A Double-Blind, Randomized, Placebo-Controlled Trial of Ursodeoxycholic Acid (UDCA) in Parkinson's Disease

BACKGROUND

Rescue of mitochondrial function is a promising neuroprotective strategy for Parkinson's disease (PD). Ursodeoxycholic acid (UDCA) has shown considerable promise as a mitochondrial rescue agent across a range of preclinical in vitro and in vivo models of PD.

OBJECTIVES

To investigate the safety and tolerability of high-dose UDCA in PD and determine midbrain target engagement.

METHODS

The UP (UDCA in PD) study was a phase II, randomized, double-blind, placebo-controlled trial of UDCA (30 mg/kg daily, 2:1 randomization UDCA vs. placebo) in 30 participants with PD for 48 weeks. The primary outcome was safety and tolerability. Secondary outcomes included 31-phosphorus magnetic resonance spectroscopy (31 P-MRS) to explore target engagement of UDCA in PD midbrain and assessment of motor progression, applying both the Movement Disorder Society Unified Parkinson's Disease Rating Scale Part III (MDS-UPDRS-III) and objective, motion sensor-based quantification of gait impairment.

RESULTS

UDCA was safe and well tolerated, and only mild transient gastrointestinal adverse events were more frequent in the UDCA treatment group. Midbrain 31 P-MRS demonstrated an increase in both Gibbs free energy and inorganic phosphate levels in the UDCA treatment group compared to placebo, reflecting improved ATP hydrolysis. Sensor-based gait analysis indicated a possible improvement of cadence (steps per minute) and other gait parameters in the UDCA group compared to placebo. In contrast, subjective assessment applying the MDS-UPDRS-III failed to detect a difference between treatment groups.

CONCLUSIONS

High-dose UDCA is safe and well tolerated in early PD. Larger trials are needed to further evaluate the disease-modifying effect of UDCA in PD. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Analysis of brain and spinal MRI measures in a common domain to investigate directional neurodegeneration in motor neuron disease

BACKGROUND

Magnetic resonance imaging (MRI) of the brain and cervical spinal cord is often performed in diagnostic evaluation of suspected motor neuron disease/amyotrophic lateral sclerosis (MND/ALS). Analysis of MRI-derived tissue damage metrics in a common domain facilitates group-level inferences on pathophysiology. This approach was applied to address competing hypotheses of directionality of neurodegeneration, whether anterograde, cranio-caudal dying-forward from precentral gyrus or retrograde, dying-back.

METHODS

In this cross-sectional study, MRI was performed on 75 MND patients and 13 healthy controls. Precentral gyral thickness was estimated from volumetric T1-weighted images using FreeSurfer, corticospinal tract fractional anisotropy (FA) from diffusion tensor imaging using FSL, and cross-sectional cervical cord area between C1-C8 levels using Spinal Cord Toolbox. To analyse these multimodal data within a common domain, individual parameter estimates representing tissue damage at each corticospinal tract level were first converted to z-scores, referenced to healthy control norms. Mixed-effects linear regression models were then fitted to these z-scores, with gradients hypothesised to represent directionality of neurodegeneration.

RESULTS

At group-level, z-scores did not differ significantly between precentral gyral and intracranial corticospinal tract tissue damage estimates (regression coefficient - 0.24, [95% CI - 0.62, 0.14], p = 0.222), but step-changes were evident between intracranial corticospinal tract and C1 (1.14, [95% CI 0.74, 1.53], p < 0.001), and between C5 and C6 cord levels (0.98, [95% CI 0.58, 1.38], p < 0.001).

DISCUSSION

Analysis of brain and cervical spinal MRI data in a common domain enabled investigation of pathophysiological hypotheses in vivo. A cranio-caudal step-change in MND patients was observed, and requires further investigation in larger cohorts.

Using 31-phosphorus magnetic resonance spectroscopy (31P-MRS) to identify Parkinson’s Disease subgroups with bioenergetic dysfunction

Background

Sporadic Parkinson’s disease (sPD) is an aetiologically heterogeneous disorder. Identification of distinct pathogenic mechanisms causing sPD will be crucial to develop future “Precision Medicine” approaches. 31P-MRS is a non-invasive tool that can quantify key bionenergetic metabolites in individual patients.

Objective

To determine whether 31P-MRS can identify mitochondrial dysfunction in the midbrain/sub- stantia nigra of individual PD patients and correlates with trial-relevant clinical aspects of PD.

Methods

31P-MRS spectra were obtained from 35 sPD patients and 25 healthy, age-matched controls. Spectra were analysed using the jMRUI software package and AMARES spectral fitting algorithm. Clinical assessment included widely utilised clinical rating scales, genetic analysis and the calculation of predicted risk of rapid disease progression.

Results

There was a significantly broader variance in 31P-MRS midbrain ATP with 1/3 of all PD patients having ATP levels > 2 standard deviations outside the mean control values (p=0.0030). Higher midbrain phosphocreatine was associated with greater risk of rapid disease progression (p= 0.0384).

Conclusions

31P-MRS may help to identify a subgroup of sPD with significant mitochondrial dysfunction or at higher risk of more rapid progression and facilitate stratification for future precision medicine neu- roprotective trials. Longitudinal studies are required to characterise if changes 31P-MRS measures mirror clinical progression.

COVID-19 vaccination hesitancy among people with chronic neurological disorders: a position paper

Background and purpose

Health risks associated with SARS‐CoV‐2 infection are undisputed. Moreover, the capability of vaccination to prevent symptomatic, severe, and fatal COVID‐19 is recognized. There is also early evidence that vaccination can reduce the chance for long COVID‐19. Nonetheless, the willingness to get vaccinated and receive booster shots remains subpar among people with neurologic disorders. Vaccine scepticism not only jeopardizes collective efforts to end the COVID‐19 pandemic but puts individual lives at risk, as some chronic neurologic diseases are associated with a higher risk for an unfavorable COVID‐19 course.

Methods

In this position paper, the NeuroCOVID‐19 Task Force of the European Academy of Neurology (EAN) summarizes the current knowledge on the prognosis of COVID‐19 among patients with neurologic disease, elucidates potential barriers to vaccination coverage, and formulates strategies to overcome vaccination hesitancy. A survey among the Task Force members on the phenomenon of vaccination hesitancy among people with neurologic disease supports the lines of argumentation.

Results

The study revealed that people with multiple sclerosis and other nervous system autoimmune disorders are most skeptical of SARS‐CoV‐2 vaccination. The prevailing concerns included the chance of worsening the pre‐existing neurological condition, vaccination‐related adverse events, and drug interaction.

Conclusions

The EAN NeuroCOVID‐19 Task Force reinforces the key role of neurologists as advocates of COVID‐19 vaccination. Neurologists need to argue in the interest of their patients about the overwhelming individual and global benefits of COVID‐19 vaccination. Moreover, they need to keep on eye on this vulnerable patient group, its concerns, and the emergence of potential safety signals.

OUP accepted manuscript

The routine clinical integration of individualized objective markers of disease activity in those diagnosed with the neurodegenerative disorder amyotrophic lateral sclerosis is a key requirement for therapeutic development. A large, multicentre, clinic-based, longitudinal cohort was used to systematically appraise the leading candidate biofluid biomarkers in the stratification and potential therapeutic assessment of those with amyotrophic lateral sclerosis. Incident patients diagnosed with amyotrophic lateral sclerosis (n = 258), other neurological diseases (n = 80) and healthy control participants (n = 101), were recruited and followed at intervals of 3–6 months for up to 30 months. Cerebrospinal fluid neurofilament light chain and chitotriosidase 1 and blood neurofilament light chain, creatine kinase, ferritin, complement C3 and C4 and C-reactive protein were measured. Blood neurofilament light chain, creatine kinase, serum ferritin, C3 and cerebrospinal fluid neurofilament light chain and chitotriosidase 1 were all significantly elevated in amyotrophic lateral sclerosis patients. First-visit plasma neurofilament light chain level was additionally strongly associated with survival (hazard ratio for one standard deviation increase in log₁₀ plasma neurofilament light chain 2.99, 95% confidence interval 1.65–5.41, P = 0.016) and rate of disability progression, independent of other prognostic factors. A small increase in level was noted within the first 12 months after reported symptom onset (slope 0.031 log₁₀ units per month, 95% confidence interval 0.012–0.049, P = 0.006). Modelling the inclusion of plasma neurofilament light chain as a therapeutic trial outcome measure demonstrated that a significant reduction in sample size and earlier detection of disease-slowing is possible, compared with using the revised Amyotrophic Lateral Sclerosis Functional Rating Scale. This study provides strong evidence that blood neurofilament light chain levels outperform conventional measures of disease activity at the group level. The application of blood neurofilament light chain has the potential to radically reduce the duration and cost of therapeutic trials. It might also offer a first step towards the goal of more personalized objective disease activity monitoring for those living with amyotrophic lateral sclerosis.

A plea for equitable global access to COVID-19 diagnostics, vaccination and therapy: The NeuroCOVID-19 Task Force of the European Academy of Neurology

Coronavirus disease 2019 (COVID-19), a multi-organ disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues to challenge health and care systems around the globe. The pandemic has disrupted acute neurology services and routine patient care and has impacted the clinical course in patients with chronic neurological disease. COVID-19 appears to have exposed inequalities of societies and healthcare systems and had a disproportionate impact on already vulnerable communities. The next challenge will be to set up initiatives to stop disparities in all aspects related to COVID-19. From the medical perspective, there is a need to consider inequalities in prevention, treatment and long-term consequences. Some of the issues of direct relevance to neurologists are summarised. With this appraisal, the European Academy of Neurology NeuroCOVID-19 Task Force intends to raise awareness of the potential impact of COVID-19 on inequalities in healthcare and calls for action to prevent disparity at individual, national and supranational levels.

Reinnervation as measured by the motor unit size index is associated with preservation of muscle strength in amyotrophic lateral sclerosis, but not all muscles reinnervate

INTRODUCTION/AIMS

The motor unit size index (MUSIX) may provide insight into reinnervation patterns in diseases such as amyotrophic lateral sclerosis (ALS). However, it is not known whether MUSIX detects clinically relevant changes in reinnervation, or if all muscles manifest changes in MUSIX in response to reinnervation after motor unit loss.

METHODS

Fifty-seven patients with ALS were assessed at 3-month intervals for 12 months in four centers. Muscles examined were abductor pollicis brevis, abductor digiti minimi, biceps brachii, and tibialis anterior. Results were split into two groups: muscles with increases in MUSIX and those without increases. Longitudinal changes in MUSIX, motor unit number index (MUNIX), compound muscle action potential amplitude, and Medical Research Council strength score were investigated.

RESULTS

One hundred thirty-three muscles were examined. Fifty-nine percent of the muscles exhibited an increase in MUSIX during the study. Muscles with MUSIX increases lost more motor units (58% decline in MUNIX at 12 months, P < .001) than muscles that did not increase MUSIX (34.6% decline in MUNIX at 12 months, P < .001). However, longitudinal changes in muscle strength were similar. When motor unit loss was similar, the absence of a MUSIX increase was associated with a significantly greater loss of muscle strength (P = .002).

DISCUSSION

MUSIX increases are associated with greater motor unit loss but relative preservation of muscle strength. Thus, MUSIX appears to be measuring a clinically relevant response that can provide a quantitative outcome measure of reinnervation in clinical trials. Furthermore, MUSIX suggests that reinnervation may play a major role in determining the progression of weakness.

Assessment of the Precision in Measuring Glutathione at 3 T With a MEGA-PRESS Sequence in Primary Motor Cortex and Occipital Cortex

BACKGROUND

Glutathione (GSH) is an important brain antioxidant and a number of studies have reported its measurement by edited and nonedited localized ¹ H spectroscopy techniques within a range of applications in healthy volunteers and disease states. Good test-retest reproducibility is key when assessing the efficacy of treatments aimed at modulating GSH levels within the central nervous system or when noninvasively assessing changes in GSH content over time.

PURPOSE

To evaluate the intraday (in vitro and in vivo) and 1-month apart (in vivo) test-retest reproducibility of GSH measurements from GSH-edited MEGA-PRESS acquisitions at 3 T in a phantom and in the brain of a cohort of middle-aged and older healthy volunteers.

STUDY TYPE

Prospective.

SUBJECTS/PHANTOMS

A phantom containing physiological concentrations of GSH and metabolites with overlapping spectral signatures and 10 healthy volunteers (4 F, 6 M, 55 ± 14 years old).

FIELD STRENGTH/SEQUENCE

GSH-edited spectra were acquired at 3 T using the MEGA-PRESS sequence.

ASSESSMENT

The phantom was scanned twice and the healthy subjects were scanned three times (on two separate days, 1 month apart). GSH was quantified from each acquisition, with the in vivo voxels placed at the primary motor cortex (PMC) and the occipital cortex (OCC).

STATISTICAL TESTS

Mean coefficients of variation (CV) were used to assess short-term (in vitro and in vivo) and longer-term (in vivo) test-retest reproducibility.

RESULTS

In vitro, the CV was 2.3%. In vivo, the mean intraday CV was 3.3% in the PMC and 2.4% in the OCC, while the CVs at 1 month apart were 4.6% in the PMC and 7.8% in the OCC.

DATA CONCLUSION

GSH-edited MEGA-PRESS spectroscopy allows measurement of GSH with excellent precision.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 2.

Value of systematic genetic screening of patients with amyotrophic lateral sclerosis

OBJECTIVE

The clinical utility of routine genetic sequencing in amyotrophic lateral sclerosis (ALS) is uncertain. Our aim was to determine whether routine targeted sequencing of 44 ALS-relevant genes would have a significant impact on disease subclassification and clinical care.

METHODS

We performed targeted sequencing of a 44-gene panel in a prospective case series of 100 patients with ALS recruited consecutively from the Sheffield Motor Neuron Disorders Clinic, UK. All participants were diagnosed with ALS by a specialist Consultant Neurologist. 7/100 patients had familial ALS, but the majority were apparently sporadic cases.

RESULTS

21% of patients with ALS carried a confirmed pathogenic or likely pathogenic mutation, of whom 93% had no family history of ALS. 15% met the inclusion criteria for a current ALS genetic-therapy trial. 5/21 patients with a pathogenic mutation had an additional variant of uncertain significance (VUS). An additional 21% of patients with ALS carried a VUS in an ALS-associated gene. Overall, 13% of patients carried more than one genetic variant (pathogenic or VUS). Patients with ALS carrying two variants developed disease at a significantly earlier age compared with patients with a single variant (median age of onset=56 vs 60 years, p=0.0074).

CONCLUSIONS

Routine screening for ALS-associated pathogenic mutations in a specialised ALS referral clinic will impact clinical care in 21% of cases. An additional 21% of patients have variants in the ALS gene panel currently of unconfirmed significance after removing non-specific or predicted benign variants. Overall, variants within known ALS-linked genes are of potential clinical importance in 42% of patients.

Magnetic resonance spectroscopy reveals mitochondrial dysfunction in amyotrophic lateral sclerosis

Mitochondrial dysfunction is postulated to be central to amyotrophic lateral sclerosis (ALS) pathophysiology. Evidence comes primarily from disease models and conclusive data to support bioenergetic dysfunction in vivo in patients is currently lacking. This study is the first to assess mitochondrial dysfunction in brain and muscle in individuals living with ALS using 31P-magnetic resonance spectroscopy (MRS), the modality of choice to assess energy metabolism in vivo. We recruited 20 patients and 10 healthy age and gender-matched control subjects in this cross-sectional clinico-radiological study. 31P-MRS was acquired from cerebral motor regions and from tibialis anterior during rest and exercise. Bioenergetic parameter estimates were derived including: ATP, phosphocreatine, inorganic phosphate, adenosine diphosphate, Gibbs free energy of ATP hydrolysis (ΔGATP), phosphomonoesters, phosphodiesters, pH, free magnesium concentration, and muscle dynamic recovery constants. Linear regression was used to test for associations between brain data and clinical parameters (revised amyotrophic functional rating scale, slow vital capacity, and upper motor neuron score) and between muscle data and clinico-neurophysiological measures (motor unit number and size indices, force of contraction, and speed of walking). Evidence for primary dysfunction of mitochondrial oxidative phosphorylation was detected in the brainstem where ΔGATP and phosphocreatine were reduced. Alterations were also detected in skeletal muscle in patients where resting inorganic phosphate, pH, and phosphomonoesters were increased, whereas resting ΔGATP, magnesium, and dynamic phosphocreatine to inorganic phosphate recovery were decreased. Phosphocreatine in brainstem correlated with respiratory dysfunction and disability; in muscle, energy metabolites correlated with motor unit number index, muscle power, and speed of walking. This study provides in vivo evidence for bioenergetic dysfunction in ALS in brain and skeletal muscle, which appears clinically and electrophysiologically relevant. 31P-MRS represents a promising technique to assess the pathophysiology of mitochondrial function in vivo in ALS and a potential tool for future clinical trials targeting bioenergetic dysfunction.

Simultaneous ALS and SCA2 associated with an intermediate-length ATXN2 CAG-repeat expansion

Spinocerebellar ataxia type 2 (SCA2) and amyotrophic lateral sclerosis (ALS) share a common molecular basis: both are associated with CAG-repeat expansion of ATXN2 and TDP-43-positive neuronal cytoplasmic inclusions. To date, the two disorders are viewed as clinically distinct with ALS resulting from 30-33 CAG-repeats and SCA2 from >34 CAG-repeats. We describe a 67-year old with a 32 CAG-repeat expansion of ATXN2 who presented with simultaneous symptoms of ALS and SCA2. Our case demonstrates that the clinical dichotomy between SCA2 and ATXN2-ALS is false. We suggest instead that CAG-repeat expansion length determines the timing of SCA2 clinical symptoms relative to onset of ALS; consistent with this age of onset of SCA2 but not ATXN2-ALS, is dependent upon expansion length. Review of the literature and our local cohort provides evidence for occurrence of ALS in late stage SCA2, which may be under-recognised by clinicians who think of the two diseases as distinct.

The international European Academy of Neurology survey on neurological symptoms in patients with COVID-19 infection

Background and purpose

Although the main clinical features of COVID‐19 infection are pulmonary, several associated neurological signs, symptoms and diseases are emerging. The incidence and characteristics of neurological complications are unclear. For this reason, the European Academy of Neurology (EAN) core COVID‐19 Task Force initiated a survey on neurological symptoms observed in patients with COVID‐19 infection.

Methods

A 17‐question online survey was made available on the EAN website and distributed to EAN members and other worldwide physicians starting on 9 April 2020.

Results

By 27 April 2020, proper data were collected from 2343 responders (out of 4199), of whom 82.0% were neurologists, mostly from Europe. Most responders (74.7%) consulted patients with COVID‐19 mainly in emergency rooms and in COVID‐19 units. The majority (67.0%) had evaluated fewer than 10 patients with neurological manifestations of COVID‐19 (neuro COVID‐19). The most frequently reported neurological findings were headache (61.9%), myalgia (50.4%), anosmia (49.2%), ageusia (39.8%), impaired consciousness (29.3%) and psychomotor agitation (26.7%). Encephalopathy and acute cerebrovascular disorders were reported at 21.0%. Neurological manifestations were generally interpreted as being possibly related to COVID‐19; they were most commonly recognized in patients with multiple general symptoms and occurred at any time during infection.

Conclusion

Neurologists are currently and actively involved in the management of neurological issues related to the COVID‐19 pandemic. This survey justifies setting up a prospective registry to better capture the prevalence of patients with neuro COVID‐19, neurological disease characteristics and the contribution of neurological manifestations to outcome.

Nontargeted mass-spectral detection of chloroperfluoropolyether carboxylates in New Jersey soils

The toxicity and environmental persistence of anthropogenic per- and poly-fluoroalkyl substances (PFAS) are of global concern. To address legacy PFAS concerns in the United States, industry developed numerous replacement PFAS that commonly are treated as confidential information. To investigate the distribution of PFAS in New Jersey, soils collected from across the state were subjected to nontargeted mass-spectral analyses. Ten chloroperfluoropolyether carboxylates were tentatively identified, with at least three congeners in all samples. Nine congeners are ≥(CF₂)₇ Distinct chemical formulas and structures, as well as geographic distribution, suggest airborne transport from an industrial source. Lighter congeners dispersed more widely than heavier congeners, with the most widely dispersed detected in an in-stock New Hampshire sample. Additional data were used to develop a legacy-PFAS fingerprint for historical PFAS sources in New Jersey.

Limb girdle muscular dystrophy: a case report initially presenting to an outpatient musculoskeletal physiotherapy clinic with spinal pain and functional weakness

Background

The term limb girdle muscular dystrophy (LGMD) describes a group of genetic muscular disorders that require specialist input from neurologically trained clinicians. The plethora of potential symptoms of this heterogenous group can result in patients presenting initially to musculoskeletal (MSK) physiotherapists.

Case presentation

The following case report highlights the presentation of a 21 year old female attending with 2 years of spinal pain and an unusual pattern of weakness, namely when rising from a sitting position the hips were abducted and then internally rotated. Formal testing in clinic revealed no isolated weakness initially despite the odd functional movements. There were no neural limb pains and no upper or lower motor neuron concerns on testing. There were no other health concerns. Some gains were reported with recent physiotherapy strengthening exercises and these were persisted with but proved ineffective overall. The Biopsychosocial model was used judiciously to explore alternative pathologies and led to appropriate investigations, onward referral, diagnosis and appropriate management of LGMD. Extensive atrophy of the spinal muscles was evident on imaging which was not particularly identified within the physiotherapy testing process in the earlier stages. Creatine kinase levels were also significantly raised.

Conclusions

Being mindful of this novel presentation in musculoskeletal clinics may well aid future, similar cases to be identified. The case highlights the importance of looking at the functional impact as opposed to traditional testing methods especially in the early stages of such conditions.

Longitudinal multi-modal muscle-based biomarker assessment in motor neuron disease

Background

Clinical phenotypic heterogeneity represents a major barrier to trials in motor neuron disease (MND) and objective surrogate outcome measures are required, especially for slowly progressive patients. We assessed responsiveness of clinical, electrophysiological and radiological muscle-based assessments to detect MND-related progression.

Materials and methods

A prospective, longitudinal cohort study of 29 MND patients and 22 healthy controls was performed. Clinical measures, electrophysiological motor unit number index/size (MUNIX/MUSIX) and relative T2- and diffusion-weighted whole-body muscle magnetic resonance (MR) were assessed three times over 12 months. Multi-variable regression models assessed between-group differences, clinico-electrophysiological associations, and longitudinal changes. Standardized response means (SRMs) assessed sensitivity to change over 12 months.

Results

MND patients exhibited 18% higher whole-body mean muscle relative T2-signal than controls (95% CI 7–29%, p < 0.01), maximal in leg muscles (left tibialis anterior 71% (95% CI 33–122%, p < 0.01). Clinical and electrophysiological associations were evident. By 12 months, 16 patients had died or could not continue. In the remainder, relative T2-signal increased over 12 months by 14–29% in right tibialis anterior, right quadriceps, bilateral hamstrings and gastrocnemius/soleus (p < 0.01), independent of onset-site, and paralleled progressive weakness and electrophysiological loss of motor units. Highest clinical, electrophysiological and radiological SRMs were found for revised ALS-functional rating scale scores (1.22), tibialis anterior MUNIX (1.59), and relative T2-weighted leg muscle MR (right hamstrings: 0.98), respectively. Diffusion MR detected minimal changes.

Conclusion

MUNIX and relative T2-weighted MR represent objective surrogate markers of progressive denervation in MND. Radiological changes were maximal in leg muscles, irrespective of clinical onset-site.

Electronic supplementary material

The online version of this article (10.1007/s00415-019-09580-x) contains supplementary material, which is available to authorized users.

Use of carbon isotopic ratios in nontargeted analysis to screen for anthropogenic compounds in complex environmental matrices

Analytical data for ultra-high-performance liquid chromatography (UHPLC), nontargeted, high-resolution, mass-spectrometry (HR/MS) molecular features from a wide array of samples are used to calculate ¹³C₁¹²C_(n-1)/¹²C_n isotopologue ratios. These ratios increase with molecular carbon number roughly following a trend defined by atmospheric carbon. When the effective source reservoir ¹³C/¹²C ratio is calculated from the isotopologue ratio (assuming a fractionation factor of unity), features in biotic samples uniformly are tightly grouped, proximate to atmospheric ¹³C/¹²C ratio. In contrast, features in soil natural organic matter (NOM), dust NOM and anthropogenic compounds range from proximate to relatively divergent from atmospheric ¹³C/¹²C. For the NOM, ¹³C/¹²C ratios are consistent with an expected preferential volatilization of ¹²C, rendering features in soil NOM ¹³C-enriched and some features in dust NOM ¹³C-depleted. Anthropogenic compounds tend to diverge most dramatically from atmospheric ¹³C/¹²C, generally toward ¹³C-depletion, but pesticides we tested tended toward ¹³C-enriched. This pattern is robust and evident in: i) anthropogenic vs natural features in dust; ii) perfluorinated compounds in standards and as soil contaminants; and iii) sunscreen compounds in commercial products and wastewater. Considering the observed wide ¹³C/¹²C range for anthropogenic compounds, we suggest Rayleigh distillation during synthetic processes commonly favors one isotope over the other, rendering a source reservoir that is progressively depleted as synthesis proceeds and, consequently, generates a wide variation in ¹³C/¹²C for man-made products. However, kinetic-isotopic effects and/or synthesis from petroleum/natural gas might contribute to the anthropogenic isotopic signature as well. Regardless of cause, ¹³C/¹²C can be used to cull HR/MS molecular features that are more likely to be of anthropogenic or non-biotic origin.

Structural cortical network reorganization associated with early conversion to multiple sclerosis

Brain structural covariance networks (SCNs) based on pairwise statistical associations of cortical thickness data across brain areas reflect underlying physical and functional connections between them. SCNs capture the complexity of human brain cortex structure and are disrupted in neurodegenerative conditions. However, the longitudinal assessment of SCN dynamics has not yet been explored, despite its potential to unveil mechanisms underlying neurodegeneration. Here, we evaluated the changes of SCNs over 12 months in patients with a first inflammatory-demyelinating attack of the Central Nervous System and assessed their clinical relevance by comparing SCN dynamics of patients with and without conversion to multiple sclerosis (MS) over one year. All subjects underwent clinical and brain MRI assessments over one year. Brain cortical thicknesses for each subject and time point were used to obtain group-level between-area correlation matrices from which nodal connectivity metrics were obtained. Robust bootstrap-based statistical approaches (allowing sampling with replacement) assessed the significance of longitudinal changes. Patients who converted to MS exhibited significantly greater network connectivity at baseline than non-converters (p = 0.02) and a subsequent connectivity loss over time (p = 0.001-0.02), not observed in non-converters' network. These findings suggest SCN analysis is sensitive to brain tissue changes in early MS, reflecting clinically relevant aspects of the condition. However, this is preliminary work, indicated by the low sample sizes, and its results and conclusions should be treated with caution and confirmed with larger cohorts.

Recurrent rhabdomyolysis caused by carnitine palmitoyltransferase II deficiency, common but under-recognised: Lessons to be learnt

We discuss two adult siblings who presented with symptoms of myalgia and rhabdomyolysis following exercise with myoglobinuria; genetic testing confirmed carnitine palmitoyltransferase II deficiency and resulted in institution of appropriate crisis management and dietary advice. We explore the phenotypic variability of this commonest fatty oxidation defect that remains under-diagnosed in the adult population and provide clues for early recognition and diagnosis.

•

CPT II deficiency should be considered as an important differential diagnosis in individuals presenting with recurrent or even single attacks of muscle weakness.

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If the clinical history includes ‘unexplained’ rhabdomyolysis, clinicians should have a low threshold to perform plasma acylcarnitine analysis as a first line investigation, especially in the context of elevated CK.

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Confirmatory diagnosis is by identification of disease-causing variants in CPT2 through targeted testing.

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It is important that these individuals have specialist dietary advice and annual monitoring.

Imaging muscle as a potential biomarker of denervation in motor neuron disease

OBJECTIVE

To assess clinical, electrophysiological and whole-body muscle MRI measurements of progression in patients with motor neuron disease (MND), as tools for future clinical trials, and to probe pathophysiological mechanisms in vivo.

METHODS

A prospective, longitudinal, observational, clinicoelectrophysiological and radiological cohort study was performed. Twenty-nine patients with MND and 22 age-matched and gender-matched healthy controls were assessed with clinical measures, electrophysiological motor unit number index (MUNIX) and T2-weighted whole-body muscle MRI, at first clinical presentation and 4 months later. Between-group differences and associations were assessed using age-adjusted and gender-adjusted multivariable regression models. Within-subject longitudinal changes were assessed using paired t-tests. Patterns of disease spread were modelled using mixed-effects multivariable regression, assessing associations between muscle relative T2 signal and anatomical adjacency to site of clinical onset.

RESULTS

Patients with MND had 30% higher relative T2 muscle signal than controls at baseline (all regions mean, 95% CI 15% to 45%, p<0.001). Higher T2 signal was associated with greater overall disability (coefficient -0.009, 95% CI -0.017 to -0.001, p=0.023) and with clinical weakness and lower MUNIX in multiple individual muscles. Relative T2 signal in bilateral tibialis anterior increased over 4 months in patients with MND (right: 10.2%, 95% CI 2.0% to 18.4%, p=0.017; left: 14.1%, 95% CI 3.4% to 24.9%, p=0.013). Anatomically, contiguous disease spread on MRI was not apparent in this model.

CONCLUSIONS

Whole-body muscle MRI offers a new approach to objective assessment of denervation over short timescales in MND and enables investigation of patterns of disease spread in vivo. Muscles inaccessible to conventional clinical and electrophysiological assessment may be investigated using this methodology.

Factors associated with long-term weight-loss maintenance following bariatric surgery in adolescents with severe obesity

BACKGROUND/OBJECTIVES

Bariatric surgery produces robust weight loss, however, factors associated with long-term weight-loss maintenance among adolescents undergoing Roux-en-Y gastric bypass surgery are unknown.

SUBJECTS/METHODS

Fifty adolescents (mean±s.d. age and body mass index (BMI)=17.1±1.7 years and 59±11 kg m^-2) underwent Roux-en-Y gastric bypass surgery, had follow-up visits at 1 year and at a visit between 5 and 12 years following surgery (Follow-up of Adolescent Bariatric Surgery at 5 Plus years (FABS-5+) visit; mean±s.d. 8.1±1.6 years). A non-surgical comparison group (n=30; mean±s.d. age and BMI=15.3±1.7 years and BMI=52±8 kg m^-2) was recruited to compare weight trajectories over time. Questionnaires (health-related and eating behaviors, health responsibility, impact of weight on quality of life (QOL), international physical activity questionnaire and dietary habits via surgery guidelines) were administered at the FABS-5+ visit. Post hoc, participants were split into two groups: long-term weight-loss maintainers (n=23; baseline BMI=58.2 kg m^-2; 1-year BMI=35.8 kg m^-2; FABS-5+ BMI=34.9 kg m^-2) and re-gainers (n=27; baseline BMI=59.8 kg m^-2; 1-year BMI=36.8 kg m^-2; FABS-5+ BMI=48.0 kg m^-2) to compare factors which might contribute to differences. Data were analyzed using generalized estimating equations adjusted for age, sex, baseline BMI, baseline diabetes status and length of follow-up.

RESULTS

The BMI of the surgical group declined from baseline to 1 year (-38.5±6.9%), which, despite some regain, was largely maintained until FABS-5+ (-29.6±13.9% change). The BMI of the comparison group increased from baseline to the FABS-5+ visit (+10.3±20.6%). When the surgical group was split into maintainers and re-gainers, no differences in weight-related and eating behaviors, health responsibility, physical activity/inactivity, or dietary habits were observed between groups. However, at FABS-5+, maintainers had greater overall QOL scores than re-gainers (87.5±10.5 vs 65.4±20.2, P<0.001) and in each QOL sub-domain (P<0.01 all).

CONCLUSIONS

Long-term weight outcomes for those who underwent weight-loss surgery were superior to those who did not undergo surgical treatment. While no behavioral factors were identified as predictors of success in long-term weight-loss maintenance, greater QOL was strongly associated with maintenance of weight loss among adolescents who underwent Roux-en-Y gastric bypass surgery surgery.

A North American and global survey of perfluoroalkyl substances in surface soils: Distribution patterns and mode of occurrence

The distribution of 32 per/polyfluoroalkyl substances (PFASs) in surface soils was determined at 62 locations representing all continents (North America n = 33, Europe n = 10, Asia n = 6, Africa n = 5, Australia n = 4, South America n = 3 and Antarctica n = 1) using ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) systems. Quantifiable levels of perfluoroalkyl carboxylates (PFCAs: PFHxA-PFTeDA) were observed in all samples with total concentrations ranging from 29 to 14,300 pg/g (dry weight), while perfluoroalkane sulfonates (PFSAs: PFHxS, PFOS and PFDS) were detected in all samples but one, ranging from <LOQ-3270 pg/g, confirming the global distribution of PFASs in terrestrial settings. The geometric mean PFCA and PFSA concentrations were observed to be higher in the northern hemisphere (930 and 170 pg/g) compared to the southern hemisphere (190 and 33 pg/g). Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) were the most commonly detected analytes at concentrations up to 2670 and 3100 pg/g, respectively. The sum of PFCA homologues of PFOA commonly were roughly twice the concentration of PFOA. The PFCA and PFSA congener profiles were similar amongst most locations, with a few principal-component statistical anomalies suggesting impact from nearby urban and point sources. The ratio of even to odd PFCAs was consistent with the atmospheric oxidation of fluorotelomer-based precursors previously observed in laboratory and environmental studies. Given the soils were collected from locations absent of direct human activity, these results suggest that the atmospheric long-range transport (LRT) of neutral PFASs followed by oxidation and deposition are a significant source of PFCAs and PFSAs to soils.

Polyfluorinated substances in abiotic standard reference materials

The National Institute of Standards and Technology (NIST) has a wide range of Standard Reference Materials (SRMs) which have values assigned for legacy organic pollutants and toxic elements. Existing SRMs serve as homogenous materials that can be used for method development, method validation, and measurement for contaminants that are now of concern. NIST and multiple groups have been measuring the mass fraction of a group of emerging contaminants, polyfluorinated substances (PFASs), in a variety of SRMs. Here we report levels determined in an interlaboratory comparison of up to 23 PFASs determined in five SRMs: sediment (SRMs 1941b and 1944), house dust (SRM 2585), soil (SRM 2586), and sludge (SRM 2781). Measurements presented show an array of PFASs, with perfluorooctane sulfonate being the most frequently detected. SRMs 1941b, 1944, and 2586 had relatively low concentrations of most PFASs measured while 23 PFASs were at detectable levels in SRM 2585 and most of the PFASs measured were at detectable levels in SRM 2781. The measurements made in this study were used to add values to the Certificates of Analysis for SRMs 2585 and 2781.

Longitudinal evidence for anterograde trans-synaptic degeneration after optic neuritis

In multiple sclerosis, microstructural damage of normal-appearing brain tissue is an important feature of its pathology. Understanding these mechanisms is vital to help develop neuroprotective strategies. The visual pathway is a key model to study mechanisms of damage and recovery in demyelination. Anterograde trans-synaptic degeneration across the lateral geniculate nuclei has been suggested as a mechanism of tissue damage to explain optic radiation abnormalities seen in association with demyelinating disease and optic neuritis, although evidence for this has relied solely on cross-sectional studies. We therefore aimed to assess: (i) longitudinal changes in the diffusion properties of optic radiations after optic neuritis suggesting trans-synaptic degeneration; (ii) the predictive value of early optic nerve magnetic resonance imaging measures for late optic radiations changes; and (iii) the impact on visual outcome of both optic nerve and brain post-optic neuritis changes. Twenty-eight consecutive patients with acute optic neuritis and eight healthy controls were assessed visually (logMAR, colour vision, and Sloan 1.25%, 5%, 25%) and by magnetic resonance imaging, at baseline, 3, 6, and 12 months. Magnetic resonance imaging sequences performed (and metrics obtained) were: (i) optic nerve fluid-attenuated inversion-recovery (optic nerve cross-sectional area); (ii) optic nerve proton density fast spin-echo (optic nerve proton density-lesion length); (iii) optic nerve post-gadolinium T1-weighted (Gd-enhanced lesion length); and (iv) brain diffusion-weighted imaging (to derive optic radiation fractional anisotropy, radial diffusivity, and axial diffusivity). Mixed-effects and multivariate regression models were performed, adjusting for age, gender, and optic radiation lesion load. These identified changes over time and associations between early optic nerve measures and 1-year global optic radiation/clinical measures. The fractional anisotropy in patients' optic radiations decreased (P = 0.018) and radial diffusivity increased (P = 0.002) over 1 year following optic neuritis, whereas optic radiation measures were unchanged in controls. Also, smaller cross-sectional areas of affected optic nerves at 3 months post-optic neuritis predicted lower fractional anisotropy and higher radial diffusivity at 1 year (P = 0.007) in the optic radiations, whereas none of the inflammatory measures of the optic nerve predicted changes in optic radiations. Finally, greater Gd-enhanced lesion length at baseline and greater optic nerve proton density-lesion length at 1 year were associated with worse visual function at 1 year (P = 0.034 for both). Neither the cross-sectional area of the affected optic nerve after optic neuritis nor the damage in optic radiations was associated with 1-year visual outcome. Our longitudinal study shows that, after optic neuritis, there is progressive damage to the optic radiations, greater in patients with early residual optic nerve atrophy, even after adjusting for optic radiation lesions. These findings provide evidence for trans-synaptic degeneration.

Abiotic Hydrolysis of Fluorotelomer-Based Polymers as a Source of Perfluorocarboxylates at the Global Scale

Fluorotelomer-based polymers (FTPs) are the main product of the fluorotelomer industry. For nearly 10 years, whether FTPs degrade to form perfluorooctanoate (PFOA) and perfluorocarboxylate (PFCA) homologues has been vigorously contested. Here we show that circum-neutral abiotic hydrolysis of a commercial FTP proceeds with half-life estimates of 55-89 years and that base-mediated hydrolysis overtakes neutral hydrolysis at about pH = 10, with a half-life of ~0.7 years at pH ∼ 12. Considered in light of the large production volume of FTPs and the poor efficacy of conventional treatments for recovery of PFCAs from waste streams, these results suggest that FTPs manufactured to date potentially could increase PFCAs 4- to 8-fold over current oceanic loads, largely depending on the integrity of disposal units to contain PFCAs upon hydrolytic generation from FTPs.

Identification of Unsaturated and 2H Polyfluorocarboxylate Homologous Series and Their Detection in Environmental Samples and as Polymer Degradation Products

A pair of homologous series of polyfluorinated degradation products have been identified, both having structures similar to perfluorocarboxylic acids but (i) having a H substitution for F on the α carbon for 2H polyfluorocarboxylic acids (2HPFCAs) and (ii) bearing a double bond between the α-β carbons for the unsaturated PFCAs (2uPFCAs). Obtaining an authentic sample containing 2uPFOA and 2HPFOA, we optimized a mass-spectrometric multiple-reaction-monitoring (MS/MS) technique and then identified uPFCA and HPFCA homologous series in sludge-applied agricultural soils and fodder grasses for cattle grazing. Analysis of samples from a degradation experiment of commercial fluorotelomer-based polymers (FTPs), the dominant product of the fluorotelomer industry, confirmed that commercial FTPs are a potential source of uPFCAs and HPFCAs to the environment. We further confirmed the identity of the uPFCAs by imposing high-energy ionization to decarboxylate the uPFCAs then focused on the fluorinated chains in the first MS quadrupole. We also employed this high-energy ionization to decarboxylate and analyze PFCAs by MS/MS (for the first time, to our knowledge). In exploratory efforts, we report the possible detection of unsaturated perfluorooctanesulfonate in environmental samples, having a conceptual double-bond structure analogous to uPFOA. Using microcosms spiked with fluorotelomer compounds, we found 2uPFOA and 2HPFOA to be generated from unsaturated 8:2 fluorotelomer acid (8:2 FTUCA) and propose β- and α-oxidation mechanisms for generation of these compounds from 8:2 FTUCA. In light of these experimental results, we also reexamined the proposed biodegradation pathways of 8:2 fluorotelomer alcohol.

Decades-scale degradation of commercial, side-chain, fluorotelomer-based polymers in soils and water

Fluorotelomer-based polymers (FTPs) are the primary product of the fluorotelomer industry. Here we report on a 376-day study of the degradability of two commercial acrylate-linked FTPs in four saturated soils and in water. Using an exhaustive serial extraction, we report GC/MS and LC/MS/MS results for 50 species including fluorotelomer alcohols and acids, and perfluorocarboxylates. Modeling of seven sampling rounds, each consisting of ≥5 replicate microcosm treatments, for one commercial FTP in one soil yielded half-life estimates of 65–112 years and, when the other commercial FTP and soils were evaluated, the estimated half-lives ranged from 33 to 112 years. Experimental controls, consisting of commercial FTP in water, degraded roughly at the same rate as in soil. A follow-up experiment, with commercial FTP in pH 10 water, degraded roughly 10-fold faster than the circum-neutral control suggesting that commercial FTPs can undergo OH–-mediated hydrolysis. 8:2Fluorotelomer alcohol generated from FTP degradation in soil was more stable than without FTP present suggesting a clathrate guest–host association with the FTP. To our knowledge, these are the only degradability-test results for commercial FTPs that have been generated using exhaustive extraction procedures. They unambiguously show that commercial FTPs, the primary product of the fluorotelomer industry, are a source of fluorotelomer and perfluorinated compounds to the environment.

Characterizing fluorotelomer and polyfluoroalkyl substances in new and aged fluorotelomer-based polymers for degradation studies with GC/MS and LC/MS/MS

Fluorotelomer-based polymers (FTPs), the dominant product of the fluorotelomer industry, are antistaining and antiwetting agents that permeate the products and surfaces of modern society. However, the degree to which these materials expose humans and the environment to fluorotelomer and perfluorinated compounds, including recalcitrant and toxic compounds such as perfluorooctanoic acid (PFOA), is ill-defined. The design intent of FTPs, to minimize interaction with other substances, including solvents, heretofore has stymied efforts to develop robust methods to characterize the content of monomers and associated compounds of new commercial FTPs, as well as commercial FTPs that have been aged in environmental media for degradation testing. Here we show that FTPs can be exhausted of these compounds and quantitated by (i) drying the FTP on a suitable substrate at elevated temperature to achieve low, constant monomer concentrations; (ii) serial extraction with MTBE for fluorotelomer-monomer analysis by GC/MS in PCI mode; followed by (iii) serial extraction with 90/10 ACN/H2O for polyfluorocompound analysis by LC/MS/MS in negative ESI mode. This approach yields exhaustive, internally consistent accounting of monomers and associated compounds for FTPs, either alone or in a soil matrix (representing an environmental medium), for both new and simulated-aged FTPs to allow degradation testing, and for fluorinated compounds at least as long as C12.

Influence of gestational age and body weight on the pharmacokinetics of labetalol in pregnancy

BACKGROUND AND OBJECTIVES

Labetalol is frequently prescribed for the treatment of hypertension during pregnancy; however, the influence of pregnancy on labetalol pharmacokinetics is uncertain, with inconsistent findings reported by previous studies. This study examined the population pharmacokinetics of oral labetalol during and after pregnancy in women receiving labetalol for hypertension.

METHODS

Data were collected from 57 women receiving the drug for hypertension from the 12th week of pregnancy through 12 weeks postpartum using a prospective, longitudinal design. A sparse sampling strategy guided collection of plasma samples. Samples were assayed for labetalol by high-performance liquid chromatography. Estimation of population pharmacokinetic parameters and covariate effects was performed by nonlinear mixed effects modeling using NONMEM. The final population model was validated by bootstrap analysis and visual predictive check. Simulations were performed with the final model to evaluate the appropriate body weight to guide labetalol dosing.

RESULTS

Lean body weight (LBW) and gestational age, i.e. weeks of pregnancy, were identified as significantly influencing oral clearance (CL/F) of labetalol, with CL/F ranging from 1.4-fold greater than postpartum values at 12 weeks' gestational age to 1.6-fold greater at 40 weeks. Doses adjusted for LBW provide more consistent drug exposure than doses adjusted for total body weight. The apparent volumes of distribution for the central compartment and at steady-state were 1.9-fold higher during pregnancy.

CONCLUSIONS

Gestational age and LBW impact the pharmacokinetics of labetalol during pregnancy and have clinical implications for adjusting labetalol doses in these women.

A prospective pilot study measuring muscle volumetric change in amyotrophic lateral sclerosis

Our objective was to investigate the potential of muscle volume, measured with magnetic resonance (MR), as a biomarker to quantify disease progression in patients with amyotrophic lateral sclerosis (ALS). In this longitudinal pilot study, we first sought to determine the stability of volumetric muscle MR measurements in 11 control subjects at two time-points. We assessed feasibility of detecting atrophy in four patients with ALS, followed at three-month intervals for 12 months. Muscle power and MR volume were measured in thenar eminence (TEm), first dorsal interosseous (1DIO), tibialis anterior (TA) and tongue. Changes over time were assessed using linear regression models and t-tests. Results demonstrated that, in controls, no volumetric MR changes were seen (mean volume variation in all muscles < 5%, p > 0.1). In patients, between-subject heterogeneity was identified. Trends for volume loss were found in TEm (mean, - 26.84%, p = 0.056) and TA (- 8.29%, p = 0.077), but not in 1DIO (- 18.47%, p = 0.121) or tongue (< 5%, p = 0.367). In conclusion, volumetric muscle MR appears a stable measure in controls, and progressive volume loss was demonstrable in individuals with ALS in whom clinical weakness progressed. In this small study, subclinical atrophy was not demonstrable using muscle MR. Clinico-radiological discordance between muscle weakness and MR atrophy could reflect a contribution of upper motor neuron pathology.

Quantitative determination of perfluorochemicals and fluorotelomer alcohols in plants from biosolid-amended fields using LC/MS/MS and GC/MS

Analytical methods for determining perfluorochemicals (PFCs) and fluorotelomer alcohols (FTOHs) in plants using liquid chromatography/tandem mass spectrometry (LC/MS/MS) and gas chromatography/mass spectrometry (GC/MS) were developed, and applied to quantify a suite of analytes in plants from biosolid-amended fields. Dichloromethane-methanol and ethylacetate were chosen as extracting solutions for PFCs and FTOHs, respectively. Nine perfluorocarboxylic acids (PFCAs), three perfluorosulfonic acids (PFSAs), and ten FTOHs were monitored. Most PFCAs and perfluorooctanesulfonate (PFOS) were quantifiable in plants grown in contaminated soils, whereas PFCs went undetected in plants from two background fields. Perfluorooctanoic acid (PFOA) was a major homologue (∼10-200 ng/g dry wt), followed by perfluorodecanoic acid (∼3-170 ng/g). [PFOS] in plants (1-20 ng/g) generally was less than or equal to most [PFCAs]. The site-specific grass/soil accumulation factor (GSAF = [PFC](Grass)/[PFC](Soil)) was calculated to assess transfer potentials from soils. Perfluorohexanoic acid had the highest GSAF (= 3.8), but the GSAF decreased considerably with increasing PFCA chain length. Log-transformed GSAF was significantly correlated with the PFCA carbon-length (p < 0.05). Of the measured alcohols, 8:2nFTOH was the dominant species (≤1.5 ng/g), but generally was present at ≥10× lower concentrations than PFOA.

Perfluorinated chemicals in surface waters and sediments from northwest Georgia, USA, and their bioaccumulation in Lumbriculus variegatus

Concentrations of perfluorinated chemicals (PFCs) were measured in surface waters and sediments from the Coosa River watershed in northwest Georgia, USA, to examine their distribution downstream of a suspected source. Samples from eight sites were analyzed using liquid chromatography-tandem mass spectrometry. Sediments were also used in 28-d exposures with the aquatic oligochaete, Lumbriculus variegatus, to assess PFC bioaccumulation. Concentrations of PFCs in surface waters and sediments increased significantly below a land-application site (LAS) of municipal/industrial wastewater and were further elevated by unknown sources downstream. Perfluorinated carboxylic acids (PFCAs) with eight or fewer carbons were the most prominent in surface waters. Those with 10 or more carbons predominated sediment and tissue samples. Perfluorooctane sulfonate (PFOS) was the major homolog in contaminated sediments and tissues. This pattern among sediment PFC concentrations was consistent among sites and reflected homolog concentrations emanating from the LAS. Concentrations of PFCs in oligochaete tissues revealed patterns similar to those observed in the respective sediments. The tendency to bioaccumulate increased with PFCA chain length and the presence of the sulfonate moiety. Biota-sediment accumulation factors indicated that short-chain PFCAs with fewer than seven carbons may be environmentally benign alternatives in aquatic ecosystems; however, sulfonates with four to seven carbons may be as likely to bioaccumulate as PFOS.

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

BACKGROUND

Previous work showed that pericalcarine cortical volume loss is evident early after presentation with acute clinically isolated optic neuritis (ON). The aims of this study were: (1) to determine whether pericalcarine atrophy in patients with ON is associated with conversion to multiple sclerosis (MS); (2) to investigate whether regional atrophy preferentially affects pericalcarine cortex; and (3) to investigate potential causes of early pericalcarine atrophy using MRI.

METHODS

28 patients with acute ON and 10 controls underwent structural MRI (brain and optic nerves) and were followed-up over 12 months. Associations between the development of MS, optic nerve, optic radiation and pericalcarine cortical damage measures were investigated using multiple linear regression models. Regional cortical volumetric differences between patients and controls were calculated using t tests.

RESULTS

The development of MS at 12 months was associated with greater whole brain and optic radiation lesion loads, shorter acute optic nerve lesions and smaller pericalcarine cortical volume at baseline. Regional atrophy was not evident in other sampled cortical regions. Pericalcarine atrophy was not directly associated with whole brain lesion load, optic radiation measures or optic nerve lesion length. However, the association between pericalcarine atrophy and MS was not independent of these parameters.

CONCLUSIONS

Reduced pericalcarine cortical volumes in patients with early clinically isolated ON were associated with the development of MS but volumes of other cortical regions were not. Hence pericalcarine cortical regions appear particularly susceptible to early damage. These findings could be explained by a combination of pathological effects to visual grey and white matter in patients with ON.

A longitudinal functional MRI study of non-arteritic anterior ischaemic optic neuropathy patients

BACKGROUND

Non-arteritic anterior ischaemic optic neuropathy (NA-AION) can cause disabling visual loss and traditionally, visual prognosis has been considered poor, although recent studies have demonstrated improvements in visual acuity in about 30% of patients over time. The aim of the study was to determine whether there was significant cortical reorganisation with functional MRI (fMRI) after acute NA-AION by comparing affected individuals with healthy controls.

METHODS

9 patients with NA-AION were studied acutely and then after 1, 2, 3 and 6&emsp14;months. 23 healthy volunteers underwent scanning at least twice. At each time point, patients were assessed clinically and with fMRI. For the fMRI experiments, subjects underwent monocular visual stimulation (wearing goggles with flashing LED displays).

RESULTS

When stimulating the affected eye, occipital activation was reduced in patients compared with controls. Also, within the NA-AION group, activation in the right Brodmann areas (BA) 44 and 45 was seen during the early phase of the condition. The same areas were activated within the NA-AION group several months later for fellow eye stimulation. When the NA-AION and healthy control groups were formally compared however, these areas (BA 44/45) were not significantly different. NA-AION subjects did show greater activation in visual related areas compared with controls when stimulating the fellow eye. Visual acuity was correlated with more occipital cortex activation when stimulating the affected eye.

CONCLUSIONS

There is cortical re-organisation of the fMRI response in extra-visual areas, seen when both affected and fellow eyes are stimulated after NA-AION.

Concentrations, distribution, and persistence of perfluoroalkylates in sludge-applied soils near Decatur, Alabama, USA

Sludges generated at a wastewater treatment plant (WWTP) in Decatur, Alabama have been applied to agricultural fields for more than a decade. Waste-stream sources to this WWTP during this period included industries that work with fluorotelomer compounds, and sludges from this facility have been found to be elevated in perfluoroalkylates (PFAs). With this knowledge, the U.S. Environmental Protection Agency collected soil samples from sludge-applied fields as well as nearby "background" fields for PFA analysis. Samples from the sludge-applied fields had PFAs at much higher concentrations than in the background fields; generally the highest concentrations were perfluorodecanoic acid (≤ 990 ng/g), perfluorododecanoic acid (≤ 530 ng/g), perfluorooctanoic acid (≤ 320 ng/g), and perfluorooctane sulfonate (≤ 410 ng/g). Contrasts in PFA concentration between surface and deeper soil samples tended to be more pronounced in long-chain congeners than shorter chains, perhaps reflecting relatively lower environmental mobilities for longer chains. Several PFAs were correlated with secondary fluorotelomer alcohols (sec-FTOHs) suggesting that PFAs are being formed by degradation of sec-FTOHs. Calculated PFA disappearance half-lives for C6 through C11 alkylates ranged from about 1 to 3 years and increase with increasing chain-length, again perhaps reflecting lower mobility of the longer-chained compounds.

Concentrations, distribution, and persistence of fluorotelomer alcohols in sludge-applied soils near Decatur, Alabama, USA

Soil samples were collected for fluorotelomer alcohol (FTOH) analyses from six fields to which sludge had been applied and one "background" field that had not received sludge. Ten analytes in soil extracts were quantified using GC/MS. Sludge-applied fields had surface soil FTOH concentrations exceeding levels found in the background field. For 8:2nFTOH, which can degrade to perfluorooctanoic acid, impacted surface-soils ranged from 5 to 73 ng/g dry weight, clearly exceeding the background field in which 8:2nFTOH was not detected. The highest [FTOH] generally was 10:2nFTOH, which had concentrations of <5.6 to 166 ng/g. For the first time, we document the persistence of straight-chained primary FTOHs (n-FTOHs) and branch-chained secondary FTOHs (sec-FTOHs), which are transformation products of n-FTOHs, in field soils for at least five years after sludge application. Ratios of sec-FTOHs to n-FTOHs were highest for 7:2sFTOH/8:2nFTOH (∼50%) and decreased with increasing chain length to a minimum for the longest-chained analytes, 13:2sFTOH/14:2nFTOH (∼10%). Disappearance half-lives for FTOHs, calculated with these data, ranged from 0.85 to 1.8 years. These analytical results show that the practice of sludge application to land is a pathway for the introduction of FTOHs and, accordingly, their transformation products, perfluorocarboxylic acids, into the environment.

New developments in the treatment of optic neuritis

Acute optic neuritis (ON) has various etiologies. The most common presentation is inflammatory, demyelinating, idiopathic, or "typical" ON, which may be associated with multiple sclerosis. This must be differentiated from "atypical" causes of ON, which differ in their clinical presentation, natural history, management, and prognosis. Clinical "red flags" for an atypical cause of ON include absent or persistent pain, exudates and hemorrhages on fundoscopy, very severe, bilateral, or progressive visual loss, and failure to recover. In typical ON, steroids shorten the duration of the attack, but do not influence visual outcome. This is in contrast to atypical ON associated with conditions such as sarcoidosis and neuromyelitis optica, which require aggressive immunosuppression and sometimes plasma exchange. The visual prognosis of typical ON is generally good. The prognosis in atypical ON is more variable. New developments aimed at designing better treatments for patients who fail to recover are discussed, focusing on recent research elucidating mechanisms of damage and recovery in ON. Future therapeutic directions may include enhancing repair processes, such as remyelination or adaptive neuroplasticity, or alternative methods of immunomodulation. Pilot studies investigating the safety and proof-of-principle of stem cell treatment are currently underway.

Combining tractography and cortical measures to test system-specific hypotheses in multiple sclerosis

The objective was to test three motor system-specific hypotheses in multiple sclerosis patients: (i) corticospinal tract and primary motor cortex imaging measures differ between multiple sclerosis patients and controls; (ii) in patients, these measures correlate with disability; (iii) in patients, corticospinal tract measures correlate with measures of the ipsilateral primary motor cortex.

Eleven multiple sclerosis patients with a history of hemiparesis attributable to a lesion within the contralateral corticospinal tract, and 12 controls were studied. We used two advanced imaging techniques: (i) diffusion-based probabilistic tractography, to obtain connectivity and fractional anisotropy of the corticospinal tract; and (ii) FreeSurfer, to measure volume, thickness, surface area, and curvature of precentral and paracentral cortices. Differences in these measures between patients and controls, and relationships between each other and to clinical scores, were investigated.

Patients showed lower corticospinal tract fractional anisotropy and smaller volume and surface area of the precentral gyrus than controls. In patients, corticospinal tract connectivity and paracentral cortical volume, surface area, and curvature were lower with increasing disability; lower connectivity of the affected corticospinal tract was associated with greater surface area of the ipsilateral paracentral cortex.

Corticospinal tract connectivity and new measures of the primary motor cortex, such as surface area and curvature, reflect the underlying white and grey matter damage that contributes to disability. The correlation between lower connectivity of the affected corticospinal tract and greater surface area of the ipsilateral paracentral cortex suggests the possibility of cortical adaptation. Combining tractography and cortical measures is a useful approach in testing hypotheses which are specific to clinically relevant functional systems in multiple sclerosis, and can be applied to other neurological diseases.

Degradability of an acrylate-linked, fluorotelomer polymer in soil

Fluorotelomer polymers are used in a broad array of products in modern societies worldwide and, if they degrade at significant rates, potentially are a significant source of perfluorooctanoic acid (PFOA) and related compounds to the environment To evaluate this possibility, we incubated an acrylate-linked fluorotelomer polymer in soil microcosms and monitored the microcosms for possible fluorotelomer (FT) and perfluorinated-compound (PFC) degradation products using GC/MS and LC/MS/MS. This polymer scavenged FTs and PFCs aggressively necessitating development of a multistep extraction using two solvents. Aged microcosms accumulated more FTs and PFCs than were present in the fresh polymer indicating polymer degradation with a half-life of about 870-1400 years for our coarse-grained test polymer. Modeling indicates that more-finely grained polymers in soils might have half-lives of about 10-17 years assuming degradation is surface-mediated. In our polymer-soil microcosms, PFOA evidently was lost with a half-life as short as 130 days, possibly by polymer-catalyzed degradation. These results suggest that fluoratelomer-polymer degradation is a significant source of PFOA and other fluorinated compounds to the environment.

Diagnosing and managing multiple sclerosis

The most common form of MS is relapsing remitting MS (RRMS). This is now a treatable condition and early diagnosis is becoming increasingly important in order to guide management decisions. After several years, RRMS may evolve into a slowly progressive deterioration in neurological function, known as secondary progressive MS. In 10-15% of people with MS, the condition follows this pattern of slow deterioration from onset, without relapses or remissions. This is primary progressive MS. It is difficult to predict prognosis in an individual patient. Factors associated with a favourable prognosis include female sex, onset with optic neuritis or sensory symptoms (rather than weakness or ataxia) and a long interval between initial relapses. RRMS is most commonly diagnosed in white women in their 20s. The first attack is known as a 'clinically isolated syndrome' reflecting inflammation in a single location. Common sites and symptoms are: optic nerve; spinal cord; sensory symptoms; Lhermitte's symptom and brainstem. The time course of symptoms is often helpful, as it is characteristic of inflammation. Patients tend to deteriorate over days, remain at a nadir for a week or two, and then recover over weeks. Recovery may be incomplete. Question patients directly to find out if there is a past history of any of the other common symptoms and perform a full neurological examination. Primary progressive MS should be suspected in patients presenting with a progressive spastic paraparesis or cerebellar syndrome. The diagnosis of MS should be made by a specialist and patients with a syndrome suggestive of MS should be referred to a neurologist. The mainstays of pharmacological treatment in RRMS are still the beta interferons and glatiramer acetate. These drugs reduce the rate of relapse by about a third and are therefore indicated for mobile patients with at least two relapses in the past two years.