Effect of ovariectomy in humans on serum 6-keto-PGF1 alpha and TXB2 concentrations and platelet fatty acids

ALOX12 gene is associated with the onset of natural menopause in white women

OBJECTIVE

Natural menopause is a key physiological event in a woman's life. Timing of menopause affects risk for many postmenopausal systemic disorders and may thus influence life expectancy. Age at natural menopause (ANM) is largely determined genetically, but a list of candidate genes is far from complete. This study investigated the ALOX12 gene for its possible association with ANM.

METHODS

Six single-nucleotide polymorphisms (SNPs) of the gene (rs9904779, rs2073438, rs11571340, rs434473, rs2307214, and rs312462) were genotyped in a random sample of 210 unrelated white women. The SNPs and common haplotypes were then analyzed for their association with ANM. Smoking, alcohol consumption, and duration of breast-feeding were used as covariates.

RESULTS

Two SNPs, rs9904779 and rs434473 (encodes a replacement of asparagine by serine in the protein), were significantly associated with ANM (P = 0.022 and 0.033, respectively). The minor alleles of both SNPs seem to promote about 1.3- to 1.5-year earlier menopause and confer a 1.6 to 1.8 times higher risk for early menopause. All SNPs indicated significant or nearly significant interactions with alcohol use and duration of breast-feeding. Five common haplotypes were also associated with ANM.

CONCLUSIONS

The ALOX12 gene seems to be associated with the timing of natural menopause in white women.

The mythology of hormone replacement therapy

OBJECTIVE

To evaluate the literature on contraindications contained in pharmaceutical data sheets of five currently available oestrogen replacement preparations (HRT). These contraindications include cardiovascular disease, diabetes, liver diseases, otosclerosis, endometriosis, melanoma and hormone-dependent tumours.

DESIGN

Systematic review.

INTERVENTIONS

Oestrogen replacement regimens.

RESULTS

The contraindications to the five HRT preparations have been taken uncritically from the data sheets of oral contraceptives. In some of these conditions not only is HRT not contraindicated, it is indicated. The data sheets for the HRT preparations all state that cardiovascular disease is a contraindication, but systematic review shows that ischaemic heart disease, hypertension and hyperlipidaemia are not contraindications, and in ischaemic heart disease HRT may actually be indicated. Similarly, systematic review shows that diabetes, chronic liver disease, endometriosis, some cases of treated cancer of the endometrium and breast, melanoma and otosclerosis are not contraindications to HRT.

CONCLUSIONS

The information in the pharmaceutical data sheets of HRT regimens should be modified as more accurate information could influence how these preparations are prescribed by doctors as well as affect patient compliance.

Hormone replacement therapy reduces the reactivity of monocytes and platelets in whole blood--a beneficial effect on atherogenesis and thrombus formation?

OBJECTIVE

Our purpose was to investigate the effects of hormone replacement therapy on the reactivity of monocytes and platelets in whole blood, measured by tissue factor activity, tumor necrosis factor-alpha, and thromboxane B2.

STUDY DESIGN

Thirty-two women were randomized into either transdermal or oral combined hormone replacement therapy and underwent blood sampling before and after 3 and 12 months of treatment. The tissue factor activity in monocytes was measured both in unstimulated whole blood and after a weak lipopolysaccharide stimulation. Tumor necrosis factor-alpha and thromboxane B2 formation in plasma were measured after a weak lipopolysaccharide stimulation of whole blood.

RESULTS

After 12 months of hormone replacement therapy there were significant reductions of tissue factor activity in both unstimulated and lipopolysaccharide-stimulated monocytes (p < 0.001) and significant reductions in the formation of tumor necrosis factor-alpha (p < 0.03) and thromboxane B2 (p < 0.02). There were no differences in these parameters between the transdermal and the oral groups. No changes were observed after 3 months of therapy.

CONCLUSION

Twelve months of hormone replacement therapy reduces cellular activation of blood monocytes and platelets; these changes may account for some of the beneficial effects in reducing the risk of cardiovascular disease.

Thromboxane production in the blood of women increases after menopause whereas tumor necrosis factor is reduced in women compared with men

Previously we have shown that incubation of heparinized blood with a low dose of lipopolysaccharides (5 ng/ml) resulted in a 60% higher generation of TxB2 in the blood of young men as compared with that of young women. In the present study, we investigated a group consisting of 38 healthy men and 38 healthy postmenopausal women aged 50-73 years with no drug use and no known chronic disease. In contrast to our earlier observation that young men produce more TxB2 than young women, no significant difference was observed between the men and women when all the participants above 50 years of age were included (5.7 +/- 0.6 ng/l for men versus 5.2 +/- 0.7 ng/l for women). However, a strong correlation was found with simple regression analysis when increasing TxB2 generation was compared with years after menopause (P < 0.0001). No such correlation was observed for increasing age of men and their TxB2 production. The LPS stimulation system of whole blood was also used to evaluate the production of tumor necrosis factor (TNF-alpha) in older people. Men were found to generate 60% more TNF-alpha than women, but no correlation was found between increasing age of women and TNF-alpha production as observed with TxB2. Risk factors such as SDS-cholesterol, fibrinogen and factor VII were the same in men and women, whereas total cholesterol was higher in women than in men (P < 0.05). Since TxA2 is known to be a mediator of atherosclerotic-induced lesions and TNF-alpha is a well-established indicator of inflammatory reactions, we propose that the reduced production of TxB2 and TNF-alpha in women in our model system may partially explain the lower incidence of atherosclerosis in women as compared with men, and the phenomenon of increased incidence of this disease after menopause.