Biomedical subjects

A C Pearson

Publications and source records attributed to A C Pearson.

77 records · Page 5Linked to original sources

PubMed1986

Left ventricular diastolic function in weight lifters.

Concentric left ventricular (LV) hypertrophy and asymmetric septal hypertrophy have both been described in weight lifters, but diastolic filling, which is abnormal in pathologically hypertrophied ventricles, has not been investigated in such subjects. Accordingly, pulsed Doppler examination of LV inflow, M-mode and 2-dimensional echocardiography were performed in 16 competitive weight lifters and 10 age-matched male control subjects. Peak and mean filling rates were determined in milliliters per second as the product of the cross-sectional area of the mitral anulus and the Doppler-derived peak early and mean transmitral inflow velocities, respectively. Rapid filling index was defined as peak filling rate divided by mean filling rate. Flow velocity integrals of the early and atrial diastolic filling phases were also measured. LV end-diastolic volume and ejection fraction were measured using 2-dimensional echocardiography. Weight lifters had significantly higher LV end-diastolic volume (181 +/- 50 vs 136 +/- 40 ml, p less than 0.05) and dimension (5.6 +/- 0.6 vs 5.1 +/- 0.5 cm, p less than 0.05), and posterior wall thickness (0.9 +/- 0.2 vs 0.8 +/- 0.1, p less than 0.05); however, after correction for body surface area there was no significant difference in these values. Weight lifters had significantly higher LV mass (241 +/- 70 vs 165 +/- 29, p less than 0.02) and LV mass index (114 +/- 29 vs 87 +/- 15 g/m2, p less than 0.05). There was no significant difference between the weight lifters and control subjects in rapid filling index, early to late integral ratio or ejection fraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1986

Peritoneal macrophages exposed to purified macrophage colony-stimulating factor (M-CSF) suppress mitogen- and antigen-stimulated lymphocyte proliferation.

The effect of M-CSF-exposed macrophages on murine splenic lymphocyte responses was determined. Resident peritoneal macrophages incubated with purified M-CSF for 48 hr inhibited lymphocyte proliferation to Con A, PHA, and listerial antigen as determined by [3H]TdR uptake, and inhibited Con A-stimulated lymphocyte IL 2 production. The inhibition was similar to that observed with macrophages from BCG-infected mice. Maximal suppression occurred at M-CSF concentrations of 500 U/ml or greater and when the incubation time with M-CSF was 48 hr or more. M-CSF effect was specific because rabbit anti-M-CSF IgG blocked the suppression whereas control rabbit IgG did not. Secretory products of macrophages could not be implicated in this interaction. Catalase and indomethacin, alone or together, did not reverse the inhibition. In addition, putative suppressive factors were not detected in supernatants of M-CSF-stimulated macrophages. Lymphocytes that were removed from macrophage monolayers and were recultured in medium plus Con A were able to proliferate. Macrophages stimulated by M-CSF therefore appear to have inhibitory activity for proliferating lymphocytes, and may play a role in immunoregulatory mechanisms.

Animals↗

PubMedDate not supplied

Pacemaker hemodynamics: clinical implications.

Our review of the current literature and experience in caring for pacemaker patients suggests that a consideration of hemodynamics is a logical way to approach pacemaker selection and programming. Multiple clinical factors enter into the selection of a pacemaker or pacemaker programming settings in each case. It appears that in patients with sinus node disease, atrial-inhibited or dual-chamber pacing provides the best chance for preventing the development of chronic atrial fibrillation with its attendant risks of embolism and stroke. It is clear that AV synchrony has beneficial hemodynamic effects at rest in most patients. The results of Labovitz would suggest that in patients with marked left atrial enlargement, this may be less so. The results of Stewart et al would further suggest that in patients with retrograde VA conduction, dual-chamber pacing is preferable. Retrograde VA conduction can be intermittent and this makes it difficult to use its absence on a single test to decide on the type of pacemaker to use. It appears that baseline left ventricular function does not determine the relative improvement in cardiac output observed with AV synchrony or rate-adaptive pacing. However, in patients with severe congestive heart failure even a small improvement in cardiac output may result in significant clinical improvement. Studies have shown that in any given patient, there may be an optimal AV interval at rest. In general, this ranges from 100 to 150 milliseconds. In normal individuals the optimal AV interval shortens with increased heart rate during exercise in a predictable and linear fashion. The hemodynamic benefits of a shortened AV interval with faster heart rates in pacemaker patients have not yet been shown. Intuitively, however, this would appear to be a desirable approach and will probably be added to the design of future generations of dual-chamber pacemakers. Studies of the effect of different pacing modes on secretion of atrial natriuretic factor are intriguing and may contribute more to our understanding of pacing hemodynamics in the future. During exercise, heart rate increase is more important than AV synchrony and this has been shown by several studies. Thus, in active patients with chronotropic incompetence due to sick sinus syndrome, the addition of rate-adaptive pacing is important. Because single-chamber rate-adaptive atrial pacing leaves the patient exposed to the risk of future development of AV block and DDD pacing does not provide chronotropic support, it is likely that the new rate-adaptive dual-chamber (DDDR) devices will be used in a significant number of these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗

PubMedDate not supplied

Tumor invasion of the pulmonary veins: a unique source of systemic embolism detected by transesophageal echocardiography.

Two patients with a malignancy involving the lungs and spontaneous systemic embolization in whom transesophageal echocardiography detected masses consistent with tumor invading the pulmonary veins are reported. In the first patient, tumor embolization resulted in acute aortic obstruction. Transesophageal echocardiography revealed tumor present in the pulmonary veins that extended into the left atrium. This was confirmed by magnetic resonance imaging. The second patient had a stroke. Transesophageal echocardiography demonstrated a mass in the right pulmonary vein in this patient as well. In patients with pulmonary malignancy who have a systemic embolic event, tumor emboli from the pulmonary vein should be included in the differential diagnosis of possible causes of the event. Transesophageal echocardiography is a valuable tool for diagnosis of tumor involvement of the pulmonary veins in such patients.

Adenocarcinoma↗

PubMedDate not supplied

Two-dimensional, spectral Doppler, and color flow imaging in adults with acquired and congenital cor triatriatum.

Four adult patients ranging in age from 37 to 72 years with cor triatriatum diagnosed by two-dimensional, spectral Doppler, and color flow imaging are presented, including a previously undescribed "acquired" form after orthotopic heart transplantation and the oldest documented patient with cor triatriatum. The echocardiographic features of cor triatriatum with use of surface and transesophageal imaging are reviewed, with particular emphasis on the color flow findings. Color flow imaging has simplified the diagnosis and assessment of cor triatriatum, including the demonstration of other often-associated congenital cardiac anomalies.

Adult↗