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K J Chung

Publications and source records attributed to K J Chung.

48 records · Page 3Linked to original sources
PubMedDate not supplied

Ketone bodies maintain normal cardiac function and myocardial high energy phosphates during insulin-induced hypoglycemia in vivo.

It has been suggested that myocardial utilization of ketone bodies might cause deterioration of cardiac function. Therefore, the influence of ketonemia (mean: 1.3 and 3.3 mM) in the presence of hypoglycemia (mean: 33 mg/dl) on cardiac function, substrate utilization and myocardial high energy phosphate levels was studied in 10 mongrel dogs. Hypoglycemia alone led to a significant increase of mean aortic pressure, total peripheral resistance and myocardial oxygen consumption, but other hemodynamic parameters and regional myocardial function were not changed. Additional infusion of 3-hydroxybutyrate did not affect hemodynamic variables significantly. During both metabolic interventions in vivo phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy showed stable levels of myocardial Pi, PCr, ATP, as well as PCr/Pi (3.2-3.4) and PCr/ATP (3.0-3.2) ratios. Biochemical measurements revealed that ketonemia led to significant alterations in arterial concentrations and arterio-coronary venous differences of selected citric acid cycle intermediates, thus confirming previous reports which suggested a blockade of the 2-oxoglutarate-dehydrogenase reaction induced by ketone body oxidation. However, despite this blockade, the energy supply to the heart was not impaired as shown by normal NMR spectroscopy and cardiac performance. It is speculated that the blockade might be due to an enhanced NADH/NAD ratio.

3-Hydroxybutyric Acid↗
PubMedDate not supplied

Flow analysis with digital subtraction angiography: 1. Description of a simplified flow model.

An inexpensive, simplified flow model for use with digital subtraction angiographic (DSA) equipment is described. System tests show that the model gives reproducible data with a standard deviation of +/- 2.6%. Flow analysis also reveals an appropriate response to flow rates of 20-240 ml per min. The flow model can be used to investigate many of the variables and sources of error in DSA flow measurements.

Angiography↗
PubMedDate not supplied

Flow analysis with digital subtraction angiography: 2. Acquisition and accuracy of transit-flow measurements.

A steady-state flow model was used to optimize methods of data analysis, to investigate variables that affect the time-density curves, and to determine the accuracy of transit-flow measurements with digital subtraction angiography. The most accurate data were obtained by using a small region of interest placed within the vessel, averaged data acquisition, and a gamma-variate fit applied to the time-density curve. The integrated area of the curve depended on the flow, vessel size, amount of iodine injected, framing rate, and the kVp. The integrated area was not affected by the mAs; the matrix size; or the volume, concentration, or rate of injection of the contrast material. Subject density, image intensifier mode, and field size did not affect the curves except for their contribution to scatter and beam hardening. There was good correlation between digital subtraction angiographic transit-flow measurements and known flow values.

Angiography↗