Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.31 (beta-glucuronidase)
 7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To investigate the mode of action of sc injected intestinal carcinogens, the mutagenicity assay of bile collected from noninbred Sprague-Dawley rats treated sc with carcinogens was conducted in the presence and absence of beta-glucuronidase. The bile samples from rats inoculated with 4-aminobiphenyl were mutagenic for Salmonella typhimurium TA100 only in the presence of beta-glucuronidase, whereas those from the 3,2'-dimethyl-4-aminobiphenyl-treated rats did not require the enzyme for mutagenicity toward strain TA100. On the contrary, the assays with S. typhimurium G46 and TA100 of bile from rats inoculated with 1,2-dimethylhydrazine, azoxymethane, or methylazoxymethanol acetate failed to reveal mutagenicity whether beta-glucuronidase was added or not, though these carcinogens were highly mutagenic for strain G46 in the Salmonella-microsome mutagenicity test and/or in the host-mediated assay.
 ...
PMID:Assay for mutagenicity of bile in Sprague-Dawley rats treated subcutaneously with intestinal carcinogens. 38 11

The purpose of the present study was to investigate whether three different types of dietary fiber, wheat bran, carrot fiber, and citrus pectin, influenced the induction of colorectal tumors produced by 1,2-dimethylhydrazine in rats. In all groups, the tumor yield was high (87 to 97%). In the wheat bran and carrot fiber groups, the incidence of colorectal tumors was not significantly different from that of the group fed on the fiber-free basic diet. The citrus pectin group, however, had a significantly higher incidence of colorectal tumors (p less than 0.001). An increased number of auditory duct tumors was also noted in this group. In a separate experiment, dietary pectin induced a 10-fold increase in fecal beta-glucuronidase activity but did not alter this activity in the bowel wall. It has been suggested that dietary fiber protects against the induction of colorectal tumors, but this was not the case in the experiment. It is possible that the high tumor yield made the demonstration of a weak protective effect of wheat bran impossible. The reason for the increased occurrence of tumors in the citrus pectin group is obscure and will be subjected to further investigation. Fecal beta-glucuronidase activity might be one factor of importance in the activation of the carcinogen.
 ...
PMID:Effect of dietary fiber on the induction of colorectal tumors and fecal beta-glucuronidase activity in the rat. 47 99

The radioactivity of blood, bile, urine and contents of isolated intestinal segments was measured at various periods after 3H-1,2-dimethylhydrazine (3H-DMH) and 3H-1,2-diethylhydrazine (3H-DEH) subcutaneous administration. These experiments have revealed that DMH metabolites entered the intestine both with bile and directly through the intestinal wall. The DMH metabolites entering the bowel as glucuronides are cleaved with beta-glucuronidase of bacterial origin, and as a result of this the alkylation of enterocytes nucleic acids and protein takes place. In totally hepatectomized animals no methylation of enterocyte macromolecules was noted. DEH fails to penetrate the intestinal wall and to alkylate biomolecules of enterocytes, when administered parenterally or per os. Some possible DMH metabolic pathways are discussed, and the dynamics of DNA and protein methylation is analysed in the light of these proposed pathways.
 ...
PMID:[Distribution and mechanism of the carcinogenic action of 1,2-dimethylhydrazine in rats]. 93 46

The radioactivity level in blood, bile, urine and contents of parts of the gastro-intestinal tract in rats was studied after subcutaneous administration of 3-H-1,2-dimethylhydrazine (3-H-SDMH) which induces colonic tumours. The alkylation of DNA, RNA and protein in the intestinal mucosa, liver and kidneys was estimated 1 h to 28 days after 3-H-SDMH treatment from the 3-H-incorporation into these macromolecules. Administration of 3-H-1,2-diethylhydrazine (3-H-SDEH) which does not induce intestinal tumours was made as a control. Fifteen to 30 min after 3-H-SDMH treatment, marked radioactivity was found in blood, bile, urine and in contents of all regions of gastro-intestinal tract. After 3-H-SDMH administration no label occurred in the contents of localized segments of gastro-intestinal tract although it was present in blood, bile and urine. 3-H-SDMH methylated DNA, RNA and proteins of intestinal mucosa, liver and kidney to a high degree. One hour after 3-H-SDMH treatment the incorporation of label into protein of intestinal mucosa was higher than into liver and kidneys. 3-H-SDEH did not alkylate macromolecules in these organs but did so in thymus, spleen and brain, which are target organs for this carcinogen. After total hepatectomy, 3-H-SDMH did not methylate macromolecules of the intestinal mucosa. The following mechanism for the carcinogenic effect of SDMH is suggested. A carcinogenic metabolite of SDMH forms, in the liver, a conjugate with glucuronic acid. This glucuronide enters the gut both with bile and directly via the circulation. Microbial beta-glucuronidase releases the active metabolite which, in turn, alkylates tissue macromolecules.
 ...
PMID:The mechanism of carcinogenic action of 1,2-dimethylhydrazine (SDMH) in rats. 114 Aug 67

The effects of dietary calcium, magnesium, and butterfat on intestinal function and flora in rats initiated with 1,2-dimethylhydrazine (DMH) were studied. Male weanling rats were assigned to six isocaloric diets that varied in their levels of calcium and magnesium (0.25% Ca with 0.05% Mg, 1.0% Ca with 0.05% Mg, or 0.625% Ca with 0.50% Mg) and butterfat (5% or 20%). One-half of the rats in each treatment were injected subcutaneously with DMH weekly for four weeks. This short-term exposure to DMH increased colonic ornithine decarboxylase (ODC) activity and the mass of cecal contents. Ingestion of the high levels of either calcium or magnesium depressed colonic ODC activity and depressed apparent absorption of organic matter, calcium, magnesium, and phosphorus. Ingestion of excess magnesium increased the mass of the cecal contents by twofold, caused hypertrophy of cecal walls, and increased the total amount of protein and total nitroreductase and beta-glucuronidase activity in the ceca of rats. Ingestion of supplemental calcium had less dramatic effects and increased the mass of cecal contents by only 28% and decreased the total amount of protein in the ceca. On the basis of their different effects on cecal microflora, magnesium appears to have less potential than does calcium as a protective agent against colon cancer.
 ...
PMID:Changes in intestinal function of rats initiated with DMH and fed varying levels of butterfat, calcium, and magnesium. 230 74

The effect of feeding psyllium husk, a water-soluble fiber, and cellulose, a water-insoluble fiber, against chemically induced colon cancer was investigated in rats. Adult male rats were fed semipurified diets containing 20% fat, no fiber, or 10% psyllium husk or cellulose for 22 weeks. Tumors were induced in one-half of the rats fed each diet by the gastric intubation of 1,2-dimethylhydrazine (DMH) during Weeks 3-11. In terms of the number of animals with tumors in each group, psyllium strongly reduced the tumorigenicity of DMH and cellulose moderately reduced tumorigenicity, whereas the two fibers did not differ significantly from each other with respect to tumorigenicity. Psyllium-fed rats had the highest fecal aerobic counts, lowest beta-glucuronidase, and highest 7-alpha-dehydroxylase activities. The psyllium diet also resulted in increased fecal output and percent moisture. Rats fed cellulose tended to have greater fecal bulk and lower beta-glucuronidase activity compared with rats fed no fiber and lower 7-alpha-dehydroxylase activity compared with rats fed psyllium husk.
 ...
PMID:Reduction of DMH-induced colon tumors in rats fed psyllium husk or cellulose. 281 29

The fecal microflora enzymes, beta-glucuronidase and beta-glucosidase, as well as fecal bacterial counts, were examined during colon carcinogenesis in rats administered parenteral 1,2-dimethylhydrazine and fed nutritionally equivalent diets free of fiber or containing one of three single sources of dietary fiber (cellulose, hemicellulose, and pectin). Whereas pectin-fed animals had increased fecal beta-glucuronidase activities, those fed cellulose and hemicellulose, two fibers protective in dimethylhydrazine colon neoplasia, had decreased activities. Although fecal bacterial counts were not significantly changed, similar differential changes in fecal beta-glucosidase activity were noted: cellulose but not pectin or hemicellulose feeding was associated with reduced activity. Although cellulose fiber may cause differing physiological effects resulting in a reduction in colonic neoplasia development in this experimental animal model, decreased bacterial metabolic enzyme activation of carcinogens or cocarcinogens may lead to diminished exposure of colonic cells to exogenous or endogenous mutagens.
 ...
PMID:Effects of differing purified cellulose, pectin, and hemicellulose fiber diets on fecal enzymes in 1,2-dimethylhydrazine-induced rat colon carcinogenesis. 301 27

Since it has been demonstrated that a high level of fat is a dietary factor in the etiology of colon cancer, the effect of carrageenan, a polysaccharide extracted from the red seaweeds, on 1,2-dimethylhydrazine-induced colonic tumors in rats fed a semipurified control diet containing an ordinary level of fat was studied. Nevertheless, the enhancing effect of carrageenan on colonic tumors was observed. The rats fed a carrageenan diet had approximately twice the fecal weight compared to the rats fed a control diet. While no significant differences were found in beta-glucuronidase activities in colonic mucosa, liver or plasma in the carrageenan-fed rats and controls, the activity in feces was significantly lower in the carrageenan-fed rats. At least, no beta-glucuronidase activity seemed to be related to the tumor-enhancing effect of carrageenan.
 ...
PMID:Enhancing effect of carrageenan on the induction of rat colonic tumors by 1,2-dimethylhydrazine and its relation to beta-glucuronidase activities in feces and other tissues. 355 59

Albino, outbred 3-month-old rats were given a single s.c. dose of 1,2-dimethylhydrazine dihydrochloride (DMH; 100 mg/kg) and, 6 or 24 h later, an i.v. dose of bovine liver beta-glucuronidase (3 X 10(4) Fishman units). After this treatment, the incidence of tumours of the large intestine and Zymbal gland, and of cystocholangiomas was similar to that found in rats treated with DMH alone; the incidence of malignancies in various other tissues was considerably higher than that in rats treated only with DMH, especially in animals exposed to beta-glucuronidase 24 h after administration of DMH. beta-Glucuronidase itself had no carcinogenic activity. The broadening of the spectrum of malignant tumours produced in DMH-treated rats by administration of beta-glucuronidase indicates that the carcinogenic effect of DMH may be exerted through formation of comparatively stable conjugates of its metabolites and their enzymic release in target tissues. The approach used in this study could be helpful in investigating the formation of conjugates from other carcinogens.
 ...
PMID:Effect of exogenous beta-glucuronidase on the carcinogenicity of 1,2-dimethylhydrazine in rats: evidence that carcinogenic intermediates form conjugates and act through their subsequent enzymatic release. 400 53

The effect of 5% low-methoxylated pectin, high-methoxylated pectin, and guar gum on 1,2-dimethylhydrazine initiation of colon cancer was investigated using groups of 30 rats. The growth of the rats in the different groups was very similar to that of control group fed a fiber-free diet. Both kinds of pectin increased the multiplicity of color tumors, whereas guar gum did not significantly influence carcinogenesis. Bacterial beta-glucuronidase activity in feces and colonic content was the same in pectin-fed rats and controls but significantly lower in the guar gum group. Thus, it was not related to the number of tumors in each group.
 ...
PMID:Effect of two kinds of pectin and guar gum on 1,2-dimethylhydrazine initiation of colon tumors and on fecal beta-glucuronidase activity in the rat. 626 66


1 2 3 4 Next >>