Biomedical subjects

Jongmin Lee

Publications and source records attributed to Jongmin Lee.

6 recordsLinked to original sources

PubMed2004

Transglutaminase 2 induces nitric oxide synthesis in BV-2 microglia.

A hallmark of brain inflammation is the activation of microglia. Excessive production of nitric oxide (NO), as a consequence of increased inducible nitric oxide synthase (iNOS) in glia, contributes to neurodegeneration. Transglutaminase 2 (TGase 2) is a cross-linking enzyme, which is increased in neurodegeneration. TGase 2 is also considered to be a useful and reliable marker for activation levels in resident and inflammatory macrophages. Therefore, an increase of TGase 2 expression may contribute to activation of microglia. To test this hypothesis, we analyzed the expression of TGase 2 in BV-2 microglia activated with lipopolysaccharide (LPS). Total TGase activity was increased about 5-fold after 24h exposure to LPS. The increase of NO synthesis is correlated with increase of TGase 2 expression. Secretion of NO was reduced between 40 and 80% by TGase inhibition in a dose-dependent manner. This suggests that TGase 2 appears to control iNOS transcription.

Animals↗

PubMed2004

Transglutaminase 2 induces nuclear factor-kappaB activation via a novel pathway in BV-2 microglia.

Transglutaminase 2 (TGase 2) expression is increased in inflammatory diseases. We demonstrated previously that inhibitors of TGase 2 reduce nitric oxide (NO) generation in a lipopolysaccharide (LPS)-treated microglial cell line. However, the precise mechanism by which TGase 2 promotes inflammation remains unclear. We found that TGase 2 activates the transcriptional activator nuclear factor (NF)-kappaB and thereby enhances LPS-induced expression of inducible nitric-oxide synthase. TGase 2 activates NF-kappaB via a novel pathway. Rather than stimulating phosphorylation and degradation of the inhibitory subunit alpha of NF-kappaB (I-kappaBalpha), TGase2 induces its polymerization. This polymerization results in dissociation of NF-kappaB and its translocation to the nucleus, where it is capable of up-regulating a host of inflammatory genes, including inducible nitric-oxide synthase and tumor necrosis factor alpha (TNF-alpha). Indeed, TGase inhibitors prevent depletion of monomeric I-kappaBalpha in the cytosol of cells overexpressing TGase 2. In an LPS-induced rat brain injury model, TGase inhibitors significantly reduced TNF-alpha synthesis. The findings are consistent with a model in which LPS-induced NF-kappaB activation is the result of phosphorylation of I-kappaBalpha by I-kappaB kinase as well as I-kappaBalpha polymerization by TGase 2. Safe and stable TGase2 inhibitors may be effective agents in diseases associated with inflammation.

Animals↗

PubMed2004

Successful treatment with stent angioplasty for Budd-Chiari syndrome in Behçet's disease.

Budd-Chiari syndrome (BCS) is a very rare vascular complication of Behçet's disease (BD) which often leads to death as a result of portal hypertension and liver failure. We report a 45-year-old BD patient who presented with BCS. Diagnosis was confirmed with CT scan and contrast-enhanced MR angiography which showed ascites, short-segment stenosis of the inferior vena cava (IVC), and middle and left hepatic venous thrombosis. Percutaneous transluminal angioplasty (PTA) of the obstructed segment in the IVC was performed and resulted in dramatic reduction of portal venous pressure. Our experience indicates that PTA may be a safe and effective therapeutic modality for BCS in BD which is caused by short segmental obstruction of the IVC.

Angiography↗

PubMed2004

Auditory neural pathway evaluation on sensorineural hearing loss using diffusion tensor imaging.

Diffusion tensor imaging is a new in vivo tool not only for the assessment of white matter structural integrity but also for diagnosis and assessment of disease conditions which disturb tissue structural coherence. In this study, we investigated the integrity of auditory pathway in patients of sensorineural hearing loss by means of fractional anisotropy of water diffusion to see any subtle changes of auditory pathways resulting from sensorineural hearing loss. In addition, this study suggests that the diffusion anisotropy measured by diffusion tensor imaging is highly sensitive to otherwise subtle disease processes not normally seen with conventional magnetic resonance imaging or computed tomography contrast.

Adolescent↗

PubMed2004

Diode-pumped 100-W green Nd:YAG rod laser.

We developed a diode-pumped high-average-power Nd:YAG green laser. By use of a monolithic diffusive reflector having three slits and a rod with low doping concentration, uniform distribution of excited Nd ions could be achieved. Uniform distribution in the rod reduced thermal birefringence. We employed a Z-shaped cavity to have a constant beam size at the frequency-doubling crystal independent of thermal lensing in the rod. The pulse width and green power dependence on the pump power were analyzed. A maximum green power of 101 W was obtained when the total pump power was 398 W. The optical-to-optical conversion efficiency was as high as 25.4%.

Journal Article↗

PubMedDate not supplied

Fractional quantitative computed tomography for bone mineral density evaluation: accuracy, precision, and comparison to quantitative computed tomography.

OBJECTIVE: To evaluate bone mineral density considering its distribution, fractional quantitative computed tomography (fQCT) was designed and verified. METHODS: Quantitative computed tomography (QCT) was performed at 64 areas in 10 swine long bones. Fractional quantitative computed tomography was measured at the identical areas as the proportion of pixels showing a bone density higher than 130 mg/mL equivalent. All target areas were extracted and incinerated to measure apparent ash bone density. Based on standard references, the accuracy and precision of fQCT were evaluated and the results were compared with conventional QCT results. RESULTS: The correlation coefficient between fQCT and apparent ash bone density was 0.843 (P < 0.0001). The fQCT showed good correlation with volume fraction (r = 0.88, P < 0.0001). The coefficient of variation of fQCT was 0.42%. The fQCT revealed higher accuracy and precision than the results of QCT. CONCLUSION: Fractional quantitative computed tomography was designed and verified as a reliable method to measure bone mineral density.

Animals↗