Mechanism of efficient transfection of the nasal airway epithelium by hypotonic shock.

The main barrier to gene transfer in the airway epithelium is the low rate of apical endocytosis limiting naked DNA uptake. Deionized water is known to stimulate the exocytosis of numerous intracellular vesicles during hypotonic cell swelling, in order to expand plasma membrane and prevent cell lysis. This is followed by the phase of regulatory volume decrease (RVD), during which the excess plasma membrane is retrieved by intensive endocytosis. Here we show that the more hypotonic the DNA solution, the higher the transfection of the nasal tissue. P2 receptors are known to be involved in RVD and we demonstrate that some P2 agonists and a P2 antagonist impair transfection in a time-dependent manner. Our study strongly suggests that the nasal airway epithelial cells take up plasmid DNA in deionized water during RVD, within approximately half an hour. Our simple gene delivery system may constitute a promising method for respiratory tract gene therapy.

Growth dynamics in a natural biofilm and its impact on oral disease management.

Measurements of the microbial growth dynamics in natural biofilm communities are almost non-existent. In a recent study, the biofilm formation on teeth was examined. A previously unknown active period of bacterial division occurred at a certain density of plaque bacteria on tooth enamel. The density-dependent cell-division phase of plaque formation contributed 90% of the biomass in the first 24 hrs of plaque formation. This suggested that growth was induced by the bacteria. In vitro assays were developed for rapid evaluation of the growth of surface-linked bacteria by the measurement of cellular components associated with growth on a per cell per time basis. Cell-free supernatants (termed START) of media in contact with bacteria were assayed for their effects on DNA synthesis and other cellular components associated with growth. START was found to increase the incorporation of [3H-methyl]-thymidine on a per cell per time basis, when compared with media not in contact with bacteria. Additional in vivo studies and in situ-based models of complex biofilms are needed if all of the mechanisms involved in the rapid accumulation of biofilm bacteria on teeth and other surfaces are to be understood.

[Contribution of the counter-immunoelectrophoresis for the diagnosis of pneumococcal infections (author's transl)]. / Apport de la contre-immunoélectrophorèse au diagnostic des pneumococcies.

Using counter-immunoelectrophoresis (CIE), the authors have looked for pneumococcal antigens in biological fluids in 141 pneumococcal infections cases (70 meningitis, 25 empyema, 40 pneumonia, 5 peritonitis, 1 pericarditis). The best results (superior to bacteriological results) were obtained with CSF and pleural fluid. Testing sputum by CIE seems to have a real interest in pneumonia. CIE associated with bacteriology, gives more than 20% increase in aetiological diagnosis in pneumococcal infections and permits to set accurate aetiological diagnosis in less than two hours.

[The detection of bacterial antigens by counter-immunoelectrophoresis in N. meningitidis, H. influenzae serotype b, S. pneumoniae infections. Diagnostic value and evolutive aspect (in 216 cases) (author's transl)]. / Mise en évidence d' antigènes bactériens par contre-immunoélectrophorèse dans les infections à: N. meningitidis, H. influenzae sérotype b, S. pneumoniae. Intérêt diagnostique et aspect évolutif à propos de 216 cas.

Using counterimmunoelectrophoresis (CIE) the authors have assayed for soluble bacterial S. pneumoniae, N meningitidis group A, B, C. H. influenzae type b antigens, biological fluids in 216 patients (meningitis: 136; pneumonia: 76; miscellaneous: 4) during 16 months. Because of heterogeneous recruiting (the bacteriology was carried out by different laboratories) the increase in aetiological diagnosis given by CIE is only statistically valid for the bacteriologic negative group when blind antibiotic therapy had already been given. In this group, CIE makes a notable increase in diagnosis of 22,1 % +/- 10,1 in meningitis and 25,5% +/- 12,7 in pneumonia. Various physiopathological aspects are considered concerning soluble bacterial antigens detection during the course of the disease. This method seems very useful and accurate; and therefore should be used in every microbiologic laboratory.

[Etiological diagnosis of acute pneumopathies. Evaluative study. 100 cases in a pneumologic center]. / Diagnostic étiologique des pneumopathies aiguës. Etude critique. 100 observations en milieu pneumologique

This study involved 100 patients with acute pneumonia and hospitalised in a specialised service: 12 bacterial pneumonia, 40 viral pneumonia (i.e. 52% of the total). Only precise viral and bactérial studies could improve these results. Given the poor results obtained using the microbiological techniques available here, the authors suggest the inclusion in all subsequent studies of aetiological diagnosis of a quantitative examination of sputum bacterial flora and examination for the detection of bacterial exoantigens.