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At least 19 recordsLinked to original sources
PubMed1976

[Place of neuroleptics in geriatric anesthesia].

The elderly show changes in various parenchymas linked to the process of ageing. Pathological abnormalities may be added to this picture leading to physiopathology peculiar to the aged. In relation to special problems raised by this background, the advantages and disadvantages of N.L.A. are discussed. The authors refer to an experiment in the Department of Anesthetics and Intensive Care in Créteil.

Aged↗
PubMed1978

Discussion on basic equations for a flow in human air passages and their representation.

Basic equations of time-dependent flow are discussed in the case of rigid or elastic branches and according to the airway representation pattern, both continuous and discontinuous. Two relevant fundamental continuous functions are defined: the 'order of generation' G(x) and the cumulative bronchial diameter D(x). A numerical solution is outlined in the former case, then in the latter case, and the system of equations which completely describes the flow is solved.

Bronchi↗
PubMed1977

Sensory irritation to formaldehyde and acrolein during single and repeated exposures in mice.

Mice were exposed to various concentrations of formaldehyde or acrolein. Concentration-response relationships were developed by measuring per cent decrease in respiratory rate, indicating upper respiratory tract sensory irritation. Relationships are presented between the concentration associated with a 50% respiratory decrease and TLVs. A summary of other animal inhalation studies is presented. The basis for the acrolein and formaldehyde TLVs are reviewed. Mice exposed for 4 days showed increasing sensitivity daily for both compounds. A re-evaluation of the TLVs is suggested.

Acrolein↗
PubMed1978

Effects of atropine and methacholine on deposition and clearance of inhaled particles in the donkey.

The influence of sympathetic and parasympathetic controls on regional particle deposition and mucociliary clearance rates was studied in the donkey in vivo. The deposition and clearance characteristics for gamma-tagged monodisperse ferric oxide microspheres were determined for inhalation tests after atropine and methacholine injections and were compared with the characteristics determined for control tests with the same animals and aerosols. Additional tests were performed in which methacholine was injected immediately after the test aerosol inhalation and 2 1/2 h before the particle inhalation. Particle deposition is shifted distally by atropine. Methacholine produces a proximal shift initially and a distal shift 2 1/2 h later. Atropine slows mucociliary transport. Methacholine produces an acceleration in bronchial clearance initially but causes a reduced rate of clearance 2 1/2 h later. Atropine slows mucociliary transport. Methacholine produces an acceleration in bronchial clearance initially but causes a reduced rate of clearance 2 1/2 h later. It also produces an initial surge in tracheal transport, which frequently leads to tracheal mucus refluxing and thereby an increase in average tracheal residence time. The drugs were used to modify the normal deposition and clearance characteristics of a particular animal so that they resembled the normal characteristics of a different animal, suggesting that much of the large intersubject variability may be attributable to different levels of autonomic tone.

Aerosols↗
PubMed1979

Control of mucus secretion and ion transport in airways.

The output of secretions from the airway submucosal glands is regulated by vagal efferent nerves. Stimulation of cough receptors increases mucus output reflexly via the vagus nerves. Adrenergic agonists increase submucosal gland secretions in some species, which indicates that adrenergic receptors are present in these cells. However, evidence for adrenergic nervous pathways to the glands is limited. Irritants and drugs stimulate secretion from epithelial cells by direct effects. There is also evidence that the secretion of epithelial cells can be stimulated by parasympathetic nervous pathways in birds but not in mammals. Active ion transport of Cl- toward the lumen and of Na+ toward the submucosa results in net ion movement toward the airway lumen in unstimulated tracheal epithelia. Drugs and mediators increase the net movement of ions toward the lumen. No agents have yet been found that increase net ion movement toward the submucosa. The link between ion transport and water secretion in airway epithelia, although speculative, seems likely in view of the evidence from other epithelia. Since airway epithelium is a "tight junction" epithelium, modification of the tight junction may alter the transepithelial movement of water and ions. We suggest that the depth and consistency of the periciliary layer of airway secretions determine the ability of the cilia to propel the mucoprotein gel and thereby modify mucociliary transport. To achieve this, secretion of mucus must be controlled separately from the secretion of water. Studies are needed to determine which of the specialized functions of the epithelial cells interact to regulate the clearance of secretions from the airway. Is the sol maintained by secretion and reabsorption of fluid across the epithelium? Does the sol move with the gel by ciliary action or does it remain stationary? Do changes in the epithelial tight junctions influence net water movement and thus indirectly alter the depth of the sol layer? To answer these questions, techniques are needed to study subunits of the airway, including isolated surface cells and submucosal glands; and sensitive methods are required to analyze the very small samples of secretions for glycoprotein and electrolyte content. Intracellular measurements of electrolyte concentrations and electrical potentials may help to elucidate the mechanisms of transepithelial ion and water movement. The control system for the production and removal of respiratory tract secretions may be altered in disease. For instance, chronic stimulation of cough receptors causes reflex secretion and may be the cause of the hyperplasia of submucosal glands and of the abnormal secretions that occur in chronic bronchitis and asthma (50, 58). The abnormally viscid mucus in cystic fibrosis may be due to a defect in Cl- transport, which provides too little water for both the gel and sol layers. These speculations are intended to identify areas for further research, which hopefully will reduce the morbidity and mortality in these common lung diseases.

Animals↗
PubMed1975

Mucocililary activity in the respiratory tract as influenced by prostaglandin E.

Evidence is presented from in vitro experiments in over 1,100 animals that the long accepted hypothesis of a continuous tracheobronchial mucus blanket is untenable, since mucus is transported in the form of flakes, plaques and continuous streams. It is proposed that a liquid of low viscosity lies between the cilia and covers their tips. This liquid is either not transported or very slowly so. Mucus flakes and plaques are transported by the tips of the cilia over this interciliary liquid. Prostaglandin E1 (PGE1) in low concentrations caused lysis of stagnant flakes and plaques. In addition, it caused a marked increase in the quantity of the tracheobronchial fluid and no clear-cut effect on the rate of ciliary frequency. The possible involvement of adenyl cyclase in the response to PGE1 is discussed.

Animals↗
PubMed1977

Defense mechanisms of the respiratory membrane.

The success or failure of pulmonary defense mechanisms largely determines the appearance of clinical lung disease. The lung is protected by interlucking systems of nonspecific and specific defenses. Inhaled substrances can be isolated by mechanical barriers or can be physically removed from the lung either by transport up the bronchial mucociliary escalator or by transport through interstitial and lymphatic channels leading to lymph nodes. Substances can be locally detoxified within the lung by interaction with secretory proteins, such as antibodies, or by neutralization and dissolution within phagocytic cells. The pulmonary alveolar macrophage is the central figure in the protection of the respiratory membrane, operating in all 3 of the nonspecific modes of defense and augmented by specific immunologic mechanisms as well. Alterations in macrophage function and physiology may be crucial in determining the effectiveness of pulmonary defense. Recent advances in the cell biology of the alveolar macrophage have led to a greater understanding of its complex funcition. The multiple origins of macrophages from local and circulating cell pools and the variability in their fate and lifespan reflect the multi-faceted role of this cell type. The importance of the interactions between macrophages, orther lung cells, and other defense mechanisms has become increasingly clear. As well as functioning as resident defender of the alveolus, the macrophage is an important effector of the pulmonary immune response and plays a key role in the pathogenesis of a wide variety of inflammatory, destructive, and fibrotic lung diseases. Humoral and cell-mediated immune responses amplify and direct lung defenses against infection and may also participate in protection against other agents. Immunoglobulin A and G, microbial neutralizing and opsonizing anti-bodies, and macrophage-stimulating T lymphocytes are the major immunospecific forms of lung defense. Infectious agents, cigarette smoke, air pollutants, industrial dusts, and a spectrum of coexistent disease states may impair pulmonary defense mechanisms and increase susceptibility to asute and chronic respiratory diseases. A thorough understanding of the ways in which the lung protects itself against the daily assault of infectious, toxic, and immunogenic materials should lead to a beter understanding of pathogenesis and consequences of lung disease and to better clinical care of the patient with respiratory disease.

Animals↗
PubMed1978

Compliances of human rib cage and diaphragm-abdomen pathways in relaxed versus paralyzed states.

The respiratory magnetometer method of Konno and Mead was used to measure separately the rib cage and the diaphragm-abdomen components of the total respiratory system compliance in 11 subjects with normal respiratory systems. Measurements made in the awake, relaxed state by the method of Heaf and Prime were compared with similar measurements made in the anesthetized, paralyzed state by the supersyringe method. The rib cage component was greater in the paralyzed than the relaxed state in 9 of 11 subjects, but the diaphragm-abdomen component was greater in the relaxed than the paralyzed state in 8 of 11 subjects. We believe that these differences can be explained by respiratory muscle activity in the presumed relaxed state. The fraction of the tidal volume attributable to rib cage displacement compared to abdominal displacement was greater during mechanical ventilation in the paralyzed state than during awake, spontaneous breathing. This can be explained by the different distribution of inflating forces produced by diaphragmatic contraction compared to positive airway and alveolar pressure, in particular by the very different patterns of diaphragmatic displacement in the 2 states.

Abdomen↗
PubMed1977

The respiratory tract and the environment.

The primary determinants of pulmonary disease are environmental. The same thinness and delicacy of the air-blood barrier which allows rapid exchange of oxygen and carbon dioxide also reduce its effectiveness as a barrier to inhaled allergens, carcinogens, toxic particles, and noxious gases, and micro-organisms. Adults breath 10,000 to 20,000 liters of air daily. This volume of air contains potentially hazardous contaminating particles and gases. Future research should explore the diverse physiological mechanisms which prevent the accumulation and deleterious action of inhaled particles and gases. Since most pulmonary diseases are either initiated by or at least aggravated by the inhalagion of particles and gases, the role of environmental factors in the development of respiratory disease is an area worthy of continued support.

Dust↗