The relationship between exclusion from school and mental health: a secondary analysis of the British Child and Adolescent Mental Health Surveys 2004 and 2007.

BACKGROUND: Children with poor mental health often struggle at school. The relationship between childhood psychiatric disorder and exclusion from school has not been frequently studied, but both are associated with poor adult outcomes. We undertook a secondary analysis of the British Child and Adolescent Mental Health Surveys from 2004 and its follow-up in 2007 to explore the relationship between exclusion from school and psychopathology. We predicted poorer mental health among those excluded. METHOD: Psychopathology was measured using the Strengths and Difficulties Questionnaire, while psychiatric disorder was assessed using the Development and Well-Being Assessment and applying Diagnostic and Statistical Manual of Mental Disorders Fourth Edition (DSM IV) criteria. Exclusion from school and socio-demographic characteristics were reported by parents. Multi-variable regression models were used to examine the impact of individual factors on exclusion from school or psychological distress. RESULTS: Exclusion from school was commoner among boys, secondary school pupils and those living in socio-economically deprived circumstances. Poor general health and learning disability among children and poor parental mental health were also associated with exclusion. There were consistently high levels of psychological distress among those who had experienced exclusion at baseline and follow-up. CONCLUSIONS: We detected a bi-directional association between psychological distress and exclusion. Efforts to identify and support children who struggle with school may therefore prevent both future exclusion and future psychiatric disorder.

Decreasing the risk of sudden unexpected death in epilepsy: structured communication of risk factors for premature mortality in people with epilepsy.

BACKGROUND AND PURPOSE: Good practice guidelines highlight the importance of making people with epilepsy aware of the risk of premature mortality in epilepsy particularly due to sudden unexpected death in epilepsy (SUDEP). The SUDEP and Seizure Safety Checklist ('Checklist') is a structured risk communication tool used in UK clinics. It is not known if sharing structured information on risk factors allows individuals to reduce SUDEP and premature mortality risks. The aim of this study was to ascertain if the introduction of the Checklist in epilepsy clinics led to individual risk reduction. METHODS: The Checklist was administered to 130 consecutive people with epilepsy attending a specialized epilepsy neurology clinic and 129 attending an epilepsy intellectual disability (ID) clinic within a 4-month period. At baseline, no attendees at the neurology clinic had received formal risk advice, whereas all those attending the ID clinic had received formal risk advice on multiple occasions for 6 years. The Checklist was readministered 1 year later to each group and scores were compared with baseline and between groups. RESULTS: Of 12 risk factors considered, there was an overall reduction in mean risk score for the general (P = 0.0049) but not for the ID (P = 0.322) population. Subanalysis of the 25% of people at most risk in both populations showed that both sets had a significant reduction in risk scores (P < 0.001). CONCLUSION: Structured discussion results in behavioural change that reduces individual risk factors. This impact seems to be higher in those who are at current higher risk. It is important that clinicians share risk information with individuals as a matter of public health and health promotion.

Which children and young people are excluded from school? Findings from a large British birth cohort study, the Avon Longitudinal Study of Parents and Children (ALSPAC).

BACKGROUND: Exclusion from school is increasingly recognized as pertinent to child health. National educational data reveal that boys, children who are looked-after, living in poverty, have special educational needs, or from certain ethnic minorities, are disproportionately excluded from school. As population-based data on the wider characteristics of excluded children are scarce, we aimed to describe predictors of school exclusion in the Avon Longitudinal Study of Parents and Children. METHOD: Avon Longitudinal Study of Parents and Children, a prospective U.K. population-based birth cohort study, collected parent reports of permanent school exclusions by 8 years and parent and self-reports of permanent and fixed-term exclusions in the preceding 12 months at 16 years. Potential risk factors were examined for associations with exclusion using logistic regression, with a focus on child mental health and neurodevelopment. RESULTS: Analyses were based on all available data on 53/8,245 (0.6%) pupils excluded from school by 8 years and 390/4,482 (8.7%) at 16 years. Key factors associated with exclusion at both time points included male gender, lower socio-economic status, maternal psychopathology, mental health and behavioural difficulties, psychiatric disorder, social communication difficulties, language difficulties, antisocial activities, bullying/being bulled, lower parental engagement with education, low school engagement, poor relationship with teacher, low educational attainment, and special educational needs (all p < .05). CONCLUSION: Exclusion from school was associated with child, family and school-related factors identifiable at, or prior to, primary school age. Child health professionals have an important role in the holistic, multidisciplinary assessment of children who are at risk of exclusion from school. Mental health and neurodevelopmental difficulties should be recognized and supported, to improve the health and educational outcomes among this vulnerable group.

Use of Ice-Nucleating Proteins To Improve the Performance of Freeze-Thaw Valves in Microfluidic Devices.

Currently, reliable valving on integrated microfluidic devices fabricated from rigid materials is confined to expensive and complex methods. Freeze-thaw valves (FTVs) can provide a low cost, low complexity valving mechanism, but reliable implementation of them has been greatly hindered by the lack of ice nucleation sites within the valve body's small volume. Work to date has required very low temperatures (on the order of -40 °C or colder) to induce freezing without nucleation sites, making FTVs impractical due to instrument engineering challenges. Here, we report the use of ice-nucleating proteins (INPs) to induce ice formation at relatively warm temperatures in microfluidic devices. Microfluidic channels were filled with buffers containing femtomolar INP concentrations from Pseudomonas syringae. The channels were cooled externally with simple, small-footprint Peltier thermoelectric coolers (TECs), and the times required for channel freezing (valve closure) and thawing (valve opening) were measured. Under optimized conditions in plastic chips, INPs made sub-10 s actuations possible at TEC temperatures as warm as -13 °C. Additionally, INPs were found to have no discernible inhibitory effects in model enzyme-linked immunosorbent assays or polymerase chain reactions, indicating their compatibility with microfluidic systems that incorporate these widely used bioassays. FTVs with INPs provide a much needed reliable valving scheme for rigid plastic devices with low complexity, low cost, and no moving parts on the device or instrument. The reduction in freeze time, accessible actuation temperatures, chemical compatibility, and low complexity make the implementation of compact INP-based FTV arrays practical and attractive for the control of integrated biochemical assays.

Developing tailored positive parenting messages for a clinic-based communication programme.

BACKGROUND: Health care providers fill a central role in the prevention of both child abuse and neglect (CA/N) and unintentional childhood injury. Health communication interventions hold promise for promoting attitudes and behaviours among parents that increase positive parenting practices, which may be linked to decreased rates of intentional and unintentional childhood injuries. This manuscript describes the development of 'RISE Up', an ambulatory clinic-based childhood injury prevention programme that provides tailored, injury prevention print materials to parents of children ages 0-5. METHODS: Fifteen semi-structured key informant interviews were conducted with clinic healthcare providers and staff to develop communication strategies and materials for caregivers. Cognitive response testing was then conducted with 20 caregivers of the priority population to assess all materials. Interviews were recorded, transcribed and analyzed using thematic coding methods. RESULTS: Formative research revealed that health care providers and caregivers were very responsive to messages and materials. Health care providers reported that abuse and neglect were particularly relevant to their patients and noted several benefits to implementing the RISE Up programme in a health care setting. Caregivers generally found messages on reducing the risks of injuries, as well as the graphics displayed in the RISE Up programme to be helpful. CONCLUSIONS: Addressing the common determinants of both intentional and unintentional childhood injury through customized print materials may be a useful component of comprehensive prevention efforts to address childhood injury risk with greater impact. Providers and parents responded favourably to this communication strategy.

Gene transcripts associated with muscle strength: a CHARGE meta-analysis of 7,781 persons.

Lower muscle strength in midlife predicts disability and mortality in later life. Blood-borne factors, including growth differentiation factor 11 (GDF11), have been linked to muscle regeneration in animal models. We aimed to identify gene transcripts associated with muscle strength in adults. Meta-analysis of whole blood gene expression (overall 17,534 unique genes measured by microarray) and hand-grip strength in four independent cohorts (n = 7,781, ages: 20-104 yr, weighted mean = 56), adjusted for age, sex, height, weight, and leukocyte subtypes. Separate analyses were performed in subsets (older/younger than 60, men/women). Expression levels of 221 genes were associated with strength after adjustment for cofactors and for multiple statistical testing, including ALAS2 (rate-limiting enzyme in heme synthesis), PRF1 (perforin, a cytotoxic protein associated with inflammation), IGF1R, and IGF2BP2 (both insulin like growth factor related). We identified statistical enrichment for hemoglobin biosynthesis, innate immune activation, and the stress response. Ten genes were associated only in younger individuals, four in men only and one in women only. For example, PIK3R2 (a negative regulator of PI3K/AKT growth pathway) was negatively associated with muscle strength in younger (<60 yr) individuals but not older (≥ 60 yr). We also show that 115 genes (52%) have not previously been linked to muscle in NCBI PubMed abstracts. This first large-scale transcriptome study of muscle strength in human adults confirmed associations with known pathways and provides new evidence for over half of the genes identified. There may be age- and sex-specific gene expression signatures in blood for muscle strength.

The NCS-LSD cohort study: a description of the methods and analyses used to assess the long-term effectiveness of enzyme replacement therapy and substrate reduction therapy in patients with lysosomal storage disorders.

Lysosomal storage disorders (LSDs) comprise more than 50 extremely rare, inherited metabolic diseases resulting from a deficiency of specific lysosomal enzymes required for normal macromolecular metabolism. The National Collaborative Study for Lysosomal Storage Disorders (NCS-LSD), was a longitudinal cohort study which collected prospective and retrospective clinical data, and patient-reported data from adults and children with a confirmed diagnosis of Gaucher disease, Fabry disease, mucopolysaccharidosis type I (MPS I), mucopolysaccharidosis type II (MPS II), Pompe disease and Niemann Pick disease type C (NPC) in the UK. The study aimed to determine the natural history of these conditions and estimate the effectiveness and cost of therapies. Clinical outcomes were chosen to reflect disease progression. Age- and gender-adjusted treatment effects were estimated using generalised linear mixed models. Treated patients contributed data before and during treatment while untreated patients contributed natural history data. A total of 711 adults and children were recruited to this study from the seven LSD treatment centres in England. Data was collected from 2008 to 2011. This paper describes the methods used to collect and analyse clinical data for this study. The clinical findings are reported separately in a series of condition-specific articles in this issue.

Long-term effectiveness of enzyme replacement therapy in adults with Gaucher disease: results from the NCS-LSD cohort study.

OBJECTIVES: To determine the effectiveness of enzyme replacement therapies (ERT) for adults with Gaucher disease (GD). DESIGN: A longitudinal, multi-centre cohort study, including prospective and retrospective clinical data. Age- and gender-adjusted treatment effects were estimated using generalised linear mixed models. Treated patients contributed data before and during treatment. Untreated patients contributed natural history data. PARTICIPANTS: Consenting adults (N = 150, aged 16 to 83 years) with a diagnosis of GD who attended a specialist treatment centre in England. At recruitment, 131 patients were receiving ERT (mean treatment duration, 10.8 years; range 0-18 years). OUTCOME MEASURES: Clinical outcomes chosen to reflect disease progression, included platelet count; haemoglobin; absence/presence of bone pain; spleen and liver volumes and AST levels. RESULTS: One hundred and fifty adults were recruited. Duration of ERT was associated with statistically significant improvements in platelet count (p < 0.001), haemoglobin (p < 0.001), liver and spleen volumes (p < 0.001) and AST levels (p = 0.02). CONCLUSIONS: These data provide further evidence of the long-term effectiveness of ERT in adults with GD.

Long-term effectiveness of enzyme replacement therapy in Fabry disease: results from the NCS-LSD cohort study.

OBJECTIVES: To determine the effectiveness of enzyme replacement therapy (ERT) for adults and children with Fabry disease. DESIGN: Cohort study including prospective and retrospective clinical data. Age- and gender-adjusted treatment effects were estimated using generalised linear mixed models. Treated patients contributed data before and during treatment and untreated patients contributed natural history data. PARTICIPANTS: Consenting adults (N = 289) and children (N = 22) with a confirmed diagnosis of Fabry disease attending a specialist Lysosomal Storage Disorder treatment centre in England. At recruitment 211 adults and seven children were on ERT (range of treatment duration, 0 to 9.7 and 0 to 4.2 years respectively). OUTCOME MEASURES: Clinical outcomes chosen to reflect disease progression included left ventricular mass index (LVMI); proteinuria; estimated glomerular filtration rate (eGFR); pain; hearing and transient ischaemic attacks (TIA)/stroke. RESULTS: We found evidence of a statistically significant association between time on ERT and a small linear decrease in LVMI (p = 0.01); a reduction in the risk of proteinuria after adjusting for angiotensin-converting enzyme inhibitors and angiotensin receptor blockers (p < 0.001) and a small increase in eGFR in men and women without pre-treatment proteinuria (p = 0.01 and p < 0.001 respectively). The same analyses in children provided no statistically significant results. No associations between time on ERT and pain, risk of needing a hearing aid, or risk of stroke or TIAs, were found. CONCLUSIONS: These data provide some further evidence on the long-term effectiveness of ERT in adults with Fabry disease, but evidence of effectiveness could not be demonstrated in children.

Long-term effectiveness of enzyme replacement therapy in children with Gaucher disease: results from the NCS-LSD cohort study.

OBJECTIVES: To determine the effectiveness of enzyme replacement therapies (ERT) for children with Gaucher disease (GD). DESIGN: A longitudinal cohort study including prospective and retrospective clinical data. Age- and gender-adjusted treatment effects were estimated using generalised linear mixed models. Children on treatment contributed data before and during treatment. Children not on treatment contributed natural history data. PARTICIPANTS: Consenting children (N = 25, aged 1.1 to 15.6 years) with a diagnosis of GD (14 with GD1 and 11 with GD3) who attended a specialist treatment centre in England. At recruitment, 24 patients were receiving ERT (mean treatment duration, 5.57 years; range 0-13.7 years). OUTCOME MEASURES: Clinical outcomes chosen to reflect disease progression, included platelet count; haemoglobin and absence/presence of bone pain. RESULTS: Duration of ERT was associated with statistically significant improvements in platelet count (p < 0.001), haemoglobin (p < 0.001), and reported bone pain (p = 0.02). The magnitude of effect on haematological parameters was greater in children with GD3 than in those with GD1. CONCLUSIONS: These data provide further evidence of the long-term effectiveness of ERT in children with GD.

Effectiveness of enzyme replacement therapy in adults with late-onset Pompe disease: results from the NCS-LSD cohort study.

OBJECTIVES: To determine the effectiveness of enzyme replacement therapy (ERT) for adults with late-onset Pompe disease. DESIGN: A longitudinal cohort study including prospective and retrospective clinical outcome data. Age- and gender-adjusted treatment effects were estimated using generalised linear mixed models. Treated patients contributed data before and during treatment. Untreated patients contributed natural history data. PARTICIPANTS: Consenting adults (N = 62) with a diagnosis of late-onset Pompe disease who attended a specialist treatment centre in England. This cohort represented 83 % of all patients in the UK with a confirmed diagnosis of this rare condition. At study entry, all but three patients were receiving ERT (range of treatment duration, 0 to 3.1 years). OUTCOME MEASURES: Percent predicted forced vital capacity (%FVC); ventilation dependency; mobility; 6 min walk test (6MWT); muscle strength and body mass index (BMI). RESULTS: An association was found between time on ERT and significant increases in the distance walked in the 6MWT (p < 0.001) and muscle strength scores (p < 0.001). Improvements in both these measures were seen over the first 2 years of treatment with ERT. No statistically significant relationship was found between time on ERT and respiratory function or in BMI. CONCLUSIONS: These data provide some further evidence of the effectiveness of ERT in adults with late-onset Pompe disease. SYNOPSIS: The results of this longitudinal cohort study of 62 adults with late-onset Pompe disease, provide further evidence on the effectiveness of ERT in this rare condition.

Microfluidic amperometric sensor for analysis of nitric oxide in whole blood.

Standard photolithographic techniques and a nitric oxide (NO) selective xerogel polymer were utilized to fabricate an amperometric NO microfluidic sensor with low background noise and the ability to analyze NO levels in small sample volumes (~250 µL). The sensor exhibited excellent analytical performance in phosphate buffered saline, including a NO sensitivity of 1.4 pA nM(-1), a limit of detection (LOD) of 840 pM, and selectivity over nitrite, ascorbic acid, acetaminophen, uric acid, hydrogen sulfide, ammonium, ammonia, and both protonated and deprotonated peroxynitrite (selectivity coefficients of -5.3, -4.2, -4.0, -5.0, -6.0, -5.8, -3.8, -1.5, and -4.0, respectively). To demonstrate the utility of the microfluidic NO sensor for biomedical analysis, the device was used to monitor changes in blood NO levels during the onset of sepsis in a murine pneumonia model.

Laser-based directed release of array elements for efficient collection into targeted microwells.

A cell separation strategy capable of the systematic isolation and collection of moderate to large numbers (25-400) of single cells into a targeted microwell is demonstrated. An array of microfabricated, releasable, transparent micron-scale pedestals termed pallets and an array of microwells in poly(dimethylsiloxane) (PDMS) were mated to enable selective release and retrieval of individual cells. Cells cultured on a pallet array mounted on a custom designed stage permitted the array to be positioned independently of the microwell locations. Individual pallets containing cells were detached in a targeted fashion using a pulsed Nd:YAG laser. The location of the laser focal point was optimized to transfer individual pallets to designated microwells. In a large-scale sort (n = 401), the accuracy, defined as placing a pallet in the intended well, was 94% and the collection efficiency was 100%. Multiple pallets were observed in only 4% of the targeted wells. In cell sorting experiments, the technique provided a yield and purity of target cells identified by their fluorescence signature of 91% and 93%, respectively. Cell viability based on single-cell cloning efficiency at 72 h post collection was 77%.

An evidence-based approach to provide essential and desirable components to develop surveys on Sudden Unexpected Death in Epilepsy (SUDEP) for doctors: A focused review.

Sudden Unexpected Death in Epilepsy (SUDEP) is a major concern for people with epilepsy, their families, their care givers, and medical professionals. There is inconsistency in the SUDEP counselling doctors provide, compared to what is recommended in clinical guidelines. Numerous national and international surveys have highlighted how epilepsy professionals, usually doctors, deliver SUDEP risk counselling, particularly, when they deliver it and to whom. These surveys help understand the unmet need, develop suitable strategies, and raise awareness among clinicians with the eventual goal to reduce SUDEPs. However, there is no standardised survey or essential set of questions identified that can be used to evaluate SUDEP counselling practice globally. This focused review analyses the content of all published SUDEP counselling surveys for medical professionals (n=16) to date covering over 4000 doctors across over 30 countries and five continents. It identifies 36 question themes across three topics. The questions are then reviewed by an expert focus group of SUDEP communication experts including three doctors, an expert statistician and SUDEP Action, an UK based charity specialising in epilepsy deaths with a pre-set criterion. The review and focus group provide ten essential questions that should be included in all future surveys inquiring on SUDEP counselling. They could be used to evaluate current practice and compare findings over time, between services, across countries and between professional groups. They are provided as a template to download and use. The review also explores if there is a continued need in future for similar surveys to justify this activity.

Fabrication of microfluidic devices containing patterned microwell arrays.

A rapid fabrication and prototyping technique to incorporate microwell arrays with sub-10 µm features within a single layer of microfluidic circuitry is presented. Typically, the construction of devices that incorporate very small architecture within larger components has required the assembly of multiple elements to form a working device. Rapid, facile production of a working device using only a single layer of molded polydimethylsiloxane (PDMS) and a glass support substrate is achieved with the reported fabrication technique. A combination of conventional wet-chemical etching for larger (≥20 µm) microchannel features and focused ion beam (FIB) milling for smaller (≤10 µm) microwell features was used to fabricate a monolithic glass master mold. PDMS/glass hybrid chips were then produced using simple molding and oxygen plasma bonding methods. Microwell structures were loaded with 3 µm antibody-functionalized dye-encoded polystyrene spheres, and a sandwich immunoassay for common cytokines was performed to demonstrate proof-of-principle. Potential applications for this device include highly parallel multiplexed sandwich immunoassays, DNA/RNA hybridization analyses, and enzyme linked immunosorbent assay (ELISA). The fabrication technique described can be used for rapid prototyping of devices wherever submicrometer- to micrometer-sized features are incorporated into a microfluidic device.

High electric field strength two-dimensional peptide separations using a microfluidic device.

New instrumentation has been developed to improve the resolution, efficiency, and speed of microfluidic 2D separations using MEKC coupled to high field strength CE. Previously published 2D separation instrumentation [Ramsey, J. D. et al., Anal. Chem. 2003, 75, 3758-3764] from our group was limited to a maximum potential difference of 8.4 kV, resulting in an electric field strength of only approximately 200 V/cm in the first dimension. The circuit described in this report has been designed to couple a higher voltage supply with a rapidly switching, lower voltage supply to utilize the best features of each. Voltages applied in excess of 20 kV lead to high electric field strength separations in both dimensions, increasing the separation resolution, efficiency, and peak capacity while reducing the required analysis time. Detection rates as high as six peptides per second (based on total analysis time) were observed for a model protein tryptic digest separation. Additionally, higher applied voltages used in conjunction with microfluidic chips with longer length channels maintained higher electric field strengths and produced peak capacities of over 4000 for some separations. Total separation time in these longer channel devices was comparable to that obtained in short channels at low field strength; however, resolving power improved approximately threefold.

Tackling increased risks in older adults with intellectual disability and epilepsy: Data from a national multicentre cohort study.

PURPOSE: People with intellectual disabilities (ID) suffer multimorbidity, polypharmacy and excess mortality at a younger age than general population. Those with ID and epilepsy are at higher risk of worse clinical outcomes than their peers without epilepsy. In the ID population the health profile of those aged ≥40 years can be compared to those aged over 65 in the general population. To date there is limited data available to identify clinical characteristics and risk factors in older adults (≥40 years) with ID and epilepsy. METHODS: The Epilepsy in ID National Audit (Epi-IDNA) identified 904 patients with ID and epilepsy from 10 sites in England and Wales. This subsequent analysis of the Epi-IDNA cohort compared the 405 adults over 40 years with 499 adults ≥18 years aged under 40 years. Comparison was made between clinical characteristics and established risk factors using the Sudden Unexpected Death in Epilepsy (SUDEP) and Seizure Safety Checklist. RESULTS: The older adults' cohort had significantly higher levels of co-morbid physical health conditions, mental health conditions, anti-seizure medications (median 5), and antipsychotics compared to the younger cohort. The older group were significantly less likely to be diagnosed with a co-morbid neurodevelopmental disorder, and to have an epilepsy care plan. CONCLUSION: This is the largest study to date focused on adults with ID and epilepsy over 40 years. The ≥40 years cohort compared to the younger group has higher levels of clinical risk factors associated with multi-morbidity, potential iatrogenic harm and premature mortality with worse clinical oversight mechanisms.

Monolithic integration of two-dimensional liquid chromatography-capillary electrophoresis and electrospray ionization on a microfluidic device.

A microfluidic device capable of two-dimensional reversed-phase liquid chromatography-capillary electrophoresis with integrated electrospray ionization (LC-CE-ESI) for mass spectrometry (MS)-based proteomic applications is described. Traditional instrumentation was used for the LC sample injection and delivery of the LC mobile phase. The glass microfabricated device incorporated a sample-trapping region and an LC channel packed with reversed-phase particles. Rapid electrokinetic injections of the LC effluent into the CE dimension were performed at a cross-channel intersection. The CE separation channel terminated at a corner of the square device, which functioned as an integrated electrospray tip. In addition to LC-CE-ESI, this device was used for LC-ESI without any instrumental modifications. To evaluate the system, LC-MS and LC-CE-MS analyses of protein digests were performed and compared.

National mortality rates from chronic liver disease and consumption of alcohol and pig meat.

A correlation between national pig-meat consumption and mortality rates from chronic liver disease (CLD) across developed countries was reported in 1985. One possible mechanism explaining this may be hepatitis E infection spread via pig meat. We aimed to re-examine the original association in more recent international data. Regression models were used to estimate associations between national pig-meat consumption and CLD mortality, adjusting for confounders. Data on CLD mortality, alcohol consumption, hepatitis B virus (HBV) and hepatitis C virus (HCV) seroprevalence for 18 developed countries (1990-2000) were obtained from WHO databases. Data on national pig-meat and beef consumption were obtained from the UN database. Univariate regression showed that alcohol and pig-meat consumption were associated with mortality from CLD, but beef consumption, HBV and HCV seroprevalence were not. A 1 litre per capita increase in alcohol consumption was associated with an increase in mortality from CLD in excess of 1.6 deaths/100,000 population. A 10 kg higher national annual average per capita consumption of pork meat was associated with an increase in mortality from CLD of between 4 and 5 deaths/100,000 population. Multivariate regression showed that alcohol, pig-meat consumption and HBV seroprevalence were independently associated with mortality from CLD, but HCV seroprevalence was not. Pig-meat consumption remained independently associated with mortality from CLD in developed countries in the 1990-2000 period. Further work is needed to establish the mechanism.

Spatially isolated reactions in a complex array: using magnetic beads to purify and quantify nucleic acids with digital and quantitative real-time PCR in thousands of parallel microwells.

Quantitative real-time PCR (qPCR) has been the standard for nucleic acid quantification as it has a large dynamic range and good sensitivity. Digital PCR is rapidly supplanting qPCR in many applications as it provides excellent quantitative precision. However, both techniques require extensive sample preparation, and highly multiplexed assays that quantify multiple targets can be difficult to design and optimize. Here we describe a new nucleic acid quantification method that we call Spatially Isolated Reactions in a Complex Array (SIRCA), a highly parallel nucleic acid preparation, amplification, and detection approach that uses superparamagnetic microbeads in an array of thousands of 100 fL microwells to simplify sample purification and reduce reagent dispensing steps. Primers, attached to superparamagnetic microbeads through a thermo-labile bond, capture and separate target sequences from the sample. The microbeads are then magnetically loaded into a microwell array such that wells predominately contain a single bead. Master mix, lacking primers, is added before sealing the reaction wells with hydrophobic oil. Thermocycling releases the primer pair from the beads during PCR amplification. At low target concentrations, most beads capture, on average, less than one target molecule, and precise, digital PCR quantification can be derived from the percentage of positive reactions. At higher concentrations, qPCR signal is used to determine the average number of target molecules per reaction, significantly extending the dynamic range beyond the digital saturation point. We demonstrate that SIRCA can quantify DNA and RNA targets using thousands of parallel reactions, achieving attomolar limits of detection and a linear dynamic range of 105. The work reported here is a first step towards multiplexed SIRCA assays.