The formation of tissue iodoproteins during the peripheral metabolism of the thyroid hormones was examined by determining the concentration of nonethanol-extractable (125)I (NE(125)I) in various tissues after the intravenous injection of 3,5,3'-triiodo-L-thyronine (T3-(125)I) and L-thyroxine-(125)I (T4-(125)I) in groups of rats with iodide-blocked thyroid glands. 3 days after T3-(125)I and 7 da...

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Introduction: Brachytherapy is one type of internal radiation therapy where radiation sources, which are usually encapsulated, are placed as close as possible to the tumor site or inside the patient's body. In this technique, it is important to determine dose distribution around the brachytherapy capsule to create optimal treatment plant. In this way, dosimetric parameters are...

UNLABELLED We evaluated the use of radiolabeled 4-iodo-L-meta-tyrosine as an amino acid transport marker. The pharmacologic features of this compound, particularly the biodistribution and excretion, were examined by conducting in vivo and in vitro studies using 4-(125)I-iodo-L-meta-tyrosine (4-(125)I-mTyr). Results obtained for L-(14)C-Tyr and 3-(125)I-iodo-alpha-methyl-L-tyrosine ((125)I-IMT) ...

INTRODUCTION High expression of the system L amino acid transporter has been observed in clinically important tissues including tumors and the blood-brain barrier. We examined amino acid transport system L selectivity of (14)C(U)-L-tyrosine ((14)C-Tyr), (125)I-4-iodo-L-meta-tyrosine (4-(125)I-mTyr), (125)I-6-iodo-L-meta-tyrosine (6-(125)I-mTyr), (125)I-3-iodo-α-methyl-L-tyrosine ((125)I-IMT) an...

Cyclooxygenase-2 (COX-2) is an important biomarker in several tumors. Available imaging probes display relatively low tumor to background ratios (smaller than 2:1). We evaluated newly developed indomethacin (Ind) derivatives for in vivo molecular imaging of COX-2 expressing carcinoma. Radioiodinated Ind derivatives Ind-NH-(CH2)4-NH-3-[I-125]I-Bz ([I-125]5), Ind-NH-(CH2)4-NH-5-[I-124/125]I-Nic (...

This study demonstrates that a novel angiotensin I analog, angiotensinogen 3-11(Lys(11)), possesses a high affinity for angiotensin-converting enzyme (ACE), which is substantially greater than the endogenous substrates. This assessment is based on data derived from a variety of techniques. First, the binding characteristics of (125)I-angiotensinogen 3-11(Lys(11)) were examined. Equilibrium satu...

The binding characteristics of corticotropin-releasing factor (CRF) type 1 (CRF(1)) and type 2 (CRF(2)) receptors from human (hCRF(1) and hCRF(2alpha)) and Xenopus (xCRF(1) and xCRF(2)) were compared using four different (125)I-labeled CRF analogs, the agonists (125)I-CRF and (125)I-sauvagine, and the antagonists (125)I-astressin ((125)I-AST) and (125)I-antisauvagine-30 ((125)I-aSVG). The hCRF(...