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

1. Pteroylmonoglutamic acid (PteGlu) absorption has been measured by using the technique of small-intestinal perfusion with tritiated PteGlu in normal subjects and in patients with coeliac disease. 2. At similar intrajejunal pH, patients with untreated coeliac disease have significantly less PTEGlu than normal subjects and patients with treated coeliac disease. 3. The "resting" pH in the jejunum did not differ markedly between normal subjects and patients with coeliac disease. 4. Increasing pH decreased PteGlu absorption in patients with coeliac disease and in normal subjects. 5. These findings suggest that PteGlu malabsorption in coeliac disease is not due to abnormally high pH in the jejunum.
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PMID:The effect of pH on folic acid absorption in man. 0 22

Folic acid is one of the 'younger' vitamins, yet it has attracted intensive study in the thirty years since the identification of pteroylglutamic acid and its polyglutamyl conjugates. The absorption and malabsorption of folates, natural, purified and synthetic, in disease has been studied more than any other vitamin and indeed folate absorption has become one clinical test of intestinal function. We know little about the release of folate from protein complexes, but we have learned, with the help of synthetic radiolabelled pteroylpolyglutamates that polyglutamyl folates are hydrolysed at or near the luminal border of the intestine and the released folate is efficiently absorbed. The rate limiting stage of folate absorption appears to be the transport of the monoglutamyl folate. In disease, and with drugs, folate malabsorption occurs primarily when monoglutamyl transport is depressed. The specific components of the folate transport system, listed in Table 4, are receiving increased attention. The mechanism of uptake is still a topic of controversy but a dual system including both a saturable and a diffusion component would explain most of the data. Reduction and methyl or formyl addition occur in the intestine but such metabolism is not obligatory for transport. The nature of folate binding within the cell and the function of specific folate binding proteins requires further study. At present we have little or no information about the mechanism of folate release from the epithelial cell to the circulation but this step also could influence the rate and specificity of overall process. The tools are now at hand to complete our understanding of the steps in folate absorption and metabolism. Such an understanding should facilitate the management of folate deficiency whenever it complicates gastrointestinal disease or drug therapy.
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PMID:Absorption and malabsorption of folates. 1 Jan 21

Serum vitamin B12 concentrations were measured in 60 patients undergoing repetitive hemodialysis and in undialyzed patients with chronic renal failure. Dialysis patients had significantly lower serum vitamin B12 levels than the nondialyzed group 321 +/- SEM 38 pg/ml versus 793 +/- 100), and 19 of 60 dialysis patients had vitamin B12 Concentrations less than 200 pg/ml. Folic acid concentration was 5 times greater in dialysis than in nondialysis patients, presumably because the latter received daily supplementation with folic acid. Serum vitamin B12 concentrations fell progressively during the patient's course of dialysis. Neither inadequate dietary intake nor vitamin B12 malabsorption accounted for the differences in the serum vitamin B12 concentrations seen in the two groups. Serum vitamin B12 levels and nerve conduction velocities in 51 dialyzed patients showed a significant correlation. Six dialyzed patients with low serum vitamin B12 levels and slow nerve conduction velocities showed improvement in nerve conduction (+ 14.6 +/- 3.3 m/sec) following the parenteral use of pharmacological doses of vitamin B12. The cause of the low serum vitamin B12 concentration is not clear, nevertheless, alterations in serum vitamin B12 seen in some dialysis patients may be a factor in the persistence of abnormal nerve conduction and may be reversed with large doses of parenteral vitamin B12.
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PMID:Vitamin B12 levels and nerve conduction velocities in patients undergoing maintenance hemodialysis. 18 Jul 88

We studied five patients (two men and three women, age between 58 and 76 years) with clinical and electrophysiological signs of polyneuropathy. Routine neurological, hematological, and gastroenterological studies as well as procedures to test fat malabsorption were performed. Folate determinations were done using both radioactive and Lactobacillus casei methods. Two patients displayed the signs of subacute combined degeneration of the spinal cord with polyneuropathy, while three had only signs of neuropathy. All had low serum folate concentration, long-standing gastrointestinal disease, and deficient folate intake. The D-xylose absorption test gave values in all patients, while none displayed the classical malabsorption syndrome. The patients had substantial improvement or recovered (according to clinical and electrophysiological measurements) after periods ranging from 9 to 39 months of folate therapy. Such acquired folate-responsive polyneuropathy has two principal characteristics: mixed sensorimotor with mainly sensory deficits, and involvement of one or both of the lower extremities much more extensively than the upper extremities.
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PMID:Polyneuropathy and folate deficiency. 21 Jul 47

Pteroylglutamic acid (PGA) absorption was assessed in ten untreated tropical sprue (TS) and eight control subjects utilizing a marker perfusion technique. Physiologic concentrations of the vitamin (25 ng/ml) dissolved in iso-osmotic solutions containing either mannitol of glucose at a concentration of 55.6 mM were perfused on each subject on two consecutive days. A statistically significant difference in PGA absorption between TS and control subjects was obtained only when glucose was present in the perfusate. Thus, unequivocal malabsorption of PGA is demonstrable in all subjects with TS when more refined techniques than the ones applied heretofore are utilized.
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PMID:Pteroylglutamic acid malabsorption in tropical sprue. 80 48

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

Dietary folates exist as pteroylpolyglutamates (PteGlun) that undergo hydrolysis to pteroylmonoglutamate (PteGlu) forms during the process of intestinal absorption. Using the technique of jejunal perfusion of separately labeled folates, our laboratory has demonstrated that hydrolysis of PteGlun occurs on the surface of the jejunum and is a prerequisite for folate absorption. An intestinal brush border pteroylpolyglutamate hydrolase (BB-PPH) has been identified in human and pig jejunum with characteristics that are distinct from those of an intracellular hydrolase (IC-PPH). Functional parallels of BB-PPH with in vivo hydrolysis of PteGlun in human and pig intestine and the clinical responsiveness of BB-PPH to different disease states indicate that this enzyme plays the major physiological role in folate absorption. Folate malabsorption is found in diseases which affect the jejunal mucosa and in response to various drugs. In most of these clinical conditions, folate malabsorption results from suppression of both of the processes of hydrolysis of PteGlun and jejunal uptake of PteGlu. Ongoing studies in miniature pigs are aimed at definition of the sequence of development of folate malabsorption in chronic alcoholism.
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PMID:The intestinal absorption of dietary folates in health and disease. 269 55

Folic acid absorption was studied in 12 elderly subjects with atrophic gastritis and 10 elderly normal controls using tritium-labeled pteroylmonoglutamic acid. Two folic acid absorption tests were carried out on each subject with 120 ml of either water or 0.1 N HCl. Folic acid absorption was significantly lower in subjects with atrophic gastritis than in normal controls (31% vs. 51%, respectively; p less than 0.01). In subjects with atrophic gastritis, folic acid absorption rose significantly to 54% (p less than 0.001) when administered with acid, but did not change in normal controls (50%). Serum folate levels were normal in all subjects. Proximal small intestinal pH was higher in atrophic gastritis subjects than in normal controls (7.1 vs. 6.7, respectively; p less than 0.05), as were bacterial counts of small intestinal fluid (p less than 0.01). Bacteria cultured from the aspirates of subjects with atrophic gastritis were able to synthesize folate in vitro when incubated in a folate-free medium. Atrophic gastritis results in folic acid malabsorption but not in folate deficiency, possibly due to increased bacterial synthesis of folate in the small intestine.
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PMID:Folic acid malabsorption in atrophic gastritis. Possible compensation by bacterial folate synthesis. 377 Mar 72

A description and evaluation of the methods used in a clinical investigation of the relationship between nutritional status and intestinal malabsorption in a sample of asymptomatic rural residents in Puerto Rico and the Dominican Republic is presented. These countries were choosen for their contrasting nutritional status. The diet of the rural population in Puerto Rico is relatively good while the diet of Dominican Republic's rural residents is marginal. Household surveys were conducted in one small, rural community in Puerto Rico and in another such community in the Dominican Republic. A sample of 96 patients from the former and 42 patients from the latter were hospitalized for 6 days. Their diet was controlled and a series of tests were performed in order to assess intestinal absorption. The usefulness of the various clinical determinations was then evaluated. Folic acid absorption studies and fat and nitrogen studies were found to be too time-consuming. Determination of fecal excretion of nitrogen and B12 serum concentrations yielded sufficient information and were judged useful. As many tests as possible had to be performed in assessing jejunum and ileum function as the intestional abnormalities were not limited to one site. Some were in the jejunum only, others were in the ileum only, and others were scattered throughout the small intestine. Tables show 1) age-sex distributions and monthly family income for the studied communities; 2) nitrogen balance study results; and 3) daily intake of protein for Puerto Rican and Dominican Republican subjects.
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PMID:Investigations concerning the prevalence of nutritional deficiencies and intestinal malabsorption among rural populations of the West Indies. I. Methodology. 508 46

Malabsorption of folate polyglutamates prepared from yeast has been shown in eight patients with untreated tropical sprue and in three out of six patients receiving therapy for sprue. The absorptive defect for folate polyglutamates among these 14 patients occurred more frequently and in all but one patient more severely than for folic acid.Folate polyglutamates, the principal dietary form of folate, probably require deconjugation by the jejunal enzyme, folate conjugase, before absorption. The mean concentration of jejunal folate conjugase of 21 patients with untreated sprue and of 13 patients with sprue receiving therapy were both significantly less than the mean concentration in a control group. Nevertheless, all but five of the 34 patients had jejunal folate concentrations within the control range. There was no correlation in the individual patients between the jejunal folate conjugase concentration measured in vitro and the ability to absorb folate polyglutamates-nine patients having normal jejunal folate conjugase levels despite showing malabsorption of folate polyglutamates.
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PMID:Malabsorption of folate polyglutamates in tropical sprue. 576 88


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