Deciphering ApoE Genotype-Driven Proteomic and Lipidomic Alterations in Alzheimer's Disease Across Distinct Brain Regions.

Alzheimer's disease (AD) is a neurodegenerative disease with a complex etiology influenced by confounding factors such as genetic polymorphisms, age, sex, and race. Traditionally, AD research has not prioritized these influences, resulting in dramatically skewed cohorts such as three times the number of Apolipoprotein E (APOE) ε4-allele carriers in AD relative to healthy cohorts. Thus, the resulting molecular changes in AD have previously been complicated by the influence of apolipoprotein E disparities. To explore how apolipoprotein E polymorphism influences AD progression, 62 post-mortem patients consisting of 33 AD and 29 controls (Ctrl) were studied to balance the number of ε4-allele carriers and facilitate a molecular comparison of the apolipoprotein E genotype. Lipid and protein perturbations were assessed across AD diagnosed brains compared to Ctrl brains, ε4 allele carriers (APOE4+ for those carrying 1 or 2 ε4s and APOE4- for non-ε4 carriers), and differences in ε3ε3 and ε3ε4 Ctrl brains across two brain regions (frontal cortex (FCX) and cerebellum (CBM)). The region-specific influences of apolipoprotein E on AD mechanisms showcased mitochondrial dysfunction and cell proteostasis at the core of AD pathophysiology in the post-mortem brains, indicating these two processes may be influenced by genotypic differences and brain morphology.

Circulating medium- and long-chain acylcarnitines are associated with plasma P-tau181 in cognitively normal older adults.

Alzheimer's disease (AD) pathogenesis involves dysregulation in diverse biochemical processes. Nevertheless, plasma tau phosphorylated at threonine 181 (P-tau181), a recognised AD biomarker, has been described to reflect early-stage cortical amyloid-ß (Aß) deposition in cognitively normal (CN) adults. Therefore, identifying changes in plasma metabolites associated with plasma P-tau181 at the pre-clinical stage may provide insights into underlying biochemical mechanisms to better understand initial AD pathogenesis. In the current study, plasma P-tau181, quantified via single molecule array (Simoa) technology, and plasma metabolites, quantified via targeted-mass spectrometry, were investigated for associations in CN older adults and upon stratification by positron emission tomography (PET)-Aß load. In addition, the P-tau181-linked metabolites were evaluated for cognitive performance and neuroimaging markers of AD and the potential to distinguish between CN Aß- and CN Aß+ individuals. Significant positive associations of medium- and long-chain acylcarnitines (ACs) were observed with P-tau181 in the entire cohort, CN Aß- and CN Aß+, suggesting a link between initial Aß pathology and fatty acid oxidation-mediated energy metabolism pathways. However, in CN Aß-, additional linear associations of P-tau181 were observed with muscle metabolism and nitric oxide homeostasis-associated metabolites. Upon investigating the P-tau181-linked metabolites for cognitive performance, significant inverse correlations of the verbal and visual episodic memory and the global composite score were noted in CN Aß+ with medium- and long-chain ACs, suggesting prognostic value of ACs accompanying weaker cognitive performance. While investigating neuroimaging markers, ACs had positive associations with PET-Aß load and inverse associations with hippocampal volume in CN Aß+, indicating connections of ACs with initial AD pathogenesis. Furthermore, based on receiver operating characteristics analysis, the associated ACs potentially classified PET-Aß status in older adults. Therefore, plasma P-tau181-linked circulating ACs may serve as potential prognostic markers for initial AD pathogenesis in CN older adults. However, further cross-sectional and longitudinal research in highly characterised AD cohorts is needed to validate current findings.

A unified mediation analysis framework for integrative cancer proteogenomics with clinical outcomes.

MOTIVATION: Multilevel molecular profiling of tumors and the integrative analysis with clinical outcomes have enabled a deeper characterization of cancer treatment. Mediation analysis has emerged as a promising statistical tool to identify and quantify the intermediate mechanisms by which a gene affects an outcome. However, existing methods lack a unified approach to handle various types of outcome variables, making them unsuitable for high-throughput molecular profiling data with highly interconnected variables. RESULTS: We develop a general mediation analysis framework for proteogenomic data that include multiple exposures, multivariate mediators on various scales of effects as appropriate for continuous, binary and survival outcomes. Our estimation method avoids imposing constraints on model parameters such as the rare disease assumption, while accommodating multiple exposures and high-dimensional mediators. We compare our approach to other methods in extensive simulation studies at a range of sample sizes, disease prevalence and number of false mediators. Using kidney renal clear cell carcinoma proteogenomic data, we identify genes that are mediated by proteins and the underlying mechanisms on various survival outcomes that capture short- and long-term disease-specific clinical characteristics. AVAILABILITY AND IMPLEMENTATION: Software is made available in an R package (https://github.com/longjp/mediateR). SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Sleep discrepancy and cognitive function in community-dwelling older adults.

This was the first study to use cluster analysis to characterise sleep discrepancy (the discordance between self-reported and objective sleep) across multiple sleep parameters, in community-dwelling older adults. For sleep efficiency, negative discrepancy (the tendency to self-report worse sleep than objectively-measured) was associated with poorer memory, independent of insomnia severity, depressive symptoms and objective sleep. This suggests a unique role for sleep discrepancy as a possible risk factor for future cognitive decline, and warrants the need for further research.

Physical activity and brain amyloid beta: A longitudinal analysis of cognitively unimpaired older adults.

INTRODUCTION: The current study evaluated the relationship between habitual physical activity (PA) levels and brain amyloid beta (Aß) over 15 years in a cohort of cognitively unimpaired older adults. METHODS: PA and Aß measures were collected over multiple timepoints from 731 cognitively unimpaired older adults participating in the Australian Imaging, Biomarkers and Lifestyle (AIBL) Study of Aging. Regression modeling examined cross-sectional and longitudinal relationships between PA and brain Aß. Moderation analyses examined apolipoprotein E (APOE) ε4 carriage impact on the PA-Aß relationship. RESULTS: PA was not associated with brain Aß at baseline (ß = -0.001, p = 0.72) or over time (ß = -0.26, p = 0.24). APOE ε4 status did not moderate the PA-Aß relationship over time (ß = 0.12, p = 0.73). Brain Aß levels did not predict PA trajectory (ß = -54.26, p = 0.59). DISCUSSION: Our study did not identify a relationship between habitual PA and brain Aß levels. HIGHLIGHTS: Physical activity levels did not predict brain amyloid beta (Aß) levels over time in cognitively unimpaired older adults (≥60 years of age). Apolipoprotein E (APOE) ε4 carrier status did not moderate the physical activity-brain Aß relationship over time. Physical activity trajectories were not impacted by brain Aß levels.

Longitudinal associations between exercise and biomarkers in autosomal dominant Alzheimer's disease.

INTRODUCTION: We investigated longitudinal associations between self-reported exercise and Alzheimer's disease (AD)-related biomarkers in individuals with autosomal dominant AD (ADAD) mutations. METHODS: Participants were 308 ADAD mutation carriers aged 39.7 ± 10.8 years from the Dominantly Inherited Alzheimer's Network. Weekly exercise volume was measured via questionnaire and associations with brain volume (magnetic resonance imaging), cerebrospinal fluid biomarkers, and brain amyloid beta (Aß) measured by positron emission tomography were investigated. RESULTS: Greater volume of weekly exercise at baseline was associated with slower accumulation of brain Aß at preclinical disease stages ß = -0.16 [-0.23 to -0.08], and a slower decline in multiple brain regions including hippocampal volume ß = 0.06 [0.03 to 0.08]. DISCUSSION: Exercise is associated with more favorable profiles of AD-related biomarkers in individuals with ADAD mutations. Exercise may have therapeutic potential for delaying the onset of AD; however, randomized controlled trials are vital to determine a causal relationship before a clinical recommendation of exercise is implemented. HIGHLIGHTS: Greater self-reported weekly exercise predicts slower declines in brain volume in autosomal dominant Alzheimer's disease (ADAD). Greater self-reported weekly exercise predicts slower accumulation of brain amyloid beta in ADAD. Associations varied depending on closeness to estimated symptom onset.

Low-dose thioguanine guided by therapeutic drug monitoring is a safe and effective alternative in inflammatory bowel disease patients intolerant to conventional thiopurines.

BACKGROUND: Thioguanine is an alternative thiopurine for inflammatory bowel disease (IBD) patients. AIMS: To evaluate the short-term efficacy and safety of low-dose therapeutic drug-monitored (TDM) thioguanine. METHODS: A retrospective evaluation of IBD patients intolerant to conventional thiopurines started on thioguanine from 2017 to 2019 with dosing guided by TDM was conducted. Clinical response was defined for ulcerative colitis (UC) as a reduction of partial Mayo score ≥3 with reduction in rectal bleeding score of at least 1 and a final rectal bleeding subscore of 0-1 at Week 12 of therapy. Crohn disease (CD) response was defined as a reduction of Harvey-Bradshaw index ≥3 (HBI) at Week 12 of therapy. Remission was defined in UC as partial Mayo score of <2 and in CD as HBI score of <5. RESULTS: Forty-six patients were included in the study. The median thioguanine dose was 20 mg/day (standard deviation 7.3; range: 10-40 mg/day) with a median 6-thioguanine nucleotide level of 577 pmol/8 × 108 (interquartile range (IQR) IQR 378.5-878.75) for CD and 677.5 pmol/8 × 108 (IQR 523.25-842.25) for UC. The overall clinical response rate was 62% (13/21), intention to treat (ITT). Maintenance of remission was 76% (19/25, ITT). Thirty-seven percent (17/46) of patients experienced an adverse effect. No early cases of nodular regenerative hyperplasia (NRH) were seen. CONCLUSION: Thioguanine was tolerated well in 63% of patients. A clinical response was seen in 62% of patients, and maintenance of remission was high at 76%. No cases of early NRH were seen. Longer-term follow up is required to ensure safety and to assess durability of response.

Plasma Aß42/40 ratio, p-tau181, GFAP, and NfL across the Alzheimer's disease continuum: A cross-sectional and longitudinal study in the AIBL cohort.

INTRODUCTION: Plasma amyloid beta (Aß)1-42/Aß1-40 ratio, phosphorylated-tau181 (p-tau181), glial fibrillary acidic protein (GFAP), and neurofilament light (NfL) are putative blood biomarkers for Alzheimer's disease (AD). However, head-to-head cross-sectional and longitudinal comparisons of the aforementioned biomarkers across the AD continuum are lacking. METHODS: Plasma Aß1-42, Aß1-40, p-tau181, GFAP, and NfL were measured utilizing the Single Molecule Array (Simoa) platform and compared cross-sectionally across the AD continuum, wherein Aß-PET (positron emission tomography)-negative cognitively unimpaired (CU Aß-, n = 81) and mild cognitive impairment (MCI Aß-, n = 26) participants were compared with Aß-PET-positive participants across the AD continuum (CU Aß+, n = 39; MCI Aß+, n = 33; AD Aß+, n = 46) from the Australian Imaging, Biomarker & Lifestyle Flagship Study of Ageing (AIBL) cohort. Longitudinal plasma biomarker changes were also assessed in MCI (n = 27) and AD (n = 29) participants compared with CU (n = 120) participants. In addition, associations between baseline plasma biomarker levels and prospective cognitive decline and Aß-PET load were assessed over a 7 to 10-year duration. RESULTS: Lower plasma Aß1-42/Aß1-40 ratio and elevated p-tau181 and GFAP were observed in CU Aß+, MCI Aß+, and AD Aß+, whereas elevated plasma NfL was observed in MCI Aß+ and AD Aß+, compared with CU Aß- and MCI Aß-. Among the aforementioned plasma biomarkers, for models with and without AD risk factors (age, sex, and apolipoprotein E (APOE) ε4 carrier status), p-tau181 performed equivalent to or better than other biomarkers in predicting a brain Aß-/+ status across the AD continuum. However, for models with and without the AD risk factors, a biomarker panel of Aß1-42/Aß1-40, p-tau181, and GFAP performed equivalent to or better than any of the biomarkers alone in predicting brain Aß-/+ status across the AD continuum. Longitudinally, plasma Aß1-42/Aß1-40, p-tau181, and GFAP were altered in MCI compared with CU, and plasma GFAP and NfL were altered in AD compared with CU. In addition, lower plasma Aß1-42/Aß1-40 and higher p-tau181, GFAP, and NfL were associated with prospective cognitive decline and lower plasma Aß1-42/Aß1-40, and higher p-tau181 and GFAP were associated with increased Aß-PET load prospectively. DISCUSSION: These findings suggest that plasma biomarkers are altered cross-sectionally and longitudinally, along the AD continuum, and are prospectively associated with cognitive decline and brain Aß-PET load. In addition, although p-tau181 performed equivalent to or better than other biomarkers in predicting an Aß-/+ status across the AD continuum, a panel of biomarkers may have superior Aß-/+ status predictive capability across the AD continuum. HIGHLIGHTS: Area under the curve (AUC) of p-tau181 ≥ AUC of Aß42/40, GFAP, NfL in predicting PET Aß-/+ status (Aß-/+).  AUC of Aß42/40+p-tau181+GFAP panel ≥ AUC of Aß42/40/p-tau181/GFAP/NfL for Aß-/+.  Longitudinally, Aß42/40, p-tau181, and GFAP were altered in MCI versus CU.  Longitudinally, GFAP and NfL were altered in AD versus CU.  Aß42/40, p-tau181, GFAP, and NfL are associated with prospective cognitive decline.  Aß42/40, p-tau181, and GFAP are associated with increased PET Aß load prospectively.

Leukocyte surface biomarkers implicate deficits of innate immunity in sporadic Alzheimer's disease.

INTRODUCTION: Blood-based diagnostics and prognostics in sporadic Alzheimer's disease (AD) are important for identifying at-risk individuals for therapeutic interventions. METHODS: In three stages, a total of 34 leukocyte antigens were examined by flow cytometry immunophenotyping. Data were analyzed by logistic regression and receiver operating characteristic (ROC) analyses. RESULTS: We identified leukocyte markers differentially expressed in the patients with AD. Pathway analysis revealed a complex network involving upregulation of complement inhibition and downregulation of cargo receptor activity and Aß clearance. A proposed panel including four leukocyte markers - CD11c, CD59, CD91, and CD163 - predicts patients' PET Aß status with an area under the curve (AUC) of 0.93 (0.88 to 0.97). CD163 was the top performer in preclinical models. These findings have been validated in two independent cohorts. CONCLUSION: Our finding of changes on peripheral leukocyte surface antigens in AD implicates the deficit in innate immunity. Leukocyte-based biomarkers prove to be both sensitive and practical for AD screening and diagnosis.

Assessment of a polygenic hazard score for the onset of pre-clinical Alzheimer's disease.

BACKGROUND: With a growing number of loci associated with late-onset (sporadic) Alzheimer's disease (AD), the polygenic contribution to AD is now well established. The development of polygenic risk score approaches have shown promising results for identifying individuals at higher risk of developing AD, thereby facilitating the development of preventative and therapeutic strategies. A polygenic hazard score (PHS) has been proposed to quantify age-specific genetic risk for AD. In this study, we assessed the predictive power and transferability of this PHS in an independent cohort, to support its clinical utility. RESULTS: Using genotype and imaging data from 780 individuals enrolled in the Australian Imaging, Biomarkers and Lifestyle (AIBL) study, we investigated associations between the PHS and several AD-related traits, including 1) cross-sectional Aß-amyloid (Aß) deposition, 2) longitudinal brain atrophy, 3) longitudinal cognitive decline, 4) age of onset. Except in the cognitive domain, we obtained results that were consistent with previously published findings. The PHS was associated with increased Aß burden, faster regional brain atrophy and an earlier age of onset. CONCLUSION: Overall, the results support the predictive power of a PHS, however, with only marginal improvement compared to apolipoprotein E alone.

Plasma high-density lipoprotein cargo is altered in Alzheimer's disease and is associated with regional brain volume.

Cholesterol levels have been repeatedly linked to Alzheimer's Disease (AD), suggesting that high levels could be detrimental, but this effect is likely attributed to Low-Density Lipoprotein (LDL) cholesterol. On the other hand, High-Density Lipoproteins (HDL) cholesterol levels have been associated with reduced brain amyloidosis and improved cognitive function. However, recent findings have suggested that HDL-functionality, which depends upon the HDL-cargo proteins associated with HDL, rather than HDL levels, appears to be the key factor, suggesting a quality over quantity status. In this report, we have assessed the HDL-cargo (Cholesterol, ApoA-I, ApoA-II, ApoC-I, ApoC-III, ApoD, ApoE, ApoH, ApoJ, CRP, and SAA) in stable healthy control (HC), healthy controls who will convert to MCI/AD (HC-Conv) and AD patients (AD). Compared to HC we observed an increased cholesterol/ApoA-I ratio in AD and HC-Conv, as well as an increased ApoD/ApoA-I ratio and a decreased ApoA-II/ApoA-I ratio in AD. Higher cholesterol/ApoA-I ratio was also associated with lower cortical grey matter volume and higher ventricular volume, while higher ApoA-II/ApoA-I and ApoJ/ApoA-I ratios were associated with greater cortical grey matter volume (and for ApoA-II also with greater hippocampal volume) and smaller ventricular volume. Additionally, in a clinical status-independent manner, the ApoE/ApoA-I ratio was significantly lower in APOE ε4 carriers and lowest in APOE ε4 homozygous. Together, these data indicate that in AD patients the composition of HDL is altered, which may affect HDL functionality, and such changes are associated with altered regional brain volumetric data.

Systemic perturbations of the kynurenine pathway precede progression to dementia independently of amyloid-ß.

Increasing evidence suggests that kynurenine pathway (KP) dyshomeostasis may promote disease progression in dementia. Studies in Alzheimer's disease (AD) patients confirm KP dyshomeostasis in plasma and cerebrospinal fluid (CSF) which correlates with amyloid-ß and tau pathology. Herein, we performed the first comprehensive study assessing baseline levels of KP metabolites in participants enrolling in the Australian Imaging Biomarkers Flagship Study of Aging. Our purpose was to test the hypothesis that changes in KP metabolites may be biomarkers of dementia processes that are largely silent. We used a cross-sectional analytical approach to assess non-progressors (N = 73); cognitively normal (CN) or mild cognitive impairment (MCI) participants at baseline and throughout the study, and progressors (N = 166); CN or MCI at baseline but progressing to either MCI or AD during the study. Significant KP changes in progressors included increased 3-hydroxyanthranilic acid (3-HAA) and 3-hydroxyanthranilic acid/anthranilic acid (3-HAA/AA) ratio, the latter having the largest effect on the odds of an individual being a progressor (OR 35.3; 95% CI between 14 and 104). 3-HAA levels were hence surprisingly bi-phasic, high in progressors but low in non-progressors or participants who had already transitioned to MCI or dementia. This is a new, unexpected and interesting result, as most studies of the KP in neurodegenerative disease show reduced 3-HAA/AA ratio after diagnosis. The neuroprotective metabolite picolinic acid was also significantly decreased while the neurotoxic metabolite 3-hydroxykynurenine increased in progressors. These results were significant even after adjustment for confounders. Considering the magnitude of the OR to predict change in cognition, it is important that these findings are replicated in other populations. Independent validation of our findings may confirm the utility of 3-HAA/AA ratio to predict change in cognition leading to dementia in clinical settings.

Analysis of plasma proteins using 2D gels and novel fluorescent probes: in search of blood based biomarkers for Alzheimer's disease.

BACKGROUND: The Australian Imaging and Biomarker Lifestyle (AIBL) study of aging is designed to aid the discovery of biomarkers. The current study aimed to discover differentially expressed plasma proteins that could yield a blood-based screening tool for Alzheimer's disease. METHODS: The concentration of proteins in plasma covers a vast range of 12 orders of magnitude. Therefore, to search for medium to low abundant biomarkers and elucidate mechanisms of AD, we immuno-depleted the most abundant plasma proteins and pre-fractionated the remaining proteins by HPLC, prior to two-dimensional gel electrophoresis. The relative levels of approximately 3400 protein species resolved on the 2D gels were compared using in-gel differential analysis with spectrally resolved fluorescent protein detection dyes (Zdyes™). Here we report on analysis of pooled plasma samples from an initial screen of a sex-matched cohort of 72 probable AD patients and 72 healthy controls from the baseline time point of AIBL. RESULTS: We report significant changes in variants of apolipoprotein E, haptoglobin, α1 anti-trypsin, inter-α trypsin inhibitor, histidine-rich glycoprotein, and a protein of unknown identity. α1 anti-trypsin and α1 anti-chymotrypsin demonstrated plasma concentrations that were dependent on APOE ε4 allele dose. Our analysis also identified an association with the level of Vitamin D binding protein fragments and complement factor I with sex. We then conducted a preliminary validation study, on unique individual samples compared to the discovery cohort, using a targeted LC-MS/MS assay on a subset of discovered biomarkers. We found that targets that displayed a high degree of isoform specific changes in the 2D gels were not changed in the targeted MS assay which reports on the total level of the biomarker. CONCLUSIONS: This demonstrates that further development of mass spectrometry assays is needed to capture the isoform complexity that exists in theses biological samples. However, this study indicates that a peripheral protein signature has potential to aid in the characterization of AD.

Identification of Leukocyte Surface P2X7 as a Biomarker Associated with Alzheimer's Disease.

Alzheimer's disease (AD) has shown altered immune responses in the periphery. We studied P2X7 (a proinflammatory receptor and a scavenger receptor) and two integrins, CD11b and CD11c, on the surface of circulating leukocytes and analysed their associations with Aß-PET, brain atrophy, neuropsychological assessments, and cerebrospinal fluid (CSF) biomarkers. Total 287 age-matched, sex-balanced participants were recruited in a discovery cohort and two validation cohorts through the AIBL study and studied using tri-colour flow cytometry. Our results demonstrated reduced expressions of P2X7, CD11b, and CD11c on leukocytes, particularly monocytes, in Aß +ve cases compared with Aß -ve controls. P2X7 and integrin downregulation was observed at pre-clinical stage of AD and stayed low throughout disease course. We further constructed a polygenic risk score (PRS) model based on 12 P2RX7 risk alleles to assess the genetic impact on P2X7 function in AIBL and ADNI cohorts. No significant association was identified between the P2RX7 gene and AD, indicating that P2X7 downregulation in AD is likely caused by environmental changes rather than genetic factors. In conclusion, the downregulation of P2X7 and integrins at pre-clinical stage of AD indicates altered pro-inflammatory responses, phagocytic functions, and migrating capabilities of circulating monocytes in early AD pathogenesis. Our study not only improves our understanding of peripheral immune involvement in early stage of AD but also provides more insights into novel biomarker development, diagnosis, and prognosis of AD.

Bayesian modeling of multiple structural connectivity networks during the progression of Alzheimer's disease.

Alzheimer's disease is the most common neurodegenerative disease. The aim of this study is to infer structural changes in brain connectivity resulting from disease progression using cortical thickness measurements from a cohort of participants who were either healthy control, or with mild cognitive impairment, or Alzheimer's disease patients. For this purpose, we develop a novel approach for inference of multiple networks with related edge values across groups. Specifically, we infer a Gaussian graphical model for each group within a joint framework, where we rely on Bayesian hierarchical priors to link the precision matrix entries across groups. Our proposal differs from existing approaches in that it flexibly learns which groups have the most similar edge values, and accounts for the strength of connection (rather than only edge presence or absence) when sharing information across groups. Our results identify key alterations in structural connectivity that may reflect disruptions to the healthy brain, such as decreased connectivity within the occipital lobe with increasing disease severity. We also illustrate the proposed method through simulations, where we demonstrate its performance in structure learning and precision matrix estimation with respect to alternative approaches.

Relative rate of change in cognitive score network dynamics via Bayesian hierarchical models reveal spatial patterns of neurodegeneration.

The degeneration of the human brain is a complex process, which often affects certain brain regions due to healthy aging or disease. This degeneration can be evaluated on regions of interest (ROI) in the brain through probabilistic networks and morphological estimates. Current approaches for finding such networks are limited to analyses at discrete neuropsychological stages, which cannot appropriately account for connectivity dynamics over the onset of cognitive deterioration, and morphological changes are seldom unified with connectivity networks, despite known dependencies. To overcome these limitations, a probabilistic wombling model is proposed to simultaneously estimate ROI cortical thickness and covariance networks contingent on rates of change in cognitive decline. This proposed model was applied to analyze longitudinal data from healthy control (HC) and Alzheimer's disease (AD) groups and found connection differences pertaining to regions, which play a crucial role in lasting cognitive impairment, such as the entorhinal area and temporal regions. Moreover, HC cortical thickness estimates were significantly higher than those in the AD group across all ROIs. The analyses presented in this work will help practitioners jointly analyze brain tissue atrophy at the ROI-level conditional on neuropsychological networks, which could potentially allow for more targeted therapeutic interventions.

Short-term colectomy is avoided in over half of regional patients failing medical therapy for acute severe ulcerative colitis with co-ordinated transfer and tertiary care.

BACKGROUND AND AIMS: Many patients presenting with an acute severe ulcerative colitis to a regional hospital are transferred to a metropolitan hospital for specialised care. This study aimed to evaluate the outcomes and characteristics of these patients. METHOD: A retrospective observational cohort study was conducted to examine the 30-day colectomy rate using prospectively collected data on 69 consecutive index cases of acute severe ulcerative colitis transferred from regional hospitals to our metropolitan hospital meeting Truelove and Witts criteria. Those that avoided colectomy were followed out to 1 year to examine outcomes. RESULTS: The 30-day colectomy rate was 46.4% (32/69) in regional transfer patients. Rescue therapy was administered to 65% (45/69) of patients after transfer to our metropolitan hospital. Colectomy was avoided in 55% of these patients at 30 days. Colectomy free status was maintained in 78% (29/39) of these patients. Mortality was 0% at 30 days and 1 year. CONCLUSION: Over 50% of the patients failing therapy in a regional centre and requiring transfer avoided short term colectomy with co-ordinated referral for rescue therapy in a tertiary metropolitan inflammatory bowel disease unit. These patients would have ultimately required colectomy in their regional hospital without intervention.

Detectable Laboratory Abnormality Is Present up to 12 Months Prior to Diagnosis in Patients with Crohn's Disease.

BACKGROUND AND AIMS: Patients with inflammatory bowel disease (IBD) often have subjective symptoms for months or years prior to their diagnosis. Blood tests taken prior to diagnosis may provide objective evidence of duration of pre-diagnosis disease. We aim to describe the pre-diagnosis laboratory pattern of patients with IBD. METHODS: A total of 838 patients diagnosed with IBD between 01/01/1996 and 01/03/2014, with pre-diagnosis laboratory testing available, contributed data for analysis. C-reactive protein, erythrocyte sedimentation rate, hemoglobin level, mean cell volume (MCV) platelet count, white blood cell count, neutrophil count, albumin level, ferritin level, serum iron level, alanine transaminase level, and fecal calprotectin were examined in the 24 months leading up to diagnosis and compared to baseline data taken between 24 and 36 months prior to diagnosis. RESULTS: For patients with Crohn's disease, a significant drop in serum albumin and MCV levels and a significant rise in platelet count were observed between 115 and 385 days prior to diagnosis (p < 0.01, two-tailed t test). For patients with ulcerative colitis, a significant change in albumin level, MCV, hemoglobin level, platelet count, and serum iron level was observed at diagnosis (p < 0.01, two-tailed t test) but was not detectable before. CONCLUSIONS: These data provide objective evidence of duration of delay between disease onset and diagnosis in a cohort of patients with IBD. Expediting diagnostic testing in patients presenting with symptoms consistent with IBD, who also have abnormal laboratory results, may reduce diagnostic delay, speed access to therapy, and improve clinical outcomes.

Biochemically-defined pools of amyloid-ß in sporadic Alzheimer's disease: correlation with amyloid PET.

We fractionated frontal cortical grey matter from human Alzheimer's disease and control subjects into four biochemically defined pools that represent four distinct compartments: soluble/cytosolic, peripheral membrane/vesicular cargo, integral lipid/membranous pools and aggregated/insoluble debris. Most of the readily extractable amyloid-ß remains associated with a lipid/membranous compartment. There is an exchange of amyloid-ß between the biochemical pools that was lost for the amyloid-ß42 species in Alzheimer's disease, consistent with the peptide being irreversibly trapped in extracellular deposits. The quantitative amyloid-ß data, combined with magnetic resonance imaging volumetric analysis of the amount of cortical grey matter in brain, allowed us to estimate the total mass of amyloid-ß in Alzheimer's disease (6.5 mg) and control (1.7 mg) brains. The threshold positron emission tomography standard uptake value ratio of 1.4 equates to 5.0 µg amyloid-ß/g of grey matter and the mean Alzheimer's disease dementia standard uptake value ratio level of 2.3 equates to 11.20 µg amyloid-ß/g of grey matter. It takes 19 years to accumulate amyloid from the threshold positron emission tomography standard uptake value ratio to the mean value observed for Alzheimer's disease dementia. This accumulation time window combined with the difference of 4.8 mg of amyloid-ß between Alzheimer's disease and control brain allows for a first approximation of amyloid-ß accumulation of 28 ng/h. This equates to an estimated 2-5% of the total amyloid-ß production being deposited as insoluble plaques. Understanding these rates of amyloid-ß accumulation allows for a more quantitative approach in targeting the failure of amyloid-ß clearance in sporadic Alzheimer's disease.

A Bayesian integrative approach for multi-platform genomic data: A kidney cancer case study.

Integration of genomic data from multiple platforms has the capability to increase precision, accuracy, and statistical power in the identification of prognostic biomarkers. A fundamental problem faced in many multi-platform studies is unbalanced sample sizes due to the inability to obtain measurements from all the platforms for all the patients in the study. We have developed a novel Bayesian approach that integrates multi-regression models to identify a small set of biomarkers that can accurately predict time-to-event outcomes. This method fully exploits the amount of available information across platforms and does not exclude any of the subjects from the analysis. Through simulations, we demonstrate the utility of our method and compare its performance to that of methods that do not borrow information across regression models. Motivated by The Cancer Genome Atlas kidney renal cell carcinoma dataset, our methodology provides novel insights missed by non-integrative models.