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Indian Pacing and Electrophysiology... May 2024Premature ventricular contraction (PVC) is usually eliminated in the earliest activation site based on the conventional electrode of ablation catheter. However, the...
Premature ventricular contraction (PVC) is usually eliminated in the earliest activation site based on the conventional electrode of ablation catheter. However, the large size electrode may contain far-field potential. The QDOT MICRO ablation catheter has three micro electrodes with 0.33 mm electrode length, in addition to the conventional electrode with 3.5 mm electrode length. The micro electrodes can reflect only near-field potential. A 78-year-old with symptomatic frequent PVCs underwent catheter ablation. PVC-1 showed good pace-mapping in distal great cardiac vein (GCV). The local bipolar electrograms in the conventional electrode of ablation catheter preceded the PVC-QRS onset by 32 ms in distal GCV and 13 ms in left coronary cusp (LCC), but those in the micro electrodes preceded only by 13 ms both in distal GCV and LCC. PVC-1 was eliminated by radiofrequency (RF) application, not in distal GCV, but in LCC. PVC-2 showed good pace-mapping in LCC. The local bipolar electrograms in both the conventional electrode and the micro electrodes of ablation catheter preceded the PVC-QRS onset by 32 ms in LCC. PVC-2 was eliminated by RF application in LCC. Comparing the local electrograms of micro electrodes and the conventional electrodes may be important for identifying depth of the origin of PVCs.
PubMed: 38729242
DOI: 10.1016/j.ipej.2024.05.001 -
Journal of Neurosurgery. Spine May 2024The goal of this study was to assess the safety of mapping spinal cord locomotor networks using penetrating stimulation microelectrodes in Yucatan minipigs (YMPs) as a...
OBJECTIVE
The goal of this study was to assess the safety of mapping spinal cord locomotor networks using penetrating stimulation microelectrodes in Yucatan minipigs (YMPs) as a clinically translational animal model.
METHODS
Eleven YMPs were trained to walk up and down a straight line. Motion capture was performed, and electromyographic (EMG) activity of hindlimb muscles was recorded during overground walking. The YMPs underwent a laminectomy and durotomy to expose the lumbar spinal cord. Using an ultrasound-guided stereotaxic frame, microelectrodes were inserted into the spinal cord in 8 animals. Pial cuts were made to prevent tissue dimpling before microelectrode insertion. Different locations within the lumbar enlargement were electrically stimulated to map the locomotor networks. The remaining 3 YMPs served as sham controls, receiving the laminectomy, durotomy, and pial cuts but not microelectrode insertion. The Porcine Thoracic Injury Behavioral Scale (PTIBS) and hindlimb reflex assessment results were recorded for 4 weeks postoperatively. Overground gait kinematics and hindlimb EMG activity were recorded again at weeks 3 and 4 postoperatively and compared with preoperative measures. The animals were euthanized at the end of week 4, and the lumbar spinal cords were extracted and preserved for immunohistochemical analysis.
RESULTS
All YMPs showed transient deficits in hindlimb function postoperatively. Except for 1 YMP in the experimental group, all animals regained normal ambulation and balance (PTIBS score 10) at the end of weeks 3 and 4. One animal in the experimental group showed gait and balance deficits by week 4 (PTIBS score 4). This animal was excluded from the kinematics and EMG analyses. Overground gait kinematic measures and EMG activity showed no significant (p > 0.05) differences between preoperative and postoperative values, and between the experimental and sham groups. Less than 5% of electrode tracks were visible in the tissue analysis of the animals in the experimental group. There was no statistically significant difference in damage caused by pial cuts between the experimental and sham groups. Tissue damage due to the pial cuts was more frequently observed in immunohistochemical analyses than microelectrode tracks.
CONCLUSIONS
These findings suggest that mapping spinal locomotor networks in porcine models can be performed safely, without lasting damage to the spinal cord.
PubMed: 38728765
DOI: 10.3171/2024.2.SPINE23757 -
Frontiers in Plant Science 2024Condensed tannins are common in vegetative tissues of woody plants, including in roots. In hybrid poplar ( also known as ) CT assays indicated they were most...
Condensed tannins are common in vegetative tissues of woody plants, including in roots. In hybrid poplar ( also known as ) CT assays indicated they were most concentrated in younger white roots and at the root tip. Furthermore, CT-specific staining of embedded tissue sections demonstrated accumulation in root cap cells and adjacent epidermal cells, as well as a more sporadic presence in cortex cells. In older, brown roots as well as roots with secondary growth (cork zone), CT concentration was significantly lower. The insoluble fraction of CTs was greatest in the cork zone. To determine if CT accumulation correlates with nutrient uptake in poplar roots, a microelectrode ion flux measurement (MIFE™) system was used to measure flux along the root axis. Greatest NH uptake was measured near the root tip, but NO and Ca did not vary along the root length. In agreement with earlier work, providing poplars with ample nitrogen led to higher accumulation of CTs across root zones. To test the functional importance of CTs in roots directly, CT-modified transgenic plants could be important tools.
PubMed: 38721337
DOI: 10.3389/fpls.2024.1388549 -
Frontiers in Physiology 2024The loose-patch clamp technique was first developed and used in native amphibian skeletal muscle (SkM), offering useful features complementing conventional sharp...
Loose-patch clamp analysis applied to voltage-gated ionic currents following pharmacological ryanodine receptor modulation in murine hippocampal cornu ammonis-1 pyramidal neurons.
INTRODUCTION
The loose-patch clamp technique was first developed and used in native amphibian skeletal muscle (SkM), offering useful features complementing conventional sharp micro-electrode, gap, or conventional patch voltage clamping. It demonstrated the feedback effects of pharmacological modification of ryanodine receptor (RyR)-mediated Ca release on the Na channel (Nav1.4) currents, initiating excitation-contraction coupling in native murine SkM. The effects of the further RyR and Ca-ATPase (SERCA) antagonists, dantrolene and cyclopiazonic acid (CPA), additionally implicated background tubular-sarcoplasmic Ca domains in these actions.
MATERIALS AND METHODS
We extend the loose-patch clamp approach to ion current measurements in murine hippocampal brain slice cornu ammonis-1 (CA1) pyramidal neurons. We explored the effects on Na currents of pharmacologically manipulating RyR and SERCA-mediated intracellular store Ca release and reuptake. We adopted protocols previously applied to native skeletal muscle. These demonstrated Ca-mediated feedback effects on the Na channel function.
RESULTS
Experiments applying depolarizing 15 ms duration loose-patch clamp steps to test voltages ranging from -40 to 120 mV positive to the resting membrane potential demonstrated that 0.5 mM caffeine decreased inward current amplitudes, agreeing with the previous SkM findings. It also decreased transient but not prolonged outward current amplitudes. However, 2 mM caffeine affected neither inward nor transient outward but increased prolonged outward currents, in contrast to its increasing inward currents in SkM. Furthermore, similarly and in contrast to previous SkM findings, both dantrolene (10 μM) and CPA (1 μM) pre-administration left both inward and outward currents unchanged. Nevertheless, dantrolene pretreatment still abrogated the effects of subsequent 0.5- and 2-mM caffeine challenges on both inward and outward currents. Finally, CPA abrogated the effects of 0.5 mM caffeine on both inward and outward currents, but with 2 mM caffeine, inward and transient outward currents were unchanged, but sustained outward currents increased.
CONCLUSION
We, thus, extend loose-patch clamping to establish pharmacological properties of murine CA1 pyramidal neurons and their similarities and contrasts with SkM. Here, evoked though not background Ca-store release influenced Nav and Kv excitation, consistent with smaller contributions of background store Ca release to resting [Ca]. This potential non-canonical mechanism could modulate neuronal membrane excitability or cellular firing rates.
PubMed: 38720787
DOI: 10.3389/fphys.2024.1359560 -
Scientific Reports May 2024Enterochromaffin (EC) cells located within the intestinal mucosal epithelium release serotonin (5-HT) to regulate motility tones, barrier function and the immune system....
Enterochromaffin (EC) cells located within the intestinal mucosal epithelium release serotonin (5-HT) to regulate motility tones, barrier function and the immune system. Electroanalytical methodologies have been able to monitor steady state basal extracellular 5-HT levels but are unable to provide insight into how these levels are influenced by key regulatory processes such as release and uptake. We established a new measurement approach, amperometry approach curve profiling, which monitors the extracellular 5-HT level at different electrode-tissue (E-T) distances. Analysis of the current profile can provide information on contributions of regulatory components on the observed extracellular 5-HT level. Measurements were conducted from ex vivo murine ileum and colon using a boron-doped diamond (BDD) microelectrode. Amperometry approach curve profiling coupled with classical pharmacology demonstrated that extracellular 5-HT levels were significantly lower in the colon when compared to the ileum. This difference was due to a greater degree of activity of the 5-HT transporter (SERT) and a reduced amount of 5-HT released from colonic EC cells. The presence of an inhibitory 5-HT autoreceptor was observed in the colon, where a 40% increase in extracellular 5-HT was the half maximal inhibitory concentration for activation of the autoreceptor. This novel electroanalytical approach allows estimates of release and re-uptake and their contribution to 5-HT extracellular concentration from intestinal tissue be obtained from a single series of measurements.
Topics: Serotonin; Animals; Mice; Ileum; Intestinal Mucosa; Colon; Enterochromaffin Cells; Microelectrodes; Serotonin Plasma Membrane Transport Proteins; Male; Electrochemical Techniques; Mice, Inbred C57BL
PubMed: 38714793
DOI: 10.1038/s41598-024-61296-9 -
MedRxiv : the Preprint Server For... Apr 2024Intracortical microstimulation (ICMS) is a method for restoring sensation to people with paralysis as part of a bidirectional brain-computer interface to restore upper...
Intracortical microstimulation (ICMS) is a method for restoring sensation to people with paralysis as part of a bidirectional brain-computer interface to restore upper limb function. Evoking tactile sensations of the hand through ICMS requires precise targeting of implanted electrodes. Here we describe the presurgical imaging procedures used to generate functional maps of the hand area of the somatosensory cortex and subsequent planning that guided the implantation of intracortical microelectrode arrays. In five participants with cervical spinal cord injury, across two study locations, this procedure successfully enabled ICMS-evoked sensations localized to at least the first four digits of the hand. The imaging and planning procedures developed through this clinical trial provide a roadmap for other brain-computer interface studies to ensure successful placement of stimulation electrodes.
PubMed: 38712177
DOI: 10.1101/2024.04.26.24306239 -
ACS Sensors May 2024In this work, we present the development of the first implantable aptamer-based platinum microelectrode for continuous measurement of a nonelectroactive molecule,...
In this work, we present the development of the first implantable aptamer-based platinum microelectrode for continuous measurement of a nonelectroactive molecule, neuropeptide Y (NPY). The aptamer immobilization was performed via conjugation chemistry and characterized using cyclic voltammetry before and after the surface modification. The redox label, methylene blue (MB), was attached at the end of the aptamer sequence and characterized using square wave voltammetry (SWV). NPY standard solutions in a three-electrode cell were used to test three aptamers in steady-state measurement using SWV for optimization. The aptamer with the best performance in the steady-state measurements was chosen, and continuous measurements were performed in a flow cell system using intermittent pulse amperometry. Dynamic measurements were compared against confounding and similar peptides such as pancreatic polypeptide and peptide YY, as well as somatostatin to determine the selectivity in the same modified microelectrode. Our Pt-microelectrode aptamer-based NPY biosensor provides signals 10 times higher for NPY compared to the confounding molecules. This proof-of-concept shows the first potential implantable microelectrode that is selectively sensitive to NPY concentration changes.
Topics: Neuropeptide Y; Microelectrodes; Biosensing Techniques; Platinum; Aptamers, Nucleotide; Electrochemical Techniques
PubMed: 38709872
DOI: 10.1021/acssensors.4c00449 -
Heliyon May 2024In this clinical trial, we evaluated the effects of transcutaneous electroacupoint stimulation (TEAS) on postoperative fatigue (POF) in Parkinson disease (PD) patients...
BACKGROUND
In this clinical trial, we evaluated the effects of transcutaneous electroacupoint stimulation (TEAS) on postoperative fatigue (POF) in Parkinson disease (PD) patients undergoing deep brain stimulation (DBS) surgery.
METHODS
A total 60 PD patients undergoing DBS surgery were enrolled. They were randomized to receive either electrical stimulation [alternative frequency 2/10 Hz, dense and disperse, intensity adjusted to the maximum tolerated by the participants (6-15 mAmp)] via surface electrodes (TEAS group) or surface electrodes only without electrical stimulation (Con group) at bilateral Zusanli and Sanyinjiao acupuncture points. All participants received their assigned intervention (TEAS or Con) during the 1st stage of surgery [(except during microelectrode recording (MER)] and the entire 2nd stage of surgery. Intraoperative anesthetic requirements were adjusted based on bispectral index (BIS) monitor. POF was assessed by Christensen fatigue scales (ChrFS), along with Quality of Recovery-15 (QoR-15) and mini-mental state examination (MMSE) postoperatively over a 7-day-period. We recorded the usage of rescue analgesics and anti-emetics.
RESULTS
Fifty-nine patients' datasets were included for final analyses. Fewer patients in TEAS experienced severe POF (defined as ChrFS ≥6) at T than those in the Con group (TEAS vs. Con: 7 vs. 22, p < 0.001). During the 1st stage of surgery, more patients in Con group required dexmedetomidine infusion (TEAS vs. Con: 2 vs. 6; P < 0.01). Total dosages of propofol and remifanil during the 2nd stage of surgery were TEAS vs. Con: 374.7 ± 61.2 vs 421.5 ± 81.9; p < 0.001 and 572.3 ± 82.0 vs. 662 ± 148.2; P < 0.001, respectively. Postoperative rescue analgesics (TEAS vs. Con: 2 vs. 6; P < 0.001) were used less in the TEAS group. TEAS patients reported better POF, MMSE and QoR15 scores than those in the Con group during most of the assessment period.
CONCLUSIONS
Intraoperative TEAS decreased the severity of POF, reduced intraoperative anesthetic requirements and facilitated post-DBS recovery in this group of PD patients.
PubMed: 38707419
DOI: 10.1016/j.heliyon.2024.e30012 -
Biological Psychiatry Global Open... Jul 2024Development of synaptic activity is a key neuronal characteristic that relies largely on interactions between neurons and astrocytes. Although astrocytes have known...
BACKGROUND
Development of synaptic activity is a key neuronal characteristic that relies largely on interactions between neurons and astrocytes. Although astrocytes have known roles in regulating synaptic function and malfunction, the use of human- or donor-specific astrocytes in disease models is still rare. Rodent astrocytes are routinely used to enhance neuronal activity in cell cultures, but less is known about how human astrocytes influence neuronal activity.
METHODS
We established human induced pluripotent stem cell-derived neuron-astrocyte cocultures and studied their functional development on microelectrode array. We used cell lines from 5 neurotypical control individuals and 3 pairs of monozygotic twins discordant for schizophrenia. A method combining NGN2 overexpression and dual SMAD inhibition was used for neuronal differentiation. The neurons were cocultured with human induced pluripotent stem cell-derived astrocytes differentiated from 6-month-old astrospheres or rat astrocytes.
RESULTS
We found that the human induced pluripotent stem cell-derived cocultures developed complex network bursting activity similar to neuronal cocultures with rat astrocytes. However, the effect of NMDA receptors on neuronal network burst frequency (NBF) differed between cocultures containing human or rat astrocytes. By using cocultures derived from patients with schizophrenia and unaffected individuals, we found lowered NBF in the affected cells. We continued by demonstrating how astrocytes from an unaffected individual rescued the lowered NBF in the affected neurons by increasing NMDA receptor activity.
CONCLUSIONS
Our results indicate that astrocytes participate in the regulation of neuronal NBF through a mechanism that involves NMDA receptors. These findings shed light on the importance of using human and donor-specific astrocytes in disease modeling.
PubMed: 38706704
DOI: 10.1016/j.bpsgos.2024.100313 -
Analytica Chimica Acta Jun 2024The Caco-2 cells were used as intestinal epithelial cell model to illustrate the hyperuricemia (HUA) mechanism under the co-culture of the imbalanced intestinal...
The Caco-2 cells were used as intestinal epithelial cell model to illustrate the hyperuricemia (HUA) mechanism under the co-culture of the imbalanced intestinal microbiome in this work. The uric acid (UA) concentration in the HUA process was monitored, and could be up to 425 μmol/L at 8 h co-cultured with the imbalanced intestinal microbiome. Single-cell potentiometry based on ion-selective microelectrode was used to study extracellular calcium change, which is hypothesized to play an important role in the UA excretion. The potential signal of the calcium in the extremely limited microenvironment around single Caco-2 cell was recorded through the single-cell analysis platform. The potential signal of sharp decrease and slow increase followed within a few seconds indicates the sudden uptake and gradually excretion process of calcium through the cell membrane. Moreover, the value of the potential decrease increases with the increase of the time co-cultured with the imbalanced intestinal microbiome ranging from 0 to 8 h. The Ca concentration around the cell membrane could decrease from 1.3 mM to 0.4 mM according to the potential decrease of 27.0 mV at the co-culture time of 8 h. The apoptosis ratio of the Caco-2 cells also exhibits time dependent with the co-culture of the imbalanced intestinal microbiome, and was 39.1 ± 3.6 % at the co-culture time of 8 h, which is much higher than the Caco-2 cells without any treatment (3.9 ± 2.9 %). These results firstly provide the links between the UA excretion with the apoptosis of the intestinal epithelial cell under the interaction of the imbalanced intestinal microbiome. Moreover, the apoptosis could be triggered by the calcium signaling.
Topics: Single-Cell Analysis; Caco-2 Cells; Humans; Microelectrodes; Coculture Techniques; Calcium; Carbon Fiber; Gastrointestinal Microbiome; Intestines; Potentiometry; Adenosine; Apoptosis
PubMed: 38692795
DOI: 10.1016/j.aca.2024.342615