Note 9 - Warrants to Purchase Common Stock (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Options Outstanding	67,434	82,336
Options Granted	1,683	13,159
Options Expired	(1,238)	(28,061)
Options Outstanding	67,879	67,434
Options exercisable at End	66,270
Outstanding at Beginning, Weighted-Average Exercise Price	$ 26.26	$ 42.42
Weighted- Average Exercise Price, Granted	2.08	21.21
Weighted- Average Exercise Price, Expired	18.79	46.46
Outstanding at Ending, Weighted-Average Exercise Price	21.40	$ 26.26
Weighted- Average exercisable at End	$ 36.70
Weighted- Average Remaining Contractual Term, Beginning balance	8 years 1 month 10 days	9 years 1 month 2 days
Weighted- Average Remaining Contractual Term, Granted	9 years 2 months 5 days	9 years 1 month 10 days
Weighted- Average Remaining Contractual Term, Ending Balance	7 years 2 months 1 day	8 years 1 month 10 days
Weighted- Average Remaining Contractual Term, exercisable at End	6 years 9 months 15 days
Warrant [Member]
Options Outstanding	171,369	103,823
Options Granted	5,233	70,753
Options Expired	(98,140)	(3,207)
Options Outstanding	78,462	171,369
Options exercisable at End	78,462
Outstanding at Beginning, Weighted-Average Exercise Price	$ 70.70	$ 101
Weighted- Average Exercise Price, Granted	16.36	29.29
Weighted- Average Exercise Price, Expired	100.81	303
Outstanding at Ending, Weighted-Average Exercise Price	29.55	$ 70.70
Weighted- Average exercisable at End	$ 29.55
Weighted- Average Remaining Contractual Term, Beginning balance	2 years 15 days	1 year 4 months 10 days
Weighted- Average Remaining Contractual Term, Granted	2 years 8 months 1 day	4 years 4 months 28 days
Weighted- Average Remaining Contractual Term, Ending Balance	3 years 5 months 5 days	2 years 15 days
Weighted- Average Remaining Contractual Term, exercisable at End	3 years 5 months 5 days