Biomedical subjects

María Antolín

Publications and source records attributed to María Antolín.

6 recordsLinked to original sources

PubMed2006

Lactobacillus casei prevents the upregulation of ICAM-1 expression and leukocyte recruitment in experimental colitis.

Lactobacillus casei has been shown to attenuate the severity of experimental colitis. The objective of the present study was to determine whether the effects of L. casei on colitis are related to modulation of leukocyte recruitment into the inflamed intestine. Rats with a colonic segment excluded from fecal transit were surgically prepared. The segment was decontaminated with antibiotics and recolonized with normal flora isolated from the inflamed rat colon, associated or not to L. casei. Control and colitic [2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced] animals were studied. Leukocyte-endothelial cell interactions were characterized in the colonic microcirculation by intravital microscopy, and ICAM-1 and VCAM-1 expression was measured by the radiolabeled antibody technique. Compared with the noninflamed colonic segment, induction of colitis by TNBS provoked a marked increase in the number of leukocytes firmly adherent to the venular wall (0.5 +/- 0.1 vs. 2.1 +/- 0.6 leukocytes/100 mum, P < 0.01). Colonization with L. casei significantly reduced the number of adherent leukocytes (1.3 +/- 0.4 leukocytes/100 mum; P < 0.05) but did not affect the increased rolling interactions associated with the induction of colitis. Compared with the noncolitic group, induction of colitis was associated with a marked increase in ICAM-1 expression (117 +/- 4 vs. 180 +/- 3 ng antibody/g tissue) that was abrogated when the colitic segment was colonized by L. casei (117 +/- 3 ng antibody/g tissue, P < 0.05). However, L. casei administration did not modify VCAM-1 upregulation in colitic animals. L. casei attenuates leukocyte recruitment observed in experimental colitis induced by TNBS. This effect is possibly related to abrogation of ICAM-1 upregulation.

Animals↗

PubMed2006

Study of laparoscopic forces perception for defining simulation fidelity.

One of the most controversial dilemmas in virtual reality laparoscopic simulators design is the incorporation of force feedback (FF). This issue is approached with an experimental design in which surgeons assess the resistance against pulling of four different tissues, which are characterized with the acquisition of interaction forces. Comparing subjective assessments with objective force parameters we aim to determine the fidelity boundary beyond which no more realism is necessary in simulation. Interaction pulling forces of four tissues have been characterized, which can constitute a basis for requirements of a FF algorithm. Results have also led to the hypothesis that surgeons are able to differentiate tissues and perceive somesthesic information although resulting interaction forces are of the same magnitude than interferences like trocar friction.

Animals↗

PubMed2005

Induction of colonic transmural inflammation by Bacteroides fragilis: implication of matrix metalloproteinases.

BACKGROUND: Commensal bacteria are implicated in the pathophysiology of intestinal inflammation, but the precise pathogenetic mechanisms are not known. We hypothesized that Bacteroides fragilis-produced metalloproteinases (MMPs) are responsible for bacterial migration through the intestinal wall and transmural inflammation. AIM: To investigate the role of bacterial-MMP activity in an experimental model of colitis induced by the intramural injection of bacteria. METHODS: Suspensions of viable B. fragilis or Escherichia coli were injected into the colonic wall, and the effect of the MMP inhibitor (phenantroline) on histologic lesion scores was tested. MMP activity in bacterial suspensions was measured by azocoll assay. RESULTS: The inoculation with B. fragilis induced chronic inflammatory lesions that were preferentially located in the subserosa, whereas inoculation with E. coli induced acute-type inflammatory reactions, evenly distributed in both the submucosa and subserosa. Treatment with phenantroline significantly decreased subserosal lesion scores in rats inoculated with B. fragilis, but not in rats inoculated with E. coli. Bacterial suspensions of B. fragilis showed MMP activity, but E. coli suspensions did not. Sonication of B. fragilis reduced MMP activity and virulence to induce serosal lesions. CONCLUSION: Our data suggest that bacterial MMPs may be implicated in the serosal migration of B. fragilis and in the induction of transmural inflammation.

Animals↗

PubMed2004

Hydrogen breath test with low-dose rice flour for assessment of exocrine pancreatic insufficiency.

OBJECTIVES: The hydrogen (H2) breath test is widely used in the assessment of carbohydrate malabsorption. Severe exocrine pancreatic insufficiency markedly diminishes pancreatic amylase production and results in malabsorption of complex carbohydrates. Thus, the H2 breath test with low-dose rice flour starch was tested to determine its value in detecting exocrine pancreatic insufficiency by comparison with a direct measurement of pancreatic function. METHODS: Ten patients with clinically suspected pancreatic insufficiency confirmed with a duodenal perfusion technique and measurement of trypsin and lipase output after cerulein stimulation were included. An H2-rice flour breath test was performed by orally administering 30 g of rice flour. End-alveolar breath samples were obtained before rice load and at 30-minute intervals thereafter for the next 5 hours. RESULTS: The results are expressed as median (percentile 25-75). Patients included 8 men and 2 women with moderate to severe exocrine pancreatic insufficiency due to chronic pancreatitis, pancreatectomy, or cystic fibrosis. Stimulated duodenal output of lipase and trypsin was abnormally low in all patients (median release, 1.7; range, 0.5-4.5 and 0.8, range, 0.1-11.3 KU/h, respectively). Basal H2 excretion was 9 ppm (range, 7-17) and delta increase over basal H2 excretion was 4 ppm (range, 1-6). Correlation between H2-rice breath test and basal or stimulated duodenal output of lipase and trypsin was not significant. CONCLUSION: In exocrine pancreatic insufficiency, an oral load of 30 g rice flour slightly raises H2 excretion in breath. This increase is not useful for detecting pancreatic insufficiency due to poor sensitivity and because it is influenced by extrapancreatic factors such as small bowel bacterial overgrowth.

Adult↗

PubMed2003

Effects of nonpathogenic bacteria on cytokine secretion by human intestinal mucosa.

OBJECTIVE: The human intestine harbors a complex microbial ecosystem, and the mucosa is the interface between the immune system and the luminal environment. The aim of this study was to elucidate whether host-bacteria interactions influence mucosal cytokine production. METHODS: Macroscopically normal colonic specimens were obtained at surgery from eight patients with neoplasm, and inflamed ileal specimens were obtained from two patients with Crohn's disease. Mucosal explants were cultured for 24 h with either nonpathogenic Escherichia coli ECOR-26, Lactobacillus casei DN-114 001, L. casei DN-114 056, L. casei ATCC-334, or Lactobacillus bulgaricus LB-10. Each study included blank wells with no bacteria. Tissue and bacteria viability were confirmed by LDH release and culture. Concentration of tumor necrosis factor (TNF)alpha, transforming growth factor beta1, interleukin (IL)-8, and IL-10 was measured in supernatants. In parallel experiments, neutralizing anti-TNFalpha antibody was added to the culture. RESULTS: Co-culture of mucosa with bacteria did not modify LDH release. Co-culture with L. casei strains significantly reduced TNFalpha release, whereas E. coli increased it. These effects were observed both in normal and inflamed mucosa. In combination studies, L. casei DN-114 001 prevented TNFalpha stimulation by E. coli. L. casei DN-114 001 also reduced IL-8 release via a TNFalpha-independent pathway. L. casei DN-114 056 or E. coli increased IL-10 release in the presence of neutralizing anti-TNFalpha. CONCLUSIONS: Nonpathogenic bacteria interact with human intestinal mucosa and can induce changes in cytokine production that are strain specific.

Aged↗

PubMed2002

Increased activity and expression of matrix metalloproteinase-9 in a rat model of distal colitis.

Matrix metalloproteinases may play a role in tissue remodelling and destruction associated with inflammation. We investigated activity and expression of matrix metalloproteinases in a rat model of colitis and tested the therapeutic potential of a synthetic inhibitor (CGS-27023-A). Colitis was induced by dextran sulphate sodium (at 5% in drinking water for 5 days) in a group of eight rats, whereas a matched control group received plain water. Activity and expression of matrix metalloproteinases were measured in colonic tissue homogenates using zymography and Western blot on days 3 and 5 after induction of colitis. In another set of experiments, two groups of colitic rats (20 per group) were treated with CGS-27023-A (20 mg/kg) or vehicle, respectively. On days 5 and 14, colonic mucosal lesions were blindly scored by microscopic examination. Induction of colitis led to a significant upregulation of matrix metalloproteinase-9 protein and its activity, but no change in matrix metalloproteinase-2 activity was observed. Treatment with CGS-27023-A significantly decreased the extent and severity of epithelial injury but did not influence mucosal repair. We conclude that increased activity of matrix metalloproteinases may contribute to epithelial damage in this model of colitis.

Animals↗