Ethnic differences in levels of bone and cartilage biomarkers and hormonal responsiveness in nine groups of postmenopausal Asian women: The Pan-Asia Menopause (PAM) study

Viewpoint on the role of tissue maintenance in ageing: focus on biomarkers of bone, cartilage, muscle, and brain tissue maintenance

Specific hallmarks are thought to underlie the ageing process and age-related functional decline. In this viewpoint, we put forward the hypothesis that disturbances in the process of tissue maintenance are an important common denominator that may lie in between specific hallmarks of ageing (i.e. damage and responses to damage) and their ultimate (patho)physiological consequences (i.e. functional decline and age-related disease). As a first step towards verifying or falsifying this hypothesis, it will be important to measure biomarkers of tissue maintenance in future studies in different study populations. The main aim of the current paper is to discuss potential biomarkers of tissue maintenance that could be used in such future studies. Among the many tissues that could have been chosen to explore our hypothesis, to keep the paper manageable, we chose to focus on a selected number of tissues, namely bone, cartilage, muscle, and the brain, which are important for mobility and cognition and affected in several common age-related diseases, including osteoporosis, osteoarthritis, sarcopenia, and neurodegenerative diseases. Furthermore, we discuss the advantages and limitations of potential biomarkers for use in (pre)clinical studies. The proposed biomarkers should be validated in future research, for example by measuring these in humans with different rates of ageing.

East is east and West is west: perspectives on the menopause in Asia and The West

There is a school of thought that believes that menopausal symptoms are a peculiarly 'Western' phenomenon, not experienced by women from other regions and particularly not from Asia where, it has been claimed, dietary, social and cultural factors afforded protection for women living in that region. More recently, studies conducted in multi-ethnic communities living in Western countries as well as in Asian communities have found that the menopause and its consequences are similar world-wide. Ethnic differences within Asia account for small differences in endogenous hormone levels and age at menopause between Asian and Western women, and the type of menopause symptoms and their prevalence also differ between those two communities. However, like in the West and perhaps because of a Western influence, the long-term health problems of postmenopausal women including cardiovascular disease, osteoporosis and breast cancer are of major importance to Asian women and health services in the 21st century.

Bone turnover and bone mineral density in HIV-1 infected Chinese taking highly active antiretroviral therapy -a prospective observational study

Background

Low bone mass and high bone turnover have been reported in HIV-infected individuals, both as a consequence of HIV infection itself, as well as from treatment with highly active antiretroviral therapy (HAART). The purpose of this study is to evaluate the impact of HAART on bone mineral density and bone turnover in HIV-1 infected Chinese patients.

Methods

Forty HIV-1 infected patients were enrolled in this study; all patients were followed through 48 weeks, and 17 patients completed 96 weeks. Bone mineral density (BMD), procollagen type 1 N-terminal propeptide (P1NP), collagen type 1 cross-linked C-telopeptide (β-CTX), parathyroid hormone (PTH), and 25-OH vitamin D levels were measured at baseline, 48 and 96 weeks. Baseline measurements were compared with an age-, gender-, and BMI-matched healthy control population.

Results

At baseline, raw BMD in the lumbar spine of HIV-1 infected patients was significantly lower than that of healthy controls (1.138 ± 0.112 g/cm² vs. 1.195 ± 0.139 g/cm², p = 0.047). During the first 48 weeks after initiating HAART, BMD of lumbar spine, femoral neck, and total hip decreased significantly in HIV-1 infected patients, with annual percent decline ranging from 1.78-3.28%. However, from week 48 to 96, BMD remained stable. Baseline levels of β-CTX (0.31 ± 0.16 ng/mL vs. 0.42 ± 0.19 ng/mL, p = 0.008) and P1NP (32.96 ± 14.00 ng/mL vs. 55.82 ± 26.87 ng/mL, p = 0.05) were lower in HIV-infected patients compared with controls, respectively. Both β-CTX and P1NP levels increased after onset of HAART until week 48, and remained elevated during the next 48 weeks. 25-OH vitamin D in HIV-infected patients was lower at baseline compared to healthy controls, but this difference was not statistically significant. PTH, however, was higher in HIV patients at baseline, and showed a significant increase throughout the study.

Conclusions

Chinese adults with HIV-1 infection have low bone turnover prior to HAART as well as lower raw BMD of the lumbar spine compared with healthy controls, with further bone loss occurring following the initiation of HAART. The long-term clinical implications of these findings remain unclear at this time.

Oral bioavailability and bone-sparing effects of estetrol in an osteoporosis model

OBJECTIVES

To measure the oral bioavailability of estetrol (E(4)) in rats relative to its subcutaneous administration and to test the bone-sparing effect of oral E(4) compared to that of ethinylestradiol (EE).

METHODS

In the bioavailability study, E(4) was administered as a single dose of 0.05, 0.5 or 5.0 mg/kg orally or subcutaneously to female rats. Plasma was analyzed using an LC-MS/MS method. The bone study was conducted in 3-month-old female rats assigned to the following seven treatment groups of ten animals each: no treatment; sham-operated + vehicle; bilaterally ovariectomized (OVX) + vehicle; OVX + E(4) 0.1, 0.5, or 2.5 mg/kg/day and OVX + EE 0.1 mg/kg/day. Once-daily treatment by oral gavage was given for 4 weeks and the following measurements were performed: serum osteocalcin, bone mineral density, bone mineral content and bone mineral area of lumbar vertebrae L3-L6, peripheral quantitative computed tomography of the left tibiae and the biomechanical properties of the distal femora.

RESULTS

Oral bioavailability of E(4), relative to that of subcutaneous dosing, was 70% and above at the 0.05 and 0.5 mg/kg doses based on the AUC(0-t last). Subcutaneous dosing provided significantly higher E(4) levels at the 1-h time point only, and was comparable to oral dosing after 0.5, 2, 4 and 8 h. In the bone study, E(4) dose-dependently and significantly (1) inhibited the OVX-related increase in osteocalcin levels, (2) increased bone mineral density and content, and (3) increased bone strength, all attenuated by ovariectomy. In this rat model, the relative potency of the highest dose of E(4) (2.5 mg/kg/day) was comparable to the EE dose, used as positive control.

CONCLUSIONS

Estetrol exhibits high oral bioavailability in the rat, a species considered relevant for pharmacological studies that are predictive for effects on human bone. Oral administration of E(4) conveys dose-dependent bone-sparing effects of high-quality bone in estrogen-depleted OVX rats. Based on its bone-sparing effects, its oral bioavailability and its preclinical safety and efficacy profile, E(4) may be superior to other estrogens and is a potential drug for the prevention of osteoporosis in postmenopausal women.

Estetrol review: profile and potential clinical applications

In this review paper, the existing information on the human fetal steroid estetrol (E4) has been summarized. In the past, E4 was considered as a weak estrogen and interest disappeared. However, recent new research has demonstrated that E4 is a potent, orally bioavailable, natural human fetal selective estrogen receptor modulator, since it acts in the rat as an estrogen on all tissues investigated except breast tumor tissue, where it has estrogen antagonistic properties in the presence of estradiol. Based on its safety data, its pharmacokinetic properties, its pharmacological profile and the results of first human studies, E4 may be suitable as a potential drug for human use in applications such as hormone replacement therapy (vaginal atrophy, hot flushes), contraception and osteoporosis. Additional areas worth exploring are the treatment of breast and prostate cancer, hypoactive sexual desire disorder and topical use (wrinkles) in women, auto-immune diseases, migraine, cardiovascular applications and the treatment of selected obstetric disorders.