MidOcean Partners, a middle-market private equity firm, has acquired professional staffing services provider All Systems Holding (System One). Prospect Capital provided a $32 million senior secured loan to support the acquisition. Based in Pittsburgh, System One provides outsourced staffing services to the energy, utility, information technology and legal sectors. CEO Troy Gregory formed the company in 2008 through a management buyout of Hudson Highland Group's engineering staffing business. Veronis Suhler Stevenson made a growth investment in the company in October 2010.