Browsing by Author "Weerasinghe, M"

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Embargo
Brewing plastics: OCT reveals microplastic release from nylon tea bags in simulated brewed tea infusions
(Royal Society of Chemistry, 2026-02-12) Jayasekara, P.M; Abhishek, P; Kahandawala,B.S; Damith, N; Weerasinghe, M; Kahatapitiya, N.S; Silva, B.N; Karunaratne, S; Wijesinghe, R.E; Wijenayake, U
The release of microplastics (MPs) from nylon tea bags poses a critical concern for human exposure; however,their detection and quantification remain challenging especially in beverage matrices, and hence, this study pioneers the use of high-resolution optical coherence tomography (OCT) integrated with an image processing algorithm to rapidly detect and quantify the size and count of the MPs directly in the water extractions simulating tea brewing. The water extractions prepared by simulating tea brewing conditions, hot (100 °C, 1–5min), cold (2 °C, 1 h), and ambient (30 °C, 1 h), were observed employing OCT imaging and validated through Nile Red (NR) staining and digital microscopy. The nylon tea bags steeped in hot water for 5 minutes released 16 000 to 24 000 LMPs (>30 mm) and SMPs (12–30 mm) per millilitre. The estimated daily intake (EDI) of MPs indicates a higher exposure for children (ranging from 0.201 to 0.349 mm3 kg−1 day−1 ) compared to adults (0.046 to 0.080 mm3 kg−1 day−1 ). In contrast, cold brewing for 1 hour released fewer LMPs but an equal quantity of small MPs (SMPs) compared to hot brewing. This OCT-based approach offers a rapid, versatile platform for the detection and quantification of MPs from diverse packaging materials and provides a powerful tool for comprehensive risk assessment when combined with chemical and toxicological analyses.
Embargo
Environmental forensics of the X-press pearl disaster: Uncovering the internal micro-structural transformations in marine microplastics
(Elsevier B.V., 2025-07-15) Jayasekara, P.M; Abhishek, P; Kahatapitiya, N. S; Weerasinghe, M; Kahandawala, B. S; Silva, B. N; Wijenayake, U; Rajapaksha, A.U; Wijesinghe, R. E; Vithanage, M
The MV X-Press Pearl (XPP) maritime disaster on May 25, 2021, released approximately 75 billion microplastic (MP) nurdles into the Indian Ocean and degraded due to the elevated temperatures, a cocktail of chemicals, physical abrasions, and environmental factors. While degradation-induced surface-level chemical and morphological changes were well documented, internal degradation remains largely unexplored. This study highlights the utilization of high-resolution optical coherence tomography (OCT) as a purely non-destructive imaging modality to discover profound internal alterations in the micrometer range, such as internal hollow regions, cracks, and voids in MP nurdles subjected to different degrees of degradation. The dark pixel intensity probability density corresponds to the degraded areas, increased from 0.0019 (pristine nurdle) to 0.0135–0.5252 for thermal degradation, 0.0878–0.3134 for chemical degradation, and 0.1291–0.2179 for mechanical degradation, indicating progressive internal degradation. Attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy analysis confirmed that all the nurdles are polyethylene (PE) and revealed that extreme conditions lead to the formation of new functional groups, including hydroxyl bands and carbonyl bands, even though PE is highly resistant to degradation. The integration of high-resolution OCT imaging with FTIR analysis provides novel insights into the interconnection between micrometer-scale internal physical alterations and associated chemical modifications of MP nurdles resulting from environmental degradation. These findings highlight the potential of this OCT-FTIR integrated approach for advancing the understanding of MP degradation and its long-term environmental impacts.
Open Access
In Silico Analysis of the Diversity of DPYD Gene Variants Aff ecti ng Fluoropyrimidine Toxicity: A Comparison of South Asians with Other World Populati ons
(Faculty of Humanities and Sciences, SLIIT, 2024-12-04) Perera, N; Weerasinghe, M; Kasturiarachchi, J; Ranasinghe, P
Fluoropyrimidine (FP) chemotherapy drug is uti lized to treat colon, head, neck and breast cancers. Apart from its eff ecti veness, toxicity is a limitati on. DPD (dihydropyrimidine dehydrogenase) enzyme, which aids in the FP metabolism is produced by the highly polymorphic DPYD gene. Mutati ons in the DPYD gene cause the defi ciency or non-functi onality of the DPD enzyme which varies among diff erent populati ons. This research aimed to compare allele frequencies of common DPYD gene variants of South Asians (SAS) such as DPYD*2A(rs3918290), DPYD*9(rs1801265), DPYD*5, rs2297595, DPYD*6, rs17376848, rs56038477, DPYD*4(rs1801158), rs67376798 and rs75017182 with Africans (AFR), Amish (AMI), Lati n Americans (AMR), Ashkenazi Jewish (ASJ), East Asians (EAS), Finnish (FIN) and Non-Finnish (NFE). Allele frequencies were obtained from the Genome Aggregati on Database in the PharmGKB database. Χ² analysis was performed. p<0.05 was deemed to be stati sti cally signifi cant. The study found a signifi cant diff erence between the SAS populati on and AFR, AMR, ASJ, EAS, FIN and NFE populati ons for the DPYD*9A gene variant, except for the AMI populati on. The distributi on of the DPYD*2A gene variant of SAS was found to be signifi cant in the AFR, ASJ, FIN and NFE populati ons, except for AMR and AMI. The prevalence of DPYD*5, DPYD*6, rs17376848, and rs56038477 in the SAS signifi cantly diff ered from all above-menti oned populati ons. The distributi on of the rs75017182 gene variant in SAS has shown signifi cant diff erences with AFR, AMR, ASJ and EAS except for NFE and FIN. This study highlights the variati ons in pharmacogenomics data specifi c to populati ons that could lead to personalized medicine and the need for DPYD genotyping before cancer treatment, especially in SAS communiti es where clinically signifi cant geneti c variati ons and haplotypes occur. Study fi ndings pinpoint the potenti al contributi on of DPYD gene variati ons to individual variability in anti -cancer dosage requirements among SAS.
Open Access
A Study on the Diversity of Pharmacogenomic Variants Aff ecti ng Dapsone Hypersensiti vity: A Comparati ve Study Based on South Asian and Other World Populati ons
(Faculty of Humanities and Sciences, SLIIT, 2024-12-04) Weerasinghe, M; Perera, N; Kasthuriarachchi, J; Ranasinghe, P
Recent data from Sri Lanka indicates an increase in leprosy cases, emphasizing the necessity of dapsone as a drug vital for managing it. Ironically, dapsone eff ecti veness is accompanied by dapsone hypersensiti vity syndrome (DHS) which varies among populati ons. We postulate that this is due to signifi cant diff erences between SNP frequencies in HLA-B*13:01, CYP2C9*3, rs701829, rs17211071, and rs201929247. As per our reading, no comparati ve study has been done so far on DHS and related genes between South Asian (SAS) and other world populati ons. Therefore, this study compares the allele frequencies of SNPs from PharmGKB and dbSNP of world populati ons against SAS using chisquare (χ²) tests. For HLA-B*13:01; it is reported that Europeans, Africans, African others, and African Americans have demonstrated signifi cant diff erences, and Asians, EAS, Other Asians, and Lati n Americans have shown no signifi cant diff erences. For CYP2C9*3 and rs701829; Americans, Africans, Amish, Ashkenazi Jews, East Asians (EAS), Finns, and Non-Finnish Europeans (NFE) all have demonstrated a signifi cant diff erence from SAS. For rs17211071, Africans, Amish, Americans, East Asians, Finns, and NFE demonstrated no signifi cant diff erence, and ASJ showed a signifi cant diff erence. For rs201929247, Africans and Finns had no signifi cant diff erences, whereas Americans, Amish, ASJ, EAS, and NFE had. Hence, compared with other populati ons, allele frequencies of some studied SNPs were signifi cantly diff erent in SAS, and these may likely account for the variability of DHS occurrence among these populati ons. Signifi cant allele frequency diff erences between SAS and the rest of the world populati ons’ impact personalized medicine in leprosy treatment. Clinical research needs to determine the opti mal dapsone dose alterati ons, considering environmental and other factors behind DHS.