Brush Border Hydrolase Activities Research Articles

Structural changes induced by heating affect ovalbumin-antigen processing and reduce allergic response in mouse model of food allergy

Background Food allergy is a serious health concern affecting about 8% of young children and about 3% of adults. The egg protein ovalbumin belongs among six frequent food allergens. Our goal was to develop the mouse model of ovalbumin food allergy and investigate how thermal processing affects its ability to induce allergic responses. Methods Effect of thermal processing (70°C and 95°C) on an ovalbumin secondary structure was characterized by circular dichroism and by kinetics of pepsin digestion with subsequent HPLC analysis. BALB/c mice were sensitized intraperitoneally and challenged intragastrically with native form or thermal processed ovalbumin (70°C). Clinical symptoms (allergic diarrhea, weight and temperature) were observed during the mice challenging. Levels of allergen-specific serum antibodies were determined by ELISA (IgA, IgG1 and IgG2a) by beta-hexosaminidase release test (IgE). Cytokine production (IL-4, IL-5, IL-6, IL-10, IL-13, IL-17, IFN-gamma) and mast cell protease-1 activity were assessed by ELISA. The activities of brush-border hydrolases were determined in the jejunum of treated mice. Results Heating of ovalbumin caused slight irreversible changes in secondary structure and significantly decreased clinical symptoms (allergic diarrhea). The thermal processing also decreased immune allergic response on the level of IgE, IL-4, IL-5, IL-13. Furthermore, thermal-processed ovalbumin induced lower activities of serum mast cell protease-1 and enterocyte brush border membrane alkaline phosphatase as compared to native ovalbumin. On the other hand, thermal-processed ovalbumin stimulated higher IgG2a antibodies in sera and IFN-gamma secretion by splenocytes. Conclusion In our mice model of food allergy, we show that even a slight change in the secondary structure of ovalbumin after thermal processing reduces its allergenicity and induces shift towards Th1 immune responses. At present, we utilize this model for studying of food allergy in germfree mice.

Electroencephalography: Basic Principles, Clinical Applications, and Related Fields, Fifth Edition

Highly differentiated human proximal tubule (HPT) cells in primary culture were established from heterogeneous suspension of tubules prepared from the human renal cortex by an original two-step procedure. First, gluconeogenic-competent HPT cells were selected by using a hormonally defined serum-free medium without glucose or insulin; then, the selected HPT cells were grown in a medium containing a low concentration of glucose (1 mM) and insulin (0.5 micrograms/mL) but no antibiotics. HPT cells grown on plastic support formed confluent, cobblestone-like monolayers with numerous mitochondria and pinocytosis vacuoles, solitary cilia, junctional complexes, and a well-developed brush border consisting of densely packed microvilli. Compared with cell monolayers on plastic support, HPT cells grown on porous filter membranes showed better morphologic differentiation. HPT cell monolayers expressed the following differentiated functions of the proximal tubule in situ: a low-affinity, high-capacity Na(+)-dependent glucose transport system inhibited by phlorizin, a high-affinity Na(+)-dependent phosphate transport system, a basolateral organic cation uptake inhibited by mepiperphenidol, parathyroid hormone-sensitive cAMP synthesis, brush-border hydrolase activities, gluconeogenesis-associated enzymes, glutathione-S-transferases and N-acetyl-beta-D-glucosaminidase. The medium containing low glucose and insulin concentrations markedly limited the increase in glycolysis but did not prevent the falls in gluconeogenesis and brush-border hydrolase activity at any time of the culture period. Similar decreases of brush border enzyme activities were obtained for HPT cells grown either on plastic or on porous filter membrane. A thorough characterization study demonstrated that this simple and preparative experimental approach makes it possible to establish highly differentiated HPT cells in primary culture suitable for investigating human renal proximal tubular cell function.

Functional interaction of Escherichia coli heat‐labile enterotoxin with blood group A‐active glycoconjugates from differentiated HT29 cells

Human colon adenocarcinoma cells (HT29-ATCC) and the clone HT29-5F7 were cultured under conditions that differentiate cells to a polarized intestinal phenotype. Differentiated cells showed the presence of junctional complexes and intercellular lumina bordered by microvilli. Intestinal brush border hydrolase activities (sucrase, aminopeptidase N, lactase and maltase) were detected mainly in differentiated HT29-ATCC cells compared with the differentiated clone, HT29-5F7. The presence of non-GM1 receptors of Escherichia coli heat-labile enterotoxin (LT-I) on both types of differentiated HT29 cells was indicated by the inability of cholera toxin B subunit to block LT-I binding to the cells. Binding of LT-I to cells, when GM1 was blocked by the cholera toxin B subunit, was characterized by an increased number of LT-I receptors with respect to undifferentiated control cells. Moreover, both types of differentiated cells accumulated higher amounts of cyclic AMP in response to LT-I than undifferentiated cells. Helix pomatia lectin inhibited the binding of LT-I to cells and the subsequent production of cyclic AMP. LT-I recognized blood group A-active glycosphingolipids as functional receptors in both HT29 cell lines and the active pro-sucrase form of the glycoprotein carrying A-blood group activity present in HT29-ATCC cells. These results strongly suggest that LT-I can elicit an enhanced functional response using blood group A-active glycoconjugates as additional receptors on polarized intestinal epithelial cells.

Developmental regulation of intestinal epithelial hydrolase activity in human fetal jejunal xenografts maintained in severe-combined immunodeficient mice.

Intestinal epithelial brush border hydrolases are important and sensitive enzyme markers of gastrointestinal development and function. Little is know about the mechanisms that regulate the induction of these enzymes during human fetal development, as these events occur primarily in utero. The present work used ectopically grafted human fetal jejunal xenografts (median age,13.3 wk of gestation), maintained in severe-combined immunodeficient mice, to study the differential expression of five different hydrolases after 10 wk of xenotransplantation. The spatio-temporal distribution of brush border alkaline phosphatase, aminopeptidase-N, alpha-glucosidase, lactase-phlorizin hydrolase, and dipeptidyl peptidase IV enzyme activities were measured quantitatively using scanning microdensitometry along the crypt-villus axes of fetal, xenograft, and pediatric (median age, 34 mo) biopsies. Ectopic grafting of fetal jejunum closely recapitulated the development of these enzymes in utero, with alkaline phosphatase, aminopeptidase-N, alpha-glucosidase, and dipeptidyl peptidase IV enzyme activities closely matching the spatio-temporal distribution and levels recorded in pediatric duodenal biopsies. Lactase-phlorizin hydrolase was the only enzyme not to reach values recorded in pediatric brush border membranes, although activities were significantly (5.6-fold) higher than in pretransplanted fetal bowel. Human jejunal xenografts therefore demonstrate an appropriate developmental induction of brush border hydrolase activity and may represent a useful model to study trans-acting factors that promote human epithelial differentiation and function in vivo. Characterization of such agents may be of potential therapeutic use in the treatment of diseases associated with gastrointestinal immaturity, notably necrotizing enterocolitis.

Divergent phenotypic patterns and commitment to apoptosis of Caco-2 cells during spontaneous and butyrate-induced differentiation.

Caco-2 cells differentiate spontaneously when cultured in confluence and on exposure to the physiologically relevant short-chain fatty acid, butyrate. This study aimed to compare the phenotype induced by these pathways and their relations to cell turnover. Caco-2 cells were treated with butyrate at a nontoxic concentration of 2 mM for 3 days, or allowed to spontaneously differentiate for 0-21 days. Brush border hydrolase activities and carcinoembryonic antigen (CEA) expression, transepithelial resistance and dome formation, expression of components of the urokinase system, and cell turnover by flow cytometry, and the degree of DNA fragmentation were quantified. Butyrate induced increases in alkaline phosphatase activity and CEA expression but not the activities of other hydrolases, while culture alone induced progressive increases in the activities/expression of all markers. Butyrate induced a significantly greater increase in transepithelial resistance (TER) than occurred during culture alone but the densities of domes were similar. Butyrate induced a ninefold increase in urokinase receptor expression and twofold increase in urokinase activity, while culture alone induced a significantly smaller increase in receptor expression, an increase in plasminogen activator inhibitor-1 but no change in activity. While both stimuli induced cell cycle arrest, only butyrate increased the proportion of cells undergoing apoptosis. In conclusion, differentiation of Caco-2 cells can proceed along multiple pathways but does not necessarily lead to apoptosis. The phenotypic changes during spontaneous differentiation mimic those that occur in normal colonic epithelial cells in vivo during their migration from the crypt base to neck, while butyrate-induced effects more closely follow those occurring when normal colonic epithelial cells migrate from crypt neck to the surface compartment.

Relationship of hydrolase activities to epithelial cell turnover in distal colonic mucosa of normal rats.

The relationships between changes induced by diet in colonic epithelial kinetics and in the activities of brush border hydrolases are poorly defined. The aims of this study are to define these relationships, as changes in kinetics would be expected to influence differentiation, and to determine whether the type of ingested dietary indigestible carbohydrates influences hydrolase activities. Groups of eight rats were fed a low fibre diet +/- supplements of different types of indigestible carbohydrates for 4 weeks. Alkaline phosphatase (ALP) and dipeptidyl peptidase IV (DPPIV) activities and epithelial kinetics were measured in distal colonic mucosa. Median ALP activities correlated positively and DPPIV activity negatively with the median proportion of cells entering metaphase (r = 0.58 and -0.58, respectively; P < 0.05) and number of metaphase arrests per crypt column across the diets (r = 0.59 and 0.58, respectively; P < 0.05). Stepwise regression analysis showed that both hydrolases independently predicted these kinetic indices (R2 > 63% for each). Mucosal ALP activities were markedly elevated during consumption of raw potato starch, guar gum and methylcellulose, while only potato starch caused a significant elevation of DPPIV activities. The type of indigestible carbohydrate in the diet influences colonic mucosal hydrolase activities. The opposite relationship between kinetics and each of the two hydrolases indicates that these hydrolases do not reflect the same event; dipeptidyl peptidase IV might relate to differentiation status while ALP could also be influenced by epithelial irritation due to changes in luminal conditions.

Effect of butyrate on paracellular permeability in rat distal colonic mucosa ex vivo.

The effects of butyrate on colonic epithelial barrier function are poorly understood. The aim of this study was to examine the short-term effects of butyrate on paracellular permeability of rat distal colonic epithelium. Mucosa mounted in Ussing chambers was treated with butyrate (1-10 mmol/L) for 4 h. Transepithelial conductance, [51Cr]-EDTA flux, mucosal brush border hydrolase activity and epithelial kinetics, using proliferating cell nuclear antigen (PCNA) staining, were measured. On exposure to butyrate (10 mmol/L, but not 1 or 5 mmol/L), transepithelial conductance was 65 +/- 2% higher (mean +/- SEM; n = 8, P < 0.05, paired t-test) and the rate coefficient for [51Cr]-EDTA flux was 65 +/- 25% higher (P = 0.03) than those of control tissue. Histologically, the epithelium exhibited no signs of injury, but butyrate-treated tissue exhibited interstitial oedema consistent with water uptake in association with butyrate absorption. Butyrate caused a reduction in crypt column height to 30.6 +/- 1.6 cells from 33.4 +/- 1.8 cells in controls (n = 10, P < 0.03), but the number of cells per crypt column staining with PCNA was unchanged. Butyrate significantly reduced the mucosal activities of alkaline phosphatase by 40 +/- 16%, maltase by 54 +/- 12% and dipeptidyl peptidase IV by 41 +/- 14%. Acute exposure to butyrate increased paracellular permeability in rat distal colon. The mechanism involved may relate to the loss of differentiated surface epithelial cells, or as a physiological response to Na+-coupled butyrate uptake.

Modulation of distal colonic epithelial barrier function by dietary fibre in normal rats

BACKGROUNDDietary fibre influences the turnover and differentiation of the colonic epithelium, but its effects on barrier function are unknown.AIMSTo determine whether altering the type and amount of fibre in the...

A pancreatic extract-enriched diet corrects ileal mucosa atrophy in endotoxemic aged rats.

An altered adaptive response of the pancreas and small intestine to nutritional stress has an adverse impact upon nutritional status in elderly humans or senescent rats. We evaluated the effects of a pancreatic extract nutritional supplement on intestinal mucosa adaptation in LPS-treated aged rats. Endotoxemic rats were starved for 48 hr and then refed ad libitum for four days with a standard diet. Afterwards they received, over one week, the standard diet enriched with either pancreatic extract (PE) (2.4 g/day) or casein (isonitrogenous to PE supplement). Healthy aged rats fed ad libitum with a standard diet were studied in parallel. Whereas no changes occurred in the jejunal segment, an adaptive villus hyperplasia was observed in the proximal ileum of rats receiving PE without an increase in the brush border hydrolase activities. Our results indicate that oral PE supplementation exerts a trophic effect on the ileal mucosa of aged rats in response to nutritional stress.

Dietary modulation of colonic mucosal urokinase activity in rats.

The amount and type of dietary fibre ingested influences colonic luminal characteristics, especially the concentration of carbohydrate fermentation products such as butyrate. This study aimed to assess whether diets supplemented with fibres of differing fermentability (delivering different amounts of butyrate to the colon) influence mucosal activities of urokinase and brush border hydrolases, and epithelial turnover. Groups of five rats were fed one of four diets containing low (2%), highly fermented (guar 10% or oat bran 10%) or slowly fermented fibre (wheat bran 10%) for 4 weeks. Activities of urokinase, alkaline phosphatase, dipeptidyl peptidase IV and maltase were measured in mucosal homogenates of proximal and distal colon and from rectum. Proliferative kinetics were assessed in distal and proximal colon by the metaphase arrest technique. Hydrolase activities were similar across all four dietary groups but a significant difference was found for urokinase (P = 0.014). This was due to a reduction in urokinase activities of > 30% at the three sites in the wheat bran group compared with the other groups. Of proliferative indices, only crypt column height differed across the groups (P = 0.038) and was highest in rats fed wheat bran and lowest in those fed the low fibre diet (P = 0.047). The proportion of mitoses in the top one-fifth of the crypt also differed across groups (P = 0.038) due to the high values in the distal colon of the low fibre group. Thus, addition of a slowly fermented (but not highly fermented) fibre to the diet of rats reduces net urokinase activity in large bowel mucosa and increases the life span of colonic epithelial cells without changing activities of brush border hydrolases.

Consecutive use of hormonally defined serum-free media to establish highly differentiated human renal proximal tubule cells in primary culture.

Highly differentiated human proximal tubule (HPT) cells in primary culture were established from heterogeneous suspension of tubules prepared from the human renal cortex by an original two-step procedure. First, gluconeogenic-competent HPT cells were selected by using a hormonally defined serum-free medium without glucose or insulin; then, the selected HPT cells were grown in a medium containing a low concentration of glucose (1 mM) and insulin (0.5 micrograms/mL) but no antibiotics. HPT cells grown on plastic support formed confluent, cobblestone-like monolayers with numerous mitochondria and pinocytosis vacuoles, solitary cilia, junctional complexes, and a well-developed brush border consisting of densely packed microvilli. Compared with cell monolayers on plastic support, HPT cells grown on porous filter membranes showed better morphologic differentiation. HPT cell monolayers expressed the following differentiated functions of the proximal tubule in situ: a low-affinity, high-capacity Na(+)-dependent glucose transport system inhibited by phlorizin, a high-affinity Na(+)-dependent phosphate transport system, a basolateral organic cation uptake inhibited by mepiperphenidol, parathyroid hormone-sensitive cAMP synthesis, brush-border hydrolase activities, gluconeogenesis-associated enzymes, glutathione-S-transferases and N-acetyl-beta-D-glucosaminidase. The medium containing low glucose and insulin concentrations markedly limited the increase in glycolysis but did not prevent the falls in gluconeogenesis and brush-border hydrolase activity at any time of the culture period. Similar decreases of brush border enzyme activities were obtained for HPT cells grown either on plastic or on porous filter membrane. A thorough characterization study demonstrated that this simple and preparative experimental approach makes it possible to establish highly differentiated HPT cells in primary culture suitable for investigating human renal proximal tubular cell function.

Functional and metabolic changes in intestinal mucosa of rats after enteral administration of ornithine alpha-ketoglutarate salt.

Ornithine alpha-ketoglutarate salt efficiently improves the nutritional status of protein-depleted patients. Our aim was to explore the effects of ornithine alpha-ketoglutarate supplementation on intestinal physiology in healthy animals. Rats were given a nutritive mixture supplemented with ornithine alpha-ketoglutarate (1 g.kg-1 per day) by enteral route for 7 days. Controls received the diet supplemented with casein acid hydrolysate under isoenergetic and isonitrogenous conditions. An adaptive hyperplasia of the villi and an increase in the brush-border hydrolase activities were observed in rats receiving ornithine alpha-ketoglutarate. Because of the high ornithine aminotransferase activity, ornithine alpha-ketoglutarate-derived ornithine was extensively transaminated with a concomitant enhancement of ornithine decarboxylation. Surprisingly, with glutamate and putrescine, the products of ornithine transamination and decarboxylation, gamma-aminobutyric acid accumulated (10-fold to 16-fold) dramatically in the intestinal mucosa of rats treated with ornithine alpha-ketoglutarate. Because gamma-aminobutyric acid formation was completely prevented by the diamine oxidase inhibitor aminoguanidine but was not modified after inactivation of ornithine aminotransferase by 5-fluoromethylornithine, it is evident that gamma-aminobutyric acid is formed in the mucosa from ornithine via putrescine as an intermediate. It is assumed that enhanced gamma-aminobutyric acid formation in the intestinal mucosa by ornithine alpha-ketoglutarate treatment might be of physiologic importance in the regulatory processes of cell growth and differentiation.

Jejunal Brush Border Hydrolase Activity Is Higher in Tallow-Fed Pigs than in Corn Oil-Fed Pigs

We tested the effect of dietary fat on the lipid composition and hydrolase activity of jejunal brush border membranes in piglets. Eighteen 5-wk-old piglets were divided into three groups and for 4 wk fed either an unsaturated low fat diet (3.2% corn oil), an unsaturated high fat diet (17.2% corn oil) or a saturated high fat diet (2.2% corn oil + 15% tallow). Brush border membranes were prepared from the jejunal mucosa and analyzed for cholesterol, phospholipid and fatty acids. The activities of sucrase-isomaltase, lactase-phlorizin hydrolase, maltase-glucoamylase, aminopeptidase and alkaline phosphatase were measured. Lactase-phlorizin hydrolase isoforms were immunopurified and separated by SDS-PAGE, and their relative proportions were measured by densitometry. The activities of the disaccharidases and alkaline phosphatase, but not aminopeptidase, were greater in animals fed the saturated high fat diet than in animals fed the unsaturated high fat diet. The fatty acid composition of the membranes generally reflected the composition of the diet. Correlation analysis demonstrated that the phospholipid, fatty acid and cholesterol compositions of the membranes were associated with the differences in brush border hydrolase activity.

Effect of grape seed tannins on the activity of some rat intestinal enzyme activities.

The present study was designed to investigate the effects of grape seed tannins on rat intestinal alkaline phosphatase (AP), sucrase and dipeptidyl peptidase IV (DPP IV) activities. An experiment was performed in vivo by dietary supplementation with 2% tannins; this diet was tested on an experimental group of rats; a control group received a diet without tannins. After 31 days, tannins intake significantly decreased middle-jejunal AP from 123 to 45 mU/mg protein and sucrase activities from 310 to 195 mU/mg protein, while no significant difference appeared at the duodenal stage (p < 0.05). Ileal DPP IV activity was also significantly reduced (p < 0.05) from 190 to 110 mU/mg protein after tannin intake. Using in vitro experiments on purified brush border membranes, AP activity was found to be inhibited by grape tannins; this inhibition was prevented by the detergent Triton X-100. The addition of pancreatic-biliary (PB) juice to the incubation medium prevented or reversed the tannin-inhibited enzyme activity. The present data indicate that in the duodenal lumen, alkalinity and detergency from the PB secretion neutralized the ability of tannins to inactivate brush border hydrolase activities and suggest that enzyme inhibition took place once bile salts were reabsorbed while moving down the gut. This was confirmed by in vitro experiments where sucrase and DPP IV activities inhibited by grape seed tannins were largely recovered after the addition of PB juice to the incubation medium.

Selective regulation of epithelial gene expression in rabbit Peyer's patch tissue.

The physiological mechanisms that regulate epithelial gene expression during enterocyte migration and differentiation are still poorly understood. The present study has used a combination of quantitative in situ hybridisation, immunohistochemistry and enzyme cytochemistry to examine epithelial cell differentiation in rabbit small intestine. We have measured and compared the levels of mRNA and enzyme activity of the enterocyte brush border markers alkaline phosphatase, amino-peptidase N and lactase in normal villus epithelia and in epithelial cells exposed directly to the Peyer's patch immune environment. All three genes appeared to be expressed in parallel, but in each epithelial population examined, the pattern of gene expression was different. The level of these mRNAs was markedly reduced in Peyer's patch-associated epithelia, this being most pronounced in the follicle-associated epithelium, compared with normal villi. The activities of alkaline phosphatase and aminopeptidase N approximated the expression of their genes, whereas additional post-transcriptional events were shown to clearly contribute to the level of lactase activity in these tissues. These findings demonstrate that the reduced brush border hydrolase activity in Peyer's patch tissue that has been observed previously, is due to a down-regulation of epithelial gene expression in this location. These observations have been used to discuss epithelial differentiation in Peyer's patch tissue and the possible role of local immune factors in regulating such events.

Fetal mouse kidney maturation in vitro: Coordinated influences of epidermal growth factor, transferrin and hydrocortisone

We have investigated the individual and combined actions of epidermal growth factor (EGF), transferrin and hydrocortisone on the maturation of whole fetal mouse metanephroi maintained in serum-free conditions for up to 5 days. The presence of EGF (100 ng/ml) resulted in elevated levels of [3H]-thymidine incorporation when compared to controls; autoradiograms showed that the proliferation of mesenchymal cells in the nephrogenic zone is particularly enhanced as verified by cell counting. Brush border hydrolase activities (alkaline phosphatase and gamma-glutamyltransferase), on the other hand, were significantly diminished. Transferrin (5 micrograms/ml) slightly stimulated DNA synthesis and potentiated EGF mitogenic action. The activation of DNA replication by the growth factor seems to be mediated through the protein kinase C pathway. When added alone, hydrocortisone (10(-6) M) strongly inhibited DNA synthesis, stimulated hydrolase activities and exerted a positive effect on brush border differentiation. When combined with EGF or to EGF + transferrin, hydrocortisone counteracted the effects of these latter peptides on DNA synthesis and enzyme activities. Considering the earlier observation of a reciprocal relation between proliferation and differentiation during the neotubulogenic phase of kidney development, the results described in the current study suggest that synergistic and synarchic actions of these heterologous factors are involved in the regulation of tubulogenesis.

Age related increase of brush border enzyme activities along the small intestine.

Intestinal morphology and brush border hydrolase activities were determined along the small intestine of young adult (three months, n = 10), mature (12 months, n = 10), and senescent (29 months, n = 15) rats. The intestinal segments of the senescent rats contained higher mucosal mass and protein content (p less than 0.05) compared with the young and mature animals. A significant reduction of villus height and crypt depth (p less than 0.05) was found in the proximal intestine during aging. A 35% increase in villus height (p less than 0.05) without changes in crypt depth, was observed in the distal ileum in senescent rats. The activities of sucrase and isomaltase were significantly increased during aging in the duodenum and jejunum (p less than 0.05). Lactase and aminopeptidase activities which showed only minor changes between young and mature animals were significantly enhanced in senescent animals (p less than 0.05) with aminopeptidase exhibiting a three-fold increase in activity in the proximal ileum. The results when combined with those of previous studies suggest that in the aged animal, the increased level of intestinal hydrolase activities may be the consequence of prolonged cellular maturation along the villi in the proximal intestine, and of adaptation to increased concentrations of intraluminal substrates in the distal intestine.

Enhancement of maternal and fetal nephrotoxicity of salicylate by zinc deficiency. Morphological, enzyme histochemical and immunohistochemical studies.

An oral dose of 700 mg/kg salicylic acid was given to normal and Zn-deficient rats at day 16 of gestation. Maternal and fetal kidneys were studied at day 19 of gestation. Zn-deficiency did not cause any lesions detectable by semi-thin section light microscopy, electron microscopy, enzyme histochemistry and immunohistochemistry. Salicylate may lead only to small morphological, enzymatic and cytoskeletal defects in the maternal and fetal kidney. However, enzyme activities decreased in plasma membranes, mitochondria, lysosomes, endoplasmic reticulum and peroxisomes in all segments of the tubular apparatus when salicylate was given to Zn-deficient rats. Cytoskeletal proteins such as keratin in the glomerular cells and epithelial lining of the collecting ducts and vimentin in vascular endothelial cells of the maternal kidney were also affected. In addition, the epithelial cells of the collecting ducts, which were comparatively less damaged, accumulated high amounts of fat. In severe cases, the enzymatic and cytoskeletal lesions were accompanied by hematuria and tubular necroses including and collecting ducts in the renal papilla. In less severe cases reduced activities of brush border hydrolases were the only sign of disturbed renal function in maternal rats indicating that membrane alteration and loss of membrane-bound enzymes are the primary defects. In the fetal kidneys, mitotic activity of the cells of the nephron anlagen and collecting ducts was reduced and enzymatic and morphological differentiation were disturbed. As a consequence less mature nephrons and collecting ducts occurred.

Decreased Brush Border Hydrolase Activities without Gross Morphologic Changes in Human Intestinal Mucosa after Prolonged Total Parenteral Nutrition of Adults C. GUEDON, J. SCHMITZ, E. LEREBOURS, J. METAYER, E. AUDRAN, J. HEMET, AND R. COLIN Gastroenterology 90: 373–378, 1986

Decreased Brush Border Hydrolase Activities without Gross Morphologic Changes in Human Intestinal Mucosa after Prolonged Total Parenteral Nutrition of Adults C. GUEDON, J. SCHMITZ, E. LEREBOURS, J. METAYER, E. AUDRAN, J. HEMET, AND R. COLIN Gastroenterology 90: 373–378, 1986

SELECTIVE INHIBITION OF BRUSH BORDER HYDROLASE DEVELOPMENT IN COELIAC DISEASE (CD) AND COW'S MILK PROTEIN INTOLERANCE (CMPI)

Brush border hydrolase activities increase as enterocytes migrate from crypts towards villous tips. Recently this process has been studied at the cellular level using quantitative cytochemistry (1). This technique is now applied to alkaline phosphatase (AP), a-glucosidase (a-G), and lactase (L) developrrentt in controls (n=6), and children with CD (n=6) and CMPI (n=5).In controls AP, a-G, and L activities increased over the first 120 μm from the crypt-villous junction (142 to 270; 102 to 147; 78 to 138 absorbance units [AU] respectively)and changed little thereafter. The development pattern in CMPI was similar for AP (115 to 263 AU) but a-G & L levels were lower (49 to 100; 31 to 91 AU). The pattern of development in CD was again similar for AP (110 to 208 AU); a-G activity was initially low and the subsequent increase was reduced (48 to 84 AU); L activity remained low throughout (19 to 26 AU).Cells migrate more rapidly and have considerably shortened life spans in CD and CMPI yet they still manage to attain the same maximal AP activity, presumably through adaptation. The failure of enterocytes to respond in a similar way when expressing a-G and L probably represents a specific and selective disease-induced lesion.(1) Smith MW (1985) Ann Roy Physiol 47 247-260