Tissue studies

One of the main uses of osmium tetroxide is as a biological staining agent for microscopic ceU and tissue studies. Osmium tetroxide is unique in that it both fixes and stains biological material. 

Figure 6.10b shows a pattern of antagonism often observed in isolated tissue studies but not so often in cell-based assays. Saturation of uptake systems for the agonist or saturation of an adsorption site for the agonist can account for this effect. The linear portion of the regression can be used to estimate the pKB or the pA2. If there is a loss of concentration dependence of antagonism, as seen in... 

Parathion is uniformly distributed throughout the body following acutely lethal doses, but there is no evidence of storage in any of the tissues studied even after long terms of feeding. 

The use of vesicle cell membranes, isolated cells, and cell monolayers and intestinal tissue studies has provided valuable correlations with in situ and in vivo drug absorption in animals as well as correlations with drug absorption in clinical studies. Most prominent among the literature sources establishing correlations between in vitro tissue and cellular systems with drug absorption in humans are the work of Dowty and Dietsch [73], Lennernas et al. [74], and Stewart et al. [75],... 

Studies using radioactivity-labeled acrylonitrile indicate that acrylonitrile or its metabolites form covalent adducts with cellular macromolecules in most tissues. Studies to develop chemical or immunological methods for measuring these adducts would be especially valuable in detecting and perhaps even quantifying human exposure to acrylonitrile. Adverse health effects demonstrated following exposure to acrylonitrile, particularly acute exposures, were characteristic of cyanide toxicity. Because these effects are also indicative of exposure to many other toxicants, additional methods are needed for more specific biomarkers of effects of acrylonitrile exposure. 

Hydrazide-based cyanine dyes are reactive with common formaldehyde fixatives for cell and tissue studies. This enables these dyes to function as general stains for protein-rich areas within cells, and they get crosslinked into place by the formaldehyde reaction process. 

Most interesting in this light are our initial experiments on mouse bladder showing the absolute dependence of [i adrenergic relaxation in the bladder to the presence of PLB. Isoproterenol or forskolin activation of the A -kinase pathway led to complete relaxation of bladder from wild type mice, with little or no response in the PLB knockout bladder (K. Nobe R. J. Paul, unpublished observations). On the other hand, relaxation via G -kinase pathway activation was identical in the PLB knockout and wild-type bladder. PLB modulation of SR appears to be the dominant pathway for A-kinase mediated relaxation in mouse bladder in contrast to its lesser role in this pathway for the vascular tissues studied. 

Modulation of the SR Ca2+ ATPase by PLB perhaps provides the clearest evidence of the significance of the SR to smooth muscle Ca2+ homeostasis and contractility. It also offers some cautions since the effects of modulation of SR function were clearly dependent on the smooth muscle tissue studied. In summary, genetically altered mouse models provide a new approach for assessing the physiological significance of the SR to smooth muscle function in vivo. 

More recent studies continue to support the unique antifibrillatory activity of bretylium. Kowey et al. [38] have shown that bretylium prevented spontaneous VF and decreased the effects on VF threshold in a feline myocardial infarction model. They attributed this beneficial effect to a decrease in the dispersion of refractoriness between normal and ischaemic regions of the heart. In contrast, clofilium (14, see below), which had little effect on dispersion of refractoriness after coronary occlusion, was unable to prevent spontaneous VF. Similar results were seen in isolated tissue studies with canine subendocardial Purkinje fibres and ventricular muscle which contained both normal and ischaemic regions [39]. In these studies bretylium caused a smaller increase in dispersion of refractoriness in subendocardial Purkinje fibres than either sotalol or clofilium. In ventricular muscle tissue, bretylium decreased dispersion while sotalol and clofilium increased dispersion of refractoriness. 

Many reports on the effects of ozone and PAN on physiologic processes (net photosynthesis, stomatal response, and water relations) and on metallic activity (including in vivo and in vitro studies of individual enzymes, enzyme systems, metabolic pathways, metabolic pool relationships, cell organelles, and plant tissue studies) have appeared since 1964. 

Laboratory evaluation [241] of acute and chronic toxicity of prenylamine indicates that, in high doses, convulsions accompanied by respiratory paralysis (often with pulmonary oedema) led to death. Doses inadequate to produce this result led only to phenomena characteristic of reserpine-like dmgs. Chronic administration failed to produce recognizable changes in any organs or tissues studied. No toxic effects, unattributable to amine depletion, have appeared during several years clinical use. 

Another problem with wintertime toxicity data is that toxin levels are reported per 100 gm of tissue. Studies of the deep sea scallop Placopecten magellanicus indicate that the size of the digestive gland can vary through the year (51). Thus a constant amount of toxin in a gland would look variable when normalized to 100 gm of tissue, with the highest relative toxicity during winter months when the tissues are the smallest. It would appear, however, that this error is small (perhaps 20-30%) relative to the 2 to 4-fold toxin increases typically reported between seasons in scallops (4, 47). 

Many tissue studies rely on animal models, rats and mice in particular, hence there have been several reports of HRMAS studies of animal tissues. As in human tissues, the primary goal has been to establish biochemical... 

Chronic exposures chronic exposure symptoms are similar to acute exposures with pulmonary lung function decrements depending on concentrations and duration of exposure. Asthma, allergies, other respiratory disorders have been observed. Breathing disorders, tumorgenic, direct and indirect genetic damage have been found in animal and/or human tissue studies. 

In contrast to y-glutamyl transpeptidase, which is almost entirely bound to particulates, y-glutamyl cyclotransferase is present in the supernatant fractions of liver and other tissues. Studies on the distribution of the enzyme shows that it is present in most animal tissues but that there are some species differences (Table IV). Relatively high enzymic activity is found in kidney, liver, brain, and skin. In man, the highest activity is found in the brain. The unusually high activity in... 

Martin, C. A., Salomoni, P. D., and Badran, A. F. 2001. Cytokeratin immunoreactivity in mouse tissues Study of different antibodies with a new detection system. Appl. Immunohlstochem. Mol. Morphol. 9 70-73. 

In the past decade Raman spectroscopy has assumed an important role in musculoskeletal tissue studies, especially in bone tissue studies. Applications to a wide range of problems in basic biology, biomechanics, and medicine have appeared in the journal literature. Most workers have used cell cultures or excised bone tissue, including human biopsy and cadaveric tissue. We expect that Raman spectroscopy will become increasingly important in such studies, as more life scientists and engineers learn how to employ it. Just as importantly, recent reports of non-invasive spectroscopy suggest that Raman spectroscopy may have a role in human subjects studies of bone development, function, and disease. 

In a preliminary Australian study, Taylor et al. (1999) found the levels of OCPs were higher in breast adipose tissue taken from women with breast cancer compared with women with benign breast conditions. DDE levels were significantly different between malignant and benign tissues. Studies of plasma levels of organochlorines and breast cancer risks have... 

Gustafsson J, Eriksson J, Marcus C. Glucose metabolism in human adipose tissue studied by 13C-glucose and microdialysis. Scandinavian Journal of Clinical and Laboratory Investigation 2007, 67, 155-164. 

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