OBJECTIVES We aimed to increase the bacterial cell killing efficacy of erythrosine-mediated photodynamic therapy (PDT) of Streptococcus mutans biofilms by fractionating the delivered light dose into a series of shorter pulses. METHODS S. mutans biofilms of 200 microm thickness were grown in a constant-depth film fermenter (CDFF). Biofilms were incubated with 22 microM erythrosine before being...

The presence of oxygen in tumours has substantial impact on treatment outcome; relative to anoxic regions, well-oxygenated cells respond better to radiotherapy by a factor 2.5–3. This increased radioresponse is known as the oxygen enhancement ratio. The oxygen effect ismost commonly explained by the oxygen fixation hypothesis, which postulates that radical-inducedDNAdamage can be permanently ‘f...

The presence of oxygen in tumours has substantial impact on treatment outcome; relative to anoxic regions, well-oxygenated cells respond better to radiotherapy by a factor 2.5–3. This increased radioresponse is known as the oxygen enhancement ratio. The oxygen effect ismost commonly explained by the oxygen fixation hypothesis, which postulates that radical-inducedDNAdamage can be permanently ‘f...

The single cell plating technique has been applied to quantitation of the reproductive killing of mammalian cells by specific antibodies. This method confirms previous demonstrations by other workers of localization of all the killing activity in the gamma-globulin fraction of specific cell antisera but not of normal sera; the need for complement for the killing action in low doses of antibody ...

BACKGROUND Natural killer cells are an important component of the innate immune system. Anti-cancer therapies utilizing monoclonal antibodies also rely on the cytotoxicity of NK cells for their effectiveness. Here, we study the dynamics of NK cell cytotoxicity. METHODOLOGY/PRINCIPAL FINDINGS We observe that IL-2 activated human NK cells can serially hit multiple targets. Using functional assa...