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The primary defect in mice lacking the c-src gene is osteopetrosis, a deficiency in bone resorption by osteoclasts. Osteoclasts express high levels of the c-Src protein and the defect responsible for the osteopetrotic phenotype of the c-src-deficient (src-) mouse is cell-autonomous and occurs in mature osteoclasts. However, the specific signalling pathways(More)
Gonadal failure induces bone loss while obesity prevents it. This raises the possibility that bone mass, body weight, and gonadal function are regulated by common pathways. To test this hypothesis, we studied leptin-deficient and leptin receptor-deficient mice that are obese and hypogonadic. Both mutant mice have an increased bone formation leading to high(More)
The parathyroid glands are the only known source of circulating parathyroid hormone (PTH), which initiates an endocrine cascade that regulates serum calcium concentration. Glial cells missing2 (Gcm2), a mouse homologue of Drosophila Gcm, is the only transcription factor whose expression is restricted to the parathyroid glands. Here we show that(More)
1,25-Dihydroxyvitamin D3 plays a major role in intestinal calcium transport. To determine what phenotypic abnormalities observed in vitamin D receptor (VDR)-ablated mice are secondary to impaired intestinal calcium absorption rather than receptor deficiency, mineral ion levels were normalized by dietary means. VDR-ablated mice and control littermates were(More)
1,25-Dihydroxyvitamin D3 has been shown to play an important role in vitro in regulating osteoblast gene transcription and promoting osteoclast differentiation. To address the role of the vitamin D receptor (VDR) in skeletal homeostasis, formal histomorphometric analyses were performed in VDR null mice in the setting of impaired mineral ion homeostasis as(More)
BACKGROUND In Germany, vitamin D intake from food and synthesis in the skin is low, which leads to low 25(OH)D serum concentrations. In contrast to many other countries, general vitamin D food fortification is still prohibited in Germany, although the European Commission published a regulatory framework to harmonize addition of vitamins to foods. Thus the(More)
Primary osteoporosis is an age-related disease characterized by an imbalance in bone homeostasis. While the resorptive aspect of the disease has been studied intensely, less is known about the anabolic part of the syndrome or presumptive deficiencies in bone regeneration. Multipotent mesenchymal stem cells (MSC) are the primary source of osteogenic(More)
Parathyroid hormone-related peptide (PTHrP) appears to play a major role in skeletal development. Targeted disruption of the PTHrP gene in mice causes skeletal dysplasia with accelerated chondrocyte maturation (Amizuka, N., H. Warshawsky, J.E. Henderson, D. Goltzman, and A.C. Karaplis. 1994. J. Cell Biol. 126:1611-1623; Karaplis, A.C., A. Luz, J. Glowacki,(More)
Bone development is a multistep process that includes patterning of skeletal elements, commitment of hematopoietic and/or mesenchymental cells to chondrogenic and osteogenic lineages, and further differentiation into three specialized cell types: chondrocytes in cartilage and osteoblasts and osteoclasts in bone. Although PRL has a multitude of biological(More)
Compared to anurans from other families, landings of toads (Bufonidae) during saltation appear well coordinated and the initial landing impact is absorbed exclusively by the forelimbs. Although the forelimbs and particularly the pectoral girdle have been suggested to be important for shock absorption, the functional roles of its various elements have not(More)