Brillouin microscopy monitors rapid responses in subcellular compartments.

Measurements and imaging of the mechanical response of biological cells are critical for understanding the mechanisms of many diseases, and for fundamental studies of energy, signal and force transduction. The recent emergence of Brillouin microscopy as a powerful non-contact, label-free way to non-invasively and non-destructively assess local viscoelastic properties provides an opportunity to expand the scope of biomechanical research to the sub-cellular level. Brillouin spectroscopy has recently been validated through static measurements of cell viscoelastic properties, however, fast (sub-second) measurements of sub-cellular cytomechanical changes have yet to be reported. In this report, we utilize a custom multimodal spectroscopy system to monitor for the very first time the rapid viscoelastic response of cells and subcellular structures to a short-duration electrical impulse. The cytomechanical response of three subcellular structures - cytoplasm, nucleoplasm, and nucleoli - were monitored, showing distinct mechanical changes despite an identical stimulus. Through this pioneering transformative study, we demonstrate the capability of Brillouin spectroscopy to measure rapid, real-time biomechanical changes within distinct subcellular compartments. Our results support the promising future of Brillouin spectroscopy within the broad scope of cellular biomechanics.

A systematic review of the literature reporting on remote monitoring epileptic seizure detection devices.

BACKGROUND: Early detection and alert notification of an impending seizure for people with epilepsy have the potential to reduce Sudden Unexpected Death in Epilepsy (SUDEP). Current remote monitoring seizure detection devices for people with epilepsy are designed to support real-time monitoring of their vital health parameters linked to seizure alert notification. An understanding of the rapidly growing literature on remote seizure detection devices is essential to address the needs of people with epilepsy and their carers. AIM: This review aims to examine the technical characteristics, device performance, user preference, and effectiveness of remote monitoring seizure detection devices. METHODOLOGY: A systematic review referenced to PRISMA guidelines was used. RESULTS: A total of 1095 papers were identified from the initial search with 30 papers included in the review. Sixteen non-invasive remote monitoring seizure detection devices are currently available. Such seizure detection devices were found to have inbuilt intelligent sensor functionality to monitor electroencephalography, muscle movement, and accelerometer-based motion movement for detecting seizures remotely. Current challenges of these devices for people with epilepsy include skin irritation due to the type of patch electrode used and false alarm notifications, particularly during physical activity. The tight-fitted accelerometer-type devices are reported as uncomfortable from a wearability perspective for long-term monitoring. Also, continuous recording of physiological signals and triggering alert notifications significantly reduce the battery life of the devices. The literature highlights that 3.2 out of 5 people with epilepsy are not using seizure detection devices because of the cost and appearance of the device. CONCLUSION: Seizure detection devices can potentially reduce morbidity and mortality for people with epilepsy. Therefore, further collaboration of clinicians, technical experts, and researchers is needed for the future development of these devices. Finally, it is important to always take into consideration the expectations and requirements of people with epilepsy and their carers to facilitate the next generation of remote monitoring seizure detection devices.

Assessment of DNA fibers to track replication dynamics.

DNA replication is a complex and tightly regulated process that must proceed accurately and completely if the cell is to faithfully transmit genetic material to its progeny. Organisms have thus evolved complex mechanisms to deal with the myriad exogenous and endogenous sources of replication impediments to which the cell is subject. These mechanisms are of particular relevance to cancer biology, given that such "replication stress" frequently foreshadows genome instability during cancer pathogenesis, and that many traditional chemotherapies and a number of precision medicines function by interfering with the progress of DNA replication. Visualization of the progress and dynamics of DNA replication in living cells was historically a major challenge, neatly surmounted by the development of DNA fiber assays that utilize the fluorescent detection of halogenated nucleotides to track replication forks at single-molecule resolution. This methodology has been widely applied to study the dynamics of unperturbed DNA replication, as well as the cellular responses to various replication stress scenarios. In recent years, subtle modifications to DNA fiber assays have facilitated assessment of the stability of nascent DNA at stalled replication forks, as well as the detection of single-stranded DNA gaps and their subsequent filling by error-prone polymerases. Here, we present and discuss several iterations of the fiber assay and suggest methodologies for the analysis of the data obtained.

Adaptation of the Strength and Difficulties Questionnaire for Use in the Republic of Georgia.

Background: Children in low-resource countries like Georgia often have limited access to assessment measures for mental health care services. This study adapts and validates the mental health screening tool the Strength and Difficulties Questionnaire for use in Georgian children. Methods: A total of 16 654 children were assessed by a parent and/or teacher using Georgian-adapted Strength and Difficulties Questionnaire. Receiver operating characteristic analyses were performed to assess the discriminative validity of the Strength and Difficulties Questionnaires and to establish an optimal cutoff score. Results: Data from 15 738 parents- and 13 560 teachers-administered Strength and Difficulties Questionnaire were analyzed. The internal consistency analysis showed Cronbach's alpha to be 0.625 and 0.621 for parent- and teacher-administered Strength and Difficulties Questionnaire, respectively. The area under the curve (95% CI) shows that the Strength and Difficulties Questionnaire can differentiate risk group children from typically developing peers: parent-administered questionnaires-0.629 (0.556-0.702) and teacher-administered questionnaires-0.680 (0.611-0.789). Parent-administered Strength and Difficulties Questionnaire has a cutoff value of 16 or more with 92.5% of sensitivity and teacher-administered Strength and Difficulties Questionnaire-14 or more with a sensitivity of 85.6%. Conclusion: The study finds that the Strength and Difficulties Questionnaire is a valid screening instrument and does not depend on the informant-parent or teacher. It suggests that with appropriate cultural adaptation, the SDQ can be used in the Republic of Georgia to identify children at risk for mental disorders and help guide resource allocation.

The relation of subjective experience to cognitive processing.

Barzykowski and Moulin argue that common memory processes form the basis of involuntary autobiographical memory and the déjà vu experience. We think that they underemphasize the potential dissociability between processes that enact retrieval and the processes that produce conscious experience. We propose that retrieval and conscious experience result from different processes in both involuntary autobiographical memory and déjà vu experiences.

Effect of nanosecond pulsed electric fields (nsPEFs) on coronavirus survival.

Previous work demonstrated inactivation of influenza virus by GHz frequency electromagnetic fields. Despite theoretical and experimental results, the underlying mechanism driving this inactivation remains unknown. One hypothesis is that the electromagnetic field is causing damage to the virion membrane (and therefore changing spike protein orientation) rendering the virus unable to attach and infect host cells. Towards examining this hypothesis, our group employed nanosecond pulsed electric fields (nsPEFs) as a surrogate to radiofrequency (RF) exposure to enable exploration of dose response thresholds of electric field-induced viral membrane damage. In summary, Bovine coronavirus (BCoV) was exposed, in suspension, to mono and bipolar 600-ns pulsed electric fields (nsPEFs) at two amplitudes (12.5 and 25 kV/cm) and pulse numbers [0 (sham), 1, 5, 10, 100, and 1000] at a 1 Hz (Hz) repetition rate. The temperature rise immediately after exposure(s) was measured using thermocouples to differentiate effects of the electric field (E-field) and heating (i.e., the thermal gradient). Inactivation of BCoV was evaluated by infecting HRT-18G host cells and assessing differences in virus infectivity days after exposure. Our results show that 600 nsPEFs, both bipolar and monopolar, can reduce the infectivity of coronaviruses at various amplitudes, pulse numbers, and pulse polarity. Interestingly, we observed that bipolar exposures appeared to be more efficient at lower exposure intensities than monopolar pulses. Future work should focus on experiments to identify the mechanism underlying nsPEF-induced viral inactivation.

Control of the Electroporation Efficiency of Nanosecond Pulses by Swinging the Electric Field Vector Direction.

Reversing the pulse polarity, i.e., changing the electric field direction by 180°, inhibits electroporation and electrostimulation by nanosecond electric pulses (nsEPs). This feature, known as "bipolar cancellation," enables selective remote targeting with nsEPs and reduces the neuromuscular side effects of ablation therapies. We analyzed the biophysical mechanisms and measured how cancellation weakens and is replaced by facilitation when nsEPs are applied from different directions at angles from 0 to 180°. Monolayers of endothelial cells were electroporated by a train of five pulses (600 ns) or five paired pulses (600 + 600 ns) applied at 1 Hz or 833 kHz. Reversing the electric field in the pairs (180° direction change) caused 2-fold (1 Hz) or 20-fold (833 kHz) weaker electroporation than the train of single nsEPs. Reducing the angle between pulse directions in the pairs weakened cancellation and replaced it with facilitation at angles <160° (1 Hz) and <130° (833 kHz). Facilitation plateaued at about three-fold stronger electroporation compared to single pulses at 90-100° angle for both nsEP frequencies. The profound dependence of the efficiency on the angle enables novel protocols for highly selective focal electroporation at one electrode in a three-electrode array while avoiding effects at the other electrodes. Nanosecond-resolution imaging of cell membrane potential was used to link the selectivity to charging kinetics by co- and counter-directional nsEPs.

Image Clarity Affects Tip-of-the-Tongue Rates for Faces.

Tip-of-the-tongue states are subjective experiences that unrecalled target words will be remembered. This study investigates if the visual fluency of familiar faces affects the likelihood of tip-of-the-tongue experiences (TOTs) as well as name recall and name recognition. To manipulate visual fluency, three levels of clarity for 396 celebrity faces were set: high, medium, and low clarity. Four hundred and twenty-nine participants were asked to recall the last names of the celebrities for all clarity levels, and, if they did not recall, to indicate if they experienced a TOT. Following the TOT question, they performed a name recognition test. Results showed that higher-clarity faces resulted in higher TOT rates than lower-clarity faces for unrecalled faces. Name recall was also higher for clearer faces. However, clarity level did not affect the correct answer rate on the name recognition test. These results support the view that perceptual cue-based factors influence TOT experiences.

Evaluation of inactivation of bovine coronavirus by low-level radiofrequency irradiation.

Inactivation of influenza A virus by radiofrequency (RF) energy exposure at levels near Institute of Electrical and Electronics Engineers (IEEE) safety thresholds has been reported. The authors hypothesized that this inactivation was through a structure-resonant energy transfer mechanism. If this hypothesis is confirmed, such a technology could be used to prevent transmission of virus in occupied public spaces where RF irradiation of surfaces could be performed at scale. The present study aims to both replicate and expand the previous work by investigating the neutralization of bovine coronavirus (BCoV), a surrogate of SARS-CoV-2, by RF radiation in 6-12 GHz range. Results showed an appreciable reduction in BCoV infectivity (up to 77%) due to RF exposure to certain frequencies, but failed to generate enough reduction to be considered clinically significant.

Rapid and precise tracking of water influx and efflux across cell membranes induced by a pulsed electric field.

Quantitative measurements of water content within a single cell are notoriously difficult. In this work, we introduce a single-shot optical method for tracking the intracellular water content, by mass and volume, of a single cell at video rate. We utilize quantitative phase imaging and a priori knowledge of a spherical cellular geometry, leveraging a two-component mixture model to compute the intracellular water content. We apply this technique to study CHO-K1 cells responding to a pulsed electric field, which induces membrane permeabilization and rapid water influx or efflux depending upon the osmotic environment. The effects of mercury and gadolinium on water uptake in Jurkat cells following electropermeabilization are also examined.

Evaluation of Viral Inactivation on Dry Surface by High Peak Power Microwave (HPPM) Exposure.

Previous research has shown that virus infectivity can be dramatically reduced by radio frequency exposure in the gigahertz (GHz) frequency range. Given the worldwide SARS-CoV-2 pandemic, which has caused over 1 million deaths and has had a profound global economic impact, there is a need for a noninvasive technology that can reduce the transmission of virus among humans. RF is a potential wide area-of-effect viral decontamination technology that could be used in hospital rooms where patients are expelling virus, in grocery and convenience stores where local populations mix, and in first responder settings where rapid medical response spans many potentially infected locations within hours. In this study, we used bovine coronavirus (BCoV) as a surrogate of SARS-CoV-2 and exposed it to high peak power microwave (HPPM) pulses at four narrowband frequencies: 2.8, 5.6, 8.5, and 9.3 GHz. Exposures consisted of 2 µs pulses delivered at 500 Hz, with pulse counts varied by decades between 1 and 10,000. The peak field intensities (i.e. the instantaneous power density of each pulse) ranged between 0.6 and 6.5 MW/m2 , depending on the microwave frequency. The HPPM exposures were delivered to plastic coverslips containing BCoV dried on the surface. Hemagglutination (HA) and cytopathic effect analyses were performed 6 days after inoculation of host cells to assess viral infectivity. No change in viral infectivity was seen with increasing dose (pulse number) across the tested frequencies. Under all conditions tested, exposure did not reduce infectivity more than 1.0 log10. For the conditions studied, high peak power pulsed RF exposures in the 2-10 GHz range appear ineffective as a virucidal approach for hard surface decontamination. © 2023 Bioelectromagnetics Society.

Pulsed Electric Field Ablation of Esophageal Malignancies and Mitigating Damage to Smooth Muscle: An In Vitro Study.

Cancer ablation therapies aim to be efficient while minimizing damage to healthy tissues. Nanosecond pulsed electric field (nsPEF) is a promising ablation modality because of its selectivity against certain cell types and reduced neuromuscular effects. We compared cell killing efficiency by PEF (100 pulses, 200 ns-10 µs duration, 10 Hz) in a panel of human esophageal cells (normal and pre-malignant epithelial and smooth muscle). Normal epithelial cells were less sensitive than the pre-malignant ones to unipolar PEF (15-20% higher LD50, p < 0.05). Smooth muscle cells (SMC) oriented randomly in the electric field were more sensitive, with 30-40% lower LD50 (p < 0.01). Trains of ten, 300-ns pulses at 10 kV/cm caused twofold weaker electroporative uptake of YO-PRO-1 dye in normal epithelial cells than in either pre-malignant cells or in SMC oriented perpendicularly to the field. Aligning SMC with the field reduced the dye uptake fourfold, along with a twofold reduction in Ca2+ transients. A 300-ns pulse induced a twofold smaller transmembrane potential in cells aligned with the field, making them less vulnerable to electroporation. We infer that damage to SMC from nsPEF ablation of esophageal malignancies can be minimized by applying the electric field parallel to the predominant SMC orientation.

Observed Reductions in the Infectivity of Bioaerosols Containing Bovine Coronavirus Under Repetitively Pulsed RF Exposure.

OBJECTIVE: The purpose of the present study is to investigate the inactivation of bioaerosols containing Bovine Coronavirus, BCoV, under repetitively pulsed radio frequency (RF) electromagnetic exposure. METHODS: These experiments were performed in a waveguide containing a flowing aerosol stream and were limited to a single RF waveform: ∼2 µs square envelope, 5.6 GHz, 4.8 kHz repetition rate. Aerosol streams were exposed to RF electric field amplitudes in the range of 41.9 +/-6.2 kV/m. Under laminar flow conditions, 75% of the total collected aerosol stream spends 0.85 seconds or less in the RF exposure region. RESULTS: Application of the RF waveform changed mean survival rate of the aerosolized BCoV by -0.58 decades (roughly a 74% reduction) and impacted the variance and standard deviation of the experimental results, with the RF exposure data showing an 800% increase in variance and 196% increase in standard deviation over the control results. Experimental results were compared to those from an analytic electromagnetic-heating inactivation model. CONCLUSION: The comparison indicated the feasibility that the observed reduction in BCoV survival rate might be due to a combination of thermal effects and non-thermal electric field effects. SIGNIFICANCE: Developing better insight into the mechanisms of inactivation is important for understanding the potential limits of efficacy for this method. Additionally, these results contribute an important baseline for the impact of electromagnetic fields on aerosolized pathogens.

Sensitivity vs. awareness curve: A novel model-based analysis to uncover the processes underlying nonconscious perception.

In this study, we present a novel model-based analysis of the association between awareness and perceptual processing based on a multidimensional version of signal detection theory (general recognition theory, or GRT). The analysis fits a GRT model to behavioral data and uses the estimated model to construct a sensitivity versus awareness (SvA) curve, representing sensitivity in the discrimination task at each value of relative likelihood of awareness. This approach treats awareness as a continuum rather than a dichotomy, but also provides an objective benchmark for low likelihood of awareness. In two experiments, we assessed nonconscious facial expression recognition using SvA curves in a condition in which faces (fearful vs. neutral) were rendered invisible using continuous flash suppression (CFS) for 500 and 700 milliseconds. We predicted and found nonconscious processing of face emotion, in the form of higher than chance-level sensitivity in the area of low likelihood of awareness.

A Literature Review of the Effects of Air Pollution on COVID-19 Health Outcomes Worldwide: Statistical Challenges and Data Visualization.

Several peer-reviewed papers and reviews have examined the relationship between exposure to air pollution and COVID-19 spread and severity. However, many of the existing reviews on this topic do not extensively present the statistical challenges associated with this field, do not provide comprehensive guidelines for future researchers, and review only the results of a relatively small number of papers. We reviewed 139 papers, 127 of which reported a statistically significant positive association between air pollution and adverse COVID-19 health outcomes. Here, we summarize the evidence, describe the statistical challenges, and make recommendations for future research. To summarize the 139 papers with data from geographical locations around the world, we also present anopen-source data visualization tool that summarizes these studies and allows the research community to contribute evidence as new research papers are published.

Action spectra and mechanisms of (in) efficiency of bipolar electric pulses at electroporation.

The reversal of the electric field direction inhibits various biological effects of nanosecond electric pulses (nsEP). This feature, known as "bipolar cancellation," enables interference targeting of nsEP bioeffects remotely from stimulating electrodes, for prospective applications such as precise cancer ablation and non-invasive deep brain stimulation. This study was undertaken to achieve the maximum cancellation of electroporation, by quantifying the impact of the pulse shape, duration, number, and repetition rate across a broad range of electric field strengths. Monolayers of endothelial cells (BPAE) were electroporated in a non-uniform electric field. Cell membrane permeabilization was quantified by YO-PRO-1 (YP) dye uptake and correlated to local electric field strength. For most conditions tested, adding an opposite polarity phase reduced YP uptake by 50-80 %. The strongest cancellation, which reduced YP uptake by 95-97 %, was accomplished by adding a 50 % second phase to 600-ns pulses delivered at a high repetition rate of 833 kHz. Strobe photography of nanosecond kinetics of membrane potential in single CHO cells revealed the temporal summation of polarization by individual unipolar nsEP applied at sub-MHz rate, leading to enhanced electroporation. In contrast, there was no summation for bipolar pulses, and increasing their repetition rate suppressed electroporation. These new findings are discussed in the context of bipolar cancellation mechanisms and remote focusing applications.

Neurodevelopmental profiles of 4-year-olds in the Navajo Birth Cohort Study.

Objective: Native American children disproportionally face many risk factors for poor developmental outcomes; these factors include poverty, environmental toxicant exposure, and limited medical, and intervention services. To understand these risks, comprehensive documentation of developmental and behavioral phenotypes are needed. In the current descriptive study, we assessed the neurodevelopment of young Diné (Navajo) children using standardized assessment instruments in combination with expert clinician judgment. Methods: As part of an ongoing, population-based, prospective birth cohort study, we conducted comprehensive neurodevelopmental assessments of 138, 3-5-year-old, Diné children residing on or near the Navajo Nation. We report results from standardized parent reports, psychiatric examinations, and direct assessments of children's language, cognitive, adaptive, and social-emotional development, as well as best estimate clinical diagnoses. Results: Forty-nine percent of our sample met DSM-5 criteria for a neurodevelopmental disorder (NDD) diagnosis. Language and speech sound disorders were most common, although autism spectrum disorder (ASD) was also elevated compared to the general population. Though language performance was depressed amongst all groups of children with, and without, NDDs, those meeting criteria for certain NDDs performed significantly lower on all language measures, when compared to those without. Social-emotional, behavioral, and nonverbal cognitive ability were in the average range overall. Conclusions: Diné children in our study were found to have a high percentage of clinically significant developmental delays. Overall, children presented with a pervasive pattern of depressed language performance across measures, irrespective of diagnosis (or no diagnosis), while other domains of functioning were similar to normative samples. Findings support the need to identify appropriate intervention and educational efforts for affected youth, while also exploring the causes of the specific developmental delays. However, longitudinal studies are necessary to establish best practices for identifying delays and delineating resilience factors to optimize development of Diné children.

Comprehensive single-shot biophysical cytometry using simultaneous quantitative phase imaging and Brillouin spectroscopy.

Single-cell analysis, or cytometry, is a ubiquitous tool in the biomedical sciences. Whereas most cytometers use fluorescent probes to ascertain the presence or absence of targeted molecules, biophysical parameters such as the cell density, refractive index, and viscosity are difficult to obtain. In this work, we combine two complementary techniques-quantitative phase imaging and Brillouin spectroscopy-into a label-free image cytometry platform capable of measuring more than a dozen biophysical properties of individual cells simultaneously. Using a geometric simplification linked to freshly plated cells, we can acquire the cellular diameter, volume, refractive index, mass density, non-aqueous mass, fluid volume, dry volume, the fractional water content of cells, both by mass and by volume, the Brillouin shift, Brillouin linewidth, longitudinal modulus, longitudinal viscosity, the loss modulus, and the loss tangent, all from a single acquisition, and with no assumptions of underlying parameters. Our methods are validated across three cell populations, including a control population of CHO-K1 cells, cells exposed to tubulin-disrupting nocodazole, and cells under hypoosmotic shock. Our system will unlock new avenues of research in biophysics, cell biology, and medicine.