La dyspnée est une des principales doléances des patients atteints de BPCO. L’objectif principal de cette étude est la description du symptôme de dyspnée et de sa prise en charge chez les patients atteints de BPCO en Lorraine. Il s’agit d’une étude prospective descriptive via la cohorte iBPCO. La population étudiée concerne les 120 premiers patients inclus dans la cohorte iBPCO, au CHU de Nancy, du 01/06/15 au 25/02/16. La dyspnée « sévère » est définie par un stade mMRC supérieur ou égal à 3. Une dyspnée sévère qui persiste plus de 3 mois, malgré un traitement optimal de la BPCO sous-jacente, avec une intensité importante est considérée « réfractaire ». Parmi les 120 patients inclus, 69 sont des hommes (57,5 %) avec un âge médian de 66 ans (57–72). Cinquante-deux patients (43 %) sont obèses et 19 patients (16 %) ont une insuffisance cardiaque. Soixante-quatre patients (53 %) ont une dyspnée sévère, dont 41 patients (soit 64 % d’entre eux) ont une dyspnée réfractaire. L’intensité de la dyspnée évaluée par l’echelle mMRC est positivement corrélée à l’obstruction bronchique (r = 0,49, p < 0,0001). Concernant les comorbidités cardio-vasculaires, il n’y a pas de différence significative entre le groupe dyspnée sévère et non sévère. Les patients qui ont une dyspnée sévère ont significativement plus de symptômes anxio-dépressifs (SAD) que les non sévères : score HAD anxiété positif (>10) 34,4 % versus 11,1 % (p = 0,003) ; score HAD dépression positif (> 10) 31,1 % versus 7,4 % (p = 0,001). Parmi les 120 patients inclus, 41 patients (34 %) ont eu une réhabilitation respiratoire (RR). Concernant les patients avec une dyspnée sévère, 41 % ont effectué une RR et 94 % ont un traitement pharmacologique étiologique considéré optimal selon les recommandations de la SPLF. Les patients qui ont une dyspnée réfractaire ont eu une RR pour 41,5 % d’entre eux. Aucun patient n’a de traitement symptomatique par morphinique à visée eupnéisante. Un quart des patients dyspnéiques sévères et réfractaires qui ont des SAD à prédominance « anxiété » sont traités par anxiolytique et 15 % des patients dyspnéiques sévères et réfractaires qui ont des SAD à prédominance « dépression » sont traités par antidépresseur. La prise en charge de la dyspnée et des comorbidités fréquentes comme les SAD dans le cadre de la BPCO n’est pas optimale. Promouvoir la RR et les traitements pharmacologiques symptomatiques représentent un élément déterminant de la prise en charge globale de la BPCO.

Si les relations entre régime alimentaire et fonction pulmonaire ont fait l’objet d’études au sein de larges cohortes prospectives, les liens entre apports alimentaires et les manifestations de la BPCO au sein d’une population de patients BPCO restent à préciser.

Point mutations in the gene of pyruvate oxidase from Lactobacillus plantarum, with proline residue 178 changed to serine, serine 188 to asparagine, and alanine 458 to valine, as well as a combination of the three single point mutations, lead to a significant functional stabilization of the protein. The enzyme is a tetrameric flavoprotein with tightly bound cofactors, FAD, TPP, and divalent metal ions. Thus, stabilization may be achieved either at the level of tertiary or quaternary interactions, or by enhanced cofactor binding. In order to discriminate between these alternatives, unfolding, dissociation, and cofactor binding of the mutant proteins were analyzed. The point mutations do not affect the secondary and tertiary structure, as determined by circular dichroism and protein fluorescence. Similarly, the amino acid substitutions neither modulate the enzymatic properties of the mutant proteins nor do they stabilize the structural stability of the apoenzymes. This holds true for both the local and the global structure with unfolding transitions around 2.5 M and 5 M urea, respectively. On the other hand, deactivation of the holoenzyme (by urea or temperature) is significantly decreased. The most important stabilizing effect is caused by the Ala-Val exchange in the C-terminal domain of the molecule. Its contribution is close to the value observed for the triple mutant, which exhibits maximum stability, with a shift in the thermal transition of ca. 10 degrees C. The effects of the point mutations on FAD binding and subunit association are interconnected. Because FAD binding is linked to oligomerization, the stability of the mutant apoenzyme-FAD complexes is increased. Accordingly, mutants with maximum apparent FAD binding exhibit maximum stability. Analysis of the quaternary structure of the mutant enzymes in the absence and in the presence of coenzymes gives clear evidence that both improved ligand binding and subunit interactions contribute to the observed thermal stabilization.

Recombinant factor XIIIa (FXIIIa), produced in Saccharomyces cerevisiae, was recovered as a fully active cytosolic component and rigorously compared to natural F XIIIa from human placenta with respect to physicochemical and functional properties. Identical parameters were found in SDS polyacrylamide gel electrophoresis, analytical ultracentrifugation and HPLC gel filtration, and all spectral characteristics including derivative UV absorbance, fluorescence and circular dichroism were identical. Similarly, the interaction of both proteins with polyclonal antibodies directed against the entire FXIIIa or its N-terminal 4 kD activation peptide were identical. Furthermore, thrombin cleavage and fibrin cross-linking showed indistinguishable patterns. The only difference we observed was with respect to endgroup analysis. The recombinant protein is homogeneous, whereas placental FXIIIa shows multiple electrophoretic bands caused by microheterogeneity in the C-terminal part of the protein.

The denaturation-renaturation transition between the native and unfolded states of the dimeric blood coagulation factor XIIIa has been examined by far-UV circular dichroism, fluorescence spectroscopy, activity measurements, sedimentation equilibrium analysis, and size exclusion high performance liquid chromatography. Guanidine hydrochloride and urea-dependent denaturation in the absence and in the presence of 5mM dithioerythritol or glutathione (5mM GSH) exhibit biphasic transitions. The first stage represents a sharp transition characterized by a change in secondary structure without subunit dissociation. This step is accompanied by the irreversible loss of biological activity. The second transition reflects the dissociation and complete unfolding of the protein to a random coil. After loss of biological activity no reactivation can be accomplished under any of the following conditions: (i) denaturation and renaturation under reducing or non-reducing conditions, (ii) variation of the protein concentration and temperature, (iii) addition of specific ligands (Ca2+, substrate), (iv) presence of stabilizing and/or destabilizing agents. Attempts to renature the protein under standard conditions (0.1 M Tris/HCl pH 7.5-9.0, 5mM DTE, 5mM EDTA) lead to refolding intermediates which exhibit a strong tendency to aggregate. A soluble product of reconstitution can be obtained by refolding at low protein concentration, low temperature, and in the presence of small amounts of destabilizing agents such as arginine or urea in the renaturation buffer at pH 7.5 to 9. The spectroscopic and hydrodynamic characterization of the partially reconstituted (non-native inactive) protein shows that partially reconstituted factor XIIIa exhibits the fluorescence properties and the dimeric structure of the native protein.(ABSTRACT TRUNCATED AT 250 WORDS)