Manuel Kirchen

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Magnesium (Mg) intake has been linked to bone mass and/or rate of bone loss in humans. Experimental Mg deficiency in animal models has resulted in impaired bone growth, osteopenia, and increased skeletal fragility. In order to assess changes in bone and mineral homeostasis that may be responsible, we induced dietary Mg deficiency in adult Simonsen albino(More)
Healing of 0.5 or 1.0-millimeter step-off defects associated with displaced intra-articular fractures of the medial femoral condyle was examined in fifty-four adult New Zealand White rabbits. The rabbits were treated with either immobilization for three weeks, intermittent active motion, or continuous passive motion for seven days. At twelve weeks, the(More)
Peptido-leukotrienes are short-lived organic molecules known to have potent biological effects as mediators of inflammation, hypersensitivity and respiratory disorders. However, little is known concerning their effects on bone cells. We have shown previously that stromal cells isolated from a human giant cell tumor secrete 5-HETE (5-hydroxyeicosatetraenoic(More)
Disorders in which magnesium (Mg) depletion is common have an associated high incidence of osteoporosis. Mg depletion in humans results in hypocalcemia, low serum parathyroid hormone (PTH) and 1, 25(OH)2-vitamin D levels, as well as PTH and vitamin D resistance which may serve as mechanisms for the development of osteoporosis. In order to determine if(More)
The effectiveness of methotrexate eluted from polymethylmethacrylate on cell lines established from giant cell tumor of bone was investigated in vitro to determine the possible efficacy of this treatment. Elation of methotrexate from polymethylmethacrylate beads and boluses was shown in vitro to be dose dependent and limited by the size of the bolus.(More)
Undemineralized methacrylate embedded bone biopsies and other bone specimens can be processed much more rapidly by application of acidified 2,2-dimethoxypropane (DMP) dehydration, which requires two hours, than by traditional graded ethanol dehydration, which requires at least four days. This shortened processing time is valuable when biopsy results are(More)
Human bone and cartilage specimens were evaluated for acid and alkaline phosphatase localization following varying fixation periods for fresh or frozen tissue. Formalin fixations of up to 183 hr were followed by embedment in methyl methacrylate; frozen tissue was examined either without fixation or following fixation for up to 1 hr and subsequent glycol or(More)
The appropriate irrigation fluid for use during arthroscopic procedures should be selected on the basis of fluid-tissue and fluid-instrumentation compatibility. This study describes a new irrigation fluid, Synovisol, that is isomolar, nonhemolytic, nonantigenic, has a low viscosity, and is nonconductive. The rabbit knee was used as a model to demonstrate(More)
Giant cell tumors of bone are common but unusual tumors that are comprised of multiple cell types. Most attention has been focused on the giant cells, which resemble osteoclasts morphologically and functionally. This study examines the properties of a cell line derived from mononuclear cells from one of these tumors, since it appears likely that these cells(More)
Bone healing was investigated histologically in a rat fibular osteotomy model subjected to microgravity (shuttle flight STS-29) and the tail suspension microgravity simulation model. Exposure to microgravity or tail suspension occurred during the last 5 days of a 10-day healing period. Periosteal osteogenesis and the development of vascular channels in both(More)