Soft tissues sampling time

Figure 8. Calcium values in vertebrate bone and soft tissue samples versus 6 Ca in dietary source (Skulan and DePaolo 1999). Bone values are systematically about 1.3%o lower than source values. Soft tissue values are more variable. All of the values are hypothesized to reflect the balance between Ca dietary intake and exchange with bone calcium (Fig. 9). The soft tissue values are variable largely because the residence time of Ca in the tissues is short. The high value of the egg white reflects Rayleigh-type distillation the egg white loses light Ca to the shell as the shell forms. The small amount of Ca left in the egg white is highly fractionated. The low 6 Ca value of the seal muscle is interpreted as a sign of distress the seal may have had a dietary Ca deficiency for several days or longer before it died, and hence was deriving most of its Ca from bone dissolution.

Few reports are available on the potential effect of chemical concentration on the BAF in an aquatic organism (e.g., Mayer, 1976). Yet, a key assumption of EP theory is the independency of BAF relative to exposure concentration. To our knowledge, there is only one report (Huckins et al., 2004) in the peer-reviewed literature, where the effect of chemical exposure level on concentration factors (CFs) or BAFs has been tested in side-by-side BMO and passive sampler exposures. Huckins et al. (2004) defined CF as the ratio of the concentration in a sample matrix (whole body [soft tissues in the case of bivalves] or whole SPMDs) relative to the concentration in the ambient exposure medium at any moment in time, whereas the A sw and BAF (includes biomagnilication) represent the maximal CF. Similar to ATs s and BAFs, CFs are expected to be independent of exposure concentrations, when residue exchange follows first-order kinetics. 

Chemistry offers a reliable method of extracting information from a large variety of archaeological finds. Some of the most important of these are human remains. Human remains from ancient times are usually skeletons, as the soft tissues of the body decompose quickly. But in Egypt and a few other places, archaeologists have discovered more complete samples. Wealthy Egyptians, believing in an afterlife that required maintenance of the body, were often preserved after death. These... 

As these are mostly diagnosed by excision biopsy, there is a paucity of data as to the protein status before excision. At times up to 20 years later, when dissemination has followed, apart from some predilection of metastases for unusual bony sites (Wll), the disease can be indistinguishable from myelomatosis, and I have usually had no diflSculty in finding paraproteins. Careful study of preoperative serum samples in 26 patients with biopsy proven soft-tissue plasmacytoma and no obvious metastases only detected paraproteins in 11 (yDl, yG9, yMl), and this may be because at least 20-50 g tumor is needed to render them visible. 

In any imaging experiment, the critical issues are sample preparation, image contrast, spatial resolution, field of view, and total time of the experiment Relative to other imaging techniques, the NMR spectroscopists s control over the image contrast mechanisms is exceptional. Of course, MRI images are affected by the number of nuclei in each volume element In addition, the NMR relaxation dynamics, Ti and T2, can be used to control image contrast, especially for the soft tissues in the human body. Sample preparation is perfectly simple for the patient remove metal objects and lie still. For inanimate objects, sample preparation of... 

Hoyer s medium is a useful mountant for both larval and adult cuticles. The medium rapidly digests soft tissues, leaving the cuticle cleared for observation. In addition, samples can be transferred directly from water to Hoyer s medium. However, specimens mounted in Hoyer s medium will degrade over time. For example, the fine denticles on the larval dorsum are best observed soon after mounting they begin to fade after 1 week, and they may disappear completely after several months. More robust features, such as the ventral denticle belts, will persist for a longer period of time. The preparation of Hoyer s medium is described in Protocol 36.1. 

Two new independently developed techniques called Dart ° (direct analysis in real time) and Desi (desorption electrospray ionisation) are making a huge impact on mass spectrometry. Together they remove the need for sample preparation and vacuum, speed up analysis time and can work in the open air. The sample is held in a gas or liquid stream at room temperature and the impact induces the surface desorption of ions. The ions then continue into the vacuum interface of the MS for analysis. Samples can be hard, soft or even liquid in nature. Ifa et al. have used Desi to image biological samples in two dimensions, recording images of tissue sections and the relative concentrations of molecules therein. Jeol have launched a commercial Dart ion source for non-contact analysis of materials in open air under ambient conditions. 

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