Biomedical subjects

M Zareie

Publications and source records attributed to M Zareie.

7 recordsLinked to original sources

PubMed2006

Probiotics prevent bacterial translocation and improve intestinal barrier function in rats following chronic psychological stress.

BACKGROUND AND AIMS: Chronic psychological stress, including water avoidance stress (WAS), induces intestinal mucosal barrier dysfunction and impairs mucosal defences against luminal bacteria. The aim of this study was to determine the ability of a defined probiotic regimen to prevent WAS induced intestinal pathophysiology. METHODS: Male rats were subjected to either WAS or sham stress for one hour per day for 10 consecutive days. Additional animals received seven days of Lactobacillus helveticus and L rhamnosus in the drinking water prior to stress and remained on these probiotics for the duration of the study. Rats were then sacrificed, intestinal segments assessed in Ussing chambers, and mesenteric lymph nodes cultured to determine bacterial translocation. RESULTS: All animals remained healthy for the duration of the study. Chronic WAS induced excess ion secretion (elevated baseline short circuit current) and barrier dysfunction (increased conductance) in both the ileum and colon, associated with increased bacterial adhesion and penetration into surface epithelial cells. Approximately 70% of rats subjected to WAS had bacterial translocation to mesenteric lymph nodes while there was no bacterial translocation in controls. Probiotic pretreatment alone had no effect on intestinal barrier function. However, WAS induced increased ileal short circuit current was reduced with probiotics whereas there was no impact on altered conductance. Pretreatment of animals with probiotics also completely abrogated WAS induced bacterial adhesion and prevented translocation of bacteria to mesenteric lymph nodes. CONCLUSION: These findings indicate that probiotics can prevent chronic stress induced intestinal abnormalities and, thereby, exert beneficial effects in the intestinal tract.

Animals↗

PubMed2001

Monocyte/macrophage activation by normal bacteria and bacterial products: implications for altered epithelial function in Crohn's disease.

Intestinal immune cells are less reactive than those in the peripheral blood; however, such cells from patients with Crohn's disease may be more responsive to bacterial products. Our study examined if nonpathogenic bacteria or lipopolysaccharide (LPS), can affect epithelial function in the presence of monocytes/macrophages. Lamina propria mononuclear cells (LPMCs) and peripheral blood monocytes (PBMs) were obtained from patients with Crohn's disease and control patients. Filter-grown T84 epithelial monolayers were co-cultured with nonactivated or LPS-activated LPMCs or PBMs for 48 hours. Epithelial secretory [baseline short-circuit current (Isc) and DeltaIsc to forskolin] and barrier (transepithelial electrical resistance) parameters were measured in Ussing chambers. LPS-activated PBMs from both controls and patients with Crohn's disease significantly increased Isc ( approximately 300%) and reduced transepithelial electrical resistance ( approximately 40%). Epithelial function was not altered after co-culture with control LPMCs +/- LPS. However, LPMCs from patients with Crohn's disease spontaneously secreted tumor necrosis factor-alpha, and induced epithelial changes similar to those produced by LPS-activated PBMs. Co-culture with control Escherichia coli and PBMs induced comparable changes in epithelial physiology, which were abrogated by anti-tumor necrosis factor-alpha antibody. We conclude that LPMCs of patients with Crohn's disease are spontaneously activated, possibly by gram-negative luminal bacteria, and can directly cause significant alterations in epithelial ion transport and barrier functions.

Adolescent↗

PubMed2001

Rat models in peritoneal dialysis.

BACKGROUND: It is widely accepted that the currently used dialysis solutions are not biocompatible with the peritoneal membrane. Therefore, animal studies have been performed to study different aspects of peritoneal dialysis. However, representative models mimicking the human situation are not yet available. METHODS: The effect of a single injection of peritoneal dialysis (PD) fluid on the cellular composition was studied. Thereafter, the effect of a single injection of PD fluid on bacterial clearing was tested over time. Finally, an in vivo rat model was established to study the effects of long-term exposure to PD fluid on the peritoneal membrane and the local host defence (peritoneal cells). RESULTS: In the rat model, long-term daily exposure is possible. The 'drop-out' after 9-10 weeks on the most commonly used PD fluid Dianeal 3.86%, however, is approximately 50% due to omental wrapping. In the remaining study group, large differences were observed (as compared with controls), especially with respect to morphological parameters. CONCLUSIONS: The rat peritoneal continuous exposure model seems to have potential for intervention studies, since it uses no additions, no antibiotics and no omentomectomy, and gives continuous long-term exposure to PD fluid. However, problems still remain: 'drop-out' is quite often seen and this non-uraemic exposure model does not totally mimic the situation present in continuous ambulatory PD patients.

Animals↗

PubMed2001

Accumulation of omental mast cells during peritoneal dialysis.

OBJECTIVE: New vessel formation has been reported in various tissues during peritoneal dialysis (PD). In that line, mast cells can produce factors such as tryptase, chymase, or basic fibroblast growth factor that might contribute to the formation of new vessels. In the present study, the association of mast cells with neovascularization during PD was investigated. METHODS: Rats received daily 10 mL infusions of conventional 3.86% glucose-containing PD fluid over a 10-week period. The infusions were delivered through a subcutaneously implanted mini access port that was connected by catheter to the peritoneal cavity. Untreated rats served as a control group. The number of blood vessels and of mast cells in the omentum were counted. Also, the number of peritoneal mast cells was determined. RESULTS: Chronic exposure to PD fluid resulted in an increased number of mast cells in the omentum. However, no clear correlation was found between the elevated number of omental blood vessels and the number of mast cells in the omentum or in the peritoneal cavity. CONCLUSIONS: Omental mast cells accumulated dramatically upon exposure to PD fluid. The actual role of accumulated omental mast cells in the induction of angiogenesis during PD should, however, be further investigated.

Animals↗

PubMed1999

Improved effects of novel glucocorticosteroids on immune-induced epithelial pathophysiology.

Glucocorticosteroids are a mainstay therapy in inflammatory bowel disease and other chronic inflammatory conditions. However, severe systemic side effects are associated with their long-term use. The new generation of glucocorticosteroids have a high degree of topical activity with reduced systemic effects due to rapid metabolism. We previously described an in vitro model of inflammation in which monolayers of the human T84 colonic epithelial cell line displayed altered ion secretion and increased permeability after coculture with endotoxin-activated monocytes/macrophages (MPhi). Here, we tested the effects of budesonide and two novel analogs, D5519 and S1316, on MPhi-induced epithelial changes. Filter-grown T84 monolayers were cocultured with activated MPhi and single daily doses of drug were added to the luminal (physiological) side of the monolayer. Basal and stimulated epithelial ion transport [baseline short-circuit current (Isc) and DeltaIsc to forskolin, respectively] and barrier (transepithelial resistance) parameters were measured 48 h later in Ussing chambers. D5519, S1316, and budesonide (10(-7) to 10(-9) M) dose dependently inhibited the MPhi-induced epithelial abnormalities, restoring normal resistance, decreasing the elevated baseline Isc, and improving the reduced Isc response to forskolin. Of the drugs tested, D5519 was consistently the most potent and effective in inhibiting the MPhi-induced epithelial irregularities. Coupled with a further improvement in their rate of hepatic inactivation, our findings indicate that the novel steroids, particularly D5519, will be a valuable addition to current treatment strategies for inflammatory bowel disease and other chronic inflammatory conditions.

Budesonide↗

PubMed1998

Monocyte/macrophages evoke epithelial dysfunction: indirect role of tumor necrosis factor-alpha.

We examined the ability of monocytes (MPhi) activated by bacterial products to alter epithelial physiology. Confluent monolayers of the T84 colonic epithelial cell line were grown on filter supports and then cocultured in the presence of human MPhi with or without the activating agents bacterial lipopolysaccharide and the bacterial tripeptide formyl-methionyl-leucyl-phenylalanine. After 24 or 48 h, monolayers were mounted in Ussing chambers where parameters of epithelial function were measured. Exposure to activated MPhi resulted in a significant increase (P < 0.05) in baseline short-circuit current (250% after 48 h) that was associated with enhanced secretion of Cl-. In addition, epithelial permeability was significantly increased as shown by reduced transepithelial resistance and increased flux of 51Cr-EDTA. Activated MPhi produced substantial amounts (approximately 3 ng/ml at 48 h) of tumor necrosis factor-alpha (TNF-alpha). TNF-alpha was identified as a key mediator acting via an autocrine mechanism to induce epithelial pathophysiology. Our data show that MPhi, when activated by common bacterial components, are potent effector cells capable of initiating significant changes in the transport and barrier properties of a model epithelium.

Adult↗

PubMed1996

Fibronectin concentrations correlate with ovarian follicular size and estradiol values in equine follicular fluid.

The amounts of total protein, albumin, fibronectin, alpha 2-macroglobulin (alpha 2-M), immunoglobulin G, ceruloplasmin and antithrombin were determined in fluids collected from 53 preovulatory equine follicles and compared with the contents of estradiol-17 beta, progesterone and androstenedione, with follicle size and the amounts of the equivalent proteins in normal equine plasma. The concentration of fibronectin and the fibronectin/albumin ratios increased significantly with follicle size and with follicular estradiol levels. The alpha 2-M levels and alpha 2-M/albumin ratios correlated with follicle size but not with hormone content. Both fibronectin and alpha 2-M were present in lower amounts in follicular fluid compared with plasma while the other proteins were present in similar amounts. Among the proteins evaluated, there was a positive correlation between the amount of the protein in the follicular fluid and the molecular weight of the protein.

Albumins↗