Biomedical subjects

E Puchelle

Publications and source records attributed to E Puchelle.

At least 127 records · Page 7Linked to original sources

PubMed1989

Streptococcus pneumoniae and Staphylococcus aureus surface properties in relation to their adherence to human buccal epithelial cells.

Adherence to host cells by pathogenic bacteria is achieved through both specific and non-specific mechanisms. The former involve bacterial adhesin and corresponding cell receptors (Gibbons and Van Houte, 1980), while the second include electric charges and hydrophobicity of bacterial cell walls. In a previous study (Beck et al., 1988), we showed that these two cell surface characteristics vary during growth of Staphylococcus aureus in a manner which should promote adherence to host cells. The aims of the current study were to assess: (1) whether the same growth-related variations in surface properties were present in another bacterial species, Streptococcus pneumoniae; (2) whether the adherence of the two types of bacteria to epithelial cells was in fact different at different growth times; and (3) whether such differences were consistent with the observed surface properties.

Bacterial Adhesion↗

PubMed1989

Adherence of Pseudomonas aeruginosa to respiratory epithelium and the effect of leucocyte elastase.

The tracheobronchial secretions from patients with cystic fibrosis often contain high amounts of free proteases. To evaluate whether human leucocyte elastase (HLE) can favour the persistence of bacterial airways infection, we exposed the frog palate mucosa to HLE and then to radiolabelled Pseudomonas aeruginosa and followed the sequence of events by scanning electronmicroscopy. In response to HLE there was a marked outpouring of mucus and a desquamation of the epithelium. P. aeruginosa was shown to adhere to recently secreted granules of mucus and to the exposed submucosal underlying connective tissues. For the eight different bacterial strains studied, a significative adherence to HLE-injured mucosa was observed only in strains that possessed internal haemagglutinating activity. Neither the presence of fimbriae, nor of the mucoid exopolysaccharide, nor of the bacterial surface haemagglutinating activity could be related to adherence of P. aeruginosa to the injured mucosa. These results support the hypothesis that HLE enhances bacterial infection of the respiratory mucosa both by inducing mucus hypersecretion and by exposing receptors to the microbial adhesins. It is also suggested that P. aeruginosa internal lectins may be implicated in adherence to host tissues.

Animals↗

PubMed1989

Role of mucus and cilia in nasal mucociliary clearance in healthy subjects.

Large interindividual variations of nasal mucocilliary clearance across healthy subjects have been previously described. The aim of this study was to evaluate the respective role of the nasal mucus quality and ciliary activity in determining nasal mucociliary clearance and to study changes in these variables across time and with environmental conditions. In 20 healthy nonsmoking volunteers, the in vivo nasal mucociliary clearance was measured with the saccharin test. Then, nasal mucus and ciliated cells were collected. The in vitro ciliary beat frequency of the nasal cells was evaluated by a photometric analysis. The in vitro nasal mucus transport rate was evaluated by use of the frog depleted-palate model. The nasal mucociliary transport time (NMTT) of saccharin was greater than 30 min in seven subjects and was 13.6 +/- 6.1 min (mean +/- SD) in the remaining 13 subjects. NMTT was correlated to the in vitro transport rate of the nasal mucus (r = -0.75, p less than 0.001), but not to the ciliary beating frequency or to ambient temperature, relative humidity, or air pollution indices measured. Moreover, large intraindividual variations of NMTT, measured on two occasions 4 to 8 wk apart, were found to be significantly correlated with changes in mucus transport rate (r = -0.60, p less than 0.05).

Adult↗

PubMed1989

Effect of air humidity on spinability and transport capacity of canine airway secretions.

The effect of varying the inspired air humidity on a rheological property (spinability) and transport capacity of airway mucus has been analyzed in 10 mongrel dogs. Tracheal mucus was collected in anesthetized dogs inspiring through an endotracheal tube the air of a climate chamber maintained at constant temperature (T degrees:20 degrees C). In one test, the dogs inspired air at an absolute humidity (AH) of 9 g water/m3 air directly through the endotracheal tube. In the other test, the dogs inspired through an artificial nose connected to the endotracheal tube giving a AH of 30 g water/m3 air. Tracheal mucus was collected at the external distal end of the endotracheal tube. The spinability (Sp) or thread-forming properties of mucus was measured. The relative mucociliary transport rate (TR) of mucus was analyzed on a frog palate epithelium preparation. The transport rate was significantly (p less than 0.01) lower (range: 0.59-0.80) when the AH of the inspired air was low in comparison to that obtained with high AH (range: 0.70-1.13). The variations in mucus Sp due to changing AH were positively and significantly correlated (r = 0.80, p less than 0.01) with the corresponding variations in TR. These results suggest that lowering the AH of air induces a decrease in the transport capacity which appears to be dependent on the change of spinability that occurs in the mucus.

Air↗

PubMed1989

The role of mucus gel viscosity, spinnability, and adhesive properties in clearance by simulated cough.

We investigated the role of the viscoelastic and adhesive properties of mucus gel simulants on the clearance of mucus by simulated cough. Mucus-like gels with widely varying viscoelastic properties were prepared from polysaccharides crosslinked with sodium borate. Cough was simulated by opening a solenoid valve connecting a model trachea to a pressurized tank. The clearance of gels lining the model trachea was quantified by observing marker particle transport. Viscosity elastic modulus, relaxation time and yield stress were measured with a steady-shear viscoelastometer. Spinnability (thread formation) was determined with a filancemeter. Adhesivity (surface tension) was measured by the platinum ring technique. The viscoelastic and adhesive properties of the mucus gel simulants spanned the ranges observed for bronchial secretions from patients with COPD. The relationship between simulated cough clearance and the viscoelastic and adhesive properties of the gels was analyzed by stepwise linear regression of the non-zero data matrix. The major independent variable relating to clearance was viscosity. Secondary, but highly significant dependences, were also found for spinnability and adhesivity. Elastic modulus, relaxation time and yield stress had no independent effect on cough clearance over the investigated range. The results indicate that, in the absence of airway surface liquid, cough-type clearance relates primarily with mucus gel viscosity. For a given viscosity, clearance is also impaired by spinnability, i.e. the capacity of the mucus to form threads. At constant viscosity and spinnability, clearance is further impaired by an increase in the adhesivity of the mucus. The negative dependence of each of these physical factors can be rationalized in terms of their inhibitory effect on wave formation in the mucus lining layer during high velocity airflow interaction.

Adhesiveness↗

PubMed1989

The role of mucus sol phase in clearance by simulated cough.

Using a simulated cough machine, we analyzed the effect of adding tensio-active liquids as sol phase simulant on the clearance of gel mucus simulant by cough. Polysaccharides crosslinked with sodium tetraborate were used at different concentration as gel mucus simulant. A drop of gel mucus simulant was deposited either directly on the model trachea or on a sol phase layer simulant (2% sodium dodecyl sulfate in water). The clearance of the mucus simulants was quantified by observing the movement of marker particles in the gel layer. The viscoelastic properties of gel mucus simulants were determined by using a viscoelastometer (SEFAM). The adhesive properties were analyzed by means of the platinum ring technique. The wettability of the mucus simulants was quantified by the automatic measurement of the contact angle of the drop of gel on the model trachea. We found that the addition of a sol phase significantly decreased by about 50% the adhesivity and wettability of the gel mucus simulants. This decrease was associated with a marked enhancement of cough clearance, whatever the viscoelastic properties of the gel mucus simulants. These results suggest that the sol phase is essential in bronchial respiratory mucus clearance by the cough mechanism.

Adhesiveness↗

PubMed1989

Comparative rheological profile of rat gastric and duodenal gel mucus.

Methods for measuring the adhesiveness, plasticity, viscoelasticity and spinnability of mucus microsamples have been developed. The rheological properties of the rat gastric and duodenal gel mucus have been analyzed and compared. Using a controlled stress rheometer (Carri-Med), flow and creep experiments showed that gastroduodenal mucus exhibits a typically non-newtonian, pseudoplastic and viscoelastic behaviour. The apparent viscosity (7,800 +/- 11,000 Pa.s) and yield stress (24.9 +/- 8.5 Pa) of gastric mucus were significantly higher than the duodenal mucus viscosity (39 +/- 160 Pa.s) and yield stress (12.9 +/- 2 Pa). Spinnability of gastric mucus, measured with a Filancemeter (SEFAM), was significantly lower (4.9 +/- 2.5 mm) in comparison to duodenal mucus (6.9 +/- 1.5 mm). Adhesive properties of gastric mucosa (analyzed with the platinum ring method) were not significantly different in comparison to duodenal mucus (99.9 +/- 31.5 mN/m and 92.8 +/- 11.2 mN/m, respectively).

Adhesiveness↗

PubMed1989

Growth and characterization of isolated bovine tracheal gland cells in culture. Influence of a reconstituted basement membrane matrix.

We describe a method for establishing the culture of bovine tracheal submucosal gland (BTG) cells, in which we have also examined the influence of a reconstituted basement membrane matrix derived from the Engelbreth-Holm-Swarm tumor (EHS) on the growth and morphological differentiation of these cells. BTG cells have been isolated by tissue enzymatic digestion using trypsin, deoxyribonuclease I, elastase, hyaluronidase and EGTA for 1 hr at 37 degrees C. Afterwards, cells and tissue were collected by centrifugation and were incubated for 15 min with 15% newborn calf serum to inactivate the proteolytic enzymes. Enzymatic digestion using only trypsin, centrifugation and inactivation steps were repeated three times. Using this protocol, we obtained 15 +/- 4 (X 10(6] cells per g of tracheal submucosa with 72 +/- 2% (n = 5) cell viability. On microscopic observation, isolated cells were mainly composed of serous type glandular cells. Cells were cultured in a 1:1 medium of Dulbecco's Modified Eagle's/Ham's F12 supplemented with 10% fetal calf serum and subcultured in either plastic flasks or flasks coated with EHS matrix. On the plastic, the BTG cells exhibited at confluency an epithelioid appearance. They stained positively with the immunofluorescent anticytokeratin antibody and contained PAS-staining granules. By electron microscopy, lactoferrin, a protein marker specific to the serous cells, was demonstrated immunocytochemically in small secretory vesicles. BTG cells cultured on EHS matrix revealed a significantly increased growth in comparison to those cultured on plastic. In post-confluent culture of BTG cells on EHS matrix, we observed numerous dome-like structures formed by differentiated cells which were joined together around luminal spaces.

Animals↗

PubMed1988

Synthesis and secretion of an albumin-like protein by cultured bovine tracheal gland serous cells.

Bovine tracheal submucosal gland serous cells were incubated with (35S) methionine. The proteins synthesized and secreted into the culture medium during pulse and chase periods were analyzed. Three major protein bands with apparent molecular weight values of 67 kD, 47 kD and 32 kD were detected by fluorography following SDS-polyacrylamide gel electrophoresis. Based on the molecular weight, immuno-reactive cross reactivity and surface molecular change characteristics, the labeled Mr 67 kD protein was identified as an albumin-like protein. Our results suggest that albumin found in airway secretions can originate, at least in part, from tracheal gland serous cells.

Albumins↗

PubMed1988

[Methods of studying mucociliary function].

The mucociliary system represents the first respiratory tract barrier which acts by removing insoluble particles from the conductive airways. Impairment of mucociliary clearance, due to respiratory mucus and ciliary activity abnormalities, leads to mucus stasis, responsible for infection and bronchial obstruction. In obstructive airway diseases, the efficiency of the mucociliary function can be investigated quantitatively by in vivo and in vitro tests. In vivo mucociliary clearance can be measured by radioactive marker techniques. In vitro tests can evaluate the physical properties and transportability of mucus. The ciliary function can easily be analyzed on ciliated cells collected by nasal or bronchial brushing. Coupled with respiratory function tests, the investigation of the mucociliary function by in vivo and in vitro tests, provides a guideline for selection and assessment of drugs used to correct mucociliary disorders.

Bronchi↗

PubMed1988

A new model for studying bacterial adherence to the respiratory epithelium.

The frog palate mucosa was used as a new model for studying bacterial adherence to the respiratory epithelium. The main advantage of this model is that the mucus blanket, normally present on airway mucosa, can be preserved during the assays. The adherence of radiolabeled pneumococci to mucus-coated mucosa was five times higher (P less than 0.001) than the adherence to mucus-depleted mucosa. In the latter case, bacteria were never seen attached to ciliated cells but could be detected on small remaining patches of mucus. These results demonstrate that respiratory mucus plays a major role in bacteria-mucosa interactions.

Animals↗

PubMed1987

Relationships between the lipid content and the rheological properties of airway secretions in cystic fibrosis.

The lipid composition and rheological properties of expectorated airway secretions have been analyzed in 16 patients with cystic fibrosis (CF), separated into two groups according to whether their secretions were superinfected or not. The total lipid content was higher in the superinfected CF secretions. The content in cholesterol and GL1, GL3 and GL4 glycosphingolipid fractions were significantly higher in the superinfected in comparison to the non-superinfected group. The viscosity was two-fold higher in the CF superinfected group. A significant correlation (r = 0.72, p less than 0.01) was observed between the apparent viscosity and the total lipid content of CF secretions. Cholesterol, glycosphingolipids and sphingomyelin were the lipid components which were the most closely and positively correlated to the viscosity. On the opposite, phosphoglycerol was negatively correlated (r = -0.72, p less than 0.05) to the viscoelastic properties of CF airway secretions.

Adolescent↗

PubMed1987

Identification of different molecular forms of human airway lysozyme.

Human airway lysozyme (HAL) was separated into fractions of distinct molecular forms using a Mono S cation-exchange column on a fast-protein liquid chromatography system. This new and rapid (30 min) purification procedure of human lysozyme enabled the preparation of fractions, highly enriched in different isoenzymes of HAL. Purified HAL from pathological purulent airway secretions, nonpurulent airway secretions, and normal tracheobronchial tissue culture medium was characterized by four, three, and only one enzymatically active molecular forms, respectively. All charge forms (separated or combined) recovered from either purulent or nonpurulent airway secretions or tracheobronchial culture medium exhibited the same apparent molecular weight of 15,000.

Chromatography, Ion Exchange↗

PubMed1987

Rheological properties controlling mucociliary frequency and respiratory mucus transport.

Respiratory mucus and mucosa possess highly hydrophilic structures which are difficult to preserve using standard fixative methods. The close interaction between cilia and mucus can be observed after instantaneously interrupting the ciliary movement using ultra rapid and cryosubstitution fixation methods. Mucus possess several rheological properties such as pseudoplasticity, elastothixotropy, spinability and adhesiveness. Rheological properties of mucus may control, per se, the ciliary beating frequency. By measuring the mucociliary frequency on the excised mucus-depleted frog palate of native mucus and xanthan gum using a simulant of mucus, we observed that beyond an optimal value of viscosity (close to 12 Pa.s) the mucociliary frequency and transport rate decrease in parallel. Other rheological factors such as adhesion and spinability of mucus can also be implicated in the regulation of the mucociliary transport rate.

Animals↗

PubMed1987

The 99m technetium labeling effect on bacterial surface properties.

The present study was undertaken to determine whether labeling Pseudomonas aeruginosa with 99m Technetium would modify some of the bacterial physicochemical surface properties which play an important role in the interaction between bacteria and eukaryotic cells. No significant difference in electrophoretic mobility or distribution of cationized ferritin on the cell surface was observed between labeled and unlabeled bacteria. Also, the 99m Tc labeling process did not modify bacterial hydrophobicity or adhesiveness to human buccal epithelial cells. It is concluded that bacterial labeling with 99m Tc can be accepted as a useful method for biological research.

Bacterial Adhesion↗

PubMed1987

In vitro restructuring effect of human airway immunoglobulins A and lysozyme on airway secretions.

The in vitro effects of different pure proteins: IgA, IgM and human airway lysozyme (HAL) on rheological and transport properties of airway secretions from patients with chronic bronchitis, were studied. The proteins were added to the reconstituted sputum samples in concentrations within the range present in sputa (IgA: 4% HAL: 1% and IgM: 0.5%). A significant (p less than 0.05) positive increase in apparent viscosity and in elastic modulus was observed after adding IgA or HAL. This suggests that these two secretory proteins contribute to the viscoelastic properties of airway secretions and may act as restructuring molecules. After protein overload of the sputum samples, opposite changes in mucociliary transport rate were observed according to whether the initial values of protein concentration and rheology were abnormally low or high. These results suggest that, as for mucus rheology, there is an intermediate range of IgA and HAL optimal for mucociliary transport rate.

Elasticity↗

PubMed1987

Effect of human airway lysozyme on the in vitro growth of type I Streptococcus pneumoniae.

The effects of purified human airway lysozyme and hen egg-white lysozyme on growth rate and viability of growing type I Streptococcus pneumoniae were studied. Exposure of bacteria to human and hen lysozyme at the same final concentration (100 micrograms/ml) for 1.5-4.5 h resulted in a marked reduction of the number of colony-forming units per ml compared to control cultures. After a 1.5-h exposure to human or hen lysozyme, the remaining percentage of colony forming units per ml was 54% and 69%, respectively. The onset of growth only appeared after a 3.5-h exposure period for human lysozyme whereas it began at 2.5 h for hen lysozyme. After 3.5 h and 4.5 h of exposure, the number of colony-forming units was significantly lower (p less than 0.05) in human lysozyme-treated bacteria cultures compared to control cultures. Parallel electron microscopic observations of Streptococcus pneumoniae cultures confirmed that the density of pneumococci was less in the presence of either human lysozyme or hen lysozyme in comparison to control cultures, and showed the presence of numerous long, ribbon-like material and cytoplasmic condensations liberated in the culture medium.

Bronchi↗

PubMed1986

Characterization and conformational analysis by Raman spectroscopy of human airway lysozyme.

Human airway lysozyme, purified from pathological bronchial secretions, is characterized by a specific activity 3-fold higher than that of hen egg-white lysozyme. The amino acid composition of human airway lysozyme is identical to that of other human lysozymes. The laser Raman spectra of human airway lysozyme and hen egg-white lysozyme in phosphate buffer solution (pH 7.2) are recorded in the range 300-1900 cm-1 at 488 nm. Drastic intensity differences are observed between the spectra analyzed in the ranges characteristic of the peptide backbone (e.g., beta-sheet; C alpha-C, C alpha-N), and of the aromatic side-chain vibrations (tyrosine, tryptophan). The deconvolution of the Raman amide I band gives secondary structures of 38% and 39% alpha-helix, 25% and 20% beta-sheet, and 37% and 41% undefined structure for the human and hen lysozymes, respectively.

Amino Acids↗