Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
2,435
result(s) for
"Gerber, M."
Sort by:
Non-Sinusoidal Activity Can Produce Cross-Frequency Coupling in Cortical Signals in the Absence of Functional Interaction between Neural Sources
The analysis of cross-frequency coupling (CFC) has become popular in studies involving intracranial and scalp EEG recordings in humans. It has been argued that some cases where CFC is mathematically present may not reflect an interaction of two distinct yet functionally coupled neural sources with different frequencies. Here we provide two empirical examples from intracranial recordings where CFC can be shown to be driven by the shape of a periodic waveform rather than by a functional interaction between distinct sources. Using simulations, we also present a generalized and realistic scenario where such coupling may arise. This scenario, which we term waveform-dependent CFC, arises when sharp waveforms (e.g., cortical potentials) occur throughout parts of the data, in particular if they occur rhythmically. Since the waveforms contain both low- and high-frequency components, these components can be inherently phase-aligned as long as the waveforms are spaced with appropriate intervals. We submit that such behavior of the data, which seems to be present in various cortical signals, cannot be interpreted as reflecting functional modulation between distinct neural sources without additional evidence. In addition, we show that even low amplitude periodic potentials that cannot be readily observed or controlled for, are sufficient for significant CFC to occur.
Journal Article
Visuo-acoustic stimulation that helps you to relax: A virtual reality setup for patients in the intensive care unit
After prolonged stay in an intensive care unit (ICU) patients often complain about cognitive impairments that affect health-related quality of life after discharge. The aim of this proof-of-concept study was to test the feasibility and effects of controlled visual and acoustic stimulation in a virtual reality (VR) setup in the ICU. The VR setup consisted of a head-mounted display in combination with an eye tracker and sensors to assess vital signs. The stimulation consisted of videos featuring natural scenes and was tested in 37 healthy participants in the ICU. The VR stimulation led to a reduction of heart rate (p = 0. 049) and blood pressure (p = 0.044). Fixation/saccade ratio (p < 0.001) was increased when a visual target was presented superimposed on the videos (reduced search activity), reflecting enhanced visual processing. Overall, the VR stimulation had a relaxing effect as shown in vital markers of physical stress and participants explored less when attending the target. Our study indicates that VR stimulation in ICU settings is feasible and beneficial for critically ill patients.
Journal Article
Global ocean storage of anthropogenic carbon
The global ocean is a significant sink for anthropogenic carbon (Cant), absorbing roughly a third of human CO2 emitted over the industrial period. Robust estimates of the magnitude and variability of the storage and distribution of Cant in the ocean are therefore important for understanding the human impact on climate. In this synthesis we review observational and model-based estimates of the storage and transport of Cant in the ocean. We pay particular attention to the uncertainties and potential biases inherent in different inference schemes. On a global scale, three data-based estimates of the distribution and inventory of Cant are now available. While the inventories are found to agree within their uncertainty, there are considerable differences in the spatial distribution. We also present a review of the progress made in the application of inverse and data assimilation techniques which combine ocean interior estimates of Cant with numerical ocean circulation models. Such methods are especially useful for estimating the air–sea flux and interior transport of Cant, quantities that are otherwise difficult to observe directly. However, the results are found to be highly dependent on modeled circulation, with the spread due to different ocean models at least as large as that from the different observational methods used to estimate Cant. Our review also highlights the importance of repeat measurements of hydrographic and biogeochemical parameters to estimate the storage of Cant on decadal timescales in the presence of the variability in circulation that is neglected by other approaches. Data-based Cant estimates provide important constraints on forward ocean models, which exhibit both broad similarities and regional errors relative to the observational fields. A compilation of inventories of Cant gives us a \"best\" estimate of the global ocean inventory of anthropogenic carbon in 2010 of 155 ± 31 PgC (±20% uncertainty). This estimate includes a broad range of values, suggesting that a combination of approaches is necessary in order to achieve a robust quantification of the ocean sink of anthropogenic CO2.
Journal Article
Investigating the role of auditory and visual sensory inputs for inducing relaxation during virtual reality stimulation
Stress is a part of everyday life which can be counteracted by evoking the relaxation response via nature scenes presented using immersive virtual reality (VR). The aim of this study was to determine which sensory aspect of immersive VR intervention is responsible for the greatest relaxation response. We compared four conditions: auditory and visual combined (audiovisual), auditory only, visual only, and no artificial sensory input. Physiological changes in heart rate, respiration rate, and blood pressure were recorded, while participants reported their preferred condition and awareness of people, noise, and light in the real-world. Over the duration of the stimulation, participants had the lowest heart rate during the audiovisual and visual only conditions. They had the steadiest decrease in respiration rate and the lowest blood pressure during the audiovisual condition, compared to the other conditions, indicating the greatest relaxation. Moreover, ratings of awareness indicated that participants reported being less aware of their surroundings (i.e., people, noise, light, real environment) during the audiovisual condition versus the other conditions (p < 0.001), with a preference for audiovisual inputs. Overall, the use of audiovisual VR stimulation is more effective at inducing a relaxation response compared to no artificial sensory inputs, or the independent inputs.
Journal Article
Preventing respiratory illness in cerebral palsy: Results of a pilot randomized controlled trial
Respiratory illness is consistently the leading cause of death and hospitalization in severe cerebral palsy (CP). Respiratory Exacerbations-Plan for Action and Care Transitions (RE-PACT) is a just-in-time adaptive intervention to prevent respiratory illness in severe CP. RE-PACT combines early illness detection with rapid clinical response to address varying causes of respiratory illness early enough to modify illness trajectory. This study's objective was to determine RE-PACT's feasibility, acceptability, fidelity, and estimated effect size.
This two-site randomized controlled trial occurred from April 2022-February 2024 in demographically and geographically distinct locations. Caregiver-child pairs were recruited from complex care programs, and children had both gross motor function classification system level 4-5 CP and either pulmonologist care or daily respiratory treatments. Children were randomized to usual care or RE-PACT for six months. Primary outcomes were feasibility, acceptability, and fidelity measures having a priori definitions of success. The primary clinical outcome was the severe respiratory illness (SRI) event rate, defined as hospitalizations due to respiratory diagnoses. Clinicaltrials.gov registration is NCT05292365.
Sixty children were enrolled, of which 26 were randomized into RE-PACT. Measures confirmed RE-PACT's feasibility, acceptability, and fidelity, e.g., text message response rates were 97.5%, and no action planning or clinical responder activities were missed. System usability scale scores were \"good to excellent\" (mean [SD], 79.5 [11.7]). The RE-PACT SRI event rate (95% confidence interval, CI) was 0.71 (0.36-1.14) per person-year compared to the usual care event rate 1.08 (0.61-1.91) per person-year, a risk ratio of 0.66 (0.28-1.56). Secondary outcomes and qualitative data reinforced RE-PACT's positive impact.
RE-PACT is a feasible, acceptable intervention that can be delivered with high fidelity to diverse families caring for children with severe CP. These data inform the sample and design characteristics needed for efficacy testing of RE-PACT's ability to prevent severe respiratory illness.
Journal Article
Regulation of human hematopoietic stem cell self-renewal by the microenvironment’s control of retinoic acid signaling
The high expression of aldehyde dehydrogenase 1, also known as retinaldehyde dehydrogenase, by hematopoietic stem cells (HSCs) suggests an important role for retinoic acid (RA) signaling in determining the fate of these cells. We found that primitive human bone marrow-derived CD34 ⁺CD38 ⁻ cells not only highly express aldehyde dehydrogenase 1, but also the RA receptor α. Despite the up-regulation of early components of RA signaling, the downstream pathway remained inactive in the primitive CD34 ⁺CD38 ⁻ cells. Primitive hematopoietic cells rapidly undergo terminal differentiation when cultured away from their microenvironment; however, we found that inhibition of RA signaling maintained their primitive phenotype and function, and promoted their self-renewal. HSCs reside in a complex microenvironment that enforces the balance between self-renewal and differentiation. The exact physiologic mechanisms by which the niche controls HSC fate remain elusive. The embryonic gonadal microenvironment has recently been shown to determine germ-cell fate by degrading RA through expression of the P450 retinoid-inactivating enzyme CYP26B1. We found that the bone marrow microenvironment similarly can control primitive hematopoietic cell fate via modulation of retinoid bioavailability. Accordingly, we found that bone marrow stromal cell CYP26 was also able to inactivate retinoids in serum, preventing RA signaling. Thus, primitive hematopoietic cells appear to be intrinsically programmed to undergo RA-mediated differentiation unless prevented from doing so by bone marrow niche CYP26. Modulation of RA signaling also holds promise for clinical HSC expansion, a prerequisite for the wide-scale use of these cells in regenerative medicine and gene therapy.
Journal Article
Unobtrusive measurement of gait parameters using seismographs: An observational study
Analyzing irregularities in walking patterns helps detect human locomotion abnormalities that can signal health changes. Traditional observation-based assessments have limitations due to subjective biases and capture only a single time point. Ambient and wearable sensor technologies allow continuous and objective locomotion monitoring but face challenges due to the need for specialized expertise and user compliance. This work proposes a seismograph-based algorithm for quantifying human gait, incorporating a step extraction algorithm derived from mathematical morphologies, with the goal of achieving the accuracy of clinical reference systems. To evaluate our method, we compared the gait parameters of 50 healthy participants, as recorded by seismographs, and those obtained from reference systems (a pressure-sensitive walkway and a camera system). Participants performed four walking tests, including traversing a walkway and completing the timed up-and-go (TUG) test. In our findings, we observed linear relationships with strong positive correlations (
R
2
> 0.9) and tight 95% confidence intervals for all gait parameters (step time, cycle time, ambulation time, and cadence). We demonstrated that clinical gait parameters and TUG mobility test timings can be accurately derived from seismographic signals, with our method exhibiting no significant differences from established clinical reference systems.
Journal Article
Leucine Rich α-2 Glycoprotein: A Novel Neutrophil Granule Protein and Modulator of Myelopoiesis
Leucine-rich α2 glycoprotein (LRG1), a serum protein produced by hepatocytes, has been implicated in angiogenesis and tumor promotion. Our laboratory previously reported the expression of LRG1 in murine myeloid cell lines undergoing neutrophilic granulocyte differentiation. However, the presence of LRG1 in primary human neutrophils and a role for LRG1 in regulation of hematopoiesis have not been previously described. Here we show that LRG1 is packaged into the granule compartment of human neutrophils and secreted upon neutrophil activation to modulate the microenvironment. Using immunofluorescence microscopy and direct biochemical measurements, we demonstrate that LRG1 is present in the peroxidase-negative granules of human neutrophils. Exocytosis assays indicate that LRG1 is differentially glycosylated in neutrophils, and co-released with the secondary granule protein lactoferrin. Like LRG1 purified from human serum, LRG1 secreted from activated neutrophils also binds cytochrome c. We also show that LRG1 antagonizes the inhibitory effects of TGFβ1 on colony growth of human CD34+ cells and myeloid progenitors. Collectively, these data invoke an additional role for neutrophils in innate immunity that has not previously been reported, and suggest a novel mechanism whereby neutrophils may modulate the microenvironment via extracellular release of LRG1.
Journal Article
A Usability Pilot Study of a Sensor-Guided Interactive System for Dexterity Training in Parkinson’s Disease
This pilot study aimed to evaluate the usability of a new, feedback-based dexterity training system in people with Parkinson’s disease (PwPD) and healthy adults. Seven PwPD and seven healthy adults participated in the study. The System Usability Scale (SUS) and the Post-Study System Usability Questionnaire Version 3 (PSSUQ) were used to assess usability. Additionally, the feedback shown as a counter, detected through newly developed algorithms, was evaluated by comparing the device-detected repetitions during six exercises to those counted by a supervisor. High median SUS scores of 92.5 were obtained in both PwPD (IQR = 81.25–98.75) and healthy adults (IQR = 87.5–93.75, maximum score 100, minimum score 0). Similarly, high PSSUQ median scores were achieved after the session (1.14, IQR = 1.00–1.33, PD; 1.08, IQR = 1.00–1.58, healthy adults, maximum score 1, minimum score 7). PwPD completed 648 repetitions, with 551 (85%) correctly recognized by the system. For healthy adults, 883 out of 913 (97%) repetitions were classified as right. The present study showed high usability and high perceived user satisfaction for the new training system in all study participants. The system effectively detects exercise repetition rates but requires further refinement to enhance accuracy for specific pinch grip exercises.
Journal Article