The world’s human population ages rapidly thanks to the great advance in modern medicine. While more and more body system diseases become treatable and curable, age-related neurodegenerative diseases remain poorly understood mechanistically, and are desperately in need of preventive and therapeutic interventions. Biomarker development consists of a key part of concerted effort in combating neurodegenerative diseases. In many chronic neurodegenerative conditions, neuronal damage/death occurs long before the onset of disease symptoms, and abnormal proteolysis may either play an active role or be a companying event of neuronal injury. Increased spectrin cleavage yielding elevated spectrin breakdown products (SBDPs) by calcium-sensitive proteases such as calpain and caspases has been established in conditions associated with acute neuronal damage such as traumatic brain injury (TBI). Here we review literature regarding spectrin expression and metabolism in the brain, and propose a potential use of SBDPs as biomarkers for neurodegenerative diseases such as Alzheimer’s diseases.
Aging; Alzheimer’s disease; Apoptosis; Autophagy; Calcium; Calpain; Caspases; Membrane skeleton; Neuroplasticity; Neurodegeneration; Proteolysis
This study investigated the comparability of potential AD biomarkers across blood fractions and assay platforms.
Non-fasting serum and plasma samples from 300 participants (150 AD patients, 150 controls) were analyzed. Proteomic markers were obtained via electrochemiluminescence or Luminex technology. Comparisons were conducted via Pearson correlations. The relative importance of proteins within an AD diagnostic profile was examined using random forest importance plots.
On the MSD multi-plex platform, 10 out of the 21 markers shared >50% of the variance across blood fractions (SAA R2=0.99, IL10 R2=0.95, FABP R2=0.94, I309 R2=0.94, IL5 R2=0.94, IL6 R2=0.94, Eotaxin3 R2=0.91, IL18 R2=0.87, sTNFR1 R2=0.85, PPY R2=0.81). When examining protein concentrations across platforms, only five markers shared >50% of the variance (β2M R2=0.92, IL18 R2=0.80, FVII R2=0.78, CRP R2=0.74, FABP R2=0.70).
The current findings highlight the importance of considering blood fractions and assay platforms when searching for AD relevant biomarkers.
Alzheimer’s disease; Blood; Serum; Plasma; Biomarker Discovery; Multi-plex Assay Platform; Meso Scale Discovery; Rules Based Medicine; Proteins; Pre-analytic Processing; Standardization; Diagnostics
Amyloid-β 1–42 peptide (Aβ1–42) is associated with plaque formation in the brain of patients with Alzheimer’s disease (AD). Pharmacodynamic studies of AD therapeutics that lower the concentrations of Aβ1–42 in peripheral blood require highly sensitive assays for its measurement. A digital enzyme-linked immunosorbent assay (ELISA) using single molecule array (Simoa) technology has been developed that provides improved sensitivity compared with conventional ELISA methods using the same antibody reagents.
A sensitive digital ELISA for measurement of Aβ1–42 using antibodies 3D6 and 21F12 was developed. Assay performance was evaluated by repeated testing of pooled human plasma and buffer diluent quality control samples to determine relative accuracy, intra- and inter-assay precision, limit of detection (LOD), lower limit of quantification (LLOQ), dilutional linearity, and spike recovery. The optimized assay was used to quantify Aβ1–42 in clinical samples from patients treated with the β-site amyloid precursor protein cleaving enzyme 1 inhibitor LY2886721.
The prototype assay measured Aβ1–42 with an LOD of 0.3 pg/ml and an LLOQ of 2.8 pg/ml in plasma, calibrated using an Aβ1–42 peptide standard from Fujirebio. Assay precision was acceptable with intra- and inter-assay coefficients of variation both being ≤10%. Dilutional linearity was demonstrated in sample diluent and immunodepleted human plasma. Analyte spike recovery ranged from 51% to 93% with a mean of 80%. This assay was able to quantify Aβ1–42 in all of the 84 clinical samples tested. A rapid reduction in levels of Aβ1–42 was detected within 1 h after drug treatment, and a dose-dependent decrease of Aβ1–42 levels was also observed over the time course of sample collection.
This digital ELISA has potential utility in clinical applications for quantification of Aβ1–42 in plasma where high sensitivity and precision are required.
Digital ELISA; Ultrasensitive; Aβ1–42; Plasma; Alzheimer’s disease; Therapeutic
To test whether plasma tau is altered in Alzheimer disease (AD) and whether it is related to changes in cognition, CSF biomarkers of AD pathology (including β-amyloid [Aβ] and tau), brain atrophy, and brain metabolism.
This was a study of plasma tau in prospectively followed patients with AD (n = 179), patients with mild cognitive impairment (n = 195), and cognitive healthy controls (n = 189) from the Alzheimer's Disease Neuroimaging Initiative (ADNI) and cross-sectionally studied patients with AD (n = 61), mild cognitive impairment (n = 212), and subjective cognitive decline (n = 174) and controls (n = 274) from the Biomarkers for Identifying Neurodegenerative Disorders Early and Reliably (BioFINDER) study at Lund University, Sweden. A total of 1284 participants were studied. Associations were tested between plasma tau and diagnosis, CSF biomarkers, MRI measures, 18fluorodeoxyglucose-PET, and cognition.
Higher plasma tau was associated with AD dementia, higher CSF tau, and lower CSF Aβ42, but the correlations were weak and differed between ADNI and BioFINDER. Longitudinal analysis in ADNI showed significant associations between plasma tau and worse cognition, more atrophy, and more hypometabolism during follow-up.
Plasma tau partly reflects AD pathology, but the overlap between normal aging and AD is large, especially in patients without dementia. Despite group-level differences, these results do not support plasma tau as an AD biomarker in individual people. Future studies may test longitudinal plasma tau measurements in AD.
Traumatic brain injury (TBI) is one of the leading causes of death and disability around the world. The lack of validated biomarkers for TBI is a major impediment to developing effective therapies and improving clinical practice, as well as stimulating much work in this area. In this review, we focus on different settings of TBI management where blood or cerebrospinal fluid (CSF) biomarkers could be utilized for predicting clinically-relevant consequences and guiding management decisions. Requirements that the biomarker must fulfill differ based on the intended context of use (CoU). Specifically, we focus on fluid biomarkers in order to: (1) identify patients who may require acute neuroimaging (cranial computerized tomography (CT) or magnetic resonance imaging (MRI); (2) select patients at risk for secondary brain injury processes; (3) aid in counseling patients about their symptoms at discharge; (4) identify patients at risk for developing postconcussive syndrome (PCS), posttraumatic epilepsy (PTE) or chronic traumatic encephalopathy (CTE); (5) predict outcomes with respect to poor or good recovery; (6) inform counseling as to return to work (RTW) or to play. Despite significant advances already made from biomarker-based studies of TBI, there is an immediate need for further large-scale studies focused on identifying and innovating sensitive and reliable TBI biomarkers. These studies should be designed with the intended CoU in mind.
traumatic brain injury (TBI); biomarkers; TBI management
Multiplex ligand binding assays (LBAs) are increasingly being used to support many stages of drug development. The complexity of multiplex assays creates many unique challenges in comparison to single-plexed assays leading to various adjustments for validation and potentially during sample analysis to accommodate all of the analytes being measured. This often requires a compromise in decision making with respect to choosing final assay conditions and acceptance criteria of some key assay parameters, depending on the intended use of the assay. The critical parameters that are impacted due to the added challenges associated with multiplexing include the minimum required dilution (MRD), quality control samples that span the range of all analytes being measured, quantitative ranges which can be compromised for certain targets, achieving parallelism for all analytes of interest, cross-talk across assays, freeze-thaw stability across analytes, among many others. Thus, these challenges also increase the complexity of validating the performance of the assay for its intended use. This paper describes the challenges encountered with multiplex LBAs, discusses the underlying causes, and provides solutions to help overcome these challenges. Finally, we provide recommendations on how to perform a fit-for-purpose-based validation, emphasizing issues that are unique to multiplex kit assays.
biomarker; diagnostics; ligand binding assay; multiplex; validation
Although imatinib is highly effective in the treatment of chronic myeloid leukemia (CML), 25–30% patients do not respond or relapse after initial response. Imatinib uptake into targeted cells is crucial for its molecular response and clinical effectiveness. The organic cation transporter 1 (OCT1) has been proposed to be responsible for this process, but its relevance has been discussed controversially in recent times. Here we found that the multidrug and toxin extrusion protein 1 (MATE1) transports imatinib with a manifold higher affinity. MATE1 mainly mediates the cellular uptake of imatinib into targeted cells and thereby controls the intracellular effectiveness of imatinib. Importantly, MATE1 but not OCT1 expression is reduced in total bone marrow cells of imatinib-non-responding CML patients compared with imatinib-responding patients, indicating that MATE1 but not OCT1 determines the therapeutic success of imatinib. We thus propose that imatinib non-responders could be identified early before starting therapy by measuring MATE1 expression levels.
Implementation of amyloid biomarkers in clinical practice would be accelerated if such biomarkers could be measured in blood. We analyzed plasma levels of Aβ42 and Aβ40 in a cohort of 719 individuals (the Swedish BioFINDER study), including patients with subjective cognitive decline (SCD), mild cognitive impairment (MCI), Alzheimer’s disease (AD) dementia and cognitively healthy elderly, using a ultrasensitive immunoassay (Simoa platform). There were weak positive correlations between plasma and cerebrospinal fluid (CSF) levels for both Aβ42 and Aβ40, and negative correlations between plasma Aβ42 and neocortical amyloid deposition (measured with PET). Plasma levels of Aβ42 and Aβ40 were reduced in AD dementia compared with all other diagnostic groups. However, during the preclinical or prodromal AD stages (i.e. in amyloid positive controls, SCD and MCI) plasma concentration of Aβ42 was just moderately decreased whereas Aβ40 levels were unchanged. Higher plasma (but not CSF) levels of Aβ were associated with white matter lesions, cerebral microbleeds, hypertension, diabetes and ischemic heart disease. In summary, plasma Aβ is overtly decreased during the dementia stage of AD indicating that prominent changes in Aβ metabolism occur later in the periphery compared to the brain. Further, increased levels of Aβ in plasma are associated with vascular disease.
The lack of readily available biomarkers is a significant hindrance towards progressing to effective therapeutic and preventative strategies for Alzheimer’s disease (AD). Blood-based biomarkers have potential to overcome access and cost barriers and greatly facilitate advanced neuroimaging and cerebrospinal fluid biomarker approaches. Despite the fact that preanalytical processing is the largest source of variability in laboratory testing, there are no currently available standardized preanalytical guidelines. The current international working group provides the initial starting point for such guidelines for standardized operating procedures (SOPs). It is anticipated that these guidelines will be updated as additional research findings become available. The statement provides (1) a synopsis of selected preanalytical methods utilized in many international AD cohort studies, (2) initial draft guidelines/SOPs for preanalytical methods, and (3) a list of required methodological information and protocols to be made available for publications in the field in order to foster cross-validation across cohorts and laboratories.
Biomarkers; blood; serum; plasma; Alzheimer’s disease; dementia; diagnosis; treatment
This study investigated the comparability of potential Alzheimer's disease (AD) biomarkers across blood fractions and assay platforms.
Nonfasting serum and plasma samples from 300 participants (150 AD patients and 150 controls) were analyzed. Proteomic markers were obtained via electrochemiluminescence or Luminex technology. Comparisons were conducted via Pearson correlations. The relative importance of proteins within an AD diagnostic profile was examined using random forest importance plots.
On the Meso Scale Discovery multiplex platform, 10 of the 21 markers shared >50% of the variance across blood fractions (serum amyloid A R2 = 0.99, interleukin (IL)10 R2 = 0.95, fatty acid-binding protein (FABP) R2 = 0.94, I309 R2 = 0.94, IL-5 R2 = 0.94, IL-6 R2 = 0.94, eotaxin3 R2 = 0.91, IL-18 R2 = 0.87, soluble tumor necrosis factor receptor 1 R2 = 0.85, and pancreatic polypeptide R2 = 0.81). When examining protein concentrations across platforms, only five markers shared >50% of the variance (beta 2 microglobulin R2 = 0.92, IL-18 R2 = 0.80, factor VII R2 = 0.78, CRP R2 = 0.74, and FABP R2 = 0.70).
The current findings highlight the importance of considering blood fractions and assay platforms when searching for AD relevant biomarkers.
Alzheimer's disease; Blood; Serum; Plasma; Biomarker discovery; Multiplex assay platform; Meso Scale Discovery; Rules Based Medicine; Proteins; Preanalytic processing; Standardization; Diagnostics
Neurotoxicity has been linked to a number of common drugs and chemicals, yet efficient and accurate methods to detect it are lacking. There is a need for more sensitive and specific biomarkers of neurotoxicity that can help diagnose and predict neurotoxicity that are relevant across animal models and translational from nonclinical to clinical data. Fluid-based biomarkers such as those found in serum, plasma, urine, and cerebrospinal fluid (CSF) have great potential due to the relative ease of sampling compared with tissues. Increasing evidence supports the potential utility of fluid-based biomarkers of neurotoxicity such as microRNAs, F2-isoprostanes, translocator protein, glial fibrillary acidic protein, ubiquitin C-terminal hydrolase L1, myelin basic protein, microtubule-associated protein-2, and total tau. However, some of these biomarkers such as those in CSF require invasive sampling or are specific to one disease such as Alzheimer’s, while others require further validation. Additionally, neuroimaging methodologies, including magnetic resonance imaging, magnetic resonance spectroscopy, and positron emission tomography, may also serve as potential biomarkers and have several advantages including being minimally invasive. The development of biomarkers of neurotoxicity is a goal shared by scientists across academia, government, and industry and is an ideal topic to be addressed via the Health and Environmental Sciences Institute (HESI) framework which provides a forum to collaborate on key challenging scientific topics. Here we utilize the HESI framework to propose a consensus on the relative potential of currently described biomarkers of neurotoxicity to assess utility of the selected biomarkers using a nonclinical model.
neurotoxicity; biomarker; imaging; CSF; neurotoxicity
This review provides perspectives on the utility of magnetic resonance imaging (MRI) as a neuroimaging approach in the development of novel treatments for Alzheimer’s disease. These considerations were generated in a roundtable at a recent Wellcome Trust meeting that included experts from academia and industry. It was agreed that MRI, either structural or functional, could be used as a diagnostic, for assessing worsening of disease status, for monitoring vascular pathology, and for stratifying clinical trial populations. It was agreed also that MRI implementation is in its infancy, requiring more evidence of association with the disease states, test-retest data, better standardization across multiple clinical sites, and application in multimodal approaches which include other imaging technologies, such as positron emission tomography, electroencephalography, and magnetoencephalography.
To provide a temporal framework for the genoarchitecture of brain development, in situ hybridization data were generated for embryonic and postnatal mouse brain at 7 developmental stages for ~2100 genes, processed with an automated informatics pipeline and manually annotated. This resource comprises 434,946 images, 7 reference atlases, an ontogenetic ontology, and tools to explore co-expression of genes across neurodevelopment. Gene sets coinciding with developmental phenomena were identified. A temporal shift in the principles governing the molecular organization of the brain was detected, with transient neuromeric, plate-based organization of the brain present at E11.5 and E13.5. Finally, these data provided a transcription factor code that discriminates brain structures and identifies the developmental age of a tissue, providing a foundation for eventual genetic manipulation or tracking of specific brain structures over development. The resource is available as the Allen Developing Mouse Brain Atlas (developingmouse.brain-map.org).
To determine if candidate biomarkers, ubiquitin carboxyl-terminal esterase L1 and glial fibrillary acidic protein, are elevated in neonates with hypoxic ischemic encephalopathy who die or have severe MRI injury compared with surviving infants with minimal or no injury on brain MRI.
Prospective observational study.
Level IIIC outborn neonatal ICU in a free-standing children's hospital.
Term newborns with moderate-to-severe hypoxic ischemic encephalopathy referred for therapeutic hypothermia
Serum specimens were collected at 0, 12, 24, and 72 hours of cooling. MRI was performed in surviving infants at target 7–10 days of life and was scored by a pediatric neuroradiologist masked to biomarker and clinical data.
Measurements and Main Results
Serial biomarker levels were determined in 20 hypoxic ischemic encephalopathy patients. Ubiquitin carboxyl-terminal esterase L1 was higher at initiation and 72 hours of cooling, while glial fibrillary acidic protein was higher at 24 and 72 hours in babies with adverse outcome compared with those with favorable outcome.
This preliminary data support further studies to evaluate ubiquitin carboxyl-terminal esterase L1 and glial fibrillary acidic protein as immediate biomarkers of cerebral injury severity in newborns with hypoxic ischemic encephalopathy.
asphyxia; biomarker; hypoxic ischemic encephalopathy; neonate; therapeutic hypothermia
Decision-making in treatment of an acute compartment syndrome is based on clinical assessment, supported by invasive monitoring. Thus, evolving compartment syndrome may require repeated pressure measurements. In suspected cases of potential compartment syndromes clinical assessment alone seems to be unreliable. The objective of this study was to investigate the feasibility of a non-invasive application estimating whole compartmental elasticity by ultrasound, which may improve accuracy of diagnostics.
In an in vitro model, using an artificial container simulating dimensions of the human anterior tibial compartment, intra-compartmental pressures (p) were raised subsequently up to 80 mmHg by infusion of saline solution. The compartmental depth (mm) in the cross-section view was measured before and after manual probe compression (100 mmHg) upon the surface resulting in a linear compartmental displacement (∆d). This was repeated at rising compartmental pressures. The resulting displacements were related to the corresponding intra-compartmental pressures simulated in our model. A hypothesized relationship between pressures related compartmental displacement and the elasticity at elevated compartment pressures was investigated.
With rising compartmental pressures, a non-linear, reciprocal proportional relation between the displacement (mm) and the intra-compartmental pressure (mmHg) occurred. The Pearson coefficient showed a high correlation (r2 = −0.960). The intra-observer reliability value kappa resulted in a statistically high reliability (κ = 0.840). The inter-observer value indicated a fair reliability (κ = 0.640).
Our model reveals that a strong correlation between compartmental strain displacements assessed by ultrasound and the intra-compartmental pressure changes occurs. Further studies are required to prove whether this assessment is transferable to human muscle tissue. Determining the complete compartmental elasticity by ultrasound enhancement, this application may improve detection of early signs of potential compartment syndrome.
Electronic supplementary material
The online version of this article (doi:10.1186/s13037-014-0051-4) contains supplementary material, which is available to authorized users.
Compartment syndrome; Intra-compartmental pressure; Non-invasive diagnostic; Elasticity measurement; Elastography
Treatment of Alzheimer’s disease (AD) is significantly hampered by the lack of easily accessible biomarkers that can detect disease presence and predict disease risk reliably. Fluid biomarkers of AD currently provide indications of disease stage; however, they are not robust predictors of disease progression or treatment response, and most are measured in cerebrospinal fluid, which limits their applicability. With these aspects in mind, the aim of this article is to underscore the concerted efforts of the Blood-Based Biomarker Interest Group, an international working group of experts in the field. The points addressed include: (1) the major challenges in the development of blood-based biomarkers of AD, including patient heterogeneity, inclusion of the “right” control population, and the blood– brain barrier; (2) the need for a clear definition of the purpose of the individual markers (e.g., prognostic, diagnostic, or monitoring therapeutic efficacy); (3) a critical evaluation of the ongoing biomarker approaches; and (4) highlighting the need for standardization of preanalytical variables and analytical methodologies used by the field.
Neuroanatomically precise, genome-wide maps of transcript distributions are critical resources to complement genomic sequence data and to correlate functional and genetic brain architecture. Here we describe the generation and analysis of a transcriptional atlas of the adult human brain, comprising extensive histological analysis and comprehensive microarray profiling of ~900 neuroanatomically precise subdivisions in two individuals. Transcriptional regulation varies enormously by anatomical location, with different regions and their constituent cell types displaying robust molecular signatures that are highly conserved between individuals. Analysis of differential gene expression and gene co-expression relationships demonstrates that brain-wide variation strongly reflects the distributions of major cell classes such as neurons, oligodendrocytes, astrocytes and microglia. Local neighbourhood relationships between fine anatomical subdivisions are associated with discrete neuronal subtypes and genes involved with synaptic transmission. The neocortex displays a relatively homogeneous transcriptional pattern, but with distinct features associated selectively with primary sensorimotor cortices and with enriched frontal lobe expression. Notably, the spatial topography of the neocortex is strongly reflected in its molecular topography— the closer two cortical regions, the more similar their transcriptomes. This freely accessible online data resource forms a high-resolution transcriptional baseline for neurogenetic studies of normal and abnormal human brain function.
Neuroscience; Genetics; Genomics; Databases
The role of amyloid-β (Aβ) neuropathology and its significant changes in biofluids after traumatic brain injury (TBI) is still debated. We used ultrasensitive digital ELISA approach to assess amyloid-β1-42 (Aβ42) concentrations and time-course in cerebrospinal fluid (CSF) and in plasma of patients with severe TBI and investigated their relationship to injury characteristics, neurological status and clinical outcome. We found decreased CSF Aβ42 levels in TBI patients acutely after injury with lower levels in patients who died 6 months post-injury than in survivors. Conversely, plasma Aβ42 levels were significantly increased in TBI with lower levels in patients who survived. A trend analysis showed that both CSF and plasma Aβ42 levels strongly correlated with mortality. A positive correlation between changes in CSF Aβ42 concentrations and neurological status as assessed by Glasgow Coma Scale (GCS) was identified. Our results suggest that determination of Aβ42 may be valuable to obtain prognostic information in patients with severe TBI as well as in monitoring the response of the brain to injury.
Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by pathological deposits of β-amyloid (Aβ) in senile plaques, intracellular neurofibrillary tangles (NFTs) comprising hyperphosphorylated aggregated tau, synaptic dysfunction and neuronal death. Substantial evidence indicates that disrupted neuronal calcium homeostasis is an early event in AD that could mediate synaptic dysfunction and neuronal toxicity. Sodium calcium exchangers (NCXs) play important roles in regulating intracellular calcium, and accumulating data suggests that reduced NCX function, following aberrant proteolytic cleavage of these exchangers, may contribute to neurodegeneration. Here, we show that elevated calpain, but not caspase-3, activity is a prominent feature of AD brain. In addition, we observe increased calpain-mediated cleavage of NCX3, but not a related family member NCX1, in AD brain relative to unaffected tissue and that from other neurodegenerative conditions. Moreover, the extent of NCX3 proteolysis correlated significantly with amounts of Aβ1–42. We also show that exposure of primary cortical neurons to oligomeric Aβ1–42 results in calpain-dependent cleavage of NCX3, and we demonstrate that loss of NCX3 function is associated with Aβ toxicity. Our findings suggest that Aβ mediates calpain cleavage of NCX3 in AD brain and therefore that reduced NCX3 activity could contribute to the sustained increases in intraneuronal calcium concentrations that are associated with synaptic and neuronal dysfunction in AD.
Alzheimer’s disease; beta-amyloid; calcium; calpain; sodium calcium exchanger; tau
High brain and acute leukemia, cytoplasmic (BAALC) expression defines an important risk factor in cytogenetically normal acute myeloid leukemia (CN-AML). The prognostic value of BAALC expression in relation to other molecular prognosticators was analyzed in 326 CN-AML patients (<65 years). At diagnosis, high BAALC expression was associated with prognostically adverse mutations: FLT3 internal tandem duplication (FLT3-ITD) with an FLT3-ITD/FLT3 wild-type (wt) ratio of ⩾0.5 (P=0.001), partial tandem duplications within the MLL gene (MLL-PTD) (P=0.002), RUNX1 mutations (mut) (P<0.001) and WT1mut (P=0.001), while it was negatively associated with NPM1mut (P<0.001). However, high BAALC expression was also associated with prognostically favorable biallelic CEBPA (P=0.001). Survival analysis revealed an independent adverse prognostic impact of high BAALC expression on overall survival (OS) and event-free survival (EFS), and also on OS when eliminating the effect of allogeneic stem cell transplantation (SCT) (OSTXcens). Furthermore, we analyzed BAALC expression in 416 diagnostic and follow-up samples of 66 patients. During follow-up, BAALC expression correlated with mutational load or expression levels, respectively, of other minimal residual disease markers: FLT3-ITD (r=0.650, P<0.001), MLL-PTD (r=0.728, P<0.001), NPM1mut (r=0.599, P<0.001) and RUNX1mut (r=0.889, P<0.001). Moreover, a reduction in BAALC expression after the second cycle of induction chemotherapy was associated with improved EFS. Thus, our data underline the utility of BAALC expression as a marker for prognostic risk stratification and detection of residual disease in CN-AML.
BAALC expression; CN-AML; prognosis; MRD
Therapeutic products that depend on the use of an in vitro diagnostic biomarker test to confirm their effectiveness are increasingly being developed. Use of biomarkers is particularly meaningful in the context of selecting the patient population where the therapeutic treatment is believed to be efficacious (patient enrichment). Currently available 'research-use-only' assays for Alzheimer's disease diagnosis all suffer from non-analyte and analyte-specific interferences. The impact of these interferences on the outcome of the assays is not well understood. The confounding factors are hampering correct value determination in biological samples and are intrinsic to the assay concept, the assay design, the presence in the sample of heterophilic antibodies and auto-antibodies, or might be the result of the therapeutic approach. This review focuses on the importance of assay interferences and considers how these might be minimized with the final aim of making the assays more acceptable as in vitro diagnostic biomarker tests for theranostic use.
Neurobiochemical marker levels in blood after traumatic brain injury (TBI) may reflect structural changes detected by neuroimaging. This study evaluates whether correlations between neuronal (ubiquitin carboxy-terminal hydrolase-L1 [UCH-L1]) and glial (glial fibrillary acidic protein [GFAP]) biomarkers may be used as an indicator for differing intracranial pathologies after brain trauma. In 59 patients with severe TBI (Glasgow Coma Scale [GCS] score≤8) serum samples were obtained at the time of hospital admission and analyzed for UCH-L1 and GFAP. Glial neuronal ratio (GNR) was evaluated as the ratio between GFAP and UCH-L1 concentrations. A logistic regression analysis was used to identify variables associated with type of injury. GNR had a median of 0.85 and was positively correlated with age (R=0.45, p=0.003). Twenty-nine patients presented with diffuse injury and 30 with focal mass lesions as assessed by CT scan at admission and classified according to the Marshall Classification. GNR was significantly higher in the focal mass lesion group compared with the diffuse injury group (1.77 versus 0.48, respectively; p=0.003). Receiver operating characteristic curve analysis showed that GNR discriminated between types of injury (area under the curve [AUC]=0.72; p=0.003). GNR was more accurate earlier (≤12 h after injury) than later (AUC=0.80; p=0.002). Increased GNR was independently associated with type of injury, but not age, gender, GCS score, or mechanism of injury. GNR was significantly higher in patients who died, but was not an independent predictor of death. The data from the present study indicate that GNR provides valuable information about different injury pathways, which may be of diagnostic significance. In addition, GNR may help to identify different pathophysiological mechanisms following different types of brain trauma, with implications for therapeutic interventions.
biomarkers; computed tomography; diagnostic; glial neuronal ratio; traumatic brain injury
The somatodendritic A-current, ISA, in hippocampal CA1 pyramidal neurons regulates the processing of synaptic inputs and the amplitude of back propagating action potentials into the dendritic tree, as well as the action potential firing properties at the soma. In this study, we have used RNA interference and over-expression to show that expression of the Kv4.2 gene specifically regulates the ISA component of A-current in these neurons. In dissociated hippocampal pyramidal neuron cultures, or organotypic cultured CA1 pyramidal neurons, the expression level of Kv4.2 is such that the ISA channels are maintained in the population at a peak conductance of approximately 950 pS/pF. Suppression of Kv4.2 transcripts in hippocampal pyramidal neurons using an RNA interference vector suppresses ISA current by 60% in 2 days, similar to the effect of expressing dominant-negative Kv4 channel constructs. Increasing the expression of Kv4.2 in these neurons increases the level of ISA to 170% of the normal set point without altering the biophysical properties. Our results establish a specific role for native Kv4.2 transcripts in forming and maintaining ISA current at characteristic levels in hippocampal pyramidal neurons.
A-current; dominant–negative; hippocampal pyramidal neurons; Kv4 potassium channels; RNA interference; viral vectors
In Poland, because breast cancer detection is delayed, patients usually undergo amputation or breast reconstruction. Surgeons believe that delayed reconstruction yields better aesthetic results compared with immediate reconstruction after mastectomy. Reconstruction is achieved by using either the patient’s own tissues or a tissue expander, which is later exchanged for a prosthesis/expandable implant. The two-stage reconstruction method (expander and prosthesis) is considered to be optimal because the implant position can be corrected. This study evaluated the aesthetic results of 54 patients who underwent the two-stage breast reconstruction method.
Presently, breast cancer detection is delayed in Poland and, thus, the only other option for patients is amputation and breast reconstruction (immediate or delayed). Reconstructive methods are based on using the patient’s own tissue (pedicled or free myocutaneous flaps) or implants (a tissue expander, which is later exchanged for a prosthesis or an expandable implant).
To evaluate the aesthetic results of a delayed two-stage breast reconstruction with the use of implants (expander and prosthesis) in patients who have previously undergone cancer-related mastectomy.
From 2006 to 2009, 54 patients (34 to 65 years of age) underwent reconstruction at least one year after their mastectomy and adjuvant chemotherapy; three women also received x-ray therapy. All women underwent a two-stage treatment with a tissue expander, which was later exchanged for a prosthesis.
Outcomes of the surgery (evaluated by the physician and the patient at least six months after all stages of reconstruction) were found to be very good in 42 patients and good in 12 patients. After amputation and x-ray therapy in two cases, a fistula developed, which necessitated implant removal.
After amputation, breast reconstruction with implants (expander and prosthesis) provides good aesthetic results. The method is mildly burdening to the patient and does not cause severe scarring. Symmetrization of the second breast is often recommended; however, the cost is not covered by the national health system. In principle, earlier x-ray therapy disqualifies the application of implants. Dividing reconstruction into two stages (expander and prosthesis) allows for possible correction of prosthesis placement.
Breast implant; Breast reconstruction; Delayed; Prosthesis; Tissue expander; Two stage