scholarly journals Autoradiographic Determination of Regional Brain Glucose Content

1983 ◽  
Vol 3 (3) ◽  
pp. 303-310 ◽  
Author(s):  
Albert Gjedde ◽  
Nils Henrik Diemer
Keyword(s):  
Rat Brain ◽  
Brain Slices ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Glucose Content ◽  
Brain Glucose ◽  
Lumped Constant ◽  
Normal Rat ◽  
Apparent Volume Of Distribution

Brain glucose content is an important experimental variable that affects the value of the “lumped constant” of the 2-deoxyglucose method. The apparent volume of distribution in brain of the nonmetabolizable glucose analog, 3- O-methylglucose, depends only on the glucose content. From the kinetic constants of glucose transport and the apparent volume of distribution, we used autoradiography to calculate the regional glucose content of the normal rat brain. The regional glucose content varied only insignificantly in gray matter regions; the average glucose content of all rat brain slices examined was 4 μmol g−1, with an average plasma glucose concentration of 8.6 m M. Regional values varied between 3.4 and 4.6 μmol g−1. Thus, there is no reason to believe that the regional values of the lumped constant vary significantly in normal rat brains.

Letters to the Editor

PEDIATRICS ◽  
1981 ◽  
Vol 68 (4) ◽  
pp. 601-602
Author(s):  
M. Spino ◽  
J. J. Thiessen ◽  
A. Isles ◽  
H. Levison ◽  
S. M. MacLeod
Keyword(s):  
Clinical Application ◽  
Drug Concentration ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Intravenous Dose ◽  
Single Intravenous Dose ◽  
Letters To The Editor ◽  
Potential Clinical Application ◽  
Apparent Volume Of Distribution

We found the report by Feldman et al1 interesting with potential clinical application. However, we would like to point out an error in their determination of the apparent volume of distribution (V) and comment on both their methodology and results. They state that V was calculated by dividing the dose of the drug by the extrapolated y intercept for drug concentration at time 0. This method is correct for a drug which exhibits monoexponential elimination following a single intravenous dose.

scholarly journals Brain Glucose Levels in Portacaval-Shunted Rats with Chronic, Moderate Hyperammonemia: Implications for Determination of Local Cerebral Glucose Utilization

1994 ◽  
Vol 14 (1) ◽  
pp. 113-124 ◽  
Author(s):  
Nancy F. Cruz ◽  
Gerald A. Dienel
Keyword(s):  
Glucose Utilization ◽  
Normal Values ◽  
Brain Structures ◽  
Glucose Content ◽  
Brain Glucose ◽  
Glucose Levels ◽  
Lumped Constant ◽  
Dg Method ◽  
The Brain

Rates of glucose utilization (lCMRglc) in many structures of the brain of fed, portacaval-shunted rats, when assayed with the [14C]deoxyglucose (DG) method in our laboratory, were previously found to be unchanged (30 of 36 structures) or depressed (6 structures) during the first 4 weeks after shunting, but to rise progressively to higher than normal values in 25 of 36 structures from 4–12 weeks. In contrast, lCMRglc, when assayed with the [14C]glucose method in another laboratory, was depressed in most structures of brains of 4–8-week shunted rats that had relatively high brain ammonia levels. There was a possibility that the increases in lCMRglc obtained with the [14C]DG method may have been artifactual, due, in part, to a change in brain glucose content which could alter the value of the lumped constant of the DG method. Brain glucose levels of shunted rats were, therefore, assayed by both direct chemical measurement in freeze-blown samples and by determination of steady-state brain:plasma distribution ratios for [14C]methylglucose; the methylglucose distribution ratio varies as a function of plasma and tissue glucose contents. Within a week after shunting, ammonia levels in blood and brain rose to 0.25–0.30 m M and 0.35–0.70 μmol/g, respectively, and mean plasma glucose levels fell from 9–10 m M to 7.4–8.5 m M, and then remained nearly constant. Brains of fedshunted rats had normal glycogen levels and stable but moderately reduced glucose contents between 1 and 12 weeks (i.e., 1.9–2.2 μmol/g). [14C]Methylglucose distribution ratios were essentially the same as those in controls in 22 brain structures at 2 and 8 weeks after shunting. Because brain glucose levels remained stable from 1 to 12 weeks after shunting, there is no evidence to support the hypothesis that the value of the lumped constant would have changed and caused an artifactual rise in lCMRglc.

An LC-MS/MS Method for Synchronous Determination of Paclitaxel and Curcumin: Development, Validation, and Application to a Pharmacokinetic Study

2019 ◽  
Vol 15 (4) ◽  
pp. 319-326
Author(s):  
Kaifeng Qiu ◽  
Chunxia Liu ◽  
Yonghui Shi ◽  
Xiaoxia Yu ◽  
Guanghui Chen ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Mobile Phase ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Tandem Mass ◽  
Spectrometry Method ◽  
Chromatography Tandem Mass Spectrometry ◽  
Apparent Volume Of Distribution

Background: A chromatography tandem mass spectrometry method was first established and validated for the synchronous determination of curcumin(CUR) and paclitaxel (PTX) in this study. </P><P> Objective: An LC-MS/MS Method for Determination of Paclitaxel and Curcumin. Methods: The analytes were extracted with methanol, and docetaxel was used as the internal standard (IS). The analytes and the IS were separated on a C18 (4.6 mm × 50 mm, 3.5 µm) column with a mobile phase of 0.1% formic acid solution and methanol (80:20, v/v). The flow velocity of the mobile phase was 0.5 mL/min. And then, the method was applied to study the pharmacokinetic behavior of CUR and PTX in rats. Results: The calibration curves were linear within the concentration ranges of 2–1000 ng/mL for PTX and 5–500 ng/mL for CUR, the mean extraction recoveries and matrix effects of PTX, CUR, and the IS were within an acceptable range. The apparent volume of distribution of PTX was different between the group of administration of PTX and the group of co-administration with CUR and PTX. Conclusion: A sensitive and simple liquid chromatography-tandem mass spectrometry method was established and validated for the synchronous determination of PTX and CUR in rat plasma, CUR increased the apparent volume of distribution of PTX when CUR and PTX were co-administered.

Direct Determination of Tobramycin Clearance in Patients with Mild-to-Moderate Cystic Fibrosis

1987 ◽  
Vol 21 (7-8) ◽  
pp. 639-641 ◽  
Author(s):  
Carl W. Kildoo ◽  
Arthur F. Harralson ◽  
Hugo L. Folli ◽  
P. Colin Kelly ◽  
Eliezer Nussbaum
Keyword(s):  
Cystic Fibrosis ◽  
Serum Concentration ◽  
Direct Determination ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Pharmacokinetic Parameters ◽  
Concentration Data ◽  
Altered Pharmacokinetic ◽  
Apparent Volume Of Distribution

Studies performed in patients with cystic fibrosis (CF) have suggested altered pharmacokinetic parameters for aminoglycosides. Specifically, increased plasma clearance (CI) of aminoglycosides and increased apparent volume of distribution have been noted. In the present study, tobramycin CI is determined by both serum concentration data and direct renal clearance (Clren). Tobramycin Clren appeared to be directly correlated to the measured creatinine clearance (Clcr) (r = 0.93, p <0.01 ). The tobramycin Cl, by both methods of determination, was not elevated in comparison to the Clcr or expected values for patients without the disease. These results appear to corroborate a recent study in which the renal and plasma Cl of gentamicin was measured in patients with mild-to-moderate CF and were not noted to be elevated. It is suggested that standard doses of tobramycin be used initially in patients with mild-to-moderate CF with dosage adjustment based on serum concentration data to achieve the desired goals.

Pharmacokinetics and Tissue Distribution of Norfloxacin in Eel Following Oral Gavage

2012 ◽  
Vol 452-453 ◽  
pp. 1069-1073
Author(s):  
Yun Hua Hui ◽  
You Qiong Cai ◽  
Bing Feng ◽  
Wen Ruan ◽  
Hui Juan Yu
Keyword(s):  
Apparent Volume ◽  
Volume Of Distribution ◽  
European Eel ◽  
Half Time ◽  
Oral Gavage ◽  
Concentration Time ◽  
Liver And Kidney ◽  
Apparent Volume Of Distribution ◽  
Different Tissues ◽  
Body Clearance

The pharmacokinetics of norfloxacin were investigated in the European eel after a single oral gavage of 10 mg norfloxacin per kg body weight. The concentrations of norfloxacin in the main tissues (kidney, muscle, hepatopancreas and blood) were simultaneously detected by HPLC. All of the concentration-time curves of norfloxacin in the plasma, muscle and liver were consistent with absorption of a two-compartment open kinetic model. Norfloxacin was widely distributed in different tissues in the European eel. Apparent volume of distribution (Vd) was 52.025 L/kg, 34.589 L/kg, 2.795 L/kg, and 0.969 L/kg, in plasma, muscle, liver and kidney, respectively. Norfloxacin in the eel was proved to eliminate slowly, and half-time (tβ1/2) in plasma, muscle, liver and kidney, was 201.222 h, 123.789 h, 120.634 h and 627473.495 h, respectively. Body clearance was 0.689 L / ( kg•h ), 1.793 L/( kg•h ), 0.097 L/( kg•h ) and 0.028 L /( kg•h ), in plasma, muscle, liver and kidney, respectively.

Ketamine kinetics: decerebrate vs. intact cats

1979 ◽  
Vol 57 (8) ◽  
pp. 878-881 ◽  
Author(s):  
James E. Heavner ◽  
Duane C. Bloedow
Keyword(s):  
Apparent Volume ◽  
Volume Of Distribution ◽  
Drug Dose ◽  
The Body ◽  
Pharmacokinetic Parameters ◽  
Peripheral Compartment ◽  
Blood Concentrations ◽  
Open Model ◽  
Apparent Volume Of Distribution ◽  
Compartment Open Model

Pharmacokinetic parameters of a ketamine (10 mg/kg, iv) bolus in decerebrate and intact cats were compared. A two-compartment open model best described the data in both groups. The apparent volume of distribution of the peripheral compartment, the apparent volume of distribution of the drug in the body, and the half-life of the postdistributive phase were significantly less (p < 0.05) in the decerebrate animals. These results emphasize the importance of correlating behavior and neuronal activity with plasma or blood concentrations of drug in animals rather than assuming that, for a given drug dose, blood (and thus tissue) levels of the agent will be similar regardless of how the animal is prepared for study.

Determination of the Deoxyglucose and Glucose Phosphorylation Ratio and the Lumped Constant in Rat Brain and a Transplantable Rat Glioma

1989 ◽  
Vol 53 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Rajesh Kapoor ◽  
Alexander M. Spence ◽  
Mark Muzi ◽  
Michael M. Graham ◽  
Gregory L. Abbott ◽  
...  
Keyword(s):  
Rat Brain ◽  
Rat Glioma ◽  
Lumped Constant ◽  
Glucose Phosphorylation

scholarly journals Tacrolimus Pharmacokinetics in Living-Donor and Deceased-Donor Liver Transplant in Saudi Patients

2019 ◽  
pp. 288-294
Author(s):  
Hisham S. Abou-Auda ◽  
Eqbal Qaddour ◽  
Hussein Alsisi ◽  
Azizah Ajlan ◽  
Mohammad Alsebayel
Keyword(s):  
Liver Transplant ◽  
Deceased Donor ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Transplant Recipients ◽  
Donor Liver ◽  
Apparent Clearance ◽  
Donor Liver Transplant ◽  
Liver Transplant Recipients ◽  
Apparent Volume Of Distribution

Introduction: Tacrolimus is a macrolide immunosuppressant. It has a narrow therapeutic index and serious side effects which necessitate monitoring of tacrolimus blood concentration. The trough concentration of the drug may also differ based on the type of liver transplant. This study was conducted to investigate differences in pharmacokinetics between transplant types and to determine tacrolimus population pharmacokinetic in liver transplant recipients in Saudi Arabia. Method: Patients on tacrolimus, as the main immunosuppressant, who underwent liver transplant throughout2012-2014 were retrospectively studied. Demographic characteristic, tacrolimus blood trough concentrations, liver, renal, biochemistry, and hematology lab results were all collected. The pharmacokinetic parameters were estimated assuming one compartment model. Results: Tacrolimus pharmacokinetic parameters were found to be as following; elimination rate constant () 0.094 ±  0.0123, apparent volume of distribution () 112.48±63.033 L/hr, elimination half-life () 7.46± 1.01 hr and apparent total body clearance () 10.27± 5.69 L/hr (mean ± SD). Statistically significant difference was found between living-donor and deceased-donor liver transplant with respect to apparent clearance and apparent volume of distribution. Living-donor liver transplant recipients have apparent volume of distribution of 97.39±47.00 L (mean ± SD) and an apparent clearance of 8.89±4.24L/hr (mean± SD). On the other hand, deceased-donor liver transplant has an apparent clearance of 12.97±7.09L/hr (mean ± SD) and an apparent volume of distribution of 142.17± 78.65 L (mean ± SD). Conclusions: Tacrolimus pharmacokinetics parameters were accurately determined in liver transplant recipients in Saudi Arabia. The results of the present study can be clinically used in the therapeutic drug monitoring of tacrolimus in the individualization of drug dosage and taking the appropriate clinical decisions to prevent allograft rejection.

Letters to the Editor

PEDIATRICS ◽  
1981 ◽  
Vol 68 (4) ◽  
pp. 602-603
Author(s):  
Charles H. Feldman ◽  
Vincent E. Hutchinson ◽  
Charles E. Pippenger ◽  
Thomas A. Blumenfeld ◽  
Bernard R. Feldman ◽  
...  
Keyword(s):  
Elimination Rate ◽  
Area Under The Curve ◽  
Compartment Model ◽  
Apparent Volume ◽  
Systemic Circulation ◽  
Volume Of Distribution ◽  
Letters To The Editor ◽  
Correct Formula ◽  
Original Report ◽  
Apparent Volume Of Distribution

We appreciate the comments of Weinberger et al and Spino et al. The equation utilized in our original report to calculate the apparent volume of distribution (V) was in error, as it was based on determinations for drugs that exhibit monoexponential elimination following a single intravenous dose. The correct formula for oral dosing at steady state with a drug obeying one-compartment model kinetics is: V = F.X0/AUCτ. K, where F is the total fraction of dose reaching systemic circulation, X0, is the dose, AUCτ is the area under the curve during a dosing interval; K is the elimination rate constant.1

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