Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ischaemia of the small intestine leads to the destruction of the intestinal mucosa. The capacity of the epithelium to regenerate is proportional to the duration of revascularization. The aim of this work was to analyze the kinetic aspects of intestinal epithelial regeneration after destruction due to prolonged ischaemia. This study was conducted in 44 animals (swine) after development of an ischaemia-revascularization protocol of a jejunal loop and bipolar secondary cutaneous exteriorization. After a first series with ischaemia times of 1, 2, 3 and 4 hours, the 4 hour period of ischaemia was chosen for further analysis of the regeneration kinetics over a period of 21 days since it leads to regular and total destruction of the epithelium compatible with regeneration. This analysis included (1) a histological examination (semi-thin slices), (2) immunofluorescent detection of intestinal brush border proteins on frozen slices (villin, saccharase-isomaltase, aminopeptidase N, dipeptidylpeptidase-IV) and mucines, (3) measurement of specific intestinal hydrolase activities (saccharase, aminopeptidase N, dipeptidylpeptidase-IV and alkaline phosphatase) in enriched brush border fractions, and (4) an analysis of variations in intestinal flora. After the 4 hour ischaemia, total destruction of the epithelium with disappearance of the villin and intestinal hydrolases and disorganization of the mucosa invaded by mucosal lacks was observed. Epithelial regeneration was rapid and two days later the histological aspect of the mucosa showed apical expression (still discontinuous), villin and intestinal hydrolase activity. Luminal apical expression of the markers became continuous on day 4, demonstrating the total recovery of the intestinal barrier as confirmed by stable microbial flora. Mucine expression also returned to normal. This regeneration was however incomplete since the mucosa was seen to be flat, without villosities. Immunofluorescence showed the weak intensity of brush border activity and the very low specific activity of hydrolase. Values were below normal and did not start to rise again until day 21. If serum levels and associated brush border markers could be measured and were significant, they could be specific markers of regeneration in double stomy ischaemic-revascularized intestine and thus eliminate the need for early second look laparotomy.
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PMID:[Effects of ischemia and revascularization on the epithelium of the small intestine: study on swine]. 798 9

To investigate the role of post-translational events in intestinal cell differentiation we have studied the effects of heat shock on processing and cell surface delivery of sucrase-isomaltase (SI), dipeptidylpeptidase IV (DPPIV) and aminopeptidase N (APN) in Caco-2 cells. In cells cultured at 42.5 degrees C there was a rapid decline in sucrase activity, while DPPIV and APN were unaffected over a 3-day period. Immunofluorescence staining confirmed the selective disappearance of SI from the surface membrane after only 1 day of culture at 42.5 degrees C. Cell-surface biotinylation of cells metabolically labelled with [35S]methionine 4 h after a switch from 37 degrees C to 42.5 degrees C demonstrated that newly synthesized APN and DPPIV were associated with the surface membrane, while SI was almost completely retained intracellularly. Pulse-chase experiments confirmed that, in these cells, DPPIV and APN were normally processed and vectorially delivered to the cell surface; in contrast, conversion between the two conformationally distinct high-mannose precursor forms of SI (hmP1 and hmP2) was markedly inhibited, a significant fraction of newly synthesized enzyme was degraded, probably in the ER, and an immature form of complex-glycosylated SI precursor (cP) was produced and mostly retained intracellularly. Double labelling of Caco-2 cells for SI and cathepsin D excluded an accumulation of SI in the lysosomes, suggesting that this organelle was not involved in the degradation of SI. These results indicate that the ER may play an important role in intestinal cell differentiation by regulating the conformational maturation, degradation and eventual cellular localization of some digestive enzymes.
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PMID:Intracellular degradation and reduced cell-surface expression of sucrase-isomaltase in heat-shocked Caco-2 cells. 810 Apr 14

To examine the postnatal development of equine small intestine, biopsy specimens of jejunal mucosa from 8 ponies, between 6 and 28 weeks old, were subjected to analytical subcellular fractionation and assay of organelle marker enzymes. Fractionation revealed a reduction in the particulate brush border component of beta-galactosidase (lactase) activity between 6 and 28 weeks, and a corresponding increase in soluble activity, although the reduction in mean specific activity was not significant. There also was a decrease in the proportion of brush border to soluble aminopeptidase N activity, a relative loss of brush border gamma-glutamyltransferase activity, and a considerable decrease in the specific activity of alkaline phosphatase throughout the gradient fractions. In contrast, there were marked increases in activities of alpha-glucosidase (maltase) and sucrase in the older ponies, accompanied by considerable changes in the intracellular distribution of particulate alpha-glucosidase activity, which was predominantly associated with endoplasmic reticulum at 6 weeks, whereas the large increase in activity observed by 28 weeks was clearly associated with the brush border. The modal density of brush borders also increased with age, suggestive of an increase in the glycoprotein-to-lipid ratio of the microvillar membrane. In contrast to these brush border changes, there was relatively little alteration in the activities or density distributions of marker enzymes for endoplasmic reticulum, basolateral membranes, mitochondria, or lysosomes. These findings indicate that maturation of equine intestinal epithelium during the first few months of life results in major changes in the properties and enzyme composition of enterocyte brush borders.
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PMID:Subcellular biochemical changes during the development of the small intestine of pony foals. 853 83

Erythromycin has been shown to inhibit the intestinal transport of L-threonine and D-galactose in strips of mucosal jejunum when it was directly added to the incubation medium. Nevertheless, the effect of erythromycin administered therapeutically by intramuscular injection on both the intestinal absorption of nutrients and the intestinal digestive activity, remains unknown. The results obtained show that, firstly, the intestinal absorption of L-threonine is inhibited in animals treated with erythromycin. The kinetic study shows that the effect seems to be mainly due to an alteration of the affinity apparent constant (Kt) of the Na(+)-dependent system of transport located in the mucosal border. However, the Na(+)-dependent L-threonine transport in BBMV was not altered by the treatment with erythromycin. The (Na(+)-K+) ATPase activity in BLMV from treated jejunum was 40% of the activity in control BLMV. Secondly, the treatment with erythromycin did not modify the digestive enzymatic activity of sucrase and aminopeptidase N.
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PMID:Study of the action of intramuscularly administered erythromycin on the L-threonine transport and the digestive enzymatic activity in rabbit jejunum. 876 16

This study describes the properties of a clone of immortalized cells (m-ICc12 cells) derived from the bases of small intestinal villi from 20-day-old fetuses of L-type pyruvate kinase (L-PK)/ TAg1 transgenic mice. The mice harbor the simian virus 40 large T antigen under the control of the 5' regulatory sequence from the L-PK gene. m-ICc12 cells expressed nuclear large T antigen, had a prolonged life span, and were nontumorigenic when injected into nude mice. They formed confluent monolayers of cuboid cells separated by tight junctions, developed dense, short apical microvilli, and formed domes. They also possessed cytokeratins, villin, aminopeptidase N, dipeptidyl-peptidase IV, and glucoamylase and retained crypt cell features, including intracellular sucrase isomaltase and alpha-L-fucose glycoconjugates accumulation and expression of the polymeric immunoglobulin receptor and the cystic fibrosis transmembrane conductance regulator gene. Thus the m-ICc12 cell line obtained by targeted oncogenesis in transgenic mice maintained in culture several important properties and differentiated functions of intestinal crypt cells.
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PMID:Transimmortalized mouse intestinal cells (m-ICc12) that maintain a crypt phenotype. 876 49

The role of luminal nutrients in regulating enterocyte gene expression was studied in a natural model for long-term fasting, the hibernating ground squirrel. Squirrels were studied during the active season and during the hibernation season when they had not eaten for at least 12 wk. The specific activities of sucrase, isomaltase, and intestinal alkaline phosphatase in jejunal brush-border membranes were similar in hibernating and active squirrels, whereas amino-oligopeptidase was reduced in hibernators. Na(+)-K(+)-adenosinetriphosphatase activity in jejunal mucosa was unchanged by hibernation. Densitometric analysis of Western blots showed that abundance of sucrase-isomaltase (SI), amino-oligopeptidase, and the Na(+)-glucose cotransporter SGLT1 was similar in the two activity states. Preservation of SI abundance in hibernation was confirmed by immunocytochemistry. Slot-blot analysis revealed no differences in mRNA levels for these proteins between hibernating and active squirrels. Enterocyte proliferation and migration rates were greatly suppressed in torpid squirrels but increased immediately upon rewarming during arousals. These results demonstrate the striking constancy of enterocyte gene expression despite long-term fasting in a hibernating mammal.
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PMID:Preservation of intestinal gene expression during hibernation. 894 94

The activities of carbohydrase, peptidases, alkaline phosphatase in the different parts of jejunum and in colon were determined. The minimum activity of all enzymes except the sucrase was observed in duodenum, the maximum one--in ileum. The significant activities of dipeptidases and alkaline phosphatase as well as the minimum activities of carbohydrase and aminopeptidase M were determined in colon.
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PMID:[The topography of the intestinal enzymes in rhesus macaques]. 909 44

This study has identified a naturally occurring, specific deficiency of a brush border aminopeptidase N (ApN) in the small intestines of five clinically healthy dogs. ApN activity in mucosal homogenates of dog small intestine was reduced significantly in deficient animals (13.4 (1.1) nmol min-1 mg-1 protein, n = 5, P < 0.002) compared to healthy control dogs (95.1 (6.7), n = 22). Alkaline phosphatase, gamma-glutamyl transferase, zinc-resistant alpha-glucosidase, maltase, sucrase and lactase in the ApN deficient dogs exhibited comparable activities to those in the control dogs. Microvillar membranes were analysed by one- and two-dimensional electrophoresis. ApN was represented by a single 145kDa band in all control dogs, identified by immunoblotting and immunoprecipitation. Protein maps from deficient dogs were normal apart from the virtual absence of an ApN spot and there were no apparent abnormalities in the glycosylation of microvillar proteins. The findings suggest that intestinal ApN deficiency in these dogs is a primary lesion involving diminished expression of an otherwise normal enzyme protein.
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PMID:An aminopeptidase N deficiency in dog small intestine. 942 46

The objective of the present study was to examine whether cinnamic acid exerts antitumor activity against colon cancer cells in vitro. For this purpose we investigated the effect of cinnamic acid on cell proliferation and on the differentiation markers alkaline phosphatase, sucrase and aminopeptidase N in human colon adenocarcinoma cells (Caco-2). Cinnamic acid (2.5-8.0 mM) prolonged the doubling time and inhibited the DNA synthesis of growing cells. The antiproliferative effect occurred rapidly after 2 h of treatment with 8.0 mM cinnamic acid and reached nearly maximal values after 8 h of treatment. Sucrase and aminopeptidase N activities were stimulated under cinnamic acid treatment (4.0-8.0 mM), while alkaline phosphatase activity was inhibited in postconfluent cells (8.0 mM). Similar effects on enzyme activities were seen in non-proliferating cells. Cinnamic acid did not alter the adhesion to collagen matrix or cell viability. Intracellular cAMP levels were decreased significantly after 1 h of treatment with 8.0 mM cinnamic acid, suggesting that cinnamic acid induces its effects on enzyme activities partly by modulating the cAMP signaling pathway.
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PMID:Cinnamic acid inhibits proliferation and modulates brush border membrane enzyme activities in Caco-2 cells. 968 74

Serotonin has been shown to alter the intestinal transport of ions and intestinal motility. These effects may interfere with each other, modulating the whole physiology of the intestine. We have previously shown that serotonin also alters the transport of nutrients. Thus, the aims of the present work were to determine the possible interference between the secretagogue effect of serotonin and the mechanism by which serotonin inhibits the absorption of nutrients, and to study the effect of serotonin on the digestive activity of nutrients of the brush border membrane jejunum enterocyte in the rabbit. The results show that the secretagogue effect of serotonin neither affects the inhibitory effect of serotonin on the intestinal absorption of the nutrients, nor affects the activity of Na+/K+-ATPase. The activity of sucrase and aminopeptidase N was also not affected by serotonin in the rabbit jejunum. Finally, we also studied different parameters of the motility in the rabbit small intestine. Serotonin seemed to stimulate the motility of the rabbit small intestine by increasing integrated mechanical activity and tone of muscle fibers in duodenum, jejunum, and ileum. In conclusion, serotonin might alter or modulate the whole intestinal physiology.
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PMID:Effects of serotonin on the physiology of the rabbit small intestine. 1084 30


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