Validation of microscopic magnetochiral dichroism theory.

Magnetochiral dichroism (MChD), a fascinating manifestation of the light-matter interaction characteristic for chiral systems under magnetic fields, has become a well-established optical phenomenon reported for many different materials. However, its interpretation remains essentially phenomenological and qualitative, because the existing microscopic theory has not been quantitatively confirmed by confronting calculations based on this theory with experimental data. Here, we report the experimental low-temperature MChD spectra of two archetypal chiral paramagnetic crystals taken as model systems, tris(1,2-diaminoethane)nickel(II) and cobalt(II) nitrate, for light propagating parallel or perpendicular to the c axis of the crystals, and the calculation of the MChD spectra for the Ni(II) derivative by state-of-the-art quantum chemical calculations. By incorporating vibronic coupling, we find good agreement between experiment and theory, which opens the way for MChD to develop into a powerful chiral spectroscopic tool and provide fundamental insights for the chemical design of new magnetochiral materials for technological applications.

Unveiling phonons in a molecular qubit with four-dimensional inelastic neutron scattering and density functional theory.

Phonons are the main source of relaxation in molecular nanomagnets, and different mechanisms have been proposed in order to explain the wealth of experimental findings. However, very limited experimental investigations on phonons in these systems have been performed so far, yielding no information about their dispersions. Here we exploit state-of-the-art single-crystal inelastic neutron scattering to directly measure for the first time phonon dispersions in a prototypical molecular qubit. Both acoustic and optical branches are detected in crystals of [VO(acac)[Formula: see text]] along different directions in the reciprocal space. Using energies and polarisation vectors calculated with state-of-the-art Density Functional Theory, we reproduce important qualitative features of [VO(acac)[Formula: see text]] phonon modes, such as the presence of low-lying optical branches. Moreover, we evidence phonon anti-crossings involving acoustic and optical branches, yielding significant transfers of the spin-phonon coupling strength between the different modes.

Development of a deep convolutional neural network to predict grading of canine meningiomas from magnetic resonance images.

An established deep neural network (DNN) based on transfer learning and a newly designed DNN were tested to predict the grade of meningiomas from magnetic resonance (MR) images in dogs and to determine the accuracy of classification of using pre- and post-contrast T1-weighted (T1W), and T2-weighted (T2W) MR images. The images were randomly assigned to a training set, a validation set and a test set, comprising 60%, 10% and 30% of images, respectively. The combination of DNN and MR sequence displaying the highest discriminating accuracy was used to develop an image classifier to predict the grading of new cases. The algorithm based on transfer learning using the established DNN did not provide satisfactory results, whereas the newly designed DNN had high classification accuracy. On the basis of classification accuracy, an image classifier built on the newly designed DNN using post-contrast T1W images was developed. This image classifier correctly predicted the grading of 8 out of 10 images not included in the data set.

Coherent coupling between Vanadyl Phthalocyanine spin ensemble and microwave photons: towards integration of molecular spin qubits into quantum circuits.

Electron spins are ideal two-level systems that may couple with microwave photons so that, under specific conditions, coherent spin-photon states can be realized. This represents a fundamental step for the transfer and the manipulation of quantum information. Along with spin impurities in solids, molecular spins in concentrated phases have recently shown coherent dynamics under microwave stimuli. Here we show that it is possible to obtain high cooperativity regime between a molecular Vanadyl Phthalocyanine (VOPc) spin ensemble and a high quality factor superconducting YBa2Cu3O7 (YBCO) coplanar resonator at 0.5 K. This demonstrates that molecular spin centers can be successfully integrated in hybrid quantum devices.

Giant spin-phonon bottleneck effects in evaporable vanadyl-based molecules with long spin coherence.

Vanadium(iv) complexes have recently shown record quantum spin coherence times that in several circumstances are limited by spin-lattice relaxation. The role of the environment and vibronic properties in the low temperature dynamics is here investigated by a comparative study of the magnetization dynamics as a function of crystallite size and the steric hindrance of the ß-diketonate ligands in VO(acac)2 (1), VO(dpm)2 (2) and VO(dbm)2 (3) evaporable complexes (acac- = acetylacetonate, dpm- = dipivaloylmethanate, and dbm- = dibenzoylmethanate). A pronounced crystallite size dependence of the relaxation time is observed at unusually high temperatures (up to 40 K), which is associated with a giant spin-phonon bottleneck effect. We model this behaviour by an ad hoc force field approach derived from density functional theory calculations, which evidences a correlation of the intensity of the phenomenon with ligand dimensions and the unit cell size.

Rearrangement of the dendritic morphology in limbic regions and altered exploratory behavior in a rat model of autism spectrum disorder.

Valproic acid (VPA) is a blocker of histone deacetylase widely used to treat epilepsy, bipolar disorders, and migraine; its administration during pregnancy increases the risk of autism spectrum disorder (ASD) in the child. Thus, prenatal VPA exposure has emerged as a rodent model of ASD. In the present study, we aimed to investigate the effect of prenatal administration of VPA (500mg/kg) at E12.5 on the exploratory behavior and locomotor activity in a novel environment, as well as on neuronal morphological rearrangement in the prefrontal cortex (PFC), in the hippocampus, in the nucleus accumbens (NAcc), and in the basolateral amygdala (BLA) at three different ages: immediately after weaning (postnatal day 21 [PD21]), prepubertal (PD35) and postpubertal (PD70) ages. Hyper-locomotion was observed in a novel environment in VPA animals at PD21 and PD70. Interestingly, exploratory behavior assessed by the hole board test at PD70 showed a reduced frequency but an increase in the duration of head-dippings in VPA-animals compared to vehicle-treated animals. In addition, the latency to the first head-dip was longer in prenatal VPA-treated animals at PD70. Quantitative morphological analysis of dendritic spine density revealed a reduced number of spines at PD70 in the PFC, dorsal hippocampus and BLA, with an increase in the dendritic spine density in NAcc and ventral hippocampus, in prenatal VPA-treated rats. In addition, at PD70 increases in neuronal arborization were observed in the NAcc, layer 3 of the PFC, and BLA, with retracted neuronal arborization in the ventral and dorsal hippocampus. Our results extend the list of altered behaviors (exploratory behavior) detected in this model of ASD, and indicate that the VPA behavioral phenotype is accompanied by previously undescribed morphological rearrangement in limbic regions.

Effect of disease-modifying drugs on cortical lesions and atrophy in relapsing-remitting multiple sclerosis.

OBJECTIVE: To measure the effects of disease-modifying drugs (DMDs) on the development of cortical lesions (CL) and cortical atrophy in patients with relapsing-remitting multiple sclerosis (RRMS). METHODS: RRMS patients (n = 165) were randomized to subcutaneous (sc) interferon (IFN) beta-1a (44 mcg three times weekly), intramuscular (im) IFN beta-1a (30 mcg weekly) or glatiramer acetate (GA; 20 mg daily). The reference population comprised 50 untreated patients. Clinical and MRI examinations were performed at baseline, 12 months and 24 months. RESULTS: One hundred and forty-one treated patients completed the study. After 12 months, 37/50 (74%) of untreated patients developed ≥ 1 new CL (mean 1.6), compared with 30/47 (64%) of im IFN beta-1a-treated patients (mean 1.2, p = 0.021), 24/48 (50%) of GA-treated patients (mean 0.8, p = 0.001) and 12/46 (26%) of sc IFN beta-1a-treated patients (mean 0.4, p < 0.001). After 24 months, ≥ 1 new CL was observed in 41/50 (82%) of untreated (mean 3.0), 34/47 (72%) of im IFN beta-1a-treated (mean 1.6, p < 0.001), 30/48 (62%) of GA-treated (mean 1.3, p < 0.001) and 24/46 (52%) of sc IFN beta-1a-treated patients (mean 0.8, p < 0.001). Mean grey matter fraction decrease in DMD-treated patients at 24 months ranged from 0.7 to 0.8 versus 1.0 in untreated patients (p = 0.023). CONCLUSIONS: Disease-modifying drugs significantly decreased new CL development and cortical atrophy progression compared with untreated patients, with faster and more pronounced effects seen with sc IFN beta-1a than with im IFN beta-1a or GA.

Cortical pathology in multiple sclerosis patients with epilepsy: a 3 year longitudinal study.

INTRODUCTION: The cause of epilepsy in multiple sclerosis (MS) has not yet been elucidated. The relevance of cortical pathology (cortical lesions and thickness) in MS patients with and without epilepsy was evaluated in a longitudinal study. METHODS: 32 relapsing-remitting MS patients with epilepsy (RRMS/E) and 60 matched RRMS patients without epilepsy were included in a 3 year longitudinal study. The following clinical and MR parameters were analysed: Expanded Disability Status Scale (EDSS), cognitive score (CS), cortical lesion (CL) number and volume, grey matter fraction (GMf), global cortical thickness (CTh), T2 white matter lesion volume (T2WMLV), new CLs and new WM lesions. RESULTS: At baseline (T0), CLs were observed in 27/32 (84.4%) RRMS/E and in 26/60 (43.3%) RRMS (p<0.001) patients, and the RRMS/E group had a higher number (10.2 ± 8.9 vs 4.5 ± 2.4; p<0.001) and total volume (2.0 ± 1.3 vs 0.7 ± 0.8 cm(3); p<0.001) of CLs compared with the RRMS group. No significant difference in T2WMLV was observed. Global CTh was lower in RRMS/E (2.12 ± 0.19 vs 2.35 ± 0.14 mm; p<0.001), and this group also showed a decline in cognition (CS 10.9 ± 6.3 vs 6.2 ± 3.5; p<0.001). After 3 years (T1), the RRMS/E group had a higher accumulation of new CLs (3.4 ± 3.2 vs 1.2 ± 1.1; p<0.001) and faster reduction of GMf (p=0.022) while the two groups did not differ in the number of new WM and new Gad+ lesions. DISCUSSION: RRMS/E had a more severe and rapidly evolving cortical pathology (CLs and atrophy) compared with RRMS without epilepsy. The RRMS/E group was also characterised by more pronounced cognitive decline, higher EDSS and higher prevalence of men.

Vagus nerve stimulation modulates cortical synchrony and excitability through the activation of muscarinic receptors.

Vagus nerve stimulation (VNS) is an FDA approved treatment for drug-resistant epilepsy and depression. Recently, we demonstrated the capacity for repeatedly pairing sensory input with brief pulses of VNS to induce input specific reorganization in rat auditory cortex. This was subsequently used to reverse the pathological neural and perceptual correlates of hearing loss induced tinnitus. Despite its therapeutic potential, VNS mechanisms of action remain speculative. In this study, we report the acute effects of VNS on intra-cortical synchrony, excitability, and sensory processing in anesthetized rat auditory cortex. VNS significantly increased and decorrelated spontaneous multi-unit activity, and suppressed entrainment to repetitive noise burst stimulation at 6-8 Hz but not after application of the muscarinic antagonist scopolamine. Collectively, these experiments demonstrate the capacity for VNS to acutely influence cortical synchrony and excitability and strengthen the hypothesis that acetylcholine and muscarinic receptors are involved in VNS mechanisms of action. These results are discussed with respect to their possible implications for sensory processing, neural plasticity, and epilepsy.

Early pericalcarine atrophy in acute optic neuritis is associated with conversion to multiple sclerosis.

BACKGROUND: Previous work showed that pericalcarine cortical volume loss is evident early after presentation with acute clinically isolated optic neuritis (ON). The aims of this study were: (1) to determine whether pericalcarine atrophy in patients with ON is associated with conversion to multiple sclerosis (MS); (2) to investigate whether regional atrophy preferentially affects pericalcarine cortex; and (3) to investigate potential causes of early pericalcarine atrophy using MRI. METHODS: 28 patients with acute ON and 10 controls underwent structural MRI (brain and optic nerves) and were followed-up over 12 months. Associations between the development of MS, optic nerve, optic radiation and pericalcarine cortical damage measures were investigated using multiple linear regression models. Regional cortical volumetric differences between patients and controls were calculated using t tests. RESULTS: The development of MS at 12 months was associated with greater whole brain and optic radiation lesion loads, shorter acute optic nerve lesions and smaller pericalcarine cortical volume at baseline. Regional atrophy was not evident in other sampled cortical regions. Pericalcarine atrophy was not directly associated with whole brain lesion load, optic radiation measures or optic nerve lesion length. However, the association between pericalcarine atrophy and MS was not independent of these parameters. CONCLUSIONS: Reduced pericalcarine cortical volumes in patients with early clinically isolated ON were associated with the development of MS but volumes of other cortical regions were not. Hence pericalcarine cortical regions appear particularly susceptible to early damage. These findings could be explained by a combination of pathological effects to visual grey and white matter in patients with ON.

Imaging distribution and frequency of cortical lesions in patients with multiple sclerosis.

BACKGROUND: The presence of cortical lesions (CLs) and their topographic distribution in the brains of patients with multiple sclerosis (MS) have been clearly shown by recent histopathologic studies. CLs can also be assessed in vivo, with less sensitivity, by using specific MRI sequences. MRI-based lesion probability maps (LPMs) may partially overcome this lack of sensitivity and provide unique information on the spatial distribution and frequency of CLs in MS. METHODS: A total of 149 patients with MS (103 relapsing-remitting [RR] and 46 primary progressive [PP]) underwent an MRI examination, which included the double inversion recovery (DIR) sequence for CL assessment. CL masks were then obtained for each patient and a cortical LPM (cLPM) was created for each MS subtype. RESULTS: CLs were mainly distributed in the frontal (RR = 51.8%; PP = 50.5%) and temporal (RR = 30.4%; PP = 35.5%) lobes, with a prominent involvement of the motor (RR = 37.8%; PP = 30.6%) and anterior cingulate (RR = 9.2%; PP = 10.6%) cortices. The extent of brain lobe affected by CLs was higher in RR than in PP patients. The frequency of CL occurrence was higher in PP than in RR patients. Both measurements, however, did not show differences between the 2 MS subtypes at voxel-wise analysis. CONCLUSIONS: Patients with RRMS and PPMS share more similarities than differences in terms of CL number, volume, topographic distribution, and frequency. The similarities between histopathologic data and the findings reported here suggest that DIR images can accurately illustrate the focal pathology occurring in the cortical regions of patients with MS, providing clinically relevant information.

Widespread cortical thinning characterizes patients with MS with mild cognitive impairment.

BACKGROUND: Although cognitive dysfunction affects a relevant portion of patients with multiple sclerosis (MS), its pathologic substrate has not been clarified and it does not seem entirely explained by white matter changes. METHODS: A total of 100 consecutive patients with relapsing remitting MS (RRMS) and 42 normal controls (NC) were enrolled in the study. Cognitive performance was assessed by Rao's Brief Repeatable Battery of Neuropsychological Tests (BRB). Regional cortical thickness (CTh) was evaluated by Freesurfer. RESULTS: Thirty-one patients with RRMS failed 1 or 2 tests of BRB and were considered to have a mild cognitive impairment (mCI-RRMS), while 8 patients failed at least 3 tests and were classified as markedly impaired (sCI-RRMS). The mean CTh of mCI-RRMS and sCI-RRMS group was significantly lower than in NC (p < 0.001) and cognitively normal patients with RRMS (CN-RRMS) (p < 0.001). The regional analysis revealed significant cortical thinning in frontal and temporal regions (frontotemporal thinning) of CN-RRMS compared to NC, while a widespread pattern of cortical thinning was observed in mCI-RRMS and in sCI-RRMS compared to both CN-RRMS and NC. A correlation was observed between cognitive score (CS) and the mean CTh (r = -0.69, p < 0.001) and between CS and CTh of almost all the cortical areas analyzed (r value between -0.20 and -0.65, p < 0.01). A correlation was found between T2-WM-LV and mean CTh (r = -0.31, p = 0.004) or CS (r = 0.21, p = 0.031). The multivariate analysis confirmed a widespread cortical thinning as the best predictor of cognitive impairment. CONCLUSIONS: A widespread pattern of cortical thinning characterizes patients with cognitive dysfunction, suggesting such dysfunction as expression of a more aggressive and widespread cortical pathology.

[Analysis of acute distal radius fractures with the articular sagittal index (ASI)]. / L'index sagittal articulaire (ISA) pour l'analyse des fractures fraîches du radius distal.

Displacements of articular fragments are not always visible on initial radiographs of acute distal radius fractures. Despite the wide use of CT scan, it may be useful to know a simple index that could suggest an articular displaced fracture from the initial standard radiographs. The authors describe an articular sagittal index (ASI) of the distal radius and provide reference values from a study of 100 healthy volunteers. An increase of the ASI index suggests a displaced articular distal radius fracture with possible impaction.

Cortical lesions in primary progressive multiple sclerosis: a 2-year longitudinal MR study.

BACKGROUND: In primary progressive multiple sclerosis (PPMS), a discrepancy exists between the modest brain white matter (WM) lesion burden and the severity of neurologic disability. Double-inversion recovery (DIR) sequences have improved MRI sensitivity in the detection of cortical lesions (CLs) in patients with relapsing-onset MS. OBJECTIVE: This 2-year longitudinal study was designed to assess the frequency, extent, and rate of formation of CLs in PPMS and their relationship with T2 lesion volume (LV), gray matter (GM) atrophy, and disability. METHODS: Forty-eight patients with PPMS underwent clinical and magnetic resonance examinations at baseline and after 2 years. The number and volume of CLs, WM T2 LV, and GM fraction (GMf) were assessed at baseline and at follow-up. RESULTS: At baseline, CLs were detected in 81.2% of patients with PPMS. At least one new CL was found in 28 patients during the follow-up. In patients with PPMS, CL and T2 WM LVs increased over the follow-up. At baseline, CL number and volumes were significantly correlated with T2 WM LV, GMf, disease duration, and Expanded Disability Status Scale score, as well as with increasing GM atrophy and disability during the follow-up. A multivariate analysis showed that CL volume at baseline was an independent predictor of percentage GM volume change and disability accumulation during the subsequent 2-year period. CONCLUSIONS: Cortical lesions are a frequent finding in primary progressive multiple sclerosis. The extent of such abnormalities is associated with the extent of cortical atrophy and clinical disability, and is able to predict their changes over a medium time period.

Clinical and diagnostic aspects of multiple sclerosis and acute monophasic encephalomyelitis in pediatric patients: a single centre prospective study.

OBJECTIVE: The purpose of the study was to compare and contrast the initial presenting demographic, clinical, neuroimaging, and laboratory features in a cohort of children affected from multiple sclerosis (MS) or acute disseminated encephalomyelitis (ADEM). METHODS: A 12-year prospective study was conducted in 68 pediatric patients (age

Evidence for relative cortical sparing in benign multiple sclerosis: a longitudinal magnetic resonance imaging study.

BACKGROUND: Using double inversion recovery (DIR) MRI, cortical lesions can be seen in the brain of patients with multiple sclerosis (MS). The burden of such lesions seems to be well correlated with the severity of MS-related disability. OBJECTIVE: To investigate whether the extent of cortical damage in patients with benign MS (BMS) might contribute to explain their favorable clinical status. METHODS: Forty-eight patients with BMS (Expanded Disability Status Scale [EDSS] score < or =3.0 and disease duration > or =15 years) and 96 patients with non-disabling, early relapsing-remitting (RR) MS (EDSS score < or =3.0 and disease duration < or =5 years) were studied. Brain MRI, including a DIR and a fluid-attenuated inversion recovery (FLAIR) sequence, was acquired at baseline and after 12 months. On DIR images, intracortical (ICL) and cortical-subcortical lesions (CSL) were identified and their number and volume calculated. Total white matter (WM) lesion volume was quantified on FLAIR images. RESULTS: Compared with early RRMS, patients with BMS had lower number of ICL at both study time points (P < or = 0.001 for both comparisons). At one-year follow-up, a significant increase of ICL and CSL number and total volume was observed only in early patients with RRMS. The number and volume of cortical lesions was not correlated with WM lesion volume. Total ICL number at baseline, total cortical lesion volume at baseline, and total cortical lesion volume change were independent predictors of MS phenotype. CONCLUSION: In patients with BMS, the selective sparing of the cortex from disease-related focal pathology might be one of the factors associated to their favorable clinical status, independently of the (possible) accrual of WM lesions.

Increased fronto-temporal perfusion in bipolar disorder.

OBJECTIVES: Previous imaging reports showed over-activation of fronto-limbic structures in bipolar patients, particularly in response to emotional stimuli. In this study, for the first time, we used perfusion weighted imaging (PWI) to analyze lobar cerebral blood volume (CBV) in bipolar disorder to further explore the vascular component to its pathophysiology. METHODS: Fourteen patients with DSM-IV bipolar disorder (mean age+/-SD=49.00+/-12.30 years; 6 males, 8 females) and 29 normal controls (mean age+/-SD=45.07+/-10.30 years; 13 males, 16 females) were studied. PWI images were obtained following intravenous injection of paramagnetic contrast agent (Gadolinium-DTPA), with a 1.5 T Siemens magnet using an echo-planar sequence. The contrast of enhancement (CE), was calculated pixel by pixel as the ratio of the maximum signal intensity drop during the passage of contrast agent (Sm) by the baseline pre-bolus signal intensity (So) (CE=Sm/So*100) for frontal, temporal, parietal, and occipital lobes, bilaterally, on two axial images. Higher CE values correspond to lower CBV and viceversa. RESULTS: Bipolar patients had significantly lower CE values in left frontal and temporal lobes (p=0.01 and p=0.03, respectively) and significantly inverse laterality index for frontal lobe (p=0.017) compared to normal controls. No significant correlations between CE measure and age or clinical variables were found (p>0.05). CONCLUSION: This study found increased left frontal and temporal CBV in bipolar disorder. Fronto-temporal hyper-perfusion may sustain over-activation of these structures during emotion modulation, which have been observed in patients with bipolar illness.

[Multidetector CT urography: diagnostic role in the evaluation of patients with non-traumatic hematuria]. / Urografia-TC multidetettore: ruolo diagnostico nella valutazione del paziente con ematuria non traumatica.

Blood in the urine (hematuria) can originate from any site along the urinary tract and may be the only sign of renal or vesical malignancy. Therefore, literature recommends for the evaluation of any case of macroscopic or microscopic hematuria. Our aim was to define the diagnostic role of multidetector CT urography (MDCTu) in the evaluation of this symptom through the analysis of 181 consecutive patients from January 2003 to March 2006.

Second-generation sonographic contrast agents in the evaluation of renal trauma.

PURPOSE: The purpose of this study was to define the indications, diagnostic accuracy and limitations of second-generation sonographic contrast agents in the evaluation of patients with renal trauma. MATERIALS AND METHODS: Between March 2004 and April 2005, 277 patients with blunt abdominal trauma were evaluated. Twenty-eight out of 277 patients had renal lesions, the severity of which was graded according to the organ injury severity scale of the American Association for the Surgery of Trauma (AAST). All the patients enrolled in the study had minor trauma and were evaluated with baseline ultrasound (US), contrast-enhanced US after injection of a second-generation contrast agent (SonoVue) and, if positive, with multiphasic multidetector computed tomography (MDCT). RESULTS: Five out of 28 traumatic parenchymal lesions with perirenal fluid collection were identified at baseline US. All 28 renal parenchymal lesions, with or without perirenal or retroperitoneal haematoma, were identified at contrast-enhanced US. Multiphase MDCT confirmed all the cases that were positive at contrast-enhanced US and demonstrated the integrity of the urinary tract in the delayed phase. CONCLUSIONS: Our experience confirmed the diagnostic accuracy of second-generation sonographic contrast material both for diagnosis and for appropriate patient management. In particular, contrast-enhanced sonography proved to be a reliable technique for the evaluation and follow-up of low-grade renal injuries. Its main advantage is reduced radiation exposure, as fewer MDCT examinations are needed, whereas its limitation is the high cost of the technique if used in unselected patients.