Volume of distribution terms for a drug (ceftriaxone) exhibiting concentration-dependent protein binding II. Physiological significance

1983 ◽  
Vol 25 (3) ◽  
pp. 407-412 ◽  
Author(s):  
P. J. McNamara ◽  
M. Gibaldi ◽  
K. Stoeckel
Keyword(s):  
Protein Binding ◽  
Volume Of Distribution ◽  
Physiological Significance ◽  
Dependent Protein

scholarly journals Single-Nucleotide Polymorphisms Sequencing Identifies Candidate Functional Variants at Prostate Cancer Risk Loci

Genes ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 547 ◽  
Author(s):  
Peng Zhang ◽  
Lori S. Tillmans ◽  
Stephen N. Thibodeau ◽  
Liang Wang
Keyword(s):  
Prostate Cancer ◽  
Cancer Risk ◽  
Single Nucleotide Polymorphisms ◽  
Protein Binding ◽  
Prostate Cancer Risk ◽  
Sequencing Analysis ◽  
Nucleotide Polymorphisms ◽  
Single Nucleotide ◽  
Functional Variants ◽  
Dependent Protein

Genome-wide association studies have identified over 150 risk loci that increase prostate cancer risk. However, few causal variants and their regulatory mechanisms have been characterized. In this study, we utilized our previously developed single-nucleotide polymorphisms sequencing (SNPs-seq) technology to test allele-dependent protein binding at 903 SNP sites covering 28 genomic regions. All selected SNPs have shown significant cis-association with at least one nearby gene. After preparing nuclear extract using LNCaP cell line, we first mixed the extract with dsDNA oligo pool for protein–DNA binding incubation. We then performed sequencing analysis on protein-bound oligos. SNPs-seq analysis showed protein-binding differences (>1.5-fold) between reference and variant alleles in 380 (42%) of 903 SNPs with androgen treatment and 403 (45%) of 903 SNPs without treatment. From these significant SNPs, we performed a database search and further narrowed down to 74 promising SNPs. To validate this initial finding, we performed electrophoretic mobility shift assay in two SNPs (rs12246440 and rs7077275) at CTBP2 locus and one SNP (rs113082846) at NCOA4 locus. This analysis showed that all three SNPs demonstrated allele-dependent protein-binding differences that were consistent with the SNPs-seq. Finally, clinical association analysis of the two candidate genes showed that CTBP2 was upregulated, while NCOA4 was downregulated in prostate cancer (p < 0.02). Lower expression of CTBP2 was associated with poor recurrence-free survival in prostate cancer. Utilizing our experimental data along with bioinformatic tools provides a strategy for identifying candidate functional elements at prostate cancer susceptibility loci to help guide subsequent laboratory studies.

THE EFFECTS OF CALCIUM ON PROTEIN-BINDING AND METABOLISM OF ARGININE VASOPRESSIN IN RATS

1965 ◽  
Vol 32 (2) ◽  
pp. 141-151 ◽  
Author(s):  
M. W. SMITH ◽  
N. A. THORN
Keyword(s):  
Protein Binding ◽  
Calcium Chloride ◽  
Blood Volume ◽  
Arginine Vasopressin ◽  
Binding Sites ◽  
Blood Concentration ◽  
Blood Circulation ◽  
Volume Of Distribution ◽  
Rat Serum

SUMMARY Hypercalcaemia produced in rats by the intravenous injection of calcium chloride, slowed the rate of disappearance of injected vasopressin from the blood circulation. 24% of the vasopressin injected appeared in the urine of hypercalcaemic rats compared with 7 % in control animals. Vasopressin injected intravenously into control rats was distributed in a volume equal to the blood volume but when rats had been made hypercalcaemic, the theoretical volume of distribution was three to four times greater. Antidiuresis produced by injection of large doses of vasopressin into hydrated rats was little affected by changes in the blood concentration of calcium. Calcium chloride injected intravenously into hydrated rats resulted in a temporary antidiuresis. Experiments in vitro with Sephadex G-25 showed that both ox neurophysin and rat serum protein bind vasopressin and that calcium interferes with the binding. It is suggested that calcium can compete directly with vasopressin for acidic binding sites on proteins; that this can cause the release of vasopressin and alter the transport and possibly the rate of inactivation, of vasopressin.

scholarly journals Novel Population Pharmacokinetic Approach to Explain the Differences between Cystic Fibrosis Patients and Healthy Volunteers via Protein Binding

Pharmaceutics ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 286 ◽  
Author(s):  
Nirav Shah ◽  
Jürgen Bulitta ◽  
Martina Kinzig ◽  
Cornelia Landersdorfer ◽  
Yuanyuan Jiao ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Protein Binding ◽  
Healthy Volunteers ◽  
Plasma Concentrations ◽  
Volume Of Distribution ◽  
Population Pharmacokinetic ◽  
Unbound Fraction ◽  
Low Protein ◽  
Novel Approach ◽  
Special Patient

The pharmacokinetics in patients with cystic fibrosis (CF) has long been thought to differ considerably from that in healthy volunteers. For highly protein bound β-lactams, profound pharmacokinetic differences were observed between comparatively morbid patients with CF and healthy volunteers. These differences could be explained by body weight and body composition for β-lactams with low protein binding. This study aimed to develop a novel population modeling approach to describe the pharmacokinetic differences between both subject groups by estimating protein binding. Eight patients with CF (lean body mass [LBM]: 39.8 ± 5.4kg) and six healthy volunteers (LBM: 53.1 ± 9.5kg) received 1027.5 mg cefotiam intravenously. Plasma concentrations and amounts in urine were simultaneously modelled. Unscaled total clearance and volume of distribution were 3% smaller in patients with CF compared to those in healthy volunteers. After allometric scaling by LBM to account for body size and composition, the remaining pharmacokinetic differences were explained by estimating the unbound fraction of cefotiam in plasma. The latter was fixed to 50% in male and estimated as 54.5% in female healthy volunteers as well as 56.3% in male and 74.4% in female patients with CF. This novel approach holds promise for characterizing the pharmacokinetics in special patient populations with altered protein binding.

Apparent Valproic Acid Neurotoxicity in a Hypoalbuminemic Patient

1993 ◽  
Vol 27 (1) ◽  
pp. 32-35 ◽  
Author(s):  
Barry E. Gidal ◽  
D. Michael Collins ◽  
Brad R. Beinlich
Keyword(s):  
Valproic Acid ◽  
Protein Binding ◽  
Plasma Protein Binding ◽  
Plasma Protein ◽  
Plasma Concentrations ◽  
Free Fraction ◽  
Laboratory Evaluation ◽  
Neurologic Symptoms ◽  
Drug Concentrations ◽  
Dependent Protein

OBJECTIVE: To report a case of possible neurotoxicity caused by markedly elevated free valproic acid (VPA) plasma concentrations. CASE SUMMARY: A patient with a history of a mixed-type seizure disorder that had been treated with oral VPA 1000 mg four times daily for the previous two years was admitted to the neurology service with the chief complaint of increasing difficulty in walking and involuntary muscle jerks that were new in onset. The patient was hypersomnolent and dysarthric. The total plasma VPA concentration was 103 μg/mL, which was only slightly above the recommended therapeutic range (50–100 μg/mL). VPA free fraction and free plasma concentrations, however, were unexpectedly elevated (26 percent, 26.8 μg/mL, respectively). Further laboratory evaluation revealed a serum albumin concentration of 33 g/L. The neurologic symptoms resolved upon VPA dosage reduction. DISCUSSION: VPA displays concentration-dependent protein binding, resulting in disproportionate increases in drug free fraction with increasing drug concentration. This effect may be magnified in patients with decreased plasma protein-binding capacity. The plasma protein-binding kinetics of VPA are reviewed and the implications for therapeutic drug monitoring are discussed. CONCLUSIONS: It is likely that the markedly elevated free VPA plasma concentrations contributed to the neurologic symptoms displayed in this patient. In patients with decreased albumin concentrations, failure to recognize concentration-dependent protein binding, as well as exclusive reliance upon total drug concentrations, may lead to erroneous pharmacokinetic and therapeutic interpretations.

Phenobarbital-dependent protein binding to Barbie box-like sequences in the coding region of cytochrome P450BM-3 gene from Bacillus megaterium

Gene ◽  
1996 ◽  
Vol 183 (1-2) ◽  
pp. 97-101 ◽  
Author(s):  
Elena K. Gaidamakova ◽  
Oleg V. Alpatov ◽  
Igor V. Ischenko ◽  
Sergei P. Kovalenko ◽  
Vyacheslav V. Lyakhovich
Keyword(s):  
Protein Binding ◽  
Bacillus Megaterium ◽  
Coding Region ◽  
Dependent Protein

Influence of hypercapnia and (or) hypoxemia and metabolic acidosis on sulfamethazine kinetics in the conscious rabbit

1984 ◽  
Vol 62 (9) ◽  
pp. 1170-1177 ◽  
Author(s):  
Patrick du Souich ◽  
Hélène Courteau
Keyword(s):  
Metabolic Acidosis ◽  
Protein Binding ◽  
Flow Distribution ◽  
Blood Gases ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Experimental Conditions ◽  
Multiple Blood ◽  
Total Body ◽  
Acute Changes

The aim of the present study was to determine whether acute changes in blood gases and pH alter sulfamethazine (SMZ) kinetics. Groups of conscious rabbits were exposed for 270 min either to air or to a high CO2 and (or) low O2 atmosphere to produce hypercapnia, hypoxemia, or both. Another group of rabbits received 47 mL/kg of 0.3 M HCl by gavage tube to induce metabolic acidosis. Once the blood gases were stabilized, the rabbits received 20 mg/kg SMZ i.v. Multiple blood samples were drawn for 180 min to assess SMZ kinetic parameters, SMZ protein binding, and blood gases. Fifteen minutes after the administration of SMZ, a suboccipital puncture was performed to determine the concentration of SMZ in the cerebrospinal fluid (CSF). Urine was collected for the first 180 min through a sterile catheter and for the next 21 h in a metabolic cage. Hypercapnia alone did not significantly influence SMZ kinetics. Hypoxemia, hypoxemia combined with hypercapnia, and metabolic acidosis increased the SMZ apparent volume of distribution (V) and total body clearance (CL). This increase in the SMZ V correlated positively (p < 0.01) to the ratio of SMZ concentration in CSF to SMZ concentration in plasma. The increase in SMZ CL was mainly due to an increase in nonrenal clearance, although a slight increase in SMZ renal clearance was also observed. Several factors may be related to these kinetic changes: (i) SMZ plasma protein binding decreased under these experimental conditions as a result of a decrease in the apparent intrinsic association constant; (ii) in addition, SMZ nonionized fraction may have increased by 42% in hypercapnia combined with hypoxemia and metabolic acidosis; (iii) theoretically, changes in blood flow distribution may have also contributed. It was concluded that the acute modification of blood gases and pH do influence SMZ kinetics, hypoxemia being the factor most responsible for kinetic changes.

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