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Kock G, Dicks M, Yip KT, Kohl B, Pütz S, Heumann R, Erdmann KS, Stoll R. Molecular Basis of Class III Ligand Recognition by PDZ3 in Murine Protein Tyrosine Phosphatase PTPN13. J Mol Biol 2018; 430:4275-4292. [PMID: 30189200 DOI: 10.1016/j.jmb.2018.08.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [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: 04/13/2018] [Revised: 07/31/2018] [Accepted: 08/23/2018] [Indexed: 12/26/2022]
Abstract
Protein tyrosine phosphatase PTPN13, also known as PTP-BL in mice, represents a large multi-domain non-transmembrane scaffolding protein that contains five consecutive PDZ domains. Here, we report the solution structures of the extended murine PTPN13 PDZ3 domain in its apo form and in complex with its physiological ligand, the carboxy-terminus of protein kinase C-related kinase-2 (PRK2), determined by multidimensional NMR spectroscopy. Both in its ligand-free state and when complexed to PRK2, PDZ3 of PTPN13 adopts the classical compact, globular D/E fold. PDZ3 of PTPN13 binds five carboxy-terminal amino acids of PRK2 via a groove located between the EB-strand and the DB-helix. The PRK2 peptide resides in the canonical PDZ3 binding cleft in an elongated manner and the amino acid side chains in position P0 and P-2, cysteine and aspartate, of the ligand face the groove between EB-strand and DB-helix, whereas the PRK2 side chains of tryptophan and alanine located in position P-1 and P-3 point away from the binding cleft. These structures are rare examples of selective class III ligand recognition by a PDZ domain and now provide a basis for the detailed structural investigation of the promiscuous interaction between the PDZ domains of PTPN13 and their ligands. They will also lead to a better understanding of the proposed scaffolding function of these domains in multi-protein complexes assembled by PTPN13 and could ultimately contribute to low molecular weight antagonists that might even act on the PRK2 signaling pathway to modulate rearrangements of the actin cytoskeleton.
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Affiliation(s)
- Gerd Kock
- Biomolecular NMR Spectroscopy, Faculty of Chemistry and Biochemistry, Ruhr-University of Bochum, D-44780, Germany
| | - Markus Dicks
- Biomolecular NMR Spectroscopy, Faculty of Chemistry and Biochemistry, Ruhr-University of Bochum, D-44780, Germany
| | - King Tuo Yip
- Biomolecular NMR Spectroscopy, Faculty of Chemistry and Biochemistry, Ruhr-University of Bochum, D-44780, Germany
| | - Bastian Kohl
- Biomolecular NMR Spectroscopy, Faculty of Chemistry and Biochemistry, Ruhr-University of Bochum, D-44780, Germany
| | - Stefanie Pütz
- Biomolecular NMR Spectroscopy, Faculty of Chemistry and Biochemistry, Ruhr-University of Bochum, D-44780, Germany
| | - Rolf Heumann
- Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr-University of Bochum, D-44780, Germany
| | - Kai S Erdmann
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, United Kingdom
| | - Raphael Stoll
- Biomolecular NMR Spectroscopy, Faculty of Chemistry and Biochemistry, Ruhr-University of Bochum, D-44780, Germany.
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Arnolds O, Zhong X, Tuo Yip K, Schöpel M, Kohl B, Pütz S, Abdel-Jalil R, Stoll R. NMR-based Drug Development and Improvement Against Malignant Melanoma - Implications for the MIA Protein Family. Curr Med Chem 2017; 24:1788-1796. [PMID: 28595551 DOI: 10.2174/0929867324666170608104347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [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: 01/27/2017] [Revised: 04/21/2017] [Accepted: 05/05/2017] [Indexed: 11/22/2022]
Abstract
The Melanoma Inhibitory Activity (MIA) protein is strongly expressed and secreted by malignant melanoma cells and was shown to promote melanoma development and invasion. The MIA protein was the first extracellular protein shown to adopt an Src homology 3 (SH3) domain-like fold in solution that can bind to fibronectin type III domains. Together with MIA, the homologous proteins OTOR (or FDP), MIA-2, and TANGO (or MIA-3) constitute a protein family of non-cytosolic and - except for fulllength TANGO and TANGO1-like (TALI) - extracellular SH3-domain containing proteins. Members of this protein family modulate collagen maturation and export, cartilage development, cell attachment in the extracellular matrix, and melanoma metastasis. These proteins may thus serve as promising targets for drug development against malignant melanoma. For the last twenty years, NMR spectroscopy has become a powerful technique in medicinal chemistry. While traditional high throughput screenings only report on the activity or affinity of low molecular weight compounds, NMR spectroscopy does not only relate to the structure of those compounds with their activity, but it can also unravel structural information on the ligand binding site on the protein at atomic resolution. Based on the molecular details of the interaction between the ligand and its target protein, the binding affinities of initial fragment hits can be further improved more efficiently in order to generate lead structures that exhibit significant therapeutic effects. The NMR-based approach promises to greatly contribute to the quest for low molecular weight compounds that ultimately could yield drugs to treat skin-related diseases such as malignant melanoma more effectively.
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Affiliation(s)
- Oliver Arnolds
- Biomolecular NMR, Ruhr University of Bochum, 44780 Bochum, Germany
| | - Xueyin Zhong
- Biomolecular NMR, Ruhr University of Bochum, 44780 Bochum, Germany
| | - King Tuo Yip
- Biomolecular NMR, Ruhr University of Bochum, 44780 Bochum, Germany
| | - Miriam Schöpel
- Biomolecular NMR, Ruhr University of Bochum, 44780 Bochum, Germany
| | - Bastian Kohl
- Biomolecular NMR, Ruhr University of Bochum, 44780 Bochum, Germany
| | - Stefanie Pütz
- Biomolecular NMR, Ruhr University of Bochum, 44780 Bochum, Germany
| | - Raid Abdel-Jalil
- Chemistry Department, College of Science, Sultan Qaboos University, Muscat, Oman
| | - Raphael Stoll
- Biomolecular NMR, Ruhr University of Bochum, 44780 Bochum, Germany
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Yip KT, Zhong X, Seibel N, Arnolds O, Schöpel M, Stoll R. Human melanoma inhibitory protein binds to the FN12-14 Hep II domain of fibronectin. Biointerphases 2017; 12:02D415. [PMID: 28565914 PMCID: PMC5451317 DOI: 10.1116/1.4984008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [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: 02/24/2017] [Revised: 05/03/2017] [Accepted: 05/10/2017] [Indexed: 11/17/2022] Open
Abstract
The heparin binding site (Hep II) of fibronectin plays a major role in tumor cell metastasis. Its interaction with heparan sulfate proteoglycans occurs in a variety of physiological processes including focal adhesion and migration. The melanoma inhibitory activity (MIA) is an important protein that is functionally involved in melanoma development, progression, and tumor cell invasion. After its secretion by malignant melanoma cells, MIA interacts with fibronectin and thereby actively facilitates focal cell detachment from surrounding structures and strongly promotes tumor cell invasion and the formation of metastases. In this report, the authors have determined the molecular basis of the interaction of MIA with the Hep II domain of fibronectin based on nuclear magnetic resonance spectroscopic binding assays. The authors have identified the type III modules 12 to 14 of fibronectin's Hep II as the major MIA binding sites. These results now provide a new target protein-protein binding interface for the discovery of novel antimetastatic agents against malignant melanoma in the future.
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Affiliation(s)
- King Tuo Yip
- Biomolecular NMR, Ruhr University of Bochum, 44780 Bochum, Germany
| | - Xueyin Zhong
- Biomolecular NMR, Ruhr University of Bochum, 44780 Bochum, Germany
| | - Nadia Seibel
- Biomolecular NMR, Ruhr University of Bochum, 44780 Bochum, Germany
| | - Oliver Arnolds
- Biomolecular NMR, Ruhr University of Bochum, 44780 Bochum, Germany
| | - Miriam Schöpel
- Biomolecular NMR, Ruhr University of Bochum, 44780 Bochum, Germany
| | - Raphael Stoll
- Biomolecular NMR, Ruhr University of Bochum, 44780 Bochum, Germany
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4
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Yip KT, Zhong XY, Seibel N, Pütz S, Autzen J, Gasper R, Hofmann E, Scherkenbeck J, Stoll R. Small Molecules Antagonise the MIA-Fibronectin Interaction in Malignant Melanoma. Sci Rep 2016; 6:25119. [PMID: 27151361 PMCID: PMC4858652 DOI: 10.1038/srep25119] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 04/11/2016] [Indexed: 02/01/2023] Open
Abstract
Melanoma inhibitory activity (MIA), an extracellular protein highly expressed by malignant melanoma cells, plays an important functional role in melanoma development, progression, and metastasis. After its secretion, MIA directly interacts with extracellular matrix proteins, such as fibronectin (FN). By this mechanism, MIA actively facilitates focal cell detachment from surrounding structures and strongly promotes tumour cell invasion and migration. Hence, the molecular understanding of MIA's function provides a promising target for the development of new strategies in malignant melanoma therapy. Here, we describe for the first time the discovery of small molecules that are able to disrupt the MIA-FN complex by selectively binding to a new druggable pocket, which we could identify on MIA by structural analysis and fragment-based screening. Our findings may inspire novel drug discovery efforts aiming at a therapeutically effective treatment of melanoma by targeting MIA.
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Affiliation(s)
- King Tuo Yip
- Ruhr University of Bochum, Faculty of Chemistry and Biochemistry, Bochum, 44780, Germany
| | - Xue Yin Zhong
- Ruhr University of Bochum, Faculty of Chemistry and Biochemistry, Bochum, 44780, Germany
| | - Nadia Seibel
- Ruhr University of Bochum, Faculty of Chemistry and Biochemistry, Bochum, 44780, Germany
| | - Stefanie Pütz
- Ruhr University of Bochum, Faculty of Chemistry and Biochemistry, Bochum, 44780, Germany
| | - Jasmin Autzen
- University of Wuppertal, Faculty of Chemistry, Wuppertal, 42119, Germany
| | - Raphael Gasper
- Ruhr University of Bochum, Faculty of Biology and Biotechnology, Bochum, 44801, Germany
| | - Eckhard Hofmann
- Ruhr University of Bochum, Faculty of Biology and Biotechnology, Bochum, 44801, Germany
| | | | - Raphael Stoll
- Ruhr University of Bochum, Faculty of Chemistry and Biochemistry, Bochum, 44780, Germany
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Düppe PM, Tran Thi Phuong T, Autzen J, Schöpel M, Yip KT, Stoll R, Scherkenbeck J. Sequence-selective molecular recognition of the C-terminal CaaX-boxes of Rheb and related Ras-proteins by synthetic receptors. ACS Chem Biol 2014; 9:1755-63. [PMID: 24856002 DOI: 10.1021/cb5002075] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Constitutive activation of Ras-proteins plays an important role in the development of aggressive colorectal carcinomas and several other types of cancer. Despite some progress in recent years in the case of K-Ras4B, until now not a single small molecule inhibitor has been identified that binds efficiently to Rheb and interrupts the protein-protein interactions with mTOR. We describe here a complementary approach that aims at inhibiting membrane insertion of Rheb and related Ras proteins by masking the crucial C-terminal CaaX-box with peptidomimetic receptors identified in combinatorial solid-phase libraries.
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Affiliation(s)
- Peter M. Düppe
- University of Wuppertal, Gaußstraße
20, D-42119 Wuppertal, Germany
| | | | - Jasmin Autzen
- University of Wuppertal, Gaußstraße
20, D-42119 Wuppertal, Germany
| | - Miriam Schöpel
- Ruhr-University of Bochum, Universitätsstraße
150, D-44780 Bochum, Germany
| | - King Tuo Yip
- Ruhr-University of Bochum, Universitätsstraße
150, D-44780 Bochum, Germany
| | - Raphael Stoll
- Ruhr-University of Bochum, Universitätsstraße
150, D-44780 Bochum, Germany
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Schöpel M, Jockers KFG, Düppe PM, Autzen J, Potheraveedu VN, Ince S, Yip KT, Heumann R, Herrmann C, Scherkenbeck J, Stoll R. Bisphenol A binds to Ras proteins and competes with guanine nucleotide exchange: implications for GTPase-selective antagonists. J Med Chem 2013; 56:9664-72. [PMID: 24266771 DOI: 10.1021/jm401291q] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We show for the first time that bisphenol A (10) has the capacity to interact directly with K-Ras and that Rheb weakly binds to bisphenol A (10) and 4,4'-biphenol derivatives. We have characterized these interactions at atomic resolution suggesting that these compounds sterically interfere with the Sos-mediated nucleotide exchange in H- and K-Ras. We show that 4,4'-biphenol (5) selectively inhibits Rheb signaling and induces cell death suggesting that this compound might be a novel candidate for treatment of tuberous sclerosis-mediated tumor growth. Our results propose a new mode of action for bisphenol A (10) that advocates a reduced exposure to this compound in our environment. Our data may lay the foundation for the future design of GTPase-selective antagonists with higher affinity to benefit of the treatment of cancer because K-Ras inhibition is regarded to be a promising strategy with a potential therapeutic window for targeting Sos in Ras-driven tumors.
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Affiliation(s)
- Miriam Schöpel
- Faculty of Chemistry and Biochemistry, Ruhr University of Bochum , Universitätsstraße 150, D-44780 Bochum, Germany
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Wong RCW, Heung SSY, Ho YC, Yip KT, Que TL. Evaluation of PREVI Color Gram Automated Staining System on Positive Blood Culture Samples. Lab Med 2011. [DOI: 10.1309/lmz5zo7vw2wnkonx] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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8
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Shek KC, Tsui KL, Lam KK, Crow P, Ng KHL, Ades G, Yip KT, Grioni A, Tan KS, Lung DC, Lam TSK, Fung HT, Que TL, Kam CW. Oral bacterial flora of the Chinese cobra (Naja atra) and bamboo pit viper (Trimeresurus albolabris) in Hong Kong SAR, China. Hong Kong Med J 2009; 15:183-190. [PMID: 19494373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
OBJECTIVE To determine the oral bacterial flora associated with two common local venomous snakes in Hong Kong, namely the Chinese cobra (Naja atra) and the bamboo pit viper (Trimeresurus albolabris). DESIGN Cross-sectional study. SETTING A non-government organisation and a regional hospital in Hong Kong. SUBJECTS Thirty-two Chinese cobras and seven bamboo pit vipers. MAIN OUTCOME MEASURES Species identification of bacteria in the oral cavity of both snakes and their antibiotic susceptibilities. RESULTS The oral cavity of Chinese cobra harbour a wide range of pathogenic bacteria, including: Gram-negative bacterial species like Morganella morganii, Aeromonas hydrophila and Proteus, and Gram-positive bacteria like Enterococcus faecalis, coagulase-negative Staphylococcus as well as anaerobic species (clostridia). The oral cavity of the Chinese cobra is more likely than that of the bamboo pit viper to harbour pathogenic bacteria associated with snakebite infection (P<0.001). The median number of pathogenic bacteria per snake was significantly higher in the Chinese cobra (P<0.001). All pathogenic Gram-negative bacteria isolated were susceptible to levofloxacin. Amoxicillin/clavulanate provided good coverage against pathogenic Gram-positive bacteria (Enterococcus faecalis) and anaerobes. CONCLUSION 'Prophylactic' antibiotic treatment for Chinese cobra bites may be beneficial, owing to the multiple pathogenic bacteria in its oral cavity and the higher risk of ensuing necrosis. The regimen of levofloxacin plus amoxicillin/clavulanate appears promising for this purpose, but further study is required to confirm its clinical utility in patients.
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Affiliation(s)
- K C Shek
- Accident and Emergency Department, Tuen Mun Hospital, Hospital Authority, Hong Kong.
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Yip TPP, Chan WH, Yip KT, Que TL, Lee MM, Kwong NS, Ho CK. Incidence of neonatal chlamydial conjunctivitis and its association with nasopharyngeal colonisation in a Hong Kong hospital, assessed by polymerase chain reaction. Hong Kong Med J 2007; 13:22-6. [PMID: 17277388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023] Open
Abstract
OBJECTIVES Using polymerase chain reactions, this study aimed to evaluate the incidence of neonatal chlamydial conjunctivitis in our region of Hong Kong and explore any association between such conjunctivitis and nasopharyngeal colonisation with Chlamydia trachomatis. DESIGN Prospective epidemiological study. SETTING Regional hospital, Hong Kong. PATIENTS Consecutive patients with neonatal conjunctivitis presenting to our hospital were recruited from May 2004 to April 2005 inclusive. Both eyes were investigated separately for Chlamydia trachomatis by polymerase chain reaction, direct immunofluorescent assay, and cell culture by two assigned ophthalmologists. Neonates diagnosed to have ocular Chlamydia trachomatis infection were subjected to additional nasopharyngeal investigations. Complete sets of ocular and nasopharyngeal investigations were also undertaken 1 week after oral erythromycin treatment to confirm complete eradication of Chlamydia trachomatis. RESULTS Of 192 patients with neonatal conjunctivitis, 24 were diagnosed to have chlamydial conjunctivitis. Fifteen of them had nasopharyngeal colonisation with Chlamydia trachomatis. Among the 20 neonatal chlamydial conjunctivitis patients that completed the follow-up study, one suffered treatment failure. None had clinically diagnosed systemic Chlamydia trachomatis infection 3 months after oral erythromycin. CONCLUSIONS The incidence of neonatal chlamydial conjunctivitis in our region of Hong Kong was 4 in 1000 live births, of whom 63% had nasopharyngeal presence of Chlamydia trachomatis. Owing to the high rate of nasopharyngeal isolation and possibility of treatment failure, post-treatment ocular and nasopharyngeal polymerase chain reaction testing for Chlamydia trachomatis may be considered to confirm complete eradication.
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Affiliation(s)
- Terri P P Yip
- Department of Ophthalmology, Tuen Mun Hospital, Tsing Chung Koon Road, Tuen Mun, Hong Kong.
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Tse K, Siu SLY, Yip KT, Chan SM, Que TL, Lui WYS, Chan PS. Immuno-prophylaxis of babies borne to hepatitis B carrier mothers. Hong Kong Med J 2006; 12:368-74. [PMID: 17028357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023] Open
Abstract
OBJECTIVES To examine the efficacy of current hepatitis B immuno-prophylaxis and estimate the prevalence of S-mutant infections among local newborn babies. DESIGN Prospective study. SETTING Regional hospital, Hong Kong. PATIENTS A total of 137 newborn babies delivered between the period of November 2000 and 30 June 2001 inclusive, whose mothers were chronic hepatitis B surface antigen carriers. RESULTS Of the 121 infants who were followed up for 12 months, three were found to be chronic hepatitis B virus carriers, giving a vertical transmission rate of 2.5%. One (0.8%) was suspected to be infected by the S-mutant. All the three hepatitis B virus carrier babies were born to mothers with hepatitis B e antigen, but none to the eight mothers suspected to have S-mutants. Of 119 (98.3%) infants who developed hepatitis B surface antibody upon follow-up at 12 months, 35 were found to have hepatitis B e antigen at birth. All were born to hepatitis B e antigen-positive mothers. Only three of the 35 babies were found to be hepatitis B virus carriers. Most babies lost the hepatitis B e antigen by 6 months of age; only the infected babies had the antigen persisting at 1 year of age. The non-infected infants' hepatitis B e antigen is likely transplacental. CONCLUSIONS Our hepatitis B virus prophylaxis programme was effective at preventing perinatal infection and the non-infected infants' hepatitis B e antigen was likely transplacental.
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Affiliation(s)
- K Tse
- Department of Paediatrics and Adolescent Medicine, Tuen Mun Hospital, Tsing Chung Koon Road, Tuen Mun, Hong Kong
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Ng KHL, Yip KT, Choi CH, Yeung KH, Auyeung TW, Tsang ACC, Chow L, Que TL. A case of oral myiasis due to Chrysomya bezziana. Hong Kong Med J 2003; 9:454-6. [PMID: 14660813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023] Open
Abstract
Chrysomya bezziana is a causative agent of obligatory myiasis. We report the first case of human infestation of Chrysomya bezziana in Hong Kong in an 89-year-old woman who had previously had a stroke. One day after hospital admission for fever, a small fissure at the labial gingiva of the upper incisors and several ulcerative lesions at the hard palate were noticed during routine mouth care. A live maggot was seen protruding from the small fissure. In the following few days, a total of seven maggots were removed by forceps. Urgent computed tomography and magnetic resonance imaging of the oral cavity showed an ulcerative soft-tissue lesion over the anterior palate, with a fistula communicating to the labial gingiva. The tissue loss was limited to the bony margin of the hard palate. The infestation was managed by manual removal of maggots and surgical debridement. Medical personnel taking care of old or debilitated patients need to bear in mind the possibility of Chrysomya bezziana infestation to be able to make a prompt diagnosis and implement relevant intervention to prevent extensive tissue destruction.
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Affiliation(s)
- K H L Ng
- Department of Clinical Pathology, Tuen Mun Hospital, Tsing Chung Koon Road, Tuen Mun, Hong Kong.
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12
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Que TL, Ho PL, Yip KT, Ng HL, Leung FY, Lai KK, Yuen KY. Three-year study of targeted screening for methicillin-resistant Staphylococcus aureus at hospital admission. Eur J Clin Microbiol Infect Dis 2003; 22:268-70. [PMID: 12709843 DOI: 10.1007/s10096-002-0880-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- T L Que
- New Territory North Pathology Service, Northern District Hospital, Hong Kong SAR, People's Republic of China
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Yee YK, Yip KT, Que TL, Chang KK, Li KF, Lee CK, Wong SW, Lau SF, Szeto ML. Efficacy of enzyme immunoassay for the detection of Helicobacter pylori antigens in frozen stool specimens: local validation. Aliment Pharmacol Ther 2002; 16:1739-42. [PMID: 12269966 DOI: 10.1046/j.1365-2036.2002.01338.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
AIM To investigate the efficacy of measurement of Helicobacter pylori stool antigen (HpSA) using stored frozen stool specimens, and to assess whether there were factors affecting efficacy in Hong Kong. METHODS Patients undergoing upper endoscopy at Tuen Mun Hospital were recruited. Stool samples were saved for HpSA testing and questionnaires were completed. Stool samples were frozen immediately upon receipt and stored at -70 degrees C until tested. HpSA results were compared with rapid urease test and histology. RESULTS One hundred and eighty-one patients were recruited. One hundred and seventy-eight patients were suitable for analysis. Eighty-three were H. pylori positive and 95 were H. pylori negative. The mean duration of storage of the stool samples was 120 days (range, 40-225 days). The sensitivity, specificity and positive and negative predictive values were 84.3%, 97.9%, 97.2% and 88.6%, respectively. In patients with a false negative HpSA test, there was a significant delay in collecting the stool specimen after endoscopy when compared with those with a true positive HpSA test (4.2 vs. 2.3 days; P < 0.05). However, the duration of storage of the specimens was not longer, and consumption of coffee or tea and smoking habits were similar. CONCLUSIONS HpSA testing showed good sensitivity and specificity, even with frozen stool samples stored for up to 225 days. The efficacy was not affected by coffee, tea or smoking.
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Affiliation(s)
- Y K Yee
- Department of Medicine, Tuen Mun Hospital, Hong Kong.
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14
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Ho CK, Yip KT, Eng JB, Rajan L, Tan BH. Traumatic transection of aorta. Med J Malaysia 2001; 56:374-7. [PMID: 11732086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
A 16 year-old man presented with fracture of both his femurs after a road traffic accident. Chest radiograph revealed mediastinal widening. Subsequent CT scan and arch aortogram confirmed the findings of traumatic aortic arch transection at the isthmus. He underwent successful surgical repair. High index of suspicion and prompt actions are important in managing this potentially fatal but treatable condition.
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Affiliation(s)
- C K Ho
- Department of Imaging, Hospital Lam Wah Ee, Jalan Tan Sri Teh Ewe Lim, 11600 Pulau Pinang
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