Experimental optical properties explained by density functional theory of the natural red algae for dye-sensitized solar cells application.

The present study investigates the usage of a novel natural dye derived from red algae of Morocco in dye-sensitized solar cells (DSSCs) for the first time. The main pigments responsible for sensitizing the semiconductor TiO2 coatings in the red algae were identified as phycoerythrin, carotenoid, and chlorophyll. The efficiency of a DSSC made from red algae was compared to that of a solar cell made from chlorophyll alone. The photovoltaic performance of the DSSC was evaluated through photocurrent density to photovoltage (J-V) characteristic analysis, and the efficiency was found to be 0.93%. To gain insights into its behavior, the absorbance and photoluminescence in a broad range were studied. Both absorbance and photoluminescence exhibited a broad-spectrum range. Additionally, electronic properties, such as HOMO, LUMO, energy gap, and chemical reactivity parameters, were studied using density functional theory (DFT) calculations.

Mixture of Doxycycline, ML-7 and L-NAME Restores the Pro- and Antioxidant Balance during Myocardial Infarction-In Vivo Pig Model Study.

The restoration of blood flow to the ischemic myocardium inflicts ischemia/reperfusion (I/R) heart injury (IRI). The main contributors to IRI are increased oxidative stress and subsequent excessive production of ROS, increased expression of NOS and peroxinitate, activation of MMPs, and enhanced posttranslational modifications of contractile proteins, which make them more susceptible to proteolytic degradation. Since the pathophysiology of IRI is a complex issue, and thus, various therapeutic strategies are required to prevent or reduce IRI and microvascular dysfunction, in the current study we proposed an innovative multi-drug therapy using low concentrations of drugs applied intracoronary to reach microvessels in order to stabilize the pro- and antioxidant balance during a MI in an in vivo pig model. The ability of a mixture of doxycycline (1 µM), ML-7 (0.5 µM), and L-NAME (2 µM) to modulate the pro- and antioxidative balance was tested in the left ventricle tissue and blood samples. Data showed that infusion of a MIX reduced the total oxidative status (TOS), oxidative stress index (OSI), and malondialdehyde (MDA). It also increased the total antioxidant capacity, confirming its antioxidative properties. MIX administration also reduced the activity of MMP-2 and MMP-9, and then decreased the release of MLC1 and BNP-26 into plasma. This study demonstrated that intracoronary administration of low concentrations of doxycycline in combination with ML-7 and L-NAME is incredibly efficient in regulating pro- and antioxidant balance during MI.

In Vivo Study on Doxycycline Protective Mechanisms during Myocardial Ischemia Injury in Rats.

BACKGROUND: The fact that during myocardial ischemia/reperfusion (I/R) injury, myosin light chain 1 (MLC1) and troponin I (TnI) are degraded by matrix metalloproteases activity has already been well established in both in vitro and ex vivo studies. However, I/R injury is a complex issue based on several overlapping mechanisms. Increased activity of myosin light chain kinase and nitric oxide synthase due to oxidative stress leads to post-translational modifications of MLC1, thus leading to the increased degradation of these proteins. METHODS: Wistar rats were subjected to left anterior descending coronary artery occlusion. To measure the pharmacological effect of doxycycline, transthoracic echocardiography as well as biochemical tests, concentrations of TnI, LDH, MLC1, MMP-2 and MMP-9 were performed. Gelatinize activity and cytotoxicity level were also assessed; Results: I.p., administration of doxycycline before LAD occlusion surgery increased TnI and LDH content in the heart and decreased cytotoxicity. A reduction of MMP-2 and MMP-9 concentration and MMP-2 activity after administration of Doxy was also observed, as well as improvement in echocardiographic parameters just 7 days after surgery. CONCLUSIONS: Inhibition of MMPs by doxycycline, in vivo, may serve as a protective agent in future therapy.

The Risk Function of Breast and Ovarian Cancers in the Avrami-Dobrzynski Cellular Phase-Transition Model.

Specifying the role of genetic mutations in cancer development is crucial for effective screening or targeted treatments for people with hereditary cancer predispositions. Our goal here is to find the relationship between a number of cancerogenic mutations and the probability of cancer induction over the lifetime of cancer patients. We believe that the Avrami-Dobrzynski biophysical model can be used to describe this mechanism. Therefore, clinical data from breast and ovarian cancer patients were used to validate this model of cancer induction, which is based on a purely physical concept of the phase-transition process with an analogy to the neoplastic transformation. The obtained values of model parameters established using clinical data confirm the hypothesis that the carcinogenic process strongly follows fractal dynamics. We found that the model's theoretical prediction and population clinical data slightly differed for patients with the age below 30 years old, and that might point to the existence of an ancillary protection mechanism against cancer development. Additionally, we reveal that the existing clinical data predict breast or ovarian cancers onset two years earlier for patients with BRCA1/2 mutations.

Klotho inhibits IGF1R/PI3K/AKT signalling pathway and protects the heart from oxidative stress during ischemia/reperfusion injury.

Ischemia/reperfusion injury (IRI) of the heart involves the activation of oxidative and proapoptotic pathways. Simultaneously Klotho protein presents anti-aging, antiapoptotic and antioxidative properties. Therefore, this study aimed to evaluate the effect of Klotho protein on oxidative stress in hearts subjected to IRI. Isolated rat hearts perfused with the Langendorff method were subjected to ischemia, followed by reperfusion, in the presence or absence of recombinant rat Klotho protein. The factors involved in the activation of insulin-like growth factor receptor (IGF1R)/phosphoinositide-3-kinase (PI3K)/protein kinase B (AKT) signalling pathway were evaluated. IRI caused activation of the IGF1R (p = 0.0122)/PI3K (p = 0.0022) signalling, as compared to the aerobic control group. Infusion supply of Klotho protein during IRI significantly reduced the level of phospho-IGF1R (p = 0.0436), PI3K (p = 0.0218) and phospho-AKT (p = 0.0020). Transcriptional activity of forkhead box protein O3 (FOXO3) was reduced (p = 0.0207) in hearts subjected to IRI, compared to aerobic control. Administration of Klotho decreased phosphorylation of FOXO3 (p = 0.0355), and enhanced activity of glutathione peroxidase (p = 0.0452) and superoxide dismutase (p = 0.0060) in IRI + Klotho group. The levels of reactive oxygen/nitrogen species (ROS/RNS) (p = 0.0480) and hydrogen peroxide (H2O2) (p = 0.0460), and heart injury (p = 0.0005) were significantly increased in hearts from the IRI group in comparison to the aerobic group. Klotho reduced NADPH oxidase 2 (NOX2) (p = 0.0390), ROS/RNS (p = 0.0435) and H2O2 (p = 0.0392) levels, and heart damage (p = 0.0286) in the hearts subjected to IRI. In conclusion, Klotho contributed to the protection of the heart against IRI and oxidative stress via inhibition of the IGF1R/PI3K/AKT pathway, thus can be recognized as a novel cardiopreventive/cardioprotective agent.

News media exposure and life satisfaction in the COVID-19 pandemic: a moderated mediation model of COVID-19 fear and worries and gender.

BACKGROUND: Research has found that news media exposure may have both positive and negative consequences for well-being in times of crisis. However, the internal mechanisms underlying that relationship need further investigation. The purpose of the research presented in the paper was to explore the role of COVID-19 fear and worries and users' gender in the relationship between news media exposure and life satisfaction. PARTICIPANTS AND PROCEDURE: Three hundred seventy-one media users aged 19 to 65 (M = 28.88, SD = 10.25) were surveyed with news media exposure, COVID-19 fear and worries, and life satisfaction scales. Correlation analyses and moderated mediation analyses were performed. RESULTS: The study demonstrated a significant positive association between news media exposure and life satisfaction, and an indirect effect of news exposure on life satisfaction via COVID-19 fear moderated by gender: elevated COVID-19 fear decreases the positive association between news exposure and life satisfaction, and this effect is stronger for women. CONCLUSIONS: The present study expands our understanding of the role that news media can play in shaping the user's well-being in a time of a health crisis. It demonstrates that the effects of exposure to news media during a crisis are twofold. On the one hand, the use of news media is associated with a more positive evaluation of one's life, which may indicate that media use is a way to cope with a crisis. On the other hand, frequent use of news media leads to an elevated level of fear related to COVID-19, which, in turn, lowers the user's well-being.

Mitoquinone Alleviates Donation after Cardiac Death Kidney Injury during Hypothermic Machine Perfusion in Rat Model.

Transplanted organs are subjected to harmful conditions through stopping blood flow, hypothermic storage of the graft, and subsequent reperfusion. In particular, kidneys donated from patients after cardiac arrest (DCD) are classified as more vulnerable to ischemia-reperfusion injury (IRI). Hypothermic machine perfusion is proposed as a solution for better kidney storage before transplantation, and it is a good platform for additional graft treatment. Antioxidants have gained interest in regenerative medicine due to their ability to scavenge reactive oxygen species (ROS), which play a key role in IRI. We evaluated the effect of Mitoquinone (MitoQ), a strong mitochondria-targeted antioxidant, administered directly to the perfusing buffer. Rat kidneys were isolated, randomly classified into one of the following groups, donation after brainstem death (DBD), DCD, and DCD with MitoQ, and perfused for 22 hours with a hypothermic machine perfusion system. Subsequently, we detected levels of kidney injury (KIM-1) and oxidative stress (ROS/RNS, cytochrome C oxidase, and mitochondrial integrity) markers. We compared the activation of the apoptosis pathway (caspase 3 and 9), the concentration of phosphorylated Akt (pAkt), and the pAkt/total Akt ratio. MitoQ reduces KIM-1 concentration, total ROS/RNS, and the level of caspases. We observed a decrease in pAkt and the pAkt/total Akt ratio after drug administration. The length of warm ischemia time negatively impacts the graft condition. However, MitoQ added to the perfusing system as an 'on pump' therapy mitigates injury to the kidney before transplantation by inhibiting apoptosis and reducing ROS/RNS levels. We propose MitoQ as a potential drug for DCD graft preconditioning.

Dispersion-enabled control of photonic density of states in photonic hypercrystals.

In this work, we investigate possibility of engineering photonic density of states (PDOS) in photonic hypercrystals (PHCs). In the course of our analysis, we have demonstrated that it is possible to obtain photonic bandgap for selected polarization of light as well as to achieve significant broadband PDOS enhancement. We have also presented for the first time that anomalous dispersion, that arises from effective resonance of hyperbolic medium constituting the PHC structure, may lead to negative PDOS, which is photonic equivalent of mobility gap, observed in electronic crystals. Furthermore, we have demonstrated that application of PHC structure, instead of standalone hyperbolic medium, allows to obtain more versatile electromagnetic response, such as broadband perfect absorption of adjustable spectral range of operation.

A tetrahydroacridine derivative and its conjugate with gold nanoparticles: promising agents for the treatment of Alzheimer's disease.

A new tetrahydroacridine derivative (CHDA) with acetylcholinesterase inhibitory properties was synthesized. Using a range of physicochemical techniques, it was shown that the compound strongly adsorbs onto the surface of planar macroscopic or nanoparticulate gold, forming a nearly full monolayer. The adsorbed CHDA molecules reveal well-defined electrochemical behavior, being irreversibly oxidized to electroactive species. The CHDA also exhibits strong fluorescence, which is effectively quenched after adsorption onto gold via a static quenching mechanism. Both CHDA and its conjugate reveal considerable inhibitory properties against acetylcholinesterase activity, which is promising from the perspective of therapeutic application in the treatment of Alzheimer's disease. Moreover, both agents appear to be non-toxic as demonstrated using in vitro studies. On the other hand, conjugation of CHDA with nanoradiogold particles (Au-198) offers new potential diagnostic perspectives in medical imaging.

Low-density 3D-printed boluses with honeycomb infill in radiotherapy.

PURPOSE: Dosimetric characteristics of 3D-printed plates using different infill percentage and materials was the purpose of our study. METHODS: Test plates with 5%, 10%, 15% and 20% honeycomb structure infill were fabricated using TPU and PLA polymers. The Hounsfield unit distribution was determined using a Python script. Percentage Depth Dose (PDD) distribution in the build-up region was measured with the Markus plane-parallel ionization chamber for an open 10x10 cm2 field of 6 MV. PDD was measured at a depth of 1 mm, 5 mm, 10 mm and 15 mm. Measurements were compared with Eclipse treatment planning system calculations using AAA and Acuros XB algorithms. RESULTS: The mean HU for CT scans of 3D-printed TPU plates increased with percentage infill increase from -739 HU for 5% to -399 HU for 20%. Differences between the average HU for TPU and PLA did not exceed 2% for all percentage infills. Even using a plate with the lowest infill PDD at 1 mm depth increase from 44.7% (without a plate) to 76.9% for TPU and 76.6% for PLA. Infill percentage did not affect the dose at depths greater than 5 mm. Differences between measurements and TPS calculations were less than 4.1% for both materials, regardless of the infill percentage and depth. CONCLUSIONS: The use of 3D-printed light boluses increases the dose in the build-up region, which was shown based on the dosimetric measurements and TPS calculations.

Generation of red light with intense photoluminescence assisted by Forster resonance energy transfer from Znq2 and DCM thin films.

In this work, a novel experimental investigation of photoluminescence properties of Znq2 thin films co-doped with different concentrations of DCM were performed. The thin films were successfully deposited on glass substrates with different compositions, under high vacuum, by using the vacuum evaporation technique. For all compositions, the photoluminescence was measured at room temperature and also at low temperature in a wide range from 77 to 300 K with a step of 25 K in a high vacuum. The lifetime of the sample studied in real time was also measured using the decay time technique. The results obtained confirm that the doping influences the intensity of the DCM photoluminescence and also shows a complete energy transfer occurred from Znq2 to DCM which may have shifted the photoluminescence peak from Znq2 to the orange wavelength region which is related to DCM. The lifetime of the sample studied in real time was about 4.47 ns for Znq2 and while all the other samples showed two decay time components. As a result, the doping influences the optical properties of Znq2 and makes it a potential candidate for optoelectronic applications.

Topography and Nonlinear Optical Properties of Thin Films Containing Iodide-Based Hybrid Perovskites.

This article covers selected properties of organic-inorganic thin films of hybrid perovskites with the summary formulas CH3NH3MI3, where M = Pb, Cd, Ge, Sn, Zn. The paper discusses not only the history, general structure, applications of perovskites and the basics of the theory of nonlinear optics, but also the results of experimental research on their structural, spectroscopic, and nonlinear optical properties. The samples used in all presented studies were prepared in the physical vapor deposition process by using co-deposition from two independent thermal sources containing the organic and inorganic parts of individual perovskites. Ultimately, thin layers with a thickness of the order of nanometers were obtained on glass and crystalline substrates. Their structural properties were characterized by atomic force microscopy imaging. Spectroscopic tests were used to confirm the tested films' transmission quality and determine previously unknown physical parameters, such as the absorption coefficient and refractive index. Experimental results of the nonlinear optical properties were obtained by studying the second and third harmonic generation processes and using initial sample polarization in the so-called Corona poling process. The obtained experimental results allowed us to determine the second- and third-order nonlinear optical susceptibility of the tested materials.

Klotho Protein Decreases MMP-Mediated Degradation of Contractile Proteins during Ischaemia/Reperfusion Injury to the Cardiomyocytes.

Ischaemia, followed by reperfusion, causes the generation of reactive oxygen species, overproduction of peroxynitrite, activation of matrix metalloproteinases (MMPs), and subsequently the degradation of heart contractile proteins in the cardiomyocytes. Klotho is a membrane-bound or soluble protein that regulates mineral metabolism and has antioxidative activity. This study aimed to examine the influence of Klotho protein on the MMP-mediated degradation of contractile proteins during ischaemia/reperfusion injury (IRI) to the cardiomyocytes. Human cardiac myocytes (HCM) underwent in vitro chemical IRI (with sodium cyanide and deoxyglucose), with or without the administration of recombinant Klotho protein. The expression of MMP genes, the expression and activity of MMP proteins, as well as the level of contractile proteins such as myosin light chain 1 (MLC1) and troponin I (TnI) in HCM were measured. Administration of Klotho protein resulted in a decreased activity of MMP-2 and reduced the release of MLC1 and TnI that followed in cells subjected to IRI. Thus, Klotho protein contributes to the inhibition of MMP-dependent degradation of contractile proteins and prevents injury to the cardiomyocytes during IRI.

Silencing RNA for MMPs May Be Utilized for Cardioprotection.

Ischemia/reperfusion (I/R) injury is accompanied by an increase of matrix metalloproteinase 2 (MMP-2) activity, which degrades heart contractile proteins. The aim of the study was to investigate the effect of MMP-2 small interfering RNA (MMP-2 siRNA) administration on I/R heart. Isolated rat hearts perfused by the Langendorff method were subjected to I/R in the presence or absence of MMP-2 siRNA. The hemodynamic parameters of heart function were monitored. Lactate dehydrogenase (LDH) activity was measured in coronary effluents. Activity and concentration of MMPs in the hearts were measured. Concentration of troponin I (TnI) in coronary effluents was examined as a target for MMP-2 degradation. Recovery of heart mechanical function was reduced after I/R; however, administration of MMP-2 siRNA resulted in restoration of proper mechanical function (p < 0.001). LDH activity was decreased after the use of MMP-2 siRNA (p = 0.02), providing evidence for reduced cardiac damage. Both MMP-2 and MMP-9 syntheses as well as their activity were inhibited in the I/R hearts after siRNA administration (p < 0.05). MMP-2 siRNA administration inhibited TnI release into the coronary effluents (p < 0.001). The use of MMP-2 siRNA contributed to the improvement of heart mechanical function and reduction of contractile proteins degradation during I/R; therefore, MMP-2 siRNA may be considered a cardioprotective agent.

Corrigendum to "Ameliorating Effect of Klotho Protein on Rat Heart during I/R Injury".

[This corrects the article DOI: 10.1155/2020/6427284.].

Recent Methods of Kidney Storage and Therapeutic Possibilities of Transplant Kidney.

Kidney transplantation is the standard procedure for the treatment of end-stage renal disease (ESRD). During kidney storage and before implantation, the organ is exposed to damaging factors which affect the decline in condition. The arrest of blood circulation results in oxygen and nutrient deficiency that lead to changes in the cell metabolism from aerobic to anaerobic, damaging organelles and cell structures. Currently, most kidney grafts are kept in a cold preservation solution to preserve low metabolism. However, there are numerous reports that machine perfusion is a better solution for organ preservation before surgery. The superiority of machine perfusion was proved in the case of marginal donor grafts, such as extended criteria donors (ECD) and donation after circulatory death (DCD). Different variant of kidney machine perfusions are evaluated. Investigators look for optimal conditions to protect kidneys from ischemia-reperfusion damage consequences by examining the best temperature conditions and comparing systems with constant or pulsatile flow. Moreover, machine perfusion brings additional advantages in clinical practice. Unlike cold static storage, machine perfusion allows the monitoring of the parameters of organ function, which gives a real possibility to make a decision prior to transplantation concerning whether the kidney is suitable for implantation. Moreover, new pharmacological therapies are sought to minimize organ damage. New components or cellular therapies can be applied, since perfusion solution flows through the organ. This review outlines the pros and cons of each machine perfusion technique and summarizes the latest achievements in the context of kidney transplantation using machine perfusion systems.

Δ9-Tetrahydrocannabinol (Δ9-THC) Improves Ischemia/Reperfusion Heart Dysfunction and Might Serve as a Cardioprotective Agent in the Future Treatment.

BACKGROUND: Ischemia/reperfusion (I/R) is a pivotal mechanism of organ injury during clinical stetting for example for cardiopulmonary bypasses. The generation of reactive oxygen species (ROS) during I/R induces oxidative stress that promotes endothelial dysfunction, DNA dissociation and local inflammation. In turn, those processes induce cytokine release, resulting in damage to cellular structures and cell death. One of the major psychoactive compounds of Cannabis is delta-9-tetrahydrocannabinol (Δ9-THC), which is known as an anti-inflammatory mediator. Our research aimed to test if Δ9-THC may be protective in the treatment of cardiovascular system dysfunction arising from I/R heart injury. METHODS: Two experimental models were used: isolated rat hearts perfused with the Langendorff method and human cardiac myocytes (HCM) culture. Rat hearts and HCM underwent ex vivo/chemical in vitro I/R protocol with/without Δ9-THC treatment. The following parameters were measured: cell metabolic activity, morphology changes, cell damage as lactate dehydrogenase (LDH) activity, ceramide kinase (CERK) activity, ROS level, total antioxidant capacity (TAC) and heart hemodynamic parameters. RESULTS: Δ9-THC protected the heart, as evidenced by the improved recovery of cardiac function (p < 0.05, N = 3-6). Cells subjected to I/R showed lower cytoplasmic LDH activity, and 10 µM Δ9-THC treatment reduced cell injury and increased LDH content (p = 0.019, N = 6-9). Morphology changes of HCM-spherical shape, vacuolisation of cytoplasm and swollen mitochondria-were inhibited due to Δ9-THC treatment. I/R condition affected cell viability, but 10 µM Δ9-THC decreased the number of dead cells (p = 0.005, N = 6-9). The total level of CERK was lower in the I/R group, reflecting oxidative/nitrosative stress changes. The administration of Δ9-THC effectively increased the production of CERK to the level of aerobic control (p = 0.028, N = 6-9). ROS level was significantly decreased in I/R cells (p = 0.007, N = 6-8), confirming oxidative stress, while administration of 10 µM Δ9-THC enhanced TAC in cardiomyocytes subjected to I/R (p = 0.010, N = 6-8). CONCLUSIONS: Δ9-THC promotes the viability of cardiomyocytes, improves their metabolic activity, decreases cell damage and restores heart mechanical function, serving as a cardioprotective. We proposed the use of Δ9-THC as a cardioprotective drug to be, administered before onset of I/R protocol.

Calibration and Validation of a Linear-Elastic Numerical Model for Timber Step Joints Based on the Results of Experimental Investigations.

The paper is dedicated to the numerical analysis of a single-step joint, enabling the prediction of stiffness and failure modes of both single- and double-step joints. An experimental analysis of the geometrically simplest version, the single-step joint, serves as a reference for the calibration of the subsequent finite element model. The inhomogeneous and anisotropic properties of solid timber make detailed modelling computationally intensive and strongly dependent on the respective specimen. Therefore, the authors present a strategy for simplified but still appropriate modelling for the prediction of local failure at certain load levels. The used mathematical approach is based on the linear elasticity theory and orthotropic material properties. The finite element calculations are performed in the environment of the software Abaqus FEA. The calibrated numerical model shows a good conformity until first failures occur. It allows for a satisfactory quantification of the stiffness of the connection and estimation of the force when local failure begins and is, therefore, recommended for future, non-destructive research of timber connections of various shapes.

Evaluation of different internal standardization approaches for the quantification of melatonin in cell culture samples by multiple heart-cutting two dimensional liquid chromatography tandem mass spectrometry.

We evaluate here different analytical strategies for the chromatographic separation and determination of N-acetyl-5-methoxytryptamine (MEL) and its oxidative metabolites N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK), N1-acetyl-5-methoxykynuramine (AMK) and cyclic 3-hydroxymelatonin (c3OHM) in cell culture samples. Two dimensional liquid chromatography (2D-LC) in the multiple heart-cutting mode was compared with regular 1D chromatographic separations of MEL and its oxidative metabolites. Our results showed that the use of trifluoroacetic acid (TFA) as mobile phase modifier was required to obtain a satisfactory resolution and peak shapes particularly for c3OHM. As TFA is not compatible with ESI ionization the application of the MHC mode was mandatory for a proper chromatographic separation. We evaluate also different internal standardization approaches based on the combined use of a surrogate standard (5-methoxytryptophol) and an internal standard (6-methoxytryptamine) for MEL quantification in cell culture samples obtaining unsatisfactory results both by 1D- and 2D-LC-ESI-MS/MS (from 9 ± 2 to 186 ± 38%). We demonstrate that only the application of isotope dilution Mass Spectrometry through the use of an in house synthesized 13C isotopically labelled analogue provided quantitative MEL recoveries both by using 1D- and 2D-LC-ESI-MS/MS (99±1 and 98±1. Respectively) in androgen-insensitive human prostate carcinoma PC3 cells.

The Klotho protein supports redox balance and metabolic functions of cardiomyocytes during ischemia/reperfusion injury.

BACKGROUND: Acute heart ischemia followed by reperfusion leads to overproduction of reactive oxygen/ /nitrogen species (ROS/RNS), disrupted expression of nitric oxide synthase (NOS) and unbalanced glucose metabolism. Klotho is a membrane-bound or soluble protein that exerts protective activity in many organs. While Klotho is produced mainly in the kidneys and brain, it has been recently proven that Klotho is expressed in the cardiomyocytes as well. This study aimed to show the influence of the Klotho protein on oxidative/nitrosative stress and metabolic function of the cardiomyocytes subjected to ischemia/reperfusion (I/R) injury. METHODS: Human cardiac myocytes underwent in vitro chemical I/R (with sodium cyanide and 2-deoxyglucose), in the presence or absence of the recombinant human Klotho protein. The present study included an investigation of cell injury markers, level of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX), level of oxidative/nitrosative stress and metabolic processes of the cardiomyocytes. RESULTS: Administration of Klotho protein resulted in mitigation of injury, decreased level of NOX2 and NOX4, reduced generation of ROS/RNS and hydrogen peroxide (H2O2), decreased expression of inducible NOS and limited production of nitrates/nitrites in cells under I/R. Glucose uptake and lactate production in the cardiomyocytes subjected to I/R were normalized after Klotho supplementation. CONCLUSIONS: The Klotho protein participates in the regulation of redox balance and supports metabolic homeostasis of the cardiomyocytes and hence, contributes to protection against I/R injury.