Mohammad Shafiei

Clinical evaluation of antimicrobial peptide [99mTc/Tricine/HYNIC0]ubiquicidin 29–41 as a human-specific infection imaging agent

INTRODUCTION Ubiquicidin (UBI) 29-41 is a cationic synthetic antimicrobial peptide fragment that binds preferentially with the anionic microbial cell membrane at the site of infection. This study was conducted to evaluate the potentiality of [(99m)Tc/Tricine/HYNIC(0)]UBI 29-41 prepared from lyophilized kits as an infection imaging agent in humans. METHODS Seven patients (5 males and 2 females; mean age=55 years; age range=35-75 years) with suspected bone or soft-tissue infections participated in this study. [(99m)Tc/Tricine/HYNIC]UBI 29-41, corresponding to activity in the range 555-740 MBq added to 40 mug of peptide obtained from instant freeze-dried kit formulations with radiochemical purities >95%, was injected intravenously. A 45-min dynamic study was followed by spot views of the suspected region of infection (target) and a corresponding normal area (nontarget). Whole-body anterior and posterior images were also acquired at 30, 60 and 120 min after injection. True- or false-positive or true- or false-negative images were interpreted upon bacterial culture, radiography, clinical tests and bone scanning. RESULTS The biodistribution of [(99m)Tc/Tricine/HYNIC]UBI 29-41 in patients showed rapid accumulation of activity in the kidneys in the first 30 min after injection that gradually declined and accumulated in the urinary bladder. There were positive findings in five studies and negative findings in two. Findings were subsequently confirmed to be true positive or negative. Images showed minimal accumulation in nontarget tissues, with an average target/nontarget ratio of 2.10+/-0.33 in positive lesions at 30 min. CONCLUSION Given its favorable clinical characteristics, [(99m)Tc/Tricine/HYNIC]UBI 29-41 shows promise as a tracer for infection imaging that allows early diagnosis (30 min) of infection.

A 99mTc‐tricine‐HYNIC‐labeled peptide targeting the neurotensin receptor for single‐photon imaging in malignant tumors

In this study, a new neurotensin (NT) analog was labeled with (99m) Tc via HYNIC chelator and tricine as coligand and investigated further. An NT (7-13) analog was prepared, and labeling with (99m) Tc was performed. The internalization rate and biodistribution of radiopeptide were studied in HT-29 cells and nude mice bearing tumor, respectively. Radiolabeling with (99m) Tc was performed at high specific activities (54 MBq/nmol) with an acceptable labeling yield (>95%). In vitro cell line studies showed a specific internalization uptake up to 13.23 ± 0.45% during 4 h which was blocked in the presence of excess cold peptide to 0.83 ± 0.15%. In biodistribution studies, uptake was observed in NT receptor-positive organs so that after 1 h the uptakes in mouse intestine and tumor were 1.23 ± 0.16% ID/g and 1.12 ± 0.11% ID/g, respectively. In animals co-injected with excess cold peptide, reduction uptake in tumor and intestines were 73% (1.10% vs. 0.29% ID/g at 4 h) and 61% (1.22% vs. 0.47% ID/g at 4 h) respectively. Predominant renal excretion pathway with a highest accumulation of activity in bladder was observed for this radiopeptide. This radiolabeled peptide could be a candidate for detection of NT positive tumors.

99mTc-tricabonyl labeling of ofloxacin and its biological evaluation in Staphylococcus aureus as an infection imaging agent

Even in recent decades, one of the major causes of death and unhealthiness in the whole world is infection and inflammation. The use of radiopharmaceuticals is a powerful tool in managing the patients with infectious diseases. In this study, ofloxacin as a second-generation fluoroquinolone has been labeled with [(99m) Tc(CO)3 (H2 O)3 ](+) core to formulate a suitable infection imaging agent. Ofloxacin was radiolabeled with (99m) Tc using carbonyl core. Radioligand chemical analysis involved HPLC methods. Radioconjugate stability and lipophilicity were determined. Binding with Staphylococcus aureus and biodistribution in infected mice for labeled compound were studied. The radioligand was characterized by HPLC, and its radiochemical purity was more than 90%. In vitro stability studies have shown the complex was stable at least 6 h after labeling at room temperature. The n-octanol/water partition coefficient experiment exhibited logP = 1.52 ± 0.21 for (99m) Tc(CO)3 -ofloxacin. The complex showed specific binding to S. aureus. Biodistribution results showed that radioligand had high accumulation in the infected muscle in a mice (T/NT = 2.02 ± 0.12 at 4 h postinjection). On the basis of stability and infection site uptake ratio, suitability of this complex as a radiotracer for imaging of infections is recognized.

Preparation of 99mTc-TRODAT-1 with high labeling yield in boiling water bath: A new formulation

A new formulation for preparation of (99m)Tc-labeled tropane derivative, (99m)Tc-TRODAT-1, which is useful as a potential CNS dopamine transporter imaging agent, was evaluated and characterized. Preparation of (99m)Tc-TRODAT-1 was attained previously by a formulation in which vial has to be autoclaved at 121 °C for 30 min. It is highly desirable to further improve the preparation method by developing a simplified one vial formulation which will be labeled in boiling water bath (95 °C) for 15 min and a high labeling yield will be achieved. A formulation contained 10 μg of TRODAT-1, 20 μg tricine, 40 μg SnCl2 and 20mg manitol was prepared. Labeling was performed at 95 °C for 15 min and radiochemical analysis involved ITLC and HPLC methods. The stability of radioconjugate was checked in the presence of human serum at 37 °C up to 24h. (99m)Tc-TRODAT-1 was prepared with a radiochemical purity of more than 95% and specific activity of 64.3 MBq/nmol. Biodistribution studies of this new formulation in rats revealed similar regional brain distribution as compared with those obtained with the previous preparation in which brain uptake was high in striatum and striatum to cerebellum ratio was high. Requiring no autoclave facility for labeling, this new formulation will significantly improve the using feasibility of this radiopharmaceutical in clinic.

Preparation and evaluation of rhenium-188-pamidronate as a palliative treatment in bone metastasis

OBJECTIVE Rhenium-188-hydroxyethylidene diphosphonate (188Re-HEDP) as a first generation bisphosphonate has been widely used for bone seeking radiopharmaceutical in cases of metastatic bone disease. No study has been yet reported on preparing a complex of 188Re with pamidronate (3-aminohydroxypropylidene-1,1-bisphosphonic acid) (PMA) as a second generation bisphosphonate. Based on this fact, it was hypothesized that a bone-seeking 188Re-PMA radiopharmaceutical could be developed as an agent for palliative radiotherapy of bone pain due to skeletal metastases. METHODS Pamidronate was labeled with 188ReO4- eluted from the alumina based 188W/188Re generator. Labeling was optimized, and radiochemical analysis was performed by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Biodistribution of this radioconjugate was evaluated and verified further in mice. RESULTS 188Re-PMA was prepared successfully in a high labeling yield (˃95%) corresponding to a specific activity of 124MBq/μmol and good in vitro stability, but it is likely to consist of multiple species. In biodistribution studies selective uptake and retention of activity in the skeletal system (0.81±0.25% ID/g and 0.57±0.16 at 4 and 48h in bone post injection respectively) followed by clearance in the soft tissues were observed. CONCLUSION These results show that due to its biological capabilities it would be advantageous to use 188Re-PMA for bone pain palliation therapy.

Synthesis, radiolabeling and bioevaluation of a novel arylpiperazine derivative containing triazole as a 5-HT1A receptor imaging agents

INTRODUCTION It has been recognized that serotonin plays a main role in various pathological conditions such as anxiety, depression, aggressiveness, schizophrenia, suicidal behavior, panic and autism. 1-(2-Methoxyphenyl) piperazine pharmacophore, a fragment of the true 5-HT(1A) antagonist WAY100635, is found in numerous selective 5-HT(1A) imaging agents. In this paper, we have reported the synthesis of a novel derivative of 1-(2-methoxyphenyl) piperazine that is labeled with (99m)Tc (CO)(3) via click chemistry. METHODS The bidentate alkyne, propargylglycine was reacted with phenyl piperazine triazole derivative in the presence of a catalytic amount of Cu (I) to form tridentate ligand. The ligand was radiolabeled with the precursor [(99m)Tc] [(H(2)O)(3) (CO)(3)](+) and characterized by HPLC. The bioevaluation of radio labeled ligand was carried out in rats. RESULTS Triazole complex was labeled by (99m)Tc-tricarbonyl and its radiochemical yield was more than >95% which was determined by HPLC. In vivo stability studies in human serum albumin show a 93% ratio of complex after a 24h period. The calculated partition coefficient (logP) was 0.34±0.02. Receptor binding assays indicated about 70% specific binding of radioligand to 5-HT(1A) receptors. Biodistribution studies have shown brain hippocampus uptake of 0.40±0.08 %ID/g at 30 min post injection. CONCLUSIONS Results indicate that this (99m)Tc-tricabonyl-arylpiperazine derivative has specific binding to 5-HT(1A) receptors and presented suitable characters for its use as a CNS imaging agent.

Labeling and evaluation of 99mTc‐tricarbonyl‐meloxicam as a preferential COX‐2 inhibitor for inflammation imaging

Imaging of inflammation has an important role in dissolving problems in diagnosis and therapy of patients with inflammatory disorders. In this study meloxican as a nonsteroidal anti-inflammatory drug (NSAID) has been labeled with thechnetium-99m-tricarbonyl core ([(99m) Tc (CO)3 (H2 O)3 ](+) ) in order to evaluate its feasibility as an inflammation imaging agent for in vivo use. (99m) Tc-tricabonyl labeling of meloxicam was performed by its incubation with prepared precursor (99m) Tc-tricabonyl and heating in a boiling water bath for 30 min while various range of pH (1-9) was adjusted. The stability of (99m) Tc-tricarbonyl-Meloxicam was checked in human serum at 37 °C, and biodistribution was studied in mice. Labeling yield of 98.1 ± 0.4% was obtained corresponding to a specific activity of 0.14 GBq/µmol. The radioconjugate showed good stability in human serum. Our main achievement was high accumulation of (99m) Tc-tricarbonyl-Meloxicam in the inflammated muscle in mice (T/NT = 3.90 at 4 h post injection) which may diagnostically be beneficial for distinguish sites of inflammation.