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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Starvation overnight and starvation for 48 h reduced the weight and the protein content of mucosal scrapings, but only minimally reduced the DNA content of the mucosal scrapings. The activity of sucrase and maltase was reduced by both periods of starvation. The activity of lactase and of acid and alkaline phosphatase, however, was less subject to starvation. There were striking differences in the response to starvation between the proximal, mid and distal third of the small intestine. The importance of the proper reference system was discussed.
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PMID:Effect of starvation on small intestinal enzyme activity in germ-free rats. 10 66

Starvation for 48 hrs reduced the activity of sucrase referred to unit length in rat proximal small intestine by approximately 30%, irrespective of whe her mucosal scrapings, isolated villus epithelial cells or brush border membranes were investigated. Sucrase activity referred to unit weight, unit protein or to unit DNA of intestinal epithelium did not change.
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PMID:Starvation and sucrose activity in small intestinal mucosa. An evaluation of different tissue preparations and reference systems. 68 56

The activities of maltase and sucrase of the small intestine were low at night and high in the daytime in rats which had been fed from 09.00 h to 15.00 h for 2 weeks. A remarkable rise of enzyme activities was observed at 08.00 h, 1 h before the start of feeding. The rhythmic changes in disaccharidase activities continued for at least 2 days after starvation, but completely disappeared after 5 days of starvation. It was suggested that the disaccharidase rhythms are not a direct consequence of food intake, but that anticipation of food intake acts as a trigger for initiation of the disaccharidase rhythms.
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PMID:Circadian rhythms in disaccharidases of rat small intestine and its relation to food intake. 124 87

Glucose starvation has been widely used to select differentiated subpopulations from the heterogenous human colon cancer cell line HT29. We observed that the important cell loss elicited by culturing these cells in glucose-free medium could be limited when type I collagen gel was used as substratum instead of conventional plastic support. We took advantage of this property to develop a new protocol, which combined glucose starvation and culture on collagen gels, for cloning HT29 cells. Using this procedure we have isolated four clones that were characterized on the basis of morphological (optical and transmission electron microscopy), electrophysiological (determination of transepithelial electrical parameters) and biochemical (detection of villin, sucrase-isomaltase and carcinoembryonic antigen) criteria. These four clones expressed different patterns of enterocytic differentiation regarding to these criteria. These results confirmed the heterogeneity of the HT29 cell line. One of these clones, HT29-A7, which displayed numerous intercellular cysts that disappeared at confluency, appears as a complementary model in the study of epithelial biogenesis.
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PMID:Combination of culture on collagen gels and glucose starvation for cloning human colon cancer cells. Obtention of clones exhibiting different patterns of enterocytic differentiation. 136 54

In the rat, starvation lowers jejunal sucrase activity and increases or has no effect upon jejunal lactase activity. The mechanism by which starvation influences these intrinsic microvillus proteins remains unclear. Jejunal sucrase and lactase activities were studied during starvation or refeeding after a three-day fast. Using polyclonal monospecific antibodies, sucrase-isomaltase (SI) and lactase-phlorizin hydrolase (LPH) protein contents were measured in parallel to determine changes in enzyme activation. Sucrase activity and SI protein fell after two and three days of fasting and rose during refeeding. In contrast, lactase activity and jejunal LPH content increased after starvation and decreased after refeeding for 48 hr. For both enzymes, changes in catalytic activity and protein content occurred in parallel. [3H]Leucine incorporation studies in vivo showed more labeling of immunoprecipitable LPH than SI during starvation, but refeeding induced relatively more labeling of SI than of LPH. Therefore, starvation and refeeding produce opposing effects upon jejunal lactase and sucrase activities by modulating LPH and SI protein production and not by modifying enzyme activation.
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PMID:Effects of starvation and refeeding on jejunal disaccharidase activity. 158 86

The effects of long-term starvation on the activities of sucrase, lactase, and aminopeptidase, and on their respective mRNA were determined in the small intestine of thyroidectomized and sham-operated adult rats. Thyroidectomy reduced the protein loss at the level of the intestinal brush border membranes during starvation. Prolonged fasting caused a significant decrease in sucrase activity, but thyroidectomy partly prevented this effect. However, the amount of the corresponding mRNA dropped during long term starvation without incidence of thyroidectomy. Lactase activity in the brush border membranes was increased by starvation, and thyroidectomy caused a further elevation of the enzyme activity. Simultaneously, lactase mRNA content rose only slightly compared to the enzyme activity. Aminopeptidase activity and mRNA content decreased during starvation and thyroidectomy did not prevent this process. These results indicate that intestinal hydrolases respond non-coordinately to long-term food deprivation. In addition, the thyroid status of the animals has a direct influence on the adaptation of several brush border hydrolases to starvation. This suggests that the drop in plasma thyroid hormones during fasting allows a better maintenance of protein content and of hydrolase activities in the brush border membranes of the small intestine. These adaptive processes seemed to be partly controlled at a post-transcriptional level.
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PMID:Adaptation of intestinal hydrolases to starvation in rats: effect of thyroid function. 193 43

The clonal cell line HT29-D4 is able to differentiate by two different ways: i) by replacing glucose by galactose in the culture medium; ii) by addition of suramin (a drug known to interfere with the growth promoting activity of growth factors) in the medium. In both cases the transition in the organization of the cell monolayer occurred without cell loss. The two ways (i.e., glucose starvation or suramin addition) lead to polarized cells which generate electrically active cell monolayers (Fantini et al., Biol. Cell 65, 163-169 (1989) and this paper). Yet several important differences can be observed at the morphological or at the electrophysiological levels. 1) The suramin-treated cells (HT29-D4-S cells) organized into monolayers of high (40-50 microns) columnar cells while glucose-starved cells (HT29-D4-Gal cells) were rather cuboidal (20-25 microns). 2) HT29-D4-S cells were highly polarized; the nucleus was rejected at the basal side of the cell and lysosomes in the upper part of the cytoplasm. Numerous lipid-like droplets surrounded with glycogen were observed underneath the nucleus. HT29-D4-Gal cells never presented such a degree of organization. 3) The transepithelial resistance and the potential difference of HT29-D4-S monolayers reached values significantly higher than those for HT29-D4-Gal monolayers, reflecting a higher degree of organization. Specific proteins such as sucrase-isomaltase, alkaline phosphatase and carcinoembryonic antigen were localized exclusively on the apical membrane while human lymphocyte antigen (HLA) class I molecules were restricted to the basolateral membrane for both HT29-D4-S and HT29-D4-Gal cells. The present data demonstrate that the same cells can generate a different degree of cellular organization according to the experimental conditions of cell growth, the most elaborate state of differentiation being obtained in the presence of suramin.
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PMID:Suramin-treated HT29-D4 cells grown in the presence of glucose in permeable culture chambers form electrically active epithelial monolayers. A comparative study with HT29-D4 cells grown in the absence of glucose. 232 32

The effects of starvation (72 h) and refeeding with three liquid diets, differing only in the molecular form of the nitrogen source (whole whey proteins, WP; tryptic whey protein hydrolysate, WPH; and amino acid mixture, AAM), on the jejunal mucosal morphology and brush border enzyme activities (sucrase, S; maltase, M; and neutral aminopeptidase, NA) of male Wistar rats were studied. All three diets produced repair of the fasting-induced mucosal atrophy; the WP diet gave the most rapid growth with maximum villus height (VH) and protein content after 48 h (p less than 0.01). AAM gave the fastest and greatest stimulation of sucrase and maltase activities (p less than 0.01). There were no significant differences in NA activity. In control rats the WPH and AAM diets produced significantly greater villus height and disaccharidase activities than did the WP diet. Jejunal morphology and disaccharidase activities can be modified by the molecular form of alimentary protein and nutritional status interferes with these modifications.
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PMID:Dietary whey proteins and their peptides or amino acids: effects on the jejunal mucosa of starved rats. 264 93

The effects of starvation on intestinal disaccharidase activities and disaccharide absorption were studied in rats. Adult male rats were starved for either 16 or 72 h and the specific activity of lactase and sucrase was determined together with the absorption of lactose, sucrose, and glucose in vitro by the everted sac technique. The specific activity of lactase was significantly higher and the specific activity of sucrase was lower in the 72-h starved animals when compared with the 16-h starved group. The higher specific lactase activity in the 72-h starved animals was reflected in enhanced absorption of lactose as determined by the transfer of the constituent monosaccharides into the serosal fluid. The transfer of glucose into the serosal fluid by the glucose sac was also higher in the 72-h starved rats but not to the same extent as that of lactose. The absorption of sucrose was not significantly different between the two groups of animals. This study shows that the increase of intestinal lactase activity induced by starvation of adult rats correlates with in vitro increased lactose absorption.
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PMID:Dependency of lactose absorption on lactase activity in starved rats. 313 Jan 73

Effects of diet, hibernation and seasonal variations on hydrolase activities were determined in mucosa and purified brush border membranes of the small intestine of European hamsters. Wild hamsters captured in April and fed for several weeks with an equilibrated laboratory chow (20% protein, 50% carbohydrates) exhibited a rise in disaccharidase activities (sucrase, isomaltase, lactase) but no changes in aminopeptidase N activity. During deep hibernation, in contrast to sucrase and isomaltase activities which showed only minor changes, lactase activity was significantly enhanced along the jejunoileum, and aminopeptidase N activity was maximum in the ileum. After a short period (48 h) of wakefulness and feeding following 10 days of starvation during the hibernation period, the activities of the disaccharidases and of aminopeptidase N returned to values measured in active animals. In contrast to the nutritional state, which has an important impact on the activities of intestinal enzymes, season has little effect on the intestine of the active animal under a controlled environment. The pattern of enzyme activities which occurs along the small intestine in the hibernating animal may be a prerequisite for optimum digestion during the short phases of waking during the hibernation period of the European hamster.
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PMID:Adaptation of intestinal enzymes to seasonal and dietary changes in a hibernator: the European hamster (Cricetus cricetus). 317 Aug 22


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