Spatiotemporally controlled single cell sonoporation

This paper presents unique approaches to enable control and quantification of ultrasound-mediated cell membrane disruption, or sonoporation, at the single-cell level. Ultrasound excitation of microbubbles that were targeted to the plasma membrane of HEK-293 cells generated spatially and temporally controlled membrane disruption with high repeatability. Using whole-cell patch clamp recording combined with fluorescence microscopy, we obtained time-resolved measurements of single-cell sonoporation and quantified the size and resealing rate of pores. We measured the intracellular diffusion coefficient of cytoplasmic RNA/DNA from sonoporation-induced transport of an intercalating fluorescent dye into and within single cells. We achieved spatiotemporally controlled delivery with subcellular precision and calcium signaling in targeted cells by selective excitation of microbubbles. Finally, we utilized sonoporation to deliver calcein, a membrane-impermeant substrate of multidrug resistance protein-1 (MRP1), into HEK-MRP1 cells, which overexpress MRP1, and monitored the calcein efflux by MRP1. This approach made it possible to measure the efflux rate in individual cells and to compare it directly to the efflux rate in parental control cells that do not express MRP1.     

Social Stress Alters Inhibitory Synaptic Input to Distinct Subpopulations of Raphe Serotonin Neurons

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Poor maintenance of sinus rhythm after electrical cardioversion of patients with atrial fibrillation or flutter: a 5‐year follow‐up of 268 consecutive patients

Objective—To report long‐term results of direct current (DC)‐cardioversion in unselected patients with atrial fibrillation (AF) or flutter.

Design—The study was a retrospective 5‐year follow‐up of all patients undergoing DC‐cardioversion for AF or flutter at our institution between 1993 and 1997.

Results—Three hundred and eighty‐five DC‐cardioversions were performed in 268 patients. Two hundred and forty‐nine patients underwent cardioversion for the first time. Of these, 183 (74%) were converted to sinus rhythm. During the first month of follow‐up 105 (57%) relapsed into AF. Only 33 patients (13%) of the 249 patients scheduled for cardioversion remained in sinus rhythm after 1 year. In multivariate analysis arrhythmia duration was the only variable that was associated with successful cardioversion. Periprocedural complications occurred in 9.9% of the cardioversions.

Conclusion—In daily routine only a minority of patients will maintain sinus rhythm after DC‐cardioversion for AF or flutter. Also, DC‐cardioversion is not without risk. These observational data suggest a conservative approach to re‐establishment of sinus rhythm in patients with AF.     

Excitation Patterns of Standard and Steered Partial Tripolar Stimuli in Cochlear Implants

Current steering in partial tripolar (pTP) mode has been shown to improve pitch perception and spectral resolution with cochlear implants (CIs). In this mode, a fraction (σ) of the main electrode current is returned within the cochlea and steered between the basal and apical flanking electrodes (with a proportion of α and 1 − α, respectively). Pitch generally decreases when α increases from 0 to 1, although the salience of pitch change varies across CI users. This study aimed to identify the mechanism of pitch changes with pTP-mode current steering and the factors contributing to the intersubject variability in pitch-ranking sensitivity. The electrical fields were measured for steered pTP stimuli on the same main electrode with α = 0, 0.5, and 1 in five implanted ears using electrical field imaging (EFI). The related excitation patterns were also measured physiologically using evoked compound action potential (ECAP) and psychophysically using psychophysical forward masking (PFM). Consistent with the pitch-ranking results in this study, the EFI, ECAP, and PFM centroids shifted apically with increasing α. An apical shift was also observed for the PFM peak but not for the EFI or ECAP peak. The pattern width was similar with different α values within a given measure (e.g., EFI, ECAP, or PFM), but the ECAP patterns were broader than the EFI and PFM patterns, possibly because ECAP was measured with smaller σ values than EFI and PFM. The amount of pattern shift with α depended on σ (i.e., the total amount of current used for steering) but was not correlated with the pitch-ranking sensitivity across subjects. The results revealed that the pitch changes elicited by pTP-mode current steering were not only driven by the shifts of excitation centroid.     

The effects of isoproterenol on abnormal electrical and contractile activity and diastolic calcium are attenuated in myocytes from aged Fischer 344 rats

We investigated whether the age-related decrease in sensitivity of the heart to catecholamines was accompanied by changes in Ca(2+) homeostasis and abnormal electrical and contractile activity caused by beta-adrenergic receptor (beta-AR) stimulation. Ventricular myocytes were isolated from young adult (3 months) and aged (24 months) male Fischer 344 rats. Unloaded cell shortening was measured in field-stimulated myocytes (2Hz, 37 degrees C); membrane currents and action potentials were measured with microelectrodes. Contractile responses to the non-selective beta-AR agonist, isoproterenol were significantly decreased in aged myocytes compared to younger myocytes and aged myocytes were less sensitive to isoproterenol. In contrast, Ca(2+) transients measured simultaneously with contractions were similar between groups. Isoproterenol increased sarcoplasmic reticulum Ca(2+) stores in both groups, but the increase was larger in aged cells. However, signs of Ca(2+) overload induced by isoproterenol were reduced with age. Diastolic Ca(2+) accumulation, contracture and the incidences of transient inward current, oscillatory afterpotentials (OAPs), aftertransients and aftercontractions induced by isoproterenol also were reduced with age. These results demonstrate that aged myocytes exhibit fewer signs of Ca(2+) overload in response to isoproterenol than young adult myocytes. These age-related changes in intracellular Ca(2+) may protect the aging heart against induction of arrhythmias initiated by OAPs.(1).     

Tolerability and feasibility of at-home remotely supervised transcranial direct current stimulation (RS-tDCS): Single-center evidence from 6,779 sessions

IntroductionThe ability to deploy transcranial direct current stimulation (tDCS) at home is a key usability advantage to support scaling for pivotal clinical trials. We have established a home-based tDCS protocol for use in clinical trials termed remotely supervised (RS)-tDCS.ObjectiveTo report the tolerability and feasibility of tDCS sessions completed to date using RS-tDCS in clinical trials.MethodsWe analyzed tolerability (i.e., adverse events, AEs) reported in six Class I/II/III trials using RS-tDCS to study symptom outcomes over 10 to 60 daily applications. Across the six clinical trials, 308 participants (18–78 years old) completed an average of 23 sessions for a total of 6779 RS-tDCS administrations. The majority of participants were diagnosed with multiple sclerosis, and open-label trials included those diagnosed with a range of other conditions (e.g., Parkinson's disease, post-stroke aphasia, traumatic brain injury, cerebellar ataxia), with minimum-to-severe neurologic disability. Clinical trial feasibility (i.e., treatment fidelity and blinding integrity) was examined using two Class I randomized controlled trials (RCTs).ResultsNo serious AEs occurred. Across administrations, three sessions (0.04%) were aborted due to discomfort, but no participant discontinued due to tolerability. The AEs most commonly reported by participants were tingling (68%), itching (41%) and warmth sensation (42%) at the electrode site, and these were equally reported in active and sham tDCS conditions. The two Class I RCTs resulted in rapid enrollment, high fidelity to treatment completion, and blinding integrity.ConclusionsAt-home RS-tDCS is tolerable, including when used over extended periods of time. Home-based RS-tDCS is feasible and can enable Class I tDCS clinical trial designs.     

New Evaluation and Management Code Level Selection Trends in Hip and Knee Osteoarthritis Patients

BackgroundOn January 1, 2021, the American Medical Association implemented changes regarding the outpatient Evaluation and Management (E/M) criteria dictating Current Procedural Terminology code level selection to help diminish administrative burden and emphasize medical decision-making as the primary determinant in E/M level of service (EML). The goal of this study was to describe EML coding trends in outpatient visits for hip and knee osteoarthritis after the 2021 Centers for Medicare and Medicaid Services changes to the E/M system.MethodsAll outpatient visits for primary hip and knee osteoarthritis within the divisions of Joint Replacement, Operative Sports Medicine, and Nonoperative Sports Medicine at a single orthopaedic practice were retrospectively analyzed during 2 separate 10-month timeframes in 2019 and 2021. The primary endpoint was the visit EML (1 through 5) based on Current Procedural Terminology E/M codes.ResultsIn 2019, 7.8% of all visits were billed as level 2, 85.8% of all visits were billed as level 3, and 6.3% of all visits were billed as level 4. In 2021, 2.8% of visits were billed as level 2, 54% of visits were billed as level 3, and 41.3% of visits were billed as level 4. Level 1 and Level 5 visits did not exceed 2% in either year. Across all 3 divisions, level 2 and 3 visits decreased significantly (P < .05), while level 4 visits increased significantly (P < .05).ConclusionSince the E/M coding criteria overhaul in 2021, there has been a significant trend towards higher level of service code selection across multiple divisions in our orthopaedic practice.