• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.72-75
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• 2011

Purpose: The HSV1-tk reporter gene system is the most widely used system because of its advantage is that it is possible to monitor directly without the introduction of a separate reporter gene in case of HSV1-tk suicide gene therapy. This study was performed to automate 9-(4-[$^{18}F$] Fluoro-3-hydroxymethylbutyl) guanine ([$^{18}F$] FHBG) that are widely used as substrate for the HSV1-tk reporter gene in living organisms with positron emission tomography (PET) and find the optimized conditions of synthesis. Materials and Methods: Fully automated synthesis of [$^{18}F$] FHBG was performed using Explora-RN (CTI, USA) module. We have changed of reaction time (3, 5, 10 min) and temperature (110, 120, $130^{\circ}C$) for the optimized conditions of synthesis. Also we experimented to find the optimal concentration of precursor (5, 7, 10 mg). Results: [$^{18}F$] FHBG was purified by HPLC system and collected at around 10-12 min. Synthesis using Explora-RN module showed a $32.0{\pm}1.2%$ yield of radiochemical (decay corrected), the purity was greater than 98%. And the entire synthesis time was less than 48 min. Temperature of the highest synthesis yield was $130^{\circ}C$, reaction time was 5 minutes and concentration of precursor was 10 mg (recommended volume in manual) (n=36). In contrast to radiochemical yield of precursor 10 mg ($32{\pm}1.2%$), yield of 5 and 7 mg precursor was unstable. Conclusion: Automation of [$^{18}F$] FHBG synthesis at Explora-RN module has been completed. In addition, we were able to obtain optimized reaction time, temperature and concentration of precursor. Therefore this study would be provided more rapid synthesis and higher radiochemical yield.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.22 no.2
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• pp.164-173
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• 2000

The p16 protein is a cyclin dependent kinase inhibitor that inhibits cell cycle progression from $G_1$ phase to S phase in cell cycle. Many p16 gene mutations have been noted in many cancer-cell lines and in some primary cancers, and alterations of p16 gene function by DNA methylation have been noticed in various kinds of cancer tissues and cell-lines. There have been a large body of literature has accumulated indicating that abnormal patterns of DNA methylation (both hypomethylation and hypermethylation) occur in a wide variety of human neoplasma and that these aberrations of DNA methylation may play an important epigenetic role in the development and progression of neoplasia. DNA methylation is a part of the inheritable epigenetic system that influences expression or silencing of genes necessary for normal differentiation and proliferation. Gene activity may be silenced by methylation of up steream regulatory regions. Reactivation is associated with demethylation. Although evidence or a high incidence of p16 alterations in a variety of cell lines and primary tumors has been reported, that has been contested by other investigators. The precise mechanisms by which abnormal methylation might contribute to carcinogenesis are still not fully elucidated, but conceivably could involve the modulation of oncogene and other important regulatory gene expression, in addition to creating areas of genetic instability, thus predisposing to mutational events causing neoplasia. There have been many variable results of studies of head and neck squamous cell carcinoma(HNSCC). This investigation was studied on 13 primary HNSCC for p16 gene status by protein expression in immunohistochemistry, and DNA genetic/epigenetic analyzed to determine the incidence, the mechanisms, and the potential biological significance of its Inactivation. As methylation detection method of p16 gene, the methylation specific PCR(MSP) is sensitive and specific for methylation of any block of CpG sites in a CpG islands using bisulfite-modified DNA. The genomic DNA is modified by treatment with sodium bisulfate, which converts all unmethylated cytosines to uracil(thymidine). The primers designed for MSP were chosen for regions containing frequent cytosines (to distinguish unmodified from modified DNA), and CpG pairs near the 5' end of the primers (to provide maximal discrimination in the PCR between methylated and unmethylated DNA). The two strands of DNA are no longer complementary after bisulfite treatment, primers can be designed for either modified strand. In this study, 13 paraffin embedded block tissues were used, so the fragment of DNA to be amplified was intentionally small, to allow the assessment of methylation pattern in a limited region and to facilitate the application of this technique to samlples. In this 13 primary HNSCC tissues, there was no methylation of p16 promoter gene (detected by MSP and automatic sequencing). The p16 protein-specific immunohistochemical staining was performed on 13 paraffin embedded primary HNSCC tissue samples. Twelve cases among the 13 showed altered expression of p16 proteins (negative expression). In this study, The author suggested that low expression of p16 protein may play an important role in human HNSCC, and this study suggested that many kinds of genetic mechanisms including DNA methylation may play the role in carcinogenesis.

• Korean Journal of Food Science and Technology
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• v.5 no.3
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• pp.169-173
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• 1973

Secondary amines and nitrites in various daily foods have been known as the precursors of potent carcinogenic nitroso compound produced in the human stomach when they were ingested simultaneouly in high concentration. In this report, the amounts and distribution of secondary amines and nitrites in Korean daily foods, kim-chi, fishes, fish eggs, sausages, canned fish foods and fish sauces (salted fish) were studied.Nitrite contents were low in most subjected foods except in sausages. Secondary amines showed low contents in kim-chi, fishes, but high in fish sauces, fish eggs and canned fish foods. The result of this study suggested that the possible formation of carcinogenic nitrosamines during manufacturing, storage and cooking of all Korean foods should be studied.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.5
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• pp.478-486
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• 2009

Purpose: 5-iododeoxyuridine analogues have been exclusively developed for the potential antiviral and antitumor therapeutic agents. In this study, we synthesized carbocyclic radioiododeoxyuridineanalogue (ddIVDU) and carbocyclic intermediate as efficient carbocyclic radiopharmaceuticals. Materials and Methods: The synthesis is LAH reduction, hetero Diels-Alder reaction as key reactions including Pd(0)-catalyzed coupling reaction together with organotin. MCA-RH7777 (MCA) and MCA-tk (HSV1-tk positive) cells were treated with various concentration of carbocyclic ddIVDU, and GCV. Cytotoxicity was measured by the MTS methods. For in vitro uptake study, MCA and MCA-tk cells were incubated with 1uCi of [$^{125}I$]carbocyclic ddIVDU. Accumulated radioactivity was measured after various incubation times. Results: The synthesis of ddIVDU and precursor for radioiodination were achieved from cyclopentadiene in good overall yield, respectively. The radioiododemetallation for radiolabeling gave more than 80% yield with > 95% radiochemical purity. GCV was more toxic than carbocyclic ddIVDU in MCA-tk cells. Accumulation of [$^{125}I$]carbocyclic ddIVDU was higher in MCA-tk cells than MCA cells. Conclusion: Biological data reveal that ddIVDU is stable in vitro, less toxic than ganciclovir (GCV), and selective in HSV1-tk expressed cells. Thus, this new carbocyclic nucleoside, referred to in this paper as carbocyclic 2',3'-didehydro-2',3'-dideoxy-5- iodovinyluridine (carbocyclic ddIVDU), is a potential imaging probe for HSV1-tk.

• Journal of Animal Environmental Science
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• v.13 no.1
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• pp.13-20
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• 2007

Sawdust biofiltration is an emerging bio-technology for control of ammonia emissions including compost odors from composting of biological wastes. Although sawdust is widely used as a medium for bulking agent in composting system and for microbial attachment in biofiltration systems, the performance of agitated bed composting and sawdust biofiltration are not well established. A pilot-scale composting of hog manure amended with sawdust and sawdust biofiltration systems for practical operation were investigated using aerated and agitated rectangular reactor with compost turner and sawdust biofilter operated under controlled conditions, each with a working capacity of approximately $40m^3\;and\;4.5m^3$ respectively. These were used to investigate the effect of compost temperature, seed germination rate and the C/N ratio of the compost on ammonia emissions, compost maturity and sawdust biofiltration performance. Temperature profiles showed that the material in three runs had been reached to temperature of 55 to $65^{\circ}C$ and above. The ammonia concentration in the exhaust gas of the sawdust biofilter media was below the maximum average value as 45 ppm. Seed germination rate levels of final compost was maintained from 70 to 93% and EC values of the finished compost varied between 2.8 and 4.8 ds/m, providing adequate conditions for plant growth.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.3
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• pp.235-245
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• 2008

Purpose: The HSV1-tk gene has been extensively studied as a type of reporter gene. In hepatocellular carcinoma (HCC), only a small proportion of patients are eligible for surgical resection and there is limitation in palliative options. Therefore, there is a need for the development of new treatment modalities and gene therapy is a leading candidate. In the present study, we investigated the usefulness of substrate, 2'-fluoro-2'-deoxy-1-${\beta}$-D-arabino-furanosyi-5-[$^{124/125}I$]iodo- uracil ([$I^{124/125}I$]FIAU) as a non-invasive imaging agent for HSV1-tk gene therapy in hepatoma model using small animal PET. Material and Methods: With the Morris hepatoma MCA cell line and MCA-tk cell line which was transduced with the HSV1-tk gene, in vitro uptake and correlation study between [$^{125}I$]FIAU uptake according to increasing numeric count of percentage of MCA-tk cell were performed. The biodistribution data and small animal PET images with [$^{124}I$]FIAU were obtained with Balb/c-nude mice bearing both MCA and MCA-tk tumors. Results:, Specific accumulation of [[$^{125}I$]FIAU was observed in MCA-tk cells but uptake was low in MCA cells. Uptake in MCA-tk cells was 15 times higher than that of MCA cells at 480 min. [$^{125}I$]FIAU uptake was linearly correlated (R2 =0.964, p =0.01) with increasing percentage of MCA-tk numeric cell count. Biodistribution results showed that [$^{125}I$]FIAU was mainly excreted via the renal system in the early phase. Ratios of MCA-tk tumor to blood acting were 10, 41, and 641 at 1 h, 4 h, and 24 h post-injection, respectively. The maximum ratio of MCA-tk to MCA tumor was 192.7 at 24 h. Ratios of MCA-tk tumor to liver were 13.8, 66.8, and 588.3 at 1 h, 4 h, and 24 h, respectively. On small animal PET, [$^{124}I$]FIAU accumulated in substantial higher levels in MCA-tk tumor and liver than MCA tumor. Conclusion: FIAU shows selective accumulation to HSV1-tk expressing hepatoma cell tumors with minimal uptake in normal liver. Therefore, radiolabelled FIAU is expected to be a useful substrate for non-invasive imaging of HSV1-tk gene therapy and therapeutic response monitoring of HCC.