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    Evaluation of (99m)Technetium-Vancomycin Imaging Potential in Experimental Rat Model for the Diagnosis of Infective Endocarditis
    (Bentham Science Publ Ltd, 2021) Kis, Tuba Tatli; Kose, Sukran; Yilmaz, Osman; Kis, Mehmet; Yurt, Fatma; Acar, Emine; Bekis, Recep
    Background: Infective endocarditis (IE) is an infection of the heart's endocardial surface. In recent years, nuclear imaging methods have gained importance in the diagnosis of IE. The present study aims to investigate the imaging potential of Tc-99m-labeled vancomycin (Tc-99m-Van-comycin) as a new agent that would enable the diagnosis of IE in its early stages when it is difficult to diagnose or has small vegetation in the experimental rat model. Methods: Tc-99m-Vancomycin scintigraphy was evaluated for its accumulation in IE with Staphylococcus aureus performed in an experimental rat model. Serial planar scintigraphic and biodistribution analysis of infected vegetations are compared to rats with sterile vegetations. The heart was identified as an infected organ, the liver was identified as a non-infected organ and the heart/liver uptake ratio (T / NT ratio) was compared between infective endocarditis and sterile endocarditis groups. Results: Planar scintigrams (in vivo measurements) showed more uptake in the heart of rats in the infective endocarditis group compared to the uptake in the heart of rats in the sterile endocarditis group, but this difference was not statistically significant (p>0.05). From the ex vivo measurements, the Tc-99m-Vancomycin heart uptake increased significantly (p = 0.016), liver uptake was significantly decreased (p = 0.045) and the T/NT ratio was significantly higher (p = 0.014) in the infective endocarditis group compared to the sterile endocarditis group. Conclusion: In this experimental study, Tc-99m-Vancomycin scintigraphy ensured the detection of ex vivo infected tissue in a rat model of IE. In addition, the absence of significant Tc-99m-Van-comycin uptake in the sterile endocarditis group indicates that this agent targeted the infected tissue instead of the sterile inflammatory tissue. Finally, this agent should also be evaluated with animal-specific imaging devices.
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    Evaluation of I-131-Pentamidine for scintigraphy of experimentally Leishmania tropica-infected hamsters
    (Informa Healthcare, 2014) Inceboz, Tonay; Lambrecht, Fatma Yurt; Eren, Mine Sencan; Girginkardesler, Nogay; Bekis, Recep; Yilmaz, Osman; Er, Ozge; Ozbilgin, Ahmet
    We aimed to assess the ability of I-131-Pentamidine scintigraphy to detect the lesions of Leishmania tropica infection. An experimental model of cutaneous leishmaniasis was developed. The presence of cutaneous leishmaniasis was confirmed. Pentamidine was radioiodinated with I-131. The radiolabeled pentamidine was validated by the requisite quality control tests to check its radiolabeling efficiency, in vitro stability. I-131-Pentamidine (activity: 18.5 MBq/100 mu l) was injected intracardiacally into infected hamsters. Static whole body images of the hamsters were acquired under the gamma camera at 5 and 30 min, 2, 6 and 24 h following the administration. On the scintigrams, anatomically adjusted regions of interest (ROIs) were drawn over the right feet (target) and left feet (not-target) and various organs. Accumulation of I-131-Pentamidine at sites of infection is expressed as the target to non-target (T/NT) ratio. The results T/NT ratio decreased with time. In concluding the I-131-Pentamidine has poor sensitivity in detection of L. tropica infection.
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    Gold nanoparticle probes: Design and in vitro applications in cancer cell culture
    (Elsevier Science Bv, 2012) Unak, Gulcan; Ozkaya, Feriha; Medine, E. Ilker; Kozgus, Ozge; Sakarya, Serhan; Bekis, Recep; Unak, Perihan; Timur, Suna
    A new architecture has been designed by the conjugation of [(18)F]2-fluoro-2-deoxy-D-glucose ((18)F-FDG), gold nanoparticles (AuNPs), and anti-metadherin (Anti-MTDH) antibody which is specific to the metadherin (MTDH) over-expressed on the surface of breast cancer cells. Mannose triflate molecule is used as a precursor for synthesis of (18)F-FDG by nucleophilic fluorination. For the conjugation of (18)F-FDG and AuNPs, cysteamine was first bound to mannose triflate (Man-CA) before synthesizing of (18)F-FDG which has cysteamine sides ((18)FDG-CA). Then, (18)FDG-CA was reacted with HAuCl(4) to obtain AuNPs and with NaBH(4) for reduction of AuNPs. At the end of this procedure. AuNPs were conjugated to (18)F-FDG via disulphide bonds ((18)FDG-AuNP). For the conjugation of Anti-MTDH, 1,1'-carbonyl diimidazol (CDI) was bound to the (18)FDG-AuNP, and Anti-MTDH was conjugated via CDI ((18)FDG-AuNP-Anti-MTDH). This procedure was also performed by using Na(19)F to obtain non-radioactive conjugates ((19)FDG-AuNP-Anti-MTDH). Scanning electron microscopy (SEM) images demonstrated that synthesized particles were in nano sizes. (18)FDG-AuNP-Anti-MTDH conjugate was characterized and used as a model probe containing both radioactive and optical labels together as well as the biological target. The (18)FDG-AuNP-Anti-MTDH conjugate was applied to MCF7 breast cancer cell line and apoptotic cell ratio was found to be increasing from 2% to 20% following the treatment. Hence, these results have promised an important application potential of this conjugate in cancer research. (C) 2011 Elsevier B.V. All rights reserved.
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    A new agent for sentinel lymph node detection: preliminary results
    (Springer, 2011) Bekis, Recep; Medine, Ilker; Dagdeviren, Kagan; Ertay, Turkan; Unak, Perihan
    Sentinel lymph node detection is widely used to identify lymph nodes that receive lymphatic drainage from a primary tumor. (99m)Tc labeled iron oxide nanoparticles were prepared to invent a new colorful radioactive agent for sentinel lymph node detection. Iron oxide nanoparticles were produced by co-precipitation of FeCl(3) and FeCl(2) in the presence of NaOH. Then iron oxide nanoparticles were labeled with (99m)Tc. (99m)Tc labeled nanoparticles (7.4 MBq/0.1 mL) were intradermally injected in the distal hind limb of 16 rabbits. Dynamic and static lymphoscintigraphic images were taken for 24 h. Labeling efficiencies of (99m)Tc-iron oxide nanoparticles were over 99%. Their sizes are between 50 and 60 nm. (99m)Tc-iron oxide nanoparticles were accumulated in the popliteal lymph node in 11 of 16 rabbits (69%). Retention of nanoparticles in the popliteal lymph node was obvious at from 2nd through 24th hours. The radioactive lymph node was identified easily by gamma probe. The popliteal lymph node was excised and established for radioactivity and black dye. These black and radioactive nanoparticles may be potential agent successfully used for sentinel lymph node detection.
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    Preparation of I-131-Pyrimethamine and evaluation for scintigraphy of experimentally Toxoplasma gondii-infected rats
    (Informa Healthcare, 2013) Inceboz, Tonay; Lambrecht, Fatma Yurt; Surucu, Erdem; Yilmaz, Osman; Yavasoglu, Altug; Durkan, Kubra; Baykara, Basak; Bekis, Recep; Uner, Ahmet
    We aimed to assess the ability of I-131-Pyrimethamine scintigraphy to detect the lesions of Toxoplasma gondii infection. An experimental model of toxoplasmosis was developed. The presence of toxoplasmosis was confirmed 60 days after implantation. Pyrimethamine was radioiodinated with I-131. The radioligand was validated by the requisite quality control tests to check its radiolabeling efficiency, in vitro stability and radiochemical purity etc. I-131-Pyrimethamine (specific activity: 7.08 MBq/mu mol) was injected intravenously into the tail vein of the control and infected rats. Static whole body images of the rats were acquired under the gamma camera at 5 min, 45 min, 2 h, 6 h, and 24 h following the intravenous administration of the radioactivity (3.7 MBq/rat). Then the scintigraphic data were analyzed both visually and semiquantitatively. Regions of interest (ROIs) were drawn over the organs (thyroid, stomach, liver, bladder, and soft tissues) to calculate the ratios of the radiotracer in infected vs. control rats. The mean ratio of radiotracer in infected/control rats in the liver and diaphragm was over 1 at 45 min which persisted till 24 h. In conclusion, I-131-Pyrimethamine may be useful agent for diagnosis toxoplasmosis especially involving liver and diaphragm, needs further preclinical validation before being extended for use in clinical applications.
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    Preparation of I-131-Pyrimethamine and evaluation for scintigraphy of experimentally Toxoplasma gondii-infected rats
    (Informa Healthcare, 2013) Inceboz, Tonay; Lambrecht, Fatma Yurt; Surucu, Erdem; Yilmaz, Osman; Yavasoglu, Altug; Durkan, Kubra; Baykara, Basak; Bekis, Recep; Uner, Ahmet
    We aimed to assess the ability of I-131-Pyrimethamine scintigraphy to detect the lesions of Toxoplasma gondii infection. An experimental model of toxoplasmosis was developed. The presence of toxoplasmosis was confirmed 60 days after implantation. Pyrimethamine was radioiodinated with I-131. The radioligand was validated by the requisite quality control tests to check its radiolabeling efficiency, in vitro stability and radiochemical purity etc. I-131-Pyrimethamine (specific activity: 7.08 MBq/mu mol) was injected intravenously into the tail vein of the control and infected rats. Static whole body images of the rats were acquired under the gamma camera at 5 min, 45 min, 2 h, 6 h, and 24 h following the intravenous administration of the radioactivity (3.7 MBq/rat). Then the scintigraphic data were analyzed both visually and semiquantitatively. Regions of interest (ROIs) were drawn over the organs (thyroid, stomach, liver, bladder, and soft tissues) to calculate the ratios of the radiotracer in infected vs. control rats. The mean ratio of radiotracer in infected/control rats in the liver and diaphragm was over 1 at 45 min which persisted till 24 h. In conclusion, I-131-Pyrimethamine may be useful agent for diagnosis toxoplasmosis especially involving liver and diaphragm, needs further preclinical validation before being extended for use in clinical applications.
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    Radioiodine labeled CdSe/CdS quantum dots: Lectin targeted dual probes
    (Walter De Gruyter Gmbh, 2014) Akca, Ozlet; Unak, Perihan; Medine, E. Ilker; Sakarya, Serhan; Kilcar, Ayfer Yurt; Ichedef, Cigdem; Bekis, Recep; Timur, Suna
    CdSe/CdS quantum dots (QD) were synthesized and bioconjugated with Sambucus nigra agglutinin (SNA) lectin (Lec). Mannose triflate and cysteamine molecules (MTC) were also utilized to prepare MTC-QDs and MTC-QDs-Lec probes as well as Lec bound QDs. Afterwards; potential use of these nanoparticles as radiolabeled fluorescence nano-probes for the cell imaging studies has been investigated. Biological activities of I-125(-), I-125-MTC-QDs, MTC-QDs- Lec-I-125, QDs-Lec-I-125 and Lec-I-125 were examined on various cancer cell lines such as Caco-2, MCF-7 and A-549 in terms of cell incorporation. QDs-Lec-I-125 exhibited the highest cell incorporation on whole cell lines. In addition, the QDs-Lec-I-131, was used for in vivo imaging. The whole body distribution of the radiolabeled QDs on New Zealand rabbits and Balb C mice were examined by taking dynamic and static images. Radioactivity cleared from the kidneys and the bladder, while significant amount radioactivity was retained in the heart and liver within 24 h.