Cell sample preparation standardization

Standardization of IHC/ICC has been a critical issue for more than three decades, especially with the advances in targeted therapy such as the development of trastuzumab (Herceptin) for advanced breast cancer.51 Nevertheless, standardization is a difficult issue because numerous factors may influence the consistency and reliability of immunostaining results, including fixatives, fixation time, AR, antibody clones, detection system, and interpretation (see Part II). In cytopathology, the situation is even worse due to its variable cell sample preparation techniques. Cytopreparation is. .. the foundation of cytomorphology. 52 We believe it is also the foundation of ICC. Therefore, standardization of ICC needs to start with uniform and reliable cytopreparation. 

EC is usually determined on solutions of salt in water. A soil sample is mixed with water until a paste, which is allowed to stand overnight, is obtained. The paste is then filtered and the EC of the solution measured. A conductivity cell for water is shown in Figure 9.6 (E). A sample is simply put in the cavity, or the cell is inserted into the extract, and a measurement made. Standardization is carried out by preparing standard solutions of salt, usually sodium chloride (NaCl), in distilled water. 

Although laser-ablation sample preparation and analysis are conducted with relative ease, quantification of data can prove challenging. With liquid samples, the amount of material introduced into the ICP-MS remains relatively constant, and instrument drift is usually corrected through the use of internal standards. However, in LA-ICP-MS, conditions such as the texture of the sample, ablation time, the location of the sample within the laser cell, surface topography, laser... 

Recording Absorptiometers. At least two types are available. In the first unit there are two test sample cells and one standard reference cell. Successive samples are metered alternately into the two test cells. While the cell containing one sample is being read and recorded, the other cell is being automatically rinsed in preparation for arrival of the succeeding sample. 

The quantification of metabolites in dried blood spots primarily ensures that the quality of the isotopes standards is excellent in terms of chemical and isotopic purity. When using MS/MS, it is essential that the fragments produced by the collision cell and the product ions detected ensure that both labeled and unlabeled metabolites are identical. Most importantly, the choice of the isotope label and the structural positions must be such that they are stable and do not exchange with other isotopes during sample preparation. Finally, it is imperative that the mass shift is sufficiently high (at least 3 Da) for small molecules less than 1000 Da and that the label occurs at a mass free from other compound interference. Figure 4 illustrates the concepts of quantification using stable isotope with Phe measurement in a dried blood spot as an example. 

Toraya s WPPD approach is quite similar to the Rietveld method it requires knowledge of the chemical composition of the individual phases (mass absorption coefficients of phases of the sample), and their unit cell parameters from indexing. The benefit of this method is that it does not require the structural model required by the Rietveld method. Furthermore, if the quality of the crystallographic structure is poor and contains disordered pharmaceutical or poorly refined solvent molecules, quantification by the WPPD approach will be unbiased by an inadequate structural model, in contrast to the Rietveld method. If an appropriate internal standard of known quantity is introduced to the sample, the method can be applied to determine the amorphous phase composition as well as the crystalline components.9 The Rietveld method uses structural-based parameters such as atomic coordinates and atomic site occupancies are required for the calculation of the structure factor, in addition to the parameters refined by the WPPD method of Toraya. The additional complexity of the Rietveld method affords a greater amount of information to be extracted from the data set, due to the increased number of refinable parameters. Furthermore, the method is commonly referred to as a standardless method, since the structural model serves the role of a standard crystalline phase. It is generally best to minimize the effect of preferred orientation through sample preparation. In certain instances models of its influence on the powder pattern can be used to improve the refinement.12... 

The Human Proteome Project (HUPO, www.hupo.org) initiated the Plasma Proteome Project (PPP) in 2002, and numerous laboratories have contributed to this ambitious project of deciphering all proteins contained in the human plasma. Plasma, the soluble component of the human blood, is believed to harbor thousands of distinct proteins that originate from a variety of cells and tissues through either active secretion or leakage from blood cells or tissues. For the reasons described above, HUPO recommends use of plasma instead of serum, with EDTA (or citrate) for anticoagulation and standardized sample preparation. HUPO proposes combinations of serum depletion, fractionation procedures, and MS/MS technologies, with explicit... 

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