Different Mechanisms Underlie the Metabolic Response of GBM Stem-Like Cells to Ionizing Radiation: Biological and MRS Studies on Effects of Photons and Carbon Ions

Glioblastoma multiforme (GBM) is a malignant primary brain tumor with very poor prognosis, high recurrence rate, and failure of chemo-radiotherapy, mainly due to a small fraction of cells with stem-like properties (GSCs). To study the mechanisms of GSCs resistance to radiation, two GSC lines, named line #1 and line #83, with different metabolic patterns and clinical outcome, were irradiated with photon beams and carbon ions and assessed by ¹H Magnetic Resonance Spectroscopy (MRS). Both irradiation modalities induced early cytotoxic effects in line #1 with small effects on cell cycle, whereas a proliferative G2/M cytostatic block was observed in line #83. MR spectroscopy signals from mobile lipids (ML) increased in spectra of line #1 after photon and C-ion irradiation with effects on lipid unsaturation level, whereas no effects were detected in line #83 spectra. Gamma-Aminobutyric Acid (GABA), glutamic acid (glu) and Phosphocreatine (pCr) signals showed a significant variation only for line #1 after carbon ion irradiation. Glucose (glc) level and lactate (Lac) extrusion behaved differently in the two lines. Our findings suggest that the differences in irradiation response of GSCs #1 and #83 lines are likely attributable to their different metabolic fingerprint rather than to the different radiation types.

Longitudinal Multimodal fMRI to Investigate Neurovascular Changes in Spontaneously Hypertensive Rats

Hypertension is an important risk factor for age-related cognitive decline and neuronal pathologies. Studies have shown a correlation between hypertension, disruption in neurovascular coupling and cerebral autoregulation, and cognitive decline. However, the mechanisms behind this are unclear. To further understand this, it is advantageous to study neurovascular coupling as hypertension progresses in a rodent model. Here, we use a longitudinal functional MRI (fMRI) protocol to assess the impact of hypertension on neurovascular coupling in spontaneously hypertensive rats (SHRs). Eight female SHRs were studied at 2, 4, and 6 months of age, as hypertension progressed. Under an IV infusion of propofol, animals underwent fMRI, functional MR spectroscopy, and cerebral blood flow (CBF) quantification to study changes in neurovascular coupling over time. Blood pressure significantly increased at 4 and 6 months (P < .0001). CBF significantly increased at 4 months old (P < .05), in the acute stage of hypertension. The size of the active region decreased significantly at 6 months old (P < .05). Change in glutamate signal during activation, and N-acetyl-aspartate (NAA) signal, remained constant. This study shows that, while cerebral autoregulation is impaired in acute hypertension, the blood oxygenation-level-dependent (BOLD) response remains unaltered until later stages. At this stage, the consistent NAA and glutamate signals show that neuronal death has not occurred, and that neuronal activity is not affected at this stage. This suggests that neuronal activity and viability is not lost until much later, and changes observed here in BOLD activity are due to vascular effects.

Treatment effects on neurometabolite levels in schizophrenia: A meta-analysis dataset of proton magnetic resonance spectroscopy

This article describes a dataset for a meta-analysis that aimed to investigate the effects of treatment on the neurometabolite status in patients with schizophrenia (DOI of original article: https://doi.org/10.1016/j.schres.2020.03.069[1]). The data search was performed with MEDLINE, Embase, and PsycINFO. The neurometabolites investigated include glutamate, glutamine, glutamate + glutamine, gamma-aminobutyric acid, N-acetylaspartate, and myo-inositol, and the regions of interest (ROIs) include the frontal cortex, temporal cortex, parieto-occipital cortex, thalamus, basal ganglia, and hippocampus. The meta-analysis was conducted with a random-effects model, and the use of the standardized mean difference method between pre- and post-treatment of subjects for neurometabolites in each ROI of three patient groups or more. The dataset covers raw data of 39 patient groups (773 patients with schizophrenia at follow-up) with neurometabolite levels measured by magnetic resonance spectroscopy both before and after treatment. Furthermore, it contains details of clinical characteristics and treatment types for each group. Therefore, the data would be useful for a reinvestigation of treatment effects on the neurometabolite status from diverse points of view, as well as for the development of future treatment strategies for psychiatric diseases.

Myocardial Steatosis Among Antiretroviral Therapy-Treated People With Human Immunodeficiency Virus Participating in the REPRIEVE Trial

BACKGROUND

People with human immunodeficiency virus (PWH) face increased risks for heart failure and adverse heart failure outcomes. Myocardial steatosis predisposes to diastolic dysfunction, a heart failure precursor. We aimed to characterize myocardial steatosis and associated potential risk factors among a subset of the Randomized Trial to Prevent Vascular Events in HIV (REPRIEVE) participants.

METHODS

Eighty-two PWH without known heart failure successfully underwent cardiovascular magnetic resonance spectroscopy, yielding data on intramyocardial triglyceride (IMTG) content (a continuous marker for myocardial steatosis extent). Logistic regression models were applied to investigate associations between select clinical characteristics and odds of increased or markedly increased IMTG content.

RESULTS

Median (Q1, Q3) IMTG content was 0.59% (0.28%, 1.15%). IMTG content was increased (> 0.5%) among 52% and markedly increased (> 1.5%) among 22% of participants. Parameters associated with increased IMTG content included age (P = .013), body mass index (BMI) ≥ 25 kg/m2 (P = .055), history of intravenous drug use (IVDU) (P = .033), and nadir CD4 count < 350 cells/mm³ (P = .055). Age and BMI ≥ 25 kg/m2 were additionally associated with increased odds of markedly increased IMTG content (P = .049 and P = .046, respectively).

CONCLUSIONS

A substantial proportion of antiretroviral therapy-treated PWH exhibited myocardial steatosis. Age, BMI ≥ 25 kg/m2, low nadir CD4 count, and history of IVDU emerged as possible risk factors for myocardial steatosis in this group.

CLINICAL TRIALS REGISTRATION

NCT02344290; NCT03238755.

Cystathionine as a marker for 1p/19q codeleted gliomas by in vivo magnetic resonance spectroscopy

BACKGROUND

Codeletion of chromosome arms 1p and 19q (1p/19q codeletion) highly benefits diagnosis and prognosis in gliomas. In this study, we investigated the effect of 1p/19q codeletion on cancer cell metabolism and evaluated possible metabolic targets for tailored therapies.

METHODS

We combined in vivo 1H (proton) magnetic resonance spectroscopy (MRS) measurements in human gliomas with the analysis of a series of standard amino acids by liquid chromatography-mass spectroscopy (LC-MS) in human glioma biopsies. Sixty-five subjects with low-grade glioma were included in the study: 31 underwent the MRI/MRS examination, 47 brain tumor tissue samples were analyzed with LC-MS, and 33 samples were analyzed for gene expression with quantitative PCR. Additionally, we performed metabolic tracer experiments in cell models with 1p deletion.

RESULTS

We report the first in vivo detection of cystathionine by MRS in 1p/19q codeleted gliomas. Selective accumulation of cystathionine was observed in codeleted gliomas in vivo, in brain tissue samples, as well as in cells harboring heterozygous deletions for serine- and cystathionine-pathway genes located on 1p: phosphoglycerate dehydrogenase (PHGDH) and cystathionine gamma-lyase (CTH). Quantitative PCR analyses showed 40-50% lower expression of both PHGDH and CTH in 1p/19q codeleted gliomas compared with their non-codeleted counterparts.

CONCLUSIONS

Our results provide strong evidence of a selective vulnerability of codeleted gliomas to serine and glutathione depletion and point to cystathionine as a possible noninvasive marker of treatment response.

Glutamate metabolites in treatment resistant schizophrenia: A meta-analysis and systematic review of 1H-MRS studies

Nearly a third to half of schizophrenia patients are non-responsive to first-line antipsychotics and are labelled treatment resistant schizophrenia (TRS). Neurochemical abnormalities in TRS may not be dopaminergic but possibly glutamate (Glu) related. Studies that have examined glutamatergic abnormalities using proton magnetic resonance spectroscopy (¹H-MRS) in TRS, have showed inconsistent results. Hence, we conducted a meta-analysis of ¹H-MRS studies comparing levels of Glu-and its metabolites in the brains of TRS and non-treatment resistant schizophrenia (nTRS) patients. Four eligible studies were included in the analysis. Summary effect size for the group difference between TRS (n = 101, including Ultra-TRS) and nTRS (n = 61) in Glu-levels in the anterior cingulate cortex (ACC) as measured with Hedges's g was 0.21 (95% CI: -0.42 to 0.85; p = 0.5) suggesting absence of significant difference. However, on leave one out analysis, one iteration showed significant difference in Glu-levels between the groups (Hedges's g = 0.46; p = 0.02) with higher Glu-levels in TRS implying significant effect of a single study on the effect size. The higher ACC Glu-in TRS was not associated with symptom severity or antipsychotic administration, indicating a possible trait abnormality. The limited number of datasets comparing Glu-metabolites in other brain regions are narratively described. Our analysis is limited by the significant heterogeneity between studies. Further longitudinal, prospective studies are needed to confirm higher Glu-metabolite levels in ACC in TRS and explore this potential trait abnormality.

Clinical and biochemical predictors of late-outcome in patients after ischemic stroke

OBJECTIVE

The aim of this study is to evaluate neurological scales, as well as biochemical and radiological parameters measured on day 10 after ischemic stroke (IS), according to their value as predictors of the long-term outcome.

MATERIAL AND METHODS

45 patients were assessed according to the Barthel Index (BI) and National Institute of Health Stroke Scale (NIHSS) on day 10, and according to Modified Rankin Scale (mRS) 3 months after the onset of IS. On day 10 of IS, the serum level of C-reactive protein (CRP), albumin, D-dimers (DD), S100BB and Tau proteins was measured and the volume of ischemic focus assessed with the use of Computed Tomography (CT). The patients were divided into groups with good outcome (GO) and mRS 0-2, and with bad outcome (BO) and mRS 3-6.

RESULTS

NIHSS and BI scores (p<0.001), the volume of ischemic focus (p<0.01), CRP (p<0.01) and albumin level (p<0.05), but not DD, S100BB and Tau protein levels evaluated on day 10, correlated with mRS after 3 months since IS onset. Patients from the BO group were observed to have lower BI (p=0.001), higher NIHSS (p<0.01) and CRP levels (p<0.05), and bigger volume of ischemic focus (p<0.05) measured on day 10 of IS. In the GO group, there were more patients with atherosclerotic etiology (p=0.02 x2=7.856). Regression analysis showed that only the BI score assessed on day 10 of IS can predict the outcome after 3 months assessed by mRS (OR=1.102, 95%, CI:1.01-1.203; p=0.001).

CONCLUSIONS

BI assessed on day 10 has a predictive value for the outcome evaluated by mRS 3 months after the onset of IS.

Pharmacokinetics, Safety, and Tolerability of Orally Administered Ursodeoxycholic Acid in Patients With Parkinson's Disease-A Pilot Study

Mitochondrial dysfunction is implicated in the pathogenesis of Parkinson's disease. Preliminary data have shown lower brain adenosine triphosphate (ATP) levels in Parkinson's disease versus age-matched healthy controls. Ursodeoxycholic acid (UDCA) may improve impaired mitochondrial function. Our objective was to evaluate UDCA tolerability, pharmacokinetics, and its effect on brain bioenergetics in individuals with Parkinson's disease. An open-label, prospective, multiple-ascending-dose study of oral UDCA in 5 individuals with Parkinson's disease was completed. A blood safety panel, plasma concentrations of UDCA and UDCA conjugates, and brain ATP levels were measured before and after therapy (week 1: 15 mg/kg/day; week 2: 30 mg/kg/day; and weeks 3-6: 50 mg/kg/day). UDCA and conjugates were measured using liquid chromatography-mass spectrometry. ATP levels and ATPase activity were measured using 7-Tesla 31 P magnetic resonance spectroscopy. Secondary measures included the Unified Parkinson's Disease Rating Scale and Montreal Cognitive Assessment. UDCA was generally well tolerated. The most frequent adverse event was gastrointestinal discomfort, rated by subjects as mild to moderate. Noncompartmental pharmacokinetic analysis resulted in (mean ± standard deviation) a maximum concentration of 8749 ± 2840 ng/mL and half-life of 2.1 ± 0.71 hr. Magnetic resonance spectroscopy data were obtained in 3 individuals with Parkinson's disease and showed modest increases in ATP and decreases in ATPase activity. Changes in Unified Parkinson's Disease Rating Scale (parts I-IV) and Montreal Cognitive Assessment scores (mean ± standard deviation) were -4.6 ± 6.4 and 2 ± 1.7, respectively. This is the first report of UDCA use in individuals with Parkinson's disease. Its pharmacokinetics are variable, and at high doses it appears reasonably well tolerated. Our findings warrant additional studies of its effect on brain bioenergetics.

Fitness Level Influences White Matter Microstructure in Postmenopausal Women

Aerobic exercise has both neuroprotective and neurorehabilitative benefits. However, the underlying mechanisms are not fully understood and need to be investigated, especially in postmenopausal women, who are at increased risk of age-related disorders such as Alzheimer’s disease and stroke. To advance our understanding of the potential neurological benefits of aerobic exercise in aging women, we examined anatomical and functional responses that may differentiate women of varying cardiorespiratory fitness using neuroimaging and neurophysiology. A total of 35 healthy postmenopausal women were recruited (59 ± 3 years) and cardiorespiratory fitness estimated (22–70 mL/kg/min). Transcranial magnetic stimulation was used to assess -aminobutyric acid (GABA) and glutamate (Glu) receptor function in the primary motor cortex (M1), and magnetic resonance spectroscopy (MRS) was used to quantify GABA and Glu concentrations in M1. Magnetic resonance imaging was used to assess mean cortical thickness (MCT) of sensorimotor and frontal regions, while the microstructure of sensorimotor and other white matter tracts was evaluated through diffusion tensor imaging. Regression analysis revealed that higher fitness levels were associated with improved microstructure in pre-motor and sensory tracts, and the hippocampal cingulum. Fitness level was not associated with MCT, MRS, or neurophysiology measures. These data indicate that, in postmenopausal women, higher cardiorespiratory fitness is linked with preserved selective white matter microstructure, particularly in areas that influence sensorimotor control and memory.

Negative association between left prefrontal GABA concentration and BDNF serum concentration in young adults

Background

The brain's major inhibitory neurotransmitter gamma-aminobutyric acid (GABA) and the brain-derived neurotrophic factor (BDNF) play important roles in several stress-related disorders. Magnetic resonance spectroscopy (MRS) allows for non-invasive quantification of GABA concentration in the brain. We investigated the relationship between GABA concentration in the left dorsolateral prefrontal cortex (DLPFC) and BDNF concentration in the serum in a community-based sample of young subjects.

Methods

For the GABA measurement a single voxel MR spectrum was assessed in the prefrontal lobe (25 × 40 × 30 mm) using the MEGA-PRESS method in 276 subjects. BDNF serum concentrations were assessed with an ELISA kit. For 147 subjects we had both MRS and BDNF serum data, and for 79 subjects we had genotype data on the BDNF rs6265 polymorphism. Depressive psychopathology was assessed using Beck's Depression Inventory (BDI), Montgomery-Asberg Depression Rating Scale (MADRS) and Structured Clinical Interviews for Diagnostic and Statistical Manual of Mental Disorders (SCID) for DSM-IV.

Results

GABA concentration in the left DLPFC was negatively associated with BDNF serum concentration (r = -.264, p = .001). This correlation remained significant if corrected for sex (r = -.264, p = .001). BDNF serum concentration was also positively associated with volumes and surface areas of the left prefrontal cortex (p = .048, p = .005). There were no significant associations or interaction with depressive psychopathology (BDI, MADRS, SCID) or rs6265.

Conclusion

The results of this study suggest that GABA, BDNF and prefrontal brain volumes are interrelated, but do not show a strong association to depressive psychopathology, possibly due to the mild forms of psychiatric conditions present in our community-based sample.

Early Detection of Pancreatic Intraepithelial Neoplasias (PanINs) in Transgenic Mouse Model by Hyperpolarized 13C Metabolic Magnetic Resonance Spectroscopy

While pancreatic cancer (PC) survival rates have recently shown modest improvement, the disease remains largely incurable. Early detection of pancreatic cancer may result in improved outcomes and therefore, methods for early detection of cancer, even premalignant lesions, may provide more favorable outcomes. Pancreatic intraepithelial neoplasias (PanINs) have been identified as premalignant precursor lesions to pancreatic cancer. However, conventional imaging methods used for screening high-risk populations do not have the sensitivity to detect PanINs. Here, we have employed hyperpolarized metabolic imaging in vivo and nuclear magnetic resonance (¹H-NMR) metabolomics ex vivo to identify and understand metabolic changes, towards enabling detection of early PanINs and progression to advanced PanINs lesions that precede pancreatic cancer formation. Progression of disease from tissue containing predominantly low-grade PanINs to tissue with high-grade PanINs showed a decreasing alanine/lactate ratio from high-resolution NMR metabolomics ex vivo. Hyperpolarized magnetic resonance spectroscopy (HP-MRS) allows over 10,000-fold sensitivity enhancement relative to conventional magnetic resonance. Real-time HP-MRS was employed to measure non-invasively changes of alanine and lactate metabolites with disease progression and in control mice in vivo, following injection of hyperpolarized [1-¹³C] pyruvate. The alanine-to-lactate signal intensity ratio was found to decrease as the disease progressed from low-grade PanINs to high-grade PanINs. The biochemical changes of alanine transaminase (ALT) and lactate dehydrogenase (LDH) enzyme activity were assessed. These results demonstrate that there are significant alterations of ALT and LDH activities during the transformation from early to advanced PanINs lesions. Furthermore, we demonstrate that real-time conversion kinetic rate constants (k_PA and k_PL) can be used as metabolic imaging biomarkers of pancreatic premalignant lesions. Findings from this emerging HP-MRS technique can be translated to the clinic for detection of pancreatic premalignant lesion in high-risk populations.

MRS Shows Regionally Increased Glutamate Levels among Patients with Exhaustion Syndrome Due to Occupational Stress

Despite the rapid increase of reports of exhaustion syndrome (ES) due to daily occupational stress, the mechanisms underlying ES are unknown. We used voxel-based 1H-MR spectroscopy to examine the potential role of glutamate in this condition. The levels of glutamate were found to be elevated among ES patients (n = 30, 16 females) compared with controls (n = 31, 15 females). Notably, this increase was detected only in the anterior cingulate and mesial prefrontal cortex (ACC/mPFC), and the glutamate levels were linearly correlated with the degree of perceived stress. Furthermore, there was a sex by group interaction, as the glutamate elevation was present only in female patients. Female but not male ES patients also showed an increase in N-acetyl aspartate (NAA) levels in the amygdala. No group differences were detected in glutamine concentration (also measured). These data show the key role of glutamate in stress-related neuronal signaling and the specific roles of the amygdala and ACC/mPFC. The data extend previous reports about the neurochemical basis of stress and identify a potential neural marker and mediator of ES due to occupational stress. The observation of specific sex differences provides a tentative explanation to the well-known female predominance in stress-related psychopathology.

Predictors of clinical outcome among Thai patients with atrial fibrillation-associated acute ischemic stroke

OBJECTIVE

To investigate the predictors of 3-month death among an atrial fibrillation-associated acute ischemic stroke (AF-stroke).

METHODS

This retrospective cohort study was conducted at a university hospital in Thailand. Patients with AF-stroke admitted between 2012 and 2017 were enrolled into the study. Baseline characteristics, clinical presentations, complications, and outcomes measured by the modified Rankin scale were collected from electronic medical records. Predictors of death outcomes were analyzed by univariate and multivariate logistic regression analysis.

RESULTS

The mortality rate among 119 AF-stroke patients was 26.89%. The independent predictors of 3-month death were developing AKI during hospitalization (adjusted odds ratio [aOR] = 6.38, 95% CI = 1.96-20.76, p = 0.001) and age above 75 years old (aOR = 3.08, 95% CI = 1.17-8.13, p = 0.019). In contrast, receiving treatment with an oral anticoagulant prior to the stroke episode was a protective factor (aOR = 0.13, 95% CI = 0.03-0.64, p = 0.002).

CONCLUSION

Developing AKI and older age were the independent predictor of 3- month death among AF-stroke patients.

A multisample 7 T dynamic nuclear polarization polarizer for preclinical hyperpolarized MR

Dynamic nuclear polarization (DNP) provides the opportunity to boost liquid state magnetic resonance (MR) signals from selected nuclear spins by several orders of magnitude. A cryostat running at a temperature of ~ 1 K and a superconducting magnet set to between 3 and 10 T are required to efficiently hyperpolarize nuclear spins. Several DNP polarizers have been implemented for the purpose of hyperpolarized MR and recent systems have been designed to avoid the need for user input of liquid cryogens. We herein present a zero boil-off DNP polarizer that operates at 1.35 ± 0.01 K and 7 T, and which can polarize two samples in parallel. The samples are cooled by a static helium bath thermally connected to a 1 K closed-cycle ⁴ He refrigerator. Using a modified version of the commercial fluid path developed for the SPINlab polarizer, we demonstrate that, within a 12-minute interval, the system can produce two separate hyperpolarized ¹³ C solutions. The ¹³ C liquid-state polarization of [1-¹³ C]pyruvate measured 26 seconds after dissolution was 36%, which can be extrapolated to a 55% solid state polarization. The system is well adapted for in vitro and in vivo preclinical hyperpolarized MR experiments and it can be modified to polarize up to four samples in parallel.

Progression of Alzheimer's disease and effect of scFv-h3D6 immunotherapy in the 3xTg-AD mouse model: An in vivo longitudinal study using Magnetic Resonance Imaging and Spectroscopy

Alzheimer's disease (AD) is an incurable disease that affects most of the 47 million people estimated as living with dementia worldwide. The main histopathological hallmarks of AD are extracellular β-amyloid (Aβ) plaques and intracellular neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau protein. In recent years, Aβ-immunotherapy has been revealed as a potential tool in AD treatment. One strategy consists of using single-chain variable fragments (scFvs), which avoids the fragment crystallizable (Fc) effects that are supposed to trigger a microglial response, leading to microhemorrhages and vasogenic edemas, as evidenced in clinical trials with bapineuzumab. The scFv-h3D6 generated by our research group derives from this monoclonal antibody, which targets the N-terminal of the Aβ peptide and recognizes monomers, oligomers and fibrils. In this study, 3xTg-AD mice were intraperitoneally and monthly treated with 100 μg of scFv-h3D6 (a dose of ~3.3 mg/kg) or PBS, from 5 to 12 months of age (-mo), the age at which the mice were sacrificed and samples collected for histological and biochemical analyses. During treatments, four monitoring sessions using magnetic resonance imaging and spectroscopy (MRI/MRS) were performed at 5, 7, 9, and 12 months of age. MRI/MRS techniques are widely used in both human and mouse research, allowing to draw an in vivo picture of concrete aspects of the pathology in a non-invasive manner and allowing to monitor its development across time. Compared with the genetic background, 3xTg-AD mice presented a smaller volume in almost all cerebral regions and ages examined, an increase in both the intra and extracellular Aβ_1-42 at 12-mo, and an inflammation process at this age, in both the hippocampus (IL-6 and mIns) and cortex (IL-6). In addition, treatment with scFv-h3D6 partially recovered the values in brain volume, and Aβ, IL-6, and mIns concentrations, among others, encouraging further studies with this antibody fragment.

Insular Cell Integrity Markers Linked to Weight Concern in Anorexia Nervosa-An MR-Spectroscopy Study

Objective: An insular involvement in the pathogenesis of anorexia nervosa (AN) has been suggested in many structural and functional neuroimaging studies. This magnetic resonance spectroscopy (MRS) study is the first to investigate metabolic signals in the anterior insular cortex in patients with AN and recovered individuals (REC). Method: The MR spectra of 32 adult women with AN, 21 REC subjects and 33 healthy controls (HC) were quantified for absolute N-acetylaspartate (NAA), glutamate + glutamine (Glx), total choline, myo-inositol, creatine concentrations (mM/L). After adjusting the metabolite concentrations for age and partial gray/white matter volume, group differences were tested using one-way multivariate analyses of variance (MANOVA). Post-hoc analyses of variance were applied to identify those metabolites that showed significant group effects. Correlations were tested for associations with psychometric measures (eating disorder examination), duration of illness, and body mass index. Results: The MANOVA exhibited a significant group effect. The NAA signal was reduced in the AN group compared to the HC group. The REC and the HC groups did not differ in metabolite concentrations. In the AN group, lower NAA and Glx signals were related to increased weight concern. Discussion: We interpret the decreased NAA availability in the anterior insula as a signal of impaired neuronal integrity or density. The association of weight concern, which is a core feature of AN, with decreased NAA and Glx indicates that disturbances of glutamatergic neurotransmission might be related to core psychopathology in AN. The absence of significant metabolic differences between the REC and HC subjects suggests that metabolic alterations in AN represent a state rather than a trait phenomenon.

Loss of PYCR2 Causes Neurodegeneration by Increasing Cerebral Glycine Levels via SHMT2

Patients lacking PYCR2, a mitochondrial enzyme that synthesizes proline, display postnatal degenerative microcephaly with hypomyelination. Here we report the crystal structure of the PYCR2 apo-enzyme and show that a novel germline p.Gly249Val mutation lies at the dimer interface and lowers its enzymatic activity. We find that knocking out Pycr2 in mice phenocopies the human disorder and depletes PYCR1 levels in neural lineages. In situ quantification of neurotransmitters in the brains of PYCR2 mutant mice and patients revealed a signature of encephalopathy driven by excessive cerebral glycine. Mechanistically, we demonstrate that loss of PYCR2 upregulates SHMT2, which is responsible for glycine synthesis. This hyperglycemia could be partially reversed by SHMT2 knockdown, which rescued the axonal beading and neurite lengths of cultured Pycr2 knockout neurons. Our findings identify the glycine metabolic pathway as a possible intervention point to alleviate the neurological symptoms of PYCR2-mutant patients.

Advanced Imaging of Brain Metastases: From Augmenting Visualization and Improving Diagnosis to Evaluating Treatment Response

Early detection of brain metastases and differentiation from other neuropathologies is crucial. Although biopsy is often required for definitive diagnosis, imaging can provide useful information. After treatment commences, imaging is also performed to assess the efficacy of treatment. Contrast-enhanced magnetic resonance imaging (MRI) is the traditional imaging method for the evaluation of brain metastases, as it provides information about lesion size, morphology, and macroscopic properties. Newer MRI sequences have been developed to increase the conspicuity of detecting enhancing metastases. Other advanced MRI techniques, that have the capability to probe beyond the anatomic structure, are available to characterize micro-structures, cellularity, physiology, perfusion, and metabolism. Artificial intelligence provides powerful computational tools for detection, segmentation, classification, prediction, and prognosis. We highlight and review a few advanced MRI techniques for the assessment of brain metastases-specifically for (1) diagnosis, including differentiating between malignancy types and (2) evaluation of treatment response, including the differentiation between radiation necrosis and disease progression.

Reduced anterior cingulate glutamate of comorbid skin-picking disorder in adults with obsessive-compulsive disorder

BACKGROUND

Obsessive Compulsive Disorder (OCD) is characterized by hyperactivity in a network of forebrain structures, including the anterior cingulate cortex (ACC). Convergent evidence suggests that glutamatergic dysfunction may contribute to the disorder. Skin picking disorder (SPD) was listed as one of the obsessive-compulsive and related disorders, which is often comorbid with OCD and share overlapping phenomenology and pathophysiology. However, potential confounding effects between the two diagnostic effects on neurotransmitter levels remain largely unexamined.

METHODS

We examined the pregenual anterior cingulate cortex (pACC) glutamate and other neurochemicals in 62 subjects using a single-voxel acquisition 1H MRS at 3Tesla; of these, 47 subjects yielded usable measurements of both glutamate and glutamine and were included in the analysis (17 medicated with OCD alone, 13 medicated with comorbid OCD + SPD, 17 healthy control).

RESULTS

OCD with comorbid SPD showed significantly lower pACC glutamate than in patients without SPD (p = 0.001) or control subjects (p = 0.035). OCD without SPD subjects showed pACC glutamate levels indistinguishable from controls (p = 0.501). In the OCD with SPD subjects, glutamate was correlated with Y-BOCS total score in female patients (n = 9, r = 0.69, p = 0.041).

LIMITATIONS

The main limitation of the study was the cross-sectional data. Our patients were on SSRI medication which may have modified the effect of SPD and OCD interaction on glutamate activity.

CONCLUSION

Our results suggest that alterations of the glutamatergic system may play an important role in the pathophysiology of a subgroup of OCD and reduced pACC glutamate may be a biomarker of a distinct subset of OCD patients.

Exploring Changes in Thalamus Metabolites as Diagnostic Biomarkers in Idiopathic Generalised Epilepsy Patients Using Magnetic Resonance Spectroscopy

Introduction

Idiopathic generalised epilepsy (IGE) refers to a group of epilepsies resulting from the activation of neurons in the whole brain. This study aimed to evaluate the metabolite changes in thalamus as diagnostic biomarkers in IGE patients compared to healthy individuals using magnetic resonance spectroscopy (MRS) technique.

Methods

The MRS was performed on 35 IGE patients (26 women and 11 men) with average age of 32 (ranged from 18 to 43) and 35 healthy individuals (13 women and 22 men) with average age of 31 (ranged from 21 to 50) as the control group. The levels of N-acetylaspartate (NAA), creatine (Cr) and choline (Cho) were measured using MRS. The NAA/Cr and NAA/Cho ratios were calculated for all participants. These values were statistically compared using t-test between the groups.

Results

The NAA had significant lower values in IGE patients, 9.6 (SD = 0.8) and 9.9 (SD = 0.7) for right and left thalamus, respectively, compared to 10.9 (SD = 0.9) and 10.7 (SD = 0.9) in control group. The Cr values in the left side of thalamus were significantly higher in IGE patients (6.7 [SD = 0.8] versus 5.8 [SD = 0.5]); however, there was no difference in right thalamus. Measurements showed no difference for amounts of Cho between the groups in both sides of thalamus. The NAA/Cr ratio was 1.48 (SD = 0.14) and 1.48 (SD = 0.16) for right and left thalamus, respectively, in IGE patients in comparison with 1.83 (SD = 0.2) and 1.86 (SD = 0.26) in controls. There was no meaningful variation between the NAA/Cho ratio of the right and left thalamus among the groups.

Conclusion

Thalamic NAA, Cr and NAA/Cr ratio values in IGE patients showed statistical differences compared to healthy individuals. Evaluating metabolites variations in thalamus using MRS is suggested for differentiating IGE patients from healthy individuals.

In vivo MRS measurement of 2-hydroxyglutarate in patient-derived IDH-mutant xenograft mouse models versus glioma patients

PURPOSE

To generate a preclinical model of isocitrate dehydrogenase (IDH) mutant gliomas from glioma patients and design a MRS method to test the compatibility of 2-hydroxyglutarate (2HG) production between the preclinical model and patients.

METHODS

Five patient-derived xenograft (PDX) mice were generated from two glioma patients with IDH1 R132H mutation. A PRESS sequence was tailored at 9.4 T, with computer simulation and phantom analyses, for improving 2HG detection in mice. 2HG and other metabolites in the PDX mice were measured using the optimized MRS at 9.4 T and compared with 3 T MRS measurements of the metabolites in the parental-tumor patients. Spectral fitting was performed with LCModel using in-house basis spectra. Metabolite levels were quantified with reference to water.

RESULTS

The PRESS TE was optimized to be 96 ms, at which the 2HG 2.25 ppm signal was narrow and inverted, thereby leading to unequivocal separation of the 2HG resonance from adjacent signals from other metabolites. The optimized MRS provided precise detection of 2HG in mice compared to short-TE MRS at 9.4 T. The 2HG estimates in PDX mice were in excellent agreement with the 2HG measurements in the patients.

CONCLUSION

The similarity of 2HG production between PDX models and parental-tumor patients indicates that PDX tumors retain the parental IDH metabolic fingerprint and can serve as a preclinical model for improving our understanding of the IDH-mutation associated metabolic reprogramming.

Alcohol consumption is associated with reduced creatine levels in the hippocampus of older adults

Besides its well established susceptibility to ageing, the hippocampus has also been shown to be affected by alcohol consumption. Proton spectroscopy (¹H-MRS) of the hippocampus, particularly at high-field 7T MRI, may further our understanding of these associations. Here, we aimed to examine how hippocampal metabolites varied with age and alcohol consumption. Hippocampal metabolite spectra were acquired in 37 older adults using 7T ¹H-MRS, from which we determined the absolute concentration of N-acetylaspartate (NAA), creatine, choline, myo-inositol, glutamate and glutamine. Thirty participants (mean age = 70.4 ± 4.7 years) also had self-reported data on weekly alcohol consumption. Total choline inversely correlated with age, although this did not survive multiple comparisons correction. Crucially, adults with a higher weekly alcohol consumption had significantly lower levels of creatine, suggesting a deficit in their hippocampal metabolism. These findings add to an increasing body of evidence linking alcohol to hippocampal function.

Thalamic Gamma Aminobutyric Acid Level Changes in Major Depressive Disorder After a 12-Week Iyengar Yoga and Coherent Breathing Intervention

Objective: To determine if a 12-week yoga intervention (YI) was associated with increased gamma aminobutyric acid (GABA) levels and decreased depressive symptoms in participants with major depressive disorder (MDD). Methods: Subjects were randomized to a high-dose group (HDG) of three YIs a week and a low-dose group (LDG) of two YIs a week. Thalamic GABA levels were obtained using magnetic resonance spectroscopy at Scan-1 before randomization. After the assigned 12-week intervention, Scan-2 was obtained, immediately followed by a YI and Scan-3. Beck Depression Inventory II (BDI-II) scores were obtained before Scan-1 and Scan-3. Settings/Location: Screenings and interventions occurred at the Boston University Medical Center. Imaging occurred at McLean Hospital. Subjects: Subjects met criteria for MDD. Intervention: Ninety minutes of Iyengar yoga and coherent breathing at five breaths per minute plus homework. Outcome measures: GABA levels and the BDI-II. Results: BDI-II scores improved significantly in both groups. GABA levels from Scan-1 to Scan-3 and from Scan-2 to Scan-3 were significantly increased in the LDG (n = 15) and showed a trend in the total cohort. Post hoc, participants were divided into two groups based on having an increase in GABA levels at Scan-2. Increases in Scan-2 GABA levels were observed in participants whose mean time between their last YI and Scan-2 was 3.93 ± 2.92 standard deviation (SD) days, but not in those whose mean time between their last YI and Scan-2 was 7.83 ± 6.88 SD. Conclusions: This study tentatively supports the hypothesis that one of the mechanisms through which yoga improves mood is by increasing the activity of the GABA system. The observed increase in GABA levels following a YI that was no longer observed 8 days after a YI suggests that the associated increase in GABA after a YI is time limited such that at least one YI a week may be necessary to maintain the elevated GABA levels.

Exploration of New Contrasts, Targets, and MR Imaging and Spectroscopy Techniques for Neuromuscular Disease - A Workshop Report of Working Group 3 of the Biomedicine and Molecular Biosciences COST Action BM1304 MYO-MRI

Neuromuscular diseases are characterized by progressive muscle degeneration and muscle weakness resulting in functional disabilities. While each of these diseases is individually rare, they are common as a group, and a large majority lacks effective treatment with fully market approved drugs. Magnetic resonance imaging and spectroscopy techniques (MRI and MRS) are showing increasing promise as an outcome measure in clinical trials for these diseases. In 2013, the European Union funded the COST (co-operation in science and technology) action BM1304 called MYO-MRI (www.myo-mri.eu), with the overall aim to advance novel MRI and MRS techniques for both diagnosis and quantitative monitoring of neuromuscular diseases through sharing of expertise and data, joint development of protocols, opportunities for young researchers and creation of an online atlas of muscle MRI and MRS. In this report, the topics that were discussed in the framework of working group 3, which had the objective to: Explore new contrasts, new targets and new imaging techniques for NMD are described. The report is written by the scientists who attended the meetings and presented their data. An overview is given on the different contrasts that MRI can generate and their application, clinical needs and desired readouts, and emerging methods.