Intestinal peroxidase

Sibley, D.A., Grisham, M.B. and Specian, KD. (1991). The generation of bactericidal and cytotoxic oxidants by goblet cell intestinal peroxidase. Gastroenterology 100, A841. 

IP4 Inositol tetrakisphosphate IPF Idiopathic pulmonary fibrosis IPO Intestinal peroxidase IpOCOCq Isopropylidene OCOCq I/R Ischaemia-reperfusion IRAP IL-1 receptor antagonist protein IRF-1 Interferon regulatory factor 1 la Short-circuit current ISCOM Immune-stimulating complexes... 

Kimura S, Yamazaki I (1979) Comparisons between hog intestinal peroxidase and bovine lactoperoxidase-compound I formation and inhibition by benzhydroxamic acid. Arch Bio-chem Biophys 198 580-588... 

However, this will also prevent the formation of other cytotoxic species such as the hydroxyl radical. Further evidence that antioxidants prevent against the development of I/R injury comes from studies that show that previous ischaemic injury in the small intestine of rats results in prevention of further damage on subsequent ischaemic challenge in association with measured increases in mucosal glutathione peroxidase and catalase (Osborne et al., 1992). 

Enzyme labels are usually coupled to secondary antibodies or to (strept)avidin. The latter is used for detection of biotinylated primary or secondary antibodies in ABC methods (see Sect. 6.2.1). Enzyme labels routinely used in immunohisto-chemistry are horseradish peroxidase (HRP) and calf intestinal alkaline phosphatase (AP). Glucose oxidase from Aspergillus niger and E. coli (3-galactosidase are only rarely applied. 

Enzymatic markers used in immunohistochemistry Horseradish peroxidase (HRP) and calf intestinal or E.coli alkaline phosphatase (AP). Glucose oxidase from Aspergillus niger and E.coli /3-galactosidase are only rarely applied. 

Peroxidases. Another group of enzymes, which is involved in the oxidation of xenobiotics, is the peroxidase. There are a number of these enzymes in mammalian tissues prostaglandin synthase found in many tissues, but especially seminal vesicles and also the kidney, the lung, the intestine spleen, and blood vessels lactoperoxidase found in mammary glands myeloperoxidase found in neutrophils, macrophages, liver Kupffer cells, and bone marrow cells. 

Different tissues contain different isoenzymes of alkaline phosphatase, and the intestinal isoenzyme is not inhibited by levamisole The enzyme used in immu-nohistochemistry is extracted from calf intestine, so that levamisole can be used as an inhibitor without affecting the desired reaction. For labile antigens in the intestine, it is better to switch to the peroxidase method. 

Antigens can he present in intestinal lymphoid tissue by the transport of macros molecules across M-cells. Hie enzyme marker horseradish peroxidase is trans-... 

The flux of horseradish peroxidase from the mucosal to serosal sides is jnwsrimiuj hy in vital KinmmenN jn slrinnpJ anlrffijih intestinal epithelium. Through enzymology and electron-microscopic techniques the intestinal uptake is shown [50],... 

R. L. Owen, Sequential uptake of horaeiadiah peroxidase by lymphoid follicle cptheinim of Foyers patches in the neonatal unobstructed mouse intestine on uhrastaucturat study. Gastroenterology 72 440-451 (1977). 

A. Kiliaan, G. Scholten, P. B(jlsma, K Dekko and J. Groot. Influence of fbnkolln and cnrhaehol on intestinal absorption of horseradish peroxidase in the goldfish... 

Immunoenzymatic staining methods utilize enzyme substrate reactions to convert colorless chromogens into colored end products. Of the enzymes used in these applications, only horseradish peroxidase and calf intestine alkaline phosphatase will be considered in some detail. Because of its low sensitivity, glucose oxidase (Aspergillus niger) is only rarely used today. 

Horseradish peroxidase and calf intestine alkaline phosphatase meet most of these criteria, and the following will list their properties in more detail. 

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. 

Unquenched endogenous alkaline phosphatase activity may be seen in leucocytes, kidney, liver, bone, ovary bladder, salivary glands, placenta and gastro-intestinal tissue. Add levamisole to the alkaline phosphatase chromogen reagent or use another enzyme label such as horseradish peroxidase. Intestinal alkaline phosphatase is not quenched by the addition of levamisole. Pretreat the tissue with 0.03 N HCI. 115-121... 

Occult blood is defined as traces of blood in the stool which are not perceptible to the naked eye. Usually, the passage of blood into the intestinal contents amounts to around 2 ml/day. Proof of occult blood is obtained by chemical testing (e. g. peroxidase reaction), although it is only possible to detect amounts of blood in excess of 1.5-2.0 ml/100 ml stool or to demonstrate them by means of an immunological rapid diagnostic test with a specificity of virtually 100%. The test usually comprises three specimens collected at different points in time. (s. p. 349)... 

The M cells found in Peyer s patches have also been suggested to transport particles. These are specialized absorptive cells known to absorb and transport indigenous bacteria (i.e.. Vibrio cholerae)-, macromolecules, such as ferritin and horseradish peroxidase viruses and carbon particles, from the lumen of the intestine to submucosal lymphoid tissue (33,37,38). It has been reported that hydrophobic, negatively charged or neutral particles of size smaller than 5 pm are better taken up by M cells particles smaller than 1 pm in size accumulate in the basal medium, while larger particles remain entrapped in the Peyer s patches (39). Transport of absorbed materials to the systemic circulation... 

Little is known about the specific biochemical mechanism(s) by which selenium and selenium compounds exert their acute toxic effects. Long-term effects on the hair, skin, nails, liver, and nervous system are also well documented, and a general theory has been developed to explain the toxicity of exposure to excess selenium, as discussed below. Generally, water-soluble forms are more easily absorbed and are generally of greater acute toxicity. Mechanisms of absorption and distribution for dermal and pulmonary uptake are unknown and subject to speculation, but an active transport mechanism for selenomethionine absorption in the intestine has been described (Spencer and Blau 1962). The mechanisms by which selenium exerts positive effects as a component of glutathione peroxidase, thioredoxin reductase, and the iodothyronine 5 -deiodinases are better understood, but the roles of other selenium-containing proteins in mammalian metabolism have not been clarified. 

Figure 3 Diagram summarizing the stages observed in the transport of horseradish peroxidase (HRP) by the M cell from the intestinal lumen to the intraepithelial lymphocyte. C Columnar cells L lymphocytes. (From Ref. 24.)...

---