Species differences in oxidative drug metabolism: some basic considerations

Elevated circulating Hsp70 levels are correlative for malignancies in different mammalian species

Circulating Hsp70 levels were determined in feline and porcine cohorts using two different ELISA systems. These comparative animal models of larger organisms often reflect diseases, and especially malignant tumors, better than conventional rodent models. It is therefore essential to investigate the biology and utility of tumor biomarkers in animals such as cats and pigs. In this study, levels of free Hsp70 in the blood of cats with spontaneously occurring tumors were detected using a commercial Hsp70 ELISA (R&D Systems). Sub-analysis of different tumor groups revealed that animals with tumors of epithelial origin presented with significantly elevated circulating Hsp70 concentrations. In addition to free Hsp70 levels measured with the R&D Systems Hsp70 ELISA, levels of exosomal Hsp70 were determined using the compHsp70 ELISA in pigs. Both ELISA systems detected significantly elevated Hsp70 levels (R&D Systems: median 24.9 ng/mL; compHsp70: median 44.2 ng/mL) in the blood of a cohort of APC1311/+ pigs diagnosed with high-grade adenoma polyps, and the R&D Systems Hsp70 ELISA detected also elevated Hsp70 levels in animals with low-grade polyps. In contrast, in flTP53R167H pigs, suffering from malignant osteosarcoma, the compHsp70 ELISA (median 674.32 ng/mL), but not the R&D Systems Hsp70 ELISA (median 4.78 ng/mL), determined significantly elevated Hsp70 concentrations, indicating that in tumor-bearing animals, the dominant form of Hsp70 is of exosomal origin. Our data suggest that both ELISA systems are suitable for detecting free circulating Hsp70 levels in pigs with high-grade adenoma, but only the compHsp70 ELISA can measure elevated, tumor-derived exosomal Hsp70 levels in tumor-bearing animals.

Nutrient plasma levels achieved during treatment that reduces noise-induced hearing loss

Hearing loss encompasses both temporary and permanent deficits. If temporary threshold shift (TTS) and permanent threshold shift (PTS) share common pathological mechanisms, then agents that reduce PTS also should reduce TTS. Several antioxidant agents have reduced PTS in rodent models; however, reductions in TTS have been inconsistent. This study first determined whether dietary antioxidants (beta-carotene and vitamins C and E) delivered in combination with magnesium (Mg) reliably increase plasma concentrations of the active agents. Then, additional manipulations tested the hypothesis that these nutrients reduce acute TTS insult in the first 24 h after loud sound as well as longer lasting changes in hearing measured up to 7 days postnoise. Saline or nutrients were administered to guinea pigs prior to and after noise exposure. Sound-evoked electrophysiological responses were measured before noise, with tests repeated 1-h postnoise, as well as 1-day, 3-days, 5-days, and 7-days postnoise. All subjects showed significant functional recovery; subjects treated with nutrients recovered more rapidly and had better hearing outcomes at early postnoise times as well as the final test time. Thus, this combination of nutrients, which produced significant increases in plasma concentrations of vitamins C and E and Mg, effectively reduced hearing loss at multiple postnoise times. These data suggest that free radical formation contributes to TTS as well as PTS insults and suggest a potential opportunity to prevent TTS in human populations.