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Query: UMLS:C0024523 (malabsorption)
 7,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Microscopic (light and electron) and histochemical abnormalities have been demonstrated in the jejunum of rats with the blind loop syndrome. Three groups of animals were studied: normal control animals, and animals with either self-filling (SF) or self-emptying (SE) blind loops. Vitamin B12 malabsorption and bacterial overgrowth occurred only in those animals with SF blind loops. Three jejunal segments were studied: the blind loop segment and the jejunal segments proximal and distal to the blind loop. In the animals with the blind loop syndrome, those with SF blind loops, the most striking findings occurred in the blind loop itself, with similar but less marked changes in the jejunum distal but not proximal to the blind loop segment. Hypertrophy of both crypts and villi was evident with focal abnormalities of villus architecture. Approximately 10 to 20% of the columnar cells in the upper half of the villi were swollen and vesiculated. By electron microscopy microvilli demonstrated a variety of degeneration changes and the glycocalyx and terminal web were disrupted. Mitochondria and endoplasmic reticulum (ER), both smooth and rough, were swollen. Concentric whorls of parallel membranes and long, curvilinear rough ER were present in the cytoplasm. Histochemically, there was loss of enzymatic activity in the epithelial brush border, mitochondria and ER. Inasmuch as bacterial invasion of the jejunal mucosa was not seen, the etiology of these changes is not known but may involve bacterial "toxins" or products of bacterial metabolism. These morphological observations demonstrate that both brush border and intracellular injury occur in the jejunal epithelial cell of rats with the experimental blind loop syndrome.
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PMID:Small intestinal mucosal injury in the experimental blind loop syndrome. Light- and electron-microscopic and histochemical studies. 112 7

Duodenal bile acid concentration following a standard meal, glycine/taurine (G/T) ratio, vitamin B12 absorption, and faecal fat were determined in 79 patients with Crohn's disease. Intestinal resection had been made in 50 patients before the study, and no evidence of recurrence was present at the time of the study. Among 46 patients subjected to ileal resection of 10-180 cm, a reduced duodenal bile acid concentration and vitamin B12 malabsorption was almost invariably present when 50 cm or more of ileum had been removed. Patients with smaller resections and unoperated patients did not show a consistent pattern. Vitamin B12 absorption and duodenal bile acids were of equal value as indicators of ileal dysfunction with the exception that, in 10 ileostomy patients, duodenal bile acids were decreased in every case, but vitamin B12 absorption only when 80 cm of ileum or more had been resected. G/T-ratio was related to the extent of ileal resection-being elevated after large resections (80 cm or more)-but not to the presence of an abnormal flora. Faecal fat was much more elevated in ileostomy patients with large ileal resection (80 cm or more) than in unoperated patients and patients without an ileostomy.
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PMID:The effect of the site of lesion and extent of resection on duodenal bile acid concentration and vitamin B12 absorption in Crohn's disease. 113 25

A modified protein-bound cobalamin absorption test was used to study dietary cobalamin absorption in healthy adults of different age groups and patients with isolated low serum concentrations of cobalamin. Dietary cobalamin absorption was significantly reduced in healthy adults aged 55-75 years compared with young adults, with a further reduction in those older than 75 years. No difference was detected between dietary cobalamin absorption in patients with isolated low serum cobalamin and controls of a similar age group. Cobalamin malabsorption was associated with elevated serum gastrin. The diagnostic value of this protein-bound cobalamin absorption test in the elderly was limited by the frequent finding of reduced absorption in healthy elderly people with normal serum cobalamin concentrations. The performance of such tests should be evaluated in different age groups before application in diagnosis.
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PMID:Protein-bound cobalamin absorption declines in the elderly. 155 Jan 10

Impaired Vitamin B12 absorption after significant ileal resection has been reported to be permanent, although partial recovery after ileal bypass can occur. Three children are presented in whom Vitamin B12 malabsorption returned to normal 6-8 years after ileal resection. This was due probably to adaptation of the remaining small bowel, although spontaneous resolution of bacterial overgrowth is a possible explanation. An abnormal Schilling test after ileal resection does not automatically imply the need for life-long Vitamin B12 injections.
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PMID:Normalization of vitamin B12 absorption after ileal resection in children. 156 69

Intrinsic factor is produced by the gastric parietal cell. Its secretion is stimulated via all pathways known to stimulate gastric acid secretion: histamine, gastrin, and acetylcholine. There is, however, a different mode of secretion for both substances: atropine, vagotomy, and H2 receptor antagonists inhibit both intrinsic factor and acid secretion, but secretin and the hydrogen-potassium ATPase antagonist omeprazole have no effect on intrinsic factor while substantially reducing acid secretion. Cobalamin in food is bound to animal protein. Cobalamin deficiency due to inadequate dietary intake is rarely seen in extreme vegetarians (vegans). In the stomach cobalamin is liberated from its protein binding by peptic digestion and bound to R-proteins. Hypochlorhydria or achlorhydria, whether medically induced or not, may impair cobalamin uptake. The cobalamin-R-protein complex is split by pancreatic enzymes in the duodenum, where cobalamin is bound to intrinsic factor. Pancreatic insufficiency may lead to cobalamin deficiency. Lack of intrinsic factor is the commonest cause of cobalamin deficiency; very rarely, aberrant forms of intrinsic factor are produced, but the clinical syndrome is similar. Gram-negative anaerobe bacteria bind the cobalamin-intrinsic factor complex, and bacterial overgrowth of the small intestine diminishes cobalamin resorption. Parasitic infections with fish tape-worm and Giardia lamblia are also associated with cobalamin malabsorption. The cobalamin-intrinsic factor complex binds to the ileal receptors in the terminal ileum. Cobalamin absorption may be impaired after resection or by diseases affecting more than 50 cm of the terminal ileum, such as Crohn's disease, coeliac disease, tuberculosis, lymphoma or radiation. There is clearly a wide diversity in the aetiology of cobalamin deficiency, which requires a versatile diagnostic approach.
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PMID:Intrinsic factor secretion and cobalamin absorption. Physiology and pathophysiology in the gastrointestinal tract. 177 33

Vitamin B12 malabsorption in the ileum has been postulated as the underlying cause of the Imerslund-Grasbeck syndrome comprising megaloblastic anemia, proteinuria, and multiple neurological abnormalities. A young Saudi child with spasticity, truncal ataxia, cerebral atrophy, megaloblastic anaemia and proteinuria is described. Replacement therapy with parenteral vitamin B12 resulted in the complete resolution of his neurological findings and brain atrophy.
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PMID:Reversal of severe neurological abnormalities after vitamin B12 replacement in the Imerslund-Grasbeck syndrome. 194 Sep 89

Vitamin B12 malabsorption was reported earlier to occur in patients with exocrine pancreatic insufficiency, and pancreatic extracts were shown to improve the absorption of vitamin B12. We investigated serum levels of vitamin B12 and serum folate in patients with chronic pancreatitis and different degrees of pancreatic insufficiency. 137 patients (84 males, 53 females, age 34-72 years) with chronic pancreatitis (C.P.) were included in the study. 123 of 137 (89.8%) patients had a pathologic pancreatic function test result, classified into mild (n = 24), moderate (n = 61) or severe (n = 38) insufficiency. The normal range of serum vitamin B12 and folic acid was established in 58 healthy controls and was found to be 190-1020 pg/ml for serum vitamin B12 and 2.4-16.1 ng/ml for folic acid. 7 patients (5.7%) with C.P. had vitamin B12 serum levels below 190 pg/ml; 4 of these had severe and 3 had mild or moderate exocrine pancreatic insufficiency. However there was no overall correlation between the degree of pancreatic insufficiency and vitamin B12 values. Serum levels of Vitamin B12 were 512 +/- 48 pg/ml in mild, 493 +/- 52 pg/ml in moderate and 428 +/- 45 pg/ml in severe exocrine insufficiency. Serum folic acid below 2.4 ng/ml were present in 5 patients (3.6%). Folic acid serum levels were 8.34 +/- 0.76 ng/ml in mild, 6.34 +/- 0.52 ng/ml in moderate and 7.45 +/- 0.53 ng/ml in severe exocrine insufficiency. We conclude that vitamin B12 deficiency is a rare finding in chronic pancreatitis and does not strictly depend on the degree of exocrine pancreatic insufficiency.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Vitamin B12 and folic acid deficiency in chronic pancreatitis: a relevant disorder? 204 78

Vitamin B12 can bind two carrier proteins in the digestive tract, haptocorrin (R binder) and intrinsic factor, but only its binding to intrinsic factor allows its absorption. A malabsorption of vitamin B12 is observed in about 30% of adult patients with exocrine pancreatic insufficiency, using the Schilling test. None of the hypotheses that have tried to explain this malabsorption are entirely satisfactory. A failure to degrade haptocorrin can prevent the binding of vitamin B12 to intrinsic factor. It has also been suggested that pancreatic secretion could modify the structure of intrinsic factor, enabling the uptake of the vitamin B12-intrinsic factor complex by the ileum. Other factors can also affect the binding of vitamin B12 to intrinsic factor, such as the gastric pH and bile. The Schilling test is abnormal in nearly all cases of cystic fibrosis. One explanation could be the gastric hyperacidity observed in this disease. Despite the frequency of abnormal Schilling tests, vitamin B12 deficiency is very rare in cases of exocrine pancreatic dysfunction, in adults as well as in children with cystic fibrosis. The assimilation of this vitamin with a tracer included in food instead of the crystalline labeled cobalamin used in the Schilling test remains to be investigated.
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PMID:Malabsorption of vitamin B12 in pancreatic insufficiency of the adult and of the child. 223 67

A case is reported of a patient with symptomatic bacterial overgrowth and Vitamin B12 malabsorption secondary to two duodenal diverticula, treated successfully by surgical excision of the diverticula.
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PMID:Surgical treatment of duodenal diverticula associated with symptomatic bacterial overgrowth. 251 Jul 9

We have investigated the acute and chronic side effects of cancer chemotherapy on the intestinal absorption of adult patients with neoplastic diseases. D-xylose absorption was reduced by 35% in 34 of 50 patients within 48 hours after one course (p less than 0.001), while the vitamin B12 absorption was diminished by 41% in 27 of 38 patients (p less than 0.001). The serum digoxin level fell in 7 of 8 patients by 43% at the first day (p less than 0.01) and normalized after one week. Electron microscopy of the jejunal biopsy specimens revealed damages of the microvilli and defects in the glycocalix. Chronic effects, which were measured after several courses and a pause of four weeks, showed a diminished D-xylose absorption of 36% in 16 of 19 cases (p less than 0.01). Vitamin B12 absorption was reduced by 37% in 11 of 13 patients (p less than 0.01). Microscopical investigations of the jejunum revealed a shortening of the villi and a destruction of microvilli. Acute and chronic malabsorption after cancer chemotherapy should be considered in patients, who are treated with enteral medication and nutrition.
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PMID:[Disorders of intestinal absorption in patients treated with cytostatic chemotherapy]. 258 35


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