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Biomedical subjects

M Chauveau

Publications and source records attributed to M Chauveau.

11 recordsLinked to original sources
PubMed1992

Bronchial provocation tests in small animals: a quantified and automated procedure.

Bronchial provocation tests using aerosols in laboratory animals are difficult to standardize and quantify, because the amount of drug actually reaching the airways is unknown. To improve the quantification of aerosolized inhaled stimuli, we designed an apparatus that allows, in anesthetized intubated ventilated animals, control of temperature and hygrometry of inspired air, computerized measurement of pulmonary resistance, and fully automated delivery of a known amount of aerosolized drug directly into the trachea. Calibration of the aerosol delivery involved direct measurement of liquid delivered at the tip of the tracheal cannula. Despite all our efforts at standardization and full automation of all steps, reproducibility of aerosol delivery was poor, with stroke-by-stroke differences of 26 or 42%, according to whether an air-jet or an ultrasonic nebulizer was used. Histamine dose-response curves performed in 15 guinea pigs with this device confirmed marked differences among animals and also disclosed large intraindividual changes in bronchial responsiveness.

Aerosols↗
PubMed1988

Breathing dry air causes acute epithelial damage and inflammation of the guinea pig trachea.

Drying and cooling of the airways mucosa caused by respiratory water loss may be responsible for exercise- and hyperventilation-induced asthma. Therefore we designed this study to investigate whether breathing dry air is capable of causing structural changes of the airways mucosa. Anesthetized guinea pigs breathed spontaneously through a tracheostomy either dry (n = 15) or water-saturated (n = 12) air at approximately 38 degrees C for 30 or 60 min, during which time total pulmonary resistance (TPR) was measured. Immediately afterward, the animals were killed and the lungs and airways were prepared for histological examination (light microscopy, transmission electron microscopy, and scanning electron microscopy). With dry as well as humid air, there was no change in TPR or in the structure of the main bronchi and lung parenchyma. With humid air the tracheal mucosa was normal in six guinea pigs and exhibited minor changes of the ciliae in eight and localized epithelial damage on light microscopy in the remaining animal. With dry air we found widespread loss of the ciliae on scanning electron microscopy in 10 of 12 animals, associated with detachment or sloughing of the epithelium, subepithelial vascular congestion, edema, and cellular infiltration on light microscopy. Our data demonstrate that a short exposure of the trachea to dry air causes marked epithelial lesions and local inflammation.

Air↗
PubMed1987

The arteriovenous fistula in segmental pancreatic transplantation in dogs--a hemodynamic study.

Arterial and/or venous thrombosis is a frequent complication in experimental or human pancreatic transplantation. A canine experiment was used to study the hemodynamic effects of spleno-splenic arteriovenous fistula during segmental pancreatic transplantation. An increase in blood flow, without "steal" syndrome in the pancreatic blood supply or pressure increase, was found. Thus this technique can help prevent vascular thrombosis in pancreatic transplant in dogs.

Animals↗
PubMed1986

[Doppler study in algodystrophy. Apropos of 10 cases].

Algodystrophy is usually attributed to disorders of microcirculation, and one may reasonably expect to demonstrate these by the Doppler method applied to arteries. Ten patients with algodystrophy stage I were explored and compared with 10 healthy controls and 10 patients with diseases likely to encourage the development of algodystrophy. Systolic, diastolic and mean blood flow velocities were recorded at different levels in the limbs involved and compared with velocities recorded at the same levels in the limbs of healthy subjects and in the clinically healthy limb of control patients. Algodystrophic patients actually had local circulatory abnormalities consisting of an increase in mean velocity with a diastolic component. A diastolic velocity superior to 3 cm/sec on the main arterial axis of the affected limb, or a difference of more than 5 cm/sec in mean velocity between the right and left sides provided an early diagnosis of algodystrophy with an 80 p. 100 sensitivity in this small series. Moreover, in 3 out of 10 cases Doppler velocimetry demonstrated abnormalities at varying levels of the contralateral limb.

Adult↗
PubMed1985

Quantitative Doppler blood flow measurement method and in vivo calibration.

Femoral blood flow (FBF) was measured in seven dogs, simultaneously with both an electromagnetic perivascular probe and a transcutaneous range gated Doppler velocimeter. Measurements were made in basal conditions and during intraarterial infusions of noradrenaline (10 to 400 ng . kg-1 . min-1) and isoprenaline (10 to 400 ng . kg-1 . min-1) thus allowing comparisons of ultrasonic (DBF) and electromagnetic (EMBF) blood flow at 91 different blood flow rates ranging from 5 to 300 cm3 . min-1. The linear regression line through the data of ultrasonic and electromagnetic simultaneous measurement was: DBF = 0.8 + 1.016 EMBF +/- 19.0 cm3 . min-1 with a highly significant correlation (r = 0.96, p less than 0.001) but there was a wide scattering about the mean. Errors in DBF were mainly due to positioning of the probe and determination of arterial diameter.

Animals↗
PubMed1977

[Effect of catecholamines in blood flow in arteries of distribution].

In large arteries, distributing blood to an area (hind leg of dog), the vasomotor substances (catecholamines) induce differences in flow. In case of state of vasoconstriction, the mean velocity of flow decreases, while the amplitude of pulsatile flow and the pressure increase. The radial expansion is wider. In case of state of dilatation, inverse reactions are observed.

Animals↗
PubMed1977

[Effect of localized heat on blood flow in arteries of distribution].

In large arteries distributing blood to an area (hind leg of dog), local heat induces a vasodilatation. The mechanical reactions (variations of mean velocity of flow and amplitude of pulsatile flow) express a distal dilatation. Radial expansion responds in original way (pulsation become uniform).

Animals↗
PubMedDate not supplied

[What information can digital plethysmography provide in acrosyndromes?].

Digital plethysmography records digital pulsation and measures blood flow by occlusion and perfusion pressure. The pulsatile curve is modified in vasomotor disorders of the extremities, and is delayed and flattened in obstructive arteriopathy. In Raynaud's phenomenon, the basal flow (at 22 degrees C) decreases with clinical severity, and suppression of post-ischemic blood flow by cold seems to be an attribute of Raynaud's disease. Digital perfusion pressure is usually greater than or equal to 70% of the humeral systolic pressure. When it decreases under hot conditions, organic obstructive arteriopathy is indicated; decreases due to local cooling allow quantification of hyperreactivity to cold of the digital artery.

Cyanosis↗
PubMedDate not supplied

[An unusual case of intermittent venous claudications].

The authors report on a case of intermittent venous claudications in a 76-year-old man, who three months previously suffered a sudden acute attack of phlebitis in the right upper limb. The Doppler exam showed post-phlebitic failure of the humeral valve and diminished permeability of the axillobrachial axis of the vein, with sub-clavicular obstruction. The discussion provides an opportunity for reviewing the various anatomo-pathological definitions and explanations of the mechanism of intermittent venous claudications.

Aged↗