Inhibition of leukocyte adherence by 3-M potassium chloride extracts of human colorectal tumors.

Leukocyte adherence inhibition (LAI) assays were performed to test whether peripheral blood leukocytes (PBL) from patients with colorectal cancer could be inhibited from attachment to a glass surface when tumor-associated antigens (TAA) of human colorectal tumors were present. The assays were performed with PBL from 41 patients with adenocarcinoma of the colon or rectum with 3-M KCl extracts of colorectal tumors. The results demonstrated the presence of colorectal TAA in the 3-M KCl extract of colorectal tumor materials. The reactivity of leukocytes from patients with a favorable prognosis showed an increasing LAI trend; the reactivity of leukocytes from patients with an unfavorable prognosis had a decreasing LAI trend. In individual patients, alterations in the sequential LAI results paralleled changes in the clinical status, which thus strongly indicated that the LAI assay could be of value in the assessment of antitumor immunity.

Carbon-11-labeled amino acids for the rectilinear and positron tomographic imaging of the human pancreas.

Modification of the Bücherer-Strecker amino acid synthesis facilitated the production of DL-[11C]tryptophan and DL-[11C]valine for clinical trials in patients with proven or suspected pancreatic disease. Examples of rectilinear scans and tomographic images of the pancreas are presented in this initial paper. Positron computed tomography was done with the ORTEC ECAT system. Rapid localization of these C-11-labeled amino acids and fast clearance from the plasma permit almost immediate examination following i.v. injection. Illustrative images include the normal pancreas, pancreatitis, and pancreatic carcinoma. The use of positron tomobraphy with C-11-labeled DL-tryptophan and DL-valine appears to offer a new and promising diagnostic modality for the detection and study of pancreatic diseases.

Comparison of Clostridium difficile detection by monolayer and by inhibition of nucleoside uptake.

Detection and identification of Clostridium difficile toxin by traditional monolayer assay were compared with results obtained by a new procedure based on toxin-dependent inhibition of target cell uptake of a radioactive nucleoside. A high degree of correlation was noted between the two determinations. Although the new procedure was quantitative and objective, its value is seen at present as a rapid screen that may support results obtained in monolayers and as a potential assay for other, currently unidentified, toxins.

Differentiation of retroperitoneal tumor using positron emission computed tomography.

Positron emission computed tomography (ECT) with 11C-DL-tryptophan and 11C-aminocyclobutanecarboxylic acid (11C-ACBC) has produced some promising results in patients with retroperitoneal masses. This brief report gives an example of one patient in whom a retroperitoneal mass could not be differentiated from the pancreas by transmission computed tomography but was suspected to be of pancreatic origin based on arteriographic findings. The ECT scans with 11C-DL-tryptophan showed a normal pancreas, whereas the tumor localizing agent 11C-ACBC concentrated in a tumor surrounding the tail and body of the pancreas. This approach with dual radiopharmaceuticals for the differentiation of metabolically active neoplasms and normal tissues warrants further investigation.

Immunologic studies of colonic cancer: evaluation of immunocompetence.

Detailed immunologic studies were done on 29 patients with colorectal cancer. The plasma level of circulating carcinoembryonic antigen, the in vitro reactivity of the peripheral blood leukocytes (PBL) to colorectal-tumor-associated antigens (CTAA), and the competence of the T cell population were determined. The in vitro reactivity of the PBL to CTAA was determined by a lymphoblastic response and leukocyte migration inhibition. The competent T cell population was determined by enumerating the T and B cells, the rosette-inhibiting titer of antithymocyte globulin, and the reactivity to skin test antigens. An arbitrary score ranging from 0 (low immunocompetence) to 100 (high) was assigned to the results of each test. The mean score on the immunocompetence quotient (ICQ) which ranged from 22 to 100 was judged to reflect the immunocompetence. The sequential ICQ of individual patients strongly suggested that this information reflected the immunocompetence of patients with cancer of the colon.

Sequential carcinoembryonic antigen levels. A predictor of response and relapse in combination chemotherapy of advanced gastrointestinal cancer.

Serial determinations of plasma carcinoembryonic antigen (CEA) levels were assayed for 34 patients with advanced gastrointestinal cancer undergoing 5-fluorouracil and mitomycin C combination chemotherapy. 21 patients (62%) had an objective response and the CEA level was decreased in 12. After chemotherapy was initiated a rise in CEA level occurred on the average 6.5 months later, while the mean time to clinical relapse was 8 months. 5 patients (15%) had stable disease; the CEA level was decreased in 2. In 8 patients (24%) with progressive disease, the mean time for a rising CEA level was 3 months. In our view, a change in the CEA level reflects the effectiveness of combination chemotherapy in patients with advanced gastrointestinal cancer.