Biomedical subjects

P Poulet

Publications and source records attributed to P Poulet.

22 records · Page 2Linked to original sources

PubMedDate not supplied

Localized T1 measurements using an inversion-recovery OSIRIS method.

This work presents a new method for localized T1 measurements, based upon the OSIRIS scheme. It relies on the use of a non-selective 180 degrees pulse applied before the OSIRIS preparation cycle. The accuracy of the method has been verified with test tubes and in vivo for two nuclei, 1H and 19F. The accuracy of the T1 values is discussed, as well as possible applications of the inversion-recovery method to non-invasive in vivo pO2 measurements.

Animals↗

PubMedDate not supplied

Susceptibility-based MRI contrast of the CSF by intravascular superparamagnetic nanoparticles.

Endorem, a suspension of superparamagnetic iron oxide dextran nanoparticles (NP), have been injected intravenously to healthy anesthetized rats for the purpose of contrast enhancement of brain in gradient-echo imaging at 200 MHz. Not only gray and white matter but also particular regions of the cerebrospinal fluid (CSF) were contrasted in sagittal and transverse images, although samples of this fluid did not contain NP. The selected contrast in the CSF would result form the ability of dense vascular beds containing highly magnetized particles to induce a remote susceptibility effect far beyond the vascular walls into a large fraction of extravascular water.

Animals↗

PubMedDate not supplied

31P NMR spectroscopy of photodynamically treated cells.

The metabolic response of Chinese Hamster Ovary (CHO) cells during photodynamic therapy (PDT) with hematoporphyrin IX (Hp IX) and pheophorbide (Ph) was monitored in real time by 31-phosphorous (31P) nuclear magnetic resonance (NMR) spectroscopy. The effects of the delivered light dose and of cell oxygenation were investigated. A delayed disappearance of nucleoside triphosphate (NTP) following irradiation was observed, which was related to the treatment efficiency. For cells irradiated with a light dose of 0.8 J/cm2 in the presence of Hp IX, the disappearance of the NTP peaks occurred within 30 minutes of irradiation, but for an irradiation of 0.24 J/cm2, the disappearance of the NTP peaks occurred about 6 hours later, and this delayed disappearance is related to the surviving fraction. For irradiation experiments involving Ph and a light dose of 0.036 J/cm2, NTP in injured cells began to decrease about 3 hours after irradiation, whereas for a light dose of 0.24 J/cm2, we observed the instantaneous disappearance of the NTP peaks occurring during the irradiation time. The same efficiency was obtained with two different oxygen partial pressures in the perfusate (360 and 154 mmHg) and a light dose of 0.24 J/cm2.

Animals↗

PubMedDate not supplied

Experimental observation of photochemically induced oxygen depletion in perfused cells undergoing photodynamic therapy.

This report presents a non invasive method for studying oxygen consumption during photodynamic therapy in cultured cells. The oxygen partial pressure of perfusion medium flowing through cells cultured on microcarrier beads, was investigated before, during and after treatment. Pheophorbide a was used as a sensitiser. Time-dependent measurements demonstrate photochemical oxygen depletion induced by photosensitized reactions, followed by an oxygen pressure increase were attributed to a reduction in the cells' metabolism.

Animals↗