Induction of endogenous C-type virus by 5-iododeoxyuridine and augmentation of this induction by polycyclic hydrocarbons]

When the MLg Mouse cells were treated with the chemical carcinogens, in the presence of microsomal enzymes and NADPH2 after 5-iododeoxyuridine (IUdR) treatment, the induction frequency of the endogenous C-type virus was increased by nearly 10-fold in comparison with the cultures treated with IUdR only. In the preliminary screening of several polycyclic hydrocarbons including carcinogenic and non-carcinogenic products, apparently there was no correlation between the carcinogenecity in vivo and the stimulation capacity of IUdR induced C-type virus activation in our test conditions.     

Isoelectric variants of the principal polypeptide (p 30) of different strains of murine oncornaviruses]

The major murine oncornavirus polypeptide p 30 (30,000 daltons), which bears the conventional group-specific (gs) determinants, can be separated by isoelectric focusing into four classes, with isoelectric points (pI) of 5.5, 5.9, 6.7 and 7.1. All the Moloney stocks tested have a pI 5.9 p 30, while p 30's with three to four different pI values are found to coexist in other stocks, with the pI 6.7 form predominating in Gross virus stocks.     

Different primary structure of 2 variants of Friend virus p 30 polypeptide separated by isoelectric focusing]

Variants of p 30 (iso-p 30s), the 30,000 dalton major polypeptide of murine C-type retraviruses, have been characterized in all virus strains by isoelectric focusing. Several of these iso-p 30s have been found to coexist in a given virus strain. In the present study, two iso-p 30s, characteristic of the Friend-Rauscher subgroup, separated by preparative isoelectric focusing of p 30 in thin layers of polydextran gel, were subjected to tryptic peptide mapping and aminoacid analysis. The two iso-p 30s, with isoelectric points (pI) of 6.5 and 7.1, were found to possess a partially different primary structure, with about 50% homology. The results are discussed.     

Cytotoxicity of human T-lymphocytes sensitized by Epstein-Barr virus. Role of HLA antigens at the surface of target cells infected by the virus]

Peripheral T-lymphocytes from patients with infectious mononucleosis are cytotoxic towards target cells from Epstein-Barr virus-genome carrying human lumphoblastoid lines. Thus, these T-cells appear to be sensitized to viral coded determinants. Daudi cells, that carry EBV-genome, but lack HLA antigens are resistant to specific cytolysis in this model. These results suggest direct HLA involvement in the target structure recognized by birus-sensitized cytolytic T-lymphocytes in human.     

Induction of the mesoderm and primordial germ cells by the endoderm of Pleurodeles waltlii (Amphibia, Urodele): development during gastrulation]

Blastulae ectoderm is combined with dorsal or ventral endoderm from blastulae, gastrulae and early neurulae. In vitro culture reveals the presence of different mesodermal structures whose nature is connected with the endoderm origin site. Primordial germ cells differentiate essentially in the recombinates including ventral endoderm. The inducing capacity of this latter concerning germ cells is maximum at the beginning of gastrulation, then decreases during it and finally disappears at the onset of neurulation.     

Sensitivity of transformed EHSVi fibroblasts to the antibody-complement lytic system. Cooperation between the lytic units, and existence of a cellular defense]

The sensitivity of transformed EHSVi fibroblasts to the antibody-complement lytic system was evaluated, at various antibody concentrations (Ac), in conditions in which a variation of the lytic activity proportional to Ac3, 1 may be observed. This points out, not the expected cooperation between IgG molecules in activating C1 within a definite lytic unit, but a cooperation between the lytic units themselves, and therefore the existence of a cell defence.     

Study of the coronary arteriole bed at rest and during hyperemia by selective coronary scintigraphy with labeled microspheres]

The hyperemic response induced by the tri-iodinated contrast agent injection for coronarography assesses functional value of the arteriolar areas of coronary distribution. The intracoronary injection of two kinds of micropheres labeled with gamma emitter radionuclides of different levels of energy (99m-Technetium and 113m-Indium) provides comparison of the studied areas-scintigraphies at rest and during hyperemia.     

The effect of alloxan on the multiplication of different types of normal or cancerous cells, and on the transformation of chick embryo fibroblasts by Rous virus in vitro]

The action of alloxan was studied in vitro, on different categories of normal or cancerous cells. At concentrations of 250 and 350 gamma/ml, alloxan does not significantly inhibit the growth of normal cells, whereas it does inhibit the growth of cancerous cells. Furthermore, alloxan inhibits infection and transformation of chicken-embryo fibroblasts infected by the Rous virus.     

Influence of the viscous substance at the tip of the labellar hairs ofPhormia regina M. on the effectiveness of stimulation by cations and anions

Summary The stimulating effectiveness of salt solutions on the labellar taste hairs ofPhormia regina M. is discussed on the basis of ion diffusion properties across the mucopolysaccharidic layer at the hair tip.This work is partly supported by a grant from the Consiglio Nazionale delle Ricerche (CNR), Roma, Italy.     

Degradation of [3H]thymidine by a pentosyltransferase (EC 2.4.2.4) in the plasma of man and different animals.

[3H]Thymidine is degraded by an enzyme (thymidine phosphorylase; EC 2.4.2.4) which we have identified in the plasma of man and some animals. The presence of this enzyme in plasma or sera used to supplement culture media may, under certain experimental conditions, limit the validity of measuring the uptake of radiolabeled thymidine as a means of defining DNA synthesis.