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Biomedical subjects

Y-C Kim

Publications and source records attributed to Y-C Kim.

10 recordsLinked to original sources
PubMed2007

Enhanced degradation and toxicity reduction of dihexyl phthalate by Fusarium oxysporum f. sp. pisi cutinase.

AIMS: This research aims to investigate the efficiency of two lipolytic enzymes--fungal cutinase and yeast esterase--upon the biodegradation of dihexyl phthalate (DHP). METHOD AND RESULTS: During the enzymatic degradation of DHP dissolved in methanol, several degradation products were detected and their time-course changes were monitored using GC/MS. The DHP-degradation rate of cutinase was surprisingly high; i.e. almost 70% of the initial DHP (500 mg l(-1)) was decomposed within 4.5 h. Although the same amount of esterase was employed, more than 85% of the DHP remained after 3 days. Almost all the DHP was converted by cutinase into 1,3-isobenzofurandione (IBF), whereas hexyl methyl phthalate and IBF were abundantly produced by esterase. In addition, the toxicities of the DHP-degraded products by esterase were evaluated using various recombinant bioluminescent bacteria, which caused oxidative and protein damage, whereas the hydrolysis products from cutinase never caused any cellular damage in the methanol-containing reaction system. CONCLUSIONS: Cutinase starts to act as a DHP-degrader much earlier and faster than esterase, with high stability in ester-hydrolytic activity, therefore a plausible approach to the practical application of cutinase for DHP degradation in the DHP-contaminated environments may be possible. SIGNIFICANCE AND IMPACT OF THE STUDY: This study describes the enhanced degradation and detoxification of DHP using Fusarium oxysporum f. sp. pisi cutinase.

Biodegradation, Environmental↗
PubMed2007

Classical reward conditioning in Drosophila melanogaster.

Negatively reinforced olfactory conditioning has been widely employed to identify learning and memory genes, signal transduction pathways and neural circuitry in Drosophila. To delineate the molecular and cellular processes underlying reward-mediated learning and memory, we developed a novel assay system for positively reinforced olfactory conditioning. In this assay, flies were involuntarily exposed to the appetitive unconditioned stimulus sucrose along with a conditioned stimulus odour during training and their preference for the odour previously associated with sucrose was measured to assess learning and memory capacities. After one training session, wild-type Canton S flies displayed reliable performance, which was enhanced after two training cycles with 1-min or 15-min inter-training intervals. Higher performance scores were also obtained with increasing sucrose concentration. Memory in Canton S flies decayed slowly when measured at 30 min, 1 h and 3 h after training; whereas, it had declined significantly at 6 h and 12 h post-training. When learning mutant t beta h flies, which are deficient in octopamine, were challenged, they exhibited poor performance, validating the utility of this assay. As the Drosophila model offers vast genetic and transgenic resources, the new appetitive conditioning described here provides a useful tool with which to elucidate the molecular and cellular underpinnings of reward learning and memory. Similar to negatively reinforced conditioning, this reward conditioning represents classical olfactory conditioning. Thus, comparative analyses of learning and memory mutants in two assays may help identify the molecular and cellular components that are specific to the unconditioned stimulus information used in conditioning.

Animals↗
PubMed2006

Loss of interleukin-2-dependency in HTLV-I-infected T cells on gene silencing of thioredoxin-binding protein-2.

The transition from interleukin-2 (IL-2)-dependent to IL-2-independent growth is considered one of the key steps in the transformation of human T-cell leukemia virus type-I (HTLV-I)-infected T cells. The expression of thioredoxin-binding protein-2 (TBP-2) is lost during the transition of HTLV-I-infected T-cell lines. Here, we analysed the mechanism of loss of TBP-2 expression and the role of TBP-2 in IL-2-dependent growth in the in vitro model to investigate multistep transformation of HTLV-I. CpGs in the TBP-2 gene are methylated in IL-2-independent but not in IL-2-dependent cells. Sequential treatment with 5-aza-2'-deoxycytidine and a histone deacetylase inhibitor augmented histone acetylation and TBP-2 expression, suggesting that loss of TBP-2 expression is due to DNA methylation and histone deacetylation. In IL-2-dependent cells, a basal level of TBP-2 expression was maintained by IL-2 associated with cellular growth, whereas TBP-2 expression was upregulated on deprivation of IL-2 associated with growth suppression. Overexpression of TBP-2 in IL-2-independent cells suppressed the growth and partially restored responsiveness to IL-2. Knockdown of TBP-2 caused the IL-2-dependent cells to show partial growth without IL-2. These results suggested that epigenetic silencing of the TBP-2 gene results in a loss of responsiveness to IL-2, contributing to uncontrolled IL-2-independent growth in HTLV-I-infected T-cell lines.

Acetylation↗
PubMed2006

C-arm-guided pudendal nerve block: a new technique.

Pudendal nerve block (PNB) is an effective diagnostic and/or treatment method for perineal pain. Various approach techniques, such as transperineal, transvaginal, computerised tomography (CT)- or sono-guided approach, have been suggested for this block. However, they have some limitations, such as high cost, difficulty to perform in practice, inaccurate and unreliable results and inconvenience. To overcome these limitations, we first tried C-arm-guided approach for accomplishing PNB in the prone position. Under the optimal ischial spine view of C-arm fluoroscopy, the block needle was placed on the tip of the ischial spine. Then a mixed solution for the block was administered. All of the 25 patients enrolled in this study were blocked successfully using this method. No side-effects or complications were observed in relation to the block. We concluded that the C-arm-guided approach for PNB is an effective alternative to the existing techniques, which can overcome their limitations.

Adult↗
PubMed2003

Microvenular hemangioma.

Microvenular hemangioma is a rare, slowly growing, benign vascular tumor. It usually presents as a solitary, asymptomatic, purple to red papule or plaque in young to middle-aged adults. Histologically, the tumor is composed of irregular, branching venules with inconspicuous lumina with a lack of endothelial atypia. We describe a case of microvenular hemangioma in a 40-year-old female. The lesion was slightly tender unlike that of previously reported cases. In the context of the histological similarity to a low-grade malignant tumor, Kaposi's sarcoma, the awareness of microvenular hemangioma, a benign vascular tumor, is important.

Adult↗
PubMed2002

The effect of introducer gauge, design and bevel direction on the deflection of spinal needles.

This study was performed to determine how the use of an introducer affects the extent to which a needle deflects during a spinal or combined spinal-epidural injection. A polystyrene block was used to simulate the paraspinal area of the back. A line was drawn perpendicular to the edge of the block to use as a guide and to measure the deflection. The use of an introducer needle decreased the deflection in all the bevelled needles (p < 0.001). Depending on the direction of both the bevels, the deflection decreased as the introducer bevel was changed from the same direction, to right-angles to bevel direction and then to a direction opposite to that of the spinal needle (p < 0.05). Deflection was decreased when a thick introducer was used (p < 0.001). The use of an introducer increased the deflection of the pencil-point needle only in the deflection direction of the introducer (p < 0.001). The 18-gauge Tuohy needle with a "backhole" deflected more than the corresponding needle without a backhole (p < 0.001), and the spinal needle inserted through the Tuohy needle with a backhole deflected more (p = 0.002). Besides the tip type and gauge, the deflection of a spinal needle depends upon the use of introducer, its gauge and bevel direction. The deflection of a Tuohy needle depends upon its design, gauge and the presence of a backhole.

Anesthesia, Epidural↗
PubMed2002

Keratitis, ichthyosis and deafness syndrome with development of multiple hair follicle tumours.

We report multiple occurrences of various kinds of tumours that originate from hair follicles in a patient diagnosed with KID (keratitis, ichthyosis, deafness) syndrome. These tumours are diagnosed as: (i) trichilemmal cysts in early lesions; (ii) proliferating trichilemmal tumours in moderate duration lesions; and (iii) malignant proliferating trichilemmal tumours in advanced lesions that are thought to progress from benign trichilemmal lesions. This three-step process raises the hypothesis of a multihit model that could account for the frequent development of tumours in KID patients.

Adult↗