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J C Meslin

Publications and source records attributed to J C Meslin.

12 recordsLinked to original sources
PubMed1992

Intestinal mucosal morphometry and ileal epithelial renewal in conventional and germ-free rats fed an amylomaize starch diet.

Intestinal mucosal morphometry and ileal epithelial renewal were studied in conventional (CV) and germ-free (GF) rats fed either poorly digestible amylomaize or normal maize starch diets. Intestinal morphometry and position of labelled enterocytes were studied at various times after tritiated thymidine injection. With amylomaize starch diet, no difference was observed in the size of crypts (C), villi (V) and C + V between duodenum and jejunum both in CV and GF rats. In the ileum, however, values were significantly lower than those in the duodenum and jejunum. Furthermore, the presence of the microbial flora led to higher values when compared with GF values. Despite the morphological modifications in the ileum, no significant difference was detected in the labelled cell positions and epithelial renewal time between CV and GF values. This suggests that the resistant part of amylomaize starch was responsible for the modification in mucosal morphometry and the longer ileal epithelium renewal time in CV rats which then becomes similar to that in GF rats.

Amylopectin↗
PubMed1991

Effects of a low dietary linoleic acid level on intestinal morphology and enterocyte brush border membrane lipid composition.

The influence of low dietary linoleic acid level (an essential fatty acid deficiency) on the intestine mucosal morphology and the purified brush border membrane (BBM) lipid composition was investigated in the rat. Electron micrographs and morphometric measurements showed that villi and crypt sizes as well as the ultrastructure of epithelial cells were altered. Cholesterol (CHOL) and phospholipid (PL) levels, CHOL/PL ratio and PL class distribution were not changed by the low linoleate diet. However, the fatty acid composition of phospholipids was markedly modified in the enterocyte BBM, showing elevated amounts of palmitoleic (16:1n-7), oleic (18:1n-9) and 5,8,11-eicosatrienoic (20:3n-9) acids and, by contrast, depressed linoleic (18:2n-6) and arachidonic (20:4n-6) acid levels. Although the underlying mechanisms remain unknown the results obtained suggest that essential fatty acids (EFA) could be directly involved in the trigger action of the observed alterations, as regards both their dynamic (metabolic) and structural roles.

Animals↗
PubMed1991

Changes in small intestinal mucosa morphology and cell renewal in suckling, prolonged-suckling, and weaned lambs.

No information concerning the effect of weaning on intestinal cell proliferation is currently available in large species with early intestinal morphogenesis, a group including most domestic animals and humans. Changes in intestinal morphology and epithelial cell renewal were investigated in 1-, 5-, and 8-wk-old suckling and 8-wk-old weaned lambs after injection of [3H]thymidine. In suckling lambs a gradual increase in crypt depth occurred with age, especially in the proximal intestine, whereas villus height was significantly reduced in the distal regions. At 8 wk of age weaned and prolonged-suckling lambs exhibited no significant differences in crypt depth throughout the intestine and in villus height proximally. However, weaned lambs had shorter villi in the jejunum and ileum. The highest enterocyte migration rates (4.4-9.7 microns/h) were observed in 1-wk-old lambs. In suckling animals, migration rates decreased with age by 60, 51, and 11% in the duodenum, jejunum, and ileum, respectively. Weaned and prolonged-suckling 8-wk-old lambs had a similar rate of enterocyte migration in the ileum. Furthermore, ruminating animals exhibited only slightly higher migration rates in the duodenum and the jejunum (53 and 15%, respectively). In suckling lambs, epithelial cell renewal required 2.1-4.0, 4.5-6.3, and 4.0-5.3 days at 1, 5, and 8 wk of age, respectively, whereas labeled cells reached the tips of the villi within 3.0-3.1 days in weaned animals. These data suggest that the suckling period corresponds to a gradual and important phase of postnatal intestinal adaptation in the sheep, a species with early patterns of intestinal cell replacement.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[Decrease of the intestinal microflora without consequences for the morphometry and topography of the distal ileum in the mouse treated with antibiotics].

The aim of this study was to assess the possible modifications in the conventional intestine when deprived of its symbiotic microflora. The experiment was designed to study the effect of a heavy antibiotic dose on fecal microflora during the 33-d treatment period as well as its effects upon the intestinal wall. Conventional adult mice received either a casein-starch diet (conventional controls) or an antibiotic-supplemented (0.66% dry matter, DM) diet (treated conventionals); Furthermore, germ-free (axenic) mice taken from isolators to the open animal room received the same antibiotic-supplemented diet (treated axenics) Fecal microbial population remained around 10(8)/g in the conventional mice while it decreased to 10(3)/g in the treated conventional mice. Fecal microbial population of the treated axenic mice dropped to 10(2)/g. At the end of the 33-d treatment period, no significant difference in ileal villus height between the treated or control groups no difference either was seen in the aspects of the villus and cell surface as shown by scanning electron microscopy. In the control group, however, development of bacterial colonies exhibiting various shapes were observed on the intestinal mucus. Although it was found that antibiotic treatment was followed by significant changes in microbial population and biochemical composition of digestive contents, this study concluded that the structure of the distal ileal epithelium was not impaired.

Animals↗
PubMed1990

Histamine and mast cell distribution in the intestinal wall of the germ free and conventional rats. Influence of the mode of sterilization of the diet.

The influence of the mode of sterilization of the diet (gamma-irradiation vs. autoclaving) on the histamine and mast cells distribution in the intestinal mucosa, was studied in germ free (GF) and conventional (CV) rats. Interactions between the diet and the digestive microflora were observed. Histamine concentration and mast cells counts are higher in CV rats small intestine than in GF's. The differences are increased with the irradiated diet. At the opposite in the hindgut, these values are higher in GF than in CV rats, especially in the rats fed the steam sterilized diet. The variations in the wall histamine contents and in the mucosal mast cells counts due to the diet and/or the microflora do not appear to be always correlated.

Animals↗
PubMed1989

Evolution of the caecal epithelial barrier during Clostridium difficile infection in the mouse.

The most striking effect of Clostridium difficile infection is its degrading of the intestinal barrier. The aim of this study is to establish whether the cellular or paracellular constituent of the barrier is the initial target of the toxins produced by C difficile. Accordingly, the caecal epithelium of C3H/He mice was challenged under three experimental conditions with the C difficile strain VPI 10463: (1) by in vivo inoculation of axenic mice, (2) by adding the toxins to ligated caeca in vivo, and (3) by adding them to the mucosal side of isolated caeca in Ussing chambers. Under all three conditions, the epithelial barrier was tested in caeca mounted in these chambers. The transepithelial potential difference (PD), electrical conductance (G), and intact and degraded Horseradish peroxidase (HRP) fluxes were used as indexes of permeability. Results were as follows: (1) In axenic mice, C difficile caused severe infection, produced toxins A and B, reduced PD, and enhanced G and intact HRP fluxes without changing degraded HRP fluxes, (2) four hours after the toxins were added to ligated caeca in vivo, PD was relatively unaltered, but G, and intact and degraded HRP fluxes increased, and (3) when toxins were added to caeca during two hours in the Ussing chambers, the only modification observed was an increase in degraded-HRP fluxes. These results indicate that the C difficile toxins gradually cause intestinal lesions. After an apparent resistance, they stimulate the endocytotic process and then increase paracellular permeability and finally cause loss of cell viability.

Animals↗
PubMed1989

Epithelial cell migration on small intestinal villi in the neonatal rat. Comparison between [3H] thymidine and cytoplasmic labelling after Pu-citrate ingestion.

This study compares, in 2-d-old rats, the migration rates of epithelial cells on villi of the small intestine, using two labelling methods: a single [3H] thymidine injection; and cytoplasmic labelling by a single ingestion of Pu-citrate. Histoautoradiography showed negligible diffusion of Pu after the initial retention, which was mostly confined to the epithelial cells of the villi. However, after sloughing of labelled cells in the intestinal lumen, Pu was reabsorbed by the distal epithelial cells. In segments in which Pu reabsorption was negligible, the migration rates of Pu- and 3H-labelled cells were very close. These rates, expressed in micrometers, were almost constant along the length of the villus, and the Pu and 3H labelling edges reached the top of the villi in about 5 and 7 d, respectively. Once Pu retention had reached its maximum in 9 equal segments cut along the small intestine, tissue counting showed an exponential Pu release of 30-40%/d from each segment until the end of the experiment at d16. This constant release might reflect a constant cell migration rate during the period from Pu ingestion until d16.

Animals↗
PubMed1987

Intestinal absorption of macromolecules during viral enteritis: an experimental study on rotavirus-infected conventional and germ-free mice.

Epithelial transport and degradation of horseradish peroxidase (HRP), a macromolecular tracer, was studied in conventional and germ-free suckling mice following an experimental infection with rotavirus. Conventional and germ-free mice developed diarrhea from days 2 to 8 postinfection (pi), with growth failure. In mucosal homogenates, infectious virus detected by immunofluorescence on MA 104 cells was present from day 2 through day 8 pi in germ-free mice, but persisted longer (day 13 pi) in conventional mice. Only mild histological lesions were observed during diarrhea, but obvious macrovacuolation of epithelial cells and increased cellular density occurred during the convalescence period (days 9 to 13 pi). Intact and degraded HRP fluxes from mucosa to serosa were measured in vitro on segments of jejunum mounted in Ussing chambers. Both groups of mice developed increased HRP permeability during the experimental period, but at different times after inoculation: during the diarrheal period (days 2 and 3 pi) conventional mouse epithelium absorbed five times more HRP than noninfected controls and during the convalescence period (days 9 to 13 pi) HRP absorption in germ-free mice rose 10-fold as compared to its level before infection. In both cases, this increase in HRP permeability was entirely due to an increase in intact HRP absorption, probably via a transcellular route, and occurred without any alteration in degraded HRP transport. These results indicate that in mice, rotavirus infection causes a transient rise in gut permeability to undegraded proteins. The intestinal microflora seems to affect the timing, magnitude, and duration of this increased permeability.

Animals↗
PubMed1985

Histamine and mast cell distribution in the gastrointestinal wall of the rat: comparison between germ-free and conventional rats.

The distributions of histamine and mast cells in the intestinal mucosa have been studied in conventional (CV) and germ-free (GF) rats. Both distributions do not appear to be uniform throughout the gastrointestinal tract. The presence of digestive microflora influences these distributions: more histamine and mucosal mast cells are present in the small intestine of CV than in GF rats. Paradoxically the opposite is observed in the large intestine. Differences in mast cell counts in the crypt area of the small intestine (higher in CV than in GF rats) confirm the role of microflora on crypt cell proliferation due to a mild chronic inflammation. In the large intestine, however, the microflora appears to have a more complex influence and could act indirectly on histamine turnover.

Animals↗
PubMed1975

[Effect of dietary magnesium levels on cardiac lesions in rats fed a diet rich in rapeseed oil].

Cardiac lesions (histiocyte infiltration and fibrosis) obtained in rats fed rapeseed oil and 3 magnesium levels (high, low and normal) during 30 or 50 days are quantified by their size. Correspondence factorial analysis is used to compare the results. After 30 days, less cardiac lesions of histiocyte infiltration or fibrosis appear with rats fed a diet high in both rapeseed oil and magnesium than with normal or low magnesium diet. After 50 days, cardiopathogenic effects are less severe with normal magnesium diet than with the others (high or low). In both cases, more severe lesions are seen with low magnesium diet. It is concluded that magnesium overload in the diet does not protect against the cardiopathogenic effects of a diet containing high levels of rapeseed oil. Classical nephrocalcinosis and hypomagnesemia are seen with a low magnesium diet (70 ppm).

Animals↗