PubMed Health⌕ Search

Biomedical subjects

V Ranga

Publications and source records attributed to V Ranga.

7 recordsLinked to original sources
PubMed1991

Effects of ozone on airway epithelial permeability and ion transport.

Ozone is a highly reactive form of oxygen produced in the atmosphere by photochemical reactions involving substrates emitted from automobile engines. Outdoor air concentrations as high as 0.4 parts per million (ppm) occur. The respiratory tract extracts about 90% of inhaled ozone. From the chemical reactivity of ozone, it is expected to attack organic molecules located on or near the respiratory surfaces. The airways are covered with a cohesive layer of epithelial cells that forms the boundary between the external environment and the respiratory tissues. One important role of this epithelial layer is its barrier function. Airborne particles that deposit (and dissolve) in the airway surface liquid are not readily absorbed, and soluble tissue components are excluded from the surface liquid. The epithelium also controls the volume and composition of the surface liquid. One important process in this regard is the absorption and secretion of ions and water. We have studied the effects of inhalation of ozone on the barrier function (permeability to dissolved molecules) and the ion transport activity of epithelium using both in vivo and in vitro techniques. All our experiments were performed with male Hartley strain guinea pigs. Conscious, unrestrained animals were exposed to a concentration of ozone of 1 ppm for three hours in controlled environmental chambers in the Health Effects Research Laboratory, U.S. Environmental Protection Agency (EPA), Research Triangle Park, NC. Such exposures caused a marked increase in the rate of appearance in blood of various water-soluble compounds instilled onto the surface of the trachea, indicating increased permeability of the airway epithelium. This interpretation was supported by electron microscopy, which showed that the tracer molecule horseradish peroxidase was present in the intercellular spaces of tracheal epithelium from ozone-exposed, but not air-exposed (control), animals. However, when the tracheas were excised after ozone exposure and mounted in a tissue bath before measurement of permeability, no increase was found. We suggest that the effect of ozone inhalation on airway permeability requires the action of mediators that are washed out in the in vitro situation. When we exposed animals to 1 ppm for 3 hours daily, we found that the increased permeability in vivo was no longer demonstrable after the fourth exposure. The mechanisms for this type of "adaptation" are not known. The phenomenon recalls the response of human subjects to repeated daily ozone exposures. Ozone exposure caused a sharp increase in active ion transport by tracheal epithelium.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1979

Age-related changes in elastic fibers and elastin of lung.

The effect of age on the lung elastic tissue of inbred BALB/c mice were studied. Static compliance of excised lungs increased with age. Morphometrically determined total elastic fiber length increased with lung expansion in age- and sex-matched mice (r = 0.83, P smaller than 0.001), indicating an axial extension of elastic fibers. However, total elastic fiber length of aging lungs fixed at a distending pressure of 15 cm H2O showed no significant change despite an age-related increase in lung volume (male, r = 0.96, P smaller than 0.001; female, r = 0.95 P smaller than 0.001). The correlative finding of decreased elastin content (r = -0.87, P smaller than 0.001) indicates that there is a loss of elastic fibers in the aging lung. It is suggested that the absence of pseudoelastin fibers, as demonstrated by histochemical techniques, accounts for the observed differences in elastin content of aging human and mouse lungs.

Aging↗
PubMed1978

Effect of histamine and methacholine on guinea pig tracheal permeability to HRP.

The effects of histamine, methacholine, and ether on the permeability of the respiratory mucosa to macromolecules were investigated employing a radioimmunoassay and histochemical techniques to monitor movement of horseradish peroxidase (HRP) from airway lumen to blood. We found that 0.08% of the dose of HRP instilled into guinea pig tracheas was present in the blood volume at 10 min, and plasma HRP levels increased at a rate of 0.0036% instilled dose/min thereafter. After inhalation challenge, significant increases in plasma rates of accumulation of HRP were recorded for the histamine, methacholine, and ether groups, whereas no change in rate was noted for the control (Tyrode's) group. Electron micrographs of tracheal sections showed HRP penetration into the intercellular spaces of the epithelium after histamine, methacoline, or ether exposure but no penetration in the Tyrode's group. We conclude that, like ether, histamine and methacholine increase tracheobronchial permeability and this effect is most likely mediated by a functional change in the epithelial tight junction.

Aerosols↗
PubMed1978

Structure and function of small airways in health and disease.

During the last two decades, great strides have been made in our understanding of the functional aspects of airflow in the periphery of the lung. It seems that the small airways are the important site of obstruction in a variety of chronic respiratory disorders associated with airflow obstruction. This review deals with the anatomic and functional aspects of small airways in normal and diseased lungs. In particular, the basis of obstruction or narrowing that is not dependent on intrinsic airway lesion is reviewed. The variety of pathologic changes in small airways observed in these diseases are outlined along with physiologic tests that are currently used to detect dysfunction at a stage long before they produce symptoms or alter standard tests of lung function.

Aging↗
PubMed1977

Pulmonary resection.

Seventy-seven patients who had elective pulmonary resections were enrolled in a prospective double-blind study to assess the role of prophylactic antibiotics in preventing postoperative infections. Criteria for infection were strictly defined. A five-day course of a cephalosporin (2 gm/day in divided doses) was compared to an identical placebo. There were 17 infections in the 34 patients in the placebo group (50%), compared to only eight infections in the 43 patients in the antibiotic group (19%) (P = .005). When infections unrelated to thoracotomy and minor infections were excluded, the advantage of prophylactic antibiotics proved even more evident. Fourteen thoracic infections occurred in the placebo group (41%) compared to only two thoracic infections (4.7%) in the antibiotic group (P = .0002). No relationship of infection rate to the extent of pulmonary resection was found. A history of smoking, the presence or absence of chronic bronchitis, spirometric abnormalities, and obesity were all analyzed; none was related to the development of infection. We conclude that the routine use of perioperative antibiotics is indicated to prevent postoperative infections in pulmonary resection.

Abscess↗
PubMed1975

Aminoacetonitrile (AAN)prevents connective proliferation in rat liver induced by tetrachlorcarbon. Continuous concomitant administration of AAN.

A total dose of 10 g/kg body weight of aminoacetonitrile distributed almost evenly over 35 days prevents formation of connective bands and damage of hepatocytes in the liver of rats submitted to CCl4 inhalations at a partial pressure of 1/6 atm, eight times within the same interaval. Control animals exhibited the usual pattern of CCl4 injury.

Acetonitriles↗