Effect of oligomycin on NADH oxidation and its coupled phosphorylation with the particulate fraction from dark aerobically grown Rhodospirillum rubrum

Summary NADH oxidation with the particulate fraction from dark aerobically grown Rhodospirillum rubrum is significantly stimulated by the addition of phosphate (Pi) and Mg⁺⁺, or Pi, Mg⁺⁺, ATP and the hexokinase-glucose system. K _m values for Pi in NADH oxidation and phosphorylation are 10^–3 m and 8×10^–4 m, respectively. These K _m values are almost the same as in corresponding photophosphorylation and oxidative phosphorylation catalyzed with chromatophores. As in the case of NADH oxidation with chromatophores, NADH oxidation with the particulate fraction has an optimal pH at 7.5 without additions, which is shifted to 6.9 by the addition of Pi and Mg⁺⁺, or Pi, Mg⁺⁺, ATP and the hexokinase-glucose system. The optimal pH for coupled phosphorylation is 6.9. 10 g per ml of oligomycin can suppress stimulation of NADH oxidation by Pi, or by the energy trapping system, and prevent the shift of optimal pH. The particulate fraction can catalyze Pi-incorporation into glucose-6-phosphate without externally added ATP, so that Pi-incorporation is inhibited by oligomycin. From these findings, it is concluded that NADH oxidation in the particulate fraction is tightly coupled to phosphorylation.     

Environmental Factors Influencing the Hyperfine Structure of Manganous Low-Temperature Electron Paramagnetic Resonance Spectra

Hyperfine structure is observed in low temperature (T = -180°C) EPR (electron paramagnetic resonance) spectra of a number of solutions containing Mn⁺⁺ ions 13, 15) which have characteristics in common with low temperature EPR spectra from biological substances such as mitochondria and microsomes (1-4). This investigation is an attempt to understand the features of these signals in terms of the molecular environment of the manganous ion, and a qualitative explanation for the observations reported here is advanced in terms of the amount of axial distortion of a manganese hydrate in different environments.     

Characterization of Ferroplasma Isolates and Ferroplasma acidarmanus sp. nov., Extreme Acidophiles from Acid Mine Drainage and Industrial Bioleaching Environments

Three recently isolated extremely acidophilic archaeal strains have been shown to be phylogenetically similar to Ferroplasma acidiphilum Y^T by 16S rRNA gene sequencing. All four Ferroplasma isolates were capable of growing chemoorganotrophically on yeast extract or a range of sugars and chemomixotrophically on ferrous iron and yeast extract or sugars, and isolate “Ferroplasma acidarmanus” Fer1^T required much higher levels of organic carbon. All four isolates were facultative anaerobes, coupling chemoorganotrophic growth on yeast extract to the reduction of ferric iron. The temperature optima for the four isolates were between 35 and 42°C and the pH optima were 1.0 to 1.7, and “F. acidarmanus” Fer1^T was capable of growing at pH 0. The optimum yeast extract concentration for “F. acidarmanus” Fer1^T was higher than that for the other three isolates. Phenotypic results suggested that isolate “F. acidarmanus” Fer1^T is of a different species than the other three strains, and 16S rRNA sequence data, DNA-DNA similarity values, and two-dimensional polyacrylamide gel electrophoresis protein profiles clearly showed that strains DR1, MT17, and Y^T group as a single species. “F. acidarmanus” Fer1^T groups separately, and we propose the new species “F. acidarmanus” Fer1^T sp. nov.     

Calcium binding to the subunit c ofE. coli ATP-synthase and possible functional implications in energy coupling

The 8-kDa subunit c of theE. coli F₀ ATP-synthase proton channel was tested for Ca⁺⁺ binding activity using a⁴⁵Ca⁺⁺ ligand blot assay after transferring the protein from SDS-PAGE gels onto polyvinyl difluoride membranes. The purified subunit c binds⁴⁵Ca⁺⁺ strongly with Ca⁺⁺ binding properties very similar to those of the 8-kDa CF₀ subunit III of choloroplast thylakoid membranes. The N-terminal f-Met carbonyl group seems necessary for Ca⁺⁺ binding capacity, shown by loss of Ca⁺⁺ binding following removal of the formyl group by mild acid treatment. The dicyclohexylcarbodiimide-reactive Asp-61 is not involved in the Ca⁺⁺ binding, shown by Ca⁺⁺ binding being retained in twoE. coli mutants, Asp61Asn and Asp61Gly. The Ca⁺⁺ binding is pH dependent in both theE. coli and thylakoid 8-kDa proteins, being absent at pH 5.0 and rising to a maximum near pH 9.0. A treatment predicted to increase the Ca⁺⁺ binding affinity to its F₀ binding site (chlorpromazine photoaffinity attachment) caused an inhibition of ATP formation driven by a base-to-acid pH jump in whole cells. Inhibition was not observed when the Ca⁺⁺ chelator EGTA was present with the cells during the chlorpromazine photoaffinity treatment. An apparent Ca⁺⁺ binding constant on the site responsible for the UV plus chlorpromazine effect of near 80–100 nM was obtained using an EGTA-Ca⁺⁺ buffer system to control free Ca⁺⁺ concentration during the UV plus chlorpromazine treatment. The data are consistent with the notion that Ca⁺⁺ bound to the periplasimic side of theE. coli F₀ proton channel can block H⁺ entry into the channel. A similar effect occurs in thylakoid membranes, but the Ca⁺⁺ binding site is on the lumen side of the thylakoid, where Ca⁺⁺ binding can modulate acid-base jump ATP formation. The Ca⁺⁺ binding to the F₀ and CF₀ complexes is consistent with a pH-dependent gating mechanism for control of H⁺ ion flux across the opening of the H⁺ channel.This work was supported in part by grants from the Department of Energy and the U.S. Department of Agriculture.On leave from the Institute of Soil Science and Photosynthesis, Russian Academy of Science, Pushchino, Russia.     

Studies on ATP hydrolysis in medium for histochemical demonstration of ATPase activity

Summary Nonenzymatic ATP hydrolysis in medium of Wachstein and Meisel for histochemical demonstration of ATPase activity was investigated. In this medium considerable amounts of phosphorus are released without the participation of the enzyme. ATP hydrolysis in Wachstein-Meisel's medium increase with the concentration of Pb⁺⁺ and decrease at its small concentrations. The degree of ATP hydrolysis appeared to increase with increase both temperature and pH. At high concentration of ATP (5.76 mM) the degree of ATP hydrolysis in Wachstein-Meisel's medium is lower than at 1.44 mM ATP. 10.0 mM Ca⁺⁺ or 3.6 mM Fe⁺⁺ speed up ATP hydrolysis after 30- and 60-minute incubation. In the presence of 3.6 mM Co⁺⁺ or 2.6 mM Cu⁺⁺ ATP hydrolysis in Wachstein-Meisel's medium increased throughout the whole period examined. On the contrary, 3.6 mM Fe⁺⁺⁺ decreases ATP hydrolysis in this medium.10.0 mM F^– raises the degree of ATP hydrolysis which is, however, lowered in the presence of 2.5 mM pCMB or 3.6 mM KCN. 2.0 mM cysteine highly inhibits the process of nonenzymatic ATP hydrolysis in Wachstein-Meisel's medium.These data show that the histochemical reaction for ATPase activity in Wachstein-Meisel's medium does not originate exclusively from the hydrolysis of ATP in the presence of Pb⁺⁺, but take rise, above all, as a result of an enzymatic reaction.     

The binding of thyrotropin to liposomes containing gangliosides.

The relationship between uptake of Ca⁺⁺ and incorporation of sn-[¹⁴C]-glycerol-3-phosphate into phosphatidate, diglyceride, and triglyceride was evaluated in microsomes isolated from livers of normal fed male rats. Uptake of Ca⁺⁺ was dependent on concentration of Ca⁺⁺ (0.1 – 2.5 mM), and accompanied by a decrease in the rate of glycerolipid synthesis. The quantity of Ca⁺⁺ ion taken up at 20 μM CaCl₂ in the presence of ATP was equivalent to that observed with 2.5 mM CaCl₂ in the absence of ATP. The ATP dependent uptake of Ca⁺⁺, like the passive uptake at higher concentrations of Ca⁺⁺, was correlated with inhibition of incorporation of sn-glycerol-3-phosphate into phosphatidate. Accumulation of Ca⁺⁺ in hepatic microsomes, therefore, appears to result in a calcium-dependent decrease in biosynthesis of phosphatidate and other glycerolipids.     

Histochemical study of TPPase and NDPase in the human nervous tissue,with particular reference to glia cells

Summary TPPase and IDPase activities were investigated in normal and reactive human nervous tissue with three divalent ions as activators at different concentrations. Enzyme distribution in neuronal Golgi apparatus, vessels and glia cells is described. In glia cells IDP was hydrolyzed almost equally with the different ions at the concentration of 0.005 M, while TPP was only weakly hydrolyzed with Ca⁺⁺ and Mg⁺⁺. Small positive structures in the cells remained positive and for these a correspondence with the Golgi apparatus is suggested.Partially supported by Consiglio Nazionale delle Ricerche (C.N.R), Rome.     

Observation of calcium uptake by isolated sarcoplasmic reticulum employing a fluorescent chelate probe

The fluorescent chelate probe technique is employed to observe the accumulation and binding of Ca⁺⁺ to isolated sarcoplasmic reticulum from skeletal and cardiac muscle. Chlorotetracycline serves as a fluorescent chelate probe which chelates to membrane bound Ca⁺⁺ giving rise to an intensely fluorescence adduct. An increase in fluorescence of chlorotetracycline is caused by ATP induced Ca⁺⁺ transport in both skeletal and cardiac muscle microsomes. The fluorescence spectra indicate that Ca⁺⁺ lies on the membrane surface in a relatively polar environment.     

Cation activation of desoxyribonuclease

The activation of desoxyribonuclease on desoxyribonucleate, known to occur with Mg⁺⁺ and Mn⁺⁺, has been shown to occur equally well with Co⁺⁺, to nearly the same extent with Fe⁺⁺, and to a lesser extent with Ca⁺⁺, Ba⁺⁺, Sr⁺⁺, Ni⁺⁺, Cd⁺⁺, and Zn⁺⁺. The conditions under which the optimal activation is revealed vary among these ions. Thus, Mg⁺⁺, Mn⁺⁺, and Co⁺⁺ may show marked activation under conditions in which Fe⁺⁺ is nearly ineffective. Since too high a concentration of an ion may be as ineffective as too little, concentration-activation curves were determined for each ion. Per micromole of nucleic acid phosphorus, the optimal effective amount of each ion in micromoles is as follows: Mg⁺⁺ 3, Mn⁺⁺ 3, Co⁺⁺ 3, Fe⁺⁺ 0.3, Ni⁺⁺ 0.3, Ba⁺⁺ 1.7, Ca⁺⁺ 3, Sr⁺⁺ 3, Zn⁺⁺ 0.3, and Cd⁺⁺ 0.3.The optimum pH for the activation with Mg⁺⁺, Co⁺⁺, and Ca⁺⁺ is about 6.5, that with Fe⁺⁺ is at 5.7, while Mn⁺⁺ shows two optima at pH 6.8 and 8.0.Experiments conducted in Pyrex and in quartz vessels showed the same results, and indicated that there was no activation of desoxy-ribonuclease in the absence of added salts.     

Studies on the Acid-protease of Paecilomyces varioti Bainier TPR-220

The crystalline acid-protease of Paecilomyces varioti Bainier TPR-220 is most active toward casein as substrate, at pH 3.0 and 60°C, and stable at pH 3.0 to 6.0 below 40°C. The enzyme decomposes protein molecules into smaller fragments than pepsin does and is inhibited by p-chloromercuri-benzoate, monoiodoacetate, sodium lauryl sulfate, iodine, potassium permanganate, N-bromosuccinimide, bacitracin, nitrofurylacrylamide, and Hg⁺ ion, but affected neither by metal ion except Hg⁺ ion, nor metal chelating agent, soy bean trypsin inhibitor, potato-protease inhibitior, cysteine, diiso-propylfluorophosphate, cyanogen bromide, and heparin. The presence of Ca⁺⁺, Co⁺⁺, Cu⁺⁺, Mg⁺⁺, Sr⁺⁺, and Zn⁺⁺ ions prevents heat inactivation of the enzyme.     

A study of sodium release in the course of ATP hydrolysis by membrane ATPase

Summary With the aid of sodium-sensitive glass electrodes, changes in sodium ion activity were studied in the course of subsequent additions of components required for ATP hydrolysis provided by Na⁺–K⁺-dependent membrane ATPase. Membrane ATPase was obtained from guinea pig kidney cortex. In the presence of ATP, Mg⁺⁺ and Na⁺ in media, the addition of K⁺ caused an increase in Na⁺ activity. The omission of ATP or its substitution by ADP as well as the addition of Ca⁺⁺ to the media eliminated the above-mentioned increase of Na⁺ activity. Quabain did not affect Na⁺ release caused by the addition of K⁺, although it significantly inhibited ATPase activity of the preparation. The data obtained were considered to be a direct indication of ion exchange during the course of membrane ATPase reaction. This ion-exchange stage of the reaction is not inhibited by ouabain. The ratio of sodium ions released per one inorganic phosphate formed in the course of the reaction was found to be much higher than that established for transporting membranes of intact cells. A possible cause of this difference is discussed.     

Electron microscopic observations on the mitochondrial adenosinetriphosphatase in the rat spinal cord

Summary Nucleosidetriphosphatase activity of the rat spinal cord was studied with a modified Wachstein-Meisel method at ultrastructural level. A short formaldehyde perfusion fixation favoured the preservation of the mitochondrial activity.The reaction product was localized intramitochondrially in the neuropil, while the pericaryonal mitochondria were nonreactive. Similar results were obtained, when ITP was substituted for ATP. No membrane activity was observed by Mg⁺⁺ activation only, but a certain membrane affinity was noticed in the neuropil, when Na⁺ and K⁺ were included.The specificity of the ATPase reaction reported in this paper is further discussed.Abbreviations used ATP adenosinetriphosphate - ATPase adenosinetriphosphatase - IDP inosinediphosphate - ITP inosinetriphosphate - TPP thiaminepyrophosphate - UDP uridinediphosphate     

Electron spin resonance of myosin spin labeled at the S1 thiol groups during hydrolysis of adenosine triphosphate

On the addition of Mg²⁺ and ATP the electron spin-resonance spectrum of the spin label, N-(1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl)-iodoacetamide, selectively bound to the S₁ thiol groups of myosin changes from the one characteristic of strong immobilization to one indicating weaker immobilization. The latter spectrum persists during the steady state of hydrolysis of ATP; when hydrolysis is complete it changes to a spectrum identical with that produced by ADP. This third spectrum indicates a mobility between that of the label on myosin in the absence of ATP and that found during the steady state. The same results are obtained with heavy meromyosin or subfragment-1. The appearance of the spectrum typical of the steady state requires the presence of a divalent cation; either Ca²⁺ or Mg²⁺ is effective. It also seems to require hydrolysis of ATP since it is not observed in the absence of activating cations, when hydrolysis has been inhibited with N-ethylmaleimide, or when nonhydrolyzable analogs of ATP are used. One of these, β,γ-imino-adenosinetriphosphate, produces the same spectral change as ADP. These different spectra have been interpreted in terms of the kinetic scheme developed by Lymn and Taylor for native myosin in which the rate-limiting step follows the rapid hydrolysis of the terminal phosphate of ATP. Ourpresent observation of an “initial burst” of P_iliberation with S₁-labeled myosin justifies the application of this scheme. According to this scheme the intermediate responsible for the steady-state spectrum contains the products of ATP hydrolysis but its spectrum is distinct from the complex formed by adding products. This suggests the presence of two spectrally distinct myosin-product complexes. The changes in esr spectra probably reflect localized conformational changes in the head of the myosin molecule. Reducing the pH, temperature, or salt concentration substantially reduces the mobility of the spin labels during the hydrolysis of ATP, suggesting that the conformation of myosin during the steady state may depend on the temperature, pH, and concentration of salt. Alternatively, the spectral changes may be brought about by a change in the relative concentrations of two or more spectrally distinct steady-state intermediates. Changes in these parameters have little or no effect on spectra recorded in the absence of substrate.     

Concentration changes of some elements during a year cycle in Lake Vechten

During summer-stratification in Lake Vechten (May–October) a great number of chemical parameters show variations. The concentration patterns of calcium, manganese and iron have been studied in some detail.The calcium concentration in the epilimnion is controlled by carbonate-formation; in the hypolimnion however, no saturation with respect to calcium-carbonate is reached, due to the fact, that carbondioxide equilibrium with the atmosphere no longer exists. The concentration pattern in the hypolimnion (max. concentration about 80 mg.l^–1 near the sediment, 40 mg.l^–1 in epilimnion) is controlled by the velocity of calcium transport from the sediment and perhaps by dissolution of precipitating carbonates from the epilimnion.The maximum manganese concentration in the hypolimnion (about 5 mg.l^–1) is controlled by the solubility of manganese carbonate, causing, together with manganese transport from the sediment, a uniform concentration up to two meters above the bottom. In the epi- and meta-limnion the presence of oxygen is limiting the concentration of manganese.The iron concentration in the hypolimnion shows a strong gradient existing until the overturn (max. concentration near the sediment about 20 mg.l^–1) and is controlled by a number of mechanisms: 1^o. Oxidation by oxygen and manganese oxides near the epilimnion. 2^o. Precipitation by sulphide formation; a strong correlation exists at different depths between sulphate disappearance and a slower increase of iron concentration. 3^o. Transport from the sediment.Control of iron concentration by carbonate formation is unlikely, as the solubility product of iron carbonate is greatly exceeded (10–100 fold). The relative importance of the other processes is not yet known.To describe iron- and manganese dynamics in relation to the cycle of reducing power, generated in primary production we need data about precipitating quantities of iron and manganese compounds, for which suitable sediment-traps must be developed.     

The Accumulation of Calcium Ions by Sarcotubular Vesicles

The accumulation of Ca⁺⁺ by microsomal (sarcotubular) preparations of rabbit skeletal muscle in the presence of oxalate, and the concurrent splitting of nucleoside triphosphate, displayed moderate nucleotide specificity in the sequence ATP > GTP, CTP, ITP > UTP > (ADP) > ATetraP for the former, ATP > (ADP) > ITP > GTP > CTP > UTP > ATetraP for the latter process. The "calcium pump" was weakly inhibited by caffeine, and was inhibited together with the ATPase by pyridoxalphosphate. Carnosine had no effect as such nor in the presence of pyridoxalphosphate except at high concentration; thiourea and p-chloromercuribenzoate were inhibiting while iodoacetate was inactive. Ca⁺⁺ accumulation and ATPase were inhibited by atabrine (not tested on ATPase), dinitrophenol, and amytal. High concentrations of oligomycin and rutamycin inhibited Ca⁺⁺ uptake while slightly stimulating ATPase. Antimycin A stimulated the Ca⁺⁺ uptake. These results are discussed in the light of their possible relation to partial reactions in oxidative phosphorylation. The Ca⁺⁺ uptake and relaxing factor activities did not behave identically throughout. This is in part ascribed to changes in reactivity of actomyosin in the relaxation test, in part to the participation of relaxing substances other than the calcium pump.     

Studies on the Pentose Isomerases of Lactic Acid Bacteria

d-Xylose isomerase requires manganese ions for its action, but l-arabinose isomerase has a less specific on metal requirement. l-Arabinose isomerase is activated by addition of Mn⁺⁺ or Co⁺⁺, less effectively by addition of Zn⁺⁺, Ca⁺⁺, Mg⁺⁺, Sr⁺⁺ or Cd⁺⁺. Moreover, manganese and potassium ions for d-xylose isomerase, and manganese and cobaltous ions for l-arabinose isomerase were also shown to have protective effect on respective enzymes against thermal inactivation.     

Effect of lipid on the access of ATP and calcium to the delipidated Ca++-ATPase of intestinal brush border membrane.

The delipidated Ca⁺⁺-ATPase prepared from intestinal brush border membranes showed a higher activity of Ca⁺⁺-independent ATPase, a lower Km value for ATP and a higher Km value for Ca⁺⁺ than its original membrane Ca⁺⁺-ATPase. The addition of phosphatidylcholine re-activated the delipidated Ca⁺⁺-ATPase to approximately 89 % of its original membrane Ca⁺⁺-ATPase activity but did not restore the affinity for Ca⁺⁺. This phospholipid raised the Km value for ATP but had little effect on the Km value for Ca⁺⁺. Palmitic acid elevated the Km value for Ca⁺⁺ but did not change the Km value for ATP. Kinetic analyses of these data suggest that the hydrocarbon chain of phosphatidylcholine is an important rate-limiting factor for the access of Ca⁺⁺ to the enzyme and the polar head groups of phosphorylcholine and ester bond may be the factor for the access of ATP.     

Acquisition of Iron by Alkaliphilic Bacillus Species

The biochemical and molecular mechanisms used by alkaliphilic bacteria to acquire iron are unknown. We demonstrate that alkaliphilic (pH > 9) Bacillus species are sensitive to artificial iron (Fe³⁺) chelators and produce iron-chelating molecules. These alkaliphilic siderophores contain catechol and hydroxamate moieties, and their synthesis is stimulated by manganese(II) salts and suppressed by FeCl₃ addition. Purification and mass spectrometric characterization of the siderophore produced by Caldalkalibacillus thermarum failed to identify any matches to previously observed fragmentation spectra of known siderophores, suggesting a novel structure.Iron is an abundant element in nature; however, in most aqueous aerobic environments iron forms insoluble ferric hydroxide, Fe(OH)₃. This poses a major problem for most aerobic bacteria, as ferric hydroxide has a solubility constant of 10⁻³⁹ M, therefore limiting the concentration of ferric ions to 10⁻¹⁸ M at pH 7.0. For example, bacteria living in seawater (approximate pH 8.0) require iron, yet dissolved iron is only present at 0.02 to 2.0 nM (5). Despite this apparent lack of bioavailability, iron has been repeatedly demonstrated to be an essential element for aerobic bacterial growth (1).With the lack of readily accessible iron at physiological pH, most bacteria have evolved systems to deal with the incumbent problem of iron acquisition. Under iron-rich conditions, Fe²⁺ uptake receptors, such as FeoAB, are synthesized in bacteria, which passively import iron in the immediate vicinity of the cell (1, 23). No equivalent system has been identified for Fe³⁺ transport. To acquire Fe³⁺ under aqueous aerobic conditions, bacteria commonly have import systems involving the synthesis, secretion, and regathering of a group of secondary metabolites known as siderophores (1, 11). Siderophores are low-molecular-weight chemical moieties that chelate Fe³⁺ and typically have complex formation (K_f) constants in the range of 10²³ to 10⁵² (11). Siderophores, like other chelators, are known to increase the solubility of iron by hindering the formation of Fe-oxyhydroxides at high pH, at which the Fe-oxyhydroxides are the dominating inorganic species (27). Siderophores are also known to facilitate the dissolution of Fe from minerals (3). Siderophore-iron complexes can either be transported through cellular membranes using dedicated transport systems or if the Fe(III) central atom is reduced, making the iron bioavailable for cellular processes (10, 14). Three major groups of siderophores have been described in bacteria: hydroxamates, catecholates, and carboxylates. Hydroxamates and catechols are commonly produced by aerobic bacteria living at neutral to alkaline pH, whereas carboxylates are significantly more common in bacteria living in mildly acidic pH (11-13). In the genus Bacillus, Bacillus megaterium and Bacillus subtilis are producers of schizokinen and bacillibactin, respectively (6, 20). Bacillus anthracis produces both a catechol and a hydroxamate siderophore (7, 34), and B. licheniformis strain VK21 is the only known example of a thermoresistant catecholate-producing Gram-positive bacterium (32).Although there is extensive literature on iron capture mechanisms in bacteria that thrive at neutral pH, there is little information at a biochemical or molecular level on how aerobic bacteria growing at extreme alkaline pHs (i.e., pH 9 to 11) acquire iron. At alkaline pH, the solubility constant for iron decreases far below the requirement for living cells, and the concentration of bioavailable iron is estimated to be approximately 10⁻²³ M at pH 10 (11). Taking this extreme lack of iron into account, the sequestering mechanisms of alkaliphilic bacteria must be powerful, yet there has been little analysis of the types of iron-chelating molecules these bacteria produce.     

Volatile Organic Compounds in Uremia

Background

Although “uremic fetor” has long been felt to be diagnostic of renal failure, the compounds exhaled in uremia remain largely unknown so far. The present work investigates whether breath analysis by ion mobility spectrometry can be used for the identification of volatile organic compounds retained in uremia.

Methods

Breath analysis was performed in 28 adults with an eGFR ≥60 ml/min per 1.73 m², 26 adults with chronic renal failure corresponding to an eGFR of 10–59 ml/min per 1.73 m², and 28 adults with end-stage renal disease (ESRD) before and after a hemodialysis session. Breath analysis was performed by ion mobility spectrometryafter gas-chromatographic preseparation. Identification of the compounds of interest was performed by thermal desorption gas chromatography/mass spectrometry.

Results

Breath analyses revealed significant differences in the spectra of patients with and without renal failure. Thirteen compounds were chosen for further evaluation. Some compounds including hydroxyacetone, 3-hydroxy-2-butanone and ammonia accumulated with decreasing renal function and were eliminated by dialysis. The concentrations of these compounds allowed a significant differentiation between healthy, chronic renal failure with an eGFR of 10–59 ml/min, and ESRD (p<0.05 each). Other compounds including 4-heptanal, 4-heptanone, and 2-heptanone preferentially or exclusively occurred in patients undergoing hemodialysis.

Conclusion

Impairment of renal function induces a characteristic fingerprint of volatile compounds in the breath. The technique of ion mobility spectrometry can be used for the identification of lipophilic uremic retention molecules.