Uğur Avcıbaşı

Metabolic comparison of radiolabeled aniline- and phenol-phthaleins with 131I

The metabolic comparison of aniline- and phenol-phthaleins radiolabeled with (131)I ((131)I-APH and (131)I-PPH, respectively) has been investigated in this study. To compare the metabolic behavior of these phthaleins and their glucuronide conjugates radiolabeled with (131)I, scintigraphic and biodistributional techniques were applied using male Albino rabbits. The results obtained have shown that these compounds were successfully radioiodinated with a radioiodination yield of about 100%. Maximum uptakes of (131)I-APH and (131)I-PPH, which were metabolized as N- and O-glucuronides, were observed within 2 h in the bladder and in the small intestine, respectively. In the case of verification of considerably up taking of these compounds also by tumors developed in the small intestine and in the bladder tissues, these results can be expected to be encouraging to test these compounds, which will be radiolabeled with other radioiodines such as (125)I, (123)I and (124)I as imaging and therapeutic agents in nuclear medical applications.

Metabolic comparison of radiolabeled bleomycin and bleomycin-glucuronide labeled with 99mTc.

The metabolic comparison of bleomycin (BLM) and bleomycin-glucuronide (BLMG) radiolabeled with (99m)Tc ((99m)Tc-BLM and (99m)Tc-BLMG, respectively) has been investigated in this study. Quality control procedures were carried out using thin-layer radiochromatography and high-performance liquid chromatography. To compare the metabolic behavior of BLM and its glucuronide conjugate radiolabeled with (99m)Tc, scintigraphic, and biodistributional techniques were applied using male New Zealand rabbits and Albino Wistar rats. The results obtained have shown that these compounds were successfully radiolabeled with a labeling yield of about 100%. Maximum uptakes of (99m)Tc-BLM and (99m)Tc-BLMG metabolized as N-glucuronide were observed within 2 hours in the liver, the bladder, and the spinal cord for (99m)Tc-BLM and the lung, the liver, the kidney, the large intestine, and the spinal cord for (99m)Tc-BLMG, respectively. Scintigraphy and biodistributional studies performed on the experimental animals have shown that radiopharmaceutical potentials of these compounds are completely different. At the same time, uptake of the (99m)Tc-BLMG was found to be better than that of (99m)Tc-BLM.

Investigation of Therapeutic Efficiency of Bleomycin and Bleomycin-Glucuronide Labeled with 131I on the Cancer Cell Lines

The aim of this study is to determine the incorporations of radiolabeled bleomycin ((131)I-BLM) and bleomycin-glucuronide ((131)I-BLMGLU) on PC-3 (human prostate carcinoma cell line), Caco-2 (human colon adenocarcinoma cell line), Hutu-80 (Human Duodenum adenocarcinoma cell line), and A549 (Human lung adenocarcinoma epithelial cell line) cancerous cell lines. For this purpose, BLM and BLMGLU enyzmatically synthesized were labeled with (131)I, quality control studies were done and the incorporation yields of (131)I-BLM and (131)I-BLMGLU on these cell lines were measured. Quality-control studies showed that the radiolabeling yields were obtained as 95% and 90% for (131)I-BLM and (131)I-BLMGLU, respectively. Also, as a result of the cell culture studies, it was found that (131)I-BLM and (131)I-BLMGLU had higher incorporation on PC-3 cells than that of other cell lines. In addition to this, it was reported that the incorporation yield of (131)I-BLMGLU was higher than that (131)I-BLM. At the end of the study, cytotoxicities of BLM and BLMGLU on PC-3 cancerous cell line were inspected and fluorescent images of BLM and BLMGLU were taken on PC-3 cells by using fluorescein isothiocyanate. In conclusion, cell culture studies demonstrated that the incorporation values of (131)I-BLMGLU on the four cell lines were about five to six times higher than (131)I-BLM. Radiolabeled glucuronide derivatives can be used in cancer therapy and tumor imaging, depending on the properties of radioiodine for the β-glucuronidase-rich tissues because glucuronidation leads to rapid and higher incorporation on adenocarcinoma cells.

Radiosynthesis and biodistribution of 99mTc-Sulfamethoxazole: a novel molecule for in-vivo infection imaging

The aim of this study was to prepare 99mTc-Sulfamethoxazole complex and evaluate its efficiency as an infection imaging agent. The Sulfamethoxazole was labeled with 99mTc and its biological efficacy as a potential radio tracer for Staphylococcus aureus infection was investigated in bacterially infected Albino Wistar rats. The radiolabeling yield was found to be 95 ± 3.07% and remained constant at more than 93 ± 0.1% even in serum for 240 min after radiolabeling. 99mTc-Sulfamethoxazole prepared with high yield localized well in the bacterially infected muscle of the rats. 99mTc-Sulfamethoxazole may be developed as a radiopharmaceutical agent to distinguish infection from inflammation by nuclear imaging.

Effectiveness of Linezolid, 127I-Linezolid and 131I-Linezolid Against Methicillin-Susceptible Staphylococcus Aureus by Time Kill Curve Methods

Objective: Linezolid (LNZ) is one of the most effective treatments against Gram positive bacteria. However LNZ resistant intermediate strains have recently emerged in worldwide. The aim of the study was to compare the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum biofilm inhibitory concentration (MBIC) of LNZ, 127I-LNZ and 131I-LNZ against methicillin susceptible Staphylococcus aureus ATCC 35556 (MSSA) biofilms. Methods: LNZ radiolabeled with 131I and cold labeling study with 127I was performed. Radiolabeling and inactive labeling quality-control studies of LNZ were carried out by using TLC (Thin Layer Radiochromatography) and HPLC (High Pressure Liquid Chromatography). LNZ, 127I-LNZ and 131I-LNZ against biofilm-forming MSSA was investigated, using a twofold serial broth microtiter method, biofilm challenge, and bacterial count recovery. Results: The binding yield was obtained to be about 86±2% for radiolabeled LNZ. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration for LNZ, 127I-LNZ and 131I-LNZ ranged from 1 to 2 µg/mL respectively. In time-kill studies LNZ, 127I-LNZ and 131I-LNZ were bactericidal against staphylococci, producing ≥3 Log10 decrease in viable counts (cfu/mL) within 6 h at 2xMIC. Following the biofilm formation on polystyrene U-bottom microtiter plates to investigate the minimal biofilm inhibitory concentration (MBIC) of LNZ, 127I-LNZ and 131I-LNZ was defined as the minimal concentration of antibiotic required to inhibite the biofilm. None of the LNZ, 127I-LNZ and 131I-LNZ killed 100% of biofilm associated cells. Mean cell survival in biofilms treated with 64 µg/mL LNZ, 127I-LNZ and 131I-LNZ (64 µg/mL) was 48%, 49%, and 33%, respectively. Conclusion: Our results show that radiolabeled Linezolid demonstrated that 24 h of exposure to 64 µg/mL, promise in