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Yeung EYH, Deslandes V, Cowan J. Photo Quiz: Were those hyphae or pseudohyphae in blood culture? J Clin Microbiol 2024; 62:e0082223. [PMID: 38353568 PMCID: PMC10865798 DOI: 10.1128/jcm.00822-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2024] Open
Affiliation(s)
- Eugene Y. H. Yeung
- Division of Microbiology, Department of Pathology and Laboratory Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Department of Microbiology, Eastern Ontario Regional Laboratory Association (EORLA), Ottawa, Ontario, Canada
| | - Vincent Deslandes
- Division of Microbiology, Department of Pathology and Laboratory Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Department of Microbiology, Eastern Ontario Regional Laboratory Association (EORLA), Ottawa, Ontario, Canada
- The Ottawa Hospital Research Institute (OHRI), Ottawa, Ontario, Canada
| | - Juthaporn Cowan
- The Ottawa Hospital Research Institute (OHRI), Ottawa, Ontario, Canada
- Division of Infectious Disease, Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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Yeung EYH, Deslandes V, Cowan J. Answer to the Photo Quiz: Were those hyphae or pseudohyphae in blood culture? J Clin Microbiol 2024; 62:e0082423. [PMID: 38353569 PMCID: PMC10865819 DOI: 10.1128/jcm.00824-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2024] Open
Abstract
Read the full article for the answer.
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Affiliation(s)
- Eugene Y. H. Yeung
- Division of Microbiology, Department of Pathology and Laboratory Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Department of Microbiology, Eastern Ontario Regional Laboratory Association (EORLA), Ottawa, Ontario, Canada
| | - Vincent Deslandes
- Division of Microbiology, Department of Pathology and Laboratory Medicine, University of Ottawa, Ottawa, Ontario, Canada
- Department of Microbiology, Eastern Ontario Regional Laboratory Association (EORLA), Ottawa, Ontario, Canada
- The Ottawa Hospital Research Institute (OHRI), Ottawa, Ontario, Canada
| | - Juthaporn Cowan
- The Ottawa Hospital Research Institute (OHRI), Ottawa, Ontario, Canada
- Division of Infectious Disease, Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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Yeung EYH. Obtaining the local Helicobacter pylori resistance rate is easier said than done. Can Fam Physician 2024; 70:81. [PMID: 38383011 DOI: 10.46747/cfp.700281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
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Yeung EYH. A Case Series of Diarrheal Diseases Associated with Yersinia frederiksenii. Infect Dis Rep 2021; 13:552-557. [PMID: 34199195 PMCID: PMC8293068 DOI: 10.3390/idr13020051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 06/09/2021] [Accepted: 06/11/2021] [Indexed: 11/16/2022] Open
Abstract
To date, Yersinia pestis, Yersinia enterocolitica, and Yersinia pseudotuberculosis are the three Yersinia species generally agreed to be pathogenic in humans. However, there are a limited number of studies that suggest some of the “non-pathogenic” Yersinia species may also cause infections. For instance, Yersinia frederiksenii used to be known as an atypical Y. enterocolitica strain until rhamnose biochemical testing was found to distinguish between these two species in the 1980s. From our regional microbiology laboratory records of 18 hospitals in Eastern Ontario, Canada from 1 May 2018 to 1 May 2021, we identified two patients with Y. frederiksenii isolates in their stool cultures, along with their clinical presentation and antimicrobial management. Both patients presented with diarrhea, abdominal pain, and vomiting for 5 days before presentation to hospital. One patient received a 10-day course of sulfamethoxazole-trimethoprim; his Y. frederiksenii isolate was shown to be susceptible to amoxicillin-clavulanate, ceftriaxone, ciprofloxacin, and sulfamethoxazole-trimethoprim, but resistant to ampicillin. The other patient was sent home from the emergency department and did not require antimicrobials and additional medical attention. This case series illustrated that diarrheal disease could be associated with Y. frederiksenii; the need for antimicrobial treatment should be determined on a case-by-case basis.
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Affiliation(s)
- Eugene Y H Yeung
- Department of Medical Microbiology, The Ottawa Hospital General Campus, The University of Ottawa, Ottawa, ON K1H 8L6, Canada
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Yeung EYH. Granulicatella Infection of the Central Nervous System in a 3-Year-Old Girl. Can J Hosp Pharm 2021; 74:159-162. [PMID: 33896957 PMCID: PMC8042192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Affiliation(s)
- Eugene Y H Yeung
- , MD, MSc, ACPR, BSc(Pharm), is with the Faculty of Medicine, University of Ottawa, and the Eastern Ontario Regional Laboratory Association, Ottawa, Ontario
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Yeung EYH. A Case-Control Study on the Association between Salmonella Bacteriuria and Cystoscopy. Infect Dis Rep 2021; 13:205-214. [PMID: 33804416 PMCID: PMC7930975 DOI: 10.3390/idr13010023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 02/02/2021] [Accepted: 02/08/2021] [Indexed: 11/16/2022] Open
Abstract
To date, there is only one published report of an outbreak of urinary tract infections by Salmonella species after cystoscopy. Disinfection procedures for cystoscope have come into question. The current study aimed to determine the odds of developing Salmonella bacteriuria after cystoscopy. A retrospective case-control study was conducted on all patients with Salmonella species in urine (case) and blood (control) from 2017 to 2019 in 16 hospitals in Eastern Ontario, Canada. Eight of the 11 patients had cystoscopy prior to Salmonella bacteriuria; three of the 74 patients had urological procedures prior to Salmonella bacteremia, but none of their procedures were cystoscopy. The odds ratio of urological procedures with Salmonella bacteriuria was 63.1 (95% CI 10.9 to 366.6; p < 0.0001). In the bacteriuria group, the most frequently identified isolates were Salmonella enteritidis (n = 8), followed by Salmonella oranienburg, and Salmonella heidelberg. Seven of the S. enteritidis isolates had identical susceptibilities (ampicillin-sensitive; sulfamethoxazole/trimethoprim-sensitive; ciprofloxacin intermediate). In the bacteremia group, the most frequently identified isolates were S. enteritidis (n = 22), followed by Salmonella typhi, S. heidelberg, S. oranienburg, and Salmonella typhimurium. The result suggested cystoscopy is a risk factor for Salmonella bacteriuria. Identification of Salmonella bacteriuria should prompt public health investigations of linkage between cystoscopy and Salmonella bacteriuria.
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Affiliation(s)
- Eugene Y H Yeung
- Department of Medical Microbiology, The Ottawa Hospital General Campus, The University of Ottawa, Ottawa, ON K1H 8L6, Canada
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Yeung EYH. There should only be one most responsible provider. Can Pharm J (Ott) 2020; 153:317-318. [PMID: 33282015 DOI: 10.1177/1715163520958021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Yeung EYH. I sympathise with both the supporters and naysayers of hierarchical communication rules. BMJ 2020; 370:m3495. [PMID: 32900693 DOI: 10.1136/bmj.m3495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Yeung EYH. Sexism and racism in medical care: It depends on the context. CMAJ 2020; 192:E323. [DOI: 10.1503/cmaj.74905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Yeung EYH, Mohammed RSD. Pharmacists prescribed 7 times more antibiotics than physicians did for query urinary tract infection. Can Pharm J (Ott) 2019; 152:281-282. [PMID: 31534580 DOI: 10.1177/1715163519866223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Yeung EYH. Is having broad experience a red flag in the CaRMS match? CMAJ 2019; 191:E869. [PMID: 31387960 DOI: 10.1503/cmaj.72397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Affiliation(s)
- Eugene Y H Yeung
- Resident physician, Department of Microbiology, University of Ottawa, Ottawa, Ont
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Yeung EYH. Antibiotic use: don't blame doctors for trying to manage patient expectations. BMJ 2019; 365:l1895. [PMID: 31043371 DOI: 10.1136/bmj.l1895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Yeung EYH, Mohammed RSD. Trans health needs better inpatient services too. BMJ 2018; 363:k4493. [PMID: 30381442 DOI: 10.1136/bmj.k4493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
| | - Roxanna S D Mohammed
- Ottawa Hospital General Campus, University of Ottawa, Ottawa, ON, Canada K1H 8L6
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Abstract
Physicians and pharmacists nowadays are often described as adversaries rather than members of the same team. Some pharmacists apply to medical school later in their careers, and experience obstacles during the transition process. This article details interviews with two physician–pharmacists, who each have a past pharmacist license and current physician license. The respondents described the limitations of pharmacists’ scope of practice as their main reasons to pursue a medical career. However, the respondents enjoy applying their pharmacy knowledge and experience to improve their medical practice. They do not feel pharmacy seniors and medical recruiters are supportive towards their chase for medical careers. The respondents noted the importance of peer-reviewed articles to promote pharmacist involvement in patient care and collaboration between physicians and pharmacists. Conflicts between physicians and pharmacists tend to happen because of their different focuses on patient care. The respondents do not see themselves having an edge over other medical school applicants, and noted that recruiters could negatively view their pharmacy experience. The respondents believe that physician–pharmacists are catalysts to foster collaboration between physicians and pharmacists, because they clearly understand the role of each profession. Nevertheless, the respondents feel that physicians and pharmacists are generally lukewarm towards pharmacists transitioning into physicians.
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Affiliation(s)
- Eugene Y H Yeung
- Education Centre, Royal Lancaster Infirmary, Lancaster LA1 4RP, UK.
- Department of Medical Microbiology, The Ottawa Hospital General Campus, The University of Ottawa, Ottawa, ON K1H 8L6, Canada.
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Yeung EYH. Are doctors wrong for stating the elephant in the room? BMJ 2018; 362:k3117. [PMID: 30021778 DOI: 10.1136/bmj.k3117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Yeung EYH. GPs to judge which patients deserve an NHS prescription. BMJ 2018; 360:k404. [PMID: 29419379 DOI: 10.1136/bmj.k404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Yeung EYH. Apples and oranges: comparing residency models in the UK and North America. BMJ 2018; 360:k59. [PMID: 29317449 DOI: 10.1136/bmj.k59] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Yeung EYH, Alexander M. Use of junior doctor‐led peer education to improve antibiotic stewardship. Br J Clin Pharmacol 2017; 83:2831-2832. [DOI: 10.1111/bcp.13375] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Revised: 06/29/2017] [Accepted: 07/09/2017] [Indexed: 11/29/2022] Open
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Affiliation(s)
- Eugene Y H Yeung
- Education Centre, Royal Lancaster Infirmary, University Hospitals of Morecambe Bay NHS Trust, Ashton Road, Lancaster, LA1 4RP, UK.
| | - Kurt Buhagiar
- The Orchard, Lancashire Care NHS Trust, Lancaster, LA1 4JJ, UK
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Mohammed RSD, Yeung EYH. Physical Examinations by Pharmacists: Practising the Right Thing Makes Perfect. Can J Hosp Pharm 2017; 70:468-469. [PMID: 29299008 PMCID: PMC5737191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
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Yeung EYH, Munroe J. Development of a malignant hyperthermia protocol. BMC Proc 2015. [PMCID: PMC4306034 DOI: 10.1186/1753-6561-9-s1-a32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Yeung EYH, Cavanna AE. Sleep Attacks in Patients With Parkinson's Disease on Dopaminergic Medications: A Systematic Review. Mov Disord Clin Pract 2014; 1:307-316. [PMID: 30363881 DOI: 10.1002/mdc3.12063] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 05/05/2014] [Accepted: 05/25/2014] [Indexed: 11/05/2022] Open
Abstract
Dopaminergic medications are used as first-line treatment for Parkinson's disease (PD). In 1999, a case series was published describing 9 patients who took dopamine agonists (pramipexole or ropinirole) and experienced sudden irresistible sleep attacks. Sleep attacks have subsequently been reported with other dopaminergic medications, including levodopa. Because these symptoms might not be rare and can affect health-related quality of life, we set out to review the prevalence and clinical characteristics of sleep attacks in patients with PD on dopaminergic medications. We conducted a systematic literature review using the terms parkinson* AND dopamine* AND narcolep* OR sleep attack in multiple databases (PubMed, Embase, and PsycINFO). The systematic literature review yielded 23 relevant articles, including nine case reports or case series and 14 original studies. According to the pooled data from the five studies reporting prevalence figures (n = 10,084), sleep attacks occur in 13.0% of patients with PD on dopaminergic medications. Our analysis failed to show significant differences in the Epworth Sleepiness scores between patients with and without sleep attacks (mean difference: 2.92; 95% confidence interval: -0.47-6.31). The I2 value of 76% indicated high heterogeneity among the studies. Sleep attacks are not a rare occurrence in patients with PD on dopamine agonist treatment. We found conflicting results on whether sleep attacks in PD resemble narcolepsy. The pathophysiology of these symptoms might be related to dopamine D2 and D4 receptor gene polymorphisms. The most effective management strategies were dose reduction and discontinuation of the offending drugs.
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Affiliation(s)
- Eugene Y H Yeung
- College of Medical and Dental Sciences University of Birmingham Birmingham United Kingdom
| | - Andrea E Cavanna
- College of Medical and Dental Sciences University of Birmingham Birmingham United Kingdom.,Department of Neuropsychiatry Birmingham and Solihull Mental Health NHS Foundation Trust Birmingham United Kingdom.,School of Life and Health Sciences Aston University Birmingham United Kingdom.,Sobell Department of Motor Neuroscience and Movement Disorders University College London and Institute of Neurology London United Kingdom
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Teng JLL, Yeung MY, Yue G, Au-Yeung RKH, Yeung EYH, Fung AMY, Tse H, Yuen KY, Lau SKP, Woo PCY. In silico analysis of 16S rRNA gene sequencing based methods for identification of medically important aerobic Gram-negative bacteria. J Med Microbiol 2011; 60:1281-1286. [PMID: 21498652 DOI: 10.1099/jmm.0.027805-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
This study provides guidelines on the usefulness of full and 527 bp 16S rRNA gene sequencing and Microseq databases for identifying medically important aerobic Gram-negative bacteria. Overall, full and 527 bp 16S rRNA gene sequencing can identify 26.1 % and 32.6 %, respectively, of medically important aerobic Gram-negative bacteria confidently to the species level, whereas the full-MicroSeq and 500-MicroSeq databases can identify 15.2 % and 26.1 %, respectively, of medically important aerobic Gram-negative bacteria confidently to the species level. Among the major groups of aerobic Gram-negative bacteria, the methods and databases are least useful for identification of Aeromonas, Bordetella and Bartonella species. None of the Aeromonas species can be confidently or doubtfully identified, whereas only 0 % and 0-33.3 % of Bordetella species and 0-10 % and 0-10 % of Bartonella species can be confidently and doubtfully identified, respectively. On the other hand, these methods and databases are most useful for identification of members of the families Pasteurellaceae and Legionellaceae and Campylobacter species: 29.6-59.3 % and 7.4-18.5 % of members of Pasteurellaceae, 36-52 % and 12-24 % of members of Legionellaceae, and 26.7-60 % and 0-13.3 % of Campylobacter species can be confidently and doubtfully identified, respectively. Thirty-nine medically important aerobic Gram-negative bacteria that should be confidently identified by full 16S rRNA gene sequencing are not included in the full-MicroSeq database. Twenty-three medically important aerobic Gram-negative bacteria that should be confidently identified by 527 bp 16S rRNA gene sequencing are not included in the 500-MicroSeq database. Compared with results of our previous studies on anaerobic and Gram-positive bacteria, full and 527 bp 16S rRNA gene sequencing are able to confidently identify significantly more anaerobic Gram-positive and Gram-negative bacteria than aerobic Gram-positive and Gram-negative bacteria.
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Affiliation(s)
- Jade L L Teng
- Department of Microbiology, The University of Hong Kong, Hong Kong SAR
| | - Ming-Yiu Yeung
- Department of Microbiology, The University of Hong Kong, Hong Kong SAR
| | - Geoffrey Yue
- Department of Microbiology, The University of Hong Kong, Hong Kong SAR
| | - Rex K H Au-Yeung
- Department of Microbiology, The University of Hong Kong, Hong Kong SAR
| | - Eugene Y H Yeung
- Department of Microbiology, The University of Hong Kong, Hong Kong SAR
| | - Ami M Y Fung
- Department of Microbiology, The University of Hong Kong, Hong Kong SAR
| | - Herman Tse
- Department of Microbiology, The University of Hong Kong, Hong Kong SAR.,State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong SAR.,Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong SAR.,Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong SAR
| | - Kwok-Yung Yuen
- Department of Microbiology, The University of Hong Kong, Hong Kong SAR.,State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong SAR.,Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong SAR.,Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong SAR
| | - Susanna K P Lau
- State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong SAR.,Department of Microbiology, The University of Hong Kong, Hong Kong SAR.,Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong SAR.,Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong SAR
| | - Patrick C Y Woo
- Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong SAR.,State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong SAR.,Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong SAR.,Department of Microbiology, The University of Hong Kong, Hong Kong SAR
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Abstract
Administration of melatonin to rodents decreases the incidence of tumorigenesis initiated by benzo[a]pyrene or 7,12-dimethylbenz[a]anthracene, which requires bioactivation by cytochrome P450 enzymes, such as CYP1A1, CYP1A2 and CYP1B1, to produce carcinogenic metabolites. The present study tested the hypothesis that melatonin is a modulator of human CYP1 catalytic activity and gene expression. As a comparison, we also investigated the effect of melatonin on the catalytic activity of CYP2A6, which is also a procarcinogen-bioactivating enzyme. Melatonin (3-300 microm) decreased 7-ethoxyresorufin O-dealkylation catalyzed by human hepatic microsomes and recombinant CYP1A1, CYP1A2 and CYP1B1, whereas it did not affect coumarin 7-hydroxylation catalyzed by hepatic microsomes or recombinant CYP2A6. Melatonin inhibited CYP1 enzymes by mixed inhibition, with apparent K(i) values (mean +/- S.E.M.) of 59 +/- 1 (CYP1A1), 12 +/- 1 (CYP1A2), 14 +/- 2 (CYP1B1) and 46 +/- 8 microm (hepatic microsomes). Additional experiments indicated that melatonin decreased benzo[a]pyrene hydroxylation catalyzed by hepatic microsomes and CYP1A2 but not by CYP1A1 or CYP1B1. Treatment of MCF-10A human mammary epithelial cells with melatonin (up to 300 microm) did not affect basal or benzo[a]pyrene-inducible CYP1A1 or CYP1B1 gene expression. Consistent with this finding, melatonin did not influence reporter activity in aryl hydrocarbon receptor-dependent pGudluc6.1-transfected MCF-10A cells treated with or without benzo[a]pyrene, as assessed in an in vitro cell-based luciferase reporter gene assay. Overall, melatonin is an in vitro inhibitor of human CYP1 catalytic activity, and it may be useful to develop potent analogues of melatonin as potential cancer chemopreventive agents that block CYP1-mediated chemical carcinogenesis.
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Affiliation(s)
- Thomas K H Chang
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, BC, Canada
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Abstract
Pregnane X receptor (PXR; NR1I2) is a ligand-activated transcription factor that plays a role not only in drug metabolism and transport but also in various other biological processes. Ginkgo biloba is a herbal medicine commonly used to manage memory impairment. Treatment of primary cultures of rat hepatocytes with G. biloba extract increases the mRNA expression of CYP3A23, which is a target gene for rat PXR. The present study was conducted to test the hypothesis that G. biloba extract activates PXR. Treatment of mouse PXR (mPXR) or human PXR (hPXR)-transfected HepG2 cells with G. biloba extract at 200 microg/ml increased mPXR and hPXR activation by 3.2- and 9.5-fold, respectively. Dose-response analysis showed a log-linear increase in hPXR activation by the extract over the range of 200 to 800 microg/ml. To determine whether G. biloba extract induces hPXR target gene expression, cultured LS180 human colon adenocarcinoma cells were treated for 72 h with the extract. G. biloba extract at 200, 400, and 800 microg/ml increased CYP3A4 mRNA expression by 1.7-, 2.4-, and 2.5-fold, respectively. The same concentrations of the extract increased CYP3A5 (1.3-3.6-fold) and P-glycoprotein (ABCB) 1 (2.7-6.4-fold) mRNA expression. At concentrations (5 and 10 microM) that did not down-regulate PXR gene expression and were not cytotoxic, L-sulforaphane (an hPXR antagonist) decreased CYP3A4, CYP3A5, and ABCB1 gene expression in cells treated with G. biloba extract. In summary, G. biloba extract activated mPXR and hPXR in a cell-based reporter gene assay and induced CYP3A4, CYP3A5, and ABCB1 gene expression in hPXR-expressing LS180 cells.
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Affiliation(s)
- Eugene Y H Yeung
- Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, BC, Canada V6T 1Z3
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Chang TKH, Chen J, Yeung EYH. Effect of Ginkgo biloba extract on procarcinogen-bioactivating human CYP1 enzymes: Identification of isorhamnetin, kaempferol, and quercetin as potent inhibitors of CYP1B1. Toxicol Appl Pharmacol 2006; 213:18-26. [PMID: 16226778 DOI: 10.1016/j.taap.2005.09.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2005] [Revised: 09/05/2005] [Accepted: 09/11/2005] [Indexed: 10/25/2022]
Abstract
In the present study, we investigated the effect of Ginkgo biloba extracts and some of its individual constituents on the catalytic activity of human cytochrome P450 enzymes CYP1B1, CYP1A1, and CYP1A2. G. biloba extract of known abundance of terpene trilactones and flavonol glycosides inhibited 7-ethoxyresorufin O-dealkylation catalyzed by human recombinant CYP1B1, CYP1A1, and CYP1A2, and human liver microsomes, with apparent Ki values of 2 +/- 0.3, 5 +/- 0.5, 16 +/- 1.4, and 39 +/- 1.2 microg/ml (mean +/- SE), respectively. In each case, the mode of inhibition was of the mixed type. Bilobalide, ginkgolides A, B, C, and J, quercetin 3-O-rutinoside, kaempferol 3-O-rutinoside, and isorhamentin 3-O-rutinoside were not responsible for the inhibition of CYP1 enzymes by G. biloba extract, as determined by experiments with these individual chemicals at the levels present in the extract. In contrast, the aglycones of quercetin, kaempferol, and isorhamentin inhibited CYP1B1, CYP1A1, and CYP1A2. Among the three flavonol aglycones, isorhamentin was the most potent in inhibiting CYP1B1 (apparent Ki = 3 +/- 0.1 nM), whereas quercetin was the least potent in inhibiting CYP1A2 (apparent Ki = 418 +/- 50 nM). The mode of inhibition was competitive, noncompetitive, or mixed, depending on the enzyme and the flavonol. G. biloba extract also reduced benzo[a]pyrene hydroxylation, and the effect was greater with CYP1B1 than with CYP1A1 as the catalyst. Overall, our novel findings indicate that G. biloba extract and the flavonol aglycones isorhamnetin, kaempferol, and quercetin preferentially inhibit the in vitro catalytic activity of human CYP1B1.
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Affiliation(s)
- Thomas K H Chang
- Faculty of Pharmaceutical Sciences, The University of British Columbia, 2146 East Mall, Vancouver, BC, Canada V6T 1Z3.
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