Phosphatase, effects

Jemmerson, R., and Agre, M. (1987) Monoclonal antibodies to different epitopes on a cellsurface enzyme, human placental alkaline phosphatase, effect different patterns of labeling with protein A-colloidal gold. J. Histochem. Cytochem. 35, 1277-1284. 

Runnegar, M.T., Bemdt, N., Kaplowitz, N. (1995). Microcystin uptake and inhibition of protein phosphatases effects of chemoprotectants and self-inhibition in relation to known hepatic transporters. Toxicol. Appl. Pharmacol. 134 264-72. 

Duda RJ )r, O Brien JF, Katzman JA, Peterson JM, Mann KG, Riggs BL. Concurrent assays of circulating bone gla-protein and bone alkaline phosphatase effects of sex, age, and metabolic bone disease. J Clin Endocrinol Metab 1988 66 951-7. 

N7. Nath, R. L., and Ghosh, N. K., Studies on serum phosphatases Effect of dilution on acid and alkaline phosphatases of human serum. Enzymologia 26, 182-195 (1963). 

Hoar PE, Pato MD, Kerrick WG (1985) Myosin light chain phosphatase. Effect on the activation and relaxation of gizzard smooth muscle skinned fibers. J Biol Chem 260 8760-4876... 

Craig D B, Arriaga E A, Wong J C Y, Lu H and Dovichi N J 1996 Studies on single alkaline phosphatase molecules reaction rate and activation energy of a reaction catalyzed by a single molecule and the effect of thermal denaturation—the death of an enzyme J. Am. Chem. See. 118 5245-53... 

Phosphorothioates generally protect normal tissues more than tumors. Tumor protection reported in some animal studies can pardy be explained by physiological effects of the particular dmgs, which are specific to rodents (4). WR-2721 does not appear to protect human and most animal tumors, apparentiy because of the low availabiUty of the dmg to tumor cells (4). Many tumors appear to have a reduced capillary density (44), which may mean that these tumors have altered levels of alkaline phosphatase, the enzyme that converts WR-2721 to WR-1065. A reduced abiUty of thiols to protect the hypoxic cells characteristic of many tumors may also contribute to their selectivity for normal tissues. The observation that WR-1065 protects cultured normal human fibroblasts, but not fibrosarcoma tumor cells, suggests that additional factors may contribute to the selectivity of radioprotection by WR-2721 m vivo (18). 

Aplastic anemia and leukemia are not the only health effects ascribed to benzene exposure. A number of recent studies have associated benzene exposure with chromosomal changes (aberrations) (118). Other studies have shown abnormalities in porphyrin metabolism and decrease in leucocyte alkaline phosphatase activity in apparendy healthy workers exposed to 10—20 ppm benzene (119,120). Increases in leukoagglutinins, as well as increases in blood fibrinolytic activity, have also been reported and are believed to be responsible for the persistent hemorrhages in chronic benzene poisoning (121,122). 

The ability to identify and quantify cyanobacterial toxins in animal and human clinical material following (suspected) intoxications or illnesses associated with contact with toxic cyanobacteria is an increasing requirement. The recoveries of anatoxin-a from animal stomach material and of microcystins from sheep rumen contents are relatively straightforward. However, the recovery of microcystin from liver and tissue samples cannot be expected to be complete without the application of proteolytic digestion and extraction procedures. This is likely because microcystins bind covalently to a cysteine residue in protein phosphatase. Unless an effective procedure is applied for the extraction of covalently bound microcystins (and nodiilarins), then a negative result in analysis cannot be taken to indicate the absence of toxins in clinical specimens. Furthermore, any positive result may be an underestimate of the true amount of microcystin in the material and would only represent free toxin, not bound to the protein phosphatases. Optimized procedures for the extraction of bound microcystins and nodiilarins from organ and tissue samples are needed. 

Antithyroid drags have several side effects. The most frequent side effects are maculopapular rashes, pruritus, urticaria, fever, arthralgia and swelling of the joints. They occur in 1-5% of patients [1, 2]. Loss of scalp hair, gastrointestinal problems, elevations of bone isoenzyme of alkaline phosphatase and abnormalities of taste and smell are less common. The incidence of all these untoward reactions is similar with MMI and PTU. Side effects of MMI are dose-related, whereas those of PTU are less clearly related to dose [1]. PTU may cause slight transient increases of serum aminotransferase and y-glutamyl transpeptidase concentrations but also severe hq atotoxicity whereas methimazole or carbimazole can be associated with cholestasis. The side... 

The possibility that acute ethanol directly activates PKC would seem to be ruled out by the lack of such effect occurring in various in vitro systems that have been studied. One possibility is the activation of a phosphatase, others are the modulation of the availability and type of activator. It is also possible that ethanol could modify the sensitivity of the ion channel to the effect of PKC phosphorylation or its proteolytic downregulation. 

Vanadate (sodium orthovanadate or peroxovanadate) exhibits insulin-like effects in vitro (activation of insulin receptor tyrosine kinase, PI 3-kinase, Akt) and in vivo (diabetic rats, humans). These effects can be explained at least in part by the inhibition of phosphotyrosine phosphatases which deactivate the INSR tyrosine kinase. 

Hydrogen peroxide (H202) exhibits insulin-like activity in isolated cells. Like that of vanadate, this effect is thought to be mediated by inhibition of protein-tyrosine phosphatases. 

PTEN is a phosphatase, which is a product of a tumor suppressor gene. This phosphatase has an unusual broad specificity and can remove phosphate groups attached to serine, threonine, and tyrosine residues. It is believed that its ability to dephosphorylate phosphati-dylinositol (PI) 3,4,5-triphosphate, the product of PI-3 kinase, is responsible for its tumor suppressor effects. 

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