Biomedical subjects

P A de Bruin

Publications and source records attributed to P A de Bruin.

12 recordsLinked to original sources

PubMed1991

Decrease in two intestinal copper/zinc containing proteins with antioxidant function in inflammatory bowel disease.

Oxygen derived radicals contribute to tissue injury in inflammatory bowel disease. We measured the content of superoxide dismutase and metallothionein (two endogenous copper and zinc containing proteins involved in radical scavenging) in intestinal resection specimens from 29 patients with Crohn's disease and 12 patients with ulcerative colitis and compared the concentrations with those obtained in the normal mucosa of a control group of 18 patients with colorectal cancer. The superoxide dismutase content was similar in control mucosa and non-inflamed mucosa from patients with inflammatory bowel disease (mean (SEM) 2.13 (0.10) and 2.24 (0.10) mg/g protein, respectively) but was decreased in inflamed mucosa (1.87 (0.08) mg/g protein, p less than 0.005 v non-inflamed mucosa). The metallothionein content was decreased in non-inflamed inflammatory bowel disease mucosa compared with control mucosa (0.23 (0.03) and 0.36 (0.04) mg/g protein, respectively, p less than 0.02) and a further decrease was found in inflamed mucosa (0.17 (0.02) mg/g protein, p less than 0.001 v control mucosa). No differences were found between Crohn's disease and ulcerative colitis and no significant effect of medication or tissue localisation was noted. These findings might indicate a decreased endogenous intestinal protection against oxygen derived radicals in inflammatory bowel disease which could contribute to the pathogenesis of the disease.

Adolescent↗

PubMed1990

Neoplasia-related changes of two copper (Cu)/zinc (Zn) proteins in the human colon.

Cu/Zn-containing proteins have recently become of interest with regard to their relation with malignant disorders. Cu Zn-superoxide dismutase (Cu/Zn-SOD) was found increased in chemically induced tumors of the large bowel whereas metallothionein (MT), containing Zn and some Cu, was shown important for the response of tumors to chemotherapy. In the present study, we evaluated the Cu/Zn-SOD and MT content of normal human colonic mucosa and colorectal carcinomas, obtained from 20 resection specimens, and of 47 adenomatous polyps. The Cu/Zn-SOD content of polyps and carcinomas was significantly (p less than 0.01) elevated when compared to normal mucosa. In the adenomatous polyps the Cu/Zn-SOD content increased significantly with increasing grade of epithelial cell dysplasia, diameter, and presence of a villous component. In the carcinomas no relation was noticed between the Cu/Zn-SOD content and the Dukes' stage or the grade of differentiation. The MT content was significantly decreased in both adenomatous polyps and carcinomas when compared to that in normal mucosa. The MT content was not related to the grade of epithelial cell dysplasia of the polyps, and to the Dukes' stage or the differentiation of the carcinomas. In conclusion, neoplasia of the colorectum is accompanied by an increase in Cu/Zn-SOD and a decrease in MT. These findings support the association between changes in Cu/Zn proteins and malignancy.

Adenocarcinoma↗

PubMed1989

Mucin profiles and potential for malignancy of human colorectal adenomatous polyps.

The mucin histochemical and histologic features of 166 colorectal adenomatous polyps from 124 patients were studied. A majority of the polyps (62%) had a tubular growth pattern whereas 38% showed villous growth. Severe dysplasia was more frequently found in the latter group. A significant correlation (r = 0.27, P less than 0.001) was found between the severity of dysplasia and the size of the polyps. Moreover, the ratio between goblet and columnar cells was also found to decrease (P less than 0.0001) with the severity of dysplasia. Independent of the mucin stain used (periodic acid-Schiff, alcian blue, and high-iron diamine stains), mucin reactive cells were found to be negatively correlated (-0.17 less than r less than -0.44, P less than 0.01) with severity of dysplasia, especially in the tubular adenomas. These findings suggest that evaluation of mucin stain, related to dysplasia, may contribute to the assessment of premalignant and early malignant changes in adenomas of the colon.

Adenocarcinoma↗

PubMed1989

The expression of carcinoembryonic antigen and secretory component in adenomas of the human colon and rectum.

The immunohistochemical staining for carcinoembryonic antigen (CEA) and secretory component (SC) was evaluated in 166 endoscopically obtained colorectal adenomas of 124 patients. Expression of CEA, both in the cytoplasm and on the surface of the epithelial cells, was found to be moderately correlated with the severity of dysplasia in all adenomas. This relation was not observed with the SC expression in the adenomas. Both CEA and SC expressions were found to be increased with the size of the adenomas, but only in the villous adenomas and not in the tubular adenomas. These findings indicate that evaluation of CEA and SC expression does not add much additional information to the known parameters of malignant potential of colonic adenomas, such as dysplasia, size, and pattern of mucosal growth.

Adult↗

PubMed1989

Plasminogen activators in (pre)malignant conditions of the colorectum.

Plasminogen activators have been implicated in the process of tumour growth, invasion and metastatic spread. Recent studies indicate that urokinase (mu-PA) is the major type of plasminogen activator correlated with the evolution of adenocarcinomas of the colon. Comparable changes in the plasminogen activator profile have been found in premalignant conditions of the colon as observed in adenocarcinomas. The feasibility of determining plasminogen activators in endoscopical biopsies may provide diagnostic opportunities for the detection of early malignant changes in the human colon.

Colorectal Neoplasms↗

PubMed1989

Plasminogen activators in endoscopic biopsies as indicators of gastrointestinal cancer: comparison with resection specimens.

In resection tissue samples of colorectal carcinomas, the concentration of urokinase-type plasminogen activator (u-Pa) was found to be significantly higher than in the normal parent mucosal tissue, while there was less tissue-type plasminogen activator (t-PA). u-PA and t-PA were also determined in endoscopic biopsies of colonic and gastric carcinomas, and the results were compared with those of the ultimate resection samples of the same patients, and with the histological evaluation of adjacent biopsies. The ratio of u-PA/t-PA antigen in the biopsies was found to represent a good discriminator between normal and malignant tissue. Nearly all (90%) tumour biopsies had a higher PA antigen ratio than that of the normal tissue biopsies. This discrimination based upon PA antigen measurements in biopsies was similarly efficient in the subsequent resection samples, and showed a good agreement with the histological evaluation. Thus, PA antigen measurements in endoscopic biopsies can be used to detect gastrointestinal malignancy.

Aged↗

PubMed1989

In vitro cellular cytotoxicity in Crohn's disease and ulcerative colitis: relation with disease activity and treatment, and the effect of recombinant gamma-interferon.

In a previous study using total mononuclear cells and lymphocytes, enriched by elutriation centrifugation, of patients with Crohn's disease and ulcerative colitis were found to have a decreased NK cell activity. In the present study the relation with disease activity and treatment, and the effect of recombinant gamma-interferon (gamma-IFN) on NK cell and monocyte cytotoxicity has been studied in 19 patients with Crohn's disease, 11 with ulcerative colitis, two with indeterminate colitis and 12 healthy controls. Patients with active Crohn's disease and active ulcerative colitis were shown to have an impaired NK cell activity compared to the control group. However, no difference was found in the percentage of CD16 (Leu 11+) cells, as determined by fluorocytometry, between patients with active or inactive disease. Moreover, the NK cell impairment was not related to corticosteroid treatment. Recombinant gamma-interferon (gamma-IFN) stimulated significantly the cytotoxic activity of the total mononuclear cells and the monocyte-enriched fraction against all target cell lines, both in patients and controls. No relation was found between the increase in cytotoxicity by gamma-IFN and disease activity in the patients. Stimulation with gamma-IFN demonstrated that the monocyte cytotoxic response of inflammatory bowel disease patients is normal. The present study reveals that the impairment in NK cell activity in patients with inflammatory bowel disease is related to disease activity and therefore suggests to be secondary to the inflammatory process.

Adolescent↗

PubMed1988

Plasminogen activators in the intestine of patients with inflammatory bowel disease.

Plasminogen activators were determined in intestinal tissue, obtained after surgery from patients with Crohn's disease and ulcerative colitis, and compared with normal intestinal tissue from colorectal cancer patients. The activity and quantity of tissue-plasminogen activator (t-PA) was found to decrease with the severity of inflammation in the patients with inflammatory bowel disease. Urokinase (u-PA) activity, however, was not changed compared with controls or in relation with severity of inflammation. In contrast, the level of u-PA antigen was found to be increased significantly in the inflammatory bowel disease tissues and was also related with severity of inflammation. The difference between u-PA activity and antigen in inflammatory bowel disease tissue could be attributed to an increase in inactive pro-u-PA and u-PA-inhibitor complexes. This increase in u-PA and the concomitant decrease in t-PA, are similar to those found in premalignant colonic adenomas, and might be related to the known increased cancer risk in inflammatory bowel disease.

Adolescent↗

PubMed1988

Plasminogen activator profiles in neoplastic tissues of the human colon.

Plasminogen activator (PA) activity, in particular urokinase (u-PA), has been shown to be markedly increased in adenocarcinomas of the colon. Adenomatous polyps were found to be intermediate in their PA activity to normal mucosa and adenocarcinomas. In the present study we evaluated the PA profile in relation to malignancy parameters of the adenomas. Forty-eight adenomatous polyps, obtained by endoscopic polypectomy, were scored according to size, histological type, and grade of dysplasia. In extracts, tissue-type PA (t-PA) and u-PA were determined using a spectrophotometric enzyme assay, antigen assays, and a bioimmunoassay for u-PA. Twenty-five paired samples of normal mucosa and adenocarcinoma were used as controls. Additionally, four hyperplastic polyps were studied by the same methods. The presence of complexes of PA with PA inhibitors was assessed by zymography. A 10-fold increase of u-PA antigen in carcinomas was found as compared to normal tissue. An increase was also noted in u-PA activity, although its extent was less, due to the fact that 74% of u-PA was in the inactive proenzyme form. Adenomatous polyps contained PA activities and antigens intermediate to those of normal mucosa and carcinomas, in accordance with the view that they are precursors in the development of colorectal cancer. Within the adenoma group, no relation was found between PA profile changes and histological type or polyp size. Surprisingly, in a group of four hyperplastic polyps, similar profiles of PA were found as in adenomas. When the u-PA/t-PA antigen ratio was taken as a parameter of developing malignancy, two discrete increases were seen during the adenoma-carcinoma sequence, the first at adenoma formation and the second accompanying the start of invasive growth in polyps with severe dysplasia. Zymography showed that only t-PA was present in complex with specific PA inhibitors, explaining how the decrease of t-PA activity in adenomas and carcinomas could be stronger than the parallel decrease of t-PA antigen, when these were compared with normal mucosa, which contained hardly any complexes.

Adenoma↗

PubMed1988

Natural, lectin- and phorbol ester-induced cellular cytotoxicity in Crohn's disease and ulcerative colitis.

Cellular cytotoxicity of peripheral blood cells was studied in patients with Crohn's disease or ulcerative colitis and healthy controls. The spontaneous cytotoxicity or natural killer (NK) cell activity, evaluated against the erythroleukemia K-562 and the colon cancer CaCo-2 and HT-29 cell lines, of total mononuclear cells and enriched lymphocytes was depressed in Crohn's disease and ulcerative colitis patients compared to the controls. Phytohaemagglutinin (PHA) increased the cytotoxicity in the patients, to a similar maximal level as the stimulated controls. In contrast, the phorbol ester, phorbol-myristate-acetate (PMA), enhanced the cytotoxicity in patients and in controls, but in the patients not to the levels of the controls. No cytotoxicity was observed in the monocyte-enriched fraction both in patients and controls using the same assay system. A similar small but significant stimulation of monocyte cytotoxicity was obtained by PHA and PMA in patients and in controls. In conclusion, inflammatory bowel disease is associated with a depressed NK cell activity in peripheral blood which is not target specific. PHA but not PMA could restore the deficient NK cell activity. Monocytes seem not to be involved in the decreased NK cell activity in patients with inflammatory bowel disease.

Adolescent↗

PubMed1987

Plasminogen activators and tumor development in the human colon: activity levels in normal mucosa, adenomatous polyps, and adenocarcinomas.

Malignant changes are often accompanied by alterations in activity and composition of the plasminogen activators (PA). To study the relationship between PA expression and the development of colorectal cancer, we determined urokinase-type plasminogen activator (u-PA) and tissue-type plasminogen activator (t-PA) activity in normal mucosa (n = 80), adenomatous polyps (n = 76), and adenocarcinomas (n = 71) of the colon. Tissues obtained from surgical resection or polypectomy were analyzed for t-PA and u-PA activity in a specific enzymatic assay using plasminogen, a chromogenic substrate, and selective quenching with monospecific antibodies to both activators. The plasminogen activator activities were found to be changed in adenocarcinomas as compared to normal mucosa. The relative contribution of u-PA (expressed as percentage of u-PA) was raised from 6 to 50% for, respectively, normal mucosa and adenocarcinoma. This change could be attributed to a 3-fold decrease in t-PA activity and a 5-fold increase in u-PA activity in the carcinomas. Adenomatous polyps as a group showed percentages of u-PA [20.2 +/- 1.3 (SE)] which were intermediate as well as significantly different (P less than 0.001) from those of normal mucosa and adenocarcinomas. This observation was strengthened by a gradual rise in the relative contribution of u-PA in four resection specimens containing both adenomatous polyps and adenocarcinomas. Zymography showed the presence of minor quantities of PA-PA inhibitor complexes in the tissue extracts studied. The present study shows that the sequence of normal mucosa-adenomatous polyp-adenocarcinoma in the colon is associated with a parallel change in plasminogen activator activity. Thus, change in the regulation of plasminogen activator activity is an early event in the development of colorectal cancer.

Adenocarcinoma↗

PubMedDate not supplied

The organ-specific induction of DNA adducts in 2-acetylaminofluorene-treated rats, studied by means of a sensitive immunochemical method.

Exposure of cells to chemical carcinogens and mutagens may result in the formation of DNA adducts, which can give rise to mutations in the genome and to cellular transformation. Methods to measure DNA-adduct formation may be useful for 'biomonitoring', to establish exposure of laboratory animals or humans to DNA-damaging agents. For such purposes, immunochemical methods appear to be suitable, because they allow sensitive detection and quantification of DNA adducts in small amounts of sample in a non-radiolabelled form. We have worked out optimal conditions for the detection of DNA adducts by means of competitive enzyme-linked immunosorbent assay (ELISA). This technique involves interaction of soluble antigen, immobilized antigen and antibody. It appeared that the sensitivity of the competitive assay can be improved by lowering the amount of immobilized antigen, adsorbed to the wall of the plastic reaction vessel. On the basis of these observations, suitable conditions were selected for a sensitive quantitative assay of adducts in DNA isolated from various organs of rats, treated (p.o.) with the liver carcinogen 2-acetylaminofluorene (2-AAF). Under the conditions of these experiments, the available rabbit antiserum recognizes the guanosine-AAF adduct with high specificity. A time- and dose-dependent induction of AAF adducts could be measured in liver DNA from exposed rats, whereas the amount of adducts in DNA from spleen and nucleated blood cells remained below the detection limit (1 adduct/10(8) nucleotides). The implications of these findings with respect to the relevance of blood cell biomonitoring for target cell exposure are discussed.

2-Acetylaminofluorene↗