Macromolecular synthesis and ultrastructural changes induced in human larynx carcinoma cells following photodynamic therapy in vitro.

Human larynx carcinoma cells (HEp2) were sensitized with different concentrations of Hematoporphyrin and irradiated with a He-Ne laser at different fluences. The degree of PDT-effects were estimated by two parameters: a) macromolecular synthesis and b) observations using electron microscopy. All experiments were evaluated after 68 hr at 37 degrees C.

Neutralization epitope patterns of poliovirus strains isolated from cases of acute spinal paralysis and from healthy vaccinated children.

By using a battery of poliovirus neutralizing monoclonal antibodies received from the Pasteur Institute, Paris, we carried out the study of the patterns of neutralization epitopes of more than 300 poliovirus strains isolated from cases of acute spinal paralysis and from healthy vaccinated children. We tried to find out the utility of this test for establishing the origin (wild or Sabin) of a poliovirus strain and the possible evolution of the pattern of neutralization epitopes. The study of the neutralization epitopes was carried out by neutralization index assay (NI).

DNA synthesis in monkey kidney cellular culture, hematoporphyrin sensitized and He--Ne laser irradiated.

He--Ne laser irradiation for 1-45 J/cm2 has four actions upon monkey kidney cell cultures: a) a stimulation of nuclear DNA synthesis after 20 J/cm2; b) a diminution of replication after higher dose (45 J/cm2); c) inhibition of nuclear DNA synthesis and d) a marked cytotoxic effect. At lower radiation fluences (1-5 J/cm2) the influence on the biosynthesis of DNA is not significant.

In vitro effects of pulsed near-ultraviolet laser exposure on human larynx carcinoma cells.

Effects of pulsed near-ultraviolet laser beam on structural characteristics and macromolecular synthesis of carcinoma HEp2 cells were investigated. Laser irradiation damage induced in these eukaryotic cells could be characterized by two development stages: a) a reversible stage with minor morphological damages (1.5 kJ/m2) and 2) an irreversible one, at higher fluences, characterized by cellular membrane damage, necrobiosis and cells detachment from the substrate (4.