Radiolabeled peptide

Table 3. Selected excimples of radiolabeled peptides as diagnostic radiopharmaceuticals ...

To make these substrates suitable for biological assays, the introduction of functional groups that can be traced with the proper analytical techniques is essential. The use of radio-, fluorescent-, and biotin-labeled lipidated peptides has been reported. The synthesis of fluorescent substrates is chemically straightforward and allows for production of larger quantities than the enzymatic synthesis used for radiolabeled peptides and is thus preferred over the use of radioactive compounds. [1 21] Common fluorescent probes can be introduced by conjugation to a free functional group present in the peptide. The fluorescent moiety is... 

M. A. Stackhouse, D. J. Buchsbaum, S. R. Kancharla, W. E. Grizzle, C. Grimes, K. Laffoon, L. C. Pederson, and D. T. Curiel, Specific membrane receptor gene expression targeted with radiolabeled peptide employing the erbB-2 and DF3 promoter elements in adenoviral vectors, Cancer Gene Ther. 6 209 (1999). 

Alternatively, monoclonal antibodies (Mabs) to the relevant receptors can be used as transport vectors. Anti-insulin (Mab83-7 and Mab83-14) and anti-transferrin (0X26) receptor antibodies have been proposed as efficient and selective BBB transport vectors. The antitransferrin receptor antibody binds to a site removed from the transferrin binding site and therefore does not compete with endogenous transferrin for transport across the BBB. Studies using radiolabeled peptides have shown that significant uptake of a... 

Schreicr, li.. Radiolabeled peptide ergot alkaloids, Helv. Chim. Acta,. 59, 585, 1976. 

There are few examples of the integrated design in radiolabeled peptides. One example is found in the a-melanocyte stimulating hormone (a-MSH) receptor-binding peptides that are expressed on murine and human melanoma... 

Thin layer chromatography studies are carried out on silica gel (aluminium sheets, Merck) in 10 cm strips as the stationary phase. Ammonium hydroxide methanol water (1 5 10) is used as the mobile phase. While the free activity remains at the point of origin (R(= 0), the radiolabelled peptide migrates to an of 0.4. 

The stability of the radiolabelled peptides prepared under the conditions described above was studied. The "Ln-DOTATATE was found to be adequately stable over a period of 7 d at room temperature. The addition of free radical scavengers such as 2,5-dihydroxybenzoic acid (40 mg/mL of the final mixture) was found to be essential for the storage of high specific activity Lu labelled DOTATATE preparations. 

Tables 3.3 and 3.4 summarize the results obtained from the stability studies of the radiolabelled peptides. The preparations were stored under refrigerated or frozen conditions.

The radiolabelled peptide under study was administered to rats as described above. The animals were then placed in separate glass metabolic cages, allowing reliable separation of urine and solid excreta. The animals had free access to standard diet and water. Two hours after injection of the peptide, the rats urinary bladders were emptied manually, and the urine and faeces were collected. The procedure was repeated at 24 and 48 h post-injection. 

TABLE 5.1. EXCRETION PARAMETERS OF RADIOLABELLED PEPTIDES IN PERFUSED RAT KIDNEY... 

WEINER, R.E., THAKUR, M.L., Radiolabelled peptides in the diagnosis and therapy of onclogical diseases, Appl. Radiat. Isot. 57 (2002) 749. 

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