Biomedical subjects

Jong Wook Hong

Publications and source records attributed to Jong Wook Hong.

9 recordsLinked to original sources

PubMed2006

Microfluidic digital PCR enables multigene analysis of individual environmental bacteria.

Gene inventory and metagenomic techniques have allowed rapid exploration of bacterial diversity and the potential physiologies present within microbial communities. However, it remains nontrivial to discover the identities of environmental bacteria carrying two or more genes of interest. We have used microfluidic digital polymerase chain reaction (PCR) to amplify and analyze multiple, different genes obtained from single bacterial cells harvested from nature. A gene encoding a key enzyme involved in the mutualistic symbiosis occurring between termites and their gut microbiota was used as an experimental hook to discover the previously unknown ribosomal RNA-based species identity of several symbionts. The ability to systematically identify bacteria carrying a particular gene and to link any two or more genes of interest to single species residing in complex ecosystems opens up new opportunities for research on the environment.

Animals↗

PubMed2006

[A case of idiopathic colitis developed after barium enema].

It has been reported that colitis may be associated with intrarectally administered drugs or chemicals. Colonotoxicity may results from conventional medical therapy, herbal or other illicit drugs, contrast materials, and detergents. Clues that a colitis may be due to an intrarectally administered agent include perianal excoriation, segmental distal colitis due to a concentration gradient from enema administration, and recent diagnostic or therapeutic administration of high risk solutions such as hypertonic contrast agents or detergent enemas. Barium is a highly viscous contrast agent that is insoluble in water. Barium enemas are usually very safe. Also, no case report of barium-induced chemical colitis has been reported yet. We report a case of chemical colitis with colonic stricture occurring after the barium enema for diagnostic purpose.

Barium Sulfate↗

PubMed2005

Phosphorylation of serine 147 of tis21/BTG2/pc3 by p-Erk1/2 induces Pin-1 binding in cytoplasm and cell death.

Treatment of U937 cells with epidermal growth factor (EGF) induces phosphorylation of tis21 and subsequent interaction of tis21 with Pin-1, resulting in the increased cell death with mitochondrial depolarization. Ser147 and Ser149 residues of tis21 were strongly phosphorylated by p-Erk1/2 and p-p38(MAPK), respectively, but not by JNK. To investigate the significance of phosphorylation of the Ser147 residue, Pin-1, one of the mitotic regulators that binds to the Ser(P)/Thr(P)-Pro region, was employed. Wild type tis21 phosphorylated by p-Erk1/2 clearly increased its binding to Pin-1, but not the P148A mutant, indicating that Pin-1 was bound to the Ser(P)147-Pro148 region of tis21. Transfection of tis21 significantly enhanced EGF-induced Pin-1 diffusion to cytoplasm, compared with that in the vector-transfected cells. Knockdown of tis21 expression by using shRNAi significantly inhibited EGF-induced Pin-1 diffusion, and analysis by flow cytometry after JC-1 stain and confocal microscope revealed that EGF aggravated tis21-induced mitochondrial depolarization and cell death. Furthermore, tis21 was bound to cyclin B1 and Cdc2 and inhibited its activity in vivo and in vitro. In summary, treatment of U937 cells with EGF activates Erk1/2, which in turn phosphorylates Ser147 of tis21 and induces tis21 and Pin-1 binding and mitochondrial depolarization. These data suggest, for the first time, a mechanism of how EGF can be antiproliferative in human tumor cells: binding of tis21/BTG2/pc3 to Pin-1 or cyclin B1-Cdc2 complex and induction of mitochondrial depolarization.

Antibodies↗

PubMed2004

TIS21/BTG2/PC3 is expressed through PKC-delta pathway and inhibits binding of cyclin B1-Cdc2 and its activity, independent of p53 expression.

Signal transduction pathway and a new function of TIS21/BTG2/PC3 were investigated in p53 null U937 cells; Expression of TIS21 by 12-O-tetradecanoyl phorbol-13-acetate (TPA) stimulation was mediated by PKC-delta activation, however, was strongly inhibited by cPKC isozymes. When U937 cells were treated with TPA+Go6976, but not TPA+Go6850, the level of TIS21 mRNA was maintained over that of TPA alone. When analyzed by FACS, TPA-induced G2/M arrest was significantly inhibited by Go6850, but not by Go6976, suggesting the involvement of TIS21 and nPKC isozymes. Indeed, PKC-delta was found to be a regulator of the G2/M arrest and TIS21 expression, confirmed by employing rottlerin and dnPKC-delta experiments. In vivo accumulation of TIS21 protein significantly induced cell death through caspase 3 activation, which was supported further by degradations of procaspase 3, full-length PKC-delta, pRB, and p21(WAF1) in TIS21DeltaC expresser. When the cells were synchronized by nocodazole, TIS21 overexpressers inhibited degradations of cyclin A and cyclin B1 in 3 h after release from the synchronization. Furthermore, TIS21 inhibited cyclin B1-Cdc2 binding and its kinase activity in vivo. In summary, TPA-induced TIS21 mRNA expression is mediated by PKC-delta, and TIS21 induces G2/M arrest and cell death by inhibiting cyclin B1-Cdc2 binding and the kinase activity through its binding to Cdc2.

Animals↗

PubMed2004

A nanoliter-scale nucleic acid processor with parallel architecture.

The purification of nucleic acids from microbial and mammalian cells is a crucial step in many biological and medical applications. We have developed microfluidic chips for automated nucleic acid purification from small numbers of bacterial or mammalian cells. All processes, such as cell isolation, cell lysis, DNA or mRNA purification, and recovery, were carried out on a single microfluidic chip in nanoliter volumes without any pre- or postsample treatment. Measurable amounts of mRNA were extracted in an automated fashion from as little as a single mammalian cell and recovered from the chip. These microfluidic chips are capable of processing different samples in parallel, thereby illustrating how highly parallel microfluidic architectures can be constructed to perform integrated batch-processing functionalities for biological and medical applications.

Animals↗

PubMed2004

[A case of non-traumatic hemobilia due to warfarin therapy].

Hemobilia is a hemorrhage into the biliary tract that may follow surgical trauma, liver biopsy, aneurysms, extra- or intra-hepatic tumors of the biliary tract, gallstones, and inflammatory lesion of liver, especially helminthic or pyogenic. Sometimes, it is associated with primary liver cancer. An 84 year-old woman was admitted because of continuous right upper quadrant pain 4 days before admission. Physical examination revealed decreased skin turgor, icteric sclerae and severe tenderness on right upper quadrant abdomen. She had no hepatosplenomegaly, and no rebound tenderness. She has been taking warfarin for 3 weeks before admission because of atrial fibrillation. On admission, serum bilirubin and transaminase were elevated. The level of hemoglobin and hematocrit were 11.3 g/dL and 37.4%, respectively. HBsAg was negative, but IgG anti-HBc and anti-HBs were positive and anti-HCV was negative. Parasite skin test and stool ova count demonstrated non-specific findings. Stool occult blood was strongly positive, and prothrombin time was markedly prolonged. According to endoscopic retrograde cholangiopancreatography, common bile duct was dilated, and filled with blood clot but there was no stone in bile tree. After two weeks, serum transaminase, bilirubin, hemoglobin, hematocrit, and CA19-9 were normalized. We report a case of hemobilia, occurring in a patient with continuous warfarin use.

Aged↗

PubMed2003

Gene transfer into rabbit keratocytes using AAV and lipid-mediated plasmid DNA vectors with a lamellar flap for stromal access.

Development of gene transfer methods that can precisely deliver therapeutic genes to the localized or targeted tissue(s) would be highly beneficial in developing new gene therapy approaches and may also extend animal models for studying in vivo gene function and regulation at molecular levels in the selected tissues. We investigated lipid- and AAV-mediated gene transfer in rabbit cornea using a lamellar flap-technique. The goals of this study were to (1) analyze methods for in situ gene transfer into keratocytes, (2) identify efficient and suitable vectors for gene transfer into keratocytes, and (3) characterize times of first detectable expression, localization and duration of transgene expression in keratocytes with different vectors. A lamellar flap was produced in the rabbit cornea with a microkeratome. Recombinant adeno-associated viral vector (rAAV) expressing either beta-galactosidase (rAAV-beta-gal) or chloramphenicol acetyltransferase (rAAV-CAT) reporter genes, or plasmid-cationic lipid complexes expressing CAT (pMP6-CAT) or beta-galactosidase (pTR-beta-gal) were applied beneath the lamellar flap for two minutes. The flap was repositioned and eyelids sutured overnight. Corneas were removed at 4hr, 12hr, 36hr, 3 days, 7 days, or 10 days after application and either fixed in 2% formaldehyde, cryosectioned and stained for beta-galactosidase activity or homogenized and measured for CAT levels by ELISA. Corneas infected with rAAV-beta-gal vector showed positive beta-gal staining in the center and periphery of the flap interface in whole corneas and corneal beds at 3, 7, and 10 days, but not at earlier time points. Corneas treated with pTR-beta-gal plasmid vector showed positive beta-gal expression at the interface at 4, 12 and 36hr, but not at 3 or 7 days. The posterior surface of the lamellar interface where the vector was applied showed more expression than the overlying anterior surface with both plasmid and viral vectors. The level of gene expression was less with plasmid vector than viral vector monitored using beta-gal staining. CAT-ELISA confirmed expression of the CAT reporter gene with either the plasmid or rAAV vector. These results demonstrate that foreign genes can be introduced into keratocytes with plasmid or viral vectors using a lamellar flap to gain access to the stroma. The expression profile of the reporter genes depended on the vector. Transfection of keratocytes with plasmid vectors produced rapid expression of the reporter genes, but for a short duration. Reporter gene expression following transduction by rAAV vector was delayed several days, but was at higher levels and for a longer duration. This is the first report to demonstrate selective gene transfer into keratocytes and would be highly useful in studying function and regulation of genes in vivo and may eventually furnish a tool for the treatment of corneal dystrophies.

Adenoviridae↗

PubMed2003

Integrated nanoliter systems.

Microfluidic chip platforms for manipulating liquid volumes in the nanoliter range are slowly inching their way into mainstream genomic and proteomic research. The principal challenge faced by these technologies is the need for high-throughput processing of increasingly smaller volumes, with ever higher degrees of parallelization. Significant advances have been made over the past few years in addressing these needs through electrokinetic manipulation, vesicle encapsulation and mechanical valve approaches. These strategies allow levels of integration density and platform complexity that promise to make them into serious alternatives to current robotic systems.

Chemistry Techniques, Analytical↗

PubMed2002

Relationship between intraocular pressure and systemic health parameters in a Korean population.

PURPOSE: This study aimed to evaluate the relationship between intraocular pressure (IOP) and age and obesity, adjusted for systemic health parameters such as sex and mean blood pressure, in a Korean population. METHODS: A total of 13 212 healthy participants underwent automated multiphasic tests, including tonometry, automated perimetry, fundus photography, blood pressure and body mass index (BMI). Six age groups were used, divided by decades ranging from 20-29 years to 70+ years. The association between IOP and systemic health para-meters was examined using cross-sectional analysis. RESULTS: The median age of participants was 47.6 years (range 20-84 years), and 6684 (50.6%) of participants were men. The mean IOP of participants was 15.5 mmHg. The mean IOP, blood pressure and BMI values were significantly higher in men than in women (P < 0.05). The overall prevalence of ocular hypertension, defined as IOP >21 mmHg without signs of glaucomatous visual field loss or optic disc damage, was 6.1% in men and 2.5% in women. Intraocular pressure was associated with mean blood pressure, sex, age and BMI by multiple regression analysis (P < 0.05). The relationship between IOP and age adjusted for sex, mean blood pressure and BMI had a significantly negative tendency for both sexes (P < 0.05). Body mass index had a significantly positive relation with IOP after controlling for age, sex and mean blood pressure in men (P < 0.05), but not in women. CONCLUSIONS: In this Korean population, after multiple adjustment, IOP was found to decrease with age and to increase with BMI in men.

Adult↗