Hypersensitive Electrochemical Sequential Monitoring of Total IgE and their Effects with Ovalbumin Induced Mice

Monitoring of specific biomarker is critical for determining progression of a disease or efficacy of a treatment. Currently, the standard for assessing amount of specific biomarkers is the enzyme linked immunosorbent assay (ELISA), which measures quantities on the nanogram scale. However, ELISA has high material costs, long incubation periods, requires large volume of samples and involves special instruments, which necessitates clinical samples to be sent to a lab. In order to provide rapid, accurate, easy, point-of-care measurement of biomarkers, electrochemical immunosensor can be used to provide specific and sensitive biomarker detection. Immunosensor allow near real-time results, reduced costs, and simple assays with no labelling. In this work, we developed an electrochemical biosensor to measure total immunoglobulin E (IgE), a marker of asthma disease that varies with age, gender, and disease in concentrations from 0.3–1000 ng/mL with consuming 20 µL volume of real blood sample. Also, sequential monitoring of total IgE with OVA induced mice is another application of this work and this sensor is an alternative approach for recording data and a more effective assay for understanding the cytotoxic effects of toxic materials

Agonist-Induced Endocytosis and Receptor Phosphorylation Mediate Resensitization of Dopamine D2 Receptors

The regulatory mechanisms and functional roles of agonist-induced internalization of G protein-coupled receptors (GPCRs) were analyzed using mutant dopamine D2 receptors (D2Rs) in which all possible GPCR kinase (GRK) phosphorylation sites were mutated or the affinity for β-arrestins was altered. Agonist-induced internalization of D2Rs involved a phosphorylation-dependent component, which was mediated by serine/threonine (S/T) residues in the second loop and T225 in the third loop, and a phosphorylation-independent component. GRK2-mediated enhancement of the internalization and inhibition of D2R signaling did not involve receptor phosphorylation, and only the former required the enzymatic activity of GRK2. The phosphorylation-deficient mutant (D2R-intracellular loop 2/3) recycled more slowly and showed more agonist-induced desensitization than did the wild-type D2R, suggesting that receptor phosphorylation mediates the recycling of the internalized receptors and enhances receptor resensitization. Blockade of the agonist-induced internalization of D2R-intracellular loop 2/3 provoked desensitization as in wild-type D2R, suggesting that certain cellular processes other than receptor dephosphorylation occurring within the endocytic vesicle are responsible for the resensitization of D2R. When dissociation between D2R and β-arrestin was inhibited or when the expression of cellular β-arrestins was decreased, agonist-induced desensitization of D2R did not occur, suggesting that dissociation from β-arrestin is the main cellular process required for resensitization of D2R and is achieved through agonist-induced internalization. These results indicate that, in the regulation of some GPCRs, phosphorylation-independent association with β-arrestin plays a major role in agonist-induced desensitization