Plasmodium falciparum growth in deep culture.

Culture conditions have been developed which enable the asexual erythrocytic stage of Plasmodium falciparum to be grown in deep culture and produce parasite yields comparable to shallow stationary culture. The major benefit of deep culture is that large volumes of parasites can be grown in a single vessel (up to 8 litres) and thus advantage can be taken of semi-automatic approaches to medium replacement. Other benefits are that large quantities of viable parasites can be matured without multiple medium replacements and synchronized parasite culture can be maintained easily over an extended time.

A device for the nondestructive decontamination of large volumes of infected egg waste.

A device for the decontamination of large numbers of infected eggs which remain as by-products of vaccine production is described. Homogenates of infected eggs were heated to 60 degrees C and maintained at that temperature for 3 h in a specially constructed recirculation tank. The infectivity of all detectable influenza viruses and more than 99% of the bacteria associated with the homogenates was destroyed by this procedure. Eggshell material was separated from the proteins present in the homogenate at the end of the heating cycle by means of a cyclone separator. The proportions of all the amino acids, except cystine, in the proteins remaining in the suspension after the heating cycle were similar to that normally present in whole embryos.

Controlled formaldehyde fumigation system.

A comparative study of formaldehyde (HCHO) fumigation was carried out by controlled vaporization, using an electric vapor generator, and by the Formalin-permanganate method. Determination of vapor levels as well as bactericidal action showed the generator to be more effective. Maximum achievable fumigant levels were temperature dependent and related to the equilibrium vapor concentration of HCHO. At a room temperature of 21 degrees C, vaporization of more than 2,000 micrograms of HCHO per liter resulted in conversion of HCHO to paraformaldehyde, which condensed on surfaces and contributed to prolonged residual vapor levels. An electronic monitor is described which is capable of detecting HCHO levels as low as 10 microgram/liter and can be used to monitor the complete fumigation process.