Residence time in blood

This model accurately predicted the time curves for blood concentration and urinary excretion of metabolites by male volunteers exposed to 100 ppm trichloroethylene (Sato et al. 1991). It was found that, while the amount of metabolite excretion increases with body weight, the concentration does not, because of a corresponding increase in urinary volume. Also, women and obese people, compared with slim men, have lower concentrations but longer residence times of blood trichloroethylene because of their higher fat content (Sato et al. 1991). As a consequence, the model predicted that 16 hours after exposure to trichloroethylene, one could expect a woman s blood level to be 30% higher and an obese man s level to be twofold higher than that of a slim man (Sato 1993). 

Kinetic Constants and Model Parameters in the O Flaherty Model 2-7 Residence Times in the Biokinetic Module of the IEUBK Model 2-8 Kinetic Constants and Model Parameters in the Leggett Model 2-9 Summary of Blood Slope Factors from Various Environmental Media 2-10 Genotoxicity of Lead In Vivo 2-11 Genotoxicity of Lead In Vitro... 

GIT motility has a significant effect on GIT absorption of a toxicant. For example, excessively rapid movement of gut contents can reduce absorption by reducing residence time in the GIT, while the presence of food in the stomach can delay the progress of drugs from the stomach to the small intestine where most of the absorption will occur. Increased splanchnic blood flow after a meal can result in absorption of several drugs (e.g., propranolol), but in hypovolemic states, absorption can be reduced. 

Furthermore, this lysine dendrimer-bound gadolinium complex exhibits a higher in-vivo stability as a contrast agent and hence a longer residence time in tissue than comparatively simple commercially available gadolinium compounds and thus assures improved visualisation of organs, blood vessels, and tissue (Fig. 8.18) [58],... 

Assume the average worker in the auto tunnels into and out of Manhattan had a blood lead level of 155 pg/L and that 25 pg/day of this lead is either excreted or deposited to bone. What is lead s residence time in the blood of this worker ... 

Seven male volunteers were exposed to 2-butoxyethanol for 2 hours at the Swedish occupational exposure limit (20 ppm or 0.85 mmol/m ) during light physical exercise on a bicycle ergometer (Johanson et al. 1986a). Expired air was collected at regular time intervals for estimation of the respiratory uptake of the solvent. Capillary blood and urine were sampled, during and after the exposure period, and analyzed for 2-butoxyethanol and its metabolite, free 2-butoxyacetic acid. 2-Butoxyethanol was no longer detectable in the blood 2-4 hours after the end of exposure. The apparent values of elimination half-time, mean residence time, total blood clearance, and steady-state volume of distribution were 40 minutes, 42 minutes, 1.2 E/minute, and 54 L, respectively, for 2-butoxyethanol. The half-life for 2-butoxyethanol in urine was 1.36 hours. The amount of 2-butoxyethanol excreted in urine was less than... 

In most studies in which attempts have been made to investigate the relationship between hydrodynamics and thrombus formation, the flow rate of blood through the test device was changed to alter the hydrodynamics. Unfortunately, for many configurations [for example, a tube (9)] a change in flow rate also changed the residence time of blood in the device, the mass transfer coefficients, as well as shear rates at the biomaterial-blood interface. This simultaneous variation in hemodynamic parameters makes it difficult to assign specific cause and effect relationships to the results obtained with these methods. 

Atmospheric deposition of lead is a major source of soil, water and sediment contamination. Depending on the particulate size, airborne suspended particles may have a long residence time in the atmosphere. Studies from remote areas indicate that lead-containing particles are transported over substantial distances, up to thousands of kilometres, by general weather systems. In rural areas of Europe and North America, the annual deposition rates (wet and dry) are typically in the range of 20-80 p-g/m per day. In large cities the deposition rates are about 1.5-10 times higher than in rural areas (OECD, 1993). Some data indicate that lead fallout in excess of 250 pg/m per day will increase blood lead levels (WHO, 1994). 

Rudnai and Horvath (1996) conducted a survey in an area of Budapest which had formerly been heavily polluted by a lead-waste processing plant. At the time of the study, the plant had already been closed. The measured blood levels are presented in Table 22. The distance of residence from the plant, the length of residence time in the area, and in case of women age, were found to be significantly correlated with blood lead values. 

The absorption, bioavailability, and retention of radionuclides in mammals are modified by the age, sex, species, and diet of the organism season of collection the chemical form of the radionuclide in tissue and blood residence time in the digestive tract preferential accumulation by selected organs and tissues and many other variables. 

From the other point of view, the residence time in the order of several minutes in combination with the relatively low material temperatures explains successful drying on inert carriers of some biomaterials such as Zn-bacitracine, animal blood, vegetable extracts, egg products, pea protein, starch, and meat... 

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