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Search Results: 1 - 10 of 653 matches for " Hyeonsook Cheong "
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Isolation and Purification of a Novel Deca-Antifungal Peptide from Potato (Solanum tuberosum L. cv. Jopung) Against Candida albicans
Jong-Kook Lee,Ramamourthy Gopal,Chang Ho Seo,Hyeonsook Cheong,Yoonkyung Park
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13044021
Abstract: In a previous study, an antifungal protein, AFP-J, was purified from tubers of the potato ( Solanum tuberosum cv. L Jopung) and by gel filtration and HPLC. In this study, the functional peptide was characterized by partial acid digestion using HCl and HPLC. We obtained three peaks from the AFP-J, the first and third peaks were not active in the tested fungal strain. However, the second peak, which was named Potide-J, was active (MIC; 6.25 μg/mL) against Candida albicans. The amino acid sequences were analyzed by automated Edman degradation, and the amino acid sequence of Potide-J was determined to be Ala-Val-Cys-Glu-Asn-Asp-Leu-Asn-Cys-Cys. Mass spectrometry showed that its molecular mass was 1083.1 Da. Finally, we confirmed that a disulfide bond was present between Cys 3 and Cys 9 or Cys 10. Using this structure, Potide-J was synthesized via solid-phase methods. In these experiments, only the linear sequence was shown to display strong activity against Candida albicans. These results suggest that Potide-J may be an excellent candidate compound for the development of commercially applicable antibiotic agents.
PG-2, a Potent AMP against Pathogenic Microbial Strains, from Potato (Solanum tuberosum L cv. Gogu Valley) Tubers Not Cytotoxic against Human Cells
Jin-Young Kim,Ramamourthy Gopal,Sang Young Kim,Chang Ho Seo,Hyang Burm Lee,Hyeonsook Cheong,Yoonkyung Park
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14024349
Abstract: In an earlier study, we isolated potamin-1 (PT-1), a 5.6-kDa trypsin-chymotrypsin protease inhibitor, from the tubers of a potato strain ( Solanum tuberosum L cv. Gogu Valley). We established that PT-1 strongly inhibits pathogenic microbial strains, but not human bacterial strains, and that its sequence shows 62% homology with a serine protease inhibitor. In the present study, we isolated an antifungal and antibacterial peptide with no cytotoxicity from tubers of the same potato strain. The peptide (peptide-G2, PG-2) was isolated using salt-extraction, ultrafiltration and reverse-phase high performance liquid chromatography (RP-HPLC). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) showed the protein to have a molecular mass of 3228.5 Da, while automated Edman degradation showed the N-terminal sequence of PG-2 to be LVKDNPLDISPKQVQALCTDLVIRCMCCC-. PG-2 exhibited antimicrobial activity against Candida albicans, a human pathogenic yeast strain, and Clavibacter michiganensis subsp. michiganensis, a plant late blight strain. PG-2 also showed antibacterial activity against Staphylococcus aureus, but did not lyse human red blood cells and was thermostable. Overall, these results suggest PG-2 may be a good candidate to serve as a natural antimicrobial agent, agricultural pesticide and/or food additive.
Protease Inhibitors from Plants with Antimicrobial Activity
Jin-Young Kim,Seong-Cheol Park,Indeok Hwang,Hyeonsook Cheong,Jae-Woon Nah,Kyung-Soo Hahm,Yoonkyung Park
International Journal of Molecular Sciences , 2009, DOI: 10.3390/ijms10062860
Abstract: Antimicrobial proteins (peptides) are known to play important roles in the innate host defense mechanisms of most living organisms, including plants, insects, amphibians and mammals. They are also known to possess potent antibiotic activity against bacteria, fungi, and even certain viruses. Recently, the rapid emergence of microbial pathogens that are resistant to currently available antibiotics has triggered considerable interest in the isolation and investigation of the mode of action of antimicrobial proteins (peptides). Plants produce a variety of proteins (peptides) that are involved in the defense against pathogens and invading organisms, including ribosome-inactivating proteins, lectins, protease inhibitors and antifungal peptides (proteins). Specially, the protease inhibitors can inhibit aspartic, serine and cysteine proteinases. Increased levels of trypsin and chymotrypsin inhibitors correlated with the plants resistance to the pathogen. Usually, the purification of antimicrobial proteins (peptides) with protease inhibitor activity was accomplished by salt-extraction, ultrafiltration and C18 reverse phase chromatography, successfully. We discuss the relation between antimicrobial and anti-protease activity in this review. Protease inhibitors from plants potently inhibited the growth of a variety of pathogenic bacterial and fungal strains and are therefore excellent candidates for use as the lead compounds for the development of novel antimicrobial agents.
Quantum Cohomology Rings of Lagrangian and Orthogonal Grassmannians and Total Positivity
Daewoong Cheong
Mathematics , 2006,
Abstract: We verify in an elementary way a result of Peterson for the maximal orthogonal and Lagrangian Grassmannians, and then find Vafa-Intriligator type formulas which compute their 3-point, genus zero Gromov-Witten invariants. Finally we study total positivity of the related Peterson varieties and show that Rietsch's conjecture about the total positivity holds for these cases.
Self-perceived competence correlates poorly with objectively measured competence in Evidence Based Medicine among medical students
Nai Lai, Cheong Teng
BMC Medical Education , 2011, DOI: 10.1186/1472-6920-11-25
Abstract: We recruited a group of medical students in their final six months of training between March and August 2006. The students were receiving a clinically-integrated EBM training program within their curriculum. We evaluated the students' self-perceived competence in two EBM domains ("searching for evidence" and "appraising the evidence") by piloting a questionnaire containing 16 relevant items, and objectively assessed their competence in EBM using an adapted version of the Fresno test, a validated tool. We correlated the matching components between our questionnaire and the Fresno test using Pearson's product-moment correlation.Forty-five out of 72 students in the cohort (62.5%) participated by completing the questionnaire and the adapted Fresno test concurrently. In general, our students perceived themselves as moderately competent in most items of the questionnaire. They rated themselves on average 6.34 out of 10 (63.4%) in "searching" and 44.41 out of 57 (77.9%) in "appraising". They scored on average 26.15 out of 60 (43.6%) in the "searching" domain and 57.02 out of 116 (49.2%) in the "appraising" domain in the Fresno test. The correlations between the students' self-rating and their performance in the Fresno test were poor in both the "searching" domain (r = 0.13, p = 0.4) and the "appraising" domain (r = 0.24, p = 0.1).This study provides supporting evidence that at the undergraduate level, self-perceived competence in EBM, as measured using our questionnaire, does not correlate well with objectively assessed EBM competence measured using the adapted Fresno test.International Medical University, Malaysia, research ID: IMU 110/06Evidence Based Medicine (EBM) has been incorporated into the curricula of many medical schools over the past two decades. Teaching learning activities and assessments in EBM are mainly based on the clearly defined domains of asking answerable clinical questions, searching for evidence, appraising the evidence and applying the evidence [1]
Using an Ishikawa diagram as a tool to assist memory and retrieval of relevant medical cases from the medical literature
Kam Cheong Wong
Journal of Medical Case Reports , 2011, DOI: 10.1186/1752-1947-5-120
Abstract: In this report, an Ishikawa diagram is used to demonstrate how to relate potential causes of a major presenting problem in a clinical setting. This tool can be used by teams in problem-based learning or in self-directed learning settings.An Ishikawa diagram annotated with references to relevant medical cases and literature can be continually updated and can assist memory and retrieval of relevant medical cases and literature. It could also be used to cultivate a lifelong learning habit in medical professionals.Doctors are accustomed to learning from their more experienced peers as well as from their own experiences in treating their patients [1]. Because of this, it is important that they develop learning techniques that are proactive and encourage a lifelong learning orientation. Case reports can provide valuable sources of information for others to learn from. Studying medical cases is an effective way to enhance clinical reasoning skills and reinforce clinical knowledge [2]. A case report provides important and detailed information about a patient that is often lost in larger studies [3]. Reading case reports is also intellectually stimulating. When clinicians or medical students analyze a clinical problem, they usually start with potential common causes. For example, if a patient presents with secondary amenorrhea, a clinician will consider common causes such as pregnancy and use of contraceptive medications before exploring other less common but critical causes such as hyperprolactinemia, ovarian cancer and so on.When clinicians are faced with a puzzling clinical problem, they may search journals that publish clinical cases for information about the condition [4]. There are various sources for medical cases such as the Journal of Medical Case Reports, BMJ Case Reports and the New England Journal of Medicine. However, because of the diversity of the case reports, it may be difficult to recall and organize the located material in a systematic manner in order to e
On moduli of k-convexity
Teck-Cheong Lim
Abstract and Applied Analysis , 1999, DOI: 10.1155/s1085337599000202
Abstract:
Community Adaptation to the Hebei-Spirit Oil Spill
So-Min Cheong
Ecology and Society , 2012, DOI: 10.5751/es-05079-170326
Abstract: The focus of the research is the significance of dependence for communities to survive and adapt in times of environmental disasters. It shifts the emphasis on self-reliant communities for survival and examines the types and effects of dependence and external linkages by analyzing the range of community responses that include initial responses, early social impact, compensation, and conflicts after the Hebei-Spirit oil spill in December 2007 in Korea. The findings reveal that dependence is necessary, and the effects of dependence can be both positive and negative depending on the relations between external entities and affected communities as well as the community capacity to absorb resources and information.
Taste Profiles That Correlate with Soy Consumption in Developing Countries
Brian Wansink,JaeHak Cheong
Pakistan Journal of Nutrition , 2002,
Abstract: While insufficient protein consumption is a concern to many demographic segments in developed countries, it is a greater concern in developing nations where the cost or availability of traditional forms of animal protein results in protein deficiencies. Soy is a low-cost, highly available protein source, yet it is largely overlooked because of its unfamiliar taste and texture. To determine how to best encourage soy consumption, a convenience sample of 132 Indians and Pakistanis living in the United States was examined for insights in to what characterizes someone who regularly eats soy for taste-related reasons. Three groups of consumers were analyzed, people who ate soy primarily for taste-related reasons, those who ate it primarily for health-related reasons, and those who did not eat it. People who ate soy primarily for taste-related reasons were found to be more likely to appreciate fine food, to live with a great cook, and to be more of an opinion leader than did those in either of the other two groups. These along with additional findings have implications for targeting soy-predisposed consumers, who will adopt soy for the long-term, and who can influence others because of their role as opinion-leaders within their peer or reference group.
A greedy double swap heuristic for nurse scheduling
Murphy Choy,Michelle Cheong
Management Science Letters , 2012,
Abstract: One of the key challenges of nurse scheduling problem (NSP) is the number of constraints placed on preparing the timetable, both from the regulatory requirements as well as the patients’ demand for the appropriate nursing care specialists. In addition, the preferences of the nursing staffs related to their work schedules add another dimension of complexity. Most solutions proposed for solving nurse scheduling involve the use of mathematical programming and generally considers only the hard constraints. However, the psychological needs of the nurses are ignored and this resulted in subsequent interventions by the nursing staffs to remedy any deficiency and often results in last minute changes to the schedule. In this paper, we present a staff preference optimization framework solved with a greedy double swap heuristic. The heuristic yields good performance in speed at solving the problem. The heuristic is simple and we will demonstrate its performance by implementing it on open source spreadsheet software.
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