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Biomedical subjects

H Gautier

Publications and source records attributed to H Gautier.

At least 91 records · Page 5Linked to original sources
PubMed1978

Pulmonary gas exchange, diffusing capacity in natives and newcomers at high altitude.

At high altitude, in resting conditions, no differences have been observed between High Altitude Natives (HAN) and acclimatized Sea Level Natives (SLN) in AaDO2, aADCO2 or venous admixture. In acclimatized SLN, AaDO2 is smaller than at sea level because of: (1) The minor effect on arterial oxygenation of the probably constant venous admixture. (2) The reduction of VA/Q inequality as shown by a smaller aADCO2. In HAN, DLCO is greater than in SLN; the contribution of DM or VC in this difference remains unsettled, mainly because of the difficulties of measurement of DM and VC in HAN suddenly exposed to acute hyperoxia. In SLN, in acute hypoxia, DLCO increased transitorily. Asynchronous mechanisms of adaptation to high altitude are evoked.

Acclimatization↗
PubMed1978

Gas exchanges during exercise in normoxia and hyperoxia.

Exercises of constant workload (90 watt) have been carried out during normoxia or hyperoxia FIO2 = 0.45). It has been shown that, in spite of a significant dispersion in the values of O2 deficit and O2 debt calculated, these values are related to the increased blood lactate level which contributes to the marked acidosis observed in both conditions of oxygenation. Hyperoxia reduces lactate level as well as the O2 debt. In addition to the significant increase in arterial [H+] and PCO2, exercise provokes a slight decrease in PO2. It is suggested that the significant variations of these humoral factors might contribute to the control of ventilation during exercise in both conditions of oxygenation.

Acid-Base Equilibrium↗
PubMed1978

Changes in ventilatory pattern induced by intravenous anesthetic agents in human subjects.

The tidal volume-inspiratory duration relationship was studied during air breathing and rebreathing in conscious and anesthetized human subjects using three different intravenous agents. The results observed have been compared with similar experiments carried out in cats. Its has been shown that anesthesia provokes an increase in breathing rate associated with a decrease in tidal volume in human subjects; an opposite effect on breathing rate was observed in cats. Thus, the tidal volume-inspiratory duration relationship, although very similar in the conscious cat or human subject, is very different under anesthesia. The results were quite consistent in a given species whatever the nature of the drug used. It is suggested that modifications of the breathing rate by anesthesia, related to animal species, are caused by central effects of the drug. These effects are probably mediated by different actions on inputs to the inspiratory "off-switch" mechanisms in the two species.

Alfaxalone Alfadolone Mixture↗
PubMed1977

Treatment of malignant gliomas and brain metastases in adults using a combination of adriamycine, VM 26, and CCNU. Results of a type II trial.

Forty-three patients with inoperable and/or recurring malignant gliomas and 30 patients with multiple recurring brain metastases were treated with a combination of adriamycine (45 mg/m 2 and 4-dimethyl-epipodophyllotoxin D-thenylidene (VM 26) (60 mg/m 2 for 2 days) and 1-(2-chloroethyl)-3-cyclohexyl-1-nitroso-urea (CCNU) (60 mg/m 2 for 2 days). These cycles of treatment were repeated as soon as the hematologic restoration was complete. The treatment was well-tolerated and the clinical condition of 31 out of 43 glioblastoma patients improved during the 2 months after the beginning of the treatment. Six out of eight patients with breast cancer metastases, one out of 13 with bronchial cancer metastases, and three out of nine with other types of cancer metastases also benefitted from the treatment. Examination of the results reveals the following characteristics: 1. A low degree of efficiency of this combination in the treatment of brain metastases, except for breast cancer metastases. 2. Absence of complete correlation between the clinical results observed and the cinegammagraphic developments 3. Similarity of the results independent of the initial localization 4. Establishment of a 6-month median survival period, with ten patients at present in a state of apparently complete remission, 180-506 days after beginning of the treatment.

Adult↗
PubMed1976

[Combination chemotherapy in the treatment of polymetastic breast cancer. Comparison of therapeutic effects of 2 methods of sequential drug administration. Role of adriamycin in these combinations].

One thousand and twenty four patients with disseminated breast cancer were submitted to combination chemotherapy. Fifty one patients (group I) were sequentially given VCR, CPM and 5 FU, and seventy three patients (group II) were given ADM, VCR, CPM and 5 FU. The general and haematological tolerance was good and comparable in the both groups of patients: we observed only two severe infectious complications. Bonemarrow hypoplasia, six myocardial ischemia (two of them were lethal) in each group of patients, without any predominance in the group of patients treated with adriamycin. The percentage of objective regression in both groups was respectively: 72% and 71%. The mean duration of response was eight months. The median survival time was 420 days for patients of group I; for patients of group II the median is not obtained at 480 days. This study confirms that responders to chemotherapy significantly increase the mean duration of survival time. However, in this group of responders the presence of the liver metastases is worse prognosis than all other visceral metastases.

Adenocarcinoma↗
PubMed1976

[Trial treatment of glioblastomas in adults and cerebral metastais by adriamycin, VM 26 and CCNU combination. Result of a type II trial].

Forty-three patients with inoperable and/or recurring malignant gliomas, and 30 patients with multiple recurring brain metastases were treated with a combination of adriamycine (45 mg/m2) and 4-dimethyl-epipodophyllotoxin D-thenylidene (VM 26) (60 mg/m2 for 2 days) with 1-(2-chloroethyl) -3-cyclohexyl-1-nitroso-urea (CCNU) (60 mg/m2 for two days). These cycles of treatment were repeated as soon as the hematological restoration was complete. The treatment was well tolerated and the clinical condition of 31 out of 43 glioblastoma patients improved during the two months after the beginning of the treatment. Six out of eight patients with breast cancer metastases, one out of 13 with bronchial cancer metastases and three out of nine with other types of cancer metastases also benefitted from the treatment. Examination of the results obtained reveals the following characteristics: -A low degree of efficiency of the combination in the treatment of brain metastases, except for breast cancer metastases. -Absence of complete correlation between the clinical results observed and the cinegammagraphic developments. -Similarity of the results independent of the initial localization. -Establishment of a six-months median survival period, with ten patients at present in a state of apparently complete remission, 180 to 506 days after beginning of the treatment.

Adult↗
PubMed1976

Pattern of breathing during hypoxia or hypercapnia of the awake or anesthetized cat.

The breathing patterns during hypoxia and hypercapnia are similar in anesthetized cats but are qualitatively different in awake cats. The differences seen in the awake animals can be explained by either the central depressive effect of hypoxia or by a specific effect of hypercapnia on supra-pontine structures. The Breuer-Hering reflex sensitivity, i.e. the VT-TI relationship, appears, in the awake cat, quite similar to that recently described in man. The inspiratory activity is shown to be controlled by mechanisms dependent on the nature of the respiratory stimulation. The recent model proposed for the control of inspiration during anesthesia must be modified to account for the results observed in awake animal.

Anesthesia↗
PubMed1976

Servo respirator constructed from a positive-pressure ventilator.

We have constructed an electronically controlled respirator from three commercially available components: a positive-pressure ventilator, a recorder pen motor, and a differential amplifier. Using negative feedback derived from a tracheal pressure signal, the instrument functions as a servo respirator which provides precise control of tracheal pressure. The system's power and response characteristics are well suited for ventilation of anesthetized cats and dogs. The servo respirator can be used as an externally controlled respiratory pump which provides flexibility in selection of the parameters of the ventilatory cycle. Alternatively, it can function as a "demand" respirator which generates transthoracic pressure proportional to efferent respiratory discharge.

Electronics↗
PubMed1976

Interaction of pulmonary afferents and pneumotaxic center in control of respiratory pattern in cats.

The interaction between the pulmonary afferents (PA) and the pneumotaxic center (PC) in control of respiratory pattern was studied in lightly anesthetized paralyzed cats before and after bivagotomy or lesions of the PC using inflations controlled by the onset or cessation of phrenic nerve discharge, i.e., cycle-triggered inflations. This interaction was also studied using electrical stimulation of the central stumps of cut vagi. Introduction of a delay between inspiratory onset and the commencement of an inflation at constant flow and duration resulted in increases of the durations of inspiration (T1) and expiration (TE) and amplitude of the integrated phrenic nerve discharge (A). The lung volume at inspiratory cutoff, i.e., the volume threshold, increased markedly as T1 increased. There were linear relationships between T1 and TE and between T1 and A. At constant alveolar CO2 and tidal volume, the quantitative effects of delay were dependent on the rate of inflation; i.e., when the flow increased, the volume threshold for a given T1 decreased. Bilateral vagotomy abolished the effects of delay and flow. PC lesions, which resulted in apneusis when the cycle-triggered inflations were stopped, produced the following changes compared to the delay effects seen in intact cats: a) the volume threshold for zero delay doubled and its rate of decrease with increased T1 was significantly smaller, and b) the change in TE for a given change in T1 was reduced markedly. Introduction of a delay between inspiratory onset and the start of electrical stimulation of the afferent vagi resulted in effects similar to those seen for delays in cycle-triggered inflations. The T1-TE relationship remained linear when the stimulus trains ended with inspiratory cessation. These results suggest that: a) the inspiratory cutoff mechanism is responsive to the rate, as well as the level, of lung inflation; b) all of the lung volume information affecting inspiratory cutoff in paralyzed cats is carried via the vagi; c) an intact PC is necessary for the generation of a normal time dependence of the volume threshold for inspiratory cutoff; d) the PC plays an important role in matching TE to T1 when the latter changes. For inflations and vagal stimulations applied during expiration, with introduction of a delay between inspiratory cessation and the start of cycle-triggered inflation or vagal stimulation, the results indicated that the expiratory cutoff mechanism has an irrevocable phase of 300-450 ms.

Animals↗
PubMed1975

Breath holding and rebreathing at low and high altitude.

Breath holding and rebreathing have been carried out at sea level in lowlanders and at high altitude in acclimatized lowlanders and in highlanders. It has been shown that the values of gasping time, breath-holding time, rebreathing time and the composition of the alveolar gases at the breaking point are modified by chronic hypoxia, especially in highlanders. The modifications observed can be explained by different sensitivities to humoral stimuli of the different groups of subjects. The importance of nonhumoral factors, as studied by comparing apnea and rebreathing, seems modified at altitude, especially in highlanders, although the mechanism of this change is unknown.

Acclimatization↗
PubMed1975

Respiratory effects of pneumotaxic center lesions and subsequent vagotomy in chronic cats.

Ventilation was monitored in awake and anesthetized cats breathing air or CO2 mixtures, both before and after lesions in the pneumotaxic center region and after subsequent bilateral vagotomy. Cats with pontile lesions had, relative to intact state, a prolonged inspiratory duration and an increase in tidal volume and expiration duration. The changes seen on the spirogram differed quantitatively according to the region of the pneumotaxic system which was destroyed. After subsequent bilateral vagotomy, respiratory phases and tidal volume were greatly increased. These results indicate that the pneumotaxic center would control the sensitivity of Breuer-Hering reflex and that the inspiratory activity is released by the successive suppression of the two inspiratory-inhibitory mechanisms, i.e., the pneumotaxic center and the vagal pulmonary afferents.

Animals↗