Charles A. Frolik

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The Wnt signaling pathway has recently been demonstrated to play an important role in bone cell function. In previous studies using DNA microarray analyses, we observed a change in some of the molecular components of the canonical Wnt pathway namely, frizzled-1 (FZD-1) and axil, in response to continuous parathyroid hormone (PTH) treatment in rats. In the(More)
beta-Lactam antibiotics such as penicillins and cephalosporins are synthesized by a wide variety of microbes, including procaryotes and eucaryotes. Isopenicillin N synthetase catalyzes a key reaction in the biosynthetic pathway of penicillins and cephalosporins. The genes encoding this protein have previously been cloned from the filamentous fungi(More)
Parathyroid hormone (PTH)(1-34), given once daily, increases bone mass in a variety of animal models and humans with osteoporosis. However, continuous PTH infusion has been shown to cause bone loss. To determine the pharmacokinetic profile of PTH(1-34) associated with anabolic and catabolic bone responses, PTH(1-34) pharmacokinetic and serum biochemical(More)
A procedure has been developed for the iodination of human transforming growth factor-beta (TGF-beta) with full retention of biological activity. Using the iodinated peptide, saturable receptors have been found for TGF-beta on normal rat kidney fibroblasts, a cell line that will grow in soft agar in the presence of TGFs but not in their absence. Scatchard(More)
Bone loss associated with postmenopausal osteoporosis can be reduced by treatment with antiresorptive agents such as estrogen or bisphosphonates. Whereas bisphosphonates primarily affect bone loss, estrogens have an advantage of also lowering serum cholesterol levels, although they have a detrimental effect in the uterus. Recently, raloxifene HCl, a(More)
The Cbfa1/Runx2 (referred to herein as Cbfa1) transcription factor has been shown to be essential for osteoblast differentiation and bone formation during embryogenesis. PTH given intermittently is a proven bone anabolic agent. Here, we investigated whether PTH regulates the expression and/or activity of Cbfa1 in osteoblastic cells and in a rat metatarsal(More)
The active site structure of isopenicillin N synthase (IPNS) has been previously studied by the use of Mössbauer, EPR, electronic absorption, and NMR spectroscopies [Chen, V.J., Frolik, C.A., Orville, A.M., Harpel, M.R., Lipscomb, J.D., Surerus, K.K., & Münck, E. (1989) J. Biol. Chem. 264, 21677-21681; Ming, L.-J., Que, L., Jr., Kriauciunas, A., Frolik,(More)
Human bone was sequentially extracted with 4 M guanidine hydrochloride to remove nonmineralized tissue components, 0.5 M EDTA to dissolve the mineral phase, 4 M guanidine hydrochloride to remove matrix associated proteins and finally a combination of 4 M guanidine hydrochloride and 0.5 M EDTA to remove residual proteins. The extracts were examined for the(More)
UNLABELLED GSK-3, a component of the canonical Wnt signaling pathway, is implicated in regulation of bone mass. The effect of a small molecule GSK-3 inhibitor was evaluated in pre-osteoblasts and in osteopenic rats. GSK-3 inhibitor induced osteoblast differentiation in vitro and increased markers of bone formation in vitro and in vivo with concomitant(More)
NRK fibroblasts exposed to transforming growth factor-beta (TGF-beta) show increased binding of radiolabeled epidermal growth factor (EGF) relative to untreated cells. The binding of another growth factor, rat insulin-like growth factor-II, is unaffected. The increase in EGF binding induced by TGF-beta is not due to inhibition of EGF processing nor to an(More)