Tissue fractionation

The apparent volume of distribution (Vd) slightly increases depending on plasma volume (Fp), tissue volume (Ft), and free tissue fraction (ft) whereas the half-life slightly decreases with significantly increasing free plasma fraction. 

The volume will decrease when renal impairment is associated with a decrease in the elimination rate beta (betaNorm => betaFail). On the other side, the volume will increase when the free plasma fraction (fp) increases in renal impairment where jp = 1 - PB%. The volume decreases, when the free tissue fraction (ft) increases in renal impairment. 

Hohson, K.A. and Clark, R.G. 1992 Assessing avian diets using stable isotopes 11 factors influencing diet-tissue fractionation. The Condor 94 181-188. 

Bartsch, H., Camus, A.-M. and Malaveille, C. (1976). Comparative mutagenicity of N-nitrosamines in a semi-solid and in a liquid incubation system in the presence of rat or human tissue fractions. Mutation Res. 37 149-162. 

Treatment with hot organic solvents was the next step in the tissue fractionation, to remove lipid-phosphorous and breakdown lipid-protein interactions. In the Schneider procedure, nucleic acids were then extracted in hot dilute trichloroacetic or perchloric acid, leaving a protein residue with any phosphoprotein links still intact. This method was to become particularly useful when 3H thymidine became the preferred label for DNA in the early 1960s. For investigations where both RNA and DNA were to be examined the Schmidt-Thannhauser process was often chosen. Here the lipid-extracted material was hydrolyzed with dilute sodium hydroxide releasing RNA nucleotides and any hydroxyamino acid bound phosphorus. DNA could be precipitated from the extract but the presence in the alkaline hydrolysate of the highly labeled phosphate released from phosphoprotein complicated... 

It is well known that the structure, distribution and properties of protolignin in cell walls vary according to cell type and morphological location. This is based upon extensive studies on topochemical properties of lignin using various methods such as ultraviolet microscopic photometry (1,2), bromination-SEM-EDXA (3) and other physical or chemical analyses of isolated tissue fractions (4). 

In most instances the specimens will be self-evident (e.g., samples of blood, plasma, serum, urine, spinal fluid, aqueous humor, organs, tissues, and tissue fractions that are taken from a test system with the intention of performing an examination or analysis). In other instances the definition may not be as clear. For example, the assay plates used in the mammalian cell transformation assay and the mammalian point mutation assay are considered specimens even though they bear many of the attributes of a test system. For these assays, the originally plated cells plus media and excipients are the test system. After treatment with the test or... 

Tissue lysate (or homogenates), post-mitochondrial supernatants and microsomes offer several practical advantages for the study of xenobiotic metabolism. The principal advantages are that the human tissues provide a complete system containing all the enzymes in ratios found in vivo, and tissue fractions are stable in relatively long-term storage. Within the different types of tissue fractions, microsomes provide an enrichment of the membrane-bound enzymes, and post-mitochondrial supernatants provide a means to study both membrane-bound and soluble enzymes. Tissue fractions are easily prepared from a variety of tissues including human liver and can be cryopreserved for several years. This allows detailed characterization of the tissue prior to use with xenobiotics of unknown routes of metabolism... 

Cell or tissue lysates represent the crudest tissue fraction. Use of lysates is practical when the level of enzyme is relatively high. However, lysates have a tendency to form aggregates, which limits the maximum protein concentration which can be used and also limits the time for which the reaction to be studied is linear. Typically, protein concentrations of less than 3 mg/ml must be used and incubation time is limited to about 30 min. This can be an important limitation for substrates which are metabolized very slowly. In addition, cell fractionation is not limited to primary tissues. Fractions can be prepared from cDNA-expressing cell lines. This can provide a level of convenience to the researcher relative to the demands of maintaining multiple cell lines for extended periods of time. 

Generation of potential human metabolites for structural identification prior to administration of the drug candidate to humans can be performed with either cDNA-expressed enzymes or tissue fractions. This allows identification of potential human metabolites and development of appropriate analytical methods prior to clinical trials. Generation and identification of pharmacologically active human metabolites early in the development process can be beneficial for obtaining appropriate patent protection. 

In vitro. The activity or absolute level of enzymes such as cytochrome P-450 and glucuronosyl transferase can be measured in cells, tissue fractions, or subcellular fractions (e.g., microsomes) and compared with those from control animals. The activity is measured by using a particular substrate for each of the isoforms of the enzyme (e.g., cytochrome P-450 or UDPGT) of interest. The total level of cytochrome P-450 could be determined by spectrophotometry using standard methods (e.g., carbon monoxide binding and difference spectra). Alternatively, the level of protein can be determined by gel electrophoresis and Western blotting, and this would allow the separation of different isoforms. 

Murphy, M.E. and Kehrer, J.P. 1987. Simultaneous measurment of tocopherols and tocopheryl quinines in tissue fractions using high-performance liquid chromatography with redox-cycling electrochemical detection../. Chromatogr. 421 71-82. 

Tissue fraction Glucose-6-P phospho- hydrolase Inorganic pyrophosphatase PPi-glucose phosphotrans- ferase CDP-glucose phospho- transferase... 

Tissue fraction Inorganic pyrophosphatase (%) PPi-glucose phosphotransferase (%) Glucose-6-P phosphohydrolase (%)... 

Inductively coupled plasma-mass spectrometry (ICP-MS) is a powerful technique that uses an inductively coupled plasma as an ion source and a mass spectrometer as an ion analyzer. It can measure the presence of more than 75 elements in a single scan, and can achieve detection limits down to parts per trillion (ppt) levels for many elements—levels that are two or three orders of magnitude lower than those obtained by ICP-AES (Keeler 1991). It is more expensive than ICP-AES and requires more highly skilled technical operation. Aluminum levels in urine and saliva were detected down to 0.02 g/mL and in blood serum to 0.001 g/mL using ICP-MS (Ward 1989). Speciation studies have employed ICP-MS as a detector for aluminum in tissue fractions separated by size-exclusion chromatography (SEC) with detection limits of 0.04 g/g in femur, kidney and brain (Owen et al. 1994). 

The first argument was supplied by Post and Vincent (4o) in their study of the incorporation of radiolabeled glucose in tissue fractions of normal... 

Table 7. Incorporation of radioactivity from (6- C)-D-glucose in tissue fractions of normal and Du 19111-treated Pieris larvae, expressed as jxg glucose, with standard deviations (40).

Protein expression of dysbindin-1 is also ubiquitous in the body and is detectable in cell bodies of virtually all neuronal populations. Levels of somatal protein are variable, however, with the highest levels found in areas listed above where gene expression is highest. High levels of dysbindin-1 protein expression are also seen in certain synaptic fields. Where these have been examined with immunoEM, dysbindin-1 has been found mainly along microtubules of dendrites and axons, in PSDs of dendritic spines, and around synaptic vesicles. Tissue fractionation of whole brain tissue reveals that dysbindin-1 A is most highly concentrated in PSD fractions, dysbindin -IB in synaptic vesicle fractions, and dysbindin-1C in both PSD and synaptic vesicle fractions. 

Westermark U, Lidbrandt O, Eriksson I (1988) Lignin distribution in spruce (Picea abies) determined by mercurization with SEM-EDXA technique. Wood Sci Technol 22 243-250 Whiting P, Goring DAI (1982) Chemical characterization of tissue fractions from the middle lamella and secondary wall of black spruce tracheids. Wood Sci Technol 16 261-267 Wood JR, Goring DAI (1971) The distribution of lignin in stem wood and branch wood of Douglas-fir. Pulp Pap Mag Can 72 T95-T102... 

TBA reactivity is thus a reflection of the total amount of MDA, / -unsaturated aldehydes, cyclic peroxides and contaminants present in the sample and in the basic form, the reaction is clearly not specific for any one class of peroxidation product (Kosugi and Kugawa, 1986). However, as a first approximation, measurement of tissue fraction oxidation it can be a useful method because it is quick and easy. Great care must be exercised in the interpretation of the results. 

The activity of the GST-peroxidase (Type 2) is difficult to measure directly and individually, since the observed activity in tissue fractions will be the sum of the glutathione peroxidase and GST activities. In practice, therefore, the GST-peroxidase activity may be obtained by... 

It is often desirable, in order to obtain a picture of the entire GST activity of a tissue or tissue fraction, to measure the enzyme with several different substrates this can conveniently be done by a modification of the spectrophotometric method of Habig and Jakoby (1981). 

Sterner, T.R., Ruark, C.D., Robinson, P.J. (2008). Predicting nerve agent tissue blood partition coefficients using algorithms accovmting for accessible tissue fraction. Toxicol. Sci. 102 (Suppl. 1) 205. 

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