Biomedical subjects

Young J Kim

Publications and source records attributed to Young J Kim.

17 recordsLinked to original sources

PubMed2006

Polycyclic aromatic hydrocarbons in bulk PM2.5 and size-segregated aerosol particle samples measured in an urban environment.

To analyze polycyclic aromatic hydrocarbons (PAHs) at an urban site in Seoul, South Korea, 24-hr ambient air PM2.5 samples were collected during five intensive sampling periods between November 1998 and December 1999. To determine the PAH size distribution, 3-day size-segregated aerosol samples were also collected in December 1999. Concentrations of the 16 PAHs in the PM2.5 particles ranged from 3.9 to 119.9 ng m(-3) with a mean of 24.3 ng m(-3). An exceptionally high concentration of PAHs( approximately 120 ng m(-3)) observed during a haze event in December 1999 was likely influenced more by diesel vehicle exhaust than by gasoline exhaust, as well as air stagnation, as evidenced by the low carbon monoxide/elemental carbon (CO/EC) ratio of 205 found in this study and results reported by previous studies. The total PAHs associated with the size-segregated particles showed unimodal distributions. Compared to the unimodal size distributions of PAHs with modal peaks at < 0.12 microm measured in highway tunnels in Los Angeles (Venkataraman and Friedlander, 1994), four- to six-ring PAHs in our study had unimodal size distributions, peaking at the larger size range of 0.28-0.53 microm, suggesting the coagulation of freshly emitted ultrafine particles during transport to the sampling site. Further, the fraction of PAHs associated with coarse particles(> 1.8 microm) increased as the molecular weight of the PAHs decreased due to volatilization of fine particles followed by condensation onto coarse particles.

Aerosols↗

PubMed2006

Fine-scale map of encyclopedia of DNA elements regions in the Korean population.

The International HapMap Project aims to generate detailed human genome variation maps by densely genotyping single-nucleotide polymorphisms (SNPs) in CEPH, Chinese, Japanese, and Yoruba samples. This will undoubtedly become an important facility for genetic studies of diseases and complex traits in the four populations. To address how the genetic information contained in such variation maps is transferable to other populations, the Korean government, industries, and academics have launched the Korean HapMap project to genotype high-density Encyclopedia of DNA Elements (ENCODE) regions in 90 Korean individuals. Here we show that the LD pattern, block structure, haplotype diversity, and recombination rate are highly concordant between Korean and the two HapMap Asian samples, particularly Japanese. The availability of information from both Chinese and Japanese samples helps to predict more accurately the possible performance of HapMap markers in Korean disease-gene studies. Tagging SNPs selected from the two HapMap Asian maps, especially the Japanese map, were shown to be very effective for Korean samples. These results demonstrate that the HapMap variation maps are robust in related populations and will serve as an important resource for the studies of the Korean population in particular.

Asian People↗

PubMed2006

T4 gastric carcinoma: the benefit of non-curative resection.

BACKGROUND: The prognosis of patients with gastric carcinoma with invasion of the adjacent organs (T4 gastric carcinoma) is very poor. We evaluated the survival benefit of resection in this group of patients. METHOD: We retrospectively reviewed the hospital records of 288 patients with T4 gastric carcinoma to compare the clinicopathological results in patients with curative resection (n = 95) with patients with non-curative resection (n = 193) during the period 1986-2000. RESULTS: With a 33% curative resectability in patients with T4 gastric carcinoma, patients with tumour resection (curative and non-curative) had a significantly improved survival rate. The overall survival rate was higher for patients who underwent resection (11.6%) than for patients who were not resected (2.5%), regardless of curability (P < 0.001). Using Cox's proportional hazard regression model, lymph node invasion and curability were independent statistically significant prognostic parameters. The prognosis of patients with invasion to the peritoneum and adrenal glands was significantly poorer than that of patients in whom there was no such invasion. But, the number of organs invaded had no effect on patient survival. CONCLUSIONS: Patients with T4 gastric carcinoma might be benefited from curative resection. The results also emphasize the improved survivorship of T4 gastric carcinoma patients with resection compared with those who did not undergo resection. Although curative resection cannot be undertaken in patients with T4 gastric carcinoma, we recommend performing resection in patients with locally advanced gastric carcinoma, regardless of curability.

Aged↗

PubMed2005

Visualization of a primary anti-tumor immune response by positron emission tomography.

Current methodologies that monitor immune responses rely on invasive techniques that sample tissues at a given point in time. New technologies are needed to elucidate the temporal patterns of immune responses and the spatial distribution of immune cells on a whole-body scale. We describe a noninvasive, quantitative, and tomographic approach to visualize a primary anti-tumor immune response by using positron emission tomography (PET). Bone marrow chimeric mice were generated by engraftment of hematopoietic stem and progenitor cells transduced with a trifusion reporter gene encoding synthetic Renilla luciferase (hRluc), EGFP, and Herpes virus thymidine kinase (sr39TK). Mice were challenged with the Moloney murine sarcoma and leukemia virus complex (M-MSV/M-MuLV), and the induced immune response was monitored by using PET. Hematopoietic cells were visualized by using 9-[4-[(18)F]fluoro-3-(hydroxymethyl)butyl]guanine ([(18)F]FHBG), a radioactive substrate specific for the sr39TK PET reporter protein. Immune cell localization and expansion were seen at the tumor and draining lymph nodes (DLNs). 2-[(18)F]fluoro-2-deoxy-D-glucose ([(18)F]FDG), which is sequestered in metabolically active cells, was used to follow tumor growth and regression. Elevated glucose metabolism was also seen in activated lymphocytes in the DLNs by using the [(18)F]FDG probe. When M-MSV/M-MuLV-challenged mice were treated with the immunosuppressive drug dexamethasone, activation and expansion of immune cell populations in the DLNs could no longer be detected with PET imaging. The method we describe can be used to kinetically measure the induction and therapeutic modulations of cell-mediated immune responses.

Animals↗

PubMed2005

Modulating the strength of cadherin adhesion: evidence for a novel adhesion complex.

Adherens junctions and desmosomes are critical for embryogenesis and the integrity of adult tissues. To form these junctions, classical cadherins interact via alpha- and beta-catenin with the actin cytoskeleton, whereas desmosomal cadherins interact with the intermediate filament system. Here, we used a hormone-activated mutant N-cadherin expressed in fibroblasts to show the existence of a novel classical cadherin adhesion system. N-cadherin was fused at its C-terminus to a modified estrogen receptor ligand-binding domain (NcadER) that binds 4-hydroxytamoxifen (4OHT) and expressed in L cells, which lack an endogenous cadherin. Cells with the mutant cadherin (LNER cells) aggregated in the absence of 4OHT, but only in its presence formed tightly compacted aggregates like those formed by L cells expressing wild-type N-cadherin (LN cells). Compaction of LNER cells treated with 4OHT was accompanied by elevated levels of p120ctn in NcadER immunoprecipitates, compared to immunoprecipitates of non-treated cells, but without changes in alpha- and beta-catenin, or actin. Compaction induced by 4OHT was also accompanied by increased interaction of the NcadER with the cytoskeleton and increased vimentin organization. Vimentin co-immunoprecipitated with the NcadER/catenin complex, suggesting an interaction between cadherin and vimentin. The mechanism by which vimentin interacts with the cadherin appears to involve p120ctn as it co-immunoprecipitates and colocalizes with vimentin in the parent L cells, which lack a cadherin and alpha- and beta-catenins. Disrupting the actin cytoskeleton with cytochalasin B inhibited aggregation, whereas knocking down vimentin with specific siRNAs inhibited compaction. Based on our results we propose that a vimentin-based classical cadherin complex functions together with the actin-based complex to promote strong cell-cell adhesion in fibroblasts.

Actins↗

PubMed2005

Simultaneous measurements of atmospheric pollutants and visibility with a Long-Path DOAS system in urban areas.

In this paper, the applicability of a Long-Path Differential Optical Absorption Spectroscopy (LP-DOAS) system was checked for the feasibility of the simultaneous measurement of trace gases (such as 03, NO2, SO2, and HCHO) and atmospheric visibility (light extinction by aerosols) in Asian urban areas. Field studies show that an LP-DOAS system can simultaneously measure the key pollutants (such as O3, NO2, SO2, and HCHO) at detection limits in the ppb/sub-ppb range as well as the Mie extinction coefficient with an uncertainty of approximately 0.1 km(-1) at time resolution of a few minutes. It is thus concluded that the use of LP-DOAS system is feasible for simultaneous measurement of gaseous pollutants as well as an atmospheric extinction coefficient which is tightly bound to fine particulate concentration.

Aerosols↗

PubMed2005

Effect of acidulated phosphate fluoride (APF) gel on the adherence of cariogenic bacteria to resin composites.

PURPOSE: To evaluate the effect of 1.23% acidulated phosphate fluoride (APF) and the subsequent polishing on the in vitro adherence of mutans streptococci to resin composites in a model that simulated the oral cavity conditions. METHODS: Samples of light-curing resin-based composites (Z100 and Z250) were treated with 1.23% APF gel (Sultan) for 1 minute and polished subsequently with Sof-Lex disks. The bacterial adherence of Streptococcus mutans and Streptococcus sobrinus to the APF gel treated resin samples and the subsequent polished samples were analyzed and compared with the adherence to the non-treated controls. RESULTS: The 1.23% APF gel caused a significant increase in the adherence of Streptococcus mutans and Streptococcus sobrinus. The increasing rate of the bacterial adherence to resin composites after APF treatment ranged from 73.5% to 167% and differed according to the bacterial strains. A decrease in the adherence of the bacteria was found after subsequent polishing with Sof-Lex disks.

Acidulated Phosphate Fluoride↗

PubMed2004

Source contributions to fine particulate matter in an urban atmosphere.

This paper proposes a practical method for estimating source attribution by using a three-step methodology. The main objective of this study is to explore the use of the three-step methodology for quantifying the source impacts of 24-h PM2.5 particles at an urban site in Seoul, Korea. 12-h PM2.5 samples were collected and analyzed for their elemental composition by ICP-AES/ICP-MS/AAS to generate the source composition profiles. In order to assess the daily average PM2.5 source impacts, 24-h PM2.5 and polycyclic aromatic hydrocarbons (PAH) ambient samples were simultaneously collected at the same site. The PM2.5 particle samples were then analyzed for trace elements. Ionic and carbonaceous species concentrations were measured by ICP-AES/ICP-MS/AAS, IC, and a selective thermal MnO2 oxidation method. The 12-h PM2.5 chemical data was used to estimate possible source signatures using the principal component analysis (PCA) and the absolute principal component scores method followed by the multiple linear regression analysis. The 24-h PM2.5 source categories were extracted with a combination of PM2.5 and some PAH chemical data using the PCA, and their quantitative source contributions were estimated by chemical mass balance (CMB) receptor model using the estimated source profiles and those in the literature. The results of PM2.5 source apportionment using the 12-h derived source composition profiles show that the CMB performance indices; chi2, R2, and percent of mass accounted for are 2.3%, 0.97%, and 100.7%, which are within the target range specified. According to the average PM2.5 source contribution estimate results, motor vehicle exhaust was the major contributor at the sampling site, contributing 26% on average of measured PM2.5 mass (41.8 microg m-3), followed by secondary sulfate (23%) and nitrate (16%), refuse incineration (15%), soil dust (13%), field burning (4%), oil combustion (2.7%), and marine aerosol (1.3%). It can be concluded that quantitative source attribution to PM2.5 in an urban area where source profiles have not been developed can be estimated using the proposed three-step methodology approach.

Air Pollutants↗

PubMed2004

LIDAR measurements of the vertical aerosol profile and optical depth during the ACE-Asia 2001 IOP, at Gosan, Jeju Island, Korea.

In order to investigate the characteristic of optical properties of Asian dust particles, the atmospheric aerosol vertical profile was measured with the multi-wavelength LIDAR system, at the Gosan super site (33 degrees 17'N, 126 degrees 10'E) in Jeju Island, Korea, during the ACE-Asia intensive observation period, 11 March-4 May 2001. An air mass backward trajectory analysis, using Hysplit-4, was carried out to track the aerosol plume, with high mass loading, from the Chinese desert regions during the period of Asian dust storm events. Vertical atmospheric aerosol profiles on three major Asian dust storm event days, 22 March and 13 and 26 April 2001, have been analyzed. The LIDAR-derived aerosol optical depth values were compared with those measured by a collocated sunphotometer.

Aerosols↗

PubMed2004

Chemical composition of post-harvest biomass burning aerosols in Gwangju, Korea.

The main objective of this study was to investigate the chemical characteristics of post-harvest biomass burning aerosols from field burning of barley straw in late spring and rice straw in late fall in rural areas of Korea. A 12-hr integrated intensive sampling of particulate matter (PM) with an aerodynamic diameter less than or equal to 10 microm (PM10) and PM with an aerodynamic diameter less than or equal to 2.5 microm (PM2.5) biomass burning aerosols had been conducted continuously in Gwangju, Korea, during two biomass burning periods: June 4--15, 2001, and October 8--November 14, 2002. The fine and coarse particles of biomass burning aerosols were analyzed for mass and ionic, elemental, and carbonaceous species. The average fine and coarse mass concentrations of biomass burning aerosols were, respectively, 129.6 and 24.2 microg/m3 in June 2001 and 47.1 and 33.2 microg/m3 in October--November 2002. An exceptionally high PM2.5 concentration of 157.8 microg/m3 was observed during biomass burning events under stagnant atmospheric conditions. In the fine mode, chlorine and potassium were unusually rich because of the high content of semi-arid vegetation. Both organic carbon (OC) and elemental carbon increased during the biomass burning periods, with the former exhibiting a higher abundance. PM from the open field burning of agricultural waste has an adverse impact on local air quality and regional climate.

Aerosols↗

PubMed2003

N-cadherin-catenin complexes form prior to cleavage of the proregion and transport to the plasma membrane.

Cadherins are calcium-dependent glycoproteins that function as cell-cell adhesion molecules and are linked to the actin cytoskeleton via catenins. Newly synthesized cadherins contain a prosequence that must be proteolytically removed to generate a functional adhesion molecule. The goal of this study was to examine the proteolytic processing of N-cadherin and the assembly of the cadherin-catenin complex in cells that express endogenous N-cadherin. A monoclonal antibody specific for the proregion of human N-cadherin was generated and used to examine N-cadherin processing. Our data show that newly synthesized proN-cadherin is phosphorylated and proteolytically processed prior to transport to the plasma membrane. In addition, we show that beta-catenin and plakoglobin associate only with phosphorylated proN-cadherin, whereas p120(ctn) can associate with both phosphorylated and non-phosphorylated proN-cadherin. Immunoprecipitations using anti-proN-cadherin showed that cadherin-catenin complexes are assembled prior to localization at the plasma membrane. These data suggest that a core N-cadherin-catenin complex assembles in the endoplasmic reticulum or Golgi compartment and is transported to the plasma membrane where linkage to the actin cytoskeleton can be established.

Actins↗

PubMed2003

The therapeutic relationship in child therapy: perspectives of children and mothers.

Examined qualities of the therapeutic relationship as perceived by low-income children who were in treatment for serious emotional disorders and their mothers. Recent emphasis on engaging families in the treatment of their children highlights the importance of understanding processes that facilitate therapeutic partnerships. Therapeutic bonds (i.e., the closeness of the relationship to therapist) for both children and their mothers were assessed. One-hundred fifty-seven families participated. Cross-sectional analyses indicated that children's perceptions of closeness with their therapists were associated with their perceptions of closeness with their mothers, their own age, and welfare status of the family. Maternal therapy bond scores were associated with mental health services efficacy and breadth of social support.

Adolescent↗

PubMed2002

A randomized, controlled trial of a community-based support program for families of children with chronic illness: pediatric outcomes.

BACKGROUND: Children with chronic illnesses have a heightened risk for mental health problems. OBJECTIVES: To develop, implement, and evaluate child outcomes of a 15-month, community-based, family-support intervention designed to reduce risk for poor adjustment and mental health problems in children with 1 of 4 chronic illnesses (diabetes mellitus, sickle cell anemia, cystic fibrosis, or moderate to severe asthma) and their mothers. DESIGN: Randomized, controlled clinical trial design with multiple measures of mental health based on both child and parent reports taken 1 year apart. SETTING: Community-based intervention linked to subspecialty and general pediatric clinics and practices in Baltimore, Md. PARTICIPANTS: One hundred thirty-six mothers and children aged 7 to 11 years with diabetes mellitus, sickle cell anemia, cystic fibrosis, or moderate to severe asthma. INTERVENTION: The program, provided by "experienced mothers" and child life specialists, included telephone contacts, face-to-face visits, and special family events. MAIN OUTCOME MEASURES: Outcomes were measured using the following instruments: the Personal Adjustment and Role Skills Scale III, the Children's Depression Inventory, the Revised Children's Manifest Anxiety Scale, and the Self-Perception Profile for Children. RESULTS: The experimental group's mean adjustment score increased over the intervention period while the control group's mean adjustment score decreased. Analysis of variance demonstrated that the intervention had a significant main effect on postintervention adjustment controlling for baseline scores (P =.01). Using a cutoff score indicating maladjustment, the percentage of experimental group children in the maladjustment range fell from 19% at baseline to 10% after the intervention; the percentage of control group children in the maladjustment range rose from 15% at baseline to 21% after the intervention. The effect of the intervention was more pronounced for children who had low physical self-esteem than for those who had moderate to high physical self-esteem at the beginning of the program. CONCLUSIONS: Our results demonstrate modest positive effects of a family support intervention in promoting the adjustment of children with selective chronic health conditions. Including child life specialists in a community-based intervention may be especially salient for children with chronic illnesses who have low physical self-esteem. The intervention had a similar outcome for all diagnostic groups, suggesting that it could be effective for children with any chronic illness and implemented in a variety of pediatric settings.

Anemia, Sickle Cell↗

PubMedDate not supplied

Multimodality imaging of lymphocytic migration using lentiviral-based transduction of a tri-fusion reporter gene.

PURPOSE: Previous work showed quantitative imaging of T-cell migration into a tumor site by positron emission tomography (PET), using retroviral transduction of mutated thymidine kinase (sr39TK) reporter genes into immunized T-lymphocytes. PROCEDURES AND RESULTS: In order to improve the sensitivity and flexibility of the imaging analysis, lentivirus, that expressed sr39TK, was used to transduce the lymphocytes that migrated to an immunogenic sarcoma site. In comparison to retrovirally transduced lymphocytes, the lentivirally transduced lymphocytes showed enhanced PET signal when equal numbers of transduced lymphocytes were transferred. Furthermore, in order to utilize multimodality in vivo imaging capability, a tri-fusion reporter gene containing sr39TK, synthetic Renilla luciferase (hRluc), and enhanced green fluorescent protein (eGFP) was inserted into a lentiviral transfer vector. Using the adoptive transfer model, tumor-specific lymphocytic migration was detected by both microPET scan and bioluminescence imaging. CONCLUSION: The multimodal imaging strategy coupled with lentiviral reporter construct delivery demonstrated here can facilitate future molecular imaging studies.

Animals↗

PubMedDate not supplied

N-cadherin-mediated cell motility requires cis dimers.

Cadherins are expressed on the cell surface as a dimer in the membrane of one cell (cis dimer) that interacts with a cis dimer on an adjacent cell to form an adhesive trans dimer. It is well established that both cis and trans dimers must form for the cadherin to be an effective adhesion protein. In addition to their adhesive activity cadherins also play an important role in modulating cell behavior by regulating cell motility and signal transduction. Whether or not cis or trans dimers are necessary for the nonadhesive functions of cadherins has not been addressed. Here we show that N-cadherin cis dimers are necessary to induce cell motility in epithelial cells and that N-cadherin's ability to modulate the steady state levels of activated small GTPases requires both cis and trans dimers.

Cadherins↗

PubMedDate not supplied

Incremental penetration depth estimation between convex polytopes using dual-space expansion.

We present a fast algorithm to estimate the penetration depth between convex polytopes in 3D. The algorithm incrementally seeks a "locally optimal solution" by walking on the surface of the Minkowski sums. The surface of the Minkowski sums is computed implicitly by constructing a local dual mapping on the Gauss map. We also present three heuristic techniques that are used to estimate the initial features used by the walking algorithm. We have implemented the algorithm and compared its performance with earlier approaches. In our experiments, the algorithm is able to estimate the penetration depth in about a milli-second on an 1 GHz Pentium PC. Moreover, its performance is almost independent of model complexity in environments with high coherence between successive instances.

Algorithms↗

PubMedDate not supplied

Interactive collision detection for deformable models using streaming AABBs.

We present an interactive and accurate collision detection algorithm for deformable, polygonal objects based on the streaming computational model. Our algorithm can detect all possible pairwise primitive-level intersections between two severely deforming models at highly interactive rates. In our streaming computational model, we consider a set of axis aligned bounding boxes (AABBs) that bound each of the given deformable objects as an input stream and perform massively-parallel pairwise, overlapping tests onto the incoming streams. As a result, we are able to prevent performance stalls in the streaming pipeline that can be caused by expensive indexing mechanism required by bounding volume hierarchy-based streaming algorithms. At runtime, as the underlying models deform over time, we employ a novel, streaming algorithm to update the geometric changes in the AABB streams. Moreover, in order to get only the computed result (i.e., collision results between AABBs) without reading back the entire output streams, we propose a streaming en/decoding strategy that can be performed in a hierarchical fashion. After determining overlapped AABBs, we perform a primitive-level (e.g., triangle) intersection checking on a serial computational model such as CPUs. We implemented the entire pipeline of our algorithm using off-the-shelf graphics processors (GPUs), such as nVIDIA GeForce 7800 GTX, for streaming computations, and Intel Dual Core 3.4G processors for serial computations. We benchmarked our algorithm with different models of varying complexities, ranging from 15K up to 50K triangles, under various deformation motions, and the timings were obtained as 30 approximately 100 FPS depending on the complexity of models and their relative configurations. Finally, we made comparisons with a well-known GPU-based collision detection algorithm, CULLIDE [4] and observed about three times performance improvement over the earlier approach. We also made comparisons with a SW-based AABB culling algorithm [2] and observed about two times improvement.

Algorithms↗