Search PubMed⌕ Search

Biomedical subjects

R A Waugh

Publications and source records attributed to R A Waugh.

48 records · Page 3Linked to original sources
PubMed1978

Comparative stereology of the mouse and finch left ventricle.

The volume fractions and surface per unit cell volume of some subcellular components of the left ventricles of the finch and mouse were quantitated by stereologic techniques. These species were chosen for study because they have similar heart rates but differ morphologically in some respects: fiber diameter is larger in the mouse; the mouse has transverse tubules while the finch does not; and the finch has a form of junctional sarcoplasmic reticulum (JSR), extended JSR (EJSR), located in the cell interior with no direct plasmalemmal contact, while the mouse interior JSR (IJSR) abuts on transverse tubules. Our data show that the volume fraction (Vv) and surface area per unit cell volume (Sv) of total SR, and free SR (FSR) are similar. The volume fractions of mitochondria, myofibrils, and total junctional SR were also similar. The Sv of the cell surface of the finch was similar to the Sv of the cell surface of the mouse (Sv-plasmalemma plus Sv of the transverse tubules). The principal difference was in the distribution of JSR; the mouse peripheral JSR (PJSR) represents only 9% of the total JSR, while the finch PJSR accounts for 24% of the bird's JSR. The similar volume fractions of total junctional SR (PJSR + EJSR in the finch; PJSR + IJSR in the mouse) suggest that the EJSR is not an embryologic remnant, and raises the possibility that some function of JSR is independent of plasmalemmal contact.

Animals↗
PubMed1978

Effect of phasic respiration on left ventricular dimension and performance in a normal population. An echocardiographic study.

Echocardiographic examination of the left ventricle (LV) in 30 normal subjects, 5 to 47 years of age, was performed in order to analyze the effects of phasic respiration on LV dimensions and derived LV function. Peak expiratory and peak inspiratory LV diastolic and systolic dimensions were measured and extrapolated to volume estimates using a standard formula. Although there was wide variation in the individual measurements, and particularly in systolic dimension, the mean peak inspiratory diastolic dimension, derived diastolic volume, and stroke volume all decreased significantly (P less than 0.001); a smaller decrease in ejection fraction was seen (P less than 0.02), while the changes in mean end-systolic dimension and end-systolic volume were not significant. While these observed changes may reflect a true physiologic variation, an artifactual component cannot be excluded. Regardless of their physiologic significance, however, these data show that the effect of phasic respiration is a factor to be considered in correlative echocardiographic studies of LV function in both normal and, possibly, pathologic cardiovascular conditions.

Adolescent↗
PubMed1978

Ultrastructure of heart muscle.

The ultrastructure of cardiac muscle is described. In the course of the descriptions advantage has been taken of comparative anatomy, in order to elucidate the relationships between structure and function. Physiologic parameters are discussed in a comparative manner including information from skeletal muscles fibers that often provide a well-studied point of departure. The descriptions of the ultrastructure of cardiac muscle are illustrated by a few electron photomicrographs to give a general overview.

Animals↗
PubMedDate not supplied

Association of physical fitness and transient myocardial ischemia in patients with coronary artery disease.

PURPOSE: To examine the relationship between physical fitness and transient myocardial ischemia (TMI) in the laboratory and during daily life, in a sample of coronary patients with a recent positive exercise test. METHODS: 47 patients with coronary disease (CAD) participated in laboratory mental and exercise stress testing and 48-hour outpatient Holter monitoring after being withdrawn from ant-ischemic medications. During laboratory testing, left ventricular performance was assessed by radionuclide ventriculography. Physical fitness was assessed by measurement of oxygen consumption during symptom-limited exercise treadmill testing. RESULTS: Higher physical fitness subjects were less likely to exhibit wall-motion abnormalities in response to mental stress (P < .05), and to exercise stress (P < .05) testing. They also had smaller decreases in left ventricular ejection fraction (LVEF) in response to mental stress than less fit subjects (P .056), and exhibited a mean increase in LVEF during exercise, compared to the less fit subjects who exhibited a decrease in LVEF (P < .02). Moreover, higher fit subjects exhibited fewer episodes of TMI (P < .04), for a shorter duration (P < .04), and less total ischemic burden (P < .04) during Holter monitoring. CONCLUSION: These findings suggest that within a population of CAD patients, higher levels of physical fitness are associated with less TMI assessed in the laboratory and during routine activities of daily living.

Adult↗