PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “RESPIRATORY SYSTEM”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed1977

Studies on the respiratory system of Aspergillus oryzae. V. Some properties of the respiratory system of mitochondria from mycelia grown in the presence of chloramphenicol.

Presence of chloramphenicol in the growth medium for mycelia of Aspergillus oryzae was without effect on the oxidative activity, respiratory control, or P/O ratio of isolated mitochondria. The mitochondria oxidized Krebs cycle intermediates even in the presence of cyanide at the concentration markedly inhibiting the normal mitochondrial oxidation. However, the P/O ratio during the mitochondrial oxidation decreased by about 1.0 on addition of cyanide. The c-type cytochromes, shown to occur in large amounts than in normal mitochondria (Wakiyama and Ogura, 1972), were suggested to act as electron carriers in this cyanide-resistant oxidation. A novel pigment, demonstrated only in the mitochondria prepared from chloramphenicol-treated mycelia by a CO-difference spectrum, was presumed to be the terminal oxidase of the respiration in the presence of cyanide.

Antimycin A↗
PubMed2000

Surgery of the avian respiratory system.

The avian respiratory system is different from that of mammals. Although some surgical techniques can be adapted from those used in mammals, many are unique to avian patients (e.g., choanal atresia correction and air sac cannulation). This article reviews the common surgeries of the upper and lower respiratory systems and describes surgical techniques for the treatment of chronic sinusitis and cranial coelomic mass removal.

Animals↗
PubMedDate not supplied

Respiratory system involvement in systemic vasculitides.

The respiratory system may be involved in all systemic vasculitides (SV), although with a variable frequency. Lung disease is a very common and important feature of the antineutrophil cytoplasmic antibodies (ANCA)-associated SV (AASV), such as Wegener's granulomatosis (WG), Churg-Strauss syndrome (CSS), and microscopic polyangiitis (MPA). In WG, almost all patients have either upper airway or lower respiratory tract disease. Solitary or multiple nodules and masses are the most common findings on chest radiograph. Asthma is a cardinal symptom of CSS, often preceded by allergic rhinitis, frequently complicated by nasal polyposis and sinusitis. Pulmonary transient and patchy alveolar infiltrates are the most common radiographic findings. In MPA, diffuse alveolar hemorrhage (DAH) due to alveolar capillaritis is the most frequent manifestation of the respiratory involvement, clinically expressing with hemoptysis, respiratory distress and anemia. However, DAH may be subclinical and has to be suspected when chest radiograph demonstrates new unexplained bilateral alveolar infiltrates, in the face of falling hemoglobin levels. In giant cell arteritis, the most frequent respiratory symptom is cough, usually non-productive, persistent, and responsive to corticosteroids. In Takayasu arteritis, pulmonary involvement is frequently subclinical and detectable by non-invasive techniques. Pulmonary involvement is rare in polyarteritis nodosa, Kawasaki disease, Henoch-Schönlein purpura and cryoglobulinemic vasculitis. In conclusion, the involvement of the respiratory system is a very common and important feature of AASV, whereas is less frequent in other SV. It comprises a wide spectrum of clinical features and radiological findings, and may have a prognostic significance. The assessment of the respiratory system should be included in the work-up of all patients with SV, especially of those with AASV.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1985

Measurement of static compliance of the total respiratory system in patients with acute respiratory failure during mechanical ventilation. The effect of intrinsic positive end-expiratory pressure.

In mechanically ventilated patients with acute respiratory failure, the static compliance of the total respiratory system is conventionally obtained by dividing the tidal volume by the difference between the "plateau" pressure measured at the airway opening (PaO) during an occlusion at end-inspiration and positive end-expiratory pressure (PEEP) set by the ventilator. This analysis is valid only if the elastic recoil pressure of the respiratory system is zero at the end of expiration, indicating that the system has reached its elastic equilibrium point. To test if this is always the case, in 14 mechanically ventilated patients with acute respiratory failure, measurements were made of PaO and of flow and volume changes. In only 4 of the patients did expiratory flow become nil before end-expiration and inspiratory flow started synchronously with the onset of the positive-pressure swing delivered by the ventilator, indicating that in these 4 patients the end-expiratory elastic recoil pressure was indeed zero. By contrast, in the remaining 10 subjects, expiratory flow was still present when the ventilator had already begun to increase PaO, indicating that the end-expiratory elastic recoil pressure was not zero. Indeed, in all these 10 patients, a positive delta PaO (as much as 7.5 cm H2O) had to be applied by the ventilator before the actual onset of inspiratory flow. This delta PaO represents the pressure required to counterbalance the end-expiratory elastic recoil before inspiratory flow will begin, and can be termed intrinsic PEEP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2001

Static and dynamic pressure-volume curves reflect different aspects of respiratory system mechanics in experimental acute respiratory distress syndrome.

INTRODUCTION: A lower inflection point, an upper inflection (or deflection) point, and respiratory system compliance can be estimated from an inspiratory static pressure-volume (SPV) curve of the respiratory system. Such data are often used to guide selection of positive end-expiratory pressure (PEEP)/tidal volume combinations. Dynamic pressure-volume (DPV) curves obtained during tidal ventilation are effortlessly displayed on modern mechanical ventilator monitors and bear a theoretical but unproven relationship to the more labor-intensive SPV curves. OBJECTIVE: Attempting to relate the SPV and DPV curves, we assessed both curves under a range of conditions in a canine oleic acid lung injury model. METHODS: Five mongrel dogs were anesthetized, paralyzed, and monitored to assure a stable preparation. Acute lung injury was induced by infusing oleic acid. SPV curves were constructed by the super-syringe method. DPV curves were constructed for a range of PEEP and inspiratory constant flow settings while ventilating at a frequency of 15 breaths/min and tidal volume of 350 mL. Functional residual capacity at PEEP = 0 cm H2O was measured by helium dilution. The change in lung volume by PEEP at 8, 16, and 24 cm H2O was measured by respiratory inductance plethysmography. RESULTS: The slope of the second portion of the DPV curve did not parallel the corresponding slope of the SPV curve. The mean lower inflection point of the SPV curve was 13.2 cm H2O, whereas the lower inflection point of the DPV curve was related to the prevailing flow and PEEP settings. The absolute lung volume during the DPV recordings exceeded (p < 0.05) that anticipated from the SPV curves by (values are mean +/- SEM) 267 +/- 86 mL, 425 +/- 129 mL, and 494 +/- 129 mL at end expiration for PEEP = 8, 16, and 24 cm H2O, respectively. CONCLUSIONS: The contours of the SPV curve are not reflected by those of the DPV curve in this model of acute lung injury. Therefore, this study indicates that DPV curve should not be used to guide the selection of PEEP/tidal volume combinations. Furthermore, an increase in end-expiratory lung volume occurs during tidal ventilation that is not reflected by the classical SPV curve, suggesting a stable component of lung volume recruitment attributable to tidal ventilation, independent of PEEP.

Animals↗
PubMed2003

Developmental dynamics of the bronchial (airway) and air sac systems of the avian respiratory system from day 3 to day 26 of life: a scanning electron microscopic study of the domestic fowl, Gallus gallus variant domesticus.

The lung buds were first conspicuous on day 3 of embryogenesis. They fused on day 4 and the common growth divided into left and right primordial lungs on day 5. Progressively, the lungs elongated, diverged, and advanced towards the respective dorsolateral aspects of the body wall, reaching their definitive topographical locations in the coelomic cavity on day 6. On day 7, they rotated, attached onto the ribs, gradually started to slide into them, and were deeply inserted by day 8. The primary bronchus (PB) first appeared as a solid cord of epithelial cells (day 4) that successively canalized as it invaded the surrounding mesenchyme, extending along the proximal-distal axis of the lung. From day 8, the secondary bronchi (SB) begun to sprout from the PB in a craniocaudal sequence. On day 9, the parabronchi (PR) started to bud from the SB, projecting into the adjacent mesenchyme. They commenced to canalize on day 10 and greatly increased in length, number, and diameter. By day 13, the PR had anastomosed profusely and totally masked the SB. The luminal surface of the PR was lined by a columnar epithelium from which the atria (day 15), infundibulae (day 16), and air capillaries (ACs) (day 18) developed. At hatching (day 21), the ACs were well developed and had anastomosed profusely with the blood capillaries. Of the air sacs (ASs), the abdominal ones appeared earliest (day 5) followed by the cervical ones on day 6. In quick succession, the other ASs were well formed by day 10. After hatching, no further consequential structures formed: only shifts in topographical locations and an increase in size and number occurred. Morphogenetically, the avian respiratory system differs from the mammalian one in certain key aspects: besides the ASs that are unique to it, the lung is exceptionally complex in structure and is essentially mature at the end of the embryonic life.

Air Sacs↗
PubMed1999

Biotransport in the human respiratory system.

The human respiratory system is an 'open' organ, which is designed to exchange oxygen and carbon dioxide between the circulating blood and the external environment. This gas exchange is successfully accomplished via a set of transport phenomena comprised of oscillatory air flow, heat and water vapor exchange, mucus transport and air-blood gas exchange all of which take place in a complex geometry that undergoes large changes. These transport phenomena occur simultaneously to supply the body's need for oxygen in different physiological conditions and/or environments, while defending it from external hazards. The need for better comprehension of the mechanisms involved in pulmonary diseases and for advanced techniques for both diagnosis and intervention stimulated numerous studies of the different biotransport processes that take place in the human respiratory system.

Body Temperature Regulation↗
PubMed1985

Noninvasive determination of respiratory system mechanics during mechanical ventilation for acute respiratory failure.

In 10 acutely ill patients mechanically ventilated for management of acute respiratory failure, respiratory system mechanics were determined with the interrupter technique as described recently (J Appl Physiol 1984; 56:681-690). Flow, volume, and tracheal pressure were measured throughout a series of brief expiratory interruptions. A plateau in tracheal pressure during interruption was observed in all patients, indicating respiratory muscle relaxation as well as equilibration between alveolar and tracheal pressure. Measurement of the plateau in postinterruption tracheal pressure, corresponding volume, and preceding flow enabled determination of the passive elastic and flow-resistive properties of the total respiratory system. In general, the volume-pressure relationship was linear over the expired volume examined and did not necessarily pass through the origin, indicating deviation of the end-expiratory lung volume during mechanical ventilation from the equilibrium position of the respiratory system. Elastance, or inverse slope of this relationship, averaged 16.88 +/- 1.90 (SE) cmH2O X 1(-1). The pressure-flow relationship of the respiratory system was curvilinear; resistance averaged 19.74 +/- 2.08 (SE) cmH2O X 1(-1) X s at a flow rate of 1.0 1 X s-1. In 6 patients the pressure-flow relationship was concave upward. An upward convexity, particularly towards end expiration, was present in the remaining patients. This was associated with characteristic "supramaximal" flow transients after expiratory interruptions, indicating the presence of dynamic airway compression and expiratory flow limitation. In conclusion, the interrupter technique enabled detailed examination of the passive elastic and flow-resistive properties of the total respiratory system in mechanically ventilated patients using simple, noninvasive equipment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1997

The avian respiratory system: a unique model for studies of respiratory toxicosis and for monitoring air quality.

There are many distinct differences (morphologic, physiologic, and mechanical) between the bird's lung-air-sac respiratory system and the mammalian bronchoalveolar lung. In this paper, we review the physiology of the avian respiratory system with attention to those mechanisms that may lead to significantly different results, relative to those in mammals, following exposure to toxic gases and airborne particulates. We suggest that these differences can be productively exploited to further our understanding of the basic mechanisms of inhalant toxicology (gases and particulates). The large mass-specific gas uptake by the avian respiratory system, at rest and especially during exercise, could be exploited as a sensitive monitor of air quality. Birds have much to offer in our understanding of respiratory toxicology, but that expectation can only be realized by investigating, in a wide variety of avian taxa, the pathophysiologic interactions of a broad range of inhaled toxicants on the bird's unique respiratory system.

Aerosols↗
PubMed1988

Tonic sensory pathways of the respiratory system.

Both respiratory centres and the preganglionic vagal motoneurones, which control respiratory (striated) and airway (smooth) muscles respectively, receive information on the lungs, the circulation and the skeletal and respiratory muscles. Each of these nervous pathways has two components: one is phasic, i.e. in phase with biological rhythms, and comes from mechanoreceptors connected to large myelinated fibres; the second has a tonic low frequency firing rate and corresponds to the spontaneous activity of polymodal receptors connected to thin sensory fibres, which act mostly as sensors of changes in extracellular fluid composition (O2 and/or CO2 partial pressure, pH, release of algesic agents etc...). Some of them also detect large mechanical disturbances or local temperature changes. The influence of tonic background sensory activity is well known in animals concerning the role played by arterial chemoreceptors in the control of ventilation and of thin vagal afferents from the lungs (bronchopulmonary C-fibres and irritant receptors) in reflex facilitation of the bronchoconstrictor vagal tone. Moreover, the stimulation of thin sensory fibres in particular circumstances is responsible for hyperventilation (arterial chemoreceptors and muscle afferents), increased airway tone (arterial chemoreceptors and mostly thin vagal afferent fibres) or bronchodilation (muscle afferents). These peripheral inputs project centrally on different structures and also on brain stem neurones, which integrate simultaneously chemosensory, vagal and muscle information. This results in complex interactions between the different sensory pathways.

Animals↗
PubMed1992

Four-year follow-up of effects of toluene diisocyanate exposure on the respiratory system in polyurethane foam manufacturing workers. II. Four-year changes in the effects on the respiratory system.

Fifty-seven polyurethane foam manufacturing workers (PF workers) and 24 reference workers were followed for 4 years to clarify the effects on pulmonary function of working in PF factories with exposure to toluene diisocyanate (TDI). No significant differences in the average annual losses (AALs) of pulmonary function for 4 years were observed among the 28PF workers whose TDI exposure levels were very low (mean = 0.1 ppb, group L), the remaining 29 PF workers with mean TDI exposure of 5.7 ppb (group H), and the reference workers. However, 15 PF workers in group H who had experienced peak exposure excursions to 30 ppb or above with a mean concentration of 8.2 ppb showed significantly larger AALs in percentage maximal mid-expiratory flow, forced expiratory volume in 1 s ratio to vital capacity (FVC), and forced expiratory flow at 25% of FVC than expected, and significantly larger AALs in some obstructive pulmonary function indices than those of the 14 remaining PF workers in group H whose peak exposure excursion levels were 3-14 ppb with a mean time-weighted average (TWA) of 1.7 ppb, group L, and the reference workers. These findings suggest that the peak exposure excursion level of TDI might be important in inducing obstructive pulmonary function changes in the PF workers rather than the TWA exposure levels, though further comparative studies of the AAL in those who are exposed to different peak exposure excursion levels but the same mean exposure levels are necessary. From the standpoint of prevention, the proposition that peak exposure excursion levels exceeding 20 ppb should be avoided is reasonable.

Adult↗