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: ["Disease", "Chemical"].

Please return the output as a JSON object of the format: {"Chemical" : ["Naloxone", ...], "Disease" : ["Hypotensive", ...]}. 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:

Absence of acute cerebral vasoconstriction after cocaine-associated subarachnoid hemorrhage. INTRODUCTION: Cocaine use has been associated with neurovascular complications, including arterial vasoconstriction and vasculitis. However, there are few studies of angiographic effects of cocaine on human cerebral arteries. Information on these effects could be obtained from angiograms of patients with cocaine-associated subarachnoid hemorrhage (SAH) who underwent angiography shortly after cocaine use. METHODS: We screened patients with SAH retrospectively and identified those with positive urine toxicology for cocaine or its metabolites. Quantitative arterial diameter measurements from angiograms of these patients were compared to measurements from control patients with SAH who were matched for factors known to influence arterial diameter. Qualitative comparisons of small artery changes also were made. RESULTS: Thirteen patients with positive cocaine toxicology were compared to 26 controls. There were no significant differences between groups in the mean diameters of the intradural internal carotid, sphenoidal segment of the middle cerebral, precommunicating segment of the anterior cerebral, or basilar arteries (p greater than 0.05 for all comparisons, unpaired t-tests). There also were no significant differences between groups when expressing diameters as the sum of the precommunicating segment of the anterior cerebral + sphenoidal segment of the middle cerebral + supraclinoid internal carotid artery + basilar artery divided by the diameter of the petrous internal carotid artery (p greater than 0.05, unpaired t-tests). Qualitative assessments showed two arterial irregularities in the distal vasculature in each group. CONCLUSION: No quantitative evidence for narrowing of large cerebral arteries or qualitative angiographic evidence for distal narrowing or vasculitis could be found in patients who underwent angiography after aneurysmal SAH associated with cocaine use.
{"Chemical": ["Cocaine", "cocaine"], "Disease": ["SAH", "subarachnoid hemorrhage", "neurovascular complications", "vasculitis", "aneurysmal"]}