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Results for “INTESTINAL AMEBIASIS”

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PubMed1992

Model of intestinal amebiasis: structural and functional lesions to the rabbit colon mucosa by Entamoeba histolytica lysates.

Although the events occurring during the initial interaction of E. histolytica trophozoites with the mucosa of the large intestine probably determine the invasion by the parasites, an appropriate experimental model does not exist. To develop such a model we used full-thickness rabbit colon preparations (0.28 cm2) mounted in Ussing-type chambers. Untreated preparations had electrophysiological properties (potential difference, short-circuit current and electrical resistance) similar in magnitude and duration to those reported for stripped colonic mucosa. Exposure to E. histolytica trophozoite lysates for up to 80 min produced dose-dependent lesions in the colon, consisting of: (a) increased decay rates for potential difference, short-circuit current and transmural resistance, and (b) mucosal lesions involving vacuolation at the bases and shortening of epithelial cells, loss of intercellular junctions, destruction of microvilli, and necrosis of interglandular epithelial zones. The specificity and speed of the electrophysiologic effects and their correlation with the microscopic lesions suggest that this new model will help to understand the initial pathogenic events of intestinal amebiasis.

Animals↗
PubMed1999

Spectrum of complicated intestinal amebiasis through resected specimens: incidence and outcome.

BACKGROUND/PURPOSE: Entamoeba hystolytica (EH) is an enteric protozoan that may cause serious complications that require operative management in children. A retrospective clinical trial was performed to find out the incidence and outcome of complicated intestinal amebiasis (IA) by means of surgically resected specimens in children. METHODS: The histopathologic evaluation of 554 intestinal specimens (including appendix and polyp) of 482 patients between 1980 and 1997, inclusive, were reviewed. Intestinal biopsy specimens taken from successfully medically treated patients with uncomplicated IA were excluded. RESULTS: Complicated IA was noted in 18 children (3.7%) consisting of 7 girls and 11 boys with a mean age of 9.2+/-2.3 years. EH was present in the (1) appendices of 4 patients with perforated appendicitis and 3 patients with normal appendix who underwent negative exploration; (2) juvenile polyps of 4 patients presenting with hematochesia; (3) colonic wall of 1 patient presenting with intussusception and treated by resection and anastomosis; (4) cecum of 1 patient presenting with right lower quadrant mass and underwent exploration with the presumptive diagnosis of lymphoma; (5) colonic wall of 5 patients who underwent ileostomy followed by subtotal colectomy and endorectal pull-through with the presumptive diagnosis of chronic inflammatory bowel disease (n = 3), toxic megacolon + peritonitis (n = 1), and total colonic polyposis (n = 1). All above-mentioned patients are alive and free of symptoms. CONCLUSIONS: The diagnosis of IA should be considered in a very wide spectrum of clinical appearances. IA may be associated with colonic polyps and perforated appendicitis, may act as a leading point for intussusception, and may mimic the clinical picture of appendicitis and lymphoma resulting in negative explorations. The diagnosis and treatment of complicated IA in patients who received a misdiagnosis of inflammatory bowel disease is a great challenge and requires major and emergency surgery.

Appendicitis↗
PubMed2000

Pathogenesis of intestinal amebiasis: from molecules to disease.

In spite of a wealth of knowledge on the biochemistry and cellular and molecular biology of Entamoeba histolytica, little has been done to apply these advances to our understanding of the lesions observed in patients with intestinal amebiasis. In this review, the pathological and histological findings in acute amebic colitis are related to the molecular mechanisms of E. histolytica pathogenicity described to date. Infection of the human colon by E. histolytica produces focal ulceration of the intestinal mucosa, resulting in dysentery (diarrhea with blood and mucus). Although a complete picture has not yet been achieved, the basic mechanisms involved in the production of focal lytic lesions include complex multifactorial processes in which lectins facilitate adhesion, proteases degrade extracellular matrix components, porins help nourish the parasite and may also kill incoming polymorphonuclear leukocytes and macrophages, and motility is used by the parasite to invade deeper layers of the colon. In addition, E. histolytica has developed mechanisms to modulate the immune response during acute infection. Nevertheless, much still needs to be unraveled to understand how this microscopic parasite has earned its well-deserved histolytic name.

Animals↗
PubMed2001

Intestinal amebiasis: a diagnosis not to be missed.

Entamoeba histolytica is a well-recognized cause of infectious colitis and disseminated amebic abscesses. Most prevalent in the tropics and subtropics, E. histolytica infections may also occur in the developed world. We describe a case of a North American traveler with intestinal amebiasis, a diagnosis first made by colonic biopsy. We review the available diagnostic tools and the role of the surgical pathologist in the detection of this infection.

Adult↗
PubMed1992

Early invasive intestinal amebiasis in Mongolian gerbils.

Mongolian gerbils were inoculated intracecally with E. histolytica trophozoites cultured monoxenically. During the first hours of interaction an increase in mucus production was observed. Microulcerative mucosal lesions appeared 24 to 72 h post-inoculation. Inflammatory infiltrate and edema of the lamina propria were associated with necrotic foci. At 96 h, the cecal mucosa was normal and live amebas were no longer detected. It is concluded that gerbils are useful as experimental models for studying the early stages of invasive intestinal amebiasis.

Animals↗
PubMed1978

[Intestinal amebiasis in children. I. Etiological study of colonic lesions of the rectosigmoid colon].

A total of 253 children from two months to 12 years old, who had diarrheic or dysenteric syndromes, were studied from the rectosigmoidoscopic and parasitologic points of view. In addition, 112 and 20 of these patients were also studied bacteriologically and virologically, respectively. Only in 28 patients torphozoites of Entamoeba histolytica were found by means of direct microscopic examination, staining techniques and amoebal cultures. Enteropathogenic bacteria were isolated in 41 of the 112 cases examined. No viral particles were detected in the 20 cases studied. From the discussion of these results, the conclusion is reached that the rectosigmoidal mucusal alterations which have been currently considered as suggesting amoebal lessions are not characteristic of invasive intestinal amebiasis in children.

Child↗
PubMed1988

Generation of reactive oxygen species by Kupffer cells and blood monocytes during intestinal amebiasis in guinea pigs.

The reactive oxygen species generation capacity of Kupffer cells and blood monocytes was studied through chemiluminescence (CL) in guinea pigs, infected intracecally with Entameba histolytica, on days 0, 3, 7, 14 and 21 post infection. There was an elevated response up to the 14th post-infection day. The CL response of these cells was diminished on the 21st post infection day though it was significantly higher than up the controls. The CL response increased exponentially with the severity of cecal lesions. A direct correlation was observed between the CL response of phagocytic cells and cecal lesions of animals. The role of oxygen species in causation of tissue injury during intestinal amebiasis is postulated.

Animals↗