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Query: UMLS:C0009402 (colorectal cancer)
 53,228 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of parenteral and oral iron was examined in the rat 1,2 dimethylhydrazine (DMH) colorectal carcinogenesis model in a series of experiments. Parenteral supplementation of iron was found to augment tumor yield (p = 0.012) and oral iron was found to augment tumor incidence (p = 0.03, when control groups were combined). In addition, phytic acid, a significant component of dietary fiber was found to reverse the augmenting effect of oral iron on tumor yield and incidence (p = 0.09 for both). Furthermore, in a short term DMH nuclear toxicity assay, analysis of the karyorrhectic index (KI), there was no difference in the KI between oral iron and phytate dietary groups (p = 0.53 for the left colon and p = 0.2 for the right colon), implying that iron's effect on colorectal tumor induction takes place during the promotional phase of carcinogenesis and not during initiation. These experiments support the epidemiologic observation that dietary iron may augment colorectal cancer risk and that the mechanism by which dietary fiber diminishes colorectal cancer risk may be the chelation of dietary iron by the phytic acid component of dietary fiber.
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PMID:The effect of iron on experimental colorectal carcinogenesis. 256 Jun 18

A hypothesis is presented to account for the dietary induction and promotion of colorectal cancer. The principal agents are the secondary bile acids, lithocholic and deoxycholic acids, the vitamin K group and ferrous iron complexes. These metabolites may interact to subvert the normal free radical generating mechanisms involved in mucosal defence. Diets high in fat and red meat and low in fibre support a Bacteroides-dominated colonic microflora, which both synthesis and utilises vitamin K2 isoprenalogues or menaquinones as enzyme co-factors. Iron(II) complexes such as haemin from the breakdown of dietary haemoglobin and myoglobin also serve as growth factors for these bacteria and provide a rich source of haem-iron for intestinal uptake. Biliary secretion is stimulated by dietary fat and bile acids are essential for the intestinal uptake of vitamin K and possibly of iron complexes such as haemin. In the mature colonocyte, vitamin K and haemin may initiate redox cycling reactions which liberate superoxide (O2-.). Bile acids can activate the membrane bound phospholipase to liberate arachidonate and diacylglycerol. This leads in turn to the production of more O2-. which can enter the microcirculation and acts as a potent chemoattractant for the neutrophils that line the lamina propria. The released diacylglycerol can activate protein kinase C in the neutrophil membrane to switch on the respiratory burst oxidase system generating yet more O2-. and may stimulate the proliferation of transformed stem cells by a similar protein kinase C mediated mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Free radical generating mechanisms in the colon: their role in the induction and promotion of colorectal cancer? 279 47

Variations in dietary exposure to several minerals may alter the risk of acquiring colorectal cancer. These minerals include selenium, zinc, calcium, sodium, potassium, iron and fluoride. The mechanism by which each of these minerals alters cancer risk is not established. However, as both the epidemiologic and experimental evidence for major calorie sources, fat and protein, being the primary determinants of colorectal cancer risk is weakening, micronutrients may prove to be the primary determinants of risk in human colorectal cancer.
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PMID:Dietary minerals and colon carcinogenesis (review). 329 40

In a multicentre prospective trial 358 patients undergoing curative surgery for colorectal cancer were followed for a median 18.0 months (+/- 7.2 months). The presence or absence of sialomucin in either resection margin was studied using the high iron diamine-alcian blue stain. There was evidence of excess sialomucin at one or other resection margin in 106 patients (29.6 per cent). Apart from sigmoid carcinomas occurring more often in the sialomucin positive group, there were no significant differences in any histological or clinical parameters between groups. Survival analysis for the events 'death', 'local recurrence', and 'all recurrence' was undertaken using the Cox regression model. The best prognostic variables selected in a stepwise fashion for death and all recurrence were 'Dukes' classification', 'sialomucin present' and 'histological differentiation'. The best prognostic variables selected for local recurrence were 'sialomucin present', 'Dukes' classification' and 'histological differentiation'. Sialomucin in a resection margin is an important independent prognostic variable for the development of local tumour recurrence and of subsequent survival for patients with colorectal carcinoma.
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PMID:Influence of sialomucin at the resection margin on local tumour recurrence and survival of patients with colorectal cancer: a multivariate analysis. 329 33

The current status of superoxide dismutase (SOD) is that it is an enzyme with diverse ramifications. This review attempts an understanding of SOD as a structural, functional, and biological entity. Accordingly, the review is in three parts. The first part discusses SOD in terms of protein structure, proceeding from primary to secondary and three-dimensional structure for the three forms of SOD: copper/zinc SOD, manganese SOD, and iron SOD. This is the order of structural knowledge of the enzyme. Iron SOD is an enzyme of prokaryotes and some higher plants. Manganese SOD is an enzyme of prokaryotes and eukaryotes. Copper/zinc SOD is an enzyme of eukaryotes and certain prokaryotes. The evolutionary relationships of the three forms of SOD, the status of the copper/zinc SOD gene in prokaryotes, and the cloning and sequencing of SOD genes are discussed. The second part of the review deals with the catalytic mechanism of SOD in the three forms of the enzyme. Structural and mechanistic conclusions from various spectroscopic studies are critically considered. A detailed picture is given of the active site of copper/zinc SOD. The third part is a review of SOD in the general context of oxygen toxicity. After consideration of the question of superoxide toxicity and superoxide pathology, several areas in which SOD has been investigated or used as a tool in a biochemical, pharmacological, or clinical context are discussed, including population genetics; trisomy 21; development and senescence; the nutritional copper, zinc, and manganese status; hemolysis and anemia; oxygen toxicity in the lung and nervous system; inflammation, autoimmune disease and chromosome breakage, ischemia and degenerative changes; radiation damage; and malignancy. A comprehensive picture is given of measurements of SOD activity in disease states, and the question of superoxide-related disease is considered at several points.
CRC Crit Rev Biochem 1987
PMID:Aspects of the structure, function, and applications of superoxide dismutase. 331 61

Increasing attention has been given to hereditary nonpolyposis colorectal cancer (HNPCC). This report provides medical genetic/pathologic findings on an HNPCC kindred from southern Italy that shows criteria consistent with Lynch syndrome II. An international collaborative effort led to extension of this kindred with disclosure of a potentially new spectrum of phenotypic findings: an excess of gastric carcinoma; complete intestinal metaplasia and chronic atrophic gastritis restricted to the antrum; an apparent excess of colonic mucosal macrophagia, which by special stain appeared to be positive for mucin, with a constant content of both sialo and sulfomucin, a lack of iron, and an inconstant positivity for lysozyme obtained by immunoperoxidase technique; and findings of crypt atrophy of the colonic mucosa. During the relatively short period of investigation of this family, an intensive educational and surveillance program has been mounted in the interest of improving cancer control through direct application of knowledge of natural history and the risk factor evidence through pedigree assessment.
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PMID:New phenotypic aspects in a family with Lynch syndrome II. 358 Oct 33

In a multicentre prospective trial, 281 patients undergoing "curative" resection for colorectal cancer were followed for a mean of 13.6 months (SD 7.2 months). The presence or absence of sialomucin at the resection margin was studied histochemically using the high iron diamine-alcian blue (HID-AB) stain. There were 49 deaths relating to tumour recurrence: 21 in the sialomucin positive group (n = 77) and 28 in the sialomucin negative group (n = 204) (p less than 0.02). Life table survival was correlated against the presence or absence of sialomucin in the resection margin. At the mean follow-up (13.6 months) 85.6% of patients were alive in the sialomucin negative group, and 76.4% of patients were alive in the sialomucin positive group. Regression analysis predicts 32.8% and 18.9% five year survivals for sialomucin negative and positive groups respectively. There was no significant statistical correlation between the presence of sialomucin in the resection margin and the Dukes staging, site or tumour differentiation. The appearance of sialomucin in either resection margin appears to be an early marker of poor prognosis for patients with colorectal cancer.
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PMID:Influence of sialomucins at the resection margin on survival of patients with colorectal cancer. 367 28

It has been suggested that diffuse changes in epithelial mucins may help to identify a subgroup of patients with ulcerative colitis who are at increased risk of developing colorectal cancer. Colonoscopic biopsy specimens were taken from 11 colitic patients shortly before colectomies were performed, in which cancer was identified. These patients were matched to colitic patients without cancer for age, sex, and duration of disease. Sections were stained with high iron diamine and alcian blue (HID-AB), mild periodic acid Schiff, and for peanut lectin binding sugar sequences. The sections were assessed blindly and graded semiquantitatively. Most showed ulcerative colitis in remission or mild active disease. There were no differences between the study and control groups. Metaplastic foci were more common in the group who had cancer. These showed increased staining of mucus by mild periodic acid Schiff and increased binding by peanut lectin to the supranuclear (Golgi) zone. Epithelial dysplasia (detected in four of the patients with cancer showed focal intense binding by peanut lectin to cytoplasm, mucus, and glycocalyx. Although dysplasia differed histochemically from normal tissue, special techniques did not facilitate its diagnosis.
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PMID:Value of mucin histochemistry in follow up surveillance of patients with long standing ulcerative colitis. 370 Jun 73

In a prospective trial, the resection margins of 130 patients who underwent apparently curative resection for colorectal cancers were examined. Sialomucin was markedly increased in 17.0 percent of proximal resection margins and 17.3 percent in distal resection margins. Clinical follow-up has demonstrated four patients who have developed local recurrence of their disease. Three of these patients had increased sialomucin staining in the resection margins at the time of initial surgery. High iron diamine-alcian blue staining of resection margin may identify those patients at risk of developing local recurrence of colorectal cancer or metachronous tumor following apparently curative resection.
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PMID:The sialomucin content of colonic resection margins. 397 29

The prognosis in colorectal cancer is related to the stage of the tumour. Thus, early detection of developing tumours will significantly improve the overall prognosis. This study assessed the histochemical changes in mucus from normal and tumour bearing mucosa to determine possible premalignant changes. Eighty patients with colorectal cancer and ten normal subjects were studied. Biopsies were taken from the tumour and from adjacent 'normal' mucosa and from both resection edges. Sections were stained with high iron diamine-alcian blue to distinguish sulphated from sialomucins. All normal mucosal biopsies showed a predominantly sulphated mucin pattern. By contrast, all 70 tumour mucosal biopsies showed a marked sialomucin staining. In transitional mucosa adjacent to the tumour, 30 patients showed marked increase in sialomucin (2+), 42 a moderate increase (+) and the remaining eight a normal pattern (-ve). Twenty-one (15%) patients had increased sialomucin at either surgical resection margins, all of whom had similar changes adjacent to the tumour, suggesting a wide field change in the mucus pattern. Since these changes in mucus are associated with malignant transformation then estimation of mucus pattern may give early prediction of malignant change in patients at risk of developing primary or recurrent carcinoma.
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PMID:Study of the histochemical changes in mucus from normal and tumour bearing mucosa in patients with colorectal cancer. 402 3


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