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SummaryA large plaque variant of Sindbis virus was obtained by repeatedly cloning after serial passage 50 times in chorioallantoic membrane in tissue culture. This virus has a high infectious titer in CEF cells as well as suckling mice. On the other hand, a small plaque of Sindbis virus obtained by the same method above using chick embryo brains instead of chorioallantoic membrane, grows to somewhat lower titer than that of the large plaque variant, and is not sensitive to agar inhibitors.

Summary An infectious RNA was extracted from mouse brains infected with Theiler's mouse encephalomyelitis virus (GDVII strain). The yield of infectious RNA from heated virus was compared to that from u.v. irradiated virus material and at the same time, the stability of the hemagglutinating activity of the virus with respect to heat and u.v. irradiation was investigated. The results obtained suggest that inactivation of virus by heat is due, in large part, to denaturation of virus protein whereas inactivation by u.v. irradiation is due to destruction of viral RNA without denaturation of protein.

It is well known that the selective media for pleuropneumonia-like organisms and mycoplasma, i. e., PPLO agar and broth contain thallium acetate and penicillin in order to inhibit or suppress Gram-negative bacteria and Gram-positive bacteria, respectively. There are a lot of reports concerning inhibition of bacteria by penicillin, but a few works about the effect of thallium acetate on suppression of the growth of bacteria. This communication is to describe the effect of thallium acetate on the growth and morphological changes of bacteria which grow well on agar-agar medium.

Recently, transmission of Myc, leprae to mice which had been established by Shepard, have been employed for immunological and chemotherapeutic studies. In these experiments, effects of drugs tested are estimated by reduction of solid form in bacilli stained under the definite condition. In the case of Myc. lepraemurium, stained properties of the bacilli are very variable and subtle depending upon staining conditions. The present paper describes factors influencing morphological index of acid fast bacilli, in order to contribute to the studies on a relationship between staining quality and vitalities of Myc. leprae and lepraemurium.

SummaryThe growth of type A influenza virus in tissue cultures of chorioallantoic membrane was inhibited by M. pneumoniae when the latter was inoculated 2 days before the virus. However, this inhibition was reversed by addition of l-arginine. On the other hand, the growth of mycoplasma was stimulated by influenza virus infection, especially in the culture medium containing arginine. In the case of the JE virus growing in PS cells, the virus was not affected by M. orale infection. On the contrary, the growth patterns of M. orale were modified by JE virus infection, particularly when the virus was inoculated 1 or 2 days before mycoplasma infection. However, no modification of growth pattern of M. orale was observed when the virus was inoculated after mycoplasma infection.

Summary Optimal conditions for obtaining infectious RNA from mouse brains infected with JBE virus were three phenol extractions followed by more than three ether treatments for removing the excess phenol contained in the aqueous phase. Maximum number of plaques in chick embryo cell monolayers were formed either when the RNA preparation was diluted in 1.0 M NaCl solution, or when the cell layer was washed with 1.0 M NaCl solution prior to seeding with the RNA preparation. RNA required approximately 5 to 10 minutes to initiate maximum infection of chick embryo cell cultures. RNA was quite stable to acid compared to intact JBE virus, and was about as sensitive to heat as intact virus. Ether, chloroform, and n-butanol had no influence on the infectivity of JBE RNA, whereas the intact virus was promptly inactivated by these reagents. RNA was much more resistant to sodium desoxycholate than was intact virus.

Common origin of the Val30Met mutation responsible for the amyloidogenic transthyretin type of familial amyloidotic polyneuropathy.

In the feasibility study of a FBR cycle system, alternative nuclear fuels are considered. One option is the "sphere-pac" fuel, which consists of a spherical particle bed vibro-packed into the cladding tube. Potential advantages of this concept are an almost powder less production and lower mechanical interaction between fuel and cladding. JNC has developed a new fuel irradiation behavior analysis code for sphere-pac fuel. It is based on a pellet type fuel code because of its analogous irradiation behavior. However, the macrostructure of the sphere-pac fuel affects some properties. Therefore, some modifications have to be applied. The PSI SPACON model is used to calculate the effective thermal conductivity. This theoretical calculation model takes into account the discontinuous structure with voids between the particles. It also accounts the increased thermal conductivity due to the sintering of the bed. A mechanistic sintering model addresses this structural change. Finally, the mechanical interaction between particle bed and cladding is studied. A three-dimensional Distinct Element Method is applied to investigate mechanical properties of the bed. Together with the theory of radial expansion pressure, these results then built a new model for the sphere-pac mechanical interaction.