The diversity of endosymbiotic bacteria that kill male host offspring during embryogenesis and their frequencies in certain groups of host taxa suggest that the evolution of male killing and the subsequent spread of male-killing symbionts are primarily determined by host life history characteristics. We studied the 10-spot ladybird beetle, Adalia decempunctata L. (Coleoptera: Coccinellidae), in...

Eosinophil and/or neutrophil leukocytes appear to have important roles in host defense against invasive, migratory helminth infestations, but the mechanisms of larval killing by leukocytes are uncertain. This study examines killing of newborn (migratory phase) larvae of Trichinella spiralis during incubation with granule preparations of human eosinophils or neutrophils and generators of hydroge...

Cytotoxic T lymphocytes (CTLs) are important immune effectors against intra-cellular pathogens. These cells search for infected cells and kill them. Recently developed experimental methods in combination with mathematical models allow for the quantification of the efficacy of CTL killing in vivo and, hence, for the estimation of parameters that characterize the effect of CTL killing on the targ...

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...

A novel decoherence mechanism caused by spacetime curvature is revealed. As a consequence, the spin state of a particle decoheres if only the particle moves in a curved spacetime. In particular, when a particle is near the event horizon of a black hole, an extremely rapid spin decoherence occurs for an observer who is static in a Killing time, however slow the particle’s motion is. PACS : 03.65...

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 synthesis of methotrexate (MTX) polyglutamates has been investigated in a human leukemia cell line, CCRF-CEM. An increase in either the extracellular MTX concentration (0.1-10 microM) or exposure time (4-24 h) allowed a greater accumulation of polyglutamate derivatives. The species which predominated (di-, tri-, or tetraglutamate) was also time and concentration dependent. Derivatives up to...

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...

Microbeams are ideally suited to the study of so-called ‘non-targeted’ phenomena that are now known to occur when living cells and tissues are irradiated. Non-targeted effects are those where cells are seen to respond to ionising radiation through pathways other than direct damage to the DNA. One such phenomenon is the ‘bystander effect’; the observation that unirradiated cells can be damaged t...