Abstract: Betulin and dihydrobetulin acyl derivatives according to the present invention have been found to have potent anti-HIV activity. The compounds of the present invention have the following formulae: or pharmaceutically acceptable salts thereof, wherein R1 is a C2-C20 substituted or unsubstituted carboxyacyl, R2 is a C2-C20 substituted or unsubstituted carboxyacyl; and R3 is hydrogen, halogen, amino, optionally substituted mono- or di-alkylamino, or —OR4, where R4 is hydrogen, C1-4 alkanoyl, benzoyl, or C2-C20 substituted or unsubstituted carboxyacyl; wherein the dashed line represents an optional double bond between C20 and C29.

Abstract: An endotoxin inactivator is isolated from human plasma by anion exchange (DEAE-Sephadex), dye-affinity (Cibracron Blue-Sepharose), and adsorption (on hydroxyapatite) chromatography. The endotoxin inactivator, isolated in essentially pure form, may be used to depyrogenate clinical blood products.

Abstract: An apparatus for obtaining highly uniform thin rectangular strips from solid support sheets, such as antigen-laden nitrocellulose sheets used in immunoassays, is disclosed which includes a rectangular-shaped base plate having longitudinal parallel grooves, a hinged rectangular-shaped top plate having longitudinal parallel slots and a fastening element to secure the top plate to the base plate so that the longitudinal slots of the top plate register precisely above the longitudinal grooves of the base plate. The apparatus also includes cutting blades, a holder for holding the cutting blades, a sliding mechanism to move the holder and the blades through the longitudinal parallel slots, solid support sheet and across the longitudinal parallel grooves, and hold down bars and trackways to guide the cutting blades through the longitudinal parallel slots and across the longitudinal parallel grooves.

Abstract: An endotoxin inactivator is isolated from human plasma by anion exchange (DEAE-Sephadex), dye-affinity (Cibracron Blue-Sepharose), and adsorption (on hydroxyapatite) chromatography. The endotoxin inactivator, isolated in essentially pure form, may be used to depyrogenate clinical blood products.

Abstract: An enclosed device and method for controlled freezing of cell cultures, especially eucaryotic cell cultures, contained in cell culture vials by means of a conventional freezer includes a container and top, a supporting grid and supporting grid base within the container for supporting the culture vials and a compatible liquid refrigerant in a volume of at least fifteen times the culture volume and at a level to totally immerse all of the cultures to be frozen. Compatible liquid refrigerants include the straight chain aliphatic alcohols, preferrably ethanol and methanol.

Abstract: An enclosed device and method for controlled freezing of cell cultures, especially eucaryotic cell cultures, contained in cell culture vials by means of a conventional freezer includes a container and top, a supporting grid and supporting grid base within the container for supporting the cultire vials and a compatible liquid refrigerant in a volume of at least fifteen times the culture volume and at a level to totally immerse all of the cultures to be frozen. Compatible liquid refrigerants include the straight chain aliphatic alcohols, preferrably ethanol and methanol.