Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0024523 (malabsorption)
 7,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epidemiological and experimental studies indicate a strong association between an elevated colon cancer risk and increased fecal excretion of secondary bile acids, neutral sterols, and prolonged gastrointestinal transit time. Starch malabsorption, on the other hand, has been reported to be a possible protective factor in colon carcinogenesis. To study the impact of starch malabsorption on these parameters, 12 healthy volunteers consumed a diet rich in starch for two 4-week periods. During a double-blind crossover trial they received the alpha-glucosidase inhibitor acarbose (BAY g 5421) in one of the study periods and placebo in the other. During acarbose treatment stool wet weight increased by 68%, stool dry weight by 57%, and gastrointestinal mean transit time by 30%. Fecal concentrations (mg/g dry weight) of the neutral sterols coprostanol, coprostanone, campesterol, 4-cholesten-3-one, and beta-sitosterol decreased by 36.8, 48.7, 42.1, 34.6, and 39.4%, respectively, under acarbose. Concentrations of the major secondary bile acids, deoxycholic and lithocholic acid, decreased by 59.9 and 52.2%, respectively. In spite of an increased stool weight, also daily excretion (mg/day) of these two bile acids was lower under acarbose (47.9 and 36.6%, respectively) compared to placebo, whereas excretion of the main primary bile acid, cholic acid, rose from 22.58 mg/day to 379.80 mg/day during the acarbose period. The changes in fecal bile acid and neutral sterol excretion found during acarbose treatment may explain a protective effect of starch malabsorption on colon cancer development.
 ...
PMID:Effect of starch malabsorption on fecal bile acids and neutral sterols in humans: possible implications for colonic carcinogenesis. 186 44

It has been suggested that a significant amount of starch may reach the colon undigested and stimulate microbial fermentation. Indirect estimates of the quantity of starch reaching the colon have been obtained from breath hydrogen (H2) measurements, but numerous variables, i.e., dietary fiber source and level of intake, oral hygiene, hyperventilation, and cigarette smoking, stimulate H2 production and may exaggerate estimates of starch malabsorption. With proper controls, however, the lactulose breath H2 test based on total excess volume seems to provide a reasonable measure of the average amount of starch metabolized in the colon. Direct estimates of starch metabolism from human ileostomy studies suggest that typically less than 5% of the ingested starch escapes digestion in the small intestine. The general assumption that starch malabsorption stimulates normal colonic function, particularly with respect to colorectal carcinogenesis, is not entirely supported by the limited number of available epidemiologic studies. Further experimental studies are needed to elucidate the role of starch intake and malabsorption on colonic function and human health issues.
 ...
PMID:Passage of starch into the colon of humans: quantitation and implications. 203 95

The interaction of ethanol with drugs and xenobiotics is complex because ethanol can affect any of the following steps; absorption, plasma protein binding, hepatic blood flow, distribution, hepatic uptake of drugs, and phase I and II hepatic metabolism. The ingestion of ethanol can lead to malabsorption of a variety of nutrients and can modify the absorption of various drugs. High concentrations of ethanol in conjunction with aspirin causes gastric mucosal damage. The principal effect of acute ethanol ingestion on drug metabolism is inhibition of microsomal drug metabolism. The synergistic effects of ethanol on central nervous system depressants can be explained by this mechanism. In contrast, chronic ethanol consumption increases mixed function oxidation and drug metabolism. The cross tolerance between ethanol and sedatives in chronic alcoholics may be due to this effect of alcohol. In addition, enhanced production of hepatotoxic products from certain drugs and xenobiotics and an increased activation of procarcinogens to carcinogens can result from this microsomal induction. The increased susceptibility to hepatotoxins and the enhanced carcinogenesis in the alcoholic may be explained by this fact. Other effects of the interaction between drugs and ethanol are the result of changes in organ susceptibility, best demonstrated for the central nervous system. Subsequently, the presence of liver disease has a great effect on drug metabolism in alcoholics.
 ...
PMID:Alcohol effects on drug-nutrient interactions. 390 40

Nutrition and cancer interact at several levels. Both dietary deficiencies and dietary excesses have been linked with changes in prevalence of certain human cancers. With respect to one particular nutrient, riboflavin, a dietary deficiency may decrease the development of spontaneous tumors in experimental animals but increase carcinogenesis due to certain agents. Cancer itself has profound effects upon nutritional status, and neoplastic tissue appears in general to resist dietary deficiency more effectively than normal tissues. Nutrition has a major role in therapy of cancer, but as an adjunct to the treatment plan rather than as an alternative. Parenteral nutrition, either peripheral or total, can provide support that is critically needed when patients cannot eat or swallow, have obstruction or malabsorption, or are otherwise unable to utilize dietary nutrients in adequate amounts. The advent of home parenteral nutrition now provides a means for long-term rehabilitation of cancer patients.
 ...
PMID:Nutrition and cancer. 641 66

The possibility that anticoagulation with warfarin might inhibit the development of spontaneous metastases from intestinal carcinomas induced by azoxymethane (AOM) was tested in Sprague-Dawley rats with and without 60% distal small-bowel resection (DSBR). Warfarin (0.5 mg/l) was added to the drinking water from 1 week or 12 weeks postoperatively, and thromboplastin times were measured thereafter. AOM was given by 12 weekly s.c. injections (10 mg/kg/week), starting 1 week after DSBR. Besides increasing the sensitivity of rats to warfarin, DSBR itself caused partial anticoagulation, probably because of vitamin K malabsorption: at 30 weeks faecal fat was 59-93% higher, while serum B12 was 40% lower (> 0.05 P > 0.005). Adaptive growth of the jejunum and caecum after DSBR was manifested by 22-76% increases in segmental weight and surface area (P < 0.001). DSBR produced a 4-fold increase in duodenojejunal tumours at 15-25 weeks (P = 0.025) and a 76% increase in colorectal tumours at 25-35 weeks (P < 0.005). Eight of 20 control rats dying after 15 weeks had lymphatic metastases, compared with 0 of 15 rats with DSBR plus warfarin from week 1 (P = 0.005). The overall prevalence of metastases was reduced by both DSBR and warfarin, when assessed independently. Intestinal carcinogenesis induced by AOM is enhanced by the adaptive response to DSBR, but anticoagulation inhibits spontaneous metastases in this model.
 ...
PMID:Effects of anticoagulation and ileal resection on the development and spread of experimental intestinal carcinomas. 742 32

Epidemiological and experimental studies have implicated bile acids (particularly secondary bile acids) as important factors in the development of colorectal cancer. The ileal sodium-dependent bile acid transporter (ISBT) is a crucial player in the enterohepatic circulation of bile acids. Genetic defects in ISBT may result in malabsorption of bile acids and a loss of bile acids into the large intestine, with a resultant increase in the cytotoxic secondary bile acids in the colon. In a case-control study, we investigated the association between two sequence variations in SLC10A2, the gene encoding ISBT, and colorectal adenomas, a precursor lesion of colorectal cancer. The frequency of the missense mutation in codon 171 of exon 3 (a nucleotide transversion from G to T resulting in an alanine to serine substitution) was not significantly different between cases and controls. However, we found a 2-fold higher risk of colorectal adenomas associated with a C-->T nucleotide transition in codon 169 of exon 3 (odds ratio = 2.06; 95% confidence interval: 1.10-3.83). Logistic regression analysis using A171S/169 C-->T haplotypes as the allelic markers showed that among AA wild-type homozygotes for A171S mutation, this C-->T nucleotide transition in codon 169 was associated with a 2.42 times increased risk (odds ratio = 2.42; 95% confidence interval: 1.26-4.63). This initial observation of an association between a polymorphism in the SLC10A2 gene and the risk of colorectal adenomatous polyps would, if confirmed by other studies, support the role of bile acids in the carcinogenesis of colorectal cancer.
 ...
PMID:An association between genetic polymorphisms in the ileal sodium-dependent bile acid transporter gene and the risk of colorectal adenomas. 1153 43

The ingestion of probiotics is associated with various beneficial effects on human health and modifies the physiological homeostasis of the intestinal flora. Probiotics are microorganisms with some particular characteristics: human origin, safety in human use, bile and acid resistance, survival in the intestine, at least temporary colonization of the human gut, adhesion to the mucosa and bacteriocine production. Thanks to these characteristics, probiotics block the invasion of human intestinal cells by the enteroinvasive bacteria. Furthermore, they should be able to stimulate and modulate the intestinal immune response, and to protect and stabilize the mucosal barrier. Finally, the efficacy of probiotics should be evident and documented with valid studies. All their properties should be maintained during processing and storage. Probiotics are usually used to protect the host from pathogens. With regard to this, they are useful in the prevention of antibiotic and traveler's diarrhea and they may play a role in the management of gastric Helicobacter pylori infection. Furthermore, their efficacy in the treatment of infectious diarrhea, in inflammatory bowel diseases, in pouchitis and in food allergy has been shown. Probiotics can improve the symptoms of irritable bowel syndrome and of lactose malabsorption. Finally, it has been suggested that such microorganisms may play a role in the prevention of carcinogenesis and of tumor growth.
 ...
PMID:[Probiotics: history, definition, requirements and possible therapeutic applications]. 1240 63

Probiotic microorganisms have been documented over the past two decades to play a role in cholesterol-lowering properties via various clinical trials. Several mechanisms have also been proposed and the ability of these microorganisms to deconjugate bile via production of bile salt hydrolase (BSH) has been widely associated with their cholesterol lowering potentials in prevention of hypercholesterolemia. Deconjugated bile salts are more hydrophobic than their conjugated counterparts, thus are less reabsorbed through the intestines resulting in higher excretion into the feces. Replacement of new bile salts from cholesterol as a precursor subsequently leads to decreased serum cholesterol levels. However, some controversies have risen attributed to the activities of deconjugated bile acids that repress the synthesis of bile acids from cholesterol. Deconjugated bile acids have higher binding affinity towards some orphan nuclear receptors namely the farsenoid X receptor (FXR), leading to a suppressed transcription of the enzyme cholesterol 7-alpha hydroxylase (7AH), which is responsible in bile acid synthesis from cholesterol. This notion was further corroborated by our current docking data, which indicated that deconjugated bile acids have higher propensities to bind with the FXR receptor as compared to conjugated bile acids. Bile acids-activated FXR also induces transcription of the IBABP gene, leading to enhanced recycling of bile acids from the intestine back to the liver, which subsequently reduces the need for new bile formation from cholesterol. Possible detrimental effects due to increased deconjugation of bile salts such as malabsorption of lipids, colon carcinogenesis, gallstones formation and altered gut microbial populations, which contribute to other varying gut diseases, were also included in this review. Our current findings and review substantiate the need to look beyond BSH deconjugation as a single factor/mechanism in strain selection for hypercholesterolemia, and/or as a sole mean to justify a cholesterol-lowering property of probiotic strains.
...
PMID:Probiotics and the BSH-related cholesterol lowering mechanism: a Jekyll and Hyde scenario. 2457 69

Canagliflozin is an SGLT2 inhibitor used for the treatment of type 2 diabetes mellitus. Studies were conducted to investigate the mechanism responsible for renal tubular tumors and pheochromocytomas observed at the high dose in a 2-year carcinogenicity study in rats. At the high dose (100mg/kg) in rats, canagliflozin caused carbohydrate malabsorption evidenced by inhibition of intestinal glucose uptake, decreased intestinal pH and increased urinary calcium excretion. In a 6-month mechanistic study utilization of a glucose-free diet prevented carbohydrate malabsorption and its sequelae, including increased calcium absorption and urinary calcium excretion, and hyperostosis. Cell proliferation in the kidney and adrenal medulla was increased in rats maintained on standard diet and administered canagliflozin (100mg/kg), and in addition an increase in the renal injury biomarker KIM-1 was observed. Increased cell proliferation is considered as a proximal event in carcinogenesis. Effects on cell proliferation, KIM-1 and calcium excretion were inhibited in rats maintained on the glucose-free diet, indicating they are secondary to carbohydrate malabsorption and are not direct effects of canagliflozin.
...
PMID:Carbohydrate malabsorption mechanism for tumor formation in rats treated with the SGLT2 inhibitor canagliflozin. 2513 Aug 57

Although epidemiological evidence in humans and bile acid feeding studies in rodents implicate bile acids as tumor promoters, the role of endogenous bile acids in colon carcinogenesis remains unclear. In this study, we exploited mice deficient in the ileal apical sodium-dependent bile acid transporter (ASBT, encoded by SLC10A2) in whom fecal bile acid excretion is augmented more than 10-fold. Wild-type and Asbt-deficient (Slc10a2 (-/-) ) male mice were treated with azoxymethane (AOM) alone to examine the development of aberrant crypt foci, the earliest histological marker of colon neoplasia and a combination of AOM and dextran sulfate sodium to induce colon tumor formation. Asbt-deficient mice exhibited a 54% increase in aberrant crypt foci, and 70 and 59% increases in colon tumor number and size, respectively. Compared to littermate controls, Asbt-deficient mice had a striking, 2-fold increase in the number of colon adenocarcinomas. Consistent with previous studies demonstrating a role for muscarinic and epidermal growth factor receptor signaling in bile acid-induced colon neoplasia, increasing bile acid malabsorption was associated with M3 muscarinic and epidermal growth factor receptor expression, and activation of extracellular signal-related kinase, a key post-receptor signaling molecule.
Carcinogenesis 2015 Oct
PMID:Slc10a2-null mice uncover colon cancer-promoting actions of endogenous fecal bile acids. 2621 Jul 40


1 2 Next >>