Structural basis for the binding of DNP and purine nucleotides onto UCP1.

Uncoupling protein 1 (UCP1) conducts protons through the inner mitochondrial membrane to uncouple mitochondrial respiration from ATP production, thereby converting the electrochemical gradient of protons into heat1,2. The activity of UCP1 is activated by endogenous fatty acids and synthetic small molecules, such as 2,4-dinitrophenol (DNP), and is inhibited by purine nucleotides, such as ATP3-5. However, the mechanism by which UCP1 binds to these ligands remains unknown. Here we present the structures of human UCP1 in the nucleotide-free state, the DNP-bound state and the ATP-bound state. The structures show that the central cavity of UCP1 is open to the cytosolic side. DNP binds inside the cavity, making contact with transmembrane helix 2 (TM2) and TM6. ATP binds in the same cavity and induces conformational changes in TM2, together with the inward bending of TM1, TM4, TM5 and TM6 of UCP1, resulting in a more compact structure of UCP1. The binding site of ATP overlaps with that of DNP, suggesting that ATP competitively blocks the functional engagement of DNP, resulting in the inhibition of the proton-conducting activity of UCP1.

The BCKDK inhibitor BT2 is a chemical uncoupler that lowers mitochondrial ROS production and de novo lipogenesis.

Elevated levels of branched chain amino acids (BCAAs) and branched-chain α-ketoacids are associated with cardiovascular and metabolic disease, but the molecular mechanisms underlying a putative causal relationship remain unclear. The branched-chain ketoacid dehydrogenase kinase (BCKDK) inhibitor BT2 (3,6-dichlorobenzo[b]thiophene-2-carboxylic acid) is often used in preclinical models to increase BCAA oxidation and restore steady-state BCAA and branched-chain α-ketoacid levels. BT2 administration is protective in various rodent models of heart failure and metabolic disease, but confoundingly, targeted ablation of Bckdk in specific tissues does not reproduce the beneficial effects conferred by pharmacologic inhibition. Here, we demonstrate that BT2, a lipophilic weak acid, can act as a mitochondrial uncoupler. Measurements of oxygen consumption, mitochondrial membrane potential, and patch-clamp electrophysiology show that BT2 increases proton conductance across the mitochondrial inner membrane independently of its inhibitory effect on BCKDK. BT2 is roughly sixfold less potent than the prototypical uncoupler 2,4-dinitrophenol and phenocopies 2,4-dinitrophenol in lowering de novo lipogenesis and mitochondrial superoxide production. The data suggest that the therapeutic efficacy of BT2 may be attributable to the well-documented effects of mitochondrial uncoupling in alleviating cardiovascular and metabolic disease.

Label-Free Detection of Unbound Bilirubin and Nitrophenol Explosives in Water by a Mechanosynthesized Dual Functional Zinc Complex: Recognition of Picric Acid in Various Common Organic Media.

High levels of unconjugated bilirubin (UB) in serum lead to asymptomatic and neonatal jaundice and brain dysfunctions. Herein, we have reported the detection of UB at as low as 1 µM in an aqueous alkaline medium using a Zn(II) complex. The specificity of the complex has been validated by the HPLC in the concentration window 6-90 µM, which is rare. The sensory response of the probe at physiological pH against nitro explosives developed it as an instant-acting fluorosensor for picric acid (PA) and 2,4-dinitrophenol (2,4-DNP). Spectroscopic titration provided a binding constant of 4×105  M-1 with PA. The naked eye detection was found to be 15 µM. The solid-state photoluminescent nature of the complex enabled it for PA sensing in the solid phase. Interestingly, the probe remained fluorescent in various volatile and non-volatile organic solvents. As a result, it can also detect PA and 2,4-DNP in a wide range of common organic media. NMR studies revealed the coordination of PA, 2,4-DNP, and UB to the Zn(II) center of the probe, which is responsible for the observed quenching of the probe with the analytes.

Dysregulation of CITED2 in abnormal lung development in the nitrofen rat model.

PURPOSE: CITED2 both modulates lung, heart and diaphragm development. The role of CITED2 in the pathogenesis of congenital diaphragmatic hernia (CDH) is unknown. We aimed to study CITED2 during abnormal lung development in the nitrofen model. METHODS: Timed-pregnant rats were given nitrofen on embryonic day (E) 9 to induce CDH. Fetal lungs were harvested on E15, 18 and 21. We performed RT-qPCR, RNAscope™ in situ hybridization and immunofluorescence staining for CITED2. RESULTS: We observed no difference in RT-qPCR (control: 1.09 ± 0.22 and nitrofen: 0.95 ± 0.18, p = 0.64) and in situ hybridization (1.03 ± 0.03; 1.04 ± 0.03, p = 0.97) for CITED2 expression in E15 nitrofen and control pups. At E18, CITED2 expression was reduced in in situ hybridization of nitrofen lungs (1.47 ± 0.05; 1.14 ± 0.07, p = 0.0006), but not altered in RT-qPCR (1.04 ± 0.16; 0.81 ± 0.13, p = 0.33). In E21 nitrofen lungs, CITED2 RNA expression was increased in RT-qPCR (1.04 ± 0.11; 1.52 ± 0.17, p = 0.03) and in situ hybridization (1.08 ± 0.07, 1.29 ± 0.04, p = 0.02). CITED2 protein abundance was higher in immunofluorescence staining of E21 nitrofen lungs (2.96 × 109 ± 0.13 × 109; 4.82 × 109 ± 0.25 × 109, p < 0.0001). CONCLUSION: Our data suggest that dysregulation of CITED2 contributes to abnormal lung development of CDH, as demonstrated by the distinct spatial-temporal distribution in nitrofen-induced lungs.

Practical NIR Assay Derived from Cyanine to Evaluate Intracellular H2S in Living Cell Imaging.

To monitor the biological function of H2S in real time, this investigation demonstrated the design and synthesis of a novel fluorescent probe integrated with cyanine and 2,4-dinitrophenol for the qualitative and quantitative detection of H2S. An NIR sensitive sensor (FS-HS-1) was provided with a straightforward process. Spectroscopy experiments elucidated that FS-HS-1 could selectively detect H2S in a PBS solution (containing 40% acetonitrile) with a 111-fold fluorescence enhancement at 715 nm (ex. 605 nm). The response towards NaHS occurred in less than 2 min, and the detection limit was confirmed to be as low as 4.47 ± 0.11 nmol/L. Furthermore, the probe is capable of monitoring changes in exogenous H2S concentrations within living cells with confocal and 2P imaging.

Phenolic compounds in water: Review of occurrence, risk, and retention by membrane technology.

Phenolic compounds are one of the main contributors to water source contamination worldwide. In this review, the data collected on Elsevier, Scopus, and Pubmed, considering papers published between 2000 and 2023, showed more than 60 different phenols have been identified in water matrix (<0.065-179,000,000 ng L-1). The highest concentration reported was in surface water canals in India. The most recurrent and studied compound was bisphenol A (n = 93) in concentrations ranging from 0.45 to 2,970,000 ng L-1. The solid phase extraction (HBL Oasis cartridge) and methanol as solvent was the method of pre-concentration most used followed by gas chromatography for the determination of phenols in water samples. The importance of drinking water guidelines incorporating more phenolic compounds was emphasized given the variety of these compounds quantified in water matrix. The human health risk assessment (HRA) was performed for the min-max concentrations of the pollutants reported in the literature. High HRA even at the lowest concentrations for 2-nitrophenol, 2,6-dichlorophenol, 3,4,5-trichlorophenol, 2,3,4,6-tetrachlorophenol, and 2,4-dinitrophenol was recognized. The cancer risk estimated was considered possible for 3-methylphenol, 2,4-dimethylphenol, 2,4,6-trichlorophenol, pentachlorophenol, and 2,4-dinitrophenol in the highest concentrations. The in-depth discussion of mechanisms, advantages, challenges, and carbon footprint of membrane technologies in water treatment and phenols retention demonstrated the great potential and trends for the production of safe drinking water, highlighting reverse osmosis, as a mature technology, and membrane distillation, as an emergent technology.

Non-Cardiotoxic Tetradecanoic Acid-2,4-Dinitrophenol Ester Nanomicelles in Microneedles Exert Potent Anti-Obesity Effect by Regulating Adipocyte Browning and Lipogenesis.

Sustained oral uncoupler 2,4-dinitrophenol (DNP) administration exerts prominent anti-obesity effects, but the adipose tissue off-target disadvantage leads to systemic adverse effects. A novel non-cardiotoxicity DNP delivery method using a biocompatible microneedles patch containing the amphiphilic tetradecanoic acid-DNP ester (TADNP) is described, which is synthesized via esterification on the phenolic hydroxyl of DNP. The TADNP is self-assembled as nanomicelles, which enhance the endocytosis rate of DNP by adipocytes and its permeation in isolated adipose tissues. The microenvironment of adipose tissues promotes the massive release of DNP and plasma and simulated gastrointestinal fluids. The microneedles-delivered TADNP nanomicelles (MN-TADNP) effectively deliver DNP in treated adipose tissues and reduce DNP content in off-target organs. Both oral and MN patch-delivered TADNP micelles effectively exert anti-obesity effects in a mouse model of high-fat diet-induced obesity; and noteworthily, MN-TADNP exhibit more satisfactory biosafety than oral administration. Here, a smart MN patch loaded with tetradecanoic acid-modified DNP is reported, which enhances its accumulation in adipose tissues and exerts an anti-obesity effect without causing any systemic toxicity.

The relationship between experimental 2,4-Dinitrophenol administration and neurological oxidative stress: in terms of dose, time and gender differences.

Although 2,4-DNP is claimed to promote fast weight reduction, it is also related with an intolerable high risk of serious side effects to various tissues. On the other hand, it is known to have neuroprotective effects. These different effects of 2,4-DNP may be due to the administration conditions. For this reason, in this study, it was aimed for the first time to clarify the oxidative changes that occur in the brain during the use of 2,4-DNP, depending on the dose, time and gender. For this purpose, 60 Wistar rats (30 male, 30 female) were divided into ten groups: control groups, short-term/long-term groups and low dose/high dose groups. Except for the control groups, 2,4-DNP was administered to the other groups by oral gavage. End of the experiment, thiobarbituric acid-reactive substances (TBARs), glutathione (GSH), nitric oxide (NOx) and ascorbic acid (AA) levels were measured in the brain tissues of sacrificed animals. 2,4-DNP administration showed attenuation impact on oxidative stress depending on both dose, time and gender. It can be said that it is more beneficial in terms of neuroprotection, especially in the short-term and male groups. In conclusion, our findings suggest that, depending on the dose, time, and gender, 2,4-DNP may be beneficial in the treatment of neurodegenerative disorders.

The Adsorption Efficiency of Regenerable Chitosan-TiO2 Composite Films in Removing 2,4-Dinitrophenol from Water.

In this work, the great performance of chitosan-based films blended with TiO2 (CH/TiO2) is presented to adsorb the hazardous pollutant 2,4-dinitrophenol (DNP) from water. The DNP was successfully removed, with a high adsorption %: CH/TiO2 exhibited a maximum adsorption capacity of 900 mg/g. For pursuing the proposed aim, UV-Vis spectroscopy was considered a powerful tool for monitoring the presence of DNP in purposely contaminated water. Swelling measurements were employed to infer more information about the interactions between chitosan and DNP, demonstrating the presence of electrostatic forces, deeply investigated by performing adsorption measurements by changing DNP solutions' ionic strength and pH values. The thermodynamics, adsorption isotherms, and kinetics were also studied, suggesting the DNP adsorption's heterogeneous character onto chitosan films. The applicability of pseudo-first- and pseudo-second-order kinetic equations confirmed the finding, further detailed by the Weber-Morris model. Finally, the adsorbent regeneration was exploited, and the possibility of inducing DNP desorption was investigated. For this purpose, suitable experiments were conducted using a saline solution that induced the DNP release, favoring the adsorbent reuse. In particular, 10 adsorption/desorption cycles were performed, evidencing the great ability of this material that does not lose its efficiency. As an alternative approach, the pollutant photodegradation by using Advanced Oxidation Processes, allowed by the presence of TiO2, was preliminary investigated, opening a novel horizon in the use of chitosan-based materials for environmental applications.

Pharmacological testing of therapeutics using normothermic machine perfusion: A pilot study of 2,4-dinitrophenol delivery to steatotic human livers.

INTRODUCTION: Normothermic machine perfusion (NMP) provides a platform for drug-delivery. However, pharmacological considerations for therapeutics delivered during NMP are scarcely reported. We aimed to demonstrate the ability of NMP as a platform for pharmacological testing, using a drug which increases metabolism (2,4-dinitrophenol; DNP) as an example therapeutic. METHODS: We performed 25 h of NMP on human livers which had been declined for transplant due to steatosis (n = 7). Three livers received a DNP bolus, three were controls, and one received a DNP infusion. RESULTS: Toxicity studies revealed DNP delivery was safe, without hepatotoxic effects. The liver surface temperature was increased in the DNP group (p = 0.046), but no livers suffered hyperthermia-the mechanism of DNP toxicity in vivo. Pharmacokinetic studies revealed DNP elimination with first-order kinetics and 7.7 h half-life (95% CI = 5.1-15.9 hrs). The clearance of DNP in bile was negligible. As expected, DNP significantly increased oxygen consumption (p = 0.023); this increase was closely correlated with perfusate DNP concentration (r2  = 0.975; p = 0.002) and the effect was lost as DNP was eliminated by the liver. A DNP infusion rate, calculated using our pharmacokinetic data, successfully maintained perfusate DNP concentration. DISCUSSION: Detailed pharmacological testing can be performed during NMP. Our therapeutic (DNP) is rapidly eliminated by the ex vivo liver, meaning the drug effect of increased metabolism is only transient. This demonstrates the importance of assessing pharmacokinetics when delivering therapeutics during NMP, especially for prolonged perfusion of organs with established roles in drug elimination. Rigorous pharmacological testing is needed to unlock the potential of NMP as a clinical drug-delivery platform.

Physiologically-based pharmacokinetic model for 2,4-dinitrophenol.

New approaches in drug development are needed to address the growing epidemic of obesity as the prevalence of obesity increases worldwide. 2,4-Dinitrophenol (DNP) is an oxidative phosphorylation uncoupling agent that was widely used in the early 1930s for weight loss but was quickly banned by the FDA due to the severe toxicities associated with the compound. One of the limitations leading to the demise of DNP as a pharmaceutical was a lack of understanding about the pharmacokinetic-pharmacodynamic relationship. The purpose of this study was to investigate whole body disposition of DNP in order to understand the relationship between the pharmacokinetics, efficacy and toxicity in the C57BL/6J diet induced obese mouse model. Following intravenous administration of 1 mg/kg, and intraperitoneal administration of 5 mg/kg and 15 mg/kg of DNP, we found limited DNP distribution to tissues. Experimentally measured partition coefficients were found to be less than 1 for all analyzed tissues. In addition, DNP exhibits significant nonlinear pharmacokinetics, which we have attributed to nonlinear plasma protein binding and nonlinear partitioning into liver and kidney. By enhancing our understanding of the PK-PD relationship, we can develop new approaches to leverage oxidative phosphorylation uncoupling as a weight loss strategy.

2,4-Dinitrophenol as an Uncoupler Augments the Anthracyclines Toxicity against Prostate Cancer Cells.

One of the strategies for the treatment of advanced cancer diseases is targeting the energy metabolism of the cancer cells. The compound 2,4-DNP (2,4-dinitrophenol) disrupts the cell energy metabolism through the ability to decouple oxidative phosphorylation. The aim of the study was to determine the ability of 2,4-DNP to sensitize prostate cancer cells with different metabolic phenotypes to the action of known anthracyclines (doxorubicin and epirubicin). The synergistic effect of the anthracyclines and 2,4-DNP was determined using an MTT assay, apoptosis detection and a cell cycle analysis. The present of oxidative stress in cancer cells was assessed by CellROX, the level of cellular thiols and DNA oxidative damage. The study revealed that the incubation of LNCaP prostate cancer cells (oxidative phenotype) with epirubicin and doxorubicin simultaneously with 2,4-DNP showed the presence of a synergistic effect for both the cytostatics. Moreover, it contributes to the increased induction of oxidative stress, which results in a reduced level of cellular thiols and an increased number of AP sites in the DNA. The synergistic activity may consist of an inhibition of ATP synthesis and the simultaneous production of toxic amounts of ROS, destroying the mitochondria. Additionally, the sensitivity of the LNCaP cell line to the anthracyclines is relatively higher compared to the other two (PC-3, DU-145).

Photochemical Degradation of 4-Nitrocatechol and 2,4-Dinitrophenol in a Sugar-Glass Secondary Organic Aerosol Surrogate.

The roles that chemical environment and viscosity play in the photochemical fate of molecules trapped in atmospheric particles are poorly understood. The goal of this work was to characterize the photolysis of 4-nitrocatechol (4NC) and 2,4-dinitrophenol (24DNP) in semisolid isomalt as a new type of surrogate for glassy organic aerosols and compare it to photolysis in liquid water, isopropanol, and octanol. UV/vis spectroscopy was used to monitor the absorbance decay to determine the rates of photochemical loss of 4NC and 24DNP. The quantum yield of 4NC photolysis was found to be smaller in an isomalt glass (2.6 × 10-6) than in liquid isopropanol (1.1 × 10-5). Both 4NC and 24NDP had much lower photolysis rates in water than in organic matrices, suggesting that they would photolyze more efficiently in organic aerosol particles than in cloud or fog droplets. Liquid chromatography in tandem with mass spectrometry was used to examine the photolysis products of 4NC. In isopropanol solution, most products appeared to result from the oxidation of 4NC, in stark contrast to photoreduction and dimerization products that were observed in solid isomalt. Therefore, the photochemical fate of 4NC, and presumably of other nitrophenols, should depend on whether they undergo photodegradation in a liquid or semisolid organic particle.

[Antipyretic activity and potential mechanism of Indigo Naturalis on 2,4-dinitrophenol-induced fever rat model].

As an effective antipyretic medicine,Indigo Naturalis has a long history of application in the field of Chinese medicine.The content of organics,mainly indigo and indirubin,is about 10%. However,the active ingredients and mechanism of its antipyretic effect have not yet been fully elucidated. In view of this,they were investigated in this study with the rectal temperature change as an indicator and 2,4-dinitrophenol-induced fever rats as subjects. The content of PGE2 and c AMP in the hypothalamus and the serum levels of TNF-α,IL-1ß and IL-6 were determined by ELISA. Moreover,the plasma samples of fever rats were analyzed by metabonomics in combination with UPLC-Q-TOF-MS for the exploration of potential biomarkers and the discussion on the antipyretic mechanism of Indigo Naturalis and its active ingredients. The results showed that the rising trend of rectal temperature in rats was suppressed 0. 5 h after the treatment with Indigo Naturalis,organic matter,indigo or indirubin as compared with the rats of model group( P < 0. 05),among which Indigo Naturalis and organic matter had better antipyretic effect. ELISA results showed that organic matter and indigo can inhibit the expression of PGE2 and c AMP( P<0. 01),while Indigo Naturalis and organic matter were effective in curbing the increase in TNF-α( P<0. 05). A total of 21 endogenous metabolites were identified from the plasma samples of the Indigo Naturalis,organic matter,indigo and indirubin groups,which were mainly involved in glycerophospholipid metabolism.

Bicarbonate suppresses mitochondrial membrane depolarization induced by conventional uncouplers.

Bicarbonate has been known to modulate activities of various mitochondrial enzymes such as ATPase and soluble adenylyl cyclase. Here, we found that the ability of conventional protonophoric uncouplers, such as 2,4-dinitrophenol (DNP), carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP) and carbonyl cyanide m-chlorophenyl hydrazone (CCCP), but not that of the new popular uncoupler BAM15, to decrease mitochondrial membrane potential was significantly diminished in the presence of millimolar concentrations of bicarbonate. Thus, the depolarizing activity of DNP and FCCP in mitochondria could be sensitive to the local concentration of bicarbonate in cells and tissues. However, bicarbonate could not restore the ATP synthesis suppressed by DNP or CCCP in mitochondria. Bicarbonate neither altered the depolarizing action of DNP and FCCP on proteoliposomes with reconstituted cytochrome c oxidase, nor affected the protonophoric activity of DNP and FCCP in artificial lipid membranes as measured with pyranine-loaded liposomes, thereby showing that the bicarbonate-induced reversal of the depolarizing action of DNP and FCCP on mitochondria did not result from direct interaction of bicarbonate with the uncouplers.

Death of an apprentice bodybuilder following 2,4-dinitrophenol and clenbuterol intake.

We present the case of a 17-year-old man, who died after 2,4-dinitrophenol (DNP) and clenbuterol consumption, which he likely took for physical enhancement. Forensic post-mortem examination revealed a yellowish skin colour and nonspecific signs of asphyxia. Analytical confirmation of the intoxication was obtained in blood and urine, with high levels of DNP and clenbuterol. Both of these substances are used by bodybuilders as DNP enhance lipolysis and clenbuterol has anabolic properties, but their toxicity is underestimated. DNP uncouples oxidative phosphorylation, leading to thermogenesis and even relatively small doses can cause fatal hyperthermia. Clenbuterol is a ß2 agonist that causes electrolyte disturbances (hypokalemia and hyperglycemia mostly) and death have been described through coronary vasospasm. Given the circumstances in which the body was found and toxicological results, we believe the cause of death to be fatal hyperthermia from DNP intake. These substances are illegal in many countries, but easily bought online. Through this availability, the last decades have seen an increase of fatal intoxications. Websites selling them are regularly closed by French public authorities and Interpol, but unfortunately it seems insufficient.

Diet aid or aid to die: an update on 2,4-dinitrophenol (2,4-DNP) use as a weight-loss product.

During the last decades, we have witnessed unparalleled changes in human eating habits and lifestyle, intensely influenced by cultural and social pressures. Sports practice became strongly implemented in daily routines, and visits to the gym peaked, driven by the indulgence in intensive 'weight-loss programs'. The pledge of boasting a healthy and beautiful body instigates the use of very attractive 'fat burners', which are purportedly advertised as safe products, easily available in the market and expected to quickly reduce body weight. In this context, the slimming properties of 2,4-dinitrophenol (2,4-DNP) galvanised its use as a weight-loss product, despite the drug ban for human consumption in many countries since 1938, due to its adverse effects. The main symptoms associated with 2,4-DNP intoxication, including hyperthermia, tachycardia, decreased blood pressure, and acute renal failure, motivated a worldwide warning, issued by the Interpol Anti-Doping Unit in 2015, reinforcing its hazard. Information on the effects of 2,4-DNP mainly derive from the intoxication cases reported by emergency care units, for which there is no specific antidote or treatment. This review provides a comprehensive update on 2,4-DNP use, legislation and epidemiology, chemistry and analytical methodologies for drug determination in commercial products and biological samples, pharmacokinetics and pharmacodynamics, toxicological effects, and intoxication diagnosis and management.

Efficient removal of 2,4-dinitrophenol from synthetic wastewater and contaminated soil samples using free and immobilized laccases.

Among hazardous pollutants, 2,4-Dinitrophenol (2,4-DNP) is considered highly toxic and possesses a remarkable resistance to degradation. Therefore, investigation of the possible mechanisms for removal of such pollutants is important. Laccase enzyme can decompose phenolics despite the fact that its application has been limited due to lack of possibility to reuse it. Immobilization can overcome this problem. In this paper, laccase complexes with montmorillonite K10 and zeolite were used to decompose 2,4-DNP with concentrations of 1.5 mg l-1 and 50 mg kg-1 in synthetic wastewater and soil, respectively. The maximum removal of pollutant from wastewater in samples containing laccase-zeolite and laccase-montmorillonite complexes were 99 and 93.3%, respectively, which occurred at 4 h incubation compared with 6 h for free laccase. The maximum removal of pollutant from soil was observed for all treatments after 16 h of incubation. The maximum removal for samples containing free laccase, laccase-zeolite, and laccase-montmorillonite complexes were 98.5%, 98.6%, and 90.4%, respectively. Control sample also showed maximum removal of 35.8%. In general, application of laccase-zeolite complexes in aqueous environment, and these complexes and free laccases in soil was found very effective in degradation of 2,4-DNP. Hence, the use of laccase, especially immobilized laccases, for removal of 2,4-DNP from environment is promising.

Amperometric Cytosensor for Studying Mitochondrial Interferences Induced by Plasticizers Bisphenol B and Bisphenol A.

The widespread presence of plasticizers Bisphenol B (BPB) and Bisphenol A (BPA) in food contact materials, medical equipment, and common household products is a toxicological risk factor for health due to internal exposure after environmental dietary exposure. This work describes the use of an amperometric cytosensor (i.e., a whole cell-based amperometric biosensoristic device) for studying mitochondrial interferences of BPA and BPB (5-100 µg/mL) in the yeast Saccharomyces cerevisiae model following long-term (24 h) exposure (acute toxicity). Percentage interference (%ρ) on yeast aerobic mitochondrial catabolism was calculated after comparison of aerobic respiration of exposed and control S. cerevisiae cell suspensions. Results suggested the hypothesis of a dose-dependent co-action of two mechanisms, namely uncoupling of oxidative phosphorylation and oxidative stress. These mechanisms respectively matched with opposite effects of hyperstimulation and inhibition of cellular respiration. While uncoupling of oxidative phosphorylation and oxidative stress have been previously described as separate effects from in vitro BPA exposure using other biochemical endpoints and biological systems, effects of BPB on cellular aerobic respiration are here reported for the first time. Results highlighted a similar hyperstimulation effect after exposure to 5 µg/mL BPA and BPB. About a 2-fold higher cellular respiration inhibition potency was observed after exposures to 15, 30, and 100 µg/mL BPB compared to BPA. 2,4-Dinitrophenol (2,4-DNP) was used as model uncoupling agent. A time-dependent mechanism of mitochondrial interference was also highlighted.

Increase of core temperature affected the progression of kidney injury by repeated heat stress exposure.

An epidemic of chronic kidney disease of unknown etiology (Mesoamerican nephropathy) has emerged in hot regions of Central America. We have demonstrated that dehydration associated with recurrent heat exposure causes chronic kidney disease in animal models. However, the independent influence of core body temperature on kidney injury has not been explored. In the present study, we tested the hypothesis that kidney injury could be accelerated by increasing body temperature independent of external temperature. Wild-type mice were exposed to heat (39.5°C, 30 min, 2 times daily) with or without the mitochondrial uncoupling agent 2,4-dinitrophenol (DNP) for 10 days. Core temperature, renal function, proteinuria, and renal histological and biochemical analyses were performed. Isolated mitochondria markers of oxidative stress were evaluated from kidney tissue. DNP increased body core temperature in response to heat by 1°C (42 vs. 41°C), which was transient. The mild increase in temperature correlated with worsening albuminuria (R = 0.715, P < 001), renal tubular injury, and interstitial infiltration of monocytes/macrophages. Tubular injury was marked in the outer medulla. This was associated with a reduction in kidney tissue ATP levels (nonheated control: 16.71 ± 1.33 nmol/mg and DNP + heat: 13.08 ± 1.12 nmol/mg, P < 0.01), reduced mitochondria, and evidence for mitochondrial oxidative stress. The results of the present study suggest that kidney injury in heat stress is markedly worsened by increasing core temperature. This is consistent with the hypothesis that clinical and subclinical heat stroke may play a role in Mesoamerican nephropathy.