The ultrastructure of macaque mesencephalic trigeminal nucleus neurons.

Primary afferents originating from the mesencephalic trigeminal nucleus provide the main source of proprioceptive information guiding mastication, and thus represent an important component of this critical function. Unlike those of other primary afferents, their cell bodies lie within the central nervous system. It is believed that this unusual central location allows them to be regulated by synaptic input. In this study, we explored the ultrastructure of macaque mesencephalic trigeminal nucleus neurons to determine the presence and nature of this synaptic input in a primate. We first confirmed the location of macaque mesencephalic trigeminal neurons by retrograde labeling from the masticatory muscles. Since the labeled neurons were by far the largest cells located at the edge of the periaqueductal gray, we could undertake sampling for electron microscopy based on soma size. Ultrastructurally, mesencephalic trigeminal neurons had very large somata with euchromatic nuclei that sometimes displayed deeply indented nuclear membranes. Terminal profiles with varied vesicle characteristics and synaptic density thicknesses were found in contact with either their somatic plasma membranes or somatic spines. However, in contradistinction to other, much smaller, somata in the region, the plasma membranes of the mesencephalic trigeminal somata had only a few synaptic contacts. They did extend numerous somatic spines of various lengths into the neuropil, but most of these also lacked synaptic contact. The observed ultrastructural organization indicates that macaque trigeminal mesencephalic neurons do receive synaptic contacts, but despite their central location, they only avail themselves of very limited input.

Brainstem sources of input to the central mesencephalic reticular formation in the macaque.

Physiological studies indicate that the central mesencephalic reticular formation (cMRF) plays a role in gaze changes, including control of disjunctive saccades. Neuroanatomical studies have demonstrated strong interconnections with the superior colliculus, along with projections to extraocular motor nuclei, the preganglionic nucleus of Edinger-Westphal, the paramedian pontine reticular formation, nucleus raphe interpositus, medullary reticular formation and cervical spinal cord, as might be expected for a structure that is intimately involved in gaze control. However, the sources of input to this midbrain structure have not been described in detail. In the present study, the brainstem cells of origin supplying the cMRF were labeled by retrograde transport of tracer (wheat germ agglutinin conjugated horseradish peroxidase) in macaque monkeys. Within the diencephalon, labeled neurons were noted in the ventromedial nucleus of the hypothalamus, pregeniculate nucleus and habenula. In the midbrain, labeled cells were found in the substantia nigra pars reticulata, medial pretectal nucleus, superior colliculus, tectal longitudinal column, periaqueductal gray, supraoculomotor area, and contralateral cMRF. In the pons they were located in the paralemniscal zone, parabrachial nucleus, locus coeruleus, nucleus prepositus hypoglossi and the paramedian pontine reticular formation. Finally, in the medulla they were observed in the medullary reticular formation. The fact that this list of input sources is very similar to those of the superior colliculus supports the view that the cMRF represents an important gaze control center.

Neural control of rapid binocular eye movements: Saccade-vergence burst neurons.

During normal viewing, we direct our eyes between objects in three-dimensional (3D) space many times a minute. To accurately fixate these objects, which are usually located in different directions and at different distances, we must generate eye movements with appropriate versional and vergence components. These combined saccade-vergence eye movements result in disjunctive saccades with a vergence component that is much faster than that generated during smooth, symmetric vergence eye movements. The neural control of disjunctive saccades is still poorly understood. Recent anatomical studies suggested that the central mesencephalic reticular formation (cMRF), located lateral to the oculomotor nucleus, contains premotor neurons potentially involved in the neural control of these eye movements. We have therefore investigated the role of the cMRF in the control of disjunctive saccades in trained rhesus monkeys. Here, we describe a unique population of cMRF neurons that, during disjunctive saccades, display a burst of spikes that are highly correlated with vergence velocity. Importantly, these neurons show no increase in activity for either conjugate saccades or symmetric vergence. These neurons are termed saccade-vergence burst neurons (SVBNs) to maintain consistency with modeling studies that proposed that such a class of neuron exists to generate the enhanced vergence velocities observed during disjunctive saccades. Our results demonstrate the existence and characteristics of SVBNs whose activity is correlated solely with the vergence component of disjunctive saccades and, based on modeling studies, are critically involved in the generation of the disjunctive saccades required to view objects in our 3D world.

Nitrogen in Diamond.

Nitrogen is ubiquitous in both natural and laboratory-grown diamond, but the number and nature of the nitrogen-containing defects can have a profound effect on the diamond material and its properties. An ever-growing fraction of the supply of diamond appearing on the world market is now lab-grown. Here, we survey recent progress in two complementary diamond synthesis methods-high pressure high temperature (HPHT) growth and chemical vapor deposition (CVD), how each is allowing ever more precise control of nitrogen incorporation in the resulting diamond, and how the diamond produced by either method can be further processed (e.g., by implantation or annealing) to achieve a particular outcome or property. The burgeoning availability of diamond samples grown under well-defined conditions has also enabled huge advances in the characterization and understanding of nitrogen-containing defects in diamond-alone and in association with vacancies, hydrogen, and transition metal atoms. Among these, the negatively charged nitrogen-vacancy (NV-) defect in diamond is attracting particular current interest in account of the many new and exciting opportunities it offers for, for example, quantum technologies, nanoscale magnetometry, and biosensing.

Superior colliculus projections to target populations in the supraoculomotor area of the macaque monkey.

A projection by the superior colliculus to the supraoculomotor area (SOA) located dorsal to the oculomotor complex was first described in 1978. This projection's targets have yet to be identified, although the initial study suggested that vertical gaze motoneuron dendrites might receive this input. Defining the tectal targets is complicated by the fact the SOA contains a number of different cell populations. In the present study, we used anterograde tracers to characterize collicular axonal arbors and retrograde tracers to label prospective SOA target populations in macaque monkeys. Close associations were not found with either superior or medial rectus motoneurons whose axons supply singly innervated muscle fibers. S-group motoneurons, which supply superior rectus multiply innervated muscle fibers, appeared to receive a very minor input, but C-group motoneurons, which supply medial rectus multiply innervated muscle fibers, received no input. A number of labeled boutons were observed in close association with SOA neurons projecting to the spinal cord, or the reticular formation in the pons and medulla. These descending output neurons are presumed to be peptidergic cells within the centrally projecting Edinger-Westphal population. It is possible the collicular input provides a signaling function for neurons in this population that serve roles in either stress responses, or in eating and drinking behavior. Finally, a number of close associations were observed between tectal terminals and levator palpebrae superioris motoneurons, suggesting the possibility that the superior colliculus provides a modest direct input for raising the eyelids during upward saccades.

Cerebellar projections to the macaque midbrain tegmentum: Possible near response connections.

Since most gaze shifts are to targets that lie at a different distance from the viewer than the current target, gaze changes commonly require a change in the angle between the eyes. As part of this response, lens curvature must also be adjusted with respect to target distance by the ciliary muscle. It has been suggested that projections by the cerebellar fastigial and posterior interposed nuclei to the supraoculomotor area (SOA), which lies immediately dorsal to the oculomotor nucleus and contains near response neurons, support this behavior. However, the SOA also contains motoneurons that supply multiply innervated muscle fibers (MIFs) and the dendrites of levator palpebrae superioris motoneurons. To better determine the targets of the fastigial nucleus in the SOA, we placed an anterograde tracer into this cerebellar nucleus in Macaca fascicularis monkeys and a retrograde tracer into their contralateral medial rectus, superior rectus, and levator palpebrae muscles. We only observed close associations between anterogradely labeled boutons and the dendrites of medial rectus MIF and levator palpebrae motoneurons. However, relatively few of these associations were present, suggesting these are not the main cerebellar targets. In contrast, labeled boutons in SOA, and in the adjacent central mesencephalic reticular formation (cMRF), densely innervated a subpopulation of neurons. Based on their location, these cells may represent premotor near response neurons that supply medial rectus and preganglionic Edinger-Westphal motoneurons. We also identified lens accommodation-related cerebellar afferent neurons via retrograde trans-synaptic transport of the N2c rabies virus from the ciliary muscle. They were found bilaterally in the fastigial and posterior interposed nuclei, in a distribution which mirrored that of neurons retrogradely labeled from the SOA and cMRF. Our results suggest these cerebellar neurons coordinate elements of the near response during symmetric vergence and disjunctive saccades by targeting cMRF and SOA premotor neurons.

Central mesencephalic reticular formation control of the near response: lens accommodation circuits.

To view a nearby target, the three components of the near response are brought into play: 1) the eyes are converged through contraction of the medial rectus muscles to direct both foveae at the target, 2) the ciliary muscle contracts to allow the lens to thicken, increasing its refractive power to focus the near target on the retina, and 3) the pupil constricts to increase depth of field. In this study, we utilized retrograde transsynaptic transport of the N2c strain of rabies virus injected into the ciliary body of one eye of macaque monkeys to identify premotor neurons that control lens accommodation. We previously used this approach to label a premotor population located in the supraoculomotor area. In the present report, we describe a set of neurons located bilaterally in the central mesencephalic reticular formation that are labeled in the same time frame as the supraoculomotor area population, indicating their premotor character. The labeled premotor neurons are mostly multipolar cells, with long, very sparsely branched dendrites. They form a band that stretches across the core of the midbrain reticular formation. This population appears to be continuous with the premotor near-response neurons located in the supraoculomotor area at the level of the caudal central subdivision of the oculomotor nucleus. The central mesencephalic reticular formation has previously been associated with horizontal saccadic eye movements, so these premotor cells might be involved in controlling lens accommodation during disjunctive saccades. Alternatively, they may represent a population that controls vergence velocity. NEW & NOTEWORTHY This report uses transsynaptic transport of rabies virus to provide new evidence that the central mesencephalic reticular formation (cMRF) contains premotor neurons controlling lens accommodation. When combined with other recent reports that the cMRF also contains premotor neurons supplying medial rectus motoneurons, these results indicate that this portion of the reticular formation plays an important role in directing the near response and disjunctive saccades when viewers look between targets located at different distances.

Academic neurosurgery in the UK: present and future directions.

Academic neurosurgery encompasses basic science and clinical research efforts to better understand and treat diseases of relevance to neurosurgical practice, with the overall aim of improving treatment and outcome for patients. In this article, we provide an overview of the current and future directions of British academic neurosurgery. Training pathways are considered together with personal accounts of experiences of structured integrated clinical academic training and unstructured academic training. Life as an academic consultant is also described. Funding is explored, for the specialty as a whole and at the individual level. UK academic neurosurgical organisations are highlighted. Finally, the UK's international standing is considered.

Motor cortex relocation after complete anatomical hemispherectomy for intractable epilepsy secondary to Rasmussen's encephalitis.

BACKGROUND: The authors report a case with interesting clinical and radiological outcomes following complete anatomical hemispherectomy. METHODS: A seven-year-old female with medically refractory epilepsy secondary to Rasmussen's encephalitis was treated with a complete right-sided anatomical hemispherectomy. RESULTS: Surgical intervention provided seizure relief, and at eleven-years post-operatively she was independently mobile, with spasticity of the upper limb. She had normal intellect and was pursuing higher education. Functional MRI found re-location of left-sided motor control to the remaining left hemisphere, alongside the existing motor cortex. CONCLUSION: This interesting case is a good example of effective neuroplasticity; motor functionality relocated an area in the contralateral hemisphere that already contained the prerequisite cellular architecture and white matter connectivity required to control movement.

Natural History and Predictors of Parastomal Hernia after Robot-Assisted Radical Cystectomy and Ileal Conduit Urinary Diversion.

PURPOSE: We investigated the prevalence of and variables associated with parastomal hernia and its outcomes after robot-assisted radical cystectomy and ileal conduit creation for bladder cancer. MATERIALS AND METHODS: We retrospectively reviewed the records of patients who underwent robot-assisted radical cystectomy at our institution. Parastomal hernia was defined as the protrusion of abdominal contents through the stomal defect in the abdominal wall on cross-sectional imaging. Parastomal hernia was further described in terms of patient and hernia characteristics, symptoms, management and outcomes. The Kaplan-Meier method was used to determine time to parastomal hernia and time to surgery. Multivariate stepwise logistic regression was done to evaluate variables associated with parastomal hernia. RESULTS: A total of 383 patients underwent robot-assisted radical cystectomy and ileal conduit creation. Of the patients 75 (20%) had parastomal hernia, which was symptomatic in 23 (31%), and 11 (15%) underwent treatment. Median time to parastomal hernia was 13 months (IQR 9-22). Parastomal hernia developed in 9%, 23% and 32% of cases at 1, 2 and 3 years, respectively. Patients with parastomal hernia had a significantly higher body mass index (30 vs 28 kg/m2, p = 0.02), longer overall operative time (357 vs 340 minutes, p = 0.01) and greater blood loss (325 vs 250 ml, p = 0.04). On multivariate analysis operative time (OR 1.25, 95% CI 1.21-3.90, p <0.001), a fascial defect 30 mm or greater (OR 5.23, 95% CI 2.32-11.8, p <0.001) and a lower postoperative estimated glomerular filtration rate (OR 2.17, 95% CI 1.21-3.90, p = 0.01) were significantly associated with parastomal hernia. CONCLUSIONS: Symptoms develop in approximately a third of patients with parastomal hernia and 15% will require surgery. The risk of parastomal hernia plateaued after postoperative year 3. Longer operative time, a larger fascial defect and lower postoperative kidney function were associated with parastomal hernia.

Outcomes of Intracorporeal Urinary Diversion after Robot-Assisted Radical Cystectomy: Results from the International Robotic Cystectomy Consortium.

PURPOSE: This study aimed to provide an update and compare perioperative outcomes and complications of intracorporeal and extracorporeal urinary diversion following robot-assisted radical cystectomy using data from the multi-institutional, prospectively maintained International Robotic Cystectomy Consortium database. MATERIALS AND METHODS: We retrospectively reviewed the records of 2,125 patients from a total of 26 institutions. Intracorporeal urinary diversion was compared with extracorporeal urinary diversion. Multivariate logistic regression models using stepwise variable selection were fit to evaluate preoperative, operative and postoperative predictors of intracorporeal urinary diversion, operative time, high grade complications and 90-day hospital readmissions after robot-assisted radical cystectomy. RESULTS: In our cohort 1,094 patients (51%) underwent intracorporeal urinary diversion. These patients demonstrated shorter operative time (357 vs 400 minutes), less blood loss (300 vs 350 ml) and fewer blood transfusions (4% vs 19%, all p <0.001). They experienced more high grade complications (13% vs 10%, p = 0.02). Intracorporeal urinary diversion use increased from 9% of all urinary diversions in 2005 to 97% in 2015. Complications after this procedure decreased significantly with time (p <0.001). On multivariable analysis higher annual cystectomy volume (OR 1.02, 95% CI 1.01-1.03, p <0.002), year of robot-assisted radical cystectomy (2013-2016 OR 68, 95% CI 44-105, p <0.001) and American Society of Anesthesiologists® score less than 3 (OR 1.75, 95% CI 1.38-2.22, p <0.001) were associated with undergoing intracorporeal urinary diversion. The procedure was associated with a shorter operative time of 27 minutes (p = 0.001). CONCLUSIONS: The use of intracorporeal urinary diversion has increased in the last decade. A higher annual institutional volume of robot-assisted radical cystectomy was associated with intracorporeal urinary diversion as well as with shorter operative time. Although intracorporeal urinary diversion was associated with higher grade complications than extracorporeal urinary diversion, they decreased with time.

Variability and interpretation of communication taxonomy during robot-assisted surgery: do we all speak the same language?

OBJECTIVE: To investigate and analyse the different ways surgeons communicate with bedside assistants during robot-assisted surgery (RAS). METHODS: We retrospectively reviewed video and audio recordings of 26 RAS procedures (23 prostatectomies and three cystectomies). Three cameras and eight lapel microphones were used to record the operating theatre environment. We identified five common tasks and categorized them into 'specific', 'non-specific' and 'unclear' categories. We also determined the frequency, time to execute the task, inconveniences and acknowledgements associated with each category. The most efficient category was the one that took the shortest duration to accomplish and was associated with the fewest inconveniences. RESULTS: A total of 1 000 requests were made by three surgeons for six bedside assistants by three surgeons. The five identified tasks were: instrument change; clipping; suction; irrigation; and retraction. For instrument change, non-specific requests were the most frequent compared with the other categories (77% vs 18% vs 5%; P < 0.001). For suction, specific requests were the most frequently used of the three categories (73% vs 27% vs 0%; P < 0.001) and this task was associated with the fewest inconveniences (38% vs 62%; P = 0.01). For clipping, irrigation and retraction, both specific and non-specific requests were similar in terms of their frequency, action time and inconveniences. Comparing complete vs incomplete requests, incomplete requests had significantly shorter median action time (5 vs 8 s; P < 0.001) but did not significantly differ in terms of inconveniences and acknowledgement. CONCLUSION: To our knowledge, this is the first study to provide a detailed analysis of communication during RAS. It lays a foundation for standardized taxonomy to improve communication, surgical efficiency and patient safety.

Development and validation of surgical training tool: cystectomy assessment and surgical evaluation (CASE) for robot-assisted radical cystectomy for men.

BACKGROUND: We aimed to develop a structured scoring tool: cystectomy assessment and surgical evaluation (CASE) that objectively measures and quantifies performance during robot-assisted radical cystectomy (RARC) for men. METHODS: A multinational 10-surgeon expert panel collaborated towards development and validation of CASE. The critical steps of RARC in men were deconstructed into nine key domains, each assessed by five anchors. Content validation was done utilizing the Delphi methodology. Each anchor was assessed in terms of context, score concordance, and clarity. The content validity index (CVI) was calculated for each aspect. A CVI ≥ 0.75 represented consensus, and this statement was removed from the next round. This process was repeated until consensus was achieved for all statements. CASE was used to assess de-identified videos of RARC to determine reliability and construct validity. Linearly weighted percent agreement was used to assess inter-rater reliability (IRR). A logit model for odds ratio (OR) was used to assess construct validation. RESULTS: The expert panel reached consensus on CASE after four rounds. The final eight domains of the CASE included: pelvic lymph node dissection, development of the peri-ureteral space, lateral pelvic space, anterior rectal space, control of the vascular pedicle, anterior vesical space, control of the dorsal venous complex, and apical dissection. IRR > 0.6 was achieved for all eight domains. Experts outperformed trainees across all domains. CONCLUSION: We developed and validated a reliable structured, procedure-specific tool for objective evaluation of surgical performance during RARC. CASE may help differentiate novice from expert performances.

The British Neurosurgical Trainee Research Collaborative: Five years on.

Since its inception in 2012, the British Neurosurgical Trainee Research Collaborative (BNTRC) has established itself as a robust example of a trainee-led research collaborative. This article summarises the work of the collaborative over its first 5 years of existence, outlining the structure, its research projects, impact and future directions.

Natural History, Predictors and Management of Ureteroenteric Strictures after Robot Assisted Radical Cystectomy.

PURPOSE: Ureteroenteric strictures represent the most common complication requiring reoperation after radical cystectomy. We investigated the prevalence, outcomes, predictors and management of ureteroenteric strictures. MATERIALS AND METHODS: We retrospectively reviewed our quality assurance, robot assisted radical cystectomy database to identify patients in whom ureteroenteric strictures developed. Data were reviewed for demographics, perioperative outcomes and ureteroenteric stricture characteristics. The Kaplan-Meier method was used to calculate time to ureteroenteric stricture and multivariable stepwise regression was done to evaluate predictors of ureteroenteric strictures. RESULTS: Ureteroenteric strictures developed in 12%, 16% and 19% of 51 patients (13%) at 1, 3 and 5 years after robot assisted radical cystectomy, respectively. All patients were initially treated endoscopically or percutaneously, including 57% treated only endoscopically or percutaneously and 43% who required surgery, which was open repair in 6 and robot assisted repair in 16. At a median followup of 23 months 33 patients (65%) were free of disease, including 13 after endoscopic or percutaneous treatment, 15 after robot assisted repair and 5 after open revision. Open and robot assisted revisions showed comparable perioperative outcomes. On multivariable analysis the predictors of ureteroenteric anastomotic strictures were body mass index (OR 1.07, 95% CI 1.01-1.13, p = 0.02), intracorporeal urinary diversion (OR 3.28, 95% CI 1.41-7.61, p = 0.006), length of the right resected ureter (OR 0.66, 95% CI 0.50-0.88, p = 0.004), estimated glomerular filtration rate 30 days after assisted radical cystectomy (OR 0.85, 95% CI 0.74-0.98, p = 0.03), urinary tract infection (OR 2.68, 95% CI 1.31-5.49, p = 0.007) and leakage (OR 3.85, 95% CI 1.05-14.1, p = 0.04). Male gender (OR 0.19, 95% CI 0.04-0.96, p = 0.04) and higher body mass index (OR 0.85, 95% CI 0.72-0.996, p = 0.05) were associated with lower odds of successful endoscopic management. CONCLUSIONS: Multiple modifiable factors were associated with ureteroenteric anastomotic strictures following robot assisted radical cystectomy. Surgical revision can provide a definitive management with comparable outcomes for open and robotic repairs.

Early Oncologic Failure after Robot-Assisted Radical Cystectomy: Results from the International Robotic Cystectomy Consortium.

PURPOSE: We sought to investigate the prevalence and variables associated with early oncologic failure. MATERIALS AND METHODS: We retrospectively reviewed the IRCC (International Radical Cystectomy Consortium) database of patients who underwent robot-assisted radical cystectomy since 2003. The final cohort comprised a total of 1,894 patients from 23 institutions in 11 countries. Early oncologic failure was defined as any disease relapse within 3 months of robot-assisted radical cystectomy. All institutions were surveyed for the pneumoperitoneum pressure used, breach of oncologic surgical principles, and techniques of specimen and lymph node removal. A multivariate model was fit to evaluate predictors of early oncologic failure. The Kaplan-Meier method was applied to depict disease specific and overall survival, and Cox proportional regression analysis was used to evaluate predictors of disease specific and overall survival. RESULTS: A total of 305 patients (22%) experienced disease relapse, which was distant in 220 (16%), local recurrence in 154 (11%), peritoneal carcinomatosis in 17 (1%) and port site recurrence in 5 (0.4%). Early oncologic failure developed in 71 patients (5%) at a total of 10 institutions. The incidence of early oncologic failure decreased from 10% in 2006 to 6% in 2015. On multivariate analysis the presence of any complication (OR 2.87, 95% CI 1.38-5.96, p = 0.004), pT3 or greater disease (OR 3.73, 95% CI 2.00-6.97, p <0.001) and nodal involvement (OR 2.14, 95% CI 1.21-3.80, p = 0.008) was a significant predictor of early oncologic failure. Patients with early oncologic failure demonstrated worse disease specific and overall survival (23% and 13%, respectively) at 1 and 3 years compared to patients who experienced later or no recurrences (log rank p <0.001). CONCLUSIONS: The incidence of early oncologic failure following robot-assisted radical cystectomy has decreased with time. Disease related rather than technical related factors have a major role in early oncologic failure after robot-assisted radical cystectomy.

Robot-assisted approach to 'W'-configuration urinary diversion: a step-by-step technique.

OBJECTIVE: To describe a detailed step-by-step approach of our technique for robot-assisted intracorporeal 'W'-configuration orthotopic ileal neobladder. PATIENTS AND METHODS: Five patients underwent robot-assisted radical cystectomy (RARC), extended pelvic lymph node dissection and intracorporeal neobladder (ICNB). ICNB was divided into six key steps to facilitate and enable a detailed analysis and auditing of the technique. No conversion to open surgery was required. Timing for each step was noted. All patients had at least 3 months of follow-up. RESULTS: The mean age was 57 years. The mean overall console and diversion times were 357 and 193 min, respectively. None of the patients had any evidence of residual disease after RARC. Four of the five patients had complications; three developed fevers due to urinary tract infections (one required readmission), and one developed myocardial infarction and required coronary angiography and stenting. Looking at the timing for the individual steps, bowel detubularisation and construction of the posterior plate were consistently the longest among the key steps (average 46 min, 13% of the overall operative time), followed by uretero-ileal anastomosis (37 min, 10%), neobladder-urethral anastomosis (23 min, 6%), and identification and fixation of the bowel (26 min, 7%). CONCLUSION: We described our step-by-step technique and initial perioperative outcomes of our first five ICNBs with 'W' configuration.

Development, validation and clinical application of Pelvic Lymphadenectomy Assessment and Completion Evaluation: intraoperative assessment of lymph node dissection after robot-assisted radical cystectomy for bladder cancer.

OBJECTIVES: To develop a scoring tool, Pelvic Lymphadenectomy Appropriateness and Completion Evaluation (PLACE), to assess the intraoperative completeness and appropriateness of pelvic lymph node dissection (PLND) following robot-assisted radical cystectomy (RARC). PATIENTS, SUBJECTS AND METHODS: A panel of 11 open and robotic surgeons developed the content and structure of PLACE. The PLND template was divided into three zones. In all, 21 de-identified videos of bilateral robot-assisted PLNDs were assessed by the 11 experts using PLACE to determine inter-rater reliability. Lymph node (LN) clearance was defined as the proportion of cleared LNs from all PLACE zones. We investigated the correlation between LN clearance and LN count. Then, we compared the LN count of 18 prospective PLNDs using PLACE with our retrospective series performed using the extended template (No PLACE). RESULTS: A significant reliability was achieved for all PLACE zones among the 11 raters for the 21 bilateral PLND videos. The median (interquartile range) for LN clearance was 468 (431-545). There was a significant positive correlation between LN clearance and LN count (R2 = 0.70, P < 0.01). The PLACE group yielded similar LN counts when compared to the No PLACE group. CONCLUSIONS: Pelvic Lymphadenectomy Appropriateness and Completion Evaluation is a structured intraoperative scoring system that can be used intraoperatively to measure and quantify PLND for quality control and to facilitate training during RARC.

Development of a patient and institutional-based model for estimation of operative times for robot-assisted radical cystectomy: results from the International Robotic Cystectomy Consortium.

OBJECTIVES: To design a methodology to predict operative times for robot-assisted radical cystectomy (RARC) based on variation in institutional, patient, and disease characteristics to help in operating room scheduling and quality control. PATIENTS AND METHODS: The model included preoperative variables and therefore can be used for prediction of surgical times: institutional volume, age, gender, body mass index, American Society of Anesthesiologists score, history of prior surgery and radiation, clinical stage, neoadjuvant chemotherapy, type, technique of diversion, and the extent of lymph node dissection. A conditional inference tree method was used to fit a binary decision tree predicting operative time. Permutation tests were performed to determine the variables having the strongest association with surgical time. The data were split at the value of this variable resulting in the largest difference in means for the surgical time across the split. This process was repeated recursively on the resultant data sets until the permutation tests showed no significant association with operative time. RESULTS: In all, 2 134 procedures were included. The variable most strongly associated with surgical time was type of diversion, with ileal conduits being 70 min shorter (P < 0.001). Amongst patients who received neobladders, the type of lymph node dissection was also strongly associated with surgical time. Amongst ileal conduit patients, institutional surgeon volume (>66 RARCs) was important, with those with a higher volume being 55 min shorter (P < 0.001). The regression tree output was in the form of box plots that show the median and ranges of surgical times according to the patient, disease, and institutional characteristics. CONCLUSION: We developed a method to estimate operative times for RARC based on patient, disease, and institutional metrics that can help operating room scheduling for RARC.

Belief propagation in genotype-phenotype networks.

Graphical models have proven to be a valuable tool for connecting genotypes and phenotypes. Structural learning of phenotype-genotype networks has received considerable attention in the post-genome era. In recent years, a dozen different methods have emerged for network inference, which leverage natural variation that arises in certain genetic populations. The structure of the network itself can be used to form hypotheses based on the inferred direct and indirect network relationships, but represents a premature endpoint to the graphical analyses. In this work, we extend this endpoint. We examine the unexplored problem of perturbing a given network structure, and quantifying the system-wide effects on the network in a node-wise manner. The perturbation is achieved through the setting of values of phenotype node(s), which may reflect an inhibition or activation, and propagating this information through the entire network. We leverage belief propagation methods in Conditional Gaussian Bayesian Networks (CG-BNs), in order to absorb and propagate phenotypic evidence through the network. We show that the modeling assumptions adopted for genotype-phenotype networks represent an important sub-class of CG-BNs, which possess properties that ensure exact inference in the propagation scheme. The system-wide effects of the perturbation are quantified in a node-wise manner through the comparison of perturbed and unperturbed marginal distributions using a symmetric Kullback-Leibler divergence. Applications to kidney and skin cancer expression quantitative trait loci (eQTL) data from different mus musculus populations are presented. System-wide effects in the network were predicted and visualized across a spectrum of evidence. Sub-pathways and regions of the network responded in concert, suggesting co-regulation and coordination throughout the network in response to phenotypic changes. We demonstrate how these predicted system-wide effects can be examined in connection with estimated class probabilities for covariates of interest, e.g. cancer status. Despite the uncertainty in the network structure, we demonstrate the system-wide predictions are stable across an ensemble of highly likely networks. A software package, geneNetBP, which implements our approach, was developed in the R programming language.