Search

This study aimed to evaluate surface defects of Remover rotary Nickel-Titanium (NiTi) files after single and multiple uses in conventional endodontic retreatment procedures using scanning electron microscopy (SEM). Eighty acrylic blocks, simulating root canals with a 1.5 mm internal diameter, a 5 mm radius of curvature, and a 55° curvature, were utilized. After chemomechanical preparation and obturation, 24 new Remover files (N30, 7%, L23) were randomly assigned to three groups: single use, triple use, and six uses. The files were operated at 600 rpm with a torque of 2.5 Ncm, cleaned, and sterilized after each use. SEM analysis at magnifications of 100x, 250x, and 500x revealed surface defects, including tip deformation, microcracks, fracture, unwinding, surface pitting, and blade disruption. Deformation was observed in 75% of the files after a single use and in 100% of the files after three and six uses. Microcracks were absent after single use but appeared in 25% and 87.5% of files after three and six uses, respectively, showing a statistically significant increase (p < 0.001). Surface pitting also significantly increased among groups (p = 0.004). No fractures were observed in any group. The most common defects were tip deformation (91.7%) and surface pitting (70.8%). The findings suggest that repeated use of NiTi files significantly increases surface defects, elevating the risk of fatigue fractures. Thus, the results recommend limiting the reuse of Remover files to a maximum of 3x. Further research is needed to correlate defect types with anatomical factors and to assess file effectiveness in retreatment scenarios.

Introduction: Root canal retreatment often employs organic solvents like chloroform, eucalyptol, and orange oil. However, studies comparing their effectiveness yield inconsistent results. The quantity of d-limonene, a crucial component in orange oil, varies depending on the oil production method. Cold-pressed orange oil has been observed to contain the highest d-limonene levels. This study investigates the comparative solvent effects of cold-pressed and steam-hydrodistilled orange oils on gutta-percha and GuttaFlow2, typically used components in root canal fillings., Methods: Thirty-two discs (10 mm in diameter and 2 mm in thickness) were prepared using GuttaFlow and gutta-percha cones. The samples were weighed and then randomly divided into four groups (n=8) based on the type of solvent used. Each group was immersed in its respective solvent for 10 minutes. After exposure to the solvent, the samples were reweighed to determine the amount of material removed., Results: The weight loss in the group treated with cold-pressed orange oil on gutta-percha was significantly higher than in other groups (GuttaFlow2 + cold-pressed orange oil, gutta-percha + steam hydrodistilled orange oil, GuttaFlow2 + steam hydrodistilled orange oil) (p<0.001, p<0.001, and p<0.001)., Conclusion: According to the study findings, cold-pressed orange oil demonstrated a higher solvent effect on both GuttaFlow2 and traditional gutta-percha compared to steam-hydrodistilled orange oil. This indicates the significant impact of the production method of orange oil on its efficacy as a solvent in root canal therapy retreatment., Competing Interests: Human subjects: All authors have confirmed that this study did not involve human participants or tissue. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Ozden et al.)

Realizing the full potential of stretchable bioelectronics in wearables, biomedical implants and soft robotics necessitates conductive elastic composites that are intrinsically soft, highly conductive and strain resilient. However, existing composites usually compromise electrical durability and performance due to disrupted conductive paths under strain and rely heavily on a high content of conductive filler. Here we present an in situ phase-separation method that facilitates microscale silver nanowire assembly and creates self-organized percolation networks on pore surfaces. The resultant nanocomposites are highly conductive, strain insensitive and fatigue tolerant, while minimizing filler usage. Their resilience is rooted in multiscale porous polymer matrices that dissipate stress and rigid conductive fillers adapting to strain-induced geometry changes. Notably, the presence of porous microstructures reduces the percolation threshold (V c  = 0.00062) by 48-fold and suppresses electrical degradation even under strains exceeding 600%. Theoretical calculations yield results that are quantitatively consistent with experimental findings. By pairing these nanocomposites with near-field communication technologies, we have demonstrated stretchable wireless power and data transmission solutions that are ideal for both skin-interfaced and implanted bioelectronics. The systems enable battery-free wireless powering and sensing of a range of sweat biomarkers-with less than 10% performance variation even at 50% strain. Ultimately, our strategy offers expansive material options for diverse applications., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Postganglionic neurons of the autonomic nervous system lie outside of the central nervous system and innervate specific target effectors such as organs or glands. The major pelvic ganglion (MPG) is one such ganglion that plays a significant role in controlling bladder function in rodents. However, because of technical and physical constraints in recording electrophysiological signals from these neurons in vivo, the functional neural activity in MPG is mostly unknown. Transgenic animal models expressing genetically encoded calcium indicators now provide opportunities to monitor the activity of populations of neurons in vivo to overcome these challenges related to traditional electrophysiological methods. However, like many peripheral neurons, the MPG is not conducive to conventional fluorescent microscopy techniques, as it is located in the pelvic cavity, thus limiting robust optical access by benchtop microscopes. Here, we present an endoscopic approach based on a custom miniscope system (UCLA V3) that allows for effective in vivo monitoring of neural activity in the MPG for the first time. We show that our imaging approach can monitor activity of hundreds of MPG neurons simultaneously during the filling and emptying of the bladder in a urethane-anesthetized transgenic mouse line expressing GCaMP6s in cholinergic MPG neurons. By using custom analysis scripts, we isolated the activity of hundreds of individual neurons and show that populations of neurons have distinct phasic activation patterns during sequential bladder filling and voiding events. Our imaging approach can be adapted to record activity from autonomic neurons across different organs and systems in both healthy and disease models. NEW & NOTEWORTHY The functional activity and information processing within autonomic ganglia is mostly unknown because of technical and physical constraints in recording electrophysiological signals from these neurons in vivo. Here, we use a micro-endoscopic approach to measure in vivo functional activity patterns from a population of autonomic neurons controlling bladder function for the first time. This approach can be adapted to record activity from autonomic neurons across different organs and systems in both healthy and disease models.

How do humans and animals perform trial-and-error learning when the space of possibilities is infinite? In a previous study, we used an interval timing production task and discovered an updating strategy in which the agent adjusted the behavioral and neuronal noise for exploration. In the experiment, human subjects proactively generated a series of timed motor outputs. Positive or negative feedback was provided after each response based on the timing accuracy. We found that the sequential motor timing varied at two temporal scales: long-term correlation around the target interval due to memory drifts and short-term adjustments of timing variability according to feedback. We have previously described these two key features of timing variability with an augmented Gaussian process, termed reward-sensitive Gaussian process (RSGP). In a nutshell, the temporal covariance of the timing variable was updated based on the feedback history to recreate the two behavioral characteristics mentioned above. However, the RSGP was mainly descriptive and lacked a neurobiological basis of how the reward feedback can be used by a neural circuit to adjust motor variability. Here we provide a mechanistic model and simulate the process by borrowing the architecture of recurrent neural networks (RNNs). While recurrent connection provided the long-term serial correlation in motor timing, to facilitate reward-driven short-term variations, we introduced reward-dependent variability in the network connectivity, inspired by the stochastic nature of synaptic transmission in the brain. Our model was able to recursively generate an output sequence incorporating internal variability and external reinforcement in a Bayesian framework. We show that the model can generate the temporal structure of the motor variability as a basis for exploration and exploitation trade-off. Unlike other neural network models that search for unique network connectivity for the best match between the model prediction and observation, this model can estimate the uncertainty associated with each outcome and thus did a better job in teasing apart adjustable task-relevant variability from unexplained variability. The proposed artificial neural network model parallels the mechanisms of information processing in neural systems and can extend the framework of brain-inspired reinforcement learning (RL) in continuous state control., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Wang, El-Jayyousi and Ozden.)

Mitochondrial Ca 2+ plays a critical role in controlling cytosolic Ca 2+ buffering, energy metabolism, and cellular signal transduction. Overloading of mitochondrial Ca 2+ contributes to various pathological conditions, including neurodegeneration and apoptotic cell death in neurological diseases. Here we present a cell-type specific and mitochondria targeting molecular approach for mitochondrial Ca 2+ imaging in astrocytes and neurons in vitro and in vivo. We constructed DNA plasmids encoding mitochondria-targeting genetically encoded Ca 2+ indicators (GECIs) GCaMP5G or GCaMP6s (GCaMP5G/6s) with astrocyte- and neuron-specific promoters gfaABC1D and CaMKII and mitochondria-targeting sequence (mito-). For in vitro mitochondrial Ca 2+ imaging, the plasmids were transfected in cultured astrocytes and neurons to express GCaMP5G/6s. For in vivo mitochondrial Ca 2+ imaging, adeno-associated viral vectors (AAVs) were prepared and injected into the mouse brains to express GCaMP5G/6s in mitochondria in astrocytes and neurons. Our approach provides a useful means to image mitochondrial Ca 2+ dynamics in astrocytes and neurons to study the relationship between cytosolic and mitochondrial Ca 2+ signaling, as well as astrocyte-neuron interactions.

Propolis is a candidate for cancer treatment with its activity against different tumor cells and, has a wide spectrum of biological and pharmacological activities due to the diversity of its components. In this study, antitumorigenic activities of ethanol extract of propolis (EEP) and ethanol extract of propolis loaded niosome (PLN) were compared using 2D and 3D cell culture. Niosome formulations were prepared by thin film hydration technique. Cell viability of EEP and PLN was analyzed on MCF7, A549, MDA-MB-231, SK-MEL, SK-BR-3, DU145 and L-929 cell lines using MTT assay. L929, MCF7 and A549 cells were cultured using the 3D petri dish technique and their spherical forms were obtained after 142 h. After 24 h, PLN and EEP application, cell viability analysis was performed on 3D cultures with WST assay. As a result, niosome formulations containing EEP showed higher activity than ethanol extract of propolis in cancer cells. While a slow decrease was observed in cell viability in EEP treated cancer cells, it was observed that the percentage viability rates decreased in a shorter time in PLN treated cancer cells. Also, PLN can be used as an anticancer activity drug such as Doxorubicin, but this is not the case for EEP.