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Re-evaluation of [<sup>18</sup>F]fluorobenzaldehyde as a prosthetic group
Choe, Yearn Seong 대한방사성의약품학회 2015 Journal of radiopharmaceuticals and molecular prob Vol.1 No.2
[$^{18}F$]Fluorobenzaldehyde, which is a versatile radioactive prosthetic group, can undergo reduction, reductive amination, or oxidation to be used for synthesis of diverse radiotracers. This review covers synthesis of [$^{18}F$]fluorobenzaldehyde and its conversion to secondary prosthetic groups, and also highlights its application to the development of radiotracers.
Choe, Yearn Seong 충남대학교 약학대학 의약품개발연구소 1993 藥學論文集 Vol.9 No.-
Prostatic cancer is the third greatest cause of cancer deaths in American men after lung and colon cancer, and its incidence is shown to increase with age. According to the American Urological Association, prostatic cancer is classified into four stages. The tumor is confined within the capsule of the prostate in early two stages, but gradually grows outside of this capsule. Accurate staging of the prostatic cancer is thus very important for effective treatment of the tumor, since radiation and surgery are commonly used in early two stages, while androgen withdrawal therapy is applied in late two stages. Early detection of the tumor is also important, and several diagnostic methods are currently available. In virtro methods include invasive and non-invasive assays: the former invasive assay is used to measure the level of steroid receptors, and solely depends on partial tissue sampling. The latter assay includes measurements of prostatic specific antigen (PSA) and prostatic acid phosphatase (PAP), which serve as tumor markers in a person's blood. Currently available in vivo methods are the digital rectal examination and transrectal ultrasonography. These in vitro and in vivo diagnostic methods are of low sensitivity and low reliability. Therefore, in vivo imaging techniques are very attractive for accurate diagnosis and staging of prostatic tumors. One of these includes positron emission tomography (PET), which uses a positron emitting radionuclide as a positron source. These radionuclides emit positrons which in turn interact with electrons within a 1-6 mm range from the origin of the positron emission. This interaction releases two photons coincidently in opposite directions, which are then detected by PET. The high energy of the photons(511 KeV) and the coincident detection provide a sensitive and accurate in vivo image. The most commonly used positron emitting radionuclide is 18F due to its long half life (t_(1/2)=109.7 min).
Molar activity of radiopharmaceuticals
Choe, Yearn Seong 대한방사성의약품학회 2018 Journal of radiopharmaceuticals and molecular prob Vol.4 No.1
최근에 보고된 방사성의약품화학 분야의 명명법에 따라 그 동안 specific activity로 정의하였던 개념을 물리적인 성질을 나타내는 specific activity와 화학적 성질을 나타내는 molar activity로 세분하였다(1). 이 종설에서는 방사성의약품의 molar activity 및 중요성 등을 알아보았으며, 방사성의약품을 합성할 때 중요하게 고려하여야 한다. Radiopharmaceuticals are used for diagnosis or therapy of diseases. According to the recent consensus nomenclature rules for radiopharmaceutical chemistry, specific activity is defined as the radioactivity per gram of radiolabeled compound and molar activity as the radioactivity per mole of radiolabeled compound. In this review, molar activity of radiopharmaceuticals is discussed in terms of its significance in nuclear imaging as well as its measurement methods.
분자영상 방사성추적자의 생산에 사용되는 방사성동위원소 표지방법
최연성 대한핵의학회 2004 핵의학 분자영상 Vol.38 No.2
Molecular imaging visualizes cellular processes at a molecular or genetic level in living subjects, and diverse molecular probes are used for this purpose. Radiolabeling methods as well as radioisotopes are very important in preparation of molecular probes, because they can affect the biodistribution in tissues and the excretion route. In this review, the molecular probes are divided into small organic molecules and macromolecules such as peptides and proteins, and their commonly used radiolabeling methods are described. (Korean J Nucl Med 38(2):121-130, 2004)
최연성 대한핵의학회 1999 핵의학 분자영상 Vol.33 No.2
There is considerable interest in 188Re due to its favorable properties as a therapeutic radionuclide. 188Re and 99mTc act as a matched pair because of their similar chemical properties, and therefore methods of labeling with 99mTc can be applied to the labeling with 188Re. With appropriately chosen agents as carriers of 188Re, the labeling can be readily carried out using 188ReO4- in the presence of a reducing agent. 188Re radio pharmaceuticals based on 99mTc complexes have been synthesized and are currently being studied for clinical use. Some of them are shown to be suitable for therapeutic use and promising for radiotherapy in nuclear medicine.
메스암페타민 반복투여가 생쥐뇌 각 영역의 [??C]메스암페타민 분포에 미치는 영향
이윤성,이경한,김병태,이숭덕,최연성,이정빈 大韓法醫學會 1996 대한법의학회지 Vol.20 No.2
We evaluated whether alterations in regional cerebral methamphetamine(MA) uptake is involved in the behavioral effects of repeated MA administration. Group Ⅰ,Ⅱ, and control ICR mice were respectively injected with 2㎎/㎏ MA every 48 hr for 8 days, 15㎎/㎏ every 12 hr for 4 days, and saline, Regional cerebral uptakes of [??C] MA, [??Ⅰ]β-CIT, and ??Tc-ECD were measured 7 days later to assess regional MA uptake, transporter density, and blood flow, respectively. The behavioral excitation score increased in group Ⅰ(p<0.0001) and Ⅱ(p<0.05). Striatal[??C]MA uptake (% ID/gram) was 2.5±0.5, 1.4±0.4 in the control group, 2.5±0.5, 1.5±0.1 in group Ⅰ, and 2.1±0.7, 1.2±0.3 in group Ⅱ(30, and 60 minutes, respectively). Striatal to cerebellar uptake ratio at 30 minutes was significantly higher in group Ⅰ(1.43±0.07) compared to the control group(1.35±0.04;p<0.05) and group Ⅱ(1.33±0.11;p<0.05), while the ratio at 60 minutes was lower in group Ⅱ(1.22±0.04) compared to the control group (1.35±0.08;p<0.01) and group Ⅰ(1.38±0.08;p<0.001). There was no difference in regional uptake of ??Tc-ECD between the groups. Striatal uptake ratio of [??Ⅰ] β-CIT was significantly decreased in group Ⅱ(6.2±1.9) vs. control group (10.4±1.7;p<0.001), but not in group Ⅰ(9.6±1.7). Thus, repeated low dose MA enhanced striatal MA uptake without altering regional blood flow or dopamine transporter densities, while high dose MA caused dopaminergic nerve terminal damage. This suggests that enhanced striatal MA uptake has a role in the MA sensitization phenomenon.
α_4β_2 니코틴성 아세틸콜린 수용체 영상 방사성리간드 2-[^18F]fluoro-A85380의 합성 및 평가
류은경,최연성,김상은,황세환,백진영,최용,이경한,김병태 대한핵의학회 2002 핵의학 분자영상 Vol.36 No.4
Purpose: Nicotinic acetylcholine receptors (nAChRs), which mediate excitatory neurotransmission, are known to participate in various neurophysiological functions. Severe losses of nAChRs have been noted in Alzheimer's and Parkinson's diseases. Therefore, noninvasive and quantitative imaging of nAChRs would offer a better understanding on the function of these receptors. In this study, 2-[^18F]fluoro-A85380 ([^18F]1), an α_4β_2 nAChRs radioligand, was prepared using one HPLC purification and evaluated in mouse brain, and the results were compared with those in the literature. Materials and Methods: [^18F]1 was prepared by [^18F]fluorination of the iodo precursor followed by acidic deprotection and then purified by HPLC. Tissue distribution studies were performed in mouse brain at the indicated time points adn the result was expressed as %ID/g, Inhibition studies were also carried out with pretreatment of various ligands. Results: One HPLC purification method gave the desired product in 15-20% radiochemical yield and with high specific activity (38-55 GBq/μmol). Tissue distribution studies showed that [^18F]1 specifically labeled nAChRs in mouse brain with a high thalamus to cerebellum uptake ratio (13.8 at 90 min). Inhibition studies demonstrated selective binding of [^18F]1 to nAChRs, blocking the uptake of the [^18F]1 in nAChR-rich regions by selective ligands such as cytisine and nicotine which are well-known nAChRs agonists. Conclusion: This study demonstrated that the [^18F]1 produced by the method using one HPLC purification gave the results similar to those reported in the literature. Therefore, this synthetic method can be readily applied to the routine preparation of [^18F]1, a PET radioligand for α_4β_2 nAChRs imaging. (Korean J Nucl Med 2002;36;261-70)