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Tan RY, Pang SC, Teh SP, Lee KG, Ng CY, Foo WYM, Gogna A, Chong TT, Tan CS. FP653OUTCOMES ENDOVASCULAR SALVAGE OF CLOTTED ARTERIOVENOUS ACCESSES AND PREDICTORS OF POSTINTERVENTION PATENCY. Nephrol Dial Transplant 2019. [DOI: 10.1093/ndt/gfz106.fp653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Phang CC, Tan RY, Pang SC, Tan CW, Teh SP, Cheng R, Kho YX, Chong TT, Gogna A, Foo WY, Tan CS. Paclitaxel‐coated balloon in the treatment of recurrent dysfunctional arteriovenous access, real‐world experience and longitudinal follow up. Nephrology (Carlton) 2019; 24:1290-1295. [DOI: 10.1111/nep.13591] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2019] [Indexed: 01/10/2023]
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Htay H, Seng JJB, Yong MHA, Pang SC, Wu SY, Chan CM, Sim MH, Johnson DW, Foo MWY. Comparison of Clinical Presentation and Outcomes of Peritonitis in the Elderly and Younger Peritoneal Dialysis Patients. Perit Dial Int 2019; 39:163-168. [DOI: 10.3747/pdi.2018.00056] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Accepted: 07/01/2018] [Indexed: 11/15/2022] Open
Abstract
Background The incidence of elderly patients receiving peritoneal dialysis (PD) has increased. This study aimed to examine the clinical presentation and outcomes of peritonitis in elderly PD patients compared with younger PD patients. Methods This single-center, retrospective, observational cohort study included all adult PD patients who developed peritonitis between January 2011 and December 2014. Elderly was defined as ≥ 65 years old at PD initiation. The primary outcome was medical cure, defined as a peritonitis episode cured by antibiotics without being complicated by catheter removal, transfer to hemodialysis (HD), relapsing peritonitis, or death. The secondary outcomes were clinical manifestations (fever, cloudy dialysate) and complications (catheter removal, transfer to HD, relapse, hospitalization, and mortality). Peritonitis outcomes were compared using multivariable logistic regression. Results Overall, 377 peritonitis episodes occurred in 247 patients. Of these, 126 episodes occurred in 79 elderly patients and 251 episodes occurred in 168 younger patients. Baseline demographic data were comparable between the 2 groups, except that elderly patients were significantly more likely to have diabetes mellitus (66% vs 46%), diabetic nephropathy (55% vs 39%), and a lower serum albumin than younger patients. Medical cure was comparable between the 2 groups (71% vs 72%, respectively, p = 0.67, adjusted odds ratio [AOR] 0.89, 95% confidence interval [CI]: 0.52 – 1.53). Compared with younger patients, elderly patients experiencing peritonitis had lower odds of fever (OR 0.53, 95% CI: 0.30 – 0.94), cloudy dialysate (OR 0.45, 95% CI: 0.23 – 0.88), and catheter removal (AOR 0.50, 95% CI: 0.26 – 0.98), but similar odds of transfer to HD (AOR 0.70, 95% CI: 0.32 – 1.51), relapse (AOR 1.57, 95% CI: 0.46 – 5.40), hospitalization (AOR 1.55, 95% CI: 0.52 – 4.56), and all-cause mortality (AOR 1.88, 95% CI: 0.83 – 4.26). Conclusions Compared with younger patients, elderly PD patients with peritonitis achieved similar medical cure rates, a lower catheter removal rate, and comparable rates of HD transfer, relapse, hospitalization, and death. Elderly PD patients experiencing peritonitis were less likely to present with fever or cloudy dialysate.
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Tan RY, Pang SC, Teh SP, Lee KG, Chong TT, Gogna A, Tan CS. Comparison of alteplase and urokinase for pharmacomechanical thrombolysis of clotted hemodialysis access. J Vasc Access 2018; 20:501-506. [PMID: 30585114 DOI: 10.1177/1129729818819735] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Percutaneous pharmacomechanical thrombolysis is increasingly used to salvage thrombosed hemodialysis access. We aim to evaluate the effectiveness of alteplase compared to urokinase in percutaneous pharmacomechanical thrombolysis clotted access. METHODS Records of patients who underwent pharmacomechanical thrombolysis at Interventional Nephrology Suite in a tertiary teaching hospital from 1 January 2016 to 31 December 2016 were reviewed. Technical and clinical success rates, thrombosis-free and cumulative survivals, procedure time, and radiation dose imparted to patients were compared for pharmacomechanical thrombolysis with urokinase versus alteplase. RESULTS A total of 122 incident patients underwent pharmacothrombolysis (n = 53 for urokinase, n = 69 for alteplase) during the study period. The mean dose of urokinase and alteplase used was 176,897 ± 73,418 units and 3.7 ± 0.8 mg, respectively. Pharmacomechnical thrombolysis using urokinase versus alteplase has similar technical success rate (98.1% vs 97.1%, p = 0.599), clinical success rate (88.7% vs 97.1%, p = 0.068), complication rate (9.4% vs 13.0%, p = 0.373), and primary patency rates at 3 months (57.1% vs 70.1%, p = 0.106). Thrombosis-free survivals of the vascular access were 113.2 (35.3, 196) days versus 122 (84, 239) days (p = 0.168). Cumulative survivals were 239 (116, 320) vs 213 (110.5, 316.5) days (p = 0.801). Procedure time, fluoroscopy time, skin dose, and dose were significantly lower for pharmacomechanical thrombolysis using alteplase compared to urokinase (p = 0.045, p < 0.0001, p = 0.006, p = 0.001, respectively). Stenting was found to be associated with successful dialysis following thrombolysis on univariate analysis (odds ratio: 9.167, 95% confidence interval: 1.391-19.846, p = 0.021), although this was no longer significant in multivariate analysis (p = 0.078). CONCLUSION Alteplase is an effective and safe alternative to urokinase for pharmacomechanical thrombolysis of clotted vascular access.
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Tan RY, Lee KG, Gan SWS, Li H, Yeon W, Pang SC, Teh SP, Htay H, Teo SH, Kwek JL, Tok PL, Poh CB, Ng CY, Liu P, Tay HB, Koniman R, Foo MWY, Choong LHL, Tan CS. Impact of simulation‐based learning on immediate outcomes of temporary haemodialysis catheter placements by nephrology fellows. Nephrology (Carlton) 2018; 23:933-939. [DOI: 10.1111/nep.13156] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 07/21/2017] [Accepted: 08/13/2017] [Indexed: 01/02/2023]
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Tan RY, Chong TT, Tsai FC, Pang SC, Lee KG, Gogna A, Ong AH, Tan CS. A pilot study on adjunctive use of parametric colour-coded digital subtraction angiography in endovascular interventions of haemodialysis access. BMC Med Imaging 2018; 18:28. [PMID: 30219054 PMCID: PMC6139131 DOI: 10.1186/s12880-018-0270-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 08/24/2018] [Indexed: 11/10/2022] Open
Abstract
Background Two-dimensional digital subtraction angiography (DSA) is the gold standard for angiographic evaluation of dysfunctional haemodialysis access. We aim to investigate the utility of parametric colour coded DSA in providing hemodynamic analysis during haemodialysis access interventions. Methods We retrospectively studied 20 patients who underwent access intervention and applied parametric colour-coding on selected DSA acquisitions before and after percutaneous transluminal angioplasty (PTA). The difference in time to peak (dTTP) contrast enhancement and time attenuation curve (TAC) of pre- and post-stenotic regions of interest (ROIs) were obtained and compared after treatment. Results Improvements were seen in mean percent of stenosis after PTA (p < 0.0001) for all cases. Median dTTP improved from 0.52 (IQR 0.26, 0.8) to 0.25 (IQR 0, 0.26) seconds (p = 0.001). Median 50% contrast washout time improved from 0.77 (IQR 0.39, 1.17) to 0.42 (IQR 0.23, 0.59) seconds (p = 0.031). Significant correlation was seen for dTTP vs. percent of stenosis (r = 0.723, p = 0.043) pre-PTA and for change in dTTP vs. percent change in stenosis post-PTA (r = 0.786, p = 0.021) for inflow lesions. Such correlation was however not seen in outflow lesions. Conclusions Adjunctive use of parametric colour-coded DSA may provide potentially useful hemodynamic information during vascular access interventions. Larger prospective studies are needed to validate our findings.
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Tan RY, Teh SP, Pang SC, Tan CS. FP563ALTEPLASE VERSUS UROKINASE FOR PHARMACOMECHANICAL THROMBOLYSIS OF THROMBOSED DIALYSIS ACCESS. Nephrol Dial Transplant 2018. [DOI: 10.1093/ndt/gfy104.fp563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Lee KG, Tan RY, Chidambaram VA, Pang SC, Tan CS. Duplicate superior vena cava on arteriovenous fistulography. J Vasc Surg Venous Lymphat Disord 2017; 5:739. [PMID: 28818231 DOI: 10.1016/j.jvsv.2017.03.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 03/22/2017] [Indexed: 11/29/2022]
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Lee KG, Tan CS, Tan RY, Pang SC, Li H, Goh N, Achudan S, Tan YL, Choong HL, Chong TT. MP660A PREDICTOR SCORING SYSTEM FOR PRIMARY ARTERIOVENOUS FISTULA SUCCESS IN MULTIETHNIC ASIAN HEMODIALYSIS PATIENTS. Nephrol Dial Transplant 2017. [DOI: 10.1093/ndt/gfx178.mp660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Teh SP, Tan RY, Liu PY, Ng CY, Lee KG, Pang SC, Tan CS. MP640PREDICTORS OF POOR VASCULAR ACCESS PATENCY AFTER ENDOVASCULAR THROMBECTOMY. Nephrol Dial Transplant 2017. [DOI: 10.1093/ndt/gfx178.mp640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Lee KG, Tan CS, Tan RY, Pang SC, Li H, Goh N, Achudan S, Tan YL, Choong HL, Chong TT. MP659AN EXTERNAL VALIDATION OF FAILURE TO MATURATION RISK EQUATION IN PRIMARY ARTERIOVENOUS FISTULAS IN MULTIETHNIC ASIAN HEMODIALYSIS PATIENTS. Nephrol Dial Transplant 2017. [DOI: 10.1093/ndt/gfx178.mp659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Pang SC, Chiang LP, Tan CH, Vythilingam I, Lam-Phua SG, Ng LC. Low efficacy of delthamethrin-treated net against Singapore Aedes aegypti is associated with kdr-type resistance. Trop Biomed 2015; 32:140-150. [PMID: 25801264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
There has been a worldwide surge in the number and severity of dengue in the past decades. In Singapore, relentless vector control efforts have been put in to control the disease since the 1960's. Space spraying, fogging, chemical treatment and source reduction are some commonly used methodologies for controlling its vectors, particularly Aedes aegypti. Here, as we explored the use of a commercially available delthamethrin-treated net as an alternative strategy and the efficacy of the treated net was found to be limited. Through bioassays and molecular studies, the failure of the treated net to render high mortality rate was found to be associated with the knockdown resistance (kdr) mutation. This is the first report of kdr- mutations in Singapore's Ae. aegypti. At least one point mutation, either homozygous or heterozygous, at amino acid residue V1016G of DIIS6 or F1269C of DIIIS6 was detected in 93% of field strains of Ae. aegypti. Various permutations of wild type and mutant amino acids of the four alleles were found to result in varying degree of survival rate among local field Ae. aegypti when exposed to the deltamethrin treated net. Together with the association of higher survival rate with the presence of both V1016G and F1269C, the data suggest the role of these mutations in the resistance to the deltamethrin. The high prevalence of these mutations were confirmed in a country wide survey where 70% and 72% of the 201 Ae. aegypti analysed possessed the mutations at residues 1016 and 1269 respectively. The highest mutated frequency combination was found to be heterozygous alleles (VG/FC) at both residues 1016 and 1269 (37.8%), followed by homozygous mutation at allele 1269 (24.4%) and homozygous mutation at allele 1016 (22.9%). The kdr- type of resistance among the vector is likely to undermine the effectiveness of pyrethroids treated materials against these mosquitoes.
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Kaupp JA, Tse MY, Pang SC, Kenworthy G, Hetzler M, Waldman SD. The effect of moving point of contact stimulation on chondrocyte gene expression and localization in tissue engineered constructs. Ann Biomed Eng 2013; 41:1106-19. [PMID: 23417513 DOI: 10.1007/s10439-013-0763-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2012] [Accepted: 02/11/2013] [Indexed: 11/29/2022]
Abstract
Tissue engineering is a promising approach for articular cartilage repair. However, using current technologies, the developed engineered constructs generally do not possess an organized superficial layer, which contributes to the tissue's durability and unique mechanical properties. In this study, we investigated the efficacy of applying a moving point of contract-type stimulation (MPS) to stimulate the production of a superficial-like layer in the engineered constructs. MPS was applied to chondrocyte-agarose hydrogels at a frequency of 0.5, 1 or 2 Hz, under a constant compressive load of 10 mN for durations between 5 and 60 min over 3 consecutive days. Expression and localization of superficial zone constituents was conducted by qRT-PCR and in situ hybridization. Finite element modeling was also constructed to gain insight into the relationship between the applied stimulus and superficial zone constituent expression. Gene expression of superficial zone markers were affected in a frequency dependent manner with a physiologic frequency of 1 Hz producing maximal expression of PRG4, biglycan, decorin and collagen II. In situ hybridization revealed that localization of these markers predominantly occurred at 500-1000 μm below the construct surface which correlated to sub-surface strains between 10 and 25% as determined by finite element modeling. These results indicate that while mechanical stimuli can be used to enhance the expression of superficial zone constituents in engineered cartilage constructs, the resultant subsurface loading is a critical factor for localizing expression. Future studies will investigate altering the applied stimulus to further localize superficial zone constituent expression at the construct surface.
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Lee AW, Farnquist B, Islam O, Mackenzie J, Taylor SAM, Pang SC, Reifel CW. Noninvasive investigation of asymmetrically conjoined tripus twins with features of rachipagus, parapagus dicephalus, and cephalopagus. Clin Anat 2011; 25:1023-9. [PMID: 21433086 DOI: 10.1002/ca.21149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 01/17/2011] [Accepted: 01/18/2011] [Indexed: 11/09/2022]
Abstract
A hypothetical mechanism for conjoined twinning postulated by Spencer ([2003] Developmental Malformations and Clinical Implications, Baltimore: Johns Hopkins University Press, p 1-476) suggests that, after separation, monovular twins fuse in one of eight predictable homologous sites. The tripus fetal specimen under study embodies characteristics of three types therefore preventing it from classification into a simple variant of any one of the eight twin types described by Spencer. The aim of this study was to reveal internal structural anomalies of the fetal specimen by using magnetic resonance imaging and computerized tomography. Dorsally appended to the primary twin is a secondary head mass (brain tissue and ocular globe) and two spinal columns converging at T4/T5, suggesting rachipagus twinning. The ventral orientation of the secondary twin's (right lateral) lower limb suggests parapagus twinning. The caudal divergence of the spinal columns and the presence of a secondary hemipelvis, separate from the primary pelvis, suggest cephalopagus twinning. Measurements of the long bones indicate a gestational age of ∼20-23 weeks. Secondary malformations of the primary fetal body include anencephaly, cleft palate, renal agenesis, decreased left ventricular outflow, and a prematurely terminating descending aorta. This study demonstrates the possibility of using current imaging techniques to study very old, formalin-preserved human material for documentation and scientific discussion without destroying the specimen, thus keeping it intact for posterity.
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O'Tierney PF, Angelis E, Tse MY, Pang JJ, Adams MA, Pang SC. A potential role for the endothelin ETA receptor in salt-sensitive hypertension of the proANP gene-disrupted mouse. Mol Cell Biochem 2006; 275:57-66. [PMID: 16335784 DOI: 10.1007/s11010-005-7716-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We have previously shown that the partial disruption of the gene for atrial natriuretic peptide (ANP) results in a salt-sensitive phenotype. The present study examined the possibility that alterations in either the ANP natriuretic pathway or endothelin (ET) system in the kidney of the salt-challenged ANP +/- mouse was responsible for its salt-sensitive phenotype. Plasma ANP levels and renal cGMP activity were increased in response to a salt load in both ANP +/+ and +/- mice. However, the mRNA expression of proANP was found to be increased only in the ANP +/- kidney along with its guanylyl cyclase-linked receptor, NPRA; the upregulation of NPRA mRNA was limited to the renal medulla. This suggests that the renal ANP pathway remains capable of responding to a salt load in the ANP +/- animal, but may be compensating for other dysfunctional pathways. We also report a significant increase in renal ET-1 mRNA and ETA receptor protein expression in medulla and cortex of the salt-treated, ANP +/- mouse, but not its wild-type counterpart. In fact, ETA expression decreased in the renal cortex of the ANP +/+ salt-treated animal. The ETB receptor expression was not affected by diet in either genotype. We hypothesize that the salt-sensitive hypertension in the ANP +/- mouse is exacerbated, and possibly driven by the vasoconstrictive effects resulting from an upregulated ET-1/ETA pathway.
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Reid A, de Klerk N, Ambrosini GL, Olsen N, Pang SC, Berry G, Musk AW. The effect of asbestosis on lung cancer risk beyond the dose related effect of asbestos alone. Occup Environ Med 2006; 62:885-9. [PMID: 16299098 PMCID: PMC1740938 DOI: 10.1136/oem.2005.020834] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIMS To determine if the presence of asbestosis is a prerequisite for lung cancer in subjects with known exposure to blue asbestos (crocidolite). METHODS Former workers and residents of Wittenoom with known amounts of asbestos exposure (duration, intensity, and time since first exposure), current chest x ray and smoking information, participating in a cancer prevention programme (n = 1988) were studied. The first plain chest radiograph taken at the time of recruitment into the cancer prevention programme was examined for radiographic evidence of asbestosis according to the UICC (ILO) classification. Cox proportional hazards modelling was used to relate asbestosis, asbestos exposure, and lung cancer. RESULTS Between 1990 and 2002 there were 58 cases of lung cancer. Thirty six per cent of cases had radiographic evidence of asbestosis compared to 12% of study participants. Smoking status was the strongest predictor of lung cancer, with current smokers (OR = 26.5, 95% CI 3.5 to 198) having the greatest risk. Radiographic asbestosis (OR = 1.94, 95% CI 1.09 to 3.46) and asbestos exposure (OR = 1.21 per f/ml-year, 95% CI 1.02 to 1.42) were significantly associated with an increased risk of lung cancer. There was an increased risk of lung cancer with increasing exposure in those without asbestosis. CONCLUSION In this cohort of former workers and residents of Wittenoom, asbestosis is not a mandatory precursor for asbestos related lung cancer. These findings support the hypothesis that it is the asbestos fibres per se that cause lung cancer, which can develop with or without the presence of asbestosis.
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Reid A, de Klerk N, Ambrosini G, Olsen N, Pang SC, Musk AW. The additional risk of malignant mesothelioma in former workers and residents of Wittenoom with benign pleural disease or asbestosis. Occup Environ Med 2005; 62:665-9. [PMID: 16169910 PMCID: PMC1740875 DOI: 10.1136/oem.2004.018531] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AIMS To examine the hypothesis that people with benign pleural disease or asbestosis have an increased risk of malignant mesothelioma beyond that attributable to their degree of asbestos exposure. METHODS Former workers and residents of the crocidolite mining and milling town of Wittenoom are participating in a cancer prevention programme (n = 1988). The first plain chest radiograph taken at the time of recruitment into the cancer prevention programme was read for evidence of benign pleural disease and asbestosis, using the UICC classification. Crocidolite exposure of former workers was derived from employment records and records of dust measurements performed during the operation of the asbestos mine and mill between 1943 and 1966. Based on fibre counts, exposure for former residents was determined using duration of residence and period of residence (before and after a new mill was commissioned in 1957) and interpolation from periodic hygienic measures undertaken from personal monitors between 1966 and 1992. Cox proportional hazards modelling was used to relate benign pleural disease, asbestosis, asbestos exposure, and mesothelioma. RESULTS Between 1990 and 2002, there were 76 cases of mesothelioma (56 of the pleura and 20 of the peritoneum). Cases had more radiographic evidence of (all) benign pleural disease, pleural thickening, blunt/obliterated costophrenic angle, and asbestosis than non-cases. Adjusting for time since first exposure (log years), cumulative exposure (log f/ml-years), and age at the start of the programme, pleural thickening (OR = 3.1, 95% CI 1.2 to 7.6) and asbestosis (OR = 3.3, 95% CI 1.3 to 8.6) were associated with an increased risk of peritoneal mesothelioma. There was no increased risk for pleural mesothelioma. CONCLUSION The presence of benign pleural disease, in particular pleural thickening, and asbestosis appears to increase the risk of mesothelioma of the peritoneum, but not of the pleura beyond that attributable to indices of asbestos exposure in this cohort of subjects exposed to crocidolite.
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Lee YCG, Singh B, Pang SC, de Klerk NH, Hillman DR, Musk AW. Radiographic (ILO) readings predict arterial oxygen desaturation during exercise in subjects with asbestosis. Occup Environ Med 2003; 60:201-6. [PMID: 12598668 PMCID: PMC1740487 DOI: 10.1136/oem.60.3.201] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Exercise impairment is common in subjects with asbestosis. Arterial oxygen desaturation during exercise is an important contributor to exercise limitation. The International Labour Office (ILO) classification of plain chest radiographs correlates with resting pulmonary function, but its value in predicting abnormal ventilatory responses to exercise, including desaturation, has not been explored. AIMS To determine in subjects with asbestosis (1) if radiographic profusion scores and the extent of small irregular shadows on plain chest radiographs correlate with resting lung function and abnormal ventilatory responses to exercise; and (2) if radiographic scores add value to resting lung function tests in predicting abnormal ventilatory responses to exercise. METHODS Thirty eight male subjects with asbestosis were included. Plain chest radiographs were read according to the ILO classification independently by three observers. All subjects underwent assessment of lung function and an incremental exercise test. RESULTS Profusion scores and number of affected zones correlated significantly with the percentage predicted values of single breath diffusing capacity (DLCO), forced vital capacity (FVC), and total lung capacity (TLC). Arterial oxygen desaturation occurred in 29% of the subjects. The severity of desaturation correlated significantly with profusion and the number of affected zones. The combined use of number of affected zones, FEV(1)/FVC ratio and DLCO predicted desaturation during exercise with an explained variance of 41%. VO(2)max was significantly related only to DLCO but was not predicted by the ILO score. CONCLUSION Arterial oxygen desaturation correlated with the profusion and extent of parenchymal abnormality on chest radiographs. The addition of morphological indices to physiological measurements is valuable for predicting oxygen desaturation during exercise but not for VO(2)max. Refinement of the radiographic scoring system and the addition of more sophisticated imaging techniques may further improve the predictive power.
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De Klerk NH, Ambrosini GL, Pang SC, Musk AW. Silicosis compensation in Western Australian gold miners since the introduction of an occupational exposure standard for crystalline silica. THE ANNALS OF OCCUPATIONAL HYGIENE 2002; 46:687-92. [PMID: 12406862 DOI: 10.1093/annhyg/mef088] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
UNLABELLED Occupational exposure limits for crystalline silica are under review worldwide because of the large numbers of exposed people and, especially, because of the recent International Agency for Research on Cancer classification of silica as a human carcinogen. OBJECTIVES The aims of this study were to (i) re-examine the incidence of silicosis in Western Australian gold miners and, using estimates of the total population at risk, (ii) estimate the upper confidence limit for the risk of silicosis in Western Australian gold miners since 1974, when the current exposure standard for crystalline silica was implemented. METHODS Work histories of cases compensated for pneumoconiosis after 1974 were examined. Numbers of workers in the total workforce likely to be exposed to crystalline silica in Western Australia were estimated as the population at risk. RESULTS There were no cases of compensated silicosis in Western Australian miners whose first dust exposure began during or after 1974. The upper 95% confidence interval for this zero rate was estimated to be 4.8 per 100,000 person-yr. CONCLUSIONS There have been no compensated cases of silicosis in Western Australia among miners first exposed to crystalline silica after introduction of the current exposure standard. A rate of compensated silicosis higher than five cases per 100,000 person-yr is unlikely.
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Situ D, Reifel CW, Smith R, Lyons GW, Temkin R, Harper-Little C, Pang SC. Investigation of a cyclopic, human, term fetus by use of magnetic resonance imaging (MRI). J Anat 2002; 200:431-8. [PMID: 12090389 PMCID: PMC1570717 DOI: 10.1046/j.1469-7580.2002.00053.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Using magnetic resonance imaging (MRI), the internal neural and craniofacial malformations of a cyclopic fetus are described. External facial features were characterized by a tubular proboscis situated above a single eye slit. The brain was recognized as 'pancake' type alobar holoprosencephaly (a condition where the undifferentiated telencephalon partially surrounds a monoventricle). Displacement of some bones that normally contribute to the orbit could be clearly discerned. Absence of neural structures (e.g. falx cerebri, corpus callosum) and missing components of the ethmoid bone indicated a midline deficit. This correlates with proposed theories of cyclopic embryopathy, which suggest that the prechordal plate and the neural crest cells are affected during the third week of gestation in cyclopia.
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Tse MY, Watson JD, Sarda IR, Flynn TG, Pang SC. Expression of B-type natriuretic peptide in atrial natriuretic peptide gene disrupted mice. Mol Cell Biochem 2001; 219:99-105. [PMID: 11354260 DOI: 10.1023/a:1011087513774] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) are two hormones produced and secreted by the heart to control blood pressure, body fluid homeostasis and electrolyte balance. Each peptide binds to a common family of 3 receptors (GC-A, GC-B and C-receptor) with varying degrees of affinity. The proANP gene disrupted mouse model provides an excellent opportunity to examine the regulation and expression of BNP in the absence ofANP. A new radioimmunoassay (RIA) was developed in order to measure mouse BNP peptide levels in the plasma, atrium and ventricle of the mouse. A detection limit of 3-6 pg/tube was achieved by this assay. Results show that plasma and ventricular level of BNP were unchanged among the three genotypes of mice. However, a significant decrease in the BNP level was noted in the atrium. The homozygous mutant (ANP-/-) had undetectable levels of BNP in the atrium, while the heterozygous (ANP+/-) and wild-type (ANP+/+) mice had 430 and 910 pg/mg in the atrium, respectively. Northern Blot analysis shows the ANP-/- mice has a 40% reduction of BNP mRNA level in the atrium and a 5-fold increase in the ventricle as compared with that of the ANP+/+ mouse. Our data suggest that there is a compensatory response of BNP expression to proANP gene disruption. Despite the changes in the atrial and ventricular tissue mRNA and peptide levels, the plasma BNP level remains unaltered in the ANP-/- mice. We conclude that the inability of BNP to completely compensate for the lack of ANP eventually leads to chronic hypertension in the proANP gene disrupted mice.
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Reifel CW, Lyons GW, Boyd S, Situ D, Temkin R, Pang SC. Thoracic stomach in a centenarian female cadaver. J Anat 2001; 198:505-7. [PMID: 11327214 PMCID: PMC1468238 DOI: 10.1046/j.1469-7580.2001.19840505.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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McDonough JL, Labugger R, Pickett W, Tse MY, MacKenzie S, Pang SC, Atar D, Ropchan G, Van Eyk JE. Cardiac troponin I is modified in the myocardium of bypass patients. Circulation 2001; 103:58-64. [PMID: 11136686 DOI: 10.1161/01.cir.103.1.58] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Selective proteolysis of cardiac troponin I (cTnI) is a proposed mechanism of contractile dysfunction in stunned myocardium, and the presence of cTnI degradation products in serum may reflect the functional state of the remaining viable myocardium. However, recent swine and canine studies have not demonstrated stunning-dependent cTnI degradation. METHODS AND RESULTS To address the universality of cTnI modification, myocardial biopsy samples were obtained from coronary artery bypass patients (n=37) before and 10 minutes after removal of cross-clamp. Analysis of biopsy samples for cTnI by Western blotting revealed a spectrum of modified cTnI products in myocardium both before and after cross-clamp, including degradation products (7 products resulting from differential N- and C-terminal processing) and covalent complexes (3 products). In particular, a 22-kDa cTnI degradation product with C-terminal proteolysis was identified, which may represent an initial ischemia-dependent cTnI modification, similar to cTnI(1-193) observed in stunned rat myocardium. Although no systematic change in amount of modified cTnI was observed, subgroups of patients displayed an increase (n=10, 85+/-5% of cTnI remaining intact before cross-clamp versus 75+/-5% after) or a decrease (n=12, 67+/-5% before versus 78+/-5% after). Electron microscopy demonstrated normal ultrastructure in biopsy samples, which suggests no necrosis was present. In addition, cTnI modification products were observed in serum through a modified SDS-PAGE methodology. CONCLUSIONS cTnI modification, in particular proteolysis, occurs in myocardium of bypass patients and may play a key role in stunning in some bypass patients.
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Lee YC, Runnion CK, Pang SC, de Klerk NH, Musk AW. Increased body mass index is related to apparent circumscribed pleural thickening on plain chest radiographs. Am J Ind Med 2001; 39:112-6. [PMID: 11148021 DOI: 10.1002/1097-0274(200101)39:1<112::aid-ajim11>3.0.co;2-g] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Diffuse pleural thickening and pleural plaques are the commonest radiological manifestations of asbestos exposure. Differentiation between subpleural fat and non-calcified pleural plaques is important clinically and medico-legally. This study aims to determine if apparent circumscribed pleural thickening on chest radiographs is related with obesity. METHODS Surveillance chest x-rays of 693 former asbestos workers were read with the ILO classification. Subjects with costophrenic angle obliteration (n = 57) were analyzed separately. The remaining subjects were subdivided according to their body mass index (BMI): Group 1 < 26 kg/m(2); Group 2 26-30 kg/m(2); Group 3 > 30 kg/m(2). RESULTS Baseline characteristics, asbestos exposure, and profusion scores were evenly distributed. BMI of > 30 kg/m(2) was associated with a higher prevalence of pleural thickening on CXR (Gp1 = 8.5%; Gp2 = 9.3%; Gp3 = 18.3%). This relationship was strongest in the subgroups with 25-50% of the lateral chest wall involved and pleural thickness of < 10 mm. CONCLUSIONS Obesity (BMI > 30 kg/m(2)) is related to apparent circumscribed pleural thickening on CXR, especially thin (< 1 cm) shadows covering 25-50% of the lateral chest wall.
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Mukherjee S, de Klerk N, Palmer LJ, Olsen NJ, Pang SC, William Musk A. Chest pain in asbestos-exposed individuals with benign pleural and parenchymal disease. Am J Respir Crit Care Med 2000; 162:1807-11. [PMID: 11069817 DOI: 10.1164/ajrccm.162.5.9912012] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Many asbestos-exposed individuals complain of chest pain for which there is no clear explanation. To determine whether chest pain is associated with the presence of benign pleural or parenchymal disease on chest radiograph, we studied 1,280 subjects undergoing surveillance because of prior asbestos exposure at Wittenoom, Western Australia. All subjects completed the Rose questionnaire on chest pain and this revealed 556 subjects (43%) who experienced some chest pain. A posterior-anterior chest radiograph was performed at the same clinic visit and was subsequently graded independently by two experienced readers for diffuse parenchymal disease and pleural disease. Logistic regression models adjusted for sex, age, and cumulative asbestos exposure indicated that the presence of chest pain was significantly associated with the presence of both benign pleural disease and diffuse parenchymal disease. Further analysis after stratification of chest pain into nonanginal and anginal pain showed that there was a significant association between anginal pain and the presence of pleural and parenchymal asbestos-induced radiologic abnormalities and an association of nonanginal pain with parenchymal disease. We conclude that radiographic evidence of either parenchymal or pleural disease in subjects exposed to asbestos is significantly related to the presence of chest pain, particularly anginal pain.
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