Circadian variations in minute ventilation can be reproduced by a pacemaker sensor.

Special software allowing the memorization of 24-hour minute ventilation can be loaded into the memory of the Chorus RM, a DDDR pacemaker driven by minute ventilation. This feature was tested in the postimplant period in 13 patients. Measurements of minute ventilation, respiratory rate, and respiratory amplitude were analyzed according to prospectively defined diurnal and nocturnal time periods. Minute ventilation decreased by 39% (P < 0.001) from the diurnal to the nocturnal phase, while respiratory rate and amplitude decreased by 18% and 28%, respectively (P < 0.001 each). Thus, minute ventilation allowed discrimination between sleep and waking hours. This information could be utilized to modulate the backup rate of the pacemaker.

Relationship between heart rate and minute ventilation, tidal volume and respiratory rate during brief and low level exercise.

The correlation between heart rate (HR) and three respiratory parameters, minute ventilation (VE), tidal volume (Vt), and respiratory rate (RR), were studied. Four healthy subjects performed four exercise tests (duration 30 seconds at 50, 100, 150, or 200 W), in random order. Cardio-respiratory parameters were recorded respiratory cycle by respiratory cycle. The results of these low level exercise tests showed that oxygen consumption (VO2) was strongly correlated with VE (r = 0.91 +/- 0.10; P less than 0.01) (except in one test) and Vt (r = 0.91 +/- 0.07; P less than 0.001) (except in one test). There was no significant correlation between VO2 and RR. At exercise onset HR, VE, and Vt were modified in a matter of a few heart beats while RR varied depending on the subject and the level of exercise. During exercise average HR, VE, and Vt were significantly higher than at rest in most cases; but RR was not significantly changed by exercise. The correlations between HR and VE, Vt and RR varied from one individual to another. Nevertheless, the correlation coefficients were positive for VE and Vt, while they were negative for RR. Sensing respiratory rate thus appears to be insufficient for responsive pacing at exercise onset, but sensing respiratory volumes (Vt, VE) should give satisfactory results.

Increased content of neutrosoluble collagen and dialyzable hydroxyproline in panacinar emphysema and spontaneous pneumothorax.

Hydroxyproline transfer to an incubation medium was studied in ten emphysematous, nine relapsing pneumothorax, and eight control samples surgically removed from 2 females and 25 males, ranging in age from 17 to 69 years. Total hydroxyproline in the lung pieces, expressed as a fraction of DNA, was not modified. A large increase of dialyzable and nondialyzable hydroxyproline fraction was observed in the incubation medium of biopsies from emphysema dn pneumothorax groups. Although the pneumothorax group had average values between controls and emphysema, some pneumothorax patients exhibited very high content of soluble hydroxyproline, suggesting a common pattern between some relapsing pneumothorax and emphysema. These findings could not be due to extracellular degradation during the processing of the samples since the results were not affected by the presence of protease inhibitors. These observations suggest that individuals with emphysema and pneumothrax have abnormalities in lung collagen structure and/or biosynthesis resulting in increased degradation of this macromolecule.

SO2-induced bronchopathy in the rat: abnormal permeability of the bronchial epithelium in vivo and in vitro after anatomic recovery.

The effects of different SO2 exposures on the uptake and transport of exogenous proteins by the tracheobronchial epithelium were investigated in vivo and in vitro using explanted tissue from rat lungs. By optical and electron microscopy, modifications in ferritin uptake and transport were observed, depending on SO2 exposure and on subsequent structural changes; these changes involved a considerable increase in mucosal permeability, both in vivo and in vitro, affecting the epithelium of the trachea and main bronchi. Such an increase, although reduced, was observed 3 months after SO2 exposure had been discontinued, at a time when the structure appeared normal. These findings suggested that SO2-induced changes in upper respiratory epithelium may be responsible for long-term abnormal permeability and that such changes may contribute to the pathogenesis of chronic bronchopathy.

Biochemical and anatomical study of collagen and associated macromolecules in pulmonary panacinar emphysema and spontaneous pneumothorax.

In collagen content of four emphysematous lungs as defined by radiological, physiological and anatomical tests were studied. They were compared to three control lungs and five lungs removed from patients with relapsing pneumothorax (PNO). Morphologically, emphysematous lungs were characterized by patchy disorganization of collagen fibers, involving microfibrillar areas or elastoid laminae. Elastic fibers were at times found in plugs. Such abnormalities were also present, but less frequently in the PNO group. Biochemically, emphysematous lungs showed an increase of soluble proteins removed by CaCl2 extraction, which were associated with a decrease in insoluble proteins in extracted by TCA. Total hydroxyproline, expressed as a fraction of deoxyribonucleic acid (DNA) content, was not modified, but an increase of dialyzable and undialyzable fraction was observed in MEM medium. The PNO group showed the same modifications in terms of mean values, but individual results were more scattered. Results of in vitro 14C-proline incorporation did not show any modification of collagen biosynthesis, except in 2 emphysematous lungs. The results indicate that the PNO group is nearer to the emphysematous group than the controls. This suggests that patients with relapsing PNO may develop emphysema but it has to be further substantiated. The results here presented indicate that soluble hydroxyproline is an index either of abnormal synthesis or of excessive collagenolysis.

[Experimental study of extra-corporeal circulation with membrane oxygenators: effects on the lung structures of dogs and monkeys (author's transl)]. / Etude expérimentale de la circulation extra-corporelle avec oxygénateurs à membrane. Effets sur les structures pulmonaires du chien et du singe.

Six dogs and 5 monkeys underwent extra-corporeal circulations with membrane oxygenators for variable time periods (from 4 to 57 hours). The development and evolution of the lesions, which were similar in the two animal species, were controlled by electron microscopic examination of lung samples. From the 2nd h, abnormalities of the capillary endothelium were observed; but a 6 h, all the inner lung structures were reached and the lesions grew worse with time. Thus, the intrinsic toxicity of membrane oxygenators on lung structures emphasizes that this method should be used with utmost precaution in man.

Experimental modifications induced by membrane oxygenators on lung ultrastructure in dogs and baboons.

Extracorporeal circulation with membrane oxygenator (E.C.M.O.) was performed in 6 dogs and 5 baboons during 4 to 57 hours. Examination of pulmonary samples showed progressive lesions in the two species: at the second hour of E.C., alteration of capillary endothelium, at the sixth, extensive lesions of all the lung structures, worsening later on. We discussed whether these lesions are related to the E.C.M.O., their reversibility and the questionable benefit of E.C.M.O. for management of respiratory distress syndrome.

[Experimental study of the effect of membrane oxygenators on the pulmonary structure of the dog and monkey (author's transl)]. / Etude expérimentale de l'effet des oxygénateurs à membrane sur les structures pulmonaires du chien et du singe.

Six dogs and 5 monkeys were subject to extracorporeal circulations with membrane oxygenators for various time periods (from 4 to 57 hours). The pulmonary samples, examined with electron microscopy, enabled us to control the appearance of lesions (similar for the two animal species) and to follow their evolution. From the second hour, abnormalities of the capillary endothelium were observed; but at the 6th hour, the lesions had already deeply affected the whole pulmonary structure and became more and more serious. This intrinsic toxicity of membrane oxygenators on the pulmonary structure should incite extreme caution in the use of this method in man.

[Abnormalities in bronchial permeability after induction of a chronic SO2 bronchopathy in rat (author's transl)]. / Anomalies de la perméabilité bronchique après induction d'une bronchopathie chronique au SO2 chez le rat.

Our aim was to study the effects of a chronic exposure to SO2 on the permeability of bronchial epithelium in the rat, in vivo and in vitro, in relation with a marker (ferritin). The anatomical lesions observed in light and electron microscopy considerably increased the passage of ferritin both in vivo and in vitro through the epithelium of trachea and primary bronchi. This increase was still found although more discrete three months after the end of exposure while the histological appearance returned to normal. Those results showed that SO2 induces in upper airways functional abnormalities persisting beyond the necessary lapse of time for the repairing of histological lesions which could therefore intervene in the pathogeny of chronic bronchopathies.

Bronchial lymphoepithelial nodules in the rat: morphologic features and uptake and transport of exogenous proteins.

Using morphologic and ultrastructural criteria, the present study in the rat was undertaken to distinguish lymphoepithelial modules from lymphoid aggregates and lymph modes, and to demonstrate the uptake and transport of ferritin and latex particles, instilled in the trachea, by the lymphoepithelium. Unlike lymph nodes or lymphoid aggregates, lymphoepithelial nodules can be distinguished by the following characteristics of the lymphoepithelium: it is flattened and devoid of goblet cells; it contains intracellular and "intercellular" vacuoles; occasional macrophage-like cells infiltrates and surrounding lymphocytes clusters can be observed. At any time, no latex particle was found inside or under the lymphoepithelium, but until 1 hour after local instillation, ferritin particles were localized close to the cilia, at the luminal surface of the epithelium, within vesicles at the surface of some cells, and in the intercellular space. Moreover, ferritin particles were consistently present on both sides of the basement membrane after 1 hour. These results suggest that lymphoepithelial nodules may be considered as original structures capable of uptake and transport across the basement membrane of certain foreign materials.

Bronchial lympho-epithelial nodules in the rat: definition and morphological characteristics in optical and electron microscopy.

Three type of structures can be distinguished among the bronchial lymphoid tissue: lymph nodes, lymphoids cells aggregates and lymphoepithelial nodules. Such structures are encountered in many species and may be characterized by flattened epithelium, devoid of mucus producing cells, infiltrated with lymphocytes and containing of few ciliated cells. The lymphoepithelium surrounds the nodules, characterized by a high cellular density. Original structures may be observed, mainly inter and intracellular vacuoles. Peripheral lymphatic vessels and high endothelium veins contribute to the important lymphocyte transfer. Electron microscope, studies support the view that lymphoepithelium has an uptake function of particulate matter; more direct evidence is however attempted. An hypothesis of capacity for antigenic recognition of the lymphoepithelium nodules is discussed.

[Bronchial lympho-epithelial nodules in the rat. Definition and morphological characteristics in optical and electron microscopy (author's transl)]. / Nodules lympho-épithéliaux bronchiques chez le rat. Définition et caractéristiques morphologiques en microscopie optique et électronique

Among the bronchial lymphoid tissue, lympho-epithelial nodules are an original component, easily distinguished from other structures, particularly from lymphoid cell infiltrates. Such structures are encountered in many species and may be characterized by a flattened epithelium, containing a few ciliated cells, devoid of mucus producing cells, and infiltrated with lymphocytes. Inter and intracellular vacuoles are described in the lympho-epithelium and the underlying mucosa. Electron microscope studies support the view that lymphoepithelium has a "trapping" function of particulate matter, more direct evidence is however attempted. Peripheral lymphatic vessels and high endothelium veins contribute to the important lymphocyte transfer. An hypothesis of capacity for antigenic recognition of the lymphoepithelial nodule is discussed.

[Ultrastructural study of pulmonary lesions caused by a membrane oxygenator. Comparison with a similar case, which had not received the same treatment]. / Etude ultrastructurale des lésions pulmonaires induites par oxygénateur à membrane. Comparaison avec un case similaire n'ayant pas bénéficié du même traitement

The authors made a preliminary study of the damage caused by membrane oxygenators. They suggest nevertheless before a completely definative interpretation to increase the number of observations and above all to check the autopsy findings by an experimental study.