Conference Papers
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This collection contains abstracts of conference papers, presented at local and international conferences by the staff of the Faculty of Medicine
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Item Heart rate variability among gas station attendants exposed to benzene, toluene, and xylenes (BTX) in Sri Lanka(Springer Nature., 2021) Warnakulasuriya, T.; Medagoda, K.; Kottahachchi, D.; Luke, D.; Wadasinghe, D.; de Silva, D.; Ariyawansha, J.; Rathnayaka, P.; Dissanayaka, T.; Fernando, S.; Devanarayana, N.M.; Scheepers, P.T.J.Introduction: Benzene, toluene, and xylenes (BTX) exposure among gas station attendants in Sri Lanka is high. Cardiovascular morbidity and mortality are reported to be higher among those exposed to BTX. A hypothesis is based on alterations in the autonomic nervous system, especially disruption of autonomic regulation of the heart. Autonomic regulation of cardiac functions can be assessed by short-term heart rate variability (HRV), which measures the fluctuations in the interval between sequential sinus heartbeats. Objective: To determine whether BTX exposure affects the heart rate variability (HRV) among gas station attendants. Methods: Forty-nine gas station attendants from the Gampaha district of Sri Lanka, aged between 19 and 65 years, were recruited for the study. Age and gender-matched controls (n = 46) without occupational exposure to fuel were used as controls. Ethical approval for the study was granted by the Ethics Review Committee of the Faculty of Medicine, University of Kelaniya, Sri Lanka. Informed written consent was obtained from each participant. Demographic data were collected, and a physical examination was performed before the HRV assessment. We measured SDNN, RMSSD, pNN50, HF, LF, and LF: HF ratio as HRV indices. Pre- and post-shift samples of end-exhaled air were collected and analyzed for BTX using a thermal desorption gas chromatography–mass spectrometry system (TD-GC-MS) among 24 gas station attendants and 14 controls. As a proxy of shift exposure, we calculated the increase from pre-shift (as a baseline) to postshift and reported this as ‘delta’. Results and discussion: For gas station attendants (n = 24) median pre-/post-shift exhaled air concentrations (ng/L) were: benzene 10.47/ 19.00; toluene 10.41/21.86; m/p-xylene 1.63/2.14; o-xylene 0.93/1.42. For controls (n = 14) these values were 9.40/11.05, 3.19/3.91, 1.23/ 1.43 and 0.47/0.47. The heart rate variability (HRV) analysis showed significantly higher SDNN and SD2 among the gas station attendants (n = 49) than controls (n = 46) (Mann Whitney U = 842.00, p = 0.034 and Mann Whitney U = 843.50, p = 0.035, respectively). RMSSD, pNN50, Total power, HF, and SD1 among gas station attendants negatively correlated at a significant level with the mean increment in exposure to BTX (p\0.05).Conclusions: Exposure to BTX alters the HRV indices, indicating an effect on autonomic cardiac regulation. Funding: University of Kelaniya research grant: RP/03/04/03/01/ 2017, Foreign Award 2017 of the Dutch Occupational Hygiene Society (NVvA).Item Cardiovascular autonomic functions of gas station attendants in Sri Lanka(Springer Nature., 2021) Warnakulasuriya, T.; Medagoda, K.; Kottahachchi, D.; Luke, D.; Wadasinghe, D.; de Silva, D.; Ariyawansha, J.; Rathnayaka, P.; Dissanayaka, T.; Fernando, S.; Devanarayana, N.M.Introduction: Sri Lanka, a middle-income country in South Asia, has seen a rapid expansion in motor vehicles and, associated with this, an increase in demand for fuel. The dispensing of fuel at fuel stations is performed manually by male fuel handlers, who have long working hours. Such workers are exposed to hydrocarbon fuels which are associated with multiple health effects. This study was performed to determine cardiovascular autonomic functions among fuel handlers in a densely populated district of Sri Lanka. Methods: Fuel handlers (n = 50) from the Gampaha district of Sri Lanka, aged between 19 and 65 years, were identified for the study from seven selected fuel stations. Age and gender-matched controls (n = 46) without occupational exposure to fuel were used as controls. All participants were male (females were not employed as fuel handlers). After obtaining written informed consent, demographic data were collected, and general physical examination performed before autonomic function assessment. Non-parametric methods were used for data analysis. Ethical approval was granted by the ethics review committee of the Faculty of Medicine, University of Kelaniya, Sri Lanka. Results: There were no significant differences in weight, height or BMI among the study and the control populations (p[0.05). Both the systolic (SBP) and diastolic (DBP) blood pressures were significantly higher among the fuel handlers compared to controls (SBP, Mann Whitney U = 743.5, p = 0.003) and (DBP, Mann Whitney U = 686.5, p = 0.001). Valsalva ratio was significantly higher among the fuel handlers (Mann Whitney U—874.00, p = 0.043). The rise in DBP during sustained handgrip, a sympathetic parameter, was significantly higher among the controls (Mann Whitney U = 863.00, p = 0.049). Conclusions: Altered sympathetic:parasympathetic balance was observed among the fuel handlers. Monitoring of the health, using personal protective equipment, and curtailing hours of employment per week is recommended for those employed at fuel stations.Item A Unique syndrome with facial, cranial, dental and skeletal features: possible relationship to maternal chikungunya exposure or an unidentified genetic cause?(Sri Lanka College of Paediatricians, 2015) de Silva, D.; Basnayake, S.; Gunasekara, R.; Smith, J. C.; Donnai, D.; Newman, B.BACKGROUND:Six children from the western province of Sri Lanka, born between June 2007 and November 2008 have presented with a unique phenotype comprising distinctive facial features, skeletal abnormalities and variable intellectual disability. In four children the mother reported a clinical history of chikungunya infection (CHKV) during their first trimester. OBJECTIVE: • Describe the clinical and demographic features of affected cases • Identify a genetic basis using whole exome sequencing (WES) DESIGN, SETTING AND METHOD: Cases were recruited following informed consent from parents. Blood taken for DNA extraction and WES performed using the lllumina HiSeq 2500 platform. Reads were aligned to the human reference sequence hg19 and analysed using bioinformatics software. RESULTS: Four cases were females. Five were Sinhalese, one Tamil. None had parental consanguinity. Four mothers reported first trimester CHKV infection. Distinctive facial features (pinched face, downslanting eyes, turri-brachvcephalv, open mouth, lip retraction, V shaped dental arches and high mandibular angles), restriction of joint movements (small and large joints) and variable developmental delay were present. Review by a panel of experts revealed no syndrome diagnosis WES analysis on five cases did not identify a homozygous or compound heterozygous recessive or de novo dominant mutation of an autosomal gene. CONCLUSIONS: WES analysis did not identify a homozygous or compound heterozygous recessive or de novo dominant mutation of an autosomal gene.Item Molecular diagnosis of velo-cardio-facial syndrome among sri lankan patients with congenital cardiac defects(Sri Lanka College of Paediatricians, 2015) Tevarajan, I.; Ranaweera, D. M.; Perera, S.; Samarasinghe, D.; Morawakkorala, R.; Silva, R. L.; de Silva, D.; Chandrasekharan, N.V.Velo cardio facial Syndrome (VCFS) is caused by a 3 Mb deletion of chromosome 22qll.2. Its multiple clinical features include orofacial clefting, congenital cardiac defects (especially conotruncal),developmental delay and learning difficulties. Hypoparathyroidism and thymic hypoplasia are associated. Dysmorphic features include expressionless face, prominent nose, narrow eyes and long fingers/ toes. Clinical diagnosis is difficult due to its variability making molecular diagnosis essential but this is often too expensive for widespread use. We have developed a less expensive semi-quantitative PCR method for diagnosing VCFS and report preliminary results in congenital cardiac defect patients.OBJECTIVE: • Identify the 22qll.2 deletion syndrome among a selected group of children with typical cardiac defects • Describe clinical features of affected cases DESIGN, SETTING AND METHOD: TweIve children (6 males, mean age 3y lmo) with conotruncal congenital cardiac anomalies or cardiac defects associated with other clinical feature of VCFS were .recruited following informed consent from parents. Ethical approval had been granted for this study. A blood sample was obtained for DNA extraction and the clinical data recorded. Molecular diagnosis was performed using semi-quantitative PCR. RESULTS: Three cases were positive for the deletion. Their cardiac anomalies were an interrupted aortic arch,tetralogy of Fallot and right sided aortic arch. None had palatal anomalies and two (67%) had learning difficulties. None had a positive family history. Only one had facies that were typical. The negative cases included six with aortic arch anomalies, none with clefting and 4 with learning difficulties(44). Two had a family history suggestive of VCFS and two had typical facial features. CONCLUSIONS: Three out of the 12 children were positive for the 22qll.2 deletion.Item Molecular diagnosis of Williams Buren syndrome in a cohort of Sri Lankan patients(Sri Lanka Medical Association, 2012) Ranaweera, D.M.; de Silva, D.; Samarasinghe, D.; Perera, S.; Rajapaksha, N.; Chandrasekharan, N.V.INTRODUCTION: Williams Bueren Syndrome (WBS) is a common genetic cause of congenital heart defects associated with developmental delay, hypercalcaemia and characteristic facial dysmorphism. It is caused by a 1.5 to 1.8 Mb deletion of chromosome 7qll.23 involving the loss of around 23 genes including the elastin (ELN) gene. This study reports the development of a semi quantitative PCR method to diagnose WBS. AIMS: To establish a molecular diagnostic test for WBS and determine the frequency of ELN deletions among clinically suspected cases. METHODS: Sixteen suspected WBS cases identified by two paediatric cardiologists were recruited following ethical clearance and informed consent. DNA was extracted and dosage analysis was carried out using semi-quantitative PCR. In a multiplex PCR reaction normal (N), positive control (with a confirmed deletion) and patients' (PJ DNA was amplified using 2 primer pairs which amplified regions within the ELN gene and the CFTR gene on chromosome 7 but outside the deleted region. Following agarose gel electrophoresis, the amplified products were quantified. A ratio of P:N of 0.5 indicated the presence of a deletion while a ratio of 1 indicated the absence of a deletion. RESULTS: Among sixteen suspected cases, 12 (75%) had an ELN gene deletion while 4 cases did not. CONCLUSIONS: This semi-quantitative PCR method was able to distinguish ELN deleted cases from the non deleted ones. The preliminary data supports this as a useful diagnostic test for WBS but validation is required before its clinical use.Item Molecular diagnosis of Velocardiofacial Syndrome in a cohort of Sri Lankan patients(Sri Lanka Medical Association, 2014) Thevarajan, I.; Ranaweera, D.M.; de Silva, D.; Prabodha, L.B.L.; Gunasekera, R.; Dias, D.K.; Nanayakkara, B.G.; Basnayake, S.; Jayathilake, M.; Chandrasekharan, N.V.INTRODUCTION AND OBJECTIVES: Velocardiofacial Syndrome (VCFS) is caused by a 3 Mb deletion encompassing around 40 genes on chromosome 22qll.2. It is characterised by variable features including congenital malformations of the palate and heart, growth and developmental delay, immunological anomalies, hypocalcaemia and other problems. Clinical diagnosis is difficult due to its variability within and between families. Early diagnosis enables appropriate management of the affected cases. Objective was to establish a reliable and cost effective molecular diagnostic test for VCFS. METHODS: Nineteen clinically suspected patients with palatal and facial features suggestive of VCFS from Lady Ridgeway Hospital, Colombo and the Teaching hospital, Karapitiya were recruited following informed consent and prior ethical clearance. A semi-quantitative multiplex poiymerase chain reaction (PCR) was established to identify the deletion using dosage analysis. The PCR assay was carried out using DNA from patients (P), unaffected person (N) and a positive control (with a FISH confirmed deletion} using STS markers within the deleted region and CFTR (Cystic Fibrosis Transmembrane Regulatory Conductance) control primers outside the deleted region. Following agarose gel electrophoresis the PCR products were quantified. A ratio of P: N of 0.5 was taken to indicate a deletion while a ratio of 1 indicated absence of the deletion. RESULTS: Among nineteen clinically suspected VCFS cases, five cases had the deletion. CONCLUSIONS: This semi-quantitative PCR assay was able to identify.deletions in clinically suspected patients. However further validation is required before its clinical usage.