Thorax
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We induced chronic pulmonary hypertension in one group of rats by exposing them to chronic hypobaric hypoxia (380 mm Hg for three weeks) and in another group by administering a single subcutaneous dose of monocrotaline (60 mg/kg body weight). Both groups of rats showed increase of the right ventricular mean systolic blood pressure and right ventricular hypertrophy. We measured the surface area of histological sections of the left or right lungs and counted all small blood vessels with an external diameter of less than 50 microns and with a definite elastic coat lying distal to respiratory bronchioles. ⋯ The mean total number of small pulmonary blood vessels in nine rats with monocrotaline-induced pulmonary hypertension was 396.8 +/- 61.7 compared with 384 +/- 55.4 in three control rats. The number of small pulmonary blood vessels per mm2 lung tissue was 3.3 +/- 0.6 in the rats treated with monocrotaline compared with 3.6 +/- 0.6 in the control group. We conclude that the number of small pulmonary blood vessels is not reduced in rats with pulmonary hypertension induced by chronic hypoxia or monocrotaline.
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Randomized Controlled Trial Comparative Study Clinical Trial
Tracheal damage after endotracheal intubation: comparison of two types of endotracheal tubes.
Twenty-eight patients who required endotracheal intubation for open-heart surgery were randomly allocated to one of two types of endotracheal tube. The tracheal mucosa was examined with a fibreoptic bronchoscope at the time of extubation, usually 24 hours after operation. The degree of oedema, inflammation, and ulceration was scored by the bronchoscopist, who also photographed the whole length of the trachea. ⋯ Both observers found significantly less mucosal damage with the low-pressure, high-volume type of cuff than with the traditional high-pressure, low-volume type. This difference may be related to the differences in lateral wall pressures exerted by the two types of cuff. The low-pressure type of cuff may be preferable in patients requiring prolonged endotracheal intubation.
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Biography Historical Article
Robert Koch: centenary of the discovery of the tubercle bacillus, 1882.
This is an account of the life and work of Robert Koch (1843-1910), Nobel Laureate in Medicine and a founder of the science of bacteriology. In particular, Koch's researches into tuberculosis are described--the discovery of the tubercle bacillus, the controversy regarding the human and bovine types, the Koch phenomenon, and the introduction of tuberculin, which proved to be ineffective as a cure but became important as a diagnostic tool in the management of tuberculosis. By his achievements in this field, Koch may be considered to be the father of the scientific study of tuberculosis. On the occasion of the centenary of Koch's discovery of the tubercle bacillus in 1882, we pay tribute to this great German master of medicine.
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Comparative Study
Angiotensin converting enzyme activity and evolution of pulmonary vascular disease in rats with monocrotaline pulmonary hypertension.
We have investigated the role of angiotensin converting enzyme (ACE) in the development of pulmonary hypertension, right ventricular hypertrophy, and pulmonary vascular disease in rats given a single subcutaneous injection of the pyrrolizidine alkaloid monocrotaline. Thirty-six young female Wistar rats were divided into a test group of 27 animals and a control group of nine animals. Each test rat was given a single subcutaneous injection of monocrotaline (60 mg/kg body weight). ⋯ Serum ACE activity was unchanged. It is concluded that the reduction in lung ACE activity is a result rather than a cause of the pulmonary hypertension. This reduction in lung ACE activity may be a protective mechanism designed to limit the elevation of the pulmonary arterial pressure.
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Most measurements of pulmonary blood volume have been based on the Stewart-Hamilton dye dilution principle and have required direct catheterisation of the cardiac chambers. Alternatively a precordial counter may be used to detect the composite right and left heart curves after an intravenous injection of radionuclide. We investigated the use of a gamma camera/computer system to determine the radionuclide dilution curves from individual cardiac chambers. ⋯ The effect of posture on pulmonary blood volume was determined in six subjects lying supine and tilted at a 45 degree angle. A reduction in pulmonary blood volume in the tilted position was observed in each subject (p less than 0.005). This simple non-invasive measurement should allow more detailed assessment of physiological or pharmacological changes of the pulmonary vascular bed.