Alveolar Septa

The walls of the distal airspaces have a similar structure whether these are alveoli or alveolar ducts (Kuhn 1985). 

Alterations of the connective tissue composition of the extracellular matrix are an important feature of various inherited and acquired disorders of soft tissue (Miller 1976). This phenomenon is particularly important in the lung in which elasticity is a vital determinant of function. Interstitial collagen is composed of at least two distinct trimeric polypeptide molecules designated as type 1 and type 111 collagens. Type 1 contains two ai(I) chains and one 02 chain, whereas type 111 contains 3 identical a, (HI) chains. Pulmonary fibroblasts produce more type I 

Glutathione and metallothionein protected mouse lung fibroblasts against copper toxicity, as shown in buthionine sulphoxime/Zn-pretreated metallothionein MT-/- mice (Jiang et al. 2002). 

Following a 60-hour exposure of rats to 98 % O2 lung collagen content was reduced by almost 20 % (Riley et al. 1983). Brief periods of hyperbaric hy-peroxia had no influence (Richmond and D Aoust 1976). 

Oxygen metabolites produced by intratracheal instillation of 38 mg xanthine in 0.25 ml sterile phosphate-buffered saline (pH 7.4) plus 100 ng xanthine oxidase in 0.25 ml ice-cold phosphate-buffered saline on day 0 and 38 mg xanthine plus 250 pg xanthine oxidase on day 5 into hamsters increased hydroxyproUne from 903 pg/lung in controls to 1080, 1301, 1195 and 1148 ig/lung at days 12, 19, 26, and 33, respectively (Giri et al. 1988). 

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Increased lung weights accompanied by thickening of the alveolar septa and proliferation of foam cells were observed in male rats that were exposed to 1,000 mg/m3 of DEHP aerosol for 6 hours/day,... 

Rat 28 d (Wistar) 5 d/wk 6 hr/d Resp 50 1000 (increased lung weight, foam cell proliferation, thickening of alveolar septa) Klimisch et al. 1991... 

Watanabe, S., Watanabe, K., Ohishi, T., Aiba, M. and Kagcyaraa, K. (1974). Mast cells in the rat alveolar septa undergoing fibrosis after ionising irradiation. Lab. Invest. 31, 555-567. 

Aerosolized exposure, studied in monkeys, causes acute bronchiolitis within 24-48 h, depending on the size of the particles. After 72 h, inflammation develops in peribronchial tissues and the alveolar septa. Animals exposed to the smaller aerosolized particles developed bronchopneumonia characterized by tracheobronchial lymph node enlargement and 0.2-0.5cm. inflammatory lesions throughout the... 

Morphologically, emphysema is associated with a destruction of the alveolar septum, which results in a dilation and consequent enlargement of the alveolar spaces (Fig. 19). This is apparently caused by a breakdown of the interstitial connective tissue proteins (primarily elastin) that provide the major structural framework of the lung parenchyma. Two types of emphysema have been defined on the basis of the types of destruction of the alveolar septa observed and the type of dilation of the terminal respiratory unit (the acini) that is observed. A typical acinus branches from a terminal bronchiole and consists of the respiratory bronchioles that have alveolated walls and lead to the alveolar ducts and ultimately to the alveolar sacs (see Fig. 3). In centrilobular (or centriacinar) emphysema, the sites of degradation and dilation are limited to the region of the terminal and respiratory bronchioles. In panlobular (or panacinar) emphysema, the entire acinus (including the alveolar ducts and sacs) is more uniformly affected. 

Lung Butylated hydroxytoluene Acute respiratory distress, increased mortality, thickening of alveolar septa, destruction of alveolar architecture, extensive damage to alveolar capillaries, increased lung weight Chan et al. (1999)... 

Within focal regions where fenestration of the alveolar wall and some confluence of air spaces were identified, Belton et al. (1977) found randomised electron dense collagen fibrils, whereas the normal alveolar septa contained uniformly parallel collagen fibrils. Many of the randomised fibrils had sufficient swelhng to display prominent internal spiralling. When the thickened fibrils were cut transversely, the appeared as a stack of flattened, electron dense lamellae. 

While the alveolar capillaries in normal human lungs and in nonthickened alveolar walls of patients with various fibrotic lung disorders gave a negative reaction for Factor VIII this reaction became positive in thickened alveolar septa (Komatsu et al. 1989, Kawanami et al. 1995). 

The activity of extracellular superoxide dismut-ase (EC 1.15.1.1) in mouse lungs is 3- to 10-fold higher than that found in most mammals, and is 30-fold higher than that found in rat lungs (Mar-KLUND 1984). Extracellular superoxide dismutase labelling is strongest in the matrix of vessels, airways, and alveolar septa, especially in the septal tips (Fattman et al. 2000). 

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