Selection of a therapeutic agent for the treatment of chronic obstructive pulmonary disease in smokers.
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Biomedical subjects
Publications and source records attributed to G M Turino.
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Intratracheal instillation of bleomycin in hamsters initiates a series of events that mimic human interstitial pulmonary fibrosis. Because glycosaminoglycans and particularly hyaluronan (hyaluronic acid, HA), may play an important role in the extracellular matrix response to early injury and subsequent fibrosis, this study was undertaken to define the early time course of changes in HA and hyaluronidase. Hamsters were given either 1 unit bleomycin sulfate in 0.2 ml saline or 0.2 ml saline (control), and randomly selected animals from both groups were killed at Days 3, 5, 6, 7, 9, and 17. Glycosaminoglycan fractions prepared from lung tissue of individual animals were analyzed for HA. The maximal HA content was reached 6 days after instillation of bleomycin and was 14.6-fold the normal value. The weight of injured lungs was 2.3-fold the control value. Thus, the increase in HA content was 30-fold. By Day 7 the HA content had dropped sharply. It then declined gradually to approximately double control values at Day 17. The specific activity of lysosomal hyaluronidase was the same in bleomycin-treated lungs and control lungs. Total units of the enzyme were increased in injured lungs, even at the time of maximal HA content, indicating active turnover of HA. The maximal HA content occurs prior to the rise in collagen and elastin biosynthesis. This observation in addition to the magnitude of the increase and its abrupt decline suggest that HA may be an important initiating factor for pathologic changes in lung extracellular matrix components.
Hyperoxia is routinely administered to patients with severe emphysema. To gain insight into the possibly adverse effects of such treatment, hamsters were exposed to 60% oxygen for 5 days, beginning 48 h after induction of pulmonary emphysema by intratracheal instillment of pancreatic elastase. Control groups consisted of (1) animals instilled with elastase and exposed to room air, (2) animals instilled with saline and exposed to 60% oxygen, and (3) animals instilled with saline and exposed to room air. Cross-linked elastin content and synthesis in the lung were measured immediately following termination of hyperoxia, and the mean linear intercept was determined 4 wk later. Cytologic examination of bronchoalveolar lavage fluids was also performed. Statistical significance was determined by a two-way analysis of variance. Results indicate that exposure to 60% oxygen significantly affected (p less than 0.05) air-space size, causing a 51% increase among elastase-treated hamsters (124 versus 82 microns) but only a 4% increment among saline-treated animals (52 versus 50 microns). When compared to other groups, animals treated with both elastase and hyperoxia had a significantly greater (p less than 0.01) percentage of neutrophils (28%) in their lung lavage fluids immediately following exposure to 60% oxygen. Although total lung elastin content was not altered by hyperoxia at this time, labelling of elastin cross-links was significantly increased (p less than 0.05). These studies demonstrate that exposure to 60% oxygen enhances elastase-induced lung injury. They also raise the possibility that oxygen therapy may, under certain circumstances, accelerate the progression of human emphysema.
A strain of endothelial cells derived from a single cell cloned from a line of normal adult rat lung parenchyma has been maintained in tissue culture for more than 3 years. These cells have been identified as endothelial cells based on the combination of their growth characteristics, cell morphology as observed with both light and electron microscopy, and their physiological properties. They have continued to produce granules, which stain specifically for glycosaminoglycans with Alcian blue, for over 2 1/2 years. During the same period of time, glycosaminoglycans were identified biochemically in both cells and medium. They have maintained the ability to degrade bradykinin over this period as well.
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Administration of 200 mg of D-galactosamine/kg intraperitoneally to rats produced a decrease in the serum concentrations of trypsin and elastase inhibitory capacities. Induction of emphysema by intravenous injection of pancreatic elastase resulted in significantly increased severity of the disease in the animals depleted of alpha 1-antitrypsin. The degree of severity of the disease determined by mean linear intercept suggested a correlation with trypsin and elastase inhibitory capacities at the time of elastase injection.
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Antibodies were developed in rabbits against an established line of endothelial cells from normal adult rat lung. Pre- and postimmunization sera were tested for antibody activity by the indirect immunofluorescence technique. Preimmunization serum failed to react with the endothelial cells, whereas the antibody titer of postimmunization serum from two rabbits was 1:512. Organ specificity and species specificity were assessed by absorbing the serum with packed dissociated cells from different organs of the rat and lung cells of other species. Only cells obtained from rat lung absorbed the antibodies completely. The antiserum showed some crossreactivity with the other cultured cells but the pattern of fluorescence was different. In the presence of complement the antiserum was found to be cytotoxic to cultured rat lung endothelial cells but not to the other crossreacting cells.
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The relationship between right duct lymph flow and extravascular lung water was studied in 3 normal dogs and 15 dogs with pulmonary edema induced by alpha-naphthylthiourea (ANTU). Right duct lymph was collected in a pouch created by ligating jugular, subclavian, and brachiocephalic veins. Extravascular lung water was measured in vivo by double indicator dilution and post-mortem by weighting lungs before and after drying. Cardiac output, pulmonary artery and pulmonary artery wedge pressures, and the concentration of protein and electrolytes in plasma and right duct lymph were determined. Eight lungs were examined by light and electron microscopy. There was a direct relationship between right duct lymph flow (RDLF in milliters per hour per gram dry lung) and extravascular lung water (Qwl in milliliters per gram dry lung) which was best described by the equation RDLF=0.75-0.26 Qwl+0.03 (Qwl).2 Dogs with severe ANTU-induced edema had extensive lung capillary endothelial destruction but only mild interstitial swelling and no visible damage to type I alveolar epithelial cells. Cardiac output, pulmonary artery and wedge pressures, and protein and electrolyte concentrations did not correlate with either extravascular water or right duct flow. Thus, in ANTU-induced pulmonary edema right duct lymph flow was directly related to extravascular lung water with the highest flows occurring with severe edema. The absence of a rapid increase in lymph flow with small increases in extravascular water may be due to early sequestration of fluid in the alveolar space. Hemodynamic changes did not account for changes in lung water or lymph flow. The pulmonary interstitial factors relating increased extravascular water to lymph drainage remain to be determined.
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More complete understanding of the disturbances in the regulation of ventilation in disease must await techniques which can estimate the neural output of the respiratory centers and also the neural inputs. Some of these techniques, such as diaphragmatic electromyography, offer the prospect of clinical usefulness even now and newer techniques, such as mouth occlusion pressure, are promising but have just begun to be evaluated in disease. Despite the limited ability of current techniques to clearly distinguish abnormal central nervous system function of ventilatory control from peripheral mechanical limitations to ventilation, a useful interpretation of clinical tests of ventilatory responsiveness may be gained by an awareness of the many physiologic and pathogenetic factors which are interposed by disease. These factors may reinforce or diminish both stimuli and response. In chronic disease states, these modifying factors must be identified and evaluated for their role in altered ventilatory responsiveness. Frequently, therapeutic measures can induce substantial effects on these modifying factors, whereas primary disturbances of central nervous system function may be difficult to alter. For the above reasons, tests of ventilatory responsiveness which provide information focussed only on the normality or abnormality of responsiveness to CO2 breathing from measurement of minute ventilation and alveolar PCO2 in an unsteady state, as in the CO2 rebreathing test, may, in a patient, require the addition of tests which allow more complete evaluation of these modifying factors. The state of arterial blood gases, hydrogen ion concentration, bicarbonate concentration, pulmonary function, ventilatory response to exercise, as well as understanding of the state of body temperature, catecholamine secretion, the functional state of the muscles of ventilation, as well as the resistances to ventilation are all a necessary part of the evaluation.
The glycosaminoglycans produced by a mixed cell line of normal adult rat lung and an endothelial clone derived from this line were isolated and examined. Cellulose acetate electrophoresis of media and cells before and after digestion with specific enzymes indicated that all the major glycosaminoglycans except keratan sulfate were synthesized by both cultures. Heparan sulfate and dermatan sulfate were found only in the cell fraction while hyaluronic acid was found in both the medium and the cell fractions. The chondroitin sulfates were isolated from the medium. The endothelial clone produced a 4:1 ratio of glucosamine to galactosamine in the medium from the fifth through thirteenth months of culture. The medium of the mixed cell line initially contained glycosaminoglycans with a glucosamine to galactosamine ratio of 2:1 but after approximately one year of culture, the ratio had changed to 4.6:1 suggesting that the culture contained predominatly endothelial cells.