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Biomedical subjects

F Raul

Publications and source records attributed to F Raul.

At least 109 records · Page 6Linked to original sources
PubMed1981

Comparative in vivo and in vitro effect of mono- and disaccharides on intestinal brush border enzyme activities in suckling rats.

Suckling rats were bottle fed during 48 h with a basic diet enriched with different mono- or disaccharides. In parallel, explants of intestinal mucosa were cultured in vitro for 48 h in the presence or in the absence of a synthetic glucocorticoid (dexamethasone) and with or without different carbohydrates. In both studies, enzyme activities were assayed on purified brush border membranes. From these combined in vivo and in vitro investigations it appeared that (1) there is a highly specific stimulation of mono- and disaccharides on the corresponding brush border disaccharidases: glucose, fructose, sucrose on sucrase and maltase activities, fructose being generally the most potent activator. Other brush border enzymes were not modified by the dietary carbohydrates. (2) These sugar-mediated effects were obtained only in the presence of glucocorticoids. This hormone alone induced the appearance of a slight sucrase activity and provoked a stimulation of maltase activity. The results show clearly that glucocorticoids are necessary to induce sucrase activity, but that the level of this activity is under the strict dependence of the dietary carbohydrates.

Alkaline Phosphatase↗
PubMed1981

Modified protein kinase activity and isozyme distribution in adenocarcinoma of the human colon.

Protein kinase activity and histone kinase isozyme distribution have been determined in soluble extracts of adenocarcinoma of the human colon and compared to adjacent normal mucosa. The results show an enhancement in endogenous protein kinase activity and the presence of an additional isozyme (PKI) for histone kinase activity in the tumour tissue. PKI activity exhibited a peculiar behaviour in comparison to the isozyme. PKII present in both carcinoma and normal mucosa after dialysis of the soluble extracts. It is suggested that alteration of intracellular regulatory processes involved in PKI activity might be related to the maintenance of the proliferate state in human colon carcinoma.

Adenocarcinoma↗
PubMed1980

Effect of sucrose refeeding on disaccharidase and aminopeptidase activities of intestinal villus and crypt cells in adult rats. Evidence for a sucrose-dependent induction of sucrase in the crypt cells.

In order to gain more insight into the adaptative mechanism of intestinal enzymes to dietary factors in rats, modifications in the activities of disaccharidases and aminopeptidase were measured after refeeding of a 70% solution of sucrose for 15 h following a 2-day fast. Mature epithelial cells from the villus and immature cells from the crypt were isolated after sequential removal of the cells along the villus-crypt axis. Synthesis of brush border disaccharidases was determined by measuring [3H]valine incorporation into proteins. 1. In the whole mucosa, a highly significant increase in sucrase and maltase activities and a significant drop in aminopeptidase activity was observed in the brush border membranes after sucrose refeeding. 2. Stimulation of sucrase and maltase activities in sucrose refed rats was produced mainly in the immature cells of the crypt and lower villus compartment. 3. After separation of the brush border proteins by SDS gel electrophoresis from villus and crypt cells of sucrose refed rats, major incorporation of the radioactive precursor occured in the protein bands corresponding to sucrase and maltase activities of the lower villus and crypt cell brush borders. These findings demonstrate that sucrase stimulation by sucrose occurs mainly in the immature epithelial cells and that the substrate induces de novo synthesis of sucrase molecules.

Animals↗
PubMed1979

Developmental pattern of rat intestinal brush-border enzymic proteins along the villus--crypt axis.

At various postnatal stages, intestinal epithelial cells were isolated sequentially from villus tip to crypt base by successive EDTA treatments. According to the localization of marker enzymic activities, isolated cells were pooled into three cell compartments: villus (V), lower villus and upper crypt (VC) and crypt (C). Purified brush-border-membrane proteins were separated by 7.5%-polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. Enzymic activities could be assigned to some protein bands: maltase/glucoamylase (protein band 3), sucrase-isomaltase (protein bands 3 and 6), lactase (protein band 5) and alkaline phosphatase (region of protein bands 8 and 9). The findings suggest the following. (1) Sucrase-isomaltase activities appeared in compartment C at 17 days with a simultaneous increase of the pre-existing protein band 3 and appearance of a well-defined protein band in position 6; the enzymic complex remained still present in the crypt cells until adulthood. From the day 21 onwards, sucrase-isomaltase was detected in compartments VC and V. (2) Lactase was only present in the three cell compartments until day 21; at this developmental stage its activity completely disappeared from compartment C, in spite of the persistence of a weak protein band. (3) Alkaline phosphatase activity could be detected as a single peak corresponding to protein band 9 in all three cell compartments until day 21; thereafter it was replaced by two peaks of activity showing a less precise correlation with the well-defined protein bands 8 and 9. In the crypt cells of the adult rat, however, the preweaning situation, which was regularly observed, is an unexpected phenomenon. (4) Maltase and glucoamylase did not display any marked qualitative or quantitative modifications either along the villus-crypt axis or during the period of postnatal development studied. Evidence is given from the present data that each brush-border enzyme investigated has a specific developmental pattern.

Age Factors↗
PubMed1978

Hormonal stimulation of intestinal brush border enzymes release.

The rat small bowel was perfused in vivo and ex vivo in the absence of biliary and pancreatic secretion. Intraluminal release of sucrase, alkaline phosphatase, aminopeptidases and enterokinase was significantly increased after administration of pentagastrin, caerulein and glucagon at doses ranging between 1 pg and 10 microgram. This suggests that there is a direct hormonal stimulation of the intestinal mucosa. This effect might at least partly be mediated through cyclic AMP since dibutyryl derivates of this cyclic nucleotide exerted a significant stimulatory effect on intraluminal release of proteins, sucrase and enterokinase, although the pattern of enzyme was quite different from the effect produced by the three peptides.

Alkaline Phosphatase↗
PubMed1978

Sucrase and lactase synthesis in suckling rat intestine in response to substrate administration.

The intestinal brush border disaccharidases separated by gel electrophoresis were studied after oral administration of a high sucrose or lactose diet to 11-day-old suckling rats during 3 days. Some modifications of the brush border protein and eyzyme patterns could be attributed to the effect of the basic diet: increase of glucoamylase, appearance of a weak sucrase activity and of a second molecular form of maltase. However, the specific action of a given disaccharide on the synthesis of the corresponding hydrolytic enzyme could be clearly demonstrated. Indeed, the electrophoretic pattern after sucrose or lactose feeding showed a marked increase of the protein bands corresponding to sucrase-isomaltase or lactase activities.

Administration, Oral↗
PubMed1978

Separation and characterization of intestinal brush border enzymes in adult rats and in suckling rats under normal conditions and after hydrocortisone injections.

Adult and suckling (13 days old) rat intestinal brush borders have been purified by the procedure of Schmitz et al. (25). Enzymatic proteins have been separated by polyacrylamide gel electrophoresis. In the adult rat, enzyme proteins have been separated by polyacrylamide gel electrophoresis. In the adult rat, enzyme activities in order from the origin were: maltase/glucoamylase/sucrase-isomaltase (protein band 3), lactase (protein band 5), maltase/sucrase-isomaltase (protein band 6) and alkaline phosphatase (protein bands 8 and 9). In the suckling rat, protein band 5 associated with lactase activity was found to be markedly higher compared to the adult rat. Gels were completely devoid of sucrase-isomaltase activity while protein band 3 was strikingly reduced and protein band 6 absent. After hydrocortisone administration to suckling rats, a new band associated with sucrase-isomaltase activity appeared in position 6, whereas protein band 3 markedly increased with the simultaneous appearance of sucrase-isomaltase activity.

Aging↗
PubMed1977

Intestinal enzymes activities in isolated villus and crypt cells during postnatal development of the rat.

A modification of Weiser's (1973) cell isolation method was used in order to study the developmental pattern of various intestinal enzyme activities in villus and crypt cells of normal rats from 5 days after birth until 8 weeks. Alkaline phosphatase and enterokinase activities were always located in the upper villus zone during postnatal development. Enterokinase activity was higher in the upper villus cells during the third week of life than after this period. Aminopeptidase activity was located in the crypt cells during the first week, its maximum activity remained in this area until the third week. At this time, sucrase activity appeared in the crypt cells, then aminopeptidase and sucrase activities rose to the villus zone during the fourth week. Amylase activity was detected along the entire crypt-villus axis 5 days after birth, reaching maximum activity in crypt cells at the end of the first week and in the upper villus cells after the fourth week. In contrast with the other enzymes studied almost all amylase activity was soluble in the youngest animals whereas at weaning most of the activity appeared in a particulate form in the villus cells. But in the crypt cells the ratio between particulate and soluble form remained unchanged until the adult stage. Various hypotheses are advanced to explain the patterns of evolution of the different enzymes.

Alkaline Phosphatase↗
PubMed1977

Ex vivo vascular perfusion of the isolated rat small bowel. Importance of the intestinal brush border enzyme-release in basal conditions.

The vascular perfusion of the whole isolated intestine of the rat with homologous non-diluted blood is compared with classical in vivo experiments. During a 2 1/2-hour perfusion procedure no significant difference was noted between the two experimental schedules as far as haemodynamic, histological, mechanical and/or electrical activities of the gut are concerned. However, striking changes in the intestinal brush border enzyme output within the lumen appear between ex vivo and in vivo experiments. The early increase of intraluminal intestinal sucrase, already after the 95th min of perfusion indicate clearly the existence of a subcellular damage even not detectable by other tests of viability. Therefore, it is suggested that release of brush border enzymes might represent an interesting criterion of viability of in vitro or ex vivo preparations.

Alkaline Phosphatase↗
PubMed1975

[Effect of puromycin, nalidixic acid and cycloheximide on neuromuscular transmission].

The action of puromycin, nalidixic acid and cycloheximid on neuromuscular transmission has been assayed using diaphragm-phrenic nerve preparation from rat. The results demonstrate that all antibiotics used, reversibly blodk neuromuscular transmission. Cycloheximid seems to act presynaptically by inhibiting acetylcholine release from nerve terminal. Puromycin and nalidixic acid act as curare-like agents. They seem to compete with acetylcholine for fixation at the cholinergic receptor.

Animals↗
PubMed1975

[The effect of puromycin, nalidixic acid, and cycloheximide acetylcholinesterase purified from Electrophorus electricus L].

The action of puromycin, nalidixic acid and cycloheximide on acetylcholinesterase has been studied using an "electrophoretically pure" preparation. Results obtained show that these well known inhibitors of protein synthesis have an inhibitory effect on acetylcholinesterase activity. The inhibitory action exercised by puromycin and nalidixic acid is of a mixed inhibition type, similar to the one seen when decamethonium and d-tubocurarine are used as inhibitory agents. Cycloheximide acts in a non competitive way on the enzyme activity.

Cycloheximide↗
PubMedDate not supplied

Sucrase and cellular development.

The cellular changes that take place as the intestinal cell migrates from crypt to villus are morphologically and biochemically remarkable. It is fortunate that many of these phenomena can be delineated by following enzymic activities. Sucrase-isomaltase is a particularly fascinating enzyme complex because it is a marker of the differentiated cell. Sucrase is inducible with steroids and protected by the substrate sucrose. Purified enzyme can be used to stimulate production of specific antibodies in goats; these antibodies have been used as probes to locate enzymically active and inactive antigen in the cells of the crypt and villus respectively. Further examination of the enzyme has indicated a molecular weight of 200 000--350 000. These higher molecular weight components are located in the brush border of the enterocytes. Lower molecular weight subunits are antigenically active and are in the cytosol. It is assumed that these smaller components are enzymically inactive pre-combination subunits of the sucrase-isomaltase complex and that the sucrase-isomaltase of the brush border is an aggregate of these subunits. The California sea lion, which is deficient in intestinal sucrase activity, does have isomaltase activity. This finding supports the concept that there are different gene complexes for sucrase and for isomaltase.

Aging↗