| 391. |
- Shemesh, Noam, et al.
(författare)
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Conventions and nomenclature for double diffusion encoding NMR and MRI.
- 2016
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Ingår i: Magnetic Resonance in Medicine. - : Wiley. - 1522-2594 .- 0740-3194. ; 75:1, s. 82-87
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Forskningsöversikt (refereegranskat)abstract
- Stejskal and Tanner's ingenious pulsed field gradient design from 1965 has made diffusion NMR and MRI the mainstay of most studies seeking to resolve microstructural information in porous systems in general and biological systems in particular. Methods extending beyond Stejskal and Tanner's design, such as double diffusion encoding (DDE) NMR and MRI, may provide novel quantifiable metrics that are less easily inferred from conventional diffusion acquisitions. Despite the growing interest on the topic, the terminology for the pulse sequences, their parameters, and the metrics that can be derived from them remains inconsistent and disparate among groups active in DDE. Here, we present a consensus of those groups on terminology for DDE sequences and associated concepts. Furthermore, the regimes in which DDE metrics appear to provide microstructural information that cannot be achieved using more conventional counterparts (in a model-free fashion) are elucidated. We highlight in particular DDE's potential for determining microscopic diffusion anisotropy and microscopic fractional anisotropy, which offer metrics of microscopic features independent of orientation dispersion and thus provide information complementary to the standard, macroscopic, fractional anisotropy conventionally obtained by diffusion MR. Finally, we discuss future vistas and perspectives for DDE. Magn Reson Med, 2015. © 2015 Wiley Periodicals, Inc.
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| 392. |
- Shin, Hyeong-Geol, et al.
(författare)
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Compartmental anisotropy of filtered exchange imaging (FEXI) in human white matter : What is happening in FEXI?
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Ingår i: Magnetic Resonance in Medicine. - 1522-2594.
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate the effects of compartmental anisotropy on filtered exchange imaging (FEXI) in white matter (WM).THEORY AND METHODS: FEXI signals were measured using multiple combinations of diffusion filter and detection directions in five healthy volunteers. Additional filters, including a trace-weighted diffusion filter with trapezoidal gradients, a spherical b-tensor encoded diffusion filter, and a T2 filter, were tested with trace-weighted diffusion detection.RESULTS: A large range of apparent exchange rates (AXR) and both positive and negative filter efficiencies (σ) were found depending on the mutual orientation of the filter and detection gradients relative to WM fiber orientation. The data demonstrated that the fast-diffusion compartment suppressed by diffusional filtering is not exclusively extra-cellular, but also intra-cellular. While not comprehensive, a simple two-compartment diffusion tensor model with water exchange was able to account qualitatively for the trends in positive and negative filtering efficiencies, while standard model imaging (SMI) without exchange could not. This two-compartment diffusion tensor model also demonstrated smaller AXR variances across subjects. When employing trace-weighted diffusion detection, AXR values were on the order of the R 1 (=1/T1) of water at 3T for crossing fibers, while being less than R 1 for parallel fibers. CONCLUSION: Orientation-dependent AXR and σ values were observed when using multi-orientation filter and detection gradients in FEXI, indicating that WM FEXI models need to account for compartmental anisotropy. When using trace-weighted detection, AXR values were on the order of or less than R 1, complicating the interpretation of FEXI results in WM in terms of biological exchange properties. These findings may contribute toward better understanding of FEXI results in WM.
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| 393. |
- Sjostrom, H, et al.
(författare)
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Mapping of apparent susceptibility yields promising diagnostic separation of progressive supranuclear palsy from other causes of parkinsonism
- 2019
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Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9:1, s. 6079-
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for methods that distinguish Parkinson’s disease (PD) from progressive supranuclear palsy (PSP) and multiple system atrophy (MSA), which have similar characteristics in the early stages of the disease. In this prospective study, we evaluate mapping of apparent susceptibility based on susceptibility weighted imaging (SWI) for differential diagnosis. We included 134 patients with PD, 11 with PSP, 10 with MSA and 44 healthy controls. SWI data were processed into maps of apparent susceptibility. In PSP, apparent susceptibility was increased in the red nucleus compared to all other groups, and in globus pallidus, putamen, substantia nigra and the dentate nucleus compared to PD and controls. In MSA, putaminal susceptibility was increased compared to PD and controls. Including all studied regions and using discriminant analysis between PSP and PD, 100% sensitivity and 97% specificity was achieved, and 91% sensitivity and 90% specificity in separating PSP from MSA. Correlations between putaminal susceptibility and disease severity in PD could warrant further research into using susceptibility mapping for monitoring disease progression and in clinical trials. Our study indicates that susceptibility in deep nuclei could play a role in the diagnosis of atypical parkinsonism, especially in PSP.
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| 394. |
- Sjödahl Hammarlund, Catharina, et al.
(författare)
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Conceptualizing and prioritizing clinical trial outcomes from the perspectives of people with Parkinson’s disease versus health care professionals : a concept mapping study
- 2014
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Ingår i: Quality of Life Research. - 0962-9343 .- 1573-2649. ; 23:6, s. 1687-1700
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundFocusing clinical investigations on outcomes that are meaningful from an end-user perspective is central in clinical research, particularly in chronic disorders such as Parkinson’s disease (PD). However, little is known about how end-users such as people with PD (PwPD) and health care professionals (HCPs) view and prioritize therapeutic outcomes.PurposeTo compare the perspectives of PwPD and HCPs regarding prioritized areas for outcome measurement in clinical PD trials.MethodsConcept mapping was used to identify prioritized outcomes (statements) through focus groups (n = 27; 12 PwPD, 12 HCPs, three researchers), statement sorting and importance rating (n = 38; 19 PwPD, 19 HCPs), followed by quantitative (multidimensional scaling, cluster analysis, procrustes analysis) and qualitative analysis.ResultsSorting of 99 statements by PwPD and HCPs yielded 2D maps (PwPD/HCPs stress values, 0.31/0.21) with eight clusters per group. The correlation between raw sorting data of PwPD and HCPs was 0.80, and there was a significant concordance (m12 = 0.53; P < 0.001; i.e., r = 0.68) between the spatial arrangements in their respective maps. Qualitatively, the maps from the two groups represented partially different perspectives. There were no significant differences between PwPD and HCP item importance ratings.ConclusionAlthough similarities dominated, there were differences in how the relationships between items were perceived by the two groups, emanating from different perspectives, i.e., the clinical biomedical (“disease”) versus the lived experience (“illness”). This study illustrates the clinical importance of attention to the perspective of PwPD; taking this into account is likely to provide evidence from clinical investigations that are meaningful and interpretable for end-users.
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| 395. |
- Sjödahl Hammarlund, Catharina, et al.
(författare)
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Conceptualizing and prioritizing clinical trial outcomes from the perspectives of people with Parkinson’s disease versus health care professionals : a concept mapping study
- 2014
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Ingår i: Quality of Life Research. - : Springer Netherlands. - 0962-9343 .- 1573-2649. ; 23:6, s. 1687-1700
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Tidskriftsartikel (refereegranskat)abstract
- Background Focusing clinical investigations on outcomes that are meaningful from an end-user perspective is central in clinical research, particularly in chronic disorders such as Parkinson’s disease (PD). However, little is known about how end-users such as people with PD (PwPD) and health care professionals (HCPs) view and prioritize therapeutic outcomes. Purpose To compare the perspectives of PwPD and HCPs regarding prioritized areas for outcome measurement in clinical PD trials. Methods Concept mapping was used to identify prioritized outcomes (statements) through focus groups (n = 27; 12 PwPD, 12 HCPs, three researchers), statement sorting and importance rating (n = 38; 19 PwPD, 19 HCPs), followed by quantitative (multidimensional scaling, cluster analysis, procrustes analysis) and qualitative analysis. Results Sorting of 99 statements by PwPD and HCPs yielded 2D maps (PwPD/HCPs stress values, 0.31/0.21) with eight clusters per group. The correlation between raw sorting data of PwPD and HCPs was 0.80, and there was a significant concordance (m12 = 0.53; P < 0.001; i.e., r = 0.68) between the spatial arrangements in their respective maps. Qualitatively, the maps from the two groups represented partially different perspectives. There were no significant differences between PwPD and HCP item importance ratings. Conclusion Although similarities dominated, there were differences in how the relationships between items were perceived by the two groups, emanating from different perspectives, i.e., the clinical biomedical (“disease”) versus the lived experience (“illness”). This study illustrates the clinical importance of attention to the perspective of PwPD; taking this into account is likely to provide evidence from clinical investigations that are meaningful and interpretable for end-users.
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| 396. |
- Sjölund, Jens, et al.
(författare)
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Constrained optimization of gradient waveforms for generalized diffusion encoding
- 2015
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Ingår i: Journal of magnetic resonance. - : Elsevier. - 1090-7807 .- 1096-0856. ; 261, s. 157-168
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Tidskriftsartikel (refereegranskat)abstract
- Diffusion MRI is a useful probe of tissue structure. The prototypical diffusion encoding sequence, the single pulsed field gradient, has recently been challenged with the introduction of more general gradient waveforms. Out of these, we focus on q-space trajecory imaging, which generalizes the scalar b-value to a tensor valued property. To take full advantage of its capabilities, it is imperative to respect the constraints imposed by the hardware, while at the same time maximizing the diffusion encoding strength. We formulate this as a constrained optimization problem that accomodates constraints on maximum gradient amplitude, slew rate, coil heating and positioning of radiofrequency pulses. The power of this approach is demonstrated by a comparison with previous work on optimization of isotropic diffusion sequences, showing possible gains in diffusion weighting or in heat dissipation, which in turn means increased signal or reduced scan-times.
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| 397. |
- Skendros, Panagiotis, et al.
(författare)
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Complement C3 inhibition in severe COVID-19 using compstatin AMY-101
- 2022
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 8:33
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Tidskriftsartikel (refereegranskat)abstract
- Complement C3 activation contributes to COVID-19 pathology, and C3 targeting has emerged as a promising therapeutic strategy. We provide interim data from ITHACA, the first randomized trial evaluating a C3 inhibitor, AMY-101, in severe COVID-19 (PaO2/FiO2 <= 300 mmHg). Patients received AMY-101 (n = 16) or placebo (n = 15) in addition to standard of care. AMY-101 was safe and well tolerated. Compared to placebo (8 of 15, 53.3%), a higher, albeit nonsignificant, proportion of AMY-101-treated patients (13 of 16, 81.3%) were free of supplemental oxygen at day 14. Three nonresponders and two placebo-treated patients succumbed to disease-related complications. AMY-101 significantly reduced CRP and ferritin and restrained thrombin and NET generation. Complete and sustained C3 inhibition was observed in all responders. Residual C3 activity in the three nonresponders suggested the presence of a convertase-independent C3 activation pathway overriding the drug's inhibitory activity. These findings support the design of larger trials exploring the potential of C3-based inhibition in COVID-19 or other complement-mediated diseases.
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| 398. |
- Sloot, Frea, et al.
(författare)
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Inventory of current EU paediatric vision and hearing screening programmes
- 2015
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Ingår i: Journal of Medical Screening. - : SAGE Publications. - 0969-1413 .- 1475-5793. ; 22:2, s. 55-64
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To examine the diversity in paediatric vision and hearing screening programmes in Europe. Methods: Themes for comparison of screening programmes derived from literature were used to compile three questionnaires on vision, hearing, and public health screening. Tests used, professions involved, age, and frequency of testing seem to influence sensitivity, specificity, and costs most. Questionnaires were sent to ophthalmologists, orthoptists, otolaryngologists, and audiologists involved in paediatric screening in all EU full-member, candidate, and associate states. Answers were cross-checked. Results: Thirty-nine countries participated; 35 have a vision screening programme, 33 a nation-wide neonatal hearing screening programme. Visual acuity (VA) is measured in 35 countries, in 71% of these more than once. First measurement of VA varies from three to seven years of age, but is usually before age five. At age three and four, picture charts, including Lea Hyvarinen, are used most; in children over four, Tumbling-E and Snellen. As first hearing screening test, otoacoustic emission is used most in healthy neonates, and auditory brainstem response in premature newborns. The majority of hearing testing programmes are staged; children are referred after 1–4 abnormal tests. Vision screening is performed mostly by paediatricians, ophthalmologists, or nurses. Funding is mostly by health insurance or state. Coverage was reported as >95% in half of countries, but reporting was often not first-hand. Conclusion: Largest differences were found in VA charts used (12), professions involved in vision screening (10), number of hearing screening tests before referral (1–4), and funding sources (8).
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| 399. |
- Sogorb-Esteve, Aitana, et al.
(författare)
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Differential impairment of cerebrospinal fluid synaptic biomarkers in the genetic forms of frontotemporal dementia.
- 2022
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Ingår i: Alzheimer's research & therapy. - : Springer Science and Business Media LLC. - 1758-9193. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Approximately a third of frontotemporal dementia (FTD) is genetic with mutations in three genes accounting for most of the inheritance: C9orf72, GRN, and MAPT. Impaired synaptic health is a common mechanism in all three genetic variants, so developing fluid biomarkers of this process could be useful as a readout of cellular dysfunction within therapeutic trials.A total of 193 cerebrospinal fluid (CSF) samples from the GENetic FTD Initiative including 77 presymptomatic (31 C9orf72, 23 GRN, 23 MAPT) and 55 symptomatic (26 C9orf72, 17 GRN, 12 MAPT) mutation carriers as well as 61 mutation-negative controls were measured using a microflow LC PRM-MS set-up targeting 15 synaptic proteins: AP-2 complex subunit beta, complexin-2, beta-synuclein, gamma-synuclein, 14-3-3 proteins (eta, epsilon, zeta/delta), neurogranin, Rab GDP dissociation inhibitor alpha (Rab GDI alpha), syntaxin-1B, syntaxin-7, phosphatidylethanolamine-binding protein 1 (PEBP-1), neuronal pentraxin receptor (NPTXR), neuronal pentraxin 1 (NPTX1), and neuronal pentraxin 2 (NPTX2). Mutation carrier groups were compared to each other and to controls using a bootstrapped linear regression model, adjusting for age and sex.CSF levels of eight proteins were increased only in symptomatic MAPT mutation carriers (compared with controls) and not in symptomatic C9orf72 or GRN mutation carriers: beta-synuclein, gamma-synuclein, 14-3-3-eta, neurogranin, Rab GDI alpha, syntaxin-1B, syntaxin-7, and PEBP-1, with three other proteins increased in MAPT mutation carriers compared with the other genetic groups (AP-2 complex subunit beta, complexin-2, and 14-3-3 zeta/delta). In contrast, CSF NPTX1 and NPTX2 levels were affected in all three genetic groups (decreased compared with controls), with NPTXR concentrations being affected in C9orf72 and GRN mutation carriers only (decreased compared with controls). No changes were seen in the CSF levels of these proteins in presymptomatic mutation carriers. Concentrations of the neuronal pentraxins were correlated with brain volumes in the presymptomatic period for the C9orf72 and GRN groups, suggesting that they become abnormal in proximity to symptom onset.Differential synaptic impairment is seen in the genetic forms of FTD, with abnormalities in multiple measures in those with MAPT mutations, but only changes in neuronal pentraxins within the GRN and C9orf72 mutation groups. Such markers may be useful in future trials as measures of synaptic dysfunction, but further work is needed to understand how these markers change throughout the course of the disease.
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| 400. |
- Soldatov, Ruslan, et al.
(författare)
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Spatiotemporal structure of cell fate decisions in murine neural crest
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6444
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Tidskriftsartikel (refereegranskat)abstract
- Neural crest cells are embryonic progenitors that generate numerous cell types in vertebrates. With single-cell analysis, we show that mouse trunk neural crest cells become biased toward neuronal lineages when they delaminate from the neural tube, whereas cranial neural crest cells acquire ectomesenchyme potential dependent on activation of the transcription factor Twist1. The choices that neural crest cells make to become sensory, glial, autonomic, or mesenchymal cells can be formalized as a series of sequential binary decisions. Each branch of the decision tree involves initial coactivation of bipotential properties followed by gradual shifts toward commitment. Competing fate programs are coactivated before cells acquire fate-specific phenotypic traits. Determination of a specific fate is achieved by increased synchronization of relevant programs and concurrent repression of competing fate programs.
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