Because the shape of the proximal isovelocity surface area is nearly hemispheric at a blue-red interface velocity of 11 to 15 cm/s, volume flow rate can be accurately calculated in this proximal isovelocity surface area interface velocity range (produced by zero baseline shift) by measuring a single-interface radius. This approach should be clinically useful for calculating the volume flow rate across stenotic and regurgitant valves and across shunt defects.
Studies of organometallic reactions in living cells commonly rely on ensemble-averaged measurements, which can obscure the detection of reaction dynamics or location-specific behavior. This information is necessary to guide the design of bioorthogonal catalysts with improved biocompatibility, activity, and selectivity. By leveraging the high spatial and temporal resolution of single-molecule fluorescence microscopy, we have successfully captured single-molecule events promoted by Ru complexes inside live A549 human lung cells. By observing individual allylcarbamate cleavage reactions in real-time, our results revealed that they occur with greater frequency inside the mitochondria than in the non-mitochondria regions. The estimated turnover frequency of the Ru complexes was at least 3fold higher in the former than the latter. These results suggest that organelle specificity is a critical factor to consider in intracellular catalyst design, such as in developing metallodrugs for therapeutic applications.
Doppler color flow mapping of a proximal isovelocity surface area (PISA), calculated from a blue-red aliasing radius, has been shown in vitro to be accurate for estimating volume flow rate across a narrowed orifice. Volume flow rate (in cm 3/sec) can be calculated as PISA (in cm 2) x aliasing velocity (in cm/sec). This method has advantages over other color Doppler approaches in that PISA-derived volume flow rate calculations appear to be independent of machine parameter settings and orifice shape. We evaluated the clinical applicability of the PISA method in 49 patients with native valve mitral regurgitation (MR). Color Doppler flow mapping was performed at color aliasing velocities of 54-72 cm/sec. Twenty-four patients were excluded because a color aliasing radius was not clearly seen: 20 of these 24 patients had mild MR. In the remaining 25 patients, the ratio of maximum regurgitant jet area-to-left atrial area, as well as the regurgitant stroke volume estimated using the time-velocity integral method, were compared to regurgitant stroke volume calculated from the PISA method. Maximum PISA was calculated using a formula derived from previous in vitro studies: PISA = 8.05 x r 2, where r is the maximum color Doppler aliasing radius in the apical four-chamber view.(ABSTRACT TRUNCATED AT 250 WORDS)
Clinical research
shows that frequent measurements of both pH and
lactate can help guide therapy and improve patient outcome. However,
current methods of sampling blood pH and lactate make it impractical
to take readings frequently (due to the heightened risk of blood infection
and anemia). As a solution, we have engineered a subcutaneous pH and
lactate sensor (PALS) that can provide continuous, physiologically
relevant measurements. To measure pH, a sheet containing a pH-sensitive
fluorescent dye is placed over 400 and 465 nm light-emitting diodes
(LEDs) and a filter-coated photodetector. The filter-coated photodetector
collects an emitted signal from the dye for each LED excitation, and
the ratio of the emitted signals is used to monitor pH. To measure
lactate, two sensing sheets comprising an oxygen-sensitive phosphorescent
dye are each mounted to a 625 nm LED. One sheet additionally comprises
the enzyme lactate oxidase. The LEDs are sequentially modulated to
excite the sensing sheets, and their phase shift at the LED drive
frequency is used to monitor lactate.
In vitro
results
indicate that PALS successfully records pH changes from 6.92 to 7.70,
allowing for discrimination between acidosis and alkalosis, and can
track lactate levels up to 9 mM. Both sensing strategies exhibit fast
rise times (< 5 min) and stable measurements. Multianalyte
in vitro
models of physiological disorders show that the
sensor measurements consistently quantify the expected pathophysiological
trends without cross talk;
in vivo
rabbit testing
further indicates usefulness in the clinical setting.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.