Paul Héroux

Monitoring living tissues by electrical impedance spectroscopy

Solving the experimental difficulties associated with measurement of the electrical impedance of living tissues gives access to valuable tissue compartment parameters which are sensed within seconds using minimally invasive, simple metallic electrodes. Extracellular conductivity and cell membrane capacitance can be followed over time under conditions of metabolic toxicity, perfusion loss and thermal stress in liver, brain cortex, and muscle, respectively. Application of this technique in burns therapy allows an accurate estimation of the severity of thermal injury to skeletal muscle, supporting predictions on tissue survival.

Characterization of the 60-Hz magnetic fields in schools of the Carleton board of education

The aim of this study was to characterize 60-Hz magnetic field levels in 79 schools managed by the Carleton Board of Education. Using a Field StarTM 1000 magnetometer, 43,009 60-Hz magnetic field measurements were taken in June 1993. The average magnetic field levels in schools (AM =9 0.082 µT, GM = 0.033 µT) were lower than in many other occupational environments. Typing rooms exhibited the highest level with an AM of 0.226 µT. There was a trend for stronger fields in secondary schools, with a GM of 0.072 µT, than those in elementary and intermediate schools, whose fields had a GM of 0.065 and 0.061 µT, respectively. High energy consumption (more than 50,000 kW hr) correlated with the 1 percentile (L1%) of magnetic field levels (r = 0.615).The geometric mean (GM) of the average magnetic field levels of two-story buildings (0.080 µT) was found to be significantly higher than that for one-story buildings (GM = 0.056 µT, p = 0.024). The sources accounting for the largest number of hot spots were wires in th...

Low Serum Testosterone Levels Are Associated with Elevated Urinary Mandelic Acid, and Strontium Levels in Adult Men According to the US 2011–2012 National Health and Nutrition Examination Survey

Background Little is known regarding the effects of environmental exposure of chemicals on androgenic system in the general population. We studied 5,107 subjects included in the National Health and Nutrition Examination Survey (2011–2012). Methods Urinary, serum, and blood levels of 15 subclasses comprising 110 individual chemicals were analyzed for their association with serum testosterone levels. The subjects were divided into high and low testosterone groups according to the median testosterone concentration (374.51 ng/dL). Odds ratios (ORs) of individual chemicals in association with testosterone were estimated using logistic regression after adjusting for age, ethnicity, cotinine, body mass index, creatinine, alcohol, and the poverty income ratio. Results Adjusted ORs for the highest versus lowest quartiles of exposure were 2.12 (95% CI: 1.07, 4.21; Ptrend = 0.044), 1.84 (95% CI: 1.02, 3.34; Ptrend = 0.018) for the association between urinary mandelic acid, and strontium quartiles with low testosterone concentrations in adult men, respectively. However, no association was observed for the remaining chemicals with testosterone. Conclusions The National Health and Nutrition Examination Survey data suggest that elevations in urinary mandelic acid, and strontium levels are negatively related to low serum testosterone levels in adult men.

Metabolic restriction of cancer cells in vitro causes karyotype contraction—an indicator of cancer promotion?

The metabolism of cultured cancer cells is stimulated by 21% oxygen and generous nutrition, while real tumors grow in oxygen and nutrient-restricted environments. The effect of these contrasted conditions was studied in five hyperploid (54–69) cancer cell lines. When grown under anoxia and in the presence of antioxidant metabolic restrictors, the cell lines quickly reverted to almost normal chromosome numbers (47–49). The stepped withdrawal of oxygen over K562 showed progressive increases in proliferation rate and the acquisition of a stable, stem phenotype. In genetic studies, hyperploid cancer cells adjusted their chromosome numbers up or down to match their micro-environment through rapid mechanisms of endo-reduplication or chromosome loss. These fast reactions may explain the surprising adaptability of tumor cells to oncologic interventions. Furthermore, karyotype contraction may provide a basis for the previously observed carcinogenic influence of the administration of some antioxidants in human populations.