Protein metabolism in Turner syndrome and the impact of hormone replacement therapy

Dosage of estradiol, bone and body composition in Turner syndrome: a 5-year randomized controlled clinical trial

OBJECTIVE

Reduced bone mineral density (BMD) is seen in Turner syndrome (TS) with an increased risk of fractures, and body composition is characterized by increased body fat and decreased lean body mass. To evaluate the effect of two different doses of oral 17B-estradiol in young TS women on bone mineral density (BMD), biochemical markers of bone turnover and body composition with the hypothesis of a positive effect of the higher dose.

DESIGN

A double-blind 5-year randomized controlled clinical trial. 20 young TS women participated. Inclusion criteria were diagnosis of TS, age 15-25 years and current treatment with 2 mg oral estradiol daily.

METHODS

The low-dose (LD) group was administered 2 mg 17B-estradiol/day orally and placebo, the high-dose (HD) group was administered 2 + 2 mg 17B-estradiol/day orally. Main outcome measures were whole body and regional bone mineral density (BMD), lean body mass (LBM), fat mass (FM) measured yearly by DXA scan and resorptive and formative bone markers in serum.

RESULTS

BMD, whole body and regional, increased over time with an attenuation toward the end of the study, and bone turnover markers decreased over time, both with no differences between the treatment groups (P = 0.2-0.9). LBM increased significantly more in the HD group (P = 0.02). FM remained stable in both groups.

CONCLUSIONS

A steady increase in BMD over time in TS was found similar to healthy young women. The higher estrogen dose did not differentially affect BMD or bone markers. The positive effect on body composition may have long-ranging health benefits in TS.

The macrophage low-grade inflammation marker sCD163 is modulated by exogenous sex steroids

Soluble CD163 (sCD163) is a novel marker linked to states of low-grade inflammation such as diabetes, obesity, liver disease, and atherosclerosis, all prevalent in subjects with Turner syndrome (TS) and Klinefelter syndrome (KS). We aimed to assess the levels of sCD163 and the regulation of sCD163 in regards to treatment with sex hormone therapy in males with and without KS and females with and without TS. Males with KS (n=70) and age-matched controls (n=71) participating in a cross-sectional study and 12 healthy males from an experimental hypogonadism study. Females with TS (n=8) and healthy age-matched controls (n=8) participating in a randomized crossover trial. The intervention comprised of treatment with sex steroids. Males with KS had higher levels of sCD163 compared with controls (1.75 (0.47-6.90) and 1.36 (0.77-3.11) respectively, P<0.001) and the levels correlated to plasma testosterone (r=-0.31, P<0.01), BMI (r=0.42, P<0.001), and homeostasis model of assessment insulin resistance (r=0.46, P<0.001). Treatment with testosterone did not significantly lower sCD163. Females with TS not receiving hormone replacement therapy (HRT) had higher levels of sCD163 than those of their age-matched healthy controls (1.38±0.44 vs 0.91±0.40, P=0.04). HRT and oral contraceptive therapy decreased sCD163 in TS by 22% (1.07±0.30) and in controls by 39% (0.55±0.36), with significance in both groups (P=0.01 and P=0.04). We conclude that levels of sCD163 correlate with endogenous testosterone in KS and are higher in KS subjects compared with controls, but treatment did not significantly lower levels. Both endogenous and exogenous estradiol in TS was associated with lower levels of sCD163.

Coagulation and fibrinolytic disturbances are related to carotid intima thickness and arterial blood pressure in Turner syndrome

OBJECTIVE

Turner syndrome (TS) is characterized by growth retardation, hypogonadism and a high risk of cardiovascular complications and atherosclerosis; case reports suggest that thrombo-embolic complications may be present.

DESIGN

Cross-sectional study.

PATIENTS

Sixty women with TS.

MEASUREMENTS

We characterized the activities of the haemostatic system, elucidated by the assessment of a panel of clotting factors and thrombosis risk factors and related these findings to carotid intima thickness (CIMT) and blood pressure.

RESULTS

Most (81%) received hormone replacement therapy. The medians of all measured factors and inflammatory parameters were not different from normative data, but many cases displayed values of C-reactive protein (CRP) (40%), fibrinogen (15%), fibrin D-dimer (15%), factor VIII (25%), von Willebrand factor (vWF) (15%), cholesterol and liver parameters that were greater than normative limits. CRP, fibrinogen, vWF, factor VIII and liver parameters were highly and positively correlated. Haemostatic variables were positively related to both CIMT and blood pressure. The Factor V Leiden G1691A gene polymorphism heterozygosity was detected in 12·5%.

CONCLUSION

We describe a significant proportion of individual TS females having high levels of vWF, factor VIII, fibrinogen and CRP (15-40%) and an increased frequency of the Leiden mutation, with important associations with CIMT and blood pressure, suggesting that a subset of TS may have an unfavourable haemostatic balance, which may contribute to the increased risk of premature ischaemic heart disease and possibly increase the risk of deep venous and portal vein thrombosis.

Acute estrogen exposure does not affect basal very low-density lipoprotein-triglyceride production or oxidation in postmenopausal women

CONTEXT

Long-term hormone replacement therapy (HRT) with estradiol (E(2)) is associated with an altered lipid profile including unfavorable increases in triglyceride (TG) concentrations and augmented hepatic very low-density lipoprotein (VLDL)-TG production. There are indications that this effect of estrogens may be immediate.

OBJECTIVE

To study the in vivo effect of a single dose of E(2) on VLDL-TG kinetics and oxidation in humans.

METHODS

Eight healthy, postmenopausal women were given a single dose of either placebo or E(2) (4 mg) orally. VLDL-TG kinetics was assessed by a 240-min primed-continuous infusion of ex vivo labeled [1-(14)C]triolein-labeled VLDL. Fractional and absolute VLDL-TG oxidation was determined by hyamin trapping of exhaled (14)C label. Indirect calorimetry provided measurements of lipid oxidation.

RESULTS

Administration of 4 mg of E(2) orally rapidly increased plasma E(2) concentrations from below detection threshold to premenopausal levels. Free fatty acids (FFA) and TG concentrations were unaltered. No immediate effect was observed on either VLDL-TG production (placebo versus E(2)): 20.0+/-12.4 vs 24.1+/-10.7 micromol/min, P=0.33; VLDL-TG oxidation: 12.3+/-10.9 vs 12.6+/-5.6 micromol/min, P=0.93); or VLDL-TG clearance rates: 51.4+/-16.8 vs 64.9+/-28.8 ml/min, P=0.34).

CONCLUSIONS

Short-term E(2) elevation does not affect VLDL-TG production, oxidation, or clearance in humans. We therefore propose that HRT-associated dyslipidemia has a gradual rather than immediate onset.

Little change in markers of protein breakdown and oxidative stress in humans in immobilization-induced skeletal muscle atrophy

A number of studies in rodents suggest that disuse atrophy results from a large increase in proteolysis affected by, or accompanying, increased oxidative stress. Little information is available, however, about the effects of immobilization on markers of muscle protein breakdown and oxidative stress in humans. Therefore, the purpose of this investigation was to measure markers of breakdown or oxidative stress in subjects who underwent 14 days of knee-brace-mediated immobilization. Vastus lateralis samples taken from 21 young subjects before, and 2 days and 14 days after, single leg immobilization were measured for ubiquitin-protein conjugates, caspase 3/7 activity, the 14-kDa caspase-3 cleaved actin fragment, 4-hydroxy-2-nonenal (4-HNE) adducts, and protein carbonyls. Quadriceps cross-sectional area decreased by 5.7% +/- 1.1% (p < 0.0001) following immobilization. Ubiquitin-protein conjugates were elevated at 2 days of immobilization (12%, p < 0.05) but were not different from baseline at 14 days. Levels of the 14-kDa actin fragment and caspase 3/7 activity did not change over the immobilization period. The oxidative stress markers, 4-HNE adducts and protein carbonyls, did not change at any time point. These static measures of breakdown and oxidative modification suggest that a small increase in protein ubiquitination occurs early (2 days), but elevations in ubiquitinated or oxidatively modified proteins are not sustained during the later phase (14 days) of uncomplicated disuse atrophy in humans, suggesting that these pathways are not playing a major role in simple disuse-induced atrophic loss of protein mass.