Nonlinear protein binding and enzyme heterogeneity: Effects on hepatic drug removal

1993 ◽  
Vol 21 (1) ◽  
pp. 43-74 ◽  
Author(s):  
Xin Xu ◽  
Paul Selick ◽  
K. Sandy Pang
Keyword(s):  
Protein Binding ◽  
Hepatic Drug ◽  
Enzyme Heterogeneity ◽  
Drug Removal ◽  
Heterogeneity Effects

scholarly journals Artificial Neural Network Modeling for Drug Dialyzability Prediction

2013 ◽  
Vol 16 (5) ◽  
pp. 665 ◽  
Author(s):  
Kahina Daheb ◽  
Mark L. Lipman ◽  
Patrice Hildgen ◽  
Julie J Roy
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Protein Binding ◽  
Plasma Protein Binding ◽  
Plasma Protein ◽  
Neural Network Modeling ◽  
Ann Model ◽  
Drug Concentrations ◽  
Drug Removal ◽  
Artificial Neural

Purpose. The purpose of this study was to develop an artificial neural network (ANN) model to predict drug removal during dialysis based on drug properties and dialysis conditions. Nine antihypertensive drugs were chosen as model for this study. Methods. Drugs were dissolved in a physiologic buffer and dialysed in vitro in different dialysis conditions (UFRmin/UFRmax, with/without BSA). Samples were taken at regular intervals and frozen at -20ºC until analysis. Extraction methods were developed for drugs that were dialysed with BSA in the buffer.  Drug concentrations were quantified by high performance liquid chromatography (HPLC) or mass spectrometry (LC/MS/MS). Dialysis clearances (CLDs) were calculated using the obtained drug concentrations.  An ANOVA with Scheffe’s pairwise adjustments was performed on the collected data in order to investigate the impact of drug plasma protein binding and ultrafiltration rate (UFR) on CLD. The software Neurosolutions® was used to build ANNs that would be able to predict drug CLD (output). The inputs consisted of dialysis UFR and the herein drug properties: molecular weight (MW), logD and plasma protein binding. Results. Observed CLDs were very high for the majority of the drugs studied. The addition of BSA in the physiologic buffer statistically significantly decreased CLD for carvedilol (p= 0.002) and labetalol (p<0.001), but made no significant difference for atenolol (p= 0.100). In contrast, varying UFR does not significantly affect CLD (p>0.025). Multiple ANNs were built and compared, the best model was a Jordan and Elman network which showed learning stability and good predictive results (MSEtesting = 129). Conclusion. In this study, we have developed an ANN-model which is able to predict drug removal during dialysis. Since experimental determination of all existing drug CLDs is not realistic, ANNs represent a promising tool for the prediction of drug CLD using drug properties and dialysis conditions. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

Transient Prealbumin- Associated Hyperthyroxinemia in TSH-Producing Pituitary Adenoma

1990 ◽  
Vol 29 (01) ◽  
pp. 40-43 ◽  
Author(s):  
W. Langsteger ◽  
P. Költringer ◽  
P. Wakonig ◽  
B. Eber ◽  
M. Mokry ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Case Report ◽  
Pituitary Adenoma ◽  
Thyroid Hormones ◽  
Protein Binding ◽  
Alpha Subunit ◽  
Normal Range ◽  
Thyroxine Binding Globulin ◽  
Free Thyroid Hormones ◽  
Transmission Computed Tomography

This case report describes a 38-year-old male who was hospitalized for further clarification of clinically mild hyperthyroidism. His increased total hormone levels, the elevated free thyroid hormones and the elevated basal TSH with blunted response to TRH strongly suggested a pituitary adenoma with inappropriate TSH incretion. Transmission computed tomography showed an intrasellar expansion, 16 mm in diameter. The neoplastic TSH production was confirmed by an elevated alpha-subunit and a raised molar alpha-sub/ATSH ratio. However, T4 distribution on prealbumin (PA, TTR), albumin (A) and thyroxine binding globulin (TBG) showed a clearly increased binding to PA (39%), indicating additional prealbumin-associated hyperthyroxinemia. The absolute values of PA, A and TBG were within the normal range. After removal of the TSH-producing adenoma, basal TSH, the free thyroid hormones and T4 binding to prealbumin returned to normal. Therefore, the prealbumin-associated hyperthyroxinemia had to be interpreted as a transitory phenomenon related to secondary hyperthyroidism (T4 shift from thyroxine binding globulin to prealbumin) rather than a genetically conditioned anomaly of protein binding.

Absorption, Metabolic Stability and Protein Binding Properties of Sutherlandioside B from Sutherlandia frutescens

Planta Medica ◽  
2008 ◽  
Vol 74 (03) ◽  
Author(s):  
VLM Madgula ◽  
B Avula ◽  
X Fu ◽  
XC Li ◽  
TJ Smillie ◽  
...  
Keyword(s):  
Protein Binding ◽  
Metabolic Stability ◽  
Binding Properties ◽  
Sutherlandia Frutescens

INCORPORATION OF IODIDE INTO ORGANIC COMPOUNDS IN THE GUINEA PIG THYROID

1963 ◽  
Vol 43 (1) ◽  
pp. 110-118 ◽  
Author(s):  
R. Ekholm ◽  
T. Zelander ◽  
P.-S. Agrell
Keyword(s):  
Guinea Pig ◽  
Protein Binding ◽  
Organic Compounds ◽  
Guinea Pigs ◽  
Microsomal Fraction ◽  
Thyroid Tissue ◽  
Particulate Fraction ◽  
Supernatant Fraction ◽  
Hydrolysis Of

ABSTRACT Guinea pigs, kept on a iodine-sufficient diet, were injected with Na131I and the thyroids excised from 45 seconds to 5 days later. The thyroid tissue was homogenized and separated into a combined nuclear-mitochondrial-microsomal fraction and a supernatant fraction by centrifugation at 140 000 g for one hour. Protein bound 131iodine (PB131I) and free 131iodide were determined in the fractions and the PB131I was analysed for monoiodotyrosine (MIT), diiodotyrosine (DIT) and thyroxine after hydrolysis of PB131I. As early as only 20 minutes after the Na131I-injection almost 100% of the particulate fraction 131I was protein bound. In the supernatant fraction the protein binding was somewhat less rapid and PB131I values above 90% of total supernatant 131I were not found until 3 hours after the injection. In all experiments the total amount of PB131I was higher in the supernatant than in the corresponding particulate fraction. The ratio between supernatant PB131I and pellet PB131I was lower in experiments up to 3 minutes and from 2 to 5 days than in experiments of 6 minutes to 20 hours. Hydrolysis of PB131I yielded, even in the shortest experiments, both MIT and DIT. The DIT/MIT ratio was lower in the experiments up to 2 hours than in those of 3 hours and over.

EVALUATION OF TISSUE STEROID BINDING IN VITRO

1971 ◽  
Vol 68 (1_Suppl) ◽  
pp. S223-S246 ◽  
Author(s):  
C. R. Wira ◽  
H. Rochefort ◽  
E. E. Baulieu
Keyword(s):  
Protein Binding ◽  
Binding Sites ◽  
Experimental System ◽  
Specific Protein ◽  
Coupling Mechanism ◽  
Target Tissue ◽  
Protein Binding Sites ◽  
Definition Of ◽  
Hormone Specificity

ABSTRACT The definition of a RECEPTOR* in terms of a receptive site, an executive site and a coupling mechanism, is followed by a general consideration of four binding criteria, which include hormone specificity, tissue specificity, high affinity and saturation, essential for distinguishing between specific and nonspecific binding. Experimental approaches are proposed for choosing an experimental system (either organized or soluble) and detecting the presence of protein binding sites. Techniques are then presented for evaluating the specific protein binding sites (receptors) in terms of the four criteria. This is followed by a brief consideration of how receptors may be located in cells and characterized when extracted. Finally various examples of oestrogen, androgen, progestagen, glucocorticoid and mineralocorticoid binding to their respective target tissues are presented, to illustrate how researchers have identified specific corticoid and mineralocorticoid binding in their respective target tissue receptors.

EVALUATION OF A SIMPLIFIED METHOD FOR DETERMINING SERUM THYROXINE BY COMPETITIVE PROTEIN BINDING ANALYSIS

1970 ◽  
Vol 64 (4) ◽  
pp. 630-636 ◽  
Author(s):  
Stephen C. Thorson ◽  
Ronald Tsujikawa ◽  
James L. Brown ◽  
Robert T. Morrison ◽  
Hamish W. McIntosh
Keyword(s):  
Protein Binding ◽  
Clinical Application ◽  
Thyroid Status ◽  
Serum Thyroxine ◽  
Binding Analysis ◽  
Simplified Method ◽  
Competitive Protein Binding ◽  
Hypothyroid Patients

ABSTRACT Serum thyroxine concentrations were determined in 66 euthyroid, 30 hyperthyroid and 13 hypothyroid patients using both the established Murphy method and a simplified method of competitive protein binding analysis. A diagnosis compatibility of 96% was found with both methods indicating that the simplified method has comparable clinical application as an initial screen of thyroid status.

AN IMPROVED METHOD FOR THE ASSAY OF PROGESTERONE BY COMPETITIVE PROTEIN BINDING

1970 ◽  
Vol 63 (2) ◽  
pp. 225-241 ◽  
Author(s):  
B. D. Reeves ◽  
M. L. A. de Souza ◽  
I. E. Thompson ◽  
E. Diczfalusy
Keyword(s):  
Protein Binding ◽  
Binding Sites ◽  
Entire Range ◽  
Improved Method ◽  
Plasma Progesterone ◽  
Extraction And Purification ◽  
Corticosteroid Binding Globulin ◽  
Competitive Protein Binding ◽  
The Individual ◽  
Range Of Values

ABSTRACT An improved method for the assay of plasma progesterone by competitive protein binding is described. The improvement is based upon rigorous control of the variables, the compensation for and standardisation of interfering factors inherent in the method and the use of a human corticosteroid binding globulin, that meets the requirements for sensitivity at levels of 1.0 ng of progesterone and below. The assessment of the reliability of the individual steps in the method as well as that of the complete method is presented. The sensitivity of the method is around 0.2 ng progesterone per ml plasma. Accuracy was measured by adding progesterone in amounts ranging from 0.0 to 1.0 ng to 1.0 ml plasma. There was a linear relationship between the progesterone added and recovered throughout the entire range of values, with a coefficient of correlation (r) of 0.94. Of 52 related steroids tested, none was found which would remain associated with progesterone following extraction and purification and which would also compete with progesterone for binding sites.

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