Homeostasis, disturbances

Several studies investigated the possible role of calcium homeostasis disturbances in OPIDP pathogenesis, but results were inconsistent across various OPs and species (Suwita et al, 1986 El-Fawal et al, 1989 Luttrell et al., 1993 Barber et al, 2001 Piao el al, 2003 Wu et al, 2003 Choudhary and Gill, 2001),... 

Many types of liver injury are caused by a number of biochemical reactions of toxicants or their active metabolites. Such reactions inclnde covalent binding, lipid peroxidation, inhibition of protein synthesis, pertnrbation of calcium homeostasis, disturbance of biliary prodnction, and a variety of immunologic reactions. The types of liver injury from such biochemical reactions include steatosis (fatty liver), liver necrosis, cirrhosis, cholestasis, hepatitis, and carcinogenesis. The toxicants that cause these injuries are discussed in brief. 

Hernias 114, 377, 384-392, 403, 642 Hips, dislocation 114 Hirschsprung disease 583 Hirsutism 438, 560561 Hoarseness 441, 443 Holoprosencephaly 583 Homeostasis, disturbed energy 332 Humeri, disproportionately affecting 495... 

There is evidence for immunosuppressive effects of PAHs in rodents (Davila et al. 1997). For example, strong immunosuppressive effects were reported in mice that had been dosed with benzo[fl]pyrene and 3-methyl cholanthrene, effects that persisted for up to 18 months (Environmental Health Criteria 202). Multiple immu-notoxic effects have been reported in rodents, and there is evidence that these result from disturbance of calcium homeostasis (Davila et al. 1997). PAHs can activate protein tyrosine kinases in T cells that initiate the activation of a form of phospholipase C. Consequently, release of inositol triphosphate—a molecule that immobilizes Ca + from storage pools in the endoplasmic reticulum—is enhanced. 

The above studies have generated a huge body of invaluable data concerning the effects of oxidative stress on cells. In particular the importance of GSH in cell protection and the role of disturbed calcium homeostasis in cell killing have been greatly illuminated. 

O Signs and symptoms of adrenal insufficiency reflect the disturbance of normal physiologic carbohydrate, fat, and protein homeostasis caused by inadequate cortisol production and inadequate cortisol action. 

More than a century ago Claude Bernard speculated that the milieu interne must be maintained to preserve life (B17). Later, Walter Cannon indicated that physical disturbances could elicit a coordinative response of the organism to keep homeostasis (C7). The stress concept of Hans Selye noted that these stimuli that disturbed the physical integrity of the organism resulted in a general adaptation... 

Potential PCL applications in medicine (these investigations are in progress) include characterization of disturbances in antioxidative homeostasis, in the following areas ... 

Acid-base disorders are caused by disturbances in hydrogen ion (H+) homeostasis, which is ordinarily maintained by extracellular buffering, renal regulation of hydrogen ion and bicarbonate, and ventilatory regulation of carbon dioxide (C02) elimination. 

Jewell, S.A., Bellomo, G., Thor, H., Orrenius, S. and Smith, M.T. (1982). Bleb formation in hepatocytes during drug metabolism is caused by disturbances in thiol and calcium ion homeostasis. Science 217 1257-1258. 

Other Factors. ECT no doubt destroys the homeostasis of the cancerous cells by profoundly disturbing their microenvironment and by dismantling their structure. It might also lead to the inhibition of their DNA synthesis. It has been speculated that ECT might release the Tumor Necrosis Factor (TNF) or, somehow super-activate the immune system at the tumor site. 

The prototype of a small pore-forming toxin is the S. aureus a-toxin, also called ct-hemolysin, that has been extensively investigated hy Bhakdi and coworkers. Monomers of ct-hemolysin (33 kDa) hind to the surface of erythrocytes, and after lateral diffusion within the lipid hilayer, seven monomers oligomerize to form pores in the cell membrane. The ct-hemolysin forms mushroom-shaped pores with an outer diameter of lOnm and an inner diameter of approximately 2.5 nm. Small molecules can pass through the pore and diffuse into/out of the cytosol, along with water. As a consequence of such movement, cell homeostasis is greatly disturbed and pushed into an unhealthy state. In animals, the a-hemolysin represents a major virulence factor of S. aureus which causes hemolysis as well as tissue destruction. ... 

Rabotnov (32) considers that allelopathy contributes to maintaining homeostasis in natural plant communities. Economically important losses may occur when the ecological balance in such communities is disturbed. For example. Booth and Barker ( ) recorded lost grazing capacity due to invasion of pastoral lands by shrub species such as... 

Calcium and phosphate, the major mineral constituents of bone, are also two of the most important minerals for general cellular function. Accordingly, the body has evolved a complex set of mechanisms by which calcium and phosphate homeostasis are carefully maintained (Figure 42-1). Approximately 98% of the 1-2 kg of calcium and 85% of the 1 kg of phosphorus in the human adult are found in bone, the principal reservoir for these minerals. These functions are dynamic, with constant remodeling of bone and ready exchange of bone mineral with that in the extracellular fluid. Bone also serves as the principal structural support for the body and provides the space for hematopoiesis. Thus, abnormalities in bone mineral homeostasis can lead not only to a wide variety of cellular dysfunctions (eg, tetany, coma, muscle weakness) but also to disturbances in structural support of the body (eg, osteoporosis with fractures) and loss of hematopoietic capacity (eg, infantile osteopetrosis). 

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