Biomedical subjects

T A Butler

Publications and source records attributed to T A Butler.

22 records · Page 2Linked to original sources

PubMed1978

[1-11C] DL-valine, a potential pancreas-imaging agent.

There is a great need for a better pancreas-imaging agent. Studies with [1-14C] DL-valine have shown this amino acid to have a high pancreatic specificity in the four animal species examined. The tissue distribution was almost optimal by 30 min after injection, and no carrier effect was observed through a dose of 5 mg/kg. [1-11C] DL-Valine was synthesized in amounts up to 363 mCi using a rapid (T1/2 = 20.4 min for C-11), high-temperature, high-pressure modification of the Bücherer-Strecker amino acid synthesis. Purification was by anion-exchange followed by cation-exchange chromatography. [1-11C] DL-Valine was obtained in a 70% chemical yield with a total synthesis and purification time of 45 min. Studies in animals have demonstrated that it is a potentially useful new agent for clinical pancreatic imaging.

Animals↗

PubMed1977

Tumor location with 1-aminocyclopentane [11C] carboxylic acid: preliminary clinical trials with single-photon detection.

High specific activity [11C] Carboxyl-labeled 1-aminocyclopentane-carboxylic acid ([11C] ACPC) was tested as a tumor-scanning agent in thirty-eight patients. This artificial amino acid clears the blood to a level of less than 12% within 45 min; thus, imaging is possible within the useful life of C-11. [11C] ACPC can be produced in amounts adequate for clinical scanning. Doses between 12 and 45 mCi were given by i.v. injection, and scans obtained only in the single-photon mode gave clinical information on the sites of tumors. There was no evidence of any toxic effects from [11C] ACPC, and the radiation doses as extrapolated from animal data are approximately 0.01 rad per mCi for the whole body and less than 0.06 rad per mCi for the pancreas. In all but five of the 38 patients [11C] ACPC scans were compared with those obtained with Ga-67 citrate. There were 19 positive [11C] ACPC scans and 24 positive Ga-67 scans. The results indicate that [11C] ACPC is likely to be of diagnostic value for cancer patients if used in conjunction with positron tomography instrumentation.

Amino Acids↗

PubMed1976

Carboxyl-labeled 11C-1-aminocyclopentanecarboxylic acid, a potential agent for cancer detection.

Carboxyl-labeled 11C-1-aminocyclopentanecarboxylic acid (11C-ACPC) has been prepared in multimillicurie amounts. The conversion of H11CN to 11C-ACPC (t1/2 = 20.4 min) was accomplished by a rapid (20-min) two-step high-temperature modification of the Bücherer-Strecker amino acid synthesis technique, which should be applicable at other accelerator installations. Purification was by ion exchange techniques. Animal studies have indicated that 11C-ACPC is a potential tumor-localizing agent for detecting cancer in humans by nuclear medicine scanning techniques.

Animals↗

PubMedDate not supplied

Compost age and sample storage effects on maturity indicators of biosolids compost.

Compost product safety and quality assurance are required to meet the needs of the horticultural, agricultural, and silvicultural user markets. At present, there exist no industry-wide sampling and testing protocols for compost products, thus limiting the production sector. The objective of this research was to test three methods for determining compost maturity. The study followed the composting process of a locally successful commercial composting operation that had been producing lime-stabilized biosolids compost in the Washington, DC metro region for 12 yr. Change over time in the dependent variables--Dewar flask self-heating capacity, oxygen uptake rate, and cation exchange capacity (CEC)-during a 57-d composting of lime-stabilized biosolids was studied. Because cold storage at 4 degrees C is recommended when compost samples cannot be tested for maturity immediately, cold storage of up to 11 wk was included as a variable. Mathematical models were developed that predict change in the Dewar flask self-heating capacity, oxygen uptake rate, and CEC with composting time and storage at 4 degrees C. The Dewar flask self-heating test was the most useful indicator of compost maturity. This test showed change throughout the 57-d biosolids composting period while oxygen respirometry did not change after 29 d. The CEC was found to increase with age and storage. Storage effects varied for the different tests. Except for Days 1 and 57, composts continued to stabilize during storage. Testing stored composts may produce erroneous results that suggest the compost is mature.

Agriculture↗