Search PubMed⌕ Search

Biomedical subjects

C Saunier

Publications and source records attributed to C Saunier.

At least 37 records · Page 2Linked to original sources
PubMed1991

Effects of cilazapril, a novel angiotensin converting enzyme inhibitor, on the structure of pulmonary arteries of rats exposed to chronic hypoxia.

Chronic hypoxia is known to be associated with a thickening of the media of pulmonary arteries. The goal of the present study was to assess if cilazapril, a novel long-acting angiotensin converting enzyme (ACE) inhibitor, could prevent this thickening. For this purpose, three groups of rats were studied. One group was kept in normal room air. Two other groups were exposed to chronic hypoxia (inspired fraction of oxygen equal to 8% during 4 weeks). One group of hypoxic rats was treated with placebo and the other group received cilazapril (as food admixture of approximately 3 mg/kg/day). After 4 weeks, rats were anesthetized and pulmonary artery pressure and hematocrit measured. Then, the lungs were perfused and fixed and morphometry of the pulmonary arteries was performed. Hypoxia induced an increase in pulmonary artery pressure and hematocrit associated with a dramatic increase in the thickness of the media of the pulmonary arteries. Cilazapril completely prevented the thickening of the media of the pulmonary arteries but did not significantly decrease the pulmonary artery pressure or right ventricular weight.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1991

Preserved CO2 response in cerebral and muscular blood vessels during cimetidine treatment.

It is known that cimetidine inhibits the hypoxia-induced increase in cerebral blood flow (CFB) in dogs, but the mechanism of this inhibition is not fully understood. Since the accepted mechanisms explaining the increase in CBF during hypercapnia are very different from those active during hypoxia, acute hypercapnia was induced in 12 conscious dogs in order to study the cimetidine effect in this condition. Six dogs were given i.v. saline (control group) and the other six, i.v. cimetidine (4 mg kg-1). After 15 min, CBF and various muscular blood flow measurements were performed, using the microspheres technique under two conditions: (1) breathing air and (2) after 2 h inhalation of a gas mixture with FiCO2 0.10, FiO2 0.21 in nitrogen. The CBF increase was similar in both series with or without cimetidine. The changes in muscular blood flow were unaffected by the H2-blocker. We conclude that cimetidine has no effect on the CBF and on muscular blood flow during acute hypercapnia.

Animals↗
PubMed1991

Effects of H2-receptor blockers on response of cerebral blood flow to normocapnic hypoxia.

Cimetidine blunts the increase in cerebral blood flow (CBF) normally observed during hypoxia. It is important, therefore, to know whether other H2-blockers also affect the cerebral circulation adaptation to hypoxia. Cerebral blood flow was measured in 24 awake dogs after an intravenous injection of either saline (control) or one of three H2-blockers: 1 mg/kg ranitidine, 0.4 mg/kg famotidine, or 1 mg/kg roxatidine. These doses are equipotent blockers of H2-gastric receptors. Each dog was studied during normoxia and after 2 and 4 h of normocapnic hypoxia (FIO2, 0.10; FICO2, 0.035). During each set of experimental conditions, a bolus of either saline or one of the anti-H2 drugs was administered, and, 15 min later, radiolabeled microspheres (ruthenium 103, scandium 46, and cerium 141) were injected into the left atrium for measurement of regional CBF. After death by an overdose of thiopental, each dog's brain was excised and fixed in 10% formaldehyde; it was then weighed and dissected by region, with the radioactivity measured in each region using a gamma counter. During hypoxia, PaO2 ranged from 45 to 50 mm Hg, and pH, PaCO2, and hematocrit were within the normal limits. In the control group CBF increased 34% above normoxic baseline levels after 2 h and 31% after 4 h of hypoxia. Ranitidine (1 mg/kg) did not prevent the increase in CBF during hypoxia, but famotidine and roxatidine prevented it. When the dose of ranitidine was doubled (2 mg/kg), it too abolished the increase of CBF induced by hypoxia. In conclusion, H2-receptor blockers could interfere with the adaptation of CBF during hypoxia.

Animals↗
PubMed1991

Prevalence of antibodies to HTLV-1 in South American Indians (Mapuches) from Chile.

The seroprevalence of HTLV-1 antibodies was investigated in 405 serum samples from healthy South American Indians (Mapuches) from Chile, using enzyme linked immunoassay (ELISA), Western immunoblot (WB) and radioimmuno precipitation assay (RIPA). Six samples were positive by ELISA; 3 of them were confirmed by WB/RIPA. Thus, we observed a seroprevalence of 0.7% for HTLV-1 antibodies in healthy Mapuches.

Blotting, Western↗
PubMed1991

Accuracy and precision of fourteen pulse oximeters.

Two sets of seven pulse oximeters (Criticare CSI-502; Nellcor-N200; Datex-Satlite; Physio-Control-Lifestat 1600; Critikon-Oxyshuttle; Ohmeda-Biox 3700; Ohmeda-Biox 3740; Radiometer-Oxi; Spectramed-Pulsat; Kontron-7840; Biochem-Ox2000; Invivo-4500; Engström-EOS; Novametrix-505) were studied in two groups of eight healthy subjects, aged 26-50 yrs. The transcutaneous oxygen saturation (SpO2) was compared with arterial oxygen saturation (SaO2) measured in simultaneously with drawn blood samples (OSM2 Radiometer) at four 20 min steady-state levels of inspired oxygen fraction (FIO2) (0.21, 0.10, 0.08 and 0.07; SaO2 99-55%) in a conditioned chamber. Both the error in accuracy (mean SpO2-SaO2 difference), and the error in precision (SD of the differences) remained less than 3% for the two highest FIO2 levels (SaO2 greater than 83%) but, during deeper hypoxia, they were increased to 8% and 5%, respectively. An instrumental systematic bias affected accuracy in particular. We concluded that a good agreement between SpO2 and SaO2, as reflected by the Bartko's intraclass coefficient, was observed in nine instruments.

Adult↗
PubMed1990

The inotropic effect of digoxin on an isolated rat heart in hypercapnia and (or) hypoxia.

The explanation for the increased frequency of troubles with digoxin therapy in patients with chronic pulmonary diseases is debated. The reported effects of hypoxia in vivo on myocardial levels of digoxin are contradictory, and there have been few studies on the effects of hypercapnia. In the past, it has been shown in rat myocardial tissue at rest in vitro that hypoxia decreased and hypercapnic acidosis increased the digoxin uptake. We performed a new study in vitro in an isolated beating rat heart perfused at constant flow (37 degrees C) and stimulated at a constant frequency (6 Hz). The performances were recorded with an intraventricular balloon equipped with a tip-manometer catheter. The action of digoxin was studied by recording systolic pressure (PS) and diastolic pressure (PD), the left ventricular developed pressure (LVDP = PS - PD), the (dP/dt)max, and the ratio (dP/dt)max/PS. First, the heart was perfused for 30 min with a modified Tyrode's solution perfusate aerated with carbogen (pH = 7.40; PCO2 = 37 mmHg; PO2 = 530 mmHg) (1 mmHg = 133.32 Pa). Various parameters of contractions were recorded (initial control values). Then the heart was perfused for 15 min with Tyrode's solution aerated either with a hypoxic gas mixture (pH = 7.41; PCO2 = 36 mmHg; PO2 = 122 mmHg), a hypercapnic gas mixture (pH = 7.08; PCO2 75 mmHg; PO2 = 485 mmHg), or a hypoxic-hypercapnic gas mixture (pH = 7.09; PCO2 = 73 mmHg; PO2 = 124 mmHg). Control hearts were continuously perfused with Tyrode's solution aerated with carbogen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[HTLV-1 in a Mapuche population].

The seroprevalence of HTLV-1 in 405 serum samples from South American Indians, Mapuches, from the IXth region of Chile was investigated using enzyme linked immunosorbent assay (ELISA). Six samples were positive and only 3 of them were also positive by western blot and radio immuno precipitation assay. This corresponds to a seroprevalence of 0.74% for HTLV-1 in healthy Mapuches, which differs from that observed in other populations throughout the world. Additional studies are necessary to evaluate the real magnitudes of HTLV-1 infection in Chile.

Adult↗
PubMed1989

Effects of hypoxia and hypercapnia on atrial natriuretic factor and plasma renin activity in conscious dogs.

1. The aim of the present study was to assess the effects of hypercapnia or hypoxia on plasma concentrations of atrial natriuretic factor (ANF) in conscious unrestrained dogs. 2. For this purpose, chronically instrumented dogs were exposed in a random order to either room air, or to an atmosphere containing 21% O2/10% CO2/69% N2 to produce hypercapnia, or 10% O2/3% CO2/87% N2 to produce hypoxia without respiratory alkalosis. 3. Plasma concentrations of ANF did not change significantly during hypoxia. 4. In contrast, during hypercapnia, plasma concentrations of ANF increased by more than 100% and returned to baseline at the end of hypercapnia. 5. Hypercapnia, but not hypoxia, induced an increase in left atrial and central venous pressures. 6. We conclude that hypercapnia increases plasma ANF concentration, and that this increase may be secondary to an increase of the left and right atrial pressures. These phenomena may explain the increase in diuresis and natriuresis which has been described during hypercapnia.

Animals↗
PubMed1989

Theophylline disposition in patients with COLD with and without hypoxemia.

This study aimed to assess the effect of hypoxemia on theophylline disposition. Ten patients with a mean (+/- SEM) of 58 +/- 3 years with COLD (PaO2 55 +/- 1 mm Hg, PaCO2 46 +/- 2 mm Hg, and pH of 7.39 +/- 0.01) were hospitalized to have oxygen therapy. Before starting O2, they received intravenously, 4 mg/kg of theophylline over a 20-minute period; blood samples and urine were collected for six hours. The results suggested that hypoxia does not influence the disposition of theophylline or its metabolites.

Biotransformation↗
PubMed1989

Metabolic CO2 removal by dialysis: THAM vs NaOH infusion.

New methods of respiratory support are needed to reduce the high mortality rate of acute respiratory failure. To simplify the procedures of extracorporeal CO2 elimination under apneic oxygenation, one approach is to replace the membrane lung by a hemodialyzer and to administer an alkali, since hemodialysis requires a lower blood flow rate than blood-gas exchange. This study compared the effectiveness of trishydroxymethyl aminomethane (THAM) and NaOH in this procedure. Twelve male Anglo-Poitevin dogs (25 to 33 kg) were anesthetized, curarized and mechanically hypoventilated (VE = 41% of the control value). After not less than 15 min, a venovenous shunt was used for dialysis with blood flow of 7-10 ml. min.-1kg-1 for at least 8 hours. The dialysate contained no acetate, bicarbonate or lactate, but was alkalinized to a pH of 8-9 by the addition of NaOH. A solution of THAM (0.5 N) was infused into the right heart at the rate of 0.30 ml.min.-1kg-1 in six animals, and NaOH (0.15 N) was infused in the other six at the rate of 0.80 ml.min-1kg-1. The injected volumes were compensated for by an equivalent amount of ultrafiltration. Elimination of CO2 (mean TCO2 = 2.3 ml.min.-1kg-1) was the same with both methods and the difference for the electrolytes and acid-base equilibrium was only very small. However, hemolysis was six times greater with NaOH than with THAM. Despite ultrafiltration, a similar marked weight gain was observed from the second hour of the experiment in the NaOH series, but only after 7 hours with THAM. It thus appears that hemodialysis combined with alkalinisation is still too complex a procedure to be safely applied in acute or chronic pulmonary failure.

Acidosis↗
PubMed1988

Cardiorespiratory function and pathological findings in heart-lung block reimplanted after hypothermic preservation.

A good result from the heart-lung transplantation depends on the quality of the preservation of cardiopulmonary transplants. To determine the functional and pathological status of the heart-lung block after preservation for several hours, we performed 10 heterologous heart-lung transplantations in Beagle dogs (weight 13.5 kg) under extracorporeal circulation. Weight and length compatibility between donor and receiver was ensured. Measurements of hemodynamics, lung mechanics and blood gases were performed in the donor and in the receiver before the transplantation, and in the receiver after heart-lung reimplantation. Histological studies were carried out by biopsy on the heart and on the lung of the donor before removal, at the beginning of the preservation at low temperature, after 3 h of ischemia in cold, and every hour after recirculation in the heart-lung block. Myocardial preservation was conducted with cold cardioplegia at 4 degrees C (Ringer lactate solution with high potassium). Lung preservation was achieved by injecting a Euro-Collins solution at 4 degrees C, with addition of dog plasma, into the pulmonary artery; during the whole ischemic phase, the lung parenchyma was maintained at 0 degrees C, and inflated at a 10 cm H2O pressure. After transplantation, we observed that cardiac output was low in all cases, with normal or subnormal pulmonary arterial pressure. Dynamic lung compliance was very low immediately after transplantation, and increased when restarting the circulation, but deteriorated again after several hours. At the same time alveolo-arterial O2 pressure difference and arterio-alveolar CO2 pressure difference progressively increased, due to the extensive gas exchange impairment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Effect of moderate hypoxemia on atrial natriuretic factor and arginine vasopressin in normal man.

The object of this study was to assess the effect of moderate acute hypoxemia on plasma concentrations of atrial natriuretic factor (ANF), arginine vasopressin (AVP), plasma renin activity (PRA) and urinary excretion of prostaglandin E2 (UPGE2V). Eight volunteers were exposed for 2 hours to a gas mixture containing 10% O2, 4.5% CO2 and 85.5% N2. Hypoxia increased diastolic blood pressure and free water clearance. Hypoxia did not change the AVP, PRA or UPG2V, although increased ANF from 17.7 +/- 3.4 pg/mL to 27.2 +/- 1.7 pg/mL (p less than 0.005) at 120 minutes. ANF changes were closely associated with the rise in blood pressure.

Adult↗
PubMed1987

Theophylline disposition during acute and chronic hypoxia in the conscious dog.

It has been reported in experimental models that acute hypoxia reduced the activity of the hepatic cytochrome P-450. The objective of the present study was to investigate in conscious dogs whether acute and chronic hypoxia will influence the disposition of theophylline. To this purpose 6 beagle dogs received 8 mg/kg i.v. of theophylline while breathing air, after acute hypoxia (PaO2 of 48.5 +/- 0.3 mmHg) and after 96 hours of hypoxia. Theophylline and metabolites, 3-methylxanthine and 1,3-dimethyluric acid, were assayed by HPLC. Theophylline volume of distribution, while breathing air, was 0.51 +/- 0.03 L/kg and was not affected by hypoxia. Theophylline metabolic and renal clearances were 1.53 +/- 0.24 and 0.18 +/- 0.04 mL/min/kg and remained constant when the dogs were hypoxic. The urinary recovery of theophylline and metabolites was not affected by acute or chronic hypoxia. It is concluded, that in the dog hypoxia does not affect the disposition of theophylline.

Acute Disease↗
PubMed1986

Resting muscle glucose metabolites and related compounds in hypercapnia.

Glucose metabolites (lactate, pyruvate, citrate, malate), alanine, glutamate and adenosine triphosphate (ATP) were determined in the resting anterior tibial muscle of dogs. The muscle was sampled in anesthetized animals first breathing air, and secondly after an hour of breathing a hypercapnic mixture, FICO2 = 0.10 (experimental subjects n = 6) or air (control subjects n = 6). A decrease in concentration of glucose metabolites (lactate: -34%; pyruvate: -24%; Citrate: -34%; malate: -54%), glutamate (-43%), alanine (-35%) and ATP (-8%) was observed in the resting muscle during acute hypercapnic acidosis. This was not the case in control animals breathing air.

Animals↗
PubMed1986

Cimetidine inhibits cerebral and hepatic mitochondrial respiration in rat.

The presence of cimetidine in the incubation medium of rat brain mitochondria caused decreased oxygen uptake, especially during oxidative phosphorylation (state 3). This inhibition of the respiratory control and of ATP synthesis was dose-dependent. The same observations were made for hepatic mitochondria. The significance of these results is discussed in terms of both the neurological side-effects of cimetidine and its effect on regulatory mechanisms of cerebral or hepatic blood flow.

Animals↗
PubMed1986

[Tracheal rupture in closed cervicothoracic injuries].

Two cases are reported of tracheal fracture occurring during blunt cervico-thoracic trauma. The first case emphasized the impossibility of passing a tracheal tube below the fracture preoperatively, without the fibreoptic or rigid tracheoscope which has the added advantage of making an accurate diagnosis of the fracture. The clinical and paraclinical signs could only lead to a suspicion of the diagnosis, but not its confirmation. The second case showed the use of different ventilatory means during and after surgery (separate lung ventilation, jet ventilation, high frequency ventilation) in case of proximal fractures. The monitoring of intratracheal pressure should be used so as to have the best ventilation for the lowest pressures in the suture zone.

Accidents, Traffic↗