Search PubMed⌕ Search

Biomedical subjects

C Duvivier

Publications and source records attributed to C Duvivier.

At least 109 records · Page 6Linked to original sources
PubMed1984

Use of a laser-Doppler electrophoresis method in bacteriology (preliminary results).

A new electrophoresis system using Laser Doppler velocimetry has been developed. This technic allows fast measurements, (1 minute) over a large number of particles (several thousand or more). Furthermore, the small size of the particles is no longer a limitation of the measurement. These qualities made it possible to study the electrokinetic properties of cells. In this paper the authors present the first application obtained on different types of bacteria (Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, Proteus vulgaris) submitted to five antibiotics (gentamycin, minocyclin, cephalotin, spiramycin, sobramycin). After four hours of incubation at 37 degrees C, important decreases of electrophoretic mobility were observed on bacteria treated with antibiotics to which they were sensitive. On the other hand, no significant modification appeared on bacteria treated with antibiotics to which they were not sensitive. In conclusion, the electrophoretic mobility test seems to be useful to study the response of bacteria to antibiotics and perhaps could be used to set antibiograms.

Anti-Bacterial Agents↗
PubMed1984

A technique for continuously measuring filtration resistance at constant pressure.

A device for continuously measuring, at constant pressure, the filtration resistance of different liquid suspensions is described. It is made up of two main parts: flowmeter system and electronic circuit. The flowmeter consists of a capillary tube and a sensitive pressure transducer, and has a time response of 100 ms and a linearity of +/- 1% from 1 uls-1. The electronic part allows the calculation and recording of flow versus time and filtration resistance versus the volume which passes through the filter. Principle, technical characteristics of the system and examples of recording with several Red Blood Cell populations are reported.

Electronics↗
PubMed1983

Spinability of bronchial mucus. Relationship with viscoelasticity and mucous transport properties.

Spinability of normal mucus and of sputum collected in chronic bronchitic patients was measured using an automatic device derived from that developed by CHRETIEN et al (1977) for cervical mucus. Spinability of sputum decreased as the purulence increased. Although significant correlations were found between spinability and apparent viscosity (r = - 0.50, p less than 0.05) or elasticity (r = 0.54, p less than 0.02), large variations in spinability were observed for sputum samples ranging in a zone of low viscosity and elasticity. Sputum with high spinability exhibited normal transport rate on the depleted frog palate although their viscosity and elasticity were abnormally low. The significant correlation obtained between spinability and sputum transport rate (r = 0.61, p less than 0.01) suggests that this rheological factor, along with viscosity and elasticity, plays an important role in the mucociliary transport mechanism.

Adult↗
PubMed1982

Effect of a rocking bed on apnoea of prematurity.

We describe a rocking bed for use in incubators. Its effect was studied in 12 preterm infants with idiopathic apnoea, using each as his own control. All but one had less apnoea when the bed was rocking than when it was still. Apnoea associated with a significant fall in transcutaneous PO2 was less frequent, and fewer interventions were needed to terminate apnoeic attacks.

Apnea↗
PubMed1982

New device for determination of cell electrophoretic mobility using doppler velocimetry.

Electrical phenomena of cell membranes may be examined by means of cell electrophoresis. Direct microscopic techniques are tedious, inaccurate and rarely reproducible. Therefore, the authors have developed a new device using Doppler velocimetry. After describing the apparatus, they propose two methods for testing treatment against electroosmosis and present the first biological applications on mixed populations of red cells.

Cell Membrane↗
PubMed1980

The continuous monitoring of CO2 ductances in pulmonary intensive care.

A cardiorespiratory monitoring system allows the measurement of FAECO2 and FECO2 in the expired air of the patient at the mouth (endtidal CO2) and in a mixing box. From these parameters, combined with the measured PACO2, the alveolo-expired (DuA = PECO2/PAECO2) and alveolar-arterial (Dua = PAECO2/PACO2) ductances which assimilate the respiratory system to a two-stage exchanger have brought about a lot of valuable information 1. DuA improves by 20% in 20 patients after removal of bronchial obstruction (p < 0.001) and by 9% in 7 intubated patients after tracheotomy (p < 0.02). DuA falls by 15% (p < 0.001) in 10 patients with hypocapnia (PaCO2 = 28 mmHg) after a dead space adjunction with the aim of normalizing PaCO2 (paCO2 = 35 mmHg). 2. Dua falls by 33% in six patients after pulmonary embolism, proved by angiography (p 0.001) by 9% in 34 patients after 30 min of pure oxygen breathing (p 0.001). On the other hand, inthe absence of clinical or radiological pulmonary edema, in increases by 19% in 38 patients with hypervolemia after diuresis (furosemide) (p < 0.001). Thus since DuACO2 varies with anatomical dead space and the air distribution disorder, DuaCO2 evolves according to the disorders of the blood distribution and arterial-alveolar diffusion. The determination of these coefficients, in the absence of significant changes in the arterial blood gases, helps the diagnosis, guides the early treatment and allows for the monitoring of its efficiency.

Airway Obstruction↗
PubMed1978

The respiratory response to inhaled carbon dioxide in man after 3 hours exposure to 3% carbon dioxide.

1. The respiratory response to inhaled 3% and 6% CO2 was measured in 10 normal subjects after a 3 h acclimatization period to 3% CO2 in an environmental chamber. Control studies were carried out after a 3 h period of breathing air in the chamber. 2. At the end of the acclimatization period studies were carried out during 20 min periods breathing 3% CO2, 6% CO2 and air. 3. At 2-min intervals during the studies measurements were made of tidal volume (Vt), breathing frequency (fR), minute ventilation (Ve), viscous pulmonary rate of work (Wp) and total viscous rate of work across the lungs and apparatus (Wt). Blood gas tensions were measured at the end of this period. 4. After acclimatization to 3% CO2 there was a significant shift in the response curves Ve/Pa,CO2 and Wt/Pa,CO2 such that subjects showed higher Pa,CO2 values for given values of Ve or Wt. There was no significant change in the slope of the response curves. 5. No correlation was found between the slope of the response curve after the control period breathing air and the degree of shift of the response curve. 6. There was no difference in respiratory pattern or in pulmonary resistance. 7. Similar results were found in two subjects studied after 24 h acclimatization to 3% CO2 but one subject also showed a significant change in the slope of the Ve/Pa,CO2 curve.

Acclimatization↗
PubMedDate not supplied

Effect of atrial natriuretic peptide on bronchial tone in anesthetized rabbits.

The effect of atrial natriuretic peptide (ANP) on histamine-induced bronchoconstriction was studied in vivo (in normoxic and in hypoxic rabbits) and in vitro. Thirty-two anesthetized rabbits, spontaneously breathing room air or 10% O2, received infusions of ANP (20, 40, or 80 ng/min/kg normoxia; 20 ng/min/kg hypoxia) or the vehicle for 100 min. After 75 min of ANP infusion, bronchoconstriction was induced inhaling histamine; respiratory resistance (Rrs) was measured prior to and until 20 min posthistamine. The results show that the histamine-induced increase in Rrs was significantly reduced by ANP 80 ng/kg/min in normoxia, and by ANP 20 ng/kg/min in hypoxia. In vitro, ANP had no effect on tracheal and bronchial smooth muscle precontracted with histamine or acetylcholine. These results show that ANP can decrease a histamine-induced bronchoconstriction in vivo but not in vitro, suggesting an indirect mechanism of action.

Airway Resistance↗
PubMedDate not supplied

[The Nadis cohort: 6236 HIV-infected patients followed up in French university hospitals].

OBJECTIVE: The Nadis electronic medical patient record allows real time constitution of a database including the clinical, therapeutic, biological, and epidemiological features of HIV-positive patients. METHODS: Data concerning HIV-infected patients followed-up in 6 French University Hospitals was collected. Data quality was assessed on a regular basis in each center. RESULTS: The 6 first University hospitals using Nadis agreed to group their data on March 15, 2004, concerning 6236 patients having consulted at least once in the previous year. Among these, 29% were female patients, 80% were under treatment on March 15, 2004, 9% were off treatment, 29% were co-infected by hepatitis B or C virus, 57% had an undetectable viral load, 15% of the treated patients were in a worrying immunovirological situation, 358 were diagnosed HIV-positive in 2003. 35% of these "new patients" were women, the mode of infection was sexual in 80%, 45% were under treatment on March 15, 04. This recent data allowed us to have an accurate assessment of this population's management in 2004.

Adult↗
PubMedDate not supplied

[Technical and experimental study of two electronic spirometers (author's transl)].

Two electronic spirometers which use standard pneumotachographs were evaluated for their static and dynamic response, and clinically compared in 20 subjects to a reference flow channel. In the Pneumoscreen the data are digitalized and stored, permitting to play back the flow-volume curves at low or high speed. The instrument provides a direct read-out of forced vital capacity and of five indexes of forced expiration. It was found perfectly adequate with respect to linearity and frequency response. However, due to some systematic error in digital processing, maximum flow at low lung volumes appeared substantially over-estimated. Besides forced vital capacity and a number of indexes of forced expiration, the Medistor type M 010 may be used to measure ventilation, tidal volume, frequency and maximum breathing capacity. The data are processed by an analog computer. The transducer was found poorly linear with inadequate frequency response. However, no systematic bias in the measurements was found, except for peak flow and maximum breathing capacity.

Airway Obstruction↗
PubMedDate not supplied

Comparative value of respiratory input and transfer impedances in field studies.

Total respiratory impedance was obtained from 4 to 30 Hz in 39 healthy males and in 140 iron miners by studying the relationship between transrespiratory pressure and mouth flow when forced oscillations were applied to the respiratory system in two different ways: by varying pressure at the mouth (input impedance, Zin); by varying pressure around the chest (transfer impedance, Ztr). Zin was characterized by the slope (S) and intercept (R0) of the resistance-frequency curve, by the resonant frequency (fn), and by total respiratory inertance (I) and compliance (C) obtained from the reactance. Transfer resistance and reactance curves were respectively analysed with a two-parameter (m1, m3) and a three-parameter (m0, m2, m4) equation. Significant correlations were found between impedance indices, particularly between m1 and both R0 (r = 0.931; p less than 0.001) and m2 (r = 0.739; p less than 0.001), and also between impedance indices and maximal expiratory flows. Nonsmoking miners (n = 40), compared to control nonsmokers (n = 16), had slightly lower maximal flows at high lung volumes (p less than 0.05) and higher values of m1 (p less than 0.001), R0, S, m3 (p less than 0.01) and m2 (p less than 0.05). In contrast, miners who smoked (n = 46) mainly differed from miners who did not smoke by lower flows at middle and low lung volumes (p less than 0.01) and larger m0 (p less than 0.01), m2 and m4 (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Spinability of respiratory mucous. Validation of a new apparatus: the Filancemeter.

Spinability is the ability of various biological fluids to be drawn into threads when stretched. This rheological parameter is of particular importance in the mucous transport process and can be easily measured using a newly commercialized apparatus: the Filancemeter. The measurement limits and the volumes of the samples used are presented. By studying the effect of sample volume on spinability, the importance of using well-calibrated samples is demonstrated. For the small volumes of sample (less than 5 microliters), the reproducibility of the measurement is low (coefficient of variation: 63% with 1 microliter sample), whereas it is significantly improved with larger volumes (coefficient of variation: 16% with 5 microliters sample). The measurements on respiratory mucous are in good agreement with the results obtained with a previous apparatus using a clip as a prehension system of the sample. With fluids exhibiting low viscosity like saliva, the higher values obtained with the Filancemeter can be attributed to a better prehension of the sample. This apparatus appears to be suitable for measuring the spinability of various biological fluids such as mucous.

Equipment Design↗