[Immunogenic properties of neomycin conjugates with macromolecular carriers]. / Issledovanie immunogennykh svoistv kon"iugatov antibiotika neomitsina s makromolekuliarnym nositeliami.

To obtain diagnostic antibodies to neomycin, immunogenic properties of the neomycin conjugates with macromolecular carriers were studied. Bovine serum albumin and copolymers of N-vinylpyrrolidone with crotonic acid and N-hydroxyphthalimide ether of crotonic acid were used as carriers. It was shown that immunization of mice by the conjugates in combination with Freund's adjuvant resulted in production of neomycin antibodies, the titer being 1/80 to 1/130. When the antibiotic conjugates with the copolymers of N-vinylpyrrolidone were used and not the neomycin conjugates with the carrier of the protein nature, the neomycin antibodies were produced in the absence of Freund's full adjuvant. With the use of the isolated antibodies to neomycin a method for indirect solid phase enzyme immunoassay of neomycin was developed at the minimum detectable level of 25 ng/ml.

Replicative intermediates of hepatitis B virus in HepG2 cells that produce infectious virions.

Clonal cells derived from HepG2 cells transfected with a plasmid containing hepatitis B virus (HBV) DNA secrete hepatitis B surface antigen particles, nucleocapsids, and virions (M. A. Sells, M.-L. Chen, and G. Acs, Proc. Natl. Acad. Sci. USA 84:1005-1009, 1987) which elicit acute hepatitis in chimpanzees (G. Acs, M. A. Sells, R. H. Purcell, P. Price, R. Engle, M. Shapiro, and H. Popper, Proc. Natl. Acad. Sci. USA 84:4641-4644, 1987). We report here the initial characterization of the viral nucleic acids produced in this culture system. Kinetic analyses of nuclear, cytoplasmic, and extracellular HBV DNAs were performed by Southern blotting with radiolabeled HBV strand-specific probes. The results from these analyses indicate that at the stationary cellular growth phase, there is a dramatic increase in the rate at which HBV DNA accumulates. Incomplete double- and single-stranded forms of the HBV genome were detected in the nuclear and cytoplasmic fractions as well as in the extracellular medium. In addition, the nuclear DNA apparently includes multiple complete copies of the HBV genome chromosomally integrated and full-length covalently closed circular HBV DNA. Multiple HBV-specific polyadenylated RNAs with lengths of 3.5, 2.5, and 2.1 kilobases were identified by Northern (RNA) blot analysis. S1 nuclease mapping and primer extension identified a single 3' end and multiple unique initiation sites corresponding to nucleotides just 5' to the pre-S1 region, as well as upstream and within the pre-S2 and precore regions. The nucleic acid profile obtained from these analyses is essentially a facsimile of that obtained by studying liver tissue from HBV-infected individuals.

Replicative intermediate of hepatitis B virus in transfected murine fibroblasts.

The NIH 3T3-derived cell line psi AM22b, which carries a defective Moloney murine leukemia virus, was transfected with a plasmid carrying the neo gene and two head-to-tail copies of the hepatitis B virus (HBV) genome positioned with opposing polarities. Both the two HBV dimers and the neo gene were located between two Moloney murine leukemia virus long terminal repeats. Poly(A)+ RNAs isolated from one clone that grew in the presence of G418 contained the two major classes of HBV-specific transcripts (3.5-kilobase pregenome and 2.1-kilobase mRNAs) in approximately equivalent amounts, which was reminiscent of the profiles of viral mRNAs from the livers of infected humans and chimpanzees.

[Determination of T- and B-lymphocyte counts in guinea pigs]. / Opredelenie kolichestva T- i B-limfotsitov u morskikh svinok.

T lymphocytes of guinea-pigs were found to form spontaneous E-rosettes with rabbit red blood cells. The lymphocyte count constituted 32% of blood lymphocytes, 41% of lymph node cells. Meanwhile no T lymphocytes were detected in the bone marrow. The T lymphocyte subpopulation capable of forming "early" rosettes was demonstrated. B lymphocytes formed EAC-rosettes with sheep red blood cells. The B lymphocyte count in the blood, lymph nodes and bone marrow amounted to 10, 18 and 5%, respectively. The effects of incubation conditions, centrifugation, antibody types, and complement concentration, etc. on E- and EAC-rosette formation were defined.

[Relationship between aflatoxin formation in wheat grain and self-heating and changes in the chemical composition of grain during the growth of "storage molds"]. / Obrazovanie aflatoksinov v zerne pshenitsy v sviazi s samosogrevaniem i izmenenie khimicheskogo sostava zerna pri razvitii "plesenenei khraneniia"

The microbial composition of grain harvested in a wet (1973) and dry (1972) season was investigated. The largest amount of strains of Aspergillus flavus--the main producer of aflatoxins-was found in the surface layer of the heap of self-heating grain. The content of toxigenic strains of A. flavus in the grain harvested during the two seasons was stable amounting to 6.8%. Aflatoxins were detected in 17.4% samples of self-heating grain. Self-heating was followed by an accumulation of aflatoxins and deterioration of biochemical and baking properties of grain.