Glial Activity Load on PET Reveals Persistent "Smoldering" Inflammation in MS Despite Disease-Modifying Treatment: 18 F-PBR06 Study

PURPOSE OF THE REPORT

18 F-PBR06-PET targeting 18-kDa translocator protein can detect abnormal microglial activation (MA) in multiple sclerosis (MS). The objectives of this study are to develop individualized mapping of MA using 18 F-PBR06, to determine the effect of disease-modifying treatment (DMT) efficacy on reducing MA, and to determine its clinical, radiological, and serological correlates in MS patients.

PATIENTS AND METHODS

Thirty 18 F-PBR06-PET scans were performed in 22 MS patients (mean age, 46 ± 13 years; 16 females) and 8 healthy controls (HCs). Logarithmically transformed "glial activity load on PET" scores (calculated as the sum of voxel-by-voxel z -scores ≥4), "lnGALP," were compared between MS and HC and between MS subjects on high-efficacy DMTs (H-DMT, n = 13) and those on no or lower-efficacy treatment, and correlated with clinical measures, serum biomarkers, and cortical thickness.

RESULTS

Cortical gray matter (CoGM) and white matter (WM) lnGALP scores were higher in MS versus HC (+33% and +48%, P < 0.001). In H-DMT group, CoGM and WM lnGALP scores were significantly lower than lower-efficacy treatment ( P < 0.01) but remained abnormally higher than in HC group ( P = 0.006). Within H-DMT patients, CoGM lnGALP scores correlated positively with physical disability, fatigue and serum glial fibrillary acid protein levels ( r = 0.65-0.79, all P 's < 0.05), and inversely with cortical thickness ( r = -0.66, P < 0.05).

CONCLUSIONS

High-efficacy DMTs decrease, but do not normalize, CoGM and WM MA in MS patients. Such "residual" MA in CoGM is associated with clinical disability, serum biomarkers, and cortical degeneration. Individualized mapping of translocator protein PET using 18 F-PBR06 is clinically feasible and can potentially serve as an imaging biomarker for evaluating "smoldering" inflammation in MS patients.

Clinical Trial-Ready Patient Cohorts for Multiple System Atrophy: Coupling Biospecimen and iPSC Banking to Longitudinal Deep-Phenotyping

Multiple system atrophy (MSA) is a fatal neurodegenerative disease of unknown etiology characterized by widespread aggregation of the protein alpha-synuclein in neurons and glia. Its orphan status, biological relationship to Parkinson's disease (PD), and rapid progression have sparked interest in drug development. One significant obstacle to therapeutics is disease heterogeneity. Here, we share our process of developing a clinical trial-ready cohort of MSA patients (69 patients in 2 years) within an outpatient clinical setting, and recruiting 20 of these patients into a longitudinal "n-of-few" clinical trial paradigm. First, we deeply phenotype our patients with clinical scales (UMSARS, BARS, MoCA, NMSS, and UPSIT) and tests designed to establish early differential diagnosis (including volumetric MRI, FDG-PET, MIBG scan, polysomnography, genetic testing, autonomic function tests, skin biopsy) or disease activity (PBR06-TSPO). Second, we longitudinally collect biospecimens (blood, CSF, stool) and clinical, biometric, and imaging data to generate antecedent disease-progression scores. Third, in our Mass General Brigham SCiN study (stem cells in neurodegeneration), we generate induced pluripotent stem cell (iPSC) models from our patients, matched to biospecimens, including postmortem brain. We present 38 iPSC lines derived from MSA patients and relevant disease controls (spinocerebellar ataxia and PD, including alpha-synuclein triplication cases), 22 matched to whole-genome sequenced postmortem brain. iPSC models may facilitate matching patients to appropriate therapies, particularly in heterogeneous diseases for which patient-specific biology may elude animal models. We anticipate that deeply phenotyped and genotyped patient cohorts matched to cellular models will increase the likelihood of success in clinical trials for MSA.

Adenosine A2A receptor availability in cerebral gray and white matter of patients with Parkinson's disease

OBJECTIVE

Atrophic changes in cerebral gray matter of patients with PD have been reported extensively. There is evidence suggesting an association between cortical gyrification changes and white matter abnormalities. Adenosine A2A receptors have been shown to be upregulated in cerebral white matter and on reactive astrocytes in preclinical models of neurodegenerative diseases. We, therefore, sought to investigate in vivo changes in A2A receptor availability in cerebral gray and white matter of PD patients and its association with gray matter atrophy.

METHODS

Eighteen patients with PD without dyskinesia and seven healthy controls were enrolled for this study. Brain MRI and dynamic PET scan was acquired with [11C]TMSX radioligand which binds selectively to A2A receptors. FreeSurfer software was used to segment cerebral gray and white matter structures. The resulting masks were used to calculate region specific volumes and to derive distribution volume ratios (DVRs), after co-registration with PET images, for the quantification of specific [11C]TMSX binding.

RESULTS

We showed an increase in A2A receptor availability in frontal (P < 0.001) and parietal (P < 0.001) white matter and a decrease in occipital (P = 0.02) gray matter of PD patients as compared to healthy controls. A decrease in gray matter volume ratios was observed in frontal (P < 0.01), parietal (P < 0.001), temporal (P < 0.01) and occipital (P < 0.01) ROIs in patients with PD versus healthy controls.

CONCLUSIONS

Our results suggest a role of A2A receptor-based signaling in the neurodegenerative changes seen in the cerebral gray and white matter of patients with PD.

Assessment of Microglial Activation in Alzheimer Disease Using 18 F-PBR06 PET

ABSTRACT

A 69-year-old woman with progressive short-term memory deficits was diagnosed with Alzheimer disease (MMSE 26/30, CDR 0.5) and underwent PET using 18 F-PBR06, a second-generation 18-kDa translocator protein ligand, targeting brain microglia and astrocytes. SUV and voxel-by-voxel binding potential maps (using simplified reference tissue method and a cerebellar pseudo-reference region) were generated. Images showed evidence of increased glial activation in biparietal cortices (including bilateral precuneus and posterior cingulate gyri) and bilateral frontal cortices. After 6 years of clinical follow-up, patient progressed to moderate cognitive impairment (CDR 2.0) and required assistance for activities of daily living.

Adenosine A2A receptor availability in patients with early- and moderate-stage Parkinson's disease

INTRODUCTION

Adenosine 2A (A_2A) receptors co-localize with dopamine D₂ receptors in striatopallidal medium spiny neurons of the indirect pathway. A_2A receptor activation in the striatum or pallidum decreases D₂ signaling. In contrast, A_2A receptor antagonism may help potentiate it. Furthermore, previous PET studies have shown increased A_2A receptor availability in striatum of late-stage PD patients with dyskinesia. However, human in vivo evidence for striatal A_2A receptor availability in early-stage PD is limited. This study aimed to investigate possible differences in A_2A receptor availability in the striatum and pallidum of early- and moderate-stage PD patients without dyskinesias.

METHODS

Brain MRI and PET with [¹¹C]TMSX radioligand, targeting A_2A receptors, was performed in 9 patients with early- and 9 with moderate-stage PD without dyskinesia and in 6 healthy controls. Distribution volume ratios (DVR) were calculated to assess specific [¹¹C]TMSX binding in caudate, putamen and pallidum.

RESULTS

A_2A receptor availability (DVR) was decreased in the bilateral caudate of early-stage PD patients when compared with healthy controls (P = 0.02). Conversely, DVR was increased bilaterally in the pallidum of moderate-stage PD patients compared to healthy controls (P = 0.03). Increased mean striatal DVR correlated with higher motor symptom severity ([Formula: see text] = 0.47, P = 0.02).

CONCLUSION

Our results imply regional and disease stage-dependent changes in A_2A receptor signaling in PD pathophysiology and in response to dopaminergic medication.

Innate Immune Cell–Related Pathology in the Thalamus Signals a Risk for Disability Progression in Multiple Sclerosis

Background and Objectives

Our aim was to investigate whether 18-kDa translocator protein (TSPO) radioligand binding in gray matter (GM) predicts later disability progression in multiple sclerosis (MS).

Methods

In this prospective imaging study, innate immune cells were investigated in the MS patient brain using PET imaging. The distribution volume ratio (DVR) of the TSPO-binding radioligand [¹¹C]PK11195 was determined in 5 GM regions: thalamus, caudate, putamen, pallidum, and cortical GM. Volumetric brain MRI parameters were obtained for comparison. The Expanded Disability Status Scale (EDSS) score was assessed at baseline and after follow-up of 3.0 ± 0.3 (mean ± SD) years. Disability progression was defined as an EDSS score increase of 1.0 point or 0.5 point if the baseline EDSS score was ≥6.0. A forward-type stepwise logistic regression model was constructed to compare multiple imaging and clinical variables in their ability to predict later disability progression.

Results

The cohort consisted of 66 patients with MS and 18 healthy controls. Patients with later disability progression (n = 17) had more advanced atrophy in the thalamus, caudate, and putamen at baseline compared with patients with no subsequent worsening. TSPO binding was significantly higher in the thalamus among the patients with later worsening. The thalamic DVR was the only measured imaging variable that remained a significant predictor of disability progression in the regression model. The final model predicted disability progression with 52.9% sensitivity and 93.9% specificity with an area under the curve value of 0.82 (receiver operating characteristic curve).

Discussion

Increased TSPO radioligand binding in the thalamus has potential in predicting short-term disability progression in MS and seems to be more sensitive for this than GM atrophy measures.

Economic evidence of preventive interventions for anxiety disorders in children and adolescents – a systematic review

Introduction

Anxiety disorders are common in children and youth. Also, in prevention, be it universal, selective or indicated, economic evaluation supports decision-making in the allocation of scarce resources.

Objectives

This review identified and summarised the existing evidence of economic evaluations for the prevention of anxiety disorders in children and adolescents.

Methods

A systematic search was conducted on the EBSCO, Scopus, Web of Science, ProQuest, Cochrane and PubMed databases. We included studies that focused on children and adolescents under 18 years of age, aimed to prevent anxiety disorders, and presented an incremental analysis of costs and effectiveness. A registered checklist was used that assessed the quality of the included articles.

Results

The search yielded 1,697 articles. Five articles were included in this review. Three were RCT-based and two were model-based studies. Out of five included interventions, one was a universal school-based intervention, two selective interventions and two indicated interventions. Universal school-based prevention of anxiety was not cost-effective compared to usual teaching. Selective parent training and indicative child- and parent-focused CBT prevention were likely cost-effective compared to usual care or doing nothing.

Conclusions

Parent education and cognitive behaviour therapy interventions can be cautiously interpreted as being a cost-effective way of preventing anxiety in children and adolescents. However, the evidence is weak related to cost-effectiveness as there are only a few studies, with relatively small sample sizes and short follow-ups.

Disclosure

No significant relationships.

Circulating neurofilament is linked with morbid obesity, renal function, and brain density

Neurofilament light chain (NfL) is a novel biomarker reflecting neuroaxonal damage and associates with brain atrophy, and glial fibrillary acidic protein (GFAP) is a marker of astrocytic activation, associated with several neurodegenerative diseases. Since obesity is associated with increased risk for several neurodegenerative disorders, we hypothesized that circulating NfL and GFAP levels could reflect neuronal damage in obese patients. 28 morbidly obese and 18 lean subjects were studied with voxel based morphometry (VBM) MRI to assess gray and white matter densities. Serum NfL and GFAP levels were determined with single-molecule array. Obese subjects were re-studied 6 months after bariatric surgery. Morbidly obese subjects had lower absolute concentrations of circulating NfL and GFAP compared to lean individuals. Following bariatric surgery-induced weight loss, both these levels increased. Both at baseline and after weight loss, circulating NfL and GFAP values correlated inversely with eGFR. Cross-sectionally, circulating NfL levels correlated inversely with gray matter (GM) density, and this association remained significant also when accounting for age and total eGFR. GFAP values did not correlate with GM density. Our data suggest that when determining circulating NfL and GFAP levels, eGFR should also be measured since renal function can affect these measurements. Despite the potential confounding effect of renal function on NfL measurement, NfL correlated inversely with gray matter density in this group of subjects with no identified neurological disorders, suggesting that circulating NfL level may be a feasible biomarker of cerebral function even in apparently neurologically healthy subjects.

Cortical and Subcortical Dysmetabolism Are Dynamic Markers of Clinical Disability and Course in Anti-LGI1 Encephalitis

Background and Objectives

This [¹⁸F]fluorodeoxyglucose (FDG) PET study evaluates the accuracy of semiquantitative measurement of putaminal hypermetabolism in identifying anti–leucine-rich, glioma–inactivated-1 (LGI1) protein autoimmune encephalitis (AE). In addition, the extent of brain dysmetabolism, their association with clinical outcomes, and longitudinal metabolic changes after immunotherapy in LGI1-AE are examined.

Methods

FDG-PET scans from 49 age-matched and sex-matched subjects (13 in LGI1-AE group, 15 in non–LGI1-AE group, 11 with Alzheimer disease [AD], and 10 negative controls [NCs]) and follow-up scans from 8 patients with LGI1 AE on a median 6 months after immunotherapy were analyzed. Putaminal standardized uptake value ratios (SUVRs) normalized to global brain (P-SUVRg), thalamus (P/Th), and midbrain (P/Mi) were evaluated for diagnostic accuracy. SUVRg was applied for all other analyses.

Results

P-SUVRg, P/Th, and P/Mi were higher in LGI1-AE group than in non–LGI1-AE group, AD group, and NCs (all p < 0.05). P/Mi and P-SUVRg differentiated LGI1-AE group robustly from other groups (areas under the curve 0.84–0.99). Mediotemporal lobe (MTL) SUVRg was increased in both LGI1-AE and non–LGI1-AE groups when compared with NCs (both p < 0.05). SUVRg was decreased in several frontoparietal regions and increased in pallidum, caudate, pons, olfactory, and inferior occipital gyrus in LGI1-AE group when compared with that in NCs (all p < 0.05). In LGI1-AE group, both MTL and putaminal hypermetabolism were reduced after immunotherapy. Normalization of regional cortical dysmetabolism associated with clinical improvement at the 6- and 20-month follow-up.

Discussion

Semiquantitative measurement of putaminal hypermetabolism with FDG-PET may be used to distinguish LGI1-AE from other pathologies. Metabolic abnormalities in LGI1-AE extend beyond putamen and MTL into other subcortical and cortical regions. FDG-PET may be used in evaluating disease evolution in LGI1-AE.

Classification of Evidence

This study provides Class II evidence that semiquantitative measures of putaminal metabolism on PET can differentiate patients with LGI1-AE from patients without LGI1-AE, patients with AD, or NCs.

Differences in brain changes between adults with childhood-onset epilepsy and controls: A prospective population-based study

Purpose

To determine the impact of childhood‐onset uncomplicated epilepsy (COE) on brain aging over 50‐year prospective follow‐up.

Methods

A population‐based cohort of 41 aging subjects with COE and their 46 matched controls participated in a detailed in‐person prospective assessment in 2012 and 2017 to characterize ongoing changes in the aging brain.

Results

The mean age of the COE participants was 63.2 years (SD 4.14, median 63.2, range 55.8–70.6) and 63.0 years (mean, SD 4.13, median 63.3, range 56.0–69.9) years for controls. Neurologic signs were significantly more common in COE participants not in remission (p = .015), and the most frequent abnormalities were cerebellar signs (p < .001). Neurologic signs in general (p = .008) and cerebellar signs in particular (p = .018) were significantly more common in focal than in generalized epilepsies. MRI white matter abnormalities were significantly associated with absence of vocational education (p = .011), and MRI hippocampal atrophy in COE subjects was associated with arterial hypertension versus normal blood pressure (p = .017). In the combined study cohort of COE subjects and controls, presenting neurologic signs increased both in the subjects and in the controls from the 2012 to 2017 study.

Conclusions

At ultra‐long‐term follow‐up, clinical and neuroimaging findings show tendencies to brain aging that is more accelerated in COE participants with active adult childhood‐onset epilepsy, and particularly in focal epilepsy.

O-076 Neurodevelopmental morbidity in children born after ART: a Nordic register study from the Committee of Nordic ART and Safety (CoNARTaS) group

Study question

Does the risk of neurodevelopmental disorders differ between singletons born after various assisted reproductive techniques (ART) and spontaneous conception (SC) until young adulthood?

Summary answer

ART children had a slightly increased rate of learning and motor functioning disorders, autism spectrum disorders (ASD), and ADHD and conduct disorders.

What is known already

Studies on the impact of ART on offspring have reported both increased risk and comparable incidences of neurodevelopmental disorders between ART and SC offspring. The most studied neurodevelopmental disorders with ART are autism spectrum disorders (ASD.) There is, however, no consensus on the risk of ASD for ART children. The risk for other neurodevelopmental disorders, like attention-deficit hyperactivity disorders (ADHD) or tic disorder among ART children, is also a debated issue, as studies are scarce.

Study design, size, duration

A Nordic register-based cohort study including all singleton live births (N = 5 076 444) after ART (n = 116 909) or SC (n = 4 959 535) between 1995 and 2014 in Denmark and Finland, 1995 and 2015 in Sweden; and 2005 and 2015 in Norway. Children with intellectual disability (ICD-10: F70-F79) are excluded. The children are followed up to young adulthood (the year 2014 in Denmark and Finland, and 2015 in Norway and Sweden).

Participants/materials, setting, methods

Offspring outcomes were defined as following ICD-10 diagnoses: learning and motor functioning disorders (F80-83), ASD (F84), ADHD and conduct disorders (F90-F92), and tic disorders/Tourette (F95). We calculated crude and adjusted hazard ratios (HR) for neurodevelopmental diagnoses using Cox regression. Adjustments were made for the country, maternal age at the delivery, parity, smoking, and maternal psychiatric morbidity.

Main results and the role of chance

The cumulative incidences of neurodevelopmental disorders in the cohort were 1.74% for F90-F92, 1.40% for F80-83, 0.66% for F84, and 0.22% for F95. In crude Cox-regression ART children had an increased likelihood during the follow-up of being diagnosed with F84 (HR 1.12 [95% CI 1.04-1.21]) and F95 (HR 1.21 [95% CI 1.06-1.38]), but not with F80-83 (HR 1.01 [95% CI 0.96-1.07]) or F90-92 (HR 0.82 [95% CI 0.77-0.86]). After adjustments the likelihood was increased for F80-83 (HR 1.20 [95% CI 1.13-1.27]), F84 (HR 1.12 [95% CI 1.03-1.24]), and F90-92 (HR 1.09 [95% CI 1.04-1.19]), but nor for F95 (HR 1.13 [95% CI 0.99-1.30]).

After adjustments, intracytoplasmic sperm injection children compared with in vitro fertilization children had similar likelihood during follow-up for F80-83 (1.06 [95% CI 0.89–1.25]), for F84 (HR 0.92 [95% CI 0.76–1.11]), for F90-92 (HR 0.96 [95% CI 0.83–1.12]), and for F95 (HR 1.16 [95% CI 0.83–1.63]).

After adjustments, frozen embryo transfer children compared with fresh embryo transfer children had similar likelihood during follow-up for F80-83 (HR 1.11 [95% CI 0.90–1.37]), F84 (HR 0.98 [95% CI 0.76–1.27]), F90-92 (HR 0.96 [95% CI 0.78–1.19]), and F95 (HR 0.83 [95% CI 0.51–1.35]).

Limitations, reasons for caution

There may be residual confounding by unknown or unmeasured confounders. We lack information on possible confounders like the reason and length of infertility, maternal substance use other than self-reported smoking status, paternal age, and parental somatic morbidity. Additional limitations are differences in registration practice and data availability between study countries.

Wider implications of the findings

This is the largest singleton cohort and the first multinational study on the risk for neurodevelopmental disorders among ART children. While the rate of some neurodevelopmental disorders was increased among ART children, the absolute risk was moderate. The type of ART did not associate with the incidence of neurodevelopmental disorders.

Trial registration number

ISRCTN11780826

Effect of dopaminergic medication on adenosine 2A receptor availability in patients with Parkinson's disease

OBJECTIVE

To assess the necessity of withdrawing dopaminergic medication in Parkinson's disease (PD) patients for accurate estimation of adenosine 2A receptor (A_2AR) availability using [¹¹C]TMSX PET imaging. This was accomplished by studying the short-term effect of the cessation of dopaminergic medication on A_2AR availability in non-dyskinetic patients with PD treated with dopaminergic medication.

METHODS

Eight PD patients (age 67.9 ± 5.6 years; 6 men, 2 women) without dyskinesia were enrolled in this study. A_2AR availability was measured using PET imaging with a [7-methyl-¹¹C]-(E)-8-(3,4,5-trimethoxystyryl)-1,3,7-trimethylxanthine ([¹¹C]TMSX) radioligand after a short term cessation of dopaminergic medication (12hrs for levodopa, 24hrs for dopamine agonists and MAO-B inhibitors). Repeated PET imaging was performed while the patients were back 'on' their regular dopaminergic medication (median 13 days after first imaging). Conventional MRI was acquired for anatomical reference. Specific binding of [¹¹C]TMSX was quantified as distribution volume ratios (DVR) for caudate, pallidum and putamen using Logan graphical method with clustered gray matter reference region.

RESULTS

No significant differences were observed for the DVRs in all three striatal regions between 'on' and 'off' medication states. Strong correlations were also observed between the two states. Statistical equivalence was found in pallidum (TOST equivalence test, p = 0.045) and putamen (TOST equivalence test, p = 0.022), but not in caudate DVR (TOST equivalence test, p = 0.201) between the two medication states.

CONCLUSIONS

Our results show that dopaminergic medication has no significant short-term effect on the availability of A_2A receptors in putamen and pallidum of patients with PD. However, relatively poor repeatability was demonstrated in the caudate.

Whole Brain Adiabatic T1rho and Relaxation Along a Fictitious Field Imaging in Healthy Volunteers and Patients With Multiple Sclerosis: Initial Findings

BACKGROUND

In preclinical models of multiple sclerosis (MS), both adiabatic T_1rho (T_1ρadiab ) and relaxation along a fictitious field (RAFF) imaging have demonstrated potential to noninvasively characterize MS.

PURPOSE

To evaluate the feasibility of whole brain T_1ρadiab and RAFF imaging in healthy volunteers and patients with MS.

STUDY TYPE

Single institutional clinical trial.

SUBJECTS

38 healthy volunteers (24-69 years) and 21 patients (26-59 years) with MS. Five healthy volunteers underwent a second MR examination performed within 8 days. Clinical disease severity (The Expanded Disability Status Scale [EDSS] and The Multiple Sclerosis Severity Score [MSSS]) was evaluated at baseline and 1-year follow-up (FU).

FIELD STRENGTH/SEQUENCE

RAFF in second rotating frame of reference (RAFF2) was performed at 3 T using 3D-fast-field echo with magnetization preparation, RF amplitude of 11.74 μT while the corresponding value for T_1ρadiab was 13.50 μT. T₁ -, T₂ -, and FLAIR-weighted images were acquired with reconstruction voxel size 1.0 × 1.0 × 1.0 mm³ .

ASSESSMENT

The parametric maps of T_1ρadiab and RAFF2 (T_RAFF2 ) were calculated using a monoexponential model. Semi-automatic segmentation of MS lesions, white matter (WM), and gray matter (GM), and WM tracks was performed using T₁ -, T₂ -, and FLAIR-weighted images.

STATISTICAL TESTS

Regression analysis was used to evaluate correlation of T_1ρadiab and T_RAFF2 with age and disease severity while a Friedman test followed by Wilcoxon Signed Rank test for differences between tissue types. Short-term repeatability was evaluated on voxel level.

RESULTS

Both T_1ρadiab and T_RAFF2 demonstrated good short-term repeatability with relative differences on voxel level in the range of 6.1%-11.9%. Differences in T_1ρadiab and T_RAFF2 between the tissue types in MS patients were significant (P < 0.05). T_1ρadiab and T_RAFF2 correlated (P < 0.001) with baseline EDSS/MSSM and disease progression at FU (P < 0.001).

DATA CONCLUSION

Whole brain T_1ρadiab and T_RAFF2 at 3 T was feasible with significant differences in T_1ρadiab and T_RAFF2 values between tissues types and correlation with disease severity.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 1.

Brain TSPO-PET predicts later disease progression independent of relapses in multiple sclerosis

Overactivation of microglia is associated with most neurodegenerative diseases. In this study we examined whether PET-measurable innate immune cell activation predicts multiple sclerosis disease progression. Activation of microglia/macrophages was measured using the 18-kDa translocator protein (TSPO)-binding radioligand ¹¹C-PK11195 and PET imaging in 69 patients with multiple sclerosis and 18 age- and sex-matched healthy controls. Radioligand binding was evaluated as the distribution volume ratio from dynamic PET images. Conventional MRI and disability measurements using the Expanded Disability Status Scale were performed for patients at baseline and 4.1 ± 1.9 (mean ± standard deviation) years later. Fifty-one (74%) of the patients were free of relapses during the follow-up period. Patients had increased activation of innate immune cells in the normal-appearing white matter and in the thalamus compared to the healthy control group (P = 0.033 and P = 0.003, respectively, Wilcoxon). Forward-type stepwise logistic regression was used to assess the best variables predicting disease progression. Baseline innate immune cell activation in the normal-appearing white matter was a significant predictor of later progression when the entire multiple sclerosis cohort was assessed [odds ratio (OR) = 4.26; P = 0.048]. In the patient subgroup free of relapses there was an association between macrophage/microglia activation in the perilesional normal-appearing white matter and disease progression (OR = 4.57; P = 0.013). None of the conventional MRI parameters measured at baseline associated with later progression. Our results strongly suggest that innate immune cell activation contributes to the diffuse neural damage leading to multiple sclerosis disease progression independent of relapses.

Widespread Glial Activation in Primary Progressive Multiple Sclerosis Revealed by 18F-PBR06 PET: A Clinically Feasible, Individualized Approach

ABSTRACT

A 64-year-old man with primary progressive multiple sclerosis (Expanded Disability Status Scale 3.5) underwent PET using 18F-PBR06, a second-generation 18-kDa translocator protein ligand targeting activated brain microglia and astrocytes. Voxel-by-voxel statistical comparison of patient's PET images (acquired 60-90 minutes postinjection) with a healthy control data set was performed to generate a 3-dimensional z-score map of increased radiotracer uptake, which showed widespread increased glial activation in normal-appearing cerebral white matter, white matter lesional and perilesional areas, brainstem and cerebellum. In contrast, patient's 3-T MRI scan showed only a few small white matter brain lesions without contrast enhancement.

Fingolimod treatment reverses signs of diffuse white matter damage in multiple sclerosis: A pilot study

BACKGROUND

In multiple sclerosis (MS) diffuse normal appearing white matter (NAWM) damage may drive chronic worsening independent of relapse activity. Diffusion tensor imaging (DTI) is a nonconventional MRI technique that can be used to assess microstructural alterations in myelin and axons. The aim of our study was to investigate the effect of six months fingolimod treatment on the integrity of entire and segmented NAWM in patients with relapsing-remitting multiple sclerosis (RRMS).

METHODS

Ten RRMS patients initiating fingolimod treatment were included in the study. Patients underwent 3 T MRI including diffusion tensor sequences at baseline before the initiation of treatment and at six months. The mean values for fractional anisotropy (FA), and mean, radial and axial diffusivities (MD, RD and AD) were calculated within the whole NAWM and in six segmented sub-regions of NAWM (frontal, parietal, temporal, occipital, cingulate and deep NAWM). Clinical characteristics, Expanded Disability Status Scale (EDSS) and volumetric MRI data were also evaluated.

RESULTS

In the cingulate NAWM FA was increased and RD was decreased significantly at six months compared to baseline (0.462 vs. 0.472, P = 0.027 and 0.000646 vs. 0.000634, P = 0.041, respectively), indicating improvements in myelin and axonal integrity following fingolimod treatment, whereas there were no alterations in cingulate MD or AD. Cingulate and temporal FA and RD correlated with T2 lesion volume percentage of cingulate and temporal areas. EDSS change correlated with change of the whole NAWM AD.

CONCLUSIONS

Increased FA and decreased RD in the cingulate NAWM might suggest microstructural fingolimod-induced improvements in the normal appearing cingulate white matter. Our results support the concept that DTI can be used as a marker of diffuse neuronal damage also in interventional settings.

High serum neurofilament associates with diffuse white matter damage in MS

Objective

To evaluate to which extent serum neurofilament light chain (NfL) increase is related to diffusion tensor imaging–MRI measurable diffuse normal-appearing white matter (NAWM) damage in MS.

Methods

Seventy-nine patients with MS and 10 healthy controls underwent MRI including diffusion tensor sequences and serum NfL determination by single molecule array (Simoa). Fractional anisotropy and mean, axial, and radial diffusivities were calculated within the whole and segmented (frontal, parietal, temporal, occipital, cingulate, and deep) NAWM. Spearman correlations and multiple regression models were used to assess the associations between diffusion tensor imaging, volumetric MRI data, and NfL.

Results

Elevated NfL correlated with decreased fractional anisotropy and increased mean, axial, and radial diffusivities in the entire and segmented NAWM (for entire NAWM ρ = −0.49, p = 0.005; ρ = 0.49, p = 0.005; ρ = 0.43, p = 0.018; and ρ = 0.48, p = 0.006, respectively). A multiple regression model examining the effect of diffusion tensor indices on NfL showed significant associations when adjusted for sex, age, disease type, the expanded disability status scale, treatment, and presence of relapses. In the same model, T2 lesion volume was similarly associated with NfL.

Conclusions

Our findings suggest that elevated serum NfL in MS results from neuroaxonal damage both within the NAWM and focal T2 lesions. This pathologic heterogeneity ought to be taken into account when interpreting NfL findings at the individual patient level.

Insights into disseminated MS brain pathology with multimodal diffusion tensor and PET imaging

OBJECTIVE

To evaluate in vivo the co-occurrence of microglial activation and microstructural white matter (WM) damage in the MS brain and to examine their association with clinical disability.

METHODS

18-kDa translocator protein (TSPO) brain PET imaging was performed for evaluation of microglial activation by using the radioligand [11C](R)-PK11195. TSPO binding was evaluated as the distribution volume ratio (DVR) from dynamic PET images. Diffusion tensor imaging (DTI) and conventional MRI (cMRI) were performed at the same time. Mean fractional anisotropy (FA) and mean (MD), axial, and radial (RD) diffusivities were calculated within the whole normal-appearing WM (NAWM) and segmented NAWM regions appearing normal in cMRI. Fifty-five patients with MS and 15 healthy controls (HCs) were examined.

RESULTS

Microstructural damage was observed in the NAWM of the MS brain. DTI parameters of patients with MS were significantly altered in the NAWM compared with an age- and sex-matched HC group: mean FA was decreased, and MD and RD were increased. These structural abnormalities correlated with increased TSPO binding in the whole NAWM and in the temporal NAWM (p < 0.05 for all correlations; p < 0.01 for RD in the temporal NAWM). Both compromised WM integrity and increased microglial activation in the NAWM correlated significantly with higher clinical disability measured with the Expanded Disability Status Scale score.

CONCLUSIONS

Widespread structural disruption in the NAWM is linked to neuroinflammation, and both phenomena associate with clinical disability. Multimodal PET and DTI allow in vivo evaluation of widespread MS pathology not visible using cMRI.

Rituximab in the treatment of multiple sclerosis in the Hospital District of Southwest Finland

BACKGROUND

There are already numerous B-cell depleting monoclonal anti-CD20 antibodies which have been used to reduce the inflammatory burden associated with multiple sclerosis (MS). We describe here our experience of treating MS-patients with B-cell depleting rituximab.

PATIENTS AND METHODS

All MS-patients (n = 72) who had received rituximab treatment for at least six months by January 2019 were identified from the patient charts at the Turku University Hospital. Information about MS disease subtype, disease severity, MR-imaging outcomes and B-cell counts were collected from the charts.

RESULTS

Rituximab was well received and well tolerated by the patients. There were no serious infusion-related side effects. The most serious adverse event that led to treatment discontinuation was neutropenia. After rituximab initiation the annual number of relapses was decreased in the relapsing remitting and secondary progressive MS groups and the mean number of gadolinium-enhancing lesions was decreased in relapsing remitting MS. Our study confirms the usability of rituximab treatment for MS in the Finnish health care environment.

CONCLUSIONS

Off-label rituximab-treatment can be successfully used to reduce MS disease burden for the benefit of MS patients.

Progressive dopaminergic defect in a patient with primary progressive multiple sclerosis

Dopamine has a modulatory role in a number of autoimmune diseases, but there are no published cases of longitudinal dopaminergic imaging in multiple sclerosis (MS). Here we report a patient with primary progressive multiple sclerosis (PPMS) who was scanned twice with brain dopamine transporter single photon emission computed tomography (SPECT) with an interval of four years. The results showed a loss of tracer binding that corresponded to a 4-7 fold steeper decline than in normal ageing. The finding points to a relevant role of nigrostriatal dopaminergic degeneration in the pathological process of PPMS.

Natalizumab treatment reduces microglial activation in the white matter of the MS brain

Objective

To evaluate whether natalizumab treatment reduces microglial activation in MS.

Methods

We measured microglial activation using the 18-kDa translocator protein (TSPO)-binding radioligand [¹¹C]PK11195 and PET imaging in 10 patients with MS before and after 1 year treatment with natalizumab. Microglial activation was evaluated as the distribution volume ratio (DVR) of the specifically bound radioligand in brain white and gray matter regions of interest. MRI and disability measurements were performed for comparison. Evaluation was performed identically with 11 age- and sex-matched patients with MS who had no MS therapy.

Results

Natalizumab treatment reduced microglial activation in the normal-appearing white matter (NAWM; baseline DVR vs DVR after 1 year of treatment 1.25 vs 1.22, p = 0.014, Wilcoxon) and at the rim of chronic lesions (baseline DVR vs DVR after 1 year of treatment 1.24 vs 1.18, p = 0.014). In patients with MS with no treatment, there was an increase in microglial activation at the rim of chronic lesions (1.23 vs 1.27, p = 0.045). No alteration was observed in microglial activation in gray matter areas. In the untreated patient group, higher microglial activation at baseline was associated with more rapid disability progression during an average of 4 years of follow-up.

Conclusions

TSPO-PET imaging can be used as a tool to assess longitudinal changes in microglial activation in the NAWM and in the perilesional areas in the MS brain in vivo. Natalizumab treatment reduces the diffuse compartmentalized CNS inflammation related to brain resident innate immune cells.

Serum glial fibrillary acidic protein correlates with multiple sclerosis disease severity

Background:

Cerebrospinal fluid (CSF) levels of two soluble biomarkers, glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL), have been shown to associate with multiple sclerosis (MS) disease progression. Now, both biomarkers can be detected reliably in serum, and importantly, their serum levels correlate well with their CSF levels.

Objective:

To evaluate the usability of serum GFAP measurement as a biomarker of progressive disease and disease severity in MS.

Methods:

Clinical course, Expanded Disability Status Scale (EDSS), disease duration, patient age and magnetic resonance imaging (MRI) parameters were reviewed in 79 MS patients in this cross-sectional hospital-based study. Serum samples were collected for measurement of GFAP and NfL concentrations using single molecule array (Simoa) assay. A cohort of healthy controls was evaluated for comparison.

Results:

Higher serum concentrations of both GFAP and NfL were associated with higher EDSS, older age, longer disease duration, progressive disease course and MRI pathology.

Conclusion:

Earlier studies have demonstrated that GFAP, unlike NfL, is not increased in association with acute focal inflammation-related nervous system damage. Our work suggests that GFAP serum level associates with disease progression in MS and could potentially serve as an easily measurable biomarker of central nervous system (CNS) pathology related to disease progression in MS.

Steroid-responsive encephalopathy with a peculiar CSF biomarker profile in an 89-year-old man

Being treatable, steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), or Hashimoto's encephalopathy, should be distinguished from untreatable conditions. Our patient was a previously healthy 89-year-old man, who presented with cognitive and balance deterioration over several months. His cerebrospinal fluid (CSF) examination was positive for protein 14-3-3 but no other test suggested Creutzfeldt-Jacob disease. His condition improved markedly, although not fully, with intravenous corticosteroids. In control CSF sampling, protein 14-3-3 was negative but a biomarker signature consistent with Alzheimer's disease was observed. SREAT should be considered also in the very elderly in case of subacute encephalopathy.

Positron emission tomography imaging in evaluation of MS pathology in vivo

Positron emission tomography (PET) gives an opportunity to quantitate the expression of specific molecular targets in vivo and longitudinally in brain and thus enhances our possibilities to understand and follow up multiple sclerosis (MS)-related pathology. For successful PET imaging, one needs a relevant target molecule within the brain, to which a blood–brain barrier–penetrating specific radioligand will bind. 18-kDa translocator protein (TSPO)-binding radioligands have been used to detect activated microglial cells at different stages of MS, and remyelination has been measured using amyloid PET. Several PET ligands for the detection of other inflammatory targets, besides TSPO, have been developed but not yet been used for imaging MS patients. Finally, synaptic density evaluation has been successfully tested in human subjects and gives opportunities for the evaluation of the development of cortical and deep gray matter pathology in MS. This review will discuss PET imaging modalities relevant for MS today.

Evaluation of Microglial Activation in Multiple Sclerosis Patients Using Positron Emission Tomography

Understanding the mechanisms underlying progression in multiple sclerosis (MS) is one of the key elements contributing to the identification of appropriate therapeutic targets for this under-managed condition. In addition to plaque-related focal inflammatory pathology typical for relapsing remitting MS there are, in progressive MS, widespread diffuse alterations in brain areas outside the focal lesions. This diffuse pathology is tightly related to microglial activation and is co-localized with signs of neurodegeneration. Microglia are brain-resident cells of the innate immune system and overactivation of microglia is associated with several neurodegenerative diseases. Understanding the role of microglial activation in relation to developing neurodegeneration and disease progression may provide a key to developing therapies to target progressive MS. 18-kDa translocator protein (TSPO) is a mitochondrial molecule upregulated in microglia upon their activation. Positron emission tomography (PET) imaging using TSPO-binding radioligands provides a method to assess microglial activation in patients in vivo. In this mini-review, we summarize the current status of TSPO imaging in the field of MS. In addition, the review discusses new insights into the potential use of this method in treatment trials and in clinical assessment of progressive MS.

Microglial activation, white matter tract damage, and disability in MS

Objective

To investigate the relationship of in vivo microglial activation to clinical and MRI parameters in MS.

Methods

Patients with secondary progressive MS (n = 10) or relapsing-remitting MS (n = 10) and age-matched healthy controls (n = 17) were studied. Microglial activation was measured using PET and radioligand [¹¹C](R)-PK11195. Clinical assessment and structural and quantitative MRI including diffusion tensor imaging (DTI) were performed for comparison.

Results

[¹¹C](R)-PK11195 binding was significantly higher in the normal-appearing white matter (NAWM) of patients with secondary progressive vs relapsing MS and healthy controls, in the thalami of patients with secondary progressive MS vs controls, and in the perilesional area among the progressive compared with relapsing patients. Higher binding in the NAWM was associated with higher clinical disability and reduced white matter (WM) structural integrity, as shown by lower fractional anisotropy, higher mean diffusivity, and increased WM lesion load. Increasing age contributed to higher microglial activation in the NAWM among patients with MS but not in healthy controls.

Conclusions

PET can be used to quantitate microglial activation, which associates with MS progression. This study demonstrates that increased microglial activity in the NAWM correlates closely with impaired WM structural integrity and thus offers one rational pathologic correlate to diffusion tensor imaging (DTI) parameters.

Brain amyloid load and its associations with cognition and vascular risk factors in FINGER Study

OBJECTIVE

To investigate brain amyloid pathology in a dementia-risk population defined as cardiovascular risk factors, aging, and dementia risk (CAIDE) score of at least 6 but with normal cognition and to examine associations between brain amyloid load and cognitive performance and vascular risk factors.

METHODS

A subgroup of 48 individuals from the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) main study participated in brain ¹¹C-Pittsburgh compound B (PiB)-PET imaging, brain MRI, and neuropsychological assessment at the beginning of the study. Lifestyle/vascular risk factors were determined as body mass index, blood pressure, total and low-density lipoprotein cholesterol, and glucose homeostasis model assessment. White matter lesions were visually rated from MRIs by a semiquantitative Fazekas score.

RESULTS

Twenty participants (42%) had a positive PiB-PET on visual analysis. The PiB-positive group performed worse in executive functioning tests, included more participants with APOE ε4 allele (50%), and showed slightly better glucose homeostasis compared to PiB-negative participants. PiB-positive and -negative participants did not differ significantly in other cognitive domain scores or other vascular risk factors. There was no significant difference in Fazekas score between the PiB groups.

CONCLUSIONS

The high percentage of PiB-positive participants provides evidence of a successful recruitment process of the at-risk population in the main FINGER intervention trial. The results suggest a possible association between early brain amyloid accumulation and decline in executive functions. APOE ε4 was clearly associated with amyloid positivity, but no other risk factor was found to be associated with positive PiB-PET.

Severe neutropenia after rituximab-treatment of multiple sclerosis

We present here the first MS-case where rituximab-treatment led to grade IV neutropenia, with hospitalization and treatment of a serious infection with broad-spectrum antibiotics. The neutropenia resolved promptly with granulocyte-colony stimulating factor-treatment and the patient recovered well. Due to risk of recurring neutropenia rituximab-treatment was not re-administered. We discuss the mechanisms and occurrence of neutropenia as a side effect to rituximab-treatment of MS, and remind of the importance of monitoring rituximab-treated MS-patients for this rare but potentially dangerous side effect.

Evaluation of the Effect of Fingolimod Treatment on Microglial Activation Using Serial PET Imaging in Multiple Sclerosis

Traditionally, multiple sclerosis (MS) has been considered a white matter disease with focal inflammatory lesions. It is, however, becoming clear that significant pathology, such as microglial activation, also takes place outside the plaque areas, that is, in areas of normal-appearing white matter (NAWM) and gray matter (GM). Microglial activation can be detected in vivo using 18-kDa translocator protein (TSPO)-binding radioligands and PET. It is unknown whether fingolimod affects microglial activation in MS. The aim of this study was to investigate whether serial PET can be used to evaluate the effect of fingolimod treatment on microglial activation. Methods: Ten relapsing-remitting MS patients were studied using the TSPO radioligand ¹¹C-(R)-PK11195. Imaging was performed at baseline and after 8 and 24 wk of fingolimod treatment. Eight healthy individuals were imaged for comparison. Microglial activation was evaluated as distribution volume ratio of ¹¹C-(R)-PK11195. Results: The patients had MS for an average of 7.9 ± 4.3 y (mean ± SD), their total relapses averaged 4 ± 2.4, and their Expanded Disability Status Scale was 2.7 ± 0.5. The patients were switched to fingolimod because of safety reasons or therapy escalation. The mean washout period before the initiation of fingolimod was 2.3 ± 1.1 mo. The patients were clinically stable on fingolimod. At baseline, microglial activation was significantly higher in the combined NAWM and GM areas of MS patients than in healthy controls (P = 0.021). ¹¹C-(R)-PK11195 binding was reduced (-12.31%) within the combined T2 lesion area after 6 mo of fingolimod treatment (P = 0.040) but not in the areas of NAWM or GM. Conclusion: Fingolimod treatment reduced microglial/macrophage activation at the site of focal inflammatory lesions, presumably by preventing leukocyte trafficking from the periphery. It did not affect the widespread, diffuse microglial activation in the NAWM and GM. The study opens new vistas for designing future therapeutic studies in MS that use the evaluation of microglial activation as an imaging outcome measure.

Imaging of microglial activation in MS using PET: Research use and potential future clinical application

Multiple sclerosis (MS) is a complex disease, where several processes can be selected as a target for positron emission topography (PET) imaging. Unlike magnetic resonance imaging (MRI), PET provides specific and quantitative information, and unlike neuropathology, it can be non-invasively applied to living patients, which enables longitudinal follow-up of the MS pathology. In the study of MS, PET can be useful for in vivo evaluation of specific pathological characteristics at various stages of the disease. Increased understanding of the progressive MS pathology will enhance the treatment options of this undertreated condition. The ultimate goal of developing and expanding PET in the study of MS is to have clinical non-invasive in vivo imaging biomarkers of neuroinflammation that will help to establish prognosis and accurately measure response to therapeutics. This topical review provides an overview of the promises and challenges of the use of PET in MS.

Utilization of PET imaging in differential diagnostics between a tumefactive multiple sclerosis lesion and low-grade glioma

We present a case where a 30-year-old man with a history of combined MS and Charcot-Marie-Tooth (CMT I) disease was additionally diagnosed and treated for grade II glioma (astrocytoma). Tumefactive MS and gliomas are sometimes difficult to distinguish from one another based on conventional magnetic resonance imaging (MRI). In our case, positron emission tomography (PET) scans with(11)C-methionine ((11)C-MET) and (11)C-PK11195 radioligands were performed to aid in differential diagnostics. The diagnosis was confirmed finally by brain biopsy. The usefulness of PET imaging in differential diagnostics between tumefactive MS and glioma is discussed.

Imaging neuroinflammation in multiple sclerosis using TSPO-PET

Conventional MR imaging (MRI) techniques form the cornerstone of multiple sclerosis (MS) diagnostics and clinical follow-up today. MRI is sensitive in demonstrating focal inflammatory lesions and diffuse atrophy. However, especially in progressive MS, there is increasingly widespread diffuse pathology also outside the plaques, often related to microglial activation and neurodegeneration. This cannot be detected using conventional MRI. Positron emission tomography (PET) imaging using 18-kDa translocator protein (TSPO) binding radioligands has recently shown promise as a tool to detect this diffuse pathology in vivo, and for the first time allows one to follow its development longitudinally. It is becoming evident that the more advanced the MS disease is, the more pronounced is microglial activation. PET imaging allows the detection of MS-related pathology at molecular level in vivo. It has potential to enable measurement of effects of new disease-modifying drugs aimed at reducing neurodegeneration and neuroinflammation. PET imaging could thus be included in the design of future clinical trials of progressive MS. There are still technical issues related to the quality of TSPO radioligands and post-processing methodology, and comparison of studies from different PET centres is challenging. In this review, we summarise the main evidence supporting the use of TSPO-PET as a tool to explore the diffuse inflammation in MS.

In Vivo Detection of Diffuse Inflammation in Secondary Progressive Multiple Sclerosis Using PET Imaging and the Radioligand ¹¹C-PK11195

Patients with secondary progressive multiple sclerosis (SPMS) are lacking efficient medication to slow down the progression of their disease. PET imaging holds promise as a method to study, at the molecular level and in vivo, the central nervous system pathology of SPMS. PET might thus help to elucidate potential therapeutic targets and be useful as an imaging biomarker in future treatment trials of progressive multiple sclerosis. The objective of this study was to evaluate whether translocator protein (TSPO) imaging could be used to visualize the diffuse inflammation located in the periplaque area and in the normal-appearing white matter (NAWM) in the brains of patients with SPMS.

METHODS

This was an imaging study using MR imaging and PET with (11)C-PK11195 binding to TSPO, which is expressed in activated, but not in resting, microglia. Ten SPMS patients with a mean expanded disability status scale score of 6.3 (SD, 1.5) and eight age-matched healthy controls were studied. The imaging was performed using High-Resolution Research Tomograph PET and 1.5-T MR imaging scanners. Microglial activation was evaluated as the distribution volume ratio (DVR) of (11)C-PK11195 from dynamic PET images. DVR estimations were performed with special interest in NAWM and gray matter using region-of-interest and parametric image-based approaches.

RESULTS

The DVR of (11)C-PK11195 was significantly increased in the periventricular and total NAWM (P = 0.016 and P < 0.001, respectively) and in the thalamic ROIs (P = 0.027) of SPMS patients, compared with the control group. Similarly, parametric image analysis showed widespread increases of (11)C-PK11195 in the white matter of SPMS patients, compared with healthy controls. Increased perilesional TSPO uptake was present in 57% of the chronic T1 lesions in MR imaging.

CONCLUSION

The finding of increased (11)C-PK11195 binding in the NAWM of SPMS patients is in line with the neuropathologic demonstration that activated microglial cells are the source of diffuse NAWM inflammation. Evaluating microglial activation with TSPO-binding PET ligands provides a unique tool to assess diffuse brain inflammation and perilesional activity in progressive multiple sclerosis in vivo.

Brain dopamine transporter binding and glucose metabolism in progressive supranuclear palsy-like creutzfeldt-jakob disease

Here, we present a patient with Creutzfeldt-Jakob disease (CJD) who developed initial symptoms mimicking progressive supranuclear palsy (PSP). Before the development of typical CJD symptoms, functional imaging supported a diagnosis of PSP when [(123)I]-FP-CIT-SPECT showed a defect in striatal dopamine transporter binding, while [(18)F]-fluorodeoxyglucose PET showed cortical hypometabolism suggestive of Lewy body dementia. However, the postmortem neuropathological examination was indicative of CJD only, without tau protein or Lewy body findings. This case demonstrates that CJD should be taken into account in rapidly progressing atypical cases of parkinsonism, even when functional imaging supports a diagnosis of a movement disorder.

Adenosine A2A receptors in secondary progressive multiple sclerosis: a [(11)C]TMSX brain PET study

In this study, positron emission tomography (PET) imaging with a radioligand to adenosine A2A receptors (A2AR)-a potent regulator of inflammation-was used to gain insight into the molecular alterations in normal-appearing white matter (NAWM) and gray matter (GM) in secondary progressive multiple sclerosis (SPMS). Normal-appearing white matter and GM, despite seeming normal in conventional magnetic resonance imaging (MRI), are important loci of widespread inflammation, neuronal damage, and source of progressive disability in multiple sclerosis (MS). Dynamic PET imaging using A2AR-specific [(11)C]TMSX and brain MRI with diffusion tensor imaging were performed to eight SPMS patients and seven healthy controls. Distribution volumes (VT) of [(11)C]TMSX were analyzed from 13 regions of interest using Logan plot with arterial plasma input. The SPMS patients had significantly increased [(11)C]TMSX-VT in NAWM compared with controls (mean (s.d.): 0.55 (±0.08) vs. 0.45 (±0.05); P=0.036). Both the increased VT and the decreased fractional anisotropy (FA) in NAWM were associated with higher expanded disability status scale (EDSS) scores (P=0.030 and P=0.012, respectively), whereas the T2-lesion load of SPMS patients did not correlate with EDSS. This study shows, that A2ARs are increased in the brain of SPMS patients, and that [(11)C]TMSX-PET provides a novel approach to learn about central nervous system pathology in SPMS in vivo.

Carbon monoxide poisoning-induced nigrostriatal dopaminergic dysfunction detected using positron emission tomography (PET)

A malfunctioning heater caused a severe carbon monoxide (CO) intoxication leading to unconsciousness and predominantly right-sided extrapyramidal syndrome in a 29-year-old man. Follow-up included thorough clinical monitoring, and brain MRI and PET studies. Nine days after the poisoning, brain MRI showed symmetrical necrosis in the globus pallidi, but no abnormality was found in the substantia nigra. In addition, white matter periventricular lesions were seen. In a control scan 14 months later the white matter changes had subsided but small necrotic lesions were still noted bilaterally in the globus pallidi. A 6-[(18)F]fluoro-L-dopa PET examination performed 5 weeks after the intoxication revealed impaired presynaptic dopaminergic function in the left putamen whereas in the right putamen the dopaminergic activity was within normal limits. [(11)C] raclopride PET imaging 4 months after the poisoning showed no abnormality in postsynaptic D2 binding in the striatum. Clinically, the parkinsonian symptoms resolved 1.5 years after the poisoning. The final outcome of the recovery was excellent, and the patient returned to work. This is the first case reported where unilateral presynaptic, dopaminergic hypofunction in putamen could be confirmed with fluoro-l-dopa PET imaging on a patient with extrapyramidal syndrome caused by CO poisoning. Our results emphasize that CO intoxication can lead to striatal dopaminergic hypofunction, and that PET is a sensitive tool in evaluating extrapyramidal system after sudden neurotoxic insult.

Intracellular pH regulation in rainbow trout (Oncorhynchus mykiss) hepatocytes: the activity of sodium/proton exchange is oxygen-dependent

We studied pH regulation in freshly isolated rainbow trout hepatocytes using microspectrofluorometry with the fluorescent dye BCECF. In accordance with earlier data on rainbow trout hepatocytes, ion substitution (N-methyl D-glucamine for sodium and gluconate for chloride) and transport inhibitor [10 microM M methyl isobutyl amiloride (MIA) to inhibit sodium/proton exchange and 100 microM DIDS to inhibit bicarbonate transport] studies in either Hepes-buffered or bicarbonate/carbon dioxide-buffered media (extracellular pH 7.6) indicated a role for sodium/proton exchange, sodium-dependent bicarbonate transport, and sodium-independent anion exchange in the regulation of hepatocyte pH. In Hepes-buffered medium, the activity of the sodium/proton exchanger (i.e. proton extrusion inhibited by MIA) was greater at 1% than at 21% oxygen. The oxygen dependency of the sodium/proton exchange is not caused by hydroxyl radicals, which appear to mediate the oxygen sensitivity of potassium-chloride cotransport in erythrocytes.

Monitoring odorous sulfur emissions using self-organizing maps for handling ion mobility spectrometry data

Possibilities for monitoring emissions of reduced sulfur compounds in pulp and paper mills were investigated using ion mobility spectrometry (IMS) and a self-organizing map (SOM) algorithm. The reduced sulfur compounds measured were hydrogen sulfide (H2S), dimethyl sulfide (DMS), and methyl mercaptan (MM). Attention was paid to momentary concentrations because there is no monitoring device able to measure peak concentrations of reduced sulfur compounds under field conditions. These methods were evaluated by measuring the reduced sulfur compounds first in the laboratory and then at a process monitoring site at a pulp factory. The aim was to find out whether it would be possible to use the laboratory measurements to recognize the same reduced sulfur compounds at the monitoring site. Data collection was followed by analysis using the SOM algorithm and Sammon's mapping. The results showed that the IMS spectra of reduced sulfur compounds and their mixtures can be distinguished from each other by computationally intelligent methods and that the spectra from the process monitoring site corresponded with the laboratory measurements to a certain extent.

Glutamine: fructose-6-phosphate amidotransferase activity and gene expression are regulated in a tissue-specific fashion in pregnant rats

We examined whether regulation of glutamine: fructose-6-phosphate amidotransferase (GFA), the rate-limiting enzyme of the hexosamine pathway, is tissue specific and if so whether such regulation occurs at the level of gene expression. We compared GFA activity and expression and levels of UDP-hexosamines and UDP-hexoses between insulin-sensitive (liver and muscle) tissues and a glucose-sensitive (placenta) tissue from 19 day pregnant streptozotocin diabetic and non-diabetic rats. In pregnant non-diabetic rats GFA activities averaged (1521+/-75 pmol/mg protein x min) in the placenta, 895+/-74 in the liver and 81+/-11 in muscle (p<0.001 between each tissue). In the diabetic rats, GFA activities were approximately 50% decreased both in the liver (340+/-42 pmol/mg protein x min, p<0.05 vs control rats) and in skeletal muscle (46+/-3, p<0.05) compared to control rats. In the placenta, GFA activities were identical between diabetic (1519+/-112 pmol/mg protein x min) and non-diabetic (1521+/-75) animals. In the liver, the reduction in GFA activity could be attributed to a significant decrease in GFA mRNA concentrations, while GFA mRNA concentrations were similar in the placenta between diabetic and non-diabetic animals. UDP-N-acetylglucosamine (UDP-GlcNAc), the end product of the hexosamine pathway, was significantly reduced in the liver and in skeletal muscle but similar in the placenta between diabetic and non-diabetic rats. In summary, GFA activity and expression and the concentration of UDP-GlcNAc are decreased in the liver but unaltered in the placenta, although GFA activity is almost 2-fold higher in this tissue than in the liver. These data provide the first evidence for tissue specific regulation of GFA and for its regulation at the level of gene expression.

Incorporation of [3-3H]glucose and 2-[1-14C]deoxyglucose into glycogen in heart and skeletal muscle in vivo: implications for the quantitation of tissue glucose uptake

2-deoxyglucose has been widely used to quantitate tissue glucose uptake in vivo, assuming that 2-deoxyglucose is transported and phosphorylated but not further metabolized. We examined the validity of this assumption by infusing [3-3H]glucose and 2-[1-14C]deoxyglucose in a similar primed continuous fashion to chronically catheterized, freely moving rats during normoglycemic hyperinsulinemic conditions. The rates of 2-deoxyglucose uptake were determined from the accumulation of 2-[1-14C]deoxyglucose-6-phosphate and 2-[1-14C]deoxyglucose-6-phosphate combined with the rate of the incorporation of 2-[1-14C]deoxyglucose into glycogen in rectus abdominis muscle and the heart. When the rates of glycogen synthesis during the 2-h hyperinsulinemic period from the two tracers were compared in rectus abdominis muscle, the rate of glycogen synthesis was twofold higher when measured with [3-3H]glucose (337 +/- 14 micromol x kg(-1) x min(-1)) than when measured with 2-[1-14C]deoxyglucose (166 +/- 10 micromol x kg(-1) x min(-1), P < 0.001). In the heart, the rate of glycogen synthesis was twofold higher when measured with 2-[1-14C]deoxyglucose (141 +/- 20 micromol x kg(-1) x min(-1)) than when measured with [3-3H]glucose (72 +/- 15 micromol x kg(-1) x min(-1), P < 0.001). The rate of 2-deoxyglucose uptake was 29% underestimated in rectus abdominis muscle, when counts found in glycogen were not included in glucose uptake calculations (398 +/- 25 vs. 564 +/- 25 micromol x kg(-1) x min(-1), P < 0.001). In the heart, glucose uptake was underestimated by 7% if glycogen counts were not taken into account (1,786 +/- 278 vs. 1,926 +/- 291 micromol x kg(-1) dry x min(-1), P < 0.05). The fraction of [3-3H]glucose incorporated into glycogen of total glucose metabolism (calculated from 2-deoxyglucose conversion to 2-deoxyglucose-6-phosphate and glycogen) was 0.6 (337/564) in rectus abdominis muscle and 0.037 (72/1,926) in the heart. We conclude that 2-deoxyglucose is incorporated into glycogen in the heart and in skeletal muscle in vivo under normoglycemic hyperinsulinemic conditions in the rat. Failure to consider the incorporation of 2-deoxyglucose into glycogen will underestimate the rate of tissue glucose uptake. To avoid such problems, the amount of 2-deoxyglucose incorporated into glycogen should be quantitated in subsequent studies.