The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Conclusion Histomorphometric studies have made an important contribution to our understanding of how pharmacologic interventions affect BMD and bone strength in patients with osteoporosis. For antiresorptive agents, the therapeutic effect is mediated predominantly by suppression of bone turnover; in the case of more potent antiresorptive agents, changes in secondary mineralization also occur that...
A variety of in vivo and in vitro experimental models have been used to explore the effects of glucococorticoids in bone. Chronically high levels of glucocorticoids typically decrease bone mass in humans and animals and inhibit markers of bone formation in organ and cell cultures. However, under certain experimental conditions, glucocorticoids can stimulate osteoblast differentiation and bone formation...
Unintentional injuries are the seventh leading cause of death in adults ages 65 and older, and the greatest number of these deaths results from fall-related injuries. In addition to the startling mortality, the morbidity associated with fall-related injuries, particularly hip fractures, has become a research imperative. This article reviews a series of studies that was undertaken to determine the...
The genetic factors that contribute to the susceptibility of osteoporosis are likely to be extremely heterogeneous, reflecting the complex genetic program that controls the cellular aspects of bone formation and remodeling. Because it is unlikely that current genetic methods will have the power to resolve multiple subtle genetic effects from the environmental contribution, biologic approaches will...
A mechanism explaining the differential skeletal effects of intermittent and continuous elevation of serum parathyroid hormone (PTH) remains elusive. Intermittent PTH increases bone formation and bone mass and is being investigated as a therapy for osteoporosis. By contrast, chronic hyperparathyroidism results in the metabolic bone disease osteitis fibrosa characterized by osteomalacia, focal bone...
Osteoporosis is a disease characterized by fragile bones and high susceptibility to low-trauma fractures. It is a serious health problem, especially in elderly women. Bone mineral density (BMD) has been employed most commonly as the index for defining and studying osteoporosis. BMD has high genetic determination, with heritability ranging from 50 to 90%. Various genemapping approaches have been applied...
Significant calcium transfer from the mother to the fetus and infant occurs during pregnancy and lactation, theoretically placing the mother at an increased risk for osteoporosis later in life. During pregnancy, intestinal calcium absorption increases to meet much of the fetal calcium needs. Maternal bone loss also may occur in the last months of pregnancy, a time when the fetal skeleton is rapidly...
To investigate aging bone structure of humans—here, in the lumbar vertebral bodies—requires methodologies that have sufficiently high resolving power yet still have sufficient width and depth of field. No clinical imaging method can come close to meeting the first requirement, leading to the disadvantage of being limited to postmortem studies. Few microscopic methods meet the second and third requisites...
Adolescence is a period of rapid skeletal growth during which nearly half of the adult skeletal mass is accrued. This life stage is a window of opportunity for influencing peak bone mass and reducing the risk of osteoporosis later in life. Endocrine factors that may influence peak bone mass include insulin-like growth factor-1, which regulates skeletal growth, and gonadotropic hormones, which stimulate...
Control of the cell cycle is accomplished by sequentially activated cyclin-dependent kinases and the action of inhibitory proteins. We have shown that exposure of 235-1 rat pituitary tumor cells to dexamethasone (DEX) leads to a 50% reduction in growth rate. We examined the mechanism by which DEX affects 235-1 cell proliferation by determining the expression levels of proteins involved in cell-cycle...
Conclusion It is eminently reasonable to exploit the properties of radioactive iodine for the treatment of thyroid cancer, which has a unique avidity for iodine. An LID that restricts nonradioactive iodine, 127I, is rational if it allows greater radioactive iodine localization and delivery of tumoricidal doses of radiation. As discussed, the increased turnover of iodine on an LID and decreased pool...
This study was designed to determine whether four peptide hormones consisting of amino acids 1–30—long-acting natriuretic hormone (LANH), 31–67 (vessel dilator), 79–98 (kaliuretic hormone), and 99–126 (atrial natriuretic hormone [ANH])—of the 126 amino acid atrial natriuretic prohormone increase the circulating concentration of testosterone in healthy humans (n=30). Vessel dilator, kaliuretic hormone,...
The effect of intracerebroventricular (icv) injection of allopregnanolone (5α-pregnan-3α-ol-20-one) on the dopaminergic and reproductive function in ovariectomized rats primed with estrogen and progesterone was investigated. Thirty minutes after icv allopregnanolone injection, the sexual receptivity, luteinizing hormone (LH) release, dopamine content, and release in the medial basal hypothalamus (MBH)...
Reported species differences in the stimulus-secretion coupling of insulin release made it important to compare the Ca2+ handling of rat β-cells with that previously observed in mice. Single β-cells and small aggregates were prepared from pancreatic islets of Wistar rats, attached to cover slips and then used for measuring the cytoplasmic Ca2+ concentration ([Ca2+]i) with the ratiometric fura-2 technique...
Variants of growth hormone (GH) are present in most vertebrates. Chicken GH (cGH) undergoes posttranslational modifications that contribute to its structural diversity. Although the 22-kDa form of GH is the most abundant, some other variants have discrete bioactivities that may not be shared by others. The proportion of cGH variants changes during ontogeny, suggesting that they are regulated differentially...
Chronic glucocorticoid therapy causes rapid bone loss and clinical osteoporosis. We previously found that dexamethasone, a potent glucocorticoid, increased renal expression of vitamin D-24-hydroxylase, which degrades such vitamin D metabolites as 25-hydroxyvitamin D3 and 1α,25-dihydroxyvitamin D3 (1,25[OH]2D3). We therefore investigated the mechanisms of this increase in UMR-106 osteoblast-like cells...
Interleukin-6 (IL-6) is a pleiotropic cytokine with differentiation and growth-promoting effects. Extensive studies in experimental animals denote that IL-6 is produced in various endocrine organs and participates in the local control of endocrine cell function. The expression of this cytokine in human endocrine glands, however, has only been examined in a limited number of studies. We investigated...
Dehydroepiandrosterone (DHEA) and its sulfate ester (DHEA-S) exert multiple effects in rodent and human brain. Several findings suggest that insulin-like growth factor-1 (IGF-1) is involved in the actions of DHEA. In this study, we assessed whether systemic administration of DHEA regulates the IGF-1 system in the hypothalamus, hippocampus, cerebral cortex, and cerebellum of adult rats. DHEA resulted...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.