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• Webinar increased insight into neurosurgery and the path to become a neurosurgeon. • There is a substantial appetite for virtual content related to neurosurgery. • USMSs, IMSs, and undergraduates have different motivations for webinar attendance. • Webinar format may effectively provide international exposure to neurosurgery. During the COVID-19 pandemic, the American Association of Neurological Surgeons (AANS) Young Neurosurgeons Committee (YNC) and Neurosurgery Research & Education Foundation (NREF) launched the YNC-NREF Webinar Series to provide young and aspiring neurosurgeons with timely information, education, and inspiration in the absence of in-person programming. Five 90-minute Zoom webinars were evaluated, each including 1–2 keynote speakers, a panel discussion, and an audience question-and-answer section. Topics included overviews of neurosurgery, the match, subspecialties, and inspirational career stories. Optional pre- and post-webinar surveys with 11-point Likert-type scores were distributed to attendees. We compared groups using chi-squared and Kruskal-Willis tests, and perceptions pre- and post-webinar using Mann-Whitney tests. The webinars were live using Zoom, and the recordings were published on NREF's YouTube channel. The webinar series targeted young neurosurgeons. The first five episodes had a particular focus on medical students and undergraduates. A total of 673 unique participants attended the webinar series; 257 (38%) and 78 (11%) attendees completed the pre- and post-webinar survey, respectively. Respondents had high baseline interest in neurosurgery and were motivated to learn about the match and training in the US, understand neurosurgeons' day-to-day lives, and ask questions. There were significant differences in perceptions between USMSs, IMSs, and undergraduate students. The webinar improved attendees' knowledge about neurosurgical specialties, the match, and US neurosurgery training. The YNC and NREF effectively engaged a large, diverse audience through an online webinar series, building a foundation for future virtual programming by organized neurosurgery. ACGME competencies. 1. Medical Knowledge. 2. Professionalism. 3. Interpersonal Skills and Communication. [ABSTRACT FROM AUTHOR]

Radiation management literature focused on optimizing care for patients with intellectual disability is sparse. We add our experience to the literature with the goal to improve care to this vulnerable patient population. To this end, we report three cases of prostate cancer in patients with limited cognition who were treated with low dose rate (LDR) prostate brachytherapy to highlight an effective strategy to deliver optimal care to this group of patients. This is a case series of three adult male patients with limited cognition each of whom developed prostate cancer which was managed primarily with LDR brachytherapy. Patient #1: A 53-year-old male with favorable intermediate-risk prostate cancer (PSA 8.8 ng/ml, Grade Group 2), Patient #2: a 68-year-old male with unfavorable intermediate risk prostate cancer (PSA 12.6 ng/ml, Grade Group 3), and Patient #3: a 52-year-old male with high-risk prostate cancer (PSA 24 ng/ml, Grade Group 1), all of whom had intellectual disability, were evaluated for radiation therapy. A thorough discussion occurred with each patient and their legal guardian about prostate cancer therapy options including surgery versus radiation treatment with or without androgen deprivation therapy. Radiation therapy treatment strategies presented included low dose rate brachytherapy versus external beam radiation treatment including SBRT to a total dose of 3625 cGy in 5 fractions every other day or a moderately hypofractionated regimen to a total dose of 7000 cGy in 28 daily fractions Monday to Friday. In each case, a shared decision was made for each patient to undergo interstitial prostate seed implant. Of note, two out of the three patients lived more than an hour away from the radiation treatment center and relied on family support for transportation needs. Each patient initially underwent a prostate volume study with a transrectal ultrasound to 1) determine the dimensions of the prostate and 2) develop a plan for radiation dose coverage of the prostate with interstitial Cs-131 brachytherapy seeds. Each patient then underwent seed implantation under anesthesia followed by fluoroscopy and post-implant CT, to assess for appropriate seed placement as well as the post-implant dosimetry. Patient #1 received a total prescription dose of 110 Gy to the prostate D90 using 61 sources each with a strength of 1.6 U per seed for a total strength of 97.6 U and at 14 months follow up, his PSA had decreased to 1.7 ng/ml from 8.8 ng/ml. Patient #2 received a total prescription dose of 100 Gy to the prostate D90 using 59 sources each with a strength of 1.43 U per seed for a total strength of 84.37 U, and at 38 months follow up, his PSA had decreased to 0.018 ng/ml from 12.6 ng/ml. Patient #3 received 115 Gy to the prostate D90 using 90 sources each with a strength of 1.8 U per seed for a total of 162 U, and at 34 months follow up, his PSA had decreased to 0.8 ng/mL from 24 ng/ml. In all three cases, treatment was completed without complications and there was no CTCAE grade 3 or higher toxicity noted. In patients with limited cognition with select non-metastatic prostate cancer, low dose rate brachytherapy is an excellent treatment modality. It provides adequate tumor control with acceptable radiation induced toxicities. It reduces the transportation burden associated with multiple treatment sessions by requiring only two visits to a radiation treatment center. The use of sedation reduces the challenge associated with patient immobilization encountered with external beam radiation treatments. And, it is less invasive than surgery. These advantages for LDR brachytherapy are extremely useful for patients with limited cognition. Thus, LDR brachytherapy should be strongly considered for this patient population when applicable. [ABSTRACT FROM AUTHOR]

Effective treatment for locally-advanced vulvar cancer remains a challenge and often requires multi-modality care. Unresectable disease may be managed with a combination of chemotherapy, external beam radiation (EBRT), and brachytherapy. Cesium-131 Low Dose Rate (LDR) interstitial brachytherapy is an effective modality to deliver high-quality localized radiation. This case report highlights the technique and efficacy of Cesium-131 LDR interstitial brachytherapy as a part of multimodal therapy in treating a medically inoperable patient with advanced age and multiple medical comorbidities. Patient is a 79-year-old female who presented with medically inoperable FIGO Stage IVA squamous cell carcinoma of the vulva with extensive left labial disease and circumferential extension into the upper vagina. In addition, patient had hypermetabolic left inguinal lymph node metastasis on PET/CT imaging. Patient was subsequently treated with EBRT (4930 cGy over 29 fractions was delivered to the vulva, vagina, and regional lymphatics, followed by a sequential boost of 1620 cGy over 9 fractions to the involved left inguinal lymph node) with concurrent weekly cisplatin. Following EBRT, the patient had residual disease burden. She was noted to have cobblestoning of the anterior vaginal wall extending laterally on both sides, with palpably bulky disease in roughly the 10 o'clock position along her right lateral vaginal wall. She was offered High Dose Rate (HDR) interstitial brachytherapy boost, but declined this treatment due to her age and multiple medical comorbidities. She was subsequently treated with Cesium-131 LDR interstitial brachytherapy. Cesium-131 interstitial free seeds were placed with the seed inserters starting proximally and extending distally along the anterior vaginal wall in a planer fashion. 3000 cGy was prescribed to the tumor using 28 sources, each with a strength 0.72 U per seed. Dose distribution is represented in Figure 1 (Coronal CT scan demonstrating the radiation dose distribution of Cesium-131 permanent LDR implant to gross residual vaginal disease following EBRT). This was followed by vaginal cylinder HDR intracavitary brachytherapy utilizing Iridium-192 (800 cGy was prescribed at 5 mm depth from the vaginal cylinder surface delivered over 2 fractions). PET/CT done at 3 months showed complete metabolic resolution of all disease without evidence of recurrent or metastatic disease. At the patient's 21-month follow up, she had no evidence of disease on clinical exam or PET/CT imaging at that time. Acute toxicities included CTCAE grade 2-3 vulvar and inguinal skin erythema and mild diarrhea. Late toxicities include vaginal wall fibrosis at the site of Cesium-131 implant. Cesium-131 LDR interstitial brachytherapy implementation in a multimodal therapy setting is proved to be a feasible and promising treatment option to achieve long-term local control in a medically inoperable patient with an extensive vulvovaginal neoplasm. This study demonstrates a proof of concept of the safety and viability of Cesium-131 LDR interstitial brachytherapy for definitive management in selective patient populations. Future research is warranted. [ABSTRACT FROM AUTHOR]

• U.S. neurosurgery residents report moderate burnout during the COVID-19 pandemic. • Neurosurgery residents report uncertainty about future healthcare reform & earnings. • The COVID-19 pandemic may impair residents' achievement of surgical milestones. • Burnout is associated with altered rotation or vacation schedules and lower PGY. • Career satisfaction is associated with delivery of neurosurgical patient care. The coronavirus disease 2019 (COVID-19) pandemic has posed significant changes to resident education and workflow. However, the impact of the pandemic on U.S. neurosurgery residents has not been well characterized. We investigated the impact of the COVID-19 pandemic on U.S. neurosurgery resident workflow, burnout, and career satisfaction. In 2020, a survey evaluating factors related to career satisfaction and burnout was emailed to 1,374 American Association of Neurological Surgeons (AANS) residents. Bivariate and multivariate (logistic) analyses were performed to characterize predictors of burnout and career satisfaction. 167 survey responses were received, with a response rate (12.2%) comparable to that of similar studies. Exclusion of incomplete responses yielded 111 complete responses. Most respondents were male (65.8%) and White (75.7%). Residents reported fewer work hours (67.6%) and concern that COVID-19 would impair their achievement of surgical milestones (65.8%). Burnout was identified in 29 (26.1%) respondents and career satisfaction in 82 (73.9%) respondents. In multivariate analysis, burnout was significantly associated with alterations in elective rotation/vacation schedules (p =.013) and the decision to not pursue neurosurgery again if given the choice (p <.001). Higher post-graduate year was associated with less burnout (p =.011). Residents displayed greater career satisfaction when focusing their clinical work upon neurosurgical care (p =.065). Factors related to COVID-19 have contributed to workflow changes among U.S. neurosurgery residents. We report a moderate burnout rate and a paradoxically high career satisfaction rate among neurosurgery residents. Understanding modifiable stressors during the COVID-19 pandemic may help to formulate interventions to mitigate burnout and improve career satisfaction among residents. [ABSTRACT FROM AUTHOR]

Purpose: To classify subacromial bursal tissue using intraoperative and in vitro characteristics from specimens harvested during arthroscopic shoulder surgery.Methods: Subacromial bursa was harvested over the rotator cuff from 48 patients (57 ± 10 years) undergoing arthroscopic shoulder surgery. Specimens were characterized intraoperatively by location (over rotator cuff tendon or muscle), tissue quality (percent of either fatty or fibrous infiltration), and vascularity before complete debridement. Nucleated cell counts were determined after 3 weeks incubation and histological sections were reviewed for degree of fatty infiltration and vascularity. Mesenchymal stem cell surface markers were counted via flow cytometry (n = 3) and cellular migration was observed using a fluoroscopic assay (n = 3).Results: Intraoperatively, muscle bursa was found most often to have >50% fatty infiltration (n = 39), whereas tendon bursa showed majority fibrous tissue (n = 32). Cellular proliferation did not significantly differ according to intraoperative tissue quality. Intraoperative vascularity was associated with greater proliferation for highly vascular samples (P = 0.023). Tendon bursa demonstrated significantly greater proliferation potential than muscle bursa (P = 0.00015). Histologic assessment of fatty infiltration was moderately correlated with gross tissue fattiness (ρ = -0.626, P = 7.14 × 10-11). Flow cytometry showed that 90% to 100% of bursal cells were positive for MSC surface markers. Peak cellular migration rates occurred between 18 and 30 hours' incubation.Conclusions: Intraoperative and in vitro subacromial bursa characteristics were not found to reliably correlate with the degree of cellular proliferation. However, the anatomic location of subacromial bursa was consistently predictive of increased proliferation potential. Bursa-derived nucleated cells were confirmed to include mesenchymal stem cells with migratory potential.Clinical Relevance: The anatomic distinction between muscle and tendon bursa provides a simple classification for predicting cellular activity. [ABSTRACT FROM AUTHOR]

Purpose: To biomechanically compare the effect of superior capsule reconstruction (SCR) using a 3- and 6-mm thick acellular dermal allograft for the treatment of irreparable rotator cuff tears.Methods: Eight fresh-frozen cadaveric shoulders were tested using a dynamic shoulder model. Maximum abduction angle (MAA), glenohumeral superior translation (ghST), subacromial peak contact pressure (sPCP), and cumulative deltoid force (cDF) were compared among 4 conditions: (1) intact shoulder, (2) simulated irreparable rotator cuff tear (RCT), (3) SCR using a 3-mm-thick acellular dermal allograft, (4) SCR using a 6-mm-thick acellular dermal allograft.Results: Compared with the intact state, simulated irreparable RCTs significantly decreased MAA (P < .001), while significantly increasing ghST (P = .001), sPCP (P < .001), and cDF (P < .001). SCR with a 3-mm-thick graft significantly increased MAA (P = .01) and decreased ghST (P = .01) compared with the RCT state, however, showed similar sPCP and cDF. Compared with the torn state, SCR with a 6-mm-thick graft significantly increased MAA (P < .001) and significantly decreased ghST (P < .001), sPCP (P < .001), and cDF (P = .001). Using a 6-mm-thick graft demonstrated similar MAA, ghST, sPCP, and cDF compared with the intact state. When comparing the 3-mm to the 6-mm thick graft, significant differences were found in ghST (P = .03), sPCP (P < .001), and cDF (P = .02).Conclusions: SCR with a 6-mm-thick acellular dermal allograft better restored normal glenohumeral joint position and forces compared with a 3-mm-thick graft for the treatment of irreparable RCTs.Clinical Relevance: Graft thickness may affect the clinical success following SCR with commercially available dermal allografts. Using a thicker (>3 mm) graft was able to biomechanically better restore native glenohumeral joint properties. [ABSTRACT FROM AUTHOR]

Purpose: To analyze the posterior translational and rotational stability of the acromioclavicular (AC) joint following reconstruction of the superior acromioclavicular ligament complex (ACLC) using dermal allograft.Methods: Six fresh-frozen cadaveric shoulders were used (mean age of 65.3 ± 6.9 years). The resistance force against posterior translation (10 mm) and torque against posterior rotation (20°) was measured. Specimens were first tested with both the intact ACLC and coracoclavicular ligaments. The ACLC and coracoclavicular ligaments were then transected so simulate a Type III/V AC joint dislocation. Each specimen then underwent 3 testing conditions, performed in the following order: (1) ACLC patch reconstruction alone, (2) ACLC patch with an anatomic coracoclavicular reconstruction (ACCR) using semitendinosus allograft, and (3) the transected ACLC with an ACCR only. Differences in posterior translational and rotational torque across testing conditions were analyzed with a one-way repeated analysis of variance analysis.Results: Mean resistance against posterior translation in the intact condition was 65.76 ± 23.8 N. No significant difference found between the intact condition compared with specimens with the ACLC-patch only (44.2 ± 11.3 N, P = .06). The ACCR technique, when tested alone, had significantly less posterior translational resistance compared with the intact condition (38.5 ± 8.94 N, P = .008). ACLC patch in combination with an ACCR was closest in restoring native posterior translation (57.1 ± 19.2 N, P = .75). For rotational resistance, only the addition of the ACLC patch with an ACCR (0.51 ± 0.07 N-m) demonstrated similar torque compared with the intact joint (0.89 ± 0.5 N-m, P = .06).Conclusions: The ACLC-patch plus ACCR technique was able to closest restore the percent of normal posterior translational and rotational stability.Clinical Relevance: Recurrent posterior instability of the AC joint is a potential complication after coracoclavicular reconstruction surgery. In the in vitro setting, this study demonstrated increased AC joint stability with the addition of an ACLC reconstruction using dermal allograft. [ABSTRACT FROM AUTHOR]

Purpose: To identify an effective, nonenzymatic method for maximizing the yield of subacromial bursa-derived nucleated cells for augmenting rotator cuff repair.Methods: Subacromial bursa (minimum 0.2 g) was collected prospectively over the supraspinatus from patients (n = 7) with at least one full-thickness tendon tear undergoing arthroscopic primary rotator cuff repair. Samples were processed and analyzed prospectively using 4 different methods: (1) mechanical digestion with scissors (chopping), (2) collagenase digestion, (3) mechanical digestion with a tissue homogenizer, and (4) whole tissue with minimal manipulation. Tissue from each method were plated and cultured in a low oxygen tension, humidified incubator for 7 days. Following incubation, cellularity was assessed with nucleated cell count using a Coulter Counter. Flow cytometry was performed on the non-enzymatic method that demonstrated the greatest cell count to confirm the presence of mesenchymal stem cells (MSCs). The Kruskal-Wallis H test and post hoc Dunn's test were used for statistical analysis.Results: Following incubation, mean nucleated cell counts (cells/mL) were (1) 102,681 ± 73,249 for chopping, (2) 76,190 ± 66,275 for collagenase, (3) 31,686 ± 29,234 for homogenization, and (4) 11,162 ± 4016 for whole tissue. There was no significant difference between chopping and collagenase (P = .45) or between homogenization and collagenase (P = .52). Both chopping (P = .003) and collagenase (P = .03) produced significantly more cells when compared with whole tissue. Flow cytometry confirmed the presence of MSC markers on samples processed by chopping.Conclusions: Mechanical isolation of subacromial bursa-derived cells using a chopping technique demonstrated similar nucleated cell count compared with collagenase, along with the confirmed presence of MSCs.Clinical Relevance: This study demonstrated a nonenzymatic, mechanical method for isolating subacromial bursa-derived cells to potentially augment rotator cuff repair. Further clinical studies are required to assess its possible advent in the tendon-bone healing process. [ABSTRACT FROM AUTHOR]

Purpose: To compare the potency of mesenchymal stem cells between the cells derived from the subacromial bursa to concentrated bone marrow aspirate (cBMA) taken from patients undergoing rotator cuff (RC) repair.Methods: Subacromial bursa and cBMA were harvested arthroscopically from 13 patients (age 57.4 ± 5.2 years, mean ± standard deviation) undergoing arthroscopic primary RC repair. Bone marrow was aspirated from the proximal humerus and concentrated using an automated system (Angel System; Arthrex). Subacromial bursa was collected from 2 sites (over the RC tendon and muscle) and digested with collagenase to isolate a single cellular fraction. Proliferation, number of colony-forming units, differentiation potential, and gene expression were compared among the cells derived from each specimen.Results: The cells derived from subacromial bursa showed significantly higher proliferation compared with the cells derived from cBMA after 5, 7, and 10 days (P = .018). Regarding colony-forming units, the subacromial bursa had significantly more colonies than cBMA (P = .002). Subacromial bursal cells over the RC tendon produced significantly more colonies than cells over both the RC muscle and cBMA (P = .033 and P = .028, respectively). Moreover, when compared with cBMA, cells derived from subacromial bursa showed significantly higher differentiation ability and higher gene expression indicative of chondrogenesis, osteogenesis, and adipogenesis.Conclusion: The subacromial bursa is an easily accessible tissue that can be obtained during RC repair, with significant pluripotent stem cell potency for tendon healing. Compared with cBMA taken from the proximal humerus, bursal cells showed significantly increased differentiation ability and gene expression over time.Clinical Relevance: Failed RC repairs have been partly attributed to a poor healing environment. Biologic augmentation of the repair site may help increase healing potential and incorporation of the cuff at the tendon-bone interface. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of critical shoulder angle (CSA), acromion index (AI), and glenoid inclination (GI) on the postoperative healing rate after arthroscopic supraspinatus tendon repair.Methods: Patients after arthroscopic repair of a symptomatic, unilateral, single-tendon, full-thickness supraspinatus tear in whom nonoperative management had failed were retrospectively reviewed. Magnetic resonance imaging (MRI) studies were obtained 6 months postoperatively and were evaluated by 2 independent observers. Repair integrity was classified as either intact or torn. Preoperative true anteroposterior radiographs were used to measure CSA, AI, and GI.Results: Fifty-seven patients were evaluated 6 months postoperatively. The mean patient age at surgery was 54.7 ± 7.7 years. On MRI studies, 41 patients (71.9%) had an intact repair and 16 patients (28.1%) had a full-thickness retear. There were no significant differences between the intact and retear group in regard to patient age (P = .648), initial tear size (P = .205), or fatty degeneration (P = .508). The mean CSA for the retear group (37° ± 4°) was significantly higher than that in the intact group (35° ± 3°; P = .014). If the CSA was >38°, the odds ratio of having a retear was 3.78 (95% confidence interval 1.05 to 13.58; P = .042). Average AI for the retear group (0.73 ± 0.09) was significantly higher than that in the intact group (0.69 ± 0.06; P = .049). The mean GI was 17° ± 6° for the intact group and 16° ± 6° for the retear group (P = .739).Conclusions: At short-term follow-up, higher CSA and AI significantly increased the retear risk after arthroscopic supraspinatus tendon repair. CSA >38° increased the retear risk almost 4-fold. Overall GI was elevated but did not correlate with failure rate.Level Of Evidence: III, case control study. [ABSTRACT FROM AUTHOR]

Introduction: Vasospasm accounts for a large fraction of the morbidity and mortality burden in patients sustaining subarachnoid hemorrhage (SAH). Platelet-derived growth factor (PDGF)-β levels rise following SAH and correlate with incidence and severity of vasospasm.Methods: The literature was reviewed for studies investigating the role of PDGF in the pathogenesis of SAH-related vasospasm and efficacy of pharmacological interventions targeting the PDGF pathway in ameliorating the same and improving clinical outcomes.Results: Release of blood under high pressure into the subarachnoid space activates the complement cascade, which results in release of PDGF. Abluminal contact of blood with cerebral vessels increases their contractile response to PDGF-β and thrombin, with the latter upregulating PDGF-β receptors and augmenting effects of PDGF-β. PDGF-β figures prominently in the early and late phases of post-SAH vasospasm. PDGF-β binding to the PDGF receptor-β results in receptor tyrosine kinase domain activation and consequent stimulation of intracellular signaling pathways, including p38 mitogen-activated protein kinase, phosphatidylinositol-3-kinase, Rho-associated protein kinase, and extracellular regulated kinase 1 and 2. Consequent increases in intracellular calcium and increased expression of genes mediating cellular growth and proliferation mediate PDGF-induced augmentation of vascular smooth muscle cell contractility, hypertrophy, and proliferation.Conclusion: Treatments with statins, serine protease inhibitors, and small molecular pathway inhibitors have demonstrated varying degrees of efficacy in prevention of cerebral vasospasm, which is improved with earlier institution. [ABSTRACT FROM AUTHOR]

Protected areas not allowing extractive activities (here called fully protected area) are a spatially explicit conservation management tool commonly used to ensure populations persistence. This is achieved when an adequate fraction of a species' population spends most of its time within the boundaries of the protected area. Within a marine context, home ranges represent a tractable metric to provide guidance and evaluation of fully protected areas. We compiled peer-reviewed literature specific to the home ranges of finfishes and invertebrates of ecological and/or commercial importance in the Mediterranean Sea, and related this to the size of 184 Mediterranean fully protected areas. We also investigated the influence of fully protected areas size on fish density in contrast to fished areas with respect to home ranges. Home range estimations were available for 11 species (10 fishes and 1 lobster). The European spiny lobster Palinurus elephas had the smallest home range (0.0039 ± 0.0014 km 2 ; mean ± 1 SE), while the painted comber Serranus scriba (1.1075 ± 0.2040 km 2 ) had the largest. Approximately 25% of Mediterranean fully protected areas are larger than 2 times the size of the largest home range recorded. Fish densities were significantly higher when fully protected areas were larger than the home range, while no change in density occurred when home ranges were larger than fully protected areas. These results display a direct link between the effectiveness of fully protected areas and species' home range, suggesting that fully protected areas of at least 3.6 km 2 may increase the density of local populations of these coastal marine species. [ABSTRACT FROM AUTHOR]

Case studies are presented of 22, 44 and 6-year-old woman presented with shoulder acromioclavicular and coracoclavicular ligament injuries, and includes use of anatomic coracoclavicular reconstruction and semitendinosus allograft for treating the same.

One method to reduce wind variability is to diversify the wind power resource by interconnecting wind resources across a larger geography. This study uses a modified version of mean-variance portfolio optimization (MVP) to assess the potential for diverse wind to reduce the variability of wind. A one year unit commitment and economic dispatch model of the U.S. Midwest is used to understand the value of the reduced variability. The model assesses four different wind portfolios, ranging in diversity, of two wind power penetrations (10% of total system load and 20%). Employing MVP, the variance in the ramp rates decrease by 50% with a 4% increase in capacity in the 20% wind penetration and a 2% increase in the 10% penetration. With a 20% wind penetration, decreasing the ramp rate variance can reduce curtailment from 5% to 0.1%. In the absence of significant curtailment, decreasing the ramp rate variance reduces the proportion of conventional generation required for ramping. However, the impact on total production cost and emissions from conventional generation is complicated by complexities of the power system, including transmission constraints and the time of day of ramping. [ABSTRACT FROM AUTHOR]

Background: Periprosthetic joint infection is the most common cause of readmissions after total joint arthroplasty (TJA). Intrawound vancomycin powder (VP) has reduced infection rates in spine surgery; however, there are no data regarding VP in primary TJA.Methods: Thirty-four TJA patients received 2 g of VP intraoperatively to investigate VP's pharmacokinetics. Serum and wound concentrations were measured at multiple intervals over 24 hours after closure.Results: All serum concentrations were subtherapeutic (<15μg/mL) and peaked 12 hours after closure (4.7μg/mL; standard deviation [SD], 3.2). Wound concentrations were 922 μg/mL (SD, 523) 3 hours after closure and 207 μg/mL (SD, 317) at 24 hours. VP had a half-life of 7.2 hours (95% confidence interval, 7.0-9.3) in TJA wounds.Conclusions: VP produced highly therapeutic intrawound concentrations while yielding low systemic levels in TJA. VP may serve as a safe adjunct in the prevention of periprosthetic joint infection. [ABSTRACT FROM AUTHOR]

Due to decreasing solar module prices, some solar developers are increasing their projects’ inverter loading ratio (ILR), defined as the ratio of DC module capacity to AC inverter capacity. In this study, we examine the operational impacts of this trend. Using minute-level solar data, we examine the relationship between inverter induced clipping losses and AC generation. We find minimal clipping losses at an ILR of 1.25; at an ILR of 2.0, we observe that 16% of potential annual generation is lost. Minute-level data prove to be essential in determining the generation lost to clipping, as hourly data mask key clipping and ramping events. Higher ILRs lead to a greater frequency of time spent at maximum generation, but also a greater frequency and magnitude of large solar ramping events. Module degradation can attenuate the impacts of inverter clipping over time. We observe that the effective degradation rate (net of any changes to inverter clipping losses) can be as little as half the actual degradation rate for projects with high ILRs. The diurnal and seasonal trends in clipping correspond with solar insolation patterns, with the highest clipping occurring around noon. For fixed tilt installations with tilt angles at latitude, we observe the highest clipping near the autumnal and vernal equinoxes. Increasing the tilt angle leads to more winter clipping, while lower tilt angles shifts the clipping to summer months. Shifting from fixed tilt to north–south single axis tracking increases the generation lost to clipping significantly. At an ILR of 1.25, annual clipping approximately doubles to 1% compared to fixed tilt at latitude, while clipping under an ILR of 2.0 increases to 22%, compared to 16% for the fixed configuration. As expected, more clipping occurs during the hours preceding and following noon when using single axis tracking. [ABSTRACT FROM AUTHOR]

We use the CAMx (Comprehensive Air Quality Model with Extensions) chemical transport model (CTM) with 4-km horizontal resolution over the Korean Peninsula to investigate source contributions to PM 2.5 in Korea from domestic and upwind sources. We modeled 2015 and 2016 to account for meteorological variation with Korean emissions from the Clean Air Policy Supporting System (CAPSS), meteorology from WRF (Weather, Research, and Forecasting) model, and regional boundary concentrations from the GEOS-Chem global CTM. The CAMx particulate source apportionment technology (PSAT) provided PM 2.5 source contributions from 5 source sectors and 6 geographic regions within Korea, international sources, and boundary concentrations. PM 2.5 contributions from outside Korea are important with boundary concentrations plus the "other" emissions sector (includes marine shipping, agricultural ammonia, and international emissions from North Korea and Japan within the CAMx domain) contributing 67% of annual average PM 2.5 in Seoul in 2016 and 71% in 2015. The boundary concentrations contributed between 30% and 50% of PM 2.5 at different Korean cities with contributions generally lower in 2016 than in 2015. For Korean sources, PM 2.5 contributions from Electric Generating Unit (EGU) emissions were smaller than contributions from mobile and industrial emissions sources although there is considerable day-to-day variation in contributions. On an annual basis in 2016, the "other" category contributed 25% followed by mobile sources at 23%, industrial sources at 6%, and EGU sources at 3%. For 2015, the contributions were similar. Focusing on March when PM 2.5 concentrations were higher than other months, the contributions from other, mobile, industrial, and EGUs were 21%, 18%, 4%, and 4%, respectively in 2016. For 2015, contributions from these four categories were 18%, 15%, 3%, and 3%, respectively. • A regional air quality model estimated domestic contributions from different sources and regions to PM2.5 in Korea. • Boundary conditions (includes contributions from China) contributed 30% to 50% towards PM2.5 in major cities in Korea. • Among the domestic sources, mobile sources contributed the most towards PM2.5 in Korea followed by the industrial sources. • Our results are qualitatively similar to previous source attribution studies of PM2.5 in Korea. [ABSTRACT FROM AUTHOR]

Energy storage devices, such as batteries and flywheels, are promising options for providing operating reserves due to their fast response and low emissions during operation. However, because of the complex nature of power systems, adding energy storage-based reserves to the power system may not necessarily benefit the environment. In this paper, we analyze these impacts in a test system and identify important drivers that affect the environmental outcomes. Dispatch results are obtained by solving an optimal power flow (OPF) problem and are used to determine emissions. We find that the impacts of adding energy storage are highly case-dependent. In systems with high renewable penetration levels and significant renewable curtailment, adding energy storage reduces emissions; in other systems, the impacts on emissions could be positive, neutral, or negative. The analyses presented in this paper show that policies to procure energy storage as a means to reduce emissions may actually lead to increased system-wide emissions if current dispatch algorithms are used. We also explore the impacts of modifying the dispatch algorithm to ensure system emissions with energy storage are no worse than system emissions without energy storage. [ABSTRACT FROM AUTHOR]

An examination of the environmental benefits of an expanded RPS in Michigan find that, with higher coal retirements, significantly more natural gas is displaced by the expanded RPS, thereby reducing the emissions mitigation potential. This illustrates how the environmental benefits of renewable energy are dependent on the system into which it is integrated. [ABSTRACT FROM AUTHOR]

Energy storage may serve as a solution to the integration challenges of high penetrations of wind, helping to reduce curtailment, provide system balancing services, and reduce emissions. This study determines the minimum cost configuration of vanadium redox flow batteries (VRFB), wind turbines, and natural gas reciprocating engines in an off-grid model. A life cycle assessment (LCA) model is developed to determine the system configuration needed to achieve a variety of CO 2 -eq emissions targets. The relationship between total system costs and life cycle emissions are used to optimize the generation mixes to achieve emissions targets at the least cost and determine when VRFBs are preferable over wind curtailment. Different greenhouse gas (GHG) emissions targets are defined for the off-grid system and the minimum cost resource configuration is determined to meet those targets. This approach determines when the use of VRFBs is more cost effective than wind curtailment in reaching GHG emissions targets. The research demonstrates that while incorporating energy storage consistently reduces life cycle carbon emissions, it is not cost effective to reduce curtailment except under very low emission targets (190 g of CO2-eq/kW h and less for the examined system). This suggests that “overbuilding” wind is a more viable option to reduce life cycle emissions for all but the most ambitious carbon mitigation targets. The findings show that adding VRFB as energy storage could be economically preferable only when wind curtailment exceeds 66% for the examined system. The results were most sensitive to VRFB costs, natural gas upstream emissions (e.g. methane leakage), and wind capital cost. [ABSTRACT FROM AUTHOR]

Objective: The incidence of acute ischemic stroke is highest in the elderly. Information regarding outcomes of elderly patients undergoing different modalities of intra-arterial therapy (IAT) for acute ischemic stroke (AIS) is scarce and conflicting. This study compares the safety, technical efficacy and outcomes of elderly patients (≥ years) to non-elderly patients (<80 years) who underwent multimodality IAT. Methods: From a registry of consecutive patients treated with IAT for AIS at our institution over a 3.5-year period, patients with anterior circulation occlusions aged ≥80 years were compared to the patients <80 years. Results: Between 2008 and 2012, 24 patients ≥80 years (elderly) and 95 patients <80 years (non-elderly) received IAT for anterior circulation occlusions. In the elderly, there were more females (66.7% vs. 28.4%, p = <0.001) and atrial fibrillation (58.3% vs. 25.2%, p = 0.003). Between the 2 groups, there was no difference in NIHSS score (17.2 vs.16.3, p = 0.17), THRIVE score (4.21 vs. 4.39, p = 0.633), recanalization rate (70.1% vs. 85.3%, p = 0.13), or severe reperfusion hemorrhages (8.3% vs. 4.2%, p = 0.425). There was no significant difference in 3-month mortality (33.3% vs. 16.8%, p = 0.28); however, fewer elderly patients reached good 3-month outcome (0% vs. 40.0%, p = <0.001). After controlling for baseline factors, only female gender (OR 5.3, 95% CI 1.7-16.7; p = 0.04) and higher 3-month mRS (OR 1.6; 95% CI 1.1-2.40; p = 0.008) were independently associated with elderly age. Conclusion: Despite similar safety profiles and recanalization rates, elderly patients had poor functional outcomes after IAT. Intra-arterial therapy in the elderly should be pursued very cautiously only after careful analysis of the risks and benefits for each patient. [ABSTRACT FROM AUTHOR]

Highlights: [•] We assess the potential for energy storage to economically decrease wind curtailment or decrease system costs. [•] We assume that the wind is under contract via a power purchase agreement. [•] Maximum viable energy storage costs were $780/kW with ten hours of storage capacity. [•] Sizing the energy storage to reduce a small portion of curtailment supports higher unit cost batteries. [•] Significant curtailment persists even with high capacity energy storage. [Copyright &y& Elsevier]

Objective: Preoperative embolization of juvenile nasopharyngeal angiofibromas (JNA) has been shown to reduce operative times and blood loss. Although traditional transarterial (TA) embolization is commonly used, direct tumoral puncture (DTP) has also been advocated as an alternative. We report our series of JNAs embolized with Onyx and compare the two embolization techniques. Methods: We retrospectively reviewed all JNAs embolized with Onyx at our institution during a 20-month period. The fluoroscopy time, percent of tumor devascularization, periprocedural complications, and intraoperative blood loss were compared between the two groups. Results: A total of 10 patients with JNA underwent preoperative embolization by a TA route (n = 5) or DTP (n = 5). Mean fluoroscopy time was 50 and 39 minutes in the TA and DTP groups, respectively. The mean percent tumor devascularization in the TA group was 77% compared with 93% in the DTP group. Intraoperative estimated blood loss in tumors embolized transarterially was higher than those embolized by DTP (862 mL vs. 412 mL); however, this difference did not reach statistical significance. There were no neurological complications related to the embolization procedures in either group. Conclusions: Embolization of JNAs with Onyx can be performed safely by either method. Direct puncture is associated with shorter embolization procedure times and results in a greater degree of tumor devascularization. Although there was a trend toward lesser blood loss in patients embolized by DTP, it did not reach statistical significance in this small series. Larger series are needed to determine whether the improved tumor penetration achieved with DTP translates into clinical benefit. [ABSTRACT FROM AUTHOR]

Residue-specific incorporation of non-canonical amino acids into proteins allows facile alteration and enhancement of protein properties. In this review, we describe recent technical developments and applications of residue-specific incorporation to problems ranging from elucidation of biochemical mechanisms to engineering of protein-based biomaterials. We hope to inform the reader of the ease and broad utility of residue-specific non-canonical amino acid incorporation with the goal of inspiring investigators outside the field to consider applying this tool to their own research. [ABSTRACT FROM AUTHOR]

Abstract: Hydrogels are important materials for a variety of applications, particularly biomedical devices, but they generally have poor mechanical properties since they consist predominantly of water held in place by a relatively fragile polymer network. This brief review describes a few novel methods to control or improve the mechanical properties of hydrogels including slide-ring gels, double-network gels, nanocomposite gels, and photoactive gels. Our goal is to encourage more researchers to be aware of and to exploit these methods. [Copyright &y& Elsevier]

[Display omitted] Imidazoquinoline derivatives (IMDs) and related compounds function as synthetic agonists of Toll-like receptors 7 and 8 (TLR7/8) and one is FDA approved for topical antiviral and skin cancer treatments. Nevertheless, these innate immune system-activating drugs have potentially much broader therapeutic utility; they have been pursued as antitumor immunomodulatory agents and more recently as candidate vaccine adjuvants for cancer and infectious disease. The broad expression profiles of TLR7/8, poor pharmacokinetic properties of IMDs, and toxicities associated with systemic administration, however, are formidable barriers to successful clinical translation. Herein, we review IMD formulations that have advanced to the clinic and discuss issues related to biodistribution and toxicity that have hampered the further development of these compounds. Recent strategies aimed at enhancing safety and efficacy, particularly through the use of bioconjugates and nanoparticle formulations that alter pharmacokinetics, biodistribution, and cellular targeting, are described. Finally, key aspects of the biology of TLR7 signaling, such as TLR7 tolerance, that may need to be considered in the development of new IMD therapeutics are discussed. [ABSTRACT FROM AUTHOR]

Ventriculoperitoneal (VP) shunt malfunctions are common and can result in significant consequences for patients. Despite the prevalence of breast augmentation surgery and breast surgery for other pathologies, few breast related VP shunt complications have been reported. A 54-year-old woman with hydrocephalus post-subarachnoid hemorrhage returned 1 month after VP shunt placement complaining of painful unilateral breast enlargement. After investigation, it was determined that the distal VP shunt catheter had migrated from the peritoneal cavity into the breast and wrapped around her breast implant. The breast enlargement was the result of cerebrospinal fluid retention. We detail this unusual case and review all breast related VP shunt complications reported in the literature. To avoid breast related complications related to VP shunt procedures, it is important to illicit pre-procedural history regarding breast implants, evade indwelling implants during catheter tunneling and carefully securing the abdominal catheter to prevent retrograde catheter migration to the breast. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the accuracy of NOx emissions in the Texas Commission on Environmental Quality's (TCEQ) State Implementation Plan (SIP) modeling inventories of the southeastern U.S. We used retrieved satellite tropospheric NO 2 columns from the Ozone Monitoring Instrument (OMI) together with NO 2 columns from the Comprehensive Air Quality Model with Extensions (CAMx) to make top–down NOx emissions estimates using the mass balance method. Two different top–down NOx emissions estimates were developed using the KNMI DOMINO v2.0 and NASA SP2 retrievals of OMI NO 2 columns. Differences in the top–down NOx emissions estimates made with these two operational products derived from the same OMI radiance data were sufficiently large that they could not be used to constrain the TCEQ NOx emissions in the southeast. The fact that the two available operational NO 2 column retrievals give such different top–down NOx emissions results is important because these retrievals are increasingly being used to diagnose air quality problems and to inform efforts to solve them. These results reflect the fact that NO 2 column retrievals are a blend of measurements and modeled data and should be used with caution in analyses that will inform policy development. This study illustrates both benefits and challenges of using satellite NO 2 data for air quality management applications. Comparison with OMI NO 2 columns pointed the way toward improvements in the CAMx simulation of the upper troposphere, but further refinement of both regional air quality models and the NO 2 column retrievals is needed before the mass balance and other emission inversion methods can be used to successfully constrain NOx emission inventories used in U.S. regulatory modeling. [ABSTRACT FROM AUTHOR]

Neurosurgery has a high barrier of educational access for medical students. The Medical Student Neurosurgery Training Center (MSNTC) is a novel online learning platform that provides on-site and virtual training opportunities and resources that aim to increase student access to neurosurgical education. The objective of this article was to describe student-reported utility of Medical Student Neurosurgery Training Center educational resources. A Qualtrics survey was sent to attendees after the 2020 Virtual Neurosurgery Training Camp. Ratings were quantified on modified 5-point Likert scales and compared using Wilcoxon rank sum tests, with a P value of 0.05. Response was obtained from 119 (25.2%) of 473 Virtual Neurosurgery Training Camp registrants. Of respondents, 65 (54.6%) reported prior use of Brain & Spine Report (BSR), 68 (57.14%) reported use of the Video Library (VL), and 78 (65.5%) reported use of the Global Events Calendar (GEC). Among respondents who previously used the BSR, VL, or GEC, mean ratings of usefulness were 3.94 ± 1.01, 4.06 ± 0.91, and 4.10 ± 0.99, respectively. Medical students with a neurosurgery interest group at their home institution reported greater utility of the BSR (P = 0.0008), VL (P = 0.0018), and GEC (P = 0.0250). Medical students with a home program reported greater utility of the BSR (P = 0.0079), and international students reported greater utility of the VL (P = 0.0447). Medical Student Neurosurgery Training Center resources appear to have promising preliminary benefits for students. Increasing medical student awareness, continued development of these resources, and objectively assessing outcomes in neurosurgery education are warranted. [ABSTRACT FROM AUTHOR]

Objective: The degree of coronary artery calcification has been shown to predict outcomes in coronary artery disease. The impact of intracranial carotid artery calcification on the prognosis of acute ischemic stroke (AIS) is unknown. The authors sought to examine if the degree of intracranial carotid artery calcification influences reperfusion or outcomes in AIS intervention. Methods: All anterior circulation large vessel occlusion AIS cases that underwent intra-arterial therapy from January 2009 to July 2012 were reviewed. Clinical and radiographic data were collected. Noncontrast brain CT scans were assigned a Calcium Extent Score (degree of calcification of the carotid wall circumference), Calcium Thickness Score (thickness of the calcified plaque), and total Carotid Siphon Calcium (CSC) Score (8-point scale). Results: One-hundred seventeen patients met inclusion criteria. The mean age was 65.4±15.6 years and 36% were male. Calcification was present in the intracranial carotid artery of 84 patients (71%). Inter-rater agreement for total CSC score was strong (Spearman's rho = 0.883, p < 0.001). The mean Calcium Extent Score was 1.5±1.3, Calcium Thickness Score 1.3±1.0 and total CSC Score 2.8±2.2. Reperfusion and mRS were not associated with CSC. Multivariate linear regression analysis revealed that older age, history of coronary disease and cervical internal carotid occlusion/near-occlusion were independently associated with higher total CSC scores. Conclusion: Extensive calcification on the intracranial carotid artery does not have impact on reperfusion or clinical outcomes in AIS patients undergoing endovascular therapy. Higher CSC scores are associated with coronary artery disease, increasing age and cervical internal carotid artery occlusion/near-occlusion. [ABSTRACT FROM AUTHOR]

Ensuring power system reliability under high penetrations of variable renewable energy is a critical task for system operators. In this study, we use a loss of load probability model to estimate the capacity credit of solar photovoltaics and energy storage under increasing penetrations of both technologies, in isolation and in tandem, to offer new understanding on their potential synergistic effects. Increasing penetrations of solar PV alter the net load profile on the grid, shifting the peak net load to hours with little or no solar generation and leading to diminishing capacity credits for each additional increment of solar. However, the presence of solar PV decreases the duration of daily peak demands, thereby allowing energy-limited storage capacity to dispatch electricity during peak demand hours. Thus, solar PV and storage exhibit a symbiotic relationship when used in tandem. We find that solar PV and storage used together make a more significant contribution to system reliability: as much as 40% more of the combined capacity can be counted on during peak demand hours compared to scenarios where the two technologies are deployed separately. Our test case demonstrates the important distinction between winter and summer peaking systems, leading to significantly different seasonal capacity values for solar PV. These findings are timely as utilities replace their aging peaking plants and are taking energy storage into consideration as part of a low carbon pathway. [ABSTRACT FROM AUTHOR]