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At least 541 records · Page 30Linked to original sources
PubMed1994

Tuberculosis control strategies: the cost of particulate respirators.

OBJECTIVE: To assess the cost of the mandatory use of high-efficiency particulate respirators to treat patients with known or suspected tuberculosis. DESIGN: A questionnaire was used to determine the number of high-efficiency particulate respirators required and the number of cases of tuberculosis in employees that could potentially be prevented. Indirect costs included the training and fitness testing of employees. The clinical efficacy of respirators is not known. To provide a best-case scenario, it was assumed that the respirators could prevent as many as 25% of tuberculosis cases in health care workers. SETTING: 159 acute care facilities administered by the Department of Veterans Affairs. PARTICIPANTS: Quality improvement, infection control, and employee health specialists. MEASUREMENTS: Cost of the respirators compared with their maximum predicted efficacy. RESULTS: The use of the respirators would cost $7 million per case of tuberculosis prevented and $100 million per life saved. CONCLUSIONS: High-efficiency particulate respirators are a costly means of trying to prevent tuberculosis. Costs could be reduced by reusing masks or by restricting the number of health care workers allowed to have contact with potentially infectious patients. As the health care budget undergoes further restrictions, specific means of accommodating the cost of new regulations must be found.

Cost-Benefit Analysis↗
PubMed1976

Effects and specificity of anticancer agents on the respiration and energy metabolism of tumor cells.

Using 35 new anticancer agents from the screening program of the National Cancer Institute we have performed a biochemical study of the effects on the respiration and oxidative phosphorylation of rat liver mitochondria and on the respiration of leukocyte, liver, L1210 leukemia, and Ehrlich ascites cell suspensions. Fifteen of the 35 compounds were found to be potent respiratory inhibitors as defined by 50% inhibition of mitochondrial respiration at concentrations of 110 mu mol/liter or less. The mechanism of respiratory inhibition by the drugs was either a rotenone-, antimycin-, or oligomycin-like effect. One triazine derivative showed some specificity for inhibiting tumor cell respiration in comparison with normal cell respiration. Two naphthoquinone derivatives showed inhibition of respiration in in vivo treatments at chemotherapeutic doses. It was concluded that data on respiratory effects may assist in the interpretation of the results of in vivo and in vitro screening tests of the drugs, and that in some cases, as with the naphthoquinone derivatives, the effects on respiration could be related to the mechanism of action or the mechanism of toxicity of the drugs.

Animals↗
PubMed1999

Development and activation of cyanide-resistant respiration in the yeast Yarrowia lipolytica.

Changes in respiratory activity and in the contents of adenine nucleotides (ATP, ADP, AMP) were studied in cells of the yeast Yarrowia lipolytica during the development of cyanide-resistant respiration. The transition of the yeast from the logarithmic to the stationary growth phase due to exhaustion of glucose was associated with decreased endogenous respiration and with the activation of a cyanide-resistant oxidase. Cyanide activated cell respiration during the stationary growth phase. The cyanide-resistant respiration was inhibited by benzohydroxamic acid (BHA), an inhibitor of the alternative oxidase. In the absence of cyanide, BHA had no effect on the cells which had the cyanide-resistant oxidase. This indicates that the cells do not use the alternative pathway in vivo. The decreased endogenous respiration of the cells was accompanied by decreased contents of adenine nucleotides. Addition of cyanide resulted in a sharp decrease in the content of ATP, in a twofold increase in the content of ADP, and in a fivefold increase in the content of AMP. In the absence of cyanide, BHA had virtually no effect on the contents of adenine nucleotides. The decreased rate of oxygen consumption during the transition of the cells to the stationary growth phase was caused by the decreased activity of the main cytochrome-containing respiratory chain (2,4-dinitrophenol (DNP) stimulated respiration). The alternative oxidase was synthesized in the cell but was inactive. Cyanide stimulated respiration due to activation of the alternative oxidase via the AMP produced. The decrease in the cell content of ATP is suggested to be a factor inducing the synthesis of the alternative oxidase.

2,4-Dinitrophenol↗
PubMedDate not supplied

[Conditions for the manifestation of cyanide-resistant respiration in Pseudomonas aeruginosa].

Conditions for manifestation of cyanide-resistant respiration were studied in Pseudomonas aeruginosa. Transition of the culture from the logarithmic to the stationary phase of growth, once the source of carbon (hexadecane, glucose, citrate, succinate) or nitrogen was exhausted, was accompanied with a decrease in the sensitivity of bacterial respiration to cyanide. As soon as the limiting factor was added, the culture started to grow again and its respiration became more sensitive to the inhibitor. Changes in the sensitivity of respiration to cyanide were observed when the bacterial growth was not limited with oxygen, and cyanide was not accumulated in the cultural broth. The manifestation of cyanide-resistant respiration was caused by changes in the physiological state of the bacterium induced by the cessation of growth. The culture formed phenazine pigments while growing on all of the studied substrates. However, no correlation was established between the resistance of respiration to cyanide and the concentration of the pigments in the medium. Therefore, the resistance of respiration of Ps. aeruginosa to cyanide should be attributed to changes in the electron transport chain.

Culture Media↗
PubMed2002

[An analysis of the length and costs of respirator use with observational data based on medical records].

OBJECTIVE: This paper documents an analysis of the impact of respirator use on medical expenses with observational data based on medical records from all over Japan. METHOD: The data set included records of medical procedures during a single month, but not for procedures and information extending over plural months. Accordingly, censoring was an important problem. To overcome this, samples are classified into four groups; complete, right censoring, left censoring and both censoring ones using length of respirator use and hospital stay. Then, the Gompertz model was applied to calculate the expected length of respirator use. Simultaneously, medical expenses for respirator use were also estimated. RESULTS: The estimated expected length of respirator use was from 10 to 104 days, with expected medical expenses per case of from 30,000 to 40,000 yen and the number of respirator usages on aggregate of 5510. CONCLUSIONS: This means the impact of respirator use on medical expenses is from 18 to 250 billion yen per year.

Costs and Cost Analysis↗
PubMed2003

[Effects of soil temperature and moisture on soil respiration in different forest types in Changbai Mountain].

The effects of soil temperature (0, 5, 15, 25, 35 degrees C) and water content on soil respiration in three forest types in Changbai Mountain were evaluated in laboratory condition. The results indicated that the soil respiration rate was positively correlated to soil temperature from 0 to 35 degrees C and it increased with soil water content from 0.21 to 0.37 kg.kg-1. The soil respiration rate decreased with soil water content when water content was over the range. The result suggested the interactive effects of temperature and water content on soil respiration. There were significant differences in soil respiration among the various forest types and the highest was in broad leaf Korean pine forest, then in erman's birch forest, and it was the lowest in dark coniferous forest. The optimal condition for soil respiration in broad-leaved Korean pine forest was at 35 degrees C under 0.37 kg.kg-1 water content, and it was at 25 degrees C under 0.21 kg.kg-1 in dark coniferous forest and at 35 degrees C under 0.37 kg.kg-1 water content in erman's birch forest. Because the forests of broad leaf Korean pine, dark coniferous and erman's birch are located at various altitudes, the soil temperatures had 4-5 degrees C variation in different forest types during the same period. The soil respiration rates measured in brown pine mountain soil were lower than those in dark brown forest and they were higher in mountain grass forest soil than those in brown pine mountain soil.

Carbon Dioxide↗
PubMed2005

[Affecting factors of soil microorganism and root respiration].

Soil respiration is an important part of the carbon cycle in terrestrial ecosystems, and its contribution to the global carbon budget has been the focus of wide concern. Researches on the affecting factors of soil microorganism and root respiration, the main components of soil respiration, contribute to the understanding of the role of soil respiration on global carbon cycle, and to the accurate evaluation of global carbon budget. This paper reviewed the direct and indirect affecting factors of soil microorganism and root respiration, including climate factors, soil properties, vegetation and litterfall, air CO2 concentration, and human activities. These affecting factors were interactive, and their contributions to soil microorganism and root respiration varied in temporal and spatial scales. The study on natural and anthropogenic factors of soil microorganism and root respiration was emphasized, and some related research tasks in the future were also proposed.

Bacteria↗
PubMed2006

[Respiration rate of broadleaved Korean pine forest ecosystem in Changbai Mountains].

In this paper, the respiration rates of soil, foliage, and stem and branch in the broadleaved Korean pine forest ecosystem of Changbai Mountains were measured by Li-6400 CO2 analysis system in 2003, with the microclimate factors determined synchronously. The correlation models of ecosystem respiration with environmental factors were established, and the respiration rate of each component of the ecosystem was estimated based on the vegetation characteristics of the broadleaved Korean pine forest. The results showed that the annual total respiration rate of the ecosystem was 1602. 8 g C x m(-2), with a mean of (4. 37+/-2. 98) micromol x m(-2) x s(-1) , and the respiration of soil, foliage, and stem and branch contributed about 63% , 21% , and 16% of the total, respectively. There was a significant correlation between system respiration and daily mean air and soil temperature, and about 87% and 95% of the ecosystem respiration could be explained by the air and soil temperature, respectively.

China↗
PubMed1989

Evaluation of dust respirators for elimination of mouse aeroallergens.

The efficiency of various dust respirators for eliminating mouse allergens [mouse urine proteins (MUP), pelts proteins (MPP) and serum albumin (MSA)] were evaluated with use of low-volume air samplers and immunochemical methods. Three kinds of dust respirators from one manufacturer which have different efficacy in the exclusion of dust particles were put on the fiber glass filter in each air sampler. Then the air in a mouse housing room was sampled. The allergens passed through the respirators, were trapped in the fiber glass filters, and then extracted from the filters. The allergens of MUP and MPP in the extract were measured by an inhibition method of fluorometric enzyme-linked immunosorbent assay (ELISA) for IgE antibody and those of MSA measured by a fluorometric sandwich ELISA. The respirator with the lowest capability of exclusion was found to eliminate 65-86% of respective allergens. The other two respirators with higher powers eliminated 98% of MUP. MPP and MSA were eliminated to undetectable levels through these respirators. This study provided a means for the evaluation of dust respirators for animal aeroallergens.

Air Pollution↗
PubMedDate not supplied

[Study of microorganism respiration according to the parameters of their delayed fluorescence].

A method for studying microbial respiration of low oxygen concentrations (10(-5)--10(-7) M) is described. The method was used for examining the respiration chain of the bacterium Escherichia coli and the yeast Saccharomyces cerevisiae. The following constants of the respiration chain for oxygen were calculated using the parameters of delayed bacterial fluorescence: the rate of respiration, the Michaelis constant, the concentration of oxygen critical for respiration. The decrease in the rate of respiration of low oxygen concentrations consists of two phases; this is related to the existence of two different pathways of oxidation in the terminal region of the respiration chain.

Escherichia coli↗
PubMed1995

[Elimination of periodic respiration in heart failure by heart transplantation].

Patients with heart failure are known to demonstrate periodic respiration during sleep. The mechanism behind periodic respiration is thought to be related to left heart enlargement causing an increased transit time between lung and chemoreceptors leading to an oscillation of the feed back loop controlling respiration. Additionally hyperventilation was shown to play an important role. We report of an 18 year old patient with idiopathic dilated cardiomyopathy (left atrial 52 mm, left ventricular end diastolic diameter 69 mm). Polysomnography revealed prolonged transit time and periodic respiration with impaired sleep. Hypocapnia and hyperventilation was demonstrated. Following successful cardiac transplantation periodic respiration was absent and transit time was normal. There was no hypocapnia or hyperventilation. Hypercapnic ventilatory response did no change. These findings support the model of an oscillation of the feed back loop controlling respiration as the main pathomechanism behind periodic respiration.

Adolescent↗
PubMed2005

Cheyne-Stokes respiration in patients with congestive heart failure: causes and consequences.

Cheyne-Stokes respiration is a form of periodic breathing in which central apneas and hypopneas alternate with periods of hyperventilation, producing a waxing and waning pattern of tidal volume. This review focuses on the causes and consequences of Cheyne-Stokes respiration in patients with congestive heart failure, in whom the prevalence is strikingly high and ranges from 30% to 50%. Several factors have been implicated in the genesis of Cheyne-Stokes respiration, including low cardiac output and recurrent hypoxia. The key pathophysiological mechanism triggering Cheyne-Stokes respiration is hyperventilation and low arterial CO2 (PaCO2) that when below the apneic threshold triggers a central apnea. Hyperventilation is associated with pulmonary congestion, and Cheyne-Stokes respiration is more prone to occur during sleep, when the respiratory system is mainly dependent on chemical control. It is associated with recurrent dips in oxygen saturation and arousals from sleep, with oscillations in blood pressure and heart rate, sympathetic activation and increased risk of ventricular tachycardia. Cheyne-Stokes respiration is an independent marker of poor prognosis and may participate in a vicious cycle, further stressing the failing heart.

Blood Circulation↗
PubMed2004

Color Doppler sonographic signs of respiration-dependent hepatofugal portal flow.

PURPOSE: The role of respiration in modulating blood flow in the portal vein is unclear. The aim of this study was to investigate the phenomenon of respiration-dependent periodic hepatofugal portal venous blood flow as detected on color Doppler sonography. METHODS: Within 1 year, we identified 13 patients with respiration-dependent reversal of blood flow in the portal vein that was diagnosed on color Doppler sonography. This phenomenon was investigated by color Doppler sonographic examination of the portal venous flow during both mid-inspiration breath-holding and a respiratory cycle including deep inspiration; evaluation of hepatic vein Doppler waveforms as normal (triphasic) or decreased (flattened); and echocardiographic examination to determine the presence or absence of tricuspid regurgitation. RESULTS: The patients' median age was 53 years (range, 26-87 years). Seven of the 13 patients had heart disease (tricuspid regurgitation) with or without liver disease, 3 had liver disease without heart disease, and 3 had other diseases with no evidence of heart or liver disease. On Doppler sonography, 10 of the 13 patients had increased portal venous pulsatility (7 of the 10 had tricuspid regurgitation; the other 3 did not); the remaining 3 patients had neither increased pulsatility nor tricuspid regurgitation. Sonographic follow-up within 4 weeks in 4 of the 13 patients revealed loss of the respiration-dependent hepatofugal portal flow. CONCLUSIONS: Respiration-dependent hepatofugal portal flow is a rare finding associated with periodic portal hypertension in patients with right heart insufficiency and liver disease. Its clinical significance is unclear. Among our patients, its occurrence was predominantly associated with an increased venous pulsatility index due to tricuspid regurgitation or venous outflow obstruction. Further study is needed to investigate whether periodic respiration-dependent hepatofugal portal flow is predictive of the occurrence of continuous flow reversal.

Adult↗
PubMed2006

(13)C/(12)C isotope labelling to study leaf carbon respiration and allocation in twigs of field-grown beech trees.

In situ (13)C/(12)C isotopic labelling was conducted in field-grown beech (Fagus sylvatica) twigs to study carbon respiration and allocation. This was achieved with a portable gas-exchange open system coupled to an external chamber. This method allowed us to subject leafy twigs to CO(2) with a constant carbon isotope composition (delta(13)C of -51.2 per thousand) in an open system in the field. The labelling was done during the whole light period at two different dates (in June 2002 and October 2003). The delta(13)C values of respiratory metabolites and CO(2) that is subsequently respired during the night were measured. It was found that night-respired CO(2) is not completely labelled (only ca. 58% and 27% of new carbon is found in respired CO(2) immediately after the labelling in June 2002 and October 2003, respectively) and the labelling level progressively disappeared during the next day. It is concluded that the carbon respired by beech leaves after illumination was supplied by a mixture of carbon sources in which current carbohydrates were not the only contributors. In addition, as has been found in herbaceous plants, isotopic data before labelling showed that carbon isotope discrimination favoring the (13)C isotope occurred during the night respiration of beech leaves.

Carbon↗
PubMed1999

Photodynamic therapy-induced apoptosis in lymphoma cells: translocation of cytochrome c causes inhibition of respiration as well as caspase activation.

L5178Y-R mouse lymphoma (LY-R) cells undergo rapid apoptosis when treated with photodynamic therapy (PDT) sensitized with the silicon phthalocyanine Pc 4. In this study we show that cytochrome c is released into the cytosol within 10 min of an LD99.9 dose of PDT. Cellular respiration is inhibited by 42% at 15 min, and 60% at 30 min after PDT treatment, and caspase 3-like protease activity is elevated by 15 min post-PDT. In digitonin-permeabilized cells addition of cytochrome c to the respiration buffer reverses PDT-induced inhibition of state 3 respiration via Complex I by 40-60%, and via Complex III by 50-90%. In contrast, extramitochondrial cytochrome c does not stimulate respiration in permeabilized control cells, and catalyzes only a low rate of oxygen consumption via electron transfer to cytochrome b5 on the outer mitochondrial membrane. These results demonstrate that PDT-induced inhibition of respiration is primarily due to leakage of cytochrome c into the cytosol rather than to damage to the major enzyme complexes of the electron transport chain. Whether or not inhibition of respiration influences the time course or extent of Pc 4-PDT-induced apoptosis in LY-R cells is not clear at the present time.

Animals↗
PubMed2002

Unconstrained and non-invasive measurement of heart-beat and respiration periods using a phonocardiographic sensor.

With the rapid growth in the number of elderly people in the population, interest in health monitoring is increasing. Therefore the development of an unconstrained and non-invasive vital signs measurement system could be important for monitoring health status at home or in hospitals or nursing facilities. A simple system is proposed for measuring heart-beat and respiration periods for home healthcare. This was achieved with a phonocardiographic (PCG) sensor set on a water-mat or air-mat. The PCG sensor was an acceleration sensor that extracted the vibration of the mat caused by heart-beat and respiration. By calculating an autocorrelation function of the fully rectified sensor output or by local pattern matching between the rectified output and a reference signal (pre-memorised for each subject), the system measured the average and instantaneous periods of both heart-beat and respiration. Results showed that these periods were measured to a similar level of accuracy as for the electrocardiogram and thermistor respiration pickup. The comparative accuracies were within the following ranges: average heartbeat 0.19% to 0.67%, instantaneous heartbeat 0.53% to 1.15%, average respiration 0.51% to 2.17%, and instantaneous respiration 2.51% to 5.20%.

Adult↗
PubMed2004

Dynamical coupling between locomotion and respiration.

In search of the formative principles underwriting locomotor-respiratory coupling, we reanalyzed and modeled the data collected by Siegmund and coworkers (1999) on the synchronization of respiration during rowing. Apart from the frequency doubling in respiration reported earlier, detailed time-resolved spectral analyses revealed decreasing stability of entrainment close to abrupt changes in frequency relations as well as switches in the relative phase between respiration and locomotion. A single physiological, albeit mechanically constrained, quantity sufficed to explain the observed frequency and phase locking phenomena: the effective value of oxygen volume in the lungs. The cyclic abdominal pressure modulates the self-sustaining rhythmic respiration, modifies the total lung pressure, and causes (local) maxima at frequency ratios between movement and respiration that are composed of small integers. Hence, optimizing the effective oxygen volume can be seen as the mechanism that drives respiration to synchronize with locomotion.

Biomechanical Phenomena↗
PubMed1999

Portal venous blood flow while breath-holding after inspiration or expiration and during normal respiration in controls and cirrhotics.

In this study, we used magnetic resonance (MR) imaging to measure portal blood flow in 12 healthy controls and 17 cirrhotics while they were breath-holding after inspiration and after expiration. We then compared the results with measurements made during normal respiration in the healthy controls and cirrhotics. Blood flow in the main portal vein under basal fasting conditions was quantitated using the cine phase-contrast MR velocity mapping method. Three measurements were made on one occasion, as follows: (1) throughout the cardiac cycle during normal respiration, (2) with the subject breath-holding after maximal inspiration, and (3) with the subject breath-holding after maximal expiration. During normal respiration, portal blood flow was 1.3 +/- 0.21/min in controls vs 1.0 +/- 0.11/min in cirrhotics (P < 0.0001); while subjects were breath-holding after inspiration, portal blood flow was 1.0 +/- 0.21/min in controls vs 0.9 +/- 0.11/min in cirrhotics; and while subjects were breath-holding after expiration, portal blood flow was 1.5 +/- 0.21/min in controls vs 1.1 +/- 0.21/min in cirrhotics (P < 0.0001). The differences were primarily due to changes in flow velocity. When the magnitude of these hemodynamic changes in the three respiratory conditions was compared in controls and cirrhotics, analysis of variance (ANOVA) showed a significant difference (P < 0.0001). In controls, portal blood flow decreased during maximal inspiration relative to flow during normal respiration (-24.6 +/- 8.3%). Changes in portal blood flow in controls were greater than in cirrhotics (-13.5 +/- 4.5%) (P < 0.0001); however, the difference in blood flow increase associated with maximal expiration between the two groups (+11.8 +/- 9.4% vs +5.9 +/- 11.5%) was not significant. We found that the respiration-induced hemodynamic variation in portal blood flow was less in cirrhotics than in the healthy controls. Portal blood flow measurements made during normal respiration using MR imaging closely reflect nearly physiologic conditions.

Adult↗