Evidence is presented that caffeine does not act on the mitochondrial Ca uptake system and that its effect cannot be attributed to the accumulation of adenosine 3',5'-phosphate. Two distinct caffeine effects are described. At high ATP concentrations caffeine decreases the coupling between ATP hydrolysis and Ca inflow. It either inhibits inflow without any inhibition of the rate of ATP hydrolysi...

In managing a multipurpose dam, knowledge of inflow is essential in planning and scheduling discharges for optimal power production and irrigation supply, and flood control. Utilization of satellite imagery improves inflow estimates provided by digital spatial data instead of those from calculations on drawn maps; the former yields measurements over an area instead of extrapolations from point ...

BACKGROUND Due to the different properties of the contrast agents, the lung perfusion maps as measured by 99mTc-labeled macroaggregated albumin perfusion scintigraphy (PS) are not uncommonly discrepant from those measured by dynamic contrast-enhanced MRI (DCE-MRI) using indicator-dilution analysis in complex pulmonary circulation. Since PS offers the pre-capillary perfusion of the first-pass tr...

AIMS Left ventricular diastolic dysfunction has been proposed as the basis of heart failure in patients with normal left ventricular systolic function. Doppler indices of mitral inflow have been widely used to diagnose this condition and have been shown to correlate well with increased left atrial pressure in patients with cardiovascular disease. We wanted to establish age-specific criteria for...

BACKGROUND The origin and magnitude of the back pressure opposing diastolic coronary inflow remain controversial. The arterial pressure at which coronary inflow stops during a prolonged diastole, ie, "zero-flow pressure," is higher than coronary venous pressure. However, because of capacitive discharge as distending pressure falls, flow at the microcirculatory level exceeds inflow, and coronary...

Cycling of water quality constituents in lakes is affected by thermal stratification and homo-thermal conditions other factors such as oligotrophication, eutrophication, microbial activities. In addition, hydrological variability can cause greater differences residence time cycling man-made (reservoirs) than natural lakes. Thus, investigations are needed on vertical mixing new impounded reservo...

When an indicator that permeates red blood cells with an equilibration time of the order of the mean transit time of the indicator through an organ is bolus injected solely into the plasma inflow to that organ, the mean transit time of the indicator is greater than it is when the indicator is injected preequilibrated between the plasma inflow and the red cell inflow. The mean transit time for e...

When an indicator that permeates red blood cells with an equilibration time of the order of the mean transit time of the indicator through an organ is bolus injected solely into the plasma inflow to that organ, the mean transit time of the indicator is greater than it is when the indicator is injected preequilibrated between the plasma inflow and the red cell inflow. The mean transit time for e...

The acute effects of the antivascular drug, combretastatin A4 phosphate, on tumor energy status and perfusion were assessed using magnetic resonance imaging (MRI) and spectroscopy. Localized (31)P magnetic resonance spectroscopy showed that LoVo and RIF-1 tumors responded well to drug treatment, with significant increases in the P(i)/nucleoside triphosphate ratio within 3 h, whereas SaS, SaF, a...

Arabidopsis thaliana root hairs grow longer and denser in response to low-phosphorus availability. In addition, plants with the root hair response acquire more phosphorus than mutants that have root hairs that do not respond to phosphorus limiting conditions. The purpose of this experiment was to determine the efficiency of root hairs in phosphorus acquisition at high- and low-phosphorus availa...