Thomas A. Linkhart

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Analysis of MM14 mouse myoblasts demonstrates that terminal differentiation is repressed by pure preparations of both acidic and basic fibroblast growth factor (FGF). Basic FGF is approximately 30-fold more potent than acidic FGF and it exhibits half maximal activity in clonal assays at 0.03 ng/ml (2 pM). FGF repression occurs only during the G1 phase of(More)
The studies summarized in this report were intended to determine whether salmon calcitonin had direct effects on bone formation indices in vitro. The results of these investigations demonstrate acute effects of calcitonin on skeletal tissues derived from embryonic chickens to increase calvarial cell proliferation ([3H]thymidine incorporation into DNA) and(More)
Recent studies support the concept that IGF-binding protein-5 (IGFBP-5) stimulates bone formation, at least in part, via IGF-independent mechanisms. To evaluate this hypothesis further, we evaluated in vitro and in vivo effects of IGFBP-5 on bone formation parameters using the IGF-I knockout (KO) mouse. Treatment of serum-free cultures of osteoblast clones(More)
BACKGROUND An in vivo gene therapy strategy was developed to accelerate bone fracture repair. METHODS Direct injection of a murine leukemia virus-based vector targeted transgene expression to the proliferating periosteal cells arising shortly after fracture. Cyclooxygenase-2 (Cox-2) was selected because the transgene for its prostaglandin products that(More)
Although it has been established that PTH exerts potent anabolic effects on bone in animals and humans, the mechanism of PTH action on bone remains controversial. Based on the previous findings that PTH treatment increased production of IGF-I in bone cells and that PTH effects on bone cells in vitro were blocked by IGF-I-blocking antibodies, we proposed(More)
Recent work has demonstrated differences in femoral bone mineral density between two common inbred strains of mice, C3H/HeJ (C3H) and C57BL/6J (B6), across a wide age range. To investigate one possible mechanism that could affect acquisition and maintenance of bone mass in mice, we studied circulatory and skeletal insulin-like growth factor-I (IGF-I) and(More)
Fibroblast growth factor-inducible 14 (Fn14), distantly related to tumor necrosis factor receptor superfamily and a receptor for TWEAK cytokine, has been implicated in several biological responses. In this study, we have investigated the role of Fn14 in skeletal muscle formation in vitro. Flow cytometric and Western blot analysis revealed that Fn14 is(More)
Current research is reviewed regarding the actions of three growth factor systems on bone formation: insulin-like growth factors (IGFs), transforming growth factor-betas (TGF betas), and bone morphogenetic proteins (BMPs). Each growth factor family consists of multiple related growth factor genes. TGF betas and BMPs 2-7 are subfamilies of a larger TGF beta(More)
Insulin-like growth factor-binding protein-5 (IGFBP-5) is produced by osteoblasts and potentiates insulin-like growth factor mitogenic stimulation in osteoblast cell cultures. Progesterone (PG) increased IGFBP-5 expression in normal human osteoblasts and increased IGFBP-5 transcription in U2 human osteosarcoma cells. We developed a chloramphenicol(More)