| 751. |
- Tivesten, Åsa, 1969, et al.
(författare)
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Additive protective effects of estrogen and androgen treatment on trabecular bone in ovariectomized rats.
- 2004
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Ingår i: Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research. - 0884-0431. ; 19:11, s. 1833-9
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Tidskriftsartikel (refereegranskat)abstract
- Both ER and AR activation regulates trabecular bone mass. We show that combined estrogen and androgen treatment results in additive protection of trabecular bone in OVX rats. This may in part be attributable to the effect of AR activation to attenuate the inhibitory effect of ER activation on bone formation. INTRODUCTION: Sex steroids are important regulators of trabecular bone mass. Both estrogen receptor (ER) and androgen receptor (AR) activation results in increased trabecular bone mass. The aim of this study was to investigate if combined estrogen and androgen treatment might be beneficial in the treatment of trabecular bone loss. MATERIALS AND METHODS: Twelve-week-old female rats were ovariectomized (OVX) and treated with vehicle (V), 17beta-estradiol (E2; ER activation), dihydrotestosterone (DHT; AR activation), or the combination (E2 + DHT) for 6 weeks. The skeletal phenotype was analyzed by pQCT, microCT, histomorphometry of growth plates, and serum levels of biochemical bone markers. RESULTS: Both E2 (+121% over V) and DHT (+34%) preserved the trabecular volumetric BMD (tvBMD) in OVX rats. The effect of E2 and DHT on tvBMD was additive, resulting in a 182% increase over V in the rats given E2 + DHT. MicroCT analyses of the trabecular bone microstructure revealed that the effect of E2 and DHT was additive on the number of trabeculae. E2 treatment reduced serum markers of both bone resorption (collagen C-terminal telopeptide) and bone formation (osteocalcin), indicating reduced bone turnover. Addition of DHT to E2 treatment did not modulate the effects of E2 on the marker of bone resorption, whereas it attenuated the inhibitory effect of E2 on the bone formation marker, which might explain the additive protective effect of E2 and DHT on trabecular bone mass. In contrast, DHT partially counteracted the suppressive effect of E2 on longitudinal bone growth and the E2-induced alterations in growth plate morphology. CONCLUSIONS: These findings show that combined estrogen and androgen treatment results in additive protective effects on trabecular bone in OVX rats. Our data suggest that a combined treatment with selective ER and AR modulators might be beneficial in the treatment of osteoporosis.
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| 752. |
- Tivesten, Åsa, 1969, et al.
(författare)
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Circulating estradiol is an independent predictor of progression of carotid artery intima-media thickness in middle-aged men
- 2006
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Ingår i: J Clin Endocrinol Metab. - : The Endocrine Society. - 0021-972X. ; 91:11, s. 4433-7
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Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: Estrogen treatment of men with prostate cancer is associated with increased cardiovascular morbidity and mortality; however, the role of endogenous estrogen levels for atherosclerotic disease in men is unknown. OBJECTIVE: The objective of the study was to determine whether endogenous serum estradiol (E2) levels predict the progression of carotid artery intima-media thickness in men. DESIGN, SETTING AND PARTICIPANTS: This was a population-based, prospective cohort study (the Atherosclerosis and Insulin Resistance study) conducted in Goteborg, Sweden, among 313 Caucasian men without cardiovascular or other clinically overt diseases. Carotid artery intima-media thickness, an index of preclinical atherosclerosis, was measured by ultrasound at baseline (58 yr of age) and after 3 yr of follow-up. Serum sex hormone levels and cardiovascular risk factors (body mass index, waist to hip ratio, systolic blood pressure, serum triglycerides, plasma c-peptide, and smoking status) were assessed at study entry. INTERVENTION: There was no intervention. MAIN OUTCOME MEASURES: Association between baseline total and free E2 levels and progression of carotid intima-media thickness over 3 yr with adjustments for cardiovascular risk factors was measured. RESULTS: In univariate analyses, both total and free E2 levels at baseline were positively associated with the annual change in intima-media thickness. In linear regression models including E2 and cardiovascular risk factors, low-density lipoprotein and high-density lipoprotein cholesterol and E2 were identified as independent predictors of progression of carotid artery intima-media thickness (total E2 beta = 0.187, P = 0.001; and free E2 beta = 0.183, P = 0.003). CONCLUSIONS: Circulating E2 is a predictor of progression of carotid artery intima-media thickness in middle-aged men. Further studies are needed to investigate the role of endogenous E2 for incident cardiovascular disease events.
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| 753. |
- Tivesten, Åsa, 1969, et al.
(författare)
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Dehydroepiandrosterone and its Sulfate Predict the 5-Year Risk of Coronary Heart Disease Events in Elderly Men
- 2014
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Ingår i: Journal of the American College of Cardiology. - : Elsevier BV. - 0735-1097 .- 1558-3597. ; 64:17, s. 1801-1810
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND The adrenal sex hormone dehydroepiandrosterone (DHEA), which is present in serum mainly as the sulfate DHEA-S, is the most abundant steroid hormone in human blood. Its levels decline dramatically with age. Despite the great amount of literature on vascular and metabolic actions of DHEA/-S, evidence for an association between DHEA/-S levels and cardiovascular events is contradictory. OBJECTIVES This study tested the hypothesis that serum DHEA and DHEA-S are predictors of major coronary heart disease (CHD) and/or cerebrovascular disease (CBD) events in a large cohort of elderly men. METHODS We used gas and liquid chromatography-mass spectrometry to analyze baseline levels of DHEA and DHEA-S in the prospective population-based Osteoporotic Fractures in Men study in Sweden (2,416 men, ages 69 to 81 years). Complete cardiovascular clinical outcomes were available from national Swedish registers. RESULTS During the 5-year follow-up, 302 participants experienced a CHD event, and 225 had a CBD event. Both DHEA and DHEA-S levels were inversely associated with the age-adjusted risk of a CHD event; the hazard ratios and 95% confidence intervals per SD increase were 0.82 (0.73 to 0.93) and 0.86 (0.77 to 0.97), respectively. In contrast, DHEA/-S showed no statistically significant association with the risk of CBD events. The association between DHEA and CHD risk remained significant after adjustment for traditional cardiovascular risk factors, serum total testosterone and estradiol, C-reactive protein, and renal function, and remained unchanged after exclusion of the first 2.6 years of follow-up to reduce reverse causality. CONCLUSIONS Low serum levels of DHEA and its sulfate predict an increased risk of CHD, but not CBD, events in elderly men. (C) 2014 by the American College of Cardiology Foundation.
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| 754. |
- Tivesten, Åsa, 1969, et al.
(författare)
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Growth hormone-induced blood pressure decrease is associated with increased mRNA levels of the vascular smooth muscle KATP channel.
- 2004
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Ingår i: The Journal of endocrinology. - : Bioscientifica. - 0022-0795 .- 1479-6805. ; 183:1, s. 195-202
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Tidskriftsartikel (refereegranskat)abstract
- Growth hormone (GH) deficiency is associated with abnormal vascular reactivity and development of atherosclerosis. GH treatment in GH deficient states restores systemic vascular resistance, arterial compliance, endothelium-dependent and endothelium-independent vasodilation, and may reverse markers of early atherosclerosis. However, very little is known about the molecular mechanisms underlying these effects. In the present study, male Sprague Dawley rats were hypophysectomized and treated for two weeks with GH (recombinant human GH, 2 mg/kg/day) or saline as s.c. injections twice daily. GH decreased aortic systolic blood pressure compared with saline-treated animals, while the diastolic blood pressure was not significantly changed. GH treatment increased cardiac output as determined by Doppler-echocardiography and the calculated systemic vascular resistance was markedly reduced. In order to identify GH-regulated genes of importance for vascular function, aortic mRNA levels were analyzed by the microarray technique and correlated to the systolic blood pressure levels. Using this approach, we identified 18 GH-regulated genes with possible impact on vascular tone and atherogenesis. In particular, mRNA levels of the inwardly rectifying potassium channel Kir6.1 and the sulfonylurea receptor 2B, which together form the vascular smooth muscle ATP-sensitive potassium channel, were both up-regulated by GH treatment and highly correlated to systolic blood pressure. Our findings establish a major role for GH in the regulation of vascular physiology and gene expression. Increased expression of the ATP-sensitive potassium channel, recently shown to be crucial in the regulation of vascular tone, constitutes a possible mechanism by which GH governs vascular tone.
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| 755. |
- Tivesten, Åsa, 1969, et al.
(författare)
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Liver-derived insulin-like growth factor-I is involved in the regulation of blood pressure in mice.
- 2002
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Ingår i: Endocrinology. - 0013-7227. ; 143:11, s. 4235-42
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Tidskriftsartikel (refereegranskat)abstract
- IGF-I has been suggested to be of importance for cardiovascular structure and function, but the relative role of locally produced and liver-derived endocrine IGF-I remains unclear. Using the Cre-LoxP recombination system, we have previously created transgenic mice with a liver-specific, inducible IGF-I knockout (LI-IGF-I-/-). To examine the role of liver-derived IGF-I in cardiovascular physiology, liver-derived IGF-I was inactivated at 4 wk of age, resulting in a 79% reduction of serum IGF-I levels. At 4 months of age, systolic blood pressure (BP) was increased in LI-IGF-I-/- mice. Echocardiography showed increased posterior wall thickness in combination with decreased stroke volume and cardiac output, whereas other systolic variables were unchanged, suggesting that these cardiac effects were secondary to increased peripheral resistance. Acute nitric oxide-synthase inhibition increased systolic BP more in LI-IGF-I-/- mice than in control mice. LI-IGF-I-/- mice showed impaired acetylcholine-induced vasorelaxation in mesenteric resistance vessels and increased levels of endothelin-1 mRNA in aorta. Thus, the increased peripheral resistance in LI-IGF-I-/- mice might be attributable to endothelial dysfunction associated with increased expression of endothelin-1 and impaired vasorelaxation of resistance vessels. In conclusion, our findings suggest that liver-derived IGF-I is involved in the regulation of BP in mice.
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| 756. |
- Tivesten, Åsa, 1969, et al.
(författare)
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Low serum testosterone and estradiol predict mortality in elderly men.
- 2009
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Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 94:7, s. 2482-8
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Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: Age-related reduction of serum testosterone may contribute to the signs and symptoms of aging, but previous studies report conflicting evidence about testosterone levels and male mortality. No large prospective cohort study has determined a possible association between serum estradiol and mortality in men. OBJECTIVE: The main objective was to examine the association between serum testosterone and estradiol and all-cause mortality in elderly men. DESIGN, SETTING, AND PARTICIPANTS: We used specific gas chromatography-mass spectrometry to analyze serum sex steroids at baseline in older men who participated in the prospective population-based MrOS Sweden cohort (n = 3014; mean age, 75 yr; range, 69-80 yr). MAIN OUTCOME MEASURE: All-cause mortality by serum testosterone and estradiol levels. RESULTS: During a mean follow-up period of 4.5 yr, 383 deaths occurred. In multivariate hazards regression models, low levels (within quartile 1 vs. quartiles 2-4) of both testosterone [hazard ratio (HR), 1.65; 95% confidence interval (CI), 1.29-2.12] and estradiol (HR, 1.54; 95% CI, 1.22-1.95) associated with mortality. A model including both hormones showed that both low testosterone (HR, 1.46; 95% CI, 1.11-1.92) and estradiol (HR, 1.33; 95% CI, 1.02-1.73) predicted mortality. Risk of death nearly doubled (HR, 1.96; 95% CI, 1.46-2.62) in subjects with low levels of both testosterone and estradiol compared with subjects within quartiles 2-4 of both hormones. CONCLUSIONS: Elderly men with low serum testosterone and estradiol have increased risk of mortality, and subjects with low values of both testosterone and estradiol have the highest risk of mortality.
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| 757. |
- Tivesten, Åsa, 1969, et al.
(författare)
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Low serum testosterone and high serum estradiol associate with lower extremity peripheral arterial disease in elderly men. The MrOS Study in Sweden
- 2007
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Ingår i: Journal of the American College of Cardiology. - : Elsevier BV. - 0735-1097 .- 1558-3597. ; 50:11, s. 1070-1076
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: This study sought to determine whether serum levels of testosterone and estradiol associate with lower extremity peripheral arterial disease (PAD) in a large population-based cohort of elderly men. Background: Few studies have explored the relationship between serum sex steroids and lower extremity PAD in men. Methods: The Swedish arm of the MrOS (Osteoporotic Fractures in Men) study (n = 3,014; average age 75.4 years) assessed ankle-brachial index (ABI) and defined lower extremity PAD as ABI <0.90. Radioimmunoassay measured serum levels of total testosterone, estradiol, and sex hormone-binding globulin, and we calculated free testosterone and free estradiol levels from the mass action equations. Results: A linear regression model including age, current smoking, previous smoking, diabetes, hypertension, body mass index, free testosterone, and free estradiol showed that free testosterone independently and positively associates with ABI (p < 0.001), whereas free estradiol independently and negatively associates with ABI (p < 0.001). Logistic regression analyses showed that free testosterone in the lowest quartile (vs. quartiles 2 to 4; odds ratio [OR] 1.65, 95% confidence interval [CI] 1.22 to 2.23, p = 0.001) and free estradiol in the highest quartile (vs. quartiles 1 to 3; OR 1.45, 95% CI 1.09 to 1.94, p = 0.012) independently associate with lower extremity PAD. Conclusions: This cross-sectional study shows for the first time that low serum testosterone and high serum estradiol levels associate with lower extremity PAD in elderly men. Future prospective and interventional studies are needed to establish possible causal relationships between sex steroids and the development of lower extremity PAD in men.
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| 758. |
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| 759. |
- Tobias, J. H., et al.
(författare)
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Opportunities and Challenges in Functional Genomics Research in Osteoporosis: Report From a Workshop Held by the Causes Working Group of the Osteoporosis and Bone Research Academy of the Royal Osteoporosis Society on October 5th 2020
- 2021
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Ingår i: Frontiers in Endocrinology. - : Frontiers Media SA. - 1664-2392. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- The discovery that sclerostin is the defective protein underlying the rare heritable bone mass disorder, sclerosteosis, ultimately led to development of anti-sclerostin antibodies as a new treatment for osteoporosis. In the era of large scale GWAS, many additional genetic signals associated with bone mass and related traits have since been reported. However, how best to interrogate these signals in order to identify the underlying gene responsible for these genetic associations, a prerequisite for identifying drug targets for further treatments, remains a challenge. The resources available for supporting functional genomics research continues to expand, exemplified by "multi-omics" database resources, with improved availability of datasets derived from bone tissues. These databases provide information about potential molecular mediators such as mRNA expression, protein expression, and DNA methylation levels, which can be interrogated to map genetic signals to specific genes based on identification of causal pathways between the genetic signal and the phenotype being studied. Functional evaluation of potential causative genes has been facilitated by characterization of the "osteocyte signature", by broad phenotyping of knockout mice with deletions of over 7,000 genes, in which more detailed skeletal phenotyping is currently being undertaken, and by development of zebrafish as a highly efficient additional in vivo model for functional studies of the skeleton. Looking to the future, this expanding repertoire of tools offers the hope of accurately defining the major genetic signals which contribute to osteoporosis. This may in turn lead to the identification of additional therapeutic targets, and ultimately new treatments for osteoporosis.
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| 760. |
- Trajanoska, Katerina, et al.
(författare)
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Assessment of the genetic and clinical determinants of fracture risk : Genome wide association and mendelian randomisation study
- 2018
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Ingår i: BMJ (Online). - : BMJ. - 0959-8138 .- 1756-1833. ; 362
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Tidskriftsartikel (refereegranskat)abstract
- Objectives To identify the genetic determinants of fracture risk and assess the role of 15 clinical risk factors on osteoporotic fracture risk. Design Meta-analysis of genome wide association studies (GWAS) and a two-sample mendelian randomisation approach. Setting 25 cohorts from Europe, United States, east Asia, and Australia with genome wide genotyping and fracture data. Participants A discovery set of 37 857 fracture cases and 227 116 controls; with replication in up to 147 200 fracture cases and 150 085 controls. Fracture cases were defined as individuals (>18 years old) who had fractures at any skeletal site confirmed by medical, radiological, or questionnaire reports. Instrumental variable analyses were performed to estimate effects of 15 selected clinical risk factors for fracture in a two-sample mendelian randomisation framework, using the largest previously published GWAS meta-analysis of each risk factor. Results Of 15 fracture associated loci identified, all were also associated with bone mineral density and mapped to genes clustering in pathways known to be critical to bone biology (eg, SOST, WNT16, and ESR1) or novel pathways (FAM210A, GRB10, and ETS2). Mendelian randomisation analyses showed a clear effect of bone mineral density on fracture risk. One standard deviation decrease in genetically determined bone mineral density of the femoral neck was associated with a 55% increase in fracture risk (odds ratio 1.55 (95% confidence interval 1.48 to 1.63; P=1.5×10'68). Hand grip strength was inversely associated with fracture risk, but this result was not significant after multiple testing correction. The remaining clinical risk factors (including vitamin D levels) showed no evidence for an effect on fracture. Conclusions This large scale GWAS meta-analysis for fracture identified 15 genetic determinants of fracture, all of which also influenced bone mineral density. Among the clinical risk factors for fracture assessed, only bone mineral density showed a major causal effect on fracture. Genetic predisposition to lower levels of vitamin D and estimated calcium intake from dairy sources were not associated with fracture risk.
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