The effect of bacterial endotoxin on synthesis of (Cu,Zn)superoxide dismutase in lungs of oxygen-exposed rats

Administration of bacterial endotoxin to rats exposed to greater than 95% O2 results in increased lung superoxide dismutase activity, decreased O2-induced lung damage, and a 3- to 4-fold improvement in survival rate (Frank, L., Yam, J., and Roberts, R. J. (1978) J. Clin. Invest, 61, 269-275). Antibodies to rat liver (Cu,Zn) superoxide dismutase were prepared and utilized to investigate the mechanism by which endotoxin treatment leads to increased lung superoxide dismutase activity. Assay of enzyme activity and of immunodetectable enzyme showed that the increased activity is due to an increase in the number of enzyme molecules rather than activation of existing enzyme. Compared to air controls, lung slices from rats exposed to greater than 95% O2 and treated with endotoxin have elevated rats of synthesis of (Cu,Zn)superoxide dismutase (51%) and of total protein (100%). Lung slices from untreated rats exposed to greater than 95% O2 have no such elevations. Endotoxin treatment thus appears to stimulate lung protein synthesis, leading to greater (Cu,Zn)superoxide dismutase activity due to an increased number of enzyme molecules.     

The electrical resistance of the lungs,intercostal muscles,and kidneys in hypertensive ISIAH rats

A comparative study of the bioelectrical impedance of normotensive and hypertensive animal tissues was carried out. It was found that the electrical resistance of kidneys, lungs, and intercostal muscles in rats with arterial hypertension (ISIAH strain) was significantly lower than in normotensive Wistar rats, which indicates that the volume of circulating blood and the total amount of fluid were increased in animals with arterial hypertension. The fact that the resistance of the conducting medium is decreased in arterial hypertension should be taken into account in the analysis of cardioelectric potentials on the body surface and electrocardiograms in conventional leads, as well as for the purposes of the development of heterogeneous torso models and for verification of recovery algorithms for electrical properties of chest tissues.     

The protective effect of melatonin in lungs of newborn rats exposed to maternal nicotine

We investigated possible healing effects of melatonin (MEL) on biochemical and histological changes in the lungs of rat offspring caused by exposure to nicotine (NT) in utero. Pregnant rats were divided randomly into five groups. The SP group was treated with physiological saline. The EA group was treated with ethyl alcohol. The MEL group was treated with MEL. The NT group was treated with NT. The NT + MEL group was treated with NT and MEL. At the end of the study, the biochemistry and histopathology of lung tissue of the offspring were examined. Reduced alveolar development and increased numbers of alveolar macrophages and mast cells were observed in the NT group compared to the SP, EA and MEL groups. We also found increased malondialdehyde (MDA) levels and decreased total glutathione (GSH) levels in the NT group. Application of MEL ameliorated the histological and biochemical damage caused by NT. The number of alveoli was greater in the NT + MEL group than in the NT group. Also, the increased numbers of alveolar macrophages and mast cells resulting from exposure to NT were decreased following MEL treatment. We found that MEL caused a significant decrease in the level of MDA. Maternal exposure to NT caused significant structural and biochemical changes in the lungs of the offspring and administration of MEL ameliorated the changes.     

The effect of asbestos cement, UICC asbestos samples and quartz on the peritoneum of the mouse.]

Aqueous suspensions of asbestos cement powder injected experimentally into the peritoneal cavity of mice act as a fibrogenic agent, as do chrysotile asbestos or chrysotile asbestos-containing soil samples. The fibrotic nodules caused by the dust resemble morphologically silicosis granulomas. In addition, asbestos cement has a characteristically strong cytotoxic effect during the first 2 weeks of the experiment. It is suggested that this is due to the chrysotile asbestos and/or the calcite component of the powder. Amosite and crocidolite, on the other hand, induce a diffuse peritoneal fibrosis with the appearance of numerous foreign body giant cells and asbestos bodies. Dust particles displaced to the regional lymph nodes are frequent in the animals treated with quartz, asbestos cement and asbestos-containing soil samples. A spindle cell type sarcoma arising from the visceral peritoneum is observed in animals injected with crocidolite or asbestos cement. In addition, dusts containing chrysotile asbestos induce considerable amyloidosis of the liver and spleen.     

The effect of inspired oxygen concentration on the ventilation-perfusion distribution in inhomogeneous lungs

The coupled conservation of mass equations for oxygen, carbon dioxide and nitrogen are written down for a lung model consisting of two homogeneous alveolar compartments (with different ventilation-perfusion ratios) and a shunt compartment. As inspired oxygen concentration and oxygen consumption are varied, the flux of oxygen, carbon dioxide and nitrogen across the alveolar membrane in each compartment varies. The result of this is that the expired ventilation-perfusion ratio for each compartment becomes a function of inspired oxygen concentration and oxygen consumption as well as parameters such as inspired ventilation and alveolar perfusion. Another result is that the "inspired ventilation-perfusion ratio and the "expired ventilation-perfusion ratio differ significantly, under some conditions, for poorly ventilated lung compartments. As a consequence, we need to distinguish between the "inspired ventilation-perfusion distribution, which is independent of inspired oxygen concentration and oxygen consumption, and the "expired ventilation-perfusion distribution, which we now show to be strongly dependent on inspired oxygen concentration and less dependent oxygen consumption. Since the multiple inert gas elimination technique (MIGET) estimates the "expired ventilation-perfusion distribution, it follows that the distribution recovered by MIGET may be strongly dependent on inspired oxygen concentration.     

The rate of production of lung liquid in fetal goats, and the effect of expansion of the lungs

Fetal goats (95-155 days of gestation), delivered by Caesarian section, under chloralose (50 mg/kg), with intact umbilical cords, were monitored for lung fluid production by an impermeant tracer method. The average rate of production was 13.4 +/- 2.3 ml/h, or 6.0 +/- 0.9 ml/h per kg. Production rose exponentially towards birth, by both parameters, significant P less than 0.0001 (ml/h), or P less than 0.0005 (ml/h per kg). This indicated an increase in lung liquid production due to both growth and increased activity of the tissues. However, considerable individual variability, even between twins, suggested that this general pattern was modulated by physiological requirements. In 14 fetuses (plus 12 controls), expansion of the lungs with volumes of saline similar to those of the first inspirations (saline, 15-40 ml, matched to the optical density of the lung fluid; inspiration by spirometer, 20-25 ml), caused reduction of secretion or reabsorption of fluid. Secretion changed to reabsorption at about 50% expansion, and the probable physiological limit was estimated at 62-68% expansion. The logarithm of the % fall in production was linearly related to the % expansion (r = 0.88; P less than 0.0001); therefore, small expansions (equivalent to intrauterine breathing) would have little effect, but larger changes such as first breaths, would produce rapidly escalating effects. Controls showed no similar activity. Changes in Na+ and Cl- ions are in parallel to those of water. However, K+ ions moved into the lungs after expansion, in the opposite direction to Na+ ions, and against their concentration gradient. It is suggested that expansion of the lungs activates a Na+/K+ ATP-ase pump to aid reabsorption of salt and water at birth.     

The effect of vidarabine on the development of the offspring of rats, rabbits, and monkeys.

The effect of vidarabine, a new antiviral agent, on the offspring of rats, rabbits, and monkeys was studied by varying routes of administration during several periods of gestation. Vidarabine demonstrated a dose-related teratogenic effect in rats when given parenterally at doses of 30 mg/kg and greater. The drug was also teratogenic in the rabbit at dosages of 5 mg/kg and greater by the parenteral route or when applied topically in 10% concentration to 5 or 10% of the body surface area. The pattern of malformation was similar in the two species, and consisted of multiple, severe abnormalities of the head, trunk, and limbs. The drug had no demonstrable teratogenic effect in a limited study in the rhesus monkey; nor were there adverse effects on the offspring when it was applied intravaginally to pregnant rats in the perinatal period.     

The effect of cigarette smoke on the metabolism of arachidonic acid in isolated hamster lungs

The effects of cigarette smoke on the metabolism of exogenous arachidonic acid (AA) were investigated in isolated hamster lungs. Arachidonate was injected into the pulmonary circulation and the metabolites were analysed from the nonrecirculating perfusion effluent by thin layer chromatography. After the pulmonary injection of 66 nmol of ¹⁴C-AA about 20 % of the injected radioactivity appreated in the perfusion effluent mostly as metabolites in six minutes. When isolated lungs were ventilated with cigarette smoke during the perfusion, the amounts of PGF_2α, PGE₂ and two unidentified metabolite groups increased in the lung effluent. In two other experimental series hamsters were exposed to cigarette smoke before the lung perfusion either once for 30 min or during one hour daily for ten consecutive days. Neither pre-exposures caused any changes in the amounts of arachidonate metabolites in the lung effluent.     

Electron microscopic study of the tissue reaction of lungs exposed to quartz dust of varying dispersity

The tissue reaction of the lungs exposed to quartz dust of varying dispersity was studied by light, transmission and scanning electron microscopy. It is suggested that specific clinical manifestations of dust pathology are related to dispersity of silica. The largest quartz-containing dust particles give rise chiefly to the development of dust bronchitis. The most cytotoxic "medium" fractions lead to appearance of nodular forms of silicosis, whereas highly dispersed dust particles of quartz give rise to the development of diffusive sclerotic changes in the lungs.     

Morphology of the apudocytes and neuroepithelial bodies in the lungs of rats

Endocrine cells (apudocytes) and neuroepithelial bodies (NEBs) were revealed in the lungs of rats of different ages by Grimelius' argyrophilic method. Solitary apudocytes were found among the bronchial epitheliocytes, they had the oval, columnar or triangular shape. NEBs comprise groups of argyrophilic cells, in some cases the penetration of neural fibers into the bodies and their branching in the terminals are observed. Apudocytes and NEBs in 1-, 7-, and 15-day-old rats are more numerous in the epithelium of small than big bronchi. In 21- and 30-day-old and in adult animals apudocytes and NEBs are very scarce. The elements under study are likely to take part in the early postnatal development of the rat lungs.