Articles: animals.
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Animal experiments and clinical trials have shown that the neonatal respiratory distress syndrome (RDS) can be treated effectively by surfactant replacement via the airways. This treatment facilitates the resorption of fetal pulmonary fluid, promotes uniform air expansion of the lungs, enhances gas exchange, reduces the protein leak across the alveolar epithelium, and prevents the development of bronchiolar epithelial lesions during artificial ventilation. Data from recent animal experiments indicate that surfactant replacement prevents epithelial lung lesions also during high frequency ventilation. Surfactant replacement restores blood gases to normal in adult experimental animals with severe respiratory insufficiency induced by repeated lung lavage, suggesting that this type of treatment might be effective in clinical adult RDS.
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The use of a multiple gas rebreathing method for the measurement of cardiopulmonary function in mechanically ventilated neonates was evaluated. The following indices of cardiopulmonary function were assessed in 20 piglets (mean weight, 2.3 kg): 1) pulmonary capillary blood flow (Qc), 2) diffusing capacity for carbon monoxide (DLCO), 3) lung gas volume (FRC), 4) oxygen consumption (VO2), and 5) volume of the pulmonary tissues and capillaries (VTPC), the latter an estimate of total lung water. During mechanical ventilation at zero end expiratory pressure, all rebreathing parameters correlated well with body weight. ⋯ Unlike the situation with the normal piglets, when PEEP was increased from zero to 10 cm H2O in the oleic acid-infused piglets, the values for FRC and VTPC significantly increased. Mean VTPC at 10 cm H2O was 20 +/- 2 ml/kg which correlated well (r = 0.93) with the postmortem total lung water value of 19 +/- 1 g/kg. Thus, multiple gas rebreathing methodology is applicable to studies using small animals.(ABSTRACT TRUNCATED AT 250 WORDS)
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Experimental neurology · Nov 1984
Retrograde and transganglionic degeneration of sensory neurons after a peripheral nerve lesion at birth.
The sciatic nerve of newborn rats (less than or equal to 16 h old) was crushed with a watchmaker forceps. During the first 4 weeks after the injury, examination of ipsilateral L4 through L6 dorsal root ganglia, their dorsal nerve roots, and the dorsal funiculus revealed the presence of degenerating myelin and axons. Chromatolysis was not observed. ⋯ A total loss of about 60% of sensory neurons was found in the L4 through L6 spinal ganglia. About 58 and 64% of the myelinated axons were lost in L4 and L5 dorsal roots, respectively. The remaining perikarya and dorsal root axons were hypoplastic.
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Case Reports
'Atypical pneumonia' due to parakeet sensitivity: bird fancier's lung in a 10-year-old girl.
p6trinsic allergic alveolitis is rare in childhood, with most of the cases reported due to exposure to avian precipitins (Stiem et al. 1966; Dinda et al. 1969; Chandra & Everly Jones 1972; El-Hefny et al. 1980). We report a 10-year-old girl with bird fancier's lung, and suggest that environmental antigens should be sought in children presenting with non-resolving chest disease.
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A procedure is described which disrupts response-reinforcer contiguity and response dependency and which demonstrates how the location of the response dependency in interval schedules can be regarded as a controlling variable in its own right. Rats' lever pressing produced sucrose on a recycling conjunctive fixed-time 30-second fixed-ratio 1 schedule of reinforcement. Reinforcement occurred only at the end of the fixed-time component on this schedule and only if a response had occurred during that component. ⋯ When the location of the response dependency was then restricted to a 10-second period in the middle of the fixed-time component, the pattern was accentuated and response rates increased for all animals, while postreinforcement pauses decreased sharply for two animals. When responding was required in the first 10 seconds of the fixed-time component, responding peaked earlier in the interval for all animals. Response rates were slightly below those in the previous conditions, while postreinforcement pauses were between 2 and 6 seconds across animals.