The Effects of Prednisolone on the Rat Enterocyte at a Subcellular Level

1978 ◽  
Vol 55 (5) ◽  
pp. 435-443
Author(s):  
R. M. Batt ◽  
G. Wells ◽  
T. J. Peters
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Equilibrium Density ◽  
Proximal Jejunum ◽  
Brush Border Enzymes ◽  
Brush Borders ◽  
Brush Border Enzyme ◽  
Mitochondrial Malate Dehydrogenase ◽  
Subcellular Level ◽  
Isopycnic Centrifugation

1. Enterocytes, isolated from the proximal jejunum and distal ileum of normal and prednisolone-treated rats, were homogenized and fractionated by isopycnic centrifugation on sucrose density gradients. The distributions of marker enzymes for the principal subcellular organelles, RNA and protein were determined and related to the activities per enterocyte. 2. In enterocytes from the jejunum and ileum of prednisolone-treated animals the activities of particulate brush-border enzymes and of both soluble and mitochondrial malate dehydrogenase were increased compared with those of the control system. The equilibrium density of the brush borders was enhanced in the prednisolone-treated jejunum. The modal densities of the other organelles were unaltered by prednisolone administration. 3. There was a large increase in the total RNA content of enterocytes from the jejunum and ileum of prednisolone-treated animals. This was predominantly associated with a distinct particulate component, indicative of a proliferation of the rough endoplasmic reticulum and consistent with an enhanced rate of protein synthesis. 4. Studies of latent brush-border enzyme activities, the mechanical fragility of isolated brush borders and electron microscopy suggest that steroid administration results in no marked alterations in the gross conformation of the brush- border membrane or in the orientation of the enzymes within the membrane.

Analytical Subcellular Fractionation Studies on Enterocytes from the Jejunum and Ileum of the Rat and Some Properties of Brush-Border Alkaline Phosphatase

1978 ◽  
Vol 55 (2) ◽  
pp. 157-165
Author(s):  
R. M. Batt ◽  
T. J. Peters
Keyword(s):  
Alkaline Phosphatase ◽  
Brush Border ◽  
Subcellular Fractionation ◽  
Proximal Jejunum ◽  
Marker Enzymes ◽  
Brush Border Enzymes ◽  
Mechanical Disruption ◽  
Brush Borders ◽  
Mitochondrial Malate Dehydrogenase ◽  
Isopycnic Centrifugation

1. Enterocytes, isolated from the proximal jejunum and distal ileum of the rat, were homogenized and their organelles separated by isopycnic centrifugation on continuous sucrose density gradients. The distributions of marker enzymes for the principal organelles, RNA and protein were determined in the sucrose gradients and related to the activities per enterocyte. 2. In the jejunum the modal equilibrium densities of the various organelles were: brush borders (1.20), lysosomes (1.20), peroxisomes (1.19), mitochondria (1.17) and basal-lateral membranes (1.13). These values were not significantly different in the ileum. The activities of brush-border enzymes, soluble and mitochondrial malate dehydrogenase, soluble and membrane-associated lactate dehydrogenase and particulate protein content, however, were greater in the jejunal than the ileal enterocytes. 3. Detergent exposed latent alkaline phosphatase activity in jejunal enterocytes and indicated that this enzyme is present not only in the brush border but also in the basal-lateral membrane and soluble fractions of the cell. 4. Isolated jejunal brush-border preparations showed latent activities of both alkaline phosphatase and γ-glutamyltransferase whereas the activities of α-glucosidase and leucyl-β-naphthylamidase were not affected by detergent. Mechanical disruption of these preparations suggested the presence of two forms of alkaline phosphatase in the brush border and provides a technique to assess membrane fragility.

Different diuresis-dependent excretions of urinary enzymes: N-acetyl-beta-D-glucosaminidase, alanine aminopeptidase, alkaline phosphatase, and gamma-glutamyltransferase.

1986 ◽  
Vol 32 (3) ◽  
pp. 529-532 ◽  
Author(s):  
K Jung ◽  
G Schulze ◽  
C Reinholdt
Keyword(s):  
Alkaline Phosphatase ◽  
Brush Border ◽  
Excretion Rate ◽  
Urine Flow ◽  
High Intake ◽  
Brush Border Enzymes ◽  
Urinary Creatinine ◽  
Gamma Glutamyltransferase ◽  
Alanine Aminopeptidase ◽  
Brush Border Enzyme

Abstract We studied how much of the lysosomal enzyme N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30) and of the brush-border enzymes alanine aminopeptidase (EC 3.4.11.2), alkaline phosphatase (EC 3.1.3.1), and gamma-glutamyltransferase (EC 2.3.2.2) was excreted in urine over 8 h after a high intake of fluid (22 mL per kilogram of body weight). The hourly excretion of all four enzymes increased with the increasing urine flow rate. The excretion rate of the brush-border enzymes was more markedly influenced than that of N-acetyl-beta-D-glucosaminidase. By relating the enzyme excretion to urinary creatinine we could reduce the variability of brush-border enzyme output and could completely compensate for the effect of diuresis on the excretion of N-acetyl-beta-D-glucosaminidase.

scholarly journals Active Sugar Transport by the Small Intestine

1968 ◽  
Vol 52 (3) ◽  
pp. 482-494 ◽  
Author(s):  
Robert G. Faust ◽  
Mary G. Leadbetter ◽  
Regina K. Plenge ◽  
Alston J. McCaslin
Keyword(s):  
Small Intestine ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Sugar Transport ◽  
Initial Step ◽  
Inhibitory Effect ◽  
Glucose Binding ◽  
Brush Borders

Tris-disrupted and intact brush border membrane preparations from mucosa of hamster jejunum were capable of preferentially binding actively transported D-glucose in a similar manner. Density gradient centrifugation of the Tris-disrupted brush borders indicated that D-glucose was bound to a fraction containing the cores or inner material of the microvilli. The properties of this binding were examined with the Tris-disrupted brush border preparation. Actively transported sugars competitively inhibited preferential D-glucose binding, whereas no effect was observed with nonactively transported sugars. Neither actively nor nonactively transported amino acids affected D-glucose binding. D-Glucosamine, which is not actively transported, was inhibitory to preferential D-glucose binding as well as to the active transport of D-glucose by everted sacs of hamster jejunum. No inhibitory effect was observed with the same concentration of D-galactosamine. Preferential D-glucose binding was also inhibited by sulfhydryl-reacting compounds, Ca2+, and Li+ ions. On the other hand, Mg2+ was shown to be stimulatory and Na+, NH4+, and K+ had no effect on this phenomenon. The results of these experiments suggest that preferential D-glucose binding to brush borders is related to the initial step in active sugar transport by the small intestine.

scholarly journals The Influence of Peptidases in Intestinal Brush Border Membranes on the Absorption of Oligopeptides from Whey Protein Hydrolysate: An Ex Vivo Study Using an Ussing Chamber

Foods ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1415
Author(s):  
Luísa Ozorio ◽  
Caroline Mellinger-Silva ◽  
Lourdes M. C. Cabral ◽  
Julien Jardin ◽  
Gaelle Boudry ◽  
...  
Keyword(s):  
Whey Protein ◽  
Brush Border ◽  
Ex Vivo ◽  
Protein Hydrolysate ◽  
Ussing Chamber ◽  
Proximal Jejunum ◽  
Peptidase Activity ◽  
Ex Vivo Model ◽  
Brush Border Enzymes ◽  
Whey Protein Hydrolysate

For many years, it was believed that only amino acids, dipeptides, and tripeptides could be absorbed and thus reach the bloodstream. Nowadays, the bioavailability of oligopeptides is also considered possible, leading to new research. This pilot study investigates the activity of brush border enzymes on undigested whey protein hydrolysate (WPH) and on simulated intestinal digested (ID) whey hydrolysate and the subsequent absorption of resultant peptides through the proximal jejunum of a 7-week old piglet setup in an Ussing chamber model. Amongst all samples taken, 884 oligopeptides were identified. The brush border peptidase activity was intense in the first 10 min of the experiment, producing several new peptides in the apical compartment. With respect to the ID substrate, 286 peptides were detected in the basolateral compartment after 120 min of enzyme activity, originating from β-lactoglobulin (60%) and β-casein (20%). Nevertheless, only 0.6 to 3.35% of any specific peptide could pass through the epithelial barrier and thus reach the basolateral compartment. This study demonstrates transepithelial jejunum absorption of whey oligopeptides in an ex vivo model. It also confirmed the proteolytic activity of brush border enzymes on these oligopeptides, giving birth to a myriad of new bioactive peptides available for absorption.

scholarly journals Evaluation of Met-Val-Lys as a Renal Brush Border Enzyme-Cleavable Linker to Reduce Kidney Uptake of 68Ga-Labeled DOTA-Conjugated Peptides and Peptidomimetics

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3854 ◽  
Author(s):  
Shreya Bendre ◽  
Zhengxing Zhang ◽  
Hsiou-Ting Kuo ◽  
Julie Rousseau ◽  
Chengcheng Zhang ◽  
...  
Keyword(s):  
Brush Border ◽  
Ex Vivo ◽  
Neutral Endopeptidase ◽  
Amide Bond ◽  
Detection Sensitivity ◽  
Brush Border Enzymes ◽  
Positron Emission ◽  
Brush Border Enzyme ◽  
Renal Brush Border

High kidney uptake is a common feature of peptide-based radiopharmaceuticals, leading to reduced detection sensitivity for lesions adjacent to kidneys and lower maximum tolerated therapeutic dose. In this study, we evaluated if the Met-Val-Lys (MVK) linker could be used to lower kidney uptake of 68Ga-labeled DOTA-conjugated peptides and peptidomimetics. A model compound, [68Ga]Ga-DOTA-AmBz-MVK(Ac)-OH (AmBz: aminomethylbenzoyl), and its derivative, [68Ga]Ga-DOTA-AmBz-MVK(HTK01166)-OH, coupled with the PSMA (prostate-specific membrane antigen)-targeting motif of the previously reported HTK01166 were synthesized and evaluated to determine if they could be recognized and cleaved by the renal brush border enzymes. Additionally, positron emission tomography (PET) imaging, ex vivo biodistribution and in vivo stability studies were conducted in mice to evaluate their pharmacokinetics. [68Ga]Ga-DOTA-AmBz-MVK(Ac)-OH was effectively cleaved specifically by neutral endopeptidase (NEP) of renal brush border enzymes at the Met-Val amide bond, and the radio-metabolite [68Ga]Ga-DOTA-AmBz-Met-OH was rapidly excreted via the renal pathway with minimal kidney retention. [68Ga]Ga-DOTA-AmBz-MVK(HTK01166)-OH retained its PSMA-targeting capability and was also cleaved by NEP, although less effectively when compared to [68Ga]Ga-DOTA-AmBz-MVK(Ac)-OH. The kidney uptake of [68Ga]Ga-DOTA-AmBz-MVK(HTK01166)-OH was 30% less compared to that of [68Ga]Ga-HTK01166. Our data demonstrated that derivatives of [68Ga]Ga-DOTA-AmBz-MVK-OH can be cleaved specifically by NEP, and therefore, MVK can be a promising cleavable linker for use to reduce kidney uptake of radiolabeled DOTA-conjugated peptides and peptidomimetics.

Evidence that L-sucrose is resistant to hydrolysis catalyzed by jejunal brush border enzymes

1982 ◽  
Vol 60 (5) ◽  
pp. 652-654 ◽  
Author(s):  
P. K. Dinda ◽  
I. T. Beck ◽  
Walter A. Szarek ◽  
George W. Hay ◽  
Edward R. Ison ◽  
...  
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Liquid Chromatograph ◽  
Brush Border Enzymes ◽  
Intestinal Brush Border Membrane ◽  
Intestinal Brush Border ◽  
Hydrolysis Of

The sucrase–isomaltase complex of the intestinal brush border membrane (BBM) catalyzes the hydrolysis of sucrose. The stereospecificity of this enzyme, however, is not known. To investigate this, BBM of hamster jejunum was incubated with D-sucrose or L-sucrose, and the reaction mixture was analyzed using a gas–liquid chromatograph. It was found that D-sucrose was hydrolyzed to its monomers, but L-sucrose remained unhydrolyzed. It is concluded that the sucrase–isomaltase of intestinal BBM of hamster jejunum does not hydrolyze L-sucrose and therefore this enzyme is stereospecific.

Subcellular Distribution of Hydrolase Activities for Glycine and Leucine Homopeptides in Human Jejunum

1978 ◽  
Vol 54 (2) ◽  
pp. 205-207
Author(s):  
J. A. Nicholson ◽  
T. J. Peters
Keyword(s):  
Brush Border ◽  
Subcellular Distribution ◽  
Brush Border Membrane ◽  
Specific Marker ◽  
Peptidase Activity ◽  
Small Peptides ◽  
Normal Human ◽  
Analytical Fractionation ◽  
Hydrolysis Of ◽  
Isopycnic Centrifugation

1. The subcellular distribution of peptidase activities in the normal human jejunum against glycine and leucine homopeptides has been investigated with an analytical fractionation technique. 2. An 8000 g-min supernatant was prepared from homogenates of Crosby capsule biopsy specimens and subjected to isopycnic centrifugation in a Beaufay automatic zonal rotor. 3. The distribution of subcellular organelles in the gradient was established by measurement of organelle-specific marker enzymes. 4. A sensitive fluorimetric assay for glycine peptidase was developed and used for the localization of peptidase activity with peptides composed of from two to five glycine residues as substrates. 5. Glycine peptidase activity was located in the cytosol and in the brush-border membrane but the distribution of activity varied markedly with the chain-length of substrate; the longer the peptide the greater the proportion of activity associated with the brush border. Leucine peptidase showed a similar variation in cytosol—brush border distributions. 6. The results are consistent with concepts that suggest absorption and intracellular hydrolysis of small peptides and brush-border digestion of larger peptides.

Effect of ethanol on disaccharidases of hamster jejunal brush border membrane.

1979 ◽  
Vol 237 (1) ◽  
pp. E68
Author(s):  
P K Dinda ◽  
R O Hurst ◽  
I T Beck
Keyword(s):  
Alkaline Phosphatase ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Kinetic Studies ◽  
Time Dependent ◽  
Acute Exposure ◽  
Dependent Manner ◽  
Brush Border Enzyme ◽  
Dose Dependent

This study was undertaken to investigate the effect of alcohol on the activity of jejunal disaccharidases (DS). The activity of DS in a preparation of purified brush border membrane of hamster jejunum was measured in the absence and in the presence (0.8 to 6.4% wt/vol) of ethanol. To compare the effect of alcohol on DS with its action on a brush border enzyme of a different group, we also measured the activity of alkaline phosphatase (AP) under similar conditions. Ethanol depressed the activity of sucrase, maltase, and lactase in a dose-dependent and time-dependent manner, but it stimulated the activity of AP. The ethanol-induced inhibition of DS was completely reversible. Kinetic studies indicate that ethanol depressed the Vmax and increased the Km of sucrase and lactase. The Vmax of maltase also decreased, but the Km of this hydrolase was not affected by ethanol. From the results of this study it would appear that acute exposure of the jejunal brush border to ethanol depresses the DS activity of the membrane and that (because the AP was not depressed) the ethanol-induced inhibition of DS is not the result of a general inhibition of all enzymes of the brush border.

Activity of brush border membrane enzymes in proximal jejunum of portal hypertensive rats

2001 ◽  
Vol 36 (6) ◽  
pp. 407-409 ◽  
Author(s):  
Upjeet Kaur ◽  
Simran Kaur ◽  
Akhtar Mahmood ◽  
Navneet Agnihotri
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Proximal Jejunum ◽  
Hypertensive Rats ◽  
Membrane Enzymes ◽  
Brush Border Membrane Enzymes
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