Monday, May 21, 2012

Measuring Cr and Cobalt levels in the organs.

    J Biomed Mater Res A. 2012 Jun;100(6):1529-38. doi: 10.1002/jbm.a.34091. Epub 2012 Mar 15.

    Distribution of metal released from cobalt-chromium alloy orthopaedic wear particles implanted into air pouches in mice.

    Source

    Bioengineering Unit, University of Strathclyde, Wolfson Center, Glasgow G4 0NW, United Kingdom.

    Abstract

    Metal-on-metal hip replacement implants generate wear debris and release ions both locally and systemically in patients. To investigate dissemination of metal, we determined blood and organ levels of cobalt (Co), chromium (Cr), and molybdenum (Mo) following the implantation of Co-Cr alloy wear debris in mice using skin pouches as a model system. We observed increased metal levels in blood for up to 72 h; the levels of Co were highest and remained elevated for 7 days. Co levels were elevated in all organs studied (liver, kidney, spleen, lung, heart, brain, and testes), with the peak at 48 h; highest levels were measured in liver and kidney (838.9 ± 223.7 ng/g in liver, and 938.8 ± 131.6 ng/g in kidney). Organ Cr levels were considerably lower than Co levels, for example, Cr in kidney was 117.2 ± 12.6 ng/g tissue at 48 h. Co is more mobile than Cr, reaching higher levels at earlier time points. This could be due to local tissue binding of Cr. Exposure to Co-Cr particles in vivo altered antioxidant enzyme expression and activities. We observed induction of catalase protein in the liver and glutathione reductase (GR) and peroxidase (GPx) proteins in the spleen. Activities of catalase and GPx in the liver were significantly increased while that of GR was decreased in the kidney. Organs of mice with Co-Cr particle implantation were exposed to increased metal levels capable of inducing reactive oxygen species scavenging enzymes, suggesting the tissue may be subjected to oxidative stress; however, the overall antioxidant defence system was not markedly disturbed.
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    Definitions


    Redox (reduction-oxidation) reactions include all chemical reactions in which atoms have their oxidation state changed
    In
    chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound.
    Oxidative stress represents an imbalance between the systemic manifestation of
    reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. Disturbances in the normal redox state of cells can cause toxic effects through the production of peroxides and free radicals that damage all components of the cell, including proteins, lipids, and DNA. Further, some reactive oxidative species act as cellular messengers in redox signaling. Thus, oxidative stress can cause dispruptions in normal mechanisms of cellular signaling

    Carcinogenesis or oncogenesis or tumorigenesis is literally the creation of cancer. It is a process by which normal cells are transformed into cancer cells. It is characterized by a progression of changes on cellular and genetic level that ultimately reprogram a cell to undergo uncontrolled cell division, thus forming a malignant mass.

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