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Biomedical subjects

Y Jammes

Publications and source records attributed to Y Jammes.

141 records · Page 8Linked to original sources
PubMed1975

[Comparative study of respiratory exchanging surfaces in birds and mammals].

Anatomical studies of the respiratory apparatus of birds show evidences for a gas exchanging tubular system (parabronchi and air capillaries); these exchanging structures are entirely dissociated from the ventilatory drive acting on the air sacs. A "cross-current" gas exchanging system (perpendicular disposition of air and blood capillaries) allow a good wash-out of carbon dioxide (PaCO2 lower than PECO2). The great efficiency of this lung is allowed by its very large diffusive surface (ASa) and by the high values of lung specific oxygen diffusing capacity (DO2/ASa) and of O2 extraction coefficient in inspired air. The ventilatory pattern of birds is characterized by a greater tidal volume and a smaller respiratory frequency than in mammals of same weight. Respiratory centers of birds receive afferences from lung stretch receptors, CO2-sensitive lung receptors and arterial chemoreceptors.

Animals↗
PubMedDate not supplied

Long-term exposure of adults to outdoor air pollution is associated with increased airway obstruction and higher prevalence of bronchial hyperresponsiveness.

The authors studied the association between long-term exposure (i.e., > 10 y) to outdoor air pollution and the severity of obstructive pulmonary disease and prevalence of bronchial hyperreactivity to beta2 agonists in two groups of adult patients who were of similar ages and who had similar smoking habits. The subjects lived in downtown districts or in the outer suburbs of Marseilles, the neighborhood that contained air samplers. The regions were similar with respect to sulfur dioxide levels, but levels of nitric oxides and particulate matter (10 millimeters or less) were higher in the downtown area than the suburbs. The authors assessed airway obstruction, as determined by a decrease in forced expiratory volume in 1 s, mean forced expiratory flow measured between 25% and 75% of vital capacity, and an elevated value of central airway resistance. The authors tested the changes in these variables induced by inhalation of a beta2 agonist. Baseline lung function was altered more significantly in both male and female patients who lived in downtown Marseilles than in those who resided in the suburbs, and the differences persisted regardless of the season during which the study occurred. Prevalence of bronchial hyperreactivity and symptoms of asthma (but not of rhinitis) were higher in the downtown than suburban male subjects. The results of this study suggest that an association exists between actual environmental exposure to outdoor air pollution (i.e., nitrogen oxides and/or particulate matter of 10 millimeters or less) and respiratory effects in sensitive adults represented by patients with chronic obstructive pulmonary disease or asthma.

Adult↗
PubMedDate not supplied

[Cardiovascular function in man during experimental dives at 26 ATA (helium-nitrogen-oxygen mixture)].

During two human experimental dives at 26 ATA (helium-nitrogen-oxygen gaz mixture; PIO2 = 400 mbar), the cardiac frequency (Fc) and radial arterial pulse were continuously recorded, at rest and during periods of maximal expiratory (Valsalva) or inspiratory (Müller) manoeuvres, used to increase or decrease the intrathoracic pressure, respectively. Cardiovascular variables were measured at 1 and 26 ATA in resting individuals and during the maximal respiratory manoeuvres. Discontinuous measurement of arterial blood pressure using a sphygomanometer allowed to calculate the mean arterial pressure. The value of mean arterial pressure was maintained against the membrane of a radial pulse sensor. This procedure, proposed by Posey et al. (1969), gives a continuous approximation and recording of arterial blood pressure and its components. The present results did not show significant variation in the values of Fc nor systolic or diastolic blood pressures measured at rest or during Müller manoeuvres performed at 1ATA at the maximal depth. On the other hand, Valsalva manoeuvres performed at depth induced significant variations in circulatory variables compared to the normobaric response. The most important effect was an enlargement of differential pressure due to a marked decrease in the diastolic blood pressure. These observations are discussed in terms of enlarged sensitivity of the baroreflex arch under hyperbaric condition.

Adult↗
PubMedDate not supplied

Tracheobronchial and laryngeal responses to hypercapnia, histamine and capsaicin in dogs.

In nine greyhound dogs, anaesthetized with chloralose-urethane, total lung resistance, volume of an isolated cervical tracheal segment and resistance of the isolated larynx were simultaneously measured. Three stimuli were tested: inhalation of a CO2-enriched gas mixture; histamine injected intravenously or administered by aerosol to stimulate primarily lung irritant receptors; and intravenous injection of capsaicin to stimulate primarily lung C-fibre receptors. The stimuli were applied in three successive conditions: neurally-intact animals; denervation of the right lung plus cold block of myelinated fibres in the left cervical vagus nerve; and further blockade of non-myelinated fibres in this nerve. Histamine and capsaicin increased lung and laryngeal resistances, and reduced tracheal volume, and the responses after denervation are consistent with the drugs acting by lung vagal reflexes. In neurally-intact animals, hypercapnia increased total lung resistance, decreased tracheal volume and lowered laryngeal resistance. After elimination of conduction in all myelinated fibres, CO2-induced changes in lung resistance and in tracheal volume were still present. However, the dilating effect of hypercapnia on the larynx diminished markedly. Elimination of all vagal pulmonary afferents abolished the residual laryngeal response to hypercapnia, lowered and delayed changes in tracheal volume and greatly reduced the increase in lung resistance. The results indicate that the laryngeal response to hypercapnia depends on vagal integrity, but the tracheobronchial constrictor effect of CO2 is less affected by vagal denervation.

Aerosols↗