Transport of radioactive deoxyglucose by the isolated perfused human placental cotyledon as measured by the paired-tracer dilution method. Inconsistency of the transfer rates across the two trophoblast borders with the simultaneously measured rate of transplacental transfer

Placenta ◽  
1988 ◽  
Vol 9 (3) ◽  
pp. 227-235 ◽  
Author(s):  
J. Štulc ◽  
H. Schneider
Keyword(s):  
Dilution Method ◽  
Transfer Rates ◽  
Transplacental Transfer ◽  
Measured Rate ◽  
Tracer Dilution ◽  
Paired Tracer Dilution

scholarly journals A paired-tracer dilution method for characterizing membrane transport in the perfused rat hindlimb. Effects of insulin, feeding and fasting on the kinetics of sugar transport

1983 ◽  
Vol 214 (3) ◽  
pp. 737-743 ◽  
Author(s):  
M J Rennie ◽  
J P Idström ◽  
G E Mann ◽  
T Scherstén ◽  
A C Bylund-Fellenius
Keyword(s):  
Contractile Activity ◽  
Sugar Transport ◽  
Transport Processes ◽  
Dilution Method ◽  
Mammalian Muscle ◽  
Tracer Dilution ◽  
Kinetics Of ◽  
Paired Tracer Dilution ◽  
Feeding And Fasting

We have applied the paired-tracer dilution method to the study of transport processes in a mixed mammalian muscle preparation, the perfused rat hindlimb. The method is suitable for the characterization of the kinetic parameters of sugar and amino acid transport and its regulation by hormones, contractile activity, hypoxia, etc. Insulin stimulates sugar transport by increasing the Vmax. of the process 2-3 fold, but its affinity is unchanged. Starvation increases the affinity of sugar transport in perfused skeletal muscle.

Effect of Prewetting Brines and Mixing on Ice-Melting Rate of Salt at Cold Temperatures: New Tracer Dilution Method

2017 ◽  
Vol 2613 (1) ◽  
pp. 71-78 ◽  
Author(s):  
Scott Koefod
Keyword(s):  
Freezing Point ◽  
Melting Rate ◽  
Test Method ◽  
Dilution Method ◽  
Ice Melting ◽  
Cold Temperatures ◽  
Ice Melt ◽  
Solid Salt ◽  
Different Temperatures ◽  
Tracer Dilution

A novel test method has been developed to measure the ice-melting rate of deicers. The ice-melting rates of prewetted salt were determined by measuring the change in the concentration of chloride (Cl−) or magnesium or calcium cations (Mg2+ or Ca2+, respectively) in the ice melt as tracers. The method is substantially more precise than the SHRP H205.1 standard and has the further advantage of measuring ice-melting and salt dissolution rates simultaneously. Brines were preequilibrated with ice at −19.3°C (−2.7°F) and blended with solid salt to determine the effect of different prewetting brines on the ice-melting rate of the solid salt component only. The measured equilibrium ice-melting capacity of sodium chloride (NaCl) agreed well with the theoretical value calculated from the NaCl freezing point curve. Under a condition of no mixing, solid salt yielded 0.87% of its total available ice-melting capacity after 60 min when wetted with NaCl brine and 9.7% when wetted with calcium chloride (CaCl2) brine. Mixing raised the yield of ice melt to 27.1% and 50.5% after 60 min when wet with NaCl and CaCl2 brines, respectively. The CaCl2 brine was slightly more effective than the magnesium chloride (MgCl2) brine at enhancing the ice-melting rate of salt. The test method promises to be a useful tool for permitting a more precise optimization of prewetting brine composition, concentration, and brine-to-salt ratio at different temperatures. The method may also permit better determination of the cost-effectiveness of different prewetting strategies and provide deeper insights into the mechanism of chemical ice melting.

Uptake and asymmetric efflux of amino acids at maternal and fetal sides of placenta

1981 ◽  
Vol 241 (3) ◽  
pp. C106-C112 ◽  
Author(s):  
B. M. Eaton ◽  
D. L. Yudilevich
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Guinea Pig ◽  
Cellular Uptake ◽  
Transport Systems ◽  
Acid Transport ◽  
Dilution Technique ◽  
Acidic Amino Acids ◽  
Tracer Dilution ◽  
Paired Tracer Dilution

Unidirectional uptake of eighteen amino acids into the syncytiotrophoblast was measured from both the maternal and fetal circulations of isolated dually perfused guinea pig placentas using a single-circulation, paired-tracer dilution technique. A bolus containing a tritiated amino acid and L-[14C]glucose (extracellular marker) was injected intra-arterially into one circulation, and both venous outflows were sequentially sampled. The maximal cellular uptake (Umax) on the injection side was determined from (1-[3H]/[14C]) values and used to calculate the unidirectional influx. Umax values for neutral and basic amino acids ranged between 15 and 58% and were similar on both sides of the trophoblast. Uptake of the acidic amino acids and taurine was minimal. Amino acid influx from either circulation was followed by rapid tracer backflux and transplacental transfer. Tracer efflux was asymmetric and preferentially directed towards the fetal side. It is suggested that amino acid transport systems are present on both surfaces of the placenta and that net transfer from mother to fetus is the result of asymmetric efflux from the trophoblast.

scholarly journals Myocardial tissue recruitment in the dog as determined by double tracer dilution method.

1976 ◽  
Vol 39 (2) ◽  
pp. 276-281 ◽  
Author(s):  
A L'Abbate ◽  
R R Mildenberger ◽  
D T Zborowska-Sluis ◽  
G A Klassen
Keyword(s):  
Dilution Method ◽  
Myocardial Tissue ◽  
Tracer Dilution

Glucose carriers at maternal and fetal sides of the trophoblast in guinea pig placenta

1979 ◽  
Vol 237 (5) ◽  
pp. C205-C212 ◽  
Author(s):  
D. L. Yudilevich ◽  
B. M. Eaton ◽  
A. H. Short ◽  
H. P. Leichtweiss
Keyword(s):  
Guinea Pig ◽  
Intact Animal ◽  
Sugar Uptake ◽  
Dilution Technique ◽  
Nondestructive Technique ◽  
Guinea Pig Placenta ◽  
The Mean ◽  
Pig Placenta ◽  
Tracer Dilution ◽  
Paired Tracer Dilution

Trophoblast uptake and unidirectional influx of 3H-labeled hexoses were measured relative to L-[14C]glucose (extracellular marker) using a single-circulation, paired-tracer dilution technique. Successive runs were performed in the fetal and maternal circulations of isolated dually perfused guinea pig placentas, obtained from anesthetized dams and perfused for 60--140 min. The leakiness, estimated from the percentage of the L-glucose dose that crossed the trophoblast, varied (25 +/- 3% (SE), n = 28). On the injection side the maximal sugar uptake (Umax) was measured from early venous concentration ratios, since rapid tracer backflux occurred: Umax = (1 -- 3H/14C) x 100. Umax was independent of the leakiness. In all 14 placentas studied, stereospecific saturable transport of D-glucose was demonstrated at fetal (Umax = 56 +/- 4% (SE), n = 14) and maternal (62 +/- 1% (SE), n = 14) surfaces. The mean unidirectional influxes were 3.3 and 3.5 mumol.min-1.g-1, respectively. Uptakes were inhibited by phloretin and less effectively by phlorizin. D-glucose, 3-O-methylglucose, D-mannose and D-galactose had similar Umax values, about four times that of D-fructose. Tracer backflux and transplacental flux were also equal from both sides. It is concluded that similar hexose carriers, which resemble the human erythrocyte carrier, exist at the membrane on both sides of the trophoblast. The nondestructive technique employed characterizes carriers and receptors at the blood side of cells and could be applied to the placenta or other organs in the intact animal.

A fluoride borehole dilution apparatus for groundwater velocity measurements

1977 ◽  
Vol 14 (4) ◽  
pp. 554-561 ◽  
Author(s):  
G. E. Grisak ◽  
W. F. Merritt ◽  
D. W. Williams
Keyword(s):  
Large Scale ◽  
Shallow Groundwater ◽  
Tracer Test ◽  
Dilution Method ◽  
Groundwater Velocity ◽  
Low Concentrations ◽  
Groundwater Systems ◽  
Chloride Profiles ◽  
Fluoride Electrode ◽  
Tracer Dilution

A borehole dilution method using fluoride in low concentrations as the tracer and an adapted, commercially available fluoride ion electrode to measure the tracer dilution has been developed and employed at two sites. The sites are shallow groundwater systems consisting of alluvial surficial gravels near Fort Macleod, Alberta, and glaciodeltaic sand deposits at the Chalk River Nuclear Laboratories, Ontario. Zones of relatively high groundwater velocities determined at Fort Macleod with the fluoride apparatus are also evident in the results of a large-scale tracer test that documented chloride profiles over the saturated gravel thickness from point samples at 0.3 m depth intervals. The performance of the fluoride electrode compared favorably with a radio tracer (131I) technique in a simultaneous dilution experiment at the Chalk River site. Other ion-selective electrodes such as the chloride electrode may provide an alternative sensor in areas where hydrochemical conditions may restrict the use of the fluoride electrode.

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