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Biomedical subjects

M Dumont

Publications and source records attributed to M Dumont.

At least 289 records · Page 16Linked to original sources
PubMed1975

Hepatocellular uptake of erythritol and mannitol in the dog.

The purpose of this study was to determine the initial space of distribution of [14C]erythritol (mol wt 122) and [14C]mannitol (mol wt 182) in the liver of the dog by the single-injection, multiple-indicator-dilution method. 22Na was used as the extracellular indicator and tritiated water (THO) was used as total liver water indicator. The indicators were simultaneously injected into the portal vein of anesthetized dogs and dilution curves were obtained at the outflow from the hepatic vein. It was found that hepatic venous dilution curves of [14C]erythritol and THO were practically identical in all experiments. In contrast, the dilution curves of [14C]mannitol were generally distinct from those of THO. Analysis of [14C]mannitol-dilution curves according to Goresky suggested that the observed difference between this solute and THO was the result of a limited permeability of the sinusoidal membrane to mannitol. It is concluded that [14C]erythritol has instantaneous and practically unrestricted access to total liver water. This finding supports the validity of using erythritol as a liver cell water marker. A larger solute, [14C]mannitol, has restricted access to total liver cell water because of a permeability barrier in the sinusoidal liver cell membrane, but its diffusion into the hepatocyte is also very rapid.

Animals↗
PubMed1975

Hepatocellular uptake of bile acids in the dog: Evidence for a common carrier-mediated transport system. An indicator dilution study.

The purpose of this study was to compare the uptake of taurocholate (TC) by the liver of the dog to that of taurochenodeoxycholate (TCDC) and to examine the influence of TCDC on TC uptake. The uptake of these bile acids by the liver of the intact was studied with the multiple indicator dilution method, using 51Cr-labeled red blood cells as a vascular indicator, 125I-labeled albumin as an extravascular reference, and one or two labeled bile acids. The analysis of the dilution curves fitted well a three-compartment model, and no return of the extracted bile acids to the extracellular space could be detected. The initial space of distributin of TC in the presence of a fixed dose of TCDC was 1.25 +/- 0.09 (SD) times greater than that of albumin. Analysis of the data for TC uptake in the presence of TCDC was consistent with Michaelis-Menten kinetics, as previously established for TC alone. The calculated initial maximal velocity of uptake (Vmax) of TC in the precence of TCDC was 4.92 +/- 1.36 (SD) mumoles per sec per 100 g of liver. This value is not significantly different from the Vmax previously calculated for TC alone. The apparent KD (dose of TC yielding half-maximal velocity) was 18.10 +/- 6.14 (SD) mumoles per 100 g of liver, a value significantly higher than that obtained in the absence of TCDC. A K1 (the Michaelis-type constant characterizing the inhibition of TC uptake by TCDC) of 2.71 +/- 1.08 (SD) mumoles of TCDC per 100 g of liver was calculated. These observations are consistent with competitive inhibition of TC uptake by TCDC, and thus with the existence of a common carrier-mediated transport system for TC and TCDC. Estimation of the kinetic characteristics of the two bile acids from dilution curves obtained simultaneously showed that the affinity for the carrier was higher for TCDC than for TC, but that the maximal capacity was lower for TCDC than for TC.

Animals↗
PubMed1975

Alpha 1-antitrypsin in amniotic fluid.

Amniotic fluid a1-antitrypsin values were determined by radial immunodiffusion of 317 samples obtained between the 10th and 43rd weeks of gestation in normal pregnant patients and those with complications. Serial determinations of a1-antitrypsin values revealed that in normal patients values decreased as pregnancy advanced while values increased as pregnancy advanced in cases in which there was severe Rh-alloimmunization and hydramnios. A wide range of values was observed for each week of gestation. Although there was a definite tendency for values to decrease as pregnancy advanced (60.8 mg/100 ml before 30 weeks and 17.9/100 ml after 40 weeks); the method must be regarded as unreliable for determining fetal maturity in clinical practice. In the case of newborn infants with hyaline membrane disease, no decrease in amniotic fluid a1-antitrypsin values has been found.

Amniotic Fluid↗