59 results on '"Ajmera S"'
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2. Silicon Germanium Oxide (SixGeyO1-x-y) Infrared Sensitive Material for Uncooled Detectors
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Anvari, R., Cheng, Q., Hai, M. L., Bui, T., Syllaios, A. J., Ajmera, S., and Almasri, M.
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- 2009
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3. Raman Characterization of Protocrystalline Silicon Films
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Syllaios, A. J., Ajmera, S. K., Tyber, G. S., Littler, C., and Hollingsworth, R. E.
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- 2008
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4. Influence of microstructure and composition on hydrogenated silicon thin film properties for uncooled microbolometer applications.
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Saint John, D. B., Shin, H.-B., Lee, M.-Y., Ajmera, S. K., Syllaios, A. J., Dickey, E. C., Jackson, T. N., and Podraza, N. J.
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MICROSTRUCTURE ,THIN films ,SILICON ,CHEMICAL vapor deposition ,VAPOR-plating - Abstract
Doped n- and p-type hydrogenated silicon (Si:H) thin films prepared by plasma enhanced chemical vapor deposition have been investigated for uncooled microbolometer applications. The material microstructure has been studied by in situ real time spectroscopic ellipsometry collected during thin film deposition or ex situ spectroscopic ellipsometry measurements on a static sample with a multiple sample analysis technique. The key electrical properties of interest, including film resistivity (ρ), temperature coefficient of resistance (TCR), and 1/f noise, have been measured as a function of deposition conditions for p-type amorphous hydrogenated silicon (a-Si:H) films and microcrystalline content for n-type amorphous (a), microcrystalline (µc), and mixed-phase amorphous + microcrystalline (a + µc) Si:H films. The TCR and 1/f noise values were compared for p- and n-type a-Si:H samples in the resistivity range of 100 < ρ < 3000 Ω cm and show that for a given resistivity, amorphous p-type films exhibit a lower 1/f noise, which might be expected due to a larger density of majority carriers. [ABSTRACT FROM AUTHOR]
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- 2011
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5. Experimental and Numerical Investigation of Convective Heat Transfer in a Multiple-ventilated Enclosure with Discrete Heat Sources.
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Ajmera, S. K., Shukla, H. J., and Mathur, A. N.
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HEAT convection , *HEAT transfer , *TURBULENT flow , *NUMERICAL analysis , *DISCRETE systems - Abstract
The experimental and numerical investigation of convective heat transfer in a rectangular cavity of aspect ratio (L/H) = 5 has been presented in this study. The comparison of experimental results is done with a two-dimensional numerical model considered with steady and turbulent flow conditions. Six different arrangements (bottom/bottom/bottom, top/top/top, right/top/left, bottom/top/right, bottom/top/left, and bottom/right/left) were considered. The lowest and highest hotspot temperatures were observed in bottom/bottom/bottom and bottom/right/left arrangements, respectively. For similar configurations, the bottom/bottom/bottom arrangement displays better heat transfer performance, while heat transfer performance is inferior for the bottom/right/left arrangement than all other configurations. [ABSTRACT FROM PUBLISHER]
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- 2016
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6. Studies on Decomposition of Banana Leaf and Mixture of Cattle Dung and Urine by Thermophilic Coprophilous Fungi
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Ajmera Shanthipriya, Sana Shanawaz , Sivadevuni Girisham
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Environmental effects of industries and plants ,TD194-195 ,Science (General) ,Q1-390 - Abstract
In this study, the microbial population responsible for decomposition of banana leaf with dung and urine of cattle (cow and sheep used here) was isolated, identified, and their incidence calculated. During this study, significant changes were observed in different physio-chemical properties (temperature, pH, moisture content, humidity, ash content, total organic carbon, total nitrogen content, phosphorus) of decomposing material which focuses particularly on the role of thermophilic coprophilous fungi in reducing the time for decomposition. It also gives a clear demonstration of various effects of different environmental conditions on the microbial population during the process of decomposition. The decomposition product thus obtained was found to be rich in organic phosphorous and nitrogen, raising our hopes for a successful implementation of it in daily agricultural practices.
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- 2020
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7. 589 PROGNOSTIC IMPLICATION OF AUTONOMIC DYSFUNCTION IN NON CIRRHOTIC PORTAL HYPERTENSION: DO WE NEED TO INTERVENE?
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Behl, N., Ajmera, S., Gupta, R.C., Nijhawan, S., and Nepalia, S.
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- 2011
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8. Response to: ChatGPT's limited accuracy in generating anatomical images for medical.
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Ajmera P, Nischal N, Ariyaratne S, Botchu B, Bhamidipaty K, Iyengar KP, Ajmera SR, Jenko N, and Botchu R
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- 2024
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9. Belonging in Surgery: A Validated Instrument and Single Institutional Pilot.
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Acker RC, Sharpe J, Shea JA, Ginzberg SP, Bakillah E, Rosen CB, Finn CB, Roberts SE, Ajmera S, and Kelz RR
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- Humans, Female, Male, Pilot Projects, Surveys and Questionnaires, Adult, United States, Psychometrics, Reproducibility of Results, Internship and Residency, General Surgery education
- Abstract
Objective: The aim of this study was to develop and validate an instrument to measure Belonging in Surgery among surgical residents., Background: Belonging is the essential human need to maintain meaningful relationships and connections to one's community. Increased belongingness is associated with better well-being, job performance, and motivation to learn. However, no tools exist to measure belonging among surgical trainees., Methods: A panel of experts adapted a belonging instrument for use among United States surgery residents. After administration of the 28-item instrument to residents at a single institution, a Cronbach alpha was calculated to measure internal consistency, and exploratory principal component analyses were performed. Multiple iterations of analyses with successively smaller item samples suggested the instrument could be shortened. The expert panel was reconvened to shorten the instrument. Descriptive statistics measured demographic factors associated with Belonging in Surgery., Results: The overall response rate was 52% (114 responses). The Cronbach alpha among the 28 items was 0.94 (95% CI: 0.93-0.96). The exploratory principal component analyses and subsequent Promax rotation yielded 1 dominant component with an eigenvalue of 12.84 (70% of the variance). The expert panel narrowed the final instrument to 11 items with an overall Cronbach alpha of 0.90 (95% CI: 0.86, 0.92). Belonging in Surgery was significantly associated with race (Black and Asian residents scoring lower than White residents), graduating with one's original intern cohort (residents who graduated with their original class scoring higher than those that did not), and inversely correlated with resident stress level., Conclusions: An instrument to measure Belonging in Surgery was validated among surgical residents. With this instrument, Belonging in Surgery becomes a construct that may be used to investigate surgeon performance and well-being., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)
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- 2024
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10. Return of intracranial beta oscillations and traveling waves with recovery from traumatic brain injury.
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Vaz A, Wathen C, Miranda S, Thomas R, Darlington T, Jabarkheel R, Tomlinson S, Arena J, Bond K, Salwi S, Ajmera S, Bachschmid-Romano L, Gugger J, Sandsmark D, Diaz-Arrastia R, Schuster J, Ramayya AG, Cajigas I, Pesaran B, Chen HI, and Petrov D
- Abstract
Traumatic brain injury (TBI) remains a pervasive clinical problem associated with significant morbidity and mortality. However, TBI remains clinically and biophysically ill-defined, and prognosis remains difficult even with the standardization of clinical guidelines and advent of multimodality monitoring. Here we leverage a unique data set from TBI patients implanted with either intracranial strip electrodes during craniotomy or quad-lumen intracranial bolts with depth electrodes as part of routine clinical practice. By extracting spectral profiles of this data, we found that the presence of narrow-band oscillatory activity in the beta band (12-30 Hz) closely corresponds with the neurological exam as quantified with the standard Glasgow Coma Scale (GCS). Further, beta oscillations were distributed over the cortical surface as traveling waves, and the evolution of these waves corresponded to recovery from coma, consistent with the putative role of waves in perception and cognitive activity. We consequently propose that beta oscillations and traveling waves are potential biomarkers of recovery from TBI. In a broader sense, our findings suggest that emergence from coma results from recovery of thalamo-cortical interactions that coordinate cortical beta rhythms., Competing Interests: Competing interests: the authors declare no competing interests.
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- 2024
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11. Transpalpebral Transorbital Approach for Pediatric Temporal Epilepsy: 2-Dimensional Operative Video.
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Hafazalla K, Ajmera S, Kundishora A, Katowitz W, and Kennedy BC
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The transpalpebral approach provides a minimally invasive corridor to the anterior skull base and temporal lobe. It has been described for anterior circulation aneurysms and skull base tumors as well as more recently for resection of epileptogenic pathology in the adult population. We describe our experience using this approach in a 13-year-old adolescent boy suffering from epilepsy secondary to concomitant left temporal focal cortical dysplasia and pleomorphic xanthoastrocytoma extending throughout the amygdala with excellent results.1-5 To the best of our knowledge, this is the first published case using the transpalpebral approach for this pathology, as well for epilepsy in the pediatric population. The patient consented to the procedure and to the publication of his image., (Copyright © Congress of Neurological Surgeons 2024. All rights reserved.)
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- 2024
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12. Patient reported outcomes after multivisceral resection for advanced rectal cancers in female patients.
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Kazi M, Choubey K, Patil P, Jaiswal D, Ajmera S, Desouza A, and Saklani A
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- Humans, Female, Cross-Sectional Studies, Middle Aged, Aged, Adult, Sexual Dysfunction, Physiological etiology, Aged, 80 and over, Postoperative Complications etiology, Postoperative Complications epidemiology, Follow-Up Studies, Proctectomy adverse effects, Proctectomy methods, Rectal Neoplasms surgery, Rectal Neoplasms pathology, Patient Reported Outcome Measures, Quality of Life
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Introduction: Multivisceral resections for rectal cancer can lead to long-term functional disturbances. This study aims to evaluate the quality-of-life outcomes in female patients who underwent multivisceral resection for rectal cancer, specifically focusing on urinary and sexual functions., Methods: A cross-sectional study was conducted on female patients who underwent multivisceral rectal resections. Quality of life was assessed using the EORTC QLQ-CR29., Results: Out of 198 female patients that underwent multivisceral resections, 69 were assessable for functional outcomes. The uterus was removed in 42 patients (61%), and the posterior vaginal wall in 34 (49%). A vaginal reconstructive procedure was carried out in 30% (21 patients). Patients reported the most troubles with urinary frequency (mean: 69.6; SD: 9.9), hair loss (mean: 64.7; SD: 13.9), pain during intercourse (mean: 44; SD: 40.7), and bowel frequency (mean: 36.9; SD: -10.7) in this order. Amongst the functional scales, anxiety about future health (mean: 42.5; SD: -018.9) and interest in sex (mean: 57.2; SD: 33.2) scored the lowest., Conclusion: Multivisceral rectal resections in female patients are associated with physical and psychosocial changes resulting in urinary and bowel complaints, anxiety about future health, poor sexual health, and pain., (© 2024 Wiley Periodicals LLC.)
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- 2024
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13. Intraoperative visualization of cranial nerve schwannomas using second-window indocyanine green: A case series.
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Muhammad N, Ajmera S, and Lee JYK
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- Humans, Female, Middle Aged, Male, Adult, Neurosurgical Procedures methods, Coloring Agents administration & dosage, Indocyanine Green administration & dosage, Neurilemmoma surgery, Neurilemmoma diagnostic imaging, Cranial Nerve Neoplasms surgery, Cranial Nerve Neoplasms diagnostic imaging
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Background: Second Window Indocyanine Green (SWIG) is a novel intraoperative imaging technique that uses near-infrared (NIR) light for intra-operative tumor visualization using the well-known fluorophore indocyanine green (ICG). Because schwannomas often incorporate the nerve into the encapsulated tumor and impinge on surrounding neural structures, SWIG is a promising technique to improve tumor resection while sparing the nerve., Objective: To demonstrate the use of SWIG in resection of cranial nerve schwannomas., Methods: Three patients with cranial nerve schwannomas (i.e., trigeminal, vestibular, and vagus) underwent SWIG-guided resection. During surgery, NIR visualization was used intermittently used to detect fluorescence to guide resection. Signal-to-background ratio was then calculated to quantify fluorescence., Results: Patients were infused with ICG at a dose of 5.0 mg/kg 24 hours before surgery. Each patient achieved total or near-total resection and relief of symptoms with lack of recurrence at six-month follow-up. The average SBR calculated was 3.79, comparable to values for SWIG-guided resection of other brain and spine tumors., Conclusion: This case series is the first published report of trigeminal and vagus nerve schwannoma resection using the SWIG technique and suggests that SWIG may be used to detect all schwannomas, alongside many other types of brain tumor. This paper also demonstrates the importance of preoperative ICG infusion timing and discusses the inverse pattern of NIR signal that may be observed when infusion occurs outside of the optimal timing. This provides direction for future studies investigating the administration of SWIG to resect cranial nerve schwannomas and other brain tumors., (Copyright © 2024. Published by Elsevier B.V.)
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- 2024
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14. Middle meningeal artery patency after surgical evacuation for chronic subdural hematoma.
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Sioutas GS, Shekhtman O, Dagli MM, Salem MM, Ajmera S, Kandregula S, Burkhardt JK, Srinivasan VM, and Jankowitz BT
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- Female, Humans, Aged, Male, Retrospective Studies, Treatment Outcome, Meningeal Arteries surgery, Hematoma, Hematoma, Subdural, Chronic surgery, Embolization, Therapeutic methods
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Background: Chronic subdural hematoma (CSDH) often requires surgical evacuation, but recurrence rates remain high. Middle meningeal artery (MMA) embolization (MMAE) has been proposed as an alternative or adjunct treatment. There is concern that prior surgery might limit patency, access, penetration, and efficacy of MMAE, such that some recent trials excluded patients with prior craniotomy. However, the impact of prior open surgery on MMA patency has not been studied., Methods: A retrospective analysis was conducted on patients who underwent MMAE for cSDH (2019-2022), after prior surgical evacuation or not. MMA patency was assessed using a six-point grading scale., Results: Of the 109 MMAEs (84 patients, median age 72 years, 20.2% females), 58.7% were upfront MMAEs, while 41.3% were after prior surgery (20 craniotomies, 25 burr holes). Median hematoma thickness was 14 mm and midline shift 3 mm. Hematoma thickness reduction, surgical rescue, and functional outcome did not differ between MMAE subgroups and were not affected by MMA patency or total area of craniotomy or burr-holes. MMA patency was reduced in the craniotomy group only, specifically in the distal portion of the anterior division (p = 0.005), and correlated with craniotomy area (p < 0.001)., Conclusion: MMA remains relatively patent after burr-hole evacuation of cSDH, while craniotomy typically only affects the frontal-distal division. However, MMA patency, evacuation method, and total area do not affect outcomes. These findings support the use of MMAE regardless of prior surgery and may influence future trial inclusion/exclusion criteria. Further studies are needed to optimize the timing and techniques for MMAE in cSDH management., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)
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- 2024
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15. Neurological Surgery Residency Programs in the United States: A National Cross-Sectional Survey.
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Ng PR, Yearley AG, Eatz TA, Ajmera S, West T, Razak SS, Lazaro T, Urakov T, Jones PS, Coumans JV, Stapleton CJ, Shankar G, Chen HI, Komotar RJ, Patel AJ, and Nahed BV
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- Humans, United States, Cross-Sectional Studies, Education, Medical, Graduate, Neurosurgeons, Surveys and Questionnaires, Internship and Residency
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Background and Objectives: The Accreditation Council for Graduate Medical Education has approved 117 neurological surgery residency programs which develop and educate neurosurgical trainees. We present the current landscape of neurosurgical training in the United States by examining multiple aspects of neurological surgery residencies in the 2022-2023 academic year and investigate the impact of program structure on resident academic productivity., Methods: Demographic data were collected from publicly available websites and reports from the National Resident Match Program. A 34-question survey was circulated by e-mail to program directors to assess multiple features of neurological surgery residency programs, including curricular structure, fellowship availability, recent program changes, graduation requirements, and resources supporting career development. Mean resident productivity by program was collected from the literature., Results: Across all 117 programs, there was a median of 2.0 (range 1.0-4.0) resident positions per year and 1.0 (range 0.0-2.0) research/elective years. Programs offered a median of 1.0 (range 0.0-7.0) Committee on Advanced Subspecialty Training-accredited fellowships, with endovascular fellowships being most frequently offered (53.8%). The survey response rate was 75/117 (64.1%). Of survey respondents, the median number of clinical sites was 3.0 (range 1.0-6.0). Almost half of programs surveyed (46.7%) reported funding mechanisms for residents, including R25, T32, and other in-house grants. Residents received a median academic stipend of $1000 (range $0-$10 000) per year. Nearly all programs (93.3%) supported wellness activities for residents, which most frequently occurred quarterly (46.7%). Annual academic stipend size was the only significant predictor of resident academic productivity (R 2 = 0.17, P = .002)., Conclusion: Neurological surgery residency programs successfully train the next generation of neurosurgeons focusing on education, clinical training, case numbers, and milestones. These programs offer trainees the chance to tailor their career trajectories within residency, creating a rewarding and personalized experience that aligns with their career aspirations., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)
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- 2024
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16. Fluorophores in Endoscopic Neurosurgery.
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Ajmera S, Blue R, and Lee JYK
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- Humans, Fluorescent Dyes, Neuroendoscopy methods, Neurosurgical Procedures methods
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The complexity of intracranial anatomy and pathologies warrants the optimization of multimodal techniques to ensure safe and effective surgical treatment. Endoscopy is being more widely implemented in intracranial procedures as an important visualization tool, as it can offer panoramic views of deep structures while reducing the invasiveness of approaches. Fluorophores are frequently utilized to augment the identification of intracranial anatomic landmarks and pathologies. This chapter discusses the integration of these two surgical adjuncts, highlighting the key fluorophores used in endoscopic neurosurgery and their clinical applications., (© 2024. The Author(s), under exclusive license to Springer Nature Switzerland AG.)
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- 2024
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17. Endoscopic Microvascular Decompression.
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Ajmera S, Blue R, and Lee JYK
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- Humans, Endoscopy methods, Cranial Nerve Diseases surgery, Cranial Nerve Diseases etiology, Microvascular Decompression Surgery methods, Neuroendoscopy methods
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Microvascular decompression is a widely accepted surgical treatment for compressive cranial nerve pathologies such as trigeminal neuralgia, hemifacial spasm, glossopharyngeal neuralgia, and other craniofacial pain syndromes. Endoscopy has risen as a safe and effective minimally invasive tool to optimize microvascular decompression. Endoscopy offers improved visualization, minimizes retraction, and allows for smaller surgical openings compared to traditional microscopic approaches. There are several reports of improved neuralgia outcomes and reduced post-operative complications after endoscopic microvascular decompression. In skilled surgical hands, endoscopy is an excellent option for microvascular decompression as stand-alone tool or adjunct to the microscope. An overview of the history, operative considerations, and techniques is provided in this chapter., (© 2024. The Author(s), under exclusive license to Springer Nature Switzerland AG.)
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- 2024
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18. Large Language Model-Based Neurosurgical Evaluation Matrix: A Novel Scoring Criteria to Assess the Efficacy of ChatGPT as an Educational Tool for Neurosurgery Board Preparation.
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Mannam SS, Subtirelu R, Chauhan D, Ahmad HS, Matache IM, Bryan K, Chitta SVK, Bathula SC, Turlip R, Wathen C, Ghenbot Y, Ajmera S, Blue R, Chen HI, Ali ZS, Malhotra N, Srinivasan V, Ozturk AK, and Yoon JW
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- Humans, Artificial Intelligence, Educational Status, Neurosurgical Procedures, Language, Neurosurgery
- Abstract
Introduction: Technological advancements are reshaping medical education, with digital tools becoming essential in all levels of training. Amidst this transformation, the study explores the potential of ChatGPT, an artificial intelligence model by OpenAI, in enhancing neurosurgical board education. The focus extends beyond technology adoption to its effective utilization, with ChatGPT's proficiency evaluated against practice questions from the Primary Neurosurgery Written Board Exam., Methods: Using the Congress of Neurologic Surgeons (CNS) Self-Assessment Neurosurgery (SANS) Exam Board Review Prep questions, we conducted 3 rounds of analysis with ChatGPT. We developed a novel ChatGPT Neurosurgical Evaluation Matrix (CNEM) to assess the output quality, accuracy, concordance, and clarity of ChatGPT's answers., Results: ChatGPT achieved spot-on accuracy for 66.7% of prompted questions, 59.4% of unprompted questions, and 63.9% of unprompted questions with a leading phrase. Stratified by topic, accuracy ranged from 50.0% (Vascular) to 78.8% (Neuropathology). In comparison to SANS explanations, ChatGPT output was considered better in 19.1% of questions, equal in 51.6%, and worse in 29.3%. Concordance analysis showed that 95.5% of unprompted ChatGPT outputs and 97.4% of unprompted outputs with a leading phrase were aligned., Conclusions: Our study evaluated the performance of ChatGPT in neurosurgical board education by assessing its accuracy, clarity, and concordance. The findings highlight the potential and challenges of integrating AI technologies like ChatGPT into medical and neurosurgical board education. Further research is needed to refine these tools and optimize their performance for enhanced medical education and patient care., (Copyright © 2023 Elsevier Inc. All rights reserved.)
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- 2023
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19. The Device for Intraventricular Entry guide: a novel solution to a perpetual problem.
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Spadola M, Muhammad N, Ajmera S, Jabarkheel R, Tomlinson S, Miranda SP, Grady MS, Schuster J, and Blue R
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- Adult, Aged, Aged, 80 and over, Female, Male, Middle Aged, Catheters, Prospective Studies, Treatment Outcome, Humans, Brain Diseases surgery, Cerebral Ventricles surgery, Drainage adverse effects, Drainage instrumentation, Ventriculoperitoneal Shunt adverse effects, Ventriculoperitoneal Shunt instrumentation
- Abstract
Objective: The authors designed a low-profile device for reliable ventricular access and prospectively studied its safety, efficacy, and accuracy at a large academic center., Methods: A novel device for ventricular entry, the Device for Intraventricular Entry (DIVE) guide, was designed and created by the first and senior authors. Fifty patients undergoing external ventricular drainage (EVD) or shunt placement were prospectively enrolled for DIVE-assisted catheter placement at a single academic center. The primary outcome was the catheter tip location on postprocedural CT. Secondary outcomes included number of catheter passes, clinically significant hemorrhages, and procedure-related infections., Results: Fifty patients were enrolled. Indications included subarachnoid hemorrhage, intraventricular hemorrhage, traumatic brain injury, hydrocephalus, pseudotumor, and postsurgical wound drainage. In total, 76% (38/50) of patients underwent right-sided placement and 24% (12/50) underwent left-sided placement. All 100% (50/50) of patients had successful cannulation with an average of 1.06 passes. Postprocedural head CT confirmed ipsilateral frontal horn or third ventricle placement (Kakarla grade 1) in 92% (46/50) of patients and placement in the contralateral lateral ventricle in 8% (4/50) (Kakarla grade 2). There were no clinically significant track hemorrhages or procedural infections., Conclusions: This single-center prospective study investigated the safety and efficacy of DIVE-assisted ventricular access. In total, 100% of procedures had successful ventricular cannulation, with 92% achieving Kakarla grade 1, with an average of 1.06 passes without any clinical complications.
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- 2023
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20. Pain Outcomes Following Endoscopic Microvascular Decompression for Trigeminal Neuralgia Based on Vascular Compression Type.
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Blue R, Yang AI, Ajmera S, Spadola M, Howard S, Saylany A, Kvint S, Harber A, Daly M, Shekhtman E, Nair A, Deshpande R, and Lee JYK
- Abstract
Background Arterial compression of the trigeminal nerve at the root entry zone has been the long-attributed cause of compressive trigeminal neuralgia despite numerous studies reporting distal and/or venous compression. The impact of compression type on patient outcomes has not been fully elucidated. Objective We categorized vascular compression (VC) based on vessel and location of compression to correlate pain outcomes based on compression type. Methods A retrospective video review of 217 patients undergoing endoscopic microvascular decompression for trigeminal neuralgia categorizing VC into five distinct types, proximal arterial compression (VC1), proximal venous compression (VC2), distal arterial compression (VC3), distal venous compression (VC4), and no VC (VC5). VC type was correlated with postoperative pain outcomes at 1 month ( n = 179) and last follow-up (mean = 42.9 mo, n = 134). Results At 1 month and longest follow-up, respectively, pain was rated as "much improved" or "very much improved" in 89 69% of patients with VC1, 86.6 and 62.5% of patients with VC2, 100 and 87.5% of patients with VC3, 83 and 62.5% of patients with VC4, and 100 and 100% of patients with VC5. Multivariate analysis demonstrated VC4 as a significant negative of predictor pain outcomes at 1 month, but not longest follow-up, and advanced age as a significant positive predictor. Conclusion The degree of clinical improvement in all types of VC was excellent, but at longest follow-up VC type was not a significant predictor out outcome. However distal venous compression was significantly associated with worse outcomes at 1 month., Competing Interests: Conflict of Interest None declared., (Thieme. All rights reserved.)
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- 2023
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21. Navigated lumbar drain placement: A description of technique and case example.
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Montgomery CT, Blue R, Spadola M, Ajmera S, Jabarkheel R, and Schuster J
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Background: Lumbar drain (LD) placement can be a difficult procedure leading to postprocedure complications, particularly in patients with persistent cerebrospinal fluid leaks or a large body habitus. The objective of this technical case report is to describe the use of Medtronic's SureTrak Navigation system for navigated LD placement., Case Description: The patient was an 18-year-old morbidly obese male who initially underwent a suboccipital craniectomy with duraplasty and a C1 laminectomy for Chiari Malformation. Postoperatively, he developed a pseudomeningocele and was taken to the operating room for wound revision, duraplasty repair, and LD placement. Medtronic's SureTrak Navigation system was used for LD placement before wound revision. Successful LD placement was achieved in a single pass using the SureTrak Navigation. The patient did well postoperatively, and LD removal occurred on postoperative day 6. The patient was discharged in good condition without evidence of a cerebral spinal fluid leak., Conclusion: Navigation using the SureTrak system is a reasonable option to use in patients with a high body mass index and a persistent cerebrospinal fluid leak. When the patient is already undergoing an operative procedure, it can aid in an efficient low-risk intervention completed in a single prone positioning., Competing Interests: There are no conflicts of interest., (Copyright: © 2023 Surgical Neurology International.)
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- 2023
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22. Determinants of synergistic cell-cell interactions in bacteria.
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Pauli B, Ajmera S, and Kost C
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- Bacteria metabolism, Microbiota
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Bacteria are ubiquitous and colonize virtually every conceivable habitat on earth. To achieve this, bacteria require different metabolites and biochemical capabilities. Rather than trying to produce all of the needed materials by themselves, bacteria have evolved a range of synergistic interactions, in which they exchange different commodities with other members of their local community. While it is widely acknowledged that synergistic interactions are key to the ecology of both individual bacteria and entire microbial communities, the factors determining their establishment remain poorly understood. Here we provide a comprehensive overview over our current knowledge on the determinants of positive cell-cell interactions among bacteria. Taking a holistic approach, we review the literature on the molecular mechanisms bacteria use to transfer commodities between bacterial cells and discuss to which extent these mechanisms favour or constrain the successful establishment of synergistic cell-cell interactions. In addition, we analyse how these different processes affect the specificity among interaction partners. By drawing together evidence from different disciplines that study the focal question on different levels of organisation, this work not only summarizes the state of the art in this exciting field of research, but also identifies new avenues for future research., (© 2023 Walter de Gruyter GmbH, Berlin/Boston.)
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- 2023
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23. The Influence of Radiologist Practice Setting on Identification of Vascular Compression from Magnetic Resonance Imaging in Trigeminal Neuralgia.
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Ahmad HS, Blue R, Ajmera S, Heman-Ackah S, Spadola M, Lazor JW, and Lee JYK
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- Humans, Reproducibility of Results, Magnetic Resonance Imaging methods, Neuroimaging, Trigeminal Nerve surgery, Trigeminal Neuralgia surgery, Microvascular Decompression Surgery, Vascular Diseases surgery
- Abstract
Objective: Preoperative magnetic resonance imaging (MRI) studies are routinely ordered for trigeminal neuralgia (TN), though with contested reliability in contemporary literature. A potential reason for this disagreement is inconsistency in MRI reading methodologies. Here, we compare the rate of reported neurovascular compression on preoperative MRI by radiologists employed in community or private practice settings and academic neuroradiologists., Methods: A retrospective review was conducted on patients who underwent endoscopic microvascular decompression for TN with intraoperatively visualized neurovascular compression and primary read by a non-academic or community radiologist. Patient imaging was then re-read by a board-certified neuroradiologist practicing in an academic setting, who was blinded to the initial read and the side of TN symptoms., Results: Non-academic radiologists reported vascular compression in 26.0% (20/77) of all patients, and mention was rarely made of the non-pathological side (sensitivity = 26.0%). On academic neuroradiologist re-reads, vascular compression was noted in 87.0% (67/77) of patients on the pathological side and in 57.1% (44/77) on the non-pathological side (sensitivity = 87.0%, specificity = 42.9%). Isotropic/near isotropic 3-dimensional steady state or heavily T2-weighted sequences were read with 92.3% sensitivity and 36.9% specificity, compared to 58.3% sensitivity and 66.7% specificity using routine T2 weighted sequences., Conclusions: The frequency of vascular compression reported by non-academic radiologists is much lower than what is reported by academic neuroradiologists reading the same MRI scans. These results highlight the effect of practice setting on the predictive power of neuroimaging. Future studies are indicated to further investigate these relationships, as well as to trial newer imaging modalities., (Copyright © 2022 Elsevier Inc. All rights reserved.)
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- 2023
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24. Endoscopic microvascular decompression without the use of rigid head fixation.
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Blue R, Alexis M, Mensah-Brown K, Yang AI, Spadola M, Ajmera S, and Lee JYK
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- Humans, Retrospective Studies, Treatment Outcome, Microvascular Decompression Surgery methods, Trigeminal Neuralgia surgery, Hemifacial Spasm etiology, Glossopharyngeal Nerve Diseases etiology
- Abstract
Background: Rigid fixation using a three-point skull clamp is a common practice during cranial surgery. Despite its frequency of use, rigid fixation is not without risk of complications including hemodynamic changes, skull fractures and venous thromboembolism. Given this, alternative head fixation should be considered when clinically appropriate., Objective: We sought to demonstrate a safe and effective "pinless" head fixation system during endoscopic microvascular decompression (E-MVD)., Methods: Patients undergoing E-MVD were placed in the lateral position with a doughnut pillow under the head, providing support and reducing lateral neck flexion. The vertex of the cranium was angled 10 degrees downward and tape placed circumferentially in an X-shaped fashion around the head, avoiding direct pressure on the ears or eyes. The ipsilateral shoulder was pulled caudally away from the operative field and taped in place to ensure a maximal working corridor., Results: Fifty-two patients underwent the E-MVD procedure with pinless head fixation without any clinical complications. Indications included trigeminal neuralgia type 1 (63.5%), trigeminal neuralgia type 2 (5.8%), hemifacial spasm (19.2%), geniculate neuralgia (7.7%) and glossopharyngeal neuralgia (3.8%). There were no intraoperative or post operative complications and operative time for patients with three-point skull clamp fixation were similar compared to pinless head fixation., Conclusions: Pinless head fixation is a suitable alternative for certain patients undergoing E-MVD and provides a way to minimize complications that can occur secondary to rigid fixation. If pinless fixation is used, diligent and continued communication with the anesthetist is necessary to ensure there is no intraoperative patient movement., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)
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- 2022
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25. Matched Analysis of the Risk Assessment and Prediction Tool for Discharge Planning Following Single-Level Posterior Lumbar Fusion.
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Farooqi AS, Borja AJ, Ajmera S, Glauser G, Strouz K, Ozturk AK, Petrov D, Chen HI, McClintock SD, and Malhotra NR
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- Humans, Lumbar Vertebrae surgery, Postoperative Complications, Retrospective Studies, Risk Assessment, Risk Factors, Patient Discharge, Spinal Fusion
- Abstract
Objectives: Predicting patient needs for extended care after spinal fusion remains challenging. The Risk Assessment and Prediction Tool (RAPT) was externally developed to predict discharge disposition after nonspine orthopedic surgery but remains scarcely used in neurosurgery. The present study is the first to use coarsened exact matching-which incorporated patient characteristics known to independently affect outcomes-for 1:1 matching across a large population of single-level, posterior lumbar fusions, to isolate the predictive value of preoperative RAPT score on postoperative discharge disposition., Methods: Preoperative RAPT scores were prospectively calculated for 1066 patients undergoing consecutive single-level, posterior-only lumbar fusion within a single, university healthcare system. The primary outcome was discharge disposition. Logistic regression was executed across all patients, evaluating the RAPT score as a continuous variable to predict home discharge. Subsequently, patients were retrospectively clustered into predicted risk cohorts-validated within prior orthopedic joint research-based on the RAPT score (Lowest, Intermediate, and Highest Risk). Coarsened exact matching was performed among predicted risk cohorts, and outcomes were compared between exact-matched groups., Results: Among all patients, single-point increases in the RAPT score (i.e., decrease in predicted risk) were associated a 75% increased odds of home discharge (P < 0.001). Exact-matched analysis demonstrated increased odds of home discharge by 400% when comparing the Lowest versus Highest Risk cohorts (P = 0.004), by 750% when comparing the Intermediate versus Highest Risk cohorts (P < 0.001), and by 200% when comparing the Lowest versus Intermediate Risk cohorts (P < 0.001)., Conclusions: The RAPT score, captured in preoperative evaluations, can be highly predictive of discharge disposition following single-level, posterior lumbar fusion., (Copyright © 2022. Published by Elsevier Inc.)
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- 2022
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26. Pediatric Dog Bites: A Review of 1422 Cases Treated at a Level One Regional Pediatric Trauma Center.
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Boyd LC, Chang J, Ajmera S, Wallace RD, Alvarez SM, and Konofaos P
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- Animals, Dogs, Hospitalization, Humans, Male, Retrospective Studies, Bites and Stings epidemiology, Bites and Stings surgery, Trauma Centers
- Abstract
Background: Children under the age of 14 account for over 40% of the almost 900,000 annual hospital visits associated with dog bites. Care for dog bites ranges from simple wound irrigation to complex surgical reconstruction. Due to a number of factors, children frequently sustain dog bites to highly vulnerable regions, often necessitating intervention by plastic surgeons., Methods: This retrospective study analyzed data from the 1422 pediatric patients who sustained dog bites and presented to the Le Bonheur Children's Hospital Emergency Room from January 2011 to May 2017., Results: The typical pediatric dog bite case was male (63.5%), African-American (57.4%), and less than 10 years old (69.4%). The head and neck were the most commonly affected areas (64.7%). Of the head and neck regions, the cheeks and lips were the most frequently injured structures (34.5%). Hospital admission was required for 188 patients (13.2%) and operative repair was deemed necessary in 16.9% of all cases. Of the patients requiring inpatient operative repair, most (78.3%) were discharged in less than 24 hours. Operative complications occurred in 5.8% of all cases, with infections accounting for the majority (92.9%). No fatal dog bites occurred in this study., Conclusions: Age, bite location, and number of bites sustained are several factors of significance, which may aid the novice plastic surgeon in identifying, which pediatric dog bite cases will require surgical intervention., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by Mutaz B. Habal, MD.)
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- 2022
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27. Aspergillus derived mycotoxins in food and the environment: Prevalence, detection, and toxicity.
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Navale V, Vamkudoth KR, Ajmera S, and Dhuri V
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Aspergillus species are the paramount ubiquitous fungi that contaminate various food substrates and produce biochemicals known as mycotoxins. Aflatoxins (AFTs), ochratoxin A (OTA), patulin (PAT), citrinin (CIT), aflatrem (AT), secalonic acids (SA), cyclopiazonic acid (CPA), terrein (TR), sterigmatocystin (ST) and gliotoxin (GT), and other toxins produced by species of Aspergillus plays a major role in food and human health. Mycotoxins exhibited wide range of toxicity to the humans and animal models even at nanomolar (nM) concentration. Consumption of detrimental mycotoxins adulterated foodstuffs affects human and animal health even trace amounts. Bioaerosols consisting of spores and hyphal fragments are active elicitors of bronchial irritation and allergy, and challenging to the public health. Aspergillus is the furthermost predominant environmental contaminant unswervingly defile lives with a 40-90 % mortality risk in patients with conceded immunity. Genomics, proteomics, transcriptomics, and metabolomics approaches useful for mycotoxins' detection which are expensive. Antibody based detection of toxins chemotypes may result in cross-reactivity and uncertainty. Aptamers (APT) are single stranded DNA (ssDNA/RNA), are specifically binds to the target molecules can be generated by systematic evolution of ligands through exponential enrichment (SELEX). APT are fast, sensitive, simple, in-expensive, and field-deployable rapid point of care (POC) detection of toxins, and a better alternative to antibodies., Competing Interests: The authors report no declarations of interest., (© 2021 The Authors.)
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- 2021
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28. Dissecting the Financial Relationship Between Industry and Academic Neurosurgery.
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Motiwala M, Herr MJ, Jampana Raju SS, Lillard J, Ajmera S, Saad H, Schultz A, Fraser B, Wallace D, Norrdahl S, Akinduro O, Oravec CS, Xu R, Jimenez B, Justo M, Hardee J, Vaughn BN, Michael LM, and Klimo P
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- Aged, Child, Databases, Factual, Female, Humans, Male, Medicare, Neurosurgeons, Spine, United States, Neurosurgery, Surgeons
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Background: Established by the Centers for Medicare and Medicaid Services (CMS), the Open Payments Database (OPD) has reported industry payments to physicians since August 2013., Objective: To evaluate the frequency, type, and value of payments received by academic neurosurgeons in the United States over a 5-yr period (2014-2018)., Methods: The OPD was queried for attending neurosurgeons from all neurosurgical training programs in the United States (n = 116). Information from the OPD was analyzed for the entire cohort as well as for comparative subgroup analyses, such as career stage, subspecialty, and geographic location., Results: Of all identified neurosurgeons, 1509 (95.0%) received some payment from industry between 2014 and 2018 for a total of 106 171 payments totaling $266 407 458.33. A bimodal distribution was observed for payment number and total value: 0 to 9 (n = 438) vs > 50 (n = 563) and 0-$1000 (n = 418) vs >$10 000 (n = 653), respectively. Royalty/License was the most common type of payment overall (59.6%; $158 723 550.57). The median number (40) and value ($8958.95) of payments were highest for mid-career surgeons. The South-Central region received the most money ($117 970 036.39) while New England received the greatest number of payments (29 423). Spine surgeons had the greatest median number (60) and dollar value ($20 551.27) of payments, while pediatric neurosurgeons received the least (8; $1108.29). Male neurosurgeons received a greater number (31) and value ($6395.80) of payments than their female counterparts (11, $1643.72)., Conclusion: From 2014 to 2018, payments to academic neurosurgeons have increased in number and value. Dollars received were dependent on geography, career stage, subspecialty and gender., (Copyright © 2020 by the Congress of Neurological Surgeons.)
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- 2020
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29. Predicting Surgical Intervention in Cerebellar Stroke: A Quantitative Retrospective Analysis.
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Taylor DR, Basma J, Jones GM, Lillard J, Wallace D, Ajmera S, Gienapp AJ, and Michael LM 2nd
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- Aged, Brain Edema etiology, Brain Stem diagnostic imaging, Brain Stem pathology, Brain Stem Infarctions etiology, Cerebellar Diseases complications, Cerebellum diagnostic imaging, Cerebellum pathology, Clinical Decision Rules, Cohort Studies, Female, Humans, Hydrocephalus etiology, Ischemic Stroke complications, Magnetic Resonance Imaging, Male, Middle Aged, Organ Size, Retrospective Studies, Risk Assessment, Tomography, X-Ray Computed, Brain Edema surgery, Brain Stem Infarctions surgery, Cerebellar Diseases surgery, Decompression, Surgical statistics & numerical data, Hydrocephalus surgery, Ischemic Stroke surgery
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Background: Debate still exists regarding whether preventive surgical decompression should be offered to high-risk patients experiencing cerebellar stroke. This study aimed to predict neurologic decline based on risk factors, volumetric analysis, and imaging characteristics., Methods: This retrospective cohort study comprised patients ≥18 years who presented with acute cerebellar ischemic stroke (CIS) between January 2011 and December 2016. Diagnostic imaging was used to calculate metrics based on individual stroke, cerebellar, and posterior fossa volumes. Head computed tomography scans on presentation and day of peak swelling were used to tabulate a CIS score., Results: The study included 86 patients; most were male and African American. Posterior inferior communicating artery stroke was most common (50%). On initial presentation imaging, 18.6% had documented hydrocephalus, 20.9% had brainstem compression, 22.1% had brainstem stroke, and 39.5% had stroke in another vascular territory. Cardioembolic stroke was the most common etiology, followed by cryptogenic stroke. Overall, patients who underwent surgical intervention had larger stroke volumes on presentation. Patients undergoing surgical intervention also experienced faster cerebellar swelling compared with patients without intervention. Total CIS scores were statistically significant and remained significant on the peak day of swelling. CIS score was independently associated with neurosurgical intervention; patients in this group with delayed interventions (median CIS score, 6; range, 4-8) later deteriorated and required emergent surgical decompression. Eleven patients without intervention had CIS score >6; 4 patients died of stroke complications., Conclusions: Volumetric studies and CIS score are objective measures that may help predict decline on imaging before clinical deterioration., (Copyright © 2020 Elsevier Inc. All rights reserved.)
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- 2020
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30. What Variables Correlate With Different Clinical Outcomes of Abusive Head Injury?
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Ajmera S, Motiwala M, Weeks M, Oravec CS, Hersh DS, Fraser BD, Vaughn B, and Klimo P
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- Child, Preschool, Female, Humans, Infant, Male, Retrospective Studies, Risk Factors, Child Abuse, Craniocerebral Trauma complications, Stroke epidemiology, Stroke etiology
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Background: The spectrum of injury severity for abusive head trauma (AHT) severity is broad, but outcomes are unequivocally worse than accidental trauma. There are few publications that analyze different outcomes of AHT., Objective: To determine variables associated with different outcomes of AHT., Methods: Patients were identified using our AHT database. Three different, but not mutually exclusive, outcomes of AHT were modeled: (1) death or hemispheric stroke (diffuse loss of grey-white differentiation); (2) stroke(s) of any size; and (3) need for a neurosurgical operation. Demographic and clinical variables were collected and correlations to the 3 outcomes of interest were identified using bivariate and multivariable analysis., Results: From January 2009 to December 2017, 305 children were identified through a prospectively maintained AHT database. These children were typically male (60%), African American (54%), and had public or no insurance (90%). A total of 29 children (9.5%) died or suffered a massive hemispheric stroke, 57 (18.7%) required a neurosurgical operation, and 91 (29.8%) sustained 1 or more stroke. Death or hemispheric stroke was statistically associated with the pupillary exam (odds ratio [OR] = 45.7) and admission international normalized ratio (INR) (OR = 17.3); stroke was associated with the pupillary exam (OR = 13.2), seizures (OR = 14.8), admission hematocrit (OR = 0.92), and INR (9.4), and need for surgery was associated with seizures (OR = 8.6)., Conclusion: We have identified several demographic and clinical variables that correlate with 3 clinically applicable outcomes of abusive head injury., (Copyright © 2020 by the Congress of Neurological Surgeons.)
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- 2020
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31. Decoding Task-Specific Cognitive States with Slow, Directed Functional Networks in the Human Brain.
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Ajmera S, Jain H, Sundaresan M, and Sridharan D
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- Brain Mapping, Cognition, Computer Simulation, Humans, Magnetic Resonance Imaging, Nerve Net diagnostic imaging, Brain diagnostic imaging, Connectome
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Flexible functional interactions among brain regions mediate critical cognitive functions. Such interactions can be measured using functional magnetic resonance imaging (fMRI) data either with instantaneous (zero-lag) or lag-based (time-lagged) functional connectivity. Because the fMRI hemodynamic response is slow, and is sampled at a timescale (seconds) several orders of magnitude slower than the underlying neural dynamics (milliseconds), simulation studies have shown that lag-based fMRI functional connectivity, measured with approaches like Granger-Geweke causality (GC), provides spurious and unreliable estimates of underlying neural interactions. Experimental verification of this claim is challenging because neural ground truth connectivity is often unavailable concurrently with fMRI recordings. Here we demonstrate that, despite these widely held caveats, GC networks estimated from fMRI recordings contain useful information for classifying task-specific cognitive states. We estimated instantaneous and lag-based GC functional connectivity networks using fMRI data from 1000 participants (Human Connectome Project database). A linear classifier, trained on either instantaneous or lag-based GC, reliably discriminated among seven different task and resting brain states, with >80% cross-validation accuracy. With network simulations, we demonstrate that instantaneous and lag-based GC exploited interactions at fast and slow timescales, respectively, to achieve robust classification. With human fMRI data, instantaneous and lag-based GC identified complementary, task-core networks. Finally, variations in GC connectivity explained inter-individual variations in a variety of cognitive scores. Our findings show that instantaneous and lag-based methods reveal complementary aspects of functional connectivity in the brain, and suggest that slow, directed functional interactions, estimated with fMRI, may provide useful markers of behaviorally relevant cognitive states., (Copyright © 2020 Ajmera et al.)
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- 2020
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32. Shunt Failure-The First 30 Days.
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Lee RP, Ajmera S, Thomas F, Dave P, Lillard JC, Wallace D, Broussard A, Motiwala M, Norrdahl SP, Venable GT, Khan NR, Harrell C, Jones TL, Vaughn BN, Gooldy T, Hersh DS, and Klimo P
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- Adolescent, Adult, Cerebrospinal Fluid Shunts methods, Cerebrospinal Fluid Shunts trends, Child, Child, Preschool, Cohort Studies, Female, Humans, Infant, Infant, Newborn, Male, Retrospective Studies, Time Factors, Ventriculoperitoneal Shunt methods, Young Adult, Cerebral Ventricles diagnostic imaging, Cerebral Ventricles surgery, Hydrocephalus diagnostic imaging, Hydrocephalus surgery, Treatment Failure, Ventriculoperitoneal Shunt trends
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Background: Incontrovertible predictors of shunt malfunction remain elusive., Objective: To determine predictors of shunt failure within 30 d of index surgery., Methods: This was a single-center retrospective cohort study from January 2010 through November 2016. Using a ventricular shunt surgery research database, clinical and procedural variables were procured. An "index surgery" was defined as implantation of a new shunt or revision or augmentation of an existing shunt system. The primary outcome was shunt failure of any kind within the first 30 days of index surgery. Bivariate models were created, followed by a final multivariable logistic regression model using a backward-forward selection procedure., Results: Our dataset contained 655 unique patients with a total of 1206 operations. The median age for the cohort at the time of first shunt surgery was 4.6 yr (range, 0-28; first and third quartile, .37 and 11.8, respectively). The 30-day failure rates were 12.4% when analyzing the first-index operation only (81/655), and 15.7% when analyzing all-index operations (189/1206). Small or slit ventricles at the time of index surgery and prior ventricular shunt operations were found to be significant covariates in both the "first-index" (P < .01 and P = .05, respectively) and "all-index" (P = .02 and P < .01, respectively) multivariable models. Intraventricular hemorrhage at the time of index surgery was an additional predictor in the all-index model (P = .01)., Conclusion: This study demonstrates that only 3 variables are predictive of 30-day shunt failure when following established variable selection procedures, 2 of which are potentially under direct control of the surgeon., (Copyright © 2019 by the Congress of Neurological Surgeons.)
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- 2020
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33. Innovation, Royalties, and Introduction of the Patent Hirsch Index within U.S. Academic Neurosurgery.
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Motiwala M, Kumar R, Ajmera S, Lillard J, Saad H, Schultz A, Fraser B, Wallace D, Norrdahl S, Akinduro O, Oravec C, Xu R, Jimenez B, Justo M, Hardee J, Yunis Y, Gungor B, Whitaker J, and Klimo P Jr
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- Humans, United States, Inventions economics, Inventions statistics & numerical data, Neurosurgeons, Neurosurgery, Patents as Topic statistics & numerical data
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Background: Historically, practicing neurosurgeons have been key drivers of neurosurgical innovation. We sought to describe the patents held by U.S. academic neurosurgeons and to explore the relationship between patents and royalties received., Methods: The Centers for Medicare and Medicaid CMS Open Payments Data was used to identify academic neurosurgeons who had received royalties and royalty amounts during a 5-year period (2013-2017). Online patent databases were used to gather patent details. Patent citations and 5-year individual and departmental patent Hirsch (h)-indexes were calculated. Royalties were correlated with the number of patents, patent citations, and patent h-index., Results: We found that 119 academic neurosurgeons (7.8%) from 57 U.S. teaching programs (48.3%) had received royalty payments; 72 (60.5%) had published 648 patents. All surgeons were men, with approximately one half in the "late" stages of their career (45.3%) and subspecializing in spinal surgery (50.4%). The patented products or devices were most commonly used for spinal surgery (72.1%), with 2010-2019 the most productive period (n = 455; 70.2%). The median number of citations per patent was 32 (range, 0-620), with 33% having ≥100 citations. The highest individual and institutional patent h-index was 95; 25 (34.7%) neurosurgeons had a patent h-index of ≥5. The median total royalty payment per individual neurosurgeon was $111,011 (range, $58.05-$76,715,750.34). Royalties were correlated with the number of patents (Spearman r = 0.37; P ≤ 0.001), citations (Spearman r, 0.38; P ≤ 0.001), and inventor h-index (Spearman r = 0.38; P ≤ 0.001)., Conclusions: Few U.S. academic neurosurgeons (7.8%) receive royalties and hold patents (4.7%), with an even smaller select group having a patent h-index of ≥5 (1.6%)., (Copyright © 2020 Elsevier Inc. All rights reserved.)
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- 2020
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34. Management of Subdural Hematohygromas in Abusive Head Trauma.
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Nguyen VN, Wallace D, Ajmera S, Akinduro O, Smith LJ, Giles K, Vaughn B, and Klimo P
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- Child, Preschool, Cohort Studies, Craniocerebral Trauma diagnostic imaging, Craniocerebral Trauma etiology, Female, Follow-Up Studies, Hematoma, Subdural, Chronic diagnostic imaging, Hematoma, Subdural, Chronic etiology, Humans, Infant, Male, Retrospective Studies, Child Abuse, Craniocerebral Trauma surgery, Craniotomy methods, Drainage methods, Hematoma, Subdural, Chronic surgery, Trephining methods
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Background: The optimal management of nonacute subdural fluid collections in infantile abusive head trauma (AHT) remains controversial., Objective: To review the outcomes and costs of the various treatments for symptomatic subdural fluid collections in children with AHT at a single center., Methods: Our AHT database was queried to identify children requiring any intervention for hematohygromas. Demographic, hospital course, radiologic, cost, readmission, and follow-up information were collected., Results: From January 2009 to March 2018, the authors identified 318 children with AHT, of whom 210 (66%) had a subdural collection of any type (blood or cerebrospinal fluid). A total of 50 required some form of intervention specifically for chronic hematohygromas. The initial management consisted of transfontanelle percutaneous aspiration (n = 31), burr holes with (n = 12) or without (n = 3) external subdural drainage, and mini-craniotomy (n = 4). Of those who were initially managed with 1 or more needle aspiration, 23 (74%) required further intervention-12 subduroperitoneal shunts and 11 nonshunt procedures. No patient who underwent burr holes/external drainage required further intervention (n = 16). Overall, the average number of interventions needed in these 50 children for definitive treatment was 1.8 (range, 1-4). A total of 15 children ultimately required a subduroperitoneal shunt. Complications (infectious, hemorrhagic, and thrombotic) were significant and occurred in all treatment groups except burr holes without drainage (n = 3). The average hospital charge for the entire cohort was $166 300.25 (range, $19 126-$739 248)., Conclusion: Based on our experience to date, burr hole with controlled external subdural drainage is an effective and preferred treatment for traumatic hematohygromas; complications and need for additional intervention is low., (Copyright © 2019 by the Congress of Neurological Surgeons.)
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- 2020
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35. Management of sterile abdominal pseudocysts related to ventriculoperitoneal shunts.
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Erwood A, Rindler RS, Motiwala M, Ajmera S, Vaughn B, Klimo P, and Chern JJ
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Objective: There are many known complications associated with CSF shunts. One of the more rare ones is a sterile abdominal pseudocyst due to decreased peritoneal absorption. This study was undertaken to detail the presentation, evaluation, and management of this unusual shunt-related event., Methods: Patients presenting with ventriculoperitoneal shunt (VPS)-related sterile abdominal pseudocysts treated at two institutions between 2013 and 2018 were included. Patients who had undergone abdominal surgery or shunt revisions within a 12-month period preceding presentation were excluded. Information was collected regarding clinical characteristics; hospital course, including surgical intervention(s); and any subsequent complications. Special attention was given to the eventual surgery after pseudocyst resolution, including the use of laparoscopy for peritoneal catheter placement, distal shunt conversion (i.e., in the atrium or pleural cavity), endoscopic third ventriculostomy, or shunt removal. The timing and nature of any subsequent shunt failures were also noted., Results: Twenty-eight patients met the study criteria, with a mean age of 10 years. The most common etiology of hydrocephalus was intraventricular hemorrhage of prematurity. All shunts were externalized at presentation. One shunt was removed without subsequent internalization. Distal catheters were re-internalized back into the peritoneal cavity in 11 patients (laparoscopy was used in 8 cases). Fourteen shunts were converted to a ventriculoatrial shunt (VAS), and two to a ventriculopleural (VPlS). Two VPSs failed due to a recurrent pseudocyst. The total all-cause failure rates at 1 year were as follows: 18% for VPSs and 50% for VASs., Conclusions: Following treatment of a VPS-related sterile abdominal pseudocyst, laparoscopy-assisted placement of the distal catheter in the peritoneum is a viable and safe option for select patients, compared to a VAS or VPlS.
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- 2019
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36. Image Guidance for Ventricular Shunt Surgery: An Analysis of Hospital Charges.
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Ajmera S, Motiwala M, Khan NR, Smith LJ, Giles K, Vaughn B, and Klimo P
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- Female, Humans, Hydrocephalus diagnostic imaging, Imagery, Psychotherapy economics, Imagery, Psychotherapy trends, Length of Stay economics, Length of Stay trends, Male, Neuronavigation economics, Neuronavigation trends, Operating Rooms economics, Operating Rooms trends, Retrospective Studies, Tomography, X-Ray Computed trends, Ventriculoperitoneal Shunt trends, Hospital Charges trends, Hydrocephalus economics, Hydrocephalus surgery, Tomography, X-Ray Computed economics, Ventriculoperitoneal Shunt economics
- Abstract
Background: Image guidance for shunt surgery results in more accurate proximal catheter placement. However, reduction in shunt failure remains unclear in the literature. There have been no prior studies evaluating the cost effectiveness of neuronavigation for shunt surgery., Objective: To perform a cost analysis using available hospital charges of hypothetical shunt surgery performed with/without electromagnetic neuronavigation (EMN)., Methods: Hospital charges were collected for physician fees, radiology, operating room (OR) time and supplies, postanesthesia care unit, hospitalization days, laboratory, and medications. Index shunt surgery charges (de novo or revision) were totaled and the difference calculated. This difference was compared with hospital charges for shunt revision surgery performed under 2 clinical scenarios: (1) same hospital stay as the index surgery; and (2) readmission through the emergency department., Results: Costs for freehand de novo and revision shunt surgery were $23 946.22 and $23 359.22, respectively. For stealth-guided de novo and revision surgery, the costs were $33 646.94 and $33 059.94, a difference of $9700.72. The largest charge increase was due to additional OR time (34 min; $4794), followed by disposable EMN equipment ($2672). Total effective charges to revise the shunt for scenarios 1 and 2 were $34 622.94 and $35 934.94, respectively. The cost ratios between the total revision charges for both scenarios and the difference in freehand vs EMN-assisted shunt surgery ($9700.72) were 3.57 and 3.70, respectively., Conclusion: From an economic standpoint and within the limitations of our models, the number needed to prevent must be 4 or less for the use of neuronavigation to be considered cost effective., (Copyright © 2019 by the Congress of Neurological Surgeons.)
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- 2019
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37. Postgraduate publishing output in pediatric neurosurgery: correlation with fellowship site and individual scholars.
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Ajmera S, Lee RP, Schultz A, Hersh DS, Lepard J, Xu R, Saad H, Akinduro O, Justo M, Fraser BD, Motiwala M, Dave P, Jimenez B, Wallace DA, Osikoya O, Norrdahl S, Dooley JH, Khan NR, Vaughn BN, Maher CO, and Klimo P
- Abstract
Objective: The objective of this study was to analyze the publication output of postgraduate pediatric neurosurgery fellows for a 10-year period as well as identify 25 individual highly productive pediatric neurosurgeons. The correlation between academic productivity and the site of fellowship training was studied., Methods: Programs certified by the Accreditation Council for Pediatric Neurosurgery Fellowships that had 5 or more graduating fellows from 2006 to 2015 were included for analysis. Fellows were queried using Scopus for publications during those 10 years with citation data through 2017. Pearson correlation coefficients were calculated, comparing program rankings of faculty against fellows using the revised Hirsch index (r-index; primary) and Hirsch index (h-index; secondary). A list of 25 highly accomplished individual academicians and their fellowship training locations was compiled., Results: Sixteen programs qualified with 152 fellows from 2006 to 2015; 136 of these surgeons published a total of 2009 articles with 23,735 citations. Most publications were pediatric-specific (66.7%) clinical articles (93.1%), with middle authorship (55%). Co-investigators were more likely from residency than fellowship. There was a clustering of the top 7 programs each having total publications of around 120 or greater, publications per fellow greater than 12, more than 1200 citations, and adjusted ir10 (revised 10-year institutional h-index) and ih10 (10-year institutional h-index) values of approximately 2 or higher. Correlating faculty and fellowship program rankings yielded correlation coefficients ranging from 0.53 to 0.80. Fifteen individuals (60%) in the top 25 (by r5 index) list completed their fellowship at 1 of these 7 institutions., Conclusions: Approximately 90% of fellowship-trained pediatric neurosurgeons have 1 or more publications, but the spectrum of output is broad. There is a strong correlation between where surgeons complete their fellowships and postgraduate publications.
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- 2019
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38. An Analysis of Publication Productivity During Residency for 1506 Neurosurgical Residents and 117 Residency Departments in North America.
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Khan NR, Saad H, Oravec CS, Norrdahl SP, Fraser B, Wallace D, Lillard JC, Motiwala M, Nguyen VN, Lee SL, Jones AV, Ajmera S, Kalakoti P, Dave P, Moore KA, Akinduro O, Nyenwe E, Vaughn B, Michael LM, and Klimo P
- Subjects
- Bibliometrics, Databases, Factual, Efficiency, Humans, North America, Internship and Residency statistics & numerical data, Neurosurgeons supply & distribution, Neurosurgery organization & administration, Publications statistics & numerical data
- Abstract
Background: Bibliometrics is defined as the study of statistical and mathematical methods used to quantitatively analyze scientific literature. The application of bibliometrics in neurosurgery continues to evolve., Objective: To calculate a number of publication productivity measures for almost all neurosurgical residents and departments within North America. These measures were correlated with survey results on the educational environment within residency programs., Methods: During May to June 2017, data were collected from departmental websites and Scopus to compose a bibliometric database of neurosurgical residents and residency programs. Data related to authorship value and study content were collected on all articles published by residents. A survey of residency program research and educational environment was administered to program directors and coordinators; results were compared with resident academic productivity., Results: The median number of publications in residency was 3; median h-index and Resident index were 1 and 0.17 during residency, respectively. There was a statistically significant difference in academic productivity among male neurosurgical residents compared with females. The majority of articles published were tier 1 clinical articles. Residency program research support was significantly associated with increased resident productivity (P < .001). Scholarly activity requirements were not associated with increased resident academic productivity., Conclusion: This study represents the most comprehensive bibliometric assessment of neurosurgical resident academic productivity during training to date. New benchmarks for individual and department academic productivity are provided. A supportive research environment for neurosurgical residents is associated with increased academic productivity, but a scholarly activity requirement was, surprisingly, not shown to have a positive effect., (Copyright © 2018 by the Congress of Neurological Surgeons.)
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- 2019
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39. How Does the Media Portray Neurosurgeons?
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Motiwala M, Ajmera S, Akinduro O, Wallace D, Norrdahl SP, Schultz A, Fraser B, Saad H, Justo M, Dave P, Nguyen V, Vaughn B, Michael LM, and Klimo P Jr
- Subjects
- Attitude, Female, Humans, Male, United States, Communications Media, Internet, Neurosurgeons
- Abstract
Background: It is not unusual to find neurosurgeons in the news and entertainment. The present study examined the portrayal of neurosurgeons by major print and online media sources., Methods: Two search strategies identified articles from October 1, 2012 to October 1, 2017 containing the keyword "neurosurgeon." The top 25 newspapers in the United States, determined by their circulation, were searched using the LexisNexis Academic or NewsBank databases; a layman's Google News search was used to collect online stories. Each identified article was evaluated to confirm the relevance and then examined for content. Relevant characteristics for each article and neurosurgeon were determined and analyzed., Results: Our searches returned 1005 articles comprising 561 unique stories about 203 different neurosurgeons. One particular neurosurgeon had 459 reports (45.7%). More articles were reported in 2015 (405; 40.3%) than any other single year. Most articles featured male neurosurgeons (879; 87.1%) and neurosurgeons who had been practicing for >20 years (636; 63.0%), with just 10 institutions accounting for the training of most of them (733; 72.6%). The articles were classified as positive (270; 26.9%), negative (356; 35.4%), or neutral (379; 37.7%) in terms of their reflection on the field of neurosurgery. The odds of a negative story were greater for male neurosurgeons, within 10 years of residency completion, and in a nonacademic position., Conclusions: Neurosurgeons are naturally subject to media coverage, and we must be cognizant that this predilection can serve as both an occupational advantage and an occupational hazard., (Copyright © 2018 Elsevier Inc. All rights reserved.)
- Published
- 2019
- Full Text
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40. Infra-slow brain dynamics as a marker for cognitive function and decline.
- Author
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Ajmera S, Rajagopal S, Rehman RU, and Sridharan D
- Abstract
Functional magnetic resonance imaging (fMRI) enables measuring human brain activity, in vivo . Yet, the fMRI hemodynamic response unfolds over very slow timescales (<0.1-1 Hz), orders of magnitude slower than millisecond timescales of neural spiking. It is unclear, therefore, if slow dynamics as measured with fMRI are relevant for cognitive function. We investigated this question with a novel application of Gaussian Process Factor Analysis (GPFA) and machine learning to fMRI data. We analyzed slowly sampled (1.4 Hz) fMRI data from 1000 healthy human participants (Human Connectome Project database), and applied GPFA to reduce dimensionality and extract smooth latent dynamics. GPFA dimensions with slow (<1 Hz) characteristic timescales identified, with high accuracy (>95%), the specific task that each subject was performing inside the fMRI scanner. Moreover, functional connectivity between slow GPFA latents accurately predicted inter-individual differences in behavioral scores across a range of cognitive tasks. Finally, infra-slow (<0.1 Hz) latent dynamics predicted CDR (Clinical Dementia Rating) scores of individual patients, and identified patients with mild cognitive impairment (MCI) who would progress to develop Alzheimer's dementia (AD). Slow and infra-slow brain dynamics may be relevant for understanding the neural basis of cognitive function, in health and disease.
- Published
- 2019
41. Emergent and Urgent Craniotomies in Pediatric Patients: Resource Utilization and Cost Analysis.
- Author
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Ajmera S, Motiwala M, Lingo R, Khan NR, Smith LJ, Giles K, Vaughn B, and Klimo P Jr
- Subjects
- Adolescent, Child, Child, Preschool, Cost-Benefit Analysis trends, Craniocerebral Trauma diagnosis, Craniocerebral Trauma economics, Craniocerebral Trauma surgery, Craniotomy trends, Emergency Treatment trends, Female, Health Resources trends, Humans, Infant, Infant, Newborn, Male, Retrospective Studies, Cost-Benefit Analysis methods, Craniotomy economics, Emergency Treatment economics, Health Resources economics, Patient Acceptance of Health Care
- Abstract
Background: Pediatric neurosurgeons are occasionally tasked with performing surgery expeditiously to preserve a child's neurologic faculties and life., Objective: This study examines the etiologies, outcomes, and costs for urgent or emergent craniotomies at a Level I Pediatric Trauma center over a 7-year time period., Methods: A retrospective review was conducted for each patient who underwent an emergent or urgent craniotomy within 24 hours of presentation between January 2010 and April 2017. Demographic, clinical, and surgical details were recorded for a total of 48 variables. Any readmission within 90 days was analyzed. Hospital charges for each admission and readmission were collected and adjusted for inflation to October 2018 values., Results: Among the 223 children who underwent urgent or emergent craniotomies, the majority were admitted for traumatic injuries (n = 163, 73.1%). The most common traumatic mechanism was fall (n = 51, 22.9%), and the most common non-traumatic cause was tumor (n = 21, 9.4%). Overall, craniotomies were typically performed for hematoma evacuation of one type or combination (n = 115, 51.6%) during off-peak times (n = 178, 79.8%). Seventy-seven (34.5%) subjects experienced 1 or more postoperative events, 22 of whom returned to the operating room. There were 13 (5.8%) and 33 (14.8%) readmissions within 30 days and 90 days of discharge, respectively. Non-trauma patients (compared with trauma patients) and polytrauma (compared with isolated head injury) had greater healthcare needs, resulting in higher charges., Conclusion: Most urgent or emergent pediatric craniotomies were performed for the treatment of traumatic injuries involving hematoma evacuation, but non-traumatic patients were more complex requiring greater resources., (© 2019 S. Karger AG, Basel.)
- Published
- 2019
- Full Text
- View/download PDF
42. Taking the next step in publication productivity analysis in pediatric neurosurgery.
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Lee RP, Xu R, Dave P, Ajmera S, Lillard JC, Wallace D, Broussard A, Motiwala M, Norrdahl S, Howie C, Akinduro O, Venable GT, Khan NR, Taylor DR, Vaughn BN, and Klimo P
- Subjects
- Humans, Neurosurgery education, Neurosurgery methods, Neurosurgery statistics & numerical data, Neurosurgical Procedures methods, Neurosurgical Procedures statistics & numerical data, Neurosurgical Procedures education, Pediatrics education, Periodicals as Topic statistics & numerical data, Publications statistics & numerical data
- Abstract
OBJECTIVE There has been an increasing interest in the quantitative analysis of publishing within the field of neurosurgery at the individual, group, and institutional levels. The authors present an updated analysis of accredited pediatric neurosurgery training programs. METHODS All 28 Accreditation Council for Pediatric Neurosurgery Fellowship programs were contacted for the names of pediatric neurosurgeons who were present each year from 2011 through 2015. Faculty names were queried in Scopus for publications and citations during this time period. The 5-year institutional Hirsch index [i h(5)-index] and revised 5-year institutional h-index [i r(5)-index] were calculated to rank programs. Each publication was reviewed to determine authorship value, tier of research, clinical versus basic science research, subject matter, and whether it was pediatrics-specific. A unique 3-tier article classification system was introduced to stratify clinical articles by quality and complexity, with tier 3 being the lowest tier of publication (e.g., case reports) and tier 1 being the highest (e.g., randomized controlled trials). RESULTS Among 2060 unique publications, 1378 (67%) were pediatrics-specific. The pediatrics-specific articles had a mean of 15.2 citations per publication (median 6), whereas the non-pediatrics-specific articles had a mean of 23.0 citations per publication (median 8; p < 0.0001). For the 46% of papers that had a pediatric neurosurgeon as first or last author, the mean number of citations per publication was 12.1 (median 5.0) compared with 22.5 (median 8.0) for those in which a pediatric neurosurgeon was a middle author (p < 0.0001). Seventy-nine percent of articles were clinical research and 21% were basic science or translational research; however, basic science and translational articles had a mean of 36.9 citations per publication (median 15) compared with 12.6 for clinical publications (median 5.0; p < 0.0001). Among clinical articles, tier 1 papers had a mean of 15.0 citations per publication (median 8.0), tier 2 papers had a mean of 18.7 (median 8.0), and tier 3 papers had a mean of 7.8 (median 3.0). Neuro-oncology papers received the highest number of citations per publication (mean 25.7). The most common journal was the Journal of Neurosurgery: Pediatrics (20%). MD/PhD faculty members had significantly more citations per publication than MD faculty members (mean 26.7 vs 14.0; p < 0.0001) and also a higher number of publications per author (mean 38.6 vs 20.8). The median i h(5)- and i r(5)-indices per program were 14 (range 5-48) and 10 (range 5.6-37.2), respectively. The mean i r(5)/i h(5)-index ratio was 0.8. The top 5 fellowship programs (in descending order) as ranked by the i h(5)-index corrected for number of faculty members were The Hospital for Sick Children, Toronto; Children's Hospital of Pittsburgh; University of California, San Francisco Benioff Children's Hospital; Seattle Children's Hospital; and St. Louis Children's Hospital. CONCLUSIONS About two-thirds of publications authored by pediatric neurosurgeons are pediatrics-specific, although non-pediatrics-specific articles averaged more citations. Most of the articles authored by pediatric neurosurgeons are clinical, with basic and translational articles averaging more citations. Neurosurgeons with PhD degrees averaged more total publications and more citations per publication. In all, this is the most advanced and informative analysis of publication productivity in pediatric neurosurgery to date.
- Published
- 2018
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43. Discovery and optimization of 3-(4-aryl/heteroarylsulfonyl)piperazin-1-yl)-6-(piperidin-1-yl)pyridazines as novel, CNS penetrant pan-muscarinic antagonists.
- Author
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Bender AM, Weiner RL, Luscombe VB, Ajmera S, Cho HP, Chang S, Zhan X, Rodriguez AL, Niswender CM, Engers DW, Bridges TM, Conn PJ, and Lindsley CW
- Subjects
- Animals, Brain drug effects, CHO Cells, Cricetulus, Humans, Muscarinic Antagonists chemistry, Piperazine, Piperazines chemistry, Piperazines pharmacokinetics, Piperazines pharmacology, Pyridazines chemistry, Rats, Receptor, Muscarinic M4 metabolism, Structure-Activity Relationship, Brain metabolism, Muscarinic Antagonists pharmacokinetics, Muscarinic Antagonists pharmacology, Pyridazines pharmacokinetics, Pyridazines pharmacology, Receptor, Muscarinic M4 antagonists & inhibitors
- Abstract
This letter describes the synthesis and structure activity relationship (SAR) studies of structurally novel M
4 antagonists, based on a 3-(4-aryl/heteroarylsulfonyl)piperazin-1-yl)-6-(piperidin-1-yl)pyridazine core, identified from a high-throughput screening campaign. A multi-dimensional optimization effort enhanced potency at human M4 (hM4 IC50 s<200nM), with only moderate species differences noted, and with enantioselective inhibition. Moreover, CNS penetration proved attractive for this series (rat brain:plasma Kp =2.1, Kp,uu =1.1). Despite the absence of the prototypical mAChR antagonist basic or quaternary amine moiety, this series displayed pan-muscarinic antagonist activity across M1-5 (with 9- to 16-fold functional selectivity at best). This series further expands the chemical diversity of mAChR antagonists., (Copyright © 2017 Elsevier Ltd. All rights reserved.)- Published
- 2017
- Full Text
- View/download PDF
44. Are healthcare workers ready for Ebola? An assessment of their knowledge and attitude in a referral hospital in South India.
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Ahmad A, Khan MU, Jamshed SQ, Kumar BD, Kumar GS, Reddy PG, and Ajmera S
- Subjects
- Adult, Cross-Sectional Studies, Female, Hemorrhagic Fever, Ebola prevention & control, Hospitals, Public, Humans, India, Male, Middle Aged, Surveys and Questionnaires, Young Adult, Attitude of Health Personnel, Health Knowledge, Attitudes, Practice, Health Personnel, Hemorrhagic Fever, Ebola diagnosis, Hemorrhagic Fever, Ebola therapy, Professional Competence
- Abstract
Introduction: The World Health Organization (WHO) declared the Ebola virus disease (EVD) epidemic to be a public health emergency of international concern. Healthcare workers (HCWs) are at the highest risk of infection, as they may come into contact with patients' blood or fluids. This study was conducted to assess knowledge and attitudes of HCWs towards EVD in India., Methodology: A descriptive, cross-sectional study was conducted in a multispecialty public sector referral hospital of Telangana, India. Knowledge and attitude of HCWs were evaluated using a pre-validated questionnaire. A sample of 278 participants was selected to participate in this study. The Chi-squared test was used to assess the relationship between attitudes and demographic characteristics. Logistic regression was used examine the association between knowledge and study variables., Results: Of 257 participants who responded (92.4% response rate), 157 (61.1%) were females. The majority of the respondents were physicians (n = 117, 45.5%). Radio and television were the major sources of information about EVD reported by participants (89%). Overall knowledge of HCWs was poor (mean knowledge score: 6.57 ± 2.57). Knowledge of physicians and experienced workers (≥ 10 years) was significantly higher than their respective groups. The overall attitude of the participants was positive (mean attitude score: 1.62 ± 0.57). Significant positive correlations between knowledge and attitude were observed., Conclusions: The findings indicate that participants lack basic understanding of EVD. We recommend future studies be conducted across India to identify and subsequently bridge the knowledge gaps among HCWs.
- Published
- 2016
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- View/download PDF
45. Discovery and optimization of a novel series of highly CNS penetrant M4 PAMs based on a 5,6-dimethyl-4-(piperidin-1-yl)thieno[2,3-d]pyrimidine core.
- Author
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Wood MR, Noetzel MJ, Engers JL, Bollinger KA, Melancon BJ, Tarr JC, Han C, West M, Gregro AR, Lamsal A, Chang S, Ajmera S, Smith E, Chase P, Hodder PS, Bubser M, Jones CK, Hopkins CR, Emmitte KA, Niswender CM, Wood MW, Duggan ME, Conn PJ, Bridges TM, and Lindsley CW
- Subjects
- Allosteric Regulation, Animals, Brain drug effects, Brain metabolism, Humans, Microsomes, Liver metabolism, Piperidines chemical synthesis, Piperidines metabolism, Pyrimidines chemical synthesis, Pyrimidines metabolism, Quinazolines chemical synthesis, Quinazolines metabolism, Rats, Receptor, Muscarinic M4 agonists, Receptor, Muscarinic M4 antagonists & inhibitors, Structure-Activity Relationship, Thiophenes chemical synthesis, Thiophenes metabolism, Piperidines pharmacology, Pyrimidines pharmacology, Quinazolines pharmacology, Receptor, Muscarinic M4 metabolism, Thiophenes pharmacology
- Abstract
This Letter describes the chemical optimization of a novel series of M4 positive allosteric modulators (PAMs) based on a 5,6-dimethyl-4-(piperidin-1-yl)thieno[2,3-d]pyrimidine core, identified from an MLPCN functional high-throughput screen. The HTS hit was potent and selective, but not CNS penetrant. Potency was maintained, while CNS penetration was improved (rat brain:plasma Kp=0.74), within the original core after several rounds of optimization; however, the thieno[2,3-d]pyrimidine core was subject to extensive oxidative metabolism. Ultimately, we identified a 6-fluoroquinazoline core replacement that afforded good M4 PAM potency, muscarinic receptor subtype selectivity and CNS penetration (rat brain:plasma Kp>10). Moreover, this campaign provided fundamentally distinct M4 PAM chemotypes, greatly expanding the available structural diversity for this exciting CNS target., (Copyright © 2016 Elsevier Ltd. All rights reserved.)
- Published
- 2016
- Full Text
- View/download PDF
46. Volumetric pulp changes after orthodontic treatment determined by cone-beam computed tomography.
- Author
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Venkatesh S, Ajmera S, and Ganeshkar SV
- Subjects
- Adolescent, Case-Control Studies, Cuspid diagnostic imaging, Female, Humans, Image Processing, Computer-Assisted methods, Imaging, Three-Dimensional methods, Incisor diagnostic imaging, Male, Orthodontic Space Closure instrumentation, Cone-Beam Computed Tomography methods, Dental Pulp diagnostic imaging, Dental Pulp Cavity diagnostic imaging, Orthodontic Space Closure methods
- Abstract
Introduction: The purpose of this study was to observe and evaluate 3-dimensional pulp cavity changes during orthodontic treatment., Methods: Eighty-seven patients formed the study sample and were divided into an experimental group (48 patients) and a control group (39 patients). Cone-beam computed tomographic (CBCT) records were obtained before the start of the treatment (T0) and after space closure for the experimental group, whereas for the control group CBCT images were obtained approximately 17-18 months (T1) after obtaining the first image (T0). CBCT data were reconstructed with surface and volume rendering software (Mimics; Materialise, Leuven, Belgium), and the volumetric images were modified to display the teeth from various orientations. Six anterior teeth were segmented and their pulps isolated. Paired t test was used to check for statistical significance., Results: The difference in the pulp volume was statistically significant at P < .05 for all the anterior teeth in the experimental group and at P < .05 for the right canine, P < .05 for the right and left lateral incisors, and P < .05 for the left central in the control group., Conclusions: Orthodontic treatment in the experimental group produced a significant decrease in the size of the pulp, which was statistically significant., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)
- Published
- 2014
- Full Text
- View/download PDF
47. Volumetric evaluation of root resorption during orthodontic treatment.
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Ajmera S, Shivanand Venkatesh, and Ganeshkar SV
- Subjects
- Adolescent, Cuspid diagnostic imaging, Female, Follow-Up Studies, Humans, Image Processing, Computer-Assisted methods, Imaging, Three-Dimensional methods, Incisor diagnostic imaging, Male, Orthodontic Space Closure methods, Pilot Projects, Tooth Apex diagnostic imaging, Tooth Movement Techniques methods, Tooth Root diagnostic imaging, Cone-Beam Computed Tomography methods, Root Resorption diagnostic imaging, Tooth Movement Techniques adverse effects
- Published
- 2014
48. Pregnancy in rudimentary horn of uterus.
- Author
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Kulkarni K and Ajmera S
- Subjects
- Abdominal Pain etiology, Adult, Female, Humans, Pregnancy, Pregnancy, Ectopic diagnostic imaging, Ultrasonography, Young Adult, Pregnancy, Ectopic surgery, Uterine Rupture etiology, Uterus abnormalities
- Abstract
A 20-year-old primigravida with 3 months amenorrhea presented with complaints of acute abdominal pain. Her vital systemic parameters were stable. On vaginal examination, the patient was provisionally diagnosed of right cornual ectopic pregnancy, which was confirmed sonographically, and taken up for surgery. There was moderate hemoperitoneum and rupture of right horn of uterus with products protruding. The rudimentary horn was excised. The patient was discharged and advised contraception and follow-up.
- Published
- 2013
49. Synthesis and biological activity of 5-fluoro-2',3'-dideoxy-3'-fluorouridine and its 5'-phosphate.
- Author
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Ajmera S, Bapat AR, Danenberg K, and Danenberg PV
- Subjects
- Animals, Cell Division drug effects, Deoxyuracil Nucleotides toxicity, Dideoxynucleotides, Floxuridine chemical synthesis, Floxuridine toxicity, Indicators and Reagents, Kinetics, Leukemia L1210 physiopathology, Lung Neoplasms enzymology, Mice, Deoxyuracil Nucleotides chemical synthesis, Dideoxynucleosides, Floxuridine analogs & derivatives, Methyltransferases antagonists & inhibitors, Pentosyltransferases antagonists & inhibitors, Thymidine Phosphorylase antagonists & inhibitors, Thymidylate Synthase antagonists & inhibitors
- Abstract
5-Fluoro-2',3'-dideoxy-3'-fluorouridine (3'-FFdUrd) and 5-fluoro-2',3'-dideoxy-3'-fluorouridine 5'-phosphate (3'-FFdUMP) have been synthesized, and their interactions with thymidine (dThd) phosphorylase and thymidylate (dTMP) synthetase, respectively, have been examined. 3'-FFdUrd is not a substrate for dThd phosphorylase, but is a weak, noncompetitive inhibitor (Ki = 1.7 mM). 3'-FFdUMP inhibits dTMP synthetase competitively with deoxyuridylate (Ki = 0.13 mM) when both the substrate and inhibitor are present simultaneously. However, in the presence of 5,10-methylenetetrahydrofolate, the inhibition increases with time in a first-order manner (konobsd = 0.029 s-1). A complex is formed between [6-3H]3'-FFdUMP and dTMP synthetase, which is isolable on nitrocellulose filters, and has a dissociation rate (koffobsd = 1.4 X 10(-2) min-1) similar to that of the potent inhibitor 5-fluoro-2'-deoxyuridylate (koffobsd = 1.3 X 10(-2) min-1) from its ternary complex with dTMP synthetase. These results are explained in terms of a two-stage model involving the initial formation of a reversible adsorption complex, followed by a slow conversion to a tight-binding catalytic complex.
- Published
- 1984
- Full Text
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50. Effects of incorporation of 6-thioguanine into SV40 DNA.
- Author
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Maybaum J, Bainnson AN, Roethel WM, Ajmera S, Iwaniec LM, TerBush DR, and Kroll JJ
- Subjects
- Animals, Cell Line, DNA, Viral drug effects, Kinetics, DNA Replication drug effects, DNA, Viral genetics, Simian virus 40 genetics, Thioguanine pharmacology
- Abstract
The antileukemic agent 6-thioguanine (TG) is thought to inhibit DNA synthesis as a result of its incorporation into DNA. In the present study we have examined the nature of this inhibition, using replication of SV40 viral DNA as a model system. Addition of TG to SV40-infected CV1P cells from 22 to 24 hr post infection causes a dose-dependent inhibition of viral DNA synthesis. This inhibition plateaus between 250 and 2500 microM TG, resulting in a maximum decrease of viral DNA synthesis of about 50%. Pulse-chase experiments showed no detectable slowing of elongation of nascent DNA chains, whereas measurement of the conversion of incorporated 3H-dThd into supercoiled viral DNA suggested that elongation might be slightly inhibited, but by no more than 20%. Since inhibition of elongation could not account for the total depression of DNA synthesis, we hypothesized that inhibition of initiation of DNA replication takes place. This hypothesis was tested by radioactively labeling newly synthesized viral DNA and then assessing the ability of these molecules to reenter the replicating pool by density labeling with bromodeoxyuridine. The fraction of TG-containing molecules able to re-initiate replication was decreased 15%, compared to control. This effect, which was dependent on the concentration of TG added to the medium, was closely correlated to the extent of TG incorporation into the viral genome. We concluded that a portion of SV40 viral DNA synthesis inhibited by TG is due to an effect on initiation, and hypothesized that this effect may be caused by the substitution of TG for guanine in critical recognition sequences at the origin of replication. We proceeded to test this hypothesis by constructing SV40 origin sequences containing TG and then measuring their ability to bind T-antigen in vitro. The necessary deoxynucleoside triphosphate, TdGTP, was obtained by chemical phosphorylation of thiodeoxyguanosine. In order to selectively place TG within the desired region, a plasmid containing the T-antigen binding sequences was linearized so as to place these sequences at one end of the molecule, and then digested briefly with exonuclease III. The excised strand was resynthesized by use of the Klenow fragment of DNA polymerase I along with various nucleotide mixtures. Although resynthesis with mixtures containing TdGTP in place of dGTP was impeded somewhat, it was possible to achieve complete resynthesis with this analog.(ABSTRACT TRUNCATED AT 400 WORDS)
- Published
- 1987
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