13 results on '"Leong, Cheryl"'
Search Results
2. Antifungal susceptibility testing of dermatophytes: Development and evaluation of an optimised broth microdilution method.
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Curatolo, Riccardo, Juricevic, Nada, Leong, Cheryl, and Bosshard, Philipp P.
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ANTIFUNGAL agents ,DERMATOPHYTES ,RINGWORM ,TERBINAFINE ,CLINICAL drug trials ,VACCINATION - Abstract
Background: Dermatophytosis is one of the most common infections affecting 3%–17% of the population. Resistance to antifungals so far was not of concern in the therapeutic management. However, recent reports of terbinafine‐resistant strains in several countries are worrisome making antifungal susceptibility testing inevitable. Objectives: We aimed to develop and evaluate an optimised broth microdilution assay for antifungal drug susceptibility testing of dermatophytes. Methods: We first studied the effect of different inocula, incubation temperatures and incubation times to establish an optimised assay. Subsequently, we tested 79 clinical strains of 11 dermatophyte species with 13 antifungals. Results: We found inoculating with 0.5–5 × 104 colony forming units (CFU) and incubating at 29°C ± 1°C for 4 days to be appropriate. Terbinafine was the most active antifungal agent with minimum inhibitory concentration (MIC) values ≤ 0.06 µg/mL, expect for one resistant T mentagrophytes strain, which was isolated from an Indian patient. Also, a majority of MICs of other antifungals that are commonly used to treat dermatophytosis were low, except those of fluconazole. Fluconazole MICs do not correlate with the good efficacy in the clinical management. Conclusions: Our assay enables fast and reliable susceptibility testing of dermatophytes with a large panel of different antifungals. This helps to improve the therapeutic management of dermatophytosis by detecting resistant strains. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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3. Effect of zinc pyrithione shampoo treatment on skin commensal Malassezia.
- Author
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Leong, Cheryl, Wang, Joyce, Toi, Min Jet, Lam, Yuen In, Goh, Joleen PZ, Lee, Shi Mun, and Dawson, Thomas L
- Abstract
Malassezia restricta and Malassezia globosa are lipid dependent commensal yeasts associated with dandruff. Antifungal actives such as zinc pyrithione are commonly used in antidandruff shampoos, although their efficacy is not clearly demonstrated. In this study, we assessed the efficacy of antifungal treatments on scalp Malassezia via a combination of culturomic and genomic detection methods. Zinc pyrithione inhibited Malassezia growth at low minimum inhibitory concentrations (MICs). In a longitudinal pilot study, quantitative polymerase chain reaction (qPCR) analysis showed a decrease in M. restricta on the scalp after zinc pyrithione treatment. These findings validate the antifungal efficacy of zinc pyrithione as a dandruff treatment. Lay Abstract Malassezia yeasts are associated with dandruff and seborrheic dermatitis. Zinc pyrithione is effective against Malassezia growth in vitro and when tested on human skin as a shampoo. These findings will be useful for investigating the role of Malassezia in skin microbiome intervention studies. [ABSTRACT FROM AUTHOR]
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- 2021
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4. Geographical and Ethnic Differences Influence Culturable Commensal Yeast Diversity on Healthy Skin.
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Leong, Cheryl, Schmid, Bettina, Toi, Min Jet, Wang, Joyce, Irudayaswamy, Antony Sagayaraj, Goh, Joleen Peh Zhen, Bosshard, Philipp P., Glatz, Martin, and Dawson, Thomas L.
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ETHNIC differences ,CANDIDA ,MALASSEZIA ,CAUCASIAN race ,YEAST ,ETHNICITY ,SKIN ,TROPICAL climate ,MYCOSES - Abstract
Commensal fungi such as Malassezia , Candida , and Rhodotorula are common on healthy skin but are also associated with opportunistic invasive and superficial infections. Skin microbial community characterization has been extensively performed worldwide, with a focus on the 16S bacterial community. These studies have focused on geographically distinct or targeted cohorts with variable reported species distributions of commensal yeast species. To determine the effects of extrinsic environmental factors such as geography, climate, and ethnicity on detected healthy skin commensal yeast diversity, we compared cohorts from Singapore and Zürich, Switzerland, representative of two geographically and climatically distinct regions comprising multi-ethnic (Chinese, Malay, Indian, Caucasian) and predominantly white Caucasian cohorts, respectively, using identical skin sampling and culture methods. We chose to use a culture-based approach as cultures isolated from patients are still required for studies of pathogenicity and antifungal susceptibility. Detection of yeast species by culture-dependent and independent sequencing-based methods suggest healthy skin diversity reflects a species distribution representative of the geography, climate and ethnic background of their local populations. Culture success and species diversity was also found to be dependent on climate, with warm tropical climates favoring high positive culture rates and greater species diversity. Multilocus sequence typing data suggests some strains are geographically distinct and may be used to segregate potential disease-causing commensals. For accurate collection and characterization of skin microbial communities, it remains recommended to employ a combination of culture-dependent and sequence-based culture-independent methods. Characterization of healthy mycobiomes in geographically distinct local populations will be useful in defining the role of commensal fungi in health and disease. [ABSTRACT FROM AUTHOR]
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- 2019
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5. Physiological Doses of Red Light Induce IL‐4 Release in Cocultures between Human Keratinocytes and Immune Cells.
- Author
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Leong, Cheryl, Bigliardi, Paul L., Sriram, Gopu, Au, Veonice B., Connolly, John, and Bigliardi‐Qi, Mei
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KERATINOCYTES ,INTERLEUKIN-4 ,PHOTOTHERAPY ,PHOTOSENSITIZERS ,SKIN physiology ,PHYSIOLOGICAL effects of light - Abstract
Abstract: Phototherapy is routinely used for the treatment of various skin conditions and targeted therapy of superficial cancers. However, the molecular mechanisms behind their biological effects and the need for efficacy enhancing photosensitizers are not well addressed. Particularly, not much is known about the inherent effect of light from the visible spectrum on cytokine release and its downstream effects in keratinocytes and immune cells located in skin and therefore exposed to light. To address this, we delivered calibrated doses of well‐defined light qualities (380 to 660 nm) to cocultures of human keratinocytes and macrophage/dendritic cells in the absence or presence of the commonly used photosensitizer 8‐methoxypsoralen (8‐MOP). The experiments identified IL‐4 as a key effector cytokine released by this coculture model with need for 8‐MOP in the UVA
1 /blue (380 nm) and no requirement for photosensitizer in the red light spectrum (627 nm). 3D organotypic skin cultures treated with IL‐4 showed thickening of the epidermal layer and delayed differentiation. However unlike IL‐4 and UVA1 /blue light treatment, red light did not reduce the expression of keratinocyte differentiation markers or increase signs of photo‐oxidative damage. This supports the application of isolated red light as a possible alternative for photo‐immunotherapy without need for additional photosensitizers. [ABSTRACT FROM AUTHOR]- Published
- 2018
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6. Investigating endogenous µ-opioid receptors in human keratinocytes as pharmacological targets using novel fluorescent ligand.
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Leong, Cheryl, Neumann, Christine, Ramasamy, Srinivas, Rout, Bhimsen, Yi Wee, Lim, Bigliardi-Qi, Mei, and Bigliardi, Paul L.
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OPIOID peptides ,OPIOID receptors ,KERATINOCYTES ,TARGETED drug delivery ,SKIN physiology - Abstract
Opioids in skin function during stress response, regeneration, ageing and, particularly in regulating sensation. In chronic pruritus, topical treatment with Naltrexone changes μ-opioid receptor (μ-OR) localization to relieve itch. The molecular mechanisms behind the effects of Naltrexone on μ-OR function in reduction of itching behavior has not been studied. There is an immediate need to understand the endogenous complexity of μ-OR dynamics in normal and pathological skin conditions. Here we evaluate real-time behavior of μ-OR-Endomorphine complexes in the presence of agonist and antagonists. The μ-OR ligand Endomorphine-1 (EM) was conjugated to the fluorescent dye Tetramethylrhodamine (TAMRA) to investigate the effects of agonist and antagonists in N/TERT-1 keratinocytes. The cellular localization of the EM-TAMRA was followed through time resolved confocal microscopy and population analysis was performed by flow cytometry. The in vitro analyses demonstrate fast internalization and trafficking of the endogenous EM-TAMRA-μ-OR interactions in a qualitative manner. Competition with Endomorphine-1, Naltrexone and CTOP show both canonical and non-canonical effects in basal and differentiated keratinocytes. Acute and chronic treatment with Naltrexone and Endomorphine-1 increases EM-TAMRA binding to skin cells. Although Naltrexone is clinically effective in relieving itch, the mechanisms behind re-distribution of μ-ORs during clinical treatments are not known. Our study has given insight into cellular mechanisms of μ-OR ligand-receptor interactions after opioid agonist and antagonist treatments in vitro. These findings potentially offer opportunities in using novel treatment strategies for skin and peripheral sensory disorders. [ABSTRACT FROM AUTHOR]
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- 2017
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7. A Fluorescent Probe for Neural Stem/Progenitor Cells with High Differentiation Capability into Neurons.
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Kim, Beomsue, Feng, Suihan, Yun, Seong‐Wook, Leong, Cheryl, Satapathy, Rudrakanta, Wan, Si Yan Diana, and Chang, Young‐Tae
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- 2016
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8. NeuO: a Fluorescent Chemical Probe for Live Neuron Labeling.
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Er, Jun Cheng, Leong, Cheryl, Teoh, Chai Lean, Yuan, Qiang, Merchant, Paolomi, Dunn, Matthew, Sulzer, David, Sames, Dalibor, Bhinge, Akshay, Kim, Dongyoon, Kim, Seong-Min, Yoon, Myung-Han, Stanton, Lawrence W., Je, Shawn H., Yun, Seong-Wook, and Chang, Young-Tae
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NEURONS ,FLUORESCENCE ,CELLS ,BRAIN - Abstract
To address existing limitations in live neuron imaging, we have developed NeuO, a novel cell-permeable fluorescent probe with an unprecedented ability to label and image live neurons selectively over other cells in the brain. NeuO enables robust live neuron imaging and isolation in vivo and in vitro across species; its versatility and ease of use sets the basis for its development in a myriad of neuronal targeting applications. [ABSTRACT FROM AUTHOR]
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- 2015
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9. NeuO: a Fluorescent Chemical Probe for Live Neuron Labeling.
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Er, Jun Cheng, Leong, Cheryl, Teoh, Chai Lean, Yuan, Qiang, Merchant, Paolomi, Dunn, Matthew, Sulzer, David, Sames, Dalibor, Bhinge, Akshay, Kim, Dongyoon, Kim, Seong-Min, Yoon, Myung-Han, Stanton, Lawrence W., Je, Shawn H., Yun, Seong-Wook, and Chang, Young-Tae
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FLUORESCENCE spectroscopy ,MOLECULAR probes ,CENTRAL nervous system ,BRAIN damage ,PYRAMIDAL neurons - Abstract
To address existing limitations in live neuron imaging, we have developed NeuO, a novel cell-permeable fluorescent probe with an unprecedented ability to label and image live neurons selectively over other cells in the brain. NeuO enables robust live neuron imaging and isolation in vivo and in vitro across species; its versatility and ease of use sets the basis for its development in a myriad of neuronal targeting applications. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
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10. Target Identification: A Challenging Step in Forward Chemical Genetics.
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Das, Raj Kumar, Samanta, Animesh, Ghosh, Krishnakanta, Duanting Zhai, Wang Xu, Dongdong Su, Leong, Cheryl, and Young Tae Chang
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BIOCHEMICAL genetics ,MOLECULES ,PHENOTYPES ,BIOCHEMISTRY ,MOLECULAR genetics - Abstract
Investigation of the genetic functions in complex biological systems is a challenging step in recent year. Hence, several valuable and interesting research projects have been developed with novel ideas to find out the unknown functions of genes or proteins. To validate the applicability of their novel ideas, various approaches are built up. To date, the most promising and commonly used approach for discovering the target proteins from biological system using small molecule is well known a forward chemical genetics which is considered to be more convenient than the classical genetics. Although, the forward chemical genetics consists of the three basic components, the target identification is the most challenging step to chemical biology researchers. Hence, the diverse target identification methods have been developed and adopted to disclose the small molecule bound protein. Herein, in this review, we briefly described the first two parts chemical toolbox and screening, and then the target identifications in forward chemical genetics are thoroughly described along with the illustrative real example case study. In the tabular form, the different biological active small molecules which are the successful examples of target identifications are accounted in this research review. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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11. Return to work after uncomplicated myocardial infarction: a trial of practice guidelines in the community.
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Pilote, Louise, Thomas, Randal J., Dennis, Charles, Goins, Patricia, Houston-Miller, Nancy, Kraemer, Helene, Leong, Cheryl, Berger III, Walter E., Lew, Henry, Heller, Robert S., Rompf, Jonathan, DeBusk, Robert F., Pilote, L, Thomas, R J, Dennis, C, Goins, P, Houston-Miller, N, Kraemer, H, Leong, C, and Berger, W E 3rd
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PERSONNEL management ,EMPLOYEES ,MYOCARDIAL infarction - Abstract
Objective: To evaluate the effectiveness of practice guidelines for return to work after acute myocardial infarction when disseminated from a university-based setting to a practice-based setting.Design: Randomized clinical trial.Patients: A total of 187 patients with uncomplicated acute myocardial infarction.Intervention: Patients were randomly assigned to the intervention (n = 95) or to usual care (n = 92). The intervention consisted of a treadmill test, a counseling session based on the test results, and a consultation letter from a cardiologist to the primary care physician. Individualized recommendations for the timing of return to work, contained in the consultation letter, were based on the patient's risk for recurrent cardiac events.Measurements: Questionnaire, chart review, and a phone interview documented the timing of return to work and the rates of cardiac death, coronary angioplasty, coronary artery surgery, and recurrent myocardial infarction.Results: Median intervals between acute myocardial infarction and return to work were similar in both groups (intervention, 54 days; usual care, 67 days; P greater than 0.2). Among patients without myocardial ischemia, however, the interval was shorter in the intervention group than in the usual care group (38 days compared with 65 days, respectively, P = 0.008). Among patients with myocardial ischemia, intervals were similar in both groups (80 days compared with 76 days, respectively, P greater than 0.2).Conclusion: Practice guidelines developed in a university-based setting were not as successful in hastening return to work after uncomplicated acute myocardial infarction when tested in a practice-based setting. Physicians' reluctance to follow guidelines for patients with myocardial ischemia reflected their concern with prognosis even though medical outcome was good. [ABSTRACT FROM AUTHOR]- Published
- 1992
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12. Microglia specific fluorescent probes for live cell imaging.
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Leong, Cheryl, Lee, Sung Chan, Ock, Jiyeon, Li, Xin, See, Peter, Park, Sung Jin, Ginhoux, Florent, Yun, Seong-Wook, and Chang, Young-Tae
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MICROGLIA ,CELL imaging ,SMALL molecules ,IMMUNOGLOBULINS ,FLUORESCENT proteins ,NEUROLOGICAL disorders - Abstract
Small molecule fluorescent probes offer significant advantages over conventional antibody and fluorescent protein labeling techniques. Here we present CDr10a and CDr10b, dyes that label live microglia specifically. They may be applied to the isolation and imaging of live microglia when investigating their role in neuroinflammatory diseases. [ABSTRACT FROM AUTHOR]
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- 2014
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13. Cover Picture: A Fluorescent Probe for Neural Stem/Progenitor Cells with High Differentiation Capability into Neurons (ChemBioChem 22/2016).
- Author
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Kim, Beomsue, Feng, Suihan, Yun, Seong‐Wook, Leong, Cheryl, Satapathy, Rudrakanta, Wan, Si Yan Diana, and Chang, Young‐Tae
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- 2016
- Full Text
- View/download PDF
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