Factors determining whether diffuse large B-cell lymphoma samples are detected by flow cytometry.

INTRODUCTION: Flow cytometry (FCM) is widely used in the diagnosis of mature B-cell neoplasms (MBN), and FCM data are usually consistent with morphological findings. However, diffuse large B-cell lymphoma (DLBCL), a common MBN, is sometimes not detected by FCM. This study aimed to explore factors that increase the likelihood of failure to detect DLBCL by FCM. METHODS: Cases with a final diagnosis of DLBCL that were analysed by eight-colour FCM were retrospectively collated. Clinical, FCM, histopathological and genetic data were compared between cases detected and cases not detected by FCM. RESULTS: DLBCL cases from 135 different patients were analysed, of which 22 (16%) were not detected by FCM. In samples not detected by flow cytometry, lymphocytes were a lower percentage of total events (p = 0.02), and T cells were a higher percentage of total lymphocytes (p = 0.01). Cases with high MYC protein expression on immunohistochemistry were less likely to be missed by FCM (p = 0.011). Detection of DLBCL was not different between germinal centre B-cell (GCB) and non-GCB subtypes, not significantly affected by the presence of necrosis or fibrosis, and not significantly different between biopsy specimens compared to fine-needle aspirates, or between samples from nodal compared to extranodal tissue. CONCLUSION: The study identifies several factors which affect the likelihood of DLBCL being missed by FCM. Even with eight-colour analysis, FCM fails to detect numerous cases of DLBCL.

Investigating the human binocular visual system using multi-modal magnetic resonance imaging.

Having two forward-facing eyes with slightly different viewpoints enables animals, including humans, to discriminate fine differences in depth (disparities), which can facilitate interaction with the world. The binocular visual system starts in the primary visual cortex because that is where information from the eyes is integrated for the first time. Magnetic resonance imaging (MRI) is an ideal tool to non-invasively investigate this system since it can provide a range of detailed measures about structure, function, neurochemistry and connectivity of the human brain. Since binocular disparity is used for both action and object recognition, the binocular visual system is a valuable model system in neuroscience for understanding how basic sensory cues are transformed into behaviourally relevant signals. In this review, we consider how MRI has contributed to the understanding of binocular vision and depth perception in the human brain. Firstly, MRI provides the ability to image the entire brain simultaneously to compare the contribution of specific visual areas to depth perception. A large body of work using functional MRI has led to an understanding of the extensive networks of brain areas involved in depth perception, but also the fine-scale macro-organisation for binocular processing within individual visual areas. Secondly, MRI can uncover mechanistic information underlying binocular combination with the use of MR spectroscopy. This method can quantify neurotransmitters including GABA and glutamate within restricted regions of the brain, and evaluate the role of these inhibitory and excitatory neurochemicals in binocular vision. Thirdly, it is possible to measure the nature and microstructure of pathways underlying depth perception using diffusion MRI. Understanding these pathways provides insight into the importance of the connections between areas implicated in depth perception. Finally, MRI can help to understand changes in the visual system resulting from amblyopia, a neural condition where binocular vision does not develop correctly in childhood.

MRI Stereoscope: A Miniature Stereoscope for Human Neuroimaging.

Stereoscopic vision enables the perception of depth. To study the brain mechanisms behind stereoscopic vision using noninvasive brain imaging (magnetic resonance brain imaging; MRI), scientists need to reproduce the independent views of the left and right eyes in the brain scanner using "dichoptic" displays. However, high-quality dichoptic displays are technically challenging and costly to implement in the MRI scanner. The novel miniature stereoscope system ("MRI stereoscope") is an affordable and open-source tool that displays high-quality dichoptic images inside the MRI scanner. The MRI stereoscope takes advantage of commonly used display equipment, the MRI head coil, and a display screen. To validate the MRI stereoscope, binocular disparity stimuli were presented in a 3T MRI scanner while neural activation was recorded using functional MRI in six human participants. The comparison of large binocular disparities compared with disparities close to zero evoked strong responses across dorsal and ventral extra-striate visual cortex. In contrast, binocularly anti-correlated stimuli, which are not perceived in depth, did not evoke comparable activation. These results are the proof-of-concept that the MRI stereoscope can deliver dichoptic images that produce the perception of stereoscopic depth during acquisition of MR responses. Application of the MRI stereoscope to neuroscience can help to address important questions in perception and consciousness.

Comparison of flow cytometry with other modalities in the diagnosis of myelodysplastic syndrome.

INTRODUCTION: The myelodysplastic syndromes (MDSs) are heterogeneous myeloid malignancies, conventionally diagnosed by cytomorphology and cytogenetics, with an emerging role for flow cytometry. This study compared the performance of a 4-parameter flow cytometry scoring system, the Ogata Score, with other modalities in the diagnosis of MDS. METHODS: Bone marrow aspirate and trephine biopsies from 238 patients performed to assess for possible MDS were analysed, and the flow cytometry score was retrospectively applied. The sensitivity and specificity of the flow cytometry score, the aspirate microscopy, the trephine microscopy with immunohistochemistry, and cytogenetic and molecular results were determined relative to the final diagnosis. RESULTS: The medical records of the 238 patients were reviewed to determine the final clinical diagnosis made at the time of the bone marrow examination. This final diagnosis of MDS, possible MDS or not MDS, was based on clinical features and laboratory tests, including all parameters of the bone marrow investigation, except for the flow cytometry score, which was only determined for this study. The flow cytometry score was 67.4% sensitive and 93.8% specific. Aspirate microscopy had higher sensitivity (83.7%) and similar specificity (92.0%), whereas trephine microscopy had similar sensitivity (66.3%) and specificity (89.4%) to flow cytometry. Although the flow cytometry score had a lower sensitivity than aspirate microscopy, in 18 patients (7.6% of the total) the flow cytometry score was positive for MDS, whereas aspirate microscopy was negative or inconclusive. CONCLUSION: The flow cytometry score and trephine microscopy exhibited reasonable sensitivity and high specificity, and complement aspirate microscopy in the assessment of MDS.

GABAergic inhibition in the human visual cortex relates to eye dominance.

Binocular vision is created by fusing the separate inputs arriving from the left and right eyes. 'Eye dominance' provides a measure of the perceptual dominance of one eye over the other. Theoretical models suggest that eye dominance is related to reciprocal inhibition between monocular units in the primary visual cortex, the first location where the binocular input is combined. As the specific inhibitory interactions in the binocular visual system critically depend on the presence of visual input, we sought to test the role of inhibition by measuring the inhibitory neurotransmitter GABA during monocular visual stimulation of the dominant and the non-dominant eye. GABA levels were measured in a single volume of interest in the early visual cortex, including V1 from both hemispheres, using a combined functional magnetic resonance imaging and magnetic resonance spectroscopy (combined fMRI-MRS) sequence on a 7-Tesla MRI scanner. Individuals with stronger eye dominance had a greater difference in GABAergic inhibition between the eyes. This relationship was present only when the visual system was actively processing sensory input and was not present at rest. We provide the first evidence that imbalances in GABA levels during ongoing sensory processing are related to eye dominance in the human visual cortex. Our finding supports the view that intracortical inhibition underlies normal eye dominance.

Human primary visual cortex shows larger population receptive fields for binocular disparity-defined stimuli.

The visual perception of 3D depth is underpinned by the brain's ability to combine signals from the left and right eyes to produce a neural representation of binocular disparity for perception and behaviour. Electrophysiological studies of binocular disparity over the past 2 decades have investigated the computational role of neurons in area V1 for binocular combination, while more recent neuroimaging investigations have focused on identifying specific roles for different extrastriate visual areas in depth perception. Here we investigate the population receptive field properties of neural responses to binocular information in striate and extrastriate cortical visual areas using ultra-high field fMRI. We measured BOLD fMRI responses while participants viewed retinotopic mapping stimuli defined by different visual properties: contrast, luminance, motion, correlated and anti-correlated stereoscopic disparity. By fitting each condition with a population receptive field model, we compared quantitatively the size of the population receptive field for disparity-specific stimulation. We found larger population receptive fields for disparity compared with contrast and luminance in area V1, the first stage of binocular combination, which likely reflects the binocular integration zone, an interpretation supported by modelling of the binocular energy model. A similar pattern was found in region LOC, where it may reflect the role of disparity as a cue for 3D shape. These findings provide insight into the binocular receptive field properties underlying processing for human stereoscopic vision.

Correlated structure of neuronal firing in macaque visual cortex limits information for binocular depth discrimination.

Variability in cortical neural activity potentially limits sensory discriminations. Theoretical work shows that information required to discriminate two similar stimuli is limited by the correlation structure of cortical variability. We investigated these information-limiting correlations by recording simultaneously from visual cortical areas primary visual cortex (V1) and extrastriate area V4 in macaque monkeys performing a binocular, stereo depth discrimination task. Within both areas, noise correlations on a rapid temporal scale (20-30 ms) were stronger for neuron pairs with similar selectivity for binocular depth, meaning that these correlations potentially limit information for making the discrimination. Between-area correlations (V1 to V4) were different, being weaker for neuron pairs with similar tuning and having a slower temporal scale (100+ ms). Fluctuations in these information-limiting correlations just prior to the detection event were associated with changes in behavioral accuracy. Although these correlations limit the recovery of information about sensory targets, their impact may be curtailed by integrative processing of signals across multiple brain areas.NEW & NOTEWORTHY Correlated noise reduces the stimulus information in visual cortical neurons during experimental performance of binocular depth discriminations. The temporal scale of these correlations is important. Rapid (20-30 ms) correlations reduce information within and between areas V1 and V4, whereas slow (>100 ms) correlations between areas do not. Separate cortical areas appear to act together to maintain signal fidelity. Rapid correlations reduce the neuronal signal difference between stimuli and adversely affect perceptual discrimination.

A survey of neurosurgical management and prognostication of traumatic brain injury following the RESCUEicp trial.

PURPOSE: Decompressive craniectomy remains controversial because of uncertainty regarding its benefit to patients; this study aimed to explore current practice following the RESCUEicp Trial, an important study in the evolving literature on decompressive craniectomies. MATERIALS AND METHODS: Neurosurgeons in New Zealand, Australia, USA and Nepal were sent a survey consisting of two case scenarios and several multi-choice questions exploring their utilisation of decompressive craniectomy following the RESCUEicp Trial. RESULTS: One in ten neurosurgeons (n = 6, 10.3%) were no longer performing decompressive craniectomies for TBI following the RESCUEicp Trial and two fifths (n = 23, 39.7%) were less enthusiastic. Most neurosurgeons would not operate in the face of severe disability (n = 46, 79.3%) or vegetative state/death (n = 57, 98.3%). Neurosurgeons tended give more optimistic prognoses than the CRASH prognostic model. Those who suggested more pessimistic prognoses and those who use decision support tools were less likely to advise decompressive surgery. CONCLUSIONS: RESCUEicp has had a notable impact on neurosurgeons and their management of TBI. Although there remains no clear clinical consensus on the contraindications for decompressive craniectomy, most neurosurgeons would not operate if severe disability or vegetative state (the rates of which are increased by such surgery) seemed likely. Whilst unreliable, prognostic estimates still have an impact on clinical decision making and neurosurgical management. Wider use of decision support tools should be considered.

Concurrent Pituicytoma, Meningioma, and Cavernomas After Cranial Irradiation for Childhood Acute Lymphoblastic Leukemia.

BACKGROUND: The majority of patients with acute lymphoblastic leukaemia develop disease relapse in the central nervous system in the absence of central nervous system-directed prophylactic therapy. In the past, prophylactic cranial irradiation was commonly used in the form of whole-brain radiotherapy in patients with acute lymphoblastic leukemia to prevent the development of intracranial diseases. However, in addition to the inherent risk of toxicity, this type of therapy has several delayed side effects including the development of secondary intracranial tumors. CASE DESCRIPTION: We report a rare case of a patient with concurrent pituicytoma, meningioma, and cavernomas 44 years after prophylactic cranial irradiation for childhood acute lymphoblastic leukemia. The patient presented with visual disturbance, headache, and features of hypopituitarism. Endoscopic transsphenoidal resection of the pituicytoma and meningioma was performed. Subsequent regrowth of the residual meningioma necessitated further surgery and adjuvant treatment with radiotherapy. CONCLUSIONS: This case report highlights the unusual case of a patient with 3 concurrent intracranial lesions of distinct pathologies after prophylactic cranial irradiation therapy for childhood acute lymphoblastic leukemia.

Recognition for Vision.

When children grow up, the first word or first step in walking is always a significant event [...].

Comparison of Neurochemical and BOLD Signal Contrast Response Functions in the Human Visual Cortex.

We investigated the relationship between neurochemical and hemodynamic responses as a function of image contrast in the human primary visual cortex (V1). Simultaneously acquired BOLD-fMRI and single voxel proton MR spectroscopy signals were measured in V1 of 24 healthy human participants of either sex at 7 tesla field strength, in response to presentations (64 s blocks) of different levels of image contrast (3%, 12.5%, 50%, 100%). Our results suggest that complementary measures of neurotransmission and energy metabolism are in partial agreement: BOLD and glutamate signals were linear with image contrast; however, a significant increase in glutamate concentration was evident only at the highest intensity level. In contrast, GABA signals were steady across all intensity levels. These results suggest that neurochemical concentrations are maintained at lower ranges of contrast levels, which match the statistics of natural vision, and that high stimulus intensity may be critical to increase sensitivity to visually modulated glutamate signals in the early visual cortex using MR spectroscopy.SIGNIFICANCE STATEMENT Glutamate and GABA are the major excitatory and inhibitory neurotransmitters of the brain. To better understand the relationship between MRS-visible neurochemicals, the BOLD signal change, and stimulus intensity, we measured combined neurochemical and BOLD signals (combined fMRI-MRS) to different image contrasts in human V1 at 7 tesla. While a linear change to contrast was present for both signals, the increase in glutamate was significant only at the highest stimulus intensity. These results suggest that hemodynamic and neurochemical signals reflect common metabolic markers of neural activity, whereas the mismatch at lower contrast levels may indicate a sensitivity threshold for detecting neurochemical changes during visual processing. Our results highlight the challenge and importance of reconciling cellular and metabolic measures of neural activity in the human brain.

Normative cerebral cortical thickness for human visual areas.

Studies of changes in cerebral neocortical thickness often rely on small control samples for comparison with specific populations with abnormal visual systems. We present a normative dataset for FreeSurfer-derived cortical thickness across 25 human visual areas derived from 960 participants in the Human Connectome Project. Cortical thickness varies systematically across visual areas, in broad agreement with canonical visual system hierarchies in the dorsal and ventral pathways. In addition, cortical thickness estimates show consistent within-subject variability and reliability. Importantly, cortical thickness estimates in visual areas are well described by a normal distribution, making them amenable to direct statistical comparison.

Preserved extrastriate visual network in a monkey with substantial, naturally occurring damage to primary visual cortex.

Lesions of primary visual cortex (V1) lead to loss of conscious visual perception with significant impact on human patients. Understanding the neural consequences of such damage may aid the development of rehabilitation methods. In this rare case of a Rhesus macaque (monkey S), likely born without V1, the animal's in-group behaviour was unremarkable, but visual task training was impaired. With multi-modal magnetic resonance imaging, visual structures outside of the lesion appeared normal. Visual stimulation under anaesthesia with checkerboards activated lateral geniculate nucleus of monkey S, while full-field moving dots activated pulvinar. Visual cortical activation was sparse but included face patches. Consistently across lesion and control monkeys, functional connectivity analysis revealed an intact network of bilateral dorsal visual areas temporally correlated with V5/MT activation, even without V1. Despite robust subcortical responses to visual stimulation, we found little evidence for strengthened subcortical input to V5/MT supporting residual visual function or blindsight-like phenomena.

Remediation of 137Cs contaminated concrete using electrokinetic phenomena and ionic salt washes in nuclear energy contexts.

This work describes the first known the use of electrokinetic treatments and ionic salt washes to remediate concrete contaminated with 137Cs. A series of experiments were performed on concrete samples, contaminated with K+ and 137Cs, using a bespoke migration cell and an applied electric field (60V potential gradient and current limit of 35mA). Additionally, two samples were treated with an ionic salt wash (≤400molm-3 of KCl) alongside the electrokinetic treatment. The results show that the combined treatment produces removal efficiencies three times higher (>60%) than the electrokinetic treatment alone and that the decontamination efficiency appears to be proportional to the initial degree of contamination. Furthermore, the decontamination efficiencies are equivalent to previous electrokinetic studies that utilised hazardous chemical enhancement agents demonstrating the potential of the technique for use on nuclear licensed site. The results highlight the relationship between the initial contamination concentration within the concrete and achievable removal efficiency of electrokinetic treatment and other treatments. This information would be useful when selecting the most appropriate decontamination techniques for particular contamination scenarios.

Combined fMRI-MRS acquires simultaneous glutamate and BOLD-fMRI signals in the human brain.

Combined fMRI-MRS is a novel method to non-invasively investigate functional activation in the human brain using simultaneous acquisition of hemodynamic and neurochemical measures. The aim of the current study was to quantify neural activity using combined fMRI-MRS at 7T. BOLD-fMRI and semi-LASER localization MRS data were acquired from the visual cortex of 13 participants during short blocks (64s) of flickering checkerboards. We demonstrate a correlation between glutamate and BOLD-fMRI time courses (R=0.381, p=0.031). In addition, we show increases in BOLD-fMRI (1.43±0.17%) and glutamate concentrations (0.15±0.05 I.U., ~2%) during visual stimulation. In contrast, we observed no change in glutamate concentrations in resting state MRS data during sham stimulation periods. Spectral line width changes generated by the BOLD-response were corrected using line broadening. In summary, our results establish the feasibility of concurrent measurements of BOLD-fMRI and neurochemicals using a novel combined fMRI-MRS sequence. Our findings strengthen the link between glutamate and functional activity in the human brain by demonstrating a significant correlation of BOLD-fMRI and glutamate over time, and by showing ~2% glutamate increases during 64s of visual stimulation. Our tool may become useful for studies characterizing functional dynamics between neurochemicals and hemodynamics in health and disease.

An evaluation of language in brain tumor patients using a new cognitively motivated testing protocol.

OBJECTIVE: To characterize the language impairments that occur in brain tumor patients using a cognitively oriented theoretical framework. METHOD: Forty-nine preoperative brain tumor patients completed a new testing protocol (the BLAST) which assesses 8 well documented, "core" cognitive skills required for language: auditory word recognition, accessing semantic knowledge, lexical selection, phonological encoding, verbal short-term memory, goal-driven language selection, verb retrieval, and articulatory-motor planning. Patients were unselected with respect to lesion location. RESULTS: A surprising 65% of patients scored below controls on at least 1 core skill. Patients with left temporal tumors, as a group, had lower scores than the remaining patients on phonological encoding, accessing semantic knowledge and verbal short-term memory (STM). Those with left frontal tumors had the lowest scores on articulatory-motor planning. These findings are broadly consistent with previous studies examining the anatomical substrates of our "core" cognitive processes. CONCLUSIONS: We conclude that selective impairments in key language skills are common in brain tumor patients, but many of these are not adequately assessed on conventional aphasia assessments. Our protocol may provide a useful resource for preoperative, postoperative and intraoperative language assessment in this population. (PsycINFO Database Record

Polychromatic flow cytometry is more sensitive than microscopy in detecting small monoclonal plasma cell populations.

BACKGROUND: There is an emerging role for flow cytometry (FC) in the assessment of small populations of plasma cells (PC). However, FC's utility has been questioned due to consistent underestimation of the percentage of PC compared to microscopy. METHODS: A retrospective study was performed on bone marrow samples analysed by 8-colour FC. Plasma cell populations were classified as polyclonal or monoclonal based on FC analysis. FC findings were compared with microscopy of aspirates, histology and immunohistochemistry of trephine biopsies, and immunofixation (IFX) of serum and/or urine. RESULTS: FC underestimated PC compared to aspirate and trephine microscopy. The 10% diagnostic cutoff for MM on aspirate microscopy corresponded to a 3.5% cutoff on FC. Abnormal plasma cell morphology by aspirate microscopy and clonality by FC correlated in 229 of 294 cases (78%). However, in 50 cases, FC demonstrated a monoclonal population but microscopy reported no abnormality. In 15 cases, abnormalities were reported by microscopy but not by FC. Clonality assessment by trephine microscopy and FC agreed in 251/280 cases (90%), but all 29 discordant cases were monoclonal by FC and not monoclonal by microscopy. These cases had fewer PC and proportionally more polyclonal PC, and when IFX detected a paraprotein, it had the same light chain as in the PC determined by FC. CONCLUSIONS: FC was more sensitive in detecting monoclonal populations that were small or accompanied by polyclonal PC. This study supports the inclusion of FC in the evaluation of PC, especially in the assessment of small populations. © 2016 International Clinical Cytometry Society.

Vision in our three-dimensional world.

Many aspects of our perceptual experience are dominated by the fact that our two eyes point forward. Whilst the location of our eyes leaves the environment behind our head inaccessible to vision, co-ordinated use of our two eyes gives us direct access to the three-dimensional structure of the scene in front of us, through the mechanism of stereoscopic vision. Scientific understanding of the different brain regions involved in stereoscopic vision and three-dimensional spatial cognition is changing rapidly, with consequent influences on fields as diverse as clinical practice in ophthalmology and the technology of virtual reality devices.This article is part of the themed issue 'Vision in our three-dimensional world'.

Defining the V5/MT neuronal pool for perceptual decisions in a visual stereo-motion task.

In the primate visual cortex, neurons signal differences in the appearance of objects with high precision. However, not all activated neurons contribute directly to perception. We defined the perceptual pool in extrastriate visual area V5/MT for a stereo-motion task, based on trial-by-trial co-variation between perceptual decisions and neuronal firing (choice probability (CP)). Macaque monkeys were trained to discriminate the direction of rotation of a cylinder, using the binocular depth between the moving dots that form its front and rear surfaces. We manipulated the activity of single neurons trial-to-trial by introducing task-irrelevant stimulus changes: dot motion in cylinders was aligned with neuronal preference on only half the trials, so that neurons were strongly activated with high firing rates on some trials and considerably less activated on others. We show that single neurons maintain high neurometric sensitivity for binocular depth in the face of substantial changes in firing rate. CP was correlated with neurometric sensitivity, not level of activation. In contrast, for individual neurons, the correlation between perceptual choice and neuronal activity may be fundamentally different when responding to different stimulus versions. Therefore, neuronal pools supporting sensory discrimination must be structured flexibly and independently for each stimulus configuration to be discriminated.This article is part of the themed issue 'Vision in our three-dimensional world'.