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PubMed2000

Megarectum in constipation.

BACKGROUND: Faecal impaction is frequently observed in children with chronic constipation. The term megarectum is often used to describe this finding. AIM: To evaluate rectal functioning and rectal measures in constipated children with a filled rectum, in order to define the terms faecal impaction, enlarged rectum, and megarectum. METHODS: All children underwent radiological investigation, colonic transit time study, anorectal manometry, and rectal volume and rectal wall compliance measurements. Patients with faecal impaction were compared with controls, who had an empty rectum on digital rectal examination. RESULTS: A total of 31 patients and six controls were included in the study. The mean duration of complaints was 4.2 years and all had faecal incontinence. The colonic transit times in the patients showed a distinct delay in the rectosigmoid segment. Anorectal manometry was not significantly different between patients and controls. The rectal width in patients was 0.68 and in controls 0.52 with an upper limit of 0.61. The pressure-volume curve in patients showed significant less relaxation at a distension of 50 ml. The slope of the curve (corresponding with rectal wall compliance) was comparable for patients and controls. CONCLUSIONS: We suggest that faecal impaction is a filled rectum found on digital rectal examination; an enlarged rectum is defined by a rectopelvic ratio greater than 0.61; and megarectum is defined in those with significant abnormalities found with anorectal manometry, pressure-volume curves, or rectal compliance investigation. A diminished relaxation of the rectum on rectal distension could be the first sign of megarectum in children with chronic constipation.

Adolescent↗

PubMed1989

Biosynthetic precursor (214 kDa) of apolipoprotein B-48 is not secreted by Caco-2 cells and normal human intestine.

The synthesis and secretion of apolipoprotein B (apo B) was studied in a human colon carcinoma (Caco-2) cell line and in explants from normal human intestine. In Caco-2 cells, the specific activity of the intestinal disaccharidases maltase, sucrase-isomaltase and lactase was enhanced 8-, 6- and 3-fold respectively, at 19 days post-confluence as compared with 1-day-post-confluence cultures. The level of apo B secreted into the medium increased from undetectable in the cells just reaching confluency, to 115 ng/ml at 18 days post-confluence. The presence of apo B-100 and apo B-48 with mobilities on SDS/polyacrylamide-gel electrophoresis corresponding to those of human very-low-density lipoproteins and lymph chylomicrons, respectively, was detected in the media from 7-, 12- and 18-days-post-confluence cells. These two apo B proteins were also found intracellularly in 7-day-post-confluence cultures. However, more differentiated cells (12 and 18 days post-confluence) accumulated large amount of a 214 kDa protein intracellularly. Apo B-related 214 kDa protein was also synthesized by normal human intestinal explants. A pulse-chase experiment with explants from normal human jejunum showed a slow intracellular conversion of the 214 kDa protein into the size of mature apo B-48 (264 kDa), concomitant with increasing amounts of mature apo B-48 in the medium, suggesting a precursor-product relationship. Despite large intracellular quantities, the 214 kDa protein from the normal human tissue and Caco-2 cells was absent from the medium. No apo B-100 synthesis was detected in the human explants. These findings may help in our understanding of cholesterol and lipid metabolism in health and in some disorders characterized by the inability to secrete apo B-containing lipoproteins.

Apolipoprotein B-48↗