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K Haffen

Publications and source records attributed to K Haffen.

At least 55 records · Page 3Linked to original sources
PubMed1982

Control of brush border enzymes by dexamethasone in the fetal rat intestine cultured in vitro.

The effect of dexamethasone (DX) on the prenatal maturation of rat intestinal brush border enzymes was studied in organ culture. Jejunal segments were explanted daily from day 17 of gestation until birth, as well as at different postnatal stages until day 6; they were cultured for 48 h with or without DX (8 X 10(-8) M). Enzymatic activities were analyzed on brush border membranes purified from cultured intestines and were compared with values from uncultured specimens. The results showed that DX elicited (a) a precocious induction of sucrase activity in the jejunum explanted from 19 days of gestation onward, reaching a peak value when taken at birth; (b) a stimulation of maltase activity in the segments explanted as soon as day 18, leading to maximal values when taken at day 20, the stage at which the stimulated activity reached a 6.5-fold increase over the baseline activity; and (c) an increase of lactase activity comparable to that occurring in utero. As opposed to this, DX has no specific action on alkaline phosphatase and aminopeptidase activities. The present data indicate that glucocorticoids directly and specifically influence the prenatal maturation of some brush border enzymes in the mammalian gut.

Alkaline Phosphatase↗
PubMed1982

Modifications of brush border enzyme activities during starvation in the jejunum and ileum of adult rats.

Aminopeptidase, lactase and sucrase activities have been followed during 5 days in the jejunum and in the ileum of starved adult rats. Enzyme activities have been determined in the mucosal homogenates as well as in the purified brush border membranes and expressed as activities per intestinal length (segmental activities) or as activities per milligram of protein (specific activities). The segmental and specific activity of aminopeptidase was increased in the ileum during the first 2 days of starvation, suggesting that aminopeptidase may have during the first days of starvation a conservative role by preventing an important loss of tissue protein. In all conditions, lactase activity was strikingly enhanced by starvation whereas sucrase activity showed no changes or decreased activity. Lactase stimulation was initiated during the first 24 h of starvation reaching its maximum after 2 days. The various experimental conditions leading to a specific or to a nonspecific stimulation of intestinal lactase activity have been discussed.

Animals↗
PubMed1981

[Permissive effects of human colonic cancer (HT-29 and Caco-2) on intestinal smooth muscle differentiation].

Human colonic carcinoma cells (lines HT-29 and Caco-2) were associated with 5 1/2 day-old chick embryonic intestinal mesenchyme and grafted for 11 days into 3 day-old Chick embryos. In these conditions, the cancer cells exert on the mesenchyme a supportative effect leading to its differentiation into muscular layers. The results provide additional evidence that HT-29 and Caco-2 cells exhibit common properties to fetal and normal intestinal cells.

Animals↗
PubMed1981

Organogenetic potentialities of rat intestinal epithelioid cell culture.

The aim of the present study was to investigate the mesenchymal influence on cultured epithelioid cells originating from an already differentiated intestine. Epithelioid cell cultures of 6-day-old suckling rat intestine were established by sequential trypsinizations of the mucosa. Embryonic intestinal monolayers of quail cells (13 days) were used as control because of their natural cell marker. Six to thirty days after plating, both types of epithelioid cells were associated in heterospecific combination with 5 1/2-day-old chick embryonic small intestinal mesenchyme, after removal of the endoderm by collagenase treatment. In order to test the differentiation capabilities of the associations, they were grafted for 10-12 days into 3-day-old chick embryos. The results show that in such an in vivo culture system, the chimeric associations gave rise to well differentiated intestinal structures indicating that the epithelioid cell cultures derived from late embryonic or neonatal intestine will go through organotypic differentiation when recombined with an appropriate mesenchyme.

Animals↗
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↗
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

[Islet cell transplantation and diabetes (author's transl)].

It is now apparent that transplantation of islet cells is biologically feasible in experimental animals utilizing adult neonatal or fetal islet cells and employing many different sites for implantation of the islet cells. It is reasonable to expect that with successful acquisition of new basic information in immunology, endocrinology, metabolism and developmental biology islet cell transplantation should be used as a therapeutic approach to human diabetes.

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↗
PubMed1979

Turnover studies of human intestinal brush border membrane glycoproteins in organ culture.

Turnover in organ culture of human small intestinal membrane glycoproteins was measured by the pulse-chase technique, using 14C-glucosamine, 14C-fucose or 14C-leucine as tracers. Apparently, low degradation rates were found for the major high-molecular-weight proteins which co-migrated on SDS-polyacrylamide gels with maltase-glucoamylase, lactase-phlorizin-hydrolase and sucrase-isomaltase enzymic activities. In contrast, an unidentified glycoprotein appearing on gels next to alkaline phosphatase exhibited a higher degradation rate with an apparent half-life of about 30 h, this being similar to the half-life of total glycoprotein as measured in mucosal homogenates. The results obtained with the pulse-chase technique were confirmed by double isotope experiments using 14C-leucine and 3H-leucine as tracers. These findings indicate that in organ culture there is a low basic turnover of human intestinal membrane glycoproteins which co-migrate on gels with known glycosidase enzymic activities.

Cell Membrane↗
PubMed1979

Chick embryo pancreatic transplants reverse experimental diabetes of rats.

The effectiveness of xenogeneic embryonic tissue in the treatment of experimental diabetes has been investigated in rats. The splenic lobes (80) of 15- to 18-d-old chick embryos, composed almost exclusively of endocrine tissue, were implanted directly into the hepatic parenchyma of the rat recipient. The biochemical and metabolic changes in the recipients suggest that embryonic transplants of 15-d-old chick pancreases were able to significantly improve, for a prolonged period of time (18 mo), the diabetic state of nonimmunosuppressed rats. None of the recipients of 18-d-old embryos splenic lobes exhibited a long-term improvement of the diabetic state after transplantation. The complete destruction of the pancreatic B cells of the recipients was assessed by: (a) immunocytochemical investigations of the recipient's pancreas, (b) measurement of insulin in the liver and pancreas of the recipients and (c) in situ vascular perfusion of their pancreas submitted to high glucose challenge. The results suggest that pancreatic tissue of the 15-d-old embryos is immunologically immature lacking one or several lymphocyte subsets implicated in the afferent lood of "non-self" recognition.

Animals↗