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At least 757 records · Page 42Linked to original sources
PubMed1997

Isolation of coccidian enteroepithelial stages of Toxoplasma gondii from the intestinal mucosa of cats by Percoll density-gradient centrifugation.

A method for isolation of enteroepithelial stages of Toxoplasma gondii from the intestinal mucosa of experimentally infected cats was developed using Percoll density-gradient centrifugation. Gamonts and merozoites were obtained essentially free of host-cell debris. A recovery rate of nearly 30% of the parasites in the original preparations was obtained by this method. Merozoites were separated from gamonts by filtration through a 3-micron polycarbonate filter.

Animals↗
PubMed1991

Apolipoprotein synthesis in normal and abetalipoproteinemic intestinal mucosa.

The genetic disease abetalipoproteinemia is characterized by a total absence of apolipoprotein B-containing lipoproteins from plasma. A presumed synthetic defect in apolipoprotein B synthesis was thought to be responsible for this disorder. The present study quantitates apoprotein B synthesis and apolipoprotein B messenger RNA levels in duodenal mucosa from normal patients and four patients with abetalipoproteinemia. After in vitro [3H]leucine incorporation, small intestinal biopsy specimens from three of four patients with abetalipoproteinemia synthesized immunoprecipitable apolipoprotein B of identical mobility (on sodium dodecyl sulfate gel electrophoresis) to normal apolipoprotein B. In abetalipoproteinemia, the apolipoprotein B content of intestinal mucosa by radioimmunoassay was 15% of normal mucosal values, whereas apolipoprotein B messenger RNA quantitation showed 3-20-fold increased levels compared with normal mucosa. In one patient, smaller-molecular-weight fragments of apolipoprotein B were immunoprecipitated from duodenal biopsy specimens. The synthesis rates and messenger RNA levels of two other chylomicron apoproteins (apolipoprotein A-I and apolipoprotein A-IV) were found to be reduced by 50%. These results show the synthesis of immunologically recognizable apolipoprotein B48 in abetalipoproteinemia. The significance of mucosal apolipoprotein B content in abetalipoproteinemia is discussed in terms of factors controlling apolipoprotein B synthesis in normal mucosa and in abetalipoproteinemia.

Abetalipoproteinemia↗
PubMed1975

Studies of intestinal lymphoid tissue. I. Electron microscopic evidence of 'blast transformation' in epithelial lymphocytes of mouse small intestinal mucosa.

The morphology of epithelial lymphocytes in osmium-fixed, Epon-embedded jejunum of adult mice was studied by light and electron microscopy. Toluidine blue-stained 1 mum 'thick' plastic sections were compared with adjacent thin sections, thereby permitting precise ultrastructural identification and description of selected epithelial lymphocytes. Their size and appearances varied considerably, ranging from typical small lymphocytes through medium-sized lymphocytes to large immunoblasts. A high proportion of medium-sized epithelial lymphocytes (mean diameter 6-9 +/- 1-1 mum) contained several lysosomes, extensive Golgi complexes, prominent centrioles and abundant ribosomes. Their appearances, therefore, corresponded directly to mitogen-stimulated lymphocytes. In contrast, immunoblasts were big cells (mean diameter 11-0 +/- 0-8 mum) with large, euchromatic nuclei and prominent nucleoli. The majority had pale-staining, ribosome-studded cytoplasm and thus resembled type I, or T blasts. Very rarely, densely staining blasts containing ribosomes and well developed rough endoplasmic reticulum were observed; these corresponded to type II or B blasts. These observations indicate that transformation of lymphocytes occurs within the interepithelial cell spaces of the small intestinal mucosa, suggesting that epithelial lymphocytes are immunocompetent cells which may be responsive to local antigenic stimulation.

Animals↗
PubMed2002

Protective effects of recombinant growth hormone on intestinal mucosa in rats receiving abdominal radiotherapy.

BACKGROUND AND AIMS: Radiation injury to the gut induces nutrient losses that compromise the body ability to adequately fight infection, heal wounds and recover from illness. Recombinant growth hormone (rhGH), is known to enhance anabolism, therefore, we tested the hypothesis that rhGH preserves whole body growth and trophism of the jejunum and ileum of irradiated rats. METHODS: After acclimatization period, the rats were divided in three groups: (1). control rats (C), (2). rats irradiated with a single dose of 10 Gy (group A); (3). rats irradiated with a single dose of 5 Gy (Group B); after irradiation, rats were given subcutaneously (sc) saline or 0.25 or 0.50 mg rhGH/kg BW/d for the following 6 days. Body weight changes were recorded during this time. On day 6 post-radiation, rats were killed and small intestine mucosa dry and wet weights were measured, as well as mucosa protein content. RESULTS: Group A rats lost body weight during the 6-day post-radiation period, regardless of rhGH treatment and dosage. rhGH was effective in preventing weight loss and normalizing growth in group B rats (saline 23.1+/-11.1, vs. controls P<0.05; rhGH: 35.0+/-10.0 g BW/d, vs. controls P = ns). Trophic effect of rhGH was observed on mucosa weight and mucosa protein content in rats irradiated with 5 Gy, but not in those receiving 10 Gy. CONCLUSION: rhGH seems to normalize growth and mucosa protein content in irradiated rats. However, rhGH beneficial effects were observed only in rats receiving the lower dose of radiation.

Animals↗
PubMed2000

Diverse patterns of expression of the 67-kD laminin receptor in human small intestinal mucosa: potential binding sites for prion proteins?

It has been shown that the 67-kD laminin receptor (LR) may function as a receptor for Sindbis and tick-born encephalitis viruses. Recent data indicate that the 37-kD precursor (LRP) for this molecule acts as a receptor for prion proteins (PrP), self-proteins implicated in the pathogenesis of transmissible spongiform encephalopathies including new variant Creutzfeldt-Jakob disease (nvCJD). Laminin and PrP share the same binding site on LRP, which is incorporated into the mature LR as a functional binding domain. To localize PrP binding sites potentially relevant to oral infection, the expression of the LR in human small intestinal mucosa was studied. Expression of the LR was determined by immunohistochemistry in duodenal and jejunal biopsies using a monoclonal antibody (MLuC5) which specifically recognizes the 67-kD LR. Biopsy material was obtained from 39 control patients, 15 patients with ulcerative colitis, 15 patients with Crohn's disease and uninvolved small bowel, and 28 patients with active coeliac disease. Two distinctive patterns of LR expression were found within each group of patients. One pattern was characterized by LR expression in the brush border and Golgi apparatus region of villus and crypt enterocytes. Paneth cell secretory granules were positive for LR in these samples. Brush border expression of LR was found in approximately 40% of samples, with the exception of Crohn's disease (6.7% of samples were positive). Another pattern of LR expression was characterized by positively stained endothelium, while the epithelium was generally negative (45 of 97). The use of two polyclonal antibodies which recognize both the LRP and the LR confirmed brush border and paranuclear expression of the LR, but also showed varying cytoplasmic and apical surface immunoreactivity in MLuC5-negative epithelium, reflecting the distribution of LRP as opposed to the mature receptor. In conclusion, expression of the LR in the brush border and in Paneth cell secretory granules suggests that this molecule might be involved in both secretory and endocytotic functions. The major implication of intestinal epithelial/brush border expression of the LR may be an increased susceptibility to oral infection with prion proteins.

Adult↗
PubMed1986

The effect of sodium deoxycholate given by gavage with heparin on the histology of the intestinal mucosa of the rat.

To gain direct insight into the mechanism of sodium deoxycholate (DOC)-induced enhancement of gastroenteral heparin absorption in rats, we performed light and electron microscopic examination of the mucosa of the small intestine of animals treated orally with DOC, heparin or DOC plus heparin. The sole morphological change observed after DOC and DOC plus heparin administration was a marked reduction in the length and distribution of glycocalyx filaments on the microvilli of epithelial cells. The morphological picture had reverted to normal after 24 h, when the promotion of enteral heparin absorption by DOC is greatly reduced. Thus, we suggest that DOC may promote the enteral absorption of heparin in rats by affecting some as yet unidentified barrier mechanism requiring glycocalyx integrity.

Animals↗
PubMedDate not supplied

[Structural characteristics of the small intestine mucosa of rats on diets with varying amounts of protein].

The small bowel mucosa of rats fed diets containing 4 and 35% of protein in terms of caloricity over 1 month demonstrated, as compared with control (18% of protein), alterations in the nuclei, in the degree of lymphoid infiltration, number of mitoses and gobiet cells in the epithelium, pointing to changes or impairment of maturation and differentiation of the cells of the epithelial layer. The degree of mucosa plasmatization was also discovered to be reduced as compared with control. The rearrangements in question attest to a decrease in the resistance of the mucosa. These rearrangements are more demonstrable in the intestine of rats which received low-protein diets, being far more pronounced in the distal parts.

Animals↗
PubMed1984

Fructose-1,6-biphosphatase activity in the intestinal mucosa of developing rats.

Fructose-biphosphatase (EC 3.1.3.11) activity was determined in the proximal and distal parts of the small intestinal mucosa of rats 1-30 days of age. Activity was found to increase to a maximum on about the 10th postnatal day and then to decrease. It was always higher in the proximal than in the distal portion of the gut. The enzyme showed a wide range of pH optimum around 7.0 and was inhibited by AMP. In 10-day-old rats activity determined 24 or 48 h after a single injection of cortisone or triiodothyronine was significantly decreased. This effect was no longer found for cortisone in 14-day-old animals. Weaning 18-day-old rats to a high-fat diet for 5 or 7 days delayed but did not prevent the usual decrease in activity seen at weaning.

Animal Population Groups↗
PubMed1976

Characterization, distribution and biosynthesis of the major ganglioside of rat intestinal mucosa.

The major sialic acid containing glycolipid has been isolated from rat intestinal mucosa. Characterization of this ganglioside by thin layer and gas chromatographic analysis indicates that it is an hematoside (GM3) with the major portion of the sialic acid in the N-glycolyl form. The distribution of this ganglioside was determined in villus and crypt cells isolated from rat intestine. The hematoside content of crypt cells was found to be significantly decreased when compared to villus cells. CMP-sialic acid:lactosylceramide sialyltransferase, responsible for the sialylation of lactosylceramide, was measured in differentiated villus and undifferentiated crypt cells and found to be greatly reduced in the crypt cell fraction. The present study demonstrates that marked differences in ganglioside content and biosynthesis occur in contiguous populations of cells in varying states of differentiation when isolated from normal rat intestine.

Alkaline Phosphatase↗
PubMed1985

Lymphokine-activated and natural killer cell activity in human intestinal mucosa.

The activity of natural effector (NE) cells was studied in lamina propria lymphocytes (LPL) obtained from 61 histologically normal specimens of human intestine, which included 45 resected for colon carcinoma and 16 resected for nonmalignant conditions. The mean spontaneous natural killer (NK) cell activity in LPL (1.7 X 10(2) cytotoxic units (C.U.)/10(5) cells) was very low in contrast to that found in peripheral blood mononuclear cells (PBMC) (38.5 X 10(2) C.U./10(5) cells). Significant NK activity was detected in only 16 (47%) of the tissues resected for carcinoma, and in five (38%) of those removed for nonmalignant conditions. Exposure to human leucocyte interferon resulted in only minimal increases in cytotoxicity for K562 target cells. Consistent with these findings, large granular lymphocytes represented less than 0.5% of freshly isolated LPL. Cultures of LPL from both carcinoma and nonmalignant conditions in MLA144-conditioned medium (CM), a source of interleukin 2 (IL 2), generated marked increases in cytotoxicity to levels comparable with or exceeding those found in PBMC. (Mean cytotoxicities were 90.4 X 10(2) and 49 X 10(2) C.U./10(5) cells, respectively.) Cytotoxicity induced by culture in MLA144-CM could be blocked by pretreatment of LPL with the monoclonal antibody anti-Tac directed against the IL 2 receptor. In addition, LPL cultured in recombinant human IL 2 were induced to levels of cytotoxicity that were similar to those induced by MLA144-CM. These data indicate that IL 2 is the factor in MLA144-CM responsible for generating lymphokine-activated killer (LAK) cells in LPL. The IL 2-activated LPL killer cells were OKT11+, OKT3-, Leu-7-, Leu-11b-, as determined by antibody and complement-mediated lysis, and the precursor cells in the lamina propria necessary for generation of killer cells by IL 2 were also OKT11+, OKT3-, Leu-7-, Leu-11b-. These studies indicate that LAK cells may be an important potential source of nonspecific cytotoxicity in the intestinal mucosa.

Carcinoma↗
PubMed1983

Inductive properties of fibroblastic cell cultures derived from rat intestinal mucosa on epithelial differentiation.

The present study represents a first attempt to elucidate the regulatory properties displayed by the non-epithelial portion of the intestinal mucosa, growing as fibroblasts in monolayer cultures. Thus, we compared the inductive action of 6-day suckling rat duodenal fibroblasts with that displayed by chick embryonic intestinal mesenchyme on the heterotypic cytodifferentiation of 5 1/2-day chick embryonic gizzard endoderm. The latter, isolated by 0.03% collagenase, was surrounded by intestinal intramucosal fibroblastic cell sheets. As control experiments, fibroblastic cells derived from the intestinal muscle or from 20-day fetal rat skin and lung were used. Every type of association was grafted into the coelomic cavity of 3-day chick embryos for 11 to 12 days, a system providing their vascularization and growth. The results clearly demonstrate that the mucosal fibroblastic cells of rat intestine were as potent as embryonic intestinal mesenchyme in inducing brush-border enzymes like sucrase and maltase, in conformity with an induced intestinal morphology. In contrast, the control fibroblastic cells were completely ineffective.

Alkaline Phosphatase↗