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M F Desrosiers

Publications and source records attributed to M F Desrosiers.

9 recordsLinked to original sources
PubMed1992

Jamaican and American adult perspectives on child psychopathology: further exploration of the threshold model.

Although several factors determine whether children receive psychological intervention, cultural determinants may be particularly influential. Cultural factors may influence adults' levels of concern over child psychopathology. This possibility was explored by comparing adult attitudes in two socioculturally different societies. Jamaican and American parents, teachers, and clinicians (total N = 382) judged vignettes of two children, one with overcontrolled (e.g., fearfulness) and one with undercontrolled (e.g., fighting) problems. Regression analyses revealed that although years of education affected some adult ratings, culture had the most profound effect.

Attitude↗
PubMed1991

Radiation doses.

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Animals↗
PubMed1991

Estimation of the absorbed dose in radiation-processed food--1. Test of the EPR response function by a linear regression analysis.

Free radicals produced in chicken bone tissue by 137Cs gamma-rays were measured using electron paramagnetic resonance spectroscopy. The yield of radicals was found to be proportional to the absorbed dose. Additive re-irradiation of previously irradiated bones is the basis of a method to estimate the absorbed dose in radiation-processed foods. The ability of the method to provide accurate dose assessments for a range of doses (0.5-7.4 kGy) is tested here. A linear fit to the data yields reasonable dose estimates for bone irradiated less than 2 kGy, but fails at the higher doses using a linear approximation to the dose response. These data and their implications are discussed.

Animals↗
PubMed1991

Estimation of the absorbed dose in radiation-processed food--2. Test of the EPR response function by an exponential fitting analysis.

The use of electron paramagnetic resonance spectroscopy to accurately evaluate the absorbed dose to radiation-processed bones (and thus meats) is examined. Additive re-irradiation of the bone produces a reproducible dose response function which can be used to evaluate the initial dose by back-extrapolation. It was found that an exponential fit (vs linear or polynomial) to the data provides improved accuracy of the estimated dose. These data as well as the protocol for the additive dose method are presented.

Animals↗
PubMed1991

In vivo assessment of radiation exposure.

Three workers at a San Salvador 60Co irradiation facility were victims of a radiation accident, resulting in the amputation of a leg from two workers. The absorbed dose to bone was successfully assessed by electron paramagnetic resonance (EPR) quantitation of radiation-induced hydroxyapatite centers.

Accidents, Occupational↗
PubMed1989

Mechanically-induced generation of radicals in tooth enamel.

Mechanical instrumentation of enamel leads to the formation of long-lived free radicals that can be conveniently measured by electron paramagnetic resonance (EPR) spectroscopy. Powdered enamel tissue exhibited EPR signals remarkably similar to the radicals formed by ionizing radiation. The observations described below lead to the conclusion that physical stress will induce a free-radical formation in dental tissues. These observations have significance for other areas of study such as dosimetry and archeological dating.

Dental Enamel↗
PubMed1989

The effect of oxygen, antioxidants, and superoxide radical on tyrosine phenoxyl radical dimerization.

Dimerization of tyrosine phenoxyl radical yields bityrosine (BT) which can easily be monitored by its characteristic fluorescence at 400 nm. The reactivity of tyrosine phenoxyl radical with O2 was examined by a variety of techniques. BT fluorescence was measured as a function of O2 concentration. Over a range of pH values (4-12) there was no effect of oxygen on BT production ([O2] less than or equal to 0.72 mM). In addition, oxygen uptake by the phenoxyl radical was measured directly with an oxygen electrode. It was determined by this technique that oxygen does not react with the phenoxyl radical with a rate constant greater than 10(3) M-1 s-1. Tyrosine phenoxyl radical "repair" by superoxide and physiological antioxidants was examined by BT fluorescence quenching as well as pulse radiolysis. Implications of these results as to the fate of tyrosine phenoxyl radicals produced in biological systems is discussed.

Antioxidants↗