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At least 523 records · Page 29Linked to original sources
PubMed2003

Invited review: Mechanisms underlying motor unit plasticity in the respiratory system.

Neuromotor control of skeletal muscles, including respiratory muscles, is ultimately dependent on the function of the motor unit (comprising an individual motoneuron and the muscle fibers it innervates). Considerable diversity exists across diaphragm motor units, yet remarkable homogeneity is present (and maintained) within motor units. In recent years, the mechanisms underlying the development and adaptability of respiratory motor units have received great attention, leading to significant advances in our understanding of diaphragm motor unit plasticity. For example, following imposed inactivity of the diaphragm muscle, there are changes at phrenic motoneurons, neuromuscular junctions, and muscle fibers that tend to restore the ability of the diaphragm to sustain ventilation. The role of activity, neurotrophins, and other growth factors in modulating this adaptability is discussed.

Animals↗
PubMed1993

[Use of spirometry in the evaluation of the cardiovascular and respiratory system in mitral valve prosthesis].

Before the operation, in 103 patients with the defects of the right and left atrioventricular valves, echocardiography and spiro-ergometry were performed. Their performance permitted to reveal latent myocardial incompetence in these patients. Changes in the indices of external respiration and gas exchange at a level of the threshold standard load can serve as objective criteria for assessment of reserve resources of the cardiovascular and respiratory systems and prognosis of the development of acute cardiac failure at the shortest period after the mitral valve replacement.

Adolescent↗
PubMedDate not supplied

[Effect of pyrolysis products of polypropylene plastic on the defence mechanisms of the respiratory system (author's transl)].

Since the use of plastic materials, a change in the pathology of fire victims has been observed. We studied the effects of a single short-term inhalation (30 min) of a sub-lethal dose of polypropylene pyrolysis products (one LD-0). Including control and test animals, 66 rats and 112 mice were used. The exposure provoked disturbances in the antixenic defense mechanisms of the respiratory system, chiefly in tracheo-bronchial defenses, since we observed a lowering of ciliary activity of 35 to 78% in test animals exposed a few hours before, compared with the controls. These changes provoked a significant increase in death-rate of test animals, following experimental airborne infection by Klebsiella pneumoniae. The combustion products of polypropylene plastic materials did not contain hydrocyanic acid nor hydrochloric acid, and neither the temperature of the inhaled air, nor the concentration of carbon monoxide could explain these effects. On the contrary, we can suspect the well known irritative properties of aldehyde compounds formed during smoldering combustion of polypropylene.

Air Microbiology↗
PubMed2001

Significance of the changes in the respiratory system pressure-volume curve during acute lung injury in rats.

UNLABELLED: The hypothesis that the changes in the respiratory system pressure- volume (PV) curve during pulmonary edema mainly reflect distal airway obstruction was investigated in rats. Normal rats had a well-defined upper inflection point (UIP) at low airway pressure. Airway occlusion by liquid instillation decreased compliance (Crs) and the volume (Vuip) of the UIP, and increased end-inspiratory pressure. The same changes were observed during the progression of edema produced by high volume ventilation (HV). Changes in Vuip and in Crs produced by HV were correlated with edema severity in normal rats or rats with lungs preinjured with alpha-naphthylthiourea. Vuip and Crs changes were proportional, reflecting compression of the PV curve on the volume axis and suggesting reduction of the amount of ventilatable lung at low airway pressure. In keeping with this explanation, the lower Vuip and Crs were before HV, the more severe HV-induced edema was in alpha-naphthylthiourea-injected rats. When edema was profuse, PV curves displayed a marked lower inflection point (LIP), the UIP at low pressure disappeared but another was seen at high volume above the LIP, and the correlation between Vuip changes and edema severity was lost. These observations may have clinical relevance in the context of the "open lung" strategy. KEYWORDS: ventilator-induced lung injury; respiratory mechanics; acute respiratory distress syndrome

Airway Resistance↗
PubMed2006

Characterization of regional and local deposition of inhaled aerosol drugs in the respiratory system by computational fluid and particle dynamics methods.

The present work describes the local deposition patterns of therapeutic aerosols in the oropharyngeal airways, healthy and diseased bronchi and alveoli using computational fluid and particle dynamics techniques. A user-enhanced computational fluid dynamics commercial finite- volume software package was used to compute airflow fields, deposition efficiencies, and deposition patterns of therapeutic aerosols along the airways. Adequate numerical meshes, generated in different airway sections, enabled us to more precisely define trajectories and local deposition patterns of inhaled particles than before. Deposition patterns show a high degree of heterogeneity of deposition along the airways, being more uniform for nanoparticles compared to micro-particles in the whole respiratory system at all inspiratory flow rates. Extrathoracic and tracheobronchial deposition fractions of nanoparticles decrease with increasing flow rates. However, vice versa happens to the micron-size particles, that is, the deposition fraction is higher at high flow rates. Both airway constrictions and the presence of tumors significantly increased the deposition efficiencies compared to the deposition efficiencies in healthy airways by a factor ranging from 1.2 to 4.4. In alveoli, the deposition patterns are strongly influenced by particle size and direction of gravity. This study demonstrated that numerical modeling can be a powerful tool in the aerosol drug delivery optimization. Present results may be integrated in future aerosol drug therapy protocols.

Administration, Inhalation↗
PubMedDate not supplied

The effect of artifical ventilation and dehydrobenzperidol on the development of early changes in the respiratory system in dogs with Mendelson's syndrome.

The experiments were carried out to observe certain functional changes in the respiratory system which develop in the early stage of aspiration pneumonia and to study the possibility of influencing these changes by application of artificial ventilation (IPPB) and/or administration of dehydrobenzperidol. The experiments were carried out on 32 mongrel dogs divided into 4 groups. Experimental Mendelson's syndrome was produced by instilling, during anaesthesia, hydrochloric acid solution of pH 1.5 in a dose of 4 ml/kg into the tracheobronchial tree. Immediately after anaesthesia and then 10 times at intervals of one hour after HCl instillation the following determinations were done: mean blood pressure, CVP, haematocrit, PO2 and PCO2 in arterial and mixed venous blood, and minute artifical ventilation. The veno-arterial blood shunt in the lungs, alveolo-arterial difference of oxygen partial pressure and the effective compliance were also determined. The chemical damage to the lungs by acid caused condensation of blood and a fall in CVP. These changes were due to fluid escape from the vessels especially in the pulmonary vascular tree. Disturbances in pulmonary gas exchange were a result of deficient ventilation of lung areas damaged primarily by acid and suffering secondarily from developing disturbances in pulmonary blood flow. Dehydrobenzperidol in a dose of 1 mg/kg applied as the only treatment in Mendelson's syndrome had the same favourable effect on pulmonary changes as controlled IPPB. The combination of controlled artificial ventilation and intravenous dehydrobenzperidol decreased the disturbances in pulmonary gas exchange in Mendelson's syndrome. This was possible because both factors exert a benficial effect on ventilation and perfusion preventing the development of oedema and atelectasis.

Adrenergic alpha-Antagonists↗
PubMed2000

Pattern of deposition of stainless steel welding fume particles inhaled into the respiratory systems of Sprague-Dawley rats exposed to a novel welding fume generating system.

In order to investigate occupational diseases related to welding fume exposure, such as nasal septum perforation, pneumoconiosis and manganese intoxication, we built a welding fume exposure system that included a welding fume generator, exposure chamber and fume collector. The fume concentrations in the exposure chamber were monitored every 15 min during a 2-h exposure. Fume (mg/m(3)) concentrations of major metals, including Fe, Mn, Cr, and Ni were found to be consistently maintained. An acute inhalation toxicity study was conducted by exposing male Sprague-Dawley rats to the welding fumes generated in this apparatus by stainless steel arc welding. The rats were exposed in the inhalation chamber to a welding fume with a concentration of 62 mg/m(3) total suspended particulates for 4 h. Animals were sacrificed at 4 h and at 1, 3, 7, 10, and 14 days after exposure. Histopathological examinations were conducted on the animals' upper respiratory tracts, including the nasal pathway and the conducting airway, and on the gas exchange region including the alveolar ducts, alveolar sacs, and alveoli. Diameters of fume particles varied from 0.02 to 0.81 microm and were distributed log normally, with a mean diameter of 0.1 microm and geometric standard deviation of 1.42. Rats exposed to the welding fume for 4 h did not show any significant respiratory system toxicity. The mean particle diameter of 0.1 microm resulted in little adsorption of the welding fume particles in the upper respiratory tract. Particle adsorption took place principally in the lower respiratory tracts, including bronchioles, alveolar ducts, alveolar sacs, and alveoli.

Administration, Inhalation↗
PubMed1997

Retrovirus-associated neoplasms of the respiratory system of sheep and goats. Ovine pulmonary carcinoma and enzootic nasal tumor.

As retrovirus-induced neoplasms of the respiratory epithelium of sheep and goats, OPC and ENT rank as economically important diseases in many countries of the world. They are also important as models of retroviral carcinogenesis of the secretory epithelium of the respiratory system. Control of both diseases is dependent on development and application of sensitive and specific assays for identification of carrier animals infected with the causative agents of these diseases. Recent progress in characterization of type D/B retroviruses associated with the diseases and development of new reagents for the immunologic or molecular detection of antiviral antibodies, viral proteins, or viral nucleic acids bodes well for improved control or prevention of these diseases.

Adenocarcinoma↗
PubMed2004

General pharmacology of DW-286a, a new fluoronaphthyridone antibiotic: effects on central nervous, cardiovascular, and respiratory systems.

DW-286a is a new class of fluoronaphthyridone antibiotic. Its effect on the central nervous system, general behavior, and cardiovascular, respiratory, and other organ systems were studied. The doses given were 30, 50, 100, 150, 300, and 1000 mg/kg and drugs were administered orally. DW-286a did not show any effects on general behavior, motor coordination, analgesic action, seizure and mortality, blood pressure and heart rate, contractile response of isolated guinea pig ileums, and renal function. On the other hand, DW-286a decreased spontaneous locomotor activity from 120 to 240 min after administration at the doses of 300 and 1000 mg/kg and the respiration rate from 30 to 240 min after the administration of doses up to 100 mg/kg. The sleeping time and body temperature were increased significantly in mice at the dose of 1000 mg/kg. DW-286a increased the charcoal transport significantly at doses of 300 and 1000 mg/kg. DW-286a inhibited gastric acid secretion, reduced the volume of the gastric juice and total acidity, and increased the pH dose dependently. Based on the above results, it was concluded that DW-286a affects spontaneous locomotor activity, respiration and body temperature, gastrointestinal transport, gastric secretory action, and hexobarbital sleeping time at high doses.

Animals↗
PubMedDate not supplied

[Prevention of risk of cross-infection through the respiratory system during anesthesia].

The authors present a modern concept of prevention of cross contamination during forced ventilation of the lungs in the course of total anesthesia and operation. The optimal complex of measures of individual protection of a patient includes hygienic measures, use of sterile respiratory systems (better disposable), obligatory use of respiratory filters between the intubation tube and T-piece of the narcosis and respiration device; hydrophobic folded membrane filters should be preferred. Studies carried out at Anesthesiology Department of Research Center of Surgery of Russian Academy of Medical Sciences indicate that BB 22-15 filters (Pall Corporation) reliably protect patients from cross-contamination realized through respiratory gases and biological fluids (blood, saliva, condensate) and save heat and humor. Hydrophobic folded membrane filter BB 22-15 is highly effective, which recommends it for wide use.

Adult↗
PubMed1996

[Respiratory system involvement in pseudotuberculosis].

Clinical, microbiological, x-ray and immunological examinations of 1376 patients with pseudotuberculosis and 465 patients with acute respiratory diseases of viral or coccal origin, the trends in annual morbidity for the above diseases followed up within 7 years in the populations where the patients were registered and experimental investigations on rabbits provided evidence for primarily generalized pattern of pseudotuberculosis infection and a direct relationship between pulmonary lesions in the animals and effective dose of the infectant, route of the infection. The patients had nonspecific (non-yersiniosis) lesions of the respiratory system. Frequency of the infection was greater in cold seasons, especially in those who did not complete social and biological adaptation to new conditions, and depended on seasonal fluctuations of respiratory infection morbidity in nonrandom populations.

Acute Disease↗
PubMed2000

[The respiratory system].

Explore the source record for details and available documents.

Diagnostic Techniques, Respiratory System↗
PubMed1993

[Measurement of total respiratory system compliance of infants and small children].

With the constant-flow method (Pulse method) and the standard method total respiratory system compliance (CT) were measured in 54 infants and small children who were free of lung and heart diseases and received assisted ventilation under general anesthesia before operation. The results showed that CT of the infants and small children appeared to be linearly related to age. The specific total compliance of each age group was not significantly different (P > 0.05). Therefore, within the age range of infants and small children, the mean +/- s of specific total compliance could be used as normal reference value for clinical use. The CT of the two methods were significantly related (r = 0.98, P < 0.001). Pulse method was proved to be a convenient method for monitoring the changes of CT in infants and small children during ventilator treatment.

Age Factors↗
PubMed2003

How respiratory system mechanics may help in minimising ventilator-induced lung injury in ARDS patients.

The main supportive therapy in acute respiratory distress syndrome patients is mechanical ventilation. As with any therapy, mechanical ventilation has side-effects, and may induce lung injury (ventilator-induced lung injury (VILI)/ventilator-associated lung injury). The mechanical factors responsible for VILI are thought to be related to tidal recruitment/derecruitment of previously collapsed alveoli and/or pulmonary overdistension. The volume/pressure (V/P) curve of the respiratory system in patients as well as in animal models of acute lung injury (ALI) has a characteristic sigmoid shape, with a lower inflection point (LIP) corresponding to the pressure/end-expiratory volume required to initiate recruitment of collapsed alveoli, and an upper inflection point (UIP) corresponding to the pressure/end inspiratory volume at which alveolar overdistension occurs. "Protective" ventilatory approaches have therefore set out to minimise mechanical injury by using the V/P curve to individualise positive end-expiratory pressure (PEEP) (PEEP above the LIP) and tidal volume (by setting end-inspiratory V/P below the UIP) since a large number of experimental studies correlate P/V curves to histological and biological manifestations of VILI and two randomised trials showed that protective ventilatory strategy individually tailored to the P/V curve minimised pulmonary and systemic inflammation and decreased mortality in patients with ALI. However, despite the fact that several studies have: 1) proposed new techniques to perform pressure/volume curves at the bedside, 2) confirmed that the lower inflection point and upper inflection point correspond to computed tomography scan evidence of atelectasis and overdistension, and 3) demonstrated the ability of the pressure/volume curve to estimate alveolar recruitment with positive end-expiratory pressure, no large studies have assessed whether such measurement can be performed in all intensive care units as a monitoring tool to orient ventilator therapy. Preliminary experimental and clinical studies show that the shape of the dynamic inspiratory pressure/time profile during constant flow inflation (stress index), allows prediction of a ventilatory strategy that minimises the occurrence of ventilator-induced lung injury.

Humans↗
PubMed2006

Respiratory system of Gluconacetobacter diazotrophicus PAL5. Evidence for a cyanide-sensitive cytochrome bb and cyanide-resistant cytochrome ba quinol oxidases.

In highly aerobic environments, Gluconacetobacter diazotrophicus uses a respiratory protection mechanism to preserve nitrogenase activity from deleterious oxygen. Here, the respiratory system was examined in order to ascertain the nature of the respiratory components, mainly of the cyanide sensitive and resistant pathways. The membranes of G. diazotrophicus contain Q(10), Q(9) and PQQ in a 13:1:6.6 molar ratios. UV(360 nm) photoinactivation indicated that ubiquinone is the electron acceptor for the dehydrogenases of the outer and inner faces of the membrane. Strong inhibition by rotenone and capsaicin and resistance to flavone indicated that NADH-quinone oxidoreductase is a NDH-1 type enzyme. KCN-titration revealed the presence of at least two terminal oxidases that were highly sensitive and resistant to the inhibitor. Tetrachorohydroquinol was preferentially oxidized by the KCN-sensitive oxidase. Neither the quinoprotein alcohol dehydrogenase nor its associated cytochromes c were instrumental components of the cyanide resistant pathway. CO-difference spectrum and photodissociation of heme-CO compounds suggested the presence of cytochromes b-CO and a(1)-CO adducts. Air-oxidation of cytochrome b (432 nm) was arrested by concentrations of KCN lower than 25 microM while cytochrome a(1) (442 nm) was not affected. A KCN-sensitive (I(50)=5 microM) cytochrome bb and a KCN-resistant (I(50)=450 microM) cytochrome ba quinol oxidases were separated by ion exchange chromatography.

Bacterial Proteins↗