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Biomedical subjects

D T Mason

Publications and source records attributed to D T Mason.

At least 163 records · Page 9Linked to original sources
PubMed1980

Imaging procedures in the detection of cardiac tumors, with emphasis on echocardiography: a review.

Although cardiac tumors are relatively rare, their diagnosis is important because successful treatment is usually feasible if the diagnosis is made preoperatively. An analysis of 219 reports of cardiac tumors described in the English literature from 1972 through 1977 demonstrated the predominance of benign tumors, in particular myxoma, which is in agreement with past reviews. The methods of diagnosis employed included plain chest films, echocardiography, cardiac catheterization, angiocardiography, and cardiac scintigraphy. Conventional x-ray examination of the chest was abnormal in 83% of cardiac tumors but non-specific and should lead to further evaluation, first by echocardiography. Echocardiography, the most efficient diagnostic procedure for screening possible cardiac tumors, was abnormal in 94% of the cases. Cardiac catheterization was abnormal in 80% of cardiac tumors while definitive detection was made by angiocardiography in 94% of the cases. Cardiac scintigraphy has had limited use in the diagnosis of cardiac tumors, but has been diagnostic in 100% of the cases in a small series of myxomas.

Adult↗
PubMed1980

Freezing and thawing of myosin with no alteration in ATPase activity.

Myosin can be frozen in liquid nitrogen (-70 degrees C) and stored at this temperature for 5 months with no loss in K+, Ca2+, or actin + Mg2+ -stimulated ATPase activities. Furthermore, myosin can be refrozen and thawed in this manner for at least 5 consecutive times with no alteration in ATPase activity.

Actins↗
PubMed1980

Evaluation of transluminal angioplasty of chronic coronary artery stenosis. Value and limitations assessed in fresh human cadaver hearts.

The possibility of increasing reduced blood flow in atherosclerotic coronary obstruction by catheter balloon dilatation offers a nonsurgical approach to relieve clinical coronary stenosis. To assess the ability of effectively dilating such diseased vessels by transluminal angioplasty, we used the Grüntzig balloon-tipped catheter in 12 fresh human cadaver hearts in which the intervention was performed in 21 noncalcified stenotic areas, including each of the three major coronary arteries. Quantitative coronary arteriography documented decreased obstruction of each lesion; luminal diameter increased 58% (1.9 +/- 0.2 mm to 2.8 +/- 0.3; p less than 0.001) and luminal diameter relative to the most proximal normal coronary segment diminished 61% (46 +/- 4% to 18 +/- 3%; p less than 0.001). Angioplasty was most successfully applied in proximal, discrete, noncalcified lesions of the right and left anterior descending coronaries; calcified, tortuous, middle and distal lesions and the left circumflex coronary were entered with difficulty or unapproachable. Histologic examination revealed microanatomic changes, most often endothelial disruption and atheroma compression, but no serious vascular tears. Dilatation beyond normal coronary diameter caused vessel rupture. This study extends elucidation of the value and limitations of percutaneous transluminal angioplasty in the clinical use of this technique in selected patients for relieving coronary obstruction without surgery.

Arterial Occlusive Diseases↗
PubMed1980

Comparative cardiac contractile actions of six narcotic analgesics: morphine, meperidine, pentazocine, fentanyl, methadone and l-alpha-acetylmethadol (LAAM).

Cardiac muscle contractile responses to six narcotic analgesics (morphine, meperidine, pentazocine, fentanyl, methadone and l-alpha-acetylmethadol), at concentrations from 10(-8) to 10(-4) M, both in the presence and absence of the narcotic antagonist, naloxone, were studied in the isolated, isometric cat right ventricular papillary muscle preparation. Measurements of maximum developed tension (T), maximum rate of tension development (dT/dt) and time to peak tension indicated that no major changes in contractile function occurred with any narcotic at concentrations of 10(-8) to 10(-6) M except for small but significant (P < .05) increases in all three parameters at 10(-6) M fentanyl, and small but significant increases in dT/dt at 10(-8) to 10(-6) M meperidine. At 10(-5) M narcotic, dT/dt was significantly elevated in meperidine-treated muscles (+7%), but significantly reduced in muscles exposed to pentazocine (-8%) or l-alpha-acetylmethadol (-11%). For all six narcotics, the 10(-4) M drug concentration resulted in depression of contractile function that was often associated with nonresponsiveness to electrical stimulation. Pretreatment of muscles with naloxone (10(-4) M) did not prevent this reduction of contractile performance except at the highest concentration (10(-4) M) of meperidine. Following removal of drug, contractile performance improved to varying degrees (recovery to 72-97% of control T), except in l-alpha-acetylmethadol-treated muscles, in which there was no recovery of T. Isoproterenol (0.8 X 10(-7) M) elicited a positive inotropic response whether administered in the presence of 10(-4) M narcotic or following narcotic removal. We conclude that narcotic analgesics in high concentrations exert a direct myocardial depressant effect which is not prevented by naloxone and therefore is not mediated by interaction with opiate receptors. Rather, several effects, including myocardial depression, its reversibility by both drug removal and isoproterenol and decreased muscle excitability are consistent with the hypothesis that narcotic analgesics in high concentrations exert nonspecific, local anesthetic effect on the myocardium.

Analgesics, Opioid↗
PubMed1980

In vivo phosphorylation of a cardiac myosin-like protein.

Cardiac myosin heavy chains synthesized in vivo were identified by labeling of N epsilon, N epsilon, N epsilon trimethyllysine with S-adenosyl-L-(methyl 3H) methionine. A similar assessment of in vivo phosphorylation of this myosin fraction indicated that phosphate incorporation may not be occurring in cardiac myosin heavy chains, but rather in another cardiac myosin-like protein which co-purifies with myosin heavy chains.

Animals↗
PubMed1980

Plasma high density lipoproteins and coronary artery disease.

Plasma lipid samples and other atherosclerosis risk factors were related to presence of extent of coronary artery disease (CAD) in 102 consecutive patients undergoing coronary angiography. Thirty-six were without CAD and 66 had angiographically documented CAD. In CAD, high density lipoprotein (HDL) cholesterol was lower and total cholesterol and low density lipoprotein cholesterol were higher than in subjects without CAD. Further, HDL was inversely related to extent of CAD (number of major obstructed vessels). Moreover, decreased HDL was the single most important determinant of CAD among all atherosclerosis risk factors (more so in females than in males). In addition, reduced plasma enzymatic activity of lecithin:cholesterol acyltransferase (LCAT) correlated with the presence and extent of angiographically shown CAD. These findings document the protective effect of elevated plasma HDL against coronary obstructive disease and suggest this salutary action may be related to LCAT mobilization of cholesterol from atherosclerotic lesions.

Arteriosclerosis↗