Synthesis and binding of peptide T and aminoacyl derivatives to CD4+ lymphocytes.

1. Peptide T and four other aminoacyl derivatives of this octapeptide were synthesized on solid phase support using the Boc and Fmoc procedures. 2. The octapeptides were modified by chloroacetylation and radiolabelled by halogen exchange with 125I. 3. Purified and crude extracts of lymphocytes were used to determine the binding of the octapeptides at different concentrations.

Gastrointestinal scintigraphy using 99mTc- or 111In-labelled polymer beads.

In order to establish normal and pathological stomach emptying characteristics by external measurement of a radioactive meal using a gamma camera and computer system, it is necessary for the radioactively labelled substance to have the same behaviour in the stomach as the ingested food. Resins containing chelating groups which enable binding to either reduced 99mTcO4- or 111In+3 were tested for their suitability as tracers mixed into solid food. The preparation of such styrene-divinyl-benzene resins containing either triethylenetetramine substituents or the fully carboxymethylated derivatives is discussed, as well as the procedures of labelling with either 99mTc-pertechnetate or 111In-chloride. An evaluation of the resins for gastrointestinal scintigraphy was performed on 3 chacma baboons and a male human volunteer with encouraging results.

Standardisation of tracer and type of meal in the evaluation of gastric emptying and colon transit rates in normal beagle dogs.

The transit 111In-labelled polymer beads of different particle sizes in the stomach and colon of five healthy Beagle dogs was monitored after intake of different kinds of meal by a gamma camera and data processor system. The various meals studied were a solid balanced type of dog food mixed with milk, pure milk, and finally a meal of raw meat. The polymer beads carried triethylenetetramine type functions which efficiently chelated 111In+3 from an aqueous solution of InCl3. These labelled beads were well mixed into the food before being offered to the dogs. Gastric emptying curves from which half-times of emptying (T 1/2) could be obtained are presented and statistically compared. Good quality images with quantification of the colon transit rate also became possible. It appeared that standardisation of the tracer and of the meal is compulsory for relevant and reproducible results.

Detection of abscesses and lymphosarcoma with 111In-deferoxamine mesylate.

Indium-111 deferoxamine was used to delineate induced abscesses or different ages in a baboon, and lymph nodes in a case of canine spontaneous lymphosarcoma, by means of gamma-scintigraphy. Positive results were obtained already 1 hr after administration of the scanning agent, and the lesion-to-background ratio improved progressively with time. The tissue distribution of the radiopharmaceutical was determined in rats, and showed a relatively high isotope retention in the kidneys.