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PubMed1998

Effects of raloxifene on serum lipids and coagulation factors in healthy postmenopausal women.

CONTEXT: Raloxifene is a selective estrogen receptor modulator that has estrogen-agonistic effects on bone and estrogen-antagonistic effects on breast and uterus. OBJECTIVE: To identify the effects of raloxifene on markers of cardiovascular risk in postmenopausal women, and to compare them with those induced by hormone replacement therapy (HRT). DESIGN: Double-blind, randomized, parallel trial. SETTING: Eight sites in the United States. PARTICIPANTS: 390 healthy postmenopausal women recruited by advertisement. INTERVENTION: Participants were randomized to receive 1 of 4 treatments: raloxifene, 60 mg/d; raloxifene, 120 mg/d; HRT (conjugated equine estrogen, 0.625 mg/d, and medroxyprogesterone acetate, 2.5 mg/d); or placebo. MAIN OUTCOME MEASURES: Change and percent change from baseline of lipid levels and coagulation parameters after 3 months and 6 months of treatment. RESULTS: At the last visit completed, compared with placebo, both dosages of raloxifene significantly lowered low-density lipoprotein cholesterol (LDL-C) by 12% (P < .001), similar to the 14% reduction with HRT (P < .001). Both dosages of raloxifene significantly lowered lipoprotein(a) by 7% to 8% (P < .001), less than the 19% decrease with HRT (P<.001). Raloxifene increased high-density lipoprotein-2 cholesterol (HDL2-C) by 15% to 17% (P < .05), less than the 33% increase with HRT (P < .001). Raloxifene did not significantly change high-density lipoprotein cholesterol (HDL-C), triglycerides, or plasminogen activator inhibitor-1 (PAI-1); whereas HRT increased HDL-C by 11% and triglycerides by 20%, and decreased PAI-1 by 29% (for all, P < .001). Raloxifene significantly lowered fibrinogen by 12% to 14% (P < .001), unlike HRT, which had no effect. Neither treatment changed fibrinopeptide A or prothrombin fragment 1 and 2. CONCLUSIONS: Raloxifene favorably alters biochemical markers of cardiovascular risk by decreasing LDL-C, fibrinogen, and lipoprotein(a), and by increasing HDL2-C without raising triglycerides. In contrast to HRT, raloxifene had no effect on HDL-C and PAI-1, and a lesser effect on HDL2-C and lipoprotein(a). Further clinical trials are necessary to determine whether these favorable biochemical effects are associated with protection against cardiovascular disease.

Aged↗
PubMed1999

The effect of raloxifene on risk of breast cancer in postmenopausal women: results from the MORE randomized trial. Multiple Outcomes of Raloxifene Evaluation.

CONTEXT: Raloxifene hydrochloride is a selective estrogen receptor modulator that has antiestrogenic effects on breast and endometrial tissue and estrogenic effects on bone, lipid metabolism, and blood clotting. OBJECTIVE: To determine whether women taking raloxifene have a lower risk of invasive breast cancer. DESIGN AND SETTING: The Multiple Outcomes of Raloxifene Evaluation (MORE), a multicenter, randomized, double-blind trial, in which women taking raloxifene or placebo were followed up for a median of 40 months (SD, 3 years), from 1994 through 1998, at 180 clinical centers composed of community settings and medical practices in 25 countries, mainly in the United States and Europe. PARTICIPANTS: A total of 7705 postmenopausal women, younger than 81 (mean age, 66.5) years, with osteoporosis, defined by the presence of vertebral fractures or a femoral neck or spine T-score of at least 2.5 SDs below the mean for young healthy women. Almost all participants (96%) were white. Women who had a history of breast cancer or who were taking estrogen were excluded. INTERVENTION: Raloxifene, 60 mg, 2 tablets daily; or raloxifene, 60 mg, 1 tablet daily and 1 placebo tablet; or 2 placebo tablets. MAIN OUTCOME MEASURES: New cases of breast cancer, confirmed by histopathology. Transvaginal ultrasonography was used to assess the endometrial effects of raloxifene in 1781 women. Deep vein thrombosis or pulmonary embolism were determined by chart review. RESULTS: Thirteen cases of breast cancer were confirmed among the 5129 women assigned to raloxifene vs 27 among the 2576 women assigned to placebo (relative risk [RR], 0.24; 95% confidence interval [CI], 0.13-0.44; P<.001). To prevent 1 case of breast cancer, 126 women would need to be treated. Raloxifene decreased the risk of estrogen receptor-positive breast cancer by 90% (RR, 0.10; 95% CI, 0.04-0.24), but not estrogen receptor-negative invasive breast cancer (RR, 0.88; 95% CI, 0.26-3.0). Raloxifene increased the risk of venous thromboembolic disease (RR, 3.1; 95% CI, 1.5-6.2), but did not increase the risk of endometrial cancer (RR, 0.8; 95% CI, 0.2-2.7). CONCLUSION: Among postmenopausal women with osteoporosis, the risk of invasive breast cancer was decreased by 76% during 3 years of treatment with raloxifene.

Aged↗
PubMed1999

Reduction of vertebral fracture risk in postmenopausal women with osteoporosis treated with raloxifene: results from a 3-year randomized clinical trial. Multiple Outcomes of Raloxifene Evaluation (MORE) Investigators.

CONTEXT: Raloxifene hydrochloride, a selective estrogen receptor modulator, prevents bone loss in postmenopausal women, but whether it reduces fracture risk in these women is not known. OBJECTIVE: To determine the effect of raloxifene therapy on risk of vertebral and nonvertebral fractures. DESIGN: The Multiple Outcomes of Raloxifene Evaluation (MORE) study, a multicenter, randomized, blinded, placebo-controlled trial. SETTING AND PARTICIPANTS: A total of 7705 women aged 31 to 80 years in 25 countries who had been postmenopausal for at least 2 years and who met World Health Organization criteria for having osteoporosis. The study began in 1994 and had up to 36 months of follow-up for primary efficacy measurements and nonserious adverse events and up to 40 months of follow-up for serious adverse events. INTERVENTIONS: Participants were randomized to 60 mg/d or 120 mg/d of raloxifene or to identically appearing placebo pills; in addition, all women received supplemental calcium and cholecalciferol. MAIN OUTCOME MEASURES: Incident vertebral fracture was determined radiographically at baseline and at scheduled 24- and 36-month visits. Nonvertebral fracture was ascertained by interview at 6-month-interim visits. Bone mineral density was determined annually by dual-energy x-ray absorptiometry. RESULTS: At 36 months of the evaluable radiographs in 6828 women, 503 (7.4%) had at least 1 new vertebral fracture, including 10.1% of women receiving placebo, 6.6% of those receiving 60 mg/d of raloxifene, and 5.4% of those receiving 120 mg/d of raloxifene. Risk of vertebral fracture was reduced in both study groups receiving raloxifene (for 60-mg/d group: relative risk [RR], 0.7; 95% confidence interval [CI], 0.5-0.8; for 120-mg/d group: RR, 0.5; 95% CI, 0.4-0.7). Frequency of vertebral fracture was reduced both in women who did and did not have prevalent fracture. Risk of nonvertebral fracture for raloxifene vs placebo did not differ significantly (RR, 0.9; 95% CI, 0.8-1.1 for both raloxifene groups combined). Compared with placebo, raloxifene increased bone mineral density in the femoral neck by 2.1 % (60 mg) and 2.4% (120 mg) and in the spine by 2.6% (60 mg) and 2.7% (120 mg) P<0.001 for all comparisons). Women receiving raloxifene had increased risk of venous thromboembolus vs placebo (RR, 3.1; 95% CI, 1.5-6.2). Raloxifene did not cause vaginal bleeding or breast pain and was associated with a lower incidence of breast cancer. CONCLUSIONS: In postmenopausal women with osteoporosis, raloxifene increases bone mineral density in the spine and femoral neck and reduces risk of vertebral fracture.

Adult↗
PubMed1999

Special considerations in breast cancer risk and survival.

Experimental and clinical evidence suggests that breast neoplasia appears to be a hormone-dependent process that may also be influenced by dietary factors in many women. Conflicting reports on the relationship between exogenous hormones and the development, progression, and recurrence of breast cancer are critically examined in this report. The absolute breast cancer risk associated with either hormone replacement therapy or oral contraceptive use has not been clearly defined. Data from some large prospective studies have actually documented lower mortality rates for women taking hormone replacement compared with those for women who did not have hormone replacement therapy. In this regard, age, duration of use, and preexisting breast cancer risk factors must be taken into account. Although the results of two major prospective clinical trials addressing the role of timing of surgery within the menstrual cycle are forthcoming, the majority of studies have found no consistent association between timing of surgery and breast cancer survival. Recently reported prospective randomized data showing that selective-estrogen-receptor-modulators can act as effective chemoprevention agents in women at increased risk for breast cancer development are presented. Finally, information regarding the effect of dietary manipulation on breast cancer risk and survival is reviewed.

Breast Neoplasms↗
PubMed2000

Absolute structure determination of the highly biologically active bisdehydrodoisynolic acids.

In a project designed to relate the unexpected in vivo and in vitro properties exhibited by (+)- and (-)-bisdehydrodoisynolic acid with their absolute stereochemical structure, an X-ray crystal-structure analysis was undertaken of the highly estrogenic, poorly binding (-) enantiomer. (1) and (13)C NMR spectra are also reported for the first time. The crystal structure shows the cis juxtaposition of the carboxyl and ethyl groups, which are separated by a large torsion angle, and that only the carbon atom holding the carboxyl group is out of the plane in which the remainder of the fused three-ring moiety lies. The crystal structure, which unequivocally characterizes the (-) enantiomer as cis-13(S),14(R) and, implicitly, the (+) enantiomer as cis-13(R),14(S), will be useful in continued studies aimed at explaining the selective estrogen receptor modulation (SERM) of these enantiomers which, in some cases, produces significantly different end-organ effects compared to those of estradiol, in both males and females, affording the promise of a variety of therapeutic and pharmacologic applications.

Crystallography, X-Ray↗
PubMed2003

Diagnosis and management of treatment-related osteoporosis in men with prostate carcinoma.

Osteoporosis is a complication of androgen deprivation therapy in men with prostate carcinoma. Androgen deprivation therapy, caused by either bilateral orchiectomy or treatment with a gonadotropin-releasing hormone agonist, decreases bone mineral density and increases fracture risk. Other factors including diet and lifestyle may contribute to bone loss. There is limited information regarding the best strategy to prevent osteoporosis in men with prostate carcinoma. Lifestyle modification including smoking cessation, moderation of alcohol consumption, and regular weight-bearing exercise should be encouraged. Supplemental calcium and vitamin D are also recommended. Additional treatment may be warranted for men with osteoporosis, fractures, or high rates of bone loss during androgen deprivation therapy. Intravenous pamidronate, a second-generation bisphosphonate, prevents bone loss during androgen deprivation therapy. Zoledronic acid, a more potent third-generation bisphosphonate, not only prevents bone loss but also increases bone mineral density during androgen deprivation therapy. Other bisphosphonates may be effective although they have not been evaluated in this clinical setting. Treatment with estrogens or selective estrogen receptor modulators may also be effective. Monotherapy with bicalutamide or other antiandrogens may cause less bone loss than androgen deprivation therapy.

Absorptiometry, Photon↗
PubMed2003

Favorable cardiac risk among elderly breast carcinoma survivors.

BACKGROUND: There are two reasons why women who survive breast carcinoma may be at a lower risk of developing coronary heart disease (CHD) compared with women without a history of breast carcinoma. First, estrogens may be etiologic in the development of breast carcinoma and protective of CHD. Second, a common therapy for breast carcinoma (tamoxifen) may be associated with cardiac protection. METHODS: In this population-level cohort study, the authors analyzed data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER)-Medicare program to study the cardiac risk of elderly female Medicare beneficiaries with and without a history of breast carcinoma. Using the SEER file, the authors identified elderly women survivors of Stage 0, I, or II breast carcinoma (n = 5980) diagnosed between the ages of 55 and 64. Using the Medicare 5% noncancer file, the authors also identified elderly women without a history of cancer (n = 23,165). They followed women from age 67 for up to 5 years for hospitalization for acute myocardial infarction (AMI) through a review of Medicare claims. The authors controlled the analyses for race, socioeconomic status, geographic location, cohort entry year, and medical comorbidity. RESULTS: The hazard of hospitalization for AMI for breast carcinoma survivors relative to comparison patients was 0.66 (95% confidence interval, 0.49-0.88). This apparent cardioprotective effect of breast carcinoma survivorship was stronger in breast carcinoma survivors with documented cardiac risk factors. CONCLUSIONS: Survivors of early-stage postmenopausal breast carcinoma are at a significantly lower risk of hospitalization for AMI than women who do not have a history of breast carcinoma. That survivors' risk varies with previous cardiac risk factors may be consistent with effects of selective estrogen receptor modulators. This phenomenon should be evaluated further with individual-level data containing information on patient cardiac risk factors and tamoxifen use to help clarify the mechanism behind the risk reduction.

Aged↗
PubMed2003

Polymorphic variation at the -202 locus in IGFBP3: Influence on serum levels of insulin-like growth factors, interaction with plasma retinol and vitamin D and breast cancer risk.

Previous reports have suggested an association between circulating IGFBP-3 levels and the risk of premenopausal breast cancer, and a single nucleotide polymorphism (SNP) in the promoter region of IGFBP-3 (nucleotide -202) was shown to influence transcription. There is prior evidence that the action of antiproliferative agents such as retinoids and selective estrogen receptor modulators (SERMs) act in part by upregulating IGFBP3 gene expression. We identified 677 women with incident breast cancer and 834 matched controls from the Nurses' Health Study (NHS) and genotyped them at the -202 locus. For 943 of these women, we had previously measured IGF-I and IGFBP-3 plasma levels, and for 861 of these subjects, plasma retinol levels were available. Age-adjusted mean circulating IGFBP-3 levels were highest in the individuals with the AA genotype and decreased significantly in a stepwise manner in the presence of 1 or 2 copies of the C allele (4,426 ng/ml, 4,060 ng/ml and 3,697 ng/ml, respectively). We found a positive relation between age-adjusted IGFBP-3 levels and plasma retinol (14% difference in IGFBP-3 in top vs. bottom tertiles of retinol, p for trend < 0.001; Spearman correlation coefficient r = 0.25), which was similar across genotypes at the -202 IGFBP3 locus (interaction term, F = 0.10, p = 0.91). Breast cancer risk was not significantly related to genotype at the -202 locus in our prospective analyses. We confirmed a relation between the -202 IGFBP3 polymorphism and IGFBP-3 serum levels and observed a positive correlation between circulating retinol levels and circulating IGFBP-3 levels, providing further evidence that retinoids may influence IGF physiology. Our data do not demonstrate a significant influence of this locus on breast cancer risk, but we cannot exclude a minor influence or an influence confined to subgroups.

Adult↗
PubMed2006

Steroid hormone receptors and coregulators in endocrine-resistant and estrogen-independent breast cancer cells.

Resistance to hormonal therapy is often a problem in the treatment of breast cancer patients. It has been suggested that resistance could be explained by altered nuclear hormone receptor or coregulator levels or inappropriately increased agonist activity of selective estrogen receptor modulator (SERM). To test these hypotheses, we have established novel MCF-7 cell line-derived in vitro models of anti-estrogen- and progestin-resistant and estrogen-independent breast cancer by long-term culture in the presence of toremifene and medroxyprogesterone acetate (MPA) and in the absence of estradiol, respectively. Using cell growth and multiprobe ribonuclease protection assays, the expression of 5 nuclear hormone receptors and 9 coregulators as well as the alterations in the cell proliferation and target gene transcription in response to hormonal treatments were studied. Progesterone receptor (PR) expression was decreased and silencing mediator for retinoid acid and thyroid hormone receptors (SMRT) and amplified in breast cancer-1 (AIB1) expression increased in anti-estrogen-resistant cells. Estrogen caused PR and ERbeta upregulation in all cell lines, but we did not observe increased agonist activity of anti-estrogen measured by regulation of these estrogen target genes. Basal ERalpha levels and estrogenic growth response were decreased and p300/CBP-associated factor (pCAF) and AIB1 upregulated by estrogen in progestin-resistant cells, but coregulator levels were unchanged. Estrogen-independent cells were still estrogen-responsive and PR, nuclear receptor corepressor (N-CoR) and SMRT expression was increased whereas steroid receptor coactivator-1 (SRC-1a) and CBP-related protein p300 (p300) expression decreased. Their growth was inhibited by toremifene, but estradiol was able to abrogate this effect, which might have interesting clinical implications concerning the use of postmenopausal hormone replacement therapy.

Antineoplastic Agents, Hormonal↗
PubMedDate not supplied

Comparison of tamoxifen and testosterone propionate in male rats: differential prevention of orchidectomy effects on sex organs, bone mass, growth, and the growth hormone-IGF-I axis.

Testis dysfunction can weaken bone and reduce muscle mass as well as impair sexual function. Testosterone (T) therapy has useful effects on sex organs, bone, and muscle in T-deficient males, but prostate concerns can preclude T use in some men. Although estrogens or other drugs can protect bone in men, gynecomastia makes estrogens unappealing, and other drugs may also be undesirable in some cases. Selective estrogen receptor modulators (SERMs) inhibit estrogen-evoked sex organ growth but mimic estrogen effects on bone and cholesterol and are advantageous for some women. SERMs may also be useful in men who must avoid androgens. As a preclinical test of this idea, tamoxifen (a SERM) and testosterone propionate (TP, a classic androgen) were compared for their efficacy in preventing varied effects of orchidectomy (ORX) in adult male rats. ORX led to ventral prostate and seminal vesicle atrophy and decreases in somatic growth, proximal tibia bone mineral density (BMD), and serum growth hormone (GH) and insulin-like growth factor I (IGF-I). ORX also increased anterior pituitary glandular kallikrein, serum cholesterol, and body temperature. Pituitary prolactin (PRL) content was unaltered. ORX effects on sex organs, somatic growth, IGF-I, cholesterol, body temperature, and pituitary kallikrein were prevented by TP at 1 mg/kg (3 doses per week), but BMD and GH were unresponsive. ORX effects on BMD and GH were prevented by TP at 10 mg/kg, but this dose evoked supraphysiologic increases in sex organs and PRL, failed to restore somatic growth, and further reduced IGF-I. Tamoxifen (1 mg/kg daily) prevented ORX effects on BMD, GH, and cholesterol without altering basal or TP-induced sex organ growth and further reduced IGF-I and somatic growth. Tamoxifen did not alter basal PRL but blocked increases caused by TP at 10 mg/kg. In summary, tamoxifen prevented ORX effects on bone and cholesterol in male rats without affecting sex organs or PRL and might be useful for men who must avoid androgens. Unexpectedly, a TP dose that replicated testis effects on sex organs and other targets had no effect on BMD or GH, and a larger TP dose that restored BMD and GH was worse at replicating normal male physiology. In addition, correlation/regression results suggested that the GH-IGF-I axis contributes to changes in BMD.

Animals↗
PubMed2006

Comparative gene expression profiling reveals partially overlapping but distinct genomic actions of different antiestrogens in human breast cancer cells.

Antiestrogens used for breast cancer (BC) treatment differ among each other for the ability to affect estrogen receptor (ER) activity and thereby inhibit hormone-responsive cell functions and viability. We used high-density cDNA microarrays for a comprehensive definition of the gene pathways affected by 17beta-estradiol (E2), ICI 182,780 (ICI), 4OH-tamoxifen (Tamoxifen), and raloxifene (RAL) in ER-positive ZR-75.1 cells, a suitable model to investigate estrogen and antiestrogen actions in hormone-responsive BC. The expression of 601 genes was significantly affected by E2 in these cells; in silico analysis reveals that 86 among them include one or more potential ER binding site within or near the promoter and that the binding site signatures for E2F-1, NF-Y, and NRF-1 transcription factors are significantly enriched in the promoters of genes induced by estrogen treatment, while those for CAC-binding protein and LF-A1 in those repressed by the hormone, pointing to novel transcriptional effectors of secondary responses to estrogen in BC cells. Interestingly, expression of 176 E2-regulated mRNAs was unaffected by any of the antiestrogens tested, despite the fact that under the same conditions the transcriptional and cell cycle stimulatory activities of ER were inhibited. On the other hand, of 373 antiestrogen-responsive genes identified here, 52 were unresponsive to estrogen and 25% responded specifically to only one of the compounds tested, revealing non-overlapping and clearly distinguishable effects of the different antiestrogens in BC cells. As some of these differences reflect specificities of the mechanism of action of the antiestrogens tested, we propose to exploit this gene set for characterization of novel hormonal antagonists and selective estrogen receptor modulators (SERMs) and as a tool for testing new associations of antiestrogens, more effective against BC.

Breast Neoplasms↗
PubMed2006

Anisotropic lattice contraction in pharmaceuticals: the influence of cryo-crystallography on calculated powder diffraction patterns.

The following article examines the influence of thermal expansion on X-ray powder diffraction patterns. With the increasing percentages of structures that are being solved using low-temperature data sets and the nearly exclusive collection of room-temperature experimental datasets by X-ray powder diffraction, considerable discrepancies are observed when comparing calculated powder diffraction patterns to experimental patterns. Such comparisons are extremely valuable to solid-state pharmaceutical scientists attempting to identify crystal forms of active pharmaceutical ingredients and excipient components of formulations. In this study, fluoxetine HCl, raloxifene HCl, and olanzapine are examined and serve as practical laboratory examples. The observations are supported through analysis of data presented in the Cambridge Structural Database to help assess the extent and potential impact of this problem.

Anisotropy↗
PubMed2002

Transcriptional activation of estrogen receptor ERalpha and ERbeta by polycyclic musks is cell type dependent.

In the past decade the list of chemicals in the environment that are able to mimic the natural hormone estrogen, thereby disrupting endocrine function, has grown rapidly. These chemicals are able to bind to estrogen receptors (ERs) and influence estrogen signaling pathways, although several of them have structures that differ substantially from the endogenous hormone 17beta-estradiol. Because of their polycyclic nature, the polycyclic musks AHTN (6-acetyl-1,1,2,4,4,7-hexamethyltetraline) and HHCB (1,2,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-gamma-2-benzopyran) were assessed for interaction with estrogen receptors. These compounds are ubiquitously present in surface waters and have been identified in human milk fat and blood. Using sensitive in vitro reporter gene assays, we found that AHTN and HHCB act as selective estrogen receptor modulators (SERMs), inducing both estrogenic and antiestrogenic activity dependent on the cell line and the ER subtype targeted. Weak estrogenic effects were observed only at relatively high concentrations (10 microM). Antiestrogenic effects were observed in various cell lines starting at concentrations of 0.1 microM. In comparison with the well-known SERM, 4-hydroxytamoxifen, AHTN and HHCB have a much lower potency in suppressing estradiol-induced transactivation. Results with various mutant ER receptor types suggest that binding sites of the musk compounds differ from 17beta-estradiol and 4-hydroxytamoxifen. The cell type dependency of ER transactivation shows that caution should be exerted when interpreting effects of estrogenic compounds using in vitro systems.

Benzopyrans↗
PubMed2004

Effects of 17beta-estradiol, tamoxifen and raloxifene on the protein and mRNA expression of interleukin-6, transforming growth factor-beta1 and insulin-like growth factor-1 in primary human osteoblast cultures.

We investigated the effects of 17betaestradiol and two selective estrogen receptor modulators, tamoxifen and raloxifene, on the expression and release of constitutive and interleukin-1-stimulated interleukin (IL)-6, transforming growth factor-beta1 (TGF-beta1) and insulin-like growth factor-1 by osteoblasts in primary culture from trabecular bone of healthy post-menopausal women. After 24 h incubation with 10(-8) M concentration of these compounds, there was no decrease in: a) the constitutive or IL-1beta-induced levels of IL-6 protein released to culture medium; b) the constitutive IL-6 mRNA expression after incubation of osteoblasts with 10(-8) M 17betaestradiol or 10(-8) M tamoxifen for 1, 3, 6, 24 or 30 h. Although a decrease after 30 h of treatment with 10(-8) M, raloxifene was found in mRNA IL-6 expression, and this fact was not reflected by a decrease in the release of IL-6 protein to the culture medium after 48 h of incubation with 10(-8) M or 10(-7) M raloxifene. Tumoral growth factorTGF-betal expression was not influenced by incubation with these compounds. Gene expression of IGF-I increased following 24 or 30 h incubation with 10(-8) M 17beta-estradiol and 30 h incubation with raloxifene. Tamoxifen did not affect IGF-I expression. In conclusion, the effects of estradiol or tamoxifen on bone metabolism do not appear to be mediated through the regulation of osteoblast IL-6 release or synthesis, but raloxifene produces a decrease in mRNA IL-6 expression. The actions of estradiol, tamoxifen and raloxifene do not appear to be mediated by tumoral growth factor TGF-beta1. On the other hand, an increase in IGF-I synthesis induced by raloxifene and estradiol could mediate, in part, the effects of these compounds on bone.

Aged↗
PubMed2003

DT56a stimulates creatine kinase specific activity in vascular tissues of rats.

The novel natural product DT56a (Secure Pharmaceuticals, Yavne, Israel), derived from soybean, has been shown to relieve menopausal vasomotor symptoms and increase in bone mineral density with no effect on sex steroid hormone levels or endometrial thickness. In single injection, like 17beta-estradiol (E2), DT56a stimulated bone, cartilage and uterus in immature or ovariectomized female rats, by measuring the changes in the specific activity of the BB isozyme of creatine kinase (CK). When administered in multiple oral doses, DT56a stimulated skeletal tissues similarly to E2 but not uterine CK. The selective estrogen receptor modulator raloxifene blocked the stimulation of CK by either DT56a or by E2 in all tissues tested. In the present study we measured the effects of DT56a on vascular tissues i.e. aorta (Ao) and the left ventricle of the heart (Lv). Both types of animals responded to either single or multiple administration of DT56a like to E2. In the Ao from both animals and in the Lv from ovariectomized rats, raloxifene completely blocked CK activity induced by DT56a, whereas in the Lv of immature female rats the inhibition was partial. Our experimental findings suggest that DT56a acts as estrogen; it has beneficial effects not only on skeletal tissues, but also on vascular tissues, however contrary to estrogen DT56a, did not affect the uterus. These findings suggest that DT56a--which has similar beneficial effects on vascular tissues like that of E2--is probably mediated via common receptor(s).

Animals↗
PubMed2003

Distribution of estrogen receptors alpha and beta mRNA in mouse urogenital tissues and their expression after oophorectomy and estrogen replacement.

Estrogen receptors are present in the urogenital tract. However, little is known about the quantitative distribution of the traditional estrogen receptor (ERalpha) mRNA and the recently identified ERbeta mRNA. By quantitative reverse transcription polymerase chain reaction analysis, the distributions of ERalpha and ERbeta mRNA in mouse urogenital tissues and their expression in selected urogenital tissues after oophorectomy, with or without estrogen replacement, were evaluated. ERalpha mRNA concentrations were higher in the ovary, oviduct, uterus and vagina than in the kidney, ureter or bladder ( P<0.05); ERbeta transcripts were highest in the ovary, oviduct and bladder ( P<0.05). After oophorectomy and estrogen replacement, significant changes were identified in ERalpha and ERbeta mRNA expression. ERalpha and ERbeta mRNA are differentially expressed in mouse urogenital tissues. Oophorectomy and estrogen replacement affect estrogen receptors differently in the bladder, vagina and uterus. These results may explain some tissue-specific responses to estrogen and selective estrogen receptor modulators. The mRNA distributions of estrogen receptors alpha and beta and their expression after oophorectomy, with or without estrogen replacement, differ in mouse urogenital tissues.

Animals↗
PubMed2003

Assessment of bone mineral density in adults and children with Marfan syndrome.

Recent studies indicate that decreased bone mineral density (BMD) occurs in the spine, femoral necks and greater trochanters of some adults and children with Marfan syndrome. Because there is uncertainty regarding the BMD status of patients with Marfan syndrome, we undertook an analysis of BMD in both adults and children with Marfan syndrome. Dual energy X-ray absorptiometry analysis was performed on a convenience sample of 51 patients (30 adults and 21 children) with diagnosed Marfan syndrome from 1993 to 2000. T-Scores (i.e. the number of standard deviations above or below the average normal peak bone density) were determined for comparison of adults. Mean+/-SD of individual BMD values were used for comparison of the data of children. Compared to standard values obtained from normal adult patients, adult males with Marfan syndrome demonstrated significantly reduced femoral neck BMD with an average T-score of -1.54 ( P<0.001), diagnostic of osteopenia. Although osteopenia and osteoporosis were observed in several middle aged and pre- and postmenopausal women, the average T-score value for adult females and children were within normal limits. The etiology and full significance of decreased BMD in adult male patients with Marfan syndrome remain uncertain at the present time. Our results lead us to question the value of aggressive BMD evaluations by DXA in these patients, particularly prior to reaching mid-age. Further investigations will be required to shed insights into the natural history of BMD in adults and children with Marfan syndrome. Any application of bone mineral replacement therapy such as bisphosphonate, selective estrogen receptor modulators, hormone replacement therapy and vitamin D in these patients may be premature based on the existing evidence.

Absorptiometry, Photon↗
PubMed2006

Antiremodeling agents influence osteoblast activity differently in modeling and remodeling sites of canine rib.

Antiremodeling agents reduce bone loss in part through direct actions on osteoclasts. Their effects on osteoblasts and bone formation activity are less clear and may differ at sites undergoing modeling vs. remodeling. Skeletally mature intact beagles, 1-2 years old at the start of the study, were treated daily with clinically relevant doses of alendronate (0.10 or 0.20 mg/kg), risedronate (0.05 or 0.10 mg/kg), raloxifene (0.50 mg/kg), or vehicle (1 mL/kg). Dynamic bone formation parameters were histologically assessed on periosteal, endocortical/trabecular, and intracortical bone envelopes of the rib. Raloxifene significantly increased periosteal surface mineral apposition rate (MAR), a measure of osteoblast activity, compared to all other treatments (+108 to +175%, P < 0.02), while having no significant effect on MAR at either the endocortical/trabecular or intracortical envelope. Alendronate (both 0.10 and 0.20 doses) and risedronate (only the 0.10 dose) significantly (P < or = 0.05) suppressed MAR on the endocortical/trabecular envelope, while none of the bisphosphonate doses significantly altered MAR at either the periosteal or intracortical envelopes compared to vehicle. Based on these results, we conclude that (1) at clinically relevant doses the two classes of antiremodeling agents, bisphosphonates and selective estrogen receptor modulators, exert differential effects on osteoblast activity in the canine rib and (2) this effect depends on whether modeling or remodeling is the predominant mechanism of bone formation.

Alendronate↗