Biomedical subjects

Jongho Lee

Publications and source records attributed to Jongho Lee.

11 recordsLinked to original sources

PubMed2006

Respiration-induced B0 field fluctuation compensation in balanced SSFP: real-time approach for transition-band SSFP fMRI.

In functional MRI (fMRI) the resonance frequency shift induced from respiration is a major source of physiological noise. In transition-band SSFP fMRI the respiration-induced resonance offset not only increases noise interference, it also shifts the activation band. This leads to a reduction in the contrast-to-noise ratio (CNR) and the potential for varying contrast levels during the experiment. A novel real-time method that compensates for the respiration-induced resonance offset frequency is presented. This method utilizes free induction decay (FID) phase information to measure the resonance offset. For compensation, one can update the resonant frequency in real time by changing the transmit RF pulse and receiver phases to track the measured offset. The results show decreased signal power in the respiration frequency band and increased numbers of activated voxels with higher Z-scores compared to uncompensated experiments.

Algorithms↗

PubMed2004

Therapeutic effects of lysophosphatidylcholine in experimental sepsis.

Sepsis represents a major cause of death in intensive care units. Here we show that administration of lysophosphatidylcholine (LPC), an endogenous lysophospholipid, protected mice against lethality after cecal ligation and puncture (CLP) or intraperitoneal injection of Escherichia coli. In vivo treatment with LPC markedly enhanced clearance of intraperitoneal bacteria and blocked CLP-induced deactivation of neutrophils. In vitro, LPC increased bactericidal activity of neutrophils, but not macrophages, by enhancing H(2)O(2) production in neutrophils that ingested E. coli. Incubation with an antibody to the LPC receptor, G2A, inhibited LPC-induced protection from CLP lethality and inhibited the effects of LPC in neutrophils. G2A-specific antibody also blocked the inhibitory effects of LPC on certain actions of lipopolysaccharides (LPS), including lethality and the release of tumor necrosis factor-alpha (TNF-alpha) from neutrophils. These results suggest that LPC can effectively prevent and treat sepsis and microbial infections.

Animals↗

PubMed2004

Regulation of c-fos and c-jun gene expression by lipopolysaccharide and cytokines in primary cultured astrocytes: effect of PKA and PKC pathways.

The effects of lipopolysaccharide (LPS) and several cytokines on the c-fos and c-jun mRNA expression were examined in primary cultured astrocytes. Either LPS (500 ng/mL) or interferon-gamma (IFN-gamma; 5 ng/mL) alone increased the level of c-fos mRNA (1 h). However, tumor necrosis factor-alpha (TNF-alpha; 10 ng/mL) or interleukin-1beta (IL-1beta; 5 ng/mL) alone showed no significant induction of the level of c-fos mRNA. TNF-alpha showed a potentiating effect in the regulation of LPS-induced c-fos mRNA expression, whereas LPS showed an inhibitory action against IFN-gamma-induced c-fos mRNA expression. LPS, but not TNF-alpha, IL-1beta and IFN-gamma, increased the level of c-jun mRNA (1 h). TNF-alpha and IFN-gamma showed an inhibitory action against LPS-induced c-jun mRNA expression. Both phorbol 12-myristate 13-acetate (PMA; 2.5 mM) and forskolin (FSK; 5 mM) increased the c-fos and c-jun mRNA expressions. In addition, the level of c-fos mRNA was expressed in an antagonistic manner when LPS was combined with PMA. When LPS was co-treated with either PMA or FSK, it showed an additive interaction for the induction of c-jun mRNA expression. Our results suggest that LPS and cytokines may be actively involved in the regulation of c-fos and c-jun mRNA expressions in primary cultured astrocytes. Moreover, both the PKA and PKC pathways may regulate the LPS-induced c-fos and c-jun mRNA expressions in different ways.

Animals↗

PubMed2004

Identification of Lactobacillus sakei and Lactobacillus curvatus by multiplex PCR-based restriction enzyme analysis.

Two closely related lactic acid bacteria, Lactobacillus sakei and Lactobacillus curvatus, are very difficult to be rapidly differentiated. Here we report multiplex polymerase chain reaction (PCR)-based restriction enzyme analysis that is useful for rapid and reliable identification of these two species. This method employs both polymerase chain reaction (PCR) and restriction enzyme analysis (REA). First, multiplex-PCR using three primers that were designed from 16S rDNA sequence produces two bands, a 433-bp and a 623-bp band. A 433-bp band represents only L. sakei and L. curvatus among lactobacilli and genetically related bacteria, and a 623-bp band is used for further identification by restriction analysis. Second, restriction analysis of 623-bp band using Hind III restriction enzyme discriminates L. sakei from L. curvatus. This method could identify 28 strains as L. sakei or L. curvatus, which were frequently isolated from kimchi, a traditional fermented cabbage product in South Korea. Therefore, these results suggest that this method is simple, rapid, and reliable for the identification of L. sakei and L. curvatus species.

Brassica↗

PubMed2003

Lysophosphatidic acid stimulates CREB through mitogen- and stress-activated protein kinase-1.

Lysophosphatidic acid (LPA) is a growth factor-like phospholipid that elicits a variety of cellular responses in numerous cell types, including neurons, immune cells, and fibroblasts. In this report, we investigated the possibility that LPA activates the transcription factor cAMP response element-binding protein, CREB, in Rat-2 fibroblast cells. CREB is activated in many cells downstream of signaling events, such as growth factor and neurotrophin stimulation. We found that LPA rapidly stimulated phosphorylation of CREB at Ser133 in a time- and dose-dependent manner, as revealed by immunoblot analysis with a phospho-specific antibody recognizing CREB on Ser133. LPA-induced phosphorylation of CREB was dependent on the activation of extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (p38 MAPK). Inhibition of ERK1/2 with PD98059 and of p38 MAPK with SB203580 efficiently blocked LPA-mediated phosphorylation of CREB. The LPA-induced CREB phosphorylation was abolished by H89, an inhibitor of mitogen- and stress-activated protein kinase-1 (MSK1). Together, these data suggest that LPA stimulates nuclear transcription factor CREB via mitogen-activated protein kinase signaling components, ERK1/2, p38 MAPK, and MSK1 in Rat-2 fibroblast cells.

Animals↗

PubMed2003

Functional brain imaging using a blood oxygenation sensitive steady state.

Blood oxygenation level dependent (BOLD) functional MRI (fMRI) is an important method for functional neuroimaging that is sensitive to changes in blood oxygenation related to brain activation. While BOLD imaging has good spatial coverage and resolution relative to other neuroimaging methods (such as positron emission tomography (PET)), it has significant limitations relative to other MRI techniques, including poor spatial resolution, low signal levels, limited contrast, and image artifacts. These limitations derive from the coupling of BOLD functional contrast to sources of image degradation. This work presents an alternative method for fMRI that may over-come these limitations by establishing a blood oxygenation sensitive steady-state (BOSS) that inverts the signal from deoxygenated blood relative to the water signal. BOSS fMRI allows the imaging parameters to be optimized independently of the functional contrast, resulting in fewer image artifacts and higher signal-to-noise ratio (SNR). In addition, BOSS fMRI has greater functional contrast than BOLD. BOSS fMRI requires careful shimming and multiple acquisitions to obtain a precise alignment of the magnetization to the SSFP frequency response.

Artifacts↗

PubMed2003

Effect of ginsenoside Rd on nitric oxide system induced by lipopolysaccharide plus TNF-alpha in C6 rat glioma cells.

Effects of ginsenosides on nitric oxide (NO) production induced by lipopolysaccharide plus TNF-alpha (LNT) were examined in C6 rat glioma cells. Among several ginsenosides, ginsenoside Rd showed a complete inhibition against LNT-induced NO production. Ginsenoside Rd attenuated LNT-induced increased phosphorylation of ERK. Among several immediate early gene products, only Jun B and Fra-1 protein levels were increased by LNT, and ginsenoside Rd attenuated Jun B and Fra-1 protein levels induced by LNT. Furthermore, LNT increased AP-1 DNA binding activities, which were partially inhibited by ginsenoside Rd. Our results suggest that ginsenoside Rd exerts an inhibitory action against NO production via blocking phosphorylation of ERK, in turn, suppressing immediate early gene products such as Jun B and Fra-1 in C6 glioma cells.

Animals↗

PubMed2003

A rapid method for identification of typical Leuconostoc species by 16S rDNA PCR-RFLP analysis.

A polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method was developed to detect and identify typical Leuconostoc species. This method utilises a set of specific primers for amplification of the 16S rDNA region of typical Leuconostoc species. All Leuconostoc-type strains, all Leuconostoc isolates from kimchi, Korea's traditional, fermented vegetable product, and strains from closely related genera were examined to verify the identification by this method. The primers resulted in amplification only for nine typical Leuconostoc spp., but not for any other genera tested. The size of the amplified products was 976 bp and the amplicons of the different species could be differentiated from each other with MseI, HaeIII and Tsp509I endonucleases, except for the species Leuconostoc argentinum and Leuconostoc lactis, which were indistinguishable. A PCR-RFLP method for the typical Leuconostoc species was optimized to identify a large number of isolates from fermented vegetable product. This PCR-RFLP method enables the rapid and reliable identification of Leuconostoc species and to distinguish them from the other phylogenetically related lactic acid bacteria in food samples.

DNA, Bacterial↗

PubMed2003

Leuconostoc inhae sp. nov., a lactic acid bacterium isolated from kimchi.

Six strains of a hitherto unknown bacterium isolated from kimchi, a fermented vegetable food produced in Korea, were characterized by using phenotypic methods, phylogenetic analysis and DNA-DNA hybridization. The novel strains were gram-positive, non-spore-forming, heterofermentative and spherical or lenticular lactic acid bacteria. Comparative 16S rRNA gene sequencing and DNA relatedness demonstrated that the unknown strains represented a novel clade within the genus Leuconostoc and were close to, but distinct from, Leuconostoc gelidum. The unknown strains were clearly distinguished from all described members of the genus Leuconostoc by using RFLP pattems of genus-specific 16S rRNA gene PCR products with a single endonuclease, BsmAI. Based on the polyphasic evidence, the unknown isolates are classified as Leuconostoc inhae sp. nov. The type strain is strain IH003T (= KCTC 3774T = DSM 15101T).

Base Sequence↗

PubMed2002

Identification of Weissella species by the genus-specific amplified ribosomal DNA restriction analysis.

The Weissella species have been increasingly isolated from many food and meat samples. For rapid and systematic identification of Weissella species, an amplified ribosomal DNA restriction analysis (ARDRA) has been developed. This method employs both polymerase chain reaction (PCR) and restriction pattern analysis: first, PCR using the genus-specific primers that were designed from 16S rDNA sequence produces a 725-bp band only from Weissella species and next, restriction analysis using MnlI, MseI, and BceAI restriction enzymes identifies these Weissella-specific PCR fragments to the species level. This ARDRA method clearly identified six Weissella strains isolated from kimchi as well as 10 validly described Weissella type strains. Therefore, these results suggest that this ARDRA is a rapid and reliable method for identification of Weissella species.

Bacterial Typing Techniques↗

PubMedDate not supplied

Assessing the value of laser in situ keratomileusis by patient-reported outcomes using quality of life assessment.

PURPOSE: To assess the value of laser in situ keratomileusis (LASIK) by patient-reported outcomes using quality of life assessment. METHOD: This study included 288 consecutive patients treated by LASIK between July and December 2001 at two eye clinics. A Myopia-specific Quality of Life Questionnaire was developed in this study. The baseline quality of life corresponding to the situation where refractive error was corrected by glasses or contact lenses before LASIK treatment was evaluated by self-administered questionnaire. The evaluation was repeated at 4 days, and 1, 3, and 6 months after LASIK treatment. All question items were rated on a scale ranging from 1 (maximal dysfunction) to 5 (minimal dysfunction). RESULTS: Factor analysis identified 34 questions in 4 subscales-visual function, visual symptoms, social role function, and psychological well-being. The Myopia-specific Quality of Life Questionnaire subscales proved to be internally consistent (Cronbach alpha = 0.70-0.95). Criterion validity was assessed by evaluating Spearman correlation between the overall or domain-specific quality of life and traditional measures of patient status. Overall Myopia-specific Quality of Life Questionnaire score changed from 3.21 preoperatively to 3.76, 4.00, 4.07, and 4.11 at 4 days, and 1, 3, and 6 months after surgery, respectively. Social role function showed the biggest improvement (score change: 1.51, P < .05), followed by psychological well-being (0.90, P < .05), visual function (0.72, P < .05), and visual symptoms (0.49, P < .05). Regression analysis results showed that the degree of uncorrected visual acuity, discomfort associated with myopia preoperatively, and location of eye center were significant factors affecting the magnitude of changes in quality of life after LASIK. CONCLUSIONS: This study confirms that the value of LASIK went beyond the clinical achievement of refractive correction and extended to the improvement of quality of life.

Adolescent↗