Biomedical subjects

M Terrissol

Publications and source records attributed to M Terrissol.

25 records · Page 2Linked to original sources

PubMed1994

Modelling of radiation-induced DNA damage: the early physical and chemical event.

A Monte Carlo track structure calculation of single- and double-strand breaks induced by direct energy deposition in DNA and by interacting diffusible .OH radicals with DNA has been made for low energy electrons. The .OH radicals generated within 4 nm of linear segments of DNA were diffused in order to mimic the mean diffusion distance in the cellular environment. The reactions of the radical species .OH, .H and e-aq were included in this study. The calculated values for the yield of single- and double-strand breaks have been compared with experimentally determined values from the literature. The calculations indicate, too, that the majority of dsb have additional associated damage, constituting clustered lesions of varying complexity.

DNA↗

PubMed1980

Comparison between experimental measurements and calculated transport simulation for electron dose distributions inside homogeneous phantoms.

Comparison is made between dosimetric results measured on electron beams delivered by the three medical accelerators Sagittaire, Saturne and Neptune built by CGR MeV with the results simulated by a Monte Carlo method. In depth, the differences are small for moderate energies with scanned electron beams. In the penumbra region, the differences are small in all cases.

Electrons↗

PubMedDate not supplied

Plasma concentrations and pharmacokinetics of misonidazole after intraperitoneal administration to the mouse.

The pharmacokinetics of misonidazole, a hypoxic-cell radiosensitizer, were determinated after intraperitoneal administration to standardized Balb/c mice. The experimental data was fitted, using non linear analysis, to plasma-concentration curves described by tri-exponential equations derived from a two-compartment model. The pharmacokinetic constants (absorption and elimination coefficients) were determinated.

Animals↗

PubMedDate not supplied

A variable reabsorption time-delay model for pharmacokinetics of drugs.

A two-compartment model with time delay is proposed to describe the pharmacokinetics of drugs subject to enterohepatic circulation. This model is applicable when the reabsorption is repeated several times at unequal intervals. Sample applications are provided.

Biliary Tract↗

PubMedDate not supplied

Computer evaluation of direct and indirect damage induced by free and DNA-bound iodine-125 in the chromatin fibre.

PURPOSE: When Iodine-125 decays within chromatin, several in vivo experiments have shown that the radiobiological effects are caused mainly by indirect mechanisms and that more than one DNA double strand break (DSB) is produced per decay. We present calculations to evaluate the contribution of direct and indirect effects of radiation tracks to produce DNA damage induced by bound and free I-125 in a model of chromatin DNA. MATERIALS AND METHODS: A solenoid model of chromatin with 18 nucleosomal elements placed in bulk water (more than 600,000 atoms) is used where the initial I-125 decay takes place. All physical and chemical events initiated by Auger and X-rays were taken into account. The yields of single strand breaks (SSB) and DSB were derived using direct effects on DNA and indirect reactions of all radical species generated in the radiolysis of the bulk water. RESULTS: The distribution of damage complexity for free and DNA-bound I-125 is presented. We obtained more than 1.3 DSB per decay, with nearly equal contributions from direct and indirect effects. However, for the most complex type of damage, located at the decay site, the direct effect is about 70% of the total number. To show the protective effect of histones, simulations were carried out with and without the presence of histones.

Chromatin↗

PubMedDate not supplied

Chronotoxicity of methotrexate in mice after intraperitoneal administration.

Methotrexate (MTX), an effective agent in treatment of cancer, is one of the most versatile antineoplastic agents in spite of severe toxicity problems. The purpose of this study was to determine the circadian variation of this toxicity in order to decrease the side effects. The experiments were done in mice given a single i.p. dose. The toxicity of MTX, estimated from the relative weight loss, varied according to the time of administration, with a maximum after administration at 0900 (02 HALO). The dose-effect relationship can be described by a linear function: delta P/P versus log (dose). The slope of this line varies with the time of administration. These variations are correlated with the variations in biochemical [dihydrofolate reductase (DHFR) activity] and pharmacokinetic parameters (AUC) studied in previous works.

Animals↗

PubMedDate not supplied

[Morbidity and mortality in a pediatric department in Dakar].

The authors study, for the year 1983, the morbidity and the mortality in a pediatrics department in Dakar. Despite the fact that the patients admitted belong to a privileged group of the senegalese population, the mortality rate is high (17%), mainly during the neonatal period (51.5%), and within the age group of 1 to 23 months (21%). Seasonal influence is obvious. Admissions and deaths are significantly more numerous from june to december. The diseases of concern are still diarrhea, malnutrition and respiratory diseases.

Adolescent↗