Human bone sample preparation

The study of obsidian by NAA has proved to be particularly fruitful because of the relatively limited number of sources and the extent to which it was traded (Beardsley et al. 1996, Cook 1995, Darling and Hayashida 1995, Kuzmin et al. 2002, Leach 1996). Studies have also extended to include other volcanic materials such as pumice (Bichler et al. 1997, Peltz et al. 1999). NAA has also been used for the analysis of flint as OES is insensitive and not reproducible due to the effect of the high silica content, and AAS requires significant sample preparation (Aspinall and Feather 1972). The wide range of appropriate materials extends to organic materials such as human bone (Farnum et al. 1995), and its exceptional sensitivity to trace elements has led to its wide use in geochemistry (for example in determining trace [ppb] contaminants in waters) and more recently in forensic chemistry. 

Trace elements in human teeth and bone can be used to reconstruct dietary patterns in prehistoric populations. Several methods have been used to generate chemical data for prehistoric human bone. Among these methods INAA of solid bone and ICP-MS and ICP-ES of solutions have been used most often (33-35). With INAA, portions of bone or teeth are cleaned, sealed in vials, and irradiated to provide data for 8-10 elements. Samples analyzed by ICP-MS are digested in acid prior to analysis. In both cases, sample preparation is cumbersome. 

The application of quality control procedures to ensure that satisfactory analytical performance of enzyme assays is maintained on a day-to-day basis is complicated by the tendency of enzyme preparations to undergo denaturation with loss of activity. This maltes it difficult to distinguish between poor analytical performance and denaturation as possible causes of a low result obtained for a control sample introduced into a batch of analyses. Assured stability within a defined usable time span is therefore the prime requirement for enzyme control materials, as it is for enzyme calibrators. However, specifications for the two types of materials can differ in other respects. Because the function of a calibrator is to provide a stated activity under defined assay conditions, it is not necessary for it to show sensitivity to changes in the assay system identical to those of the samples under test therefore within certain Umits, enzymes from various sources can be considered in the search for stability. However, it is the function of a control to reveal small variations in reaction conditions, so it must mimic the samples being analyzed. The preparation of enzymes from human sources is not by itself a guarantee of an effective control. For example, human placental ALP is very stable, but it differs significantly in kinetic properties from the liver and bone enzymes that contribute most of the ALP activity of human serum samples it is therefore not an ideal enzyme for use in control material for the determination of ALP. 

Human biological materials to be investigated include (a) hard calcified tissues, e.g. bone, teeth, other calcified formations (b) semi-hard tissue, e.g. hair, nails (c) soft body tissues and (d) various biological fluids and secretions in the human body. The treatment of each of these materials varies from one material to another and, as stated earlier, is often determined by the instrumental method to be employed for measuring the analytical signal, the elements to be determined and the concentration levels at which these are present. For the purposes of this discussion, it shall be generally assumed that the analytical techniques employed include atomic absorption spectrometry both with (F-AAS) as well as with a furnace (GF-AAS), neutron activation analysis (NAA), flame emission spectrometry (FES) voltammetric methods and the three inductively coupled plasma spec-trometric methods viz. ICP-atomic emission spectrometry, ICP-mass spectrometry and ICP-atomic fluorescence spectrometry. The sample preparation of biological methods for all ICP techniques is usually similar (Guo, 1989). 

Hislop, J.S., Parker, A., Spicer, G.S. and Webb, M.S.W. (1973). The determination of lead in human rib bone, AERE-R 7321, Available from HMSO, UK Hohl, C. Seiler, M. and Seiler, H.G. (1989). Procedures for sample preparation of biological materials for the determination of trace elements, Mitt. Geb. Lebensmittle-unters. Hyg., 80(1), 100-112... 

DinizMG, et al. Surface topography modulates the osteogenesis in human bone marrow cell cultures grown on titanium samples prepared by a combination of mechanical and acid treatments. J Mater Sci Mater Med 2002 13(4) 421—32. 

Oxygen isotopes in ancient human skeletal remains are found in both bone and tooth enamel. Samples for the analysis of human skeletal remains are normally taken from dental enamel due to conditions of preservation and resistance to diagenesis. The hydroxyapatite mineral, a primary component of enamel, contains oxygen, in both phosphate groups (POp and carbonates (CO ). Phosphate and carbonate produce comparable results for oxygen isotope ratios, but less sample is needed for carbonate, preparation is less demanding, and results between laboratories are more comparable. 

Changes in DNA supercoiling were analyzed using nucleoid sedimentation as previously described and are shown in Fig. 1 (2). Human granulocyte-macrophage preciusor cells were prepared from bone marrow samples (obtained with consent from healthy volunteers) by density fractionation and adherence (2). Cells were exposed to two inducers of granulocytic differentiation (retinoic acid and G-CSF) and two inducers of monocytic differentiation (phorbol myristate acetate and vitamin D3). Treatment with differentiation inducers and culture conditions are described elsewhere (2). 

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