The physiology of age-related functional decline is poorly understood, but may involve hormones and inflammation. We hypothesized that older women with both low IGF-I and high IL-6 levels are at high risk for disability and death. We assessed walking speed and disability in 718 women enrolled in the Women's Health and Aging Study I, a 3-yr cohort study with 5-yr mortality follow-up. Women with IGF-I levels in the lowest quartile and IL-6 levels in the highest quartile had significantly greater limitation in walking and disability in mobility tasks and instrumental activities of daily living than those with neither risk factor (adjusted odds ratios, 10.77, 5.14, and 3.66). Women with both risk factors were at greater risk for death (adjusted relative risk, 2.10) as well as incident walking limitation, mobility disability, and disability in activities of daily living compared with those with high IGF-I and low IL-6 levels. The combination of low IGF-I and high IL-6 levels confers a high risk for progressive disability and death in older women, suggesting an aggregate effect of dysregulation in endocrine and immune systems. The joint effects of IGF-I and IL-6 may be important targets for treatments to prevent or minimize disability associated with aging.
The functional consequences of the age-associated decline in IGF-I are unknown. We hypothesized that low IGF-I levels in older women would be associated with poor muscle strength and mobility. We assessed this question in a population representative of the full spectrum of health in the community, obtaining serum IGF-I levels from women aged 70–79 yr, enrolled in the Women's Health and Aging Study I or II. Cross-sectional analyses were performed using 617 women with IGF-I levels drawn within 90 d of measurement of outcomes. After adjustment for age, there was an association between IGF-I and knee extensor strength (P = 0.004), but not anthropometry or other strength measures. We found a positive relationship between IGF-I levels and walking speed for IGF-I levels below 50 μg/liter (P < 0.001), but no relationship above this threshold. A decline in IGF-I level was associated with self-reported difficulty in mobility tasks. All findings were attenuated after multivariate adjustment. In summary, in a study population including frail and healthy older women, low IGF-I levels were associated with poor knee extensor muscle strength, slow walking speed, and self-reported difficulty with mobility tasks. These findings suggest a role for IGF-I in disability as well as a potential target population for interventions to raise IGF-I levels.
Hypertension is a leading cause of global disease, mortality, and disability. While individuals of African descent suffer a disproportionate burden of hypertension and its complications, they have been underrepresented in genetic studies. To identify novel susceptibility loci for blood pressure and hypertension in people of African ancestry, we performed both single and multiple-trait genome-wide association analyses. We analyzed 21 genome-wide association studies comprised of 31,968 individuals of African ancestry, and validated our results with additional 54,395 individuals from multi-ethnic studies. These analyses identified nine loci with eleven independent variants which reached genome-wide significance (P < 1.25×10−8) for either systolic and diastolic blood pressure, hypertension, or for combined traits. Single-trait analyses identified two loci (TARID/TCF21 and LLPH/TMBIM4) and multiple-trait analyses identified one novel locus (FRMD3) for blood pressure. At these three loci, as well as at GRP20/CDH17, associated variants had alleles common only in African-ancestry populations. Functional annotation showed enrichment for genes expressed in immune and kidney cells, as well as in heart and vascular cells/tissues. Experiments driven by these findings and using angiotensin-II induced hypertension in mice showed altered kidney mRNA expression of six genes, suggesting their potential role in hypertension. Our study provides new evidence for genes related to hypertension susceptibility, and the need to study African-ancestry populations in order to identify biologic factors contributing to hypertension.
Although fibroblast growth factor 23 (FGF23) has been implicated in the pathogenesis of cardiovascular disease, the relationship between FGF23 and cardiovascular disease has not been well characterized in the general population. The aim of this study was to determine whether serum FGF23 is independently associated with cardiovascular disease in older community-dwelling women.A cross-sectional design was used to examine the relationship between serum FGF23 and cardiovascular disease. The subjects consisted of a population-based sample of 659 women, aged 70-79 years, who participated in the Women's Health and Aging Studies in Baltimore, Maryland. Prevalent cardiovascular disease (coronary heart disease, stroke, congestive heart failure, and peripheral artery disease) was assessed through diagnostic algorithms and physician adjudication.Of the 659 women, 185 (28.1%) had cardiovascular disease. Median (25th, 75th percentile) intact serum FGF23 was 34.6 (25.2, 46.2) pg/ml. The prevalence of cardiovascular disease in the lowest, middle, and highest tertile of serum FGF23 was 22.6, 24.9, and 36.7% respectively (P=0.002). Serum log FGF23 was associated with cardiovascular disease (odds ratio per 1 s.d. increase=1.23, 95% confidence interval 1.17, 1.30; P<0.0001) in a multivariable logistic regression model, adjusting for age, race, smoking, education, body mass index, cognition, diabetes, hypertension, physical activity, total cholesterol, high-density lipoprotein cholesterol, and renal function.Elevated serum FGF23 concentrations are independently associated with prevalent cardiovascular disease in older community-dwelling women. Further studies are needed to elucidate the potential biological mechanisms by which FGF23 may be involved in the pathogenesis of cardiovascular disease.
Ghrelin is an endogenous stimulator of GH and is implicated in a number of physiological processes. Clinical trials have been performed in a variety of patient populations, but there is no comprehensive review of the beneficial and adverse consequences of ghrelin administration to humans.PubMed was utilized, and the reference list of each article was screened. We included 121 published articles in which ghrelin was administered to humans.Ghrelin has been administered as an infusion or a bolus in a variety of doses to 1850 study participants, including healthy participants and patients with obesity, prior gastrectomy, cancer, pituitary disease, diabetes mellitus, eating disorders, and other conditions. There is strong evidence that ghrelin stimulates appetite and increases circulating GH, ACTH, cortisol, prolactin, and glucose across varied patient populations. There is a paucity of evidence regarding the effects of ghrelin on LH, FSH, TSH, insulin, lipolysis, body composition, cardiac function, pulmonary function, the vasculature, and sleep. Adverse effects occurred in 20% of participants, with a predominance of flushing and gastric rumbles and a mild degree of severity. The few serious adverse events occurred in patients with advanced illness and were not clearly attributable to ghrelin. Route of administration may affect the pattern of adverse effects.Existing literature supports the short-term safety of ghrelin administration and its efficacy as an appetite stimulant in diverse patient populations. There is some evidence to suggest that ghrelin has wider ranging therapeutic effects, although these areas require further investigation.
Low testosterone (T) is associated with prevalent cardiovascular disease (CVD) and mortality. DHT, a more potent androgen, may also be associated with CVD and mortality, but few studies have examined this. The study objective was to examine whether T and DHT are risk factors for incident CVD and mortality. In a longitudinal cohort study, we evaluated whether total T, calculated free T (cFT), DHT, and calculated free DHT were associated with incident CVD and mortality in men in the Cardiovascular Health Study (mean age 76, range 66–97 years) who were free of CVD at the time of blood collection. The main outcomes were incident CVD and all-cause mortality. Among 1032 men followed for a median of 9 years, 436 incident CVD events and 777 deaths occurred. In models adjusted for cardiovascular risk factors, total T and cFT were not associated with incident CVD or all-cause mortality, whereas DHT and calculated free DHT had curvilinear associations with incident CVD (P < .002 and P = .04, respectively) and all-cause mortality (P < .001 for both). In a cohort of elderly men, DHT and calculated free DHT were associated with incident CVD and all-cause mortality. Further studies are needed to confirm these results and to clarify the underlying physiologic mechanisms.
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