Heterogeneous microgeographic genetic structure of the common cockle (Cerastoderma edule) in the Northeast Atlantic Ocean: biogeographic barriers and environmental factors.

Knowledge of genetic structure at the finest level is essential for the conservation of genetic resources. Despite no visible barriers limiting gene flow, significant genetic structure has been shown in marine species. The common cockle (Cerastoderma edule) is a bivalve of great commercial and ecological value inhabiting the Northeast Atlantic Ocean. Previous population genomics studies demonstrated significant structure both across the Northeast Atlantic, but also within small geographic areas, highlighting the need to investigate fine-scale structuring. Here, we analysed two geographic areas that could represent opposite models of structure for the species: (1) the SW British Isles region, highly fragmented due to biogeographic barriers, and (2) Galicia (NW Spain), a putative homogeneous region. A total of 9250 SNPs genotyped by 2b-RAD on 599 individuals from 22 natural beds were used for the analysis. The entire SNP dataset mostly confirmed previous observations related to genetic diversity and differentiation; however, neutral and divergent SNP outlier datasets enabled disentangling physical barriers from abiotic environmental factors structuring both regions. While Galicia showed a homogeneous structure, the SW British Isles region was split into four reliable genetic regions related to oceanographic features and abiotic factors, such as sea surface salinity and temperature. The information gathered supports specific management policies of cockle resources in SW British and Galician regions also considering their particular socio-economic characteristics; further, these new data will be added to those recently reported in the Northeast Atlantic to define sustainable management actions across the whole distribution range of the species.

Mutations in the gene encoding the 3'-5' DNA exonuclease TREX1 cause Aicardi-Goutières syndrome at the AGS1 locus.

Aicardi-Goutières syndrome (AGS) presents as a severe neurological brain disease and is a genetic mimic of the sequelae of transplacentally acquired viral infection. Evidence exists for a perturbation of innate immunity as a primary pathogenic event in the disease phenotype. Here, we show that TREX1, encoding the major mammalian 3' --> 5' DNA exonuclease, is the AGS1 gene, and AGS-causing mutations result in abrogation of TREX1 enzyme activity. Similar loss of function in the Trex1(-/-) mouse leads to an inflammatory phenotype. Our findings suggest an unanticipated role for TREX1 in processing or clearing anomalous DNA structures, failure of which results in the triggering of an abnormal innate immune response.

Predicting Alzheimer disease with ß-amyloid imaging: results from the Australian imaging, biomarkers, and lifestyle study of ageing.

OBJECTIVE: Biomarkers for Alzheimer disease (AD) can detect the disease pathology in asymptomatic subjects and individuals with mild cognitive impairment (MCI), but their cognitive prognosis remains uncertain. We aimed to determine the prognostic value of ß-amyloid imaging, alone and in combination with memory performance, hippocampal atrophy, and apolipoprotein E ε4 status in nondemented, older individuals. METHODS: A total of 183 healthy individuals (age = 72.0 ± 7.26 years) and 87 participants with MCI (age = 73.7 ± 8.27) in the Australian Imaging, Biomarkers, and Lifestyle study of ageing were studied. Clinical reclassification was performed after 3 years, blind to biomarker findings. ß-Amyloid imaging was considered positive if the (11) C-Pittsburgh compound B cortical to reference ratio was ≥1.5. RESULTS: Thirteen percent of healthy persons progressed (15 to MCI, 8 to dementia), and 59% of the MCI cohort progressed to probable AD. Multivariate analysis showed ß-amyloid imaging as the single variable most strongly associated with progression. Of combinations, subtle memory impairment (Z score = -0.5 to -1.5) with a positive amyloid scan was most strongly associated with progression in healthy individuals (odds ratio [OR] = 16, 95% confidence interval [CI] = 3.7-68; positive predictive value [PPV] = 50%, 95% CI = 19-81; negative predictive value [NPV] = 94%, 95% CI = 88-98). Almost all amnestic MCI subjects (Z score ≤ -1.5) with a positive amyloid scan developed AD (OR = ∞; PPV = 86%, 95% CI = 72-95; NPV = 100%, 95% CI = 80-100). Hippocampal atrophy and ε4 status did not add further predictive value. INTERPRETATION: Subtle memory impairment with a positive ß-amyloid scan identifies healthy individuals at high risk for MCI or AD. Clearly amnestic patients with a positive amyloid scan have prodromal AD and a poor prognosis for dementia within 3 years.

Trapping and bypassing of suspended particulate matter, particulate nutrients and faecal indicator organisms in the river-estuary transition zone of a shallow macrotidal estuary.

Hydrodynamic controls of the transport of suspended particulate matter (SPM), particulate nutrients and faecal indicator organisms (FIOs) in the river-estuary transition zone (RETZ) of a shallow macrotidal estuary were studied on tidal and seasonal timescales. The RETZ was found to be a conduit for SPM rather than a zone of particle accumulation during spring tides, with complex size fractionation and biogeochemical exchanges of particulate nutrient/FIO compositions. The downstream RETZ was characterised by flood-dominant currents, but with ebb-dominant turbulence due to the suppression of flood tide turbulence by salinity stratification created by lateral convergence; this produced a net seaward mass transport of SPM. Without lateral convergence in the narrower upstream RETZ, flood-dominant currents and flood-dominant turbulence were experienced. Hence the RETZ exported SPM landwards from its upper end and seawards from its lower end - a process observed throughout the year during spring tides and low-to-mean river flows. During neap tides when SPM concentrations were reduced, the RETZ became a zone of minor particle accumulation as its lower end imported SPM landwards from the estuary and its upper end imported SPM seawards from the river. During a river flood event, net SPM flux was significantly increased and was seawards throughout the RETZ. SPM mass concentration and carbon, nitrogen, phosphorous, and FIO concentrations peaked due to local resuspension and advection of an ephemeral estuarine turbidity maximum (ETM). The ETM formed on the advancing flood tide due to entrainment of material from intertidal flats. Flocculation and settling occurred at high slack water. The ETM was reconstituted by entrainment on the ebb and was composed of larger flocs than on the flood. Particulate nutrients and FIOs were associated with flocs in the 10-200 µm range but not with smaller or larger flocs. SPM concentrations in the resuspension component and ETM exceeded microbial water quality standards, emphasising the need for monitoring practices that consider tidal dynamics. The results from this study showing periodic SPM export from, rather than prolonged accumulation in, the RETZ and the influence of particle size fractionation on biogeochemical fluxes in the RETZ, are likely to be transferable to many other embayment-type estuaries on macrotidal coasts.

Plastic pollution and human pathogens: Towards a conceptual shift in risk management at bathing water and beach environments.

Emerging evidence indicates that micro- and macro-plastics present in water can support a diverse microbial community, including potential human pathogens (e.g., bacteria, viruses). This interaction raises important concerns surrounding the role and suitability of current bathing water regulations and associated pathogen exposure risk within beach environments. In response to this, we critically evaluated the available evidence on plastic-pathogen interactions and identified major gaps in knowledge. This review highlighted the need for a conceptual shift in risk management at public beaches recognising: (i) interconnected environmental risks, e.g., associations between microbial compliance parameters, potential pathogens and both contemporary and legacy plastic pollution; and (ii) an appreciation of risk of exposure to plastic co-pollutants for both water and waterside users. We present a decision-making framework to identify options to manage plastic-associated pathogen risks alongside short- and longer-term research priorities. This advance will help deliver improvements in managing plastic-associated pathogen risk, acknowledging that human exposure potential is not limited to only those who engage in water-based activity. We argue that adopting these recommendations will help create an integrated approach to managing and reducing human exposure to pathogens at bathing, recreational water and beach environments.

Radiotherapy of abdomen with precise renal assessment with SPECT/CT imaging (RAPRASI): design and methodology of a prospective trial to improve the understanding of kidney radiation dose response.

BACKGROUND: The kidneys are a principal dose-limiting organ in radiotherapy for upper abdominal cancers. The current understanding of kidney radiation dose response is rudimentary. More precise dose-volume response models that allow direct correlation of delivered radiation dose with spatio-temporal changes in kidney function may improve radiotherapy treatment planning for upper-abdominal tumours. METHODS/DESIGN: The Radiotherapy of Abdomen with Precise Renal Assessment with SPECT/CT Imaging (RAPRASI) is an observational clinical research study with participating sites at Sir Charles Gairdner Hospital (SCGH) in Perth, Australia and the Peter MacCallum Cancer Centre (PMCC) in Melbourne, Australia. Eligible patients are those with upper gastrointestinal cancer, without metastatic disease, undergoing conformal radiotherapy that will involve incidental radiation to one or both kidneys. For each patient, total kidney function is being assessed before commencement of radiotherapy treatment and then at 4, 12, 26, 52 and 78 weeks after the first radiotherapy fraction, using two procedures: a Glomerular Filtration Rate (GFR) measurement using the 51Cr-ethylenediamine tetra-acetic acid (EDTA) clearance; and a regional kidney perfusion measurement assessing renal uptake of 99mTc-dimercaptosuccinic acid (DMSA), imaged with a Single Photon Emission Computed Tomography / Computed Tomography (SPECT/CT) system. The CT component of the SPECT/CT provides the anatomical reference of the kidney's position. The data is intended to reveal changes in regional kidney function over the study period after the radiotherapy. These SPECT/CT scans, co-registered with the radiotherapy treatment plan, will provide spatial correlation between the radiation dose and regional renal function as assessed by SPECT/CT. From this correlation, renal response patterns will likely be identified with the purpose of developing a predictive model. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12609000322235.

Testing a peer support intervention for people with type 2 diabetes: a pilot for a randomised controlled trial.

BACKGROUND: People with Type 2 diabetes face various psycho-social, self-management and clinical care issues and evidence is mixed whether support from others with diabetes, 'peer support', can help. We now describe a 2 month pilot study of different peer support interventions. METHODS: The intervention was informed by formative evaluation using semi-structured interviews with health professionals, community support groups and observation of diabetes education and support groups. Invitations to participate were mailed from 4 general practices and included a survey of barriers to care. Participants were randomized by practice to receive individual, group, combined (both individual and group) or no peer support. Evaluation included ethnographic observation, semi-structured interviews and questionnaires at baseline and post-intervention. RESULTS: Of 1,101 invited, 15% expressed an interest in participating in the pilot. Sufficient numbers volunteered to become peer supporters, although 50% of these (8/16) withdrew. Those in the pilot were similar to other patients, but were less likely to feel they knew enough about diabetes (60.8% vs 44.6% p = 0.035) and less likely to be happy with the diabetes education/care to date (75.4% vs 55.4% p = 0.013). Key issues identified were the need to recruit peer supporters directly rather than through clinicians, to address participant diabetes educational needs early and the potential for group sessions to have lower participation rates than 1:1 sessions. CONCLUSIONS: Recruitment to a full trial of peer support within the existing study design is feasible with some amendments. Attendance emerged as a key issue needing close monitoring and additional intervention during the trial.

Brain Amyloid in Sporadic Young Onset Alzheimer's Disease.

Background: Controversy exists as to the role of the amyloid-ß (Aß) peptide in the pathophysiology of Alzheimer's disease (AD). Objective: To clarify the effect of age on Aß deposition in sporadic AD by exploring the degree of amyloid burden in patients with sporadic young onset AD (YOAD). Methods: Patients were diagnosed with YOAD with dementia starting before the age of 65 years (N = 42; males = 20, females = 22). A cross-sectional analysis of amyloid binding using positron emission tomography (PET) imaging was performed using the C-Pittsburgh Compound B (PiB). The global standardized uptake value ratios (gSUVR) were examined using the Wilcoxon two-sample test, as were the cognitive scores between disease and healthy control populations. Differences in PiB retention in different anatomical areas were compared using the Kruskal-Wallis test. The contrast in APOE genotyping between groups was calculated with Fisher's Exact Test. Results: Women had a median gSUVR = 2.68±0.73 and 73% had at least one APOE ɛ4 allele. Men had gSUVR = 2.37±0.54, with 80% having at least one APOE ɛ4 allele. The gSUVRs were significantly higher than the control populations for men and women and had significantly greater frequency of APOE ɛ4. Men and women analyzed together had significantly greater amyloid burden and APOE ɛ4 allele frequencies than controls, but no differences existed between them in gSUVR nor in the anatomical distribution of amyloid uptake. Conclusion: Men and women with YOAD have greater amyloid uptake than controls and have more APOE ɛ4 alleles. Our findings suggest that the Aß peptide is operational in young onset dementia and driven by the APOE ɛ4 allele.

The role of wind in controlling the connectivity of blue mussels (Mytilus edulis L.) populations.

BACKGROUND: Larval connectivity between distinct benthic populations is essential for their persistence. Although connectivity is difficult to measure in situ, it can be predicted via models that simulate biophysical interactions between larval behaviour and ocean currents. The blue mussel (Mytilus Edulis L.) is widespread throughout the northern hemisphere and extensively commercialised worldwide. In the Irish Sea, this industry represents ~ 50% of Welsh shellfisheries, where cultivation is mainly based on wild spat. However, the main sources and amount of spat varied interannually (1100 tonnes harvest in 2014 against zero in 2018). The aim of this study is to characterise the structure and dynamics of the blue mussel metapopulation within the northern part of the Irish Sea. METHODS: We develop a Lagrangian particle tracking model, driven by a high-resolution (from 30 to 5000 m) validated unstructured coastal hydrodynamic model of the Irish Sea, to simulate spatial and temporal variability of larval dispersal and connectivity between distinct mussel populations and potential settlement areas. RESULTS: Our results showed that: (1) larvae positioned near the surface were strongly influenced by wind-driven currents suggesting that connectivity networks had the potential to span hundreds of kilometres; (2) in contrast, larvae positioned deeper in the water column were driven by tidal currents, producing intricate spatial patterns of connectivity between mussel beds over tens of kilometres that were consistent over time. CONCLUSIONS: Dispersal of mussel larvae in the tidally energetic Irish Sea during the April-May spawning season is potentially driven by wind-driven surface currents, as confirmed by fisherman observations of inter-annual variability in wild spat collection. These results have important implications for metapopulation dynamics within the context of climate change and sustainable shellfisheries management (i.e. gain and loss of populations and harvest areas according to wind conditions).

Predicting the dispersal of SARS-CoV-2 RNA from the wastewater treatment plant to the coast.

Viral pathogens including SARS-CoV-2 RNA have been detected in wastewater treatment effluent, and untreated sewage overflows, that pose an exposure hazard to humans. We assessed whether SARS-CoV-2 RNA was likely to have been present in detectable quantities in UK rivers and estuaries during the first wave of the Covid-19 pandemic. We simulated realistic viral concentrations parameterised on the Camel and Conwy catchments (UK) and their populations, showing detectable SARS-CoV-2 RNA concentrations for untreated but not for treated loading, but also being contingent on viral decay, hydrology, catchment type/shape, and location. Under mean or low river flow conditions, viral RNA concentrated within the estuaries allowing for viral build-up and caused a lag by up to several weeks between the peak in community infections and the viral peak in the environment. There was an increased hazard posed by SARS-CoV-2 RNA with a T 90 decay rate >24 h, as the estuarine build-up effect increased. High discharge events transported the viral RNA downstream and offshore, increasing the exposure risk to coastal bathing waters and shellfisheries - although dilution in this case reduced viral concentrations well below detectable levels. Our results highlight the sensitivity of exposure to viral pathogens downstream of wastewater treatment, across a range of viral loadings and catchment characteristics - with implications to environmental surveillance.

Genomic survey of edible cockle (Cerastoderma edule) in the Northeast Atlantic: A baseline for sustainable management of its wild resources.

Knowledge on correlations between environmental factors and genome divergence between populations of marine species is crucial for sustainable management of fisheries and wild populations. The edible cockle (Cerastoderma edule) is a marine bivalve distributed along the Northeast Atlantic coast of Europe and is an important resource from both commercial and ecological perspectives. We performed a population genomics screening using 2b-RAD genotyping on 9309 SNPs localized in the cockle's genome on a sample of 536 specimens pertaining to 14 beds in the Northeast Atlantic Ocean to analyse the genetic structure with regard to environmental variables. Larval dispersal modelling considering species behaviour and interannual/interseasonal variation in ocean conditions was carried out as an essential background to which compare genetic information. Cockle populations in the Northeast Atlantic displayed low but significant geographical differentiation between populations (F ST = 0.0240; p < 0.001), albeit not across generations. We identified 742 and 36 outlier SNPs related to divergent and balancing selection in all the geographical scenarios inspected, and sea temperature and salinity were the main environmental correlates suggested. Highly significant linkage disequilibrium was detected at specific genomic regions against the very low values observed across the whole genome. Two main genetic groups were identified, northwards and southwards of French Brittany. Larval dispersal modelling suggested a barrier for larval dispersal linked to the Ushant front that could explain these two genetic clusters. Further genetic subdivision was observed using outlier loci and considering larval advection. The northern group was divided into the Irish/Celtic Seas and the English Channel/North Sea, while the southern group was divided into three subgroups. This information represents the baseline for the management of cockles, designing conservation strategies, founding broodstock for depleted beds and producing suitable seed for aquaculture production.

Priorities to inform research on marine plastic pollution in Southeast Asia.

Southeast Asia is considered to have some of the highest levels of marine plastic pollution in the world. It is therefore vitally important to increase our understanding of the impacts and risks of plastic pollution to marine ecosystems and the essential services they provide to support the development of mitigation measures in the region. An interdisciplinary, international network of experts (Australia, Indonesia, Ireland, Malaysia, the Philippines, Singapore, Thailand, the United Kingdom, and Vietnam) set a research agenda for marine plastic pollution in the region, synthesizing current knowledge and highlighting areas for further research in Southeast Asia. Using an inductive method, 21 research questions emerged under five non-predefined key themes, grouping them according to which: (1) characterise marine plastic pollution in Southeast Asia; (2) explore its movement and fate across the region; (3) describe the biological and chemical modifications marine plastic pollution undergoes; (4) detail its environmental, social, and economic impacts; and, finally, (5) target regional policies and possible solutions. Questions relating to these research priority areas highlight the importance of better understanding the fate of marine plastic pollution, its degradation, and the impacts and risks it can generate across communities and different ecosystem services. Knowledge of these aspects will help support actions which currently suffer from transboundary problems, lack of responsibility, and inaction to tackle the issue from its point source in the region. Being profoundly affected by marine plastic pollution, Southeast Asian countries provide an opportunity to test the effectiveness of innovative and socially inclusive changes in marine plastic governance, as well as both high and low-tech solutions, which can offer insights and actionable models to the rest of the world.

Management of adrenocortical carcinoma in Western Australia: a perspective over 14 years.

BACKGROUND: Adrenocortical carcinoma is a rare but aggressive form of endocrine neoplasm that confers a poor prognosis. To date, the only Australian data published is from New South Wales. This paper describes our experience in Western Australia with a focus on surgical approach and outcomes. METHODS: A retrospective study of patients treated for adrenocortical carcinoma in Western Australia over 14 years was performed. RESULTS: Over the 14-year period, a total of 33 patients underwent surgery for adrenocortical carcinoma. Resection outcomes were superior in an open en bloc approach with an 85% R0 margin (P = 0.007). Local recurrence rates were lowest in an open en bloc approach (11%) compared to laparoscopic (75%). Multivariate analysis showed that an en bloc resection is highly correlated with an R0 resection (P < 0.05) and significantly associated with lower (odds ratio = 0.06) local recurrence (P = 0.009). Higher volume surgeons (>5 cases) had lower operative times and blood loss. Compliance with mitotane was significantly improved with close monitoring of levels. The European Network for the Study of Adrenal Tumours (ENSAT) stage at presentation was most predictive of long-term survival with 100% of stage I patients alive compared to 53% of stage II, 25% of stage III and 17% of stage IV patients at the end of the follow-up period. CONCLUSION: An open en bloc approach with a low threshold for multi-visceral resection performed by high volume surgeons have improved outcomes in local recurrence, operative times and blood loss.

Impact of Sediment Concentration on the Survival of Wastewater-Derived blaCTX-M-15-Producing E. coli, and the Implications for Dispersal into Estuarine Waters.

The environmental cycling of antibiotic-resistant blaCTX-M-15-producing E. coli following release from wastewater treatment plants is a major public health concern. This study aimed to (i) assess the impact of sediment concentrations on the rate of their inactivation following release from human wastewater into freshwater, and (ii) simulate their subsequent dispersal to the nearby coastline during a "worst-case" event where heavy rainfall coincided with high spring tide in the Conwy Estuary, North Wales. Freshwater microcosms of low, medium and high turbidity were inoculated with blaCTX-M-15 -producing E. coli, then exposed to ultraviolet (UV) radiation. Typical regional wintertime exposure to UV was found to be insufficient to eradicate E. coli, and in highly turbid water, many bacteria survived simulated typical regional summertime UV exposure. Modelling results revealed that blaCTX-M-15-producing E. coli concentrations reduced downstream from the discharge source, with ~ 30% of the source concentration capable of dispersing through the estuary to the coast, taking ~36 h. Offshore, the concentration simulated at key shellfisheries and bathing water sites ranged from 1.4% to 10% of the upstream input, depending on the distance offshore and tidal regime, persisting in the water column for over a week. Our work indicates that the survival of such organisms post-release into freshwater is extended under typical wintertime conditions, which could ultimately have implications for human health.

Fine-scale seascape genomics of an exploited marine species, the common cockle Cerastoderma edule, using a multimodelling approach.

Population dynamics of marine species that are sessile as adults are driven by oceanographic dispersal of larvae from spawning to nursery grounds. This is mediated by life-history traits such as the timing and frequency of spawning, larval behaviour and duration, and settlement success. Here, we use 1725 single nucleotide polymorphisms (SNPs) to study the fine-scale spatial genetic structure in the commercially important cockle species Cerastoderma edule and compare it to environmental variables and current-mediated larval dispersal within a modelling framework. Hydrodynamic modelling employing the NEMO Atlantic Margin Model (AMM15) was used to simulate larval transport and estimate connectivity between populations during spawning months (April-September), factoring in larval duration and interannual variability of ocean currents. Results at neutral loci reveal the existence of three separate genetic clusters (mean F ST = 0.021) within a relatively fine spatial scale in the north-west Atlantic. Environmental association analysis indicates that oceanographic currents and geographic proximity explain over 20% of the variance observed at neutral loci, while genetic variance (71%) at outlier loci was explained by sea surface temperature extremes. These results fill an important knowledge gap in the management of a commercially important and overexploited species, bringing us closer to understanding the role of larval dispersal in connecting populations at a fine geographic scale.

Biochemical properties of mammalian TREX1 and its association with DNA replication and inherited inflammatory disease.

The major DNA-specific 3'-5' exonuclease of mammalian cells is TREX1 (3' repair exonuclease 1; previously called DNase III). The human enzyme is encoded by a single exon and, like many 3' exonucleases, exists as a homodimer. TREX1 degrades ssDNA (single-stranded DNA) more efficiently than dsDNA (double-stranded DNA), and its catalytic properties are similar to those of Escherichia coli exonuclease X. However, TREX1 is only found in mammals and has an extended C-terminal domain containing a leucine-rich sequence required for its association with the endoplasmic reticulum. In normal S-phase and also in response to genotoxic stress, TREX1 at least partly redistributes to the cell nucleus. In a collaborative project, we have demonstrated TREX1 enzyme deficiency in Aicardi-Goutières syndrome. Subsequently, we have shown that AGS1 cells exhibit chronic ATM (ataxia telangiectasia mutated)-dependent checkpoint activation, and these TREX1-deficient cells accumulate ssDNA fragments of a distinct size generated during DNA replication. Other groups have shown that the syndromes of familial chilblain lupus as well as systemic lupus erythematosus, and the distinct neurovascular disorder retinal vasculopathy with cerebral leukodystrophy, can be caused by dominant mutations at different sites within the TREX1 gene.

Positron emission tomography changes management, improves prognostic stratification and is superior to gallium scintigraphy in patients with low-grade lymphoma: results of a multicentre prospective study.

PURPOSE: Positron emission tomography (PET) was evaluated in low-grade non-Hodgkin lymphoma (NHL) to determine its impact on staging and management and to compare PET and gallium scans. METHODS: PET resulted in management plan changes in 74 patients with untreated low-grade NHL stages I to III. Patient outcomes to 12 months were documented. RESULTS: PET identified additional lesions in 50% of patients, led to a change in stage in 32%, and had a significant impact on management in 34%. Inferior progression-free survival was noted in patients with additional lesions detected by PET (p=0.001) and in the 28% of patients upstaged by PET to stage III or IV (p=0.024). In a subset of 16 patients undergoing both PET and gallium scans, PET was found to be superior. CONCLUSION: PET has a major role in the management of low-grade NHL in addition to its proven role in aggressive lymphoma.

5-Fluorouracil incorporated into DNA is excised by the Smug1 DNA glycosylase to reduce drug cytotoxicity.

5-Fluorouracil (FU) has been widely used for more than four decades in the treatment of a range of common cancers. The fluorine-substituted uracil analogue is converted to several active metabolites but the mechanism of cytotoxicity has remained unclear. In a widely cited but unsubstantiated model, FU is thought to kill cells via the inhibition of thymidylate synthase and increased use of dUTP in place of TTP during DNA replication, with subsequent excision of high levels of uracil causing the fragmentation of newly synthesized DNA. Using gene-targeted cell lines defective in one or both of the two mammalian uracil-DNA glycosylase repair enzymes, we were able to test this model of FU cytotoxicity. Here, we show that incorporation of FU itself into DNA has been previously underestimated and is a predominant cause of cytotoxicity. FU readily becomes incorporated into the DNA of drug-treated cells, and accumulation of FU in the genome, rather than uracil excision, is correlated with FU cytotoxicity in mammalian cells. Furthermore, the Smug1, but not the Ung, uracil-DNA glycosylase excises FU from DNA and protects against cell killing. The data provides a clearer understanding of the action of FU, suggesting predictive biomarkers of drug response and a mechanism for acquired resistance in tumors.

Viral dispersal in the coastal zone: A method to quantify water quality risk.

Waterborne and shellfish-borne enteric viruses associated with wastewater-polluted coastal waters (e.g. Norovirus, Hepatitis A/E viruses, Adenovirus) represent a major threat to human health. Improved understanding of the locations and periods of heightened risks can help target mitigation measures and improve public health. We developed a river-estuary-coast model to simulate virus dispersal, driven by point source discharges and river flows in combination with tidal forcing. Viral inputs were based on measured wastewater adenovirus concentrations and the model was implemented with or without viral die-off. We applied the model to the Conwy river (North Wales, UK), through the estuary, to the Irish Sea coast where bathing waters and shellfisheries are known to be prone to viral contamination. Using a suite of scenarios, we showed that river flow was the primary control of viral export to the coast. Since the Conwy catchment is short and steep, and the estuary is small and river-dominated, short-duration high intensity 'flash floods' were shown to transport viruses through the estuary and out to sea, despite dilution or die-off effects. Duplicating flow events (i.e., storm clustering) did not double the virus export since the virus re-entered the estuary on the flood tide. The tidal magnitude and timing of high water relative to peak river flow were also important drivers regulating viral dispersal. A worst-case event simulation (i.e., combining high river flows with high viral loading and high spring tide) resulted in increased concentrations of virus at nearby coasts, although the spatial spread was similar to the previous scenarios. Our results suggest that impact models for predicting and mitigating episodes of poor microbiological water quality may require careful representation of the intensity and timings of river flow when evaluating pathogen exposure risk.

Prevalence of structural central nervous system abnormalities in early-onset type 1 diabetes mellitus.

OBJECTIVE: To characterize the effects of severe hypoglycemia on the developing brain in children with early-onset type 1 diabetes mellitus (T1DM). STUDY DESIGN: Children diagnosed with T1DM before age 6 years were studied. Those with prospectively monitored severe hypoglycemia (coma/seizure; n = 32) were compared with age-matched peers (n = 30) with no history of such events using magnetic resonance imaging. Glycemic control (evaluated based on glycated hemoglobin [HbA(lc)] level), episodes of diabetic ketoacidosis (DKA), and clinical variables were monitored continuously since diagnosis in all subjects. RESULTS: Mean HbA(lc) from diagnosis and the duration of T1DM were similar in those with and without a history of severe hypoglycemia (9.0% +/- 0.9% vs 8.8% +/- 0.9%; 7.2 +/- 2.7 years vs 6.7 +/- 2.3 years). A high prevalence of central nervous system (CNS) structural abnormalities was detected (29%), and mesial temporal sclerosis (MTS) was detected in 16% of the total sample (n = 62). The presence of MTS was not associated with a history of severe hypoglycemia or DKA. Analysis of brain matter volumes suggested relatively less gray matter density in those subjects with a history of severe hypoglycemia. CONCLUSIONS: Early age of onset of T1DM per se is associated with a high incidence of CNS abnormalities, particularly MTS, suggesting hippocampal damage. Early-onset severe hypoglycemia may have an effect on gray matter volume.