-fat diet, resting systolic, 24 h systolic and diastolic blood pressures and insulin area under the curve were all significantly higher for women taking the oral contraceptive pills. Users of these pills also exhibited a greater systolic sensitivity to administration both of noradrenaline and of angiotensin II and had a higher plasma renin activity irrespective of dietary phase.

CONCLUSIONS

These results confirm that oral contraceptive pills have the potential to cause adverse effects on blood pressure, cardiovascular reactivity and the insulin-production response to administration of glucose and suggest that some of the beneficial effects of a low-fat diet on these parameters may be negated in women taking oral contraceptive pills.

Estrogens and atherosclerosis

Estrogens prevent heart disease in women and have also been shown to retard atherogenesis in animal models. Estrogens may act at several steps in the atherogenic process to prevent cardiovascular disease. Some of the benefits of estrogens can be ascribed to their ability to favorably alter the lipoprotein profile, i.e. increase high-density lipoprotein and decrease low-density lipoprotein, and also to their ability to prevent oxidative modification of low-density lipoprotein. Other beneficial effects of estrogens include direct actions on the vascular endothelium and vascular smooth muscle, leading to a decrease in the expression of adhesion molecules involved in monocyte adhesion to endothelial cells, and to a decrease in certain chemokines involved in monocyte migration into the subendothelial space. Estrogens may also affect the later stages of atherogenesis. Finally, estrogens may modify the behavior of atherosclerotic vessels by altering their reactivity and thereby promoting vasodilation, and this may also partly account for their ability to prevent clinical events due to cardiovascular disease.