Kidney cells, alkaline phosphatase

Ketimine 121,744s. See also Schiff base from pyridoxal phosphate 742 as electron acceptor 746, 747 a-Ketoacid. See 2-Oxoacid Ketoamine 434s Ketodeoxyoctonate. See KDO Ketone(s), acidity of 46 Khorana, H. Gobind 84 Kidney cells, alkaline phosphatase in 645... 

Studer M, Terao M, Gianni M et al (1991) Characterization of a second promoter for the mouse liver/bone/kidney-type alkaline phosphatase gene cell and tissue specific expression. Biochem Biophys Res Commim 179 1352-1360... 

The alkaline phosphatases are found in bacteria, fungi, and higher animals but not in higher plants. In E. coli alkaline phosphatase is concentrated in the peri-plasmic space. In animals it is found in the brush border of kidney cells, in cells of the intestinal mucosa, and in the osteocytes and osteoblasts of bone. It is almost absent from red blood cells, muscle, and other tissues which are not involved extensively in transport of nutrients. 

Regulation of alkaline phosphatase activity was discussed by Cox and Griffin 65). Steroids such as hydrocortisone or prednisolone (1 (ig/ml of medium) can induce a 3- to 20-fold rise in certain HeLa cell cultures, while other cell lines are induced by 15 mM phenyl phosphate. Recently, it has been shown that fibroblast cell cultures are also stimulated by prednisolone (( ( ). According to one report, Pi may have a control function here a decrease in the level of rat kidney P produced by a low phosphate diet was accompanied by an increase in alkaline phosphatase. Nine other enzymes monitored were unaffected 67). 

A less common circumstance leading to hypercalcemia is development of a form of osteomalacia characterized by a profound decrease in bone cell activity and loss of the calcium buffering action of bone. In the absence of kidney function, any calcium absorbed from the intestine accumulates in the blood. Therefore, such patients are very sensitive to the hypercalcemic action of l,25(OH)2D. These individuals generally have a high serum calcium but nearly normal alkaline phosphatase and PTH levels. The bone in such patients generally has a high aluminum content, especially in the mineralization front, which may block normal bone mineralization. These patients do not respond favorably to parathyroidectomy. Deferoxamine, an agent used to chelate iron (see Chapter 58 ... 

AP had not been used extensively in immunohistochemistry until publication of the unlabeled alkaline phosphatase-antialkaline phosphatase (APAAP) procedure (2, 3). The soluble immune complexes utilized in this procedure have molecular weights of approximately 560 kDa. The major advantage of the APAAP procedure compared to the earlier peroxidase techniques was the lack of interference posed by endogenous peroxidase activity. Because of the potential distraction of endogenous peroxidase activity, the alkaline phosphatase techniques were particularly recommended for use on blood and bone marrow smears. Endogenous alkaline phosphatase activity from bone, kidney, liver and some white cells can be inhibited by the addition of 1 mM levamisole to the substrate solution (4), although 5 mM has been found to be more effective (5). Intestinal alkaline phosphatases are not adequately inhibited by levamisole. 

Indicates endogenous alkaline phosphatase activity in the tissue sections. It is present in liver, kidney, Gl tract, bone, bladder, ovary, salivary gland, placenta, leukemic, necrotic or degenerated cells. 

GGT does not nsnally form part of the standard LFTs in most laboratories. It is an enzyme fonnd in hepatocytes and biliary epithelial cells, and also in kidney, pancreas, intestine and prostate. It has a higher sensitivity for indicating a problem of liver origin than alkaline phosphatase, but tends to follow a similar pattern. It is released in all types of liver dysfunction and therefore cannot generally be used to differentiate between types. However, a raised GGT with an isolated raised alkaline phosphatase can be suggestive of cholestasis. GGT levels can be ten to 20 times normal in cholestatic disease. 

Intestinal alkaline phosphatase and human tissue non-specific alkaline phosphatase are two urinary isoenzymes that have ehcited interest as potential segment specific markers of the human nephron [190]. Both are members of the closely related group of alkaline phosphatases. Intestinal alkaline phosphatase is the intestinal isoenzyme that is locahzed on the brush border of human intestinal epithelial cells. It is also present in normal human kidney, where it is exclusively expressed on the brush border of tubulo-epithelial cells of the S3-segment of the proximal tubule. The intestinal alkaline phosphatase, which is released in urine, has its origin in the kidney. As a result, intestinal alkaline... 

Measurement of serum y-GT activity has clinical significance. The enzyme is present in all tissues, but the highest level is in the kidney however, the serum enzyme originates primarily from the hepatobiliary system. Elevated levels of serum y-GT are found in the following disorders intra- and posthepatic biliary obstruction (elevated serum y-GT indicates cholestasis, as do leucine aminopeptidase, 5 -nucleotidase, and alkaline phosphatase) primary or disseminated neoplasms some pancreatic cancers, especially when associated with hepatobiliary obstruction alcohol-induced liver disease (serum y-GT may be exquisitely sensitive to alcohol-induced liver injury) and some prostatic carcinomas (serum from normal males has 50% higher activity than that of females). Increased activity is also found in patients receiving phenobarbital or phenytoin, possibly due to induction of y-GT in liver cells by these drugs. 

Fig. 31. (A) Rat duodenum stained for alkaline phosphatase with azo dye method (B5a). Semidense particles of azo dye are deposited in the plasma membranes of the microvilli X70,000. (B) Placental labyrinth cell reacted for alkaline phosphatase with the cadmium method (M22). Deposits are related only to the cell surface X56,000. (C) Brush border of proximal tubule cell of the kidney showing deposits of final product related to the surface of the microvilli. Cadmium method of Mizutani and Barrnett (M22) X 35,000. Electron micrographs, courtesy of R. J. Barrnett.

Often there is no good clinical test available to determine the exact type of hepatic lesion, short of liver biopsy. There are certain patterns of enzyme elevation that have been identified and can be helpful (Table 38-3). ° The specificity of any serum enzyme depends on the distribution of that enzyme in the body. Alkaline phosphatase is found in the bile duct epithelium, bone, and intestinal and kidney cells. 5-Nucleotidase is more specific for hepatic disease than alkaline phosphatase, because most of the body s store of 5 -nucleotidase is in the liver. Glutamate dehydrogenase is a good indicator of centrolobular necrosis because it is found primarily in centrolobular mitochondria. Most hepatic cells have extremely high concentrations of transaminases. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are commonly measured. Because of their high concentrations and easy liberation from the hepato-cyte cytoplasm, AST and ALT are very sensitive indicators of necrotic lesions within the liver. After an acute hepatic lesion is established, it may take weeks for these concentrations to return to normal. ... 

The nephrotoxicity of 16 continues to generate considerable interest. Orellanine was highly toxic to mice (LD50 = 12.5 mg/kg i.p.)[101] and caused interstitial nephritis and tubular necrosis in mouse kidney [102], A summary of 16-induced changes in renal function and morphology has been reported [103]. In LLC-PKi renal epithelial cell cultures, 16 decreased the activity of alkaline phosphatase and lactate dehydrogenase, and decreased the incorporation of H-leucine and H-thymidine [104]. Orellanine was a noncompetitive inhibitor of renal alkaline phosphatase, but a competitive inhibitor of the intestinal and placental enzymes [105]. In canine kidney MDCK cell cultures, 16, or a metabolite of 16, inhibited protein, RNA and DNA synthesis [106]. 

The apical plasma membrane of epithelial cells of small intestinal and renal proximal tubules is characterised by the presence of many microvilli (brush border). These membranes can be isolated relatively easily by centrifugation and free flow electrophoresis techniques. Kinne-Saffran and Kinne [15] found that after free-flow electrophoresis of a rat kidney-cortex membrane preparation, the anion-sensitive ATPase co-migrated with the alkaline phosphatase activity but was separated from the (Na + K )-ATPase activity, which is assumed to be a marker of basolateral plasma membranes. This suggests that the brush-border membrane of the proximal tubule contains an anion-sensitive ATPase. The same conclusion was reached by Liang and Sacktor [17] for a brush-border preparation from rabbit kidney. 

Alkaline phosphatases (ALP) are a group of enzymes found primarily in the liver (isoenzyme ALP-1) and bone (isoenzyme ALP-2). There are also small amounts produced by cells lining the intestines (isoenzyme ALP-3), the placenta, and the kidney (in the proximal convoluted tubules). What is measured in the blood is the total amount of alkaline phosphatase released from these tissues into the blood. As the name implies, this enzyme works best at an alkaline pH (pH 10), and thus the enzyme itself is inactive in the blood. Alkaline phosphatase acts by splitting off phosphorus (an acidic mineral), creating an alkaline pH. The primary importance of measuring alkaline phosphatase is to check the possibility of bone or liver diseases. ... 

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