ABSTRACT
Objective[s]: In line with previous research on the development of conjugated bisphosphonate ligands as new bone-avid agents, in this study, DOTA-conjugated alendronate [DOTA-ALN] was synthesized and evaluated after labeling with gallium-68 [[68]Ga]
Methods: DOTA-ALN was synthesized and characterized, followed by [68]Ga-DOTA-ALN preparation, using DOTA-ALN and [68]GaCl[3] [pH: 4-5] at 92-95°C for 10 min. Stability tests, hydroxyapatite assay, partition coefficient calculation, biodistribution studies, and imaging were performed on the developed agent in normal rats
Results: The complex was prepared with high radiochemical purity [>99% as depicted by radio thin-layer chromatography; specific activity: 310-320 GBq/mmol] after solid phase purification and was stabilized for up to 90 min with a logP value of -2.91. Maximum ligand binding [65%] was observed in the presence of 50 mg of hydroxyapatite; a major portion of the activity was excreted through the kidneys. With the exception of excretory organs, gastrointestinal tract organs, including the liver, intestine, and colon, showed significant uptake; however, the bone uptake was low [<1%] at 30 min after the injection. The data were also confirmed by sequential imaging at 30-90 min following the intravenous injection
Conclusion: The high solubility and anionic properties of the complex led to major renal excretion and low hydroxyapatite uptake; therefore, the complex failed to demonstrate bone imaging behaviors
ABSTRACT
Radiolabeled porphyrins are potential tumor avid radiopharmaceuticals because of their impersonation in the human body, ability to complex various radionuclides, water solubility, low toxicity etc. In this work a radiogallium porphyrin complex has been developed. [67Ga] labeled 5,10,15,20-tetrakis [3,4-dimethoxyphenyl] porphyrin [[67Ga]-TDMPP] was prepared using freshly prepared [67Ga]GaCl[3] and 5,10,15,20-tetrakis [3,4-dimethoxyphenyl] porphyrin [H[2]TDMPP] for 60 min at 100°C. Stability of the complex was checked in final formulation and human serum for 24 h, followed by biodistribution and imaging studies in wild type rats up to 24 h. The radiocomplex was obtained with radiochemical purity >99% [ITLC] and >98% [HPLC]], specific activity: 12-15 GBq/mmol. The partition coefficient was determined [log P=1.63]. A detailed comparative pharmacokinetic study performed for 67Ga cation and [67Ga]-TDMPP. The complex was mostly washed out from the circulation through kidneys. Myocardial uptake was significantly observed by SPECT and biodistribution studies. Knee and shoulder joints demonstrated significant activity uptake in 2h post injection. Higher water solubility of the complex due to ionic nature of the complex is an advantage for rapid wash-out of the complex from the system, the complex has significant joint uptake compared to other radiolabeled porphyrins which the mechanisms are explained
ABSTRACT
The urea breath test [UBT] which is carried out with [13]C or [14]C labeled urea is one of the most important non invasive methods for detection of Helicobacter pylori infection. Application of [13]C-UBT is becoming increasingly popular because of its non radioactive nature which makes it suitable for diagnostic purposes in children and women of child bearing ages. While isotope ratio mass spectrometer [IRMS] is generally used to detect [13]C in expired breath, this instrument is expensive and recently non dispersive isotope selective infrared [NDIR] spectroscopy which is a lower cost technique has been employed as a reliable counterpart for IRMS in small clinics. The aim of this study was to assess the validity of NDIR spectroscopy technique in Iranian population in comparison with histological examination, rapid urease test and [14]C-urea breath test as gold standard. Seventy six patients with dyspepsia were underwent [13]CUBT for diagnosis of Helicobacter pylori infection. Good agreements were found between the [13]C-UBT and gold standard methods. The [13]C-UBT showed 100% sensitivity, 97.3% specificity, 97.56% positive predictive value, 100% negative predictive value and 98.65% accuracy. On the basis of these results it could be concluded that [13]C-UBT performed with NDIR spectroscopy is a reliable, accurate and non invasive diagnostic tool for detection of Helicobacter pylori infection in the Iranian population