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Biomedical subjects

G Mazzacca

Publications and source records attributed to G Mazzacca.

At least 91 records · Page 5Linked to original sources
PubMed1989

Release of diamine oxidase into plasma by glycosaminoglycans in rats.

Plasma diamine oxidase (DAO) values are enhanced by intravenous injection of heparin which releases the enzyme, synthesized in small bowel enterocytes, from binding sites located on endothelial cells of the intestinal microvasculature. Intestinal DAO, in analogy with lipoprotein lipase (another heparin-released enzyme), is believed to be electrostatically linked to endothelial binding sites composed of a glycosaminoglycan (GAG) which is presumably heparan sulphate, but the complete mechanism of enzyme release is not known. In this study we assayed in rats the DAO-releasing capability of heparan sulphate, dermatan sulphate, chondroitin sulphate A and hyaluronic acid, all heparin related compounds. Heparan sulphate, a compound with the same hexosamine as heparin but with a lower concentration of sulphated iduronic acid, induced a very high release of DAO (3-fold less than heparin), while the other tested GAGs, composed of higher proportions of non sulphated uronic acid and with galactosamine instead of glucosamine, induced a significantly lower release. In rats treated with 60 mg heparan sulphate the significant decrease in ileal mucosal DAO activity indicates that, in analogy with heparin, the high plasma enzymatic activity induced is of enterocytic origin. It is suggested that the high charge density of the compounds tested, due to the degree of sulphatation, is the decisive factor in promoting the release of intestinal DAO.

Amine Oxidase (Copper-Containing)↗
PubMed1989

[The 75-seleno-homocholic acid-taurine test (SeHCAT). A useful method for detecting the idiopathic malabsorption of bile salts in chronic functional diarrhea].

The 75-SeHCAT test has been used for identifying, within a group of patients with chronic functional diarrhea, a subgroup of cases with ileal bile acid malabsorption. Thirty-four subjects were studied: 10 healthy subjects and 24 patients with chronic functional diarrhea. Findings are expressed as percentage of basal abdominal radioactivity after 7 days. Normal values in our control subjects were: over 25% on day 4 and over 10% on day 7. Pathological results were found in 9 of 24 patients (37.5%) on day 4 and of 24 patients (41.7%) on day 7. A significant correlation was found between the percentages of retention on days 4 and 7 (p less than 0.001). In SeHCAT-positive patients cholestyramine administration led to clinical improvement. According to our experience, the SeHCAT test is a useful tool for the evaluation of bile acid malabsorption in the differential diagnosis of chronic functional diarrhea.

Adult↗
PubMed1989

Modifications in enterocyte diamine oxidase distribution induced by heparin in the rat.

Heparin releases diamine oxidase (DAO) of enterocytic origin from binding sites located on small bowel microvascular endothelium. In the villus tip enterocytes the enzyme is found in organelles (about 60%) and in cytosol (about 40%), while a negligible activity is present in the brush border. In this study we assessed the changes in DAO distribution into the enterocytes induced by a high dose of intraperitoneal heparin (1000 IU) in the rat, by assaying DAO activity on subcellular fractions obtained from ileal mucosa homogenate. Heparin injection induced a marked reduction of enzyme activity in the S2 fraction (cytosol): after 30 min less than 20% of DAO activity is still found and only 8% after 150 min. In the P1 fraction (organelles) DAO activity significantly decreased only after 60 min and a further consistent reduction was recorded after 150 min. Recovery of DAO activity was complete 4 days after the injection, though it was already clearly evident in the first 2 days. These results indicate that enterocytic DAO is distributed in two different compartments: DAO located in the cytosol is quickly released by heparin, while the organelles-linked enzyme is more slowly released. The finding that recovery in DAO activity happens earlier in the P1 fraction suggests that the enzyme supplies the cytosol after being synthesized in the enterocyte organelles.

Amine Oxidase (Copper-Containing)↗
PubMed1989

Ornithine decarboxylase and diamine oxidase in human colon carcinoma cell line CaCo-2 in culture.

The human colon carcinoma cell line CaCo-2, grown in vitro under standard culture conditions and in the absence of differentiation inducers, spontaneously exhibits structural and functional characteristics of mature small bowel enterocytes. Differentiation is complete at late confluency. High activities of ornithine decarboxylase and diamine oxidase are present in enterocytes. Although these enzymes are involved in polyamine metabolism and therefore in cell replication, their function in small bowel epithelium remains to be defined. In this study ornithine decarboxylase and diamine oxidase activities were assessed in CaCo-2 cells at different stages of proliferation and differentiation. Diamine oxidase was also assayed in spent culture media to assess its spontaneous release by CaCo-2 cells. The trigger effect of medium replacement on ornithine decarboxylase activity was also investigated. Cell growth and cell cycle kinetics were determined by hemocytometric cell count and [3H]thymidine labeling index. Sucrase activity was assayed to evaluate brush-border functional maturation. Elevated ornithine decarboxylase activity was recorded during the replication phase (highest value 0.3 +/- 0.02 U/mg) characterized by high thymidine labeling index (43%), and was greatly enhanced by medium replacement (2.1 +/- 0.3 U/mg). Diamine oxidase activity was low in both cells and medium during the active phase of cell growth, and during the differentiation period it progressively increased (highest value 499 +/- 78 U/mg) along with sucrase activity. The high diamine oxidase activity recorded in the medium (highest value 1292 +/- 310 U/ml) and the evidence of diamine oxidase secretion through the basolateral membrane of the cells cultured on porous filters support the hypothesis of an extracellular role of intestinal diamine oxidase. The CaCo-2 cell line, which shows several analogies with small bowel enterocytes, can be proposed as an interesting in vitro model for studying many aspects of cell replication and differentiation depending on polyamine metabolism.

Amine Oxidase (Copper-Containing)↗
PubMed1989

Human serum transglutaminase and coeliac disease: correlation between serum and mucosal activity in an experimental model of rat small bowel enteropathy.

Transglutaminase (TG) activity is increased in the mucosa of patients with coeliac disease. Among 18 patients with untreated coeliac disease we have found a significant decrease (p less than 0.001) in serum levels of TG activity (0.72 (0.23) mU/ml). There was no significant differences between 16 treated coeliacs (1.24 (0.28) mU/ml) and 30 normal controls (1.63 (0.42) mU/ml). To evaluate the connection between serum and mucosal TG activity we used the experimental model of methotrexate induced acute hypoplastic enteropathy in the rat. Transglutaminase activity was unchanged in serum and mucosa 24 and 48 hours after MTX administration, but increased in mucosa (2.606 (0.95) v basal 0.207 (0.026) mU/mg protein, p less than 0.001) and significantly decreased in serum at 72 hours (2.08 (0.38) v basal 5.56 (1.50) mU/ml, p less than 0.001) during intestinal cell proliferation. Activity of the enzyme in the mucosa and serum returned to baseline levels within 120 hours. This experimental animal model helps to explain the data of TG activity in human intestinal mucosa and serum reported in this study. Results are mean (SD).

Animals↗
PubMed1989

Behaviour of transglutaminase activity in intestine of starved and refed rats.

Starvation causes an intestinal mucosa atrophy which is greater in jejunum than in ileum. Hypoplasia is promptly reversed by refeeding. Transglutaminase (TG) has been controversially implicated in cell proliferation and its role in intestine is not defined. We investigate, by the above described model, the behaviour of TG in proximal and distal small bowel as well as in colon of rats after 4 days of starvation and at day 1, 2, 3, 4, 5, 7 and 10 of refeeding. Our results emphasize a significative reduction of TG in small bowel induced by starvation (day 0) and a prompt recovery of the enzyme activity after refeeding; furthermore, in the first intestinal tract TG activity reaches from day 2 to day 5 values which are significantly higher than basal. Four days of starvation do not affect TG in colon. In conclusion, our study demonstrates that in rats high values of TG activity are coincident with the intense proliferative phase in small intestine subsequent to starvation atrophy.

Animals↗
PubMed1988

Postheparin plasma diamine oxidase in patients with small bowel Crohn's disease.

Diamine oxidase (DAO) is an enzyme located almost exclusively in villus tip enterocytes of mammals. Its plasma activity, normally very low, is enhanced by intravenous heparin, which releases the enyzme from small bowel enterocytes into the blood. Plasma postheparin DAO (PHD) values have been shown to be significantly reduced in patients with malabsorption and villous atrophy and inversely correlated with 24-h fecal fat, thus suggesting that PHD reflects the mature enterocytic mass. We have assayed PHD in 51 patients with small bowel Crohn's disease by measuring the area under the plasma DAO curve over a 120-min period after an intravenous bolus of 15,000 IU of heparin. Postheparin plasma DAO was significantly lower (p less than 0.001) in patients (328 +/- 175 U/ml.min) than in 20 normal subjects (508 +/- 101 U/ml.min; range, 391-749). Postheparin diamine oxidase values were inversely correlated with Crohn's disease activity index (CDAI), but no correlation was found with extent of disease assessed radiologically by either double-contrast small bowel enema or barium meal follow-through. In 6 patients with active disease (CDAI, 297 +/- 99) and low PHD values (188 +/- 100 U/ml.min), the assay was repeated after a clinically effective course of antiinflammatory drugs. A significant increase in PHD values (388 +/- 112 U/ml.min) was observed (p less than 0.005). These data indicate that mucosal involvement is common in small bowel Crohn's disease and that PHD may be useful in assessing and monitoring mucosal damage in these patients.

Adult↗
PubMed1988

Postheparin plasma diamine oxidase in subjects with small bowel disease. Diagnostic efficiency of a simplified test.

Diamine oxidase (DAO) is an enzyme located almost exclusively in the villus tip enterocytes of mammals. Its plasma activity, normally very low, is enhanced by intravenous heparin that releases the enzyme from the enterocytes into the blood. Postheparin plasma DAO (PHD) values have been shown to be significantly reduced in patients with malabsorption and villus atrophy and in patients with Crohn's disease, thus suggesting that this test explores the mucosal integrity. The execution of the PHD test requires 8 blood samples over a period of 120 min after an intravenous injection of 15,000 IU of heparin, and then the calculation of the area under the curve. The aim of this study was to simplify the test and make it more acceptable by choosing only one of the eight curve points required for the calculation of the area under the curve and then assessing its discriminant power in different small bowel diseases. To this end, a discriminant analysis was performed on PHD curves of 16 normal subjects, 25 patients with celiac disease, 14 patients with treated celiac disease, 5 patients with diffuse primary small bowel lymphoma, 4 patients with small bowel lymphoma during treatment, and 55 patients with small bowel Crohn's disease. Plasma DAO values assayed 1 h (T60) after the injection of 15,000 IU of heparin proved to be the best discriminator curve point and the use of the T60 point alone may be usefully employed instead of the area under the 120-min curve.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Transglutaminase activity along the rat small bowel and cellular location.

A recent report indicates a relationship between human transglutaminase (TG) jejunal mucosa activity and celiac disease. We investigated the enzyme distribution along six consecutive small bowel segments of mucosa and tested TG activity on brush border membranes obtained from whole mucosa homogenate in Wistar rats. TG activity was significantly present in jejunal mucosa even if mostly detected in the distal part of small intestine. Our study indicates highest enzymatic activity in the subcellular fraction containing organelles and cellular membranes (66.8%) while a 7% activity was associated with the brush border fraction.

Animals↗
PubMed1988

Tripotassium dicitrate bismuthate and ranitidine in duodenal ulcer. Healing and influence on recurrence.

One hundred patients were entered into a double-blind, double-dummy comparison of tripotassium dicitrate bismuthate (TDB) versus ranitidine, to evaluate short-term healing rates, and successfully healed patients were then entered into a follow-up phase to observe relapse rates. At 4 weeks 84% of patients treated with TDB and 68% of those treated with ranitidine had healed. At 8 weeks these figures had risen to 96% and 90%, respectively (p = NS). After a year's follow-up study 84% of patients healed initially with ranitidine had relapsed, whereas in the case of patients healed initially with TDB the relapse rate was 67% (p less than 0.05). The results confirm that in the short term, TDB is as effective as ranitidine, whereas the significantly better protection against relapse offered by TDB compared with ranitidine underlines the importance of restoring mucosal defence, an approach that to date has been somewhat overlooked.

Adult↗
PubMed1987

Postheparin plasma diamine oxidase in subjects with small bowel mucosal atrophy.

Diamine oxidase (DAO) is an enzyme whose low plasma values are enhanced by an intravenous injection of heparin, which releases the enzyme from the enterocytes of the villous tips. In 20 normal controls and 15 untreated subjects affected with an overt malabsorption syndrome and subtotal atrophy shown by Crosby jejunal mucosa biopsy (12 suspected celiac disease and three small bowel lymphoma), plasma diamine oxidase was assayed, over 2 hr following an intravenous bolus of 15,000 IU heparin. Plasma postheparin DAO concentrations and the corresponding values of the area under curve, expressed as units/ml X min (mean +/- SD), were significantly lower in the patients (celiac sprue: 138 +/- 62; lymphoma: 83 +/- 42) compared to normals (481 +/- 104). DAO area values were well correlated (r = 0.81; P less than 0.001) with 24-hr fecal fat excretion but not with xylosuria. Our data suggest that postheparin plasma DAO assay may be useful to detect and quantitate small bowel mucosal atrophy in patients with malabsorption syndromes.

Adolescent↗
PubMed1987

Postheparin plasma diamine oxidase increases in patients with coeliac disease during gluten free diet.

An intravenous injection of heparin releases diamine oxidase (DAO) from villous tip enterocytes. In a previous study, we found that postheparin plasma DAO (PHD) values were significantly lower in patients with malabsorption syndrome and small bowel atrophy at jejunal biopsy than in normal subjects. In this study we performed the PHD test in 14 coeliac patients before and after three and six months of gluten free diet to show whether the enterocytes maturing processes induced by the diet joined with enhanced PHD values and to assess the clinical usefulness of this test. In all subjects jejunal biopsy carried out after six months showed a partial but consistent histological recovery. The clinical status, xylosuria and daily faecal fat excretion improved progressively and there was a significant increase (p less than 0.001) in mean PHD activity that reached the normal range after three months. After six months a further slight increase of the mean PHD value was recorded. These data indicate that PHD values rise together with the improved intestinal absorptive functions of coeliac patients on gluten free diet and that this test is a useful tool in monitoring recovery of the small bowel mucosa.

Adult↗
PubMed1987

Modifications in ornithine decarboxylase and diamine oxidase in small bowel mucosa of starved and refed rats.

Starvation followed by refeeding, which provides a model of intestinal adaptation characterised by proliferative and biochemical changes, was used to clarify the biological roles of ornithine decarboxylase (ODC) and diamine oxidase (DAO)--enzymes involved in polyamines metabolism. Ornithine decarboxylase and DAO were assayed in the proximal and distal small bowel mucosa of 55 rats, starved for four days and then refed. Rats (five per day) were killed after four days' starvation and at days 1, 2, 3, 4, 5, 6, 7, 8, 10 and 12 of refeeding. ODC, whose specific activity was similar in both intestinal segments, almost disappeared after starvation and showed a biphasic response during refeeding. High values were found on day 3 of refeeding in the proximal, and on day 4 in the distal small bowel; thereafter, they decreased gradually to be followed by a further significant increase during the last two days of the experiment. Diamine oxidase specific activity increased after starvation despite a very low total DAO activity in both intestinal segments. Refeeding induced a gradual recovery of DAO total activity. Diamine oxidase specific activity also reverted gradually to control values after five days of refeeding. These data confirm the prominence of ODC in the replication processes and suggest that intestinal DAO may not play a major role in enterocyte replication.

Adaptation, Physiological↗
PubMed1986

Metabolic fate of plasma diamine oxidase: evidence of isolated and perfused rat liver uptake.

After injection of an intravenous bolus of heparin (15,000 IU) in two groups of subjects, 10 normal volunteers and 6 subjects with external biliary drainage, blood and urine samples were collected; in the latter group bile samples were collected also. All samples were assayed for diamine oxidase (DAO). Persistently high values of this enzyme were found in plasma of both populations after heparin stimulation, while no increase in enzymatic activity was detected in bile and urine. In order to confirm and support the hepatic clearance of DAO, liver uptake of the enzyme derived from porcine kidney, human plasma and human placenta was studied by perfusion of isolated rat liver. Disappearance curves of the enzyme derived from three different sources showed a prompt liver uptake: activity decreased by about 50% in 10 min (endocytic uptake) and a slower but constant reduction during the remaining 110 min of perfusion was observed. These data suggest the hypothesis of liver metabolism of plasma DAO.

Adult↗