The prevalence patterns and risk factor profiles of poor muscle health and its associated components in multiethnic older Asians: The PIONEER study

BACKGROUND

We aim to determine the multiethnic patterns of the prevalence and associated factors of poor muscle health and its associated components in older Chinese, Malays, and Indian Asian adults.

METHODS

We included 2199 participants (mean age ± SD: 72.9 ± 8.3 years; 54.3% female) from the baseline assessment of the Population Health and Eye Disease Profile in Elderly Singaporeans (PIONEER; 2017-2022) cohort study. Poor muscle health was defined as the presence of either low muscle mass (DEXA), or low muscle strength (handgrip strength), or low physical performance (gait speed). Its components include poor muscle function (low muscle strength and/or low physical performance without low muscle mass), pre-sarcopenia (low muscle mass only), and any sarcopenia (low muscle mass with low muscle strength and/or low physical performance). Sociodemographic, clinical, and lifestyle factors were assessed using biochemistry, clinical tests, and validated questionnaires. Regression models were utilized to evaluate the independent risk factors of poor muscle health and its components.

RESULTS

The national census-adjusted prevalence of poor muscle health (88%) was similar across the three ethnic groups. However, Chinese individuals had higher prevalence of pre-sarcopenia and any sarcopenia, and a lower prevalence of poor muscle function compared with Indians or Malays. We observed ethnic differences in modifiable risk factors (low physical activity, diabetes, osteoporosis, and obesity) of poor muscle health and its components. Although obesity was protective of pre-sarcopenia (RRR = 0.19, 95% CI: 0.11, 0.36) and any sarcopenia (RRR = 0.29, 95% CI: 0.18, 0.47) in the overall population and across ethnic groups, it was associated with 1.7 times (95% CI: 1.07, 2.67) the likelihood of poor muscle function in the entire population.

CONCLUSIONS

Almost 90% of community dwelling Singaporean aged ≥60 years have poor muscle health across the three ethnic groups with ethnic disparities in modifiable risk factors, highlighting an urgent need for community-wide targeted interventions to promote muscle health.

Arthralgia in midlife Singaporean women: the Integrated Women's Health Program (IWHP)

OBJECTIVE

Arthralgia is a common menopausal complaint in midlife women, and its causes remain unclear. We examined the prevalence of menopausal arthralgia with various factors including sleep quality, depression/anxiety, muscle strength and physical performance among midlife Singaporean women.

METHODS

The Integrated Women's Health Program (IWHP) comprised 1120 healthy, community-dwelling women of Chinese, Malay or Indian ethnicities (aged 45-69 years) attending well-women clinics at the National University Hospital, Singapore. Sociodemographic, menopausal, reproductive and health data were obtained with validated questionnaires. Muscle strength, physical performance and dual-energy X-ray absorptiometry were measured. Women with moderate to very severe symptoms using the Menopause Rating Scale were classified as having arthralgia. Multivariable logistic regression analyses examined risk factors for arthralgia.

RESULTS

One-third of the participants reported arthralgia, and 12.7%, 16.2% and 71.2% were in the premenopausal, perimenopausal and postmenopausal period, respectively. Menopausal symptoms, such as vaginal dryness (adjusted odds ratio [aOR]: 2.64, 95% confidence interval [CI]: 1.64, 4.24) and physical/mental exhaustion (aOR: 2.83, 95% CI: 1.79, 4.47), were independent risk factors for arthralgia. Poor muscle strength (aOR: 2.20, 95% CI: 1.29, 3.76), obesity (aOR: 1.94, 95% CI: 1.13, 3.32) and rheumatoid arthritis (aOR: 7.73, 95% CI: 4.47, 13.36) were also independently associated with arthralgia after adjustment for confounders.

CONCLUSIONS

Arthralgia in midlife Singaporean women was associated with menopausal symptoms of vaginal dryness and physical and mental exhaustion. Women with poor muscle strength were more likely to experience menopausal arthralgia.

Associations between hypertension with reproductive and menopausal factors: An integrated women's health programme (IWHP) study

BACKGROUND

Women are less likely to have classic cardiovascular risk factors than men, and events during their reproductive and menopausal years may increase hypertension risk. The aim of this study is to examine woman-specific factors, including menstrual, reproductive and pregnancy complications, in relation to the prevalence of hypertension in mid-life Asian women.

METHODS

This is a cross-sectional study of 1146 healthy women aged 45-69 years, from a multi-ethnic Asian cohort. The women completed an extensive questionnaire that included their sociodemographic details, medical history, lifestyle and physical activity, and reproductive and menopausal history. They also underwent objectively measured physical performance tests and a dual X-ray absorptiometry scan. Hypertension was defined as a systolic BP ≥140 and/or diastolic BP ≥90mm Hg, past diagnosis by a physician, or use of antihypertensive medications. Multivariable logistic regression was used to assess the independent risk factors for hypertension.

RESULTS

The average age of the 1146 women analysed was 56.3 (SD 6.2) years, and 55.2 percent of them were hypertensive. The prevalence of gestational diabetes and gestational hypertension was 12.6% and 9.4%, respectively. Besides age, abnormal menstrual cycle length at 25 years of age (OR:2.35, CI:1.34-4.13), preeclampsia (OR:2.46, CI:1.06-5.74), increased visceral adiposity (OR:4.21, CI:2.28-7.79) and reduced physical performance (OR:2.83, CI:1.46-5.47) were independently associated with hypertension in Asian women.

CONCLUSIONS

Our findings highlight the necessity of including features of menstrual and reproductive history as possible indicators of hypertension risk in cardiovascular disease risk assessment and prevention among Asian women. Reducing visceral adiposity and exercise to improve physical performance may help women avoid developing hypertension.

Individual and combined associations of sarcopenia, osteoporosis and obesity with frailty in a multi-ethnic asian older adult population

BACKGROUND

We explored the relationships between sarcopenia (SP), osteoporosis (OP), obesity (OB), (alone and in combination) with physical frailty (PF) in a multi-ethnic, population-based study of Asians aged ≥ 60 years.

METHODS

Participants were enrolled from the PopulatION HEalth and Eye Disease PRofile in Elderly Singaporeans Study (PIONEER) study. PF was defined using the modified Fried phenotype; SP using the Asian Working Group for Sarcopenia 2019; OP using bone mineral density scores; and OB using the fat mass index. Modified Poisson regression models investigated the associations between exposures and PF, and the relative excess rates of PF due to interactions (RERI) to determine synergistic or antagonistic interactions.

RESULTS

Of the 2643 participants, 54.8% was female; and 49.8%, 25.1%, 25.0% were Chinese, Indians, and Malays, respectively. 25%, 19.0% and 6.7% participants had OB only, SP only, and OP only, respectively. A total of 356 (17.5%), 151 (7.4%) and 97 (4.8%) had osteosarcopenia (OSP), sarcopenic obesity (SOB) and osteo-obesity (OOB), respectively; while 70 (3.5%) had all 3 morbid conditions (osteosarcopenic obesity, OSO). Both SP only and OB only were strongly associated with increased rates of PF (RR: 2.53, 95% CI: 1.95, 3.29; RR: 2.05, 95% CI: 1.58, 2.66 respectively); but not OP. Those with OSP, OOB and SOB were also associated with high risks of PF (RR: 2.82, 95% CI: 2.16, 3.68; RR: 2.34, 95% CI: 1.69, 3.23; and RR: 2.58, 95% CI: 1.95, 3.41, respectively) compared to robust individuals. Critically, individuals with OSO had the highest relative risk of having PF (RR: 3.06, CI: 2.28, 4.11). Only the sarcopenia-obesity interaction was significant, demonstrating negative synergism (antagonism). The concurrent presence of SP and OB was associated with a 100% lower rate of PF compared to the sum of the relatively rates of SP only and OB only.

CONCLUSION

The prevalence of SP, OB and OP, alone and combined, is substantial in older Asians and their early identification is needed to mitigate the risk of frailty. OB may interact with SP in an antagonistic manner to moderate rates of frailty. Further longitudinal studies are needed to address causality and mechanistic underpinnings our findings.

Menopausal symptoms in midlife Singaporean women: Prevalence rates and associated factors from the Integrated Women's Health Programme (IWHP)

OBJECTIVE

Menopausal symptoms can substantially impact quality of life. We studied somatic, psychological, and urogenital symptoms and their associated factors.

DESIGN

Cross-sectional study of healthy midlife Singaporean women from three major Asian ethnic groups.

METHODS

In 2014-16, women aged 45 to 69 attending well-woman clinics at the National University Hospital Singapore completed the Menopause Rating Scale (MRS). Sociodemographic, reproductive, medical, anthropometric, body composition, and physical performance characteristics were assessed using validated questionnaires and strict protocols. We analysed sub-scales and total scores by median split, and adjusted odds ratios using multivariable logistic regression.

RESULTS

Of the 1054 eligible women, 62.6 % reported at least one moderate to extremely severe symptom. The top five menopausal symptoms were joint and muscle discomfort, sleep problems, vaginal dryness, physical and mental exhaustion, and hot flushes. Higher total scores on the MRS were associated with moderate disability (adjusted odds ratio: 9.80, 95 % confidence interval: 2.88-33.34), poorer self-rated health status (2.18, 1.60-2.97), menstrual irregularity at 25 years (1.63, 1.07-2.49), and slower chair stands (1.49, 1.09-2.03). Age ≥65 (0.54, 0.30-0.94) and a lower level of education (0.45, 0.26-0.76) had significant inverse associations with total MRS score.

CONCLUSIONS

Menopausal symptoms were associated with disability, poorer health status, and weaker lower-body muscle strength. These data add to the limited Asian evidence and raise the profile of this important area of health.

Factors associated with deep infiltrating endometriosis, adenomyosis and ovarian endometrioma

Introduction: To compare epidemiological features and clinical presentations of deep infiltrating endometriosis with endometrioma and adenomyosis, as well as to identify risk factors for the respective histologically confirmed conditions. Method: Patients undergoing index surgery at the National University Hospital, Singapore for endometriosis or adenomyosis over a 7-year period—from 2015 to 2021—were identified from hospital databases using the Table of Surgical Procedures coding. Social and epidemiological features of cases with histologically confirmed diagnoses of endometrioma only, adenomyosis only, and deep infiltrating endometriosis were compared. Significant variables from univariate analysis were entered into 3 binary multivariate logistic regression models to obtain independent risk factors for: deep infiltrating endometriosis versus endometrioma only, deep infiltrating endometriosis versus adenomyosis only, and adenomyosis only versus endometrioma only. Results: A total of 258 patients were included with 59 ovarian endometrioma only, 47 adenomyosis only, and 152 deep infiltrating endometrioses. Compared to endometrioma only, deep infiltrating endometriosis was associated with higher rates of severe dysmenorrhoea (odds ratio [OR] 2.80, 95% confidence interval [CI] 1.02–7.70) and out-of-pocket private surgical care (OR 4.72, 95% CI 1.85–12.04). Compared to adenomyosis only, deep infiltrating endometriosis was associated with a higher fertility desire (OR 13.47, 95% CI 1.01–180.59) and a lower body mass index (OR 0.89, 95% CI 0.79–0.99). In contrast, heavy menstrual bleeding was the hallmark of adenomyosis, being less common in patients with endometriosis. Conclusion: Deep infiltrating endometriosis is associated with severe dysmenorrhoea, pain related to urinary and gastrointestinal tracts, higher fertility desire and infertility rate. Patients with pain symptomatology and subfertility should be referred early to a tertiary centre with the capability to diagnose and manage deep infiltrating endometriosis. Keywords: Adenomyosis, deep infiltrating endometriosis, obstetrics and gynaecology, ovarian endometrioma, public health

Association of sarcopenia with important health conditions among community-dwelling Asian women

This study aimed to examine sarcopenia prevalence using the Asian Working Group for Sarcopenia 2019 (AWGS) and the Foundation for the National Institutes of Health (FNIH) definitions, and their associations with important health conditions affecting midlife Singaporean women. Muscle mass and function were objectively assessed in 1201 healthy community-dwelling subjects aged 45-69 years under the Integrated Women's Health Program (IWHP). Dual-energy X-ray absorptiometry (DXA), handgrip strength and the Short Physical Performance Battery (SPPB) were measured, and the relationship between sarcopenia with hypertension, type 2 diabetes (T2DM), osteoporosis, depression/anxiety, and urinary incontinence were examined using binary logistic regression models. Sarcopenia prevalence was 18.0% and 7.7% by the AWGS and FNIH criteria respectively. Osteoporosis (aOR: 1.74, 95% CI: 1.02, 2.94) and T2DM (aOR: 1.98, 95% CI: 1.14, 3.42) was positively associated with AWGS- and FNIH-defined sarcopenia respectively, while hypertension was not, after adjustment for age, ethnicity, education levels and menopausal status. A negative percent agreement of 95.6% suggests good agreement between the criteria in the absence of sarcopenia. Even though they represent a single concept, sarcopenia by either criterion differed in their relationships with diabetes and osteoporosis, suggesting the need for further rationalization of diagnostic criteria.

Associations of reading language preference with muscle strength and physical performance: Findings from the Integrated Women's Health Programme (IWHP)

BACKGROUND

The contribution of language preference and ethnicity to muscle strength and physical performance is unclear. We examined the associations of reading language preferences with muscle strength and performance in Chinese women and compared them to other ethnicities.

METHODS

The Integrated Women's Health Programme (IWHP) cohort comprised community-dwelling, midlife Singaporean women aged 45-69. Ethnic Chinese women could choose between the English or Chinese versions of the questionnaire. Malay and Indian women were presented with the English version. Sociodemographic, reproductive, anthropometric characteristics were obtained. Hand grip strength and physical performance were objectively assessed. Visceral adiposity (VAT) was determined by Dual-energy X-ray Absorptiometry. Multivariable logistic regression models were used to determine independent associations of language preference/ethnicity with muscle strength and physical performance.

RESULTS

The cohort comprised 1164 women (mean age: 56.3±6.2 years); 84.1% Chinese, 5.6% Malay, and 10.3% Indian. 315 Chinese participants (32.2%) had a Chinese-language reading preference (CLP). CLP women tended to be parous, of a lower socioeconomic status (lower proportions received tertiary education, lower employment rates and lower household income), and engaged in less physical activity compared to Chinese women with an English-language preference (ELP). This translated to a weaker hand grip strength (aOR: 1.56; 95%CI: 1.07-2.27), slower repeated chair stand (1.55; 1.12-2.13), poorer balance on tandem stand (2.00; 1.16-3.47), and a slower gait speed (1.62; 1.06-2.47). Compared to ELP women, Malay women had higher odds of poor hand grip strength (1.81; 1.12-2.93) while Indians had a higher odd of poor balance on one-leg stand (2.12; 1.28-3.52) and slow gait speeds on usual (1.88; 1.09-3.25) and narrow walks (1.91; 1.15-3.17).

CONCLUSIONS

Chinese language reading preference was associated with inferior muscle strength and physical performance. Such disparities were largest and most consistent in the CLP group, followed by Indian and Malay women compared to the ELP group. Further studies should determine if CLP-associated muscle weakness can predict adverse health outcomes.

Factors associated with poor sleep quality in midlife Singaporean women: The Integrated Women's Health program (IWHP)

Objective

To examine factors associated with poor sleep quality in community-dwelling midlife women.

Methods

Healthy women (aged 45-69 years) of Chinese, Malay and Indian ethnicities attending well-women clinics at the National University Hospital, Singapore, completed the Pittsburgh Sleep Quality Index (PSQI). A PQSI score >5 denoted poor sleep quality. The women filled out validated questionnaires covering menopausal and genito-urinary symptoms, and mental health. Physical performance was measured. Bone mineral density and visceral adiposity were assessed by dual energy X-ray absorptiometry. Binary logistic regression analyses assessed independent factors for poor sleep.

Results

Poor sleep quality was reported in 38.2% of women (n = 1094, mean age: 56.4 ± 6.2 years). Indian women had higher sleep disturbance scores than Chinese women (mean ± SD: 1.33 ± 0.58 vs 1.17 ± 0.49). Malays experienced more daytime dysfunction (0.54 ± 0.60 vs 0.33 ± 0.55) and had a higher overall PSQI score (6.00 ± 3.31 vs 5.02 ± 2.97) than the Chinese. A low education level (aOR: 1.76, 95% CI: 1.01-3.05), feelings of irritability (2.67, 1.56-4.60) and vaginal dryness (1.62, 1.03-2.54) were associated with poor sleep quality in the adjusted multivariable model. Women with moderate to severe disability were ∼3 times (2.99, 1.20-7.44) more likely to experience less than ideal sleep quality, while urinary incontinence (1.53, 1.08-2.17) and breast cancer history (2.77, 1.36-5.64) were also associates of poor sleep quality.

Conclusion

Self-reports of education level, irritability, vaginal dryness, disability, urinary incontinence, and breast cancer history were independently related to poor sleep. Ethnic differences suggest the need for targeted interventions among the ethnic groups.

The Associations between Upper and Lower Body Muscle Strength and Diabetes among Midlife Women

We hypothesized that a combined index of upper and lower body muscle strength would be more strongly associated with diabetes than either measure alone. Women recruited into the Integrated Women's Health Program had their handgrip strength (HGS) measured using a dynamometer and underwent a timed 5-repetition chair stand (RCS) test. HGS < 18 kg and RCS performance ≥ 12 s assessed upper and lower body strength, respectively, both individually and combined in a muscle strength index (MSI). Diabetes was defined as physician-diagnosed, use of anti-diabetic medication, or fasting blood glucose ≥ 7.0 mmol/L. Binary logistic regression examined the associations between muscle strength and diabetes. Of 1170 midlife women, 12.1% had diabetes. A low HGS was independently associated with diabetes (aOR: 1.59, 95% CI: 1.03, 2.44). Prolonged RCS was also associated with diabetes (aOR: 1.59, 95% CI: 1.09, 2.30), but this was not independent of visceral adiposity and muscle mass. A poor MSI had higher odds of diabetes (aOR: 2.37, 95% CI: 1.40, 4.03), independent of age, ethnicity, education level, menopausal status, smoking, alcohol consumption, physical activity, height, visceral adiposity, and muscle mass. The combination of both upper and lower body muscle strength into a composite MSI was more strongly associated with diabetes than either weak HGS or prolonged RCS alone in midlife women.

Sexual inactivity and sexual dysfunction in midlife Singaporean women: A prospective cross-sectional study of prevalence and risk factors

OBJECTIVES

To examine factors relating to both sexual inactivity and sexual dysfunction in midlife Singaporean women.

STUDY DESIGN

Sociodemographic, medical/lifestyle factors, physical activity, BMI, handgrip strength (HGS) and physical performance data collected from healthy Chinese, Indian, and Malay women, aged 45-69 years, attending gynaecology clinics.

MAIN OUTCOME MEASURES

Sexual inactivity and sexual dysfunction (defined as total score ≤ 26.55) assessed using the Female Sexual Function Index (FSFI).

RESULTS

1048 women completed the FSFI. Mean (±SD) age was 56.2 (±6.2). Sexual inactivity was reported by 43.2% and was positively associated with older age [55-64 years (aOR 2.0, 95% CI 1.3-3.0) and ≥65 years (aOR 2.5, 95% CI 1.2-5.1)], younger menarche (aOR 1.8, 95% CI 1.3-2.5), lowest education (aOR 2.1, 95% CI 1.2-3.6), lowest income (aOR 1.8, 95% CI 1.1-2.8), unmarried (aOR 4.0, 95% CI 2.6-6.4), nulliparity (aOR 1.9, 95% CI 1.1-3.4), and BMI <18.5 kg/m² (aOR 2.7, 95% CI 1.3-5.6). Among the sexually active, sexual dysfunction was identified in 70.3%. Sexual dysfunction was positively associated with menopause ≥10 years (aOR 2.4, 95% CI 1.1-5.0), nulliparity (aOR 3.0, 95% CI 1.1-9.8), moderate/severe vaginal dryness (aOR 13.8, 95% CI 4.8-38.7) and HGS <18 kg (aOR 1.9, 95% CI 1.1-3.2) and negatively associated with use of menopausal hormone therapy (aOR 0.3, 95% CI 0.1-0.6).

CONCLUSION

This, the largest Singaporean sexual function study, is the first to include physical performance in a healthy population. Most were sexually active but reported dysfunction. Novel associations included underweight BMI with sexual inactivity and weaker HGS and Malay ethnicity with greater and less sexual dysfunction, respectively.

Randomized, double-blind, placebo-controlled trial to examine the safety, pharmacokinetics and effects of Epimedium prenylflavonoids, on bone specific alkaline phosphatase and the osteoclast adaptor protein TRAF6 in post-menopausal women

BACKGROUND

Fragility fractures due to menopausal osteoporosis are a major cause of morbidity and mortality. Osteoporotic medications have substantial side effects that limit long term use.

HYPOTHESES

Ingestion of a purified extract of Epimedium spp. (EP) is safe, can increase serum levels of prenylflavonoid metabolites, exert positive changes in bone specific alkaline phosphatase (BSAP), suppress of tumor necrosis factor receptor associated factor 6 (TRAF6) protein in osteoclast-precursor monocytes in peripheral blood and therefore have the potential to reduce post-menopausal bone loss.

STUDY DESIGN & METHODS

Healthy postmenopausal women were randomized in a double-blind fashion to consume either EP prenylflavonoid extract (740 mg daily) or placebo daily for 6 weeks. The main outcome measures were safety and pharmacokinetics of EP flavonoids. Fasting blood was collected at 3- and 6-weeks, and two weeks after stopping medication for safety evaluations and measurement of BSAP. Peripheral blood monocytes were harvested for measurement of TRAF6 levels. Serum levels of the EP metabolites icariin, icariside I & II, icaritin and desmethylicaritin were measured using tandem mass spectrometry, and non-compartmental pharmacokinetic analyses performed using WinNonlin software.

RESULTS

Between October 2018 and Jun 2020, 58 postmenopausal women, aged 57.9 ± 8.9 years, were randomized and completed the study. Consumption of EP prenylflavonoids was not associated with any significant adverse symptoms, with no changes in hepatic, hematological, and renal parameters observed. The main metabolites detected in sera after ingestion of EP prenylflavonoid capsules were desmethylicaritin, icaritin and icariside II. Icariin and icariside I were below detection levels. Ingestion of EP prenylflavonoids induced a median C_max and AUC_0→∞ for desmethylicaritin of 60.9 nM, and 157.9 nM ×day, respectively; and were associated with higher levels of BSAP (p < 0.05) and a trend (p = 0.068) towards lower levels of TRAF6 in peripheral blood monocytes eight weeks after commencing prenylflavonoid ingestion. Prenylflavonoid metabolites were not detected in the sera of placebo participants.

CONCLUSIONS

Despite the widespread consumption of EP extracts, the safety, mechanisms of action of their bioactive compounds, and therapeutic indications in humans are unknown. Daily consumption of EP prenylflavonoids for six weeks was safe. The predominant metabolite in sera was desmethylicaritin. Rise in prenylflavonoid metabolites was associated with higher levels of the bone anabolic marker BSAP, suggesting potential therapeutic value for post-menopausal osteoporosis.

Higher risk of type 2 diabetes in women with hyperandrogenic polycystic ovary syndrome

OBJECTIVE

To assess the risk of type 2 diabetes (T2D) in women with polycystic ovary syndrome (PCOS) in relation to body mass index (BMI) and the hyperandrogenic (HA) PCOS phenotype.

DESIGN

Population-based cohort study.

SETTING

Data from six Swedish national registers, with participants being followed for a maximum of 19 years.

PATIENT(S)

All women with an International Statistical Classification of Diseases and Related Health Problems, version 10, diagnosis of PCOS, androgen excess, or anovulatory infertility born between 1950 and 1999 (n = 52,535) were identified in the Patient Register. The HA PCOS phenotype was defined by two filled prescriptions for anti-androgenic drugs. For each woman with PCOS, five control women (n = 254,624) were randomly chosen from the Total Population Register, matched for age and geographic area.

INTERVENTION(S)

No interventions were performed.

MAIN OUTCOME MEASURE(S)

International Statistical Classification of Diseases and Related Health Problems, version 10, diagnosis of T2D or prescription of antidiabetic treatment other than metformin.

RESULT(S)

The cumulative incidence rates of T2D were 1.3%, 4.4%, and 14.2% in controls (non-PCOS women) and women with normoandrogenic (NA) and HA PCOS, respectively. After adjustment for BMI, women with PCOS had a twofold higher rate of T2D than non-PCOS women (adjusted hazard ratio, 2.52 [95% confidence interval, 2.15-2.96]). Women with HA PCOS had a higher rate of T2D than those with NA PCOS (adjusted hazard ratio, 3.86 [95% confidence interval, 3.16-4.72]).

CONCLUSION(S)

Polycystic ovary syndrome is an independent risk factor for T2D, even after adjustment for BMI. Women with the HA PCOS phenotype face an even higher risk of T2D than those with the NA PCOS phenotype.

Blood pressure and adiposity in midlife Singaporean women

Hypertension is a major risk factor for cardiac events and stroke. Visceral adipose tissue (VAT) is known to increase the risk of incident hypertension in adults. Although adiposity has been linked to markers of inflammation, few studies have examined these markers as potential mediators of the association between visceral adiposity and elevated blood pressure. We evaluated sociodemographic, reproductive, and lifestyle risk factors for elevated blood pressure among midlife Singaporean women. A total of 1189 women, with a mean age of 56.3 ± 6.2 years, from the Integrated Women's Health Program (IWHP) at National University Hospital, Singapore were studied. Hypothesized risk factors and levels of inflammatory markers were examined in relation to systolic blood pressure (SBP) and diastolic blood pressure (DBP) using multivariable linear regression models. Prehypertension (SBP 120-139 mmHg and/or DBP 80-89 mmHg) and hypertension (SBP ≥140 mmHg and/or DBP ≥90 mmHg) were observed in 518 (43.6%) and 313 (26.3%) women, respectively. Compared to women in the lowest tertiles, women in the middle and upper tertiles of VAT had 7.1 (95% CI, 4.4, 9.8) mmHg and 10.2 (95% CI, 6.7, 13.7) mmHg higher adjusted SBP, respectively. Nulliparous older women with a lower education level and those with no or mild hot flashes also had a significantly higher adjusted SBP. No significant independent risk factors were observed for DBP. Adjustments for IL-6, TNF-α, and hs-CRP did not attenuate the association between VAT and SBP. In summary, we found an independent positive association between VAT and SBP. Elevated levels of inflammatory markers did not mediate the increase in SBP in women with high VAT.

Effect of body mass index (BMI) on phenotypic features of polycystic ovary syndrome (PCOS) in Singapore women: a prospective cross-sectional study

Background

A diagnosis of Polycystic Ovary Syndrome (PCOS) and its related phenotypic features including increased hair growth can affect a woman’s social and emotional well-being. We aim to determine firstly, if excess body weight affects menstrual cycle length, excessive hair growth and other phenotypic features in healthy women without PCOS and secondly, whether having PCOS exacerbates the effects of high body mass index (BMI).

Methods

A prospective cross-sectional study involving healthy women (21–45 years) recruited at an annual health screen for hospital staff and volunteers from the university community, and PCOS cases referred to tertiary gynecological clinics in Singapore. To dissect the independent and/or combinatorial effects of PCOS and BMI on the phenotypic features, subjects were divided into four categories: non-PCOS (normal BMI), non-PCOS (high BMI), PCOS (normal BMI), and PCOS (high BMI). General linear modelling was performed to compare clinical, ovarian, hormonal and metabolic parameters across these four categories.

Results

Of 389 participants, 134 (34.4%) were classified as PCOS and the remaining 255 (65.6%), as the non-PCOS population. Overall 45.2% of women had high BMI (≥ 23). Compared to non-PCOS subjects, women with PCOS had a higher BMI (mean (SD): 25.14 ± 6.46 vs 23.08 ± 4.36, p < 0.001). Women with PCOS and high BMI had increased hair growth with modified Ferriman-Gallwey (mFG) scores that were 2.96-fold higher versus healthy-normal BMI women (mean difference; 1.85, 95% CI 0.80–2.90). Compared to healthy-high BMI women, PCOS women with high BMI had significantly higher mean differences in mFG scores (1.79, 95% CI 0.64–2.93). In PCOS women, having high BMI also significantly increased mFG scores by 1.85-fold (mean difference; 1.82. 95% CI 0.52–3.12). This effect was mirrored by the additive effect of BMI and PCOS on free androgen index. No independent effect of high BMI on rates of oligomenorrhoea, antral follicle count, ovarian volume or serum androgens were observed.

Conclusions

We observed an additive effect of body weight to increase hair growth in women with PCOS. Maximum mFG scores were present in PCOS women with high BMI. Such increases in mFG score may affect the self-esteem of women with PCOS.

Menopausal osteoporosis: screening, prevention and treatment

Screening for osteoporosis in women can be based on age and weight, using the Osteoporosis Screening Tool for Asians and assessment for other risk factors such as early menopause, Chinese ethnicity and other secondary factors. Based on the resulting risk profile, women can be triaged to dual-energy X-ray absorptiometry (DEXA) scanning for definite diagnosis of osteoporosis. Treatment should be considered in women with previous fragility fractures, DEXA-diagnosed osteoporosis and high risk of fracture. Exercise improves muscle function, can help prevent falls and has moderate effects on improvements in bone mass. Women should ensure adequate calcium intake and vitamin D. Menopausal hormone therapy (MHT) effectively prevents osteoporosis and fractures, and should be encouraged in those aged < 50 years. For women aged < 60 years, MHT or tibolone can be considered, especially if they have vasomotor or genitourinary symptoms. Risedronate or bisphosphonates may then be reserved for those aged over 60 years.

Predictors of circulating vitamin D levels in healthy mid-life Singaporean women

Vitamin D levels were lowest in Indian and Malay compared to Chinese women, and in younger and employed women. The main reason for hypovitaminosis D in study women was deficient cutaneous production. Supplementation in regions with abundant sunshine should consider ethnicity and opportunities for exposure to sunlight.

INTRODUCTION

Little is known about variations in circulating vitamin D levels in multiethnic mid-life women living in communities with year-round sunlight. Our study describes the circulating vitamin D levels and their sociodemographic predictors in mid-life Singaporean women.

METHODS

Prospective cross-sectional study of healthy Singaporean women, age 45-69 years, who were not consuming vitamin D supplements. Total 25-hydroxyvitaminD [25(OH)D], the sum of 25(OH)D₂ and 25(OH)D₃, was measured by liquid chromatography-tandem mass spectrometry.

RESULTS

The analytic cohort of 721 women, mean age 55.2±6.0 (±SD) years, was of Chinese (82%), Indian (11%), and Malay (7%) ethnicity. Their mean 25(OH)D level was 24.8±7.8ng/mL. One-third (32.6%) of the women had deficient 25(OH)D (≤20ng/mL) and 3.5% were severely deficient (<12ng/mL). 25(OH)D₃ comprised 98% of the total circulating 25(OH)D level. Adjusted mean total 25(OH)D levels were significantly lower for women of Indian and Malay (vs Chinese) ethnicity, who were premenopausal or working outside the home. Indian and Malay women had higher odds (adjusted OR 5.58 (95% CI 3.22, 9.87) and 3.83 (95% CI 1.97, 7.57), respectively) of low 25(OH)D compared to Chinese women. Obesity was not an independent predictor of low 25(OH)D, as its strong crude association was confounded by ethnicity. The adjusted odds of low 25(OH)D was reduced in women ≥65 years (adjusted OR 0.37 (95% CI 0.14, 0.87)) compared to those aged 45-55 years.

CONCLUSION

One-third of mid-life Singaporean women were 25(OH)D deficient, and the major independent predictors of deficiency were Indian or Malay ethnicity and younger age. Vitamin D supplementation in mid-life women should be targeted to those with documented deficiency or limited cutaneous production.

Risk factors for insulin resistance in midlife Singaporean women

OBJECTIVES

To understand the extent to which risk factors for insulin resistance are mediated by body mass index (BMI), visceral adipose tissue (VAT), physical activity and performance, and the inflammatory markers interleukin (IL)-6, tumor necrosis factor (TNF)- α, and high-sensitivity C-reactive protein (hs-CRP).

STUDY DESIGN

A wide range of socio-demographic characteristics of Chinese, Malay and Indian women attending routine gynecologic care in Singapore were prospectively collected. Physical performance was objectively measured by hand grip strength and the Short Physical Performance Battery. Percent VAT was determined by dual-energy X-ray absorptiometry. Fasting serum concentrations of glucose, insulin, IL-6, TNF- α, and hs-CRP were measured.

MAIN OUTCOME MEASURE

was insulin resistance, expressed as the homeostatic model assessment of insulin resistance (HOMA-IR).

RESULTS

1159 women were analyzed, mean age 56.3 (range 45-69) years, comprising women of Chinese (84.0%), Indian (10.2%), and Malay (5.7%) ethnic origins. The adjusted mean differences for obesity (0.66, 95% CI 0.32-1.00), VAT area in the highest vs lowest tertile (1.03, 95% CI 0.73-1.34), low physical performance (0.63, 95% CI 0.05-1.24), and highest vs lowest tertile of TNF- α (0.35, 95% CI 0.13-0.57) were independently associated with HOMA-IR. Women of Malay and Indian ethnicity had higher crude HOMA-IR than Chinese women. However, after adjustment for obesity, VAT, physical performance, and TNF- α, no differences in mean HOMA-IR remained, when comparing Chinese women with those of Malay ethnicity (0.27, 95% CI -0.12 to 0.66) and with those of Indian ethnicity (0.30, 95% CI -0.01 to 0.66).

CONCLUSIONS

Insulin resistance was independently associated with obesity, high VAT, low physical performance, and high levels of TNF- α in midlife Singaporean women. These variables entirely explained the significant differences in insulin resistance between women of Chinese, Malay and Indian ethnicity.

Risk Factors and Trends Associated With Mortality Among Adults With Hip Fracture in Singapore

IMPORTANCE

Examining trends in mortality following hip fracture and its associated factors is important for population health surveillance and for developing preventive interventions.

OBJECTIVE

To examine temporal trends in, and risk factors associated with, mortality following hip fracture over 18 years in Singapore.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective, population-based cohort study included men and women aged 50 years and older admitted to Singapore hospitals for first hip fracture identified and followed up from 2000 to 2017. Demographic information, fracture type, and Charlson Comorbidity Index (CCI) score were retrieved from nationwide claims data, and mortality data were from the National Death Registry. Data were analyzed from August 2018 to December 2019.

MAIN OUTCOMES AND MEASURES

Adjusted hazard ratios (aHRs) and their 95% confidence intervals were estimated using Cox proportional hazards regression. Kaplan-Meier life table methods were used to calculate survival following the hip fracture on a cohort basis. The crude survival over time since fracture was compared by sex, age group, ethnicity, CCI, and fracture type. Standardized mortality ratios (SMRs) were calculated using all-cause mortality obtained from Singapore population life tables.

RESULTS

Among 36 082 first inpatient admissions for hip fractures (mean [SD] patient age, 78.2 [10.1] years; 24 902 [69.0%] female; 30 348 [84.1%] Chinese, 2863 [7.9%] Malay, 1778 [4.9%] Indian, and 1093 [3.0%] other ethnicity), elevated rates of mortality were observed for male sex (aHR, 1.46; 95% CI, 1.41-1.52), Malay ethnicity (aHR, 1.23; 95% CI, 1.15-1.30 vs Chinese ethnicity), older age (aHR, 5.20; 95% CI, 4.27-6.34 for age ≥85 years vs 50-54 years), high CCI score (aHR, 3.62; 95% CI, 3.42-3.84 for CCI ≥6 vs CCI of 0), trochanteric fractures (aHR, 1.11; 95% CI, 1.06-1.16 vs cervical fractures), and earlier cohorts (aHR, 0.59; 95% CI, 0.56-0.62 for 2012-2017 vs 2000-2005). Absolute mortality decreased significantly over time: by 21% in 2006 to 2011 and by 40% in 2012 to 2017, compared with 2000 to 2005. On long-term follow-up, differences in survival associated with sex and ethnicity tended to diminish, whereas differences associated with older age, higher CCI score, and trochanteric fractures increased. In the first year after fracture, reductions in SMR were observed comparing the periods 2013 to 2016 with 2003 to 2007 in women (SMR, 2.05; 95% CI, 1.91-2.20 vs SMR, 2.54; 95% CI, 2.39-2.70, respectively) but not among men (SMR, 3.28; 95% CI, 3.04-3.54 vs SMR, 3.42; 95% CI, 3.18-3.68, respectively).

CONCLUSIONS AND RELEVANCE

Malay ethnicity, older age, male sex, prefracture comorbidity, and trochanteric fractures were independently associated with increased risk of death, identifying population groups that could be targeted for intervention strategies. The improvement in relative mortality for women but not men suggests the need to develop interventions that improve mortality outcomes for men.

Factors associated with re-initiation of antidepressant treatment following discontinuation during pregnancy: a register-based cohort study

Antidepressant treatment when facing a pregnancy is an important issue for many women and their physicians. We hypothesized that women with a greater burden of pre-pregnancy psychiatric illness would be more likely to re-initiate antidepressants following discontinuation of treatment during pregnancy. A register-based cohort study was carried out including 38,595 women who gave birth between the 1st of January 2007 and the 31st of December 2014, who had filled a prescription for an antidepressant medication in the year prior to conception. Logistic regressions were used to explore associations between maternal characteristics and antidepressant treatment discontinuation or re-initiation during pregnancy. Most women discontinued antidepressant treatment during pregnancy (n = 29,095, 75.4%), of whom nearly 12% (n = 3434, 11.8%) re-initiated treatment during pregnancy. In adjusted analyses, parous women (aOR 1.22, 95% CI 1.12-1.33), with high educational level (aOR 1.21, 95% CI 1.08-1.36); born within the EU (excluding Nordic countries, aOR 1.41, 95% CI 1.03-1.92) or a Nordic country (aOR 1.42, 95% CI 1.22-1.65); who more often reported prior hospitalizations due to psychiatric disorders (aOR 1.50, 95% CI 1.10-2.03, for three or more episodes); and had longer duration of pre-pregnancy antidepressant use (aOR 6.10, 95% CI 5.48-6.77, for >2 years antidepressant use), were more likely to re-initiate antidepressants than were women who remained off treatment. Women with a greater burden of pre-pregnancy psychiatric illness were more likely to re-initiate antidepressants. Thus, pre-pregnancy psychiatric history may be particularly important for weighing the risks and benefits of discontinuing antidepressants during pregnancy.

Reproductive Outcomes of Women with Polycystic Ovarian Syndrome Following In-Vitro Fertilization — A Meta-Analysis and Systematic Review

Background: Polycystic ovarian syndrome (PCOS) is a common cause of infertility in women. In-vitro fertilization (IVF) is required in 20–30% of women with PCOS trying to conceive. This is associated with increased risk of multiple gestation and ovarian hyperstimulation syndrome. Improvements in IVF techniques, safety standards, and the increased use of frozen embryos in recent years have lead to improved outcomes for women with PCOS. We performed a systematic review and meta-analysis to compare these outcomes with women without PCOS.

Search Methods: A search of PubMed, EMBASE, the Cochrane Central Register of clinical trials, and Scopus databases for all articles published until November 16th, 2017 identified 21 studies comparing IVF outcomes in PCOS and non-PCOS women. Inclusion criteria were Rotterdam criteria PCOS, comparable IVF regimes, immediate IVF outcomes, and pregnancy outcomes. Studies were excluded if the control group included any PCOS criteria, donor oocytes, or in-vitro maturation.

Outcomes: No difference was observed in live birth rate per cycle in women with vs. without PCOS (RR [Formula: see text] 1.01 [0.89, 1.16]; [Formula: see text] 82%), but the live birth rate per first cycle in PCOS cycles (RR [Formula: see text] 0.93 [0.88, 0.99]) was slightly lower. There was also no difference in the clinical pregnancy rate (RR 1.02 [0.89, 1.17]) or biochemical pregnancy rate (RR 1.03 [0.99, 1.08]) observed between the two groups. PCOS was associated with a significantly higher number of oocytes retrieved (mean difference [Formula: see text] 3.6; 95% CI [2.8, 4.4]), risk of miscarriage (RR 2.90 [2.09, 4.02]), and risk of ovarian hyperstimulation syndrome (RR 3.42 [2.28, 5.13]) per cycle.

Conclusion: Despite a widespread perception of poor reproductive potential, women with PCOS experience IVF outcomes similar to those without PCOS. Although there is a slightly lower live birth rate during their first stimulation cycle, success rates are similar after multiple cycles. PCOS is associated with a higher risk of ovarian hyperstimulation syndrome. Further studies are required to mitigate this risk.

Risk factors and prevalence of urinary incontinence in mid-life Singaporean women: the Integrated Women's Health Program

INTRODUCTION AND HYPOTHESIS

The objective was to identify the prevalence and risk factors for urinary incontinence (UI) in healthy midlife Singaporean women.

METHODS

Healthy women, aged 45-69 years, were assessed for UI and sociodemographic characteristics, including ethnicity, menopausal status, parity, and body mass index (BMI). UI subtypes corresponding to stress (SUI) alone, urge (UUI) alone, mixed (MUI), and leakage (drops only) incontinence were classified using the Urinary Distress Inventory 6 (UDI-6). Risk factors were examined using Chi-squared tests, followed by sequential multivariate logistic regression to estimate adjusted odds ratios (aOR and 95% confidence intervals).

RESULTS

A total of 1,119 women (mean age 56.2 ± 5.2) completed the UDI-6. 52.3% reported any UI; MUI and SUI were the most common, each affecting 20% of women. Post-menopausal women had a lower risk (aOR 0.5 [0.3-0.9]) of SUI, but a higher risk (aOR 4.4 [1.0-19.9]) of UUI compared with premenopausal women. Higher education was negatively associated (aOR 0.3 [0.2-0.7]) with UUI, but positively associated with MUI (aOR 2.3 [1.3-4.0]). Parity (1-2 children) increased the risk of SUI (aOR 1.8 [1.0-3.1]), but reduced the risk of UUI (aOR 0.4 [0.2-0.9]). Obesity was associated with increased risk for MUI (aOR 2.2 [1.4-3.4]) and leakage (aOR 2.0 [1.0-4.1]). Malays and Indians had a higher risk of MUI, having (aOR 2.1 (1.2-3.7) and 1.7 (1.1-2.7) respectively compared with Chinese, a difference mediated by higher BMI.

CONCLUSION

Urinary incontinence is a major morbidity prevalent in healthy midlife Asian women. Post-menopausal status, education level, parity, BMI (and its link with ethnicity) are independent risk factors in this population, and should be incorporated into counseling and targeted interventions.

Smart Phone APP to Restore Optimal Weight (SPAROW): protocol for a randomised controlled trial for women with recent gestational diabetes

BACKGROUND

Gestational diabetes (GDM) is a known risk factor for type 2 diabetes mellitus (T2DM), and women with a history of GDM have a 7-fold increased risk of developing the disease. Achieving a healthy weight post-delivery is key in reducing the risk of future diabetes in these women. The aim of this trial is to investigate the use of an interactive smartphone application (APP) to restore women to optimal weight following delivery.

METHODS

This will be an open-label randomized controlled trial. Two hundred women with gestational diabetes will be randomized to receive the intervention or standard care following delivery. Participants will be reviewed at 6 weeks and 4 months post-delivery. The intervention is an APP serving as a platform for weight, diet and physical activity tracking. The APP provides 3-5 min educational videos suggesting suitable lifestyle adjustments relevant to postnatal period such as breast feeding, diet and exercise. Lastly, the APP will allow real-time interaction between users and the team of dietitians, physiotherapists and occupational therapists to encourage restoration of optimal weight. Women in the control arm will be informed about the increased risk of developing T2DM and advised to maintain a healthy weight. Primary outcome measure is the restoration of participants' booking weight if booking BMI ≤ 23, or weight loss of at least 5% from booking weight if booking BMI > 23 over the 4 month period. Secondary outcome measures will assess serum metabolic and inflammatory markers, quality of life via questionnaires and cost-effectiveness of the intervention at each follow-up visit.

DISCUSSION

This will be the first randomised controlled trial investigating the use of a smartphone application for postpartum weight loss in women with gestational diabetes. The major ethnic groups in our study population represent the majority of ethnic groups in Asia, amongst which the prevalence of diabetes is high. If shown to be effective, this APP may be used in wider clinical settings to improve postpartum weight loss and reduce the risk of developing T2DM in these women.

TRIAL REGISTRATION

This study was registered on clintrials.gov on the 30th of October 2017, under the trial registration number: NCT03324737 .

Objective measures of physical performance associated with depression and/or anxiety in midlife Singaporean women

OBJECTIVES

The aim of this study was to identify correlates of depression and anxiety in midlife Asian women, with a special focus on the potential role of objectively measured physical performance.

METHODS

Sociodemographic characteristics, reproductive health, menopause status, medical history, lifestyle choices, physical activity, and physical performance of healthy women aged 45 to 69 attending routine gynecologic care were collected. Depressive symptoms were assessed utilizing the Center for Epidemiologic Studies for Depression Scale (CES-D) and anxiety symptoms by the General Anxiety Disorder Scale (GAD-7). Upper body physical performance was assessed by handgrip strength, and lower body physical performance was assessed by the Short Physical Performance Battery. Chi-square tests and multivariable models were used to assess the crude and adjusted associations, respectively, between the studied risk factors and depression and/or anxiety. The main outcome measures were elevated depressive symptoms ≥16 on the CES-D, and/or elevated anxiety symptoms >10 on the GAD-7 score.

RESULTS

Of 1,159 women (mean age 56.3 ± 6.2), 181 (15.9%) were identified as having depressive and/or anxiety symptoms. Weak upper body (handgrip strength) and poor lower body strength (longer duration to complete the repeated chair stand test) were associated with elevated depressive and/or anxiety symptoms (adjusted odds ratio [aOR], 1.68; 95% CI, 1.18-2.40) and (aOR, 1.33; 95% CI, 1.09-1.63), respectively.

CONCLUSIONS

Weak upper and lower body physical performances were associated with depressive and anxiety symptoms in midlife Singaporean women. Future trials are required to determine whether strengthening exercises that improve physical performance could help reduce depressive and anxiety symptoms in midlife women. : Video Summary: Supplemental Digital Content 1, http://links.lww.com/MENO/A419.

Hip fractures in Singapore: ethnic differences and temporal trends in the new millennium

Despite an increase in absolute numbers, the age-standardized incidence of hip fractures in Singapore declined in the period 2000 to 2017. Among the three major ethnic groups, Chinese women had the highest fracture rates but were the only group to show a temporal decline.

INTRODUCTION

A study published in 2001 predicted a 30-50% increase in Singapore hip fracture incidence rates over the ensuing 30 years. To test that prediction, we examined the incidence of hip fracture in Singapore from 2000 to 2017.

METHODS

We carried out a population-based study of hip fractures among Singapore residents aged ≥ 50 years. National medical insurance claims data were used to identify admissions with a primary discharge diagnosis of hip fracture. Age-adjusted rates, based on the age distribution of the Singapore population of 2000, were analyzed separately by sex and ethnicity (Chinese, Malay, or Indian).

RESULTS

Over the 18-year study period, 36,082 first hip fractures were recorded. Total hip fracture admissions increased from 1487 to 2729 fractures/year in the years 2000 to 2017. Despite this absolute increase, age-adjusted fracture rates declined, with an average annual change of - 4.3 (95% CI - 5.0, - 3.5) and - 1.1 (95% CI - 1.7, - 0.5) fractures/100,000/year for women and men respectively. Chinese women had 1.4- and 1.9-fold higher age-adjusted rates than Malay and Indian women: 264 (95% CI 260, 267) versus 185 (95% CI 176, 193) and 141 (95% CI 132, 150) fractures/100,000/year, respectively. Despite their higher fracture rates, Chinese women were the only ethnic group exhibiting a decline, most evident in those ≥ 85 years, in age-adjusted fracture rate of - 5.3 (95% CI - 6.0, - 4.5) fractures/100,000/year.

CONCLUSION

Although the absolute number of fractures increased, steep drops in elderly Chinese women drove a reduction in overall age-adjusted hip fracture rates. Increases in the older population will lead to a rise in total number of hip fractures, requiring budgetary planning and new preventive strategies.

STAT-3 regulation of CXCR4 is necessary for the prenylflavonoid Icaritin to enhance mesenchymal stem cell proliferation, migration and osteogenic differentiation

Mesenchymal stem cell (MSC) dysfunction has been implicated in the pathogenesis of osteoporosis. MSCs derived from osteoporotic subjects demonstrate significant impairment in proliferation, adhesion and chemotaxis, and osteogenic differentiation, leading to reduced functional bone-forming osteoblasts and ultimately nett bone loss and osteoporosis. Epimedium herbs and its active compound Icaritin (ICT) have been used in Chinese ethnopharmacology for the treatment of metabolic bone diseases. Using an in-vitro cell culture model, we investigated the benefits of ICT treatment in enhancing MSC proliferation, migration and osteogenic differentiation, and provide novel data to describe its mechanism of action. ICT enhances MSC proliferation, chemotaxis to stromal cell-derived factor-1 (SDF-1) and osteogenic differentiation through the activation of signal transduction activator transcription factor 3 (STAT-3), with a consequential up-regulation in the expression and activity of cysteine (C)-X-C motif chemokine receptor 4 (CXCR4). These findings provide a strong basis for future clinical studies to confirm the therapeutic potential of ICT for the prevention and treatment of osteoporosis and fragility fractures.

The prenylflavonoid Icaritin enhances osteoblast proliferation and function by signal transducer and activator of transcription factor 3 (STAT-3) regulation of C-X-C chemokine receptor type 4 (CXCR4) expression

In this study, we examined the effects of a natural prenylflavonoid Icaritin (ICT), on human osteoblast proliferation and osteogenic function. We observed that ICT dose-dependently enhanced osteoblast proliferation by ~15% over a 7day period. This increase in cell proliferation was associated with corresponding increases in osteoblast functions as measured by ALP secretion, intracellular calcium ions influx and calcium deposition. These anabolic effects were associated with a 4-fold increase in CXCR4 mRNA and protein expression. Silencing of CXCR4 protein expression using small interfering RNA reversed ICT-induced increase in cell proliferation, ALP activity and calcium deposition. Interestingly, we observed that ICT dose-dependently increased STAT-3 phosphorylation; and this resulted in increased binding of phosphorylated STAT-3 to the promoter region of the CXCR4 gene, to increase CXCR4 protein expression. Furthermore, we found that inhibition of STAT-3 phosphorylation resulted in a decrease in CXCR4 protein expression; whilst increasing phosphorylation of STAT-3 using a constitutive active STAT-3 vector significantly increased CXCR4 levels. Moreover, the chemical inhibition of STAT-3 phosphorylation annulled our previously observed ICT-induced increases of osteoblast proliferation and function. Finally, in a rat model of estrogen-deficient osteoporosis, ICT restored both osteoblasts numbers and CXCR4 expression. Taken together, both cellular and animal models support the novel findings that ICT; through the phosphorylation of STAT-3, up-regulated CXCR4, to increase osteoblast proliferation and function.

Chronic joint pain and handgrip strength correlates with osteoporosis in mid-life women: a Singaporean cohort

This study aimed to identify novel correlates which may relate to low bone mass at lumbar spine in mid-life Asian women. The possibility of developing a prediction model for osteoporosis (OP) was explored which resulted in a risk assessment tool that performed better than currently available tools.

INTRODUCTION

In order to identify novel correlates associated with low spinal bone mineral density (BMD) in mid-life women, we examined a large number of lifestyle and medical and performance measurements and developed a prediction model for triage to BMD scanning.

METHODS

Women (n = 512) aged 45-69 years (mean 57.0 ± 6.3) attending gynecology clinics for "well woman" visits were recruited for this cross-sectional study from 2014 to 2015. We assessed symptoms, medical history, anthropometry, and physical performance. Stepwise multinomial logistic regressions were performed to examine significant associated covariates for pre-specified outcomes (normal [T-score ≥ -1.0], low bone mass [T-score between -1 and -2.5], and OP [T-score ≤ -2.5] at the lumbar spine). A new screening model was developed, and its performance was compared with the OP Screening Tool for Asians (OSTA) and Fracture Risk Assessment Tool (FRAX®).

RESULTS

Spinal OP was found in 6.8%. Multivariate analysis indicated that chronic joint pain, the most common symptom reported by 37.5% of the women, was significantly associated with OP. Only age (Relative Risk Ratio [RRR] 1.63; 95%CI, 1.03-2.60), weight (RRR 0.14; 95% CI, 0.07-0.27), postmenopausal status (RRR 11.59, 95%CI, 1.15-116.73), chronic joint pain (RRR, 4.12; 95% CI, 1.53-11.07), and right handgrip strength (RRR 0.50; 95% CI, 0.31-0.80) were independently associated with spinal OP. Combining these five variables, our final model's area under curve (AUC) was significantly higher at 84% than both the OSTA [AUC; 79% (p value < 0.0231 'c' statistics)] and FRAX® [AUC 58% (p value < 0.0001 'c' statistic)].

CONCLUSION

A novel screening tool that combines age, weight, and menopausal status with chronic joint pain and right handgrip strength more reliably predicts spinal OP in mid-life Singaporean women.

TRAF6 Mediates Suppression of Osteoclastogenesis and Prevention of Ovariectomy-Induced Bone Loss by a Novel Prenylflavonoid

Given the limitations of current therapeutic options for postmenopausal osteoporosis, there is a need for alternatives with minimal adverse effects. In this study, we evaluated the effects of icaritin (ICT), a natural prenylflavonoid, on osteoclastogenesis both in vitro and in an ovariectomized (OVX) rat model and investigated its underlying molecular mechanism(s) of action. ICT inhibited osteoclast formation in two osteoclast precursor models, RAW 264.7 mouse monocyte cell line and human PBMC. ICT also inhibited sealing zone and resorption pit formation in a dose-dependent manner. Mechanistically, ICT inhibited RANKL-induced NF-κB and MAPK/AP-1 pathways to suppress gene expression of nuclear factor of activated T cells (NFAT)c1, the master transcription regulator of osteoclast differentiation. ICT, by inhibiting the TRAF6/c-Src/PI3K pathway, suppressed NADPH oxidase-1 activation to attenuate intracellular ROS production and downregulate calcineurin phosphatase activity. As a result, NFATc1 nuclear translocation and activity was suppressed. Crucially, ICT promoted proteasomal degradation of TRAF6, the critical adaptor protein that transduces RANKL/RANK signaling, and the inhibitory effect of ICT on osteoclastogenesis was reversed by the proteasomal inhibitor MG 132. ICT administration inhibited OVX-induced bone loss and resorption by suppressing osteoclast formation and activity. Consistent with cellular studies, ICT downregulated TRAF6 and NFATc1 protein expression in CD11b⁺ /Gr-1^-/low osteoclast precursors isolated from OVX rats. Put together, we present novel findings that ICT, by downregulating TRAF6, coordinates inhibition of NF-κB, MAPK/AP-1, and ROS signaling pathways to reduce expression and activity of NFATc1. These results demonstrate the potential of ICT for treatment of postmenopausal osteoporosis and point to TRAF6 as a promising target for novel anti-osteoporotic drugs. © 2017 American Society for Bone and Mineral Research.

Sleep Duration, Exercise, Shift Work and Polycystic Ovarian Syndrome-Related Outcomes in a Healthy Population: A Cross-Sectional Study

CONTEXT

Few studies have examined the associations between sleep duration, shiftwork, and exercise to the infrequent menstruation, hyperandrogenism, and ovarian morphological changes observed in women with polycystic ovarian syndrome (PCOS).

OBJECTIVE

To examine whether lifestyle factors, including short sleep duration, insufficient exercise, and shiftwork, alone or in combination, are associated with the reproductive and metabolic abnormalities typical of PCOS in a healthy population.

STUDY DESIGN, SIZE, DURATION

Prospective cross-sectional study of 231 women, including healthcare workers recruited for an annual health screen, healthy referral patients from the Women's Clinic and volunteers from the university community at the National University Hospital, Singapore, from 2011 to 2015.

MAIN OUTCOME MEASURES

The women completed a questionnaire, including their menstrual cycle length, sleep length, frequency of exercise and shift work. Hyperandrogenism (hirsutism score, testosterone, sex hormone binding globulin (SHBG)), ovarian morphology and function (anthral follicle count, ovarian volume, anti-mullerian hormone (AMH)), and metabolic measures (body mass index (BMI), waist hip ratio (WHR), blood pressure, fasting glucose, fasting insulin and fasting lipids) were examined through anthropometric measurements, transvaginal ultrasound scans, and blood tests.

RESULTS

No significant associations were observed between shift work, exercise or sleep duration and the androgenic and ovarian measures that define PCOS. However, women reporting fewer than 6 hours of sleep were more likely to report abnormal (short or long) menstrual cycle lengths (OR = 2.1; 95% CI, 1.1 to 4.2). Women who reported fewer than 6 hours of sleep had increased fasting insulin levels (difference in means = 2.13; 95% CI, 0.27 to 3.99 mU/L) and higher odds of insulin resistance (OR = 2.58; CI, 1.16 to 5.76). Lack of regular exercise was associated with higher mean fasting insulin (difference in means = 2.3 mU/L; 95% CI, 0.5 to 4.1) and HOMA-IR (difference in means = 0.49; 95% CI, 0.09 to 0.90) levels.

CONCLUSIONS

Women with insufficient sleep are at increased risk of menstrual disturbances and insulin resistance, but do not have the hyperandrogenism and polycystic ovarian morphology typical of PCOS.

WIDER IMPLICATIONS OF THE FINDINGS

Improved sleep duration may help reduce the risks of diabetes or infertility. Shift work, exercise or sleep duration appear not to impact the androgenic and ovarian measures that define PCOS.

Antimüllerian hormone, antral follicle count and ovarian volume predict menstrual cycle length in healthy women

OBJECTIVE

Although menstrual cycle length is one of the main concerns of women and may have important health consequences, little is known about its predictors. The aim of this study was to identify predictors of menstrual cycle length variability in healthy women.

DESIGN

Prospective cross-sectional study.

PATIENTS

Two hundred healthy women aged 21-45.

MEASUREMENTS

A questionnaire was administered to determine lifestyle factors. Ovarian parameters, metabolic parameters, pituitary hormones, sex steroids and antimüllerian hormone (AMH) were measured.

RESULTS

Women with long (≥35 days) and normal (25-34 days) menstrual cycles had >5-fold and >2-fold higher serum AMH levels, respectively, compared to those with short cycles (<25 days). Menstrual cycle length was associated with age but not lifestyle factors. Only one factor group (AMH, antral follicle count [AFC], ovarian volume, testosterone and LH) was significantly associated with menstrual cycle length. Within this factor group, only the ovarian parameters (AMH, AFC, ovarian volume) predicted menstrual cycle length. Each SD increase in AMH (32·9 pmol/l) and ovarian volume (2·29 cm(3) ) was associated with 2·80-fold (95% CI: 1·67-4·69) and 1·62-fold (95% CI: 1·08-2·43) increased risks, respectively, for longer menstrual cycles.

CONCLUSIONS

AMH, AFC and ovarian volume are positively associated with menstrual cycle length in healthy women. Our identification of AMH as an independent predictor of menstrual cycle length puts forth a new notion of utilizing menstrual cycle length to predict possible AMH-dependent/-associated outcomes. In addition, this novel relationship may facilitate the interpretation of AMH levels and its clinico-pathological significance across different centres.

Preclinical studies and clinical evaluation of compounds from the genus Epimedium for osteoporosis and bone health

The morbidity and mortality associated with fractures due to osteoporosis or "porous bone" contributes significantly to global healthcare costs and will increase exponentially with ageing populations. In menopausal women, the onset of menopause and rapid estrogen withdrawal leads to osteoporotic fractures. Healthy bone requires the coordinated remodeling function of osteoclasts, osteoblasts, and osteocytes in the basic bone multicellular unit, regulated by estrogen, RANKL/OPG, ROS, growth factors, and other kinase signaling pathways. Anti-osteoporotic drugs in current use such as hormone replacement therapy, selective estrogen receptor modulators, and bisphosphonates are designed to target these pathways, but all have their limitations. Extracts of the dried aerial parts of the traditional Chinese medicinal plant Epimedium (Berberidaceae) has long been used for bone health. Some nine Epimedium prenylflavonoid compounds have been reported to target estrogen signaling and other bone morphogenesis pathways in mesenchymal stem cell, osteoblast, and osteoclast cell lineages. Epimedium prenylflavonoids and enriched extracts can exert beneficial effects on bone health in estrogen-deficient and other osteoporosis animal models. The development of sensitive and rapid mass chromatographic techniques to quantify compounds extracted from Epimedium, including icariin and icaritin, has been used to standardize production and to study the pharmacokinetics and metabolism of Epimedium in animal models and humans. Recent clinical trials have reported positive effects on bone health, suggesting that compounds or extracts of Epimedium have the potential to be developed as agents, alone or in combination with other drugs, to prevent or delay the onset of osteoporosis and reduce the risk of hip fractures.

Polymorphisms of anti-Müllerian hormone signaling pathway in healthy Singapore women: population differences, endocrine effects and reproductive outcomes

In order to study the association of genetic polymorphisms of anti-Müllerian hormone (AMH) signaling pathway with endocrine changes and pregnancy outcomes, a total of 213 women of reproductive ages were recruited according to our inclusion and exclusion criteria between November 2011 and September 2014 in Singapore. Genotyping studies were performed using a minor groove binder primer/probe Taqman assay. The allele frequencies of the AMH Ile(49)Ser and AMHR2 -482A > G polymorphisms were analyzed in relation to female reproductive hormone levels, ovarian parameters, menstrual cycle lengths and pregnancy outcomes. AMH Ser allele frequency and AMHR2 G allele frequency of our Singapore population were compared with those of other populations reported in HapMap. The genotype distributions and allele frequencies for the AMH Ile(49)Ser and AMHR2 -482A > G polymorphisms were not associated with estradiol (E2) levels, ovarian parameters, menstrual cycle length, or pregnancy outcomes in our cohort. Our findings suggest that genetic variants in the AMH signal transduction pathway have population differences but do not appear to have significant effects on ovarian, endocrine, metabolic parameters and reproductive outcomes.

A Dietary Medium-Chain Fatty Acid, Decanoic Acid, Inhibits Recruitment of Nur77 to the HSD3B2 Promoter In Vitro and Reverses Endocrine and Metabolic Abnormalities in a Rat Model of Polycystic Ovary Syndrome

Hyperandrogenism is the central feature of polycystic ovary syndrome (PCOS). Due to the intricate relationship between hyperandrogenism and insulin resistance in PCOS, 50%-70% of these patients also present with hyperinsulinemia. Metformin, an insulin sensitizer, has been used to reduce insulin resistance and improve fertility in women with PCOS. In previous work, we have noted that a dietary medium-chain fatty acid, decanoic acid (DA), improves glucose tolerance and lipid profile in a mouse model of diabetes. Here, we report for the first time that DA, like metformin, inhibits androgen biosynthesis in NCI-H295R steroidogenic cells by regulating the enzyme 3β-hydroxysteroid dehydrogenase/Δ5-Δ4-isomerase type 2 (HSD3B2). The inhibitory effect on HSD3B2 and androgen production required cAMP stimulation, suggesting a mechanistic action via the cAMP-stimulated pathway. Specifically, both DA and metformin reduced cAMP-enhanced recruitment of the orphan nuclear receptor Nur77 to the HSD3B2 promoter, coupled with decreased transcription and protein expression of HSD3B2. In a letrozole-induced PCOS rat model, treatment with DA or metformin reduced serum-free testosterone, lowered fasting insulin, and restored estrous cyclicity. In addition, DA treatment lowered serum total testosterone and decreased HSD3B2 protein expression in the adrenals and ovaries. We conclude that DA inhibits androgen biosynthesis via mechanisms resulting in the suppression of HSD3B2 expression, an effect consistently observed both in vitro and in vivo. The efficacy of DA in reversing the endocrine and metabolic abnormalities of the letrozole-induced PCOS rat model are promising, raising the possibility that diets including DA could be beneficial for the management of both hyperandrogenism and insulin resistance in PCOS.

Respiratory consequences of N95-type Mask usage in pregnant healthcare workers-a controlled clinical study

Background

Outbreaks of emerging infectious diseases have led to guidelines recommending the routine use of N95 respirators for healthcare workers, many of whom are women of childbearing age. The respiratory effects of prolonged respirator use on pregnant women are unclear although there has been no definite evidence of harm from past use.

Methods

We conducted a two-phase controlled clinical study on healthy pregnant women between 27 to 32 weeks gestation. In phase I, energy expenditure corresponding to the workload of routine nursing tasks was determined. In phase II, pulmonary function of 20 subjects was measured whilst at rest and exercising to the predetermined workload while breathing ambient air first, then breathing through N95-mask materials.

Results

Exercising at 3 MET while breathing through N95-mask materials reduced mean tidal volume (TV) by 23.0 % (95 % CI −33.5 % to −10.5 %, p < 0.001) and lowered minute ventilation (VE) by 25.8 % (95 % CI −34.2 % to −15.8 %, p < 0.001), with no significant change in breathing frequency compared to breathing ambient air. Volumes of oxygen consumption (VO₂) and carbon dioxide expired (VCO₂) were also significantly reduced; VO₂ by 13.8 % (95 % CI −24.2 % to −3 %, p = 0.013) and VCO₂ by 17.7 %, (95 % CI −28.1 % to −8.6 %, p = 0.001). Although no changes in the inspired oxygen and carbon dioxide concentrations were demonstrated, breathing through N95-mask materials during low intensity work (3 MET) reduced expired oxygen concentration by 3.2 % (95 % CI: −4.1 % to −2.2 %, p < 0.001), and increased expired carbon dioxide by 8.9 % (95 % CI: 6.9 % to 13.1 %; p <0.001) suggesting an increase in metabolism. There were however no changes in the maternal and fetal heart rates, finger-tip capillary lactate levels and oxygen saturation and rating of perceived exertion at the work intensity investigated.

Conclusions

Breathing through N95 mask materials have been shown to impede gaseous exchange and impose an additional workload on the metabolic system of pregnant healthcare workers, and this needs to be taken into consideration in guidelines for respirator use. The benefits of using N95 mask to prevent serious emerging infectious diseases should be weighed against potential respiratory consequences associated with extended N95 respirator usage.

Trial Registration

The study was registered at clinicaltrials.gov, identifier NCT00265926.

A novel prostate cancer therapeutic strategy using icaritin-activated arylhydrocarbon-receptor to co-target androgen receptor and its splice variants

Persistent androgen receptor (AR) signaling is the key driving force behind progression and development of castration-resistant prostate cancer (CRPC). In many patients, AR COOH-terminal truncated splice variants (ARvs) play a critical role in contributing to the resistance against androgen depletion therapy. Unfortunately, clinically used antiandrogens like bicalutamide (BIC) and enzalutamide (MDV), which target the ligand binding domain, have failed to suppress these AR variants. Here, we report for the first time that a natural prenylflavonoid, icaritin (ICT), can co-target both persistent AR and ARvs. ICT was found to inhibit transcription of key AR-regulated genes, such as KLK3 [prostate-specific antigen (PSA)] and ARvs-regulated genes, such as UBE2C and induce apoptosis in AR-positive prostate cancer (PC) cells. Mechanistically, ICT promoted the degradation of both AR and ARvs by binding to arylhydrocarbon-receptor (AhR) to mediate ubiquitin-proteasomal degradation. Therefore, ICT impaired AR transactivation in PC cells. Knockdown of AhR gene restored AR stability and partially prevented ICT-induced growth suppression. In clinically relevant murine models orthotopically implanted with androgen-sensitive and CRPC cells, ICT was able to target AR and ARvs, to inhibit AR signaling and tumor growth with no apparent toxicity. Our results provide a mechanistic framework for the development of ICT, as a novel lead compound for AR-positive PC therapeutics, especially for those bearing AR splice variants.

Phytoplankton blooms: an overlooked marine source of natural endocrine disrupting chemicals

BACKGROUND

We had previously reported high androgenic and estrogenic activities in seawaters in confined clusters close to Singapore. Further investigations revealed a hitherto unsuspected link between estrogenic/androgenic activity and net phytoplankton count.

OBJECTIVE

The primary objective of this study was to investigate the cause of a correlation between net phytoplankton and endocrine activity, and corroborate this observation, and rule out other possible confounding factors. Our secondary objective was to study if these estrogenic secretions can impact human health.

METHODS

Five species of phytoplankton, Gymnodinium catenatum, Prorocentrum minimum, Alexandrium leei, Chattonella marina, and Fibrocapsa japonica, were isolated from Singapore waters and mass cultured and the cells and culture media screened for estrogenic and androgenic activity using human cell-based bioassays.

RESULTS

The raphidophytes C. marina and F. japonica displayed significant estrogenic activity whilst the dinoflagellates G. catenatum and P. minimum displayed significant androgenic activity in both the cell extracts and the cell culture media extract.

CONCLUSIONS

Our data shows that selected phytoplankton isolates are potent secretors of estrogenic and androgenic substances, which are potential endocrine disrupting chemicals (EDCs). As the harmful nature of EDCs is largely due to their bioaccumulation in the aquatic food chain our findings imply that the impact of these phytoplankton secretions needs to be investigated especially for seafoods, which are only a single trophic level away from phytoplankton. Alternatively, should these phytoplankton-origin EDCs not accumulate through marine food chains to significantly impact humans or marine mammals, our results indicate that functional assays could greatly over-estimate the risk from naturally occurring EDCs produced by marine phytoplankton. It remains to be determined if these EDCs affect zooplankton and other organisms that directly feed on marine phytoplankton, or if the secreted EDCs can directly impact other marine fauna.

The crystal structure of the orphan nuclear receptor NR2E3/PNR ligand binding domain reveals a dimeric auto-repressed conformation

Photoreceptor-specific nuclear receptor (PNR, NR2E3) is a key transcriptional regulator of human photoreceptor differentiation and maintenance. Mutations in the NR2E3-encoding gene cause various retinal degenerations, including Enhanced S-cone syndrome, retinitis pigmentosa, and Goldman-Favre disease. Although physiological ligands have not been identified, it is believed that binding of small molecule agonists, receptor desumoylation, and receptor heterodimerization may switch NR2E3 from a transcriptional repressor to an activator. While these features make NR2E3 a potential therapeutic target for the treatment of retinal diseases, there has been a clear lack of structural information for the receptor. Here, we report the crystal structure of the apo NR2E3 ligand binding domain (LBD) at 2.8 Å resolution. Apo NR2E3 functions as transcriptional repressor in cells and the structure of its LBD is in a dimeric auto-repressed conformation. In this conformation, the putative ligand binding pocket is filled with bulky hydrophobic residues and the activation-function-2 (AF2) helix occupies the canonical cofactor binding site. Mutations designed to disrupt either the AF2/cofactor-binding site interface or the dimer interface compromised the transcriptional repressor activity of this receptor. Together, these results reveal several conserved structural features shared by related orphan nuclear receptors, suggest that most disease-causing mutations affect the receptor's structural integrity, and allowed us to model a putative active conformation that can accommodate small ligands in its pocket.

Structural basis for molecular recognition of folic acid by folate receptors

Folate receptors (FRα, FRβ and FRγ) are cysteine-rich cell-surface glycoproteins that bind folate with high affinity to mediate cellular uptake of folate. Although expressed at very low levels in most tissues, folate receptors, especially FRα, are expressed at high levels in numerous cancers to meet the folate demand of rapidly dividing cells under low folate conditions. The folate dependency of many tumours has been therapeutically and diagnostically exploited by administration of anti-FRα antibodies, high-affinity antifolates, folate-based imaging agents and folate-conjugated drugs and toxins. To understand how folate binds its receptors, we determined the crystal structure of human FRα in complex with folic acid at 2.8 Å resolution. FRα has a globular structure stabilized by eight disulphide bonds and contains a deep open folate-binding pocket comprised of residues that are conserved in all receptor subtypes. The folate pteroate moiety is buried inside the receptor, whereas its glutamate moiety is solvent-exposed and sticks out of the pocket entrance, allowing it to be conjugated to drugs without adversely affecting FRα binding. The extensive interactions between the receptor and ligand readily explain the high folate-binding affinity of folate receptors and provide a template for designing more specific drugs targeting the folate receptor system.

Abscisic acid signaling: thermal stability shift assays as tool to analyze hormone perception and signal transduction

Abscisic acid (ABA) is a plant hormone that plays important roles in growth and development. ABA is also the central regulator to protect plants against abiotic stresses, such as drought, high salinity, and adverse temperatures, and ABA signaling is therefore a promising biotechnological target for the generation of crops with increased stress resistance. Recently, a core signal transduction pathway has been established, in which ABA receptors, type 2C protein phosphatases, and AMPK-related protein kinases control the regulation of transcription factors, ion channels, and enzymes. Here we use a simple protein thermal stability shift assay to independently validate key aspects of this pathway and to demonstrate the usefulness of this technique to detect and characterize very weak (Kd ≥50 µM) interactions between receptors and physiological and synthetic agonists, to determine and analyze protein-protein interactions, and to screen small molecule inhibitors.

Catalytic mechanism and kinase interactions of ABA-signaling PP2C phosphatases

Abscisic acid (ABA) is an essential hormone that controls plant growth, development and responses to abiotic stresses. ABA signaling is mediated by type 2C protein phosphatases (PP2Cs), including HAB1 and ABI2, which inhibit stress-activated SnRK2 kinases and whose activity is regulated by ABA and ABA receptors. Based on biochemical data and our previously determined crystal structures of ABI2 and the SnRK2.6-HAB1 complex, we present the catalytic mechanism of PP2C and provide new insight into PP2C-SnRK2 interactions and possible roles of other SnRK2 kinases in ABA signaling.

A novel prenylflavone restricts breast cancer cell growth through AhR-mediated destabilization of ERα protein

There is concern that ingestion of dietary phytoestrogens may increase risk of estrogen receptor alpha (ERα)-positive breast cancer. The prenylflavone icaritin, a phytoestrogen consumed in East Asian societies for its perceived beneficial effects on bone health, stimulated the growth of breast cancer (MCF-7) cells at low concentrations. Although acting like an estrogenic ligand, icaritin exerted an unexpected suppressive effect on estrogen-stimulated breast cancer cell proliferation and gene expression at higher concentrations. Like estradiol, icaritin could dose-dependently destabilize ERα protein. However, destabilization of ERα by the estradiol/icaritin combination was profound and greater than that observed for either compound alone. Microarray gene expression analyses implicated aryl hydrocarbon receptor (AhR) signaling for this suppressive effect of icaritin. Indeed, icaritin was an AhR agonist that competitively reduced specific binding of a potent AhR agonist and increased expression of the AhR-regulated gene CYP1A1. When AhR was knocked down by small interfering RNA, the suppressive effect of icaritin on estradiol-stimulated breast cancer cell growth and gene expression was abolished, and ERα protein stability was partially restored. Similarly in an athymic nude mouse model, icaritin restricted estradiol-stimulated breast cancer xenograft growth and strongly reduced ERα protein levels. Overall, our data support the feasibility for the development of dual agonists like icaritin, which are estrogenic but yet, through activating AhR-signaling, can destabilize ERα protein to restrict ERα-positive breast cancer cell growth.

Molecular mimicry regulates ABA signaling by SnRK2 kinases and PP2C phosphatases

Abscisic acid (ABA) is an essential hormone for plants to survive environmental stresses. At the center of the ABA signaling network is a subfamily of type 2C protein phosphatases (PP2Cs), which form exclusive interactions with ABA receptors and subfamily 2 Snfl-related kinase (SnRK2s). Here, we report a SnRK2-PP2C complex structure, which reveals marked similarity in PP2C recognition by SnRK2 and ABA receptors. In the complex, the kinase activation loop docks into the active site of PP2C, while the conserved ABA-sensing tryptophan of PP2C inserts into the kinase catalytic cleft, thus mimicking receptor-PP2C interactions. These structural results provide a simple mechanism that directly couples ABA binding to SnRK2 kinase activation and highlight a new paradigm of kinase-phosphatase regulation through mutual packing of their catalytic sites.

Identification and mechanism of 10-carbon fatty acid as modulating ligand of peroxisome proliferator-activated receptors

Peroxisome proliferator-activated receptors (PPARα, -β/δ, and -γ) are a subfamily of nuclear receptors that plays key roles in glucose and lipid metabolism. PPARγ is the molecular target of the thiazolidinedione class of antidiabetic drugs that has many side effects. PPARγ is also activated by long chain unsaturated or oxidized/nitrated fatty acids, but its relationship with the medium chain fatty acids remains unclear even though the medium chain triglyceride oils have been used to control weight gain and glycemic index. Here, we show that decanoic acid (DA), a 10-carbon fatty acid and a major component of medium chain triglyceride oils, is a direct ligand of PPARγ. DA binds and partially activates PPARγ without leading to adipogenesis. Crystal structure reveals that DA occupies a novel binding site and only partially stabilizes the AF-2 helix. DA also binds weakly to PPARα and PPARβ/δ. Treatments with DA and its triglyceride form improve glucose sensitivity and lipid profiles without weight gain in diabetic mice. Together, these results suggest that DA is a modulating ligand for PPARs, and the structure can aid in designing better and safer PPARγ-based drugs.

Darunavir/ritonavir and efavirenz exert differential effects on MRP1 transporter expression and function in healthy volunteers

BACKGROUND

The efflux transporter MRP1 actively transports antiretrovirals and reduces intracellular accumulation in peripheral blood mononuclear cells (PBMCs). We studied MRP1 expression and function in healthy volunteers treated with darunavir/ritonavir and efavirenz.

METHODS

Seven healthy HIV-negative volunteers were recruited. PBMCs were collected at baseline, 9 days after administration of darunavir (900 mg) and ritonavir (100 mg) once daily, 9 days after coadministration of darunavir/ritonavir and efavirenz (600 mg) once daily and 13 days after administration of efavirenz alone. MRP1 expression was measured in PBMCs using flow cytometry with fluorescein isothiocyanate-conjugated antibody against MRP1m6. MRP1 expression was also measured in CD4(+) T-cells with a phycoerythrin-conjugated antibody against CD4. MRP1 efflux function was assessed by incubating PBMCs with carboxyfluorescein diacetate (CFDA) and comparing CFDA fluorescence with and without the modulators MK571 and probenecid.

RESULTS

MRP1 expression was reduced after darunavir/ritonavir administration (geometric mean ratio [GMR] 0.58, 95% confidence interval [95% CI] 0.51-0.65; P<0.001) and darunavir/ritonavir plus efavirenz coadministration (GMR 0.74, 95% CI 0.64-0.84; P=0.001), but not after efavirenz administration alone (GMR 0.82, 95% CI 0.64-1.06; P=0.10). MRP1 protein expression was 41% higher in CD4(+) T-cells. MRP1 efflux function was increased after efavirenz administration (GMR 3.13, 95% CI 2.73-3.59; P<0.001) and darunavir/ritonavir plus efavirenz coadministration (GMR 4.35, 95% CI 3.35-5.68; P<0.001), but not after darunavir/ritonavir administration (GMR 1.06, 95% CI 0.80-1.42; P=0.42).

CONCLUSIONS

Darunavir/ritonavir and efavirenz treatment exerted differential effects on MRP1 expression and function. These effects could potentially alter antiviral activity, especially in CD4(+) T-cells.