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Occult blood testing in a large teaching hospital
POSTER ABSTRACTS
(14.6%) colon; 0/11 (0%) Kaposi's sarcoma; 0/4 (0%) testicular; 2/148 (1.4%) hepatoma; 0/58 (0%) melanoma; 7/65 (10.8%) prostate; 3/46 (6.5%) pancreatic. Antibody titers varied dramatically from 2 to over 20. Overall positivity for the 1256 samples tested was 5.8%. Only one of 143 sera from normal blood donors (0.7%) gave a positive response, with a titer of 1.8. Our data are in fair agreement with published prevalence for antibody development in breast (7-9%) and lung (13%) cancer, and lymphoma (21%). We here report for the first time the highest prevalence of anti-p53 antibodies in ovarian and colon cancers. We are currently investigating whether the presence of such antibodies constitute a new diagnostic or prognostic test.
New methodology for measuring anti-p53 a n t i b o d i e s in h u m a n s e r u m Angelopoulou, K. and Diamandis, E.P. Department of Clinical Biochemistry, The Toronto Hospital, Toronto, Ontario, Canada Current methodology for measuring human antibodies against the p53 tumour suppressor gene product are based on the use of radioactive p53 antigen, immunoprecipitation and Western blot analysis. These methods are timeconsuming, cumbersome and unsuitable for screening large numbers of samples. A recently developed assay is based on p53 antigen immobilization through a solid-phase monoclonal anti-p53 antibody and detection of immunoabsorbed anti-p53 human IgG with alkaline phosphatase (ALP)-labeled goat anti-human antibody. The ALP activity is then measured with time-resolved fluorometry (Method A). We here describe a new method (Method B) as follows: Human serum is incubated with a carefully selected amount of p53 antigen (derived from the tumour cell line COLO 320HSR which overproduces mutant p53 protein). During this step any antibodies present will bind the added p53 antigen. This mixture is then assayed for p53 by using a method based on a monoclonal capture anti-p53 antibody (PAb 240) and a polyclonal rabbit anti-p53 antibody. The signal is generated with a goat anti-rabbit antibody labeled with ALP. If the test serum does not contain any p53 antigen binders (e.g. antibodies) there will be generation of signal in the p53 assay due to the added p53 antigen. In the presence of human anti-p53 antibodies, the signal in the p53 assay will be very low because of p53 antigen binding prior to the assay for p53. This method was tested with p53-antibodynegative and positive human sera identified by Method A with excellent agreement between the two methods. Method B has some advantages over Method A: it
CLINICALBIOCHEMISTRY,VOLUME 26, APRIL 1993
identifies p53 binders including antibody classes other than IgG, and it requires about 10-fold less p53 antigen. We propose this method for screening patients with cancer and as a confirmatory test in combination with Method A.
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Occult blood testing in a large teaching
hospital Kostka, P., Luxton, G. and Ali, M. Department of Laboratory Medicine, St. Joseph's Hospital, 50 Charlton Ave. E., Hamilton, Ontario, LSN 4A6, Canada The clinical and diagnostic utility of occult blood testing (OBT) in hospitalized patients was evaluated by retrospective review of medical records of patients admitted to our Hospital. The sample of patients was selected using 106 consecutive requests for occult blood received by the laboratory in the period July - September 1992. Based on clinical presentation, the patients have been categorized into the following groups: patients with anemia (group A), gastrointestinal (GI) symptoms (group G), anemia plus GI symptoms (group AG) and others (group O). The highest frequency of OBT orders was found in group AG (51/106) followed by groups A (29), G (17) and O (9). The AG group of patients had the highest rate of positive OBT (43%) as compared to groups G (35%), A (24%) and O (11%). Out of 14 patients testing positive in groups A, G, and O, 13 patients had a secondary cause of GI bleed such as sepsis (5), medication (4), metastatic cancer (2), or fulminant course of disease (2). In the G and AG groups of patients, 17 out of 28 positive results were associated with conditions of malignancy (8), esophageal bleeding (5), or fulminant course of disease (4). In eight patients with malignant disease and positive OBT, only five had a primary malignancy of the GI tract. Twenty eight patients in groups G and AG tested initially for occult blood were followed by endoscopic examination. The result of OBT was a poor predictor for subsequent endoscopy (12 positive vs. 16 negative results). Conclusion: The OBT was found to be used primarily in the clinical setting of anemia and GI symptoms. However, the diagnostic utility of the test is limited owing to the multitude of conditions resulting in GI bleeding in the hospitalized patients and poor correlation with the performance of other diagnostic procedures.
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S e r u m c l i n i c a l c h e m i s t r y in six c h i l d r e n with primary hyperparathyroidism Lawson, M.L. 1, Kooh, S.W. 1 and Ellis, G.: 1Division of Endocrinology and 2Department of Clinical
129
(14.6%) colon; 0/11 (0%) Kaposi's sarcoma; 0/4 (0%) testicular; 2/148 (1.4%) hepatoma; 0/58 (0%) melanoma; 7/65 (10.8%) prostate; 3/46 (6.5%) pancreatic. Antibody titers varied dramatically from 2 to over 20. Overall positivity for the 1256 samples tested was 5.8%. Only one of 143 sera from normal blood donors (0.7%) gave a positive response, with a titer of 1.8. Our data are in fair agreement with published prevalence for antibody development in breast (7-9%) and lung (13%) cancer, and lymphoma (21%). We here report for the first time the highest prevalence of anti-p53 antibodies in ovarian and colon cancers. We are currently investigating whether the presence of such antibodies constitute a new diagnostic or prognostic test.
New methodology for measuring anti-p53 a n t i b o d i e s in h u m a n s e r u m Angelopoulou, K. and Diamandis, E.P. Department of Clinical Biochemistry, The Toronto Hospital, Toronto, Ontario, Canada Current methodology for measuring human antibodies against the p53 tumour suppressor gene product are based on the use of radioactive p53 antigen, immunoprecipitation and Western blot analysis. These methods are timeconsuming, cumbersome and unsuitable for screening large numbers of samples. A recently developed assay is based on p53 antigen immobilization through a solid-phase monoclonal anti-p53 antibody and detection of immunoabsorbed anti-p53 human IgG with alkaline phosphatase (ALP)-labeled goat anti-human antibody. The ALP activity is then measured with time-resolved fluorometry (Method A). We here describe a new method (Method B) as follows: Human serum is incubated with a carefully selected amount of p53 antigen (derived from the tumour cell line COLO 320HSR which overproduces mutant p53 protein). During this step any antibodies present will bind the added p53 antigen. This mixture is then assayed for p53 by using a method based on a monoclonal capture anti-p53 antibody (PAb 240) and a polyclonal rabbit anti-p53 antibody. The signal is generated with a goat anti-rabbit antibody labeled with ALP. If the test serum does not contain any p53 antigen binders (e.g. antibodies) there will be generation of signal in the p53 assay due to the added p53 antigen. In the presence of human anti-p53 antibodies, the signal in the p53 assay will be very low because of p53 antigen binding prior to the assay for p53. This method was tested with p53-antibodynegative and positive human sera identified by Method A with excellent agreement between the two methods. Method B has some advantages over Method A: it
CLINICALBIOCHEMISTRY,VOLUME 26, APRIL 1993
identifies p53 binders including antibody classes other than IgG, and it requires about 10-fold less p53 antigen. We propose this method for screening patients with cancer and as a confirmatory test in combination with Method A.
[-~
Occult blood testing in a large teaching
hospital Kostka, P., Luxton, G. and Ali, M. Department of Laboratory Medicine, St. Joseph's Hospital, 50 Charlton Ave. E., Hamilton, Ontario, LSN 4A6, Canada The clinical and diagnostic utility of occult blood testing (OBT) in hospitalized patients was evaluated by retrospective review of medical records of patients admitted to our Hospital. The sample of patients was selected using 106 consecutive requests for occult blood received by the laboratory in the period July - September 1992. Based on clinical presentation, the patients have been categorized into the following groups: patients with anemia (group A), gastrointestinal (GI) symptoms (group G), anemia plus GI symptoms (group AG) and others (group O). The highest frequency of OBT orders was found in group AG (51/106) followed by groups A (29), G (17) and O (9). The AG group of patients had the highest rate of positive OBT (43%) as compared to groups G (35%), A (24%) and O (11%). Out of 14 patients testing positive in groups A, G, and O, 13 patients had a secondary cause of GI bleed such as sepsis (5), medication (4), metastatic cancer (2), or fulminant course of disease (2). In the G and AG groups of patients, 17 out of 28 positive results were associated with conditions of malignancy (8), esophageal bleeding (5), or fulminant course of disease (4). In eight patients with malignant disease and positive OBT, only five had a primary malignancy of the GI tract. Twenty eight patients in groups G and AG tested initially for occult blood were followed by endoscopic examination. The result of OBT was a poor predictor for subsequent endoscopy (12 positive vs. 16 negative results). Conclusion: The OBT was found to be used primarily in the clinical setting of anemia and GI symptoms. However, the diagnostic utility of the test is limited owing to the multitude of conditions resulting in GI bleeding in the hospitalized patients and poor correlation with the performance of other diagnostic procedures.
~'~
S e r u m c l i n i c a l c h e m i s t r y in six c h i l d r e n with primary hyperparathyroidism Lawson, M.L. 1, Kooh, S.W. 1 and Ellis, G.: 1Division of Endocrinology and 2Department of Clinical
129