Safety of intracranial electrodes in an MRI environment: a technical report.

INTRODUCTION: Intracranial electroencephalography (iEEG) involves placing intracranial electrodes to localise seizures in patients with medically refractory epilepsy. While magnetic resonance imaging (MRI) enables visualisation of electrodes within patient-specific anatomy, the safety of these electrodes must be confirmed prior to routine clinical utilisation. Therefore, the purpose of this study was to evaluate the safety of iEEG electrodes from a particular manufacturer in a 3.0-Tesla (3.0T) MRI environment. METHODS: Measurements of magnetically induced displacement force and torque were determined for each of the 10 test articles using standardised techniques. Test articles were subsequently evaluated for radiofrequency-induced heating using a Perspex phantom in both open and 'fault' conditions. Additionally, we assessed radiofrequency (RF)-induced heating with all test articles placed into the phantom simultaneously to simulate an implantation, again in both open and 'fault' conditions. Finally, each test article was evaluated for MRI artefacts. RESULTS: The magnetically induced displacement force was found to be less than the force on the article due to gravity for all test articles. Similarly, the maximum magnetically induced torque was less than the worst-case torque due to gravity for all test articles apart from the 8-contact strip - for which it was 11% greater - and the depthalon cap. The maximum temperature change for any portion of any test article assessed individually was 1.7°C, or 1.2°C for any device component meant to be implanted intracranially. In the implantation configuration, the maximum recorded temperature change was 0.7°C. CONCLUSIONS: MRI may be safely performed for localising iEEG electrodes at 3.0T under certain conditions.

Endoscopic ultrasound-directed transgastric ERCP (EDGE): A multicenter US study on long-term follow-up and fistula closure.

Background and study aims Endoscopic ultrasound-directed transgastric ERCP (EDGE) is a safe and efficacious procedure to treat pancreaticobiliary diseases in Roux-en-Y gastric bypass (RYGB). This multicenter study aimed to determine the long-term outcomes of EDGE focusing on fistula persistence rates and post-procedure weight change. Patients and methods Information about patients with Roux-en-Y gastric bypass anatomy who underwent EDGE between 2015 and 2021 from 10 institutions was captured in a registry. Patient demographics, procedural details, and clinical outcomes were analyzed. Results One hundred seventy-two patients were included in the study (mean age 60, 25 % male). Technical success of lumen-apposing metal stent (LAMS) placement was 171 of 172 (99.4 %) while clinical success of intervention was 95%. The mean procedure time was 65 minutes. The most commonly reported complication was stent dislodgement/migration (n = 29, 17). Mean length of time of LAMS duration was 69 days. Mean follow-up time was 6 months. Endoscopic fistula closure was performed in 40 % of patients (69/172) at the time of LAMS removal. Persistence of fistula was observed in 19 of 62 patients (31 %) assessed. Length of LAMS indwell time (days) was a predictor of persistent fistula. The average weight gain while the LAMS was in place was 12 lb in 63 patients (36.6 %); 59.4 % of patients gained < 5 lb. Conclusions EDGE is a safe and efficacious procedure for RYGB patients requiring ERCP. Post-procedure evaluation and management of the enteral fistula varies widely among centers currently and would benefit from further standardization. Fistula persistence appears to be uncommon and can be managed endoscopically but may be related to length of indwell times of the LAMS.

Impacted gallstone within a cholecystoduodenal fistula: endoscopic laser lithotripsy to the rescue.

Video 1A large, impacted gallstone is treated unsuccessfully with electrohydraulic lithotripsy; however, fragmentation and removal is accomplished using endoscopic laser lithotripsy.

Comparing the Safety and Efficacy of Two Commercially Available Single-Use Duodenoscopes: A Multicenter Study.

INTRODUCTION: Single-use disposable duodenoscopes (SDD) have been developed to mitigate infectious risks related to reusable duodenoscopes. The aim of this study is to compare the safety and efficacy of the two available SDDs in the United States. METHODS: We conducted a comparative study of 2 SDD in consecutive ERCP procedures performed by expert endoscopists from 9 academic centers. Performance ratings, procedure details, and adverse events were collected. RESULTS: A total of 201 patients were included: 129 patients underwent ERCP with Exalt (mean age 63, Males- 66 (51%), 72 with aScope Duodeno (mean age 65, males=30 (42%). A majority of endoscopists had performed >2000 ERCPs in both groups (71% Exalt, 93% aScope Duodeno). Technical success was 92% in both groups (n=119 Exalt-group, n=66 aScope-Duodeno-group). The procedural complexity for the ERCP cases performed were: Grade 1: 35 cases (18%), Grade 2: 83 cases (41%), Grade 3: 65 cases (32%), and Grade 4: 18 cases (9%). Thirteen patients (10%) from the Exalt group and 16 patients (22%) from the aScope Duodeno group required conversion to a reusable duodenoscope. On a scale of 1 to 5, Exalt and aScope Duodeno, respectively, were rated: 2.31 versus 2.60 for location and visualization quality, 1.38 versus 1.57 for maneuverability based on papillary orientation, 1.48 versus 1.15 for suction/air control, and 2.31 versus 2.34 for elevator efficiency. None of the adverse events were related to the SDDs. CONCLUSIONS: The 2 SDDs were comparable. Further ongoing enhancements to these devices will improve maneuverability and clinical effectiveness.

An examination of the Kuleshov effect using still photographs.

The goal of the present study was to examine whether the effect of visual context on the interpretation of facial expression from an actor's face could be produced using isolated photographic stills, instead of the typical dynamic film sequences used to demonstrate the effect. Two-photograph sequences consisting of a context photograph varying in pleasantness and a photograph of an actor's neutral face were presented. Participants performed a liking rating task for the context photograph (to ensure attention to the stimulus) and they performed three tasks for the face stimulus: labeling the emotion portrayed by the actor, rating valence, and rating arousal. The results of the labeling data confirmed the existence of a visual context effect, with more faces labeled as "happy" after viewing pleasant context and more faces labeled "sad" or "fearful" after viewing unpleasant context. This effect was demonstrated when no explicit connection between the context stimulus and face stimulus was invoked, with the contextual information exerting its effect on labeling after being held in memory for at least 10 seconds. The results for ratings of valence and arousal were mixed. Overall, the results suggest that isolated photograph sequences produce a Kuleshov-type context effect on attributions of emotion to actors' faces, replicating previous research conducted with dynamic film sequences.

Learning and memory deficits in mice lacking protease activated receptor-1.

The roles of serine proteases and protease activated receptors have been extensively studied in coagulation, wound healing, inflammation, and neurodegeneration. More recently, serine proteases have been suggested to influence synaptic plasticity. In this context, we examined the role of protease activated receptor 1 (PAR1), which is activated following proteolytic cleavage by thrombin and plasmin, in emotionally motivated learning. We were particularly interested in PAR1 because its activation enhances the function of NMDA receptors, which are required for some forms of synaptic plasticity. We examined several baseline behavioral measures, including locomotor activity, expression of anxiety-like behavior, motor task acquisition, nociceptive responses, and startle responses in C57Bl/6 mice in which the PAR1 receptor has been genetically deleted. In addition, we evaluated learning and memory in these mice using two memory tasks, passive avoidance and cued fear-conditioning. Whereas locomotion, pain response, startle, and measures of baseline anxiety were largely unaffected by PAR1 removal, PAR1-/- animals showed significant deficits in a passive avoidance task and in cued fear conditioning. These data suggest that PAR1 may play an important role in emotionally motivated learning.

Subunit-specific mechanisms and proton sensitivity of NMDA receptor channel block.

We have compared the potencies of structurally distinct channel blockers at recombinant NR1/NR2A, NR1/NR2B, NR1/NR2C and NR1/NR2D receptors. The IC50 values varied with stereochemistry and subunit composition, suggesting that it may be possible to design subunit-selective channel blockers. For dizocilpine (MK-801), the differential potency of MK-801 stereoisomers determined at recombinant NMDA receptors was confirmed at native receptors in vitro and in vivo. Since the proton sensor is tightly linked both structurally and functionally to channel gating, we examined whether blocking molecules that interact in the channel pore with the gating machinery can differentially sense protonation of the receptor. Blockers capable of remaining trapped in the pore during agonist unbinding showed the strongest dependence on extracellular pH, appearing more potent at acidic pH values that promote channel closure. Determination of pK(a) values for channel blockers suggests that the ionization of ketamine but not of other blockers can influence its pH-dependent potency. Kinetic modelling and single channel studies suggest that the pH-dependent block of NR1/NR2A by (-)MK-801 but not (+)MK-801 reflects an increase in the MK-801 association rate even though protons reduce channel open probability and thus MK-801 access to its binding site. Allosteric modulators that alter pH sensitivity alter the potency of MK-801, supporting the interpretation that the pH sensitivity of MK-801 binding reflects the changes at the proton sensor rather than a secondary effect of pH. These data suggest a tight coupling between the proton sensor and the ion channel gate as well as unique subunit-specific mechanisms of channel block.