Hwan Jeong

Recent Trends in the Nucleophilic [ 18 F]-radiolabeling Method with No-carrier-added [ 18 F]fluoride

Noninvasive imaging in living subjects with positron emission tomography (PET) provides early detection of diseases in humans. For this application, it is necessary to prepare specific molecular imaging probes labeled with positron-emitting radioisotopes such as fluorine-18 for obtaining high-quality PET imaging. In this review, we describe recent trends in the F-18 radiolabeling method for the introduction of no-carrier-added fluorine-18, which was obtained from an 18O(p,n)18F reaction, into a specific molecular site, which in turn is intended to serve as an imaging agent for PET study. These labeling protocols are based on ionic liquid media 18F radiofluorination in the presence of some water, enzymatic 18F fluorination using fluorinase in water solution, non-polar protic alcohol media 18F radiofluorination and its mechanism, and nucleophilic 18F fluorination of an aromatic iodonium salt precursor.

Synthesis and characterization of iron oxide nanoparticles decorated with carboxymethyl curdlan

ConclusionsWe have synthesized the SPION coated with CMC and investigated the stability in water,T2 relaxation rate and cytotoxicity. The coating with CMC improved the stability in water and reduced the cytotoxicity to cell viability. Furthermore, the CMC-coated SPION showed superparamagnetic behaviors. The CMC-coated SPION may be used for cellular andin vivo imaging. When CMC are chemically modified for conjugation of specific ligand, the CMCcoated SPION may have a great potential for biomedical applications.

Glucosylated polyethylenimine as a tumor-targeting gene carrier.

Glucosylated polyethylenimine (GPEI) was synthesized as a tumor-targeting gene carrier through facilitative glucose metabolism by tumor glucose transporter. Particle sizes of GPEI/ DNA complex increased in proportion to glucose content of GPEI, whereas surface charge of the complex was not dependent on glucosylation, partially due to inefficient shielding of the short hydrophilic group introduced. GPEI with higher glucosylation (36 mol-%) had no cytotoxic effect on cells even at polymer concentrations higher than 200 μg/mL. Compared to unglucosylated PEI, glucosylation induced less than one-order decrease of transfection efficiency. Transfection of GPEI/DNA complex into tumor cells possibly occurred through specific interaction between glucose-related cell receptors and glucose moiety of GPEI. Gamma imaging technique revealed GPEI/DNA complex was distributed in liver, spleen, and tumors.

Optical imaging of absorption and distribution of RITC-SiO2 nanoparticles after oral administration

Purpose In this study, we investigated the absorption and distribution of rhodamine B isothiocyanate (RITC)-incorporated silica oxide nanoparticles(SiNPs) (RITC-SiNPs) after oral exposure, by conducting optical imaging, with a focus on tracking the movement of RITC-SiNPs of different particle size and surface charge. Methods RITC-SiNPs (20 or 100 nm; positively or negatively charged) were used to avoid the dissociation of a fluorescent dye from nanoparticles via spontaneous or enzyme-catalyzed reactions in vivo. The changes in the nanoparticle sizes and shapes were investigated in an HCl solution for 6 hours. RITC-SiNPs were orally administered to healthy nude mice at a dose of 100 mg/kg. Optical imaging studies were performed at 2, 4, and 6 hours after oral administration. The mice were sacrificed at 2, 4, 6, and 10 hours post-administration, and ex vivo imaging studies were performed. Results The RITC-SiNPs were stable in the HCl solution for 6 hours, without dissociation of RITC from the nanoparticles and without changes in size and shape. RITC-SiNPs flowed into the small intestine from the stomach and gradually moved along the gut during the experiment. In the ex vivo imaging studies, optical signals were observed mostly in the lungs, liver, pancreas, and kidneys. The orally administered RITC-SiNPs, which were absorbed in the systemic circulation, were eliminated from the body into the urine. The 20 nm RITC-SiNPs showed higher uptake in the lungs than the 100 nm RITC-SiNPs. The distribution of the 100 nm RITC-SiNPs in the liver was higher than that of the 20 nm RITC-SiNPs, but the differences in the surface charge behavior were imperceptible. Conclusion We demonstrated that the movement of RITC-SiNPs after oral exposure could be traced by optical imaging. Optical imaging has the potential to provide valuable information that will help in understanding the behavior of SiNPs in the body following exposure.

Glucosylated Polypropylenimine Dendrimer as a Novel Gene Carrier

Polypropylenimine (PPI) dendrimers have been used by many researchers as gene delivery carriers due to their high functionality. Glucose as a kind of carbohydrate is biocompatible and hydrophilic. In this study, we synthesized glucosylated PPI (G-PPI) dendrimers to reduce cytotoxicity. Glucose substitution of G-PPI dendrimers was determined by the sulfuric acid micromethod. The G-PPI dendrimer was complexed with plasmid DNA in various N/P ratios, and the complex was characterized. G-PPI dendrimers showed good DNA binding ability and high protection of DNA from nuclease attack. The G-PPI dendrimer had low cytotoxicity compared to PPI dendrimer by cytotoxicity assay. Also, transfection efficiency was influenced by glucosylation degree and the transfection efficiency for the G-PPI-5 was slightly higher than that of PPI dendrimer in HeLa cell line.

Chitosan Derivatives as Gene Carriers

Chitosan has been considered to be a good candidate for gene delivery system, since it is already known as a biocompatible, biodegradable, and low toxic material with high cationic potential. However, low specificity and low transfection efficiency of chitosan need to be overcome prior to clinical trial. In this review paper, chemical modification of chitosan for enhancement of cell specificity and transfection efficiency was explained. Also, chemical modification of chitosan for the stability of chitosan/DNA complexes was reviewed.

F-18 FDG PET/CT Findings of Spontaneous Mesenteric Fibromatosis in a Patient with Gardner’s Syndrome

Gardner’s syndrome (GS), a variant of familial adenomatous polyposis, is an autosomal dominant disease. Originally, Gardner described a syndrome consisting of hereditary intestinal polyposis with osteomas and multiple cutaneous and subcutaneous lesions [1] (Figs. u200b(Figs.11 and u200band2).2). The syndrome was later modified by the addition of other features, such as dental abnormalities, abdominal fibromatosis, and a number of malignant tumors. The principal cutaneous lesions that have been described in GS are epidermoid cysts. Other cutaneous lesions include fibromas, lipomas, leiomyomas, neurofibromas, and pigmented skin lesions [2]. Fibromatoses are histologically benign, but locally aggressive fibrous tumors consisting of mature fibroblasts within an extensive collagen matrix. Most cases are sporadic, but there is a clear association with familial adenomatous polyposis and GS, suggesting a link with a mutation of the APC gene on chromosome 5q22 [3]. Fibromatosis occurs in 3.5%–29% of patients with GS, and is more likely to be multiple and to involve the mesentery and abdominal wall rather than being an isolated form [4, 5]. Clinically, fibromatosis presents as a painless firm soft tissue mass. Most cases of fibromatosis are believed to be precipitated by surgical trauma; however, a few cases of spontaneous occurrence have been reported [6]. In our patient, no history of abdominal surgery or trauma was present. In addition, an abdominal CT obtained 2xa0years ago revealed no abnormality. n n n nFig.xa01 n nA 20-year-old man was admitted to oral surgery with a dental problem. A panoramic radiograph showed multiple osteomas in the right angle and anterior portion of the mandible with dental abnormalities (impacted or unerupted teeth, and supernumerary teeth). ... n n n n n nFig.xa02 n nThe patient had a history of excision of a mass on the back 4xa0years previously. (a–c) Transverse MR images showed low-signal intensity on T1-weighted image (WI), heterogenous high-signial intensity on T2WI, and marked enhancement on contrast-enhanced ... n n n nAlthough the radiological features of fibromatosis on CT or MR have been described in the literature, F-18 FDG-PET or PET/CT findings are rarely reported [7–10]. The F-18 FDG uptake in patients with fibromatosis ranged from low to moderate grade and was generally heterogenous with a few tiny foci of relatively intense uptake or relatively homogenous. The areas of higher FDG metabolism are likely to represent more cellular and mitotically active areas [7]. Mesenteric fibromatosis has similar findings to extra-abdominal lesions [7, 9] (Fig. u200b(Fig.33). n n n nFig.xa03 n nRoutine laboratory studies for dental surgery showed abnormal liver function tests. The patient was referred to the Gastroenterology Service. Computed tomography (CT) of the abdomen demonstrated a large soft tissue mass in the right lower quadrant (RLQ), ...

Unusual Case of Occult Brucella Osteomyelitis in the Skull Detected by Bone Scintigraphy

Brucellosis is a worldwide infectious disease of animals that can be transmitted to humans. Osteoarticular involvement is the most common complication of brucellosis. A 47-year-old man, who was a stockbreeder, complained of myalgia with fever and chills for 2xa0weeks. The serology titers and blood cultures for brucellosis were positive. Bone scintigraphy demonstrated a focally increased uptake in the left supraorbital area. Plain radiographs showed an osteolytic lesion, and an MRI revealed signal abnormalities in the corresponding site. We present an unususal case of occult Brucella osteomyelitis in the frontal bone of the skull detected by bone scintigraphy.

All-Trans Retinoic Acid (atRA) Release from atRA-Loaded Folate-Poly(Ethylene Glycol)/Polyethylenimine Nanoparticles for Folate-Mediated Tumor Targeting

To improve the specific accumulation in tumor sites and aqueous solubility of atRA, the core-shell type of folate-PEG-g-PEI/atRA nanoparticles were prepared by complexation between cationic PEI segments in the copolymers and anionic charged atRA, and then characterized by 1HNMR, ELS, XRD, and TEM. In vitro atRA release from the nanoparticles was investigated as a function of drug content in sink condition. Cytotocicity of atRA against HepG2, KB cell lines were also evaluated by MTT assay. The lower the drug content, the faster atRA release. atRA incorporated in folate-PEG-g-PEI/atRA nanoparticles showed much higher cytotoxic effect compared with atRA itself.