Inefficient white matter activity in Schizophrenia evoked during intra and inter-hemispheric communication

Intensive cognitive tasks induce inefficient regional and network responses in schizophrenia (SCZ). fMRI-based studies have naturally focused on gray matter, but appropriately titrated visuo-motor integration tasks reliably activate inter- and intra-hemispheric white matter pathways. Such tasks can assess network inefficiency without demanding intensive cognitive effort. Here, we provide the first application of this framework to the study of white matter functional responses in SCZ. Event-related fMRI data were acquired from 28 patients (nine females, mean age 43.3, ±11.7) and 28 age- and gender-comparable controls (nine females, mean age 42.1 ± 10.1), using the Poffenberger paradigm, a rapid visual detection task used to induce intra- (ipsi-lateral visual and motor cortex) or inter-hemispheric (contra-lateral visual and motor cortex) transfer. fMRI data were pre- and post-processed to reliably isolate activations in white matter, using probabilistic tractography-based white matter tracts. For intra- and inter-hemispheric transfer conditions, SCZ evinced hyper-activations in longitudinal and transverse white matter tracts, with hyper-activation in sub-regions of the corpus callosum primarily observed during inter-hemispheric transfer. Evidence for the functional inefficiency of white matter was observed in conjunction with small (~50 ms) but significant increases in response times. Functional inefficiencies in SCZ are (1) observable in white matter, with the degree of inefficiency contextually related to task-conditions, and (2) are evoked by simple detection tasks without intense cognitive processing. These cumulative results while expanding our understanding of this dys-connection syndrome, also extend the search of biomarkers beyond the traditional realm of fMRI studies of gray matter.

Incidental findings on brain MRI in patients with first-episode and chronic psychosis

Brain incidental findings (IFs) are unexpected brain abnormalities detected by a structural magnetic resonance (MRI) examination. We conducted a study to assess whether brain IFs are associated with first-episode psychosis (FEP) and chronic psychosis (affective vs. non-affective) compared to healthy controls (HC). Chi-squared analyses were run to compare the frequency of several IFs across groups. Logistic regression analyses were run to explore the association between group and IFs, accounting for sex, age, MRI field strength. We observed a higher frequency of most IFs in both FEP and chronic psychosis groups compared to HC, however most of the chi-squared tests did not reach significance. Patients with FEP and chronic psychosis were 3-4 times more likely to show deep white matter hyperintensities (WMH) than HC. Patients with FEP and affective chronic psychosis were 3-4 times more likely to show ventricular asymmetries than HC. All chronic patients were more likely to show periventricular WMH, liquoral spaces enlargements and ventricular system enlargements respectively. Our results suggest that deep WMH and ventricular asymmetries are associated with both the early and the chronic stages of psychosis, thus representing potential vulnerability factors already present before the onset of the symptoms, possibly due to neurodevelopmental insults.

Magnetic Resonance Spectroscopy in Adolescent Cannabis Users: Metabolites in the Anterior Cingulate Cortex Reflects Individual Differences in Personality Traits and can Affect Rehabilitation Compliance

Introduction

The anterior cingulate cortex (ACC) has shown to play a role in impulsivity, fear, and anxiety. Considering, its high glutamate receptor density, it was chosen as a region of interest to investigate the role of glutamate transmission in drug dependance. We investigated the correlations between personality trait scores and glutamate-to-glutamine (Glx) ratio concentrations in the ACC in order to evaluate if (1) personality traits may increase the probability of drug use and (2) drug use can modify cerebral metabolic pattern contributing to addictive behaviors.

Materials and Methods

Glx ratio concentrations in the ACC region were measured with high-resolution multivoxel proton magnetic resonance spectroscopy (1H-MRS). Personality traits were evaluated utilizing Cloninger's TCI-revised test. Bivariate correlations between personality scores of 28 teens cannabis users (males, mean age = 18.54 ± 2.80) were evaluated.

Results

In the ACC, we observed negative correlation between GG concentrations (r = -0.44, P = 0.05) and co-operativeness values (CO), choline (cho), and novelty seeking (NS) values (r = -0,45, P = 0.05). Low levels of glutamate and high levels of cho in the ACC were closely related to the CO and NS personality traits.

Conclusions

Metabolic and personality patterns seems to be related to the risk of substance predisposition in adolescents. Our data contribute a possible support to the "top-down" control of the ACC on brain metabolism, due to the particular cerebral metabolic pattern found in "drug-using" adolescents.

Resting state networks activity in euthymic bipolar disorder

OBJECTIVES

Bipolar disorder (BD) is a psychiatric condition causing shifts in mood, energy and activity levels severely altering the quality of life of the patients even in the euthymic phase. Although widely accepted, the neurobiological bases of the disorder in the euthymic phase remain elusive. This study aims at characterizing resting state functional activity of the BD euthymic phase in order to better understand the pathogenesis of the disease and build future neurobiological models.

METHODS

Fifteen euthymic BD patients (10 females; mean age 40.2; standard deviation 13.5; range 20-61) and 27 healthy controls (HC) (21 females; mean age 37; standard deviation 10.6; range 22-60) underwent a 3T functional MRI scan at rest. Resting state activity was extracted through independent component analysis (ICA) run with automatic dimensionality estimation.

RESULTS

ICA identified 22 resting state networks (RSNs). Within-network analysis revealed decreased connectivity in the visual, temporal, motor and cerebellar RSNs of BD patients vs HC. Between-network analysis showed increased connectivity between motor area and the default mode network (DMN) partially overlapping with the fronto-parietal network (FPN) in BD patients.

CONCLUSION

Within-network analysis confirmed existing evidence of altered cerebellar, temporal, motor and visual networks in BD. Increased connectivity between the DMN and the motor area network suggests the presence of alterations of the fronto-parietal regions, precuneus and cingulate cortex in the euthymic condition. These findings indicate that specific connectivity alterations might persist even in the euthymic state suggesting the importance of examining both within and between-network connectivity to achieve a global understanding of the BD euthymic condition.

Magnetic resonance diffusion-tensor imaging metrics in High Grade Gliomas: Correlation with IDH1 gene status in WHO 2016 era

PURPOSE

To evaluate any possible correlation between the presence of Isocitrate DeHydrogenase 1 mutation (IDH1m) and specific DTI (Diffusion Tensor Imaging) metrics, such as Fractional Anisotropy (FA), Mean Diffusivity (MD), Radial Diffusivity (RD) and Axial Diffusivity (AD).

METHODS

We retrospectively analyzed 47 patients who underwent an advanced-MR study with DTI followed by surgical intervention with a subsequent histologic diagnosis of High-Grade Glioma (HGG) and immunohistochemical evaluation of IDH1 (Isocitrate DeHydrogenase) mutation status. For each DTI metrics we measured the ratio between tumor and normal tissue and we evaluated the correlation with IDH1 mutation.

RESULTS

We observed a positive correlation with IDH1 status and RD and MD data. No correlation was demonstrated between IDH1 status and FA and AD.

DISCUSSION

Our results support the hypothesis that the number of residual axonal fibers, extracellular matrix composition and the presence of colliquated tissue, may together contribute to a global RD increase in HGG, with a relatively higher increase in IDH1m tumors.

CONCLUSIONS

Our data are in favor of a need for multimodal advance evaluation of HGG. DTI metrics help to analyze IDH1 mutation status, in order to better characterize the lesions and to tailor treatment and follow up.

Hippocampal Subfield Volumes in Patients With First-Episode Psychosis

Background

Hippocampal abnormalities have been largely reported in patients with schizophrenia and bipolar disorder, and are considered to be involved in the pathophysiology of the psychosis. The hippocampus consists of several subfields but it remains unclear their involvement in the early stages of psychosis.

Aim

The aim of this study was to investigate volumetric alterations in hippocampal subfields in patients at the first-episode psychosis (FEP).

Methods

Magnetic resonance imaging (MRI) data were collected in 134 subjects (58 FEP patients; 76 healthy controls [HC]). A novel automated hippocampal segmentation algorithm was used to segment the hippocampal subfields, based on an atlas constructed from ultra-high resolution imaging on ex vivo hippocampal tissue. The general linear model was used to investigate volume differences between FEP patients and HC, with age, gender and total intracranial volume as covariates.

Results

We found significantly lower volumes of bilateral CA1, CA4, and granule cell layer (GCL), and of left CA3, and left molecular layer (ML) in FEP patients compared to HC. Only the volumes of the left hippocampus and its subfields were significantly lower in FEP than HC at the False Discovery Rate (FDR) of 0.1. No correlation was found between hippocampal subfield volume and duration of illness, age of onset, duration of medication, and Positive and Negative Syndrome Scale (PANSS).

Conclusion

We report abnormally low volumes of left hippocampal subfields in patients with FEP, sustaining its role as a putative neural marker of psychosis onset.

Erratum to: Activations in gray and white matter are modulated by uni-manual responses during within and inter-hemispheric transfer: effects of response hand and right-handedness

The original version of this article unfortunately contained a mistake. The family name of Paolo Brambilla was incorrectly spelled as Bambilla.

Hybrid luminescent porous silicon for efficient drug loading and release

In recent decades, biocompatible and light emitting porous silicon (pSi) showed the possibility for use in biomedical applications.

Free water elimination improves test-retest reproducibility of diffusion tensor imaging indices in the brain: A longitudinal multisite study of healthy elderly subjects

Free water elimination (FWE) in brain diffusion MRI has been shown to improve tissue specificity in human white matter characterization both in health and in disease. Relative to the classical diffusion tensor imaging (DTI) model, FWE is also expected to increase sensitivity to microstructural changes in longitudinal studies. However, it is not clear if these two models differ in their test-retest reproducibility. This study compares a bi-tensor model for FWE with DTI by extending a previous longitudinal-reproducibility 3T multisite study (10 sites, 7 different scanner models) of 50 healthy elderly participants (55-80 years old) scanned in two sessions at least 1 week apart. We computed the reproducibility of commonly used DTI metrics (FA: fractional anisotropy, MD: mean diffusivity, RD: radial diffusivity, and AXD: axial diffusivity), derived either using a DTI model or a FWE model. The DTI metrics were evaluated over 48 white-matter regions of the JHU-ICBM-DTI-81 white-matter labels atlas, and reproducibility errors were assessed. We found that relative to the DTI model, FWE significantly reduced reproducibility errors in most areas tested. In particular, for the FA and MD metrics, there was an average reduction of approximately 1% in the reproducibility error. The reproducibility scores did not significantly differ across sites. This study shows that FWE improves sensitivity and is thus promising for clinical applications, with the potential to identify more subtle changes. The increased reproducibility allows for smaller sample size or shorter trials in studies evaluating biomarkers of disease progression or treatment effects. Hum Brain Mapp 38:12-26, 2017. © 2016 Wiley Periodicals, Inc.

Test-retest reliability of the default mode network in a multi-centric fMRI study of healthy elderly: Effects of data-driven physiological noise correction techniques

Understanding how to reduce the influence of physiological noise in resting state fMRI data is important for the interpretation of functional brain connectivity. Limited data is currently available to assess the performance of physiological noise correction techniques, in particular when evaluating longitudinal changes in the default mode network (DMN) of healthy elderly participants. In this 3T harmonized multisite fMRI study, we investigated how different retrospective physiological noise correction (rPNC) methods influence the within-site test-retest reliability and the across-site reproducibility consistency of DMN-derived measurements across 13 MRI sites. Elderly participants were scanned twice at least a week apart (five participants per site). The rPNC methods were: none (NPC), Tissue-based regression, PESTICA and FSL-FIX. The DMN at the single subject level was robustly identified using ICA methods in all rPNC conditions. The methods significantly affected the mean z-scores and, albeit less markedly, the cluster-size in the DMN; in particular, FSL-FIX tended to increase the DMN z-scores compared to others. Within-site test-retest reliability was consistent across sites, with no differences across rPNC methods. The absolute percent errors were in the range of 5-11% for DMN z-scores and cluster-size reliability. DMN pattern overlap was in the range 60-65%. In particular, no rPNC method showed a significant reliability improvement relative to NPC. However, FSL-FIX and Tissue-based physiological correction methods showed both similar and significant improvements of reproducibility consistency across the consortium (ICC = 0.67) for the DMN z-scores relative to NPC. Overall these findings support the use of rPNC methods like tissue-based or FSL-FIX to characterize multisite longitudinal changes of intrinsic functional connectivity. Hum Brain Mapp 37:2114-2132, 2016. © 2016 Wiley Periodicals, Inc.

Classification of first-episode psychosis in a large cohort of patients using support vector machine and multiple kernel learning techniques

First episode psychosis (FEP) patients are of particular interest for neuroimaging investigations because of the absence of confounding effects due to medications and chronicity. Nonetheless, imaging data are prone to heterogeneity because for example of age, gender or parameter setting differences. With this work, we wanted to take into account possible nuisance effects of age and gender differences across dataset, not correcting the data as a pre-processing step, but including the effect of nuisance covariates in the classification phase. To this aim, we developed a method which, based on multiple kernel learning (MKL), exploits the effect of these confounding variables with a subject-depending kernel weighting procedure. We applied this method to a dataset of cortical thickness obtained from structural magnetic resonance images (MRI) of 127 FEP patients and 127 healthy controls, who underwent either a 3Tesla (T) or a 1.5T MRI acquisition. We obtained good accuracies, notably better than those obtained with standard SVM or MKL methods, up to more than 80% for frontal and temporal areas. To our best knowledge, this is the largest classification study in FEP population, showing that fronto-temporal cortical thickness can be used as a potential marker to classify patients with psychosis.

Longitudinal reproducibility of automatically segmented hippocampal subfields: A multisite European 3T study on healthy elderly

Recently, there has been an increased interest in the use of automatically segmented subfields of the human hippocampal formation derived from magnetic resonance imaging (MRI). However, little is known about the test-retest reproducibility of such measures, particularly in the context of multisite studies. Here, we report the reproducibility of automated Freesurfer hippocampal subfields segmentations in 65 healthy elderly enrolled in a consortium of 13 3T MRI sites (five subjects per site). Participants were scanned in two sessions (test and retest) at least one week apart. Each session included two anatomical 3D T1 MRI acquisitions harmonized in the consortium. We evaluated the test-retest reproducibility of subfields segmentation (i) to assess the effects of averaging two within-session T1 images and (ii) to compare subfields with whole hippocampus volume and spatial reliability. We found that within-session averaging of two T1 images significantly improved the reproducibility of all hippocampal subfields but not that of the whole hippocampus. Volumetric and spatial reproducibility across MRI sites were very good for the whole hippocampus, CA2-3, CA4-dentate gyrus (DG), subiculum (reproducibility error∼2% and DICE > 0.90), good for CA1 and presubiculum (reproducibility error ∼ 5% and DICE ∼ 0.90), and poorer for fimbria and hippocampal fissure (reproducibility error ∼ 15% and DICE < 0.80). Spearman's correlations confirmed that test-retest reproducibility improved with volume size. Despite considerable differences of MRI scanner configurations, we found consistent hippocampal subfields volumes estimation. CA2-3, CA4-DG, and sub-CA1 (subiculum, presubiculum, and CA1 pooled together) gave test-retest reproducibility similar to the whole hippocampus. Our findings suggest that the larger hippocampal subfields volume may be reliable longitudinal markers in multisite studies.

Diffuse alterations in grey and white matter associated with cognitive impairment in Shwachman-Diamond syndrome: evidence from a multimodal approach

Shwachman-Diamond syndrome is a rare recessive genetic disease caused by mutations in SBDS gene, at chromosome 7q11. Phenotypically, the syndrome is characterized by exocrine pancreatic insufficiency, bone marrow dysfunction, skeletal dysplasia and variable cognitive impairments. Structural brain abnormalities (smaller head circumference and decreased brain volume) have also been reported. No correlation studies between brain abnormalities and neuropsychological features have yet been performed. In this study we investigate neuroanatomical findings, neurofunctional pathways and cognitive functioning of Shwachman-Diamond syndrome subjects compared with healthy controls. To be eligible for inclusion, participants were required to have known SBDS mutations on both alleles, no history of cranial trauma or any standard contraindication to magnetic resonance imaging. Appropriate tests were used to assess cognitive functions. The static images were acquired on a 3 × 0 T magnetic resonance scanner and blood oxygen level-dependent functional magnetic resonance imaging data were collected both during the execution of the Stroop task and at rest. Diffusion tensor imaging was used to assess brain white matter. The Tract-based Spatial Statistics package and probabilistic tractography were used to characterize white matter pathways. Nine participants (5 males), half of all the subjects aged 9-19 years included in the Italian Shwachman-Diamond Syndrome Registry, were evaluated and compared with nine healthy subjects, matched for sex and age. The patients performed less well than norms and controls on cognitive tasks (p = 0.0002). Overall, cortical thickness was greater in the patients, both in the left (+10%) and in the right (+15%) hemisphere, significantly differently increased in the temporal (left and right, p = 0.04), and right parietal (p = 0.03) lobes and in Brodmann area 44 (p = 0.04) of the right frontal lobe. The greatest increases were observed in the left limbic-anterior cingulate cortex (≥43%, p < 0.0004). Only in Broca's area in the left hemisphere did the patients show a thinner cortical thickness than that of controls (p = 0.01). Diffusion tensor imaging showed large, significant difference increases in both fractional anisotropy (+37%, p < 0.0001) and mean diffusivity (+35%, p < 0.005); the Tract-based Spatial Statistics analysis identified six abnormal clusters of white matter fibres in the fronto-callosal, right fronto-external capsulae, left fronto-parietal, right pontine, temporo-mesial and left anterior-medial-temporal regions. Brain areas activated during the Stroop task and those active during the resting state, are different, fewer and smaller in patients and correlate with worse performance (p = 0.002). Cognitive impairment in Shwachman-Diamond syndrome subjects is associated with diffuse brain anomalies in the grey matter (verbal skills with BA44 and BA20 in the right hemisphere; perceptual skills with BA5, 37, 20, 21, 42 in the left hemisphere) and white matter connectivity (verbal skills with alterations in the fronto-occipital fasciculus and with the inferior-longitudinal fasciculus; perceptual skills with the arcuate fasciculus, limbic and ponto-cerebellar fasciculus; memory skills with the arcuate fasciculus; executive functions with the anterior cingulated and arcuate fasciculus).

Awake surgery between art and science. Part I: clinical and operative settings

Awake surgery requires coordinated teamwork and communication between the surgeon and the anesthesiologist, as he monitors the patient, the neuroradiologist as he interprets the images for intraoperative confirmation, and the neuropsychologist and neurophysiologist as they evaluate in real-time the patient's responses to commands and questions. To improve comparison across published studies on clinical assessment and operative settings in awake surgery, we reviewed the literature, focusing on methodological differences and aims. In complex, interdisciplinary medical care, such differences can affect the outcome and the cost-benefit ratio of the treatment. Standardization of intraoperative mapping and related controversies will be discussed in Part II.

Awake surgery between art and science. Part I: clinical and operative settings

Awake surgery requires coordinated teamwork and communication between the surgeon and the anesthesiologist, as he monitors the patient, the neuroradiologist as he interprets the images for intraoperative confirmation, and the neuropsychologist and neurophysiologist as they evaluate in real-time the patient's responses to commands and questions. To improve comparison across published studies on clinical assessment and operative settings in awake surgery, we reviewed the literature, focusing on methodological differences and aims. In complex, interdisciplinary medical care, such differences can affect the outcome and the cost-benefit ratio of the treatment. Standardization of intraoperative mapping and related controversies will be discussed in Part II.

Cerebral perfusion alterations in epileptic patients during peri-ictal and post-ictal phase: PASL vs DSC-MRI

Non-invasive pulsed arterial spin labeling (PASL) MRI is a method to study brain perfusion that does not require the administration of a contrast agent, which makes it a valuable diagnostic tool as it reduces cost and side effects. The purpose of the present study was to establish the viability of PASL as an alternative to dynamic susceptibility contrast (DSC-MRI) and other perfusion imaging methods in characterizing changes in perfusion patterns caused by seizures in epileptic patients. We evaluated 19 patients with PASL. Of these, the 9 affected by high-frequency seizures were observed during the peri-ictal period (within 5hours since the last seizure), while the 10 patients affected by low-frequency seizures were observed in the post-ictal period. For comparison, 17/19 patients were also evaluated with DSC-MRI and CBF/CBV. PASL imaging showed focal vascular changes, which allowed the classification of patients in three categories: 8 patients characterized by increased perfusion, 4 patients with normal perfusion and 7 patients with decreased perfusion. PASL perfusion imaging findings were comparable to those obtained by DSC-MRI. Since PASL is a) sensitive to vascular alterations induced by epileptic seizures, b) comparable to DSC-MRI for detecting perfusion asymmetries, c) potentially capable of detecting time-related perfusion changes, it can be recommended for repeated evaluations, to identify the epileptic focus, and in follow-up and/or therapy-response assessment.

Early MRI changes in glioblastoma in the period between surgery and adjuvant therapy

To investigate the increase in MRI contrast enhancement (CE) occurring in glioblastoma during the period between surgery and initiation of chemo-radiotherapy, thirty-seven patients with newly diagnosed glioblastoma were analyzed by early post-operative magnetic resonance (EPMR) imaging within three days of surgery and by pre-adjuvant magnetic resonance (PAMR) examination before adjuvant therapy. Areas of new CE were investigated by use of EPMR diffusion-weighted imaging and PAMR perfusion imaging (by arterial spin-labeling). PAMR was acquired, on average, 29.9 days later than EPMR (range 20-37 days). During this period an increased area of CE was observed for 17/37 patients. For 3/17 patients these regions were confined to areas of reduced EPMR diffusion, suggesting postsurgical infarct. For the other 14/17 patients, these areas suggested progression. For 11/17 patients the co-occurrence of hyperperfusion in PAMR perfusion suggested progression. PAMR perfusion and EPMR diffusion did not give consistent results for 3/17 patients for whom small new areas of CE were observed, presumably because of the poor spatial resolution of perfusion imaging. Before initiation of adjuvant therapy, areas of new CE of resected glioblastomas are frequently observed. Most of these suggest tumor progression, according to EPMR diffusion and PAMR perfusion criteria.

Enlarged hypothalamic volumes in schizophrenia

Hypothalamic abnormalities in schizophrenia have been associated with endocrine dysfunctions and stress response. The hypothalamus is involved in several pathways found disrupted in schizophrenia (e.g., hypothalamic-pituitary-adrenal axis, HPA axis); however the available results on potential structural hypothalamic alterations are still controversial. The aim of the study was to investigate the volumes of the hypothalamus and the mammillary bodies in patients with schizophrenia and healthy controls. Twenty-six patients with schizophrenia and 26 healthy controls underwent a 3 Tesla magnetic resonance imaging (MRI) scan. Hypothalamus and mammillary bodies were manually traced by a rater who was blind to subjects' identity. The General Linear Model was used in group comparisons of the volumes of the hypothalamus and the mammillary bodies. The hypothalamus and mammillary body volumes were significantly larger in patients with schizophrenia than controls, with significant enlargement of the left hypothalamus and trends for significantly increased right hypothalamus and right mammillary body. The size of the mammillary bodies was inversely correlated with negative symptoms and directly correlated with anxiety. This study showed abnormally increased sizes of the hypothalamus and the mammillary bodies in schizophrenia. Mammillary bodies volumes were associated to negative symptoms and anxiety. Future longitudinal studies on the volumes of the hypothalamus and the mammillary bodies with respect to the levels of related hormones will clarify their role in modulating HPA axis in schizophrenia.

Allergy to beer in LTP-sensitized patients: beers are not all the same

BACKGROUND

Most cases of beer allergy reported so far have been associated with hypersensitivity to the non-specific lipid transfer protein (LTP). In view of the marked differences in brewing processes we assessed IgE reactivity as well as tolerance to many different beers in an allergic patient.

METHODS

A 45 year-old man hypersensitive to grass pollen, cat dander and Alternaria tenuis with a history of urticaria and dyspnoea after drinking beer and a weak skin reactivity to commercial corn extract was studied. The patient underwent SPT with 36 different brands of beer and an open challenge with those scoring negative was performed. An immunoblot analysis was carried out using 2 SPT-positive beers, 2 SPT-negative beers, and barley, wheat, and maize extracts using both patient's serum and a maize LTP-specific in-house developed polyclonal antibody from rabbit. Further, the immune reactive LTP of one beer was separated by HPLC and the chromatogram was compared to that of purified maize LTP.

RESULTS

Beer SPT scored positive in 30/36 cases. The immunoblot analysis showed IgE reactivity at about 10 kDa against the two SPT-positive beers and against maize with both patient's serum and the polyclonal anti-LTP rabbit serum, whereas the two SPT-negative beers, and barley extract scored negative. The immunodetected protein co-migrated with maize LTP.

CONCLUSION

In beer-allergic patients the diagnostic workup may point to the detection of some tolerated products that can be consumed risk-free.

Production and characterisation of monoclonal antibodies for the quantification of potentially allergenic xylanase from Aspergillus niger

Xylanase from Aspergillus niger (ANX) is widely used in bakeries as a processing aid since it stabilises and improves dough quality. An association between allergic symptoms among bakery workers and sensitisation to ANX has been reported, indicating that this enzyme is an occupational allergen. The presence of ANX in dough improvers and semi-finished goods is often hidden due to incomplete and unclear labelling. The quantification of microbial enzymes in these products is necessary and the determination of the actual concentration of ANX in workplaces is therefore essential to assess the occupational risk. To this purpose we have developed and characterised monoclonal antibodies to ANX. The monoclonal antibodies do not show any cross-reaction with other commonly used microbial enzymes, and they allow the detection of ANX in complex mixtures by ELISA inhibition assays down to the concentration limit of approximately 10 µg kg(-1). These mAbs are a valuable tool to detect and quantify ANX and to investigate its allergenic potential in the workplace.

Mapping the structural brain changes in Alzheimer's disease: the independent contribution of two imaging modalities

The macrostructural atrophy of Alzheimer's disease (AD) has been fully described. Current literature reports that also microstructural alterations occur in AD since the early stages. However, whether the microstructural changes offer unique information independent from macrostructural atrophy is unclear. Aim of this study is to define the independent contribution of macrostructural atrophy and microstructural alterations on AD pathology. The study involved 17 moderate to severe AD patients and 13 healthy controls. All participants underwent conventional and non conventional MRI (respectively, T1-weighted and diffusion-weighted MR scanning). We processed the images in order to obtain gray and white matter volumes to assess macrostructural atrophy, and fractional anisotropy and mean diffusivity to assess the microstructural damage. Analyses of covariance between patients and controls were performed to investigate microstructural tissue damage independent of macrostructural tissue loss, and vice versa, voxel by voxel. We observed microstructural differences, independent of macrostructural atrophy, between patients and controls in temporal and retrosplenial regions, as well as in thalamus, corticopontine tracts, striatum and precentral gyrus. Volumetric differences, independent of microstructural alterations, were observed mainly in the entorhinal cortex, posterior cingulum, and splenium. Measures of microstructural damage provide unique information not obtainable with volumetric mapping in regions known to be pivotal in AD as well as in others thought to be spared. This work expands the understanding of the topography of pathological changes in AD that can be captured with imaging techniques.

Effect of memantine on resting state default mode network activity in Alzheimer's disease

BACKGROUND

Memantine is an approved symptomatic treatment for moderate to severe Alzheimer's disease that reduces the excitotoxic effects of hyperactive glutamatergic transmission. However, the exact mechanism of the effect of memantine in Alzheimer's disease patients is poorly understood. Importantly, the default mode network (DMN), which plays a key role in attention, is hypoactive in Alzheimer's disease and is under glutamatergic control.

OBJECTIVE

To assess the effect of memantine on the activity of the DMN in moderate to severe Alzheimer's disease.

METHODS

Functional magnetic resonance imaging (MRI) data from 15 patients with moderate to severe Alzheimer's disease, seven treated with memantine (mean ± SD age 77 ± 8 years, mean ± SD Mini-Mental State Examination [MMSE] score 16 ± 5) and eight with placebo (mean ± SD age 76 ± 6 years, mean ± SD MMSE score 13 ± 1), were acquired at baseline (T0) and after 6 months of treatment (T6). Resting state components were extracted after spatial normalization in individual patients with independent component analysis. The consistency of the components was assessed using ICASSO and the DMN was recognized through spatial correlation with a pre-defined template. Voxel-based statistical analyses were performed to study the change in DMN activity from T0 to T6 in the two groups.

RESULTS

At T0, the two groups showed similar DMN activity except in the precuneus and cuneus, where the patients who started treatment with memantine had slightly greater activity (p < 0.05 corrected for familywise error [FWE]). The prospective comparison between T0 and T6 in the treated patients showed increased DMN activation mapping in the precuneus (p < 0.05, FWE corrected), while the prospective comparison in the untreated patients did not show significant changes. The treatment × time interaction term was significant at p < 0.05, FWE corrected.

CONCLUSIONS

The results suggest a positive effect of memantine treatment in patients with moderate to severe Alzheimer's disease, resulting in an increased resting DMN activity in the precuneus region over 6 months. Future studies confirming the present findings are required to further demonstrate the beneficial effects of memantine on the DMN in Alzheimer's disease.

Effect of median-nerve electrical stimulation on BOLD activity in acute ischemic stroke patients

OBJECTIVE

To investigate blood oxygenation level-dependent (BOLD) activation during somatosensory electrical stimulation of the median nerve in acute stroke patients and to determine its correlation with ischemic damage and clinical recovery over time.

METHODS

Fourteen acute stroke patients underwent functional magnetic resonance imaging (fMRI) during contralesional median-nerve electrical stimulation 12-48 h after stroke. Findings were then validated by diffusion tensor imaging (DTI) and motor evoked potential by transcranial magnetic stimulation (TMS).

RESULTS

Poor clinical recovery at three months was noted in four patients with no activation in the early days after stroke, whereas good clinical recovery was observed in eight patients with a normal activation pattern in the primary sensory motor area in the acute phase. In two patients BOLD activation correlated weakly with clinical recovery. Findings from TMS and DTI partially correlated with clinical recovery and functional scores.

CONCLUSIONS

Clinically relevant insights into the "functional reserve" of stroke patients gained with peripheral nerve stimulation during fMRI may carry prognostic value already in the acute period of a cerebrovascular accident.

SIGNIFICANCE

BOLD activation maps could provide insights into the functional organization of the residual systems and could contribute to medical decision making in neurological and rehabilitative treatment.

Microstructural diffusion changes are independent of macrostructural volume loss in moderate to severe Alzheimer's disease

Although it is established that Alzheimer's disease (AD) leads to cerebral macrostructural atrophy, microstructural diffusion changes have also been observed, but it is not yet known whether these changes offer unique information about the disease pathology. Thus, a multi-modal imaging study was conducted to determine the independent contribution of each modality in moderate to severe AD. Seventeen patients with moderate-severe AD and 13 healthy volunteers underwent diffusion-weighted and T1-weighted MR scanning. Images were processed to obtain measures of macrostructural atrophy (gray and white matter volumes) and microstructural damage (fractional anisotropy and mean diffusivity). Microstructural diffusion changes independent of macrostructural loss were investigated using an ANCOVA where macrostructural maps were used as voxel-wise covariates. The reverse ANCOVA model was also assessed, where macrostructural loss was the dependent variable and microstructural diffusion tensor imaging maps were the imaging covariates. Diffusion differences between patients and controls were observed after controlling for volumetric differences in medial temporal, retrosplenial regions, anterior commissure, corona radiata, internal capsule, thalamus, corticopontine tracts, cerebral peduncle, striatum, and precentral gyrus. Independent volumetric differences were observed in the entorhinal cortex, inferior temporal lobe, posterior cingulate cortex, splenium and cerebellum. While it is well known that AD is associated with pronounced volumetric change, this study suggests that measures of microstructure provide unique information not obtainable with volumetric mapping in regions known to be pivotal in AD and in those thought to be spared. As such this work provides great understanding of the topography of pathological changes in AD that can be captured with imaging.

Steady-state activation in somatosensory cortex after changes in stimulus rate during median nerve stimulation

Passive electrical stimulation activates various human somatosensory cortical systems including the contralateral primary somatosensory area (SI), bilateral secondary somatosensory area (SII) and bilateral insula. The effect of stimulation frequency on blood oxygenation level-dependent (BOLD) activity remains unclear. We acquired 3-T functional magnetic resonance imaging (fMRI) in eight healthy volunteers during electrical median nerve stimulation at frequencies of 1, 3 and 10 Hz. During stimulation BOLD signal changes showed activation in the contralateral SI, bilateral SII and bilateral insula. Results of fMRI analysis showed that these areas were progressively active with the increase of rate of stimulation. As a major finding, the contralateral SI showed an increase of peak of BOLD activation from 1 to 3 Hz but reached a plateau during 10-Hz stimulation. Our finding is of interest for basic research and for clinical applications in subjects unable to perform cognitive tasks in the fMRI scanner.

The non-specific lipid transfer protein, Ara h 9, is an important allergen in peanut

BACKGROUND

Plant food allergy in the Mediterranean area is mainly caused by non-specific lipid transfer proteins (nsLTP). The aim of this study was to characterize peanut nsLTP in comparison with peach nsLTP, Pru p 3, and assess its importance in peanut allergy.

METHODS

Peanut-allergic patients from Spain (n=32) were included on the basis of a positive case history and either a positive skin prick test or specific IgE to peanut. For comparison, sera of 41 peanut-allergic subjects from outside the Mediterranean area were used. Natural Ara h 9 and two isoforms of recombinant Ara h 9, expressed in Pichia pastoris, were purified using a two-step chromatographic procedure. Allergen characterization was carried out by N-terminal sequencing, circular dichroism (CD) spectroscopy, immunoblotting, IgE inhibition tests and basophil histamine release assays.

RESULTS

Compared with natural peanut nsLTP, the recombinant proteins could be purified in high amounts from yeast supernatant (> or =45 mg/L). The identity of the proteins was verified by N-terminal amino acid sequencing and with rabbit nsLTP-specific antibodies. CD spectroscopy revealed similar secondary structures for all preparations and Pru p 3. The Ara h 9 isoforms showed 62-68% amino acid sequence identity with Pru p 3. IgE antibody reactivity to rAra h 9 was present in 29/32 Spanish and 6/41 non-Mediterranean subjects. Recombinant Ara h 9 showed strong cross-reactivity to nPru p 3 and similar IgE-binding capacity as nAra h 9. The two Ara h 9 isoforms displayed similar IgE reactivity. In peanut-allergic patients with concomitant peach allergy, Ara h 9 showed a weaker allergenic potency than Pru p 3 in histamine release assays.

CONCLUSIONS

Ara h 9 is a major allergen in peanut-allergic patients from the Mediterranean area. Ara h 9 is capable of inducing histamine release from basophils, but to a lesser extent than Pru p 3.

Review of corpus callosum topography, analysis of diffusion values for the different callosal fibers and sex differences

Conventional MRI shows the morphology of the corpus callosum (CC), but does not reveal cortical connectivity or structural information on the CC. Here, we applied diffusion tensor imaging (DTI) in conjunction with a tract-tracing algorithm to incorporate cortical connectivity information on the CC in 40 subjects and to detect the main area and sex structural differences. CC parcellation was based on trajectories to different cortical (prefrontal, frontal motor/premotor/supplementary motor connections, parieto-occipital, temporal) and sub-cortical areas (capsular/basal ganglia connections). In agreement with recent DTI studies, we found that motor fibers occupy a much larger portion of the CC than previously believed on the basis of anatomical data. Differences in anisotropy values were instead in agreement with previous morphological evidence of smaller fibers in the anterior and posterior portions of the CC. The main sex difference was observed in anisotropy values in frontal fibers that proved to be lower in females than in males. Statistically significant differences in the regional diffusion parameters and between sexes give rise to many important questions regarding fiber organization patterns, CC microstructure and the functional relevance of these differences and provide evidence for the role of DTI, which reaches beyond the information given by morphological analysis.

Mapping local hippocampal changes in Alzheimer's disease and normal ageing with MRI at 3 Tesla

Histological studies have suggested differing involvement of the hippocampal subfields in ageing and in Alzheimer's disease. The aim of this study was to assess in vivo local hippocampal changes in ageing and Alzheimer's disease based on high resolution MRI at 3 Tesla. T(1)-weighted images were acquired from 19 Alzheimer's disease patients [age 76 +/- 6 years, three males, Mini-Mental State Examination 13 +/- 4] and 19 controls (age 74 +/- 5 years, 11 males, Mini-Mental State Examination 29 +/- 1). The hippocampal formation was isolated by manual tracing. Radial atrophy mapping was used to assess group differences and correlations by averaging hippocampal shapes across subjects using 3D parametric surface mesh models. Percentage difference, Pearson's r, and significance maps were produced. Hippocampal volumes were inversely correlated with age in older healthy controls (r = 0.56 and 0.6 to the right and left, respectively, P < 0.05, corresponding to 14% lower volume for every 10 years of older age from ages 65 to 85 years). Ageing-associated atrophy mapped to medial and lateral areas of the tail and body corresponding to the CA1 subfield and ventral areas of the head corresponding to the presubiculum. Significantly increased volume with older age mapped to a few small spots mainly located to the CA1 sector of the right hippocampus. Volumes were 35% and 30% smaller in Alzheimer's disease patients to the right and left (P < 0.0005). Alzheimer's disease-associated atrophy mapped not only to CA1 areas of the body and tail corresponding to those also associated with age, but also to dorsal CA1 areas of the head unaffected by age. Regions corresponding to the CA2-3 fields were relatively spared in both ageing and Alzheimer's disease. Hippocampal atrophy in Alzheimer's disease maps to areas in the body and tail that partly overlap those affected by normal ageing. Specific areas in the anterior and dorsal CA1 subfield involved in Alzheimer's disease were not in normal ageing. These patterns might relate to differential neural systems involved in Alzheimer's disease and ageing.

Oral allergy syndrome to fig

BACKGROUND

The few cases of food allergy to fig reported to date, whose main manifestations were anaphylactic reactions, have been related to a cross-sensitisation to weeping fig (Ficus benjamina) or to the 'latex-fruit syndrome'. Here we report on two cases of the oral allergy syndrome (OAS) to fig in patients whose main allergic manifestations were related to sensitisation to grass and birch pollens.

METHODS

The patients were characterised by clinical history, skin prick tests (SPT) with commercial and in-house extracts, prick-by-prick test, specific IgE measurements and challenge tests. PBS-soluble and insoluble extracts of both fig skin and pulp were examined for the presence of potential allergens by IgE immunoblotting.

RESULTS

Both patients showed OAS followed by respiratory symptoms when challenged with fig. They were negative in both specific IgE detection and SPT with commercial extracts of fig and many other plant materials, including F. benjamina and Hevea Brasiliensis, while grass and birch pollens gave positive results. Prick-by-prick tests and SPT with in-house extracts indicated that the fig skin had a much higher allergenicity than the pulp. Despite negative IgE detection by the CAP assay, immunoblotting experiments showed that potential fig allergens were PBS-soluble and present only in the skin of the fruit.

CONCLUSIONS

OAS to fig followed by respiratory symptoms can be present in patients not sensitised to weeping fig or having the latex-fruit syndrome. Different parts of the fig can have different allergenicities, the most important allergens being proteins related to the skin of the fruit. Improved commercial fig extracts to be used for the diagnosis of this type of allergy have to be developed.

Theophylline: a diagnostic aid for evaluating chronic airways obstruction

A study was carried out on the use of theophylline (240 mg by infusion) as a functional diagnostic test in patients showing severe chronic airways obstruction. The preliminary results suggested that the pharmacologic action of theophylline (a bronchodilating and vasoactive drug) helps discriminate the different types of anatomo-functional impairments present during a severe chronic bronchial obstruction. The changes in VA and VA/Qc induced by the drug were evaluated. The presence of a lesion mainly affecting the airways or the parenchyma of the lung might be identified by these changes.