Biomedical subjects

A Marchand

Publications and source records attributed to A Marchand.

58 records · Page 4Linked to original sources

PubMedDate not supplied

A highly specific functional test for factor V leiden: A modified tissue factor assay for activated protein C resistance.

We compared the sensitivity and specificity of a tissue factor-based assay (FVR) with the addition of a phospholipid/silica preparation, to the commercially available aPTT-based method, APCR (CoatestTM), and a modified aPTT-based method (APCM) which utilized factor V-depleted plasma, for the detection of the factor V Leiden mutation. A total of 110 patients were included in this study. This included 32 patients on coumadin therapy, 7 patients on heparin therapy, 5 patients on both anticoagulants therapy, and 24 patients who were positive for anticardiolipin antibody (ACL) and/or lupus inhibitor (LI). Our data demonstrate that the FVR is not affected by anticoagulation treatment or ACL/LI antibodies, whereas in the APCR method, 33 patients cannot be determined either due to the anticoagulant therapy or presence of the ACL and/or LI. With the APCM method, the clotting endpoint could not be determined in 1 patient due to the presence of a strong LI. The additional phospholipid/silica material utilized in the FVR enhanced the APC degradation of factor Va and therefore sharpened the demarcation between the factor V Leiden-positive and -negative patients. The sensitivity for the APCR, APCM and FVR was 42, 97 and 100% respectively. The specificity for the APCR, APCM and FVR was 94, 96 and 100% respectively.

Activated Protein C Resistance↗

PubMedDate not supplied

[Oscillations in population densities of the bacterial prey-predator couple Escherichia coli-Bdellovibrio bacteriovorus: experimental study and theoretical model].

Oscillations in population densities in the bacterial predator-prey Bdellovibrio bacteriovorus-Escherichia coli system were investigated both experimentally and theoretically. Experimental conditions for observing (damped) oscillations were first determined in a closed system and then used in an open system, i.e. in a chemostat, when an adequate flux of nutritive medium was added. The experimentally observed oscillations were always unstable with poorly reproducible amplitude and period. A theoretical model was used in order to explain this behaviour. It was first presented and satisfactorily tested for the same bacterial couple operating in a closed system, and allowed an experimental determination of its kinetic parameters. When adapted to open system conditions, it yielded computer-simulations which showed oscillations of the population densities in good agreement with those experimentally observed. It also showed that stable oscillations were not possible, the only "focus" in the predator-prey-density plane being an unstable one with no surrounding limit cycle.

Bdellovibrio↗

PubMedDate not supplied

[Theoretical model of the predator-prey interaction kinetics between "Bdellovibrio bacteriovorus" and "escherichia coli" (author's transl)].

A theoretical model is suggested in order to explain the main features of the interaction kinetics between the micropredator Bdellovibrio bacteriovorus and its prey Escherichia coli. Three parametes are used in this model: the incubation time T, the fixation rate constant k, and the predator multiplication factor a. Their values can be determined from the experimental variations of the total predator concentration p, and the total density of preys (c + c'). An experimental study of the predation kinetics was performed at various temperatures (25-40 degrees C) and in media with different Ca++ and Mg++ concentrations. From the values of parameters obtained, theoretical prey and predator density curves were computer-simulated; they agree satisfactorily with the experimental curves. The parameters values are quite reasonable and in good agreement with previous findings.

Bdellovibrio↗

PubMedDate not supplied

[Validation of a questionnaire of physical sensations in a French-Canadian population].

The objectives of this study are three-fold. The first objective is to present the aspects of reliability and validity of a self-reported questionnaire that evaluates a specific facet of Panic Disorder with Agoraphobia (PDA) for the francophone population of Quebec, mainly the fear of fear. The Body Sensations Questionnaire (17), translated as the Questionnaire des Sensations Physiques (QSP) evaluates the degree to which individuals fear somatic symptoms commonly associated with panic. A second objective is to determine the factorial validity of the QSP and to investigate the dimensionality of the construct as assessed by the questionnaire. The third objective is to establish a reference database for the agoraphobic (N = 141 and N = 70) and the non-clinical population (N = 223). Results suggest that both questionnaires have similar internal consistency, temporal stability, construct validity, and discriminative validity. While the factorial solution of the present study uncovered a three-factor model (somatic, cardiac, and psychosensorial), which points to the multidimensional nature of the construct evaluated by the QSP, it greatly differs from the one obtained by Arrindel's study (5). Nevertheless, the extraction of the three principal components is supported by the results of the screen test and by two different implementations of parallel analysis, i.e., the computation of random eigen values and the use of an interpolation table of eigen values. Finally, it can be concluded that the psychometric properties of the French-Canadian translation of the BSQ are indications that it is an appropriate instrument to use in clinical research and in clinical practice to assess the fear of bodily sensations associated with the fear of fear.

Adult↗