Bone Radicals

Bone Radicals. The recorded ESR signals (Fig 3) correspond to an extremely stable C02° radical trapped in the lattices of hydroxyapatite [Caio(P04)6(OH)2] which constitutes approximately 60% of the bone composition. It consists of a radiation-specific asymmetrical signal (A and B, g=2.002 g=1.998) superimposed upon a symmetrical endogenous signal (C, g=2.005) of much lower amplitude. Detection of irradiated bone samples is possible above a dose of 0.5 kGy, covering the majority of commercial applications for the foodstuffs considered. Detection limits and stability of the... 

Ascorbic acid—vitamin C—is an essential nutrient that the human body cannot manufacture from other compounds. It is needed for the formation of collagen, the protein that makes up connective tissue, and is essential to muscles, bones, cartilage, and blood vessels. It is a strong antioxidant, preventing damage from oxygen free radicals. 

The PMMA bone cement is formed from a mixture of prepolymer PMMA powder, which contains a free-radical initiator, and liquid MMA monomer. In the operating theatre the powder and liquid are mixed, causing the initiator to dissolve and bring about polymerisation in the monomer component. The powder pre-polymer does not dissolve in the monomer but remains in the newly polymerised materials as a kind of reinforcing filler. 

Copper is an essential trace element. It is required in the diet because it is the metal cofactor for a variety of enzymes (see Table 50—5). Copper accepts and donates electrons and is involved in reactions involving dismu-tation, hydroxylation, and oxygenation. However, excess copper can cause problems because it can oxidize proteins and hpids, bind to nucleic acids, and enhance the production of free radicals. It is thus important to have mechanisms that will maintain the amount of copper in the body within normal hmits. The body of the normal adult contains about 100 mg of copper, located mostly in bone, liver, kidney, and muscle. The daily intake of copper is about 2—A mg, with about 50% being absorbed in the stomach and upper small intestine and the remainder excreted in the feces. Copper is carried to the liver bound to albumin, taken up by liver cells, and part of it is excreted in the bile. Copper also leaves the liver attached to ceruloplasmin, which is synthesized in that organ. 

Activated B cells produce plasma cells, which form antibodies that, in combination with complement, result in accumulation of polymorphonuclear leukocytes. Polymorphonuclear leukocytes release cytotoxins, oxygen free radicals, and hydroxyl radicals that promote cellular damage to synovium and bone. 

Radical polymerization of maleic anhydride and fullerene was used to obtain a new material, the photodynamic properties of which have been studied in vitro and in vivo. HeLa and bone tumor cell growth were inhibited by treatment with fullerene and light, so the polymer was tested on mice affected by bone tumor. After injection and irradiation, tumor size and weight were reduced and the mouse survival time was extended (Jiang and Li, 2007). The photodynamic properties of a supramolecular cucurbit[8]uril-fullerene complex have been studied by the same authors (Jiang and Li, 2006) who attributed HeLa cell death mainly to the damage of membrane phosphohpids and proteins. 

The ultimate success of methyl methacrylate bone cements in surgical arenas depends on its application at an appropriate viscosity. Recent studies have raised concerns that the long-term stability of bone cements may be compromised by the empirical way in which the setting of samples is determined [6]. The literature from one manufacturer states that, in addition to the concentration effects one would expect in a biphasic free-radical... 

Since Cu ions can catalyse formation of the dangerous hydroxyl radical, its concentration in both the intra- and extracellular compartments is maintained at very low levels by binding to the protein metallothionine. Deficiency of copper results in defects in formation of connective tissue, which may cause cardiovascular problems and poor bone formation. 

Clozapine and olanzapine are atypical antipsychotic drugs used in the treatment of schizophrenia. Their strnctnres are depicted in Scheme 2.36. The use of clozapine and olanzapine, which are more effective than standard neuroleptic drugs in the treatment of refractory schizophrenia, is, however, limited becanse of their adverse effects. These adverse effects are ascribed to the formation of the corresponding cation-radicals in living organisms under oxidation by bone marrow cells. These cation-radicals eliminate protons from the NH fragments and generate their nitrenium cations. The nitreninm cations are covalently bonnd to the life-important proteins. This results in the toxic effects of clozapine and olanzapine (Sikora et al. 2007). 

One of the standardized methods, electron spin resonance (ESR) technique, permits identification of food that contains a hard, dry matrix, e.g., bone. When food containing bone is irradiated, free radicals are produced and trapped in the crystal lattice of the bone, which can be detected by ESR spectroscopy [137]. Thermoluminescence of contaminating minerals for detection of radiation treatment of, e.g., spices and dried fruits can be successfully applied [138, 139]. Another standardized method that has been developed for identification of irradiated fat-containing foods is the mass-spectrometric detection of radiation-induced 2-alkylcyclobutanones after gas-chromatographic separation [140]. The... 

Orodental infection caused by mixed aerobic, anaerobic bacteria including Vincent s infection caused by Fusobac-terium. Tetracycline also prove to be beneficial in peridontal inflammation by scavenging free radicals. Its use in pregnancy, lactation and in children is contraindicated. Its use in dentistry is very much restricted due to its chelating effect on teeth and bones. 

Seal, S.N., Hoet, R.M.A., Raats, J.M.H., Radic, M.Z. (2000). Analysis of autoimmune bone marrow by antibody phage display, Somatic mutations and CDR3 Arginines in anti-DNA and V genes. Arthritis. Rheum., 43, 2132-2138. 

The heme iron in the peroxidase is oxidized by the peroxide from III+ to V4- in compound I. The compound I is reduced by two sequential one-electron transfer processes giving rise to the original enzyme. A substrate-free radical is in turn generated. This may have toxicological implications. Thus the myeloperoxidase in the bone marrow may catalyze the metabolic activation of phenol or other metabolites of benzene. This may underlie the toxicity of benzene to the bone marrow, which causes aplastic anemia (see below and chap. 6). The myeloperoxidase found in neutrophils and monocytes may be involved in the metabolism and activation of a number of drugs such as isoniazid, clozapine, procainamide, and hydralazine (see below). In in vitro systems, the products of the activation were found to be cytotoxic in vitro. 

When bone is treated with ionising radiation, free radicals are trapped in the crystal lattice of the bone (Gordy etal., 1955) and consequently can be detected by EPR spectroscopy. Prior to its application for the identification of irradiated food, the technique was used to date archaeological specimens (Ikeya and Miki, 1980) and as an in-vivo dosimeter to determine the level of human exposure to radiation (Pass and Aldrich, 1985). 

Chicken can be retailed either frozen or chilled and irradiation can also be applied under both of these temperature regimes. In samples irradiated in the frozen state, the movement of free radicals is hindered and as expected fewer radicals are trapped in the bone. Consequently, the intensity of the signal induced in bone from irradiated frozen chicken was lower than in samples from chilled poultry carcasses given the same irradiation dose (Dodd etal., 1992 Stevenson and Gray, 1990) (Figure 4). 

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