Defective cortisol binding globulin affinity in association with adrenal hyperfunction: a case report

1980 ◽  
Vol 95 (2) ◽  
pp. 194-197 ◽  
Author(s):  
J. M. Barragry ◽  
. Stuart Mason ◽  
D. A. Seamark ◽  
D. J. H. Trafford ◽  
H. L. J. Makin
Keyword(s):  
Case Report ◽  
Binding Affinity ◽  
Binding Capacity ◽  
Adrenal Hyperfunction

Abstract. A patient with an apparent abnormality of cortisol binding globulin (CBG) is reported. Investigations showed that while the plasma CBG binding capacity (equivalent to the plasma CBG concentration) was normal, the binding affinity was reduced by a factor of four. The significance of this observation is discussed with regard to its possible role in the development of the adrenocortical hyperfunction also seen in this patient.

The Effect of Drugs on Albumin Binding of Bilirubin and on Free Bilirubin Concentration as Determined by Fluorescence Quenching

1979 ◽  
Vol 13 (9) ◽  
pp. 498-503
Author(s):  
John H. Drew ◽  
Rhondda Wells
Keyword(s):  
Fluorescence Quenching ◽  
Binding Affinity ◽  
Newborn Infant ◽  
Total Bilirubin ◽  
Binding Capacity ◽  
Albumin Binding ◽  
Binding Parameters ◽  
Bilirubin Concentration ◽  
Phenytoin Sodium ◽  
Clinically Significant

Fluorescence quenching was used to determine the influence of five drugs commonly used in the newborn infant, on the binding of bilirubin to albumin, and to quantitate the resultant changes in binding parameters and the free bilirubin concentration. The five drugs studied were digoxin, furosemide, diazepam, phenytoin sodium, and theophylline. The primary influence of digoxin, furosemide, diazepam, and phenytoin sodium was on the affinity of albumin to bind bilirubin. They also affected the capacity of albumin to bind bilirubin, but to a lesser extent. Furosemide reduced the apparent binding affinity by 60 percent (p = 0.01), phenytoin sodium by 58 percent (p < 0.01), digoxin by 52 percent (p = 0.02), and diazepam by 45 percent (p = 0.03). Furosemide reduced the apparent binding capacity by 24 percent (p < 0.001), digoxin by 23 percent (p = 0.04), and diazepam by 13 percent (p = 0.10). Phenytoin sodium had a different effect on the apparent binding capacity: It increased the apparent capacity by 30 percent (p < 0.01). Theophylline had no significant effects on either binding affinity or capacity or free bilirubin concentration. Furosemide, digoxin, and diazepam significantly increased free bilirubin concentration at all total bilirubin concentrations; therefore, these drugs should be used with caution in the jaundiced newborn infant. Phenytoin sodium increased free bilirubin concentrations in the low total bilirubin ranges only; however, the increase was marginal and unlikely to be clinically significant.

Insulin binding to liver plasma membranes in salmonids with modified plasma insulin levels

1991 ◽  
Vol 69 (11) ◽  
pp. 2745-2750 ◽  
Author(s):  
Joaquim Gutiérrez ◽  
Erika M. Plisetskaya
Keyword(s):  
Binding Affinity ◽  
Plasma Insulin ◽  
Plasma Membranes ◽  
Coho Salmon ◽  
Binding Capacity ◽  
Specific Binding ◽  
Insulin Binding ◽  
Term Treatment ◽  
Liver Plasma Membranes ◽  
Number Of Binding Sites

Insulin binding to the liver plasma membranes was assessed in coho salmon (Oncorhynchus kisutch) injected intraperitoneally with 6.6 μmol arginine/g body weight, and in rainbow trout (Oncorhynchus mykiss) fasted for 40 days and then refed for 15 days. Corresponding control groups of fish were injected with saline (coho salmon) or fed regularly (trout). Arginine injection was followed by a substantial elevation of plasma insulin titres from 12.5 to 76.8 ng/mL, an increase in the binding capacity and, consequently, an increase in specific binding of insulin to the liver plasma membranes from 3.4 to 5.5%. The binding affinity remained unchanged. Food deprivation lowered plasma insulin titres from 13.2 to 3.0 ng/mL, increased the binding capacity, but decreased the binding affinity, so the specific binding remained essentially unchanged (5.6% in fed versus 5.1% in fasted fish). Refeeding of fasted fish resulted in restoration of insulin levels and an increase in binding affinity relative to both control and fasted groups of fish. This led to a substantial elevation of the specific binding of insulin up to 7.1%. The binding of insulin to liver plasma membranes in salmonids depends both on the number of binding sites (binding capactity) and on the binding affinity. Long-term treatment, such as food deprivation, resulted in altered affinity and capacity of binding, whereas short-term treatment, such as arginine injection, affected mostly the binding capacity. Modulation of the number of binding sites in liver plasma membrane according to the insulin level was observed only in experiments on trout conducted at a higher (15 °C) water temperature.

scholarly journals Binding Characteristics Study of DNA based Aptamers for E. coli O157:H7

Molecules ◽  
2021 ◽  
Vol 26 (1) ◽  
pp. 204
Author(s):  
Saika Siddiqui ◽  
Jie Yuan
Keyword(s):  
Comparative Study ◽  
Binding Affinity ◽  
Rapid Detection ◽  
Binding Capacity ◽  
Comprehensive Analysis ◽  
Binding Characteristics ◽  
E Coli ◽  
Fast Detection ◽  
The Common ◽  
Binding Capability

E. coli O157:H7 is a pathogenic bacterium producing verotoxins that could lead to serious complications such as hemolytic uremia syndrome. Fast detection of such pathogens is important. For rapid detection, aptamers are quickly gaining traction as alternative biorecognition molecules besides conventional antibodies. Several DNA aptamers have been selected for E. coli O157:H7. Nonetheless, there has not been a comparative study of the binding characteristics of these aptamers. In this work, we present a comprehensive analysis of binding characteristics including binding affinity (Kd) and binding capacity (Bmax) of DNA-based aptamers for E. coli O157:H7 using qPCR. Our results show that aptamer E18R has the highest binding capacity to E. coli 157:H7 and the highest specificity over non-pathogenic E. coli strains K12 and DH5α. Our study also finds that the common biotin-tag modification at 5′ end typically changes the binding capacity significantly. For most of the selected aptamers, the binding capacity after a biotin-tag modification decreases. There exists a discrepancy in the binding capability between the selected aptamer and the aptamer used for detection. Our study also shows that a lower concentration of Mg2+ ions in the binding buffer leads to a decrease in the binding capacity of E17F and E18R, while it does not affect the binding capacity of S1 and EcoR1.

scholarly journals Production of Long-Acting CNGRC–CPG2 Fusion Proteins: New Derivatives to Overcome Drug Immunogenicity of Ligand-Directed Enzyme Prodrug Therapy for Targeted Cancer Treatment

2021 ◽  
Vol 20 ◽  
pp. 153303382110573
Author(s):  
Layla Al-mansoori ◽  
Alanod D. Al Qahtani ◽  
Philip Elsinga ◽  
Sayed K. Goda
Keyword(s):  
Cancer Treatment ◽  
Cancer Cells ◽  
Binding Affinity ◽  
Cancer Cell ◽  
Fusion Proteins ◽  
Binding Capacity ◽  
Enzyme Prodrug Therapy ◽  
Kinetic Activity ◽  
Cellular Marker ◽  
Long Acting

Objectives: Aminopeptidase N (APN) is an enzyme highly expressed in metastatic cancers and could be used in targeted cancer therapy. Our previous work showed the successful construction of CNGRC–carboxypeptidase G2 (CPG2) and CNGRC–CPG2–CNGRC fusion proteins. Our conjugates and prodrugs were effective in targeting high APN-expressing cancer cells. In the present study, we aim to produce long-acting fusion proteins to overcome 2 of the main drawbacks of antibody-directed enzyme prodrug therapy. Methods: N-terminal and N-, C-terminal fusion CPG2, CNGRC–CPG2, and CNGRC–CPG2–CNGRC, respectively, were PEGylated using polyethylene glycol (PEG) maleimide (40K). We examined the effect of PEGylation on the therapeutic efficacy of the new products. The resulting PEGylated fusion proteins were tested for their stability, ex vivo immunotoxicity, binding capacity to their target on high HT1080, and low A549 APN-expressing cells. The catalytic activity of the resulting PEGylated fusion CPG2 proteins was investigated. Pro-drug “ZD2767P” cytotoxic effect in association with PEG CPG2–CNGRC fusion proteins on cancer cells was studied. Results: Our work demonstrated that the properties of the PEGylated single-fused proteins were significantly improved over that of un-PEGylated fused CPG2, and its kinetic activity and APN-binding affinity were not negatively affected by the PEGylation. Significantly, The PEGylated single-fused CPG2 had lower immunogenicity than the un-PEGylated CPG2. Our results, however, were different in the case of the PEGylated double-fused CPG2. Although its stability in human serum under physiological conditions was not significantly affected, the kinetic activity and its binding affinity to their cellular marker (APN) were substantially reduced. When the study was performed with high and low APN-expressing cancer cell lines, using the prodrug ZD2767p, the PEGylated fusion CPG2 demonstrated cancer cell killing effects. Conclusion: We have successfully produced PEGylated-CNGRC–CPG2, which is bioactive and with lower immunogenicity in ligand-directed enzyme prodrug therapy for cancer treatment.

scholarly journals Distinct functional properties of native somatostatin receptor subtype 5 compared with subtype 2 in the regulation of ACTH release by corticotroph tumor cells

2005 ◽  
Vol 289 (2) ◽  
pp. E278-E287 ◽  
Author(s):  
Joost van der Hoek ◽  
Marlijn Waaijers ◽  
Peter M. van Koetsveld ◽  
Diana Sprij-Mooij ◽  
Richard A. Feelders ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Binding Affinity ◽  
Binding Capacity ◽  
Somatostatin Receptor ◽  
Inhibitory Effect ◽  
Pcr Analysis ◽  
Receptor Subtype ◽  
Mrna Levels ◽  
Acth Release

In a series of human corticotroph adenomas, we recently found predominant mRNA expression of somatostatin (SS) receptor subtype 5 (sst5). After 72 h, the multiligand SS analog SOM230, which has a very high sst5 binding affinity, but not Octreotide (OCT), significantly inhibited basal ACTH release. To further explore the role of sst5 in the regulation of ACTH release, we conducted additional studies with mouse AtT-20 cells. SOM230 showed a 7-fold higher ligand binding affinity and a 19-fold higher potency in stimulating guanosine 5′- O-(3-thiotriphosphate) binding in AtT-20 cell membranes compared with OCT. SOM230 potently suppressed CRH-induced ACTH release, which was not affected by 48-h dexamethasone (DEX) pretreatment. However, DEX attenuated the inhibitory effects of OCT on ACTH release, whereas it increased the inhibitory potency of BIM-23268, an sst5-specific analog, on ACTH release. Quantitative PCR analysis showed that DEX lowered sst2A+2B mRNA expression significantly after 24 and 48 h, whereas sst5 mRNA levels were not significantly affected by DEX treatment. Moreover, Scatchard analyses showed that DEX suppressed maximum binding capacity (Bmax) by 72% when 125I-Tyr3-labeled OCT was used as radioligand, whereas Bmax declined only by 17% when AtT-20 cells were treated with [125I-Tyr11]SS-14. These data suggest that the sst5 protein, compared with sst2, is more resistant to glucocorticoids. Finally, after SS analog preincubation, compared with OCT both SOM230 and BIM-23268 showed a significantly higher inhibitory effect on CRH-induced ACTH release. In conclusion, our data support the concept that the sst5 receptor might be a target for new therapeutic agents to treat Cushing’s disease.

Bilirubin: Worked Out Years Ago?

PEDIATRICS ◽  
1979 ◽  
Vol 64 (3) ◽  
pp. 380-385 ◽  
Author(s):  
Rodney L. Levine
Keyword(s):  
Binding Affinity ◽  
Total Bilirubin ◽  
Binding Capacity ◽  
Scientific Basis ◽  
Unbound Bilirubin ◽  
Bilirubin Binding ◽  
Risk Of Treatment

1. The free bilirubin theory proposes that unbound bilirubin binds to and enters cells. The theory is simple, reasonable, and attractive. 2. To date, there is no evidence to support the free bilirubin theory over other possible mechanisms. 3. The measurement of free bilirubin is now technically possible for mixtures of purified bilirubin and albumin. Measurement in serum is promising, but proven methods still elude current capabilities. 4. At present, there is no justification for the use of free bilirubin tests in the management of jaundice. This evaluation holds for related tests, regardless of aliases: reserve binding capacity, bilirubin binding capacity, albumin saturation, loosely bound bilirubin, gel bound bilirubin, and binding affinity. 5. For smaller prematures, the concentration of total bilirubin at which the risk of kernicterus exceeds the risk of treatment is unknown. There is no scientific basis to guide the clinician in deciding when to institute treatment of jaundice in these babies. 6. Hyperbilirubinemia can lead to kernicterus. Whether it causes other, milder forms of neurologic and developmental damage is unknown. At present, there is no basis for treating jaundice with the hope of preventing such damage.

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