Fresh tissue

An intriguing environmental feature of an Eca invasion in potatoes is the change from pH 5.0 in fresh tissue to pH 8.5 in the infected tissue after 72 h. We propose that the involvement of PLs in the degradation of pectin is an evolutionary consequence of the alkalinization which inactivates PG [optimal activity for Eca PG is at pH 6.0 (unpublished results)]. Moreover, secretion of PL isoenzymes may ensure successful biological activity of Eca in diverse types of host cell walls. 

As a gold standard, fresh tissue prepared by snap-frozen method, cut by cryostat, and fixed in acetone, ethanol, or other non-cross-linking fixatives, has been generally accepted as reliable. 

First step DNA extracted from FFPE tissue by heating showed the best score (better than fresh tissue section) ... 

Figure 3.3 Comparison of array CGH among DNA extracted from fresh tissue, FFPE tissue by heating protocol or nonheating protocol for two human tissue samples of metastatic carcinoma in lymph node (a-c), and undifferentiated non-small cell carcinoma (d-f). Array CGH hybridization genomic profiles show ratio values representing relative copy number of single BACs. A good result is scored as 1.0 that indicates a low standard deviation for gains (>0.2), normal (0.0), or losses (<-0.2). In these two cases, fresh samples show best score as 2, both FFPE tissue samples show identical score of 3. Each spot represents the average of three replicates. Clones are ordered by chromosomal position as numbers at the bottom (x axis) of each picture. The y axis is the log2 ratio of test reference intensity. Provided by Sandy DeVries from Dr. Frederic Waldman s Lab at UCSF.

This hypothesis may also be presented mathematically the protein amount in a fresh ccll/tissuc expressed as Pf produces an IHC signal in fresh tissue of I (Pf). When the identical IHC staining plus AR treatment is applied to FFPE tissue section, the IHC signal is J (Pffpe). The degree of retrieval after AR (R%) is calculated as R% = J (Pffpe)/J (Pf) x 100%. The amount of protein in the FFPE tissue may then be derived as follows Pffpe = Pf x R%. In a situation where optimized AR is 100% effective, then the IHC signal would be of equal strength in fresh tissue and FFPE tissue, and Pffpe = Pf. 

Reference FFPE FPPE Tissue Fresh Tissue FFPE Tissue ... 

As has been explained in previous chapters, the antioxidant capacity of fruits and vegetables is a function of the amounts and types of phytochemicals that are present in the fresh tissues. However, the individual contribution to the total antioxidant capacity varies widely. Various studies have demonstrated that phenols and flavonoids contribute to a higher extent than ascorbic acid, carotenoids, and others to the antioxidant capacity of fmits and vegetables (Robles-Sanchez and others 2007). It has been observed that a given content of vitamin E in fruits contributes significantly more to the antioxidant capacity than the same content of ascorbic acid. 

Abnormalities of the respiratoiy chain. These are increasingly identified as the hallmark of mitochondrial diseases or mitochondrial encephalomyopathies [13]. They can be identified on the basis of polarographic studies showing differential impairment in the ability of isolated intact mitochondria to use different substrates. For example, defective respiration with NAD-dependent substrates, such as pyruvate and malate, but normal respiration with FAD-dependent substrates, such as succinate, suggests an isolated defect of complex I (Fig. 42-3). However, defective respiration with both types of substrates in the presence of normal cytochrome c oxidase activity, also termed complex IV, localizes the lesions to complex III (Fig. 42-3). Because frozen muscle is much more commonly available than fresh tissue, electron transport is usually measured through discrete portions of the respiratory chain. Thus, isolated defects of NADH-cytochrome c reductase, or NADH-coenzyme Q (CoQ) reductase suggest a problem within complex I, while a simultaneous defect of NADH and succinate-cytochrome c reductase activities points to a biochemical error in complex III (Fig. 42-3). Isolated defects of complex III can be confirmed by measuring reduced CoQ-cytochrome c reductase activity. 

A minimum of 50% of fetuses are to be examined for visceral alterations and a minimum of 50% for skeletal abnormalities. When a fresh tissue microdissection technique is being used for the visceral examination of rabbit fetuses, all fetuses should be examined for both visceral and skeletal abnormalities. 

The two remaining of plant water status parameters (water and osmotic potential) reflect free water availability. These can be measured with a Dew Point Microvoltmeter (e.g., the WESCOR HR 33T [Logan, Utah]), but other methods and equipment can be applied. Osmotic potential can be determined from either fresh or frozen plant samples, but water potential requires fresh tissue. The water potential of leaf discs, strips or roots of the same size/weight can be measured with the WESCOR device (for detailed methods see http //www.wescor.com/environmental/index.phtml). Osmotic... 

Perfusion of brain tissue is not as easy to perform as immediate freezing following removal of fresh tissue from the animal. The former technique has long been preferred for immunohistochemistry, but it has been argued that fresh-frozen sections are better for analysis of mRNA distribution and can be adapted for immunohistochemical analysis (Newton et al., 2002). 

Taurine is a sulphur amino acid, which is not present in protein (see text). For the calculation from the amount in fresh (wet) tissue, e.g. pmol/g fresh tissue, it is assumed that the intracellular water makes up 40% of the weight. 

A recent area of major concern has been the development of a practical and specific assay for the detection of ciguatoxin directly from fish tissues. Earlier assays, some of which are still used, relied on whole tissues, crude extracts and partially purified ciguatoxin (8, 9, 20). For the mongoose and cat assays, large amounts (10-15% of body weight) of fresh tissues were required, while the mouse assay required concentrated lipid extracts of the fish tissue. 

Hepatocytes Culture methods available Full enzyme complement - contain enzymes and enzyme cofactors not present in subcellular fractions Full enzyme complement - contain enzymes and enzyme cofactors not present in subcellular fractions Can be used quantitatively Useful for prediction of Phase 1 and 11 metabolism Require fresh tissue No cell-cell contact Need collagenase digestion Handling difficult Closed system so may not be representative of in vivo situation... 

Liver slices Easy to prepare Cell-cell contact No use of proteolytic enzymes All cell types present Phase 1 and 11 metabolic processes accessible Require fresh tissue Necrosis of slice centre Long-term culture difficult Quantitative studies variable... 

Visualization of the fresh tissues under the microscope can be made difficult due to the shiny wet surfaces. Photography is also difficult one solution is to completely immerse the whole... 

Figure 7.12 PME activity retention (%) in relation to fresh tissue activity. Squares ( ) represent percentages calculated with PME activity values determined after the first blanching step (PMEi ). Triangles (A) represent percentages calculated with PME activity values determined after freezing (PME2).

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