Search PubMed⌕ Search

Biomedical subjects

R J Bing

Publications and source records attributed to R J Bing.

At least 127 records · Page 7Linked to original sources
PubMed1976

In vivo inhibition of cholesterol uptake in rabbit aortas by 7-ketocholesterol.

The iv injection of 7-ketocholesterol into rabbits, made soluble by combining with bile salts, inhibited cholesterol uptake by the aorta. However, the inhibition was not as marked or as uniform as previously demonstrated in in vitro experiments. This difference may have been the result of lower plasma concentrations of 7-ketocholesterol in the injected animals. Gastric feeding of 7-ketocholesterol failed to inhibit aortic cholesterol uptake, probably because of inadequate plasma concentrations of the inhibitory steroid. The results suggest that the mechanism of 7-ketocholesterol on aortic cholesterol uptake is through competitive inhibition.

Animals↗
PubMed1975

Lipid metabolism in perfused human and dog coronary arteries.

The paper represents a summary of our studies in which in vitro perfusion of human and animal coronary vessels was carried out. Formation and uptake of lipids in perfused human coronary arteries were studied under a vairety of experimental conditions, including exposure to carbon monoxide. The effect of collagenase on lipid synthesis and transport in carotid arteries of dogs was also studied. Human plasma with hydrogen-3-labeled cholesterol and carbon-14-acetate was used to perfuse human blood vessels. Autologous plasma was employed. Inhibition of cholesterol uptake was accomplished by the addition of 7-ketocholesterol (concentrations of 0.005 to 1 mum/ml) to the perfusate. Both atherosclerotic and normal human coronary arteries incorporated 14C-acetate into lipids but failed to synthesize either cholesterol of cholesterol esters. Similar results were obtained in human saphenous veins perfused at arterial pressure. Cholesterol uptake from the perfusion fluid was demonstrated in atherosclerotic and normal human coronary arteries as well as in human saphenous veins. Carbon monoxide increased permeability of the arterial wall to cholesterol uptake. In dog arteries exposed to collagenase marked increases in cholesterol uptake were found, but total lipid synthesis was reduced; the relative synthesis individual lipids remained unchanged. The addition of 7-ketocholesterol to the perfusate reduced cholesterol uptake by the vessel by 90 percent. Inhibition of cholesterol uptake was present in all species and was not due to oxidation of cholesterol to 7-detocholesterol in the perfusate. The results illustrate that human coronary arteries as well as human saphenous veins synthesize lipids but not cholesterol. Cholesterol flux into the artery is augmented by carbon monoxide and collagenase. The data also show that active inhibition of cholesterol uptake in the arterial wall can be accomplished by competitive inhibition with 7-ketocholesterol.

Acetates↗
PubMed1975

Blood flow velocity in the carotid artery as a measure of myocardial contractility.

An attempt was made to derive a useful noninvasive index to evalute a change in myocardial contractile state using transcutaneous Doppler flow-velocity curve from the carotid artery. In 5 mongrel dogs and in 43 patients with various heart disease, Doppler flow velocity curves were obtained from the ascending aorta intravascularly using a Doppler catheter and/or from carotid artery transcutaneously using a Doppler probe. The first derivative of left ventricular pressure (dp/dt) and electrocardiogram (ECG) were recorded simultaneously. The following 3 indices were measured from the Doppler flow-velocity curves: (1) macimum acceleration of blood flow (dv/dt), (2) time from onset of ejection to peak flow (time-to-peak), (3) time interval between the beginning of Q wave of ECG to the peak of Doppler flow velocity curve (ECG Q-Doppler peak). Among these 3 indices, only ECG Q-Doppler peak demonstrated a significant correlation between the values measured intravascularly and transcutaneously. Also, only ECG Q-Doppler peak showed significant correlation with maximum of dp/dt (max dp/dt). Since ECG Q-Doppler peak showed correlation with heart rate, the difference between observed and predicted ECG Q-Doppler peak (delta ECG Q-Doppler peak) was calculated to exclude the effect of heart rate. Predicted value of ECG Q-Doppler peak was calculated from the regression equation between heart rate and ECG Q-Doppler peak in the separate experiments. There was significant correlation between delta ECG Q-Doppler peak and max dp/dt. In 15 patients with coronary artery disease and in 16 healthy subjects, delta ECG Q-Doppler peak and the other noninvasive method (systolic time intervals) were measured. Delta ECG Q-Doppler peak showed better result in the separation of 2 groups than by systolic timeintervals. It was concluded that delta ECG Q-Doppler peak is a useful index to evaluate the myocardial contractile state since this index is readily obtained noninvasively.

Adolescent↗
PubMed1975

Radioisotopic measurements of coronary blood flow.

This review has presented a critical evaluation of current methods used in measurement of total and regional blood flow. Measurement of total coronary blood flow furnishes little evidence of pathological processes within the coronary vascular system. However, in conjunction with coronary vasodilators, measurement of total coronary blood flow may indicate the presence of coronary artery disease. Difficulties inherent in the determination of regional coronary blood flow lie primarily in defining clearance slopes and in the presence of accidental counts. More promising are methods using scintigraphs obtained with radioactive particles injected into the coronary artery. However, these procedures do not measure flow, only flow distribution. A procedure for measuring regional uptake of positron emitters by coincidence counting has been described; the method possesses definite advantages over other procedures, since it is noninvasive and appears to have good resolution. However, the method is dependent on higher decay density which necessitates the use of nuclides with a short half-life (e.g., 81rubidium).

Animals↗
PubMed1975

Coincidence and noncoincidence counting (81Rb and 43K): a comparative study.

This paper compares the accuracy of imaging and resolution obtained with 81Rb and 43K using coincidence and noncoincidence counting. Phantoms and isolated infarcted dog hearts were used. The results clearly show the superiority of coincidence counting with a resolution of 0.5 cm. Noncoincidence counting failed to reveal even sizable defects in the radioactive source.

Animals↗
PubMed1975

Mitochondrial function and excitation-contraction coupling in the development of alcoholic cardiomyopathy.

The effect of prolonged adminstration of ehtanol on cardiac metabolism, contractility, and ultrastructure was investigated. Dogs received 400 ml of a 25 percent solution of ethanol during a period of 3-6 months. Repeated heart muscle biopsied revealed a significant diminution in the activity of intramitochondrial NAD-linked isocitrate dehydrogenase in the animals exposed to alcohol. Oxidative, phosphorylation of mitochondria was measured polarographically using a vibrating oxygen electrode; respiratory control index and mitochondrial oxygen consumption were markedly reduced (p less than 0.001). Myocardial ATP content was significantly diminished (p less than 0.025). Electron microscopic changes observed consisted of mitochondrial degeneration, dehiscence of intercalated discs, and dilatation of intercellular spaces. The average force velocity curve was shifted downward and to the left in afterloaded contractions with a significant depression of Vmax (p less than 0.01). Both calcium binding and calcium uptake of mitochondria and sarcoplasmic reticulum were inhibited. These results suggest that a disorder in the generation of energy and a defect in calcium binding by subcellular membranes may be the determinant events leading to impaired myocardial function in the course of chronic alcoholism.

Adenine Nucleotides↗