Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.20 (alpha-glucosidase)
4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The in vivo absorption of 3-O-methyl-D-glucose (3MG) as a marker of intestinal function has not been studied in an animal model. We evaluated the use of 3MG as a marker of intestinal absorption when given enterally to rats recovering from small bowel mucosal injury induced by methotrexate (MTX). Radiolabeled 3MG was administered into the duodenum of control (CON) and MTX-treated rats and blood samples were obtained at specified intervals. Mucosal permeability was also assessed using radiolabeled mannitol and polyethylene glycol 900 (PEG). Concentration time points were plotted, and area under the curve was calculated as an approximation of absorbed dose. Mucosal weight, maltase activity, and protein content were determined on mucosal scrapings. During the acute phase (day 5), 3MG absorption and maltase-specific activity were significantly decreased in the MTX group when compared to the CON group (p less than 0.001). The MTX group showed a trend toward greater permeability to mannitol when compared to the CON group; however, this was not statistically significant. Mucosal permeability to PEG was similar in both groups. During a later stage in the recovery process (day 12), the area under the curve calculations for 3MG absorption were the same for both CON and MTX animals, with maltase activity in the MTX group recovering to control values. Changes in 3MG absorption paralleled total maltase activities following severe injury. These results suggest that the combined active and passive transport of 3MG in vivo could be of use as a marker of intestinal absorption in states where the small intestine has sustained major damage resulting in compromised absorption as well as brush border digestion.
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PMID:The intestinal absorption of 3-O-methyl-D-glucose in methotrexate-treated rats: an in vivo study of small bowel function. 177 9

The effect of chronic intragastric infusion of hypertonic mannitol on small intestinal mucosal structure and function was studied in adult rats. Animals were gavage-fed 20% mannitol (1300 mosm) at a dose of 5 ml/100 g body weight daily for seven days. Control animals were gavage-fed tap water on the same schedule. On day 8, the animals were anesthetized, the duodenum cannulated, and a test sugar (glucose, glucose polymer, lactose, sucrose, or maltose) was infused at a dose of 0.5 g/kg body weight in 2.5 ml distilled water over less than 1 min. Portal vein glucose was measured at 30-min intervals from 0 to 120 min. Mannitol treatment resulted in histologic and biochemical alterations (reduced lactase, sucrase, maltase) limited to the proximal small intestine compared to the control group. The absorption of glucose and glucose polymers was similar in mannitol-treated and control animals. In contrast, digestion and absorption of lactose, sucrose, and maltose was significantly diminished in mannitol-treated animals when compared to controls. No changes in permeability to polyethylene glycol 4000 or Na+-coupled glucose transport were observed in mannitol-treated animals compared to controls. These data suggest that when the intestinal mucosa is exposed to hyperosmolar loads that the digestive capacity for disaccharides is suppressed more than its glucose absorptive capacities. Furthermore, glucose oligomers may be more readily digested and absorbed than disaccharides, in this setting, due, in part, to the proximal injury and less pronounced proximal-distal gradient for glucoamylase than other brush-border carbohydrases.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Proximal small intestinal mucosal injury. Maintenance of glucose and glucose polymer absorption, attenuation of disaccharide absorption. 249 65

Brush border membrane vesicles (BBMV) were prepared from eel (Anguilla anguilla) intestine by a Mg-ethylene-glycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid precipitation technique; the BBMV were enriched 16, 12, and 13 times in leucine aminopeptidase, maltase, and alkaline phosphatase activities with respect to the starting mucosal scraping. D-[3H]glucose and L-[3H]alanine transport by these vesicles was studied by a rapid filtration technique. D-Glucose uptake was stimulated by a transmembrane Na gradient but not by an identical Na gradient in the presence of phloridzin or by a choline gradient. The Na-dependent D-glucose uptake was increased by rendering the vesicle interior electrically negative, suggesting electrogenic cotransport of the sugar with Na+. Kinetic analysis gave an apparent affinity constant (Kapp) of 0.20 mM and maximal rate (Jmax) of 6.87 nmol X mg protein-1 X min-1 for glucose influx in the presence of a Na gradient. In addition, a significant apparent diffusional permeability of these membranes to glucose (1.41 microliters X mg protein-1 X min-1) was observed. L-Alanine uptake in eel BBMV was shown to occur via 1) saturable Na-dependent pathway (Kapp = 1.29 mM, Jmax = 3.61 nmol X mg protein-1 X min-1), 2) a saturable Na-independent pathway (Kapp = 0.59, Jmax = 1.49), and 3) a nonsaturable component representing apparent diffusion (permeability coefficient P = 0.57 microliter X mg protein-1 X min-1). These findings suggest that similar transport systems for glucose and alanine are found in the fish and mammalian intestinal brush border membrane.
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PMID:Na-dependent D-glucose and L-alanine transport in eel intestinal brush border membrane vesicles. 375 80

Absorption of carbohydrate was quantitated in 49 subjects without disease of the small bowel using a new technique for ileal perfusion. A double-lumen tube with an attached balloon was inserted retrograde through the colon and used to quantify arrival in the ileum of D-xylose and a nonabsorbable marker which had been taken orally. In the same way, absorption of sucrose and the effects of an inhibitor of alpha-glucosidase were also studied. Insertion of the assembly through the colon and intubation of the terminal ileum was usually possible within 30 min; we have designated the technique, endoscopic retrograde bowel insertion (ERBI). The test meals were 500 ml of water containing either 25 g D-xylose and 5 g polyethylene glycol (PEG 4000), or 100 g sucrose with 5 g PEG. Sucrose meals also contained 0, 100, or 200 mg of an inhibitor of alpha-glucosidase (BAYg5421). At the end of a 5-hr test period, the ratio of recovery of D-xylose relative to that of PEG indicated that 69% of D-xylose was absorbed. Five-hour urinary excretion of D-xylose was 31% of that ingested, or 45% of the D-xylose which was absorbed. Sucrose was recovered in ileal samples only when administered together with inhibitor. Rates of sucrose absorption with BAYg5421, 100 and 200 mg, were 75% and 65%, respectively. The perfusion technique of ERBI is a rapid and reproduceable approach to the distal small intestine of man which could be of value in the investigation of intestinal absorption.
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PMID:New method of testing for carbohydrate absorption in man. Xylose and sucrose absorption; effects of sucrase inhibition. 395 33

A conventional brush border membrane preparation, obtained by divalent cation precipitation of homogenates of rabbit renal cortex, was analyzed by countercurrent distribution in an aqueous dextran:polyethylene glycol two-phase system. The resulting fractions were assayed for the presence of the Na+/H+ antiporter and for a variety of biochemical marker enzymes. This analysis revealed four physically distinct membrane populations (A-D). Population A consisted of two subpopulations, A' and A", which were enriched an average of 49-fold in maltase; they were also highly enriched in alkaline phosphatase, leucine aminopeptidase, and Na+/H+ antiporter. On the basis of their marker contents, populations A' and A" appear to represent highly purified, functional brush border membrane vesicles. Population B was enriched twofold in NADPH-cytochrome c reductase and population C was enriched 12-fold in galactosyltransferase. Populations B and C accounted for 25% of the protein in the starting material and appear to reflect contamination of the brush border membrane preparation by subpopulations of endoplasmic reticulum and Golgi fragments. Population D was enriched in Na+/H+ antiporter, alkaline phosphatase, leucine aminopeptidase, Na-K-ATPase, and acid phosphatase but not maltase, NADPH-cytochrome c reductase, galactosyltransferase, or succinate dehydrogenase. Its identity is unclear, and it might consist of a multiplicity of populations from different origins.
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PMID:Na+/H+ antiporter in membrane populations resolved from a renal brush border vesicle preparation. 633 Nov 75

Failure to develop clear-cut, distinguishing characteristics for hydrophobic and hydrophilic forms of maltase-glucoamylase led us to attempt the purification of the detergent-extracted enzyme in the continuous presence of protease inhibitors (phenylmethylsulfonyl fluoride and N-ethylmaleimide). The enzyme was purified by molecular exclusion, anion-exchange, and affinity column chromatography to a final specific maltase activity of 80 U/mg protein, comparable to previously solubilized enzymes. Both detergent (d-maltase) and proteolytically (p-maltase) solubilized enzymes had identical Km's for maltose and similar glycogenase activity. d-Maltase was clearly amphipathic. Whereas 95% of p-maltase was eluted with aqueous buffer from an octyl-Sepharose CL-4B column, the elution of d-maltase required solutions containing Triton X-100 and ethylene glycol. On density gradient centrifugation and sodium dodecyl sulfate (SDS)--polyacrylamide gels, p-maltase migrated as one high molecular weight species of 500,000. In contrast d-maltase migrated heterogeneously and the smallest maltase-active forms delineated by these two techniques, as well as by high pressure liquid chromatography, had molecular weights which ranged from 120,000 to 15,0000. Both p- and d-maltase were dissociated by heat in SDS, forming five prominent species as we have previously described. In contrast to p-maltase, in which the smallest species, band 1, equalled 36.7% of the total mass, band 1 of d-maltase accounted for 66.5%. Band 1 was separable when smaller amounts of enzyme were applied to slab gels and stained with silver, into two proteins of 130,000 and 145,000 daltons. The 145,000 dalton protein was absent in p-maltase and was replaced by a faint band of 140,000 daltons.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Rat intestinal maltase--glucoamylase. Purification of the detergent-solubilized enzyme in the presence of protease inhibitors: properties and identification of a protease-sensitive subunit. 642 12

Aqueous two-phase protocols have been established which successfully generate highly purified preparations of small inclusion bodies (IBs) from whole cell homogenates. Particle size analysis of disruptates confirmed that intense disruption (concomitant with maximal product release) was compromised by the corelease of contaminating solutes and the micronisation of cell debris yielding a similar particle size range to the IBs (100-200 nm). PEG 300-phosphate systems enabled partial recovery of IBs in the top phase of ATPS. In contrast, PEG 8000-phosphate systems partitioned IBs more efficiently as a discrete sediment within the lower phase, whilst the majority of micronised debris remained in the interphase. The alpha-glucosidase IB yield and purity in ATPS was bettered only by analytical sucrose density gradient centrifugation, which is not readily scaleable for application in process operations. The successful recovery of such small IBs from complex homogenates highlights a generic role that ATPS techniques might play in the recovery and purification of new bioparticulate products (viral and plasmid gene therapy vectors, particulate protein vaccines etc.).
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PMID:Aqueous two-phase systems as an alternative process route for the fractionation of small inclusion bodies. 969 87

Nonlipophilic corynebacteria associated with clinical and subclinical mastitis in dairy cows were found to belong to four species: Corynebacterium amycolatum, Corynebacterium ulcerans, Corynebacterium pseudotuberculosis, and Corynebacterium minutissimum. These species may easily be confused. However, clear-cut differences between C. ulcerans and C. pseudotuberculosis were found in their acid production from maltotriose and ethylene glycol, susceptibility to vibriostatic agent O129, and alkaline phosphatase. Absence of growth at 20 degrees C and lack of alpha-glucosidase and 4MU-alpha-D-glycoside hydrolysis activity differentiated C. amycolatum from C. pseudotuberculosis and C. ulcerans. The mastitis C. pseudotuberculosis strains differed from the biovar equi and ovis reference strains and from caprine field strains in their colony morphologies and in their reduced inhibitory activity on staphylococcal beta-hemolysin. C. amycolatum was the most frequently isolated nonlipophilic corynebacterium.
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PMID:Identification of nonlipophilic corynebacteria isolated from dairy cows with mastitis. 1007 8

Systems that can be polymerized in situ upon exposure to light radiation may have significant applications in tissue engineering and drug delivery. However, the light-induced polymerization step, which is the requisite for this technology, could be potentially deleterious to sensitive bioactive agents (e.g., enzymes, cytokines, matrix metalloproteinases) being entrapped. In this study, a method to protect sensitive molecules from a light-induced polymerizing environment is proposed. This method is based on the idea that nonaccessible substances cannot interact with the polymerizing species. To examine this concept, two model enzymes-namely, horseradish peroxidase and alpha-glucosidase-were protected by gelatin-based wet granulation and incorporated within a cured polyethylene glycol dimethacrylate, a photocurable monomer, under different conditions. Unprotected enzymes were used as controls. Enzymes were then allowed to diffuse out of the polymerized matrices. The activity and total enzyme recovered from these matrices by passive diffusion were compared to ascertain the extent of activity retention. Matrix assisted laser desorption ionization mass spectrometry combined with time of flight mass spectrometry (MALDI-TOF) was used to determine changes in enzyme molecular weight. During the first 24 h of diffusion from the polymerized matrices, unprotected enzymes consistently showed a loss of activity ranging from 10-66%, depending on the matrix composition and enzyme properties. In contrast, protected enzymes retained over 94% of their activity irrespective of the experimental setting. The loss of activity appears to be a direct consequence of the polymerizing environment.
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PMID:A method to protect sensitive molecules from a light-induced polymerizing environment. 1276 8

Rapidly progressing mucosal breakdown limits the intestinal preservation time below 10 h. Recent studies indicate that intraluminal solutions containing polyethylene glycol (PEG) alleviate preservation injury of intestines stored in UW-Viaspan. We investigated whether a low-sodium PEG solution is beneficial for intestines stored in histidine-tryptophane-ketoglutarate (HTK) preservation solution. Rat intestines used as control tissue (group 1) were perfused with HTK, groups 2 and 3 received either a customized PEG-3350 (group 2) or an electrolyte solution (group 3) intraluminally before cold storage. Tissue injury, brush-border maltase activity, zonula occludens-1 (ZO-1) and claudin-3 expression in the tight junctions (TJ) were analyzed after 8, 14 and 20 h. We measured epithelial resistance and permeability (Ussing chamber) after 8 and 14 h. Group 2 had superior morphology while maltase activity was similar in all groups. TJ proteins rapidly decreased and decolocalized in groups 1 3; these negative events were delayed in group 2, where colocalization persisted for about 14 h. Intestines in group 2 had higher epithelial resistance and lower permeability than the other groups. These results suggest that a customized PEG solution intraluminally reduces the intestinal preservation injury by improving several major epithelial characteristics without negatively affecting the brush-border enzymes or promoting edema.
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PMID:Intraluminal polyethylene glycol stabilizes tight junctions and improves intestinal preservation in the rat. 2254 29


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