A quantitative analysis of purinoceptor expression in human fetal and adult bladders.

PURPOSE: In adults there is evidence that adenosine triphosphate acting at P2X receptors functions as a co-transmitter at vesical smooth muscle. The contractile mechanisms of human fetal bladder have been studied to a limited extent and it remains undetermined whether P2X receptors contribute. We compared the expression of the 7 known P2X receptors in fetal and adult human bladders using a quantitative polymerase chain reaction (PCR) based method. MATERIALS AND METHODS: Real-time quantitative reverse transcriptase-PCR provides a system for the detection and analysis of RNA. Four complete cadaver fetal bladders were obtained at 16 weeks to full-term gestation and divided into a total of 12 segments. Adult bladder samples were obtained from 4 patients requiring bladder biopsy. Total RNA was extracted from each sample and 10 ng. were used for individual PCR reactions. An ABI 7700 machine (PE Applied Biosystems, California) determined expression levels of the 7 P2X genes in total RNA. RESULTS: In adult bladders P2X1 was by far the predominant purinergic receptor at the messenger RNA level. The remaining purinergic receptors were consistently present in the order P2X1 >> P2X4 > P2X7 >> P2X5 > P2X2 >> P2X3 = P2X6 = 0. In fetal bladders the expression of P2X1 transcripts was much lower than in adult bladders, and P2X4 and P2X7 were also present. The rank order of the P2X transcript level was P2X1 = P2X4 > P2X7 >> P2X5 >> P2X2 >> P2X3 = P2X6 = 0. With increasing gestation the P2X receptor transcript level (expression) shifted from the dome to the body of the bladder. CONCLUSIONS: P2X1 is the predominant purinoceptor subtype in adult human bladders, consistent with pharmacological evidence. The fetal expression of all P2X receptor transcripts is much lower than in adults, suggesting that purinergic transmission is of less importance. However, there are also several marked developmental changes in purinoceptor expression in the bladder, in that P2X4 is expressed in developing bladders at relatively high levels. There is also a marked developmental change in the regional distribution of purinoceptors. These changes are likely to reflect the changing role of purinergic transmission in the control of bladder motility during fetal maturation.

Long term effects of tibolone on the genital tract in postmenopausal women.

OBJECTIVES: To assess the effects of six years tibolone therapy on the genital tract in postmenopausal women against matched voluntary controls. DESIGN: Prospective, non-randomised, open label study of the efficacy of tibolone. METHODS: Symptoms were assessed by questionnaires every six months. Assessment of genital tract cellular activity comprised annual vaginal smear and endometrial biopsy/smear in the tibolone group (n = 58) and vaginal smear alone in the control group (n = 55). As a recent protocol addition, transvaginal ultrasound assessment of endometrial thickness was performed in all women who gave consent. Endometrial biopsy was performed in control women if the endometrial thickness was > 5 mm. Karyopyknotic index and maturation index were calculated from the vaginal smears. RESULTS: The rate of amenorrhoea between six months and six years treatment was 90% in the tibolone group compared with 91% in the controls (P was not significant). There was improvement in reported vaginal symptomatology in the treatment group but not in the controls. Median endometrial thickness increased slightly in the tibolone treated group (3.2 mm tibolone vs 2.5 mm control; P < 0.05). There were no cases of cytologically proven endometrial stimulation in asymptomatic women in either group. Both vaginal karyopyknotic index and maturation index increased significantly in the tibolone treated group over six years, but not in the control group. CONCLUSIONS: Tibolone is effective at maintaining an inactive endometrium while providing oestrogenisation of the lower genital tract over a six year period.

Selective estrogen receptor modulators: Women's panacea for the next millennium?

The purpose of this review is to assimilate relevant experimental and clinical information available on selective estrogen receptor modulators with respect to their potential use as agents to improve women's health in the postmenopausal years. In addition, the mechanisms of action of these drugs are outlined. Selective estrogen receptor modulators represent an exciting group of antiestrogens that possess agonist action on bone, lipids, and lipoproteins and antagonistic action in the endometrium and breast. Thus in theory these drugs may preserve bone density and reduce the risk of osteoporotic fracture and coronary heart disease at the same time that they lower the incidences of breast and endometrial neoplasms. Short-term data with the use of raloxifene suggest that bone is preserved and lipid profiles are less atherogenic. Long-term studies are needed to determine whether raloxifene or other selective estrogen receptor modulators are associated with any decrease in the risk of breast or endometrial cancer.

High resolution ultrasound assessment of the carotid artery: its relevance in postmenopausal women and the effects of tibolone on carotid artery ultrastructure.

OBJECTIVES: Hormone replacement therapy protects from cardiovascular disease at the menopause in part by reduction of menopausal pro-atherogenic serum lipid changes. Tibolone has beneficial effects on lipids, although serum high density lipoprotein levels decrease. This study aimed primarily to establish the effects of long-term administration of tibolone on a new surrogate marker for cardiovascular disease risk, the measurement of carotid artery intima-media thickness (CIMT) using high-resolution ultrasound. METHODS: Measurement of CIMT and assessment of carotid atherosclerotic plaques were undertaken in 31 women on tibolone and 30 voluntary controls from an ongoing open-label study of tibolone. RESULTS: The two groups were comparable, except for mean age and prevalence of current smokers. Repeatability of CIMT measurements was acceptable (CV, 10.0%). CIMT was significantly thicker in those with atherosclerotic plaques and increased systolic blood pressure. Prevalence of plaques was raised in those who had ever smoked, and those with elevated systolic blood pressure. There was no influence of tibolone on CIMT, whether plaques were present or not. CONCLUSIONS: This reliable technique demonstrates associations between CIMT and established risk factors. CIMT was significantly thicker in those with existing plaques. We did not demonstrate an effect of long-term tibolone use on either CIMT or prevalence of plaques.

The effects of tibolone.

Tibolone is a non-bleeding form of hormone replacement therapy (HRT). When ingested, it is broken down into metabolites, of which the progestogenic metabolite predominates at the level of the endometrium, so that an atrophic endometrium is produced. For the postmenopausal woman, the availability of non-bleeding HRT has great appeal, and compliance is substantially improved. Other clinical situations in which tibolone is particularly useful include: women who have had hormone-dependent tumors in the past, women who have had endometriosis and women taking gonadotropin-releasing hormone agonists.

Review of 3,530 referrals for bone density measurements of spine and femur: evidence that radiographic osteopenia predicts low bone mass.

PURPOSE: To determine the relationship between bone mineral density (BMD) measurements and the initial reason for referral to a BMD screening service. MATERIALS AND METHODS: Referral letters for 3,479 of the 3,530 women referred for BMD screening were classified according to the indication for screening. Mean age-matched standard deviation scores (Z scores) were derived for each of the 10 most common indications. Mean BMD between each group was compared with the age-matched value from the local normal range by means of a one-sample Student t test. Mean young normal standard deviation scores (T scores) were derived, and the percentages of women with osteopenia or osteoporosis from each referral group were calculated on the basis of the World Health Organization criteria. RESULTS: The most common reason for referral was to aid in a decision regarding hormone replacement therapy (n = 700). The highest proportion of women with osteoporosis in any group was in the radiographic osteopenia group (n = 269). CONCLUSION: Radiographic evidence of osteopenia is a strong predictor of osteoporosis. Screening for osteopenia appears justified in this and other high-risk groups and those seeking a rationale for preventive therapy.

Screening for osteopenia and osteoporosis: do the accepted normal ranges lead to overdiagnosis?

Osteoporosis is a common disease which causes significant morbidity and mortality and in many cases may be preventable. In the absence of fragility fractures the accepted method of identifying those at high risk is based upon bone mineral density (BMD) measurements with defined cut-off points. To correctly delineate normal from abnormal, reliable reference ranges appropriate to the observed population are required. We have studied the age-dependent changes in mean BMD and standard deviation at the lumbar spine and femoral neck in a normal population extracted from 4280 women screened for osteopenia and compared our findings with the manufacturer's normal range (MNR). The recent World Health Organization criteria for the diagnosis of osteopenia and osteoporosis using the 'manufacturer's young normal' (MYN) values and our 'study young normal' (SYN) values have been applied. The study normal population (SNP) included 2068 women (mixed social class; mean age 53 years, range 30-79 years). The distribution of mean lumbar spine BMD with age in SNP was generally similar to the MNR. In contrast mean femoral neck bone density from SNP was significantly different from the MNR, ranging from 3% to 12% lower in each 5-year group analysed (p < 0.05). Comparison of standard deviations in spine BMD in SNP against the fixed MNR standard deviation showed a statistically significant increase commencing at 45 years of age. The magnitude of this increase appeared to rise with age and remained significant in the 75- to 79-year age group (p < 0.05). In contrast, standard deviation in femoral neck BMD in SNP appeared relatively constant with age except in the group of women at and around the time of the menopause. The SYN value for mean lumbar spine BMD was 0.994 g/cm2 (cf. MYN value 1.047, p < 0.0001) with a standard deviation of 0.122 g/cm2 (cf. MYN 0.11, p = 0.0005). Similarly our SYN value for femoral neck BMD was 0.787 (cf. MYN value 0.895, p < 0.0001) with a standard deviation of 0.109 (cf. MYN value 0.10, p = 0.0027). Using SYN values 36% (748) for the spine and 33% (675) for the hip of our normal population are classified as osteopenic or osteoporotic. Using MYN values increases the proportion of women classified as osteopenic or osteoporotic to 52% (1078) for the spine and 68% (1409) for the femur. If both sites of measurement are considered simultaneously SYN classifies 46% (952) as either osteopenic or osteoporotic at one or other site, which is increased to 73% (1513) when the MYN values are used. We observe that manufacturer's reference ranges may not be appropriate for the local population and may lead to an erroneously high diagnosis of osteopenia and osteoporosis, which would lead to unnecessary patient anxiety and perhaps errors regarding treatment.

Hormone replacement therapy and serum angiotensin-converting-enzyme activity in postmenopausal women.

The mechanisms by which hormone replacement therapy (HRT) reduces the risk of coronary heart disease (CHD) are incompletely understood, but may include direct arterial effects. We examined the effect of oestrogen/progestagen HRT on serum angiotensin-converting-enzyme (ACE) activity in postmenopausal women. After 6 months, ACE activity was reduced by 20% (p < 0.001) on average in 28 treated women but remained unchanged in 16 controls. Serum ACE activity is modifiable by gonadal steroids and changes in serum ACE may represent a novel mechanism by which HRT reduces CHD risk in women.