Search

By the means of computer simulation, the polypeptide antigen conformational structure that initiates the immunodominant epitope of the 2nd extracellular loop of β 1-adrenoreceptor has been built. A linear 25-member peptide corresponding to the calculated sequence was synthesized by means of the solid-phase method using Fmoc-technology, then by means of the closure of disulfide bridges, the original bicyclic polypeptide was obtained corresponding to the proposed structure of the conformational antigen. With the help of high-resolution NMR spectroscopy, the 3D structure of synthetic conformational antigen was investigated. It was shown, that the structure of bicyclic polypeptide is similar to that of the computer model. Bicyclic conformational antigen was suitable for the detection of autoantibodies in the blood serum of patients with rhythm and conductivity violation without evidence of organic disease of the cardiovascular system. [ABSTRACT FROM AUTHOR]

The interactions of a water-soluble nonmembrane protein aprotinin with multilamellar vesicles (MLV) and small unilamellar vesicles (SUV) from soybean phospholipids were studied using Sephadex G-75 gel chromatography combined with different methods of the analysis of the eluate fractions (fluorescence, light-scattering, turbidity; 31P NMR spectroscopy). The composition of the liposomes mainly containing soybean phosphatidylcholine (PC) was varied by the addition of phosphatidylethanolamine (PE), phosphatidylinositol (PI) and lyso-phosphatidylcholine (lyso-PC). To evaluate the lipid-protein interactions, the amount of aprotinin in the MLV–aprotinin complexes was determined. Lipid–protein interactions were found to strongly depend on the liposome composition, medium pH and ionic strength. These dependencies point to the electrostatic nature of the aprotinin-lipid interactions. 31P NMR spectroscopy of the MLV–aprotinin complexes indicated that aprotinin influences the phospholipid structure in MLV at pH 3.0. In the case of PC:PE:PI and PC:PE:PI:lyso-PC vesicles, aprotinin induced liposome aggregation and a lamellar-to-isotropic phase transition of the phospholipids. [ABSTRACT FROM AUTHOR]

Neuronal firing sequences are thought to be the basic building blocks of neural coding and information broadcasting within the brain. However, when sequences emerge during neurodevelopment remains unknown. We demonstrate that structured firing sequences are present in spontaneous activity of human and murine brain organoids and ex vivo neonatal brain slices from the murine somatosensory cortex. We observed a balance between temporally rigid and flexible firing patterns that are emergent phenomena in human and murine brain organoids and early postnatal murine somatosensory cortex, but not in primary dissociated cortical cultures. Our findings suggest that temporal sequences do not arise in an experience-dependent manner, but are rather constrained by an innate preconfigured architecture established during neurogenesis. These findings highlight the potential for brain organoids to further explore how exogenous inputs can be used to refine neuronal circuits and enable new studies into the genetic mechanisms that govern assembly of functional circuitry during early human brain development., Competing Interests: Competing interests: All authors declare no competing interests.

Electrophysiology offers a high-resolution method for real-time measurement of neural activity. Longitudinal recordings from high-density microelectrode arrays (HD-MEAs) can be of considerable size for local storage and of substantial complexity for extracting neural features and network dynamics. Analysis is often demanding due to the need for multiple software tools with different runtime dependencies. To address these challenges, we developed an open-source cloud-based pipeline to store, analyze, and visualize neuronal electrophysiology recordings from HD-MEAs. This pipeline is dependency agnostic by utilizing cloud storage, cloud computing resources, and an Internet of Things messaging protocol. We containerized the services and algorithms to serve as scalable and flexible building blocks within the pipeline. In this paper, we applied this pipeline on two types of cultures, cortical organoids and ex vivo brain slice recordings to show that this pipeline simplifies the data analysis process and facilitates understanding neuronal activity., Competing Interests: DECLARATION OF INTERESTS K.V. and S.T.S. are co-founders and D.H., S.R.S, M.T. are advisory board members of Open Culture Science, Inc., a company that may be affected by the research reported in the enclosed paper. All other authors declare no competing interests.

Experimental neuroscience techniques are advancing rapidly, with major recent developments in high-density electrophysiology and targeted electrical stimulation. In combination with these techniques, cortical organoids derived from pluripotent stem cells show great promise as in vitro models of brain development and function. Although sensory input is vital to neurodevelopment in vivo , few studies have explored the effect of meaningful input to in vitro neural cultures over time. In this work, we demonstrate the first example of goal-directed learning in brain organoids. We developed a closed-loop electrophysiology framework to embody mouse cortical organoids into a simulated dynamical task (the inverted pendulum problem known as 'Cartpole') and evaluate learning through high-frequency training signals. Longitudinal experiments enabled by this framework illuminate how different methods of selecting training signals enable improvement on the tasks. We found that for most organoids, training signals chosen by artificial reinforcement learning yield better performance on the task than randomly chosen training signals or the absence of a training signal. This systematic approach to studying learning mechanisms in vitro opens new possibilities for therapeutic interventions and biological computation.

The analysis of tissue cultures, particularly brain organoids, requires a sophisticated integration and coordination of multiple technologies for monitoring and measuring. We have developed an automated research platform enabling independent devices to achieve collaborative objectives for feedback-driven cell culture studies. Our approach enables continuous, communicative, non-invasive interactions within an Internet of Things (IoT) architecture among various sensing and actuation devices, achieving precisely timed control of in vitro biological experiments. The framework integrates microfluidics, electrophysiology, and imaging devices to maintain cerebral cortex organoids while measuring their neuronal activity. The organoids are cultured in custom, 3D-printed chambers affixed to commercial microelectrode arrays. Periodic feeding is achieved using programmable microfluidic pumps. We developed a computer vision fluid volume estimator used as feedback to rectify deviations in microfluidic perfusion during media feeding/aspiration cycles. We validated the system with a set of 7-day studies of mouse cerebral cortex organoids, comparing manual and automated protocols. The automated protocols were validated in maintaining robust neural activity throughout the experiment. The automated system enabled hourly electrophysiology recordings for the 7-day studies. Median neural unit firing rates increased for every sample and dynamic patterns of organoid firing rates were revealed by high-frequency recordings. Surprisingly, feeding did not affect firing rate. Furthermore, performing media exchange during a recording showed no acute effects on firing rate, enabling the use of this automated platform for reagent screening studies., Competing Interests: Competing interests K.V. and S.T.S. are co-founders and D.H., S.R.S, M.T. are advisory board members of Open Culture Science, Inc., a company that may be affected by the research reported in the enclosed paper. All other authors declare no competing interests.

Seizures are made up of the coordinated activity of networks of neurons, suggesting that control of neurons in the pathologic circuits of epilepsy could allow for control of the disease. Optogenetics has been effective at stopping seizure-like activity in non-human disease models by increasing inhibitory tone or decreasing excitation, although this effect has not been shown in human brain tissue. Many of the genetic means for achieving channelrhodopsin expression in non-human models are not possible in humans, and vector-mediated methods are susceptible to species-specific tropism that may affect translational potential. Here we demonstrate adeno-associated virus-mediated, optogenetic reductions in network firing rates of human hippocampal slices recorded on high-density microelectrode arrays under several hyperactivity-provoking conditions. This platform can serve to bridge the gap between human and animal studies by exploring genetic interventions on network activity in human brain tissue., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Nature America, Inc.)

How seizures begin at the level of microscopic neural circuits remains unknown. High-density CMOS microelectrode arrays provide a new avenue for investigating neuronal network activity, with unprecedented spatial and temporal resolution. We use high-density CMOS-based microelectrode arrays to probe the network activity of human hippocampal brain slices from six patients with mesial temporal lobe epilepsy in the presence of hyperactivity promoting media. Two slices from the dentate gyrus exhibited epileptiform activity in the presence of low magnesium media with kainic acid. Both slices displayed an electrophysiological phenotype consistent with a reciprocally connected circuit, suggesting a recurrent feedback loop is a key driver of epileptiform onset. Larger prospective studies are needed, but these findings have the potential to elucidate the network signals underlying the initiation of seizure behavior., Competing Interests: Competing interests: All authors declare no competing interests.

Aim    To study the effectiveness of a treatment based on monitoring the soluble ST2 receptor (sST2) concentration in patients with chronic heart failure (CHF) with reduced left ventricular ejection fraction (LVEF) after acute decompensated heart failure (ADHF).Material and methods    The study included 37 patients hospitalized for ADHF with LVEF ≤40% and sST2 concentration ≥37.8 ng/ml at the time of discharge from the hospital. Patients were randomized into two groups: a sST2 monitoring (sST2M) group (19 patients) and a standard therapy (ST) group (18 patients). The follow-up period was 12 months. At baseline, the groups practically did not differ by clinical, functional, laboratory, and instrumental characteristics. For the sST2M group, the goal was reducing the sST2 concentration by >30% of baseline or to <30 ng/ml.Results    Therapy in both groups was comparable both in doses and in frequency of administration of basic drugs. However, the diuretic therapy was more frequently adjusted in the sST2M group (3.0 [1.0; 4.0] vs. 1.0 [0; 3.0] adjustments per patient, p = 0.047), which required more visits to the clinic (7.0 [6.0; 9.0] vs. 6.0 [6.0; 6.0] visits per patient, p=0.024). In the sST2M group at 6 months, the sST2 concentration was decreased by 43.3% (p=0.001), and 13 patients (72.2%) achieved the goal. In the ST group, the sST2 concentration was decreased by 38.5% (p=0.001), and 11 patients (68.8%) reached the target values. After 12 months, the downward trend continued in both groups. In both groups, the NT-proBNP concentration decreased: in the sST2M group by 27.7% (p=0.014), and in the ST group by 31.9% (p = 0.006). By the 12th month, the decrease remained only in the sST2M group. Only the sST2M group had an increase in LVEF (+28.5%, p=0.003), a decrease in left ventricular end-systolic volume (LVESV) (-12.0%, p=0.017), and a decrease in left atrial volume (-13.4%, p=0.045); at 12 months, LVEF remained increased (26%, p=0.006), and LA volume remained decreased (-14.3%, p=0.028). Quality of life and results of 6-minute walk test (6MWT) improved in both groups. For 6 months of treatment, the sST2M group had a significantly lower incidence of composite endpoints (CEP, cardiovascular death and decompensation/hospitalization due to HF), 26.3% (5 events) of the sST2M group compared to the ST group, 83.3% (15 events) (p=0.029), primarily due to a lower incidence of decompensated HF. For 12 months of follow-up, the incidence of CEP in the ST group was 122.2% (22 events), and 47.4% (9 events) in the sST2M group (p=0.035).Conclusions    The tactics of sST2 monitoring used in the treatment of "high-risk" HFrEF patients (with high sST2 concentrations) is associated with increased LVEF, improved functional status of patients, a beneficial effect on LV remodeling, and decreased incidence of CEP.

Aim: To evaluate the effect of Sacubitril/Valsartan (S/V) on the functional status, systolic and diastolic function of the left ventricle (LV), tolerability of therapy and to determine predictors of its effectiveness in patients with cancer therapy-related heart failure (СTRHF)., Materials and Methods: Forty patients 58 [46; 65.5] years of age with HF associated with anthracycline-containing cancer therapy were enrolled. Clinical examination, echocardiography, and assessment of potassium and creatinine levels were performed at baseline and after 6 months of S/V therapy., Results: NYHA functional class (FC) improvement was observed in 22 (64.7%) patients. Radiation therapy (RT) decreased (OR 0.091; 95% CI 0.01-0.83; p =0.03) while baseline low LV EF increased (OR 9.0; 95% CI 1.78-45.33; p =0.008) the odds of FC improvement. LV EF increased from 37.3 [30; 42.5] % to 45 [38; 48] % ( p <0.0001) and exceeded 50% in 7 (20.6%) patients. The odds of LV EF recovery increased when S/V therapy was initiated ≤1 year after anthracycline therapy (OR 10.67; 95% CI 1.57-72.67; p =0.0016) and decreased in patients with the history of RT (OR 0.14; 95% CI 0.02-0.89; p =0.0037) and in patients over 58 years (OR 0.07; 95% CI 0.01-0.68; p =0.022). LV diastolic function improvement included E/e' descent from 13.6 [10; 18.3] to 8.9 [6.9; 13.7] ( p =0.0005), and decrease in diastolic dysfunction grade in 18 (45%) patients ( p =0.0001). No significant change in serum potassium (4.45 [4.2; 4.8] versus 4.5 [4.3; 4.8]; p =0.5) and creatinine (75.4 [67.6; 85.1] versus 75.5 [68.2; 98.3]; p =0.08) levels were observed., Conclusion: S/V therapy is associated with improvement of EF, systolic and diastolic LV function, demonstrates a favorable tolerability profile in patients with СTRHF. Lack of RT and low baseline LV EF increased the odds of LV EF improvement; lack of RT, early (≤1 year) start of treatment after discontinuation of anthracycline therapy, and age <58 years increased the odds of LV EF recovery.

Background: The timing of events in the management of osteosarcoma may be critical for patient survivorship; however, the prognostic value of factors such as onset of symptoms or initiation of therapy in these patients has not been studied. This study sought to review the literature reporting treatment of osteosarcoma to determine the utility of event timing as a prognostic indicator. Due to significant heterogeneity in the literature, this study was conducted as a scoping review to assess the current state of the literature, identify strengths and weaknesses in current reporting practices, and to propose avenues for future improvement., Main Body: This review screened 312 peer-reviewed studies of osteosarcoma in any anatomic location published in an English journal for reporting of an event timing metric of any kind in a population of 6 or more. Thirty-seven studies met inclusion/exclusion criteria and were assessed for level of evidence, quality, and event timing metric. Reviewers also collated: publication year, population size, population age, tumor site, tumor type, surgical treatment, and adjuvant medical treatment. Extracted event timing data were further characterized using nine standardized categories to enable systematic analysis. The reporting of event timing in the treatment of osteosarcoma was incomplete and heterogenous. Only 37 of 312 (11.9%) screened studies reported event timing in any capacity. The period between patient-reported symptom initiation and definitive diagnosis was the most reported (17/37, 45.9%). Symptom duration was the second most reported period (10/37, 27.0%). Event timing was typically reported incidentally and was never rigorously incorporated into data analysis or discussion. No studies considered the impact of event timing on a primary outcome. The six largest studies were assessed in detail to identify pearls for future researchers. Notable shortcomings included the inadequate reporting of the definition of an event timing period and the pooling of patients into poorly defined timing groups., Conclusions: Inconsistent reporting of event timing in osteosarcoma treatment prevents the development of clinically useful conclusions despite evidence to suggest event timing is a useful prognostic indicator. Consensus guidelines are necessary to improve uniformity and utility in the reporting of event timing., (© 2022. The Author(s).)

Human brain organoids replicate much of the cellular diversity and developmental anatomy of the human brain. However, the physiology of neuronal circuits within organoids remains under-explored. With high-density CMOS microelectrode arrays and shank electrodes, we captured spontaneous extracellular activity from brain organoids derived from human induced pluripotent stem cells. We inferred functional connectivity from spike timing, revealing a large number of weak connections within a skeleton of significantly fewer strong connections. A benzodiazepine increased the uniformity of firing patterns and decreased the relative fraction of weakly connected edges. Our analysis of the local field potential demonstrate that brain organoids contain neuronal assemblies of sufficient size and functional connectivity to co-activate and generate field potentials from their collective transmembrane currents that phase-lock to spiking activity. These results point to the potential of brain organoids for the study of neuropsychiatric diseases, drug action, and the effects of external stimuli upon neuronal networks., (© 2022. The Author(s).)

Given the rising number of patients with blindness from macular, optic nerve, and visual pathway disease, there is considerable interest in the potential of electrical stimulation devices to restore vision. Electrical devices for restoration of visual function can be grouped into three categories: (1) visual prostheses whose goal is to bypass damaged areas and directly activate downstream intact portions of the visual pathway; (2) electric field stimulation whose goal is to activate endogenous transcriptional and molecular signaling pathways to promote neuroprotection and neuro-regeneration; and (3) neuromodulation whose stimulation would resuscitate neural circuits vital to coordinating responses to visual input.  In this review, we discuss these three approaches, describe advances made in the different fields, and comment on limitations and potential future directions., Competing Interests: Declaration of competing interest Kimberly Kinga Gokoffski is supported by a K08 grant (1K08EY031797) from the NEI.  Darrin Jason Lee is supported by a K08 grant (1K08MH121757) from the NINDS.  Otherwise, the authors report no proprietary or commercial interest in any product mentioned or concept discussed in this article., (Copyright © 2021. Published by Elsevier Inc.)

Developing tools to enable non-invasive, high-throughput electrophysiology measurements of large functional-networks of electrogenic cells used as in vitro disease models for the heart and brain remains an outstanding challenge for preclinical drug discovery, where failures are costly and can prove to be fatal during clinical trials. Here we demonstrate, for the first time, that it is possible to perform non-contact monitoring of extra-cellular field potentials with a multi-electrode array (MEA). To do this preliminary demonstration we built a prototype with a custom mechanical stage to micro-position cells grown on conventional glass coverslips over the recording surface of a MEA sensor. The prototype can monitor extra-cellular fields generated by multi-cellular networks in a non-contact configuration, enabling a single MEA sensor to probe different cultures in succession, without fouling or degrading its sensitive electronic surface. This first demonstration with easy to culture cardiomyocyte cells and a prototype device points to the exciting possibility for instrument development leading to more efficient and cost-effective drug screening paradigms for cardiovascular and neurological diseases.

The misfolding and accumulation of tau protein into intracellular aggregates known as neurofibrillary tangles is a pathological hallmark of neurodegenerative diseases such as Alzheimer's disease. However, while tau propagation is a known marker for disease progression, exactly how tau propagates from one cell to another and what mechanisms govern this spread are still unclear. Here, we report that cellular internalization of tau is regulated by quaternary structure and have developed a cellular assay to screen for genetic modulators of tau uptake. Using CRISPRi technology we have tested 3200 genes for their ability to regulate tau entry and identified enzymes in the heparan sulfate proteoglycan biosynthetic pathway as key regulators. We show that 6-O-sulfation is critical for tau-heparan sulfate interactions and that this modification regulates uptake in human central nervous system cell lines, iPS-derived neurons, and mouse brain slice culture. Together, these results suggest novel strategies to halt tau transmission.

Objective: This study aimed to assess the level of anti-1-adrenergic receptor autoantibodies in patients with ventricular arrhythmias with no signs of organic heart disease and with presence of cardiovascular pathology in comparison with a group of healthy volunteers., Material and Methods: The study included 44 patients with ventricular arrhythmias with no signs of organic heart disease ("idiopathic"), 34 patients with diagnosed dilated cardiomyopathy (DCM) of inflammatory origin, 35 patients with coronary heart disease and ventricular arrhythmias, 12patients with coronary heart disease with no ventricular arrhythmias, and 19 healthy volunteers (control group). The level of autoantibodies against the 1-adrenergic receptor was determined by the developed competitive cell-based enzyme-linked immunosorbent assay (ELISA) and by the standard ELISA using peptides corresponding to the second extracellular loop of the 1-adrenergic receptor., Results: Elevated level of autoantibodies detected by a competitive cell-based ELISA was observed in 62% of patients with DCM compared to 21% of healthy volunteers (p=0.0006). In patients with "idiopathic" ventricular arrhythmias, the level of 1-adrenergic receptor autoantibodies was lower than in healthy subjects (p=0.003). Coronary heart disease patients with or without ventricular arrhythmias exhibited no differences from the control group. The number of significantly positive signals in peptide-based ELISA did not exceed 10% in any of the groups. No correlation between the data from competitive cell-based ELISA and peptide-based ELISA was found., Conclusions: This study demonstrated that competitive cell-based ELISA technique can be applied for detection of 1-adrenergic receptor autoantibodies. The results in DCM patients generally correspond to the expected. Decreased level of autoantibodies in patients with "idiopathic" ventricular arrhythmias indicates that this disease is related to changes in the immune system. Such relation is not observed in the case of coronary heart disease patients.

Random telegraph signals corresponding to activated charge traps were observed with liquid-gated CNT FETs. The high signal-to-noise ratio that we observe demonstrates that single electron charge sensing is possible with CNT FETs in liquids at room temperature. We have characterized the gate-voltage dependence of the random telegraph signals and compared to theoretical predictions. The gate-voltage dependence clearly identifies the sign of the activated trapped charge.

We have performed scanning photocurrent microscopy measurements of field-effect transistors (FETs) made from individual ultraclean suspended carbon nanotubes (CNTs). We investigate the spatial-dependence, polarization-dependence, and gate-dependence of photocurrent and photovoltage in this system. While previous studies of surface-bound CNT FET devices have identified the photovoltaic effect as the primary mechanism of photocurrent generation, our measurements show that photothermoelectric phenomena play a critical role in the optoelectronic properties of suspended CNT FETs. We have quantified the photothermoelectric mechanisms and identified regimes where they overwhelm the photovoltaic mechanism.

We demonstrate that micron-scale graphene field-effect transistor biosensors can be fabricated in a scalable fashion from large-area chemical vapor deposition derived graphene. We electrically detect the real-time binding and unbinding of a protein biomarker, thrombin, to and from aptamer-coated graphene surfaces. Our sensors have low background noise and high transconductance, comparable to exfoliated graphene devices. The devices are reusable and have a shelf-life greater than one week.

Linear peptides corresponding to fragment 83-98 of the first loop and fragments 168-192 and 171-182 of the second extracellular loops of M2-muscarinic receptor (marker of early cardiac disorders and arrhythmias) were synthesized by Fmoc-SPPS method. A new conformational antigen was synthesized by method of selective ligation of linear peptides by disulfide bond with native localization. Peptides were studied in reaction with sera from patients with idiopathic arrhythmias. A new conformational antigen was recognized by sera from patients with idiopathic arrhythmias with high reactivity.

Determining the major noise sources in nanoscale field-effect transistor (nanoFET) biosensors is critical for improving bioelectronic interfaces. We use the carbon nanotube (CNT) FET biosensor platform to examine the noise generated by substrate interactions and surface adsorbates, both of which are present in current nanoFET biosensors. The charge noise model is used as a quantitative framework to show that insulating substrates and surface adsorbates are both significant contributors to the noise floor of CNT FET biosensors. Removing substrate interactions and surface adsorbates reduces the power spectral density of background voltage fluctuations by 19-fold.

Biosensor response time, which depends sensitively on the transport of biomolecules to the sensor surface, is a critical concern for future biosensor applications. We have fabricated carbon nanotube field-effect transistor biosensors and quantified protein binding rates onto these nanoelectronic sensors. Using this experimental platform we test the effectiveness of a protein repellent coating designed to enhance protein flux to the all-electronic real-time biosensor. We observe a 2.5-fold increase in the initial protein flux to the sensor when upstream binding sites are blocked. Mass transport modelling is used to calculate the maximal flux enhancement that is possible with this strategy. Our results demonstrate a new methodology for characterizing nanoelectronic biosensor performance, and demonstrate a mass transport optimization strategy that is applicable to a wide range of microfluidic based biosensors.

Neuropeptide FF (H-Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2) injected intravenously temporarily enhanced the arterial pressure (AP) and the heart rate (HR). However, its role in the regulation of blood circulation is obscure. To study the properties of the molecule, its analogue was synthesized, in which proline in position 7 was substituted with glycine, and leucine in the position 2 with norleucine. Modified neuropeptide FF (FFm) also temporarily and in a dose-dependent manner increased the AP and HR; however, the equal degree of increase was reached at doses of FFm being 5-7 times lesser as compared with the natural peptide. The application of the FFm at hemorrhagic shock excluded mortality of animals during the experiment, considerably increased the degree of AP and HR restoration in the remaining experiments, and improved the survival of animals in 24 hours. It has been found that the level of antibodies to the fragment of hFF1 receptor in the serum is lower in spontaneously hypertensive rats SHR as compared with Wistar rats, but it is increased in patients of cardiological profile as compared with donors. The findings suggest involvement of neuropeptide FF in the regulation of blood circulation; however, the precise mechanisms remain to be determined.