Note 4 - Property and Equipment, Net - Summary of Property and Equipment (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Property and equipment		$ 1,090,000	$ 971,000
Accumulated depreciation		(827,000)	(712,000)
Property and equipment, net	0	263,000	259,000
Computer Equipment and Software [Member]
Property and equipment		211,000	192,000
Furniture and Fixtures [Member]
Property and equipment		365,000	302,000
Laboratory Equipment [Member]
Property and equipment		$ 514,000	$ 477,000

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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