Radiofrequency ablation for shoulder pain: an updated systematic review.

BACKGROUND: Radiofrequency ablation (RFA) is a treatment modality that has been increasingly used for the management of chronic shoulder pain. Serious conditions that can identified as the cause of chronic shoulder pain include rotator cuff disorders, adhesive capsulitis, osteoarthritis, glenohumeral instability, and acromioclavicular joint disorders. Treatment of chronic shoulder pain typically consists of physical therapy, oral and topical medications, intra-articular corticosteroid injections, and even surgery. The aim of this study was to examine the most recent primary and secondary outcomes of RFA for chronic shoulder pain. METHODS: A systematic review was conducted using three different databases including PubMed, MEDLINE, and the Cochrane Database. The key concepts of "radiofrequency ablation" and "shoulder pain" were used. The search took place in June 2023, and it included articles from the past 20 years. RESULTS: Of the 396 articles found, 29 were included in the review. Most studies focused on reduction in pain scores, duration of relief, function, and patient satisfaction. In several studies, RFA was compared to conservative options such as physical therapy or corticosteroid injections. CONCLUSIONS: Overall, RFA shows positive outcomes in terms of the management of chronic shoulder pain. Therefore, RFA can serve as another treatment option for patients who fail conservative management or are not strong surgical candidates. Understanding the outcomes of RFA for chronic shoulder pain can provide patients and clinicians with evidence for the most appropriate treatment.

Distribution models of baleen whale species in the Irish Exclusive Economic Zone to inform management and conservation.

Irish waters are under increasing pressure from anthropogenic sources including the development of offshore renewable energy, vessel traffic and fishing activity. Spatial planning requires robust datasets on species distribution and the identification of important habitats to inform the planning process. Despite limited survey effort, long-term citizen science data on whale presence are available and provide an opportunity to fill information gaps. Using presence-only data as well as a variety of environmental variables, we constructed seasonal ensemble species distribution models based on five different algorithms for minke whales, fin whales, humpback whales, sei whales, and blue whales. The models predicted that the coastal waters off the south and west of Ireland are particularly suitable for minke, fin and humpback whales. Offshore waters in the Porcupine Seabight area were identified as a relevant habitat for fin whales, sei whales and blue whales. We combined model outputs with data on maritime traffic, fishing activity and offshore wind farms to measure the exposure of all the species to these pressures, identifying areas of concern. This study serves as a baseline for the species presence in Irish waters over the last two decades to help develop appropriate marine spatial plans in the future.

Variation in Paramarteilia canceri infections in velvet crab Necora puber.

Sustainable management of crustacean populations requires an understanding of the range of factors affecting different crustacean species. Recently, a high prevalence of a paramyxid parasite, Paramarteilia canceri, was reported in velvet crabs Necora puber in Ireland. Similar parasites have been known to cause mass mortalities in bivalves and, as velvet crabs are an important commercial species, these parasite infections are cause for concern. The main objective of this study was to examine variation in P. canceri infections in relation to host biology and season over a 2 yr period. In addition, we tested a range of host tissues and organs to gain more information on the host-parasite interaction. The parasite was present in all tissues and organs investigated, including the gonad and eggs of a berried female. Parasite prevalence was highest in the cuticular epithelium and hepatopancreas. Both annual and seasonal variation was found in parasite prevalence and parasite load. No difference was found in parasite prevalence or parasite load with either crab size or crab sex. Granulomas as a response to infection were significantly more abundant in infected velvet crab individuals. The results of this study provide important information on the host-parasite interaction between P. canceri and the velvet crab and highlight the importance of including parasite monitoring in the management of crustacean fisheries.

Reconfigurable Multifunctional van der Waals Ferroelectric Devices and Logic Circuits.

Emerging reconfigurable devices are fast gaining popularity in the search for next-generation computing hardware, while ferroelectric engineering of the doping state in semiconductor materials has the potential to offer alternatives to traditional von-Neumann architecture. In this work, we combine these concepts and demonstrate the suitability of reconfigurable ferroelectric field-effect transistors (Re-FeFETs) for designing nonvolatile reconfigurable logic-in-memory circuits with multifunctional capabilities. Modulation of the energy landscape within a homojunction of a 2D tungsten diselenide (WSe2) layer is achieved by independently controlling two split-gate electrodes made of a ferroelectric 2D copper indium thiophosphate (CuInP2S6) layer. Controlling the state encoded in the program gate enables switching between p, n, and ambipolar FeFET operating modes. The transistors exhibit on-off ratios exceeding 106 and hysteresis windows of up to 10 V width. The homojunction can change from Ohmic-like to diode behavior with a large rectification ratio of 104. When programmed in the diode mode, the large built-in p-n junction electric field enables efficient separation of photogenerated carriers, making the device attractive for energy-harvesting applications. The implementation of the Re-FeFET for reconfigurable logic functions shows how a circuit can be reconfigured to emulate either polymorphic ferroelectric NAND/AND logic-in-memory or electronic XNOR logic with a long retention time exceeding 104 s. We also illustrate how a circuit design made of just two Re-FeFETs exhibits high logic expressivity with reconfigurability at runtime to implement several key nonvolatile 2-input logic functions. Moreover, the Re-FeFET circuit demonstrates high compactness, with an up to 80% reduction in transistor count compared to standard CMOS design. The 2D van de Waals Re-FeFET devices therefore exhibit promising potential for both More-than-Moore and beyond-Moore future of electronics, in particular for an energy-efficient implementation of in-memory computing and machine learning hardware, due to their multifunctionality and design compactness.

Export pathways of biosolid derived microplastics in soil systems - Findings from a temperate maritime climate.

The environmental fate of microplastics (MPs) added to agricultural soils remains poorly understood, particularly regarding their mobility in soils. Here we investigate the potential for MP export from soil to surface waters and groundwater in two agricultural settings with a 20-year history of biosolid treatment. A third site where biosolids had never been applied served as a reference (Field R). The potential for MP export along overland and interflow pathways to surface waters was determined from MP abundances in shallow surface cores (10 cm) along ten down-slope transects (five each for Field A and B), and through MP abundances in effluent from a sub-surface land drain. The risk of vertical MP migration was assessed from 2 m cores, and from MP abundances in groundwater sampled from the core boreholes. XRF Itrax core scanning was conducted on two of the deep cores to capture high-resolution optical and 2-D radiographic imaging. Results suggest limited MP mobility at depths >35 cm, with MPs largely recovered in surface soils characterised by lower compaction. Furthermore, abundances of MPs across the surface cores were comparable, with no evidence of MP accumulations observed. Average MP abundance in the top 10 cm of soil across Field A and B was 365 ± 302 MP kg-1, with 0.3 MP l-1 and 1.6 MP l-1 recovered from the groundwater and field drainpipe water samples, respectively. MP abundances were significantly higher in fields treated with biosolids than in Field R (90 ± 32 MP kg-1 soil). Findings suggest ploughing is the most significant driver of MP mobility in upper soil layers, however the potential for overland or interflow movement cannot be excluded, particularly for fields that may be artificially drained.

Minimum complexity integrated photonic architecture for delay-based reservoir computing.

Reservoir computing is an analog bio-inspired computation scheme for efficiently processing time-dependent signals, the photonic implementations of which promise a combination of massive parallel information processing, low power consumption, and high-speed operation. However, most of these implementations, especially for the case of time-delay reservoir computing, require extensive multi-dimensional parameter optimization to find the optimal combination of parameters for a given task. We propose a novel, largely passive integrated photonic TDRC scheme based on an asymmetric Mach-Zehnder interferometer in a self-feedback configuration, where the nonlinearity is provided by the photodetector, and with only one tunable parameter in the form of a phase shifting element that, as a result of our configuration, allows also to tune the feedback strength, consequently tuning the memory capacity in a lossless manner. Through numerical simulations, we show that the proposed scheme achieves good performance -when compared to other integrated photonic architectures- on the temporal bitwise XOR task and various time series prediction tasks, while greatly reducing hardware and operational complexity.

Experimental infection trials with European North Atlantic ranavirus (Iridoviridae) isolated from lumpfish (Cyclopterus lumpus, L.).

European North Atlantic ranavirus (ENARV, Iridoviridae), is a ranavirus species recently isolated from lumpfish (Cyclopterus lumpus, L.), which are used as cleaner fish in Atlantic salmon (Salmo salar) farming in Northern Europe. This study aimed to investigate (1) the virulence of ENARV isolates from Ireland, Iceland and the Faroe Islands to lumpfish; (2) horizontal transmission between lumpfish; and (3) virulence to Atlantic salmon parr. Lumpfish were challenged in a cohabitation model using intraperitoneally (IP) injected shedders, and naïve cohabitants. IP challenge with isolates from Iceland (1.9 × 107 TCID50  ml-1 ) and the Faroe Islands (5.9 × 107 TCID50  ml-1 ) reduced survival in lumpfish, associated with consistent pathological changes. IP challenge with the Irish strain (8.6 × 105 TCID50  ml-1 ) did not significantly reduce survival in lumpfish, but the lower challenge titre complicated interpretation. Horizontal transmission occurred in all strains tested, but no clinical impact was demonstrated in cohabitants. Salmon parr were challenged by IP injection with the Irish isolate, no virulence or virus replication were demonstrated. A ranavirus qPCR assay, previously validated for fish ranaviruses, was first used to detect ENARV in tissues of both in lumpfish and Atlantic salmon. This study provides the first data on the assessment of virulence of ENARV isolates to lumpfish and salmon, guidelines for the diagnosis of ENARV infection, and poses a basis for further investigations into virulence markers.

Imaging Mass Spectrometry Reveals Alterations in N-Linked Glycosylation That Are Associated With Histopathological Changes in Nonalcoholic Steatohepatitis in Mouse and Human.

Nonalcoholic steatohepatitis (NASH) is the progressive form of nonalcoholic fatty liver disease (NAFLD) and is characterized by inflammation, hepatocyte injury, and fibrosis. Further, NASH is a risk factor for cirrhosis and hepatocellular carcinoma. Previous research demonstrated that serum N-glycan profiles can be altered in NASH patients. Here, we hypothesized that these N-glycan modifications may be associated with specific liver damage in NAFLD and NASH. To investigate the N-glycome profile in tissue, imaging mass spectrometry was used for a qualitative and quantitative in situ N-linked glycan analysis of mouse and human NAFLD/NASH tissue. A murine model was used to induce NAFLD and NASH through ad libitum feeding with either a high-fat diet or a Western diet, respectively. Mice fed a high-fat diet or Western diet developed inflammation, steatosis, and fibrosis, consistent with NAFLD/NASH phenotypes. Induction of NAFLD/NASH for 18 months using high caloric diets resulted in increased expression of mannose, complex/fucosylated, and hybrid N-glycan structures compared to control mouse livers. To validate the animal results, liver biopsy specimens from 51 human NAFLD/NASH patients representing the full range of NASH Clinical Research Network fibrosis stages were analyzed. Importantly, the same glycan alterations observed in mouse models were observed in human NASH biopsies and correlated with the degree of fibrosis. In addition, spatial glycan alterations were localized specifically to histopathological changes in tissue like fibrotic and fatty areas. We demonstrate that the use of standard staining's combined with imaging mass spectrometry provide a full profile of the origin of N-glycan modifications within the tissue. These results indicate that the spatial distribution of abundances of released N-glycans correlate with regions of tissue steatosis associated with NAFLD/NASH.

Investigation of the transcriptomic response in Atlantic salmon (Salmo salar) gill exposed to Paramoeba perurans during early onset of disease.

Amoebic Gill Disease (AGD), caused by the protozoan extracellular parasite Paramoeba perurans (P. perurans) is a disease affecting Atlantic salmon (Salmo salar). This study investigated the gill transcriptomic profile of pre-clinical AGD using RNA-sequencing (RNA-seq) technology. RNA-seq libraries generated at 0, 4, 7, 14 and 16 days post infection (dpi) identified 19,251 differentially expressed genes (DEGs) of which 56.2% were up-regulated. DEGs mapped to 224 Gene Ontology (GO) terms including 140 biological processes (BP), 45 cellular components (CC), and 39 molecular functions (MF). A total of 27 reference pathways in the Kyoto Encyclopedia of Genes and Genomes (KEGG) and 15 Reactome gene sets were identified. The RNA-seq data was validated using real-time, quantitative PCR (qPCR). A host immune response though the activation of complement and the acute phase genes was evident at 7 dpi, with a concurrent immune suppression involving cytokine signalling, notably in interleukins, interferon regulatory factors and tumour necrosis factor-alpha (tnf-α) genes. Down-regulated gene expression with involvement in receptor signalling pathways (NOD-like, Toll-like and RIG-1) were also identified. The results of this study support the theory that P. perurans can evade immune surveillance during the initial stages of gill colonisation through interference of signal transduction pathways.

Differential Exoproteome and Biochemical Characterisation of Neoparamoeba perurans.

Infection with the protozoan ectoparasite Neoparamoeba perurans, the causative agent of AGD, remains a global threat to salmonid farming. This study aimed to analyse the exoproteome of both an attenuated and virulent N. perurans isolate using proteomics and cytotoxicity testing. A disproportionate presence of proteins from the co-cultured microbiota of N. perurans was revealed on searching an amalgamated database of bacterial, N. perurans and Amoebozoa proteins. LC-MS/MS identified 33 differentially expressed proteins, the majority of which were upregulated in the attenuated exoproteome. Proteins of putative interest found in both exoproteomes were maltoporin, ferrichrome-iron receptor, and putative ferric enterobactin receptor. Protease activity remained significantly elevated in the attenuated exoproteome compared with the virulent exoproteome. Similarly, the attenuated exoproteome had a significantly higher cytotoxic effect on rainbow trout gill cell line (RTgill W1) cells compared with the virulent exoproteome. The presence of a phosphatase and serine protease in the virulent exoproteome may facilitate AGD infection but do not appear to be key players in causing cytotoxicity. Altogether, this study reveals prolonged culture of N. perurans affects the exoproteome composition in favour of nutritional acquisition, and that the current culturing protocol for virulent N. perurans does not facilitate the secretion of virulence factors.

Polycyclic aromatic hydrocarbons (PAHs) in seabird eggs in Ireland.

Seabird eggs are considered a favourable matrix for monitoring marine pollutants and are widely used as higher trophic level indicators. Concentrations of Polycyclic aromatic hydrocarbons (Σ15PAH) were determined in the eggs of four piscivorous seabirds in Ireland from multiple colonies for the first time, Common Guillemot Uria aalge, Northern Gannet Morus bassanus, Common Tern Sterna hirundo and Arctic Tern S. paradisaea. PAH concentrations were generally lower than levels detected in eggs from other seabird studies and considerably lower than concentrations associated with no adverse effect in the eggs of domestic avian species. This study indicates potential site and species differences in PAH concentrations. Baseline data of PAHs in a range of seabird species from this study may provide an important reference point should a major pollution event occur in European waters, such as an oil spill.

Legacy and emerging contaminants in common guillemot Uria aalge eggs in Ireland and Wales.

Guillemot eggs from multiple Irish colonies and one Welsh colony were analysed for legacy pollutants such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and other organochlorine compounds (OCs), as well as metals. Stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) were measured in eggs to understand the influence of diet on contaminant levels detected. Wide-scope target and suspect screening techniques were used on a single guillemot egg, providing novel information on contaminants of emerging concern. Stable isotope ratio analysis showed that guillemots from Great Saltee Island and Lambay Island (Ireland's east coast) had a similar carbon source (δ13C) and fed at similar trophic levels (δ15N), pollutant levels were higher in eggs from Lambay Island near Dublin, Ireland's industrialised capital city. Guillemot eggs from Aughris Head (Atlantic west coast of Ireland), and Skomer Island (Wales) had differing isotopic niches to other colonies. Egg samples from Aughris Head had the lowest levels of pollutants in this study (with the exception of mercury) and amongst the lowest levels reported worldwide. In contrast, Skomer Island had the highest level of pollutants with higher concentrations of Σ16PCB, Σ6PBDE and HCB than Irish colonies, most likely a result of its proximity to historically industrial areas. Levels of PCBs, p,p' -DDE and mercury in guillemot eggs have decreased over time according to this study, in concurrence with worldwide trends. Levels of pollutants in guillemot eggs, in this study, fall below existing thresholds for adverse effects in other species, with the exception of mercury.

Host Response of Atlantic Salmon (Salmo salar) Re-Inoculated with Paramoeba perurans.

In aquaculture, recurrence rates of amoebic gill disease (AGD) caused by the ectoparasite Paramoeba perurans are high and no prophylactic strategies exist for disease prevention. In this study, Atlantic salmon (Salmo salar) were initially inoculated with P. perurans and following the development of amoebic gill disease were treated with freshwater immersion on day 21 and day 35 post inoculation. Fish were re-inoculated following a negative qPCR analysis for the presence of P. perurans. The gill host immune response was investigated at 7, 14, and 18 days post re-inoculation. Differential proteome expression of immune related proteins was assessed by comparison of each time point against naïve controls. In the gill, some proteins of the innate immune system were expressed in response to gill re-colonization by P. perurans, while no features of adaptive immunity were found to be differentially expressed. Many of the proteins identified are novel in the context of AGD and their expression profiles suggest that their roles in the response to disease development and progression in single or multiple infections warrant further investigation.

Persistent pollutants in fresh and abandoned eggs of Common Tern (Sterna hirundo) and Arctic Tern (Sterna paradisaea) in Ireland.

Higher levels of persistent pollutants (Σ16PCB, Σ6PBDE, ΣHCH, ΣDDT, ΣCHL) were detected in fresh eggs of Common Terns Sterna hirundo from Rockabill Island near Dublin (Ireland's industrialised capital city) compared to Common and Arctic Terns S. paradisaea from Ireland's west coast. Intra-clutch variation of pollutant levels in Common Terns was shown to be low, providing further evidence that random sampling of one egg may be an appropriate sampling strategy. Significant differences in pollutant concentrations were detected between fresh and abandoned eggs on Rockabill. However, abandoned eggs can still provide a useful approximation of pollutants in bird eggs if non-destructive sampling is preferred. Levels of p,p' -DDE in tern eggs have decreased over time according to this study, in concurrence with worldwide trends. Results in this study fall below toxicological thresholds for birds and OSPARs EcoQO thresholds set for Common Tern eggs, except for mercury and HCH in the west coast.

Investigation of the Initial Host Response of Naïve Atlantic Salmon (Salmo salar) Inoculated with Paramoeba perurans.

Amoebic Gill Disease (AGD), caused by the ectoparasite Paramoeba perurans is characterised by hyperplasia of the gill epithelium and lamellar fusion. In this study, the initial host response of naïve Atlantic salmon (Salmo salar) inoculated with P. perurans was investigated. Using gel-free proteomic techniques and mass spectrometry gill and serum samples were analysed at 7 timepoints (2, 3, 4, 7, 9, 11 and 14 days) post-inoculation with P. perurans. Differential expression of immune related proteins was assessed by comparison of protein expression from each time point against naïve controls. Few host immune molecules associated with innate immunity showed increased expression in response to gill colonisation by amoebae. Furthermore, many proteins with roles in immune signalling, phagocytosis and T-cell proliferation were found to be inhibited upon disease progression. Initially, various immune factors demonstrated the anticipated increase in expression in response to infection in the serum while some immune inhibition became apparent at the later stages of disease progression. Taken together, the pro-immune trend observed in serum, the lack of a robust early immune response in the gill and the diversity of those proteins in the gill whose altered expression negatively impact the immune response, support the concept of a pathogen-derived suppression of the host response.

Comparative proteomic profiling of newly acquired, virulent and attenuated Neoparamoeba perurans proteins associated with amoebic gill disease.

The causative agent of amoebic gill disease, Neoparamoeba perurans is reported to lose virulence during prolonged in vitro maintenance. In this study, the impact of prolonged culture on N. perurans virulence and its proteome was investigated. Two isolates, attenuated and virulent, had their virulence assessed in an experimental trial using Atlantic salmon smolts and their bacterial community composition was evaluated by 16S rRNA Illumina MiSeq sequencing. Soluble proteins were isolated from three isolates: a newly acquired, virulent and attenuated N. perurans culture. Proteins were analysed using two-dimensional electrophoresis coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS). The challenge trial using naïve smolts confirmed a loss in virulence in the attenuated N. perurans culture. A greater diversity of bacterial communities was found in the microbiome of the virulent isolate in contrast to a reduction in microbial community richness in the attenuated microbiome. A collated proteome database of N. perurans, Amoebozoa and four bacterial genera resulted in 24 proteins differentially expressed between the three cultures. The present LC-MS/MS results indicate protein synthesis, oxidative stress and immunomodulation are upregulated in a newly acquired N. perurans culture and future studies may exploit these protein identifications for therapeutic purposes in infected farmed fish.

Persistent pollutants in Northern Gannet Morus bassanus eggs in Ireland: Levels and colony differences.

Seabird eggs are considered a favourable matrix for monitoring marine pollutants and are widely used as higher trophic level indicators. Persistent organic pollutants such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and other organochlorine compounds (OCs) as well as metals have been shown to have deleterious impacts on seabirds. The Northern Gannet Morus bassanus is an avian sentinel; the largest breeding seabird in Ireland and an obligate piscivore. Gannet eggs were collected from two island colonies off the east coast of Ireland in locations with divergent history of industrialisation. Contaminant levels were measured and differences in concentrations between colonies compared. Stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) were measured in each egg to understand the influence of diet and trophic position on contaminant levels detected. Significantly higher levels of Σ14PCBs, Σ7PBDEs and total mercury were detected in Gannet eggs from Lambay Island near Dublin (Ireland's industrialised capital city) compared to Great Saltee Island. No differences were observed in levels of other OCs (HCB, ΣHCH, ΣCHL, ΣDDT) between the two colonies. Though Gannets travel significant distances when foraging for food, tracking studies have demonstrated that birds from proximal breeding colonies maintain exclusive feeding areas. Stable isotope ratio analysis in this study demonstrated that Gannets at both locations occupy similar dietary niches, indicating that dietary differences may not be the driver of differing contaminant levels between colonies. Levels of persistent pollutants in the Gannet eggs fall below most existing thresholds for adverse effects and are within internationally reported values. Recent population growth and range expansion of Gannets in Ireland suggest that persistent pollutants are not having an immediate impact on the Gannet population. This study will inform potential monitoring programmes that can help Ireland achieve good environmental status under the European Union's Marine Strategy Framework Directive.

Microplastics in brown trout (Salmo trutta Linnaeus, 1758) from an Irish riverine system.

Rivers play an important role in the overall transport of microplastic pollution (1 µm to 5 mm), with fluvial dynamics expected to influence biotic interactions, particularly for fish. So far, there have been few assessments of microplastics in freshwater salmonids. The prevalence (i.e. percentage occurrence) and burden (i.e. abundance per fish) of microplastics were assessed in the gastrointestinal tracts (GITs) and stomach contents (SCs) of 58 brown trout Salmo trutta Linnaeus, 1758 sampled at six sites along the River Slaney catchment in south-east Ireland. Sites were divided into two classifications (high and low exposure) based on proximity to microplastic pollution sources, comprising three sites each. Analysis of biological traits (e.g. fish length) and diet was performed on the same fish to determine possible factors explaining microplastic burden. Microplastics were found in 72% of fish having been recovered from 66% of GITs (1.88 ± 1.53 MPs fish⁻1) and 28% of SCs (1.31 ± 0.48 MPs fish⁻1). Fibres were the dominant particle type recovered from GITs (67%) and SCs (57%) followed by fragments. No difference in median microplastic burden was observed between fish collected in high and low exposure sites. Microplastic burden was unrelated to fish fork length, while microplastic size distribution (100 ≤ 350 µm, 350 µm to ≤ 5 mm) was unrelated to S. trutta age class estimates. Furthermore, microplastic burden was not explained by dietary intake. Though further research is necessary, this study showed the presence of microplastics in wild S. trutta collected from an Irish riverine system, which could have further implications for top-level consumers that feed on the species, including humans. Further analysis is required to determine possible trophic linkages for the species, with respect to microplastics, and to assess the suitability of S. trutta for monitoring microplastics in river systems.

Microplastics in sea ice and seawater beneath ice floes from the Arctic Ocean.

Within the past decade, an alarm was raised about microplastics in the remote and seemingly pristine Arctic Ocean. To gain further insight about the issue, microplastic abundance, distribution and composition in sea ice cores (n = 25) and waters underlying ice floes (n = 22) were assessed in the Arctic Central Basin (ACB). Potential microplastics were visually isolated and subsequently analysed using Fourier Transform Infrared (FT-IR) Spectroscopy. Microplastic abundance in surface waters underlying ice floes (0-18 particles m-3) were orders of magnitude lower than microplastic concentrations in sea ice cores (2-17 particles L-1). No consistent pattern was apparent in the vertical distribution of microplastics within sea ice cores. Backward drift trajectories estimated that cores possibly originated from the Siberian shelves, western Arctic and central Arctic. Knowledge about microplastics in environmental compartments of the Arctic Ocean is important in assessing the potential threats posed by microplastics to polar organisms.