A Two Compartment Model Method for Continuous Determination of Hydraulic Parameters of Higher Plant Cells by Pressure Probe Technique

1988 ◽  
Vol 39 (7) ◽  
pp. 961-971 ◽  
Author(s):  
GUO-LI ZHU ◽  
CHENG-HOU LOU
Keyword(s):  
Plant Cells ◽  
Compartment Model ◽  
Pressure Probe ◽  
Hydraulic Parameters ◽  
Higher Plant ◽  
Probe Technique ◽  
Model Method ◽  
Two Compartment Model ◽  
Continuous Determination

Clearance and Non-Invasive Determination of the Hepatic Extraction of Indocyanine Green in Baboons and Man

1983 ◽  
Vol 64 (2) ◽  
pp. 207-212 ◽  
Author(s):  
S. L. Grainger ◽  
P. W. N. Keeling ◽  
I. M. H. Brown ◽  
J. H. Marigold ◽  
R. P. H. Thompson
Keyword(s):  
Indocyanine Green ◽  
Accurate Determination ◽  
Liver Blood Flow ◽  
Compartment Model ◽  
Hepatic Extraction ◽  
Non Invasive ◽  
Two Compartment Model ◽  
Hepatic Extraction Ratio ◽  
Plasma Disappearance Curve

1. The disposition of an intravenous bolus of indocyanine green (ICG) has been studied in healthy man and baboons using a novel analysis of a two compartment pharmacokinetic model. 2. This analysis enabled the hepatic extraction ratio (ER) of dye to be determined solely from the plasma disappearance curve, and the ER determined did not differ from that measured by hepatic vein catheterization. 3. When compared with clearance measured at steady state, the two compartment model gave a significantly more accurate determination of plasma clearance than did the conventional one compartment model. 4. It is concluded that, in health, liver blood flow may be calculated accurately and noninvasively after a single intravenous injection of ICG.

Serial determination of glomerular filtration rate in conscious mice using FITC-inulin clearance

2004 ◽  
Vol 286 (3) ◽  
pp. F590-F596 ◽  
Author(s):  
Zhonghua Qi ◽  
Irene Whitt ◽  
Amit Mehta ◽  
Jianping Jin ◽  
Min Zhao ◽  
...  
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Compartment Model ◽  
Inulin Clearance ◽  
Male And Female ◽  
Serial Determination ◽  
Two Compartment Model ◽  
Clearance Kinetics

Two nonradioactive methods for determining glomerular filtration rate (GFR) in conscious mice using FITC-labeled inulin (FITC-inulin) were evaluated. The first method measured GFR using clearance kinetics of plasma FITC-inulin after a single bolus injection. Based on a two-compartment model, estimated GFR was 236.69 ± 16.55 and 140.20 ± 22.27 μl/min in male and female C57BL/6J mice, respectively. Total or ⅚ nephrectomy reduced inulin clearance to 0 or 32.80 ± 9.32 μl/min, respectively. Conversely, diabetes mellitus induced by streptozotocin was associated with increased GFR. The other approach measured urinary inulin clearance using intraperitoneal microosmotic pumps to deliver FITC-inulin and metabolic cages to collect timed urine samples. This approach yielded similar GFR values of 211.11 ± 26.56 and 157.36 ± 20.02 μl/min in male and female mice, respectively. These studies demonstrate the feasibility of repeated nonisotopic measurement of inulin clearance in conscious mice.

Is it Possible to Provide a Prognosis after Radical Prostatectomy for Prostate Cancer by Means of a Psa Regression Model?

2005 ◽  
Vol 20 (2) ◽  
pp. 112-118 ◽  
Author(s):  
M. May ◽  
S. Gunia ◽  
C. Helke ◽  
K.P. Braun ◽  
S. Pickenhain ◽  
...  
Keyword(s):  
Radical Prostatectomy ◽  
Computer Program ◽  
Biochemical Recurrence ◽  
Specific Antigen ◽  
Compartment Model ◽  
Recurrence Free Survival ◽  
Free Survival ◽  
Two Compartment Model

Background For over 15 years, studies have been done to evaluate the elimination kinetics of the prostate-specific antigen (PSA) after radical prostatectomy. Even though evaluation of PSA regression in the two-compartment model has become established, no clear data are currently available as to whether a statement can be made with regard to tumor prognosis from a computation of the PSA half-life (PSA-HL). This study focuses on the determination of the PSA-HL in the two-compartment model and on its correlation with the biochemical recurrence-free survival. In addition, a computer program is being developed to simplify the determination of PSA-HL. Material and methods Seventy-seven prospective patients were examined who subsequently had a radical prostatectomy at our facility without neoadjuvant or adjuvant hormone deprivation. In addition to preoperative measurement of the PSA value (d0), PSA determinations were carried out postoperatively on days 5, 10 and 60, and at four-monthly intervals thereafter (mean follow-up: 16 months). By means of the computer program developed for this purpose, CTK. TumW, the PSA half-lives for the first (d0–d5, PSA-HL1) and second (d5–d10, PSA-HL2) compartments were subsequently determined and their effect on biochemical recurrence-free survival was assessed. Results PSA-HL1 and PSA-HL2 were 1.89 (± 0.03) and 3.39 (± 0.14) days, respectively. Whilst PSA-HL1 did not permit any prognostic statement, the median PSA-HL in the second compartment between patients with and without disease progression differed significantly (4.44 versus 3.12 days; p<0.001). Discrimination analysis produced a cutoff of 3.8 days for the second compartment; patients with a PSA-HL2 ≥3.8 days had a significantly worse biochemical recurrence-free survival after 18 months than the other patients (27% versus 93%; p<0.001). Conclusion The PSA regression kinetics after radical prostatectomy follows a two-compartment model in which the prognostic value of the PSA-HL1 is limited. When a cutoff of 3.8 days is used, evaluation of the PSA-HL in compartment 2 (d5–10) appears to permit a prognostic statement. Due to the limited postsurgical follow-up, the disease process was only assessed as biochemical recurrence-free survival, and a longer follow-up will be necessary to generate data on progression-free survival.

Comparison Between Osmotic and Hydrostatic Water Flows in a Higher Plant Cell: Determination of Hydraulic Conductivities and Reflection Coefficients in Isolated Epidermis of Tradescantia virginiana

1982 ◽  
Vol 9 (4) ◽  
pp. 461 ◽  
Author(s):  
SD Tyerman ◽  
E Steudle
Keyword(s):  
Osmotic Pressure ◽  
Turgor Pressure ◽  
Water Volume ◽  
Pressure Probe ◽  
Reflection Coefficients ◽  
Higher Plant ◽  
Bathing Medium ◽  
Tradescantia Virginiana ◽  
Cell Turgor

Hydraulic conductivity (Lp), volumetric elastic modulus (ε) and reflection coefficients (δ) have been determined for cells from isolated strips of the lower epidermis of leaves of Tradescantia virginiana using the pressure probe. Lp was (6.4 � 4.5) × 10-8 ms-1 Mpa-1 [(6.4 � 4.5) × 10-7 cm s-1 bar-1; mean � s.d., n = 15 cells] and was independent of the cell turgor pressure (P) and of osmotic pressure of the bathing medium. P in Johnson's solution (π° = 0.09 MPa) was 0.42-0.67 MPa (4.2-6.7 bar), which was somewhat larger than in the intact tissue. ε increased linearly with increasing P in the pressure range from zero to full turgor. Reflection coefficients of some non-electrolytes were determined by measuring the ΔP in response to a change in external osmotic pressure (Δπ°) after the addition of the solutes. The data were corrected for solute flow. For sucrose, mannitol, urea, acetamide, formamide, glycerol and ethylene glycol, δ was close to unity and the cells behaved like ideal osmometers. For the monohydroxyalcohols n-propanol ( δ = -0.58), isopropanol (δ = 0.26), ethanol (δ = 0.25) and methanol (δ = 0.15), rather low reflection coefficients were found which were even negative for some solutes and cells. Values of δ obtained from measuring the inital water (volume) flow were in agreement with those determined from the ΔP/Δπ° ratios. For the rapidly permeating substances, the changes in turgor after the addition of solute were transient and the equilibration of solutes between cell and medium could be measured using the probe. Although unstirred layers may affect the equilibration of solute it should, in principle, be possible to use the technique for the determination of permeability coefficients of membranes of higher plant cells.

Detection of heterozygotes for phenylketonuria. Total body phenylalanine clearance and concentrations of phenylalanine and tyrosine in the plasms of fasting subjects compared.

1977 ◽  
Vol 23 (9) ◽  
pp. 1654-1660 ◽  
Author(s):  
R Jagenburg ◽  
C G Regårdh ◽  
S Rödjer
Keyword(s):  
Total Body Clearance ◽  
Compartment Model ◽  
Central Compartment ◽  
Kinetic Evaluation ◽  
Plasma Phenylalanine ◽  
Two Compartment Model ◽  
Total Body ◽  
Elimination Curve ◽  
Body Clearance

Abstract Two tests have been compared for detection of heterozygotes for phenylketonuria, one based on determination of plasma phenylalanine and tyrosine concentrations in fasting individuals and the other on kinetic evaluation of the plasma elimination curve after intravenous loading with L-phenylalanine. The plasma elimination curve was biexponential and the kinetics were evaluated according to the two-compartment model. The constant, beta, expressing the rate of elimination from plasma at pseudo-equilibrium, the rate constant for the elimination from the central compartment, and the total body clearance were determined. Of these three, total body clearance, which on the average was reduced by 32% in the phenylketonuric heterozygotes, showed the best discriminatory ability, but was not better than the information on concentrations of phenylalanine and tyrosine in detecting heterozygotes for phenylketonuria.

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