You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["HealthCareActivity", "InjuryOrPoisoning", "BodySubstance", "IntellectualProduct", "AnatomicalStructure", "SpatialConcept", "Chemical", "Bacterium", "MedicalDevice", "Organization", "BiomedicalOccupationOrDiscipline", "Finding", "BiologicFunction", "Virus", "ResearchActivity", "ClinicalAttribute", "PopulationGroup", "Eukaryote", "BodySystem", "Food", "ProfessionalOrOccupationalGroup"].

Please return the output as a JSON object of the format: {"Virus": ["HIV", ...], "Bacterium": ["MRSA", ...], "AnatomicalStructure": ["Lung", ...], "BodySystem": ["CNS", ...], "BodySubstance": ["Serum", ...], "Finding": ["Headache", ...], "InjuryOrPoisoning": ["Fracture", ...], "BiologicFunction": ["Death", ...], "HealthCareActivity": ["Biopsy", ...], "ResearchActivity": ["Clinical trial", ...], "MedicalDevice": ["Lenses", ...], "SpatialConcept": ["Camps", ...], "BiomedicalOccupationOrDiscipline": ["Forensic medicine", ...], "Organization": ["WHO", ...], "ProfessionalOrOccupationalGroup": ["Provider", ...], "PopulationGroup": ["Swimmers", ...], "Chemical": ["Gold", ...], "Food": ["Rice", ...], "IntellectualProduct": ["RPAM", ...], "ClinicalAttribute": ["Biomarker", ...], "Eukaryote": ["Dogs", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Histopathology of the filum terminale in children with and without tethered cord syndrome with attention to the elastic tissue within the filum To compare histologically transected fila from pediatric patients with tethered cord syndrome (TCS), with and without a low conus, with controls, focusing on collagenous and elastic tissue. Thirty fila from patients with TCS, including 5 where minimal cautery was used prior to filum section, were compared with fila from 27 pediatric cadavers without TCS (controls). Sections of fila were stained with H&E, Masson trichrome and Verhoeff von Gieson elastic stains, and 7 with Gordon and Sweet's reticulin stain. Fila from controls showed loose fibrous connective tissue (FCT) with thin and evenly dispersed elastic fibers (EFs). Reticulin fibers (RFs) were seen in blood vessel walls and nerve twigs. Fat was identified microscopically in 2 fila. All fila from patients with TCS had dense FCT. The EFs were in normal numbers in 17, and focally or diffusely decreased in 13. All 25 patients where the fila were cauterized during resection had thick and coiled EFs. Coiling was not seen when minimal cautery was applied. RFs were seen in blood vessel walls and nerve twigs. Fat was identified in 19 patients. Findings were similar, whether the conus termination was normal or low. The fila of all patients with TCS, whether or not the conus was low, showed abnormal FCT. EFs were decreased in 48 % of patients; however, there were thick and coiled EFs in all patients. Coiling of EFs, initially thought to be an abnormality in patients, is considered most likely to be a result of cautery (i.e., artifactual / iatrogenic coiling).
{"AnatomicalStructure": ["blood vessel walls", "dense FCT", "fibrous connective tissue", "nerve", "fila", "Fila", "cadavers", "conus", "filum", "filum terminale", "FCT", "elastic tissue", "EFs", "collagenous", "elastic fibers"], "Bacterium": [], "BiologicFunction": ["tethered cord syndrome", "TCS"], "BiomedicalOccupationOrDiscipline": ["Histopathology"], "BodySubstance": [], "BodySystem": [], "Chemical": ["Fat", "RFs", "Reticulin fibers"], "ClinicalAttribute": [], "Eukaryote": [], "Finding": ["Findings", "abnormality", "abnormal"], "Food": [], "HealthCareActivity": ["Verhoeff von Gieson elastic stains", "cautery", "Masson trichrome", "cauterized", "section", "Gordon and Sweet\u0027s reticulin stain", "resection", "stained", "H\u0026E"], "InjuryOrPoisoning": [], "IntellectualProduct": [], "MedicalDevice": [], "Organization": [], "PopulationGroup": [], "ProfessionalOrOccupationalGroup": [], "ResearchActivity": [], "SpatialConcept": ["coiling", "Coiling", "focally", "low", "coiled"], "Virus": []}