Fixation procedures technique

The methanol/acetic acid fixation techniques described above preserve chromosome morphology very well, but they remove a substantial fraction of chromosomal proteins. Thus, preparations obtained by these techniques are not suitable for immunolocalization of proteinaceous components of metaphase chromosomes. We have therefore developed a series of fixation procedures that result in good chromosomal quality with minimal removal of proteins. We stress here that different fixation protocols result in differential extraction of chromosomal proteins. Thus, for each protein under study, develop a fixation procedure that minimizes its removal from the chromosomes. In addition, we have... 

Postmortem measurements in laboratory animals supply information about regional or local deposition patterns in the lungs at better spatial resolution than noninvasive techniques can provide. Most frequently, radioactively labeled particles are applied, but magnetically labeled particles, microspheres, or fluorescent particles have also been used to quantify deposition throughout the lung on a macroscopic or microscopic level (79). Most of the invasive techniques require special lung fixation procedures before retention analysis to avoid translocation or particle loss during the fixation procedure (11,74). Rapid microwave fixation (80-82), intravascular perfusion techniques (74,83), and cryofixation (84) have been applied (see also Chap. 6). 

Finally, the localizations of low-molecular-weight compounds requires special specimen preparation techniques, as these compounds are often diffusible, water- or organic-solvent soluble, and solubilized by conventional fixation and dehydration procedures. The reader is referred to ref. (12) for the processing of cells and tissues for the cytochemical and histochemical localization of these compounds. 

The poor resolution of the fine structures of DNA and nucleosomes by conventional SEM was solved by the development of an ultrahigh-resolution SEM (14-15). Inaga et al. (16) observed the DNA double helix and nucleosomes of chicken erythrocytes by using an ultrahigh-resolution SEM. They modified the microspreading technique of Seki et al. (17) and combined it with the carbon plate method devised by Tanaka et al. (18). Briefly, they (procedures were performed at 0-4°C before fixation with the formalin solution) ... 

The localization of proteins and carbohydrates within cells and tissues with specific antibodies has long been proven to be a valuable technique. Immuno-localization procedures allow one to detect not only well-characterized cellular structures but also provide information about newly characterized proteins and carbohydrates. This chapter will review some of the advantages and drawbacks of common chemical fixation and permeabilization methods used for immuno-localization at the level of light microscopy. 

The most convenient and most popular analytical methodology to assess enantiomer purity is the direct separation of enantiomers on so-called chiral stationary phases (CSPs). CSPs consist of an (ideally) inert chromatographic support matrix incorporating chemically or physically immobilized SO species. CSPs may be created by a variety of SO immobilization techniques, including (i) covalent attachment onto fhe surface of suitably pre-functionalized carrier materials, (ii) physical fixation employing coating techniques, and (iii) incorporation into polymeric networks by copolymerization, or combinations of these procedures. 

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