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Biomedical subjects

G Chauvet

Publications and source records attributed to G Chauvet.

At least 37 records · Page 2Linked to original sources

[Malarial problems and the trans-Saharan highway].

In Maghreb, malaria eradication is near. In particular, no indigenous strains of P. falciparum have been found for ten years. The few remaining cases of malaria are of P. vivax. In the Sahelian area, on the other hand, malaria eradication failed with P. falciparum and the efficient vector A. gambiae (s.l.). Until now, the Sahara desert separated these two areas. With construction of a trans-saharan highway, the situation is very different. Now, tropical malaria circulates in Maghreb and Sahara oases in the same way as vectors. However, it seems that local vectors in Maghreb (A. labranchiae) and in Sahara (A. multicolor et A. sergenti) are not efficient vectors for tropical strain of P. falciparum. These observations must be confirmed because there are probably different anopheles populations with different vectorial capacity in the same anopheles species and different plasmodial strains with different infective capacity in the same plasmodial species. Meanwhile a dangerous potential situation exists, the temporary or permanent colonization of some stations in Sahara, in Maghreb (?) by A. gambiae the efficient vector of tropical strains of P. falciparum. From now on, important efforts of Prevention and Control for vectors and malaria must be developed with large intensity in Saharan oases and in Maghreb.

Africa, Northern↗

Analytical subcellular fractionation of guinea pig peritoneal macrophages: preparation of purified plasma membranes.

A method using sucrose gradient centrifugation is described for the purification of plasma membranes of guinea pig peritoneal macrophages. The subcellular fractions obtained have been submitted to a biochemical and ultrastructural analysis. Two plasma membrane markers, 5'-nucleotidase and alkaline phosphodiesterase I, have been assayed at the same time as markers for other subcellular organelles, DNA (nuclei), succinic dehydrogenase (mitochondria), inosine diphosphatase (endoplasmic reticulum), and acid phosphatase (lysosomes). The exposure of the plasma membranes to a low concentration of digitonin allowed us to obtain their high purification. They are only contaminated by 2-3% of other cell components present in the macrophages homogenate. The representative ultrastructural technique used has confirmed the purity of the plasma membranes isolated.

Animals↗

[Estimation of visco-elastic parameters of the bronchial system based on measurements obtained by dynamic tracheobronchography].

Visco-elastic parameters of the bronchi system are represented by the viscous modulus and the recoil static pressure. In several generations, values of the cross-sectional area of the bronchi are defined at various moments by the results obtained with dynamical tracheo-bronchography. By means of these measures and the use of a model describing the air flow in elastic bronchi, a calculation procedure of the visco-elastic parameters has been established.

Bronchi↗

[Comparison of algorithms for the resolution of a secular equation in the vibrational analysis of biological molecules].

A computer analysis of several solution methods for secular equations leads to a determination of their optimum conditions. The results contribute to the application of a new preliminary method of frequency assignment to the vibrational study of the heavy atoms coordination sphere in complex biological structures, such as metalporphyrins and adenosine triphosphate.

Adenine Nucleotides↗

An interpretation of asynchronism in non-sequential ventilation (apical and basal regions of the lung).

Non-sequential asynchronous ventilation is interpreted by a variation of velocity of fluid at a given level of bronchial tree based on a physical model already published (Chauvet and Tuchais, 1976). The possible different causes of this variation of velocity are examined. A complete study of apical and basal regions of the lung is made and it shows the influence of some factors (phase difference, amplitude, respiratory frequency) on the regional variations of alveolar pressure.

Humans↗

Discussion on basic equations for a flow in human air passages and their representation.

Basic equations of time-dependent flow are discussed in the case of rigid or elastic branches and according to the airway representation pattern, both continuous and discontinuous. Two relevant fundamental continuous functions are defined: the 'order of generation' G(x) and the cumulative bronchial diameter D(x). A numerical solution is outlined in the former case, then in the latter case, and the system of equations which completely describes the flow is solved.

Bronchi↗

A physical model of time-dependent flow in the human air passages.

A physical model of the time-dependent, homogeneous, viscous and incompressible flow in the first twelve bronchial branches is described. The anatomical data given by Weibel (1963) are used. By means of these hypotheses we obtain the following equation: Palv(t) = K1V'B(t) + K2VB2'(T), where K1 and K2 are constants which depend on bronchial geometry and Palv(t) and VB(t) are the alveolar pressure and the mouth flow rate, respectively. Some results concerning laterobronchial pressure and velocities are given.

Atmospheric Pressure↗