Four-compartment model

Fugacity Level III calculations (four-compartment model)... 

A four-compartment model consisting of a two-compartment model for each enantiomer, with elimination from both compartments, connected by rate constants for chiral inversion was fitted to the concentration data, whereas the sedative effects were correlated with the blood concentrations of R- and S-thalidomide by means of logistic regression. PK modeling predicted that varying the infusion time of a fixed dose of S-thalidomide between 10 min and 6 h would have little influence on the maximal blood concentration of formed R-thaKdomide. These effects may chiefly be exerted by S-thalidomide, but the enantiomers are interconverted in vim... 

A Four-Compartment Model as a Basis for CSF Diagnosis ofCNS... 

The complex anatomy of the brain requires a schematic model for interpreting serum and CSF findings (Fig. 1). The assumption of the four-compartment model suffices for the laboratory diagnosis of CNS diseases. These compartments are as follows ... 

Cherruault Y, Sarin VB. 1987. A four compartment model to study the kinetics of strontium metabolism in man. Int J Biomed Comput 20 21-26. 

ANALYTICAL SOLUTION FOR A STEADY-STATE FOUR-COMPARTMENT MODEL OF THE ATMOSPHERE... 

FIGURE 22.9 Four-compartment model of the atmosphere (NH = Northern Hemisphere, SH = Southern Hemisphere, S = stratosphere, T = troposphere). PNH and Psh are source emission rates of the compound in the NH and SH troposphere, respectively. The quantities of the species of interest in the four reservoirs are denoted 2nh> G h siii anc 2 sH- The fluxes between the reservoirs are proportional to the content of the compound in the reservoir where the flux originates. The flux of material from the NH troposphere to the SH troposphere is nh/sii2nh ar d the reverse flux is A H/nhG h- Other intercompartmental fluxes are defined similarly. 

Equations (22.38) and (22.39) give the steady-state concentrations of the substance in the NH and SH troposphere, respectively (Q = Q h and Qi = Q as a function of the source rates into the two hemispheres and all the transport and removal parameters of the four compartments. Steady-state concentrations in the two stratospheric reservoirs, Qi = nh and = Gsh are then obtained from (22.34) and (22.35). These equations provide a general, steady-state analysis of a four-compartment model of a substance that is emitted into the troposphere and removed by separate first-order processes in each of the four compartments. 

Application of the Four Compartment Model to Methyl Chloroform (CH3CC13)... 

Such estimates are usually accomplished with a three-dimensional atmospheric model (Prinn et al. 1992), but here we apply the simple four-compartment model to analyze the global budget of CH3CCI3. 

The four-compartment model can be used, with the parameter values and yearly emission rates given above, to estimate the steady-state mixing ratios of CH3CCI3 in the troposphere and stratosphere and the overall atmospheric residence time of CH3CCI3. The results are given below. 

A perfusion-limited, four compartment model was used to simulate the effect of several confounding factors on the levels of several contaminants in the breath, including PERC. The model, which considered metabolic clearance, consisted of a pulmonary compartment, a vessel-rich group, a group of low-perfused tissues containing muscles and skin, and a group of poorly perfused fatty tissues. The authors predicted that intra-day fluctuations in exposure would have a large effect on breath sampled just after the shift, but that the... 

FIGURE 1.4 A four-compartment model of bone cells Compartment 1 represents mesenchymal cells, compartment 2 represents osteoclasts, compartment 3 represents osteoblasts, and compartment 4 represents osteocytes. Mesenchymal cells reproduce and transform either into osteoclasts or into osteoblasts. The osteoclast can transform into an osteoblast and an osteoblast can transform into an osteoclast. The osteoblast can transform into an osteocyte. 

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