Updated from 2:36 p.m.

Shares of Nephros ( NEP) jumped 94% after the company said its OLpur HD190 high-flux filter received U.S. marketing clearance for its treatment of kidney disease. "This approval marks the beginning of our move into the U.S., and we believe this approval should also simplify and accelerate the 510(k) approval process for our MD190 and H2H products," said CEO Norman Barta. The stock closed up $1.96 to $4.04.

Shares of American Shared Hospital Services ( AMS) rose 1.9% after the medical services provider's board boosted its dividend by 5.6%, to 4.75 cents. The dividend will be payable on July 15 to shareholders of record July 1. The stock was up 12 cents to $6.28.

Shares of Vertex Pharmaceuticals ( VRTX) rose 9.7% after it and Merck ( MRK) started an additional Phase I clinical study with VX-680, a small molecule inhibitor of Aurora kinases. The two-part, open-label study is designed to evaluate the safety and tolerability of the drug when administered over a five-day treatment cycle in patients with hematologic cancers. Merck and Vertex now have three clinical studies underway with VX-680 in cancer. Vertex finished up $1.35 to $15.30, while Merck closed up 22 cents to $32.22.

Shares of Novo Nordisk ( NVO) rose 2.9% after the Food and Drug Administration cleared the use of Levemir for the treatment of type 1 and type 2 diabetes. Levemir is a long-lasting form of insulin that provides up to 24-hour action and causes little weight change, according to the company. The company also said that a New Drug Application for Levemir for pediatric indication is currently under review by the FDA. The stock finished up $1.49 to $51.75.

Other health stocks on the move were Abbott Labs ( ABT), up 35 cents to $49.43; Biogen Idec ( BIIB), down 31 cents to $35.94; Elan ( ELN), down 8 cents to $6.94; Pfizer ( PFE), up 18 cents to $28.78; and Nitromed ( NTMD), up 32 cents to $19.73.