Comparing virtual reality, desktop-based 3D, and 2D versions of a category learning experiment.

Virtual reality (VR) has seen increasing application in cognitive psychology in recent years. There is some debate about the impact of VR on both learning outcomes and on patterns of information access behaviors. In this study we compare performance on a category learning task between three groups: one presented with three-dimensional (3D) stimuli while immersed in the HTC Vive VR system (n = 26), another presented with the same 3D stimuli while using a flat-screen desktop computer (n = 26), and a third presented with a two-dimensional projection of the stimuli on a desktop computer while their eye movements were tracked (n = 8). In the VR and 3D conditions, features of the object to be categorized had to be revealed by rotating the object. In the eye tracking control condition (2D), all object features were visible, and participants' gaze was tracked as they examined each feature. Over 240 trials we measured accuracy, reaction times, attentional optimization, time spent on feedback, fixation durations, and fixation counts for each participant as they learned to correctly categorize the stimuli. In the VR condition, participants had increased fixation counts compared to the 3D and 2D conditions. Reaction times for the 2D condition were significantly faster and fixation durations were lower compared to the VR and 3D conditions. We found no significant differences in learning accuracy between the VR, 3D, and 2D conditions. We discuss implications for both researchers interested in using VR to study cognition, and VR developers hoping to use non-VR research to guide their designs and applications.

SAGES white paper on the current state of community practice surgeons: re-discovering the value of our community practice surgeons.

BACKGROUND: The Community Practice (CP) surgeon is the first point of access to surgical care globally and performs the majority of procedures in the USA. CP surgeons include those of various practice models, locations and communities, education and training, and much more. It is a diverse group that drives quality, access to care, research, and innovation. The SAGES CP Committee was formed to better define the role and highlight the contribution of the CP surgeon, as well as advocate for the position of CP surgeons in our society. METHODS: In 2018, a survey was distributed to the SAGES membership asking members to self-identify as either a Community Surgeon or Academic Surgeon. RESULTS: The majority (71%) of SAGES members surveyed self-identified as "Community Surgeons." This was in stark contrast to the distribution of Community versus Academic Surgeons in SAGES leadership (25% versus 75%, respectively). CONCLUSION: By better defining the characteristics and role of the CP, SAGES will be better informed on how to effectively engage with this large group within the society and increase its representation within the leadership. The CP Committee met on a biannual basis over a period of two years focusing on assessing their role in the SAGES organization. The committee members created the following initial goals: (1) define in a broad sense the characteristics of a CP Surgeon, (2) discuss and characterize the value of the CP surgeons, (3) highlight past and future areas of contributions of the group, and (4) delineate ways to engage and represent this subgroup. This manuscript is a culmination of the work of this committee while also serving as a way to support the initiatives and direction of SAGES leadership.

Single-site laparoscopic (SSL) cholecystectomy in human cadavers using a novel percutaneous instrument platform and a magnetic anchoring and guidance system (MAGS): reestablishing the "critical view".

INTRODUCTION: SSL introduces ergonomic challenges while establishing the critical view during dissection of the Triangle of Calot (TOC). This study investigates the use of a novel percutaneous instrument platform and MAGS in performing SSL cholecystectomy with a technique that closely mimics four-port cholecystectomy. METHODS: SSL cholecystectomy was performed on four female cadavers via a 15-18-mm incision made at the umbilicus for introduction of these devices and the working port. MAGS comprises an internal effector with a retractable monopolar cautery hook coupled across the abdominal wall to an external magnet held by the surgeon. The novel grasper was introduced percutaneously in the RUQ and comprises a 3-mm transabdominal shaft mated to a 5-mm end effector intracorporeally. Retraction was accomplished using the percutaneous grasper to manipulate the fundus and a standard 5-mm grasper at the umbilicus for the infundibulum. Dissection was performed by using a combination of the MAGS and a standard Maryland dissector. Total procedure time, time from procedure start to obtain a critical view of the TOC and clipping and dividing the cystic duct/artery, time for dissection of the gallbladder from the liver bed, and thickness of the abdominal wall at the umbilicus were measured. RESULTS: The critical view was obtained in each case, and all four procedures were completed successfully. Mean procedure time was 40 (range, 33-51) min; time from procedure start to obtaining the critical view and clipping and dividing the cystic duct/artery was 33 (range, 28-38) min, and time for dissection of the gallbladder from the liver bed was 6.7 (range, 3-13) min. The mean abdominal wall thickness was 1.9 (range, 1.5-2) cm. CONCLUSIONS: The use of a novel graspers and MAGS overcomes the limitations of SSL cholecystectomy and improves surgeon dexterity. Making SSL feel more like traditional laparoscopy will enable a wider adoption of this procedure in the community.

Mesh fixation with a barbed anchor suture results in significantly less strangulation of the abdominal wall.

BACKGROUND: Laparoscopic ventral hernia repair using an underlay mesh frequently requires suture fixation across the abdominal wall, which results in significant postoperative pain. This study investigates the utility of a novel mesh fixation technique to reduce the strangulation force on the abdominal wall. METHODS: Multiple 2-cm(2) pieces of polyester mesh (Parietex Composite, Covidien) were placed as an underlay against a porcine abdominal wall. Fixation was accomplished using either the standard 0-polyglyconate or the 0-polyglyconate barbed anchor suture designed to hold in tissue without the need to tie a knot (V-Loc 180; Covidien). Suture fixation began with a stab wound incision in the skin. A suture-passing device then was used to pass the suture across the abdominal wall and through the mesh. The suture passer was removed and reintroduced through the same stab wound incision but at a different fascial entry point 1.5 cm away. The tail of the suture was grasped and pulled up through both the mesh and the abdominal wall, creating a full-thickness U-stitch. One tail of the suture was attached to a tensiometer, and the strangulation force on the abdominal wall was measured while the suture was tied (standard) or looped (barbed). To compare pullout force, the tensiometer was attached to either the mesh or the suture, and traction was applied until material failure or suture pull through. Results are expressed as mean ± standard deviation. Comparisons were performed using Student's t-test. RESULTS: Eight pieces of mesh were placed for each suture. The average force required to secure the barbed suture (0.59 ± 0.08 kg) was significantly less than the force needed to secure the standard suture (2.17 ± 0.58 kg) (P < 0.0001). Table 1 compares the suture pullout forces with the mesh failure forces. Although the pullout force for the standard suture is significantly greater than for the barbed suture, both sutures have a pullout strength significantly greater than the mesh failure force. Table 1 Suture fixation forces for standard and barbed sutures Suture fixation force (kg) Standard suture 2.17 ± 0.58 Barbed suture 0.59 ± 0.08 P < 0.0001 CONCLUSIONS: A barbed anchor suture used to secure mesh to the abdominal wall requires nearly 75% less strangulation force than a standard monofilament suture while still providing significantly greater pullout force than that required for the mesh to tear and fail. This method of mesh fixation should result in less postoperative pain and warrants a clinical trial.

"Chopstick" surgery: a novel technique improves surgeon performance and eliminates arm collision in robotic single-incision laparoscopic surgery.

INTRODUCTION: Single-incision laparoscopic surgery (SILS) is limited by the coaxial arrangement of the instruments. A surgical robot with wristed instruments could overcome this limitation, but the arms often collide when working coaxially. This study tests a new technique of "chopstick" surgery to enable use of the robotic arms through a single incision without collision. METHODS: Experiments were conducted utilizing the da Vinci S robot (Intuitive Surgical, Inc., Sunnyvale, CA) in a Fundamentals of Laparoscopic Surgery (FLS) box trainer with three laparoscopic ports (1 x 12 mm, 2 x 5 mm) introduced through a single "incision." Pilot work determined the optimal setup for SILS to be a triangular port arrangement with 2-cm trocar distance and remote center at the abdominal wall. Using this setup, five experienced robotic surgeons performed three FLS tasks utilizing either a standard robotic arm setup or the chopstick technique. The chopstick arrangement crosses the instruments at the abdominal wall so that the right instrument is on the left side of the target and the left instrument on the right. This results in separation of the robotic arms outside the box. To correct for the change in handedness, the robotic console is instructed to drive the "left" instrument with the right-hand effector and the "right" instrument with the left. Performances were compared while measuring time, errors, number of clutching maneuvers, and degree of instrument collision (Likert scale 1-4). RESULTS: Compared with the standard setup, the chopstick configuration increased surgeon dexterity and global performance through significantly improved performance times, eliminating instrument collision, and decreasing number of camera manipulations, clutching maneuvers, and errors during all tasks. CONCLUSION: Chopstick surgery significantly enhances the functionality of the surgical robot when working through a small single incision. This technique will enable surgeons to utilize the robot for SILS and possibly for intraluminal or transluminal surgery.

Alcohol-induced alterations in hepatic microtubule dynamics can be explained by impaired histone deacetylase 6 function.

UNLABELLED: We have been using polarized, hepatic WIF-B cells to examine ethanol-induced liver injury. These cells polarize in culture and maintain numerous liver-specific activities including the ability to metabolize alcohol. Previously, we found that microtubules were more highly acetylated and more stable in ethanol-treated WIF-B cells and that increased microtubule acetylation required ethanol metabolism and was likely mediated by acetaldehyde. This study was aimed at identifying the mechanism responsible for increased microtubule acetylation. We examined the expression of two known microtubule deacetylases, histone deacetylase 6 (HDAC6) and Sirtuin T2 (SirT2), in WIF-B cells. Immunoblotting, immunofluorescence microscopy, and assays using the SirT2 inhibitor nicotinamide revealed that WIF-B cells do not express SirT2. In contrast, HDAC6 was highly expressed in WIF-B cells. Addition of trichostatin A (TSA), an HDAC6 inhibitor, induced microtubule acetylation to the same extent as in ethanol-treated cells (approximately threefold). Although immunofluorescence labeling revealed that HDAC6 distribution did not change in ethanol-treated cells, immunoblotting showed HDAC6 protein levels slightly decreased. HDAC6 solubility was increased in nocodazole-treated cells, suggesting impaired microtubule binding. Direct microtubule binding assays confirmed this hypothesis. The decreased microtubule binding was partially prevented by 4-methyl pyrazole, indicating the effect was in part mediated by acetaldehyde. Interestingly, HDAC6 from ethanol-treated cells was able to bind and deacetylate exogenous tubulin to the same extent as control, suggesting that ethanol-induced tubulin modifications prevented HDAC6 binding to endogenous microtubules. CONCLUSION: We propose that lower HDAC6 levels combined with decreased microtubule binding lead to increased tubulin acetylation in ethanol-treated cells.

Microtubule acetylation and stability may explain alcohol-induced alterations in hepatic protein trafficking.

UNLABELLED: We have been using polarized hepatic WIF-B cells to examine ethanol-induced liver injury. Previously, we determined microtubules were more highly acetylated and more stable in ethanol-treated WIF-B cells. We proposed that the ethanol-induced alterations in microtubule dynamics may explain the ethanol-induced defects in membrane trafficking that have been previously documented. To test this, we compared the trafficking of selected proteins in control cells and cells treated with ethanol or with the histone deacetylase 6 inhibitor trichostatin A (TSA). We determined that exposure to 50 nM TSA for 30 minutes induced microtubule acetylation ( approximately 3-fold increase) and stability to the same extent as did ethanol. As shown previously in situ, the endocytic trafficking of the asialoglycoprotein receptor (ASGP-R) was impaired in ethanol-treated WIF-B cells. This impairment required ethanol metabolism and was likely mediated by acetaldehyde. TSA also impaired ASGP-R endocytic trafficking, but to a lesser extent. Similarly, both ethanol and TSA impaired transcytosis of the single-spanning apical resident aminopeptidase N (APN). For both ASGP-R and APN and for both treatments, the block in trafficking was internalization from the basolateral membrane. Interestingly, no changes in transcytosis of the glycophosphatidylinositol-anchored protein, 5'-nucleotidase, were observed, suggesting that increased microtubule acetylation and stability differentially regulate internalization. We further determined that albumin secretion was impaired in both ethanol-treated and TSA-treated cells, indicating that increased microtubule acetylation and stability also disrupted this transport step. CONCLUSION: These results indicate that altered microtubule dynamics explain in part alcohol-induced defects in membrane trafficking.