Outcome of congenital lung abnormalities detected antenatally

To determine the outcome of congenital lung abnormalities, data were collected retrospectively between January 1991 and December 1996 on any foetus found to have a lung lesion on antenatal ultrasound. A total of 23 foetuses had lung lesions on antenatal ultrasound. In two foetuses the antenatal ultrasound showed bilateral enlarged "bright" echogenic lungs with evidence of hydrops. Both pregnancies were terminated and tracheal atresia was confirmed. In 15 foetuses the antenatal ultrasound appearance was of a unilateral "bright" echogenic lung. There was one case of bronchial atresia and two cases of congenital lobar emphysema, which all had surgery. In nine cases there was a reduction in the size of the lesion on serial antenatal ultrasounds and no lesion was detected after birth. In three cases a small lesion was present after birth on chest radiography. In six foetuses the antenatal ultrasound appearance was of unilateral cystic or mixed cystic and echogenic lung lesions. Two pregnancies were terminated; both had congenital cystic adenomatoid malformation. Four pregnancies were continued and three infants had surgery soon after birth and were confirmed to have had congenital cystic adenomatoid malformation. One infant has been managed conservatively. In conclusion, a definitive diagnosis cannot usually be made antenatally. A large lesion on initial scan does not necessarily predict a poor outcome. The natural history of small asymptomatic postnatal lesions is unknown and a long-term prospective study is needed to determine the outcome of these lesions.     

Cultured endothelial cells maintain their L-arginine level despite the continuous release of EDRF

Endothelial cells cultured from bovine aorta and grown on microcarrier beads contain 107 +/- 9 microM L-arginine (Arg; n = 11). When packed into a jacketed chromatography column and perfused with Krebs solution, the cells showed a substantial and sustained release of endothelium-derived relaxing factor (EDRF) for up to 2 h, which was further enhanced by infusions of adenosine diphosphate (4 microM). In contrast to other amino acids, such as L-alanine, L-aspartate, L-glutamine, L-glutamate or L-serine, which showed a time-dependent decrease to less than 30% of their original level within 2 h, Arg remained at control levels for 30 min and decreased only by 25% after 2 h. Thus endothelial cells can generate Arg from an intracellular source to maintain their Arg level despite the continuous formation of EDRF.     

Differential formation of prostacyclin (PGX or PGI2) by layers of the arterial wall. An explanation for the anti-thrombotic properties of vascular endothelium.

Different layers of rabbit aorta were separated and classified by microscopic examination into intima, internal elastic lamina, media and adventitia. The ability of each layer to produce prostacyclin (PGI₂), a potent endogenous inhibitor of platelet aggregation was investigated. The effect of adding the different layers to platelet rich plasma was studied and correlated with the synthetic capacity to form prostacyclin. Observations were also made after inhibiting prostacyclin formation with 15-hydroperoxy arachidonic acid (15-HPAA). The ability of the arterial wall to generate prostacyclin is highest in the intimal surface and progressively decreases to the adventitial surface. The pro-aggregatory activity of the different layers increased from the internal elastic lamina to the adventitia. These observations may explain the long known anti-thrombotic properties of vascular endothelium and help in the detailed elucidation of the mechanism of formation of intravascular thrombi and haemostatic plugs.     

Regional myocardial dysfunction: evaluation of patients with prior myocardial infarction with fast CT

A prototype ultrafast cine computed tomographic (CT) scanner, designed specifically for cardiac imaging, was used to evaluate a preliminary series of patients with prior myocardial infarction (n = 21) and a control group without coronary artery disease (n = 5). Multilevel 50-msec CT scan exposures were obtained during peripheral intravenous bolus injections of contrast medium. A comparison was made between cine-CT scans and standard left ventriculographic images in assessing segmental left ventricular motion. Results indicate that cine CT, performed at sufficiently rapid speeds (20 scans per second) to allow useful analysis of regional ventricular wall motion, can provide adequate image quality. Analysis of 110 segments revealed a good correlation (90.9%) between the two techniques in characterizing normal from abnormal regional wall motion. Cine CT, based on this initial study, demonstrates considerable potential for evaluating not only cardiac chamber dimensions but also segmental wall dynamics.     

Elimination of prostacyclin (PGI2) and 6-oxo-PGF1 alpha in anaesthetized dogs.

The plasma concentration of 6-oxo-PGF1 alpha was measured by radioimmunoassay after constant rate infusion of 6-oxo-PGF1 alpha or prostacyclin (PGI2) into anaesthetized dogs. A steady-state plasma concentration was rapidly attained with both compounds. After termination of the infusions, the concentration of 6-oxo-PGF1 alpha declined according to a bi-exponential process. The steady-state plasma concentrations of 6-oxo-PGF1 alpha obtained after infusion of 6-oxo-PGF1 alpha and PGI2 were approximately 10 times higher than the corresponding steady-state level of PGF2 alpha measured after infusion of PGF2 alph into the same dogs. The data presented suggest that PGI2 and 6-oxo-PGF1 alpha are eliminated more slowly than PGF2 alpha, probably because they are not taken up and metabolized in the lungs as rapidly as PGF2 alpha.     

Some effects of d-amphetamine on the behavior of pigeons under intermittent reinforcement

Summary The effects of d-amphetamine (0.25 to 8.0 mg/kg) were studied on key-pecking behavior under variable interval (high response rate) and DRL reinforcement (low response rate) in pigeons. Doses of 2.0 mg/kg and above progressively decreased VI responding, as was the case for DRL with doses 4.0 mg/kg and above. No consistent increases in response output on either reinforcement schedule were observed with any dose of the drug, even though prior studies have suggested that amphetamine ought to increase DRL behavior. When their behavior was reduced by d-amphetamine, DRL birds often earned many more grain reinforcements than usual, but frequently did not consume them. No effects of d-amphetamine were observed on a color discrimination tested in the VI birds.We acknowledge the advice of Dr. William B. Morse and Dr. Evalyn Segal, and the expert technical assistance of Peter Gorinsky. This research was performed at the Dept. Pharmacology, Royal College of Surgeons of England and was supported in part by a Public Health Service Special Fellowship (No. MH 25608) to the first author from the National Institute of Mental Health and by NIMH Grant-Number MH-06635 to the Royal College of Surgeons.