The use, in diabetic rats and monkeys, of artificial capillary units containing cultured islets of Langerhans (artificial endocrine pancreas).

A unit was constructed that consisted of a core of hollow fibers through which low-molecular-weight substances, such as glucose and insulin, could pass freely but were impermeable to high-molecular-weight proteins, such as antibodies. Islets of Langerhans from normal rats were planted in the space surrounding the fibers, and either blood or nutrient medium was circulated through the fibers themselves. In experiments with animals, the units were attached to the vascular system of diabetic rats and monkeys.

Large-scale cultivation of cells in closed systems: stationary and moving.

Basic metabolic differences have been observed for cell cultures propagated in conventional stationary or rotating systems. The influence of these differences on virus characteristics is largely unknown but could be significant in maintenance of genetic stability of attenuated strains. Current requirements for good manufacturing procedures prompted the development of closed systems for both stationary and rotating cultures.

Improved cell dispersal method by low-temperature incubation of tissue in a trypsin-citrate solution.

Tissues soaked at low temperature in a trypsin-citrate solution, washed to remove enzymes, and disrupted by rapid mechanical vibrations gave yields of viable cells 1.6 to 5 times those from conventional procedures.

Effects of Tween 80 and freon 113 on measles virus.

Measles vaccines were prepared from the same virus fluids by inactivation with formaldehyde or by extraction with ether, ethyl acetate, or Freon 113 in the presence of Tween 80. Tests of antigenic potency, based on antibody levels in guinea pigs, showed that the formaldehyde-inactivated vaccines were more potent than the solvent-inactivated preparations and had the additional advantage of long shelf life. Residual Tween 80 in the solvent-extracted vaccines resulted in marked loss of immunogenic potency without significant loss of hemagglutinating activity.