Radioprotective effect of N -acetyl-L-cysteine free radical scavenger on compressive mechanical properties of the gamma
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ORIGINAL PAPER
Radioprotective effect of N-acetyl-L-cysteine free radical scavenger on compressive mechanical properties of the gamma sterilized cortical bone of bovine femur Farzaneh Allaveisi • Bijan Hashemi • Seyed Mohammad Javad Mortazavi
Received: 15 January 2014 / Accepted: 1 April 2014 Ó Springer Science+Business Media Dordrecht 2014
Abstract Gamma sterilization of bone allografts is used as a gold standard method to provide safety against disease transmission. However, it is well documented that high dose levels of ionizing radiation can degrade bone mechanical properties. This effect, which is attributed to the formation of free radicals through radiolysis of the water content of collagen, can lead to post-implantation difficulties such as prefailure and/or secondary fractures of bone allografts. Recently, treatment of irradiated allografts with free radical scavengers is used to protect them against radiation-induced damages. This study aimed to investigate the radioprotective role of N-acetyl-Lcysteine (NAC) during the gamma sterilization of the cortical bone of bovine femurs using the compressive test. Totally, 195 cubic specimens with a dimension of 5 9 5 9 3 cubic mm were divided into 13 groups including a control and 12 experimental groups exposed to 18, 36, and 70 kGy at three different NAC concentrations (1.25, 12.5, and 25 mM for 18 kGy; 5, 50, and 100 mM for 36 kGy; 10, 100,
F. Allaveisi B. Hashemi (&) Department of Medical Physics, Faculty of Medical Sciences, Tarbiat Modares University, Al-Ahmad and Chamran Cross, P.O. Box 14115-111, 1411713116 Tehran, Iran e-mail: [email protected] S. M. J. Mortazavi Joint Reconstruction Research Center, Tehran University of Medical Sciences, Tehran, Iran
and 200 mM for 70 kGy). The mechanical behavior of the sterilized specimens was studied using the uniaxial compressive test. The results indicated a concentration-dependent radioprotection effect of NAC on the plastic properties of the cortical bones. The concentration dependency of NAC was in turn related to radiation dose levels. In conclusion, treatment of bone specimens with a characteristic concentration of NAC during exposure to specific radiation dose levels can provide an efficient radioprotection window for preserving the mechanical stability of gamma sterilized allografts. Keywords Gamma sterilization Cortical bone Free radical scavenger Compression test Allograft Mechanical properties
Introduction The particular interest in employing the bone grafting to reconstruct a vast range of orthopedic pathological situation such as traumatic injuries and tumor deficiencies has been continuously increased (Akkus et al. 2005; Costain and Crawford 2009). These grafting products bring the desired advantages via producing the mechanical stability as well as osteoinductive, osteogenic, and osteoconductive attributes (Costain and Crawford 2009). However, with the increasing use
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of tissue grafts, there are also problems related to microorganism contamination transferr
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