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V Bairos

Publications and source records attributed to V Bairos.

5 recordsLinked to original sources
PubMed1995

Study of the elastic fibres' framework of the rat lung.

A combination of intravascular resin injection and formic acid incubation was used to study the three-dimensional organization of the elastic fibres of the adult rat lung by scanning electron microscopy (SEM). After SEM observations, the same samples were further processed for transmission electron microscopy (TEM) in order to confirm the presence of the elastic fibres and to complement some aspects of its surface morphology observed under the SEM. Complementary studies by light microscopy (LM) and TEM using specific histochemical methods for the elastic fibres were also performed. The SEM study clearly demonstrated that the cast of the microvasculature acted as a scaffold to preserve the in vivo arrangement of the easily collapsible elastic tissue. The methodology used allowed the observation of a fine framework of elastic fibres representing remnants of the alveolar walls in close association with the capillaries interwoven with the network of elastin. Each thick elastic fibre was composed of a bundle of thin fibres. Some of these thin fibres separated from the main fibre, join other fibres, giving the appearance of an anastomosing net. The interwoven network of elastin and its proximity with the capillaries suggests that the distensibility of the alveolar wall should contribute to the subtle rhythmical change of the alveolar microcirculation at each respiratory movement. On the sub-pleural region of the lung, the elastic fibres were observed forming a continuous and fine mesh network. The elastic fibres linking the walls of the intrapulmonary conducting airways, the vessels wall and the alveolar and sub-pleural elastic network establish an interrelated and interlaced continuous framework, certainly with great physiological implications to the overall process of the mechanics of the lung respiratory function. The methodology applied was a useful tool in order to study the spatial organization of the pulmonary elastic fibres, its branching and close relation with the other lung structures.

Animals↗
PubMed1992

Kinetic modeling of Sendai virus fusion with PC-12 cells. Effect of pH and temperature on fusion and viral inactivation.

We have studied the fusion activity of Sendai virus, a lipid-enveloped paramyxovirus, towards a line of adherent cells designated PC-12. Fusion was monitored by the dequenching of octadecyl-rhodamine, a fluorescent non-exchangeable probe. The results were analysed with a mass action kinetic model which could explain and predict the kinetics of virus-cell fusion. When the temperature was lowered from 37 degrees C to 25 degrees C, a sharp inhibition of the fusion process was observed, probably reflecting a constraint in the movement of viral glycoproteins at low temperatures. The rate constants of adhesion and fusion were reduced 3.5-fold and 7-fold, respectively, as the temperature was lowered from 37 degrees C to 25 degrees C. The fusion process seemed essentially pH-independent, unlike the case of liposomes and erythrocyte ghosts. Preincubation of the virus in the absence of target cell membranes at neutral and alkaline pH (37 degrees C, 30 min) did not affect the fusion process. However, a similar preincubation of the virus at pH = 5.0 resulted in marked, though slow, inhibition in fusion with the fusion rate constant being reduced 8-fold. Viral preincubation for 5 min in the same acidic conditions yielded a mild inhibition of fusogenic activity, while preincubation in the cold (4 degrees C, 30 min) did not alter viral fusion activity. These acid-induced inhibitory effects could not be fully reversed by further viral preincubation at pH = 7.4 (37 degrees C, 30 min). Changes in internal pH as well as endocytic activity of PC-12 cells had small effect on the fusion process, thus indicating that Sendai virus fuses primarily with the plasma membranes.

Animals↗
PubMedDate not supplied

Quantification of elastin from the mouse lung during postnatal development.

Elastic fibers play a vital role in secondary septal development during the process of lung alveolization. The authors present a quantitative study by image analysis and by high-performance liquid chromatography (HPLC) of the mouse lungs'elastic fibers throughout postnatal development. Five mice from birth up to the 21st day of postnatal development and on the 30th day of life were used daily. Their left lungs were collected and processed for observation under light microscopy. The staining was carried by a modification of the Gomori technique. The right lung of each animal was processed for elastin quantification by HPLC. Analysis by linear regression of the two methods' results showed there was a significant positive linear correlation. With this methodology of staining and image analysis we evaluated the normal establishment of the elastic network of the respiratory portion of the lung from birth to adult life. We now have a good model for studying the variations induced by exogenous agents in the synthesis and degradation of the pulmonary elastic fibers.

Animals↗
PubMedDate not supplied

Menkes' kinky hair syndrome: ultrastructural cutaneous alterations of the elastic fibers.

Menkes' kinky hair syndrome is associated with the defective functioning of several copper-dependent enzymes due to impaired copper absorption, transport, or metabolism. Lysyl oxidase is a copper-requiring enzyme that catalyzes the oxidative deamination of lysyl residues linking two adjacent chains of tropoelastin polypeptides into an insoluble network. Elastin of the connective tissue is the responsible protein for the elastic properties of the skin. We report transmission electron microscopy findings concerning elastic fiber alterations of the skin in three patients with Menkes' syndrome. The reticular dermis showed marked changes in the elastic fibers with a paucity of the central amorphous component while retaining normal microfibrillary material. These ultrastructural observations, to the best of our knowledge, are reported for the first time in skin from these patients and may be readily interpreted in terms of a specific biochemical defect in elastogenesis.

Child, Preschool↗