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Owen King N, Gruev V, Lake SP. Implementation of a logarithmic division-of-focal-plane polarimeter to quantify changes in collagen alignment at varying levels of illumination. Appl Opt 2020; 59:7813-7820. [PMID: 32976451 DOI: 10.1364/ao.398362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 08/02/2020] [Indexed: 06/11/2023]
Abstract
We examine the impact of illumination, aperture, and sample thickness on two division-of-focal-plane (DoFP) polarimeters, one created using a standard 3 T pixel and the other with a forward-biased, logarithmic pixel. Across all measured metrics the logarithmic DoFP polarimeter was better able to track real-time changes in collagen alignment than the standard DoFP polarimeter.
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Vial G, Guigas B. Assessing Mitochondrial Bioenergetics by Respirometry in Cells or Isolated Organelles. Methods Mol Biol 2018; 1732:273-287. [PMID: 29480482 DOI: 10.1007/978-1-4939-7598-3_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Mitochondrial oxidative phosphorylation is central for generating ATP and maintaining energy homeostasis in most eukaryotic cells. The ex vivo measurement of mitochondrial oxygen consumption rates in intact cells or isolated organelles is a valuable approach to assess mitochondrial bioenergetics in various experimental conditions. In this chapter, we describe several step-by-step protocols for measuring mitochondrial respiration in intact cells, permeabilized cells (in situ mitochondria), and isolated organelles using both Clark-type polarographic oxygen electrode devices and the newly developed oxygen-sensing fluorophore-based Seahorse technology.
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Affiliation(s)
- Guillaume Vial
- INSERM U1042, Laboratoire Hypoxie-Physiopathologies cardiovasculaires et respiratoires HP2, Faculté de médecine et de pharmacie, Domaine de la merci, La Tronche, France
- Université Grenoble-Alpes, Laboratoire Hypoxie-Physiopathologies cardiovasculaires et respiratoires HP2, Faculté de médecine et de pharmacie, Domaine de la merci, La Tronche, France
| | - Bruno Guigas
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands.
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
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Abstract
Interest in the investigation of mitochondrial dysfunction has seen a resurgence over recent years due to the implication of such dysfunction in both drug-induced toxicity and a variety of disease states. Here we describe a methodology to assist in such investigations whereby the oxygen consumption of isolated mitochondria is assessed in a high-throughput fashion using a phosphorescent oxygen-sensitive probe , standard microtiter plates, and plate reader detection. The protocols provided describe the required isolation procedures, initial assay optimization, and subsequent compound screening. Typical data is also provided illustrating the expected activity levels as well as recommended plate maps and data analysis approaches.
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Affiliation(s)
| | - Rachel L Swiss
- Pfizer Global R&D, Compound Safety Prediction-WWMC, Cell Based Assays and Mitochondrial Biology, Groton, CT, USA
| | - Yvonne Will
- Pfizer Global R&D, Compound Safety Prediction-WWMC, Cell Based Assays and Mitochondrial Biology, Groton, CT, USA.
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Salvo LM, Malucelli MIC, da Silva JRMC, Alberton GC, Silva De Assis HC. Toxicity assessment of 2,4-D and MCPA herbicides in primary culture of fish hepatic cells. J Environ Sci Health B 2015; 50:449-455. [PMID: 25996808 DOI: 10.1080/03601234.2015.1018754] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this study, we used primary cultures of fish hepatic cells as a tool for evaluating the effects of environmental contamination. Primary hepatic cell cultures derived from the subtropical fish Metynnis roosevelti were exposed to different concentrations (0.275, 2.75 and 27.5 μg L(-1)) of the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA). Cellular respiratory activity was evaluated by polarography using three substrates: 0.5 M glucose, 0.5 M succinate and 0.5 M α-ketoglutarate. Significant changes were observed in cellular oxygen consumption with 0.5 M α-ketoglutarate. Even at low concentrations, 2,4-D and MCPA were potent uncouplers of oxidative phosphorylation. Primary cultures of M. roosevelti liver cells may provide a useful tool for the evaluation of environmental contaminant effects. A review of regulations regarding permitted concentrations of these herbicides is needed.
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Affiliation(s)
- Lígia M Salvo
- a Department of Cell and Developmental Biology , Institute of Biomedical Sciences, University of São Paulo , São Paulo, Brazil
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D'Avenio G, Poli C, Daniele C, Grigioni M. Oxygen permeability measurements of contact lenses: a proposal for accuracy improvement. Annu Int Conf IEEE Eng Med Biol Soc 2013; 2013:4730-4733. [PMID: 24110791 DOI: 10.1109/embc.2013.6610604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Contact lens are a widespread medical device. In view of the importance of a proper oxygenation of the cornea, new materials are continuously being tested, with a high permeability to oxygen. Taking into account the limitations of the methods for testing soft contact lenses, as presented in the relevant international standards, this paper focuses on the polarographic method and on the approach of measuring oxygen permeability of stacked contact lenses. The effect of the interspersed saline solution layers on the measurable permeability of the stack is considered, using Fick's law of diffusive flux, and a proposal for accuracy improvement in oxygen permeability measurements is presented.
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Abstract
A meanderline wave retarder is a unique type of frequency-selective-surface (FSS) that enables a change in the state of optical polarization. The principles of operation are very similar to a typical crystalline waveplate, such that the artificially structured meanderline array has both 'slow' and 'fast' axes that provide a phase offset between two orthogonal wave components. In this paper, we study the behavior and response of multilayered meanderline quarter-wave retarders designed for operation at 10.6 mum wavelength (28.28 THz). It will be shown that meanderline quarter-wave plates with more than a single layer exhibit improved transmission throughput at infrared frequencies due to impedance matching, similar to a multilayer optical film coating. Numerical data, both from simulations and measurements, are presented to validate this claim.
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Affiliation(s)
- Samuel L Wadsworth
- University of Central Florida, CREOL - The College of Optics and Photonics, Orlando, Florida 32816, USA.
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Pennings FA, Schuurman PR, van den Munckhof P, Bouma GJ. Brain tissue oxygen pressure monitoring in awake patients during functional neurosurgery: the assessment of normal values. J Neurotrauma 2009; 25:1173-7. [PMID: 18847378 DOI: 10.1089/neu.2007.0402] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Local brain tissue oxygen (ptiO2) monitoring is frequently applied in patients at risk for cerebral ischemia. To identify ischemic thresholds, the normal range of local brain tissue oxygen pressure (ptiO2) values needs to be established. Ideally, such normal values are determined in healthy and awake subjects, so as to eliminate the possible influences of anesthetics on cerebral physiology or ptiO2. Thus far, however, such measurements have not been conducted, and to fill this void, we determined the ptiO2 values in normal white matter of awake patients undergoing functional stereotactic brain surgery. In 25 otherwise healthy patients, who underwent functional neurosurgery for treatment of a refractory movement disorder under local anesthesia, the ptiO2 of white matter was recorded continuously using a polarographic Clark type electrode monitoring system. Preoperative screening ruled out cognitive dysfunction or structural cerebral lesions. Reliable intraoperative ptiO2 values were obtained in 22 patients. After an adaptation period of 118+/-35 min (range, 47-171 min), we found an average normal ptiO2 of 22.6+/-7.2 mm Hg in the frontal white matter. In 11 patients, ptiO2 measurements were continued postoperatively for 24 h. During this period, a similar normal ptiO2 value of 23.1+/-6.6 mm Hg was found. No iatrogenic complications occurred. In conclusion, the normal ptiO2 of cerebral white matter is most likely lower than previously assumed. Further, the long adaptation time renders this widely applied monitoring instrument unreliable in detecting ischemia early after insertion and limits its usefulness for intraoperative monitoring.
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Affiliation(s)
- Frederik A Pennings
- Division of Neurosurgery, University of Massachusetts Medical Center, Worcester, Massachusetts, USA
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Moneeb MS. Chemometric determination of rabeprazole sodium in presence of its acid induced degradation products using spectrophotometry, polarography and anodic voltammetry at a glassy carbon electrode. Pak J Pharm Sci 2008; 21:214-224. [PMID: 18614415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Chemometric stability indicating methods are presented for the determination of rabeprazole sodium in presence of its acid induced degradation products using spectrophotometry, differential pulse polarography and differential pulse anodic voltammetry at a glassy carbon electrode. The applied chemometric techniques are multivariate ones including classical least squares (CLS), principal component regression (PCR) and partial least squares (PLS). A difference spectrophotometric (DeltaA) method has also been applied. To develop the multivariate calibrations, a training set was used, consisting of 20 mixture solutions of rabeprazole sodium and its degradation products. These mixtures show percentage degradation ranging from 0.5-65%, 0.5-95% and 0.6-75% for the spectrophotometric, polarographic and anodic voltammetric calibrations, respectively. The UV absorbances were recorded in 0.1 M NaOH within the wavelength range 220-340 nm at 2 nm intervals. The polarograms and anodic voltammograms were recorded in Britton-Robinson buffer (pH 8.0) within the potential range -500 to -1508 and 400 to 1192 mV at 6 mV intervals with a pulse amplitude of -100 and 50 mV, sweep rate of 15 and 10 mV s(-1) and pulse interval of 0.4 and 0.6 s for the polarographic and anodic voltammetric methods, respectively. All the studied methods have been validated and successfully applied to the determination of rabeprazole sodium in tablet dosage form. The results were statistically compared to those obtained using a published HPLC method. No significant difference has been found.
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Affiliation(s)
- Marwa S Moneeb
- Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, University of Alexandria, Alexandria, Egypt.
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Chhabra M, Prausnitz JM, Radke CJ. A single-lens polarographic measurement of oxygen permeability (Dk) for hypertransmissible soft contact lenses. Biomaterials 2007; 28:4331-42. [PMID: 17659337 DOI: 10.1016/j.biomaterials.2007.06.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Accepted: 06/15/2007] [Indexed: 11/25/2022]
Abstract
A novel polarographic apparatus is described that requires only a single soft contact lens (SCL) to ascertain oxygen permeabilities of hypertransmissible lenses. Unlike conventional methods where a range of lens thickness is needed for determining oxygen permeabilities of SCLs, the apparatus described here requires only a single-lens thickness. This is accomplished by minimizing (or completely eliminating) edge effects, boundary-layer resistances, and lens desiccation in the polarographic apparatus. By taking these effects into account, we measure reliable oxygen permeabilities of hypertransmissible SCLs (i.e., above 100 barrer). Results are reported for nine commercial SCLs ranging in permeability from 9 to 180 barrer. Measured single-lens oxygen permeabilities are in excellent agreement with those claimed by commercial manufacturers. Our new single-lens permeameter provides a reliable, efficient, and economical method for measuring oxygen permeabilities of commercial SCLs. The single-lens method offers a potential international standard for measuring oxygen permeabilities of SCLs up to 250 barrer.
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Affiliation(s)
- Mahendra Chhabra
- Department of Chemical Engineering, University of California, Berkeley, CA 94720-1462, USA.
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Watanabe Y, Terashima Y, Takenaka N, Kobayashi M, Matsushita T. Prediction of avascular necrosis of the femoral head by measuring intramedullary oxygen tension after femoral neck fracture. J Orthop Trauma 2007; 21:456-61. [PMID: 17762476 DOI: 10.1097/bot.0b013e318126bb56] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To measure the intramedullary oxygen tension of the proximal femur after a femoral neck fracture and to evaluate the usefulness of that monitoring for prediction of subsequent avascular necrosis. DESIGN Prospective case series with comparison group. SETTING University hospital. INTERVENTION Measurement of intramedullary oxygen tension of the femoral head and neck during internal fixation using the Hansson hook-pin system. MAIN OUTCOME MEASUREMENTS Intramedullary oxygen tension was measured directly during surgery in 17 patients with 18 femoral neck fractures treated by internal fixation between October 2000 and February 2002. The intramedullary oxygen tension was measured by using polarographic oxygen electrodes and an oxygen monitor at four points: (A) 1 cm distal from the joint surface; (B) 1 cm proximal from the fracture site; (C) 1 cm distal from the fracture site; and (D) 1 cm proximal from the lateral wall. The presence or absence of avascular necrosis was evaluated by magnetic resonance imaging (MRI) at 2, 6, and 12 months after surgery. RESULTS MRI evaluation showed 11 fractures healed without complications, and 7 fractures developed avascular necrosis. We found significant differences in the distribution of intramedullary oxygen tension of the femoral head between points A (1 cm from the joint surface) and B (1 cm proximal from the fracture site) in those patients who developed avascular necrosis (P = 0.039); that is the oxygen tension was lower at point A than at point B. In contrast, in those patients who did not develop avascular necrosis there was no significant differences between point A and B were found (P = 0.059). The sensitivity and specificity for prediction of avascular necrosis were 1.0 and 0.82 (Fischer exact probability test, P = 0.002), respectively, when the cut-off level of oxygen tension differences between points A and B was set at 3.1 mm Hg. CONCLUSION We believe that this method of measuring intramedullary oxygen tension is simpler and less invasive than other currently used methods and has the possibility for intraoperatively identifying a risk group that can develop a late segmental collapse of the femoral head secondary to avascular necrosis.
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Affiliation(s)
- Yoshinobu Watanabe
- Department of Orthopaedic Surgery, Teikyo University School of Medicine, Tokyo, Japan.
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Miniaev MV, Voronchikhina LI. [Ambient air interference in oxygen intake measurements in liquid incubating media with the use of open polarographic cells]. Aviakosm Ekolog Med 2007; 41:64-8. [PMID: 17682509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
A model of oxygen intake by aerobic bio-objects in liquid incubating media was applied to investigate the influence air-media interface area on accuracy of measuring the oxygen intake and error value. It was shown that intrusion of air oxygen increases the relative error to 24% in open polarographic cells and to 13% in cells with a reduced interface area. Results of modeling passive media oxygenation laid a basis for proposing a method to reduce relative error by 66% for open cells and by 15% for cells with a reduced interface area.
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Grzelec-Mojzesowicz M, Sadowski J. Renal tissue NO and intrarenal haemodynamics during experimental variations of NO content in anaesthetised rats. J Physiol Pharmacol 2007; 58:149-63. [PMID: 17440233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Accepted: 02/02/2007] [Indexed: 05/14/2023]
Abstract
Direct renal nitric oxide (NO) measurements were infrequent and no simultaneous measurements of renal cortical and medullary NO and local perfusion. Large-surface NO electrodes were placed in renal cortex and medulla of anaesthetised rats; simultaneously, renal blood flow (RBF, index of cortical perfusion) and medullary laser-Doppler flux (MBF) were determined. NO synthase inhibitors: nonselective (L-NAME) or selective for neuronal NOS (nNOS) (S-methyl-thiocitrulline, SMTC), and NO donor (SNAP), were used to manipulate tissue NO. Baseline tissue NO was significantly higher in medulla (703+/-49 NM) than in cortex (231+/-17 nM). Minimal cortical and medullary NO current measured after maximal L-NAME dose (2.4 mg kg(-1) i.v.) was taken as tissue NO zero kevel. This dose decreased RBF and MBF significantly (-43%). SMTC, 1.2 mg kg(-1) h(-1) i.v., significantly decreased tissue NO by 105+/-32 nM in cortex and 546+/-64 nM in medulla, RBF and MBF decreased 30% and 20%, respectively. Renal artery infusion of SNAP, 0.24 mg kg(-1) min(-1) significantly increased tissue NO by 139+/-18 nM in cortex and 948+/-110 nM in medulla. Since inhibition of nNOS decreased medullary NO by 80% and MBF by 20% only, this isoform has probably minor role in the maintenance of medullary perfusion.
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Affiliation(s)
- M Grzelec-Mojzesowicz
- Laboratory of Renal and Body Fluid Physiology, M. Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
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Tutunji MF, Qaisi AM, El-Eswed BI, Tutunji LF. Reactions of Sulfenic Acid with 2-Mercaptoethanol: A Mechanism for the Inhibition of Gastric (H+−K+)-Adenosine Triphosphate by Omeprazole. J Pharm Sci 2007; 96:196-208. [PMID: 16998872 DOI: 10.1002/jps.20588] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The reactions of omeprazole, a potent proton pump inhibitor (PPI) were investigated in the presence of 2-mercapotoethanol. Reactions were monitored in solutions buffered to pH values ranging 2.0-8.0 using differential pulse polarography (DPP) at the static mercury drop electrode (SMDE). The fast, sensitive and selective electrochemical technique facilitated successive recordings of voltammograms (peak current (nA) vs. peak potential (volts vs. Ag/AgCl)) for all analytes in situe, including the 2-mercaptoethanol. In acidic solutions and in the presence of 2-mercaptoethanol, omeprazole undergoes degradation into three compounds, the first is a cyclic sulfenamide (D+), previously believed to be the active inhibitor of the H+, K+-ATPase, the second is the omeprazole dimer, and the third is the disulfide believed to be the product of reaction between 2-mercaptoethanol and D+. The cyclic sulfenamide (D+) solution was found to be stable in solutions containing 2-mercaptoethanol having pH values: 2.0, 4.0, and 6.0. This finding proved conclusively that the cyclic sulfenamide is not reactive toward the 2-mercaptoethanol. In contrast to previous reports, the conversion of the sulfenic acid intermediate into D+ was found to be irreversible. Due to this irreversibility, D+ and sulfenic acid were not rapidly interconvertable. The present work suggests that the active inhibitor is the sulfenic acid.
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Affiliation(s)
- Maha F Tutunji
- Department of Chemistry, Faculty of Science, University of Jordan, Amman-Jordan.
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Fink B, Hill RM. Corneal oxygen uptake: A review of polarographic techniques, applications, and variables. Cont Lens Anterior Eye 2006; 29:221-9. [PMID: 17052949 DOI: 10.1016/j.clae.2006.09.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Revised: 09/08/2006] [Accepted: 09/15/2006] [Indexed: 11/23/2022]
Abstract
Factors that influence the polarographic measurement of the oxygen uptake of the cornea are reviewed. These factors include the technique, electrode assembly, oxygen reservoir, membrane material and thickness, oxygen tension of the corneal environment, duration of exposure to environmental conditions and time to application of the probe all influencing measured oxygen uptake rates. Subject factors include lid position, palpebral aperture size, blinking, corneal thickness, and corneal integrity. Contact lens wear influences corneal oxygen uptake, with lens material and design parameters influencing rates obtained both under static (without blinking) and dynamic (with blinking) conditions. Measurement of corneal oxygen uptake rates remains an excellent method to quantify the oxygen supply in contact lens systems that include the contact lens, the tears, and the cornea, in which oxygen flux is influenced by the thickness and diffusion characteristics of each component.
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Affiliation(s)
- Barbara Fink
- The Ohio State University, College of Optometry, 338 West Tenth Avenue, Columbus, OH 43210-1240, USA.
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Degn H, Lundsgaard JS, Petersen LC, Ormicki A. Polarographic measurement of steady state kinetics of oxygen uptake by biochemical samples. Methods Biochem Anal 2006; 26:47-77. [PMID: 6248721 DOI: 10.1002/9780470110461.ch2] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Alsarra I, Al-Omar M, Gadkariem EA, Belal F. Voltammetric determination of montelukast sodium in dosage forms and human plasma. ACTA ACUST UNITED AC 2006; 60:563-7. [PMID: 15925367 DOI: 10.1016/j.farmac.2005.04.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2004] [Revised: 04/04/2005] [Accepted: 04/04/2005] [Indexed: 11/17/2022]
Abstract
The voltammetric behaviour of montelukast (MKST) was studied using cyclic voltammetry, direct current (DCt), differential pulse polarography (DPP) and alternating current (ACt) polarography. MKST exhibited well-defined cathodic waves over the range pH range 1-5. No anodic waves were produced over the same pH range. At pH 1, the analytical pH; the diffusion current constant (Id) was 2.2+/-0.01 microA l mmol-1. The current concentration plot was rectilinear over the range 2-20 microg ml-1 with correlation coefficient (n=10) of 0.9943. The lower limit of detection (S/N=2) was 0.2 microg ml-1 (3.41x10(-7) M). The wave has been characterised as being diffusion-controlled, although adsorption phenomenon played a limited role in the electrode reaction. The proposed method was successfully applied to the determination of MKST in commercial tablets, and results were in agreement with those given with a reference HPLC method. The method was further extended to the in vitro determination of the drug in spiked human plasma. The mean % recovery (n=5) was 101.38+/-3.85. The number of electrons transferred in the reduction process could be accomplished and a proposal of the electrode reaction was proposed.
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Affiliation(s)
- I Alsarra
- Department of Pharmaceutics, Faculty of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451, Saudi Arabia
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Bjerrum JT, Perko MJ, Beck B. Myocardial oxygen tension during surgical revascularization.☆A clinical comparison between blood cardioplegia and crystalloid cardioplegia. Eur J Cardiothorac Surg 2006; 29:181-5. [PMID: 16387508 DOI: 10.1016/j.ejcts.2005.11.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2005] [Revised: 11/18/2005] [Accepted: 11/23/2005] [Indexed: 11/28/2022] Open
Abstract
OBJECTIVE The aim of this study was to assess the effect of cardioplegic solutions on myocardial oxygenation during surgical revascularization. METHODS In 30 patients, randomized to receive crystalloid (CC) or blood (BC) cardioplegia, myocardial oxygen tension was measured continuously by polarography. RESULTS The two groups were comparable in terms of patients' age, sex, pre-operative ejection fraction, coronary disease, perfusion time, and aorta cross-clamping time. However, the BC group required 22% more of cardioplegic solution to stop electrical activity of the heart. Throughout the pre- and post-cardiac arrest periods, oxygen tension between the two groups was similar. At the end of the observation (4th day), myocardial oxygenation increased over 200% in relation to the values before revascularization. During the first infusion of cardioplegia, oxygen tension in the CC group was lower compared to the BC group (0.1 mmHg vs 1.3 mmHg; P<0.05) being the only significant difference between the two groups during cardiac arrest. Throughout the cardiac arrest, myocardial oxygen tension was close to zero regardless of the type of cardioplegia used. Post-operatively, addition of oxygen to the respiratory air increased myocardial oxygenation by over 17% resulting in a positive correlation (r=0.94; P<0.05) between myocardial oxygen tension and peripheral saturation. CONCLUSIONS In conclusion, the differences in myocardial oxygen tension between the CC and BC groups are trivial. Thus, any potential beneficial effect of blood cardioplegia compared to crystalloid cardioplegia must be due to other circumstances than its oxygen carrying capacity. An important observation is a significant increase in myocardial oxygenation during oxygen supplement to the respiratory air.
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Affiliation(s)
- Jacob T Bjerrum
- Department of Cardiothoracic Surgery 2152, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
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Maurer P, Meyer L, Eckert AW, Berginski M, Schubert J. Measurement of oxygen partial pressure in the mandibular bone using a polarographic fine needle probe. Int J Oral Maxillofac Surg 2005; 35:231-6. [PMID: 16185845 DOI: 10.1016/j.ijom.2005.07.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2004] [Revised: 04/12/2005] [Accepted: 07/20/2005] [Indexed: 11/28/2022]
Abstract
In this study, the oxygen partial pressure in the cancellous bone substance of the mandible was measured for the first time with a polarographic fine needle probe. This has so far only been established in soft tissue. The aim was to prove and to test the feasibility in principle of this method of measurement in order to ascertain the normal values for the O2 partial pressure in healthy bone. These values were afterwards compared with the results of measurements in areas of different pathological bone conditions in order to assess the clinical suitability of the method for "mapping" during mandibular resection. Measurements of oxygen partial pressure were made in a total of 42 patients (16 women, 26 men). Of these, 12 patients with clinically normal bones served as a control group. Seventeen patients had osteoradionecrosis following radiation treatment, and 13 patients presented with chronic osteomyelitis of the mandible. All measurements were carried out with a polarographic fine needle probe applied to the cancellous bone substance. The statistical analysis included a comparison of the mean values of the oxygen partial pressures measured. No statistical correlation between oxygen partial pressure and pH and hemoglobin values could be detected. The average oxygen partial pressure in the healthy mandibular bone was 71.4 mmHg. In non-healthy bone, the value fell to an average of 30.6 mmHg (osteoradionecrosis 32.3 mmHg, chronic osteomyelitis of the mandibular bone 28.4 mmHg). Statistically, the differences in the group values ascertained were highly significant (P < 0.005). The data found show that this method can be successfully used to detect poorly perfused bone. The values are reproducible and reflect the clinical situation. In the long term, the method appears to be a suitable diagnostic tool for assessing the oxygen supply in bone in studying various clinical problems related to bone surgery.
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Affiliation(s)
- P Maurer
- Klinik und Poliklinik für Mund-Kiefer- und Plastische Gesichtschirurgie, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Strasse 40, D-06097 Halle, Germany.
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Ali JH, Wang WB, Zevallos M, Alfano RR. Near infrared spectroscopy and imaging to probe differences in water content in normal and cancer human prostate tissues. Technol Cancer Res Treat 2005; 3:491-7. [PMID: 15453814 DOI: 10.1177/153303460400300510] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The content of water in cancerous and normal human prostate in vitro tissues was shown to be different using near infrared (NIR) spectroscopy. The water absorption peaks at 1444 nm and 1944 nm are observed in both types of prostate tissues. The measurements show that less water is contained in cancerous tissues than in normal tissues. The OH stretching vibrational overtone mode at 1444 nm and other water overtone modes provide key spectroscopic fingerprints to detect cancer in prostate tissue. Transmission and backscattered spectral imaging were measured in cancer and normal prostate tissues. The degree of polarization for 700 nm, 800 nm, 1200 nm, and 1450 nm is larger for normal than for cancer tissues. The knowledge about water content offers a potential as a diagnostic tool to better determine and image cancer in prostate and in other tissues types such as breast and cervix using the absorption from vibrational overtones of H(2)O molecules in the NIR.
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Affiliation(s)
- J H Ali
- Institute for Ultrafast Spectroscopy and Lasers and The New York State Center for Advanced Technology for Ultrafast Photonics Materials and Applications, City University of New York, New York, NY 10031, USA
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22
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Kraus DW, Doeller JE. Sulfide consumption by mussel gill mitochondria is not strictly tied to oxygen reduction: measurements using a novel polarographic sulfide sensor. J Exp Biol 2004; 207:3667-79. [PMID: 15371475 DOI: 10.1242/jeb.01212] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
SUMMARYSome organisms that survive in environments rich in hydrogen sulfide possess specific metabolic pathways for sulfide oxidation and subsequent use of reducing equivalents in oxidative phosphorylation, a process called chemolithoheterotrophy. This process is dependent on ambient oxygen partial pressure and environmental sulfide exposure. To define accurately the kinetics of sulfide metabolism and its dependence on cellular conditions, we have developed a polarographic sulfide sensor (PSS) to measure sulfide concentrations directly and continuously under physiological conditions.The ribbed mussel Geukensia demissa, an inhabitant of sulfide-rich coastal sediments, consumes sulfide in a chemolithoheterotrophic metabolic strategy. Gill mitochondria use sulfide as respiratory substrate for ATP production, and sulfide consumption is sufficiently rapid and so kinetically complex that only continuous real-time detection captures these events. Under normoxic conditions, oxygen and sulfide consumption are matched. Under hypoxic to anoxic conditions, however, sulfide consumption continues without commensurate oxygen consumption, and these results can be duplicated at higher oxygen conditions by selective blockade of terminal oxidases. These metabolic capabilities depend on prior environmental sulfide exposure, which suggests substantial mitochondrial metabolic plasticity. The recent finding that endogenous sulfide is a critical cell signaling molecule in all organisms suggests that the metabolic pathways that tightly control cellular sulfide levels are widespread. Sensors that accurately report sulfide concentrations under physiologically relevant conditions are valuable tools with which to explore the expanding role of sulfide in biological systems.
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Affiliation(s)
- David W Kraus
- Department of Biology, University of Alabama at Birmingham, 1300 University Boulevard, Birmingham. AL 35294-1170, USA.
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Abstract
A polarimetric assay has been developed for the identification of alpha-amino acid racemase activity. The setup consists of a microcuvette polarimeter (40 microL volume) connected to a pipetting robot for microtiter plates, a pump, and data processing. It could be demonstrated for a glutamate racemase from Lactobacillus fermentii, expressed in Escherichia coli, serving as model enzyme, that its activity can be determined from the time-dependent change of the optical rotation using l-glutamate as substrate. Thus, the specific activity was determined to 111.4 mdeg/min which corresponds to 45.7 micromol/min per mg purified enzyme. Moreover, a protocol was developed that allows the measurement of racemase activity from 96-well microtiter plates using purified enzymes. Thus, the method described can be used to determine racemase activity in an automatic manner. It should be also applicable for the screening of enzyme libraries created by directed evolution.
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Affiliation(s)
- Dorian L Schönfeld
- Institute of Chemistry & Biochemistry, Department of Technical Chemistry & Biotechnology, Ernst-Moritz-Arndt-University Greifswald, Soldmannstrasse 16, D-17487 Greifswald, Germany
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Rollins MD, Conrad MB, Hunt TK, Hopf HW. Accuracy of a polarographic electrode at high oxygen concentrations. Adv Exp Med Biol 2003; 510:169-73. [PMID: 12580423 DOI: 10.1007/978-1-4615-0205-0_28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mark D Rollins
- Bioengineering Graduate Group, University of California, San Francisco, CA, USA
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Affiliation(s)
- David K Harrison
- Regional Medical Physics Department, Durham Unit, University Hospital of North Durham, North Road, Durham DH1 5TW, UK
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Littlejohns LR, Bader MK, March K. Brain tissue oxygen monitoring in severe brain injury, I. Research and usefulness in critical care. Crit Care Nurse 2003; 23:17-25; quiz 26-7. [PMID: 12961780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
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Sharma HA, Balcavage WX, Waite LR, Johnson MT, Nindl G. Characterization of a real time H2O2 monitor for use in studies on H2O2 production by antibodies and cells. Biomed Sci Instrum 2003; 39:554-60. [PMID: 12724951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
It was recently shown that antibodies catalyze a reaction between water and ultraviolet light (UV) creating singlet oxygen and ultimately H2O2. Although the in vivo relevance of these antibody reactions is unclear, it is interesting that among a wide variety of non-antibody proteins tested, the T cell receptor is the only protein with similar capabilities. In clinical settings UV is believed to exert therapeutic effects by eliminating inflammatory epidermal T cells and we hypothesized that UV-triggered H2O2 production is involved in this process. To test the hypothesis we developed tools to study production of H2O2 by T cell receptors with the long-term goal of understanding, and improving, UV phototherapy. Here, we report the development of an inexpensive, real time H2O2 monitoring system having broad applicability. The detector is a Clark oxygen electrode (Pt, Ag/AgCl) modified to detect UV-driven H2O2 production. Modifications include painting the electrode black to minimize UV effects on the Ag/AgCl electrode and the use of hydrophilic, large pore Gelnots electrode membranes. Electrode current was converted to voltage and then amplified and recorded using a digital multimeter coupled to a PC. A reaction vessel with a quartz window was developed to maintain constant temperature while permitting UV irradiation of the samples. The sensitivity and specificity of the system and its use in cell-free and cell-based assays will be presented. In a cellfree system, production of H2O2 by CD3 antibodies was confirmed using our real time H2O2 monitoring method. Additionally we report the finding that splenocytes and Jurkat T cells also produce H2O2 when exposed to UV light.
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MESH Headings
- Animals
- Antibodies/analysis
- Antibodies/metabolism
- Antibodies, Catalytic/chemistry
- Antibodies, Catalytic/metabolism
- Antibodies, Catalytic/radiation effects
- CD3 Complex/metabolism
- CD3 Complex/radiation effects
- Calibration
- Cell-Free System/metabolism
- Electrodes
- Equipment Design
- Humans
- Hydrogen Peroxide/analysis
- Hydrogen Peroxide/metabolism
- Jurkat Cells/metabolism
- Jurkat Cells/radiation effects
- Male
- Membranes, Artificial
- Oxidation-Reduction
- Polarography/instrumentation
- Rats
- Rats, Sprague-Dawley
- Receptors, Antigen, T-Cell/chemistry
- Receptors, Antigen, T-Cell/metabolism
- Receptors, Antigen, T-Cell/radiation effects
- Sensitivity and Specificity
- Spleen/chemistry
- Spleen/metabolism
- Spleen/radiation effects
- Temperature
- Ultraviolet Rays
- Water/chemistry
- Water/metabolism
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Affiliation(s)
- Harish A Sharma
- Rose-Hulman Institute of Technology, Terre Haute, IN 47803, USA
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Abstract
The anodic polarographic behavior of ciclopirox have been studied in Britton Robinson buffer (BRb) over the pH range 6-11. In BRb of pH 7 a well defined anodic wave was produced with diffusion current constant (Id) of 4.86+/-0.048 (n=6) using DC(t) mode. Adopting both of direct current (DC(t)) and differential pulse polarographic (DPP) modes, the current-concentration relationship was found to be rectilinear over the range 4 to 24 and 2 to 12 microg ml(-1) respectively, with minimum detectability (S/N=2) of 0.2 microg ml(-1) (1 x 10(-6) M) using the DPP mode. The average percent recovery was favourably compared to a reference method, with a satisfactory standard deviation, the proposed method was further applied to the determination of ciclopirox olamine in certain pharmaceutical preparations including lotion and cream. The average percentage recoveries for lotion were 100.06+/-0.94 and 100.06+/-1.08 using DC(t) and DPP modes respectively, and for cream were 100.17+/-0.64 and 100.34+/-1.28 using DC(t) and DPP modes, respectively. A pathway for the electrode reaction was postulated.
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Affiliation(s)
- F Ibrahim
- Department of Analytical Chemistry, Faculty of Pharmacy, University of Mansoura, Mansoura 35516, Egypt.
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Doll CM, Milosevic M, Pintilie M, Hill RP, Fyles AW. Estimating hypoxic status in human tumors: a simulation using Eppendorf oxygen probe data in cervical cancer patients. Int J Radiat Oncol Biol Phys 2003; 55:1239-46. [PMID: 12654433 DOI: 10.1016/s0360-3016(02)04474-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
PURPOSE To define the minimal number of pO(2) measurements, with 90% sensitivity and 90% specificity, needed to categorize cervical tumors as either hypoxic or oxic. METHODS AND MATERIALS Using Eppendorf oxygen probe data from our ongoing prospective trial, we simulated the measurement of tumor oxygenation with a smaller number of data points in 135 patients with cervical cancer. The hypoxic proportion, defined as the percentage of pO(2) values <5 mm Hg (HP5), was calculated for each tumor. Hypoxic tumors were defined as those with a median HP5 >50%, and tumors with normal oxygen levels as those with a median HP5 < or =50%. A small number of pO(2) measurements were randomly selected from the Eppendorf measurements in each tumor, or per Eppendorf track, and used to define the tumor as hypoxic or oxic. The sensitivity and specificity were calculated, considering the classification as given by the complete set of Eppendorf measurements as the reference standard. RESULTS The probability of falsely classifying the tumor decreased as the selected number of pO(2) measurements per tumor increased, and at 16 measurements was approximately 10%. Adding additional measurements per tumor beyond 24 improved the ability to classify the tumor accurately only slightly. The probability of falsely classifying the tumor decreased as the pO(2) measurements per track increased. At five measurements per track, the probability of falsely classifying the tumor was approximately 9%. CONCLUSION Approximately 20 measurements per tumor, or five measurements per track, using the Eppendorf pO(2) histograph, are sufficient to categorize cervical tumors as hypoxic or oxic. The results of this study will serve as a guide for research clinicians in the use of this and other systems in the assessment of tumor oxygenation in humans.
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Affiliation(s)
- Corinne M Doll
- Department of Radiation Oncology, Princess Margaret Hospital, University Health Network and University of Toronto, Toronto, Ontario, Canada
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30
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Abstract
OBJECTIVE In coronary artery bypass surgery various parameters have been used to monitor patients clinical status. Direct monitoring of myocardial oxygenation can be performed by measuring intramyocardial partial oxygen tension pressure (p ti O2). This study was performed to determine the perioperative time course of this parameter in correlation to standard monitoring parameters. METHODS Twenty-three patients underwent standard coronary artery bypass grafting (CABG). A special polarographic microprobes was inserted into the myocardium in the distribution zone of the left anterior descending artery which was one of the target vessels of myocardial revascularization. Intramyocardial p ti O2 was monitored intra- and up to 12 hours postoperatively. Values were correlated to hemodynamic, oxygenation and procedure associated parameters. RESULTS Myocardial oxygenation during CABG is characterized by a significant decrease of p ti O2 during cross-clamping and a significant increase after removal of the cross-clamp. The postoperative time course of p ti O2 shows a steady increase of p ti O2 in the first 12 postoperative hours investigated. Preoperative ejection fraction as well as cardio-pulmonary bypass time does not seem to have an influence on the postoperative p ti O2 in these patients. Various standard monitoring parameters show complex influence on intramyocardial p ti O2- CONCLUSIONS Determination of intramyocardial partial oxygen pressure in patients undergoing bypass surgery shows characteristic changes. Changes in p ti O2 as a direct online parameter of myocardial oxygenation occur immediately after procedures that influence myocardial perfusion and therefore, may help to detect potential complications earlier than standard monitoring parameters in cardiac surgery.
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Affiliation(s)
- Martin Misfeld
- Clinic of Cardiac Surgery, University Clinic Schleswig-Holstein, Campus Luebeck, Luebeck, Germany
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31
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Matloob MH. Determination of cadmium, lead, copper and zinc in Yemeni khat by anodic stripping voltammetry. East Mediterr Health J 2003; 9:28-36. [PMID: 15562730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
Trace element concentrations in khat were investigated as they can disturb trace element levels in the body. Cadmium (Cd), lead (Pb), copper (Cu) and zinc (Zn) levels in khat and 6 leafy vegetables commonly consumed in the Republic of Yemen were determined by differential pulse anodic stripping voltammetry after wet digestion of the organic matter. Khat had significantly higher concentrations of Cu and Zn than did the leafy vegetables, but similar amounts of Cd and Pb. The average daily intake of khat consumers of Cd, Pb, Cu and Zn from khat only was estimated to be 2.0-10.2 microg/day, 23.6-118.0 microg/day, 530-2654 microg/day and 662-3311 microg/day respectively. Although high, these values were within Food and Agriculture Organization/World Health Organization tolerance limits.
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Affiliation(s)
- M H Matloob
- Department of Chemistry, College of Science for Girls, University of Babylon, Babylon, Iraq
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Braun RD, Lanzen JL, Snyder SA, Dewhirst MW. Comparison of tumor and normal tissue oxygen tension measurements using OxyLite or microelectrodes in rodents. Am J Physiol Heart Circ Physiol 2001; 280:H2533-44. [PMID: 11356608 DOI: 10.1152/ajpheart.2001.280.6.h2533] [Citation(s) in RCA: 194] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study we compare oxygen tension (Po 2) histograms measured with O2 microelectrodes and a new optical Po 2 measurement device, the OxyLite, in normal tissues (mouse spleen and thymus) and in tumors (R3230Ac in rats) ( n = 5–6). The transient response to glucose infusion or 100% O2 breathing (hyperoxia) was also measured in tumors. Po 2 histograms of spleen and thymus with the two devices were not different. The OxyLite tumor Po 2 histogram, however, was left-shifted compared with the microelectrode (median Po 21.0 vs. 4.0 mmHg, P = 0.016). Both probes responded to acute hyperglycemia with a mean increase of 3–6 mmHg, but the microelectrode change was not significant. The OxyLite consistently recorded large Po 2 increases (∼28 mmHg) with hyperoxia, whereas the microelectrode response was variable. The OxyLite averages Po 2 over an area that contains interstitial and vascular components, whereas the microelectrode measures a more local Po 2. This study demonstrates the importance of considering the features of the measurement device when studying tissues with heterogeneous Po 2 distributions (e.g., tumors).
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Affiliation(s)
- R D Braun
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Abstract
A micro-polarimeter with a 40 nL probe volume was configured so that it is compatible with capillary-scale flowing stream analysis. The optical configuration consists of two polarizing optics, a capillary, a laser source and a photodetector which is very simple to configure with low cost components. This unique polarimeter is based upon the interaction of a linearly polarized laser beam and a capillary tube, in this case one with an inner diameter of 250 microns. Side illumination of the tube results in a 360 degrees fan of scattered light, which contains a set of interference fringes that change in response to optically active solutes. Solutes that exhibit optical activity are quantifiable and are detected by analyzing the polarization state of the backscattered light. The ability of the instrument to make extremely sensitive optical activity measurements in flowing streams is shown by the determination of (R)-mandelic acid, with a detection limit of 66 x 10(-6) M (507 x 10(-12) g), and the non-optically active control, glycerol. Additionally, the detector was configured to minimize refractive index perturbations.
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Affiliation(s)
- K Swinney
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, USA
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Kumar SM, Porterfield DM, Muller KJ, Smith PJ, Sahley CL. Nerve injury induces a rapid efflux of nitric oxide (NO) detected with a novel NO microsensor. J Neurosci 2001; 21:215-20. [PMID: 11150338 PMCID: PMC6762443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
An early step in repair of the leech CNS is the appearance of endothelial nitric oxide synthase (eNOS) immunoreactivity and NOS activity, but coincident generation of NO at the lesion after injury has not been shown. This is important because NO can regulate microglial cell motility and axon growth. Indirect measurement of NO with the standard citrulline assay demonstrated that NO was generated within 30 min after nerve cord injury. A polarographic NO-selective self-referencing microelectrode that measures NO flux noninvasively was developed to obtain higher spatial and temporal resolution. With this probe, it was possible to demonstrate that immediately after the leech CNS was injured, NO left the lesion with a mean peak efflux of 803 +/- 99 fmol NO cm(-2) sec(-1). NO efflux exponentially declined to a constant value, as described through the equation f(t) = y(o) + ae(-t/tau), with tau = 117 +/- 30 sec. The constant y(o) = 15.8 +/- 4.5 fmol cm(-2) represents a sustained efflux of NO. Approximately 200 pmol NO cm(-2) is produced at the lesion (n = 8). Thus, injury activates eNOS already present in the CNS and precedes the accumulation of microglia at the lesion, consistent with the hypothesis that NO acts to stop the migrating microglia at the lesion site.
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Affiliation(s)
- S M Kumar
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA
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Abstract
OBJECTIVES To use recently introduced polarographic technology to characterize the distribution of oxygenation in solid tumors, explore the differences between severe hypoxia and true necrosis, and evaluate the ability to predict treatment outcomes based on tumor oxygenation. STUDY DESIGN Prospective, nonrandomized trial of patients with advanced head and neck cancer, conducted at an academic institution. METHODS A total of 63 patients underwent polarographic oxygen measurements of their tumors. Experiment 1 was designed to determine whether a gradient of oxygenation exists within tumors by examining several series of measurements in each tumor. Experiment 2 was an analysis of the difference in data variance incurred when comparing oxygen measurements using oxygen electrodes of two different sizes. Experiment 3 compared the proportion of tumor necrosis to the proportion of very low (< or =2.5 mm Hg) polarographic oxygen measurements. Experiment 4 was designed to explore the correlation between oxygenation and treatment outcomes after nonsurgical management. RESULTS No gradient of oxygenation was found within cervical lymph node metastases from head and neck squamous cell carcinomas (P > .9). Tumor measurements achieved with larger (17 microm) electrodes displayed smaller variances than those obtained with smaller (12 microm) electrodes, although this difference failed to reach statistical significance (P = .60). There was no correlation between tumor necrosis and the proportion of very low (< or =2.5 mm Hg) oxygen measurements. There was a nonsignificant trend toward poorer locoregional control and overall survival in hypoxic tumors. CONCLUSIONS Hypoxia exists within cervical lymph node metastases from head and neck squamous carcinomas, but the hypoxic regions are distributed essentially randomly. As expected, measurements of oxygen achieved with larger electrodes results in lowered variance, but with no change in overall tumor mean oxygen levels. Polarographic oxygen measurements are independent of tumor necrosis. Finally, oxygenation as an independent variable is incapable of predicting prognosis, probably reflecting the multifactorial nature of the biological behavior of head and neck cancers.
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Affiliation(s)
- D J Terris
- Division of Otolaryngology-Head and Neck Surgery, Stanford University Medical Center, California 94305, USA
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Baumgärtl H, Zimelka W, Lübbers DW. Simultaneous measurements of mechanical pressure and oxygen pressure during puncturing of semisolid polymeric networks by polarographic needle electrodes. Adv Exp Med Biol 2000; 471:613-22. [PMID: 10659195 DOI: 10.1007/978-1-4615-4717-4_71] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Affiliation(s)
- H Baumgärtl
- Max-Planck-Institut für Molekulare Physiologie, Dortmund, Germany
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Affiliation(s)
- B Uslu
- Department of Analytical Chemistry, Faculty of Pharmacy, Ankara University, Turkey
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Swinney K, Hankins J, Bornhop DJ. Laser-based capillary polarimeter. J Capill Electrophor Microchip Technol 1999; 6:93-6. [PMID: 11315158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
A laser-based capillary polarimeter has been configured to allow for the detection of optically active molecules in capillary tubes with a characteristic inner diameter of 250 microm and a 39-nL (10(-9)) sample volume. The simple optical configuration consists of a HeNe laser, polarizing optic, fused-silica capillary, and charge-coupled device (CCD) camera in communication with a laser beam analyzer. The capillary scale polarimeter is based on the interaction between a polarized laser beam and a capillary tube, which results in a 360 degree fan of scattered light. This array of scattered light contains a set of interference fringe, which respond in a reproducible manner to changes in solute optical activity. The polarimetric utility of the instrument will be demonstrated by the analysis of two optically active solutes, R-mandelic acid and D-glucose, in addition to the nonoptically active control, glycerol. The polarimetric response of the system is quantifiable with detection limits facilitating 1.7 x 10(-3) M or 68 x 10(-12) nmol (7 psi 10(-9) g) sensitivity.
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Affiliation(s)
- K Swinney
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock 79409-1061, USA
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Manley GT, Pitts LH, Morabito D, Doyle CA, Gibson J, Gimbel M, Hopf HW, Knudson MM. Brain tissue oxygenation during hemorrhagic shock, resuscitation, and alterations in ventilation. J Trauma 1999; 46:261-7. [PMID: 10029031 DOI: 10.1097/00005373-199902000-00011] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES Recently developed polarographic microelectrodes permit continuous, reliable monitoring of oxygen tension in brain tissue (PbrO2). The aim of this study was to investigate the feasibility and utility of directly monitoring PbrO2 in cerebral tissue during changes in oxygenation or ventilation and during hemorrhagic shock and resuscitation. We also sought to develop a model in which treatment protocols could be evaluated using PbrO2 as an end point. METHODS Licox Clark-type polarographic probes were inserted in the brain tissue of 16 swine to monitor PbrO2. In eight swine, changes in PbrO2 were observed over a range of fractional concentrations of inspired O2 (FiO2) as well as during periods of hyperventilation and hypoventilation. In eight other swine, PbrO2 was monitored during a graded hemorrhage of up to 70% estimated blood volume and during the resuscitation period. RESULTS When FiO2 was elevated to 100%, PbrO2 increased from a baseline of 15+/-2 mm Hg to 36+/-11 mm Hg. Hyperventilation while breathing 100% oxygen resulted in a 40% decrease in PbrO2 (p < 0.05), whereas hypoventilation increased PbrO2 to 88 mm Hg (p < 0.01). A graded hemorrhage to 50% estimated blood volume significantly reduced PbrO2, mean arterial pressure, and intracranial pressure (p < 0.01). Continued hemorrhage to 70% estimated blood volume resulted in a PbrO2 of 2.9+/-1.5 mm Hg. After resuscitation, PbrO2 was significantly elevated, reaching 65+/-13 mm Hg (p < 0.01), whereas mean arterial pressure and cerebral perfusion pressure simply returned to baseline. CONCLUSION Directly measured PbrO2 was highly responsive to changes in FiO2, ventilatory rate, and blood volume in this experimental model. In particular, hypoventilation significantly increased PbrO2, whereas hyperventilation had the opposite effect. The postresuscitation increase in PbrO2 may reflect changes in both O2 delivery and O2 metabolism. These experiments set the stage for future investigations of a variety of resuscitation protocols in both normal and injured brain.
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Affiliation(s)
- G T Manley
- School of Medicine, University of California San Francisco, Department of Neurological Surgery, San Francisco General Hospital, 94110, USA
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Sherman RT. Necessity is the mother of invention. Arch Surg 1999; 134:104. [PMID: 9927142 DOI: 10.1001/archsurg.134.1.104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Abstract
OBJECTIVE We assessed the technical and diagnostic reliability of partial pressure of oxygen (PO2) of brain tissue (P(ti)O2) monitoring. The monitoring system and the catheter probes were tested in vitro, and clinical experiences obtained with 118 brain P(ti)O2 catheter probes, used in 101 patients, are reported. METHODS The polarographic (LICOX; Medical Systems Corp., Greenvale, NY) P(ti)O2 catheter probe lies 22 to 27 mm below the dura level; its PO2-sensitive surface is 7.1 mm2. For 10 patients, the adaptation time (with initially unreliable signals after insertion) was determined. For 27 patients, the probe was removed in a stepwise fashion (three increments of 5 mm) and the heterogeneity of brain P(ti)O2 levels was investigated. After removal of the catheter probes, their PO2 and zero display error values were determined and compared with probe performance data obtained in vitro with unused PO2 catheter probes. RESULTS Small iatrogenic hematomas were observed for two patients (1.7%). No infection occurred after 6.7 +/- 3.9 days (mean +/- standard deviation) of monitoring. The technical complication (dislocation or defect) rate was 13.6%. The mean adaptation time was 79.0 +/- 51.7 min. A flow chart is presented, which helps to rule out artifacts. The mean P(ti)O2 measured at 22 to 27 mm below the dura was 23.8 +/- 8.1 mm Hg, at 17 to 22 mm was 25.7 +/- 8.3 mm Hg, at 12 to 17 mm was 33.0 +/- 13.3 mm Hg (P < 0.01, compared with the initial value), and at 7 to 12 mm was 33.3 +/- 13.3 mm Hg (P < 0.01). Recent catheter probe versions exhibited a PO2 display error of -1.2 +/- 5.1% (mean +/- standard deviation, n = 38) and a mean zero display error of 1.1 +/- 0.9 mm Hg (n = 34). The greatest PO2 display errors were measured during the first 4 days of continuous monitoring. In the in vitro test (of 12 unused catheter probes), the maximal probe display error was 1.07 +/- 2.14%, tested at temperatures between 22 degrees C and 37 degrees C and tested at oxygen pressures of 0, 44, and 150 mm Hg. In vitro, the zero display error was -0.21 +/- 0.25 mm Hg. CONCLUSION Brain P(ti)O2 monitoring, reflecting an area 17 to 27 mm below the dura, is a safe and reliable technique for monitoring cerebral oxygenation. Excluding the first 1 hour after insertion, data are reliable, with almost 100% good data quality.
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Affiliation(s)
- J Dings
- Department of Neurosurgery, University of Würzburg, Germany
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Ichijima H, Hayashi T, Mitsunaga S, Hamano H. Determination of oxygen tension on rabbit corneas under contact lenses. CLAO J 1998; 24:220-6. [PMID: 9800061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
PURPOSE To determine oxygen tension (PO2) on rabbit corneas beneath rigid gas permeable (RGP), hydrogel, and silicone elastomer lenses under open- and closed-eye conditions and to demonstrate the relationship between PO2 and overnight corneal swelling response in the rabbit model. METHODS An improved PO2 monitoring system (PO-2080) with a platinum-micro-wire-electrode was used to measure PO2. An ultrasonic pachymeter (DGH-2000) was used to measure corneal thickness after overnight wear. RESULTS The relationship between PO2 and oxygen transmissibility (Dk/ L) of the contact lens was linear for Dk/L between 0 and 70 x 10(-9) (cm/ sec)(mLO2/mL x mmHg). For Dk/L greater than 70 x 10(-9), PO2 gradually reached a plateau at 120 mmHg for open-eye conditions and 20 mmHg for closed-eye conditions. PO2 was inversely related to the overnight corneal swelling, ranging from 5.1% swelling at PO2 113.5/17.5 mmHg (open/closed-eye) for a hyper Dk/L lens (125 x 10(-9)) to 15.1% swelling at PO2 10.4/5.1 mmHg for a low Dk/L lens (11.5 x 10(-9)). CONCLUSIONS Polarographic determination of PO2 provides reliable information about the amount of oxygen available to the cornea under a lens for both open-eye and closed-eye conditions. The data demonstrate that it is not possible to achieve normal oxygen levels with contact lens wear, even when hyper Dk/L lenses are worn.
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Affiliation(s)
- H Ichijima
- R&D Department, Menicon Co., Ltd., Nagoya, Japan
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43
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Abstract
An inexpensive and self-contained apparatus for pulsed NMR at 30-250 kHz is described. The intended application is monitoring of the spin polarization of rare gas nuclei in a laser-polarizing apparatus in fields of order 30 G. In addition, the device provides a convenient method for following the polarization decay during storage and transport. Some of the features are a flexible pulse generator, splitting of transmitter RF cycles by the RF gate, a Q switch, and a wide range of receiver gains.
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Affiliation(s)
- B T Saam
- Department of Physics, Washington University, St. Louis, Missouri, 63130-4899, USA
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Furlanetto S, Pinzauti S, La Porta E, Chiarugi A, Mura P, Orlandini S. Development and validation of a differential pulse polarographic method for quinolinic acid determination in human plasma and urine after solid-phase extraction: a chemometric approach. J Pharm Biomed Anal 1998; 17:1015-28. [PMID: 9884191 DOI: 10.1016/s0731-7085(98)00067-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A chemometric approach was applied for determining quinolinic acid in human plasma by differential pulse polarography after solid phase extraction. A fractional factorial design was used to examine the significant experimental variables for the peak height maximization. A Doehlert design, which allowed a sequential response surface methodology to be performed, was applied to the variables scan rate and drop size. The results indicated that the scan rate had the greatest effect on the response peak height. The linear range was extended from 8.52 x 10(-8) to 1.34 x 10(-5) M and the limit of detection was 2.9 x 10(-8) M. The validation process consisted of a pre-validation study followed by the main validation in the plasma matrix. The robustness and the intermediate precision were evaluated by means of experimental design. A 3(4)//9 screening symmetric matrix and a central composite design were used to optimize the solid phase extraction procedure of the analyte from human plasma using anion exchange cartridges. The goal was to select the best retention, wash and elution solvents and their volumes in order to maximize the extraction efficiency using as the response the polarographic peak height. An extraction efficiency of 90% was found. The method was also applied to the determination of quinolinic acid in urine and the mean concentration in human plasma and urine, was found to be 3.7 x 10(-7) and 4.9 x 10(-5) M respectively.
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Affiliation(s)
- S Furlanetto
- Department of Pharmaceutical Sciences, University of Florence, Firenze, Italy.
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45
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Ovchinnikov AV, Gabdullin MG. [Time-base sweep unit for polarograph PA-2]. Med Tekh 1998:46. [PMID: 9791856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
A time-base sweep unit is proposed for a PA-2 polarograph (Czechia). The apparatus as a further development of a series of voltamperometric analyzers of the known mark "LP" has a number of additional modes of polarographic analysis expanding the possibilities of recording the volt-ampere characteristics of the analyzed objects. However, the apparatus cannot solve the problems pertaining to a temporal evaluation of biochemical processes, for estimation of oxygen consumption in particular as it has no a time-base sweep function (I/t), which records only volt-ampere characteristics. In this connection, a time-base sweep unit was elaborated and included into the apparatus complex that provides time-base sweep along the coordinate. The modularity of the proposed elaboration permits its use in other types of polarographs that have no time-base sweep function.
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46
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Abstract
Microcirculatory changes occur early in insulin-dependent diabetes mellitus (IDDM) and are believed to be an early feature of late diabetic complications, leading to reduced oxygen pressure and hypoxia in the skin and other tissues. Whether muscle oxygen supply is also altered is unknown. Therefore, the authors analyzed polarographic measurements of muscle oxygen tension in 44 healthy type I diabetic patients (mean age 28 years; mean diabetes duration 7 years) and in 57 healthy controls, matched for age, sex, and body mass index, and the corresponding influencing factors. Two measurements were taken at rest 60 minutes apart in the anterior tibial muscle. Muscle oxygen tensions did not differ between IDDM patients and controls (23.0 +/- 8.6 vs 25.3 +/- 9.0 mmHg) and were reproducible on repeated measurements (25.3 +/- 9.7 vs 25.5 +/- 7.4 mmHg). Coefficients of variation were 13.5 +/- 10.8% in IDDM patients and 13.1 +/- 9.3% in controls. Compared with controls, in IDDM patients hemoglobin A1c (HbA1c) and blood glucose concentrations were elevated, and arterial oxygen pressure was significantly lower. Muscle oxygen tensions were positively correlated with blood glucose concentrations in IDDM patients (Rho=0.48, P=0.002) but not with HbA1c or with insulin concentrations. The authors conclude that the polarographic measurement of muscle oxygen tension is a reliable method with good reproducibility. Hypoxia in the anterior tibial muscle of type I diabetic patients can be excluded. In IDDM patients the level of muscle oxygen tension is correlated with the level of blood glucose concentration.
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Affiliation(s)
- C Maisch
- 4th Medical Department, University of Tübingen, Germany
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47
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Abstract
Ellipsometry is an optical surface-sensitive method for the investigation of various aspects of protein adsorption mainly at reflecting metal surfaces and ceramic surfaces. One interesting feature of the method is the possibility of detailed and accurate determination of real-time adsorption kinetics of proteins without labelling of the protein. It is also possible to detect protein adsorption with the use of antibodies that adsorb onto the antigen-coated surfaces and to detect antibodies by their adsorption behaviour with regard to antigen-coated surfaces. Compared to other solid phase methods such as enzyme linked immunosorbent assay (ELISA), immunofluorescence and radioimmunoassay, ellipsometry has the advantage of not involving any labelling of the reactant and it is a relatively inexpensive method to maintain. This review is a current report of 15 years of contributions in biomaterials and biochemical research. Special consideration has been given to biologically related surface phenomena such as protein conformation changes, protein displacement effects, early events in blood clotting and complement activation. Among the technical achievements given prominence are the wettability gradient method and the rational use of silicon as an experimental surface. It is clear that ellipsometry and related methods such as reflectometry and surface plasmon resonance (Biacore) are now being increasingly used in biomaterial research as well as in other areas of research.
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Affiliation(s)
- H Elwing
- Department of General and Marine Microbiology, Göteborg University, Sweden
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48
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Abstract
The development of accurate analytical tools to control the interfacial properties of solid substrates is of importance for the design of new biomaterials, as well as for the understanding of biomolecular interactions on surfaces. Considerable research efforts are presently devoted to this area on different levels of molecular complexity, i.e. both in the presence and in the absence of the biomolecules. In this contribution we review briefly applications of infrared reflection-absorption spectroscopy (IRAS) and ellipsometry as tools for analysis of the chemical properties of model surfaces, and their biological response in vitro when in contact with blood plasma or serum, respectively. The strength of the combination of the techniques is demonstrated by determination of protein adsorption patterns on a series of chemically well-defined so-called self-assembled alkanethiolate monolayers (SAMs) of 16-thiohexadecanol (HS-(CH2)16-OH) and n-hexadecanethiol (HS-(CH2)15-CH3) on gold. The protein adsorption patterns after incubations in plasma were determined by the specific binding of antibodies to the surfaces.
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Affiliation(s)
- P Tengvall
- Department of Physics and Measurement Technology, Linköping University, Sweden
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49
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Abstract
The effect of changing growth conditions on the diameter of rod-shaped bacteria was studied in vivo with the use of polarized light scattering. The value of a ratio of scattering matrix elements was measured as a function of scattering angle at various times after nutritional "upshift" for two strains of Escherichia coli cells. The peak locations of the scattering function were calibrated against the diameter for rod-shaped bacteria. The peaks moved toward smaller angles as a function of time after upshift, indicating that the diameter was increasing. Under special conditions, substantial peak shifts occurred within a few minutes of growth condition change, indicating a rapid onset of growth in diameter. The rate of increase of the diameters after upshift was obtained from the angular shift of peak location. This rate was approximately 14 nm/min for E. coli K12 and approximately 9 nm/min for E. coli B/r at 37 degrees C. The rate of diameter increase is smaller at lower temperatures. Experiments with Bacillus megaterium showed that any diameter change after nutritional upshift at 37 degrees C is limited to at most a very small increase, at least for the strain and medium tested.
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Affiliation(s)
- W P Van de Merwe
- Biomedical Instrumentation Center, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799, USA.
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Lübbers DW, Baumgärtl H. Heterogeneities and profiles of oxygen pressure in brain and kidney as examples of the pO2 distribution in the living tissue. Kidney Int 1997; 51:372-80. [PMID: 9027709 DOI: 10.1038/ki.1997.49] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- D W Lübbers
- Max-Planck-Institut für molekulare Physiologie, Dortmund, Germany
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