Superparamagnetic iron oxide (SPIO) nanoparticles with optimized and well-characterized properties are critical for Magnetic Particle Imaging (MPI). MPI is a novel in vivo imaging modality that ...promises to integrate the speed of X-ray CT, safety of MRI and sensitivity of PET. Since SPIOs are the source of MPI signal, both the core and surface properties must be optimized to enable efficient in vivo imaging with pharmacokinetics tailored for specific imaging applications. Existing SPIOs like Resovist (ferucarbotran) provide a suboptimal MPI signal, and further limit MPI's in vivo utility due to rapid systemic clearance. An SPIO agent with a long blood half-life (t
) would be a versatile MPI tracer with widespread applications. Here we show that a long circulating polyethylene glycol (PEG)-coated SPIO tracer, LS-008, provides excellent colloidal stability and a persistent intravascular MPI signal, showing its potential as the first blood pool tracer optimized for MPI. We evaluated variations of PEG coating and found that colloidal stability of tracers improved with the increasing PEG molecular weight (keeping PEG loading constant). Blood circulation in mice, evaluated using Magnetic Particle Spectrometry (MPS), showed that the t
of SPIO tracers varied with both PEG molecular weight and loading. LS-008, coated with 20 kDa PEG at 18.8% loading capacity, provided the most promising long-term colloidal stability with a t
of about 105 minutes in mice. In vivo MPI imaging with LS-008 using a 7 T/m/μ
3D x-space MPI mouse scanner revealed a prolonged intravascular signal (3-5 hours) post-injection. Our results show the optimized magnetic properties and long systemic retention of LS-008 making it a promising blood pool MPI tracer, with potential to enable MPI imaging in cardio- and cerebrovascular disease models, and solid tumor quantification and imaging via enhanced permeation and retention.
Robust and well-established orthogonal techniques for characterization of individual extracellular vesicles (EVs) are required to utilize them as therapeutic and diagnostic tools. However, to better ...utilize any analytical technology, we first need to determine the limitations of that technology.
We have established capabilities to reliably analyze EVs samples using three different orthogonal techniques; nanoparticle tracking analysis, flow cytometry and analytical HPLC. Using these three platforms, EV samples can be analyzed reliably and in agreement with MISEV and MIFlowCyt-EV guidelines.
Scattering and fluorescence mode of NTA suffer from masking effect and photobleaching respectively. We have optimized the labeling and measurement parameters to achieve reliable measurements. We will provide guidelines on how to characterize EVs accurately using any single particle analysis technique.
We tested EV standards from Sigma (tested at ISEVxTech 2022) and measured identical particle concentration on 3 orthogonal techniques sc-NTA, fl-NTA and flow cytometry.
We compared the size distribution using 5 techniques, sc-NTA (static), sc-NTA (flow), fl-NTA (flow), DLS and Cryo-EM. We found out that fl-NTA (flow) and Cryo-EM (as the gold standard) agreed the most with each other.
Different nanoparticle families such as liposomes, lipid nanoparticles, mammalian EVs, and bacterial EVs were successfully characterized using this analytical toolbox.
Single particle analysis techniques are less reliable when crude EV samples are tested. We used BSA as a model of non-EV associated protein contaminants. We observed that the free protein concentration must be below 50 µg/mL for scattering and 5 µg/mL for fluorescence NTA to characterize EVs accurately. Therefore, the relevant ratio of EVs compared to other non-EV components is a critical parameter in reliably analyzing crude EV samples.
MSC conditioned media can be successfully characterized throughout each step of the purification process including clarification, tangential flow filtration, and chromatography.
The optimization of labeling and measurement parameters is a critical step to characterize EVs reliably. Here, We provide guidelines on performing systematic and fundamental studies using standard samples and models for both EVs and protein contaminations in the background for any analytical technology.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Superparamagnetic iron oxide (SPIO) nanoparticles with optimized and well-characterized properties are critical for Magnetic Particle Imaging (MPI). MPI is a novel
in vivo
imaging modality that ...promises to integrate the speed of X-ray CT, safety of MRI and sensitivity of PET. Since SPIOs are the source of MPI signal, both the core and surface properties must be optimized to enable efficient
in vivo
imaging with pharmacokinetics tailored for specific imaging applications. Existing SPIOs like Resovist (ferucarbotran) provide a suboptimal MPI signal, and further limit MPI's
in vivo
utility due to rapid systemic clearance. An SPIO agent with a long blood half-life (
t
1/2
) would be a versatile MPI tracer with widespread applications. Here we show that a long circulating polyethylene glycol (PEG)-coated SPIO tracer, LS-008, provides excellent colloidal stability and a persistent intravascular MPI signal, showing its potential as the first blood pool tracer optimized for MPI. We evaluated variations of PEG coating and found that colloidal stability of tracers improved with the increasing PEG molecular weight (keeping PEG loading constant). Blood circulation in mice, evaluated using Magnetic Particle Spectrometry (MPS), showed that the
t
1/2
of SPIO tracers varied with both PEG molecular weight and loading. LS-008, coated with 20 kDa PEG at 18.8% loading capacity, provided the most promising long-term colloidal stability with a
t
1/2
of about 105 minutes in mice.
In vivo
MPI imaging with LS-008 using a 7 T/m/μ
0
3D x-space MPI mouse scanner revealed a prolonged intravascular signal (3-5 hours) post-injection. Our results show the optimized magnetic properties and long systemic retention of LS-008 making it a promising blood pool MPI tracer, with potential to enable MPI imaging in cardio- and cerebrovascular disease models, and solid tumor quantification and imaging
via
enhanced permeation and retention.
Superparamagnetic iron oxide (SPIO) nanoparticles with optimized and well-characterized properties are critical for Magnetic Particle Imaging (MPI).
Non-hemorrhagic brain infarction (BI) is a recognized complication in adults treated with extracorporeal membrane oxygenation (ECMO) and associated with increased mortality. However, predictors of BI ...in these patients are poorly understood. The aim of this study was to identify predictors of BI in ECMO-treated adult patients. We conducted an observational cohort study of all adult patients treated with venovenous or venoarterial (VA) ECMO at our center between 2010 and 2018. The primary endpoint was a computed tomography (CT) verified BI. Logistic regression models were employed to identify BI predictors. In total, 275 patients were included, of whom 41 (15%) developed a BI. Pre-ECMO Simplified Acute Physiology Score III, pre-ECMO cardiac arrest, VA ECMO and conversion between ECMO modes were identified as predictors of BI. In the multivariable analysis, VA ECMO demonstrated independent risk association. VA ECMO also remained the independent BI predictor in a sub-group analysis excluding patients who did not undergo a head CT scan during ECMO treatment. The incidence of BI in adult ECMO patients may be higher than previously believed and is independently associated with VA ECMO mode. Larger prospective trials are warranted to validate these findings and ascertain their clinical significance.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
BACKGROUND AND PURPOSE—Posterior circulation stroke (PCS) accounts for 5% to 19% of patients with acute stroke receiving intravenous thrombolysis. We aimed to compare safety and outcomes following ...intravenous thrombolysis between patients with PCS and anterior circulation stroke (ACS) and incorporate the results in a meta-analysis.
METHODS—We included patients in the Safe Implementation of Treatments in Stroke Thrombolysis Registry 2013 to 2017 with computed tomography/magnetic resonance angiographic occlusion data. Outcomes were parenchymal hematoma, symptomatic intracerebral hemorrhage (SICH) per SITS-MOST (Safe Implementation of Thrombolysis in Stroke Monitoring Study), ECASS II (Second European Co-operative Stroke Study) and NINDS (Neurological Disorders and Stroke definition), 3-month modified Rankin Scale score, and death. Adjustment for SICH risk factors (age, sex, National Institutes of Health Stroke Scale, blood pressure, glucose, and atrial fibrillation) and center was done using inverse probability treatment weighting, after which an average treatment effect (ATE) was calculated. Meta-analysis of 13 studies comparing outcomes in PCS versus ACS after intravenous thrombolysis was conducted.
RESULTS—Of 5146 patients, 753 had PCS (14.6%). Patients with PCS had lower median National Institutes of Health Stroke Scale7 (interquartile range, 4–13) versus 13 (7–18), P<0.001 and fewer cerebrovascular risk factors. In patients with PCS versus ACS, parenchymal hematoma occurred in 3.2% versus 7.9%, ATE (95% CI)−4.7% (−6.3% to 3.0%); SICH SITS-MOST in 0.6% versus 1.9%, ATE−1.4% (−2.2% to −0.7%); SICH NINDS in 3.1% versus 7.8%, ATE−3.0% (−6.3% to 0.3%); SICH ECASS II in 1.8% versus 5.4%, ATE−2.3% (−5.3% to 0.7%). In PCS versus ACS, 3-month outcomes (70% data availability) were death 18.5% versus 20.5%, ATE6.0% (0.7%–11.4%); modified Rankin Scale score 0–1, 45.2% versus 37.5%, ATE1.7% (−6.6% to 3.2%); modified Rankin Scale score 0–2, 61.3% versus 49.4%, ATE2.4% (3.1%–7.9%). Meta-analysis showed relative risk for SICH in PCS versus ACS being 0.49 (95% CI, 0.32–0.75).
CONCLUSIONS—The risk of bleeding complications after intravenous thrombolysis in PCS was half that of ACS, with similar functional outcomes and higher risk of death, acknowledging limitations of the National Institutes of Health Stroke Scale for stroke severity or infarct size adjustment.
Background and purpose
Patients with stroke mimics (SM), i.e. conditions with stroke‐like symptoms, may risk harm if treated with intravenous thrombolysis (IVT). Current guidelines state low risk of ...intracerebral hemorrhage based on studies comprising a total of <400 SM cases. We aimed to compare safety and outcomes following IVT between patients with acute ischaemic stroke and mimicking conditions.
Methods
We included IVT‐treated ischaemic stroke patients in the SITS International Stroke Thrombolysis Register 2003–2017, examined with magnetic resonance imaging 22–36 h after treatment. Outcomes were parenchymal hematoma (PH) after treatment, symptomatic intracerebral hemorrhage (SICH) per Safe Implementation of Thrombolysis in Stroke Monitoring Study (SITS‐MOST), Second European Co‐operative Stroke Study (ECASS II) and National Institutes of Neurological Disorders and Stroke Study (NINDS) criteria, death and modified Rankin Scale score (mRS) at 3 months.
Results
Of 10 436 patients, 429 mimics (4.1%) were identified. The most common types were functional (30.8%), migraine (17.5%) and seizure (14.2%). Patients with mimics had fewer cerebrovascular risk factors and lower median National Institutes of Health Stroke Scale score 7 (interquartile range, 5–10) vs. 8 (5–14), P < 0.001. Among mimics versus stroke patients, PH was seen in 1.2% vs. 5.1% (P < 0.001), SICH NINDS in 0.5% vs. 3.9% (P < 0.001), SICH ECASS II in 0.2% vs. 2.1% (P = 0.007) and SICH SITS‐MOST in 0% vs. 0.5% (P = 0.28). Modified Rankin Scale score 0–1 at 3 months was present in 84.1% vs. 57.7% (P < 0.001) and death within 3 months in 2.6% vs. 5.4% (P = 0.028) of mimics and stroke patients, respectively.
Conclusions
This large observational study indicated that PH and SICH following IVT in patients with SM are uncommon.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Pituitary hormone deficiency occurs in ∼1:4,000 live births. Approximately 3% of the cases are due to mutations in the alpha isoform of POU1F1, a pituitary-specific transcriptional activator. We ...found four separate heterozygous missense variants in unrelated individuals with hypopituitarism that were predicted to affect a minor isoform, POU1F1 beta, which can act as a transcriptional repressor. These variants retain repressor activity, but they shift splicing to favor the expression of the beta isoform, resulting in dominant-negative loss of function. Using a high-throughput splicing reporter assay, we tested 1,070 single-nucleotide variants in POU1F1. We identified 96 splice-disruptive variants, including 14 synonymous variants. In separate cohorts, we found two additional synonymous variants nominated by this screen that co-segregate with hypopituitarism. This study underlines the importance of evaluating the impact of variants on splicing and provides a catalog for interpretation of variants of unknown significance in POU1F1.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The purpose of the European Stroke Organisation–Karolinska Stroke Update Conference is to provide updates on recent stroke therapy research and to give an opportunity for the participants to discuss ...how these results may be implemented into clinical routine. The meeting started 22 years ago as Karolinska Stroke Update, but since 2014 it is a joint conference with European Stroke Organisation. Importantly, it provides a platform for discussion on the European Stroke Organisation guidelines process and on recommendations to the European Stroke Organisation guidelines committee on specific topics. By this, it adds a direct influence from stroke professionals otherwise not involved in committees and work groups on the guideline procedure. The discussions at the conference may also inspire new guidelines when motivated. The topics raised at the meeting are selected by the scientific programme committee mainly based on recent important scientific publications. This year’s European Stroke Organisation–Karolinska Stroke Update Meeting was held in Stockholm on 11–13 November 2018. There were 11 scientific sessions discussed in the meeting including two short sessions. Each session except the short sessions produced a consensus statement (Full version with background, issues, conclusions and references are published as web-material and at www.eso-karolinska.org and http://eso-stroke.org) and recommendations which were prepared by a writing committee consisting of session chair(s), scientific secretary and speakers. These statements were presented to the 250 participants of the meeting. In the open meeting, general participants commented on the consensus statement and recommendations and the final document were adjusted based on the discussion from the general participants Recommendations (grade of evidence) were graded according to the 1998 Karolinska Stroke Update meeting with regard to the strength of evidence. Grade A Evidence: Strong support from randomised controlled trials and statistical reviews (at least one randomised controlled trial plus one statistical review). Grade B Evidence: Support from randomised controlled trials and statistical reviews (one randomised controlled trial or one statistical review). Grade C Evidence: No reasonable support from randomised controlled trials, recommendations based on small randomised and/or non-randomised controlled trials evidence.
Full text
Available for:
NUK, OILJ, SAZU, UKNU, UL, UM, UPUK
Transcranial Focused Ultrasound (tFUS) is a promising new potential neuromodulation tool. However, the safety of tFUS neuromodulation has not yet been assessed adequately. Patients with refractory ...temporal lobe epilepsy electing to undergo an anterior temporal lobe resection present a unique opportunity to evaluate the safety and efficacy of tFUS neuromodulation. Histological changes in tissue after tFUS can be examined after surgical resection, while further potential safety concerns can be assessed using neuropsychological testing.
Neuropsychological functions were assessed in eight patients before and after focused ultrasound sonication of the temporal lobe at intensities up to 5760 mW/cm2. Using the BrainSonix Pulsar 1002, tFUS was delivered under MR guidance, using the Siemens Magnetom 3T Prisma scanner. Neuropsychological changes were assessed using various batteries. Histological changes were assessed using hematoxylin and eosin staining, among others.
With respect to safety, the histological analysis did not reveal any detectable damage to the tissue, except for one subject for whom the histology findings were inconclusive. In addition, neuropsychological testing did not show any statistically significant changes in any test, except for a slight decrease in performance on one of the tests after tFUS.
This study supports the hypothesis that low-intensity Transcranial Focused Ultrasound (tFUS) used for neuromodulation of brain circuits at intensities up to 5760 mW/cm2 may be safe for use in human research. However, due to methodological limitations in this study and inconclusive findings, more work is warranted to establish the safety. Future directions include greater number of sonications as well as longer exposure at higher intensity levels to further assess the safety of tFUS for modulation of neuronal circuits.
•tFUS is a novel brain stimulation technique with not yet fully established safety guidelines.•tFUS was administered to patients electing to undergo resective brain surgery.•tFUS does not appear to cause damage to tissue.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
PDF
