Longitudinal microstructural alterations surrounding subcortical ischemic stroke lesions detected by free-water imaging.

In this study we explore the spatio-temporal trajectory and clinical relevance of microstructural white matter changes within and beyond subcortical stroke lesions detected by free-water imaging. Twenty-seven patients with subcortical infarct with mean age of 66.73 (SD 11.57) and median initial NIHSS score of 4 (IQR 3-7) received diffusion MRI 3-5 days, 1 month, 3 months, and 12 months after symptom-onset. Extracellular free-water and fractional anisotropy of the tissue (FAT) were averaged within stroke lesions and the surrounding tissue. Linear models showed increased free-water and decreased FAT in the white matter of patients with subcortical stroke (lesion [free-water/FAT, mean relative difference in %, ipsilesional vs. contralesional hemisphere at 3-5 days, 1 month, 3 months, and 12 months after symptom-onset]: +41/-34, +111/-37, +208/-26, +251/-18; perilesional tissue [range in %]: +[5-24]/-[0.2-7], +[2-20]/-[3-16], +[5-43]/-[2-16], +[10-110]/-[2-12]). Microstructural changes were most prominent within the lesion and gradually became less pronounced with increasing distance from the lesion. While free-water elevations continuously increased over time and peaked after 12 months, FAT decreases were most evident 1 month post-stroke, gradually returning to baseline values thereafter. Higher perilesional free-water and higher lesional FAT at baseline were correlated with greater reductions in lesion size (rho = -0.51, p = .03) in unadjusted analyses only, while there were no associations with clinical measures. In summary, we find a characteristic spatio-temporal pattern of extracellular and cellular alterations beyond subcortical stroke lesions, indicating a dynamic parenchymal response to ischemia characterized by vasogenic edema, cellular damage, and white matter atrophy.

Perineal Urethrostomy for Complex Urethral Strictures: Long-Term Patient-Reported Outcomes from a Reconstructive Referral Center and a Scoping Literature Review.

PURPOSE: There is a paucity of long-term objective and patient-reported outcomes after definitive perineal urethrostomy for complex urethral strictures. Our objective is to determine comprehensive long-term success of perineal urethrostomy with our 15-year experience at a reconstructive referral center. MATERIALS AND METHODS: Patients who underwent perineal urethrostomy between 2009 and 2023 were identified. A comprehensive long-term follow-up was conducted, evaluating both objective outcomes (retreatment-free survival) and subjective outcomes through the use of validated questionnaires. Additionally, to provide further context for our findings, we conducted a scoping review of all studies reporting outcomes following perineal urethrostomy. RESULTS: Among 76 patients, 55% had iatrogenic strictures, with 82% previously undergoing urethral interventions. At a median follow-up of 55 months, retreatment-free survival was 84%, with 16% of patients experiencing perineal urethrostomy recurrent stenosis. Patient-reported outcomes revealed a generally satisfactory voiding function (Urethral Stricture Surgery patient-reported outcome measure Lower Urinary Tract Symptoms score) and continence (International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form), with median scores of 4 (range 0-24) and 0 (range 0-21), but with bimodal distributions of sexual function scores (median International Index of Erectile Function-Erectile Function domain: 3.5; median Male Sexual Health Questionnaire-Ejaculation Scale: 21). Treatment satisfaction was very high with a median International Consultation on Incontinence Questionnaire-Satisfaction outcome score of 21 (range 0-24). The scoping review revealed varying success rates ranging from 51% to 95%, highlighting difficulties in comparison due to variable success definitions and patient case mix. CONCLUSIONS: Perineal urethrostomy provides effective treatment for complex anterior urethral strictures, with high patient satisfaction, preserved continence function, and favorable voiding outcomes. It presents a viable option for older and comorbid patients, especially after thorough counseling on expected outcomes and potential risks.

Smaller Cerebellar Lobule VIIb is Associated with Tremor Severity in Parkinson's Disease.

Alterations in the cerebellum's morphology in Parkinson's disease (PD) point to its pathophysiological involvement in this movement disorder. Such abnormalities have previously been attributed to different PD motor subtypes. The aim of the study was to relate volumes of specific cerebellar lobules to motor symptom severity, in particular tremor (TR), bradykinesia/rigidity (BR), and postural instability and gait disorders (PIGD) in PD. We performed a volumetric analysis based on T1-weighted MRI images of 55 participants with PD (22 females, median age 65 years, Hoehn and Yahr stage 2). Multiple regression models were fitted to investigate associations between volumes of cerebellar lobules with clinical symptom severity based on MDS-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III score and sub-scores for TR, BR, and PIGD; adjusted for age, sex, disease duration, and intercranial volume as cofactors. Smaller volume of lobule VIIb was associated with higher tremor severity (P = 0.004). No structure-function relationships were detected for other lobules or other motor symptoms. This distinct structural association denotes the involvement of the cerebellum in PD tremor. Characterizing morphological features of the cerebellum leads to a better understanding of its role in the spectrum of motor symptoms in PD and contributes further to identifying potential biological markers.

Female non-obstetric urogenital fistula repair: long-term patient-reported outcomes and a scoping literature review.

OBJECTIVE: To investigate long-term and patient-reported outcomes, including sexual function, in women undergoing urogenital fistula (UGF) repair, addressing the lack of such data in Western countries, where fistulas often result from iatrogenic causes. PATIENTS AND METHODS: We conducted a retrospective analysis at a tertiary referral centre (2010-2023), classifying fistulas based on World Health Organisation criteria and evaluating surgical approaches, aetiology, and characteristics. Both objective (fistula closure, reintervention rates) and subjective outcomes (validated questionnaires) were assessed. A scoping review of patient-reported outcome measures in UGF repair was also performed. RESULTS: The study included 50 patients: 17 (34%) underwent transvaginal and 33 (66%) transabdominal surgery. History of hysterectomy was present in 36 patients (72%). The median (interquartile range [IQR]) operating time was 130 (88-148) min. Fistula closure was achieved in 94% of cases at a median (IQR) follow-up of 50 (16-91) months and reached 100% after three redo fistula repairs. Seven patients (14%) underwent reinterventions for stress urinary incontinence after transvaginal repair (autologous fascial slings). Patient-reported outcomes showed median (IQR) scores on the International Consultation on Incontinence Questionnaire Female Lower Urinary Tract Symptoms Modules (ICIQ-FLUTS) of 5 (3-7) for filling symptoms, 1 (0-2) for voiding symptoms and 4.5 (1-9) for incontinence symptoms. The median (IQR) score on the ICIQ Female Sexual Matters Associated with Lower Urinary Tract Symptoms Module (ICIQ-FLUTSsex) was 3 (1-5). The median (IQR) ICIQ Satisfaction (ICIQ-S) outcome score and overall satisfaction with surgery item score was 22 (18.5-23.5) and 10 (8.5-10), respectively. Higher scores indicate higher symptom burden and treatment satisfaction, respectively. Our scoping review included 1784 women, revealing mixed aetiology and methodological and aetiological heterogeneity, thus complicating cross-study comparisons. CONCLUSIONS: Urogenital fistula repair at a specialised centre leads to excellent outcomes and high satisfaction. Patients with urethrovaginal fistulas are at increased risk of stress urinary incontinence, possibly due to the original trauma site of the fistula.

Ush regulates hemocyte-specific gene expression, fatty acid metabolism and cell cycle progression and cooperates with dNuRD to orchestrate hematopoiesis.

The generation of lineage-specific gene expression programmes that alter proliferation capacity, metabolic profile and cell type-specific functions during differentiation from multipotent stem cells to specialised cell types is crucial for development. During differentiation gene expression programmes are dynamically modulated by a complex interplay between sequence-specific transcription factors, associated cofactors and epigenetic regulators. Here, we study U-shaped (Ush), a multi-zinc finger protein that maintains the multipotency of stem cell-like hemocyte progenitors during Drosophila hematopoiesis. Using genomewide approaches we reveal that Ush binds to promoters and enhancers and that it controls the expression of three gene classes that encode proteins relevant to stem cell-like functions and differentiation: cell cycle regulators, key metabolic enzymes and proteins conferring specific functions of differentiated hemocytes. We employ complementary biochemical approaches to characterise the molecular mechanisms of Ush-mediated gene regulation. We uncover distinct Ush isoforms one of which binds the Nucleosome Remodeling and Deacetylation (NuRD) complex using an evolutionary conserved peptide motif. Remarkably, the Ush/NuRD complex specifically contributes to the repression of lineage-specific genes but does not impact the expression of cell cycle regulators or metabolic genes. This reveals a mechanism that enables specific and concerted modulation of functionally related portions of a wider gene expression programme. Finally, we use genetic assays to demonstrate that Ush and NuRD regulate enhancer activity during hemocyte differentiation in vivo and that both cooperate to suppress the differentiation of lamellocytes, a highly specialised blood cell type. Our findings reveal that Ush coordinates proliferation, metabolism and cell type-specific activities by isoform-specific cooperation with an epigenetic regulator.

Preserved Corticospinal Tract Revealed by Acute Perfusion Imaging Relates to Better Outcome After Thrombectomy in Stroke.

BACKGROUND: The indication for mechanical thrombectomy (MT) in stroke patients with large vessel occlusion has been constantly expanded over the past years. Despite remarkable treatment effects at the group level in clinical trials, many patients remain severely disabled even after successful recanalization. A better understanding of this outcome variability will help to improve clinical decision-making on MT in the acute stage. Here, we test whether current outcome models can be refined by integrating information on the preservation of the corticospinal tract as a functionally crucial white matter tract derived from acute perfusion imaging. METHODS: We retrospectively analyzed 162 patients with stroke and large vessel occlusion of the anterior circulation who were admitted to the University Medical Center Lübeck between 2014 and 2020 and underwent MT. The ischemic core was defined as fully automatized based on the acute computed tomography perfusion with cerebral blood volume data using outlier detection and clustering algorithms. Normative whole-brain structural connectivity data were used to infer whether the corticospinal tract was affected by the ischemic core or preserved. Ordinal logistic regression models were used to correlate this information with the modified Rankin Scale after 90 days. RESULTS: The preservation of the corticospinal tract was associated with a reduced risk of a worse functional outcome in large vessel occlusion-stroke patients undergoing MT, with an odds ratio of 0.28 (95% CI, 0.15-0.53). This association was still significant after adjusting for multiple confounding covariables, such as age, lesion load, initial symptom severity, sex, stroke side, and recanalization status. CONCLUSIONS: A preinterventional computed tomography perfusion-based surrogate of corticospinal tract preservation or disconnectivity is strongly associated with functional outcomes after MT. If validated in independent samples this concept could serve as a novel tool to improve current outcome models to better understand intersubject variability after MT in large vessel occlusion stroke.

Association between activity in the ventral premotor cortex and spinal cord activation during force generation-A combined cortico-spinal fMRI study.

Force generation is a crucial element of dexterity and a highly relevant skill of the human motor system. How cerebral and spinal components interact and how spinal activation is associated with the activity in the cerebral primary motor and premotor areas is poorly understood. Here, we conducted combined cortico-spinal functional magnetic resonance imaging during a simple visually guided isometric force generation task in 20 healthy young subjects. Activation was localized in the right cervical spinal cord and left primary motor and premotor areas. The main finding is that spinal activation was negatively correlated with ventral premotor cortex activation. Spinal activation was furthermore significantly correlated with primary motor cortex activation, while increasing target forces led to an increase in the amount of activation. These data indicate that human premotor areas such as the ventral premotor cortex might be functionally connected to the lower cervical spinal cord contributing to distal upper limb functions, a finding that extends our understanding of human motor function beyond the animal literature.

Disability and persistent motor deficits are linked to structural crossed cerebellar diaschisis in chronic stroke.

Brain imaging has significantly contributed to our understanding of the cerebellum being involved in recovery after non-cerebellar stroke. Due to its connections with supratentorial brain networks, acute stroke can alter the function and structure of the contralesional cerebellum, known as crossed cerebellar diaschisis (CCD). Data on the spatially precise distribution of structural CCD and their implications for persistent deficits after stroke are notably limited. In this cross-sectional study, structural MRI and clinical data were analyzed from 32 chronic stroke patients, at least 6 months after the event. We quantified lobule-specific contralesional atrophy, as a surrogate of structural CCD, in patients and healthy controls. Volumetric data were integrated with clinical scores of disability and motor deficits. Diaschisis-outcome models were adjusted for the covariables age, lesion volume, and damage to the corticospinal tract. We found that structural CCD was evident for the whole cerebellum, and particularly for lobules V and VI. Lobule VI diaschisis was significantly correlated with clinical scores, that is, volume reductions in contralesional lobule VI were associated with higher levels of disability and motor deficits. Lobule V and the whole cerebellum did not show similar diaschisis-outcome relationships across the spectrum of the clinical scores. These results provide novel insights into stroke-related cerebellar plasticity and might thereby promote lobule VI as a key area prone to structural CCD and potentially involved in recovery and residual motor functioning.

Outcome of patients with epithelialized cavity formation after excessive vesicourethral anastomotic leak post radical prostatectomy.

PURPOSE: Excessive vesicourethral anastomotic leak (EVAL) is a rare but severe complication after radical prostatectomy (RP). Epithelialized vesicourethral cavity formation (EVCF) usually develops during prolonged catheterization. To our knowledge, there is no description of postoperative outcomes, complications, or functional assessment of these patients who received conservative therapy after EVAL. METHODS: We identified 70 patients (0.56%) with radiographic evidence of EVCF out of 12,434 patients who received RP in 2016-2020 at our tertiary care center. Postoperative radiographic cystograms (CG) were retrospectively re-examined by two urologists individually. We assessed urinary continence (UC), the need for intervention due to anastomotic stricture formation, urinary tract infection (UTI), and symphysitis during the first year of follow-up post-RP. RESULTS: The median age was 66 years [interquartile range (IQR) 61-70 years], the median body mass index was 27.8 kg/m2 (IQR 25.5-30.3 kg/m2), and the median prostate specific antigen before RP was 7.1 ng/ml (IQR 4.7-11.8 ng/ml). The median catheter insertion time was 44.5 days (IQR 35.2-54 days). One-year continence follow-up was available for 27 patients (38.6%), of which 22 (81.5%) reported the use of ≤ one pad, two patients reported the use of two (7.4%) pads/24 h, and three (11.1%) patients reported use > two pads/24 h. Overall, four (5.7%) patients needed surgical reintervention for anastomotic stricture, eight (11.5%) patients presented with symphysitis, and 55 (77.1%) presented with UTI. CONCLUSION: UC in 81.5% 1-year post-RP suggests that conservative treatment in EVAL is a treatment option with an acceptable outcome on UC and should be considered before reintervention for anastomotic insufficiency.

Cortical thickness of contralesional cortices positively relates to future outcome after severe stroke.

Imaging studies have evidenced that contralesional cortices are involved in recovery after motor stroke. Cortical thickness (CT) analysis has proven its potential to capture the changes of cortical anatomy, which have been related to recovery and treatment gains under therapy. An open question is whether CT obtained in the acute phase after stroke might inform correlational models to explain outcome variability. Data of 38 severely impaired (median NIH Stroke Scale 9, interquartile range: 6-13) acute stroke patients of 2 independent cohorts were reanalyzed. Structural imaging data were processed via the FreeSurfer pipeline to quantify regional CT of the contralesional hemisphere. Ordinal logistic regression models were fit to relate CT to modified Rankin Scale as an established measure of global disability after 3-6 months, adjusted for the initial deficit, lesion volume, and age. The data show that CT of contralesional cortices, such as the precentral gyrus, the superior frontal sulcus, and temporal and cingulate cortices, positively relates to the outcome after stroke. This work shows that the baseline cortical anatomy of selected contralesional cortices can explain the outcome variability after severe stroke, which further contributes to the concept of structural brain reserve with respect to contralesional cortices to promote recovery.

Diabetes, Glycated Hemoglobin (HbA1c), and Neuroaxonal Damage in Parkinson's Disease (MARK-PD Study).

BACKGROUND: Diabetes is associated with incidence and prevalence of Parkinson's disease (PD). Furthermore, glycated hemoglobin (HbA1c) levels have been linked with motor function and progression. OBJECTIVES: We evaluated the relationship between prevalent diabetes and HbA1c levels with serum neurofilament light chain (NfL) levels as marker of neuroaxonal damage. METHODS: NfL concentrations were analyzed with Simoa in serum of 195 PD patients with available HbA1c values. Motor (MDS-UPDRS III, Hoehn & Yahr [H&Y]) and cognitive (Montreal Cognitive Assessment [MoCA]) function was assessed and vascular comorbidities were documented from medical records. RESULTS: PD patients with prevalent diabetes had higher serum NfL levels and lower MoCA scores independent of age, body mass index (BMI), and vascular risk factors. Furthermore, diabetes was associated with higher H&Y stages in unadjusted and age/BMI-adjusted models. Higher HbA1c levels were associated with increased NfL in unadjusted and age/BMI-adjusted models. CONCLUSIONS: In PD patients, diabetes and high HbA1c are associated with increased neuroaxonal damage and cognitive impairment. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson Movement Disorder Society.

Replacing bar graphs of continuous data with more informative graphics: are we making progress?

Recent work has raised awareness about the need to replace bar graphs of continuous data with informative graphs showing the data distribution. The impact of these efforts is not known. The present observational meta-research study examined how often scientists in different fields use various graph types, and assessed whether visualization practices have changed between 2010 and 2020. We developed and validated an automated screening tool, designed to identify bar graphs of counts or proportions, bar graphs of continuous data, bar graphs with dot plots, dot plots, box plots, violin plots, histograms, pie charts, and flow charts. Papers from 23 fields (approximately 1000 papers/field per year) were randomly selected from PubMed Central and screened (n=227998). F1 scores for different graphs ranged between 0.83 and 0.95 in the internal validation set. While the tool also performed well in external validation sets, F1 scores were lower for uncommon graphs. Bar graphs are more often used incorrectly to display continuous data than they are used correctly to display counts or proportions. The proportion of papers that use bar graphs of continuous data varies markedly across fields (range in 2020: 4-58%), with high rates in biochemistry and cell biology, complementary and alternative medicine, physiology, genetics, oncology and carcinogenesis, pharmacology, microbiology and immunology. Visualization practices have improved in some fields in recent years. Fewer than 25% of papers use flow charts, which provide information about attrition and the risk of bias. The present study highlights the need for continued interventions to improve visualization and identifies fields that would benefit most.

Serum neurofilament light chain and postural instability/gait difficulty (PIGD) subtypes of Parkinson's disease in the MARK-PD study.

The PIGD (postural instability / gait difficulty) subtype of Parkinson´s disease (PD) is associated with faster cognitive and motor decline. So far, there are no quantifiable biomarkers to aid clinical subtyping. Neurofilament light chain (NfL) is a highly specific marker of neuro-axonal damage and can be assessed in blood. Here, we investigated if serum NfL concentrations are associated with PIGD subtype and PIGD scores in PD patients at advanced disease stages. Furthermore, we evaluated if serum NfL is associated with motor and cognitive function assessed with MDS-UPDRS part III and Montreal cognitive assessment (MoCA). Serum NfL levels were analyzed with Single Molecule Assays (Simoa) in blood of 223 PD patients from the bioMARKers in Parkinson's Disease (MARK-PD) study. Serum NfL concentrations were higher in PIGD patients independent of age, sex and disease duration. In linear regression analysis, serum NfL levels were associated with MoCA, MDS-UPDRS III and PIGD scores in unadjusted models, but remained significant after adjustment only with PIGD scores. In conclusion, increased serum NfL levels were associated with PIGD subtype and PIGD scores in patients with advanced PD.

Impact of interhemispheric inhibition on bimanual movement control in young and old.

Interhemispheric interactions demonstrate a crucial role for directing bimanual movement control. In humans, a well-established paired-pulse transcranial magnetic stimulation paradigm enables to assess these interactions by means of interhemispheric inhibition (IHI). Previous studies have examined changes in IHI from the active to the resting primary motor cortex during unilateral muscle contractions; however, behavioral relevance of such changes is still inconclusive. In the present study, we evaluated two bimanual tasks, i.e., mirror activity and bimanual anti-phase tapping, to examine behavioral relevance of IHI for bimanual movement control within this behavioral framework. Two age groups (young and older) were evaluated as bimanual movement control demonstrates evident behavioral decline in older adults. Two types of IHI with differential underlying mechanisms were measured; IHI was tested at rest and during a motor task from the active to the resting primary motor cortex. Results demonstrate an association between behavior and short-latency IHI in the young group: larger short-latency IHI correlated with better bimanual movement control (i.e., less mirror activity and better bimanual anti-phase tapping). These results support the view that short-latency IHI represents a neurophysiological marker for the ability to suppress activity of the contralateral side, likely contributing to efficient bimanual movement control. This association was not observed in the older group, suggesting age-related functional changes of IHI. To determine underlying mechanisms of impaired bimanual movement control due to neurological disorders, it is crucial to have an in-depth understanding of age-related mechanisms to disentangle disorder-related mechanisms of impaired bimanual movement control from age-related ones.

No correlation between symmetry-based performance measures and patient-related outcome prior to and after total knee arthroplasty.

PURPOSE: Standardized outcome measures are crucial for the evaluation of different treatment and rehabilitation regimes in patients after total knee arthroplasty (TKA). Performance-based measures are necessary to capture different aspects of physical function. High reliability and agreement of five performance-based measures were hypothesized to differentiate between measurement error and change in test performance. Secondary outcomes are the correlation of performance-based measurements to KSS and WOMAC prior to surgery (baseline) and 10 weeks thereafter (t3). METHODS: The test-retest reliabilities and agreements of the 1-m walk test, the stair-climbing test, the timed-up-and-go test, the weight-balanced-chair-rising test and the isometric maximum knee extension force in patients undergoing total knee replacements were studied. The intraclass correlation coefficient was calculated and a Bland-Altman analysis performed. RESULTS: The weight-balanced-chair-rising test showed a symmetry at baseline = 0.77, 5 ± 1 days after surgery (t1) = 0.50, 9 ± 1 days (t2) = 0.59 and (t3) = 0.80. All performance tests showed high intraclass correlation coefficients (ICC = 0.81-0.99). The 10-m walk test, stair climbing test, and the timed-up-and-go test showed high agreement in the Bland-Altman analysis. The Bland-Altman analysis for the weight-balanced-chair-rising test and isometric knee extension force indicated high agreement at 5 and 9 days postoperatively, but the relative measurement error increased pre- and 10 weeks postoperatively. CONCLUSION: In conclusion, symmetry, as an important outcome after TKA, is a reliable and rather unique item that should unquestionably be added to established measurements like walking tests or survey-based function assessment. The implementation of standardized performance-based measures to assess physical function in rehabilitation procedures will help to improve the more objectively based assessment of different rehabilitation protocols. LEVEL OF EVIDENCE: II.

Corticospinal Tract Microstructure Correlates With Beta Oscillatory Activity in the Primary Motor Cortex After Stroke.

BACKGROUND AND PURPOSE: Cortical beta oscillations are reported to serve as robust measures of the integrity of the human motor system. Their alterations after stroke, such as reduced movement-related beta desynchronization in the primary motor cortex, have been repeatedly related to the level of impairment. However, there is only little data whether such measures of brain function might directly relate to structural brain changes after stroke. METHODS: This multimodal study investigated 18 well-recovered patients with stroke (mean age 65 years, 12 males) by means of task-related EEG and diffusion-weighted structural MRI 3 months after stroke. Beta power at rest and movement-related beta desynchronization was assessed in 3 key motor areas of the ipsilesional hemisphere that are the primary motor cortex (M1), the ventral premotor area and the supplementary motor area. Template trajectories of corticospinal tracts (CST) originating from M1, premotor cortex, and supplementary motor area were used to quantify the microstructural state of CST subcomponents. Linear mixed-effects analyses were used to relate tract-related mean fractional anisotropy to EEG measures. RESULTS: In the present cohort, we detected statistically significant reductions in ipsilesional CST fractional anisotropy but no alterations in EEG measures when compared with healthy controls. However, in patients with stroke, there was a significant association between both beta power at rest (P=0.002) and movement-related beta desynchronization (P=0.003) in M1 and fractional anisotropy of the CST specifically originating from M1. Similar structure-function relationships were neither evident for ventral premotor area and supplementary motor area, particularly with respect to their CST subcomponents originating from premotor cortex and supplementary motor area, in patients with stroke nor in controls. CONCLUSIONS: These data suggest there might be a link connecting microstructure of the CST originating from M1 pyramidal neurons and beta oscillatory activity, measures which have already been related to motor impairment in patients with stroke by previous reports.

White matter degeneration revealed by fiber-specific analysis relates to recovery of hand function after stroke.

Recent developments of higher-order diffusion-weighted imaging models have enabled the estimation of specific white matter fiber populations within a voxel, addressing limitations of traditional imaging markers of white matter integrity. We applied fixel based analysis (FBA) to investigate the evolution of fiber-specific white matter changes in a prospective study of stroke patients and upper limb motor deficit over 1 year after stroke. We studied differences in fiber density and macrostructural changes in fiber cross-section. Motor function was assessed by grip strength. We conducted a whole-brain analysis of fixel metrics and predefined corticospinal tract (CST) region of interest in relation to changes in motor functions. In 30 stroke patients (mean age 62.3 years, SD ±16.9; median NIHSS 4, IQR 2-5), whole-brain FBA revealed progressing loss of fiber density and cross-section in the ipsilesional corticospinal tract and long-range fiber tracts such as the superior longitudinal fascicle and trans-callosal tracts extending towards contralesional white matter tracts. Lower FBA metrics measured at the brainstem section of the CST 1 month after stroke were significantly associated with lower grip strength 3 months (p = .009, adjusted R2  = 0.259) and 1 year (T4: p < .001, adj. R2  = 0.515) after stroke. Compared to FA, FBA metrics showed a comparably strong association with grip strength at later time points. Using FBA, we demonstrate progressive fiber-specific white matter loss after stroke and association with functional motor outcome. Our results promote the application of fiber-specific analysis to detect secondary neurodegeneration after stroke in relation to clinical recovery.

The Influence of Cortico-Cerebellar Structural Connectivity on Cortical Excitability in Chronic Stroke.

Brain imaging has recently evidenced that the structural state of distinct reciprocal cortico-cerebellar fiber tracts, the dentato-thalamo-cortical tract (DTCT), and the cortico-ponto-cerebellar tract (CPCeT), significantly influences residual motor output in chronic stroke patients, independent from the level of damage to the corticospinal tract (CST). Whether such structural information might also directly relate to measures of cortical excitability is an open question. Eighteen chronic stroke patients with supratentorial ischemic lesions and 17 healthy controls underwent transcranial magnetic stimulation to assess recruitment curves of motor evoked potentials of both hemispheres. Diffusion-weighted imaging and probabilistic tractography were applied to reconstruct reciprocal cortico-cerebellar motor tracts between the primary motor cortex and the cerebellum. Tract-related microstructure was estimated by means of fractional anisotropy, and linear regression modeling was used to relate it to cortical excitability. The main finding was a significant association between cortical excitability and the structural integrity of the DTCT, the main cerebellar outflow tract, independent from the level of damage to the CST. A comparable relationship was neither detectable for the CPCeT nor for the healthy controls. This finding contributes to a mechanistic understanding of the putative supportive role of the cerebellum for residual motor output by facilitating cortical excitability after stroke.

Chemical Evolution of Antivirals Against Enterovirus D68 through Protein-Templated Knoevenagel Reactions.

The generation of bioactive molecules from inactive precursors is a crucial step in the chemical evolution of life, however, mechanistic insights into this aspect of abiogenesis are scarce. Here, we investigate the protein-catalyzed formation of antivirals by the 3C-protease of enterovirus D68. The enzyme induces aldol condensations yielding inhibitors with antiviral activity in cells. Kinetic and thermodynamic analyses reveal that the bioactivity emerges from a dynamic reaction system including inhibitor formation, alkylation of the protein target by the inhibitors, and competitive addition of non-protein nucleophiles to the inhibitors. The most active antivirals are slowly reversible inhibitors with elongated target residence times. The study reveals first examples for the chemical evolution of bio-actives through protein-catalyzed, non-enzymatic C-C couplings. The discovered mechanism works under physiological conditions and might constitute a native process of drug development.

Low-Frequency Brain Oscillations Track Motor Recovery in Human Stroke.

OBJECTIVE: The majority of patients with stroke survive the acute episode and live with enduring disability. Effective therapies to support recovery of motor function after stroke are yet to be developed. Key to this development is the identification of neurophysiologic signals that mark recovery and are suitable and susceptible to interventional therapies. Movement preparatory low-frequency oscillations (LFOs) play a key role in cortical control of movement. Recent animal data point to a mechanistic role of motor cortical LFOs in stroke motor deficits and demonstrate neuromodulation intervention with therapeutic benefit. Their relevance in human stroke pathophysiology is unknown. METHODS: We studied the relationship between movement-preparatory LFOs during the performance of a visuomotor grip task and motor function in a longitudinal (<5 days, 1 and 3 months) cohort study of 33 patients with motor stroke and in 19 healthy volunteers. RESULTS: Acute stroke-lesioned brains fail to generate the LFO signal. Whereas in healthy humans, a transient occurrence of LFOs preceded movement onset at predominantly contralateral frontoparietal motor regions, recordings in patients revealed that movement-preparatory LFOs were substantially diminished to a level of 38% after acute stroke. LFOs progressively increased at 1 and 3 months. This re-emergence closely tracked the recovery of motor function across several movement qualities including grip strength, fine motor skills, and synergies and was frequency band specific. INTERPRETATION: Our results provide the first human evidence for a link between movement-preparatory LFOs and functional recovery after stroke, promoting their relevance for movement control. These results suggest that it may be interesting to explore targeted, LFOs-restorative brain stimulation therapy in human stroke patients. ANN NEUROL 2019;86:853-865.