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Measurement of red cell folate with 75Se-selenofolate radioassay.

75Se-selenofolate radioassay was adapted for the purpose of red cell folate measurement. The results of assay of 124 whole blood samples by Lactobacillus casei microbiological assay and by radioassay using the adapted selenofolate method were concordant (r = 0.8). Red cell folate levels by the radioassay were below 170 microgram/1 in people who had haematological features of folate depletion. The distribution of results among reputedly healthy subjects extended down to 140 microgram/1.

Biological Assay↗

In vitro expression of a mouse tissue specific glutathione-peroxidase-like protein lacking the selenocysteine can protect stably transfected mammalian cells against oxidative damage.

The complete sequence of the mouse epididymal protein (MEP24) was cloned. It contains a 663 bp open-reading frame that, after conceptual translation, shows extensive identity with proteins belonging to the glutathione peroxidase (GPX) family. However, a major difference between GPX5 (MEP24) and other known GPXs concerns a protein domain known to be critical for GPX function. To find out what could be the physiological function of such a protein in the mouse epididymis, we have used a mammalian expression system to overexpress the GPX5 protein. Cells constitutively expressing the GPX5 protein were generated and assayed for their ability to metabolize regular substrates of GPX enzymes. Data presented here show that the GPX5-expressing cells can metabolize hydrogen peroxide in a manner that is consistent with a peroxidase activity. However, the substrate preference of the GPX5-expressing cells and their apparent insensitivity to a regular inhibitor of GPX enzymes suggest that the GPX5 protein belongs to a particular class of GPX proteins. Involvement of this protein in the physiology of the mouse epididymis is discussed.

Amino Acid Sequence↗

Colonoscopy and SeHCAT for investigation of chronic diarrhea.

BACKGROUND/AIMS: Chronic diarrhea is a common problem. Colonoscopy is the investigation of choice for diagnosis. Even a macroscopically normal mucosa on endoscopy can have abnormalities such as microscopic colitis and bile acid malabsorption (BAM). The aim of this study was to establish the value of colonoscopy with biopsies in patients with chronic diarrhea and to evaluate the additive value of a SeHCAT test for diagnosing BAM in these patients. METHODS: All patients who underwent a colonoscopy between November 1999 and December 2000 were included. Patient files, colonoscopy and pathology reports and SeHCAT test results were reviewed. RESULTS: 205 patients were included. The most common diagnoses were diarrhea-predominant IBS (n = 76) and IBD (n = 38). 158 patients had non-bloody diarrhea, 113 (72%) of them had a macroscopically normal appearing mucosa. In 40 (35%) of these patients, a histological diagnosis could be made and microscopic colitis was the most common diagnosis (n = 27). SeHCAT test was performed in 36 patients and 15 (42%) of them had BAM. In the 47 patients with bloody diarrhea, IBD was the main diagnosis (n = 23). CONCLUSION: Colonoscopy with biopsies must be performed when investigating chronic diarrhea and BAM should be excluded.

Bile Acids and Salts↗

Small bowel function after surgery for chronic radiation enteritis.

The retention of the gamma-emitting 75Se-homotaurocholic acid (SeHCAT) after 72 and 168 h was assessed in 10 patients after ileal resection for radiation injury (group I). 6 patients suffering from chronic postirradiation diarrhea (group II) and 6 patients in whom the ileum had been resected for other indications (group III) were also examined. The retention of SeHCAT was abnormally low (less than 50%) in all cases after 72 h and below 20% in 19 out of 21 cases after 168 h. The length of resected small bowel (groups I and III) was inversely related with SeHCAT retention after 72 h (r = 0.63; p = 0.015), but not after 168 h. There was no correlation between the diarrhea score and the extent of bowel resection, SeHCAT retention or xylose absorption. Hydrogen breath test with lactulose revealed a significantly shortened orocecal transit time in group I, compared to groups II and III. Xylose absorption was significantly reduced in patients with positive 5 g xylose-H2 breath test. In groups I and III, however, xylose absorption tended to improve with increasing time interval following resection (r = 0.79; p = 0.003). It is concluded that radiation injury in addition to small-bowel resection contributes significantly to malabsorption and diarrhea in patients after ileal resection for radiation sequelae. The chronic radiation damage seems to act mainly through impaired motility.

Body Weight↗