The Redox Status of Experimental Hemorrhagic Shock as Measured by Cyclic Voltammetry

Mittal, Anubhav; Göke, Friederike; Flint, Richard J.; Loveday, Benjamin; Thompson, Nichola M.; Delahunt, Brett; Kilmartin, Paul A.; Cooper, Garth J. S.; MacDonald, Julie; Hickey, Anthony R.J.; Windsor, John A.; Phillips, Anthony R.J.

doi:10.1097/shk.0b013e3181c0ea12

Cited by 18 publications

(14 citation statements)

References 46 publications

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“…This peak results from the oxidation of uric acid, ascorbic acid and quite possibly other antioxidants found in blood. 34,35 Additional experimentation is necessary to understand what gives rise to the voltammetric peak and then to explain the origin of the peak shift observed on NPG vs. planar gold.…”

Section: Resultsmentioning

confidence: 99%

Potentiometric Measurements in Biofouling Solutions: Comparison of Nanoporous Gold to Planar Gold

Farghaly

Lam

Freeman

et al. 2015

J. Electrochem. Soc.

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Potentiometric redox measurements were made in solutions of increasing biological complexity starting with buffer solutions containing either potassium ferri/ferrocyanide or ascorbic acid and finishing with plasma and blood. When the concentration of ferri/ferrocyanide was high (∼0.2 mM), both biofouled planar and nanoporous gold electrodes gave Nernstian slopes of 55-59 mV. However, at or below a critical concentration (≤ 0.1 mM), ∼20% loss in sensitivity was observed at planar gold in contrast to nanoporous gold where Nernstian behavior was retained. For ascorbic acid, a Nernst slope of −41 mV was observed at biofouled nanoporous gold electrodes. In contrast, biofouled planar gold electrodes failed to give any potentiometric redox response. At all concentrations studied, cyclic voltammetric measurements on biofouled electrodes revealed significant impairment of faradaic electroactivity at planar gold electrodes while no impairment was shown at nanoporous gold. These results indicate that nanoporous gold is an ideal electrode material to use when making both potentiometric and cyclic voltammetric measurements, particularly in complex solutions containing relatively low concentrations of redox molecules. As proof of concept, the redox potential of plasma and blood has been measured using nanoporous and planar gold electrodes and their values compared. Potentiometry is a technologically simple and inexpensive approach to obtain important information about the redox state of a system and/or the concentration of ions in solution.1,2 The measurement itself is simple in that all that is needed is a high impedance voltammeter, a stable reference electrode, and a suitable indicating electrode. In contrast to voltammetric measurements, no current flows, and the concentration of the redox species in solution does not change nor does the indicating electrode surface become altered as a potential is not applied. Likely the most popular potentiometric measurement is the measurement of pH using an ion-selective electrode that incorporates a thin membrane responsive to the activity of protons in solution. 3For the work described herein, the indicating electrode is an inert metallic redox electrode that is purposely designed to be nonselective and will 'ideally' respond to all redox active species in solution able to exchange electrons with the metallic surface.1,2 When the indicator electrode is immersed in solution, it will equilibrate electrochemically with the dissolved redox species and a potential will develop at its surface. The measured potential is governed by factors such as (1) the redox species present, (2) their concentrations (activities), and (3) the rate of electron exchange with the electrode.2,4,5 Such redox measurements have been used to characterize the redox state of solutions with a complex matrix including milk, cheese, sludge, water and biological systems. [6][7][8][9][10][11][12][13] An important and often neglected factor in the measurement of redox potential is the nature of the electrode surface, pa...

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Section: Resultsmentioning

confidence: 99%

Potentiometric Measurements in Biofouling Solutions: Comparison of Nanoporous Gold to Planar Gold

Farghaly

Lam

Freeman

et al. 2015

J. Electrochem. Soc.

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“…Light microscopy was performed by a blinded consultant histopathologist on 5 mm thick longitudinal paraffin sections using haematoxylin and eosin staining. A previously published standardised scoring system for organ inflammation was used (44).…”

Section: Data Collectedmentioning

confidence: 99%

Warming and humidification have no effect on oxidative stress during pneumoperitoneum in rats

Sammour

Mittal²,

Delahunt

et al. 2011

Minimally Invasive Therapy & Allied Technologies

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Pneumoperitoneum is reported to induce oxidative stress due to the desiccative effect of cold, dry gas insufflation. The aim of this study is to compare the effect of warmed, humidified insufflation to standard gas, by measuring oxidative stress markers in a physiologically relevant animal model. Twenty male Wistar rats (330?650 g) were alternately assigned to the Warm Humidified group (WH, n = 10) and Control group (n = 10). All rats underwent pneumoperitoneum at 5 mmHg and a controlled flow rate for 110 min. The WH group received warmed (37?C) and humidified (98% Relative Humidity (RH)) gas and the control group received standard gas at room temperature (19?C) and 0% RH. At the end of pneumoperitoneum, samples of liver, kidney, pancreas, jejunum, and lung were excised. Levels of plasma and tissue malondialdehyde (MDA) and protein carbonyls (PC) were measured. Organ light microscopy was performed. There were no differences between groups for MDA or PC concentrations in plasma, liver, kidney, jejunum, or lung tissue. There were no differences in histological score between groups. Warming and humidification of pneumoperitoneum insufflation gas have no effect on measures of oxidative stress compared to non-warmed, non-humidified controls.

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“…11 UA is the most abundant aqueous antioxidant in humans and contributes as much as twothirds of all of the free radical-scavenging capacity of plasma, 12 closely corresponding to changes in the redox status following ischemia-reperfusion injury. 13 …”

Section: Introductionmentioning

confidence: 99%

The reliability of clinical dynamic monitoring of redox status using a new redox potential (ORP) determination method

Zhi

Liang

et al. 2013

Redox Report

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The Redox Status of Experimental Hemorrhagic Shock as Measured by Cyclic Voltammetry

Cited by 18 publications

References 46 publications

Potentiometric Measurements in Biofouling Solutions: Comparison of Nanoporous Gold to Planar Gold

Potentiometric Measurements in Biofouling Solutions: Comparison of Nanoporous Gold to Planar Gold

Warming and humidification have no effect on oxidative stress during pneumoperitoneum in rats

The reliability of clinical dynamic monitoring of redox status using a new redox potential (ORP) determination method

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