Mary C. Vagula

Comments on Point: Counterpoint: Hypobaric hypoxia induces/does not induce different responses from normobaric hypoxia.

112:1788-1794, 2012. ; J Appl Physiol Joshua C. Weavil, Peter Bartsch and Charles F. Nelatury Samuel Verges, Patrick Levy, Eric M. Snyder, Bruce D. Johnson, Jonathon L. Stickford, Y. Millet, Benjamin D. Levine, James H. Wessel III, Bernard Wuyam, Renaud Tamisier, MacInnis, Michael S. Koehle, Thomas Rupp, Marc Jubeau, Stephane Perrey, Guillaume Laymon, Jack A. Loeppky, Matiram Pun, Kai Schommer, Mary C. Vagula, Martin J. S. Chapman, Johnny Conkin, Hugo Nespoulet, Darren P. Casey, Bryan J. Taylor, Abigail Olivier Girard, Michael S. Koehle, Jordan A. Guenette, Samuel Verges, Robert F. normobaric hypoxia induces/does not induce different responses from Comments on Point:Counterpoint: Hypobaric hypoxia

Comments on point:counterpoint: humans do/do not demonstrate selective brain cooling during hyperthermia.

TO THE EDITOR: Middle cerebral artery blood velocity (MCAVmean) is reduced up to 30% in humans following a passive increase in internal temperature of 1–1.5°C (1). If the diameter of the MCA remains unchanged during heat stress, reductions in MCAVmean are proportional to reductions in cerebral blood flow. In support of selective brain cooling in hyperthermic humans, White et al. (7) suggest that vasodilation of the cerebral vasculature exists, which in turn increases cranial perfusion and maintains the arterial-venous temperature difference. The authors state, “it remains to be explained how MCA velocity, and presumably cranial perfusion, is reduced in hyperthermic humans if mean arterial blood pressure is maintained and MCA caliber remains constant” (4, 7). This argument ignores the potent effects of changes in carbon dioxide partial pressures on cerebral perfusion, with hypercapnia increasing and hypocapnia decreasing cerebral blood flow, respectively (6). During moderate to pronounced passive heat stress, arterial and end-tidal carbon dioxide partial pressures decrease upward to 8 Torr (1, 2). Importantly, an 8-Torr reduction in arterial carbon dioxide partial pressure is estimated to reduce cerebral blood flow by 24% (5) through increases in resistance of the cerebral arterioles “downstream” from the MCA (3). Thus the clear and robust reduction in MCAVmean during passive heat stress is likely due primarily to decreases in carbon dioxide partial pressures causing increases in vascular resistance of cerebral arterioles distal to the MCA.

Commentaries on viewpoint: On the hysteresis in the human Achilles tendon.

114:518-520, 2013. ; J Appl Physiol Karamanidis and Sudarshan R. Nelatury Alexandre Foure, Christophe Cornu, Gaspar Morey-Klapsing, Lida Mademli, Kiros Maganaris, Rene B. Svensson, Christian Coupe, Andreas Hershenhan, Pernilla Eliasson, Adamantios Arampatzis, Mary C. Vagula, Andrew G. Cresswell, Constantinos N. Glen A. Lichtwark, Robert F. Ker, Neil D. Reeves, S. Peter Magnusson, Antoine Nordez, human Achilles tendon Commentaries on Viewpoint: On the hysteresis in the

Effects of BDE-85 on the Oxidative Status and Nerve Conduction in Rodents

BDE-85 is a congener of a class of flame-retardant compounds called polybrominated diphenyl ethers (PBDEs). Although there are some studies on other congeners of PBDEs, there are none on the toxicity potential of this penta-BDE member. This study, therefore, reports the oxidative status and sciatic nerve conduction properties following BDE-85 treatment in rodents. The oxidative stress markers, lipid hydroperoxides, and the activities of antioxidant enzymes, namely superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione-S-transferase (GST), and catalase, in the exposed mice liver and brain tissues showed tissue-specific alterations following intraperitoneal injection of 0.25 mg/kg body weight of BDE-85 for 4 days. The results indicate a significant disruption in the oxidant/antioxidant equilibrium and setting in of oxidative stress. Isolated sciatic nerves of rats exposed to 5 µg/mL or 20 µg/mL of BDE-85 showed a significant reduction in nerve conduction velocity and compound action potential amplitudes, indicating physiological damage to the sciatic nerves.

Lipid Peroxidation and Polybrominated Diphenyl Ethers – A Toxicological Perspective

© 2012 Vagula and Konieczko, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Lipid Peroxidation and Polybrominated Diphenyl Ethers – A Toxicological Perspective

Study of effects of radio-wave frequency radiation emitted from cellular telephones on embryonic development of danio rerio

Radio wave frequency (RF) radiation emitted from cellular telephones has become increasingly ubiquitous as a result of the popularity of these phones. With the increasing and unavoidable exposure to RF radiation a reality, it is imperative that the effects of such radiation on living tissue be well understood. In particular, it is critical to understand any effects that RF radiation may have as a carcinogen and on embryonic development, as pregnant women are not exempt from such exposure. As a model organism, zebrafish (Danio rerio) have been studied extensively, and their value in studies of gene expression cannot be overstated. This study observed the effects of RF radiation on the embryonic development of zebrafish. The expression of two genes, shha and hoxb9a, that are key to the early development of the fish was examined. Both genes have homologs in humans as well as in other model organisms. Preliminary results suggest that exposure to cell phone radiation might have an effect on the expression of shha in zebrafish embryos, causing under expression. More trials are necessary to validate these results.

Radiation hazards of radio frequency waves on the early embryonic development of Zebrafish

With the growing use of wireless devices in almost all day-to-day activities, exposure to radio-frequency radiation has become an immediate health concern. It is imperative that the effects of such radiation not only on humans, but also on other organisms be well understood. In particular, it is critical to understand if RF radiation has any bearing on the gene expression during embryonic development, as this is a crucial and delicate phase for any organism. Owing to possible effects that RF radiation may have on gene expression, it is essential to explore the carcinogenic or teratogenic properties that it may show. This study observed the effects of RF radiation emitted from a cellular telephone on the embryonic development of zebra fish. The expression of the gene shha plays a key role in the early development of the fish. This gene has homologs in humans as well as in other model organisms. Additionally, several biomarkers indicative of cell stress were examined: including lactate dehydrogenase (LDH), superoxide dismutase (SOD), and lipid peroxidation (LPO). Results show a significant decrease in the expression of shha, a significant decrease in LDH activity. There was no significant increase in SOD and LPO activity. No morphological abnormalities were observed in the developing embryos. At present, these results indicate that exposure to cell phone radiation may have a suppressive effect on expression of shha in D. rerio, though such exposure does not appear to cause morphological detriments. More trials are underway to corroborate these results.

Simulation Studies in Biochemical Signaling and Enzyme Reactions

Biochemical pathways characterize various biochemical reaction schemes that involve a set of species and the manner in which they are connected. Determination of schematics that represent these pathways is an important task in understanding metabolism and signal transduction. Examples of these Pathways are: DNA and protein synthesis, and production of several macro-molecules essential for cell survival. A sustained feedback mechanism arises in gene expression and production of mRNA that lead to protein synthesis if the protein so synthesized serves as a transcription factor and becomes a repressor of the gene expression. The cellular regulations are carried out through biochemical networks consisting of reactions and regulatory proteins. Systems biology is a relatively new area that attempts to describe the biochemical pathways analytically and develop reliable mathematical models for the pathways. A complete understanding of chemical reaction kinetics is prohibitively hard thanks to the nonlinear and highly complex mechanisms that regulate protein formation, but attempting to numerically solve some of the governing differential equations seems to offer significant insight about their biochemical picture. To validate these models, one can perform simple experiments in the lab. This paper introduces fundamental ideas in biochemical signaling and attempts to take first steps into the understanding of biochemical oscillations. Initially, the two-pool model of calcium is used to describe the dynamics behind the oscillations. Later we present some elementary results showing biochemical oscillations arising from solving differential equations of Elowitz and Leibler using MATLAB software.

The toxic effects of flame retardants: a gene expression study in elucidating their carcinogenicity

Polybrominated Diphenyl Ethers (PBDEs) are flame retardants widely used in many commercial products, including building materials, electronics, furnishings, motor vehicles, airplanes, plastics, polyurethane foams, and textiles. Although the specific toxic action of these chemicals is not clear, it is reported that they can cause serious damage to the nervous, reproductive, and endocrine systems. These chemicals are branded as “probable carcinogens” by Environmental Protection Agency (EPA). Therefore, this study is taken up to investigate the expression of genes namely, TP-53, RAD1, CRADD, and ATM, which are involved in apoptosis, DNA repair and cell cycle regulation. For this study human umbilical vein endothelial cells (HUVEC) are exposed to 5 μM of BDE-85 (a penta-BDE) and BDE-209 (deca-BDE). The results of this report reveal significant alteration in all the genes under investigation in BDE-85 and BDE-209 exposed cells. The BDE-85 induced responses are significantly more than BDE-209. These results emphasize the congener specific action of PBDEs on the expression of genes relevant to DNA repair and cell division of HUVEC cells.

Commentaries on Viewpoint: On the hysteresis in the human Achilles tendonINFERRING TENDON MECHANICAL PROPERTIES USING ULTRASOUND IMAGINGTHE HYSTERESIS OF TENDON, IN VITRO AND IN VIVOCOMMON PROBLEMS IN THE MEASUREMENT OF HUMAN TENDON HYSTERESIS IN VIVOVIEWPOINT: ON THE HYSTERESIS IN THE HUMAN ACHILLES TENDONON THE HYSTERESIS IN THE HUMAN ACHILLES TENDON: INFLUENCE OF THE LOADING RATE AND MUSCLE COORDINATIONCOMMENTARY ON VIEWPOINTSTIFFNESS AND HYSTERESIS OF HUMAN TENDONS

114:518-520, 2013. ; J Appl Physiol Karamanidis and Sudarshan R. Nelatury Alexandre Foure, Christophe Cornu, Gaspar Morey-Klapsing, Lida Mademli, Kiros Maganaris, Rene B. Svensson, Christian Coupe, Andreas Hershenhan, Pernilla Eliasson, Adamantios Arampatzis, Mary C. Vagula, Andrew G. Cresswell, Constantinos N. Glen A. Lichtwark, Robert F. Ker, Neil D. Reeves, S. Peter Magnusson, Antoine Nordez, human Achilles tendon Commentaries on Viewpoint: On the hysteresis in the