Note 4 - Property and Equipment
 12 Months Ended
Dec. 31, 2014
Property, Plant and Equipment [Abstract]  
Property, Plant and Equipment Disclosure [Text Block]
4. Property and Equipment

Property and equipment consist of the following:

   
Useful Life
(Years)
   
December 31, 2013
   
December 31, 2014
 
Office furniture and equipment
  7     $ 528,732     $ 458,380  
Computer equipment
  3       712,609       788,563  
Computer software
  3       540,809       629,948  
Laboratory equipment
  7       5,264,952       5,345,786  
Leasehold improvements
  5       2,643,023       2,646,891  
Asset related to facility lease obligation
          —       3,380,223  
Construction of manufacturing facility in progress
          76,010       500,093  
                       
            9,766,135       13,749,884  
Less: Accumulated depreciation and amortization
          (8,164,032 )     (8,236,329 )
                       
Property and equipment, net
        $ 1,602,103     $ 5,513,555  

Assets related to the Company’s facility lease obligation and construction of manufacturing facility in progress were primarily recognized during the year ended December 31, 2014 due to the Company deemed to be the accounting owner of the facility during its construction period under build-to-suite lease accounting (see Note 16).

Depreciation and amortization expense was as follows:

Year ended December 31, 2012
  $ 505,261  
Year ended December 31, 2013
    611,421  
Year ended December 31, 2014
    566,117