Linked Life Data

9648527

Source:http://linkedlifedata.com/resource/pubmed/id/9648527

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1998-7-30
pubmed:abstractText
We report the effects of singlet oxygen (1O2) and non-1O2-mediated sensitizer photobleaching on oxygen consumption and dosimetry during photodynamic therapy (PDT) of sensitized multicell tumor spheroids. We develop a theoretical model for the description of non-1O2-mediated photobleaching resulting from irreversible reactions of the excited singlet or triplet sensitizer populations with cell substrate. We show that the fluence-dependent simple exponential decay expression of sensitizer degradation is not consistent with these mechanisms and, therefore, with any reasonable mechanism that we consider, because we have shown previously that 1O2-mediated photobleaching cannot be described by a simple exponential with a constant photobleaching coefficient (I. Georgakoudi et al., Photochem. Photobiol. 65, 135-144, 1997). Analysis of oxygen microelectrode measurements performed at the edge of Nile blue selenium (EtNBSe)- and protoporphyrin IX (PpIX)-sensitized spheroids during PDT demonstrates that the former drug photobleaches via a non-1O2-mediated mechanism, while the latter is degraded via a 1O2-mediated mechanism. Comparisons of the cytotoxic effects of EtNBSe with those of Photofrin (a drug that is degraded via a 1O2-mediated mechanism) indicate that the lower threshold 1O2 dose and the higher extinction coefficient and 1O2 yield for EtNBSe do not necessarily result in improved photodynamic effects, thus emphasizing the importance of the sensitizer photobleaching mechanism for dosimetry.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0031-8655
pubmed:author
pubmed:issnType
Print
pubmed:volume
67
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
612-25
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Singlet oxygen- versus nonsinglet oxygen-mediated mechanisms of sensitizer photobleaching and their effects on photodynamic dosimetry.
pubmed:affiliation
Department of Biochemistry & Biophysics, University of Rochester School of Medicine and Dentistry, NY 14642, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't