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1.
Methods Mol Biol ; 2277: 269-276, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34080156

RESUMO

Platelet mitochondria can be used in the study of mitochondrial dysfunction in various complex diseases and can help in finding biological markers for diagnosing the disease, monitoring its course and the effects of treatment. The aim of this chapter was to describe in detail the method of measuring mitochondrial respiration in platelets using high-resolution respirometry. The described method was successfully used for the study of mitochondrial dysfunction in neuropsychiatric diseases.


Assuntos
Plaquetas/metabolismo , Mitocôndrias/metabolismo , Polarografia/métodos , Respiração Celular , Humanos , Polarografia/instrumentação
2.
Nat Prod Res ; 35(10): 1711-1716, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-31192702

RESUMO

This study was focused on in vitro screening of the total antioxidant activity of the selected extracts of the mushroom Coprinus comatus and quinic acid, one of their antidiabetic ingredients, by an uncommon electrochemical assay. Indeed, direct current (DC) polarographic HydroxoPerhydroxo Mercury(II) Complex (HPMC) assay based on decrease of anodic limiting current originating from HPMC formation in alkaline solutions of hydrogen peroxide at potential of mercury dissolution, observed upon gradual addition of antioxidants, was applied herein for the estimation of the natural products' antioxidativity. Quinic acid was found to exhibit most promising antioxidant potential (4.0 ± 0.2%µL-1) being ≈ 2-fold more active than the screened C. comatus extract samples. Actually, such a finding puts some light on the antioxidativity of cyclic polyols, well understimated class of organic compounds, compared to aromatic (poly)phenolics. As a low cost, easy-to handle and accurate this polarographic assay may be thoroughly recommended for much broader use. [Formula: see text].


Assuntos
Antioxidantes/análise , Coprinus/química , Hipoglicemiantes/análise , Polarografia , Ácido Quínico/análise , Antioxidantes/química , Produtos Biológicos/análise , Hipoglicemiantes/química , Micélio/química , Ácido Quínico/química
3.
Appl Opt ; 59(26): 7813-7820, 2020 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-32976451

RESUMO

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.


Assuntos
Colágeno/análise , Polarografia/instrumentação , Tendões/química , Animais , Bovinos , Desenho de Equipamento , Sensibilidade e Especificidade
4.
Pharmazie ; 74(1): 18-22, 2019 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-30782245

RESUMO

The electrochemical behavior of the echinocandin antifungals anidulafungin (AF) and micafungin (MF) has been investigated by differential pulse polarography (DPP). The measurements were carried out in a supporting electrolyte solution consisting of Britton-Robinson buffer and methanol at various substance concentrations and pH values. An amperometric cell with a three electrode system consisting of a dropping mercury electrode (DME) as working electrode, an auxiliary platinum electrode and an Ag/AgCl reference electrode was used in all experiments. AF was electrochemically reduced at potentials between -1.3 and -1.5 V. MF showed a first reduction peak (a) between -1.0 and -1.4 V and a second peak (b) between -1.5 and -1.8 V. A strong pH-dependence was observed, with optimal results at pH 2.0-3.0 for the AF peak, pH 2.0 for the MF peak (a) and pH 5.0 for the MF peak (b). A linear correlation between the concentration and the peak current has been demonstrated for all reduction peaks. MF peak (a) showed a similar behavior to the AF peak regarding shape, peak current and pH-dependence. Therefore, it can be assumed that both reductions are based on the same mechanism, a two-step reduction of the N-acyl group.


Assuntos
Anidulafungina/análise , Antifúngicos/análise , Micafungina/análise , Polarografia/métodos , Eletroquímica/métodos , Eletrodos , Concentração de Íons de Hidrogênio , Mercúrio/química , Polarografia/instrumentação
5.
Bioanalysis ; 11(2): 73-84, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30539646

RESUMO

AIM: Differential pulse polarography was used for the concurrent analysis of the coadministered dantrolene (DAN) and indomethacin (IND) in plasma. MATERIALS & METHODS: DAN and IND, Hanging mercury drop electrode and Britton-Robinson buffer at pH 5 were used. In plasma, cathodic reduction of DAN nitro group and its active metabolite at -0.2 V was done. IND was analyzed after carbonyl group reduction at -1.1 V. RESULTS: Drugs determination in rat plasma with good recoveries and low limit of quantitation was done. Application to trace analysis of drugs in rat plasma was done with Cmax and Tmax determination. CONCLUSION: This technique shows high sensitivity, simplicity and low cost. The method is US FDA validated and it is applicable to human level.


Assuntos
Dantroleno/sangue , Indometacina/sangue , Polarografia/métodos , Animais , Calibragem , Dantroleno/administração & dosagem , Dantroleno/metabolismo , Eletroquímica , Eletrodos , Indometacina/administração & dosagem , Indometacina/metabolismo , Masculino , Polarografia/instrumentação , Ratos , Ratos Sprague-Dawley , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
6.
Methods Mol Biol ; 1782: 7-29, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29850992

RESUMO

In many studies, the evaluation of mitochondrial function is critical to understand how disease conditions or xenobiotics alter mitochondrial function. One of the classic end points that can be assessed is oxygen consumption, which can be performed under controlled yet artificial conditions. Oxygen is the terminal acceptor in the mitochondrial respiratory chain, namely, at an enzyme called cytochrome oxidase, which produces water in the process and pumps protons from the matrix to the intermembrane space. Several techniques are available to measure oxygen consumption, including polarography with oxygen electrodes or fluorescent/luminescent probes. The present chapter will deal with the determination of mitochondrial oxygen consumption by means of the Clark-type electrode, which has been widely used in the literature and still remains to be a reliable technique. We focus our technical description in the measurement of oxygen consumption by isolated mitochondrial fractions and by permeabilized cells.


Assuntos
Permeabilidade da Membrana Celular/efeitos dos fármacos , Mitocôndrias/metabolismo , Oxigênio/metabolismo , Polarografia/instrumentação , Animais , Técnicas de Cultura de Células/instrumentação , Técnicas de Cultura de Células/métodos , Respiração Celular , Detergentes/farmacologia , Eletrodos , Complexo de Proteínas da Cadeia de Transporte de Elétrons/metabolismo , Eletroporação/instrumentação , Eletroporação/métodos , Humanos , Linfócitos , Membranas Artificiais , Células Musculares , Neutrófilos , Fosforilação Oxidativa , Consumo de Oxigênio , Polarografia/métodos , Ratos , Ratos Wistar
7.
Methods Mol Biol ; 1782: 31-70, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29850993

RESUMO

Protocols for High-Resolution FluoRespirometry of intact cells, permeabilized cells, permeabilized muscle fibers, isolated mitochondria, and tissue homogenates offer sensitive diagnostic tests of integrated mitochondrial function using standard cell culture techniques, small needle biopsies of muscle, and mitochondrial preparation methods. Multiple substrate-uncoupler-inhibitor titration (SUIT) protocols for analysis of oxidative phosphorylation (OXPHOS) improve our understanding of mitochondrial respiratory control and the pathophysiology of mitochondrial diseases. Respiratory states are defined in functional terms to account for the network of metabolic interactions in complex SUIT protocols with stepwise modulation of coupling control and electron transfer pathway states. A regulated degree of intrinsic uncoupling is a hallmark of oxidative phosphorylation, whereas pathological and toxicological dyscoupling is evaluated as a mitochondrial defect. The noncoupled state of maximum respiration is experimentally induced by titration of established uncouplers (CCCP, FCCP, DNP) to collapse the protonmotive force across the mitochondrial inner membrane and measure the electron transfer (ET) capacity (open-circuit operation of respiration). Intrinsic uncoupling and dyscoupling are evaluated as the flux control ratio between non-phosphorylating LEAK respiration (electron flow coupled to proton pumping to compensate for proton leaks) and ET capacity. If OXPHOS capacity (maximally ADP-stimulated O2 flux) is less than ET capacity, the phosphorylation pathway contributes to flux control. Physiological substrate combinations supporting the NADH and succinate pathway are required to reconstitute tricarboxylic acid cycle function. This supports maximum ET and OXPHOS capacities, due to the additive effect of multiple electron supply pathways converging at the Q-junction. ET pathways with electron entry separately through NADH (pyruvate and malate or glutamate and malate) or succinate (succinate and rotenone) restrict ET capacity and artificially enhance flux control upstream of the Q-cycle, providing diagnostic information on specific ET-pathway branches. O2 concentration is maintained above air saturation in protocols with permeabilized muscle fibers to avoid experimental O2 limitation of respiration. Standardized two-point calibration of the polarographic oxygen sensor (static sensor calibration), calibration of the sensor response time (dynamic sensor calibration), and evaluation of instrumental background O2 flux (systemic flux compensation) provide the unique experimental basis for high accuracy of quantitative results and quality control in High-Resolution FluoRespirometry.


Assuntos
Fluorometria/métodos , Mitocôndrias Musculares/metabolismo , Fosforilação Oxidativa , Polarografia/métodos , Animais , Biópsia , Biópsia por Agulha , Calibragem , Técnicas de Cultura de Células/instrumentação , Técnicas de Cultura de Células/métodos , Permeabilidade da Membrana Celular , Respiração Celular , Transporte de Elétrons , Fluorometria/instrumentação , Células HEK293 , Humanos , Camundongos , Fibras Musculares Esqueléticas/citologia , Fibras Musculares Esqueléticas/patologia , Consumo de Oxigênio , Polarografia/instrumentação
8.
Methods Mol Biol ; 1782: 71-87, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29850994

RESUMO

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.


Assuntos
Bioensaio/métodos , Ensaios de Triagem em Larga Escala/métodos , Mitocôndrias/metabolismo , Consumo de Oxigênio/efeitos dos fármacos , Polarografia/métodos , Animais , Bioensaio/instrumentação , Respiração Celular/efeitos dos fármacos , Ensaios de Triagem em Larga Escala/instrumentação , Fígado/citologia , Mitocôndrias/efeitos dos fármacos , Miócitos Cardíacos/citologia , Oxigênio/metabolismo , Polarografia/instrumentação , Ratos , Ratos Sprague-Dawley , Testes de Toxicidade/instrumentação , Testes de Toxicidade/métodos
9.
Methods Mol Biol ; 1732: 273-287, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29480482

RESUMO

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.


Assuntos
Mitocôndrias/metabolismo , Fosforilação Oxidativa , Oxigênio/metabolismo , Polarografia/métodos , Animais , Respiração Celular , Células Cultivadas , Eletrodos , Hepatócitos , Fígado/citologia , Fígado/metabolismo , Camundongos , Consumo de Oxigênio , Polarografia/instrumentação , Cultura Primária de Células
10.
Nat Prod Res ; 32(13): 1590-1599, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29052440

RESUMO

EU and Italian laws dealing for the presence of antibiotics or, more in general, drags in food established limits for different kinds of food. Suitable rules exist about the medical treatment of cattle in relation to the production of milk and meat. The adoption of a procedure to check the respect of the law limits is necessary. In this paper, the presence of different classes of antibiotics in milk and in homogenised meat is investigated. Generally, HPLC methods are applied for this purpose. In this paper, the application of polarographic analysis is studied and the results are compared with the chromatographic ones. The comparison is relative to all the phases of analysis including the sample preparation. The results show the advantage of the proposed procedure.


Assuntos
Antibacterianos/análise , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Polarografia/métodos , Animais , Bovinos , Cromatografia Líquida de Alta Pressão/métodos , Carne/análise , Leite/química
11.
J R Soc Interface ; 14(131)2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28615493

RESUMO

The evolution of structural colour mechanisms in biological systems has given rise to many interesting optical effects in animals and plants. The instance of the scarab beetle Chrysina resplendens is particularly distinctive. Its exoskeleton has a bright, golden appearance and reflects both right-handed and left-handed circularly polarized light concurrently. The chiral nanostructure responsible for these properties is a helicoid, in which birefringent dielectric planes are assembled with an incremental rotation. This study correlates details of the beetle's circularly polarized reflectance spectra directly with physical aspects of its structural morphology. Electron micrography is used to identify and measure the physical dimensions of the key constituent components. These include a chiral multilayer configuration comprising two chirped, left-handed helicoids that are separated by a birefringent retarder. A scattering matrix technique is used to simulate the system's optical behaviour in which the roles of each component of the morphological substructure are elucidated by calculation of the fields throughout its depth.


Assuntos
Besouros/fisiologia , Tegumento Comum/fisiologia , Animais , Birrefringência , Luz , Polarografia , Propriedades de Superfície
12.
J R Soc Interface ; 14(130)2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28566511

RESUMO

The damselfly Pseudolestes mirabilis reflects brilliant white on the ventral side of its hindwings and a copper-gold colour on the dorsal side. Unlike many previous investigations of odonate wings, in which colour appearances arise either from multilayer interference or from wing-membrane pigmentation, the whiteness on the wings of P. mirabilis results from light scattered by a specialized arrangement of flattened waxy fibres and the copper-gold colour is produced by pigment-based filtering of this light scatter. The waxy fibres responsible for this optical signature effectively form a structure that is disordered in two dimensions and this also gives rise to distinct optical linear polarization. It is a structure that provides a mechanism enabling P. mirabilis to display its bright wing colours efficiently for territorial signalling, both passively while perched, in which the sunlit copper-gold upperside is presented against a highly contrasting background of foliage, and actively in territorial contests in which the white underside is also presented. It also offers a template for biomimetic high-intensity broadband reflectors that have a pronounced polarization signature.


Assuntos
Luz , Odonatos/anatomia & histologia , Polarografia , Asas de Animais/anatomia & histologia , Animais , Comportamento Animal , Cor , Territorialidade
13.
Clin. transl. oncol. (Print) ; 19(4): 419-424, abr. 2017. tab, graf
Artigo em Inglês | IBECS | ID: ibc-160890

RESUMO

Purpose. Hypoxia has predictive value in head and neck cancer (HNC). It has been well described, albeit in a small number of clinical Centres. The aim of this study was to describe our experience using the polarographic probe technique to assess the predictive value of tumour oxygenation in patients with advanced HNC treated with hyperfractionated radio-chemotherapy. Hypoxia modification was induced using percutaneous spinal cord stimulation (SCS). Methods/patients. Male patients (n = 12; stage IVb n = 8; IVa n = 4; mean age 58: range 46-70 years) with advanced HNC were evaluated. Planned therapy was hyperfractionated-radiotherapy, oral tegafur (precursor of 5-fluorouracil) and hypoxia modification using SCS. Pre-treatment analyses included: haemoglobin levels and tumour oxygenation (using the Eppendorf polarographic probe device). Oxygenation was expressed as median-pO2 (in mmHg) and hypoxia as the percentage of pO2 values ≤5 mmHg (HP5) and ≤2.5 mmHg (HP2.5). Results. Lower haemoglobin levels were directly correlated with median pO2 (p = 0.017) and inversely correlated with HP5 (p = 0.020) and more advanced stages (IVb vs. IVa; p = 0.028). Patients who subsequently developed systemic metastasis had tumours that were more hypoxic, with lower median pO2 (p = 0.036) and higher HP5 (p = 0.036). The subgroup of patients with HP2.5 above the median (the most hypoxic tumours) had lower loco-regional control (p = 0.027), cause-specific survival (p = 0.008), and overall survival (p = 0.008). Conclusions. Higher tumour hypoxia showed predictive value in HNC in our study, and was significantly associated with lower overall survival, cause-specific survival, and loco-regional control. Tumour hypoxia determination could be used to select patients who would most benefit by hypoxia modification during chemo-radiotherapy of HNC (AU)


No disponible


Assuntos
Humanos , Masculino , Pessoa de Meia-Idade , Idoso , Hipóxia/diagnóstico , Hipóxia/patologia , Neoplasias de Cabeça e Pescoço/tratamento farmacológico , Neoplasias de Cabeça e Pescoço/radioterapia , Valor Preditivo dos Testes , Anemia/complicações , Anemia/diagnóstico , Polarografia/instrumentação , Polarografia/métodos , Polarografia , Prognóstico
14.
Antonie Van Leeuwenhoek ; 110(3): 365-373, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27896685

RESUMO

The possibility of reduction of vanadate monomer in the mycelium of fungus Phycomyces blakesleeanus was investigated in this study by means of polarography. Control experiments were performed with vanadyl [V(IV)] and vanadate [V(V)] in 10 mM Hepes, pH 7.2. Addition of P. blakesleeanus mycelium resulted in disappearance of all V(IV) polarographic waves recorded in the control. This points to the uptake of all available V(IV) by the mycelium, up to 185 µmol/gFW, and suggests P. blakesleeanus as a potential agent in V(IV) bioremediation. Polarographic measurements of mycelium with low concentrations (0.1-1 mM) of V(V), that only allows the presence of monomer, showed that fungal mycelia removes around 27% of V(V) from the extracellular solution. Uptake was saturated at 104 ± 2 µmol/gFW which indicates excellent bioaccumulation capability of P. blakesleeanus. EPR, 51V NMR and polarographic experiments showed no indications of any measurable extracellular complexation of V(V) monomer with fungal exudates, reduction by the mycelium or adsorption to the cell wall. Therefore, in contrast to vanadium oligomers, vanadate monomer interactions with the mycelium are restricted to its transport into the fungal cell, probably by a phosphate transporter.


Assuntos
Micélio/metabolismo , Phycomyces/metabolismo , Vanadatos/metabolismo , Biodegradação Ambiental , Transporte Biológico , Parede Celular/metabolismo , Concentração de Íons de Hidrogênio , Micélio/química , Oxirredução , Phycomyces/química , Polarografia/métodos , Soluções , Vanadatos/química
15.
Bioinspir Biomim ; 11(5): 055004, 2016 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-27596986

RESUMO

Weakly electric fish generate electric current and use hundreds of voltage sensors on the surface of their body to navigate and locate food. Experiments (von der Emde and Fetz 2007 J. Exp. Biol. 210 3082-95) show that they can discriminate between differently shaped conducting or insulating objects by using electrosensing. One approach to electrically identify and characterize the object with a lower computational cost rather than full shape reconstruction is to use the first order polarization tensor (PT) of the object. In this paper, by considering experimental work on Peters' elephantnose fish Gnathonemus petersii, we investigate the possible role of the first order PT in the ability of the fish to discriminate between objects of different shapes. We also suggest some experiments that might be performed to further investigate the role of the first order PT in electrosensing fish. Finally, we speculate on the possibility of electrical cloaking or camouflage in prey of electrosensing fish and what might be learnt from the fish in human remote sensing.


Assuntos
Mimetismo Biológico/fisiologia , Peixe Elétrico/fisiologia , Percepção de Forma/fisiologia , Animais , Polarografia
16.
Nitric Oxide ; 57: 79-84, 2016 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-27153987

RESUMO

Nitrite salts of sodium or potassium are being used for the protection of meat products. They provide color and taste of meat and they protect against clostridia. On the other hand, nitrite ions can interact with amines to form nitrosamines which are known as carcinogenic substances. They may also react with hemoglobin and reduce its oxygen carrying capacity. Thus, its concentration in food-stuff has to be controlled carefully by highly sensitive methods. A new DP polarographic method is established for the determination of nitrite. Nitrite cannot be determined directly with any analytical methods. Long and tedious procedures are necessary for many of them. In this polarographic method arsenite, As(III), ion is used for the reduction of nitrite. The nitrite is determined from the As(III) quantity left over after the reaction with nitrite. The peak of arsenite has been used since it is sharp and responds well for the standard addition of arsenite. The optimum conditions for the quantitative reaction between nitrite and arsenite have been studied. It was found that the pH for the reaction medium has to be 5-7, since nitrite is decomposed at lower pH values. The reaction medium has to be stirred for about 5 min with nitrogen gas in order to expel the NO gas formed and thus to shift the equilibrium to products side. The limit of detection, LOD, was found to be as 2 × 10(-7) M. No interference was observed from most common ions.


Assuntos
Nitritos/análise , Arsênio/química , Limite de Detecção , Oxirredução , Polarografia/métodos
17.
Plast Reconstr Surg ; 137(6): 1016e-1023e, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27219253

RESUMO

BACKGROUND: Patients undergoing ablative and reconstructive head and neck surgery with a microvascular flap have multiple factors that potentially decrease postoperative mean arterial pressure, which may endanger flap survival. The safety of vasopressor use has long been a topic of discussion. The authors analyzed the effect of vasopressors on microvascular flap perfusion after head and neck cancer reconstruction. METHODS: A total of 27 patients were enrolled in a randomized, controlled, clinical trial. A microvascular radial forearm flap was used for reconstruction. Patients were allocated into one of three groups: dopamine, norepinephrine, and control. The intervention groups received the vasoactive drug, aiming to maintain the mean arterial pressure between 80 and 90 mmHg. Normovolemia was maintained according to central venous pressure. Flap perfusion was monitored with continuous tissue partial pressure of oxygen and microdialysate metabolite (lactate-to-pyruvate ratio) measurements. RESULTS: No adverse effects were observed, and postoperative recovery was free of complications in all groups. Neither the lactate-to-pyruvate ratio nor continuous tissue partial pressure of oxygen values differed significantly between groups during the first 24 hours of the vasoactive drug infusion period or during the 72-hour follow-up. CONCLUSIONS: Norepinephrine and dopamine are safe and effective vasopressors for use during the postoperative period following head and neck cancer surgery with microvascular reconstruction. Dopamine should be used with caution, however, because of the risk of side effects. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.


Assuntos
Dopamina/administração & dosagem , Microcirurgia/métodos , Norepinefrina/administração & dosagem , Neoplasias Otorrinolaringológicas/cirurgia , Consumo de Oxigênio/efeitos dos fármacos , Retalhos Cirúrgicos/irrigação sanguínea , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Esvaziamento Cervical , Estadiamento de Neoplasias , Neoplasias Otorrinolaringológicas/patologia , Polarografia
18.
Biofizika ; 60(4): 708-15, 2015.
Artigo em Russo | MEDLINE | ID: mdl-26394470

RESUMO

The antioxidant effect of succinate and 3-hydroxybutyrate oxidation on the kinetics of lipid peroxidation induced by ATP-Fe2+ complex in isolated rat liver mitochondria of old (1.0-1.5 years) and young (3 months) male rats was investigated. The rate of induced lipid peroxidation V(LPO) in rat liver mitochondria and the half-time of oxygen consumption Δt50, which included the lag period and the initiation. phase, was recorded polarographically. Without exogenous oxidative-substrates V(LPO) was slightly higher in mitochondria of old animals, but the onset of lipid peroxidation cascade was significantly earlier than in young animals. Incubation of mitochondria with 5mM succinate for 1 min inhibited V(LPO) by 15% in young animals and by 35% in old animals. However, only in mitochondria of old animals Δt50 increased by 19% as compared to lipid peroxidation without substrates. V(LPO) in mitochondria of young animals did not significantly change during 3-hydroxybutyrate oxidation, while in mitochondria of old animals it was reduced by 19% with a slight increase in Δt50. To simulate age-dependent dysfunction we damaged isolated mitochondria by a series of freeze-thaw cycles, which caused a significant increase of V(LPO) of.both age groups. Succinate oxidation inhibited V(LPO) in damaged mitochondria in all cases by 56%, as compared to V(LPO) without oxidative substrates and extended At50 twofold in mitochondria of young animals. Oxidation of 3-hydroxybutyrate had no effect on V(LPO) in damaged mitochondria regardless of animal, age and extended Δt50 by 48% in mitochondria of young animals. Thus, the antioxidant effect of succinate oxidation can prevent lipid peroxidation damage and may exhibit geroprotective action at the level of aging mitochondria. Therefore, the antioxidant effect is due to the process of substrate oxidation in the respiratory chain but not because of an interaction of their structures with membrane lipids per se.


Assuntos
Envelhecimento/metabolismo , Antioxidantes/farmacologia , Mitocôndrias Hepáticas/efeitos dos fármacos , Ácido Succínico/farmacologia , Ácido 3-Hidroxibutírico/farmacologia , Trifosfato de Adenosina/química , Trifosfato de Adenosina/farmacologia , Animais , Antioxidantes/metabolismo , Cátions Bivalentes , Técnicas de Cultura , Transporte de Elétrons/efeitos dos fármacos , Ferro/química , Ferro/farmacologia , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Mitocôndrias Hepáticas/metabolismo , Consumo de Oxigênio/efeitos dos fármacos , Polarografia , Ratos , Ratos Sprague-Dawley , Ácido Succínico/metabolismo
19.
Zhongguo Yi Liao Qi Xie Za Zhi ; 39(2): 136-8, 2015 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-26204747

RESUMO

OBJECTIVE: A method for determined oxygen permeability (Dk) of finished soft contact lens. METHODS: Oxygen permeability(Dk) of 10 group finished soft contact lens was determined by polarographic method, and the values were linearly calibrated using the measured and established Dk values of the specified reference materials. RESULTS: Only one Dk value fell outside of the requirement of GB 11417.3-2012 tolerance for Dk (± 20%). CONCLUSION: It is great practicability when determined the oxygen permeability (Dk) of finished soft contact lens by polarographic method which were linearly calibrated using the measured and established Dk values of the specified equal thickness reference materials without the measured lens customized 4 different thickness.


Assuntos
Lentes de Contato Hidrofílicas , Oxigênio/metabolismo , Permeabilidade , Calibragem , Polarografia
20.
Angew Chem Int Ed Engl ; 54(29): 8340-62, 2015 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-26084034

RESUMO

Oxygen monitoring has been a topic of exhaustive study given its central role in the biochemistry of life. The ability to quantify the physiological distribution and real-time dynamics of oxygen from sub-cellular to macroscopic levels is required to fully understand the mechanisms associated with both normal physiology and disease states. This Review will present the most significant recent advances in the development of oxygen-sensing materials and techniques, including polarographic, nuclear medicine, magnetic resonance, and optical approaches, that can be applied specifically for the real-time monitoring of oxygen dynamics in cellular and tissue environments. As some of the most exciting recent advances in synthetic methods and biomedical applications have been in the field of optical oxygen sensors, a major focus will be on the development of these toolkits.


Assuntos
Técnicas Biossensoriais/métodos , Oxigênio/análise , Animais , Técnicas Biossensoriais/instrumentação , Técnicas de Diagnóstico por Radioisótopos/instrumentação , Hemoglobinas/análise , Humanos , Medições Luminescentes/instrumentação , Medições Luminescentes/métodos , Espectroscopia de Ressonância Magnética/instrumentação , Espectroscopia de Ressonância Magnética/métodos , Polarografia/instrumentação , Polarografia/métodos
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