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Diagnosis of the autoimmune disease type 1 diabetes (T1D) is preceded by the appearance of circulating autoantibodies to pancreatic islets. However, almost nothing is known about events leading to this islet autoimmunity. Previous epidemiological and genetic data have associated viral infections and antiviral type I interferon (IFN) immune response genes with T1D. Here, we first used DNA microarray analysis to identify IFN-β–inducible genes in vitro and then used this set of genes to define an IFN-inducible transcriptional signature in peripheral blood mononuclear cells from a group of active systemic lupus erythematosus patients (n = 25). Using this predefined set of 225 IFN signature genes, we investigated the expression of the signature in cohorts of healthy controls (n = 87), patients with T1D (n = 64), and a large longitudinal birth cohort of children genetically predisposed to T1D (n = 109; 454 microarrayed samples). Expression of the IFN signature was increased in genetically predisposed children before the development of autoantibodies (P = 0.0012) but not in patients with established T1D. Upregulation of IFN-inducible genes was transient, temporally associated with a recent history of upper respiratory tract infections (P = 0.0064), and marked by increased expression of SIGLEC-1 (CD169), a lectin-like receptor expressed on CD14+ monocytes. DNA variation in IFN-inducible genes altered T1D risk (P = 0.007), as exemplified by IFIH1, one of the genes in our IFN signature for which increased expression is a known risk factor for disease. These findings identify transient increased expression of type I IFN genes in preclinical diabetes as a risk factor for autoimmunity in children with a genetic predisposition to T1D.

The fraction of copper not bound to ceruloplasmin seems altered in Alzheimer's disease (AD). We have addressed this notion evaluating all the studies carried out from 1996 until March 2013 by means of meta-analysis. We performed our analysis on diverse indices evaluating the relationship between copper and ceruloplasmin in general circulation, namely 'Non-Cp copper', '% Non-Cp copper', and 'Adjusted copper'. For Non-Cp copper and % Non-Cp copper, the correct stoichiometry between copper and ceruloplasmin (6-8 atoms of copper for each ceruloplasmin molecule) in healthy controls has been adopted as criterion for the study to be included in the meta-analysis evaluating data with the canonic Walshe's formula for Non-Cp copper. Copper to ceruloplasmin ratio (Cu:Cp), which is an internal quality control check for ceruloplasmin calibration, was used as an index of the actual stoichiometry in the specimens. Adjusted (Adj-Cp) copper, even though less reliable, was calculated, allowing the evaluation of all the studies selected. An additional meta-analysis of systemic total copper was re-calculated accounting for all the studies carried out from 1983 to March 2013. Ten studies were analyzed in the meta-analysis for Non-Cp copper and % Non-Cp copper reaching a pooled total of 599 AD subjects and 867 controls. For Adj-Cp copper, 14 studies were analyzed with a pooled total of 879 AD and 1,712 controls. 27 studies were considered for systemic total copper meta-analysis, with a pooled total of 1,393 AD and 2,159 controls. All the copper indices analyzed were significantly higher in AD subjects compared to healthy controls.

BACKGROUND: We evaluated the utility of longitudinal measures of plasma amyloid-β (Aβ) as a means to identify pre-symptomatic cognitive decline in Alzheimer's disease (AD) when coupled to neuroimaging and neuropsychological parameters. METHODS: Participants from the Australian Imaging, Biomarkers and Lifestyle (AIBL) study were grouped based upon cognitive change and changes in measurable levels of neocortical amyloid over 36 months. Participants were classified as those who transitioned for cognitive decline and change in neocortical amyloid, those healthy controls that did not transition, and stable AD participants over 36 months. RESULTS: Comparisons of plasma Aβ levels between the transition and non-transitional groups showed Aβ1-42 and the Aβ1-42/Aβ1-40 ratio were significantly decreased at baseline (p = 0.008 and p = 0.002, respectively) and at 18 months (p = 0.003 and p = 0.004, respectively). Both measures of neocortical amyloid and two previously published composite scores validated the creation of the novel transitional grouping (p < 0.0001). In addition Aβn-42 performed well as a longitudinal prognostic indicator of transition toward cognitive decline, with a significant decrease in the transition group at the 18 month time point (p = 0.01). CONCLUSION: We demonstrated that baseline plasma Aβ1-42 and the Aβ1-42/Aβ1-40 ratio were putative biomarkers indicative of cognitive decline and validated this result using 18 month data. We created a novel transitional grouping and validated this measure using published measures of neocortical amyloid and composite memory scores. These findings suggest that longitudinal plasma Aβ could contribute to a pre-symptomatic biomarker panel for AD.

The availability of cross-platform, large-scale genomic data has enabled the investigation of complex biological relationships for many cancers. Identification of reliable cancer-related biomarkers requires the characterization of multiple interactions across complex genetic networks. MicroRNAs are small non-coding RNAs that regulate gene expression; however, the direct relationship between a microRNA and its target gene is difficult to measure. We propose a novel Bayesian model to identify microRNAs and their target genes that are associated with survival time by incorporating the microRNA regulatory network through prior distributions. We assume that biomarkers involved in regulatory networks are likely associated with survival time. We employ non-local prior distributions and a stochastic search method for the selection of biomarkers associated with the survival outcome. We use KEGG pathway information to incorporate correlated gene effects within regulatory networks. Using simulation studies, we assess the performance of our method, and apply it to experimental data of kidney renal cell carcinoma (KIRC) obtained from The Cancer Genome Atlas. Our novel method validates previously identified cancer biomarkers and identifies biomarkers specific to KIRC progression that were not previously discovered. Using the KIRC data, we confirm that biomarkers involved in regulatory networks are more likely to be associated with survival time, showing connections in one regulatory network for five out of six such genes we identified.

Inflammation is a hallmark of Alzheimer's disease (AD). Whether directly involved in the pathogenesis, or a downstream consequence of neuronal death, the blood neutrophil-lymphocyte ratio (NLR) is reported to be a putative, non-invasive peripheral biomarker for AD. The aim of this study was to re-evaluate the diagnostic utility of longitudinal measures of the NLR. The NLR was stable across all time-points and weakly correlated with neocortical amyloid burden (R=0.21 at baseline, 0.27 at 18 months, 0.20 at 36 months and 0.10 at 54 months). Cross-sectionally, the NLR was significantly elevated in AD participants as compared to HC participants at baseline (p0.0001), 18 months (p0.0001), 36 months (p=0.002) and at 54 months (p=0.007), however only prior to adjustment for age, sex and APOEε4 allele status (p0.05 at all time-points except for 18 months; p0.0001). Longitudinally, the NLR was not significantly different between HC and AD participants (p0.05) adjusted for age, sex and APOEε4 allele status. Comparing the NLR between cognitive transition groups over time (transition towards an AD type dementia), there was no significant difference in the NLR levels between those participants, who did not transition and those participants who did transition, or those in the stable AD group after adjusting for age, sex and APOEε4 allele status (p0.05). Despite inflammation being a hallmark in AD and previous reports showing that the NLR can discriminate HC from AD patients, our results suggest that the sensitivity of the NLR itself is not robust enough for diagnostic utility. We identified significant relationships cross sectionally (p0.05 at baseline, 18 months and 36 months) between the NLR and neocortical amyloid burden, but this relationship was lost after longitudinal analyses (p0.5). The NLR also had limited association with cognitive decline, although in our cohort, the number of participants transitioning was relatively small. In conclusion, the NLR may reflect AD-related inflammatory processes in the periphery, but age and sex are dominant covariates which need to be controlled for in population-based screening.

*Department of Gastroenterology, Royal Brisbane and Women’s Hospital, Brisbane, Queensland, Australia. Department of Gastroenterology, St Vincent’s Hospital, Sydney, NSW, Australia. The Australian E-Health Research Centre, Royal Brisbane and Women’s Hospital, Brisbane, Queensland, Australia. CSIRO Preventative Health Flagship, Parkville, Melbourne, Victoria, Australia. CSIRO Mathematics and Information Sciences, Macquarie University, Sydney, NSW, Australia. **IBD Group, Queensland Institute of Medical Research and University of Queensland School of Medicine, Herston Campus, Brisbane, Queensland, Australia. E-mail: anthony.croft@gmail.com

Peroxisome proliferator-activated receptor (PPAR) γ is a transcription factor, highly expressed in colonic epithelial cells, adipose tissue and macrophages, with an important role in the regulation of inflammatory pathways. The common PPARγ variants C161T and Pro12Ala have recently been associated with Ulcerative Colitis (UC) and an extensive UC phenotype respectively, in a Chinese population. PPARγ Pro12Ala variant homozygotes appear to be protected from the development of Crohn's disease (CD) in European Caucasians.A case-control study was performed for both variants (CD n=575, UC n=306, Controls n=360) using a polymerase chain reaction (PCR)-restriction fragment length polymorphism analysis in an Australian IBD cohort. A transmission disequilibrium test was also performed using CD trios for the PPARγ C161T variant. Genotype-phenotype analyses were also undertaken.There was no significant difference in genotype distribution data or allele frequency between CD and UC patients and controls. There was no difference in allele transmission for the C161T variant. No significant relationship between the variants and disease location was observed.We were unable to replicate in a Caucasian cohort the recent association between PPARγ C161T and UC or between PPARγ Pro12Ala and an extensive UC phenotype in a Chinese population. There are significant ethnic differences in genetic susceptibility to IBD and its phenotypic expression.

RUNX2 is an essential transcription factor required for skeletal development and cartilage formation. Haploinsufficiency of RUNX2 leads to cleidocranial displaysia (CCD) a skeletal disorder characterised by gross dysgenesis of bones particularly those derived from intramembranous bone formation. A notable feature of the RUNX2 protein is the polyglutamine and polyalanine (23Q/17A) domain coded by a repeat sequence. Since none of the known mutations causing CCD characterised to date map in the glutamine repeat region, we hypothesised that Q-repeat mutations may be related to a more subtle bone phenotype. We screened subjects derived from four normal populations for Q-repeat variants. A total of 22 subjects were identified who were heterozygous for a wild type allele and a Q-repeat variant allele: (15Q, 16Q, 18Q and 30Q). Although not every subject had data for all measures, Q-repeat variants had a significant deficit in BMD with an average decrease of 0.7SD measured over 12 BMD-related parameters (p = 0.005). Femoral neck BMD was measured in all subjects (-0.6SD, p = 0.0007). The transactivation function of RUNX2 was determined for 16Q and 30Q alleles using a reporter gene assay. 16Q and 30Q alleles displayed significantly lower transactivation function compared to wild type (23Q). Our analysis has identified novel Q-repeat mutations that occur at a collective frequency of about 0.4%. These mutations significantly alter BMD and display impaired transactivation function, introducing a new class of functionally relevant RUNX2 mutants.

Objective To identify plasma biomarkers for the diagnosis of Alzheimer disease (AD). Design Baseline plasma screening of 151 multiplexed analytes combined with targeted biomarker and clinical pathology data. Setting General community-based, prospective, longitudinal study of aging. Participants A total of 754 healthy individuals serving as controls and 207 participants with AD from the Australian Imaging Biomarker and Lifestyle study (AIBL) cohort with identified biomarkers that were validated in 58 healthy controls and 112 individuals with AD from the Alzheimer Disease Neuroimaging Initiative (ADNI) cohort. Results A biomarker panel was identified that included markers significantly increased (cortisol, pancreatic polypeptide, insulinlike growth factor binding protein 2, β2 microglobulin, vascular cell adhesion molecule 1, carcinoembryonic antigen, matrix metalloprotein 2, CD40, macrophage inflammatory protein 1α, superoxide dismutase, and homocysteine) and decreased (apolipoprotein E, epidermal growth factor receptor, hemoglobin, calcium, zinc, interleukin 17, and albumin) in AD. Cross-validated accuracy measures from the AIBL cohort reached a mean (SD) of 85% (3.0%) for sensitivity and specificity and 93% (3.0) for the area under the receiver operating characteristic curve. A second validation using the ADNI cohort attained accuracy measures of 80% (3.0%) for sensitivity and specificity and 85% (3.0) for area under the receiver operating characteristic curve. Conclusions This study identified a panel of plasma biomarkers that distinguish individuals with AD from cognitively healthy control subjects with high sensitivity and specificity. Cross-validation within the AIBL cohort and further validation within the ADNI cohort provides strong evidence that the identified biomarkers are important for AD diagnosis. Alzheimer disease (AD) is the most common form of dementia, affecting more than 27 million persons worldwide and predicted to affect 86 million people by the year 2050.1 The disease is characterized morphologically by an overall loss of synapses and neurons and an overall reduction in brain volume.2 The identification of peripheral biomarkers of the disease process leading to an effective and early diagnostic test for AD would allow for presymptomatic detection of disease and would be valuable for monitoring the efficacy of disease interventions during clinical trials. Currently, cerebrospinal fluid (CSF) has provided the most promising source of validated AD biomarkers. A decline in β-amyloid (Aβ) levels in the CSF has been reported to help distinguish between patients with AD and elderly individuals without AD.3- 7 In particular, the longer 42–amino acid isoform Aβ1-42 in combination with levels of the phosphorylated microtubule-associated protein tau (p-tau) has been advocated for use in the diagnosis of AD.8 Perrin and colleagues9 identified other biomarkers, including neuronal cell adhesion molecule, YKL-40 (YKL represents the first 3 N-terminal amino acids and 40 denotes molecular mass in kilodaltons; also known as human chitinase 3–like 1, cartilage glycoprotein 39, and chondrex), chromogranin A, and carnosinase I, which improved the diagnostic accuracy of Aβ1-42 and p-tau. Craig-Schapiro and colleagues10 used a biomarker discovery method from rules-based medicine (RBM) to identify novel CSF biomarkers that distinguish between very mild dementia, mild dementia, and no dementia. Compared with CSF, blood analysis has advantages as an approach to population-based disease screening because it is simpler and less invasive. As such, there has been strong interest in obtaining usable blood-based biomarkers for AD diagnosis. Ray et al11 identified a panel of 18 biomarkers from a group of 120 signaling proteins and, more recently, O’Bryant and colleagues12,13 used a panel from RBM to identify a list of 30 biomarkers to detect AD. Soares and colleagues14 describe a list of biomarkers identified within the Alzheimer Disease Neuroimaging Initiative (ADNI) cohort in this issue. Herein, we describe a short articulated panel of blood-based biomarker candidates obtained by comparing clinical factors with blood-based measures from the Australian Imaging, Biomarkers and Lifestyle (AIBL) study, a prospective longitudinal cohort study of aging in Australia.15 This biomarker panel was then validated in the ADNI cohort. The biomarkers identified in this cross-sectional analysis of data from the AIBL study may contribute toward the development of a blood-based diagnostic test, which together with appropriate imaging phenotypes may deliver an accurate means to diagnose AD.

Background Crohn's disease (CD) exhibits significant clinical heterogeneity. Classification systems attempt to describe this; however, their utility and reliability depends on inter-observer agreement (IOA). We therefore sought to evaluate IOA using the Montreal Classification (MC). Methods De-identified clinical records of 35 CD patients from 6 Australian IBD centres were presented to 13 expert practitioners from 8 Australia and New Zealand Inflammatory Bowel Disease Consortium (ANZIBDC) centres. Practitioners classified the cases using MC and forwarded data for central blinded analysis. IOA on smoking and medications was also tested. Kappa statistics, with pre-specified outcomes of κ > 0.8 excellent; 0.61–0.8 good; 0.41–0.6 moderate and ≤ 0.4 poor, were used. Results 97% of study cases had colonoscopy reports, however, only 31% had undergone a complete set of diagnostic investigations (colonoscopy, histology, SB imaging). At diagnosis, IOA was excellent for age, κ = 0.84; good for disease location, κ = 0.73; only moderate for upper GI disease (κ = 0.57) and disease behaviour, κ = 0.54; and good for the presence of perianal disease, κ = 0.6. At last follow-up, IOA was good for location, κ = 0.68; only moderate for upper GI disease (κ = 0.43) and disease behaviour, κ = 0.46; but excellent for the presence/absence of perianal disease, κ = 0.88. IOA for immunosuppressant use ever and presence of stricture were both good (κ = 0.79 and 0.64 respectively). Conclusion IOA using MC is generally good; however some areas are less consistent than others. Omissions and inaccuracies reduce the value of clinical data when comparing cohorts across different centres, and may impair the ability to translate genetic discoveries into clinical practice.

Aberrant expression of Eph and ephrin proteins in human cancers is extensively documented. However, data are frequently limited to one gene and therefore incomplete and in some instances conflicting. We analysed expression of all Eph and ephrin genes in colorectal cancer (CRC) cell lines and 153 clinical specimens, providing for the first time a comprehensive analysis of this system in CRC. Eph/ephrin mRNA expression was assessed by quantitative real-time PCR and correlated with protein expression (flow cytometry, Western blotting and immunocytochemistry). These data show that EphA1, EphA2, EphB2 and EphB4 were significantly over expressed in CRC. In all cases, at least one Eph gene was found in normal colon (EphA1, EphA2, EphB2, EphB4), where expression was observed at high levels in most CRCs. However, other Eph gene expression was lost in individual CRCs compared to the corresponding normal, EphA7 being a striking example. Loss of expression was more common in advanced disease and thus correlated with poor survival. This is consistent with the redundant functionality of Eph receptors, such that expression of a single Eph gene is sufficient for effector function. Overall, the data suggest a progressive loss of expression of individual Eph genes suggesting that individual CRCs need to be phenotyped to determine which Eph genes are highly expressed. Targeted therapies could then be selected from a group of specific antibodies, such as those developed for EphA1.

This randomised, double-blind, placebo-controlled trial assessed the efficacy and tolerability of pregabalin to alleviate the neuropathic component of moderate to severe burn pain. Patients aged 18 to 65 years admitted to a burns unit with a 5% or greater total body surface area burn injury were screened to participate in the trial. Using the Neuropathic Pain Scale (NPS), patients scoring 4 or higher on 'hot' pain or 'sharp' pain were invited to participate. Consenting patients were randomly assigned to receive pregabalin or placebo for 28 days with individual dose titration commencing at 75 mg twice daily to a maximum pregabalin dose of 300 mg twice daily. The primary outcome measure was the patients' daily response to the sharp and hot pain of the NPS. Secondary outcome measures included the remaining elements of the NPS, daily opioid requirement, length of hospital stay, pain at 6 months, and side effects of nausea, vomiting, drowsiness and giddiness. For patients administered pregabalin, the primary outcome measures hot (P = .01) and sharp (P = .04) pain were significantly reduced compared with those in patients administered placebo. Secondary outcome measures of itch, unpleasantness, surface pain, and procedural pain were significantly lower (P < .05) in the pregabalin group. Adverse effects were uncommon, with no difference between the treatment groups. There was no significant difference between the pregabalin and placebo treatment groups with respect to opioid consumption, duration of hospital stay, or pain at 6 months. Pregabalin was efficacious and well tolerated in patients after severe burn injury and whose pain was characterised by features of acute neuropathic pain. In this study, pregabalin was well tolerated and significantly reduced several elements of the neuropathic pain scale including hot pain, unpleasantness of the pain, surface pain, and itch, and also significantly reduced procedural pain.

Cholestatic liver diseases, such as cystic fibrosis (CF) liver disease and biliary atresia, predominate as causes of childhood cirrhosis. Despite diverse etiologies, the stereotypic final pathway involves fibrogenesis where hepatic stellate cells (HSCs) are recruited, producing excess collagen which initiates biliary fibrosis. A possible molecular determinant of this recruitment, monocyte chemotaxis protein-1 (MCP-1), an HSC-responsive chemokine, was investigated in CF liver disease and biliary atresia. The bile-duct-ligated rat and in vitro coculture models of cholestatic liver injury were used to further explore the role of MCP-1 in HSC recruitment and proposed mechanism of induction via bile acids. In both CF liver disease and biliary atresia, elevated hepatic MCP-1 expression predominated in scar margin hepatocytes, closely associated with activated HSCs, and was also expressed in cholangiocytes. Serum MCP-1 was elevated during early fibrogenesis. Similar observations were made in bile-duct-ligated rat liver and serum. Hepatocytes isolated from cholestatic rats secreted increased MCP-1 which avidly recruited HSCs in coculture. This HSC chemotaxis was markedly inhibited in interventional studies using anti-MCP-1 neutralizing antibody. In CF liver disease, biliary MCP-1 was increased, positively correlating with levels of the hydrophobic bile acid, taurocholate. In cholestatic rats, increased MCP-1 positively correlated with taurocholate in serum and liver, and negatively correlated in bile. In normal human and rat hepatocytes, taurocholate induced MCP-1 expression. Conclusion: These observations support the hypothesis that up-regulation of hepatocyte-derived MCP-1, induced by bile acids, results in HSC recruitment in diverse causes of cholestatic liver injury, and is a key early event in liver fibrogenesis in these conditions. Therapies aimed at neutralizing MCP-1 or bile acids may help reduce fibro-obliterative liver injury in childhood cholestatic diseases. (HEPATOLOGY 2009;49:533-544.)

Recently, a role for IFN γ in the genesis of melanoma was reported. Here, we define the mechanism whereby IFN γ becomes a growth stimulator of melanoma cells. In this study, IFN γ stimulated STAT5 to activate the expression of c- myc , an oncogene linked with reduced melanoma patient survival. In a preliminary retrospective study of 27 stage III melanoma patients who received IFN α 2 therapy, STAT5A and c- myc expression levels in metastatic lymph node biopsies were highly correlated (Pearson’s r = 0.914; P myc or STAT5 relative to STAT1 were prognostic markers indicating reduced patient survival. In vitro studies showed that STAT5 activated the c- myc proximal promoter via a functional STAT5A binding site, conferring significant inducibility by IFN γ or EGF (but not IFN α ) in luciferase reporter assays of melanoma cells overexpressing STAT5A. IFN γ caused markedly different responses in wild-type A375 cells compared with A375-STAT5A cells, supporting a key role for STAT5A in IFN γ -mediated regulation of c- myc expression in melanoma. ChIP assays confirmed direct STAT5A binding during IFN γ -mediated activation of the c- myc proximal SBE regulatory region. 5′ RACE and Q-PCR showed that increased levels of c- myc in A375-STAT5A cells induced by IFN γ were associated with a shift in the initiation of transcription near to or at the proximal STAT5 binding element. These results indicate that overexpression of STAT5 in cancer cells is responsible for growth-stimulation by IFN γ .

Interleukin-6 (IL-6) is a major regulator of matrix metalloproteinase (MMP) expression in cancers. A patient matched control study of human colorectal cancers revealed that levels of IL-6 expression correlated strongly with those of MMP-1 and MMP-3 . In human colon cancer cell lines, MMP-3 expression was increased by treatment with IL-6, and suppressed by interferon-gamma (IFN- γ ). Analysis of the MMP-1 and MMP-3 proximal promoters by gel shift and ChIP assays revealed noncanonical STAT binding elements (SBEs) which bound STAT-1 in a complex with AP-1/Fos constitutively and in an IL-6/PMA-inducible manner. STAT-3 was not observed to bind to these novel proximal promoter SBEs. Using northern blot analysis with a STAT-3 knockout colon cancer cell line confirmed that STAT-3 was not required for the IL-6 inducibility of MMP-1 and -3 expression. However, STAT-1 specific siRNA knockdown significantly inhibited induction, validating the requirement for STAT-1 in transcriptional activation. These results strengthen a role for STAT-1 in cytokine induction of malignancy-associated factors such as MMPs in colorectal cancer.

Clinical and molecular characterization of medically refractory acute, severe colitis : preliminary results from the international inflammatory bowel disease genetics consortium (IIBDGC) immunochip study

Correction to: British Journal of Cancer (2009) 100, 795–798. doi:10.1038/sj.bjc.6604908 During submission of the above article to the journal, one of the authors’ surnames was spelt incorrectly – S Sadeghi's name was published as ‘S Sadhegi’. The authors are now happy to correct this mistake.

Introduction Cerebrospinal fluid (CSF) biomarkers, although of established utility in the diagnostic evaluation of Alzheimer’s disease (AD), are known to be sensitive to variation based on pre-analytical sample processing. We assessed whether gravity droplet collection versus syringe aspiration was another factor influencing CSF biomarker analyte concentrations and reproducibility. Methods Standardized lumbar puncture using small calibre atraumatic spinal needles and CSF collection using gravity fed collection followed by syringe aspirated extraction was performed in a sample of elderly individuals participating in a large long-term observational research trial. Analyte assay concentrations were compared. Results For the 44 total paired samples of gravity collection and aspiration, reproducibility was high for biomarker CSF analyte assay concentrations (concordance correlation [95%CI]: beta-amyloid1-42 (Aβ42) 0.83 [0.71 - 0.90]), t-tau 0.99 [0.98 - 0.99], and phosphorylated tau (p-tau) 0.82 [95 % CI 0.71 - 0.89]) and Bonferroni corrected paired sample t-tests showed no significant differences (group means (SD): Aβ42 366.5 (86.8) vs 354.3 (82.6), p = 0.10; t-tau 83.9 (46.6) vs 84.7 (47.4) p = 0.49; p-tau 43.5 (22.8) vs 40.0 (17.7), p = 0.05). The mean duration of collection was 10.9 minutes for gravity collection and Conclusions Our results demonstrate that aspiration of CSF is comparable to gravity droplet collection for AD biomarker analyses but could considerably accelerate throughput and improve the procedural tolerability for assessment of CSF biomarkers.

Loss of intracellular compartmentalization of potassium is a biochemical feature of Alzheimer’s disease indicating a loss of membrane integrity and mitochondrial dysfunction. We examined potassium and rubidium (a biological proxy for potassium) in brain tissue, blood fractions and cerebrospinal fluid from Alzheimer’s disease and healthy control subjects to investigate the diagnostic potential of these two metal ions. We found that both potassium and rubidium levels were significantly decreased across all intracellular compartments in the Alzheimer’s disease brain. Serum from over 1000 participants in the Australian Imaging, Biomarkers and Lifestyle Flagship Study of Ageing (AIBL), showed minor changes according to disease state. Potassium and rubidium levels in erythrocytes and cerebrospinal fluid were not significantly different according to disease state, and rubidium was slightly decreased in Alzheimer’s disease patients compared to healthy controls. Our data provides evidence that contrasts the hypothesized disruption of the blood-brain barrier in Alzheimer’s disease, with the systemic decrease in cortical potassium and rubidium levels suggesting influx of ions from the blood is minimal and that the observed changes are more likely indicative of an internal energy crisis within the brain. These findings may be the basis for potential diagnostic imaging studies using radioactive potassium and rubidium tracers. Electronic supplementary material The online version of this article (doi:10.1186/s40478-016-0390-8) contains supplementary material, which is available to authorized users.

There is no consensus for a blood-based test for the early diagnosis of Alzheimer's disease (AD). Expression profiling of small non-coding RNA's, microRNA (miRNA), has revealed diagnostic potential in human diseases. Circulating miRNA are found in small vesicles known as exosomes within biological fluids such as human serum. The aim of this work was to determine a set of differential exosomal miRNA biomarkers between healthy and AD patients, which may aid in diagnosis. Using next-generation deep sequencing, we profiled exosomal miRNA from serum (N=49) collected from the Australian Imaging, Biomarkers and Lifestyle Flagship Study (AIBL). Sequencing results were validated using quantitative reverse transcription PCR (qRT-PCR; N=60), with predictions performed using the Random Forest method. Additional risk factors collected during the 4.5-year AIBL Study including clinical, medical and cognitive assessments, and amyloid neuroimaging with positron emission tomography were assessed. An AD-specific 16-miRNA signature was selected and adding established risk factors including age, sex and apolipoprotein ɛ4 (APOE ɛ4) allele status to the panel of deregulated miRNA resulted in a sensitivity and specificity of 87% and 77%, respectively, for predicting AD. Furthermore, amyloid neuroimaging information for those healthy control subjects incorrectly classified with AD-suggested progression in these participants towards AD. These data suggest that an exosomal miRNA signature may have potential to be developed as a suitable peripheral screening tool for AD.