Abstract: A polypeptide transforming growth factor found in porcine platelets, having activity in the TGF-.beta. assay and a molecular weight of about 25 kDa. The factor is a heterodimer, one chain of which has an N-terminal sequence very different from human platelet TGF-.beta., and the other chain of which has an N-terminal sequence identical to that of human platelet TGF-.beta.. The factor is purified using gel filtration and reverse phase HPLC.

Abstract: A stirrer apparatus for stirring culture medium has a flask with a lid, a floating magnetic stirrer responsive to a moving magnetic field, and a moving field generator including poles and coils. A guide system is provided for the stirrer including a rod which extend upwardly from the stirrer and a tube which extends through the lid, the rod extending into and being rotatable in the tube; the tube has a closed upper end. A stirrer apparatus having a floating magnetic stirrer with a central, downwardly extending, closed end guide tube, and lid with a guide rod extending into the guide tube. The stirrer included one or more continuous impellers extending across the rotational axis of the stirrer; in one embodiment, the impeller is provided by a bar magnet or magnets beneath a float and in another embodiment a bar magnet is within the float, and the impeller is a continuous blade.

Abstract: A magnetic stirrer apparatus for culture medium and other liquids comprises a flask having a floating stirrer in it; a driving guide rod extends downwardly into the flask, and has a sliding drive connection with the floating stirrer. The driving guide rod is suspended from a bearing on the underside of the flask closure, and carries a driven magnet, which is magnetically coupled with a motor-driven magnet on the outside of the closure.

Abstract: A stirrer for stirring liquid in a flask comprises a magnetically attractable member formed by or supported by a buoyancy chamber, the stirrer having less density than the liquid to be stirred; the stirrer may include an impeller. A method of stirring a liquid comprising introducing liquid and a buoyant, magnetically attractable stirrer into a vessel, and causing a rotating magnetic field to rotate the stirrer.

Abstract: A magnetic stirrer apparatus includes a vessel for liquid and a floating stirrer. The floating stirrer is rotated by a magnet driven by a magnetic field generator laterally of the vessel, and a guide rod through the floating stirrer restricts its movement to rotary movement and substantially vertical movement with change in the liquid level. The magnetic field generator is operative at any level of the liquid in the vessel.