Biomedical subjects

Sunhee Lee

Publications and source records attributed to Sunhee Lee.

13 recordsLinked to original sources

PubMed2006

An approach for estimating exposure to ambient concentrations.

The degree of certainty in epidemiological studies is probably limited more by estimates of exposure than by any other component. We present a methodology for computing daily pollutant concentration fields that reduces exposure uncertainty and bias by taking account of spatial variation in air quality. This approach, using elliptical influence functions, involves the optimum blending of observations from a monitoring network with gridded pollution fields predicted by the complex air quality model TAPM. Such fields allow more information to be incorporated in the exposure fields used in epidemiological studies, rather than having to assume that ambient exposure is the same across a whole city and/or that individuals remain at the one location for the duration of a study.

Air Pollutants↗

PubMed2006

Protection elicited by two glutamine auxotrophs of Mycobacterium tuberculosis and in vivo growth phenotypes of the four unique glutamine synthetase mutants in a murine model.

We generated four individual glutamine synthetase (GS) mutants (DeltaglnA1, DeltaglnA2, DeltaglnA3, and DeltaglnA4) and one triple mutant (DeltaglnA1EA2) of Mycobacterium tuberculosis to investigate the roles of GS enzymes. Subcutaneous immunization with the DeltaglnA1EA2 and DeltaglnA1 glutamine auxotrophic mutants conferred protection on C57BL/6 mice against an aerosol challenge with virulent M. tuberculosis, which was comparable to that provided by Mycobacterium bovis BCG vaccination.

Animals↗

PubMed2005

Setting national priorities for quality assessment of health care services in Korea.

OBJECTIVE: To identify target services and determine national priorities among those services identified for a national quality assessment program of the Health Insurance Review Agency (HIRA) in Korea. DESIGN: Target services were identified from published sources addressing quality problems, various quality-monitoring programs in other countries, suggestions from 26 medical specialty associations in Korea, and frequently reported consumer claims. Three steps were involved in the prioritization decision: (i) development of a set of priority criteria; (ii) expert panel survey to evaluate the extent to which individual services satisfy each of the priority criteria and to calculate mean priority ratings for individual services; and (iii) formation of four levels of priority groups-top, high-middle, middle, and low-according to the allocated priority ratings. RESULTS: Five priority criteria were selected: "burden of the condition", "seriousness of the quality problem", "interest and demand of society", "acceptability", and "the feasibility of quality assessment". Among the 57 services identified as targets for the national quality assessment program, 10 were selected as having a top priority for quality assessment because of their high feasibility rating. These are: cardiac surgery; cataract surgery; tonsillectomy; appendectomy; tooth extraction; usage of albumin/globulin products; treatments for hypertension, pneumonia, and acute upper respiratory infection; and services provided by clinical laboratory centers. CONCLUSION: The priority services identified from the studies will assist the HIRA in selecting target services and implementing the national assessment program.

Acute Disease↗

PubMed2005

Canonical transient receptor potential channel 4 (TRPC4) co-localizes with the scaffolding protein ZO-1 in human fetal astrocytes in culture.

Members of the mammalian transient receptor potential (TRP) family form cation-permeable channels at the plasma membrane implicated in capacitative calcium influx after activation by either second-messenger-mediated pathways or store depletion, or both. This study shows that with the use of RT-PCR, Western blotting, and immunohistochemistry, resting astrocytes express TRPC4 at the cell membrane, particularly at sites of cell-to-cell contact. By confocal imaging and immunoelectron microscopy, we detected co-localization of TRPC4 with the scaffolding protein zonula occludens 1 (ZO-1), and demonstrated that immunoprecipitation with antibodies to ZO-1 brought down TRPC4, and vice-versa. It has been proposed that the targeting of TRPC4 to the cell membrane is dependent on the interaction of the C-terminal TRL motif with PDZ domains. Using transfection of astrocytes with myc-tagged TRPC4 or TRL-motif truncated TRPC4 (deltaTRL), we found that deltaTRL localized predominantly to a juxtanuclear compartment, whereas the wild-type protein showed cell surface distribution. Deletion of the TRL motif also reduced plasma membrane expression as assessed by cell surface biotinylation experiments. Using GST fusion proteins, we found that TRPC4 interacted with the PDZ1 domain of ZO-1 and that this was also dependent on the TRL motif. Thus, our data demonstrate that the PDZ-interacting domain of TRPC4 controls its cell surface localization. These data implicate TRPC4 in the regulation of calcium homeostasis in astrocytes, particularly as part of a signaling complex that forms at junctional sites between astrocytes.

Astrocytes↗

PubMed2004

Bxz1, a new generalized transducing phage for mycobacteria.

We have isolated and characterized a new generalized transducing phage, Bxz1, from soil sampling at a neighboring Wildlife Preservation Park. The hosts of the phage, measured by the formation of plaques, include fast growing Mycobacterium smegmatis and Mycobacterium vaccae. Bxz1 is capable of transducing chromosomal markers, point mutations, and plasmids at frequencies ranging from 10(-8) to 10(-6) per plaque forming unit between strains of M. smegmatis. We also demonstrated cotransduction of a transposon insertion linked to a point mutation of the ndh gene.

Conjugation, Genetic↗

PubMed2004

A novel action of minocycline: inhibition of human immunodeficiency virus type 1 infection in microglia.

Human immunodeficiency virus type 1 (HIV-1) infection of the brain produces a characteristic disease called acquired immunodeficiency syndrome (AIDS) dementia in which productive infection and inflammatory activation of microglia and macrophages play a central role. In this report, the authors demonstrate that minocycline (MC), a second-generation tetracycline with proven safety and penetration to the central nervous system, potently inhibited viral production from microglia. Inhibition of viral release was sustained through the entire course of infection and even when the drug exposure was limited to the first day of infection. Minocycline was effective even at low viral doses, and against R5- and X4R5-HIV, as well as in single-cycle reporter virus assays. Electrophoretic mobility shift analysis showed that minocycline inhibited nuclear factor (NF)-kappaB activation in microglia. HIV-1 long terminal repeat (LTR)-promoter activity in U38 cells was also inhibited. These results, combined with recently demonstrated in vivo anti-inflammatory effects of MC on microglia, suggest a potential utility for MC as an effective adjunct therapy for AIDS dementia.

Cell Culture Techniques↗

PubMed2004

The impact of visit frequency on the relationship between service quality and outpatient satisfaction: a South Korean study.

OBJECTIVE: To examine the relative impact of four service quality dimensions on outpatient satisfaction and to test the invariance of the structural relationships between the service quality dimensions and satisfaction across three patient groups of varying numbers of prior visits to the same hospital as outpatients. DATA SOURCES/STUDY SETTING: Survey of 557 outpatients using a self-administered questionnaire over a 10-day period at a general hospital in Sungnam, South Korea. DATA COLLECTION: Patients answered questions related to two main constructs, patient satisfaction and health care service quality. The health care service quality measures (30 items) were developed based on the results of three focus group interviews and the SERVQUAL scale, while satisfaction (3 items) was measured using a previously validated scale. STUDY DESIGN: Confirmatory factor analysis was used to assess the construct validity of the service quality scale by testing convergent and divergent validity. A structural equation model specifying the four service quality dimensions as exogenous variables and patient satisfaction as an endogenous variable was estimated to assess the relative impact of each of the service quality dimensions on satisfaction. This was followed by a multigroup LISREL analysis that tested the invariance of structural coefficients across three groups with different frequencies of outpatient visits to the hospital. PRINCIPAL FINDINGS: Findings support the causal relationship between service quality and satisfaction in the context of the South Korean health care environment. The four service quality dimensions showed varying patterns of impact on patient satisfaction across the three different outpatient groups. CONCLUSION: The hospital management needs to be aware of the relative importance of each of the service quality dimensions in satisfaction formation of outpatients, which varies across different hospital utilization groups, and use this in strategic considerations.

Adult↗

PubMed2004

Indole-3-acetic acid biosynthesis is deficient in Gluconacetobacter diazotrophicus strains with mutations in cytochrome c biogenesis genes.

Gluconacetobacter diazotrophicus is an endophyte of sugarcane frequently found in plants grown in agricultural areas where nitrogen fertilizer input is low. Recent results from this laboratory, using mutant strains of G. diazotrophicus unable to fix nitrogen, suggested that there are two beneficial effects of G. diazotrophicus on sugarcane growth: one dependent and one not dependent on nitrogen fixation. A plant growth-promoting substance, such as indole-3-acetic acid (IAA), known to be produced by G. diazotrophicus, could be a nitrogen fixation-independent factor. One strain, MAd10, isolated by screening a library of Tn5 mutants, released only approximately 6% of the amount of IAA excreted by the parent strain in liquid culture. The mutation causing the IAA(-) phenotype was not linked to Tn5. A pLAFR3 cosmid clone that complemented the IAA deficiency was isolated. Sequence analysis of a complementing subclone indicated the presence of genes involved in cytochrome c biogenesis (ccm, for cytochrome c maturation). The G. diazotrophicus ccm operon was sequenced; the individual ccm gene products were 37 to 52% identical to ccm gene products of Escherichia coli and equivalent cyc genes of Bradyrhizobium japonicum. Although several ccm mutant phenotypes have been described in the literature, there are no reports of ccm gene products being involved in IAA production. Spectral analysis, heme-associated peroxidase activities, and respiratory activities of the cell membranes revealed that the ccm genes of G. diazotrophicus are involved in cytochrome c biogenesis.

Bacterial Proteins↗

PubMed2003

Structural relationship of factors affecting health promotion behaviors of Korean urban residents.

Voluntary cooperation is crucial in determining the effectiveness of a health promotion strategy. The Triandis model, a theoretical model with the advantages of the Fishbein model, is useful in directly explaining health behavior. The purpose of this study was to perform a comprehensive evaluation of behavioral tendency related to health promotion and to examine the interrelationship amongst factors related to health behavior. This study uses the Triandis model to examine the structural relationship between explaining variables of health promotion. Five-hundred and nine residents were selected by multi-stage random sampling from the province of Kyungi-do, Korea. A structured questionnaire based on the Triandis model was developed. This questionnaire was distributed to the selected residents and their responses were collected via face-to-face interviews. The results showed that expectation of behavioral consequence, social norm and age variables were significantly related to health behavioral tendency. In addition, facilitating factors, affect variable and education level were indirectly related to health behavior. The results suggest that integrating behavioral subsets may be useful for understanding the mechanism of individual health promotion behavioral tendency.

Adult↗

PubMed2002

Vpr- and Nef-dependent induction of RANTES/CCL5 in microglial cells.

Microglia are pivotal in the pathogenesis of AIDS dementia, as they serve as the major target of HIV infection in the CNS. In addition, activation of microglia correlates best with clinical dementia. Although the beta-chemokine RANTES/CCL5 is important in modulating HIV infection as well as cellular activation, no information is available regarding how its expression is regulated in microglia by HIV-1. Here we report that RANTES/CCL5 expression is induced in microglia by HIV-1, but that this requires infection by HIV-1. This conclusion was supported by (1) the delayed kinetics coinciding with viral replication; (2) the lack of effect of X4 viruses; (3) inhibition by the reverse transcriptase inhibitor AZT, and (4) the lack of effect of cytokine antagonists or antibodies. Interestingly, RANTES/CCL5 production was dependent on the viral accessory protein Vpr, in addition to Nef, demonstrating a novel role for Vpr in chemokine induction in primary macrophage-type cells. Furthermore, the specific p38 MAP kinase inhibitor SB203580 augmented chemokine expression in microglia, indicating a negative role played by p38. These data suggest unique features of RANTES/CCL5 regulation by HIV-1 in human microglial cells.

Animals↗

PubMed2002

Pathological CNS autoimmune disease triggered by traumatic spinal cord injury: implications for autoimmune vaccine therapy.

Lymphocytes respond to myelin proteins after spinal cord injury (SCI) and may contribute to post-traumatic secondary degeneration. However, there is increasing evidence that autoreactive T-lymphocytes may also convey neuroprotection and promote functional recovery after CNS injury. To clarify the role of myelin autoreactive lymphocytes after SCI, we performed contusion injuries in the thoracic spinal cord of transgenic (Tg) mice in which >95% of all CD4+ T-lymphocytes are reactive with myelin basic protein (MBP). We observed significantly impaired recovery of locomotor and reflex function in Tg mice compared with non-Tg (nTg) littermates. Measures of functional impairment in Tg mice correlated with significantly less white matter at the injury site, and morphometric comparisons of injured Tg and nTg spinal cords revealed increased rostrocaudal lesion expansion (i.e., secondary degeneration) in Tg mice. Rostrocaudal to the impact site in SCI-nTg mice, demyelination was restricted to the dorsal funiculus, i.e., axons undergoing Wallerian degeneration. The remaining white matter appeared normal. In contrast, lymphocytes were colocalized with regions of demyelination and axon loss throughout the white matter of SCI-Tg mice. Impaired neurological function and exacerbated neuropathology in SCI-Tg mice were associated with increased intraspinal production of proinflammatory cytokine mRNA; neurotrophin mRNA was not elevated. These data suggest that endogenous MBP-reactive lymphocytes, activated by traumatic SCI, can contribute to tissue injury and impair functional recovery. Any neuroprotection afforded by myelin-reactive T-cells is likely to be an indirect effect mediated by other non-CNS-reactive lymphocytes. Similar to the Tg mice in this study, a subset of humans that are genetically predisposed to autoimmune diseases of the CNS may be adversely affected by vaccine therapies designed to boost autoreactive lymphocyte responses after CNS trauma. Consequently, the safe implementation of such therapies requires that future studies define the mechanisms that control T-cell function within the injured CNS.

Animals↗

PubMed2002

Relationships between conscientiousness, self-efficacy, self-deception, and learning over time.

The present study examined the dual mediating effects of self-efficacy and self-deception on the relationship between conscientiousness and learning over time. Data from 134 college students were used to investigate the relative impact of self-efficacy and self-deception. Consistent with the hypothesized model, conscientiousness was significantly and positively related to both early training self-efficacy and self-deception, and both self-efficacy and self-deception had significant effects on learning but in opposite directions. Furthermore, the relative impact of self-efficacy and self-deception on learning changed over time as expected. The negative effect of self-deception in early stages of training disappeared at later stages of training but the positive effects of self-efficacy remained. Support was not found for self-efficacy and self-deception as mediators of the conscientiousness-learning relationship.

Adult↗

PubMed2002

Assessing the factors influencing continuous quality improvement implementation: experience in Korean hospitals.

OBJECTIVE: To assess the extent of continuous quality improvement (CQI) implementation in Korean hospitals and to identify its influencing factors. DESIGN: Cross-sectional study by mailed questionnaire survey. STUDY PARTICIPANTS: One hundred and seventeen staff members with responsibility for CQI at 67 hospitals with > or = 400 beds. MAIN OUTCOME MEASURES: The degree of CQI implementation was measured using the Malcolm Baldrige National Quality Award Criteria (MBNQAC). Factors related to the degree of CQI implementation were the four components of the CQI pyramid, namely the cultural, technical, strategic, and structural attributes of individual hospitals. RESULTS: The average CQI implementation score across the seven dimensions by MBNQAC was 3.34 on a 5-point scale. The highest score was achieved in the dimension of 'customer satisfaction' (3.88), followed by 'information/analysis' (3.59), and 'quality management' (3.35). Regression analysis showed that hospitals which better fulfilled technical requirements, such as improving information systems (P< 0.05), using more scientific CQI tools, and adopting systematic problem-solving approaches (P<0.01), tended to achieve higher degrees of CQI implementation. Although statistically insignificant, positive trends were observed for group/developmental culture and the degree of employee empowerment, and the use of prospective strategy. CONCLUSION: It appears that the most important contributing factors to active CQI implementation in Korean hospitals were the use of scientific skills in decision-making and the adoption of a quality information system capable of producing precise and valid information.

Benchmarking↗