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Biomedical subjects

D K Kim

Publications and source records attributed to D K Kim.

At least 19 recordsLinked to original sources
PubMed2007

Bronchial responsiveness to methacholine and adenosine 5'-monophosphate in atopic and non-atopic preschool children with recurrent wheezing.

BACKGROUND: It is well known that atopy is a major determinant of bronchial hyper-responsiveness (BHR) in both asymptomatic and asthmatic children. However, the relationship between atopy and BHR has not been well studied in preschool children with wheezing. BHR is usually measured by bronchial challenges using direct and indirect stimuli. OBJECTIVE: The aim of this study was to investigate whether atopic and non-atopic preschool wheezers display similar or different BHR profiles for direct and indirect stimuli. METHODS: Methacholine and adenosine 5'-monophosphate (AMP) bronchial challenges were performed in 4 to 6-year-old children with recurrent wheezing, using a modified auscultation method. The end-point was defined as the appearance of wheezing and/or oxygen desaturation. Atopy was determined to be present when a child had at least one positive reaction to a panel of 13 common airborne allergens in the presence of positive and negative controls. RESULTS: A positive response to methacholine (an end-point concentration < or =8 mg/mL) was observed in 89.3% (50/56) of atopic wheezers and in 83.8% (31/37) of non-atopic wheezers (P=0.44) for the difference. By contrast, the frequency of a positive response to AMP (an end-point concentration < or =200 mg/mL) was significantly higher in the atopic group (47/56, 83.9%) compared with the non-atopic group (12/37, 32.4%; P<0.01). CONCLUSION: While a majority of both atopic and non-atopic preschool wheezers were hyper-responsive to methacholine, atopic subjects were more hyper-responsive to AMP than non-atopic subjects. These findings suggest that atopic and non-atopic wheeze in preschool children are related to distinctive pathophysiologic pathways.

Adenosine Monophosphate↗
PubMed2006

A novel missense mutation of SLC7A9 frequent in Japanese cystinuria cases affecting the C-terminus of the transporter.

Cystinuria is caused by the inherited defect of apical membrane transport systems for cystine and dibasic amino acids in renal proximal tubules. Mutations in either SLC7A9 or SLC3A1 gene result in cystinuria. The mutations of SLC7A9 gene have been identified mainly from Italian, Libyan Jewish, North American, and Spanish patients. In the present study, we have analyzed cystinuria cases from oriental population (mostly Japanese). Mutation analyses of SLC7A9 and SLC3A1 genes were performed on 41 cystinuria patients. The uptake of 14C-labeled cystine in COS-7 cells was measured to determine the functional properties of mutants. The protein expression and localization were examined by Western blot and confocal laser-scanning microscopy. Among 41 patients analyzed, 35 were found to possess mutations in SLC7A9. The most frequent one was a novel missense mutation P482L that affects a residue near the C-terminus end of the protein and causes severe loss of function. In MDCK II and HEK293 cells, we found that P482L protein was expressed and sorted to the plasma membrane as well as wild type. The alteration of Pro482 with amino acids with bulky side chains reduced the transport function of b(0,+)AT/BAT1. Interestingly, the mutations of SLC7A9 for Japanese cystinuria patients are different from those reported for European and American population. The results of the present study contribute toward understanding the distribution and frequency of cystinuria-related mutations of SLC7A9.

Amino Acid Substitution↗
PubMed2006

Methacholine and adenosine 5'-monophosphate challenges in children with post-infectious bronchiolitis obliterans.

Airway hyperresponsiveness (AHR) is a characteristic feature of asthma, but is also frequently demonstrated by children and adults with chronic obstructive lung diseases. AHR is usually measured by bronchial challenges using direct or indirect stimuli. The aim of this study was to compare these two types of bronchial challenge in children with post-infectious bronchiolitis obliterans (BO). Methacholine and adenosine 5'-monophosphate (AMP) challenges were used as tools for the evaluation of AHR to direct and indirect stimuli, respectively, in children with post-infectious BO (n = 28). These results were compared with those of asthmatic (n = 30) and control children (n = 25). Altogether, twenty-two patients (78.6%) with post-infectious BO were hyperreactive to methacholine with a provocative concentration causing a 20% fall in forced expiratory volume in one second (PC20) of <16 mg x mL(-1), but only six (21.4%) were hyperreactive to AMP with a PC20 of <200 mg x mL(-1). All patients with asthma responded positively to methacholine, and most (28, 93.3%) also responded positively to AMP. The majority of controls were insensitive to both challenges. Airway hyperresponsiveness to methacholine is a frequent, but by no means universal, finding in children with post-infectious bronchiolitis obliterans, but is usually not accompanied by airway hyperresponsiveness to adenosine 5'-monophosphate. This finding suggests that airway hyperresponsiveness in patients with post-infectious bronchiolitis obliterans has characteristics that differ from those of asthmatic subjects.

Adenosine Monophosphate↗
PubMed2005

Analysis of testis-specific transcripts in the chicken.

Sequences of candidate chicken testis-specific genes were analysed in order to develop a resource for functional genomic studies of the testis and male germ cells. Tentative consensus sequences (TC) containing expressed sequence tags expressed in testis libraries were selected from the TIGR Gallus gallus Gene Index, resulting in 292 TC. The transcriptional expression of these genes were evaluated in several chicken tissues, including testis and ovary. One hundred ten of the 292 TC were expressed in a testis-specific manner. Annotation of the TC using the Gene Ontology database terms showed that the proportion of testis-specific TC that were classified as having catalytic activity (within the molecular function branch) was higher than the proportion of total chicken TC classified in the same way. Our results may facilitate the investigation of testis-specific genes and their functional analysis in the chicken, as well as in other avian species.

Animals↗
PubMed2005

A set of testis-specific novel genes collected from a collection of Korean Native Chicken ESTs.

We report a set of testis-specific novel genes by comparing the The Institute for Genomic Research (TIGR) chicken gene index with the 13,132 expressed sequence tag (EST) collection from Korean Native Chicken (KNC). A total of 553 novel transcripts have resulted after comparison of our EST contigs and singlets against the chicken gene index and chicken genome sequences. Interestingly, 76% of the new genes were from testis-specific EST contigs or singlet and analysis of exon/intron structure showed that a significant number of the contigs have intronless coding regions. A large portion of the testis-specific transcripts have intronless coding region indicating that the testis-specific expression pattern is related to a group of single exon genes in the chicken. The chicken EST data that are described in this paper have been submitted to the NCBI dbEST under accession numbers CO759017-CO764274, CO765331-CO768903 and CO769672-CO773972.

Animals↗
PubMed2005

Coincidence of atopy profile in terms of monosensitization and polysensitization in children and their parents.

BACKGROUND: Results from epidemiologic studies have shown that childhood atopy is probably a hereditary disorder, because the offspring of affected parents have a higher risk of developing atopy. Among the atopic population, some subjects are sensitized to only one class of allergens (monosensitized), while other subjects are sensitized to more than one class of allergens (polysensitized). The aim of this study was to investigate whether atopy profile (monosensitization/polysensitization) in children is linked to the same conditions in their parents. METHODS: We evaluated sensitization to five classes of aeroallergens (house dust mites, animal danders, pollens, molds, and cockroach) by skin prick testing in a group of 494 children with suspicious allergic symptoms and in their parents. RESULTS: The frequency of parental atopy was highest (51.6%) in polysensitized children (n = 189), intermediate (37.1%) in monosensitized children (n = 178), and was lowest (22.4%) in nonsensitized children (n = 127). The proportion of polysensitized subjects among atopic parents was significantly higher for polysensitized children (45.6%) than for monosensitized children (31.1%). Polysensitized children were found to more frequently have one or both parents polysensitized (32.3%, 7.4%) than monosensitized children (18.5%, 2.2%) with odds ratios of 2.09 (95% CI: 1.29-3.40) and 3.48 (1.12-10.78), respectively, whereas the likelihood of having one or two monosensitized parents was not increased for polysensitized children. CONCLUSION: Our data suggest a familial coincidence of atopy profile in terms of monosensitization and polysensitization, although the relative importance of genetic or environmental influence should be studied further.

Allergens↗
PubMed2005

Birth month and sensitization to house dust mites in asthmatic children.

BACKGROUND: Early exposure to high quantities of allergen has an important role in the incidence of atopic sensitization. In fact, subjects sensitized to house dust mites (HDMs) have a significantly higher proportion of births in the season when HDMs are most abundant. OBJECTIVE: The aim of this study was to investigate whether birth month patterns differ for asthmatic patients sensitized only to HDMs and for those sensitized to HDMs and other allergen(s). METHODS: Among 2225 patients with asthma, aged 10-16 years, 1642 sensitized to HDMs were identified by skin prick testing. This group was composed of patients sensitized only to HDMs (n = 715) and patients sensitized to HDMs and other allergen(s) (n = 927). The birth month distributions of the group of HDM-sensitive asthmatics or its subgroups were compared with that of a reference population (total live births in the same years as the studied subjects). The risk ratio of a given birth month in relation to all the other months was calculated as an odds ratio (OR) with the corresponding 95% confidence interval (CI). RESULTS: A significant difference in birth month distribution was observed for HDM-sensitive asthmatics (chi(2) = 23.6, P = 0.015), with higher rates of birth in August (OR: 1.23, 95% CI: 1.04-1.46) and September (1.24, 1.04-1.46). When the two subgroups were analyzed separately, significantly more births were noted in August (1.34, 1.06-1.71) and September (1.34, 1.05-1.70) for those sensitized only to HDMs, whereas no such birth month preference was observed for those sensitized to HDMs and other allergen(s). CONCLUSIONS: The HDM-positive asthmatics showed a greater proportion of births in August and September, which correspond to high HDM exposure. However, this birth month pattern was evident in asthmatic-sensitive only to HDMs, but was not observed in those sensitive to HDMs and other allergen(s).

Adolescent↗
PubMed2004

Morphological and photoelectrochemical characterization of core-shell nanoparticle films for dye-sensitized solar cells: Zn-O type shell on SnO2 and TiO2 cores.

Core-shell type nanoparticles with SnO2 and TiO2 cores and zinc oxide shells were prepared and characterized by surface sensitive techniques. The influence of the structure of the ZnO shell and the morphology ofnanoparticle films on the performance was evaluated. X-ray absorption near-edge structure and extended X-ray absorption fine structure studies show the presence of thin ZnO-like shells around the nanoparticles at low Zn levels. In the case of SnO2 cores, ZnO nanocrystals are formed at high Zn/Sn ratios (ca. 0.5). Scanning electron microscopy studies show that Zn modification of SnO2 nanoparticles changes the film morphology from a compact mesoporous structure to a less dense macroporous structure. In contrast, Zn modification of TiO2 nanoparticles has no apparent influence on film morphology. For SnO2 cores, adding ZnO improves the solar cell efficiency by increasing light scattering and dye uptake and decreasing recombination. In contrast, adding a ZnO shell to the TiO2 core decreases the cell efficiency, largely owing to a loss of photocurrent resulting from slow electron transport associated with the buildup of the ZnO surface layer.

Journal Article↗
PubMed2004

Synchronous delivery systems composed of Au nanoparticles and stimuli-sensitive diblock terpolymer.

A method to construct synchronous delivery systems via direct self-assembly of Au nanoparticles on the poly[(N-isopropylacrylamide-r-acrylamide)-b-L-lactic acid] (PNAL) nanospheres has been presented in this paper. To achieve amphiphilic diblock terpolymer, hydrophobic poly (L-lactic acid) (PLLA) block was added to poly(N-isopropylacrylamide- r-acrylamide) (PNA) block via Michel-type addition reaction. Lower critical solubility temperature (LCST) was modulated at 35.6 degrees C which is close to the body temperature, but higher than poly(N-isopropylacrylamide) (PNIPAAm) homopolymer by controlling the ratio between isopropylacrylamide (IPAAm) monomers and acrylamide (AAm) monomers. Using this amphiphilic diblock terpolymer, PNAL nanospheres were fabricated by emulsion/evaporation technique followed by direct self-assembly of Au nanoparticles on the PNAL nanospheres due to the high affinity of amino groups donated from PNA block. The 'core' site of Au@PNAL nanospheres can load various lyphophilic drugs. Moreover, Au nanoparticles in the 'shell' domain of PNAL nanospheres give optimal environment to conjugate various biomolecules. Therefore, it is expected that Au@PNAL hybrid nanospheres can be utilized in synchronous delivery of both biomolecules in the 'shell' domain and various therapeutic drugs in the 'core' domain.

Acrylic Resins↗
PubMed2004

Preferential expression of L-type amino acid transporter 1 in ameloblasts during rat tooth development.

Certain amino acid transport systems play an important role in supplying organic nutrients to each cell and for cell proliferation during tooth development. However, the mechanisms responsible for such actions are unclear. This study demonstrated for the first time that LAT1 and 4F2hc are expressed during tooth development in prenatal and postnatal rats, and that the transporters show cell-specific expression in ameloblasts, which are the epithelium-derived dental cells. LAT1 and 4F2hc expression was not observed in other dental cells of the developing teeth such as odontoblasts and cementoblasts. Overall, these results suggest that LAT1 and 4F2hc might play an important role in enamel formation.

Ameloblasts↗
PubMed2004

Performance of a web-based, realtime, tele-ultrasound consultation system over high-speed commercial telecommunication lines.

A Web-based, realtime, tele-ultrasound consultation system was designed. The system employed ActiveX control, MPEG-4 coding of full-resolution ultrasound video (640 x 480 pixels at 30 frames/s) and H.320 videoconferencing. It could be used via a Web browser. The system was evaluated over three types of commercial line: a cable connection, ADSL and VDSL. Three radiologists assessed the quality of compressed and uncompressed ultrasound video-sequences from 16 cases (10 abnormal livers, four abnormal kidneys and two abnormal gallbladders). The radiologists' scores showed that, at a given frame rate, increasing the bit rate was associated with increasing quality; however, at a certain threshold bit rate the quality did not increase significantly. The peak signal to noise ratio (PSNR) was also measured between the compressed and uncompressed images. In most cases, the PSNR increased as the bit rate increased, and increased as the number of dropped frames increased. There was a threshold bit rate, at a given frame rate, at which the PSNR did not improve significantly. Taking into account both sets of threshold values, a bit rate of more than 0.6 Mbit/s, at 30 frames/s, is suggested as the threshold for the maintenance of diagnostic image quality.

Data Compression↗
PubMed2003

A double-blind, randomised- placebo, controlled, parallel group, multicentre, flexible-dose escalation study to assess the efficacy and safety of sildenafil administered as required to male outpatients with erectile dysfunction in Korea.

The efficacy and safety of sildenafil was evaluated in a randomiSed, double-blind, placebo-controlled, flexible-dose study in Korean men aged 28-78 y with erectile dysfunction (ED) of broad-spectrum aetiology and more than 6 months duration. A total of 133 patients were randomised at six centres in Korea to receive either sildenafil (50 mg initially, increased if necessary to l00 mg or decreased to 25 mg depending on efficacy and tolerance) (n=66) or matching placebo (n=67) taken on an 'as needed' basis l h prior to anticipated sexual activity for a period of 8 weeks. At the end of this time, the primary efficacy variables relating to the achievement and maintenance of erections sufficient for sexual intercourse, and the secondary efficacy variables, which included: (1) the five separate domains of sexual functioning of the International Index of Erectile Function (IIEF) scale, (2) the percentage of successful intercourse attempts, and (3) a global assessment of erections, were all statistically significantly improved by sildenafil in comparison with placebo (P&<0.0001). Treatment-related adverse events occurred in 56.1% of patients receiving sildenafil and 20.9% receiving placebo. The most common adverse events with sildenafil were vasodilatation (flushing), headache and abnormalities in colour vision (31.8, 22.7 and 6.1% of patients, respectively), and most were mild in nature. The efficacy and safety of sildenafil in this population of Korean men appears similar to that reported in other studies in western populations.

Adult↗
PubMed2002

Fenofibrate lowers abdominal and skeletal adiposity and improves insulin sensitivity in OLETF rats.

The effect of peroxisome proliferator-activated receptor (PPAR)-alpha activators on the liver is well established, but the other effects on muscle and adipose tissue about lipid metabolism and insulin sensitivity are not clear. We investigated whether PPAR-alpha activation affects adiposity of skeletal muscle as well as adipose tissue and improves insulin sensitivity in spontaneous type 2 diabetes model, Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Thirty-three weeks of aged, 20 male OLETF rats were divided into two groups. Control group (n=10) was fed with chow and treatment group (n=10) with chow contained fenofibrate for 7 weeks. At the age of 40 weeks, all rats were examined with MRI, intravenous glucose tolerance test, and then sacrificed for measurement of fat mass and RNA analyses. The total fat (the sum of subcutaneous, mesenteric, epididymal, and retroperitoneal fat pads) measured by dissection was significantly reduced in treatment group. The signal intensity of muscular adiposity was significantly decreased in treatment group. The mRNA levels of FAT/CD36 and mitochondrial carnitine palmitoyltransferase I (M-CPT I) in liver were remarkably increased. Fasting plasma insulin and leptin levels, insulin response after intravenous glucose loading and homeostasis model assessment insulin resistance (HOMA(IR)) index were lowered in treatment group. Fenofibrate increase mitochondrial fatty acid beta-oxidation in liver but not in skeletal muscle and lower the plasma levels of triglyceride and free fatty acid. It might result in reduction of adiposity of truncal adipose tissue and skeletal muscle. We suggest that reduction of adiposity in trunk and skeletal muscle might improve insulin sensitivity.

Abdomen↗
PubMed2002

Development of the Korean versions of WHO Quality of Life scale and WHOQOL-BREF.

The purpose of this study was to develop the Korean version of World Health Organization Quality of Life study assessment instrument (WHOQOL) and WHOQOL-BREF, an abbreviated version of WHOQOL and to identify contributing factors in the quality of life of Koreans. The WHOQOL and WHOQOL-BREF were translated into colloquial Korean according to instructions of the WHOQOL study group. Then the Korean questionnaire was applied to 538 subjects, composed of 171 medical patients and 367 healthy subjects who volunteered to rate the scale. Finally, 486 subjects completed the rating. Collected data were analyzed statistically. The Korean version of WHOQOL and WHOQOL-BREF domain scores demonstrated good test-retest reliability, internal consistency, criterion validity, content validity and discriminant validity. The physical, psychological, social and environmental domains made a significant contribution to explaining the variance in the quality of life while the independence and spiritual domains made a lesser contribution. The domain scores produced by the WHOQOL-BREF correlated highly with the WHOQOL. The physical health domain contributed most in overall quality of life, while the social domain made the least contribution. These results suggest that the Korean version of WHOQOL and WHOQOL-BREF are valid and reliable in the assessment of quality of life and that physical domain is contributing most and social and spiritual factors are contributing least to the quality of life in Koreans.

Adult↗
PubMed2001

A transmembrane trap method for efficient cloning of genes encoding proteins possessing transmembrane domain.

To facilitate searching for genes encoding cell membrane proteins, we developed a method for isolating cDNAs that contain sequences for hydrophobic transmembrane runs. This cloning strategy, termed the "transmembrane (TM) trap method," utilizes a vector that directs the cell surface expression of mouse CD4 fusion protein when an insert encoding hydrophobic transmembrane sequences is cloned in-frame with correct orientation. We applied this novel method to isolation of cytokine receptor cDNAs. Our strategy enabled efficient isolation of relatively rare species encoding receptors such as IL-2Rgamma, IL-3Rbeta, IL-4Ralpha, IL-5Ralpha, and IL-6Ralpha. This method also could be used to isolate cDNAs for intracellular molecules with a transmembrane region, e.g., bcl-2. These results indicate that the TM trap method provides an efficient cloning strategy for identification of various families of genes encoding proteins with one or more transmembrane regions.

Animals↗
PubMed2001

Constitutive hyperexpression of p21(WAF1) in human U266 myeloma cells blocks the lethal signaling induced by oxidative stress but not by Fas.

p21(WAF1/CIP1) is expressed in a majority of myeloma cells. To investigate the role of p21 in myeloma cell death, comparative studies using two clones of myeloma cells, Fas-sensitive RPMI8226, and Fas-resistant U266 were performed. These latter cells were also resistant to H(2)O(2) up to 100 microM, whereas the former cells were not. SAPK/JNK was found to be a common mediator of RPMI8226 cell death induced by both H(2)O(2) and Fas. Interestingly, the concentrations of H(2)O(2) which activated SAPK/JNK in RPMI8226 cells failed to do so in U266 cells. In contrast, Fas ligation activated SAPK/JNK in both cells almost equally. U266 cells expressed p21 to levels much higher than in RPMI8226 cells. When the p21 levels were reduced using its antisense, H(2)O(2) killed U266 cells by activating SAPK/JNK. However, the reduction in p21 levels neither rendered the U266 cells susceptible to Fas-mediated cell death, nor significantly influenced Fas-induced SAPK/JNK activation. Overall, our data suggest that the p21 hyperexpression in U266 cells blocks the lethal signaling that is induced by H(2)O(2), but not by Fas. The mechanism whereby U266 cells resist Fas-mediated cell death is discussed.

Cell Death↗
PubMed2001

Early visual changes in reflected light on non-stained brain sections after focal ischemia mirror the area of ischemic damage.

There is no reliable, simple method for delineation of ischemic regions at early time points after ischemia. We propose that at early times after stroke, ischemic regions can be visualized as a subtle change in reflected light directly in thaw-mounted, dried 20 microm brain sections. In 15 male Sprague-Dawley rats, anesthetized with isoflurane, middle cerebral artery transection and permanent bilateral common carotid artery occlusion was performed and brains were processed in five different ways. Areas of reflective change (RC) on non-stained sections were compared with areas on the adjacent sections delineated by microtubule associated protein 2 (MAP2) antibody, a reliable marker for early post-stroke, in five rats each at 1, 3, and 6 h after focal cerebral ischemia. A statistically significant correlation between ischemic areas (IA) measured on non-stained brain sections (IA(RC)) and adjacent sections immunostained (IM) with MAP2 Ab (IA(IM)) (IA(RC)=0.05+0.88.IA(IM); R2=0.8; n=15; P<0.01) and a small mean difference +/-2 S.D. (-0.9+/-6.0%) indicated that the area measured on non-stained sections reflects the IA measured on MAP2 -IM sections. At 1 and 3 h after ischemia, the ratio between ischemic regions measured on the non-stained sections and on the adjacent sections immunostained with MAP2 Ab were not different from 100% (97.6+/-1.7%, 100.9+/-6.0%). At 6 h post-stroke, the IA measured on the non-stained sections was larger than on the IM sections (109.8+/-2.7%, P<0.01, compared to 100% ratio). Our study demonstrated that this quick and simple method for detection of damaged brain permitted the use of brain tissue for other assays and could be very useful for neuroprotective evaluation and for directed micro-sampling of brain tissue at early times after ischemia.

Animals↗