Effects of 6 Years Of Growth Hormone (GH) Treatment On Bone Mineral Density In GH-Deficient Adults OBJECTIVE: Adults with growth hormone (GH) deficiency are often osteopenic. Short-term GH replacement therapy has been shown to improve bone mineral density (BMD). However, whether the increases in BMD are progressive with time is still unclear. Continue reading…

Anabolic Steroids The term "anabolic steroids" refers to testosterone derivatives that are used either clinically or by athletes for their anabolic properties. However, scientists have questioned the anabolic effects of testosterone and its derivatives in normal men for decades. Most scientists concluded that anabolic steroids do not increase muscle size or strength in people with normal gonadal function and have discounted positive results as unduly influenced by positive expectations of athletes, inferior experimental design, or poor data analysis. Continue reading…

Body size, insulin/IGF signaling and aging in the nematode Caenorhabditis elegans.A number of recent studies of aging in Drosophila, mice and dogs have shown an association between reduced body size and increased lifespan. It is unclear (a) whether such an association is a general feature of animal species; and (b) whether the association reflects an effect of body size on aging, or pleiotropic effects of common determinants of growth and aging. Continue reading…

IGF-1 receptor regulates lifespan and resistance to oxidative stress in mice.Studies in invertebrates have led to the identification of a number of genes that regulate lifespan, some of which encode components of the insulin or insulin-like signalling pathways. Examples include the related tyrosine kinase receptors InR (Drosophila melanogaster) and DAF-2 (Caenorhabditis elegans) that are homologues of the mammalian insulin-like growth factor type 1 receptor (IGF-1R). Continue reading…

Extended longevity in mice lacking the insulin receptor in adipose tissue.Caloric restriction has been shown to increase longevity in organisms ranging from yeast to mammals. In some organisms, this has been associated with a decreased fat mass and alterations in insulin/insulin-like growth factor 1 (IGF-1) pathways. Continue reading…

Regulation of insulin-like growth factor-I in skeletal muscle and muscle cells.Growth hormone (GH) and insulin-like growth factor-I (IGF-I) are potent regulators of muscle mass. Transgenic mice that over-express these proteins exhibit dramatically enlarged skeletal muscles. In contrast, malnutrition, critical illness, sepsis, and aging are all associated with a dramatic reduction in muscle mass and function. Continue reading…

Insulin-like growth factor 1 (IGF-1) and aging: controversies and new insights. Insulin/insulin-like growth factor (IGF) signaling plays a major role in the control of aging and life span in invertebrates. Major extension of life span in growth hormone receptor knock out (GHR-KO) mice that are GH resistant, and subsequently, IGF-I-deficient indicates that similar mechanisms may operate in mammals. Continue reading…

Hormonal regulation of aging and life span A regulatory growth factor pathway has been implicated in determination of longevity in a variety of species. Altered signaling in this pathway confers not only extended life spans but also increased resistance to oxidative stress. A new report using mice engineered to express fewer receptors for insulin-like growth factor (IGF-I), therefore reducing the signaling through this pathway, provides strong supporting evidence that IGF-I signaling does play a significant role in longevity. Continue reading…

Hormone replacement therapy and improved survival among postmenopausal women diagnosed with colon cancer (USA).OBJECTIVES: Hormone replacement therapy (HRT) has been inversely associated with colon cancer incidence in several epidemiologic studies. In this study we used data from a population-based incident case-control study of colon cancer to evaluate the role of HRT use in survival after diagnosis with colon cancer. Continue reading…

Body mass index and colon cancer: an evaluation of the modifying effects of estrogen (United States). OBJECTIVE: The association between body mass index (BMI) and colon cancer has been reported to be different for men and women. No prior literature has examined if estrogen influences these differences. Continue reading…