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PubMed2005

Airways, respiration, and respiratory sinus arrhythmia during picture viewing.

Emotional stimuli can cause airway constriction; however, it is uncertain whether a dimensional or categorical model of emotion can better describe airway changes. Also, little is known about the affective modulation of respiration and vagal activity, which can influence airway tone. We studied changes in oscillatory resistance (Ros), respiration, and respiratory sinus arrhythmia (RSA) in asthmatics and controls during viewing of affective pictures eliciting anxiety, depression, disgust, happiness, contentment, erotic tension, or neutral affect. Ros, respiration, cardiac activity, and self-report were measured during picture presentations. Ros increased monotonically with picture unpleasantness mainly due to disgust pictures. RSA and respiratory timing parameters were particularly sensitive to erotic pictures. Differences between asthmatics and controls were minimal, suggesting that airway responses to unpleasant pictures are not specific to asthma.

Adult↗
PubMed1991

Dopaminergic neurotoxicity in vivo and inhibition of mitochondrial respiration in vitro by possible endogenous pyridinium-like substances.

Elucidation of the mechanism(s) by which 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP) and its active metabolite 1-methyl-4-phenylpyridinium (MPP+) cause parkinsonism in humans and other primates has prompted consideration of possible endogenous MPTP/MPP(+)-like neurotoxins in the etiology of idiopathic Parkinson's disease. Here we examined inhibition of mitochondrial respiration in vitro and neurotoxicity in rats in vivo produced by beta-carbolinium compounds that are presumed to form following Pictet-Spengler cyclization of serotonin. We also evaluated N-methylisoquinolinium, a putative endogenous neurotoxin, in the same manner. The latter compound exhibited MPP(+)-like mitochondrial respiratory inhibition, whereas the beta-carbolinium compounds, although more potent inhibitors of electron transport, exhibited weak accumulation-dependent enhancement of inhibition in intact mitochondria. It is interesting that the beta-carbolinium compounds inhibited succinate- as well as glutamate-supported respiration, and are best described as inhibitor-uncouplers. The results of partitioning experiments suggest that both the low accumulation potential and the inhibition of succinate respiration may be a consequence of the beta-carboliniums being in equilibrium with neutral "anhydro" bases. Relative to MPP+, all compounds tested had weak dopaminergic uptake activity in vitro and weak dopaminergic toxicity in vivo, consistent with other findings of relatively low neurotoxic potential for presumed endogenous pyridiniums.

1-Methyl-4-phenylpyridinium↗
PubMed1959

Some effects of reserpine and hydraliazine upon tissue respiration and the concentration of adenosine nucleotides in certain tissues.

The effects of reserpine and hydrallazine upon the oxygen uptake of preparations of rat brain, liver, and kidney and rabbit aorta have been investigated using the Warburg "Direct" method. In these tissues reserpine did not significantly stimulate respiration at any of the doses used. Concentrations of 10 or 50 mug./ml. had no significant effect upon respiration, but higher doses (330 mug./ml.) depressed it in all the tissues studied. This effect was also seen in rat brain at a reserpine concentration of 100 mug./ml. which had no significant effect in other tissues. Hydrallazine (50 or 100 mug./ml.) depressed respiration in all tissues studied. Stimulation at lower doses was not seen.After sublethal doses of reserpine, depletion of energy rich phosphate compounds occurred in brain and liver but not in skeletal muscle and heart. Hydrallazine also depleted brain of energy rich phosphate compounds, but did not affect liver, heart, or skeletal muscle. The bearing of these results on the mode of action of reserpine and hydrallazine is discussed.

Adenosine↗
PubMed1995

Effects of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors on mitochondrial respiration in ischaemic dog hearts.

1. Effects of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, pravastatin and simvastatin, on the myocardial level of coenzyme Q10, and on mitochondrial respiration were examined in dogs. 2. Either vehicle (control), pravastatin (4 mg kg-1 day-1), or simvastatin (2 mg kg-1 day-1) was administered orally for 3 weeks. First, the myocardial tissue level of coenzyme Q10 was determined in the 3 groups. Second, ischaemia was induced by ligating the left anterior descending coronary artery (LAD) in anaesthetized open chest dogs, pretreated with the inhibitors. After 30 min of ischaemia, nonischaemic and ischaemic myocardium were removed from the left circumflex and LAD regions, respectively, and immediately used for isolation of mitochondria. The mitochondrial respiration was determined by polarography, with glutamate and succinate used as substrates. 3. Simvastatin significantly decreased the myocardial level of coenzyme Q10, but pravastatin did not. 4. Ischaemia decreased the mitochondrial respiratory control index (RCI) in both groups. Significant differences in RCI between nonischaemic and ischaemic myocardium were observed in the control and simvastatin-treated groups. 5. Only in the simvastatin-treated group did ischaemia significantly decrease the ADP/O ratio, determined with succinate. 6. The present results indicate that simvastatin but not pravastatin may cause worsening of the myocardial mitochondrial respiration during ischaemia, probably because of reduction of the myocardial coenzyme Q10 level.

Animals↗
PubMed1999

Detection of genes for periplasmic nitrate reductase in nitrate respiring bacteria and in community DNA.

A nested PCR primed by four degenerate oligonucleotides was developed for the specific amplification of sequences from the napA gene encoding the periplasmic nitrate reductase. This approach was used to amplify fragments of the napA gene from 10 Pseudomonas species and one Moraxella sp., previously shown to be able to express the periplasmic nitrate reductase activity, from Rhodobacter capsulatus and from community DNA extracted from a fresh-water sediment. Amino acid sequences encoded by the napA fragments were compared to one another and to the corresponding regions of related enzymes. This comparison indicates that the amplification protocol is specific for its intended target. The napA sequences amplified from community DNA were tightly clustered, which may indicate a degree of homogeneity in the sediment community. All tested Gram-negative strains capable of aerobic nitrate respiration were found to have periplasmic nitrate reductase genes. However, some strains which have and express the genes are incapable of aerobic nitrate respiration. The PCR primers and amplification protocols described will be useful in future studies of nitrate respiring populations.

Amino Acid Sequence↗
PubMed1976

Plutonium hazard in respirable dust on the surface of soil.

Plutonium-239 in the fine particulate soil fraction of surface dust is subject to suspension by air currents and is a potential health hazard to humans who may inhale it. This respirable particulate fraction is defined as particles less than or equal to 5 micrometers. The respirable fraction of surface dust was separated by ultrasonic dispersion and a standard water-sedimentation procedure. Plutonium concentration in this fraction of off-site soils located downwind from the Rocky Flats Nuclear Weapons Plant (Jefferson County, Colorado) were as much as 380 times the background concentration. It is prposed that this method of evaluation defines more precisely the potential health hazard from the respirable fraction of plutonium-contaminated soils.

Colorado↗
PubMed2001

Inhibitory activities of lansoprazole against respiration in Helicobacter pylori.

Lansoprazole and its derivative AG-1789 dose-dependently inhibited cellular respiration by an endogenous substrate and decreased the ATP level in Helicobacter pylori cells. The inhibitory action of lansoprazole and AG-1789 against respiration was specific to substrates such as pyruvate and alpha-ketoglutarate and similar to the inhibitory action of rotenone, which is an inhibitor for the mitochondrial respiratory chain. Growth inhibition by lansoprazole and AG-1789 as well as by rotenone was augmented at high oxygen concentrations under atmospheric conditions. Since the 50% inhibitory concentrations of these compounds for the respiration were close to their MICs for H. pylori growth, the growth inhibition might be due to respiratory inhibition by these compounds.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2004

Fusidic acid-resistant mutants of Salmonella enterica serovar typhimurium have low levels of heme and a reduced rate of respiration and are sensitive to oxidative stress.

Mutations in the translation elongation factor G (EF-G) make Salmonella enterica serovar Typhimurium resistant to the antibiotic fusidic acid. Fus(r) mutants are hypersensitive to oxidative stress and rapidly lose viability in the presence of hydrogen peroxide. We show that this phenotype is associated with reduced activity of two catalase enzymes, HPI (a bifunctional catalase-hydroperoxidase) and HPII (a monofunctional catalase). These catalases require the iron-binding cofactor heme for their activity. Fus(r) mutants have a reduced rate of transcription of hemA, a gene whose product catalyzes the first committed step in heme biosynthesis. Hypersensitivity of Fus(r) mutants to hydrogen peroxide is abolished by the presence of delta-aminolevulinic acid, the precursor of heme synthesis, in the growth media and by the addition of glutamate or glutamine, amino acids required for the first step in heme biosynthesis. Fluorescence measurements show that the level of heme in a Fus(r) mutant is significantly lower than it is in the wild type. Heme is also an essential cofactor of cytochromes in the electron transport chain of respiration. We found that the rate of respiration is reduced significantly in Fus(r) mutants. Sequestration of divalent iron in the growth media decreases the sensitivity of Fus(r) mutants to oxidative stress. Taken together, these results suggest that Fus(r) mutants are hypersensitive to oxidative stress because their low levels of heme reduce both catalase activity and respiration capacity. The sensitivity of Fus(r) mutants to oxidative stress could be associated with loss of viability due to iron-mediated DNA damage in the presence of hydrogen peroxide. We argue that understanding the specific nature of antibiotic resistance fitness costs in different environments may be a generally useful approach in identifying physiological processes that could serve as novel targets for antimicrobial agents.

Anti-Bacterial Agents↗
PubMed1974

Studies on the mechanism of action of miconazole: effect of miconazole on respiration and cell permeability of Candida albicans.

The antifungal drug, miconazole nitrate, inhibits the growth of several species of Candida. Candida albicans, one of the pathogenic species, was totally inhibited at a concentration of approximately 10 mug/ml. Endogenous respiration was unaffected by the drug at a concentration as high as 100 mug/ml, whereas exogenous respiration was markedly sensitive and inhibited to an extent of 85%. The permeability of the cell membrane was changed as evidenced by the leakage of 260-nm absorbing materials, amino acids, proteins, and inorganic cations. The results we present clearly show that the drug alters the cellular permeability, and thus the exogenous respiration becomes sensitive to the drug.

Antifungal Agents↗
PubMed1981

Long-term effects of crude oil on uptake and respiration of glucose and glutamate in arctic and subarctic marine sediments.

The effects of crude oil on uptake and respiration (mineralization) of glucose and glutamate in marine sediments were investigated. After the sediments were treated with crude oil, they were replaced at or near the collection site by scuba divers. These sediments remained in situ until they were retrieved for analysis. Glucose and glutamate uptake rates were found to decrease, and the percent respired was found to increase in Arctic and subarctic marine sediments that had been exposed to fresh crude oil. These same changes were also observed when "weathered" crude oil was used and when untreated sediments were overlaid with oiled sediments. When the kinetics of glutamate uptake were determined, both the maximum potential uptake rate and the turnover time were significantly affected. A comparison between the proportion of glucose taken into the cells and that respired as CO(2) indicated that crude oil affected biosynthetic mechanisms. A study of sediments that had been exposed to crude oil for at least 5 months showed that glutamate transport into the cells was affected more extensively than biosynthetic mechanisms. In the initial months of exposure, bacterial concentrations and total adenylate concentrations were found to decrease in the presence of crude oil. Our data suggest that secondary productivity in the marine environment could be adversely affected by the presence of crude oil in marine sediments.

Journal Article↗
PubMed1986

Relative rates of nitric oxide and nitrous oxide production by nitrifiers, denitrifiers, and nitrate respirers.

Biogenic emissions of nitric and nitrous oxides have important impacts on the photochemistry and chemistry of the atmosphere. Although biogenic production appears to be the overwhelming source of N(2)O, the magnitude of the biogenic emission of NO is very uncertain. In soils, possible sources of NO and N(2)O include nitrification by autotrophic and heterotrophic nitrifiers, denitrification by nitrifiers and denitrifiers, nitrate respiration by fermenters, and chemodenitrification. The availability of oxygen determines to a large extent the relative activities of these various groups of organisms. To better understand this influence, we investigated the effect of the partial pressure of oxygen (pO(2)) on the production of NO and N(2)O by a wide variety of common soil nitrifying, denitrifying, and nitrate-respiring bacteria under laboratory conditions. The production of NO per cell was highest by autotrophic nitrifiers and was independent of pO(2) in the range tested (0.5 to 10%), whereas N(2)O production was inversely proportional to pO(2). Nitrous oxide production was highest in the denitrifier Pseudomonas fluorescens, but only under anaerobic conditions. The molar ratio of NO/N(2)O produced was usually greater than unity for nitrifiers and much less than unity for denitrifiers. Chemodenitrification was the major source of both the NO and N(2)O produced by the nitrate respirer Serratia marcescens. Chemodenitrification was also a possible source of NO and N(2)O in nitrifier cultures but only when high concentrations of nitrite had accumulated or were added to the medium. Although most of the denitrifiers produced NO and N(2)O only under anaerobic conditions, chemostat cultures of Alcaligenes faecalis continued to emit these gases even when the cultures were sparged with air. Based upon these results, we predict that aerobic soils are primary sources of NO and that N(2)O is produced only when there is sufficient soil moisture to provide the anaerobic microsites necessary for denitrification by either denitrifiers or nitrifiers.

Journal Article↗
PubMed1991

Energy Transduction by Anaerobic Ferric Iron Respiration in Thiobacillus ferrooxidans.

Formate-grown cells of the obligately chemolithoautotrophic acidophile Thiobacillus ferrooxidans were capable of formate- and elemental sulfur-dependent reduction of ferric iron under anaerobic conditions. Under aerobic conditions, both oxygen and ferric iron could be simultaneously used as electron acceptors. To investigate whether anaerobic ferric iron respiration by T. ferrooxidans is an energy-transducing process, uptake of amino acids was studied. Glycine uptake by starved cells did not occur in the absence of an electron donor, neither under aerobic conditions nor under anaerobic conditions. Uptake of glycine could be driven by formate- and ferrous iron-dependent oxygen uptake. Under anaerobic conditions, ferric iron respiration with the electron donors formate and elemental sulfur could energize glycine uptake. Glycine uptake was inhibited by the uncoupler 2,4-dinitrophenol. The results indicate that anaerobic ferric iron respiration can contribute to the energy budget of T. ferrooxidans.

Journal Article↗
PubMed1992

Use of a fluorescent redox probe for direct visualization of actively respiring bacteria.

The redox dye 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) was employed for direct epifluorescent microscopic enumeration of respiring bacteria in environmental samples. Oxidized CTC is nearly colorless and is nonfluorescent; however, the compound is readily reduced via electron transport activity to fluorescent, insoluble CTC-formazan, which accumulates intracellularly. Bacteria containing CTC-formazan were visualized by epifluorescence microscopy in wet-mount preparations, on polycarbonate membrane filter surfaces, or in biofilms associated with optically opaque surfaces. Counterstaining of CTC-treated samples with the DNA-specific fluorochrome 4',6-diamidino-2-phenylindole allowed enumeration of active and total bacterial subpopulations within the same preparation. Municipal wastewater, groundwater, and seawater samples supplied with exogenous nutrients yielded CTC counts that were generally lower than total 4',6-diamidino-2-phenylindole counts but typically equal to or greater than standard heterotrophic (aerobic) plate counts. In unsupplemented water samples, CTC counts were typically lower than those obtained with the heterotrophic plate count method. Reduction of CTC by planktonic or biofilm-associated bacteria was suppressed by formaldehyde, presumably because of inhibition of electron transport activity and other metabolic processes. Because of their bright red fluorescence (emission maximum, 602 nm), actively respiring bacteria were readily distinguishable from abiotic particles and other background substances, which typically fluoresced at shorter wavelengths. The use of CTC greatly facilitated microscopic detection and enumeration of metabolically active (i.e., respiring) bacteria in environmental samples.

Bacteria↗
PubMed1996

Inhibition of sulfate respiration by 1,8-dihydroxyanthraquinone and other anthraquinone derivatives.

Derivatives of 9,10-anthracenedione, or anthraquinone, were shown to inhibit respiratory sulfate reduction by pure cultures of sulfate-reducing bacteria, as well as by crude enrichment cultures. Structure-activity studies showed that an increasing degree of substitution of the anthraquinone nucleus resulted in increasing 50% inhibition (I(inf50)) values for sulfate respiration. Addition of charged ring substituents also resulted in an increase in the I(inf50) concentration. Experiments carried out with 1,8-dihydroxyanthraquinone demonstrated inhibition of hydrogen-dependent sulfate respiration but not hydrogen-dependent sulfite or thiosulfate respiration. Addition of pyruvate resulted in stimulation of sulfate-dependent hydrogen oxidation in the presence of the anthraquinone. These observations, together with a direct demonstration of uncoupling in French press vesicle preparations, suggest that the underlying mechanism of inhibition is uncoupling of ATP synthesis from electron transfer reactions. The low I(inf50) values for inhibition (0.5 to 10 (mu)M) and the relatively low general toxicity of anthraquinones suggest that these compounds may be useful for inhibition of sulfide generation in situations which are incompatible with the use of broadly toxic biocides.

Journal Article↗
PubMed2001

Kinetics of perchlorate- and chlorate-respiring bacteria.

Ten chlorate-respiring bacteria were isolated from wastewater and a perchlorate-degrading bioreactor. Eight of the isolates were able to degrade perchlorate, and all isolates used oxygen and chlorate as terminal electron acceptors. The growth kinetics of two perchlorate-degrading isolates, designated "Dechlorosoma" sp. strains KJ and PDX, were examined with acetate as the electron donor in batch tests. The maximum observed aerobic growth rates of KJ and PDX (0.27 and 0.28 h(-1), respectively) were only slightly higher than the anoxic growth rates obtained by these isolates during growth with chlorate (0.26 and 0.21 h(-1), respectively). The maximum observed growth rates of the two non-perchlorate-utilizing isolates (PDA and PDB) were much higher under aerobic conditions (0.64 and 0.41 h(-1), respectively) than under anoxic (chlorate-reducing) conditions (0.18 and 0.21 h(-1), respectively). The maximum growth rates of PDX on perchlorate and chlorate were identical (0.21 h(-1)) and exceeded that of strain KJ on perchlorate (0.14 h(-1)). Growth of one isolate (PDX) was more rapid on acetate than on lactate. There were substantial differences in the half-saturation constants measured for anoxic growth of isolates on acetate with excess perchlorate (470 mg/liter for KJ and 45 mg/liter for PDX). Biomass yields (grams of cells per gram of acetate) for strain KJ were not statistically different in the presence of the electron acceptors oxygen (0.46 +/- 0.07 [n = 7]), chlorate (0.44 +/- 0.05 [n = 7]), and perchlorate (0.50 +/- 0.08 [n = 7]). These studies provide evidence that facultative microorganisms with the capability for perchlorate and chlorate respiration exist, that not all chlorate-respiring microorganisms are capable of anoxic growth on perchlorate, and that isolates have dissimilar growth kinetics using different electron donors and acceptors.

Betaproteobacteria↗
PubMed2003

A new rate law describing microbial respiration.

The rate of microbial respiration can be described by a rate law that gives the respiration rate as the product of a rate constant, biomass concentration, and three terms: one describing the kinetics of the electron-donating reaction, one for the kinetics of the electron-accepting reaction, and a thermodynamic term accounting for the energy available in the microbe's environment. The rate law, derived on the basis of chemiosmotic theory and nonlinear thermodynamics, is unique in that it accounts for both forward and reverse fluxes through the electron transport chain. Our analysis demonstrates how a microbe's respiration rate depends on the thermodynamic driving force, i.e., the net difference between the energy available from the environment and energy conserved as ATP. The rate laws commonly applied in microbiology, such as the Monod equation, are specific simplifications of the general law presented. The new rate law is significant because it affords the possibility of extrapolating in a rigorous manner from laboratory experiment to a broad range of natural conditions, including microbial growth where only limited energy is available. The rate law also provides a new explanation of threshold phenomena, which may reflect a thermodynamic equilibrium where the energy released by electron transfer balances that conserved by ADP phosphorylation.

Arsenates↗
PubMed2004

Respiration strategies utilized by the gill endosymbiont from the host lucinid Codakia orbicularis (Bivalvia: Lucinidae).

The large tropical lucinid clam Codakia orbicularis has a symbiotic relationship with intracellular, sulfide-oxidizing chemoautotrophic bacteria. The respiration strategies utilized by the symbiont were explored using integrative techniques on mechanically purified symbionts and intact clam-symbiont associations along with habitat analysis. Previous work on a related symbiont species found in the host lucinid Lucinoma aequizonata showed that the symbionts obligately used nitrate as an electron acceptor, even under oxygenated conditions. In contrast, the symbionts of C. orbicularis use oxygen as the primary electron acceptor while evidence for nitrate respiration was lacking. Direct measurements obtained by using microelectrodes in purified symbiont suspensions showed that the symbionts consumed oxygen; this intracellular respiration was confirmed by using the redox dye CTC (5-cyano-2,3-ditolyl tetrazolium chloride). In the few intact chemosymbioses tested in previous studies, hydrogen sulfide production was shown to occur when the animal-symbiont association was exposed to anoxia and elemental sulfur stored in the thioautotrophic symbionts was proposed to serve as an electron sink in the absence of oxygen and nitrate. However, this is the first study to show by direct measurements using sulfide microelectrodes in enriched symbiont suspensions that the symbionts are the actual source of sulfide under anoxic conditions.

Anaerobiosis↗
PubMed1969

Automatic assessment of respiration during growth in stirred fermentors.

An apparatus for the continuous and automatic measurement of respiration during growth of micro-organisms in stirred aerated culture is described. The effluent atmosphere from the culture vessels is passed through commercially available oxygen and carbon dioxide gas analyzers, and their electrical output is fed to a multipoint recorder. The apparatus has been used to measure the respiration of Escherichia coli, Pseudomonas aeruginosa, Bacillus thuringiensis, and Methylococcus capsulatus during growth on complex and defined media. In addition, pH values and dissolved oxygen concentrations were measured. Growth of P. thuringiensis in glucose-limited media showed unexpected interruptions in the oxygen consumption curves which resembled diauxic growth; growth of B. thuringiensis in complex media showed similar discontinuities of respiration. These results are explained as the sequential utilization of preferred substrates which, in the case of P. aeruginosa were provided as transient intermediates of glucose.

Bacillus↗