Cavernous haemangioma of the oesophagus.
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Esophageal Neoplasms↗
Biomedical subjects
M H Thompson
Publications and source records attributed to M H Thompson.
The effect of gastric achlorhydria on the urinary recovery of nitrate in man: relevance to urinary nitrate as a measure of dietary nitrate exposure.
It is important to have a reliable method of assessing the dietary nitrate exposure of populations for a proper understanding of the potential health effects of the endogenous metabolites of this ion to be gained from epidemiological studies. Recently we strongly advocated the use of the nitrate analysis of 24 h urine samples as being a superior method for such studies. Our previous observations and those of others relating to nitrate pharmacology in healthy human volunteers formed the basis of this judgement. The purpose of this study was to determine whether gastric achlorhydria or hypochlorhydria has any significant gross effects on the urinary recovery of dietary nitrate and to what extent the inclusion of such individuals would compromise the results of potential epidemiological studies. The results demonstrated a significantly greater loss of dietary nitrate as measured by urinary recovery in achlorhydrics than in normochlorhydrics, presumably as a consequence of bacterial metabolism in the colonized stomach. Thus the average urinary nitrate recovery of a 1.5 mmol challenge was 33% in individuals with reduced stomach acidity as compared to 56% in normal controls. This significant further loss of nitrate (average 23%) when intragastric conditions favour bacterial colonization clearly indicates that for valid assessments and comparisons of nitrate exposure between populations it would be wise to exclude individuals with low levels of stomach acid where this is likely to lead to significant gastric colonization by nitrate-reducing bacteria (i.e. pH less than 4-5).
Achlorhydria↗
Complications of choledochal cysts in adulthood.
Choledochal cyst is a well-recognised entity, presenting primarily in infants and young children. Where symptoms are delayed until adulthood, associated hepatobiliary pathology may complicate the presentation. These problems may be aggravated by previous treatment with bypass surgery rather than resection. We report seven cases from our recent experience presenting with complications in adulthood. These included cholangitis, hepatic abscess, pancreatitis and malignancy within the cyst. Two patients presented during pregnancy. These complications and their implications for management are discussed.
Adenoma, Bile Duct↗
The presentation of malrotation of the intestine in adults.
Three cases of intestinal malrotation presenting in adults are reported. Each illustrates various aspects of symptomatology, investigation and treatment which are discussed.
Adenocarcinoma↗
Diet and fecal steroid profile in a South Asian population with a low colon-cancer rate.
South Asian immigrants to England and Wales have low mortality from colon cancer and high mortality from coronary heart disease compared with the general population. In a survey of a predominantly Gujarati population in northwest London, both vegetarians and nonvegetarians had similar total dietary fat intake to the native British population but higher dietary fiber intake. Total fecal bile acid and neutral animal sterol concentrations were lower in South Asians than in a native British comparison group. Sixty-two percent of South Asians excreted detectable quantities of free primary bile acids, which were not present in stools from native British subjects. The ratio of fecal coprostanol to total neutral animal sterols was also lower in South Asians. Low risk of colon cancer in this population may be related to reduced microbial activity in the bowel and low levels of tumor-promoting secondary bile acids.
Asia, Southeastern↗
The effect of different sources of nitrate exposure on urinary nitrate recovery in humans and its relevance to the methods of estimating nitrate exposure in epidemiological studies.
It was demonstrated that nitrate concentration fluctuates dramatically in both urine and saliva throughout the study period and hence single time point ('spot') samples of either fluid give a poor measure of previous nitrate exposure. In contrast, the nitrate recovery in complete 24 h urine collections showed a strong positive correlation with previous nitrate exposure which was independent of the nature of the food matrix in which the nitrate was ingested. Regression analysis of the data showed that the apparent urinary recovery of 70% appears to consist of 55% arising from the original challenge and a background of approximately 0.22 mmol/day which is independent of the challenge and which may reflect endogenous mammalian synthesis of nitrate. It is therefore important that in future epidemiological studies, in which dietary nitrate exposures are to be determined, that analyses are conducted only on 24 h urine collections. A large inter-individual variation was found in the conversion of salivary nitrate to nitrite presumably mediated by the oral flora. The resulting differences in nitrite formation may be one of the factors determining the level of endogenous N-nitroso compound formation in an individual.
Diet↗
The inhibition of bacterially mediated N-nitrosation by vitamin C: relevance to the inhibition of endogenous N-nitrosation in the achlorhydric stomach.
It has been suggested that endogenously formed N-nitroso compounds are involved in the aetiology of gastric cancer. In the model of gastric carcinogenesis postulated by Correa, gastric atrophy is an important early stage in the progression to carcinoma which results in the loss of stomach acidity, and colonization of the stomach by bacteria. As a consequence of the metabolic activity of these bacteria intragastric nitrite (a precursor to N-nitroso compounds) and possibly carcinogenic N-nitroso compounds become elevated, which may hasten the progression to carcinoma. Vitamin C has been shown to be an effective inhibitor of acid-catalysed N-nitroso compound formation, in vivo and in vitro, and this has been attributed to its relatively rapid reaction with nitrite in contrast to the slower rates of reaction of nitrite with secondary amines. However, N-nitroso compound formation in the achlorhydric stomach must proceed by mechanisms which operate at neutral pH values. One potential mechanism involves the enzymatic catalysis of N-nitrosation by a subpopulation of the bacteria colonizing the achlorhydric stomach which catalyse these reactions and in particular denitrifying organisms. In this study, we examined the effect of vitamin C on the formation of N-nitrosomorpholine from morpholine and nitrite when mediated by cells of an actively N-nitrosating denitrifying bacterium (Pseudomonas aeruginosa, BM1030) at neutral pH. Despite the fact that vitamin C ordinarily shows little reactivity towards nitrite at neutral pH it did prove to be a potent inhibitor of bacterial N-nitrosamine formation. This study provides some justification for the use of vitamin C as an inhibitor of endogenous N-nitrosation regardless of gastric pH.
Ascorbic Acid↗
Normal G2 chromosomal radiosensitivity and cell survival in the cancer family syndrome.
Recent reports have suggested that elevated chromosomal aberration yields following X-irradiation of skin fibroblasts in the G2 phase of the cell cycle are characteristic of affected members of cancer-prone families. These studies propose that this phenomenon is a consequence of impaired DNA repair and might be a useful predictor of genetic susceptibility to cancer. We have tested G2 chromosomal X-ray sensitivity in skin fibroblasts and peripheral blood lymphocytes from members of a kindred with the cancer family syndrome, a disorder in which susceptibility to colon cancer and other epithelial cancers is inherited in an autosomal dominant pattern. Further, using a cell survival assay, we tested cancer family syndrome skin fibroblasts for sensitivity to four classes of mutagens, including X-rays. In the assays used, skin fibroblasts and lymphocytes from both affected and unaffected family members exhibited responses indistinguishable from normal controls. Karyotypic analysis of lymphocytes and fibroblasts revealed no consistent constitutional cytogenetic abnormality. Thus, affected patients with the cancer family syndrome do not have increased sensitivity to irradiation and chemical mutagens and lack a germ-line chromosomal defect.
Cell Survival↗
Use of drains after cholecystectomy.
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Adult↗
Are duodenal diverticula associated with choledocholithiasis?
The results of 250 consecutive ERCP examinations were analysed in order to assess whether or not juxtapapillary duodenal diverticula are associated with choledocholithiasis. Cholangiography showed common bile duct stones in 71 patients of whom 25 (35%) had periampullary diverticula. Clear bile ducts were shown in 99, of whom only 12 had diverticula (12%) (p less than 0.05). After allowing for the differences in age between the two groups, patients with choledocholithiasis were 2.6 times (95% CI: 1.14-5.93) more likely to have a periampullary diverticulum than patients without choledocholithiasis. In the remaining 80 patients, cholangiography was either not successful or not indicated. Further clinical follow up and/or investigation have failed to reveal duct stones in any and only 10 (13%) of these 80 patients had diverticula. Overall, 47 patients had diverticula: 25 (53%) had duct stones, four may have had stones and 18 had none. Three or more years after cholecystectomy 59% of patients with duct stones had diverticula, while only 13% with clear ducts had them. These results show a significant association between periampullary duodenal diverticula and choledocholithiasis.
Adolescent↗
Faecal steroid loss in healthy subjects during short-term treatment with ursodeoxycholic acid.
Faecal steroid loss in healthy subjects during short-term treatment with ursodeoxycholic acid has been investigated. The data shows conclusively that lithocholic acid, a known co-mutagen and co-carcinogen is the major bacterial metabolite of ursodeoxycholic acid in the human intestine. Although ursodeoxycholic acid is now the drug of choice for dissolution of cholesterol gallstones, elevation of intestinal lithocholic acid may have long-term repercussions since it has been demonstrated that a high faecal lithocholic acid: deoxycholic acid ratio shows a positive correlation with the incidence of colorectal cancer.
Bile Acids and Salts↗
The importance of the ratio of lithocholic to deoxycholic acid in large bowel carcinogenesis.
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Animals↗
Fecal steroids and colorectal cancer.
The fecal steroid profiles of healthy subjects were compared with those of colorectal cancer (CRC) patients. The multicomponent profiles did not differ qualitatively in that CRC patients, like control subjects, had similar fecal steroids. The major bile acids detected in fecal extracts were lithocholic acid (LCA) and deoxycholic acid (DCA). The major sterol of animal origin was cholesterol and its bacterial metabolite coprostanol, whereas the major plant sterols were beta-sitosterol, stigmasterol, campesterol, and their corresponding bacterial metabolites. CRC patients excreted higher amounts of total major bile acids (LCA and DCA) than did the control group, but this difference was not significant. However, the LCA-to-DCA ratio was much higher in the CRC group [(1.43, p less than 0.01) compared with the control group (0.72)]. The control group excreted significantly higher amounts of total neutral sterols (p less than 0.001), sterols of animal origin (p less than 0.001), and plant sterols (p less than 0.001) compared with the CRC group; the plant sterols represented a much lower proportion of excreted total neutral sterols in the CRC group (p greater than 0.001) compared with the control group. We propose the following hypotheses. The LCA-to-DCA ratio may be an important discriminant market for CRC susceptibility. The fecal LCA-to-DCA ratio may depend on the differential hepatic synthesis of their respective precursors chenodeoxycholic acid (CDCA) and cholic acid. Hepatic synthesis of CDCA may be increased by more efficient conservation of dietary cholesterol because it has been shown that cholesterol of exogenous origin is the main precursor of this bile acid.(ABSTRACT TRUNCATED AT 250 WORDS)
Bile Acids and Salts↗
Combined anti-muscarinic and H2 receptor blockade in the healing of refractory duodenal ulcer. A double blind study.
The purpose of this study was to determine if pirenzepine and cimetidine given together was superior to cimetidine alone in inducing healing of refractory duodenal ulcers which remained unhealed after treatment with cimetidine or ranitidine for at least eight weeks. One hundred and thirty one patients from six centres were randomised to receive either cimetidine (C) 800 mg daily or cimetidine 800 mg plus pirenzepine (C + P) 100 mg daily under double blind conditions for six weeks. The healing rate was similar in both groups, irrespective of the method of calculation. On an intent-to-treat analysis, healing was: C 66%, C + P 57%, and amongst the patients who completed treatment, healing was 70% in both groups. Patients on C and on C + P experienced a similar decrease in daytime and in night time pain. Side effects of treatment, notably dry mouth and blurred vision, were reported more often by patients on combination therapy. Combined treatment with cimetidine plus pirenzepine in patients with refractory duodenal ulcer is unlikely to be beneficial.
Adult↗
Bacterially mediated N-nitrosation reactions and endogenous formation of N-nitroso compounds.
Results are presented demonstrating some factors that affect the kinetics of bacterially mediated N-nitrosation reactions. Two groups of bacteria, differing in their nitrate/nitrite metabolism, are contrasted. These findings are discussed in relation to a role for bacteria in endogenous N-nitrosation reactions.
Bacteria↗
Influence of endoscopic papillotomy on the management of bile duct stones.
In a 4 year period two hundred and seventy-nine patients were treated for gallstones in a single surgical unit. One hundred and thirteen were treated for stones in the bile duct, of them 49 patients were treated surgically and 64 endoscopically. Twenty-three patients had papillotomy without previous cholecystectomy. There were two deaths, both after surgery following failure of endoscopic treatment. Morbidity was greater in the surgically treated group. It is concluded that a large proportion of patients with bile duct stones can be treated by endoscopic papillotomy.
Ampulla of Vater↗
Steroids and cancer: faecal bile acid screening for early detection of cancer risk.
The analyses of faecal bile acids in colorectal cancer patients, breast cancer patients and healthy control subjects is described. Faecal excretion of total bile acids was similar in the three groups. The major bile acids detected were lithocholic acid (LCA) and deoxycholic acid (DCA) and the proportions of these (LCA:DCA ratio) were diametrically opposed in the colorectal cancer patients (1.91 +/- 0.33) and control subjects (0.90 +/- 0.09). Patients with adenocarcinoma of the breast also exhibited a higher LCA:DCA ratio (1.24 +/- 0.10) than the control group. The faecal LCA:DCA ratio is an important marker of cancer risk especially cancer of the large bowel and it is suggested that it may be a useful adjunct to future screening procedures.
Bile Acids and Salts↗
Endoscopic papillotomy without cholecystectomy for bile duct stones.
Endoscopic papillotomy without cholecystectomy has been performed in 20 elderly patients with complications of bile duct stones. Good biliary drainage was achieved in 17, and there were no complications. One cholecystectomy was subsequently required. Later deaths have been due to unrelated causes. It is concluded that endoscopic treatment alone may be all that is required to manage bile duct stones in the elderly.
Aged↗