Hepatic uptake and metabolism of galactose can be quantified in vivo by 2-[18F]fluoro-2-deoxygalactose positron emission tomography

Metabolism of galactose is a specialized liver function. The purpose of this PET study was to use the galactose analog 2-[18F]fluoro-2-deoxygalactose (FDGal) to investigate hepatic uptake and metabolism of galactose in vivo. FDGal kinetics was studied in 10 anesthetized pigs at blood concentrations of nonradioactive galactose yielding approximately first-order kinetics (tracer only; n = 4), intermediate kinetics (0.5–0.6 mmol galactose/l blood; n = 2), and near-saturation kinetics (>3 mmol galactose/l blood; n = 4). All animals underwent liver C15O PET (blood volume) and FDGal PET (galactose kinetics) with arterial and portal venous blood sampling. Flow rates in the hepatic artery and the portal vein were measured by ultrasound transit-time flowmeters. The hepatic uptake and net metabolic clearance of FDGal were quantified by nonlinear and linear regression analyses. The initial extraction fraction of FDGal from blood-to-hepatocyte was unity in all pigs. Hepatic net metabolic clearance of FDGal, KFDGal, was 332–481 ml blood·min−1·l−1 tissue in experiments with approximately first-order kinetics and 15.2–21.8 ml blood·min−1·l−1 tissue in experiments with near-saturation kinetics. Maximal hepatic removal rates of galactose were on average 600 μmol·min−1·l−1 tissue (range 412–702), which was in agreement with other studies. There was no significant difference between KFDGal calculated with use of the dual tracer input (KdualFDGal) or the single arterial input (KarterialFDGal). In conclusion, hepatic galactose kinetics can be quantified with the galactose analog FDGal. At near-saturated kinetics, the maximal hepatic removal rate of galactose can be calculated from the net metabolic clearance of FDGal and the blood concentration of galactose.

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Biodegradation rates of aromatic contaminants in biofilm reactors

Water Science & Technology ◽

10.2166/wst.1995.0027 ◽

1995 ◽

Vol 31 (1) ◽

pp. 117-128 ◽

Cited By ~ 8

Author(s):

Jean-Pierre Arcangeli ◽

Erik Arvin

Keyword(s):

Aromatic Hydrocarbons ◽

Competitive Inhibition ◽

Removal Rate ◽

First Order ◽

Biofilm Reactors ◽

First Order Kinetics ◽

Reducing Conditions ◽

Low Concentrations ◽

Degradation Rates ◽

Order Surface

This study has shown that microorganisms can adapt to degrade mixtures of aromatic pollutants at relatively high rates in the μg/l concentration range. The biodegradation rates of the following compounds were investigated in biofilm systems: aromatic hydrocarbons, phenol, methylphenols, chlorophenols, nitrophenol, chlorobenzenes and aromatic nitrogen-, sulphur- or oxygen-containing heterocyclic compounds (NSO-compounds). Furthermore, a comparison with degradation rates observed for easily degradable organics is also presented. At concentrations below 20-100 μg/l the degradation of the aromatic compounds was typically controlled by first order kinetics. The first-order surface removal rate constants were surprisingly similar, ranging from 2 to 4 m/d. It appears that NSO-compounds inhibit the degradation of aromatic hydrocarbons, even at very low concentrations of NSO-compounds. Under nitrate-reducing conditions, toluene was easily biodegraded. The xylenes and ethylbenzene were degraded cometabolically if toluene was used as a primary carbon source; their removal was influenced by competitive inhibition with toluene. These interaction phenomena are discussed in this paper and a kinetic model taking into account cometabolism and competitive inhibition is proposed.

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Comparative Study of Chemical Stability of Two H1Antihistaminic Drugs, Terfenadine and ItsIn VivoMetabolite Fexofenadine, Using LC-UV Methods

Journal of Analytical Methods in Chemistry ◽

10.1155/2019/5790404 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10

Author(s):

Anna Gumieniczek ◽

Anna Berecka-Rycerz ◽

Rafał Pietraś ◽

Izabela Kozak ◽

Karolina Lejwoda ◽

...

Keyword(s):

Comparative Study ◽

Chemical Stability ◽

First Order ◽

First Order Kinetics ◽

Kinetics Of Degradation ◽

Effects Of Temperature ◽

High Doses ◽

Antihistaminic Drugs ◽

Kinetics Of

A comparative study of chemical stability of terfenadine (TER) and itsin vivometabolite fexofenadine (FEX) was performed. Both TER and FEX were subjected to high temperature at different pH and UV/VIS light at different pH and then quantitatively analyzed using new validated LC-UV methods. These methods were used to monitor the degradation processes and to determine the kinetics of degradation for both the compounds. As far as the effects of temperature and pH were concerned, FEX occurred more sensitive to degradation than TER. As far as the effects of UV/VIS light and pH were concerned, the both drugs were similarly sensitive to high doses of light. Using all stress conditions, the processes of degradation of TER and FEX followed the first-order kinetics. The results obtained for these two antihistaminic drugs could be helpful in developing their new derivatives with higher activity and stability at the same time.

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REGENERATION OF VISUAL PURPLE IN SOLUTION

The Journal of General Physiology ◽

10.1085/jgp.23.1.21 ◽

1939 ◽

Vol 23 (1) ◽

pp. 21-39 ◽

Cited By ~ 19

Author(s):

Aurin M. Chase ◽

Emil L. Smith

Keyword(s):

Order Process ◽

First Order ◽

Color Changes ◽

Violet Light ◽

Frog Retina ◽

Significant Difference ◽

Kinetics Of ◽

Photosensitive Substance ◽

Subsequent Regeneration

1. Measurements of visual purple regeneration in solution have been made by a procedure which minimized distortion of the results by other color changes so that density changes caused by the regenerating substance alone are obtained. 2. Bleaching a visual purple solution with blue and violet light causes a greater subsequent regeneration than does an equivalent bleaching with light which lacks blue and violet. This is due to a photosensitive substance which has a gradually increasing effective absorption toward the shorter wavelengths. It is uncertain whether this substance is a product of visual purple bleaching or is present in the solution before illumination. 3. The regeneration of visual purple measured at 560 mµ is maximal at about pH 6.7 and decreases markedly at more acid and more alkaline pH's. 4. The absorption spectrum of the regenerating material shows only a concentration change during the course of regeneration, but has a higher absorption at the shorter wavelengths than has visual purple before illumination. 5. Visual purple extractions made at various temperatures show no significant difference in per cent of regeneration. 6. The kinetics of regeneration is usually that of a first order process. Successive regenerations in the same solution have the same velocity constant but form smaller total amounts of regenerated substance. 7. In vivo, the frog retina shows no additional oxygen consumption while visual purple is regenerating.

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Comparative gene expression profiling of mouse ovaries upon stimulation with natural equine chorionic gonadotropin (N-eCG) and tethered recombinant-eCG (R-eCG)

10.21203/rs.3.rs-18763/v5 ◽

2020 ◽

Author(s):

Kwan-Sik Min ◽

Jong-Ju Park ◽

So-Yun Lee ◽

Munkhzaya Byambaragchaa ◽

Myung-Hwa Kang

Keyword(s):

Gene Expression ◽

Chorionic Gonadotropin ◽

Expression Profiles ◽

Expression System ◽

Laboratory Animals ◽

Metabolic Clearance ◽

Qrt Pcr ◽

Significant Difference ◽

Equine Chorionic Gonadotropin

Abstract Background: Equine chorionic gonadotropin (eCG) induces super-ovulation in laboratory animals. Notwithstanding its extensive usage, limited information is available regarding the differences between the in vivo effects of natural eCG (N-eCG) and recombinant eCG (R-eCG). This study aimed to investigate the gene expression profiles of mouse ovaries upon stimulation with N-eCG and R-eCG produced from CHO-suspension (CHO-S) cells. R-eCG gene was constructed and transfected into CHO-S cells and quantified. Subsequently, we determined the metabolic clearance rate (MCR) of N-eCG and R-eCG up to 24 h after intravenous administration through the mice tail vein and identified differentially expressed genes in both ovarian tissues, via quantitative real-time PCR (qRT-PCR) and immunohistochemistry (IHC).Results: R-eCG was markedly expressed initially after transfection and maintained until recovery on day 9. Glycan chains were substantially modified in R-eCG protein produced from CHO-S cells and eliminated through PNGase F treatment. The MCR was higher for R-eCG than for N-eCG, and no significant difference was observed after 60 min. Notwithstanding their low concentrations, R-eCG and N-eCG were detected in the blood at 24h post-injection. Microarray analysis of ovarian tissue revealed that 20 of 12,816 genes assessed therein were significantly up-regulated and 43 genes were down-regulated by >2-fold in the group that received R-eCG (63 [0.49%] differentially regulated genes in total). The microarray results were concurrent with and hence validated by those of RT-PCR, qRT-PCR, and IHC analyses.Conclusions: The present results indicate that R-eCG can be adequately produced through a cell-based expression system through post-translational modification of eCG and can induce ovulation in vivo. These results provide novel insights into the molecular mechanisms underlying the up- or down-regulation of specific ovarian genes and the production of R-eCG with enhanced biological activity in vivo.

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Evaluating Hepatobiliary Transport with 18F-Labeled Bile Acids: The Effect of Radiolabel Position and Bile Acid Structure on Radiosynthesis and In Vitro and In Vivo Performance

Contrast Media & Molecular Imaging ◽

10.1155/2018/6345412 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Stef De Lombaerde ◽

Ken Kersemans ◽

Sara Neyt ◽

Jeroen Verhoeven ◽

Christian Vanhove ◽

...

Keyword(s):

Bile Acid ◽

Bile Acids ◽

Membrane Vesicles ◽

Hepatic Uptake ◽

Hepatobiliary Transport ◽

Bile Acid Transporters ◽

Significant Difference ◽

The Impact

Introduction. An in vivo determination of bile acid hepatobiliary transport efficiency can be of use in liver disease and preclinical drug development. Given the increased interest in bile acid Positron Emission Tomography- (PET-) imaging, a further understanding of the impact of 18-fluorine substitution on bile acid handling in vitro and in vivo can be of significance. Methods. A number of bile acid analogues were conceived for nucleophilic substitution with [18F]fluoride: cholic acid analogues of which the 3-, 7-, or 12-OH function is substituted with a fluorine atom (3α-[18F]FCA; 7β-[18F]FCA; 12β-[18F]FCA); a glycocholic and chenodeoxycholic acid analogue, substituted on the 3-position (3β-[18F]FGCA and 3β-[18F]FCDCA, resp.). Uptake by the bile acid transporters NTCP and OATP1B1 was evaluated with competition assays in transfected CHO and HEK cell lines and efflux by BSEP in membrane vesicles. PET-scans with the tracers were performed in wild-type mice (n=3 per group): hepatobiliary transport was monitored and compared to a reference tracer, namely, 3β-[18F]FCA. Results. Compounds 3α-[18F]FCA, 3β-[18F]FGCA, and 3β-[18F]FCDCA were synthesized in moderate radiochemical yields (4–10% n.d.c.) and high radiochemical purity (>99%); 7β-[18F]FCA and 12β-[18F]FCA could not be synthesized and included further in this study. In vitro evaluation showed that 3α-FCA, 3β-FGCA, and 3β-FCDCA all had a low micromolar Ki-value for NTCP, OATP1B1, and BSEP. In vivo, 3α-[18F]FCA, 3β-[18F]FGCA, and 3β-[18F]FCDCA displayed hepatobiliary transport with varying efficiency. A slight yet significant difference in uptake and efflux rate was noticed between the 3α-[18F]FCA and 3β-[18F]FCA epimers. Conjugation of 3β-[18F]FCA with glycine had no significant effect in vivo. Compound 3β-[18F]FCDCA showed a significantly slower hepatic uptake and efflux towards gallbladder and intestines. Conclusion. A set of 18F labeled bile acids was synthesized that are substrates of the bile acid transporters in vitro and in vivo and can serve as PET-biomarkers for hepatobiliary transport of bile acids.

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Kinetic Profiling of the Hydrolytic Reaction of Benazepril: Metabolic Pathway Simulation

Journal of AOAC International ◽

10.5740/jaoacint.17-0121 ◽

2018 ◽

Vol 101 (4) ◽

pp. 1009-1013

Author(s):

A Hemdan ◽

Adel M Michael

Keyword(s):

Room Temperature ◽

Enzyme Inhibitor ◽

Internal Standard ◽

Official Method ◽

First Order ◽

First Order Kinetics ◽

Accuracy And Precision ◽

Inhibitor Analysis ◽

Hydrolytic Reaction ◽

Significant Difference

Abstract A simple, specific, and rapid kinetic study of benazepril (BNZ) hydrolysis was developed and validated using HPLC. BNZ was degraded using 0.1 N sodium hydroxide at room temperature to produce benazeprilat, which is an active metabolite of BNZ and acts as an angiotensin-converting enzyme inhibitor. Analysis was carried out using an Athena C18 column (4.6 × 250 mm, 5 µm particle size). The mobile phase consists of a mixture of phosphate buffer (pH 4.5) and acetonitrile (53 + 47, v/v) at a flow rate of 1 mL/min. UV detection was accomplished at 242 nm using moexipril as the internal standard. The method was validated according to International Conference on Harmonization guidelines, and the calibration curve was linear over the range 10–100 µg/mL, with acceptable accuracy and precision. Kinetic profiling of the hydrolysis was shown to follow pseudo-first-order kinetics. The method was applied to the assay of BNZ in combined dosage form with no interference from other ingredients. The obtained results were statistically compared with those of the official method, showing no significant difference.

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Phase I and pharmacokinetic (PK) dose-adjusted study of IV vinflunine (VFL) in cancer patients with liver dysfunction (LD): Pharmacokinetic results

Journal of Clinical Oncology ◽

10.1200/jco.2007.25.18_suppl.2523 ◽

2007 ◽

Vol 25 (18_suppl) ◽

pp. 2523-2523

Author(s):

B. Paule ◽

F. Saliba ◽

M. Gil-Delgado ◽

C. Puozzo ◽

S. Favrel ◽

...

Keyword(s):

Phase I ◽

Antitumour Activity ◽

Vinca Alkaloid ◽

Individual Variability ◽

Pharmacokinetic Parameters ◽

Control Group ◽

Microtubule Inhibitor ◽

Blood Concentrations ◽

Significant Difference

2523 Background: VFL is a novel microtubule inhibitor of the vinca alkaloid class that has shown high antitumour activity in several in vivo tumour models and in clinical trials. VFL is mainly eliminated through metabolism and bile excretion. Therefore this trial was designed to determine if LD could increase exposure and toxicity of VFL and require a dose-adjustment. Methods: This trial had a sequential design with the objective of determining the maximal tolerated dose (MTD) and the recommended dose (RD) in three groups of LD based on clinical and biological criteria: mild (PT > 70% and UNL < serum bilirubin = 1.5xUNL), moderate (Child-Pugh A) and severe (Child-Pugh B). VFL and 4-O-deacetylvinflunine (DVFL), its only active metabolite, were quantified in whole blood during cycle 1. PK parameters (AUCinf, Cltot) were estimated using a non-compartmental analysis and were compared using a one-way ANOVA with group factor either between groups or between groups and a control group of 49 patients without LD enrolled in phase I trials). Results: Three VFL doses were investigated: The inter-individual variability (CV) in AUCinf was approximately 30% for all groups. Even if AUCinf increased between mild and moderate groups, no difference was demonstrated between moderate and severe LD groups. All individual values were within the range of control values. Cltot were also similar between groups and the control group. Statistical analysis did not evidence any significant difference between groups. No difference was observed in blood concentrations of DVFL compared to the control group. No relationship between dose limiting toxicity and blood exposure was evidenced. Conclusions: The results showed that vinflunine and DVFL pharmacokinetic parameters do not appear to be affected by the degree of LD. However, the dose of VFL has to be adjusted to the level of LD for safety reasons. [Table: see text] No significant financial relationships to disclose.

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Comparative effects of fructose and glucose on the lipid and carbohydrate metabolism of perfused rat liver

British Journal Of Nutrition ◽

10.1079/bjn19760062 ◽

1976 ◽

Vol 36 (1) ◽

pp. 113-126 ◽

Cited By ~ 26

Author(s):

D. L. Topping ◽

P. A. Mayes

Keyword(s):

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Liver Glycogen ◽

Hepatic Uptake ◽

Standard Diet ◽

Blood Concentrations ◽

Hepatic Portal Vein ◽

Hepatic Portal ◽

Blood Glucose Concentrations

1. Livers from rats fed on a standard diet were perfused with whole blood, and infused continuously with glucose and fructose at equimolar rates.2. Infusion of fructose increased both the secretion of very-low-density-lipoprotein (VLDL)-triglycerides and the incorporation of free fatty acids (FFA) from the perfusate into VLDL-lipids, but neither of these two processes was affected by infusion of glucose.3. Infusion of fructose decreased the oxidation and increased the esterification of FFA, but glucose infusion had no effect on these processes. When fructose and glucose were infused together there was a further decrease in oxidation.4. When fructose was infused alone or together with glucose, blood concentrations rapidly became stabilized at those found in the hepatic portal vein in vivo, with similar rates of hepatic uptake to those found in the intact animal. Infusion of glucose alone resulted in continuously increasing perfusate glucose concentrations, and rates of uptake which were only 20 % of those for fructose. Blood glucose concentrations were reduced, and lactate concentrations were increased by fructose infusion, and when glucose and fructose were infused together there was a greatly increased rate of glucose uptake.5. Liver glycogen was not affected by the infusion of fructose or glucose alone; however, their combined addition significantly increased its concentration.6. Uptake of perfusate FFA was not affected by either fructose or glucose infusions.7. The results are discussed in terms of the differences in nutrition and metabolism between glucose and fructose, with particular reference to the development of hyper- triglyceridaemia.

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Effect of liposomal phospholipid composition on cholesterol transfer between microsomal and liposomal vesicles

Biochemical Journal ◽

10.1042/bj2380647 ◽

1986 ◽

Vol 238 (3) ◽

pp. 647-652 ◽

Cited By ~ 20

Author(s):

C Bhuvaneswaran ◽

K A Mitropoulos

Keyword(s):

Activation Energy ◽

Enzyme Activity ◽

Control System ◽

Phospholipid Composition ◽

Acyltransferase Activity ◽

Phosphatidylcholine Liposomes ◽

First Order ◽

First Order Kinetics ◽

Phospholipid Liposomes

Preincubation of rat liver microsomal vesicles at 37 degrees C in the presence of [3H]cholesterol/phospholipid liposomes results in a net transfer of cholesterol from liposomes to microsomal vesicles. This transfer follows first-order kinetics. For similar concentrations of the donor vesicles, rates of transfer are about 6-8 times lower with cholesterol/sphingomyelin liposomes compared with cholesterol/phosphatidylcholine liposomes. Also, transfer of cholesterol from cholesterol/sphingomyelin liposomes to microsomal vesicles reveals a larger activation energy than for the process from cholesterol/phosphatidylcholine liposomes. There is a significant correlation between the amount of liposomal cholesterol transferred to microsomal vesicles during preincubation and the increase found with acyl-CoA:cholesterol acyltransferase activity in these microsomes over their corresponding controls. If, however, liposomes made solely of phospholipids are substituted for the cholesterol/phospholipid liposomes in the preincubation system containing microsomal vesicles, then the acyl-CoA:cholesterol acyltransferase activity is decreased compared with the corresponding control system. Both sphingomyelin and phosphatidylcholine liposomes are equally effective in decreasing the enzyme activity. These results offer direct kinetic evidence for the positive correlation between cholesterol and sphingomyelin found in vivo in biological membranes.

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Comparative gene expression profiling of mouse ovaries upon stimulation with native equine chorionic gonadotropin (eCG) and tethered recombinant-eCG

10.21203/rs.3.rs-18763/v1 ◽

2020 ◽

Author(s):

Kwan-Sik Min ◽

Jong-Ju Park ◽

So-Yun Lee ◽

Munkhzaya Byambaragchaa ◽

Myung-Hwa Kang

Keyword(s):

Gene Expression ◽

Chorionic Gonadotropin ◽

Expression Profiles ◽

Expression System ◽

Laboratory Animals ◽

Metabolic Clearance ◽

Qrt Pcr ◽

Significant Difference ◽

Equine Chorionic Gonadotropin

Abstract Background: Equine chorionic gonadotropin (eCG) induces super-ovulation in laboratory animals. Notwithstanding its extensive usage, limited information is available regarding the differences between the in vivo effects of native eCG and recombinant eCG (rec-eCG). This study aimed to investigate the gene expression profiles of mouse ovaries upon stimulation with native eCG and rec-eCG produced from CHO-suspension (CHO-S) cells. eCG and rec-eCG were cloned and transfected into CHO-S cells and quantified. Thereafter, we determined the metabolic clearance rate (MCR) of native eCG and rec-eCG up to 24 h after intravenous administration through the tail vein and identified differentially expressed genes in both ovarian tissues, via quantitative real-time PCR (qRT-PCR) and immunohistochemistry (IHC).Results: Rec-eCG was markedly up-regulated initially after transfection and maintained until recovery on day 9. Oligosaccharide chains were substantially modified in rec-eCG protein produced from CHO-S cells and eliminated through PNGase F treatment. The MCR was slightly lower for rec-eCG than for eCG, and no significant difference was observed after 60 min. Notwithstanding their low concentration, rec-eCG and native eCG were detected in the blood at 24h post-injection. Microarray analysis of ovarian tissue revealed that 20 of 12,816 genes assessed therein were significantly up-regulated and 43 genes were down-regulated by >2-fold in the group receiving rec-eCG (63 [0.49%] differentially regulated genes in total). The microarray results were concurrent with and hence validated by those of RT-PCR, qRT-PCR, and IHC analyses.Conclusions: The present results indicate that rec-eCG can be adequately produced through a cell-based expression system through post-translational modification of eCG and can induce ovulation in vivo. These results provide novel insights into the molecular mechanisms underlying the up- or down-regulation of specific ovarian genes and the production of rec-eCG with enhanced biological activity in vivo.

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