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W C Eckelman

Publications and source records attributed to W C Eckelman.

At least 163 records · Page 9Linked to original sources
PubMed1976

Iodinated bleomycin: an unsatisfactory radiopharmaceutical for tumor localization.

Cobalt-57-bleomycin is a clinically useful tumor-localizing agent, but attempts to label bleomycin (BLEO) with other radionuclides have been made because of the long physical half-life of 57Co. As an alternative labeling approach, we iodinated BLEO both directly on the imidazole ring and indirectly by reaction with N-succinimidyl 3-(4-hydroxy, 3-iodophenyl) propionate. Directly iodinated BLEO retained antibacterial activity, but in tumor-bearing rats it showed a lower tumor-to-blood ratio (2.3) at 2 hr than did 57Co-BLEO (11.8). The antibacterial activity of the indirectly labeled BLEO was markedly reduced and this material showed a tumor-to-blood ratio of 0.55 at 2 hr. The radioiodinated bleomycins are not suitable substitutes for 57Co-BLEO as tumor-imaging radiopharmaceuticals.

Adenocarcinoma↗
PubMed1975

Technical considerations in labeling of blood elements.

The technical difficulties of labeling albumin, red blood cells, white blood cells, and platelets are discussed with respect to the effect of procedual differences on the in vivo fate of the radiolabeled blood element. Albumin can be labeled with 99mTc by a variety of procedures that have not been proved clinically. The labeling of erythrocytes with 51Cr is well defined, but the demand for a better radionuclide has not led to a routine procedure for 99mTc-labeled red blood cells. The procedure for labeling white blood cells and platelets with 51Cr has been established, but the in vivo viability of the cells remains in question. Labeling techniques with other isotopes such as 67Ga and 99mTc are still being developed. Blood elements labeled with 51Cr are by far the best defined species, but much remains to be done with isotopes having better physical properties.

Blood Cells↗
PubMed1975

Extra-osseous localization of 99Tcm-Sn pyrophosphate.

99Tcm-Sn pyrophosphate bone scans of 250 patients referred for skeletal metastatic survey were analysed to determine the frequency of abnormal extra-osseous localization and the various pathological causes. Twenty-six patients demonstrated abnormal extra-osseous concentration. There were three false positives. Sixty-five per cent of the extra-osseous lesions concentrating pyrophosphate were malignant (carcinoma of lung and breast, metastatic hepatic carcinoma, chondrosarcoma) and the remainder were benign lesions, e.g. sarcoidosis, soft-tissue calcification, post-surgical and irradiation sites. An incidental finding was the unusual frequency of accumulation of pyrophosphate in various joints, especially the knees and shoulders in asymptomatic patients above 70 years of age.

Age Factors↗
PubMed1975

Cobalt-labeled bleomycin--a new radiopharmaceutical for tumor localization. A comparative clinical evaluation with gallium citrate.

The efficacy of 57Co-labeled bleomycin as a tumor-scanning agent was evaluated in 50 patients with malignant tumor. In terms of sensitivity, labeled bleomycin was found to be a superior agent for malignant tumor detection when compared with 67Ga-citrate (p less than or equal to 0.005). Maximum sensitivity (96%) was found in epidermoid carcinomas. Because of rapid blood clearance and rapid excretion by the kidneys, interpretation of 57Co-bleomycin scans is facilitated.

Adenocarcinoma↗
PubMed1975

Chemical and biologic properties of isolated radiolabeled bleomycin preparations.

Cobalt-57-bleomycin is a diagnostically useful radiopharmaceutical, but little is known about the nature of its individual fractions in regard to their metal-binding capacity and their in vivo distribution. Bleomycin was separated by high performance liquid chromatography (HPLC) into four major components. These were labeled and the distribution studied in tumor-bearing rats at 2 and 24 hr. In vivo radiochemical purity was also determined. Of the nine HPLC systems studied, Porasil A eluted with a mobile phase of 0.3% ammonium formate in methanol gave the best separation of the fractions. These fractions were copper free and retained their biologic activity and purity. An in vitro competitive binding study of 57Co-bleomycin with either 57Co-human serum albumin (HSA) or 57Co-ethylenediaminetetraacetic acid (EDTA) showed the labeled bleomycin to be a strong chelate. The biologic distribution in tumor-bearing rats showed significantly higher concentration in tumors at 2 hr for fractions A2 and B2 as compared to the bleomycin mixture. The other fractions, A1 and demethylA2, gave lower tumor concentrations than the bleomycin mixture. The tumor-to-blood ratios for A2 and B2 were not significantly different from the bleomycin mixture, suggesting that the concentration of the bleomycin in the tumor was related to blood concentration. Tumor-to-blood ratios of greater than 10:1 at 2 hr were achieved for A2, B2, and the mixture; ratios of greater than 31:1 were achieved at 24 hr for all three. From these data it appears that the major components A2 and B2 are the most useful for diagnostic tumor imaging.

Animals↗