Ankle-targeted exosuit resistance increases paretic propulsion in people post-stroke

BACKGROUND

Individualized, targeted, and intense training is the hallmark of successful gait rehabilitation in people post-stroke. Specifically, increasing use of the impaired ankle to increase propulsion during the stance phase of gait has been linked to higher walking speeds and symmetry. Conventional progressive resistance training is one method used for individualized and intense rehabilitation, but often fails to target paretic ankle plantarflexion during walking. Wearable assistive robots have successfully assisted ankle-specific mechanisms to increase paretic propulsion in people post-stroke, suggesting their potential to provide targeted resistance to increase propulsion, but this application remains underexamined in this population. This work investigates the effects of targeted stance-phase plantarflexion resistance training with a soft ankle exosuit on propulsion mechanics in people post-stroke.

METHODS

We conducted this study in nine individuals with chronic stroke and tested the effects of three resistive force magnitudes on peak paretic propulsion, ankle torque, and ankle power while participants walked on a treadmill at their comfortable walking speeds. For each force magnitude, participants walked for 1 min while the exosuit was inactive, 2 min with active resistance, and 1 min with the exosuit inactive, in sequence. We evaluated changes in gait biomechanics during the active resistance and post-resistance sections relative to the initial inactive section.

RESULTS

Walking with active resistance increased paretic propulsion by more than the minimal detectable change of 0.8 %body weight at all tested force magnitudes, with an average increase of 1.29 ± 0.37 %body weight at the highest force magnitude. This improvement corresponded to changes of 0.13 ± 0.03 N m kg- 1 in peak biological ankle torque and 0.26 ± 0.04 W kg- 1 in peak biological ankle power. Upon removal of resistance, propulsion changes persisted for 30 seconds with an improvement of 1.49 ± 0.58 %body weight after the highest resistance level and without compensatory involvement of the unresisted joints or limb.

CONCLUSIONS

Targeted exosuit-applied functional resistance of paretic ankle plantarflexors can elicit the latent propulsion reserve in people post-stroke. After-effects observed in propulsion highlight the potential for learning and restoration of propulsion mechanics. Thus, this exosuit-based resistive approach may offer new opportunities for individualized and progressive gait rehabilitation.

Measurement of Direct-Photon Cross Section and Double-Helicity Asymmetry at sqrt[s]=510 GeV in p[over →]+p[over →] Collisions

We present measurements of the cross section and double-helicity asymmetry A_{LL} of direct-photon production in p[over →]+p[over →] collisions at sqrt[s]=510  GeV. The measurements have been performed at midrapidity (|η|<0.25) with the PHENIX detector at the Relativistic Heavy Ion Collider. At relativistic energies, direct photons are dominantly produced from the initial quark-gluon hard scattering and do not interact via the strong force at leading order. Therefore, at sqrt[s]=510  GeV, where leading-order-effects dominate, these measurements provide clean and direct access to the gluon helicity in the polarized proton in the gluon-momentum-fraction range 0.02<x<0.08, with direct sensitivity to the sign of the gluon contribution.

Widespread RNA hypoediting in schizophrenia and its relevance to mitochondrial function

RNA editing, the endogenous modification of nucleic acids, is known to be altered in genes with important neurological function in schizophrenia (SCZ). However, the global profile and molecular functions of disease-associated RNA editing remain unclear. Here, we analyzed RNA editing in postmortem brains of four SCZ cohorts and uncovered a significant and reproducible trend of hypoediting in patients of European descent. We report a set of SCZ-associated editing sites via WGCNA analysis, shared across cohorts. Using massively parallel reporter assays and bioinformatic analyses, we observed that differential 3' untranslated region (3'UTR) editing sites affecting host gene expression were enriched for mitochondrial processes. Furthermore, we characterized the impact of two recoding sites in the mitofusin 1 (MFN1) gene and showed their functional relevance to mitochondrial fusion and cellular apoptosis. Our study reveals a global reduction of editing in SCZ and a compelling link between editing and mitochondrial function in the disease.

Abstract 1785: Multi-step engineering of gene-edited CAR T cells using RNA lipid nanoparticles

Autologous chimeric antigen receptor (CAR) T therapies utilize patient cells and can be limited by cell quality, and the high manufacturing burden of viral vectors. As such, there is a need for allogeneic, “off-the-shelf” CAR T cells to make these transformative treatments widely available. However, allogeneic therapies require multiple genetic engineering steps to express CAR and to delete proteins responsible for graft-versus-host disease. Messenger RNA (mRNA) is a promising approach for expression of therapeutic proteins and gene editing nucleases. In this work, we demonstrate a new method for multi-step engineering of gene-edited CAR T cells using RNA lipid nanoparticles (LNPs).

LNPs encapsulating Spy-Cas9 mRNA, TCR and CD52 guide RNA (sgRNA), and CAR mRNA were produced using microfluidics. The CAR construct contained an anti-CD19 scFv binding domain and CD3ζ/4-1BB co-stimulatory domains. Microgram quantities of RNA LNPs were produced to optimize LNP packaging, cargo ratios, and sgRNA combinations. Lead candidates were scaled to milligrams. Purified human primary T cells were cultured, activated, and expanded in serum-free media in plates, flasks and bioreactors. CAR+, TCR− or CD52− cells were generated by addition of the corresponding LNP to activated cells. Cytotoxic killing was determined by co-culture assays with leukemia cells. Gene knockout, CAR expression, viability and cell killing were measured using flow-cytometry.

CD19 CAR was selected as a relevant protein for expression, with TCR and CD52 proteins as gene knockout targets. Single-step addition of CAR LNPs to T cells resulted in transfection efficiencies of 95.0 ± 2.1% and high protein expression. Upon TCR or CD52 LNP addition to T cells, the onset of gene editing was within 48 hours, reaching single target knockout efficiencies of 92.3 ± 3.0% (TCR−), and double knockouts (TCR−/CD52−) of 74.5 ± 6.1%. Similar results were obtained when comparing different LNP batch sizes (microgram to milligram RNA) and cell culture vessels (125,000 to 45 million cells), demonstrating scalability of both the LNP production and cell treatment. Cell viabilities above 90% were maintained at all steps and for all RNA LNPs. Finally, as proof-of-concept for multi-step engineering, sequential addition of TCR LNPs and CAR LNPs resulted in simultaneous CAR expression and TCR gene knockout. These “off-the-shelf” gene-edited CAR T cells were functionally equivalent to non-edited cells in a B cell killing assay, efficiently clearing over 80% of leukemia target cells at a 1:1 ratio.

Our findings demonstrate the advantages of LNPs for RNA delivery to T cells. The simple and gentle nature of LNP cell treatment allows for multiple genetic engineering steps for simultaneous expression and deletion of proteins. Furthermore, LNPs can be easily manufactured using microfluidics, enabling small-scale screening of RNA libraries and rapid scale-up of lead candidates for clinical translation.

Citation Format: Samuel Clarke, R Geczy, A Balgi, S Park, R Zhao, M Swaminathan, R Tieu, N Hoang, C Webb, E Watt, M Wong, M Fujisawa, N Jain, Angela Zhang, Anitha Thomas. Multi-step engineering of gene-edited CAR T cells using RNA lipid nanoparticles [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1785.

Exploratory Investigation of the Effects of Tactile Stimulation Using Air Pressure at the Auricular Vagus Nerve on Heart Rate Variability

OBJECTIVE

To explore the effects of tactile stimulation using air pressure at the auricular branch of the vagus nerve on autonomic activity in healthy individuals.

METHODS

Three types of tactile stimulation were used in this study: continuous low-amplitude, continuous high-amplitude, and pulsed airflow. The tactile stimulations were provided to the cymba concha to investigate autonomic activity in 22 healthy participants. The mean heart rate (HR) and parameters of HR variability, including the standard deviation of R-R intervals (SDNN) and root mean square of successive R-R interval differences (RMSSD) were compared at baseline, stimulation, and recovery periods.

RESULTS

Two-way repeated measures ANOVA indicated a significant main effect of time on HR (p=0.001), SDNN (p=0.003), and RMSSD (p<0.001). These parameters showed significant differences between baseline and stimulation periods and baseline and recovery periods in the post-hoc analyses. There were no significant differences in the changes induced by stimulation type and the interaction between time and stimulation type for all parameters. One-way repeated measures ANOVA showed that HR, SDNN, and RMSSD did not differ significantly among the three time periods during sham stimulation.

CONCLUSION

Parasympathetic activity can be enhanced by auricular tactile stimulation using air pressure, targeting the cymba concha. Further studies are warranted to investigate the optimal stimulation parameters for potential clinical significance.

17-year trends of body mass index, overweight, and obesity among adolescents from 2005 to 2021, including the COVID-19 pandemic: a Korean national representative study

OBJECTIVE

There is a lack of pediatric studies that have analyzed trends in mean body mass index (BMI) and the prevalence of obesity and overweight over a period that includes the mid-stage of the COVID-19 pandemic. Thus, we aimed to investigate trends in BMI, overweight, and obesity among Korean adolescents from 2005 to 2021, including the COVID-19 pandemic.

SUBJECTS AND METHODS

We used data from the Korea Youth Risk Behavior Web-based Survey (KYRBS), which is nationally representative of South Korea. The study included middle- and high-school students between the ages of 12 and 18. We examined trends in mean BMI and prevalence of obesity and/or overweight during the COVID-19 pandemic and compared these to those of pre-pandemic trends in each subgroup by gender, grade, and residential region.

RESULTS

Data from 1,111,300 adolescents (mean age: 15.04 years) were analyzed. The estimated weighted mean BMI was 20.48 kg/m2 (95% CI, 20.46-20.51) between 2005 and 2007, and this was 21.61 kg/m2 (95% CI, 21.54-21.68) in 2021. The prevalence of overweight and obesity was 13.1% (95% CI, 12.9-13.3%) between 2005 and 2007 and 23.4% (95% CI, 22.8-24.0%) in 2021. The mean BMI and prevalence of obesity and overweight have gradually increased over the past 17 years; however, the extent of change in mean BMI and in the prevalence of obesity and overweight during the pandemic was distinctly less than before. The 17-year trends in the mean BMI, obesity, and overweight exhibited a considerable rise from 2005 to 2021; however, the slope during the COVID-19 pandemic (2020-2021) was significantly less prominent than in the pre-pandemic (2005-2019).

CONCLUSIONS

These findings enable us to comprehend long-term trends in the mean BMI of Korean adolescents and further emphasize the need for practical prevention measures against youth obesity and overweight.

Risk of transmission of COVID-19 from healthcare workers returning to work after a 5-day isolation, and kinetics of shedding of viable SARS-CoV-2 variant B.1.1.529 (Omicron)

BACKGROUND

There have been limited data on the risk of onward transmission from individuals with Omicron variant infections who return to work after a 5-day isolation.

AIM

To evaluate the risk of transmission from healthcare workers (HCWs) with Omicron variant who returned to work after a 5-day isolation and the viable-virus shedding kinetics.

METHODS

This investigation was performed in a tertiary care hospital, Seoul, South Korea. In a secondary transmission study, we retrospectively reviewed the data of HCWs confirmed as COVID-19 from March 14^th to April 3^rd, 2022 in units with five or more COVID-19-infected HCWs per week. In the viral shedding kinetics study, HCWs with Omicron variant infection who agreed with daily saliva sampling were enrolled between February and March, 2022.

FINDINGS

Of the 248 HCWs who were diagnosed with COVID-19 within 5 days of the return of an infected HCW, 18 (7%) had contact with the returned HCW within 1-5 days after their return. Of these, nine (4%) had an epidemiologic link other than with the returning HCW, and nine (4%) had contact with the returning HCW, without any other epidemiologic link. In the study of the kinetics of virus shedding (N = 32), the median time from symptom onset to negative conversion of viable virus was four days (95% confidence interval: 3-5).

CONCLUSION

Our data suggest that the residual risk of virus transmission after 5 days of isolation following diagnosis or symptom onset is low.

RESEAT: Recurrent Self-Attention Network for Multi-regional Influenza Forecasting

Early forecasting of influenza is an important task for public health to reduce losses due to influenza. Various deep learning-based models for multi-regional influenza forecasting have been proposed to forecast future influenza occurrences in multiple regions. While they only use historical data for forecasting, temporal and regional patterns need to be jointly considered for better accuracy. Basic deep learning models such as recurrent neural networks and graph neural networks have limited ability to model both patterns together. A more recent approach uses an attention mechanism or its variant, self-attention. Although these mechanisms can model regional interrelationships, in state-of-the-art models, they consider accumulated regional interrelationships based on attention values that are calculated only once for all of the input data. This limitation makes it difficult to effectively model the regional interrelationships that change dynamically during that period. Therefore, in this paper, we propose a recurrent self-attention network (RESEAT) for various multi-regional forecasting tasks such as influenza and electrical load forecasting. The model can learn regional interrelationships over the entire period of the input data using self-attention, and it recurrently connects the attention weights using message passing. We demonstrate through extensive experiments that the proposed model outperforms other state-of-the-art forecasting models in terms of the forecasting accuracy for influenza and COVID-19. We also describe how to visualize regional interrelationships and analyze the sensitivity of hyperparameters to forecasting accuracy.

Relationships between dietary diversity and gut microbial diversity in the elderly

Diet is considered as a major driver of gut microbiota composition. However, little is known about the relationship between overall dietary balance and gut microbiota, especially in the elderly. Here, using the Quantitative Index for Dietary Diversity (QUANTIDD), we analysed the relationships between dietary diversity and gut microbiota diversity in 445 Japanese subjects aged 65-90 years. We also examined the effect of age by comparing the young-old group aged 65 to 74 years (<75 years group; n=246) and the old-old group aged 75 years and older (≥75 years group; n=199). QUANTIDD showed significant positive relationships with Pielou's evenness and Shannon indices, two α-diversity indices related to the uniformity of species distribution. This suggests that a more diverse diet is associated with a more uniform abundance of various bacterial groups, rather than a greater variety of gut bacteria. QUANTIDD also showed significant positive associations with the abundance of Anaerostipes, Eubacterium eligens group, and Eubacterium ventriosum group, which produce short-chain fatty acids (SCFAs) and are beneficial to health. Negative association was found with the abundance of Ruminococcus gnavus group, which produces inflammatory polysaccharides. Positive associations between QUANTIDD and α-diversity indices or the abundance of specific bacterial groups were identified among all subjects and in the <75 years group, but not in the ≥75 years group. Our results suggest that dietary diversity contributes to the diversity of the gut microbiota and increases the abundance of SCFAs-producing bacteria, but only up to a certain age. These findings help to understand the complex relationship between diet and gut microbiota, and provide hints for specific dietary interventions to promote beneficial gut microbiota in the elderly.

Infants born preterm demonstrate reduced task-specific exploration during the scaffolded kick-activated mobile task

This study quantified the spatial exploration of 13 infants born very and extremely preterm (PT) at 4 months corrected age as they learned that moving their feet vertically to cross a virtual threshold activated an infant kick-activated mobile and compared results to 15 infants born full-term (FT) from a previously published study. Spatial exploration was quantified using two general spatial exploration variables (exploration volume, exploration path), two task-specific spatial variables (duration of time in the task-specific region of interest, vertical variance of kicks), and one non-task-specific spatial variable (horizontal variance of kicks). The infants born PT, similar to FT, increased their general spatial exploration and duration in the region of interest and did not change the vertical and horizontal variances of kicks. However, the infants born PT, compared to FT, spent less time in the task-specific region of interest and had a greater non-task-specific horizontal variance throughout the task. This may indicate that infants born PT and FT exhibit similar general spatial exploration, but infants born PT exhibit less task-specific spatial exploration. Future research is necessary to determine the contribution of learning and motor abilities to the differences in task-specific exploration between infants born PT and FT.

Analysis of Electrochemical Performance with Dispersion Degree of CNTs in Electrode According to Ultrasonication Process and Slurry Viscosity for Lithium-Ion Battery

Lithium-ion batteries (LIBs) continue to dominate the battery market with their efficient energy storage abilities and their ongoing development. However, at high charge/discharge C-rates their electrochemical performance decreases significantly. To improve the power density properties of LIBs, it is important to form a uniform electron transfer network in the cathode electrode via the addition of conductive additives. Carbon nanotubes (CNTs) with high crystallinity, high electrical conductivity, and high aspect ratio properties have gathered significant interest as cathode electrode conductive additives. However, due to the high aggregational properties of CNTs, it is difficult to form a uniform network for electron transfer within the electrode. In this study, to help fabricate electrodes with well-dispersed CNTs, various electrodes were prepared by controlling (i) the mixing order of the conductive material, binder, and active material, and (ii) the sonication process of the CNTs/NMP solution before the electrode slurry preparation. When the binder was mixed with a well sonicated CNTs/NMP solution, the CNTs uniformly adsorbed to the then added cathode material of LiNi0.6Co0.2Mn0.2O2 and were well-dispersed to form a flowing uniform network. This electrode fabrication process achieved > 98.74% capacity retention after 50 cycles at 5C via suppressed polarization at high current densities and a more reversible H1-M phase transition of the active material. Our study presents a novel design benchmark for the fabricating of electrodes applying well-dispersed CNTs, which can facilitate the application of LIBs in high current density applications.

The global burden of sudden infant death syndrome from 1990 to 2019: a systematic analysis from the Global Burden of Disease study 2019

BACKGROUND

Sudden infant death syndrome (SIDS) still remains one of the leading causes of infant death worldwide, especially in high-income countries. To date, however, there is no detailed information on the global health burden of SIDS.

AIMS

To characterize the global disease burden of SIDS and its trends from 1990 to 2019 and to compare the burden of SIDS according to the socio-demographic index (SDI).

DESIGN

Systematic analysis based on the Global Burden of Disease (GBD) 2019 data.

METHODS

Epidemiological data of 204 countries from 1990 to 2019 were collected via various methods including civil registration and vital statistics in the original GBD study. Estimates for mortality and disease burden of SIDS were modeled. Crude mortality and mortality rates per 100 000 population were analyzed. Disability-adjusted life years (DALYs) and DALY rates were also assessed.

RESULTS

In 2019, mortality rate of SIDS accounted for 20.98 [95% Uncertainty Interval, 9.15-46.16] globally, which was a 51% decrease from 1990. SIDS was most prevalent in Western sub-Saharan Africa, High-income North America and Oceania in 2019. The burden of SIDS was higher in males than females consistently from 1990 to 2019. Higher SDI and income level was associated with lower burden of SIDS; furthermore, countries with higher SDI and income had greater decreases in SIDS burden from 1990 to 2019.

CONCLUSIONS

The burden of SIDS has decreased drastically from 1990 to 2019. However, the improvements have occurred disproportionately between regions and SDI levels. Focused preventive efforts in under-resourced populations are needed.

Genetic analysis of Korean non-ischemic dilated cardiomyopathy using next generation sequencing

Background

Non-ischemic dilated cardiomyopathy (NIDCM) is a genetic disorder that causes heart failure and life-threatening arrhythmia. However, there has been no study about the up-to-date genetic analysis for NIDCM in Korean. Therefore, we performed the genetic analysis of Korean NIDCM patients (pts) using next generation sequencing (NGS).

Methods

We analyzed clinical and echocardiographic data of 203 NIDCM in a single center from July 2017 to May 2020. All pts underwent NGS analysis with customized panel including 369 genes. Genetic variants were classified as pathogenic, likely pathogenic mutations or variants of uncertain significance regarding American College of Medical Genetics guideline.

Results

A total of 203 NIDCM pts (57±15 years old, 32.0% male, LVEF 28%) had NGS analysis. Thirty-seven (18.2%) pts had pathogenic or likely pathogenic mutations. The most prevalent mutated genes were TTN (n=16, 43.2%). TNNT2 (n=6, 16.2%), MYBPC3 (n=6, 16.2%) and MYH7 (n=3, 8.1%) mutated genes were common in the following order. The patients with positive panel mutation had no significant difference in initial LVEF (27% vs. 28%, p=0.216) and prevalence of atrial fibrillation (37.8% vs. 44.6%, p=0.454) compared with patients with negative panel mutation. During the median follow-up period of 40 months, there was no significant difference in composite outcome (all-cause death, heart transplantation, LVAD, heart failure re-admission, fatal arrhythmia) (35.3% vs. 32.2%, p=0.729) or presence of improved EF (≥10 points increase from baseline LVEF, and a second measurement of LVEF &gt;40%) (41.2% vs. 50.0%, p=0.354) between the two groups.

Conclusion

This is the first study of NGS analysis in Korean NIDCM pts. We could find disease-related pathogenic or likely pathogenic mutations in 18.2% NIDCM patients. Further prospective, large study should be warranted to elucidate the effect of genetic mutation in clinical manifestation and prognosis of NIDCM in Korean population.

Funding Acknowledgement

Type of funding sources: None.

Diagnosis of coronary layered plaque by deep learning

Background/Introduction

Healed coronary plaques, morphologically characterized by a layered pattern, are signatures of previous plaque disruption and healing. Recent optical coherence tomography (OCT) studies showed that layered plaque is associated with vascular vulnerability and rapid plaque progression. However, the diagnosis of layered plaque requires expertise in OCT image interpretation and is susceptible to interobserver variability.

Purpose

We aimed to develop a deep learning (DL) model for an accurate diagnosis of layered plaque.

Methods

We developed a Visual Transformer (ViT)-based DL model emulating the cardiologists who review consecutive OCT frames to make a diagnosis (Figure 1), and compared it to the standard convolutional neural network (CNN) model. We used 302,415 cross-sectional OCT images from 873 patients collected from 9 sites: 237,021 images from 581 patients for training and internal validation from 8 sites, and 65394 images from 292 patients collected from another site for external validation.

Results

Model performances were evaluated using the area under the receiver operating characteristics (AUC). In the five-fold cross validation, the ViT-based model showed better performance than the standard CNN-based model with AUC of 0.886 (95% confidence interval [CI], 0.882–0.891) compared with 0.797 (95% CI, 0.790–0.804). The ViT-based model also outperformed the standard CNN-based model in the external validation, with an AUC of 0.857 (95% CI, 0.849–0.864) compared to 0.806 (95% CI, 0.797–0.815) (Figure 2).

Conclusion(s)

The ViT-based DL model will help cardiologists to make an accurate diagnosis of layered plaque, which might help to stratify the risk of future adverse cardiac events.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Mrs. Gillian Gray through the Allan Gray Fellowship Fund in Cardiology