Myeong Kyu Kim

Bio: Myeong Kyu Kim is an academic researcher from Chonnam National University. The author has contributed to research in topics: Epilepsy & Single-nucleotide polymorphism. The author has an hindex of 13, co-authored 47 publications receiving 1591 citations.

High cleavage efficiency of a 2A peptide derived from porcine teschovirus-1 in human cell lines, zebrafish and mice.

Abstract: When expression of more than one gene is required in cells, bicistronic or multicistronic expression vectors have been used. Among various strategies employed to construct bicistronic or multicistronic vectors, an internal ribosomal entry site (IRES) has been widely used. Due to the large size and difference in expression levels between genes before and after IRES, however, a new strategy was required to replace IRES. A self-cleaving 2A peptide could be a good candidate to replace IRES because of its small size and high cleavage efficiency between genes upstream and downstream of the 2A peptide. Despite the advantages of the 2A peptides, its use is not widespread because (i) there are no publicly available cloning vectors harboring a 2A peptide gene and (ii) comprehensive comparison of cleavage efficiency among various 2A peptides reported to date has not been performed in different contexts. Here, we generated four expression plasmids each harboring different 2A peptides derived from the foot-and-mouth disease virus, equine rhinitis A virus, Thosea asigna virus and porcine teschovirus-1, respectively, and evaluated their cleavage efficiency in three commonly used human cell lines, zebrafish embryos and adult mice. Western blotting and confocal microscopic analyses revealed that among the four 2As, the one derived from porcine teschovirus-1 (P2A) has the highest cleavage efficiency in all the contexts examined. We anticipate that the 2A-harboring cloning vectors we generated and the highest efficiency of the P2A peptide we demonstrated would help biomedical researchers easily adopt the 2A technology when bicistronic or multicistronic expression is required.

Single nucleotide polymorphisms in the multidrug resistance 1 gene in Korean epileptics.

Abstract: Summary Purpose P-glycoprotein 170 encoded by the multidrug resistance 1 ( MDR1 ) gene exports various antiepileptic drugs out of the CNS, which leads to multidrug resistance. This study was performed to elucidate the relationship between single nucleotide polymorphisms (SNPs) in the MDR1 gene and drug resistance in Koreans with epilepsy. Subjects and methods Three SNPs at nucleotide position 1236 in exon 12, 2677 in exon 21 and 3435 in exon 26 of the MDR1 gene were genotyped in 207 Korean epileptics. Subjects were classified according to whether they had drug-resistant (RS group; N =99) or drug-responsive epilepsy (RP group; N =108). The frequencies of genotype and haplotype were compared between the RS and RP groups. Results The frequencies of genotype and haplotype in the RS group were not statistically different from those in the RP group. Conclusions In Korean epileptics, there was no significant relationship between three known SNPs in MDR1 and drug resistance. And there was no association of MDR1 haplotype based on above three sites with pharmacoresistance.

5-fluorouracil-induced leukoencephalopathy in patients with breast cancer.

Abstract: The purpose of this study is to determine the characteristic clinical features, radiologic findings, and precipitating and prognostic factors in the patients with breast cancer and with 5-Fluorouracil (5-FU)-induced leukoencephalopathy. We reviewed the medical records of six breast cancer patients who developed leukoencephalopathy after chemotherapy which included 5-FU and also evaluated thorough neurological examinations including mini-mental status examination, cerebrospinal fluid studies, brain images and brain biopsies. Six patients exhibited slowly progressing neurologic symptoms characterized by the impairment of cognitive function, abulia, ataxic gait, and/or akinetic mutism. None of the patients had any specific causes or etiologic factors for leukoencephalopathy. Brain MRI in all patients showed diffuse periventricular white matter changes in the T2-weighted MR image. Brain biopsy in Patient 1 showed fragmented axonal fiber and minimally deprived myelination with many scattered macrophages. Five patients who treated with steroids at the onset of neurological symptoms showed clinical improvement, regardless of their age, sex, the pathology and stage of breast cancer, or the total dosage of chemotherapeutic agents. We conclude that leukoencephalopathy in these cases could be attributable to 5-FU neurotoxicity and suggest that the administration of steroids might be the treatment of choice.

Multi-center study on migraine and seizure-related headache in patients with epilepsy

Abstract: Purpose The purpose of this study is to investigate the frequency and characteristics of migraine and seizure-related headache (SRH) according to the criteria of the International Headache Society. Materials and Methods A questionnaire was undertaken at the initial evaluation of newly referred patients from 32 epilepsy clinics. Results Of a total of 597 patients, 74 (12.4%) patients had migraine. Age at the onset of epilepsy was lower in patients with migraine than in those without. Twenty-six (4.4%), nine (1.5%), and 146 (24.5%) patients experienced prodromal, ictal, and postictal SRH, respectively (n = 169, 28.3%). A pain intensity of prodromal and postictal SRH was 6.1 ± 1.5 (SD) and 6.3 ± 1.9 (SD) on the visual analogue scale, and their duration was 12.6 ± 26.7 (SD) hours and 9.0 ± 17.4 (SD) hours, respectively. Age at the onset of epilepsy was lower in patients with SRH than in those without, and the risk of occurrence of SRH was significantly greater in patients with longer epilepsy duration. SRH could be classified as a type of migraine in 46.2% of patients with prodromal SRH and in 36.3% of patients with postictal SRH. Prodromal SRH occurred more frequently and was more likely to be a migraine-type in patients with migraine compared with those without. Postictal SRH occurred more frequently and was more likely to be a migraine-type in patients with migraine. Conclusion This study suggests that SRH is a frequent accompanying symptom of epileptic seizures causing major impairment in daily life, and migraine is an important comorbidity of epilepsy, affecting the incidence and characteristics of SRH.

[Guillain-Barré syndrome].

Abstract: L'incidence annuelle du syndrome de Guillain-Barre est de 1,5/100000 habitants La mortalite actuelle est estimee a environ 5 % d'apres des essais therapeutiques recents, bien conduits Dix pour cent des malades gardent des sequelles motrices tres invalidantes un an apres le debut des premiers signes neurologiques La prise en charge de ces malades necessite des equipes entrainees, multidisciplinaires, pouvant pratiquer l'ensemble des therapeutiques specifiques La corticotherapie per os'ou par voie intraveineuse est inefficace Les echanges plasmatiques sont le premier traitement dont l'efficacite a ete demontree par rapport a un groupe controle Les indications sont maintenant mieux connues Les formes benignes (marche possible) beneficient de 2 echanges plasmatiques; 2 echanges supplementaires sont realises en cas d'aggravation Dans les formes intermediaires (marche impossible) et les formes severes (recours a la ventilation mecanique), 4 echanges plasmatiques sont conseilles Il n'est pas utile d'augmenter leur nombre dans les formes severes ou en cas d'absence d'amelioration De fortes doses d'immunoglobulines donnees par voie intraveineuse (lq IV) [0,4 g/kg/j pendant 5 jours] sont aussi efficaces que les echanges plasmatiques dans les formes intermediaires et severes Dans ces formes, le choix entre Ig IV et echanges plasmatiques depend des contre-indications respectives de ces traitements et de leur faisabilite Les travaux en cours ont comme objectif de mieux preciser les indications respectives des echanges plasmatiques et des lq IV dans des formes de gravite differente, leur morbidite comparee, la dose optimale des lq IV

mScarlet: a bright monomeric red fluorescent protein for cellular imaging

Abstract: We report the engineering of mScarlet, a truly monomeric red fluorescent protein with record brightness, quantum yield (70%) and fluorescence lifetime (3.9 ns). We developed mScarlet starting with a consensus synthetic template and using improved spectroscopic screening techniques; mScarlet's crystal structure reveals a planar and rigidified chromophore. mScarlet outperforms existing red fluorescent proteins as a fusion tag, and it is especially useful as a Forster resonance energy transfer (FRET) acceptor in ratiometric imaging.

High-throughput screening of a CRISPR/Cas9 library for functional genomics in human cells

Abstract: Targeted genome editing technologies are powerful tools for studying biology and disease, and have a broad range of research applications. In contrast to the rapid development of toolkits to manipulate individual genes, large-scale screening methods based on the complete loss of gene expression are only now beginning to be developed. Here we report the development of a focused CRISPR/Cas-based (clustered regularly interspaced short palindromic repeats/CRISPR-associated) lentiviral library in human cells and a method of gene identification based on functional screening and high-throughput sequencing analysis. Using knockout library screens, we successfully identified the host genes essential for the intoxication of cells by anthrax and diphtheria toxins, which were confirmed by functional validation. The broad application of this powerful genetic screening strategy will not only facilitate the rapid identification of genes important for bacterial toxicity but will also enable the discovery of genes that participate in other biological processes.

The cognitive sequelae of standard-dose adjuvant chemotherapy in women with breast carcinoma: Results of a prospective, randomized, longitudinal trial

Abstract: BACKGROUND Retrospective trials have reported that chemotherapy-induced cognitive dysfunction was experienced by a subset of patients with breast carcinoma. However, recent evidence indicated that a subset also exhibited impaired cognitive function at baseline, before the start of chemotherapy. A prospective, longitudinal trial that incorporates baseline neuropsychologic evaluations is necessary to determine to what extent cognitive dysfunction is attributable to chemotherapy in this population. METHODS Eighteen women with breast carcinoma underwent a comprehensive neuropsychologic evaluation before treatment and at short-term and long-term intervals after chemotherapy. The incidence, nature, severity, and chronicity of cognitive dysfunction developing in patients with breast carcinoma treated with a standard dose of adjuvant chemotherapy were assessed. RESULTS Before the start of systemic therapy, 33% of women in the current cohort exhibited cognitive impairment. At the short-term postchemotherapy time point, 61% of the cohort exhibited a decline relative to baseline in 1 or more domains of cognitive functioning and reported greater difficulty in maintaining their ability to work. The most common domains of cognitive dysfunction were related to attention, learning, and processing speed. At the long-term postchemotherapy time point, approximately 50% of patients who experienced declines in cognitive function demonstrated improvement, whereas 50% remained stable. Self-reported ability to perform work-related activities also improved over this interval. Neither impairment at baseline nor subsequent treatment-related cognitive decline exhibited any statistically significant correlation with affective well-being or with demographic or clinical characteristics. CONCLUSIONS The current study is the first longitudinal trial to report evidence of an association between cognitive dysfunction and chemotherapy in a subgroup of women with nonmetastatic breast carcinoma. The importance of using prospective research designs, appropriate cognitive measures, and statistical methods to evaluate subgroup effects was discussed. Identification of mechanisms associated with cognitive dysfunction and of risk factors contributing to subgroup vulnerability is necessary. Cancer 2004. © 2004 by the American Cancer Society.