Comparative Assessment of Severe Pediatric TBI Management between Developed and Developing Country Institutions

A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine.Traumatic Brain Injury (TBI) is an etiologically heterogeneous condition that represents a global public health issue with major socioeconomic impact. Evidence-based guidelines for pediatric TBI management exist, and were last updated by the Brain Trauma Foundation in 2012. There are, however, limitations and barriers to their implementation; one such are the differences in resource utilization and availability in developed versus developing countries. In this study, we performed a retrospective review of pediatric patients with severe TBI in two tertiary, pediatric hospitals in the United States and Colombia, comparing characteristics, management and outcomes.This item is part of the College of Medicine - Phoenix Scholarly Projects 2019 collection. For more information, contact the Phoenix Biomedical Campus Library at [email protected]

Microvascular Anastomosis Under 3D Exoscope or Endoscope Magnification: A Proof-Of-Concept Study

Background: Extracranial-intracranial bypass is a challenging procedure that requires special microsurgical skills and an operative microscope. The exoscope is a tool for neurosurgical visualization that provides view on a heads-up display similar to an endoscope, but positioned external to the operating field, like a microscope. The authors carried out a proof-of-concept study evaluating the feasibility and effectiveness of performing microvascular bypass using various new exoscopic tools. Methods: We evaluated microsurgical procedures using a three-dimensional (3D) endoscope, hands-free robotic automated positioning two-dimensional (2D) exoscope, and an ocular-free 3D exoscope, including surgical gauze knot tying, surgical glove cutting, placental vessel anastomoses, and rat vessel anastomoses. Image quality, effectiveness, and feasibility of each technique were compared among different visualization tools and to a standard operative microscope. Results: 3D endoscopy produced relatively unsatisfactory resolution imaging. It was shown to be sufficient for knot tying and anastomosis of a placental artery, but was not suitable for anastomosis in rats. The 2D exoscope provided higher resolution imaging, but was not adequate for all maneuvers because of lack of depth perception. The 3D exoscope was shown to be functional to complete all maneuvers because of its depth perception and higher resolution. Conclusion: Depth perception and high resolution at highest magnification are required for microvascular bypass procedures. Execution of standard microanastomosis techniques was unsuccessful using 2D imaging modalities because of depth-perception-related constraints. Microvascular anastomosis is feasible under 3D exoscopic visualization; however, at highest magnification, the depth perception is inferior to that provided by a standard operative microscope, which impedes the procedure

Severe Pediatric TBI Management in a Middle-Income Country and a High-Income Country: A Comparative Assessment of Two Centers.

Background: Traumatic brain injury (TBI) is a global public health issue with over 10 million deaths or hospitalizations each year. However, access to specialized care is dependent on institutional resources and public health policy. Phoenix Children's Hospital USA (PCH) and the Neiva University Hospital, Colombia (NUH) compared the management and outcomes of pediatric patients with severe TBI over 5 years to establish differences between outcomes of patients managed in countries of varying resources availability. Methods: We conducted a retrospective review of individuals between 0 and 17 years of age, with a diagnosis of severe TBI and admitted to PCH and NUH between 2010 and 2015. Data collected included Glasgow coma scores, intensive care unit monitoring, and Glasgow outcome scores. Pearson Chi-square, Fisher exact, T-test, or Wilcoxon-rank sum test was used to compare outcomes. Results: One hundred and one subjects met the inclusion criteria. NUH employed intracranial pressure monitoring less frequently than PCH (p = 0.000), but surgical decompression and subdural evacuation were higher at PCH (p = 0.031 and p = 0.003). Mortality rates were similar between the institutions (15% PCH, 17% NUH) as were functional outcomes (52% PCH, 54% NUH). Conclusions: Differences between centers included time to specialized care and utilization of monitoring. No significant differences were evidenced in survival and the overall functional outcomes

Characterizing Various Cup Proteins Involved in Lysosome Formation and Transport

Lysosomes are the main degradative organelles in eukaryotic cells and are essential for many cellular processes, including endocytosis, apoptosis, and autophagy. However, little is known about how they form. Endocytosed material is trafficked from early endosomes to late endosomes; materials destined for degradation are concentrated in structures that bud and separate from late endosomes, forming lysosomes. Acid hydrolases and other enzymes responsible for degradation are trafficked to these lysosomes to effect degradation. There are only two genes known to be essential for lysosome formation, rab-2 and cup-5 in Caenorhabditis elegans. Due to the complexity of lysosome formation, which includes budding, extension, and fission, we hypothesize that there are other genes involved in lysosome formation. A mutagenesis screen was conducted to identify different genes involved in lysosome formation. We used transgenic wild type C. elegans that secrete green fluorescent protein (GFP) from the body wall muscles into the body cavity of the worm; this GFP is endocytosed and degraded in lysosomes of scavenger cells called coelomocytes. We mutagenized these worms and identified mutants that had bright green coelomocytes indicative of defects in lysosome formation and/or function. We report our analysis of these new cup mutants and their possible functions in lysosomes

Plerixafor as a salvage mobilization strategy for haploidentical peripheral blood allogeneic stem cell transplantation

In allogeneic stem cell mobilization, peripheral blood stem cell mobilization with filgrastim can be considered standard of care. Poor mobilizers may be at risk for inadequate stem cell collection during apheresis. He we present a successful case of salvage plerixafor use with filgrastim in a haploidentical identical transplant patient.Paid by UA Open Access FundThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Plerixafor as a salvage mobilization strategy for haploidentical peripheral blood allogeneic stem cell transplantation

In allogeneic stem cell mobilization, peripheral blood stem cell mobilization with filgrastim can be considered standard of care. Poor mobilizers may be at risk for inadequate stem cell collection during apheresis. He we present a successful case of salvage plerixafor use with filgrastim in a haploidentical identical transplant patient.Paid by UA Open Access FundThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

MinION rapid sequencing: Review of potential applications in neurosurgery

BACKGROUND: Gene sequencing has played an integral role in the advancement and understanding of disease pathology and treatment. Although historically expensive and time consuming, new sequencing technologies improve our capability to obtain the genetic information in an accurate and timely manner. Within neurosurgery, gene sequencing is routinely used in the diagnosis and treatment of neurosurgical diseases, primarily for brain tumors. This paper reviews nanopore sequencing, an innovation utilized by MinION and outlines its potential use for neurosurgery. METHODS: A literature search was conducted for publications containing the keywords of Oxford MinION, nanopore sequencing, brain tumor, glioma, whole genome sequencing (WGS), epigenomics, molecular neuropathology, and next-generation sequencing (NGS). In total, 64 articles were selected and used for this review. RESULTS: The Oxford MinION nanopore sequencing technology has had successful applications within clinical microbiology, human genome sequencing, and cancer genotyping across multiple specialties. Technical details, methodology, and current use of MinION sequencing are discussed through the prism of potential applications to solve neurosurgery-related scientific and diagnostic questions. The MinION device has proven to provide rapid and accurate reads with longer read lengths when compared with NGS. For applications within neurosurgery, the MinION device is capable of providing critical diagnostic information for central nervous system (CNS) tumors within a single day. CONCLUSIONS: MinION provides rapid and accurate gene sequencing with better affordability and convenience compared with current NGS methods. Widespread success of the MinION nanopore sequencing technology in providing accurate, rapid, and convenient gene sequencing suggests a promising future within research laboratories and to improve care for neurosurgical patients

Regulators of Lysosome Function and Dynamics in Caenorhabditis elegans

Lysosomes, the major membrane-bound degradative organelles, have a multitude of functions in eukaryotic cells. Lysosomes are the terminal compartments in the endocytic pathway, though they display highly dynamic behaviors, fusing with each other and with late endosomes in the endocytic pathway, and with the plasma membrane during regulated exocytosis and for wound repair. After fusing with late endosomes, lysosomes are reformed from the resulting hybrid organelles through a process that involves budding of a nascent lysosome, extension of the nascent lysosome from the hybrid organelle, while remaining connected by a membrane bridge, and scission of the membrane bridge to release the newly formed lysosome. The newly formed lysosomes undergo cycles of homotypic fusion and fission reactions to form mature lysosomes. In this study, we used a forward genetic screen in Caenorhabditis elegans to identify six regulators of lysosome biology. We show that these proteins function in different steps of lysosome biology, regulating lysosome formation, lysosome fusion, and lysosome degradation

Molecular Imaging of Glucose Metabolism for Intraoperative Fluorescence Guidance During Glioma Surgery

Purpose: This study evaluated the use of molecular imaging of fluorescent glucose analog 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG) as a discriminatory marker for intraoperative tumor border identification in a murine glioma model. Procedures: 2-NBDG was assessed in GL261 and U251 orthotopic tumor-bearing mice. Intraoperative fluorescence of topical and intravenous 2-NBDG in normal and tumor regions was assessed with an operating microscope, handheld confocal laser scanning endomicroscope (CLE), and benchtop confocal laser scanning microscope (LSM). Additionally, 2-NBDG fluorescence in tumors was compared with 5-aminolevulinic acid–induced protoporphyrin IX fluorescence. Results: Intravenously administered 2-NBDG was detectable in brain tumor and absent in contralateral normal brain parenchyma on wide-field operating microscope imaging. Intraoperative and benchtop CLE showed preferential 2-NBDG accumulation in the cytoplasm of glioma cells (mean [SD] tumor-to-background ratio of 2.76 [0.43]). Topically administered 2-NBDG did not create sufficient tumor-background contrast for wide-field operating microscope imaging or under benchtop LSM (mean [SD] tumor-to-background ratio 1.42 [0.72]). However, topical 2-NBDG did create sufficient contrast to evaluate cellular tissue architecture and differentiate tumor cells from normal brain parenchyma. Protoporphyrin IX imaging resulted in a more specific delineation of gross tumor margins than intravenous or topical 2-NBDG and a significantly higher tumor-to-normal-brain fluorescence intensity ratio. Conclusion: After intravenous administration, 2-NBDG selectively accumulated in the experimental brain tumors and provided bright contrast under wide-field fluorescence imaging with a clinical-grade operating microscope. Topical 2-NBDG was able to create a sufficient contrast to differentiate tumor from normal brain cells on the basis of visualization of cellular architecture with CLE. 5-Aminolevulinic acid demonstrated superior specificity in outlining tumor margins and significantly higher tumor background contrast. Given the nontoxicity of 2-NBDG, its use as a topical molecular marker for noninvasive in vivo intraoperative microscopy is encouraging and warrants further clinical evaluation

Molecular Imaging of Glucose Metabolism for Intraoperative Fluorescence Guidance During Glioma Surgery.

PURPOSE: This study evaluated the use of molecular imaging of fluorescent glucose analog 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG) as a discriminatory marker for intraoperative tumor border identification in a murine glioma model. PROCEDURES: 2-NBDG was assessed in GL261 and U251 orthotopic tumor-bearing mice. Intraoperative fluorescence of topical and intravenous 2-NBDG in normal and tumor regions was assessed with an operating microscope, handheld confocal laser scanning endomicroscope (CLE), and benchtop confocal laser scanning microscope (LSM). Additionally, 2-NBDG fluorescence in tumors was compared with 5-aminolevulinic acid-induced protoporphyrin IX fluorescence. RESULTS: Intravenously administered 2-NBDG was detectable in brain tumor and absent in contralateral normal brain parenchyma on wide-field operating microscope imaging. Intraoperative and benchtop CLE showed preferential 2-NBDG accumulation in the cytoplasm of glioma cells (mean [SD] tumor-to-background ratio of 2.76 [0.43]). Topically administered 2-NBDG did not create sufficient tumor-background contrast for wide-field operating microscope imaging or under benchtop LSM (mean [SD] tumor-to-background ratio 1.42 [0.72]). However, topical 2-NBDG did create sufficient contrast to evaluate cellular tissue architecture and differentiate tumor cells from normal brain parenchyma. Protoporphyrin IX imaging resulted in a more specific delineation of gross tumor margins than intravenous or topical 2-NBDG and a significantly higher tumor-to-normal-brain fluorescence intensity ratio. CONCLUSION: After intravenous administration, 2-NBDG selectively accumulated in the experimental brain tumors and provided bright contrast under wide-field fluorescence imaging with a clinical-grade operating microscope. Topical 2-NBDG was able to create a sufficient contrast to differentiate tumor from normal brain cells on the basis of visualization of cellular architecture with CLE. 5-Aminolevulinic acid demonstrated superior specificity in outlining tumor margins and significantly higher tumor background contrast. Given the nontoxicity of 2-NBDG, its use as a topical molecular marker for noninvasive in vivo intraoperative microscopy is encouraging and warrants further clinical evaluation