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PubMed2000

A new method to estimate respiration rate of biological material based on the reduction of tetrazolium violet.

The traditional method for measuring the activity of the electron-transport system (ETS) gives an estimate of the potential respiration rate, since it measures the rate under saturated substrate conditions (V(max)). Accumulated literature data indicate that this does not relate closely to the actual respiration rate. The new method described here is based on reduction of tetrazolium violet in a homogenate with a natural level of substrates. The analytical protocol ensures that the spectrophotometric reading after 1 h incubation at 40 degrees C reflects the ambient amount of substrates available. This method is superior to the traditional ETS assay in giving a closer correlation with ambient respiration rate. A number of methodological tests have been performed and recommendations are given to optimize the measurements. Macrozooplankton species from the coastal waters of Sweden, representing different taxonomic and trophic groups, showed a range in respiration/ETS ratio from 1.1 to 2.9, and both inter- and intra-specific variability in this ratio were reduced by 50-70% compared with the traditional ETS assay. Results from other environments and for particulate organic matter indicate a similar general improvement. The new analytical assay is simple, cheap and well suited for fieldwork.

Journal Article↗
PubMed2001

Seawater-atmosphere O(2) exchange rates in open-top laboratory microcosms: application for continuous estimates of planktonic primary production and respiration.

Seawater-atmosphere O(2) exchange rates were experimentally measured in open-top laboratory microcosms. The objective was to establish the relationships between turbulence and oxygen transfer velocity, and thus correct continuously measured day-night changes in dissolved oxygen as estimates of planktonic primary production and respiration. After saturating 15-l sterile seawater microcosms with an oxygen-poor gas mix (4.9% O(2), 95.1% N(2)), the microcosms were left to equilibrate with the atmosphere under different turbulence conditions. The rate of increase in dissolved O(2) was measured at 15-min intervals with polarographic-pulsed electrodes and the corresponding values of the oxygen transfer velocity (the K(O(2)) constant for the different turbulence conditions) were determined. After pooling these and literature data obtained in similar experimental conditions, the relation between epsilon (turbulent kinetic energy dissipation rates) and K(O(2)) was determined. Theoretical K(O(2)) values were also calculated using semi-empirical models in which oxygen transfer velocity (K(O(2))) is related to wind velocity. Theoretical, wind related K(O(2)) values were significantly higher than the experimental ones, and as a consequence overestimate primary production and underestimate respiration rates, even resulting in nocturnal O(2) increase. The magnitude of the differences between experimentally derived and theoretically calculated oxygen transfer velocity, precludes the use of wind-derived equations to calculate K(O(2)) in meso- and microcosms experiments not affected by wind, while the equation obtained relating experimental epsilon and K(O(2)) provides statistically reliable estimations of primary production and respiration.

Journal Article↗
PubMed2001

Cost of selective feeding by the blue mussel (Mytilus trossulus) as measured by respiration and ammonia excretion rates.

The metabolic cost as measured by respiration and ammonia excretion rates associated with a selective as compared to a non-selective feeding behaviour was determined for the blue mussel, Mytilus trossulus. Mussels were challenged with four environmentally relevant seston matrices of different quality and quantity, which were known to evoke either a sorting response (i.e., selective feeding) where organic-rich particles were selected over inorganic particles as compared to no sorting (i.e., non-selective) where either inorganic or organic particles were ingested by the bivalve. Seston matrices were prepared by mixing known quantities of silt and algae such that the following extent of feeding responses would occur; no pre-sorting of ingested material, (1) no algae+50 mg silt l(-1), (2) 150x10(6) cells l(-1) of algae+no silt, and, where pre-sorting of ingested material occurred, (3) 20x10(6) cells l(-1) of algae and 20 mg l(-1) of silt, and (4) 150x10(6) cells l(-1) of algae and 50 mg l (1) of silt. A control, which represented basal metabolism consisting of mussels exposed only to filtered seawater (0.45 &mgr;m), was included for a total of five treatments. Mussel respiration and ammonia excretion rates were independent of whether mussels were pre-sorting or not sorting ingested material. Of the four matrices, only rates determined for conditions of maximum seston quality and quantity where pre-sorting of the seston occurred were significantly different from control mussels (p<0.05, ANOVA). Estimates of net energy used for feeding, where net energy is total energy intake (food) minus energy expenditure (energy lost through respiration and excreta as measured by ammonia excretion rates), indicated that feeding, whether selective or non-selective required only 0.92% of net energy intake. Hence, mussels appear to be highly adapted to a dynamic food environment with negligible costs associated with the feeding process, even when significant pre-selection of organic-rich particles occurs.

Journal Article↗
PubMed2001

Active regulation of respiration and circulation in pupae of the codling moth (Cydia pomonella).

Regulation of autonomic physiological functions has been investigated by means of multisensor electronic methods, including electrocardiographic recording of heartbeat, strain-gauge recording of extracardiac hemocoelic pulsations (EHPs), anemometric recording of air passage through spiracles and respirographic recording of O(2) consumption and CO(2) output. Pupae of Cydia exhibit continuous respiration without remarkable bursts of CO(2). The dorsal vessel of these pupae exhibited regular heartbeat reversals characterized by shorter intervals of faster (forward oriented or anterograde) pulsations and longer intervals of slower (backward oriented or retrograde) peristaltic waves. The periodically repeated EHPs were present during the whole pupal interecdysial period. The internal physiological mechanisms regulating the cardiac (heartbeat) and extracardiac (EHP) pulsations were completely independent for most of the pupal instar. Simultaneous multisensor analysis revealed that the anterograde heartbeat of the dorsal vessel had similar but not identical frequency with EHPs. During advanced pharate adult development, frequency of cardiac and extracardiac pulsation periods profoundly increased until almost uninterrupted pulsation activity towards adult eclosion. At this time, the cardiac and extracardiac pulsations occasionally performed in concert, which enhanced considerably the efficacy of hemolymph circulation in pharate adults with high metabolic rates. The fastest hemolymph flow through the main body cavity was always associated with EHPs and with anterograde heartbeat. Simple physical diffusion of O(2) and CO(2) through spiracles (diffusion theory of insect respiration) does not play a significant role in pupal respiration. Instead, several kinds of regulated, mechanical ventilations of the tracheal system, including EHPs are responsible for effective tracheal ventilation.

Journal Article↗
PubMed1995

Control of cellular respiration in vivo by mitochondrial outer membrane and by creatine kinase. A new speculative hypothesis: possible involvement of mitochondrial-cytoskeleton interactions.

The current problems of regulation of myocardial energy metabolism and oxidative phosphorylation in vivo are considered. With this purpose, retarded diffusion of ADP in cardiomyocytes was studied by analysis of elevated apparent Km for this substrate in regulation of respiration of saponin-skinned cardiac fibers, as compared to isolated mitochondria. Recently published data showing the importance of the outer mitochondrial membrane were compared with new experimental results on the proteolysis of skinned fibers and tissue homogenates. In both cases 10 min incubation and 0.125 mg/ml of trypsin resulted in a decrease of apparent Km for ADP from 297 +/- 35 and 228 +/- 16 to 109 +/- 2 and 36 +/- 16, respectively. Thus, the permeability of the outer mitochondrial membrane for ADP may be controlled by some unknown cytoplasmic protein(s), probably related to the cytoskeleton, which are separated from mitochondria during their isolation. The extent of expression of this protein(s) depends on the energy state and type of muscle. Activation of mitochondrial creatine kinase reaction coupled to oxidative phosphorylation overcomes the diffusion difficulties of ADP by amplifying the stimulatory effect of ADP on respiration. It is concluded that both cytoplasmic and mitochondrial creatine kinases, adenylate kinase and cytoplasmic factor controlling outer membrane permeability may participate in metabolic feedback regulation of respiration in muscle cells.

Adenosine Diphosphate↗
PubMed2003

Assessing the microbial activity of soil samples, its nutrient limitation and toxic effects of contaminants using a simple respiration test.

Eight soil samples from five wells of a former gas plant site differing in the contamination with BTEX and PAHs as well as the nutrient content were investigated by soil respiration measurements. The basal, glucose as well as NH4+ and PO4(3-) induced cumulative oxygen consumption and carbon dioxide production in 72 and 120 h were determined and additionally the maximal turnover rates and the limitation quotients were calculated. Without additional carbon source only one of five investigated samples was clearly nutrient limited. After glucose supplementation four of seven investigated samples showed nutrient limitation that was in accordance with the available ammonium and phosphorous content. BTEX and PAHs did not exhibit an inhibiting effect on the respiration rate. In contrast, BTEX containing samples exhibited the highest oxygen consumption indicating biodegradation of the contaminants. The results show that oxygen consumption and carbon dioxide production as well as the kinetic of these processes are all informative parameters characterizing the whole microbial respiration potential and their nutrient limitation in soil samples. Therefore this fast respirometric method can be used for the decision if further detailed studies of the bioremediation are useful and if nutrient supplementation is recommended to enhance natural attenuation.

Bacteria↗
PubMed2005

Microbial dimethylsulfoxide and trimethylamine-N-oxide respiration.

Over the last two decades, the biochemistry and genetics of dimethylsulfoxide (DMSO) and trimethylamine-N-oxide (TMAO) respiration has been characterised, particularly in Escherichia coli marine bacteria of the genus Shewanella and the purple phototrophic bacteria, Rhodobacter sphaeroides and R. capsulatus. All of the enzymes (or catalytic subunits) involved the final step in DMSO and TMAO respiration contain a pterin molybdenum cofactor and are members of the DMSO reductase family of molybdoenzymes. In E. coli, the dimethylsulfoxide reductase (DmsABC) can be purified from membranes as a complex, which exhibits quinol-DMSO oxidoreductase activity. The enzyme is anchored to the membrane via the DmsC subunit and its catalytic subunit DmsA is now considered to face the periplasm. Electron transfer to DmsA involves the DmsB subunit, which is a polyferredoxin related to subunits found in other molybdoenzymes such as nitrate reductase and formate dehydrogenase. A characteristic of the DmsAB-type DMSO reductase is its ability to reduce a variety of S- and N-oxides. E. coli contains a trimethylamine-N-oxide reductase (TorA) that is highly specific for N-oxides. This enzyme is located in the periplasm and is connected to the quinone pool via a membrane-bound penta-haem cytochrome (TorC). DorCA in purple phototrophic bacteria of the genus Rhodobacter is very similar to TorCA with the critical difference that DorA catalyses reduction of both DMSO and TMAO. It is known as a DMSO reductase because the S-oxide is the best substrate. Crystal structures of DorA and TorA have revealed critical differences at the Mo active site that may explain the differences between substrate specificity between the two enzymes. DmsA, TorA and DorA possess a "twin arginine" N-terminal signal sequence consistent with their secretion via the TAT secretory system and not the Sec system. The enzymes are secreted with their bound prosthetic groups: this take place in the cytoplasm and the biogenesis involves a chaperone protein, which is cognate for each enzyme. Expression of the DMSO and TMAO respiratory operons is induced in response to a fall in oxygen tension. dmsABC expression is positively controlled by the oxygen-responsive transcription factor, Fnr and ModE, a transcription factor that binds molybdate. In contrast, torCAD expression is not under Fnr- or ModE-control but is dependent upon a sensor histidine kinase-response regulator pair, TorSR, which activate gene expression under conditions of low oxygen tension in the presence of N- or S-oxide. Regulation of dorCDA expression is similar to that seen for torCAD but it appears that the expression of the sensor histidine kinase-response regulator pair, DorSR is regulated by Fnr and there is an additional tier of regulation involving the ModE-homologue MopB, molybdate and the transcription factor DorX. Analysis of microbial genomes has revealed the presence of dms and tor operons in a wide variety of bacteria and in some archaea and duplicate dms and tor operons have been identified in E. coli. Challenges ahead will include the determination of the significance of the presence of the dms operon in bacterial pathogens and the determination of the significance of DMSO respiration in the global turnover of marine organo-sulfur compounds.

Dimethyl Sulfoxide↗
PubMed2000

Effects of mild night chilling on respiration of expanding cotton leaves.

Utilizing expanding leaves of cotton (Gossypium hirsutum L. cv. Coker 312), the hypothesis that suboptimal night temperatures above those for putative phase transitions of mitochondrial lipids caused greater substrate control of night respiration and increased the control that respiration exerted on ATP-dependent metabolism was tested. Night respiratory CO(2) evolution rates for 5-7-day-old leaves growing at 30/19 degrees (day/night) nearly equaled those of leaves exposed to 28 degrees C nights, while leaves exposed to 15 degrees C nights had rates that were 42% of those at 28 degrees C. No restriction of respiration by carbohydrate supply was detected for leaves grown at either cool night temperature or when warm-grown plants were transferred to cool night conditions. Pyruvate utilization was more sensitive to mild chilling than glycolysis. Growth at 30/19 or 30/15 degrees C resulted in higher nocturnal ATP:ADP and energy charge for expanding leaves than growth at 30/28 degrees C, suggesting a lessening of respiratory control of ATP-dependent metabolism with long-term night chilling. However, cool night exposure resulted in reductions in total phosphorylated adenylates, and the low ATP content, most notably occurring during 15 degrees C nights, may have restricted some metabolic activity. The cause of these low ATP levels and their possible effects on cotton metabolism during chilling remain to be elucidated.

Journal Article↗
PubMed2003

Use of O2 consumption and CO2 production in kinetic cells to delineate pyrite oxidation-carbonate buffering and microbial respiration in unsaturated media.

Identifying zones of sulphide oxidation and carbonate buffering is important in the development of a management plan for mine waste-rock piles. In this study, we used a kinetic cell technique to measure rates of O2 consumption and CO2 production in low sulphide (<0.12 wt.% S), low inorganic carbon (<0.20 wt.% C(inorganic)), gneissic waste rock and associated organic-rich lake sediment (0.7 wt.% C(organic)), and forest soil (1.4 wt.% C(organic)) collected from the Key Lake uranium mine in Saskatchewan, Canada. Solid chemistry, stable carbon isotope, pore water sulphate concentration data, and stoichiometric considerations indicated that O2 consumption and CO2 production were constrained by microbial respiration in the lake sediment and forest soil and by pyrite oxidation-carbonate buffering in the gneissic waste rock. Mean ratios of molar CO2 production to O2 consumption rates were 0.5 for lake sediment, 0.7 for forest soil, and 0.2 for gneissic waste rock. The different O2/CO2 ratios suggested that O2-CO2 monitoring may provide a practical tool for identifying the zones of microbial respiration and pyrite oxidation-carbonate buffering in mine waste-rock piles. Rates of O2 consumption and CO2 production were about one order of magnitude greater in lake sediment than in gneissic waste rock, indicating that microbial respiration would exert a control on the distribution of O2 and CO2 gas in waste-rock piles constructed upon the dewatered lake sediments.

Carbon Dioxide↗
PubMed1998

Changes in heart rate and respiration rate in patients with vestibular dysfunction following head movements which provoke dizziness.

Patients with vestibular dysfunction often complain of additional symptoms typical of panic disorder and/or hyperventilation. This study investigated whether autonomic and respiratory symptoms reported by patients with vestibular disorders were associated with objective changes in heart and respiration rate following head movements provoking dizziness. Subjective ratings of symptoms and anxiety and objective measures of heart and respiration rate were obtained from 29 patients and 16 healthy controls immediately before and after the subjects performed three standardised sets of vigorous head movements. Within-group analyses revealed greater increases in respiration rate following head movement among patients who complained of more somatic symptoms, both during the previous 2 months and following head movement.

Adult↗
PubMed2000

Effects of temperature on the respiration rates and the kinetics of citrate synthase in two species of Idotea (Isopoda, Crustacea).

The two species of isopods, Idotea baltica (Pallas) and Idotea emarginata (Fabricius), co-occur frequently near Helgoland, North Sea, occupying different ecological niches. Respiration rates and kinetic properties of citrate synthase (CS) were compared in these species in order to identify possible mechanisms of temperature adaptation. Specimens were acclimated to 5 and 15 degrees C prior to further investigations. Respiration rates were measured under normoxic conditions at 5, 10 and 15 degrees C. CS was partly purified chromatographically and influences of temperature, pH, substrate saturation and ATP-concentration on enzyme activity were examined. In both species, rising temperatures led to linearly increasing oxygen consumption, with estimated Q10 values between 3.2 and 4.2. Only I. baltica showed an effect of short term acclimation: warm adapted animals had always higher respiration rates than cold adapted ones. In I. emarginata, the acclimation temperature had no effect on oxygen consumption. Furthermore, its CS slightly indicates higher affinity to oxaloacetic acid when specimens were adapted to 15 degrees C compared to those maintained at 5 degrees C. Any effect of the experimental temperature on CS in I. baltica was negligible. The results are discussed in view of the different habitats occupied by the species compared.

Animals↗
PubMed1999

Effects of inorganic mercury on the respiration and the swimming activity of shrimp larvae, Pandalus borealis.

In order to test the sensitivity of respiration (physiological and potential) to mercury (Hg) contamination, larval shrimp Pandalus borealis were exposed to inorganic Hg (0-160 ppb) for 27 h in the laboratory. Oxygen consumption rates (RO2), potential respiration (determined by respiratory electron transfer system activity, ETSA), protein content, and swimming activity for zoeae III and zoeae V stages were measured. For both zoeae stages, ETSA and protein content remained constant after 27 h exposure to 160 ppb Hg whereas RO2 and swimming activity decreased. This study revealed the impact of different Hg levels and different exposure times on RO2 of shrimp larvae. After 10 h exposure to 160 ppb Hg, the RO2 decreased by 43 and 49% in zoeae III and zoeae V stages, respectively. Exposure time of 27 h to 80 ppb Hg and higher, induced paralysis in nearly 100% larvae. Surprisingly, the paralysed larvae displayed almost 50% of the control's RO2. The results showed that Hg disturbs a part of the respiration process without modifying the maximum activity of the enzymes involved in the ETSA assay. Therefore, the ETSA assay can not be used as a sublethal bioanalytic probe to detect Hg in short-term exposures. The decline of the RO2/ETSA ratios reported here, indicates an inability of contaminated larvae to adapt their metabolism to physiological stress caused by Hg.

Animals↗
PubMed2006

A modeling study and implications of competition between Dehalococcoides ethenogenes and other tetrachloroethene-respiring bacteria.

Bioaugmentation with cultures containing Dehalococcoides strains that dechlorinate cis-1,2-dichloroethene (cDCE) to ethene is often recommended at sites where indigenous populations dechlorinate tetrachloroethene (PCE) to cDCE. In these cases, Dehalococcoides populations may have to compete with other dehalorespirers for chlorinated ethenes and/or electron donors. A continuous-flow stirred tank reactor model was used to describe the substrate interactions in three conceptual models of competition between PCE-respiring populations under natural attenuation and engineered bioremediation scenarios. Model simulations were used to evaluate the effects of other chlorinated ethene respirers on substrate utilization by, and growth of, a Dehalococcoides strain (Dhc. ethenogenes strain 195) and identify the key factors influencing the outcome of competition among different dehalorespirers. The results suggest that, under natural attenuation conditions, Dhc. ethenogenes is unlikely to be the dominant population if a dehalorespirer that can compete for limiting amounts of reducing equivalents is present. Engineered bioremediation conditions resulted in greater enrichment of Dhc. ethenogenes than of competing dehalorespirers. Under several conditions, Dhc. ethenogenes coexisted with a PCE-to-cDCE (or PCE-to-TCE) dehalorespirer, primarily by functioning as a cDCE- (or TCE)-to-ethene dechlorinating specialist. From a bioremediation standpoint, maintenance of multiple dehalorespiring specialists appears ideal because it may result in the fastest and most extensive chlorinated ethene transformations. Thus, to improve our ability to successfully implement bioremediation, it may be helpful to characterize the indigenous PCE-to-cDCE respiring populations and the nature and distribution of electron donors used by these dehalorespirers at contaminated sites. Further understanding of these interactions requires more accurate information on the kinetics of known dehalorespiring populations.

Chloroflexi↗
PubMed2002

Diazoxide and pinacidil uncouple pyruvate-malate-induced mitochondrial respiration.

We investigated the effects of K(ATP) channel openers diazoxide and pinacidil on the respiration rate and membrane potential (deltapsi) of rat heart mitochondria, oxidizing pyruvate and malate. Diazoxide and pinacidil (58.8-1348.3 microM) increased the V2 (-ADP) respiration rate accordingly by 13-208% and 30-273% and decreased the deltapsi by 2-17% and 6-55%. These effects were also similar in the respiration medium without K+. Moreover, carboxyatractyloside completely abolished diazoxide- and pinacidil-induced uncoupling, indicating a role for the mitochondrial adenine nucleotide translocase in this process.

Animals↗
PubMed1998

Relationship of the Escherichia coli TrkA system of potassium ion uptake with the F0F1-ATPase under growth conditions without anaerobic or aerobic respiration.

K+ uptake by the Escherichia coli TrkA system is unusual in that it requires both ATP and deltamuH+; a relation with H+ circulation through the membrane is therefore suggested. The relationship of this system with the F0F1-ATPase was studied in intact cells grown under different conditions. A significant increase of the N,N'-dicyclohexylcarbodiimide(DCCD)-inhibited H+ efflux through the F0F1 by 5 mM K+, but not by Na+ added into the potassium-free medium was revealed only in fermenting wild-type or parent cells, that were grown under anaerobic conditions without anaerobic or aerobic respiration and with the production of H2. Such an increase disappeared in the deltaunc or the trkA mutants that have altered F0F1 or defective TrkA, respectively. This finding indicates a closed relationship between TrkA and F0F1, with these transport systems being associated in a single mechanism that functions as an ATP-driven H(+)-K(+)-exchanging pump. A DCCD-inhibited H(+)-L(+)-exchange through these systems with the fixed stoichiometry of H+ and K+ fluxes (2H+/K+) and a higher K+ gradient between the cytoplasm and the external medium were also found in these bacteria. They were not observed in cells cultured under anaerobic conditions in the presence of nitrate or under aerobic conditions with respiration and without production of H2. The role of anaerobic or aerobic respiration as a determinant of the relationship of the TrkA with the F0F1 is postulated. Moreover, an increase of DCCD-inhibited H+ efflux by added K+, as well as the characteristics of DCCD-sensitive H(+)-K(+)-exchange found in a parent strain, were lost in the arcA mutant with a defective Arc system, suggesting a repression of enzymes in respiratory pathways. In addition, K+ influx in the latest mutant was not markedly changed by valinomycin or with temperature. The arcA gene product or the Arc system is proposed to be implicated in the regulation of the relationship between TrkA and F0F1.

Aerobiosis↗
PubMed2002

Origins and diversification of sulfate-respiring microorganisms.

If the diversification of microbial life can be depicted as a single tree, as inferred by comparative sequencing of ribosomal RNAs, this could provide a framework for defining the order of emergence of new metabolic pathways. However, recent recognition that lateral gene transfer has been a significant force in microbial evolution has created uncertainty about the interpretation of taxonomies based on gene sequences. In this context, the origins and evolution of sulfate respiration will be evaluated considering the evolutionary history of a central enzyme in this process, the dissimilatory sulfite reductase. These studies suggest at least two major lateral transfer events during the early diversification of sulfate respiring microorganisms. The high sequence conservation of this enzyme has also provided a mechanism to directly explore the natural diversity of sulfate-respiring organisms using molecular techniques, avoiding the bias of culture-based identification. These studies suggest that the habitat range and evolutionary diversity of this key functional group of organisms is greater than now appreciated.

Evolution, Molecular↗
PubMed1997

Energy balance in a respiration chamber: individual adjustment of energy intake to energy expenditure.

OBJECTIVES: In studies on substrate utilization, a state of energy balance is often required. Energy requirements are based on measured or calculated sleeping metabolic rate (SMR) or basal metabolic rate (BMR). A study was performed to compare this protocol with adjustment of energy intake (EI) to 24 h energy expenditure (24 h EE). DESIGN: In part one, eight subjects spent one night and the subsequent three days in a respiration chamber. On day 1 EI was set at 1.5*SMR. On day 2 and 3 EI was set at 24 h EE of day 1. In part two of the study, an activity protocol was provided while staying in the chamber. 12 subjects spent one night and the subsequent two days in the respiration chamber. On day 1 EI was set at 1.55*SMR and on day 2 EI was set at 24 h EE of day 1. MEASUREMENTS: Sleeping metabolic rate, diet induced thermogenesis, physical activity index and 24 h expenditure were measured using a respiration chamber. SUBJECTS: Eight healthy normal-weight females (age: 22 +/- 3, BMI: 20.9 +/- 1.8) in part one and twelve healthy normal-weight males and females (age: 26 +/- 2, BMI: 21.4 +/- 0.5) in part two of the study. RESULTS: Physical activity index (PAI = 24 h EE/SMR) on day 1 (part 1) was 1.55 +/- 0.04, close to the predicted value of 1.5, but between-subject variation was large (range: 1.39-1.68). Absolute deviation from energy balance reduced significantly from 1.35 +/- 0.30 MJ/d on day 1 to 0.51 +/- 0.21 and 0.31 +/- 0.10 MJ/d on day 2 and 3 respectively (P < 0.05). The latter can be considered as near to energy balance. With the activity protocol (part 2) absolute deviation from energy balance reduced significantly from 0.93 +/- 0.20 MJ/d on day 1 to 0.27 +/- 0.11 MJ/d on day 2 (P < 0.05). CONCLUSION: A three day stay in the chamber allows adjustment of energy intake to energy expenditure, in this way achieving a state close to energy balance. When prescribing an activity protocol the same results can be obtained within two days.

Adaptation, Physiological↗
PubMed2001

Variations in the estimation of the contribution of environmental tobacco smoke (ETS) to respirable (< or = 5 microns) indoor air particulates obtained by the use of different analytical methods.

Several methods are in use for the identification of the contribution of particulate associated environmental tobacco smoke (ETS) and sidestream smoke to an atmosphere. These include the measurement of respirable suspended particulates (RSP), measurements of the total UV absorption and total fluorescence emission of a methanol extract of collected particulates and the use of specific marker compounds such as solanesol and scopoletin. Use of these methods gave values for the contribution of particulate ETS to total respirable (< or = 5 microns) particulates in the ranges 8.3-124.7% for smokers' houses and 9.6-121.2% for smokers' offices, respectively. However, using what we consider to be the most reliable methodology, based on the measurement of solanesol, the average contribution of particulate ETS to total respirable (< or = 5 microns) particulates for smokers' houses was 21.7% and for smokers' offices was 23.3%.

Absorption↗