Tissue preparations fractions

Research in this area advanced in the 1970 s as several groups reported the isolation of potent toxins from P. brevis cell cultures (2-7). To date, the structures of at least eight active neurotoxins have been elucidated (PbTx-1 through PbTx-8) (8). Early studies of toxic fractions indicated diverse pathophysiological effects in vivo as well as in a number of nerve and muscle tissue preparations (reviewed in 9-11). The site of action of two major brevetoxins, PbTx-2 and PbTx-3, has been shown to be the voltage-sensitive sodium channel (8,12). These compounds bind to a specific receptor site on the channel complex where they cause persistent activation, increased Na flux, and subsequent depolarization of excitable cells at resting... 

The pink azo dye formed is completely soluble in alcoholic borate solution the color was remarkably stable even up to 24 hours at room temperature. The method is so sensitive that a fraction of a microgram of phenol can be estimated with ease. It is very economical of enzyme, requiring only 0.1 ml of properly diluted serum or tissue preparations, and the tedious deproteinization step becomes unnecessary. 

Studies in vitro with rat kidney tissue preparations showed that estrogen sulfates inhibit kynurenine transaminase in a reversible fashion that can be relieved by dialysis (MIO, Mil). Competition of sulfate and phosphate esters of estrogens with PLP for the kynurenine transaminase apoenzyme has been demonstrated (S5). An estrogen effect on this enzyme in vivo was suggested by the finding of higher enzyme activity in the kidneys of adult male rats than in either females or estrogen-treated males (M9, Mil). This difference applied to renal kynurenine transaminase, two-thirds of which is in the soluble fraction and the... 

Vertebrate liver is a very rich source of enzymes that metabolize lipophilic xenobiotics, and subcellular fractions are prepared to study metabolism. Sometimes, other tissues such as brain, kidney, testis, and ovary are also treated in this way. A typical subcellular fractionation of liver might be as follows ... 

Most receptors (a notable exception being the steroid receptors that influence DNA transcription) are located on the cell surface, and purified cell membranes are thus an obvious choice of preparation. When a tissue is homogenized, however, any membrane fraction isolated may well contain membranes from intracellular organelles in addition to cell membranes from all the cell types present in the tissue. Thus, brain membranes will contain membranes not only from neurons but... 

Translation-competent ER membrane fractions can also be prepared from tissue culture cells. We recommend a terminally differentiated secretory suspension cell line, such as a plasmacytoma (e.g., J558L), which contains abundant levels of ER membrane. In this protocol, cells are collected by centrifugation (5 min, 500 x g) and resuspended in a homogenization buffer containing 10 mMKOAc, 10 mMK-HEPES, pH 7.5, 1.5 mMMg(OAc)2,... 

Each specimen was dehydrated, infiltrated and embedded in Technovit based methylmethacrylate. One section was cut and around in preparation for scanning electron microscopy (SEM). In each case, three overview photos were necessary and four high magnification fields (40X) were photographed and digitized. These fields were later analyzed for volume fraction of soft tissue, bone... 

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