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Biomedical subjects

H Gautier

Publications and source records attributed to H Gautier.

At least 73 records · Page 4Linked to original sources
PubMed1981

Gas exchange during bicycle exercises preceded or not by loadless pedalling in female and male subjects.

The effects on ventilation and oxygen uptake of pedalling with no load on the ergometer before exercise have been investigated in 10 subjects (6 males and 4 females). It has been found that: (1) the O2-deficit calculated at the beginning of exercise is less variable and generally reduced when exercise has been preceded by a loadless pedalling period; (2) for a given steady-state VO2, the O2-deficit is larger in female than in male subjects; (3) the respiratory equivalents for oxygen and for carbon dioxide are not affected by loadless pedalling; they are generally larger in female than in male subjects; (4) the increase in ventilation at the beginning of exercise is smaller after loadless pedalling but this seems to be apparent only in male subjects; (5) the pattern of breathing and heart rate are not affected by loadless pedalling. It is concluded that pedalling with no load on the ergometer before the exercise prepares the subject to deliver oxygen more rapidly to the muscles. It then reduces the variability in gas exchanges and the O2-deficit. Several factors which may account for this better efficiency of oxygen delivery are discussed.

Adult↗
PubMed1981

Phrenic activity, respiratory pressures, and volume changes in cats.

In eight anesthetized cats we measured the integrated ("moving time average") phrenic activity [using phrenic electroneurogram (EPHR)] and the active transdiaphragmatic pressure [Pdi(mus)] during room air breathing, hypoxia, and hypercapnia. The relationship between Pdi(mus) and EPHR was unaffected by either hypoxic or hypercapnic stimulation of breathing, suggesting that in spontaneously breathing cats the pressure losses are negligible. In all cats, however, there was a substantial volume-related decrease in Pdi(mus), indicating that with increasing lung volume the effectiveness of the diaphragm as a pressure generator decreases. In addition, we have developed a model that allows prediction of the time course changes in lung volume for different morphology of inspiratory driving pressure. This model explains many of the features of control of breathing found experimentally in our cats.

Animals↗
PubMed1981

Time course of phrenic activity and respiratory pressures during airway occlusion in cats.

The morphology of integrated ("moving time average") phrenic electroneurograms (EPHR) and of tracheal (Ptr) and transdiaphragmatic (Pdi) pressure waves during occluded inspirations was studied in eight anesthetized cats breathing air and various hypercapnic and hypoxic mixtures. The shape of the rising part of EPR-, Ptr-, and Pdi-time profiles varied between animals (from convex to concave), but in each animal it remained virtually unchanged by hypoxia and hypercapnia. The shape of the Ptr and Pdi occlusion waves reflected the shape of EPHR. The relationship of EPHR to Pdi and Ptr did not change with chemical drive. It is concluded that central inspiratory activity (CIA) (as reflected by EPHR and its mechanical transforms Pdi and Ptr) increases in amplitude with stimulation of breathing but that the profile of CIA remains essentially unchanged. However, substantial differences in the time course development of phrenic activity, Pdi, and Ptr exist between cats. The fixed interrelationships among EPHR, Pdi, and Ptr indicate a proportional increase in activity among all inspiratory muscles with increased chemical drive.

Airway Obstruction↗
PubMed1981

Breuer-Hering inflation reflex and breathing pattern in anesthetized humans and cats.

In nine cats and nine human subjects anesthetized with alfaxalone, respiratory activity and tracheal pressure were recorded prior to and during occlusion of the airway at end inspiration or end expiration. Lung inflations at the end of expiration were also performed. In addition, the ventilatory pattern was analyzed during hypercapnia. The results show that occlusions at the end of inspiration or inflations provoked an apnea in both cats and humans. However, concomitant with increases in tidal volume during hypercapnia, inspiratory duration decreased in cats and did not change in human subjects. These results indicate that the Breuer-Hering reflex, which delays the onset of inspiration during inflation was equally operative in cats and humans. In contrast, the "Breuer-Hering threshold curve," which accounts for the off-switch" of inspiration was different in cats and humans. Thus, in summary, the Breuer-Hering inflation reflex is operative in human subjects, but it does not seem to be involved in the control of the inspiratory off-switch mechanism during increases respiratory activity resulting from hypercapnia.

Adult↗
PubMed1980

Pattern of breathing and mouth occlusion pressure during acclimatization to high altitude.

Pattern of breathing and mouth occlusion pressure have been investigated during a 6-day sojourn at an altitude of 3457 m in six resting subjects breathing ambient air or an hyperoxic mixture. It has been shown that ventilation increases and alveolar PCO2 decreases, both variables reaching a steady-state after about 4 days at altitude. Changes in ventilation are caused by modifications, at first, in the timing component of the respiratory cycle and later on, in the mean inspiratory airflow. This suggests that the output of the respiratory center is qualitatively modified during the acclimatization period. Mouth occlusion pressure, an index of neuromuscular inspiratory drive, increased on the first day at altitude, remaining constant thereafter. The mean inspiratory flow did not change on the first day, but progressively increased in the subsequent 3 days. The observation that flow increased in the face of a constant neuromuscular inspiratory drive suggests that during acclimatization to altitudes, the progressive increase in ventilation is due to changes in mechanics of the ventilatory pump rather than changes in central neural drive.

Acclimatization↗
PubMed1980

Possible alterations in brain monoamine metabolism during hypoxia-induced tachypnea in cats.

In carotid body-denervated cats, moderate hypoxia, or even normoxia when compared to hyperoxia, provokes a significant depression of the respiratory output. This is observed in conscious or anesthetized or decerebrated animals. On the other hand, more severe hypoxia induces tachypnea (hypoxic tachypnea of Miller and Tenney, Respir. Physiol. 23: 31-39, 1975) in conscious cats, whereas the same hypoxia is followed by marked respiratory depression or apnea in the anesthetized or decerebrated animals. Hypoxic tachypnea can be partly or completely reversed by injection of dopa or xanthines such as caffeine or aminophylline. This suggests that alterations in brain monoamine metabolism by hypoxia may be responsible for the alterations in suprapontine respiratory control systems, resulting the tachypnea. Mild hypercapnia can also reverse hypoxic tachypnea. It is concluded that the ventilatory response to hypoxia of conscious animals results from stimulation of peripheral chemoreceptors, inhibition of brain stem neurons, and finally involvement of suprapontine structures that seems to be mediated by depletion of monoamines.

Aminophylline↗
PubMed1980

[Vagus nerves and pulmonary artery pressure in the conscious and anesthetized cats using different levels of oxygenation (author's transl)].

Pulmonary artery pressure (PAP systolic and diastolic) and heart rate (HR) have been recorded in conscious or anesthetized cats. Experiments have been carried out before and after bilateral vagotomy or section of vagal afferents at the level of the nodose ganglion. Animals were exposed to different levels of oxygenation using FIO2 from 0.11 to 1.00. The results show that: 1 Anesthesia with sodium pentobarbital did not affect PAP for a given level of FIO2 : changes in PAP caused by modifications of FIO2 were not affected by anesthesia. Heart rate was independent of FIO2, but remained always higher in the anesthetized animals (Fig. 4). 2 In anesthetized animals, pulmonary de-afferentation or vagotomy affected neither PAP, nor its variations with FIO2 nor HR (Fig. 5). 3 In conscious animals, PAP and its variations with FIO2 were not affected by vagotomy (Fig. 6 and 7) or pulmonary de-afferentation (Fig. 8). On the other hand, heart rate was always decreased after either vagotomy or pulmonary deafferentation. It is concluded that (1) PAP and its control by FIO2 are independent of the vagal innervation; (2) the pulmonary edema observed after vagotomy cannot be caused by an increase in lung vascular pressure; (3) anesthesia, on the one hand, and pulmonary afferents, on the other hand, can play a role in the control of the cardiovascular activity.

Anesthesia, General↗
PubMed1979

Effects of carotid body denervation on respiratory pattern of awake cats.

Eight awake cats have been studied before and after carotid denervation during air and oxygen breathing, and during hypercapnia. Analysis of the variables that characterize the spirogram shows that carotid denervation consistently results in a decrease of the mean inspiratory flow (VT/TI), causing a decrease in tidal volume (VT) and ventilation with a relative alveolar hypercapnia. In carotid-denervated animals, inhalation of oxygen results in an increase in ventilation due to an augmentation of VT/TI and VT and a relative hypocapnia. TI does not significantly change in the different conditions whereas TE is significantly affected. TE seems therefore to be more closely related to the rate of rise of inspiratory activity than to inspiratory duration.

Animals↗
PubMed1978

[Non resectable colonic cancer. Results from a test of chemotherapy with simultaneous prescription of VM26, methyl-CCNU and 5 fluoro-uracile (author's transl)].

Thirty nine patients with non resectable colonic carcinoma entered into a phase II combination chemotherapy trial. The patients were treated with a sequential cyclic combination of 3 drugs: VM 26 (60 mg/m2), methyl-C.C.N.U. (120 mg/m2) and 5 fluoro-uracile. Seventeen patients out of 39 (43.6%) are considered as good responders. The median survival time of the overall of this group is 12.6 months; it is of 15,6 months for good responders and of 7 months for non responders. The simultaneous application of B.C.G. do not change neither the level of responses nor the median of survival time. The good tolerance of this protocol let us to propose this combination as an adjuvant treatment for patients surgically treated for a Dukes'C colonic cancer.

Adult↗
PubMed1978

[Non resectable squamous cell carcinoma of the bronchus. Study of the immunological status as prognosis factor and attempt at immunorestoration with B.C.G. (author's transl)].

Sixty-six patients with bronchus non resectable squamous cell carcinoma (stage III and 14) entered into a protocol of chemotherapy depending upon their initial immunological status. These patients with (+) skin tests to recall antigens were allocated to a chemotherapy programme; patients with initially (-) skin tests were submitted to a protocol of immunorestauration with B.C.G. After three weeks of B.C.G. applications on scarifications 17 patients out of 31 presented with (+) skin tests and were considered as immunocompetent patients. All the patients then were submitted to chemotherapy protocol. The comparison of different median of survival have demonstrated that immune status appears as the more fundamental prognosis factor; the B.C.G. is able to transitory restore the immunity of the patients without any modification of the tumour progress. The median of survival of patients with initially (+) skin tests was ten months, and only two months for patients with (-) skin tests. The median of survival of patients whom immunity was restored with B.C.G. was nine months. The results of this trial let us to propose new strategy for treatment of these patients.

Adult↗