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Biomedical subjects

L M Pang

Publications and source records attributed to L M Pang.

25 records · Page 2Linked to original sources
PubMed1978

Gestational changes in pulmonary converting enzyme activity in the fetal rabbit.

Changes in angiotensin-converting enzyme were measured in the lungs of fetal rabbits isolated and perfused in situ at varying ages from 22 days gestation to 7 days of age under controlled conditions of flow, pH, and temperature. Enzyme activity was assessed by infusing bradykinin or angiotensin I in Krebs-Henseleit solution and measuring residual peptide in the effluent by radioimmunoassay. The levels of substrate studied were below those required for enzyme saturation. Lungs of 22 day gestation fetuses removed only one-third of either peptide. The activity at term and in neonatal life resulted in more than 80% peptide removal. The time of the greatest rise in the percent substrate cleared occurs earlier than the time of the greatest increase in lung and body weight. The lower percentage of substrate cleared in early gestation appears to result in part from a limited surface area for enzyme activity in the primitive fetal pulmonary microvascular bed, since morphological studies with fluorescein-tagged anticonverting enzyme antibody demonstrated the presence of enzyme in the lung as early as 17 days of gestation. Electron micrographs of the pulmonary endothelial cell surface reveal that the degree of surface infolding and hence surface area increases with gestation. The higher percentage of substrate cleared in later gestation closely parallels the structural and ultrastructural development of the vascular bed. The presence of converting enzyme in the placenta by the second third of gestation and the large size of the placenta suggest that this organ may be a major locus of converting enzyme activity in the fetus.

Angiotensin I↗
PubMed1977

Terbutaline in the treatment of status asthmaticus.

The effect of administration of terbutaline on the pulmonary and cardiovascular systems was studied in ten children with status asthmaticus. Terbutaline (0.01 to 0.04 mg/kg of body weight) was given subcutaneously in multiple doses. A significant decrease in respiratory rate and in arterial blood pressure, with no significant change in cardiac rate, was seen only after the first dose of terbutaline. There was a decrease in mean arterial carbon dioxide tension and an increase in mean arterial oxygen pressure. There was gross clinical improvement following administration of terbutaline in nine of the ten patients. One patient who failed to respond to administration of terbutaline also failed to respond to intravenously administered isoproterenol. We conclude that terbutaline is effective in the treatment of status asthmaticus, with only modest effects on the cardiovascular system.

Adolescent↗
PubMed1977

Terbutaline in the treatment of acute asthma in childhood.

Forty-eight children with known asthma (ranging in age from 2 to 16 years) were studied during an acute attack. Each received either terbutaline or epinephrine subcutaneously in a random double-blind fashion. Measurement of heart rate, respiratory rate, and systemic arterial systolic and diastolic blood pressures and careful clinical assessment of obstruction of the airway were made before and at 15, 30, and 60 minutes after the administration of the drugs. Appreciable and significant clinical improvement was noted in 19 of the 24 patients in both groups and was of comparable magnitude. A small, but significant, increase in heart rate was noted in those patients requiring only one injection of terbutaline, suggesting that the drug's selectivity for the lung is relative not absolute. The present study demonstrates that terbutaline is an effective bronchodilator drug in acute childhood asthma.

Acute Disease↗
PubMed1975

Experimental coronary arterial occlusion and release. Effects on enzymes, electrocardiograms, myocardial contractility and reactive hyperemia.

After less than 1 hour of coronary arterial occlusion, the myocardium suffers irreversible changes as revealed by electron microscopy. Yet, the earliest clinical laboratory indexes of myocardial infarction--elevated serum enzyme levels and significant Q waves on the electrocardiogram--are not detected until at least 6 hours after coronary occlusion. To study the early period after coronary occlusion in the dog, occlusion of the left anterior descending coronary artery for 1 to 3 hours was followed by release, and coronary sinus and venous enzyme levels, the electrocardiogram and myocardial contractility from the infarcted area, and reactive hyperemia were monitored. Coronary sinus enzyme levels rose within 15 minutes after release of occlusion in half of the experiments with 1 to 1 1/2 hours and in all of those with 2 to 3 hours of occlusion, and this rise preceded the rise in venous levels by only 10 to 20 minutes. Significant Q waves appeared 15 to 30 minutes after release of occlusion as the serum enzymes were increasing. Thus, clinically, the delayed appearance of increased serum enzymes and significant electrocardiographic Q waves is probably largely due to a lack of circulation in the infarcted area rather than to prolonged survival time. Also, the venous enzyme level reflects the coronary sinus level minutes later. The presence of viable myocardium in the infarcted area was suggested by elevation of the S-T segment upon reclamping, and by residual myocardial contractility and retained capacity for reactive hyperemia. These findings occurred in some experiments even in the presence of a significant Q wave.

Animals↗
PubMed1975

Effect of acute lymphatic obstruction on fluid accumulation in the chest in dogs.

The effect of acute obstruction to lymphatic drainage on fluid accumulation in the lungs, pleura, and pericardium was assessed in the intact dog. Catheters were positioned in the venae cavase, right atrium (RA), left atrium (LA), age on fluid accumulation in the lungs, pleura, and pericardium was assessed in the intact dog. Catheters were positioned in the venae cavae, right atrium (RA), left atrium (LA), and aorta (Ao) of nine anesthetized, spontaneouly breathing dogs, and hydrostic and colloid osmotic pressures were continuously monitored. Lymphatic obstruction was achieved by raising systemic venous pressure to either 10 mmHg or 25 mmHg by a combination of fluid infusion and inflation of balloon catheters in the venae cavae for 2 h. The same constant net intravascular filtration pressure was maintained in both groups by appropriate use of saline or colloid-containing fluids. Pleural and pericardial fluids were measured postmortem and lung water content was determined by weighing before and after drying. Failure to detect greater fluid accumulation at the higher obstructing pressure (25 mmHg) than at the lower obstructing pressure (10 mmHg) suggests that over the range of obstructing pressures used there is no acute change in the magnitude of lymphatic drainage in the chest.

Animals↗
PubMedDate not supplied

Preemptive analgesia in children. Does it exist?

BACKGROUND AND OBJECTIVES: Preemptive analgesia has been evident in animals, but few adult human studies exist demonstrating this concept exist, and there are fewer still in children. Caudal epidural blocks with local anesthetics are often placed for postoperative analgesia in children. This study evaluated whether these blocks are more effective when placed prior to surgical incision. METHODS: Children aged 1-6 years and ASA I and II (n = 51), undergoing elective herniorrhaphy, orchidopexy, or circumcision were randomly assigned to receive a caudal epidural block with 0.6 mL/kg of 0.25% bupivacaine with 1:200,000 epinephrine, either before incision (n = 28) or after surgery (n = 23). In all patients, anesthesia was induced and maintained with oxygen, nitrous oxide, and halothane, and caudal epidural blocks were placed. Postoperative pain was scored by a blinded observer using a Faces Pain Scale in the recovery room and was also assessed at home by the parents. Analgesic requirement during the 24-hour period was recorded. RESULTS: The Faces Pain Scale scores and analgesic requirements did not differ between the groups, either in the recovery room or at home (P > .05). CONCLUSIONS: Although preemptive analgesia has been successfully demonstrated in some earlier clinical studies, our results indicate that pre- and postincisional caudal epidural blocks with 0.25% bupivacaine were equally effective in children.

Abdomen↗