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Shelat VG, Chan CY, Liau KH. Education and imaging. Hepatobiliary and pancreatic: operative bile duct injury. J Gastroenterol Hepatol 2008; 23:1461. [PMID: 18854003 DOI: 10.1111/j.1440-1746.2008.05587.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Hui M, Au-Yeang C, Wong KT, Chan CY, Yew WW, Leung CC. Post-antibiotic effects of linezolid and other agents against Mycobacterium tuberculosis. Int J Antimicrob Agents 2008; 31:395-6. [PMID: 18272351 DOI: 10.1016/j.ijantimicag.2007.12.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 12/10/2007] [Accepted: 12/12/2007] [Indexed: 11/15/2022]
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Harrison JJ, Chan CY, Onopchenko A, Pradhan AR, Petersen M. Neutral zinc(II) O,O-di-alkyldithiopho- sphates-variable temperature 31P NMR and quantum chemical study of the ZDDP monomer-dimer equilibrium. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2008; 46:115-124. [PMID: 18098153 DOI: 10.1002/mrc.2130] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
A full line-shape analysis of the VT 31P NMR spectra was carried out for the monomer-dimer equilibrium of neutral ZDDP. The energy surface and the energetics of the monomer-dimer equilibrium (DeltaH degrees , DeltaG degrees , Ea, DeltaH(not equal), and DeltaG(not equal)) are reported for three variants wherein the alkyl groups in the ZDDP are 2-ethylhexyl, isopropyl, and isobutyl. We explored a reaction pathway between the monomer and dimer form by means of density functional theory (DFT). The linear combination of atomic orbitals (LCAO) code DMol3 was used together with a synchronous transient method to effectively locate transition states. Vibrational eigenmodes of all intermediates were computed to capture finite temperature effects. Methyl and ethyl were considered as alkyl groups. Two novel intermediates were located-a four-membered ring and a six-membered ring intermediate along the reaction coordinate. Comparison of the experimentally derived and computed energy surfaces was carried out.
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King AD, Vlantis AC, Tsang RKY, Gary TMK, Au AKY, Chan CY, Kok SY, Kwok WT, Lui HK, Ahuja AT. Magnetic resonance imaging for the detection of nasopharyngeal carcinoma. AJNR Am J Neuroradiol 2006; 27:1288-91. [PMID: 16775281 PMCID: PMC8133938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
BACKGROUND Endoscopic guided biopsy (EGB) is performed after an initial endoscopy for the investigation of patients with suspected nasopharyngeal carcinoma (NPC). The aim of the study was to determine whether MR imaging has the potential to replace invasive EGB in patients with a normal endoscopy. PATIENTS AND METHODS Data from 2 groups of patients was reviewed, group 1 with proved NPC for MR staging (n = 456) and group 2 with suspected NPC (n = 77). The sensitivity was calculated for group 1 and sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for group 2. RESULTS In group 1, which included 118 of 456 (26%) with stage 1 disease, cancer was detected in all patients, giving a sensitivity of 100%. In group 2, MR imaging was negative for NPC in 70 (91%) patients, and no cancer has been detected on follow-up (follow-up range, 1-90 months; mean, 36 months). MR imaging was positive for NPC in 7 (9%) patients and NPC was confirmed by biopsy in 3 (4%). Two of these 3 patients had undergone negative endoscopy and biopsy before the MR imaging. NPC was not present in the remaining 4 patients, 2 of whom were found to have lymphoid hyperplasia. MR imaging had a sensitivity of 100%, specificity of 95%, NPV of 100%, PPV of 43%, and accuracy of 95%. CONCLUSION MR imaging has the potential to screen healthy patients who do not require EGB and direct the site of biopsy in small cancers that may be missed by endoscopy. On the basis of these results, a prospective study is planned.
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Schmoll HJ, Aapro MS, Poli-Bigelli S, Kim HK, Park K, Jordan K, von Pawel J, Giezek H, Ahmed T, Chan CY. Comparison of an aprepitant regimen with a multiple-day ondansetron regimen, both with dexamethasone, for antiemetic efficacy in high-dose cisplatin treatment. Ann Oncol 2006; 17:1000-6. [PMID: 16524979 DOI: 10.1093/annonc/mdl019] [Citation(s) in RCA: 194] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND We compared an aprepitant regimen with a control regimen of ondansetron + dexamethasone given for 4 days. PATIENTS AND METHODS Patients scheduled to receive cisplatin > or =70 mg/m(2) were randomized to either the aprepitant regimen (aprepitant, ondansetron and dexamethasone on day 1; aprepitant and dexamethasone on days 2-3; dexamethasone on day 4) or control regimen (ondansetron + dexamethasone on days 1-4). Patients recorded vomiting, nausea and rescue therapy use. The primary end point was complete response (no vomiting and no use of rescue therapy) in the overall phase (days 1-5 post-cisplatin). RESULTS Complete response rates were higher in the aprepitant than control group in the overall (72% versus 61%; P = 0.003), acute (day 1; 88% versus 79%; P = 0.005) and delayed phases (days 2-5; 74% versus 63%; P = 0.004), as were rates of no vomiting (overall 77% versus 62%, P < or = 0.001; acute 89% versus 81%, P = 0.004; delayed 79% versus 64%, P < or = 0.001). Rates of no rescue therapy were similar between groups. CONCLUSIONS Compared with an antiemetic regimen in which ondansetron + dexamethasone were given for 4 days, the aprepitant regimen was superior in the acute, delayed and overall phases of chemotherapy-induced nausea and vomiting. The aprepitant regimen should be considered a new standard of antiemetic therapy for cisplatin-treated patients. www.ClinicalTrials.gov Identifier: NTC00090207.
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Ng KHL, Wu AKL, Cheng VCC, Tang BSF, Chan CY, Yung CY, Luk SH, Lee TW, Chow L, Yuen KY. Pulmonary artery thrombosis in a patient with severe acute respiratory syndrome. Postgrad Med J 2005; 81:e3. [PMID: 15937197 PMCID: PMC1743280 DOI: 10.1136/pgmj.2004.030049] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Severe acute respiratory syndrome (SARS) is an emerging infectious disease with both pulmonary and extra-pulmonary manifestations. Although coagulation abnormalities are common in these patients, clinically overt thromboembolic events are rarely reported. This report describes the first case of pulmonary artery thrombosis in a patient with laboratory confirmed SARS.
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Dinubile MJ, Friedland I, Chan CY, Motyl MR, Giezek H, Shivaprakash M, Weinstein RA, Quinn JP. Bowel colonization with resistant gram-negative bacilli after antimicrobial therapy of intra-abdominal infections: observations from two randomized comparative clinical trials of ertapenem therapy. Eur J Clin Microbiol Infect Dis 2005; 24:443-9. [PMID: 15990986 DOI: 10.1007/s10096-005-1356-0] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The selection of resistant gram-negative bacilli by broad-spectrum antibiotic use is a major issue in infection control. The aim of this comparative study was to assess the impact of different antimicrobial regimens commonly used to treat intra-abdominal infections on the susceptibility patterns of gram-negative bowel flora after completion of therapy. In two international randomized open-label trials with laboratory blinding, adults with complicated intra-abdominal infection requiring surgery received piperacillin-tazobactam (OASIS 1) or ceftriaxone/metronidazole (OASIS II) versus ertapenem for 4-14 days. Rectal swabs were obtained at baseline, end of therapy, and 2 weeks post-therapy. Escherichia coli and Klebsiella spp. were tested for production of extended-spectrum beta-lactamase (ESBL). Enterobacteriaceae resistant to the agent used were recovered from 19 of 156 (12.2%) piperacillin-tazobactam recipients at the end of therapy compared to 1 (0.6%) patient at baseline (p<0.001) in OASIS I, and from 33 of 193 (17.1%) ceftriaxone/metronidazole recipients at the end of therapy compared to 5 (2.6%) patients at baseline (p<0.001) in OASIS II. Ertapenem-resistant Enterobacteriaceae were recovered from 1 of 155 and 1 of 196 ertapenem recipients at the end of therapy versus 0 and 1 ertapenem recipients at baseline in OASIS I and II, respectively. Resistant Enterobacteriaceae emerged significantly less often during treatment with ertapenem than with the comparator in both OASIS I (p<0.001) and OASIS II (p<0.001). The prevalence of ESBL-producers increased significantly during therapy in OASIS II among 193 ceftriaxone/metronidazole recipients (from 4 [2.1%] to 18 [9.3%]) (p<0.001), whereas no ertapenem recipient was colonized with an ESBL-producer at the end of therapy in either study. Selection for imipenem-resistant Pseudomonas aeruginosa was uncommon in all treatment groups. In these studies, the frequency of bowel colonization with resistant Enterobacteriaceae substantially increased in patients treated with either piperacillin-tazobactam or ceftriaxone/metronidazole, but not in patients treated with ertapenem.
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Zhang WJ, Meng XM, Chan CY, Chan KM, Wu Y, Bello I, Lee ST. Interfacial Study of Cubic Boron Nitride Films Deposited on Diamond. J Phys Chem B 2005; 109:16005-10. [PMID: 16853031 DOI: 10.1021/jp0517908] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have studied the nucleation and growth of cubic boron nitride (cBN) films deposited on silicon and diamond-coated silicon substrates using fluorine-assisted chemical vapor deposition (CVD). These comparative studies substantiate that the incubation amorphous/turbostratic BN layers, essential for the cBN nucleation on silicon, are not vital precursors for cBN nucleation on diamond, and they are inherently eliminated. At vastly reduced critical bias voltage, down to -10 V, cBN growth is still maintained on diamond surfaces, and cBN and underlying diamond crystallites exhibit an epitaxial relationship. However, the epitaxial growth is associated with stress in the cBN-diamond interfacial region. In addition, some twinning of crystallites and small-angle grain boundaries are observed between the cBN and diamond crystallites because of the slight lattice mismatch of 1.36%. The small-angle grain boundaries could be eliminated by imposing a little higher bias voltage during the initial growth stage. The heteroepitaxial growth of cBN films on different substrate materials are discussed in the view of lattice matching, surface-energy compatibility, and stability of the substrate against ion irradiation.
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Zhang WJ, Chan CY, Meng XM, Fung MK, Bello I, Lifshitz Y, Lee ST, Jiang X. The Mechanism of Chemical Vapor Deposition of Cubic Boron Nitride Films from Fluorine-Containing Species. Angew Chem Int Ed Engl 2005; 44:4749-53. [PMID: 15995991 DOI: 10.1002/anie.200500320] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Oxman MN, Levin MJ, Johnson GR, Schmader KE, Straus SE, Gelb LD, Arbeit RD, Simberkoff MS, Gershon AA, Davis LE, Weinberg A, Boardman KD, Williams HM, Zhang JH, Peduzzi PN, Beisel CE, Morrison VA, Guatelli JC, Brooks PA, Kauffman CA, Pachucki CT, Neuzil KM, Betts RF, Wright PF, Griffin MR, Brunell P, Soto NE, Marques AR, Keay SK, Goodman RP, Cotton DJ, Gnann JW, Loutit J, Holodniy M, Keitel WA, Crawford GE, Yeh SS, Lobo Z, Toney JF, Greenberg RN, Keller PM, Harbecke R, Hayward AR, Irwin MR, Kyriakides TC, Chan CY, Chan ISF, Wang WWB, Annunziato PW, Silber JL. A vaccine to prevent herpes zoster and postherpetic neuralgia in older adults. N Engl J Med 2005; 352:2271-84. [PMID: 15930418 DOI: 10.1056/nejmoa051016] [Citation(s) in RCA: 1500] [Impact Index Per Article: 78.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND The incidence and severity of herpes zoster and postherpetic neuralgia increase with age in association with a progressive decline in cell-mediated immunity to varicella-zoster virus (VZV). We tested the hypothesis that vaccination against VZV would decrease the incidence, severity, or both of herpes zoster and postherpetic neuralgia among older adults. METHODS We enrolled 38,546 adults 60 years of age or older in a randomized, double-blind, placebo-controlled trial of an investigational live attenuated Oka/Merck VZV vaccine ("zoster vaccine"). Herpes zoster was diagnosed according to clinical and laboratory criteria. The pain and discomfort associated with herpes zoster were measured repeatedly for six months. The primary end point was the burden of illness due to herpes zoster, a measure affected by the incidence, severity, and duration of the associated pain and discomfort. The secondary end point was the incidence of postherpetic neuralgia. RESULTS More than 95 percent of the subjects continued in the study to its completion, with a median of 3.12 years of surveillance for herpes zoster. A total of 957 confirmed cases of herpes zoster (315 among vaccine recipients and 642 among placebo recipients) and 107 cases of postherpetic neuralgia (27 among vaccine recipients and 80 among placebo recipients) were included in the efficacy analysis. The use of the zoster vaccine reduced the burden of illness due to herpes zoster by 61.1 percent (P<0.001), reduced the incidence of postherpetic neuralgia by 66.5 percent (P<0.001), and reduced the incidence of herpes zoster by 51.3 percent (P<0.001). Reactions at the injection site were more frequent among vaccine recipients but were generally mild. CONCLUSIONS The zoster vaccine markedly reduced morbidity from herpes zoster and postherpetic neuralgia among older adults.
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Chan CY, Yoo JE, Travers SP. Diverse bitter stimuli elicit highly similar patterns of Fos-like immunoreactivity in the nucleus of the solitary tract. Chem Senses 2005; 29:573-81. [PMID: 15337683 DOI: 10.1093/chemse/bjh062] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Previous studies have demonstrated that oral stimulation with quinine elicits Fos-like immunoreactivity in the first-order gustatory nucleus, the NST, with a different topographic distribution than sucrose or citric acid. However, it is unknown whether the quinine pattern is unique to this alkaloid or common across bitter stimuli with different chemical structures. Indeed, recent physiological experiments suggest that taste receptor cells and primary afferent neurons may exhibit selectivity for various bitter tastants. The present investigation compared the distribution of FLI in NST following stimulation with three bitter chemicals: QHCl, denatonium and propylthiouracil, stimuli that evoked Ca(2+) currents in almost entirely different sets of receptor cells. The results demonstrate that the quinine pattern is not idiosyncratic but instead generalizes to the other two tastants. Although it remains possible that intermingled but different NST neurons are activated by these stimuli, these data suggest that a specialized region in the NST is preferentially involved in processing a common aspect of bitter tastants. In contrast to citric acid, quinine, denatonium and propylthiouracil all elicited vigorous oromotor rejection responses, consistent with our earlier hypothesis that the medial third of the NST may be an afferent trigger zone for oromotor rejection.
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Abstract
INTRODUCTION Mirizzi syndrome (MS) is an unusual complication of gallstone disease. The majority of cases are not identified pre-operatively, despite advances in imaging techniques. MATERIALS AND METHODS Eighteen cases of MS were treated between January 1997 and April 2002. The clinical presentation, modes of investigation, surgical management and outcome are retrospectively reviewed. RESULTS There were 13 female and 5 male patients, with a mean age of 60 years. Seven patients presented with the classical Charcot's triad. Ultrasonography (US) was the first imaging investigation in 13 patients and computerised tomography (CT) in the other five cases. Eleven patients had a successful endoscopic retrograde cholangio-pancreatography (ERCP) carried out. Diagnosis of MS was arrived at in seven patients following pre-operative imagings. Overall, 11 patients had Type 1 and seven patients had Type 2 MS. In the group with Type 1 MS, nine patients underwent open cholecystectomy, of whom six had concomitant common bile duct (CBD) exploration for stones and one patient with biliary stenosis had a hepaticojejunostomy bypass. Laparoscopic cholecystectomy was attempted in two patients, with successful completion in one case. In the group with Type 2 MS, four fistulas were closed surgically, the other three had biliary bypass procedures. CONCLUSION Mirizzi syndrome is an unusual condition that poses diagnostic and operative challenges to the surgeon. With a judicious approach during dissection and early recognition of its presence, bile duct injury can be avoided. Good outcome can be achieved with an appropriate surgical procedure.
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Chan CY, Tao S, Dawson R, Wong PK. Treatment of atrazine by integrating photocatalytic and biological processes. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2004; 131:45-54. [PMID: 15210274 DOI: 10.1016/j.envpol.2004.02.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2003] [Accepted: 02/09/2004] [Indexed: 05/24/2023]
Abstract
This research examines the degradation of atrazine by photocatalytic oxidation (PCO) under different experimental conditions. Deisopropylatrazine, deethylatrazine and deethyldeisopropylatrazine were formed as major intermediates based on gas chromatography-mass spectrometry. The reaction mixture was found to be toxic towards two bioassays, i.e. the Microtox and amphipods survival tests even when atrazine was completely degraded by PCO within 2 h under optimized conditions. The results indicate that adding H2O2 could significantly enhance the degradation of atrazine by PCO. Ammeline, ammelide and cyanuric acid (CA) became the major intermediates/products as detected by high performance liquid chromatography from 6th to the 40th h of PCO treatment. After 72 h PCO treatment, only CA was detectable in the reaction mixture. Further degradation of CA was carried out by a newly isolated CA-degrading bacterium, Sphingomonas capsulata. The photochemical pretreatment integrated with microbial degradation lead to the complete degradation and detoxification of atrazine.
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Rajasekhar L, Liou LB, Chan CY, Tsai WP, Cheng CY. Matrix metalloproteinase-8 in sera and from polymorphonuclear leucocytes in rheumatoid arthritis: in vitro characterization and correlation with disease activity. Clin Exp Rheumatol 2004; 22:597-602. [PMID: 15485013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
OBJECTIVES To determine matrix metalloproteinase-8 (MMP-8) secretion from rheumatoid arthritis (RA) peripheral blood polymorphonuclear leucocytes (PMNs), in response to immune complexes (IC), cytokines and their combinations, and to study correlation of serum MMP-8 with disease activity. METHODS PMNs from RA patients and controls were stimulated in vitro with interleukin-15 (IL-15), IL-18, adherent immune complexes, rabbit anti-human immunoglobulin G (anti-HIgG), human immunoglobulin G (HIgG), and their F (ab') 2 prongs, phorbol myristate acetate (PMA) or combinations of above. Supernatants from these experiments and sera from both groups were assayed for MMP-8 using ELISA and correlated with disease activity measures in patients. RESULTS MMP-8 secretion from stimulated PMNs was compared to unstimulated PMNs. Immune complexes elicited significant MMP-8 secretion (p = 0.006 and 0.001, control and RA respectively). Unlike HIgG and its F (ab')2 fragment, very high secretion was elicited by anti-HIgG (242.37 +/- 10.85 ng/ml) and its F (ab')2 prong (195.85 +/- 28.67 ng/ml). IL-15 did not elicit any secretion. IL-18 with PMA increased secretion significantly only from RA PMNs (p = 0.003). Serum MMP-8 correlated positively with serum CRP (p = 0.017) and not with disease activity score (p = 0.199). CONCLUSIONS We for the first time demonstrate that immune complexes elicit MMP-8 secretion from PMNs. Except for higher secretion from RA PMNs in response to combination of IL-18 and PMA, both control and RA PMNs respond similarly to various stimuli. Secretion by anti-HIgG occurs by a mechanism independent of Fc receptor. Correlation with CRP suggest that serum MMP-8 may be an indicator of acute inflammatory activity.
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Abstract
This study provides the first systematic research of homicide-suicide (HS) in a Chinese society. Data were drawn from the HK Homicide Monitoring Data-base computer file derived from investigation and death reports held by the HK Police Force and the Coroner's Court. During the 10-year study period, 56 events involving 133 deaths were identified. The majority of offenders were males (75%) and most victims were female (64%). The mean age of offenders and victims were 41.9 and 32.3 years, respectively. Spouses and lovers comprised the majority of victims (46.4%) followed by child victims (36%). Most HS events were motivated by separation or termination of marital or sexual relations (39%), economic reasons (25%) and other domestic disputes (20%). The most frequent modes of killing were strangulation/suffocation (26%), stabbing/chopping (24%), followed by gassing/poisoning (14%) and falling from height (14%). The commonest of suicide was falling from height (48%). It was followed by gassing/poisoning (22%) and strangulation/suffocation (13%). Depression (18.3%) was found to be the commonest mental disorder. Most offenders were from low-socio-economic background. Two-third were unemployed and 76.6% had 9 or less years of education. HS in HK were distinguished from those reported in the western literature in respect to the high relevance of economic factors, the absence of mercy killing between old couples, a higher percentage of pedicide-suicides and the infrequent use of firearms.
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Abstract
This study provides the first systematic research of homicide-suicide (HS) in a Chinese society. Data were drawn from the HK Homicide Monitoring Data-base computer file derived from investigation and death reports held by the HK Police Force and the Coroner's Court. During the 10-year study period, 56 events involving 133 deaths were identified. The majority of offenders were males (75%) and most victims were female (64%). The mean age of offenders and victims were 41.9 and 32.3 years, respectively. Spouses and lovers comprised the majority of victims (46.4%) followed by child victims (36%). Most HS events were motivated by separation or termination of marital or sexual relations (39%), economic reasons (25%) and other domestic disputes (20%). The most frequent modes of killing were strangulation/suffocation (26%), stabbing/chopping (24%), followed by gassing/poisoning (14%) and falling from a height (14%). The commonest method of suicide was falling from a height (48%). It was followed by gassing/poisoning (22%) and strangulation/suffocation (13%). Depression (18.3%) was found to be the commonest mental disorder. Most offenders were from low-socio-economic background. Two-third were unemployed and 76.6% had 9 or less years of education. HS in HK were distinguished from those reported in the western literature in respect to the high relevance of economic factors, the absence of mercy killing between old couples, a higher percentage of pedicide-suicides and the infrequent use of firearms.
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Zou SC, Lee SC, Chan CY, Ho KF, Wang XM, Chan LY, Zhang ZX. Characterization of ambient volatile organic compounds at a landfill site in Guangzhou, South China. CHEMOSPHERE 2003; 51:1015-1022. [PMID: 12697192 DOI: 10.1016/s0045-6535(03)00004-3] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Ambient air monitoring was conducted at Datianshan landfill, Guangzhou, South China in 1998 to investigate the seasonal and horizontal variations of trace volatile organic compounds (VOCs). Twelve sampling points over the Datianshan landfill were selected and samples were collected simultaneously using Carbontrap(TM) adsorption tubes. Thirty eight VOCs were detected in the winter, whereas 60 were detected in the summer. The VOC levels measured in summer were alkanes, 0.5-6.5 microg/m(3); aromatics, 2.3-1667 microg/m(3); chlorinated species, 0.2-31 microg/m(3); terpines, 0.1-34 microg/m(3); carbonyl species, 0.3-5.6 microg/m(3) and naphthalene and its derivatives, 0.4-27 microg/m(3). Compared to the summer samples the VOC levels in winter were much lower (mostly 1-2 orders of magnitude lower). The aromatics are dominant VOCs in landfill air both in winter and summer. High levels of alkylbenzene and terpines such as methyl-isopropylbenzene (max 1667 microg/m(3)) and limonene (max 162 microg/m(3)) cause undesirable odor. The similar correlation coefficients of BTEX in summer and winter suggest VOCs emissions were from landfill site sources. The variation of BTEX ratio at landfill site is different from that in the urban area of Guangzhou. It shows that the ambient VOCs at landfill site were different from the urban areas.
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Yew WW, Chan E, Chan CY, Cheng AF. Genotypic and phenotypic resistance of Mycobacterium tuberculosis to rifamycins and fluoroquinolones. Int J Tuberc Lung Dis 2002; 6:936-7. [PMID: 12365583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023] Open
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Chan JHM, Tsui EYK, Chan CY, Lai KF, Chau LF, Fong D, Mok CK, Cheung YK, Wong KPC, Yuen MK. Digital subtraction in gadolinium-enhanced MR imaging of the brain: a method to reduce contrast dosage. Eur Radiol 2002; 12:2317-21. [PMID: 12195488 DOI: 10.1007/s00330-001-1285-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2001] [Revised: 11/15/2001] [Accepted: 11/22/2001] [Indexed: 12/01/2022]
Abstract
The aim of the study was to investigate the feasibility of using digital subtraction in contrast-enhanced MR imaging of the brain to reduce the MR contrast dosage without jeopardizing patient care. Fifty-two patients with intracranial lesions, either intra-axial or extra-axial, detected by computerized tomography were selected for contrast-enhanced MR imaging with half-dose and full-dose of gadopentetate dimeglumine. The half-dose unsubtracted, full-dose unsubtracted, and half-dose subtracted MR images were visually assessed by counting the number of enhancing brain lesions in the images and quantitatively analyzed by computing their lesion contrast-to-background ratios (CBR). The visual conspicuity of the half-dose subtracted MR images was comparable to that of the full-dose unsubtracted MR images ( p>0.05), whereas the CBR of the half-dose subtracted images was approximately two to three times higher than that of the full-dose unsubtracted images. The half-dose subtracted T1-weighted spin-echo images might be able to replace the conventional standard-dose T1-weighted spin-echo images in MR imaging of the brain.
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Heng CT, Liau KH, Ho CK, Chan CY, Wong M, Chew SP. Hepatolithiasis--a case series. ANNALS OF THE ACADEMY OF MEDICINE, SINGAPORE 2002; 31:97-101. [PMID: 11885506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
INTRODUCTION Hepatolithiasis is an uncommon entity in Singapore. We reviewed the cases presented to our institution (a 1200-bedded restructured hospital) over a 5-year period. MATERIAL AND METHODS Twelve cases of hepatolithiasis were treated between December 1995 and July 2000 representing 0.77% of gallstone disease operated on in the same period. The clinical presentation, investigations, treatment and subsequent progress are presented. RESULTS The patients' ages ranged from 28 to 82 years. There was a male to female ratio of 5:7. All patients had upper abdominal pain at presentation; 10 patients had clinical evidence of cholangitis. Ultrasound was the commonest first line investigation but additional investigations, such as computed tomographic (CT) scan and various forms of cholangiography, were frequently necessary for complete delineation of the biliary disease. The intrahepatic stones were located predominantly in the left lobe of the liver. Parenchymal atrophy was seen in 83% of patients. Two patients underwent a biliary bypass operation only, 5 had a hepatic resection only, and 5 had combined procedures. Follow-up ranged from 4 to 50 months. Postoperative recovery was generally unremarkable. Complications included subphrenic abscess (1 patient), recurrent stricture (1 patient) and recurrent stones (1 patient). One patient had an elevated serum CA 19-9 preoperatively; a small villous adenoma was noted at the biliary stricture in the resected left lateral segment of the liver. There was no operative mortality. CONCLUSION Hepatolithiasis is uncommon in Singapore. Complete diagnosis requires a combination of imaging modalities. Surgery remains the mainstay of definitive treatment. With adequate treatment, good outcome is possible.
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Chan CY, Au-Yeang C, Yew WW, Hui M, Cheng AF. Postantibiotic effects of antituberculosis agents alone and in combination. Antimicrob Agents Chemother 2001; 45:3631-4. [PMID: 11709357 PMCID: PMC90886 DOI: 10.1128/aac.45.12.3631-3634.2001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2000] [Accepted: 09/16/2001] [Indexed: 11/20/2022] Open
Abstract
The postantibiotic effects (PAEs) of seven antimycobacterial agents, tested at their respective peak concentrations in serum alone and in different combinations, against Mycobacterium tuberculosis ATCC 27294 were studied with a radiometric culture system in parallel with the viable count method. Rifampin gave the longest PAE (67.8 h) among the drugs used alone, and combinations of first-line drugs generally gave PAEs longer than 120 h. The data obtained might help provide a better understanding of the scientific basis of intermittently administered antituberculosis chemotherapy.
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Vessey SJ, Chan CY, Kuter BJ, Kaplan KM, Waters M, Kutzler DP, Carfagno PA, Sadoff JC, Heyse JF, Matthews H, Li S, Chan IS. Childhood vaccination against varicella: persistence of antibody, duration of protection, and vaccine efficacy. J Pediatr 2001; 139:297-304. [PMID: 11487760 DOI: 10.1067/mpd.2001.116051] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To document the duration of protection afforded by Oka/Merck varicella vaccine over a 7-year period. STUDY DESIGN The subjects were healthy children 1 to 12 years of age originally enrolled in clinical studies to evaluate the primary immune response to varicella vaccine 6 weeks after vaccination. Each was monitored for antibody persistence, breakthrough infection, and household exposure to varicella to produce estimates of vaccine efficacy. RESULTS The 6-year cumulative varicella antibody persistence rate was 99.5% (95% CI: 98.9%, 100.0%). The annual breakthrough rate through 7 years ranged from 0.2% to 2.3% per year; the estimated cumulative event rate was 6.5%. Comparison of the observed average annual breakthrough rate with the age-adjusted expected annual incidence rate of varicella in unvaccinated children corresponded to an estimated vaccine efficacy of 93.8% to 94.6%. Eighty vaccinated children were exposed to varicella in the household, resulting in 8 (10%) cases of infection. When compared with the historical attack rate of 86.8% in unvaccinated susceptible persons exposed to varicella in the household, this yields an estimated vaccine efficacy of 88.5% (95% CI: 80.9%, 96.1%). Varicella cases in vaccinated children generally were mild. CONCLUSION The live attenuated varicella vaccine is highly effective in inducing persistent immunity and long-term protection against breakthrough varicella infection.
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Levin MJ, Gershon AA, Weinberg A, Blanchard S, Nowak B, Palumbo P, Chan CY. Immunization of HIV-infected children with varicella vaccine. J Pediatr 2001; 139:305-10. [PMID: 11487761 DOI: 10.1067/mpd.2001.115972] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To determine the safety and immunogenicity of varicella vaccine in children with human immunodeficiency virus (HIV) infection. Children (n = 41) who were mildly affected by HIV (Centers for Disease Control and Prevention stage N1 or A1) and had no history or serum antibody indicative of prior varicella infection were immunized with two doses of live attenuated varicella vaccine. RESULTS A minority of the vaccine recipients had mild local or systemic reactions. Vaccination had no effect on the clinical stage of HIV or the HIV RNA plasma load. CD4 cell percentage and CD4 cell count were marginally decreased at week 4 after the first vaccination; this effect was no longer present at week 8 after vaccination. Two months after the second dose of vaccine, 60% of vaccine recipients had anti-varicella antibody in their serum, and 83% had a positive lymphocyte proliferation assay response to varicella antigen. CONCLUSION On the basis of its safety and immunogenicity, varicella vaccine should be considered in the childhood vaccines given to mildly affected HIV-infected children.
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