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PubMed1976

Servo respirator constructed from a positive-pressure ventilator.

We have constructed an electronically controlled respirator from three commercially available components: a positive-pressure ventilator, a recorder pen motor, and a differential amplifier. Using negative feedback derived from a tracheal pressure signal, the instrument functions as a servo respirator which provides precise control of tracheal pressure. The system's power and response characteristics are well suited for ventilation of anesthetized cats and dogs. The servo respirator can be used as an externally controlled respiratory pump which provides flexibility in selection of the parameters of the ventilatory cycle. Alternatively, it can function as a "demand" respirator which generates transthoracic pressure proportional to efferent respiratory discharge.

Electronics↗
PubMed1991

Synaptosomal respiration: a potent indicator of veratridine-induced Na influx.

Inhibition of the voltage-dependent Na channel by tetrodotoxin (5 mumol/l) decreased by about 86% the stimulation of the respiration of rat brain synaptosomes induced by veratridine (10 mumol/l). A similar effect was achieved by blocking Na(+)-K(+)-ATPase with ouabain (1 mmol/l). Pharmacological manipulations of Ca homeostasis suggested that the veratridine-induced stimulation of respiration did not depend upon Ca entry. These data suggest that the veratridine-induced stimulation of synaptosomal respiration may result primarily from an increase in intracellular Na+. They provide the basis for an indirect method, which only requires recording of synaptosomal respiration, to test drugs for their possible interaction with excessive Na influxes.

Amiloride↗
PubMed1975

Comparison and significance of respiration and glycolysis of prostatic tissue from various species.

The respiration and glycolysis of prostatic tissue from baboons, rhesus monkeys, dogs and rats were compared to the respiration and glycolysis in human prostatic tissue. All the primate prostates had a high glycolytic ability and a low respiration in contrast to the rat and dog prostate. Treatment of baboons with drugs clinically effective against prostatic cancer did not change the prostatic metabolism despite a marked prostatic atrophy. In vitro the drugs reduced respiration markedly. The metabolic similarity between the human and the baboon and rhesus monkey prostate indicates that nonhuman primates should be investigated in the evaluation of chemotherapeutic agents for treatment of prostatic cancer.

Animals↗
PubMedDate not supplied

Evaluation of a quantitative fit testing method for N95 filtering facepiece respirators.

A method for performing quantitative fit tests (QNFT) with N95 filtering facepiece respirators was developed by earlier investigators. The method employs a simple clamping device to allow the penetration of submicron aerosols through N95 filter media to be measured. The measured value is subtracted from total penetration, with the assumption that the remaining penetration represents faceseal leakage. The developers have used the clamp to assess respirator performance. This study evaluated the clamp's ability to measure filter penetration and determine fit factors. In Phase 1, subjects were quantitatively fit-tested with elastomeric half-facepiece respirators using both generated and ambient aerosols. QNFT were done with each aerosol with both P100 and N95 filters without disturbing the facepiece. In Phase 2 of the study elastomeric half facepieces were sealed to subjects' faces to eliminate faceseal leakage. Ambient aerosol QNFT were performed with P100 and N95 filters without disturbing the facepiece. In both phases the clamp was used to measure N95 filter penetration, which was then subtracted from total penetration for the N95 QNFT. It was hypothesized that N95 fit factors corrected for filter penetration would equal the P100 fit factors. Mean corrected N95 fit factors were significantly different from the P100 fit factors in each phase of the study. In addition, there was essentially no correlation between corrected N95 fit factors and P100 fit factors. It was concluded that the clamp method should not be used to fit-test N95 filtering facepieces or otherwise assess respirator performance.

Adult↗
PubMed2004

Respiration rate of hepatocytes varies with body mass in birds.

Hepatocytes were isolated from eight species of birds ranging from 13 g zebra finches to 35 kg emus. This represents a 2800-fold range of body mass (Mb). Liver mass (g) was allometrically related to species body mass by the equation: liver mass=19.6 x Mb(0.91). There was a significant allometric decline in hepatocyte respiration rate (HRR; nmol O2 mg(-1) dry mass min(-1)) with species body mass (kg) described by the relationship: HRR=5.27 x Mb(-0.10). The proportions of hepatocyte oxygen consumption devoted to (i) mitochondrial ATP production, (ii) mitochondrial proton leak and (iii) non-mitochondrial processes were estimated by using excess amounts of appropriate inhibitors. It was found that although hepatocyte respiration rate varied with body mass in birds, these processes constitute a relatively constant proportion of hepatocyte metabolic rate irrespective of the size of the bird species. The respective percentages were 54%, 21% and 25%. The portion of hepatocyte respiration devoted to ATP production for use by the sodium pump was estimated and found to be a relatively constant 24% of hepatocyte respiration and 45% of mitochondrial ATP production in different-sized bird species. These results are discussed in the context of competing theories to explain the metabolism-body size allometry, and are found to support the 'allometric cascade' model.

Adenosine Triphosphate↗
PubMed2004

Assessing soil respiration by means of near-infrared diode laser spectroscopy.

High-resolution diode laser spectroscopy in the near-infrared region is applied to the accurate measurement of soil respiration. In particular, the use of a diode-laser-based spectrometer has allowed the implementation, for the first time, of a static accumulation method capable of measuring soil respiration from continuous measurements of CO(2) concentrations, with minor perturbation on soil respiration as well as on CO(2) transport and emission. The system has been tested in a laboratory experiment by detection of CO(2) production from sandy matrices, inoculated with active soil microbes and supplied with different amounts of decomposable plant material. Respiration rates of all samples were then retrieved using a diffusion model. The results of the laboratory tests are in agreement with those expected on the basis of sample composition. Examples of operation with real soil samples are also reported. We discuss the possible field application of the system, in conjunction with closed static soil chambers.

Carbon Dioxide↗
PubMed2000

Positive human health effects of wearing a respirator in a swine barn.

STUDY OBJECTIVES: A study was conducted to evaluate the acute health effects of wearing an N-95 disposable respirator in a swine confinement facility. DESIGN: A crossover trial design was used in the study. SETTING: The study was carried out at the research facilities of the Centre for Agricultural Medicine, the Royal University Hospital, and the Prairie Swine Centre Inc, Saskatoon, Saskatchewan, Canada. PARTICIPANTS: Twenty-one nonsmoking healthy male subjects with no previous swine barn exposure participated in the study. INTERVENTIONS: The subjects participated in a laboratory session (baseline day), a 4-h exposure in a traditional swine room wearing the respirator (intervention day), and a 4-hour exposure in a traditional swine room without a respirator (nonintervention day). MEASUREMENTS: Lung function, methacholine challenge tests, blood counts, nasal lavage, and cytokines in serum and nasal lavage fluid. RESULTS: Mean (+/- SE) shift change in FEV(1), from preexposure to postexposure, was highest on nonintervention day (-8.1+/-1.01%) and was significantly different from intervention day (0.32+/-0.62%; p<0.0001) and baseline day (1.57+/-0.51%; p<0.0001). Similar patterns were observed in the mean values of the provocative concentration of a substance (methacholine) causing a 20% fall in FEV(1) (nonintervention day, 130.4+/-36.9 mg/mL; intervention day, 242.0+/-38.0 mg/mL; and baseline day, 328.0 mg/mL +/-34.1 mg/mL). Significant increases in serum neutrophil levels and nasal cell counts were observed on the nonintervention day in comparison to the baseline and intervention days. Significant increases also were found in the levels of cytokines interleukin (IL)-6 and IL-8 in nasal lavage fluid and in the levels of IL-6 in serum for the nonintervention day in comparison to the other 2 days. CONCLUSIONS: The results demonstrate that an N-95 disposable respirator can help to significantly reduce acute negative health effects in subjects not previously exposed to a swine barn environment.

Adolescent↗
PubMed2004

Symptoms, respirator use, and pulmonary function changes among New York City firefighters responding to the World Trade Center disaster.

CONTEXT: New York City firefighters responding to the World Trade Center (WTC) disaster on September 11, 2001, were exposed to numerous hazards. A medical screening program was conducted 3 weeks after the disaster on a sample of firefighters. OBJECTIVES: To determine whether arrival time at the WTC and other exposure variables (including respirator use) were associated with symptoms and changes in pulmonary function (after exposure - before exposure). DESIGN: A cross-sectional comparison of firefighters representing the following groups: (1) firefighters who arrived before/during the WTC collapse, (2) firefighters who arrived 1 to 2 days after the collapse, (3) firefighters who arrived 3 to 7 days after the collapse, and (4) unexposed firefighters. SETTING: Fire Department of New York City (FDNY) Bureau of Health Services on October 1 to 5, 2001. POPULATION: A stratified random sample of 362 of 398 recruited working firefighters (91%). Of these, 149 firefighters (41%) were present at the WTC collapse, 142 firefighters (39%) arrived after the collapse but within 48 h, 28 firefighters (8%) arrived 3 to 7 days after the collapse, and 43 firefighters (12%) were unexposed. MAIN OUTCOME MEASURES: New/worsening symptoms involving the eyes, skin, respiratory system, and nose and throat (NT), and changes in spirometry from before to after exposure. RESULTS: During the first 2 weeks at the WTC site, 19% of study firefighters reported not using a respirator; 50% reported using a respirator but only rarely. Prevalence ratios (PRs) for skin, eye, respiratory, and NT symptoms showed a dose-response pattern between exposure groups based on time of arrival at the WTC site, with PRs between 2.6 and 11.4 with 95% confidence intervals (CIs) excluding 1.0 for all but skin symptoms. For those spending > 7 days at the site, the PR for respiratory symptoms was 1.32 (95% CI, 1.13 to 1.55), compared with those who were exposed for < 7 days. Mean spirometry results before and after exposure were within normal limits. The change in spirometry findings (after exposure - before exposure) showed near-equal reductions for FVC and FEV(1). These reductions were greater than the annual reductions measured in a referent population of incumbent FDNY firefighters prior to September 11 (p or= 450 mL in FEV(1) in those arriving during the first 48 h compared to the referent (p <or= 0.05). CONCLUSIONS: The symptoms and pulmonary function changes following exposure at the WTC demonstrate the need for improvements in respirators and their use, as well as long-term medical monitoring of rescue workers.

Adult↗
PubMedDate not supplied

Comparative effects of scopoletin and aflatoxin B1 on bovine hepatic mitochondrial respiration in vitro.

A comparative study of the in vitro effects of the coumarin compounds, scopoletin and aflatoxin B1 (AFB1), on bovine (Bos indicus) hepatic mitochondrial respiration was carried out polarographically, using isocitrate -NAD+ (3 - site), succinate (2 - site), and reduced cytochrome c (1 - site), as respiratory substrates. Both scopoletin and AFB1 elicited a substrate--dependent stimulation or inhibition of the mitochondrial states 4 and 3 respiration. The results suggest that AFB1 has a higher tendency to inhibit the mitochondrial respiration than scopoletin, while scopoletin showed higher uncoupling effects than AFB1. The effects of scopoletin and AFB1 on mitochondria were more pronounced on the electron transport than on phosphorylation reaction. The extent (3-35%) of AFB1 induced inhibition of bovine mitochondrial respiration observed in this study, was appreciably lower than the values indicated in other animal species (rats and guinea fowls) reported in previous studies using equivalent concentrations of the toxin. These results were discussed in terms of the susceptibility of the animal species to the toxic effects of scopoletin and AFB1.

Aflatoxin B1↗
PubMed1992

Studies on the rapid stimulation of mitochondrial respiration by thyroid hormones.

Injection of L-3,5-diiodothyronine (T2) into rats made hypothyroid by 6-n-propyl-2-thiouracil (PTU) increased the respiration rates of subsequently isolated liver mitochondria; this stimulation of respiration by T2 occurred in the presence of cycloheximide and is therefore independent of protein synthesis on cytoplasmic ribosomes. Injection of T3 into PTU-treated rats had a lesser effect than T2 on the respiration rates of subsequently isolated mitochondria; as PTU is an inhibitor of 5'-iodothyronine deiodinases, which convert T3 into T2 in vivo, the rapid stimulation of mitochondrial respiration by T3, which has been shown in a range of systems, may not be due directly to T3 itself, but may be mediated by its deiodination product T2. Injection of T2, or T3, into hypothyroid or euthyroid rats had no effect on the percentage activity of mitochondrial pyruvate hydrogenase assayed 30 min later. The amount of active pyruvate dehydrogenase is regulated by changes in mitochondrial calcium concentration and matrix ATP/ADP ratio; therefore these parameters are not persistently affected by treatment with T3 or T2. In addition, the total amount of pyruvate dehydrogenase present was the same in euthyroid and hypothyroid rats, indicating that the expression of this enzyme is not stringently controlled by thyroid hormone status.

Adenosine Diphosphate↗
PubMed2006

Automatic detection of exogenous respiration end-point using artificial neural network.

When aerobic bacteria receive a biodegradable material such as wastewater, then respiration changes from endogenous to exogenous. The reverse occurs when biodegradation is complete. When using respirometry a respirogram is recorded showing those changes in respiration, and for an expert it is not difficult to point the moments at which they occur. The area corresponding to the exogenous respiration phase is a measure of the easily biodegradable fraction of material, also called the short-term BOD or BOD(ST). That value, in combination with a value for COD, can be used to determine the treatability of wastewater. Respirometry can also be applied on-line, e.g. for on-line monitoring of wastewater. However, automatic detection of the end-point of exogenous respiration is difficult. The first step towards on-line monitoring of wastewater treatability is to make automatic detection of this end-point possible. In this study the use of a neural network for detection of this end-point was investigated. Results are promising; after training the neural network is able to detect the correct end-point in the majority of the studied cases.

Automation↗
PubMed2006

Improving oxygen concentration control in activated sludge process with estimation of respiration and scheduling control.

The paper presents an efficient and simple model-based method of on-line estimation of respiration from the current values of dissolved oxygen concentration and airflow signals. Fast estimation of respiration is important because respiration appears as the most important disturbance signal in the control of dissolved oxygen concentration, and could therefore be used for improving control efficiency. A parameter scheduling PI (proportional and integral) control scheme is proposed, where the estimated respiration signal is used for scheduling of the PI controller parameters, by using local linearization of the process dynamics. The performance of the scheduling controller is compared to a conventional PI controller in simulation using the COST simulation benchmark, and experimentally on an activated sludge process pilot plant.

Aerobiosis↗
PubMed2006

The effects of water treatment residues on soil respiration and microbial community structure.

Land disposal of water treatment residue (WTR), a by-product of potable water production, is increasingly being considered a viable alternative to land filling. It is crucial, inter alia, that soil quality is not affected adversely. Six different WTRs obtained from South African water treatment facilities were added to Hutton and Westleigh topsoils at rates of 0, 5, 15 and 25% (m/m) to determine their impacts on soil basal respiration. In general, respiration increased with rate of addition of WTR. The Umgeni, Rand, Midvaal and Faure2 WTRs had the greatest effect on respiration. Increases in respiration became less marked with time. The Hutton topsoil was mixed with the WTRs (at 15% m/m) and, following incubation, the bacterial community structure was examined by denaturing gradient gel electrophoresis. Changes in community structure were detected after 5 d and were attributed to physico-chemical changes arising from WTR amendment. However, dominant bands associated with the Hutton soil were retained and microbial diversity was not adversely affected. The findings of this investigation suggest that WTRs can be applied to the Hutton soil at a rate of at least 15% (300 Mg ha(-1)) without having a detrimental effect on microbial indicators of soil quality.

Hydrogen-Ion Concentration↗
PubMed2000

Performance of respirator filters using quality factor in Korea.

A respirator filter of good quality has not only high aerosol collection efficiency but also low air resistance. "Quality factor", which is expressed with aerosol penetration and pressure drop, can be used to rank the performance of respirator filters within the same category. This study focuses on evaluating several respirator filters which are widely used in Korea using quality factor. Two mechanical filters and three filtering facepieces made by different manufacturers were measured aerosol penetrations and pressure drops by an automatic filter tester (CertiTest Model 8110, TSI Inc., St. Paul, USA) at four flow rates of 10, 32, 64 and 85 L/min. NaCl aerosols used were reported to be mean size of 0.1 microm and geometric standard deviation of <1.9. The penetrations and pressure drops of all filters have strong flow rate dependency. The filter quality factors decrease sharply as flow rates are increased. The mechanical filter S and filtering facepiece M are shown better filter quality than others in the same category. Since some certified filters are found to be inappropriate in the workplace exposed to fume, this result suggests that the current certified filter test protocol for respirators should be changed for the new protocol using smaller aerosols.

Aerosols↗
PubMed1989

Influence of menhaden oil on mitochondrial respiration in BHE rats.

The effects of corn or menhaden oil and thyroxine treatment on hepatic mitochondrial respiration was studied. BHE rats were fed a 64% sucrose, 6% corn, or menhaden oil diet until they were 60-70 days of age. Succinate-supported mitochondrial respiration was studied at 3 degrees C intervals from 4 to 40 degrees C. Upper and lower activation energies and transition temperatures were determined through the calculation of Arrhenius plot. Menhaden oil plus daily thyroxine injection resulted in higher and lower activation energies than the other treatments. This combined treatment also resulted in lower state 3 and higher state 4 respiration rates and tighter coupling of respiration to ATP synthesis. These effects were thought to be due to the effect this treatment combination had on membrane fluidity.

Animals↗
PubMed1992

An evaluation of MDI (metered dose inhaler) spacers and adapters: their effect on the respirable volume of medication.

The use of a metered dose inhaler (MDI) with an adapter or spacer designed to deliver medication to ventilated patients has been found to produce effects similar to those achieved with small volume nebulizers. For 9 commonly used MDI adapters or spacers, we measured and compared their production of available respirable volume (ARV) of medication. A simulated ventilator circuit was configured to determine ARV as measured by a laser particle-size counter. The adapters or spacers were grouped in three categories: chamber, in-line, and elbow styles. The devices were actuated into the circuit, and ARV was measured 36 separate times with various combinations of medication and medication canister. We found significant differences in ARV between devices, device categories, and medications as compared by ANOVA testing. In this study, chamber-style MDI devices produced greater respirable volume than the in-line- or the elbow-style devices. Of the chamber-style devices, the cone-shaped chamber device provided more respirable volume than did the other two chamber devices. We also found differences among the medications, although we did not anticipate such differences. The possible factors to explain medication differences were not investigated in this study. Because ARV differs according to the design of the individual device used, the choice of device may alter the respirable volume of the medication delivered and, therefore, the effectiveness of the prescribed medication. We conclude that to achieve the desired effects of the medication, practitioners may need to customize the number of MDI actuations according to the device in use.

Administration, Inhalation↗
PubMed1999

The effects of strapped spectacles on the fit factors of three manufactured brands of full facepiece negative pressure respirators.

A study was conducted to determine the effects of strapped spectacles on the fit factors obtained during quantitative fit testing on three different brands of full facepiece negative pressure respirators. The three brands of respirators were evaluated with and without strapped spectacles worn by the test subjects. A total of 180 quantitative fit testing trials were conducted on ten male test subjects. For each test subject, three quantitative fit testing trials were performed with each brand of respirator with and without the spectacles. The average of the fit testing trials for each subject with each respirator was used for statistical analysis. The results demonstrated that the fit factor values were significantly lower during use of the spectacles (p < 0.05). The estimated percentage of test subjects who failed the American National Standards Institute pass/fail criteria for quantitative fit testing (1000) increased by 15-36% when spectacles were worn.

Adolescent↗
PubMed2000

Alkanols inhibit respiration of intact mitochondria and display cutoff similar to that measured in vivo.

Primary aliphatic alcohols from hexanol to pentadecanol were tested for their effects on the succinate-supported respiration of intact mitochondria isolated from rat liver. Alkanols were found to inhibit State 3 and uncoupled respiration. The ADP/oxygen ratios, a measure of the efficiency of oxidative phosphorylation, also were lowered, but to a lesser degree when compared on the basis of percentage of controls. Given each alkanol's nearly identical effect on State 3 and uncoupled respiration, action is not directly on ATP synthase, but earlier in the respiratory process. In agreement with many other studies of the homologous series of alkanols, potency increased with number of carbons in the chain until reaching a peak, in this case at undecanol, then tapered off to tridecanol before reaching a cutoff, at tetradecanol. If tetradecanol or longer homologs have activity, it is only after a lag phase of >15-min preincubation. All alkanols up to tridecanol also acted as uncouplers. At higher doses, hexanol inhibited State 4 rates, whereas longer chain alkanols did not, even at doses that completely eliminated respiratory control. Hexanol and decanol also were assayed against freeze-thawed (broken) mitochondria to distinguish effects on the mitochondrial substrate carrier from those on the electron transport chain. Both compounds were only weak inhibitors of respiration in broken mitochondria, suggesting that inhibition originates from interference with the dicarboxylate carrier, which must transport succinate across the mitochondrial membranes before it can be fed into complex II, rather than affecting the electron transport chain itself.

Adenosine Diphosphate↗