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M Tobi

Publications and source records attributed to M Tobi.

At least 37 records · Page 2Linked to original sources
PubMed1995

Sampling method as a key factor in identifying K-ras oncogene mutations in preneoplastic colorectal lesions.

The development of sensitive polymerase chain reaction (PCR)-based techniques in recent years has enabled us to verify the possible presence of mutated oncogenes and tumor suppressor genes in stages preceding tumor formation. Early detection of mutants serves as a powerful tool for detecting exposure to carcinogens and can assist in diagnosis. In studies performed in the past few years, we have identified mutant ras alleles in preneoplastic samples of patients with and without colorectal cancer. Our studies have shown (i) that mutant ras alleles are present at low incidence in normal appearing tissues of patients with colorectal cancer. Such mutations are also found in colonic effluents of patients at risk for developing this tumor type; and (ii) that the method of sampling is critical to ensure true representation of the entire colonic mucosa. The implications of identifying ras mutations in patients without evidence for neoplasma are discussed.

Biomarkers, Tumor↗
PubMed1994

Detection of K-ras mutation in colonic effluent samples from patients without evidence of colorectal carcinoma.

BACKGROUND: K-ras gene mutation appears in more than 50% of patients with colon tumors. Both its frequency and early appearance may qualify this mutation as a potential biomarker. To enable early detection of mutant K-ras alleles, we had previously developed a sensitive polymerase chain reaction (PCR)-based assay, i.e., enriched PCR, which enables detection of one mutant K-ras allele present within 10,000 normal alleles. Using the enriched PCR, we were able to detect mutant K-ras alleles in "normal-appearing" colonic mucosa in patients with colorectal cancer. PURPOSE: A study was initiated to determine whether mutant K-ras alleles could be identified in colonic effluent samples of patients who may be at risk to develop colorectal cancer. METHODS: Over 9 years, colonic effluent samples were collected prior to routine colonoscopy from 39 patients who were apparently free of colorectal cancer. These samples were collected from patients with a family history of colorectal cancer (n = 7), adenomatous polyps (n = 7), previously resected colorectal cancer (n = 5), inflammatory bowel disorders (n = 13), normal colonoscopic examination (n = 6), and familial adenomatous polyposis (n = 1). All of the samples were double coded and analyzed for K-ras gene mutation. RESULTS: Of the 39 patients, seven were found to harbor mutant K-ras codon 12 alleles. Mutations were found in patients with a family history of colorectal cancer (three of seven), adenomatous polyps (one of seven), previously resected colorectal carcinoma (two of five), and familial adenomatous polyposis (one of one). In one case, effluent was found to harbor a mutant K-ras allele 4 years before the patient was diagnosed with colorectal cancer. CONCLUSIONS: (a) Effluent samples contain enough DNA to be detected with enriched PCR. Such samples may well be representative of the entire colon in general as opposed to a localized area such as that usually analyzed during colonoscopy. (b) K-ras gene mutation can be identified in routinely obtained colonic washings of patients who are at risk of developing colorectal cancer. Such mutations were absent in patients with inflammatory bowel disorders and in those who had undergone normal colonoscopic examinations. Detection of K-ras mutation in colonic washings may assist in identifying patients who may be at high risk for developing adenocarcinoma of the colon. IMPLICATIONS: The ability to examine colonic effluents provides a powerful and convenient source of sampling and may be adapted for future large-scale screening.

Adult↗
PubMed1994

A putative CEA moiety is shared by the cotton-top tamarin (Saguinus oedipus) and humans.

CEA-like molecules immunologically distinct from those in humans have been described in non-human primates. These primates do not share the human predilection for colitis and subsequent development of colorectal cancer. CEA expression has not been fully evaluated in a lower-order primate, the cotton-top tamarin (Saguinus oedipus), an animal model for colitis and colorectal cancer. We found increased levels of CEA in both colonic washings and tissues of these animals using a commercially available kit, CEA AIA-PACK (Tosoh Medics, Foster City, CA). In contrast, we observed that other CEA kits failed to detect CEA in tamarins. To elucidate the nature of the CEA-like protein detected, we used the two component monoclonal antibodies used in the CEA AIA-PACK kit, and identified the reactive molecules by Western blotting. A band of approximately M(r) 50,000 was found to be common to samples from both humans and the tamarins. Minimal binding was observed with NCA antibody. We conclude that a CEA-like molecule shared by humans and tamarins may play a role in the pathogenesis of colitis and cancer in both species.

Animals↗
PubMed1993

Large-bowel mucosal biotransformation activity in persons at high risk for colorectal cancer. A preliminary report.

The transformation of xenobiotics and endogenous compounds to active carcinogens and their subsequent deactivation as an aid to eradication may be important in the etiology of some gastrointestinal cancers. In mammals the gastrointestinal tract has been shown to be an important site of inducible enzyme systems active in mucosal biotransformation, but few data are available in man. The mucosal activity of CYPIA1 (formerly aryl hydrocarbon hydroxylase), a potential carcinogen-activating enzyme, and catechol-O-methyl transferase, a potential carcinogen-inactivating enzyme were determined in colonic tissue obtained by biopsy. There were no significant differences in activity rates in normal mucosa between colorectal cancer and healthy persons, but significant differences are seen in patients with a history of neoplasia with no evidence of recurrence. The levels of activity of these carcinogen-inductive and -protective enzymes may be prognostic markers, in that the balance or imbalance could play a role in the recurrence of neoplasia. This will require confirmation and prospective studies.

Adult↗
PubMed1993

Mucosal origin and shedding of an early colonic tumor marker defined by Adnab-9 monoclonal antibody.

Recent attention has been drawn to the diagnostic potential of tests based on shed colonic tumor markers. Adnab-9 monoclonal antibody raised against neoplastic, potentially premalignant colonic adenomas recognizes a marker in colonic effluent or tissue which correlates with the presence of tumors or risk of colorectal cancer. The origin of this antigen and optimal collection of colonic effluent were investigated by enzyme-linked immunosorbent assay and Western blotting. Mean Adnab-9 binding in effluent samples from colorectal cancer patients even after resection is high as compared with that in normal subjects (P < 0.05). Effluent samples are best collected in the morning hours. Antigen proteolysis may be significant depending on the site and timing of effluent collection, but breakdown products are reactive. Tissue and effluent Adnab-9 binding at any one anatomic site of collection appear to correlate (r = 0.88, P = 0.01). The Adnab-9 antigen is constitutively expressed at low levels throughout the distal bowel and localized to the deepest regions of the mucosal crypts. Other than meconium, no significant levels of binding are found in other body fluids. This antigen is specific for the gastrointestinal tract, its binding in conveniently collected effluent samples correlates with tissue content, and the antigen is constitutively expressed in the crypts of the distal small bowel and colonic mucosa.

Adult↗
PubMed1992

Detection of carcinoembryonic antigen in colonic effluent by specific anti-CEA monoclonal antibodies.

To characterize the CEA in colonic effluent, anti-CEA monoclonal antibody COL-4 was used in a qualitative radioimmunoassay in both fractionated and unfractionated colonic effluent. Both effluent samples and tissue extracts, were subjected to Western blotting and tissue sections to immunohistochemistry. Quantitative levels of colonic effluent CEA were determined by a kit (Abbott-EIA). Higher mean values of COL-4 binding activity were seen only in patients with a past history of polyps (P < 0.01). Quantitated CEA correlated with the presence of colorectal cancer (CRC) as compared to normal subjects, (1133 +/- 875 vs. 459 ng/ml +/- 602, P < 0.05) but not when standardized for protein content. COL-4 reacted with an 180,000 M(r) CEA in the effluent and activity was associated with membrane fraction of the effluent, but bore no relation to the immunohistological staining. We conclude that CEA is detectable in colonic effluent and is membrane associated, but the overlapping values in effluent samples do not make this a useful test in the diagnosis of CRC.

Antibodies, Monoclonal↗
PubMed1992

Adenoma-derived antibody, Adnab-9 recognizes a membrane-bound glycoprotein in colonic tissue and effluent material from patients with colorectal neoplasia.

The binding in pre-colonoscopic effluent of Adnab-9, a monoclonal antibody raised against colonic adenomas, was evaluated for specificity in the diagnosis of colorectal cancer. A heterogeneous group of 58 patients was evaluated by ELISA. Effluent samples and tissue extracts were subjected to Western blotting or ELISA to confirm specificity. Immunohistochemistry was performed on the cancer tissue sections. The proportion of positive effluent binding was higher in the cancer when compared to the normal group (P = 0.036). A dominant 87 M(r) band was found in adenoma extracts and some effluent samples. Adnab-9 binding in effluent samples predominated in membrane-bound fractions. Immunohistochemistry showed no specific staining in the cancer cells. The antigen recognised is a glycoprotein shown by effects of N-glycanase digestion and not cross-reactive with carcinoembryonic antigen. Non-gastro-intestinal tissue extracts did not bind Adnab-9. The major 87 M(r) adenoma-derived antigen may be found in effluent material, particularly in the membrane-bound fraction.

Adenoma↗
PubMed1992

Spontaneous nonfistulous barium reflux into the biliary tract: association with duodenal ulcer disease. A report of four cases.

Reflux of barium into the bile duct system during a barium study of the upper gastrointestinal tract is rare in the absence of spontaneous or postoperative fistula. We report four patients, three men and one woman, who had such reflux, associated with active duodenal ulcer disease, shown at radiologic and endoscopic investigation. Reflux of gastrointestinal contents into the biliary tract can result from peptic ulcer disease with duodenal involvement. The finding does not necessarily imply fistulous communication, ulcer perforation, or surgical emergency.

Adult↗
PubMed1992

Cellular distribution of a colonic adenoma-associated antigen as defined by monoclonal antibody Adnab-9.

Adenomatous colonic polyps constitute a precursor for colorectal cancer. Antibodies to these precancerous lesions might identify specific early tumor antigens. Adnab-9 is a murine monoclonal antibody raised against membranes of colonic adenomas. Adnab-9 binding in colonic washings (effluent) correlates with the presence of colorectal cancer. Immunohistochemical staining with Adnab-9 shows cytoplasmic reactivity in scattered cells in 4 of 31 adenomatous tissue sections, 0 of 14 sections of colorectal cancer cells, and 1 of 8 normal-appearing colonic mucosa specimens examined. Adnab-9 recognized a dominant M(r) 87,000 protein species in tissue extracts in the membrane-bound fraction of effluent by Western blotting. Adnab-9 binding by enzyme-linked immunosorbent assay in adenomatous extracts is higher than cancer or normal tissue, is membrane-bound, and is absent from established colorectal cancer cell lines. This distribution and nature of immunostaining suggest that Adnab-9 recognizes a determinant associated with the membrane component of a subpopulation of adenoma cells which may have a role in early colorectal neoplasia.

Adenoma↗
PubMed1991

Oral colon lavage solutions containing polyethylene glycol may interfere with ELISA detection of tumor-associated antigens in colonic effluent.

Immunologic methods for detection of colorectal neoplasia based on examination of stool or colonic effluent are being developed. Most current oral lavage preparations contain polyethylene glycol (PEG), and if PEG adversely interferes with immunologic testing these tests may become less useful. We describe a decrease in sensitivity of ELISA for tumor-associated antigens (TAA) when effluent samples are diluted in PEG-electrolyte lavage solution, equivalent to a commonly used oral lavage solution based on PEG. Radioisotope-labeled antigen binding to plastic plates was decreased by dilution in the PEG lavage solution. Antigen binding, present in colonic effluent collected by the laxative purge method, was absent in effluent collected by PEG oral lavage from the same patient. We conclude that PEG and PEG-containing lavage solutions interfere with ELISA detection of TAA in colonic effluents. We speculate that the in vitro, and possibly the in vivo, effect occurs at the level of antigen binding to the plate either by a steric effect or alteration of charge by the nonpolar properties of PEG.

Absorption↗
PubMed1991

Cancer associated antigen CA19-9 in colonic effluent of patients with neoplasia of the colon and inflammatory bowel disease.

We measured colonic effluent samples from 10 patients with colorectal cancer, 13 with adenomatous polyps, 14 with normal colons and compared them to 10 patients with inflammatory bowel disease by measuring this CA19-9 content. Results showed considerable overlap between the different pathologic categories, making differentiation impossible. A lower level of CA19-9 in the effluent samples from patients with adenomas was noted. These differences were reproducible for assays performed several months apart. CA19-9 may originate from the upper gastrointestinal tract since large amounts are present in pancreatico-biliary secretions. This antigen is therefore not useful in the diagnosis of neoplasia or inflammatory bowel disease using colonic effluent samples as the test material.

Adult↗
PubMed1990

Increased expression of a putative adenoma-associated antigen in pre-colonoscopic effluent of patients with colorectal cancer.

A monoclonal antibody Adnab-9, was raised against antigens derived from benign polyps of the colon. Adnab-9 was tested against pre-colonoscopic effluent material obtained from groups of patients with a macroscopically normal colonscopic examination, histologically confirmed adenomatous polyps and patients with colorectal cancer (CRC). The resultant binding levels displayed little overlap between the CRC group and the normal, and the difference was statistically significant. Since this putative early neoplasia associated antigen is essentially not expressed in CRC extracts, it may originate from a region of the colon predisposed to neoplasia, increasing in expression as the tendency to malignancy progresses, useful in the diagnosis of early stage malignancy.

Adenoma↗
PubMed1990

Massive hepatic infarction in systemic lupus erythematosus.

Liver disease in systemic lupus erythematosus, as demonstrated by abnormal histopathology, is rare and usually mild; typically, this hepatic disease is of chronic nature and not related to a hypercoagulable state. A patient is described in whom life-threatening hypercoagulability in association with systemic lupus erythematosus resulted in extensive liver infarction. Follow-up radionuclide liver scintigraphy suggested that regenerative recovery in the infarcted areas of the liver may be delayed or absent, but there was no evident functional hepatic impairment.

Adult↗
PubMed1988

Acyclovir treatment of the chronic fatigue syndrome. Lack of efficacy in a placebo-controlled trial.

Twenty-seven adults with a diagnosis of the chronic fatigue syndrome were enrolled in a double-blind, placebo-controlled study of acyclovir therapy. The patients had had debilitating fatigue for an average of 6.8 years, accompanied by persisting antibodies to Epstein-Barr virus early antigens (titers greater than or equal to 1:40) or undetectable levels of antibodies to Epstein-Barr virus nuclear antigens (titers less than 1:2) or both. Each course of treatment consisted of intravenous placebo or acyclovir (500 mg per square meter of body-surface area) administered every eight hours for seven days. The same drug was then given orally for 30 days (acyclovir, 800 mg four times daily). There were six-week observation periods before, between, and after the treatments. Three patients had acyclovir-induced nephrotoxicity and were withdrawn from the study. Of the 24 patients who completed the trial, similar numbers improved with acyclovir therapy and with placebo (11 and 10, respectively). Neither acyclovir treatment nor clinical improvement correlated with alterations in laboratory findings, including titers of antibody to Epstein-Barr virus or levels of circulating immune complexes or of leukocyte 2',5'-oligoadenylate synthetase. Subjective improvement correlated with various measures of mood. We conclude that acyclovir, as used in this study, does not ameliorate the chronic fatigue syndrome. We believe that the clinical improvement observed in most patients reflected either spontaneous remission of the syndrome or a placebo effect.

Acyclovir↗
PubMed1988

Hydrogen peroxide induced adenosine diphosphate ribosyl transferase (ADPRT) response in patients with inflammatory bowel disease.

The sample population in this initial case control study of the adenosine diphosphate ribosyl transferase (ADPRT) response of inflammatory bowel disease patients included: 23 patients with ulcerative colitis (UC)-active and inactive, 13 patients with Crohn's disease (CD)-active and inactive, 14 first degree relatives of UC and CD patients, and 19 age-matched controls. Adenosine diphosphate ribosyl transferase activity was determined after one hour incubation with 1% plasma (the constitutive value) or with 1% plasma and 100 microM H2O2 (the activated value) with the resulting difference designated as the induced value. Statistically significant decrease in ADPRT activity was found for the constitutive, activated and induced values in human mononuclear leucocytes of UC and CD patients, compared with controls. The values in the first degree relatives of UC and CD patients were not significantly different from either the control or disease populations, indicating an intermediate ADPRT response. These results may be related to the nature of the immunological response of IBD patients and comparable with similar findings in other diseases with known DNA repair deficiencies--for example, colon cancer.

Adult↗
PubMed1985

Differential responsiveness of cloned mammary carcinoma cell populations to the human recombinant leukocyte interferon enhancement of tumor antigen expression.

We have previously shown that a recombinant human leukocyte interferon (IFN-alpha A)5 can mediate an increase in cell surface tumor antigen expression in human carcinoma cells but not normal cells (Greiner et al., 1984). Such a biological response modifier may prove useful in circumventing the problem of antigenic heterogeneity and could increase the effectiveness of monoclonal antibodies (MAbs) for detection and/or therapy of human carcinoma lesions. These studies also revealed that, within populations of human carcinoma cells, there exist subpopulations which are unresponsive to the antigen-enhancing properties of IFN-alpha A. Utilizing cloned cell populations from the MCF-7 human breast carcinoma cell line, we now report the differential responsiveness to the tumor antigen enhancing and antiproliferative actions of IFN-alpha A. Binding of MAb B72.3 to the 220-400 kd tumor antigen, TAG-72, is increased by IFN-alpha A treatment on the surface of the parental MCF-7 cell line and 2 cloned cell populations. A third MCF-7 clone does not express this antigen either before or after IFN-alpha A treatment, but does express a 90 kd tumor antigen and carcinoembryonic antigen which bind MAbs B6.2 and B1.1, respectively. The level of expression of these 2 surface tumor antigens remained unchanged upon interferon treatment. The growth of the parental MCF-7 cells and the 3 cloned cell lines was, however, inhibited by IFN-alpha A. These cell lines also exhibited approximately the same number of interferon receptors with similar binding affinities for IFN-alpha A. The results demonstrate a dissociation of two biological actions of IFN-alpha A-antiproliferative activity and enhancement of tumor antigen expression within a cloned human carcinoma cell line. Our studies also indicate that the differential response of cloned MCF-7 cells to tumor antigen modulation by interferon involves alterations in the transduction of signals occurring distal to receptor occupancy within the biochemical pathways responsible for the actions of this biological response modifier. In addition, the clonal cell lines we have isolated which differ in their responsiveness to interferon should prove valuable in analyzing the molecular basis of interferon actions and may provide insights into the mechanism by which this compound confers its antitumor activity.

Antibodies, Monoclonal↗