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Biomedical subjects

P H Wells

Publications and source records attributed to P H Wells.

6 recordsLinked to original sources
PubMed1981

Early diagnosis of myocardial ischemia using the pulmonary arterial catheter.

Standard precordial electrocardiogram (ECG) leads detect transmural myocardial ischemia but are of limited use in detecting subendocardial ischemia. An early increase in the pulmonary capillary wedge pressure associated with abnormal wave forms has been noted in patients with coronary artery disease. This study sought to evaluate the usefulness of the pulmonary arterial catheter during coronary artery bypass graft surgery in detecting early myocardial ischemia. Forty patients with progressive angina pectoris undergoing elective myocardial revascularization were studied whenever one of the following signs of myocardial ischemia occurred: (a) ST-segment depression greater than 1 mm or, (b) wedge pressure tracing developed an abnormal AC wave greater than 15 torr, or V wave greater than 20 torr. Forty-five percent of the patients developed signs of myocardial ischemia. Three patients developed only ST-segment depression, five patients had ST-segment depression and an abnormal wedge pressure tracing, and 10 patients demonstrated only abnormal wedge pressure tracings. The abnormal wedge pressure tracings were associated with significant elevations of wedge pressures, central venous pressures, and triple indices. This study demonstrates that changes similar to those described in awake patients during cardiac catheterization occur under anesthesia. Abnormalities in the wedge pressure tracing may occur before the onset of ECG changes, indicating the development of myocardial ischemia. The changes in left ventricular compliance and subendocardial ischemia could not be predicted in advance by either the extent of coronary artery disease of degree of left ventricular dysfunction.

Cardiac Catheterization↗
PubMed1980

Concurrent effects of microsieve aspiration and the ionophore A23187 on the morphologic characteristics of the surface of normal erythrocytes.

Previous studies using the calcium ionophore A23187 have shown that pathologic changes in erythrocyte shape and deformability can be induced by modest increases in intracellular calcium with the concomitant depletion of cellular adenosine triphosphate. Efforts to modify the cellular response to such ionophore-induced calcium loading by means of environmental and chemical manipulation of the erythrocyte membrane have suggested that the state of the membrane prior to calcium uptake influences the response of the cell. The present investigation used the microsieve aspiration technic to induce membrane tension mechanically prior to calcium loading with A23187, and thereby to evaluate the response of the membrane to another form of stress. Erthrocytes subjected to conditions of membrane tension in the microsieve were found to resist completely the A23187-calcium-induced conversion to echinocytes or spheroechinocytes. These results support the hypothesis that the state of the membrane before calcium loading has a marked influence on the response of the cell. This may be related to the mechanism underlying the development of irreversibly sickled cells in patients with sickle cell anemia.

Anti-Bacterial Agents↗
PubMed1969

Honey bee recruitment to food sources: olfaction or language?

Honey bee recruits locate food sources by olfaction and not by use of distance and direction information contained in the recruitment dance. Recruitment efficiency increases as odor of the food source accumulates in the hive, from hour to hour and from day to day. Flight patterns, landing patterns, bee odor, and Nassanoff secretion apparently do not aid in recruitment of bees.

Animal Communication↗