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Digestive enzymes of the mucosa of the small intestine and trypsin and chymotrypsin proteolytic activity of the intestinal contents of germ-free, monocontaminated and conventional rabbits.

The activity of the membrane-bound enzymes of the microvillous zone of the entreocytes (maltase, sucrase, trehalase, lactase, cellobiase, alkaline phosphatase and leucylaminopeptidase) was studied in mucosal smears from the proximal jejunum, ileum, caecum and sigmoid flexure in a group of control (C) (8) and germ-free (GF) (7) rabbits. The trypsin and chymotrypsin activity of the contents of the ileum, caecum and sigmoid flexure was studied in 6 C, 5 GF and 5 monocontaminated (MC) rabbits. In summing up it can be stated that the individual membrane-bound enzymes have a different gradient in the various intestinal segments of C and GF rabbits and that they differ reciprocally in character. The maximum statistically significant differences between GF and C rabbits were found in the ileum; in the jejunum they were somewhat smaller and in the caecum smaller still (in this localization the difference was C versus GF). Striking differences in the proportion of the individual disaccharidases were found inthe jejunum and ileum of C rabbits compared with GF rabbits, in which, in both these segments of small intestine the relationship maltase greater than sucrase greater than trehalase greater than lactase was preserved. The proteolytic activity of the intestinal contents likewise had a different gradient character in C, MC and GF rabbits. The maximum activities (especially trypsin) were found in MC animals. The microbial flora is one of the factors regulating the enzymatic activities of the microvillous zone of the enterocytes and it also significantly influences the proteolytic activity of the intestinal contents. This influence is particularly marked in the distal part of the alimentary tube.

Animals↗

Intestinal disaccharidase and alkaline phosphatase activities in experimental rabbit mucoid enteropathy.

Mucoid enteropathy was induced experimentally by ligation of the cecum, and the activities of mucosal disaccharidases and alkaline phosphatase were measured at different locations along the small intestine of the sick and control rabbits. In the duodenum of rabbits with mucoid enteropathy, the activity of acid beta-galactosidase II was elevated and hetero beta-galactosidase declined. In the jejunum, the activities of lactase, acid beta-galactosidase I and II, hetero beta-galactosidase, trehalase, sucrase and alkaline phosphatase were significantly lower in animals with mucoid enteropathy. In the ileum, acid beta-galactosidase II, hetero beta-galactosidase, maltase, trehalase, sucrase and alkaline phosphatase showed decreased activity in rabbits with mucoid enteropathy.

Alkaline Phosphatase↗

Precancerous changes in the stomach.

Intestinal metaplasia is often associated with human gastric carcinoma. Intestinalization seems to be a typical example of abnormal differentiation and is possibly a precancerous state. For investigation of intestinal metaplasia, a method for visualizing disaccharidases using Tes-Tape was developed; this method was applied to many specimens of stomach surgically removed for the treatment of gastric carcinoma. More than 130 specimens of human stomach were investigated. Intestinalization was classified into types I and II intestinal metaplasia. In type I intestinal metaplasia, sucrase, maltase, trehalase, alkaline phosphatase, goblet cells, and Paneth cells were present; while the type II intestinal metaplasia, sucrase and maltase were present but alkaline phosphatase and trehalase were absent. In type II, goblet cells were present but not Paneth cells. The histochemical technique for sucrase was newly devised. Some of the villi with goblet cells in the area of intestinalization in the stomach were not stained by sucrase activity, although most of the villi were stained. The presence of a third type of metaplasia was suggested. Purified sucrases obtained from the intestine and one case of type I intestinal metaplasia showed blood group reactivity due to the oligosaccharide side chain. However, purified sucrases obtained from two cases of type II intestinal metaplasia were negative in blood group reactivity. A close relation between distribution of alpha-fetoprotein and carcinoembryonic antigen in gastric carcinoma and that in surrounding intestinal metaplasia is discussed.

Carcinoembryonic Antigen↗

[In vitro study of anthelmintic influence on activities of digestive enzymes in extracts from the gut of Ascaris suum and pig's pancreas].

The effect of eight anthelmintics (Rintal, Fenbesan, Telmin, Banminth, Pyrantel, Nilverm, Levamisol and Bioscardina) on the alpha- and gamma-amylases, trypsin, and lipase from pig's pancreas and gut of Ascaris suum was determined. In extracts from A. suum gut also the maltase, trehalase and saccharose activities were examined. All drugs tested did not influence on the host's alpha-amylase. Telmin and Bioscardina were inhibitors of gamma-amylase, Rintal and Telmin--of trypsin, Fenbesan and Bioscardina--of lipase from pig's pancreas. Among the parasite's enzymes the lipase was the most sensitive. Its activity was decreased (35-60%) by Telmin, Nilverm and both pyrantel derivatives. The activity of maltase and trehalase was reduced by Levamisole and Banminth, that of saccharose by Levamisole. It is concluded that the anthelmintics Levamisole and Banminth seemed the most efficient among the tested drugs because they did not alter the activity of host's enzymes and, showed the inhibitory effect on three of parasite's enzymes.

Animals↗

Biochemical effects of high intensity constant magnetic fields on worker honey bees.

Hemolymph samples from adult bees that had completed their pupal development and emergence in a 7 Tesla field contained a lower percentage of glucose than controls, indicating that trehalase enzyme activity in honey bees is reduced in strong magnetic fields. Significantly more phospholipids were found in the intestines of magnetic field-exposed bees than in controls. No significant differences were found for fatty acids, triacylglycerols, or steroids.

Animals↗

Effects of hydrocortisone on carbohydrase concentrations, de novo synthesis and turnover patterns in immature rat intestine.

Hydrocortisone administration to infant rats enhanced cellobiase and maltase activities and induced precocious expression of sucrase and trehalase activities along the length of the small intestine. These activity changes reflected proportional concentration increases in the enzymes lactase (EC 3.2.1.23), maltase/glucoamylase (EC 3.2.1.20) and sucrase-isomaltase (EC 3.2.1.48/10). Administration of an equivalent tracer dose of [3H]leucine (by body weight) to control and hydrocortisone-treated infant rats resulted in greater accumulation of label in the carbohydrase pools of the treated rats, suggesting their increased de novo synthesis. The increased concentrations of lactase and maltase/glucoamylase induced by exogenous hydrocortisone were matched by the presence of corresponding greater amounts of label in their brush border pools. Accumulation of label in each of the lactase, maltase/glucoamylase and sucrase-isomaltase pools was generally similar in the hydrocortisone-treated rats, suggesting equivalent stimulation of their synthesis as a group by the humoral agent. The turnover rates of the carbohydrases as a group were found to be similar and did not appear to differ in control and hydrocortisone-treated rats. Total protein synthesis rates were slightly greater in the intestine of the hydrocortisone-treated group of rats.

Aging↗

In vitro study of the intestinal brush border enzyme activities in developing anuran amphibian: effects of thyroxine, cortisol, and insulin.

The effects of several hormones on intestinal brush border membrane enzymatic activities have been investigated in intestinal explants taken from the amphibian midwife toad at different developmental stages. Explants were treated for at least 2 days with thyroxine (0.1 microgram/ml of culture medium) or for 2 days with cortisol (25 micrograms/ml) or insulin (6 mU/ml). The hydrolases examined were maltase, trehalase, glucoamylase, and alkaline phosphatase. In the explants from tadpoles in prometamorphosis, thyroxine had no effect on hydrolase activities; cortisol increased the activity of only glucoamylase, and insulin increased activity of maltase, glucoamylase, and alkaline phosphatase. When the explants were taken from tadpoles at the beginning of climax, cortisol and insulin generally stimulated the enzyme activities studied. When taken from tadpoles at the end of climax, at the moment when the embryonic cells under the degenerating epithelium divide, cortisol and insulin had little effect on these activities. When the animals terminate their metamorphosis, the intestinal epithelium of the explants is totally newly formed (secondary epithelium). At this time, cortisol stimulated the activities of maltase, glucoamylase, and alkaline phosphatase, while insulin decreased the activities of maltase and glucoamylase.

Alkaline Phosphatase↗

Discriminant analysis for assessing the value of amniotic fluid microvillar enzymes in the prenatal diagnosis of cystic fibrosis.

We have analysed the sensitivity, specificity, and reliability of biochemical diagnosis based on microvillar membrane enzyme assay and using discriminant analysis in amniotic fluid samples obtained from 54 pregnancies at high risk for cystic fibrosis and 125 normal pregnancies. Our results show that amniotic fluid trehalase, alkaline phosphatase, alkaline phosphatase isoenzymes and gamma-glutamyltransferase enzyme activities measured during 16-20 gestational weeks, in spite of their non-specificity for cystic fibrosis, have a very good predictive value for fetal cystic fibrosis or exclude the possibility of the disease. Overall enzyme activity analysis provided over 90 per cent reliability of the method.

Alkaline Phosphatase↗

Isolation and characterization of a phosphoprotein phosphatase-deficient mutant in yeast.

The ppd1 mutant of yeast, Saccharomyces cerevisiae, was isolated as a suppressor of the cyr2 mutation which caused alteration of the catalytic subunit of cAMP-dependent protein kinase. Three peaks of phosphoprotein phosphatase activity (peak I, II and III) were identified by DEAE-Sephacel chromatography of crude extracts of the wild-type strain. The ppd1 mutant was deficient in peak III phosphoprotein phosphatase activity. The peak III enzyme efficiently utilized the phosphorylated forms of NAD-dependent glutamate dehydrogenase and trehalase as substrate. The ppd1 mutation did not suppress the cyr1, CYR3 or ras1 ras2 mutations. The ppd1 locus was located on chromosome II and had identical characteristics with glc1. The ppd1 mutation suppressed the G1 arrest caused by nutritional limitation, but maintained sensitivity to mating pheromone. In diploids homozygous for the ppd1 mutation, no premeiotic DNA replication and commitment to intragenic recombination occurred and no spores were formed, suggesting that the accumulation of phosphorylated proteins in the absence of one of the phosphoprotein phosphatases is required for mitosis but not for the initiation of meiosis.

Cyclic AMP↗

Effect of fenvalerate-20EC on sericigenous insects. II. Digestive enzymes in the nutritive physiology of silkworm, Bombyx mori L.

Changes in the activities of a few digestive enzymes after fenvalerate-20EC treatment were studied during the late stages of multivoltine and bivoltine silkworms, Bombyx mori. Insecticide treatment induced a reduction in the activity of such enzymes as amylase, sucrase, and protease, whereas the trehalase activity was enhanced when the midgut was used as the source of enzyme. The changes recorded in the activity of these enzymes indicated probable adverse effects of fenvalerate on silkworm metabolism through interference with the functional abilities of digestive enzymes.

Amylases↗

Transport and metabolism of trehalose in Escherichia coli and Salmonella typhimurium.

The metabolism of trehalose in wild type cells of Escherichia coli and Salmonella typhimurium has been investigated. Intact cells of Escherichia coli (grown on trehalose) accumulated [14C]-trehalose as [14C]-trehalose 6-phosphate. Toluene-treated cells catalyzed the synthesis of the [14C]-sugar phosphate from [14C]-trehalose and phosphoenolpyruvate; ATP did not serve as phosphoryl donor. Trehalose 6-phosphate could subsequently be hydrolyzed by trehalose 6-phosphate hydrolase, an enzyme which catalyzes the hydrolysis of the disaccharide phosphate into glucose and glucose 6-phosphate. Both Escherichia coli and Salmonella typhimurium induced this enzyme when they grew on trehalose. These findings suggest that trehalose is transported in these bacteria by an inducible phosphoenolpyruvate:trehalose phosphotransferase system. The presence of a constitutive trehalase was also detected.

Biological Transport↗

The effect of gamma radiation on breaking of dormancy in Phycomyces spores.

Dormant sporangiospores of Phycomyces blakesleeanus were activated by Cs-137 gamma rays. After a dose of about 300 krad, between 80 and 90% of the spores germinated normally. However, further development of the mycelium was inhibited. Even with dry spores a partial activation was obtained. Activation by gamma rays was not accompanied by an increase in trehalase activity.

Cesium Radioisotopes↗

Disaccharidase deficiencies in Mongolian gerbils (Meriones unguiculatus) protected against Giardia lamblia.

The activities of the disaccharidases lactase, maltase, sucrase and trehalase were examined in gerbils during Giardia lamblia infections. In a primary infection with trophozoites, the activities of all four enzymes were reduced from day 10 post-infection (p.i.) and remained at low levels well past the elimination phase of the infection. However, during a challenge infection, the disaccharidase decreases were short-lived, with impairments being seen only on days 2 and/or 4 post-challenge (p.c.). Sucrase activity was not affected by a challenge infection. When 0.1 mg of a soluble extract of G. lamblia trophozoites was used to challenge gerbils previously exposed to the live parasite, the pattern and duration of enzyme deficiencies were comparable with those observed after the challenge with the live parasite. In addition, decreasing the extract dose used to challenge the gerbils led to smaller disaccharidase deficiencies. G. lamblia-infected gerbils were also challenged with a soluble extract of Entamoeba histolytica trophozoites, and this had no effect on the disaccharidase activities. Therefore, the presence of the intact parasite was not necessary to induce enzyme reductions in immune animals. In addition, the effects seen during the secondary infection were parasite-specific and may have involved the host's immune response to Giardia antigens. Immune gerbils were further challenged with the in vitro-released excretory/secretory products of G. lamblia. Under our experimental conditions, disaccharidase activities were found to be affected by these products in a manner that was inconsistent with the results of the live parasite challenge, and this merits further study.

Animals↗

Differentiated properties characteristic of renal proximal epithelium in a cell line derived from a normal monkey kidney (JTC-12).

The JTC-12 cell, an established cell line derived from a normal monkey kidney, was studied in an attempt to characterize the epithelial qualities. Phase contrast microscopy showed dome formation in confluent monolayers and electron microscopic examinations revealed the presence of numerous microvilli on the apical membranes and desmosome between cells. Sonicated cells showed activities of gamma-glutamyl transpeptidase, leucine aminopeptidase, alkaline phosphatase, and trehalase, marker enzymes of renal proximal epithelium. Alkaline phosphatase activity exhibited the characteristics of a renal type isozyme. Furthermore, confluent JTC-12 monolayers exhibited Na+-dependent transport of hexose, amino acid as well as inorganic phosphate. These findings indicate that JTC-12 cells in monolayer culture maintain ultrastructural, biochemical, and physiological properties of renal proximal epithelial cells. This cell line will be useful for further studies on cellular functions of renal proximal epithelium.

Alkaline Phosphatase↗

Intestinal brush border enzymes after short-term mesenteric ischemia.

The total activities of sucrase, trehalase, amino-peptidase, and gamma-glutamyltransferase in the isolated brush border of the entire small bowel are reduced to 35, 55, 33, and 21 per cent, respectively, of control values (p less than 0.001) 2 hours after a 45 minute occlusion of the superior mesenteric artery. Since brush border proteins are also reduced by ischemia to 42 per cent of control, enzymatic activity when expressed as U/mg protein is significantly reduced only in the case of gamma-glutamyltransferase, to 48 per cent of control.

Animals↗

Solubilization of brush borders of hamster small intestine and fractionation of some of the components.

About 90% of the protein of hamster intestinal brush borders was solubilised in 0.25% (w/v) sodium dodecyl sulphate without total loss of biological activity. Detergent-polyacrylamide gel electrophoresis of the solubilised proteins separated 10-15 bands and partially resolved maltase, lactase, sucrase-maltase, trehalase and alkaline phosphatase activities. The disaccharidases, which were associated with the higher molecular weight proteins, were preferentially solubilised with 0.1%. (w/v) Triton X-100, butanol or papain, whereas Tris and NaI extracted only the lower molecular weight proteins, possible derived from the core filaments. Electrophoresis of brush border proteins metabolically labelled with [14-C] glucosamine suggested that many of the membrane-bound enzymes are glycoproteins. However, chromatography of a papain digest on Sephadex G-200 showed that the sucrase-maltase complex can be separated nearly free of carbohydrate without total loss of activity. The importance of characterizing membrane proteins solubilised by a number of techniques is discussed.

Alkaline Phosphatase↗

Enzymic solubilization of the human intestinal brush border membrane enzymes.

The releases of proteins, maltase, lactase, sucrase, trehalase, alkaline phosphatase, gamma-glutamyltransferase and leucylnaphthylamide-hydrolyzing activity from human intestinal brush bborder membrane vesicles by various enzymes (especially pancreatic proteases) have been studied. The brush border membrane enzymes are not solubilized by digestion with trypsin and chymotrypsin but are largely released after treatment with papain or elastase. Most of the enzymes are fully active after the proteolytic treatment. All proteins released by papain and elastase have been identified by electrophoresis to already known intestinal hydrolases. Electron microscopy of brush border membrane vesicles demonstrates "knob-like" structures (particles) attached to the external side of the membrane. During papain treatment, enzyme removal runs parallel with the disappearance of the particles. During elastase treatment it is not possible to correlate the release of the enzymic activities with the removal of the particles. The results indicate that most of the intestinal hydrolases are surface components attached to the external side of the membrane. They are in accord with the concept that the brush border membrane enzymes are organized within the membrane in a mosaic-like pattern.

Cell Membrane↗

Glycosidases of the guinea pig brush border membrane.

The separation by polyacrylamide gel electrophoresis and subsequent enzymatic analysis of the components of the guinea pig intestinal brush border membrane revealed the presence of three enzyme complexes: maltase-glucoamylase, maltase-sucrase-glucoamylase and maltase-sucrase. Additional bands possessing lactase, trehalase and alkaline phosphatase activity were identified but no phlorizin hydrolase or palatinase was detectable. After exposure to strong dissociating conditions the bands possessing enzymatic activity were either absent or greatly reduced in intensity.

Alkaline Phosphatase↗