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BACKGROUND: Antigen-antibody reactions are a special field of molecular interactions. The physico-chemical nature of antigen-antibody binding and ligand-induced changes in the fine molecular structures of antigens during immunocomplex formation are less studied. However, these changes in the molecular appearance are extremely important for further molecular recognition. The major aim of this study is to clarify the physico-chemical modification of the antigen/hapten during immunobinding using model experiments. METHODS: An appropriate model system was designed for our investigations: fluorescein-iso-thiocyanate (FITC, isomer I) was used as the antigen (hapten), and its interactions with a specific antibody (monoclonal anti-FITC IgG1) were analyzed using spectrophotometry, different spectrofluorimetric methods and fluorescence polarization, and Fourier-transform infrared spectroscopic methods. RESULTS: Fluorescent polarization and infrared spectroscopic measurements detected a local decrease in the hydration degree in the submolecular area of the specific ligand between the small antigen (hapten) molecule and the hypervariable region of the specific IgG1, causing “rigidization” of molecular movements. Changes in hydration modified the molecular microenvironment, allowing them to influence further functions of both immunoglobulins and the antigen. CONCLUSION: Hydrophobic interactions with exclusion of water molecules around the binding sites seem to be thermodynamically strong enough for stable molecular binding without a covalent chemical interaction between the antigen and the antibody. The results of this study, together with data obtained in previous research, help understand the molecular dynamics of the antigen-antibody reaction better.

Introduction: Interleukin-6 (IL-6) is a multifunctional polypeptide cytokine composed of two glycoprotein chains, which plays an important role in many cellular reactions, pathological processes, diagnosis and treatment of diseases and so on. The detection of IL-6 plays a promising role in the cognition of clinical diseases.Methods: 4-mercaptobenzoic acid (4-MBA) was immobilized on the gold nanoparticles modified platinum carbon (PC) electrode with the linker IL-6 antibody, and finally formed an electrochemical sensor that specifically recognized IL-6. Through the highly specific antigen-antibody reaction, the IL-6 concentration of the samples to be detected. The performance of the sensor was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV).Results: The experimental results showed that the linear detection range of the sensor for IL-6 was 100 pg/mL–700 pg/mL and the detection limit was 3 pg/mL. In addition, the sensor had the advantages of high specificity, high sensitivity, high stability and reproducibility under the interference environment of bovine serum albumin (BSA), glutathione (GSH), glycine (Gly) and neuron specific enolase (NSE), which provided a prospect for specific antigen detection sensor.Discussion: The prepared electrochemical sensor successfully detected the content of IL-6 in standard and biological samples, showing excellent detection performance. No significant difference was found between the detection results of the sensor and that of ELISA. The sensor showed a very broad prospect in the application and detection of clinical samples.

Antigen–antibody reactions with conjugated magnetic nanoparticles (MNPs) are widely used for detecting viruses, bacteria, and proteins. In this study, we proposed a novel method for adsorbing antibodies directly on the surface of MNPs without coating any proteins. MNPs (Fe3O4; average size 4 nm) were synthesized by a thermal decomposition method using oleyl amine as a surfactant, the fabricated MNPs exhibit superparamagnetic characteristics, and the antibodies (anti- Bifidobacterium longum) were adsorbed. We found that 15 $\mu \text{g}$ /mg of antibody adsorbed to MNPs and were able to detect the bacteria bound to the produced antibody-MNPs based on the antigen–antibody reaction, offering potential for highly sensitive bacteria detection. [ABSTRACT FROM AUTHOR]

Aim We investigated the frequency of overall biphasic reactions, biphasic reactions that met the diagnostic criteria of anaphylaxis, and biphasic reactions that caused a severe abnormality in vital signs in patients who visited the emergency department of a tertiary hospital. Methods This retrospective cohort study included patients aged 18 years or over who presented with anaphylaxis at the emergency department of a tertiary care hospital between January 2014 and December 2016. The primary outcome was the incidence of biphasic reactions that caused a severe abnormality in vital signs and developed within 7 days. Secondary outcomes were the frequency of overall biphasic reactions and those that met the diagnostic criteria of anaphylaxis. Results In total, 437 patients aged over 18 years visited the emergency department during the study period. Among them, 202 were enrolled in this study. The proportion of patients who had overall biphasic reactions, those that met the diagnostic criteria of anaphylaxis, and those with a severe abnormality in vital signs was 8.9%, 3.0%, and 1.0%, respectively. Overall, 32.7% of patients were hospitalized, but hospitalization aided in the treatment of severe biphasic reactions at the early stage in only one patient. Conclusion We found that 8.9% of adult patients with anaphylaxis had a biphasic reaction, but biphasic reactions together with severe abnormalities in vital signs were rare.

Pneumocystis jirovecii can cause life-threatening pneumonia in immunocompromised patients. Traditional diagnostic testing has relied on staining and direct visualization of the life-forms in bronchoalveolar lavage fluid. This method has proven insensitive, and invasive procedures may be needed to obtain adequate samples. Molecular methods of detection such as polymerase chain reaction (PCR), loop-mediated isothermal amplification (LAMP), and antibody-antigen assays have been developed in an effort to solve these problems. These techniques are very sensitive and have the potential to detect Pneumocystis life-forms in noninvasive samples such as sputum, oral washes, nasopharyngeal aspirates, and serum. This review evaluates 100 studies that compare use of various diagnostic tests for Pneumocystis jirovecii pneumonia (PCP) in patient samples. Novel diagnostic methods have been widely used in the research setting but have faced barriers to clinical implementation including: interpretation of low fungal burdens, standardization of techniques, integration into resource-poor settings, poor understanding of the impact of host factors, geographic variations in the organism, heterogeneity of studies, and limited clinician recognition of PCP. Addressing these barriers will require identification of phenotypes that progress to PCP and diagnostic cut-offs for colonization, generation of life-form specific markers, comparison of commercial PCR assays, investigation of cost-effective point of care options, evaluation of host factors such as HIV status that may impact diagnosis, and identification of markers of genetic diversity that may be useful in diagnostic panels. Performing high-quality studies and educating physicians will be crucial to improve the rates of diagnosis of PCP and ultimately to improve patient outcomes. [ABSTRACT FROM AUTHOR]

The lungs and esophagus have a close anatomical and physiological relationship. Over the years, reflux-induced pulmonary injury has gained wider recognition, but the full effects of pulmonary disease on esophageal function are still unknown. Intrathoracic pressure dynamics potentially affect esophageal function, especially in patients with end-stage lung disease, both obstructive and restrictive. Lung transplantation is the only viable option for patients with end-stage pulmonary disease and has provided us with a unique opportunity to study these effects as transplantation restores the intrathoracic environment. Esophageal and foregut functional testing before and after transplantation provide insights into the pathophysiology of the foregut-pulmonary axis, such as how underlying pulmonary disease and intrathoracic pressure changes affect esophageal physiology. This review summarizes the available literature and shares the research experience of a lung transplant center, covering topics such as pre- and posttransplant foregut function, esophageal motility in lung transplant recipients, immune-mediated mechanisms of graft rejection associated with gastroesophageal reflux, and the role of antireflux surgery in this population. • Respiratory dynamics affect foregut function and vice versa. • The complex relationships can be elucidated in lung transplant patients. • Foregut function usually improves after lung transplantation. • Improvement in foregut function after lung transplantation prolongs survival. • Improvement of esophageal motility after lung transplantation may be predictable. [ABSTRACT FROM AUTHOR]

In this investigation, we attempted to produce a diagnostic Kit of Candida albicains infection (New Technique). This case-control study included 100 samples with various (fungi: C. albicans, Aspergillus spp., Tricophactone and bacterial Staphylococcus aureus) infection for immunocompromised women with average age (55-57) years and babies with average age (1-18) month in addition to 20 sample collected from apparently healthy individual (as control). Samples were collected from the skin scales(intertriginous)and skin swabs, mouth and vagina (swabs), the Samples were examined using the new technique compared to the routine methods of diagnosis, we found the new technique gave positive results for samples infected with C. albicans, while the rest of the samples non - C. albicans infection (fungal, Bacteria) gave a negative result. The results of the new technique were with (100%) sensitivity and (100%) specificity the same sensitivity and specificity (100%) to Vitek test were more sensitive (100%) and specialized (100%) for as compared to the results of other routine methods (Culture, Germ tube and API20C), according to the present result we can conclude that this new technique doesn’t need a long time with low cost and high rate of accuracy and physician can use it through the attending visit of patient without having to be sent to laboratory. [ABSTRACT FROM AUTHOR]

Herein, we report an improved minimum detectable displacement on a surface stress biosensor using optical interferometry, allowing for the detection of a low biomarker concentration via antigen-antibody reaction. The sensor is composed of a submicronthick freestanding polymethyl methacrylate (PMMA)/parylene-C membrane on a polydimethylsiloxane (PDMS) substrate with a microcavity to generate optical interference. The cavity structure was fabricated by transferring the submicron-thick bilayer to the highly adhesive PDMS substrate. The detection of human serum albumin antigen at a concentration of 1 pg/mL was achieved by antigen-antibody reaction using simultaneous optical and electrical measurements. In addition, the minimum detectable displacement of the optical interferometric surface stress sensor was determined to be 42.6 pm, representing an 11.7-fold improvement compared with conventional cantilever-based surface stress sensors. [ABSTRACT FROM AUTHOR]

The measurement of biological targets using nanoparticle magnetic markers has been extensively studied for its applications in magnetic immunoassays (MIAs). Compared with the optical immunoassay method, the MIA methods have some attractive characteristics such as a wash-free process that does not need bound/free marker separation and the ability to detect biological targets in a nebulous liquid. In addition, the wash-free process is very fast. In this paper, we tried to reduce the reaction time for the antigen-antibody reaction in order to make the MIA method more attractive. The reduction in reaction time and the detection characteristic of biological targets were demonstrated using C-reactive proteins (CRPs) as biological targets for diagnosing inflammation. To shorten the reaction time, a magnetic-shaking method using the magnetic field gradient from a neodymium magnet was developed. When comparing the reaction times with and without magnetic shaking, it was found that the reaction time decreased with magnetic shaking for all CRP concentrations. Even after the magnetic-shaking treatment, the dependence of the CRP concentration on the magnetic signal was observed. The number of surface modifications per magnetic marker and the magnetic marker concentration also affected the reaction time. In order to obtain the desired measurement range based on the CRP response characteristic, it is necessary to optimize the number of magnetic markers and polymer beads used. [ABSTRACT FROM AUTHOR]

Tuberculosis (TB) is a serious threat to human health. Although it is simple to prevent and treat TB, its prevalence is high due to the lack of facile, rapid, and low-cost diagnostic methods. In this paper, we present a liquid crystal (LC)-based on/off immunosensor (composed of two glass pieces) for the experimental as well as clinical diagnosis of TB. A variety of antigens are mixed and immobilized on the functionalized glass substrate (the bottom surface), and nanoparticle-doped LCs are arranged in an order that is determined by an electron transfer effect between nanoparticles and ITO glass (the top surface). After incubation of the substrate with TB antibody, substrate surface morphology significantly changes due to specific binding, disrupting the ordered arrangement of the LCs. The intensity of the optical signals, as seen under a polarized optical microscope, varies according the changes in the arrangements of LCs resulting from the presence or absence of binding with TB antibody. Based on these optical signals, we observed that 94% patients showed positive results, confirming the presence of the corresponding TB antibodies in the patients' serum. When samples from healthy people were used, 98% showed negative results, confirming the absence of TB antibodies. Hence, using this method, efficiently identifying the presence of TB antibodies in a sample is possible. This is especially beneficial in the diagnosis of clinical samples as this method does not require any special instrumentation or processes and will contribute to the development of novel, simple, and rapid methods for the diagnosis of TB. [ABSTRACT FROM AUTHOR]

The present preliminary study intends to evaluate the in vitro use of hydatid antigen and their antibodies once labeled with iodine 125(I 125 ) and characterized from viewpoint of radiochemical purity and immunoreactivity. Radiolabelled molecules gave satisfactory purity of 94% and 96%–98%, for hydatid antigen and IgG respectively. As regards, the specific activity of these latter, varied between 4.79 and 5.97 μCi/μg. The specificity test of radiolabelled IgG against the hydatid membranes showed a significant recognition that increased proportionally according to the contact surface. Likewise this immunoreactivity test performed with a simple binding assay, using human hydatid fluid antigen (HHF-Ag), previously fixed on a solid phase, gave satisfactory fixation rate of the order of 356 ± 48.08cpm, 2539 ± 550.12cpm and 6558 ± 712.76cpm for the concentrations of 0.1 μg/ml, 2 μg/ml and 25 μg/ml respectively. Statistical study of 88 sera, carried out with radiolabelled antigen ( 125 I-HHF-Ag) in competitive radioimmunoassay test (CRIA) showed highly significant difference (p < 0.0001) in the binding capacity of antigens from patients sera with hydatid disease (65.63 ± 9.12) compared to the negative sera (19.25 ± 14.84). No cross reaction was observed using sera from patients with toxoplasmosis (33, 07 ± 13, 07) and the difference was highly significant (p < 0.0001) compared to E granulosus infected patient sera. Furthermore, this test seemed to be sensitive since among the 43 sera tested, only 37 (86%) were found to be positive by passive hemagglutination (HAP), while the totality (100%) responded positively by CRIA. Our findings are encouraging, suggesting that these radiolabeled molecules could be useful for advancing toward new diagnostic and therapeutic modalities. [ABSTRACT FROM AUTHOR]

A magnetoresistive biosensor was demonstrated using an InSb-based semiconductor channel. The Fe 3 O 4 nanoparticle was linked with a target antigen via a capture antibody in the reagent, and a detection antibody immobilized on an InSb channel was shown to selectively bind to the antigen-capture antibody-nanoparticle complex. The detected magnetic nanoparticles produced a stray magnetic field that induced a change in the resistance of the channel due to the Lorentz force. The antigen concentration was proportional to the number of nanoparticles attached to the sensor surface, and hence could be determined by measuring the magnetoresistance level of the sensing channel. This antigen-antibody reaction sensor was shown to detect an extremely small amount of liver cancer antigen, at a concentration as low as 1 pg/ml. The systematic tests we carried out also confirmed the good selectivity and reusability of this biosensor. [ABSTRACT FROM AUTHOR]

Antibodies are useful for detecting glycoprotein antigens, but a conventional antibody recognizes only a protein epitope rather than a glycan. Thus, glycan isoform detection generally requires time- and labor-consuming processes such as lectin affinity column chromatography followed by sandwich ELISA. We recently found antigen-antibody reactions that were inhibited by lectin binding to glycans on the glycoprotein antigen, leading to a convenient glycoform-specific assay. Indeed, Sambucus sieboldiana agglutinin (SSA) lectin, a binder to sialylα2,6galactose residue, inhibited antibody binding to α2,6-sialylated transferrin (Tf) (SSA inhibition). SSA inhibition was not observed with other glycoforms, such as periodate-treated, sialidase-treated and sialidase/galactosidase-treated Tf, suggesting that the assay was glycoform-specific. SSA inhibition was also applicable for visualizing localization of α2,6-sialylated-Tf in a liver section. This is the first immunohistochemical demonstration of glycoform localization in a tissue section. SSA inhibition was utilized for establishing ELISA to quantify α2,6-sialylated carcinoembryonic antigen (CEA), a marker for various cancers. In addition, α2,6-sialylated-CEA was visualized in a colonic adenocarcinoma section by SSA inhibition. The method would further be applicable to a simple and rapid estimation of other α2,6-sialylated glycoproteins and have a potential aid to histopathological diagnosis.

CRISPR/Cas-based biosensors were typically used for nucleic-acid targets detection and complex DNA extraction and amplification procedures were usually inevitable. Here, we report a C RISPR/C a s12a-mediated, DNA ex t raction and amplifi c ation-free, h ighly dir e ct and rapid biosenso r (abbreviated as "CATCHER") for Salmonella Typhimurium (S. Typhimurium) with a simple (3 steps) and fast (∼2 h) sensing workflow. Magnetic nanoparticle immobilized anti- S. Typhimurium antibody was worked as capture probe to capture the target and provide movable reaction interface. Colloidal gold labeled with anti- S. Typhimurium antibody and DNase I was used as detection probe to bridge the input target and output signal. First, in the presence of S. Typhimurium, an immuno-sandwich structure was formed. Second, DNase I in sandwich structure degraded the valid, complete activator DNA to invalid DNA fragments which can't trigger the trans -cleavage activity of Cas12a. Finally, the integrity of reporter DNA was preserved presenting a low fluorescence signal. Conversely, in the absence of S. Typhimurium, strong fluorescence recovery appeared owing to the cutting of reporter by activated Cas12a. Significantly, the proposed "CATCHER" showed satisfactory detection performance for S. Typhimurium with the limit of detection (LOD) of 7.9 × 101 CFU/mL in 0.01 M PBS and 6.31 × 103 CFU/mL in spiked chicken samples, providing a general platform for non-nucleic acid targets. [ABSTRACT FROM AUTHOR]

Introduction: Interleukin-6 (IL-6) is a multifunctional polypeptide cytokine composed of two glycoprotein chains, which plays an important role in many cellular reactions, pathological processes, diagnosis and treatment of diseases and so on. The detection of IL-6 plays a promising role in the cognition of clinical diseases. Methods: 4-mercaptobenzoic acid (4-MBA) was immobilized on the gold nanoparticles modified platinum carbon (PC) electrode with the linker IL-6 antibody, and finally formed an electrochemical sensor that specifically recognized IL-6. Through the highly specific antigen-antibody reaction, the IL-6 concentration of the samples to be detected. The performance of the sensor was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Results: The experimental results showed that the linear detection range of the sensor for IL-6 was 100 pg/mL-700 pg/mL and the detection limit was 3 pg/mL. In addition, the sensor had the advantages of high specificity, high sensitivity, high stability and reproducibility under the interference environment of bovine serum albumin (BSA), glutathione (GSH), glycine (Gly) and neuron specific enolase (NSE), which provided a prospect for specific antigen detection sensor. Discussion: The prepared electrochemical sensor successfully detected the content of IL-6 in standard and biological samples, showing excellent detection performance. No significant difference was found between the detection results of the sensor and that of ELISA. The sensor showed a very broad prospect in the application and detection of clinical samples., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Wang, Xin, Yue, Wan, Li, Wang and Wu.)

Influenza A virus belongs to the most studied virus and its mutant initiates epidemic and pandemics outbreaks. Inoculation is the significant foundation to diminish the risk of infection. To prevent an incidence of influenza from the transmission, various practical approaches require more advancement and progress. More efforts and research must take in front to enhance vaccine efficacy. The present research emphasizes the development and expansion of a universal vaccine for the influenza virus. Research focuses on vaccine design with high efficacy. In this study, numerous computational approaches were used, covering a wide range of elements and ideas in bioinformatics methodology. Various B and T-cell epitopic peptides derived from the Neuraminidase protein N1 are recognized by these approaches. With the implementation of numerous obtained databases and bioinformatics tools, the different immune framework methods of the conserved sequences of N1 neuraminidase were analyzed. NCBI databases were employed to retrieve amino acid sequences. The antigenic nature of the neuraminidase sequence was achieved by the VaxiJen server and Kolaskar and Tongaonkar method. After screening of various B and T cell epitopes, one efficient peptide each from B cell epitope and T cell epitopes was assessed for their antigenic determinant vaccine efficacy. Identical two B cell epitopes were recognized from the N1 protein when analyzed using B-cell epitope prediction servers. The detailed examination of amino acid sequences for interpretation of B and T cell epitopes was achieved with the help of the ABCPred and Immune Epitope Database. Computational immunology via immunoinformatic study exhibited RPNDKTG as having its high conservancy efficiency and demonstrated as a good antigenic, accessible surface hydrophilic B-cell epitope. Among T cell epitope analysis, YVNISNTNF was selected for being a conserved epitope. T cell epitope was also analyzed for its allergenicity and cytotoxicity evaluation. YVNISNTNF epitope was found to be a non-allergen and not toxic for cells as well. This T-cell epitope with maximum world populace coverages was scrutinized for its association with the HLA-DRB1*0401 molecule. Results from docking simulation analyses showed YVNISNTNF having lower binding energy, the radius of gyration (Rg), RMSD values, and RMSE values which make the protein structure more stable and increase its ability to become an epitopic peptide for influenza virus vaccination. We propose that this epitope analysis may be successfully used as a measurement tool for the robustness of an antigen–antibody reaction between mutant strains in the annual design of the influenza vaccine. [ABSTRACT FROM AUTHOR]

• Modified recombinant AFTN nano-protein enabled selectively detecting salivary cortisol. • A developed electro-sensor detection cortisol level from real clinical sample. • The electro-sensor possessed a 0.95 and 1.19 ng/mL LOD in buffer and saliva samples. • R-AFTN nano-protein-based electro-sensor exhibited a 7.91 μA/(ng/mL) sensitivity. We have developed a powerful biosensing strategy for immobilizing histidine-tagged (His-Tag)-oriented recombinant nano-protein immobilization on a chemically modified glassy carbon electrode (GCE) surfaces via (S)- N -(5-amino-1-carboxypentyl)iminodiacetic acid (ANTA) acting as a chelating Ni2+ centered interaction. Here, we introduce a label-free electro-sensor to quantify cortisol levels in saliva samples for point-of-care testing (POCT). The high specificity of the chemically modified GCE was established by genetically bio-engineered metal-binding sites on the selected recombinant apoferritin (R-AFTN) nano-protein to impart functionality to its surface and by coating the carbon surface with the self-assembled monolayers of 4-aminobenzoic acid (4-ABA) attached to ANTA groups complexed with Ni2+ transition metal ions. Despite the variety of conventional assays available to monitor cortisol levels, they require bulky exterior outfits, which hinders use in the healthcare systems. Therefore, we performed a rapid, easy-to-implement, and low-cost quantitative electro-sensor to enable the real-time detection of cortisol levels in saliva samples. As a result, the cortisol electro-sensor fabricated with high specificity utilizing a GCE could measure cortisol levels with a detection limit of 0.95 ng/ml and sensitivity of 7.91 μA/(ng/mL), which is a practical approach in human saliva. Thus, protein nanoprobe-based cortisol biosensing showed high sensitivity and selectivity for the direct electro-sensing of cortisol for POCT. [ABSTRACT FROM AUTHOR]

The article discusses the potential of quartz crystal microbalance in detecting spinal ventral and dorsal roots. The study was done on 10 adult beagles aged 12 months old each, where they had their spinal canals revealed through median incisions during their surgeries to extract their ventral and dorsal roots. Results showed that the quartz crystal microbalance method can be used for searching for spinal nerve roots quickly during a surgery including the ulnar nerve and radial nerve.

Abstract: Viral vectors that genetically incorporate an immunoglobulin-binding domain on their surfaces provide many advantages because of the availability of a spectrum of antibodies that allow the selection of a wide range of target cells. However, the specificity and the effectiveness of this system have not been evaluated in the field of neuroscience. We investigated the effectiveness and specificity of a recombinant Sindbis virus displaying an antibody-binding domain of bacterial protein A (ZZ Sindbis). We found that the ZZ Sindbis virus vector specifically infected hippocampal neurons in an antibody-specific manner in living mice, although the efficiency of the gene transduction was not high. However, the ZZ Sindbis virus vector that did not display any specific antibodies continued to exhibit intrinsic tropism toward Bergmann glial cells in the cerebellum. These data indicate that the antibody-displaying viral vectors are potentially useful for delivering a gene of interest to a specific subset of neurons in the central nervous system with the help of neuron type-specific antibodies. [Copyright &y& Elsevier]

In this study, 77 and 155 MHz Love wave surface acoustic wave (SAW) biosensors were fabricated to detect antigen-antibody reactions in liquid environments. The single-interdigital transducer (IDT) on the quartz crystal substrate was found to be not suitable for Love wave SAW biosensor because of its signal distortion due to triple transit echo (TTE) between the IDT fingers. As a waveguide layer for the Love wave SAW biosensor, SU-8 photoresist was coated on a quartz crystal substrate with double-IDT patterns. Anti-mouse IgG was immobilized on the sensing area with a protein G layer bound to a gold surface. The minimum detectable concentrations of mouse IgG for 77 and 155 MHz Love wave SAW biosensors and a surface plasmon resonance (SPR) biosensor were found to be 2.5, 1, and 1 μg/mL, respectively. The fabricated Love wave SAW and SPR biosensors showed similar performances in detectable concentrations of mouse IgG and in coefficient of determination. [ABSTRACT FROM AUTHOR]

Abstract: Inhibitions of amphiphiles with a long chain (alcohols with carbon number of 10, 12, 14, 16 and the corresponding fatty acids) on the antigen–antibody reaction between fluorescent probe (fluorescein (FL)) and anti-fluorescent probe monoclonal antibody (immunoglobulin G (IgG)-49) were investigated by fluorescence spectroscopy. The resulting inhibition modes were compared with those of specific inhibitors, 5- and 6-aminofluoresceins (5- and 6-FLNH2). In the presence of all inhibitors, the fluorescence quenching of FL as the result of inhibitor binding to IgG-49 was hindered in an inhibitor concentration-dependent manner. The values of IC50 and Hill number for the inhibitors were determined from dose–response curves of the quenching inhibition. The IC50 values of the alcohols were much more dependent on the chain length than those of the fatty acids although all the values were in orders of μM. The Hill numbers of both kinds of inhibitors became larger values than 1, but they had different values for a series of alcohols and fatty acids, respectively. By contrast, the IC50 values of 5- and 6-FLNH2 were in orders of nM and the Hill numbers became smaller values than 1. Since the Lineweaver–Burk plots produced an intersection point on the intercept of the X-axis for the long-chain inhibitors with carbon number of 14 while did that on the intercept of the Y-axis for 6-FLNH2, respectively, we judged the inhibition modes of the former as non-competitive ones and those of the latter as a competitive one. Further, the effect of pressure on the inhibition by C14OH, C13COOH and 5-FLNH2 was examined, and the standard volume changes of IgG-49 for the inhibitor binding were calculated from the Johnson–Eyring plots. The volume change for 5-FLNH2 was smaller than those for C14OH and C13COOH although they became all negative. This suggests that the volume of IgG-49 shrinks by the addition of these inhibitors, and IgG-49 is not relevant to a model protein for the molecular mechanism of anesthesia. [Copyright &y& Elsevier]

Abstract: In this paper we describe the development of a shear horizontal surface acoustic wave immunosensor for medical diagnostics. There exists a strong interest in the rapid detection of antigen–antibody reactions at small concentrations in the g/ml region in plasma, serum, or whole blood. Sensors whose operating principle is based on shear horizontal acoustic surface waves are well suited for this. We have used a spin-on glass film for the guidance of the surface wave as well as for the protection of the aluminum structures of the surface wave transducers from aggressive analyte liquids. This film has proven to considerably enhance the sensitivity of the device, and to simultaneously provide a durable protection of the transducers. Furthermore, polymers based on polyvinylamines have been used for the first time for immobilization of the capture protein. This technique effectively prevents the undesired binding of foreign substances like cells, non-specific antibodies, or other proteins at the sensor surface. [Copyright &y& Elsevier]

Abstract: The electric characteristics at the surface of cells are changed depending on the surface conditions and reactions, and electrophoresis is one of the simplest methods of detecting the change in the electric characteristics of cells, and one which does not cause any damage to the sample cells. In this paper, we fabricate micro-channels, attach antibodies, that is, immunoglobulin G (IgG), to the surface of sheep''s red blood cells (RBCs) and carry out electrophoresis experiments of RBCs in the micro-channels to measure the electrophoretic mobility of each RBC. The amount of antigen-antibody reaction on the cell surface is also measured by the well-known enzyme-linked immunosorbent assay (ELISA) method. We find that there is a clear correlation between the electrophoretic mobility of the cells and the amount of IgG reaction on the surface of the cells, that is, the absolute value of the mobility of the cells decreases with an increase in the amount of IgG reaction on the cells. Therefore, the amount of surface reactions on each cell can be quickly detected by measuring the electrophoretic mobility of the cell, which is much simpler than labelling methods such as the ELISA or flow cytometric methods. The present result suggests that simultaneous detection of different diseases and health conditions may become possible by using multi-channel micro-fluidic electrophoresis devices. [Copyright &y& Elsevier]

Abstract: Aim: The present study was conducted to examine the thermal and non-thermal effects of ultrasound on apoptosis induced by anti-CD20 monoclonal antibody (rituximab). Materials and methods: SU-DHL-4 cells, a CD20-positive cell line derived from B cell lymphomas with a BCL2 gene rearrangement, were exposed to continuous 1MHz ultrasound for therapeutic use under an air- or CO2-saturated condition to control cavitation. Early apoptosis (EA) and secondary necrosis (SN) were examined by flow cytometry. Cavitation was determined by detecting the hydroxyl radicals derived from pyrolysis of water molecules using electron paramagnetic resonance-spin trapping. To assess thermal effects, cells were treated in a temperature-controlled water bath. Results: There was a significant additive increase in EA and EA+SN observed in cells treated with rituximab combined with heat at 42°C or non-thermal ultrasound at 0.5W/cm2 under an air-saturated condition, where heat or ultrasound induced some cell death. A significant synergistic increase in EA and EA+SN was observed in cells treated with rituximab and ultrasound at 2.5W/cm2 under CO2-saturated conditions, where inertial cavitations were completely suppressed. No enhancement was observed at a temperature less than 40°C or ultrasound at 0.5W/cm2 under CO2-saturated conditions. Conclusion: These results suggest that the immuno-therapeutic application of ultrasound at relatively high-intensities combined with rituximab thus produces synergistic effects under conditions where the non-thermal and non-cavitational effects are predominant. [Copyright &y& Elsevier]

Abstract: This paper describes a selective detection method for specific bacteria by using a dielectrophoretic impedance measurement method in conjunction with an antigen–antibody reaction. The authors have previously demonstrated a bacteria detection technique called DEPIM (dielectrophoretic impedance measurement) and EPA-DEPIM (electropermeabilization-assisted DEPIM) using a positive dielectrophoretic force to capture bacteria in suspension onto an interdigitated electrode chip. It has also been demonstrated that a selective DEPIM detection of specific bacteria could be realized by taking advantage of agglutination phenomena, which were caused by an antigen–antibody reaction. In the present study, other combinations of the antigen–antibody reaction with DEPIM or EPA-DEPIM were demonstrated. Antibody molecules were immobilized on the electrode chip before the preliminary bacteria trapping by positive dielectrophoresis (DEP). The bacteria were attracted to the electrode gap under the action of the positive DEP force and finally brought into contact with the glass surface to be bound with the immobilized antibody. By appropriately adjusting the balance between the DEP force and the drag force caused by liquid flow, the target bacteria (Escherichia coli) could be selectively retained on the chip surface avoiding undesired non-specific binding. The retained bacteria were electrically detected by EPA-DEPIM. It was also confirmed that the proposed method realized selective detection of the target bacteria from a mixed suspension with nontarget bacteria. [Copyright &y& Elsevier]

Over the last decade, surface plasmon resonance (SPR) becomes one of the major methods for the detection and investigation of affinity-based interactions in biochemistry, bioanalytical chemistry and biomedicine. The tremendous development of SPR use in biomedical applications during the last years is the reason why attention in this review is focused on the application of SPR for biomedical purposes. Biomedical applications take advantage of the exquisite sensitivity of SPR for the determination of DNA hybridization, diagnosis of virus-induced diseases, enzyme-substrate interactions, polyclonal antibody characterization, epitope mapping, protein conformation studies and label-free immunoassays. This review covers also some aspects of the evolution of surface plasmon resonance biosensors. The general principles of SPR sensor action are presented and major SPR formats are described. SPR biosensor employment for detection of various analytes ranging from small organics up to large protein complexes is reviewed. Immobilization methods used in the design of SPR biosensors are briefly described. Application of SPR for analysis of protein kinases as a major component in signal generation and transduction in eukaryotic cell is discussed. New ways of SPR application and new designs of hybrid SPR sensors are predicted and discussed. It is concluded that improvement of detection limits, multichannel performance, development of advanced recognition elements are the major tasks in developing new SPR sensors. [ABSTRACT FROM AUTHOR]

We investigated a new method to destruct targeted cells using magnetizable beads and pulsed magnetic force. The cells were combined with the beads by an antigen-antibody reaction (cell/bead/antibody complex), aggregated by a magnet, and stimulated by a magnetic stimulator. The viability of the aggregated and stimulated cell/bead/antibody complexes was significantly decreased, and the cells were destructed by the penetration of the beads into the cells or rupturing of the cells by the beads. These results suggest that magnetic aggregation and pulsed magnetic stimulation can effectively damage only the cells targeted by an antigen-antibody reaction. [ABSTRACT FROM PUBLISHER]

This paper describes a new selective detection method for specific bacteria by using a dielectrophoretic impedance measurement method combined with an antigen–antibody reaction. The authors have previously proposed a bacteria detection technique called dielectrophoretic impedance measurement (DEPIM) using positive dielectrophoretic force to capture bacteria in suspension onto an interdigitated microelectrode array. In this paper, the authors propose a selective bacteria detection method using DEPIM combined with an antigen–antibody reaction. A suspension containing Escherichia coli (E. coli) and Serratia marcescens (Serratia) was tested as a sample specimen. Those two bacteria were captured onto a microelectrode by positive dielectrophoresis in almost equal amounts. Agglutination of target bacteria caused by an antigen–antibody reaction was combined with conventional DEPIM in two different ways. As a result of agglutination, target bacteria became larger than nontarget ones and could experience higher dielectrophoretic force. In one method, E. coli and Serratia were trapped together under positive dielectrophoresis and then agglutinated E. coli was selectively left in the electrode gap by washing process. In the other method, agglutination products, which had been produced in advance, were selectively trapped and detected by DEPIM. It was experimentally confirmed that proposed two methods could selectively detect E. coli from the mix suspension as long as E. coli population was more than that of Serratia. [Copyright &y& Elsevier]

A sequential injection analysis (SIA) technique, in which antibody-immobilized microbeads were transferred to a jet ring (JR) cell, was used in determination of carp vitellogenin (Vg). The determination is based on a sandwich immunoassay in which two types of reactions between anti carp Vg antibodies and carp Vg are used. Namely, the antibody for the first reaction step was immobilized on microbeads (Sephadex beads), and an antibody labeled with a horseradish peroxidase (HRP) was used in the second step of the reaction. A mixed solution of hydrogen peroxide and o-phenylenediamine (OPD) was used as the source of the chromophore in the reaction. The microbeads-immobilized antibody, Vg analyte, HRP-labeled anitbody and the color developing solution were introduced automatically into the JR cell of the SIA system in a programmed sequence, and the absorbance of the oxidized OPD product was used to determine the amount of Vg present. The optimal incubation times for the immuno-raction for the first and the second steps were determined at 120 and 60 min, respectively, taking into account the sensitivity to the Vg determination. Under these conditions, a good linear correlation was obtained between Vg concentration and the absorbance of the oxidized OPD. The lower detection limit for the determination of Vg was about 5 ng ml−1 in this system. The method developed here represents a simple, accurate method for the determination method of Vg. [Copyright &y& Elsevier]

Unilamellar liposomes with incorporated hapten–phospholipid conjugates were proposed as models of polyvalent antigens with migrating determinants for quantitative analysis of their interaction with antibodies. The monovalent pesticide atrazine was used as a model antigen. For its incorporation into the lipid bilayer, the atrazine carboxylated derivative was conjugated with dimyristoylphosphatidylethanolamine (DMPE). Unilamellar liposomes were prepared with dimyristoylphosphatidylcholine/atrazine–DMPE at molar ratios of 90:10, 95:5, 98:2, 99:1 and 99.5:0.5. Their interaction with the peroxidase-labeled anti-atrazine antibodies was studied by enzyme immunoassay and polarization fluoroimmunoassay techniques.It was shown that the increase in hapten content in the liposomes from 0.5 to 10 mol% led to an increase in the equilibrium constants of the interaction with antibodies from 0.093×108 to 0.303×108 M−1. The association rate constants varied from 1.45×105 to 15.5×105 M−1 s−1 depending on the antigen content in liposomes and experimental conditions. The measured constants were applied for a mathematical model describing multi-step interaction between antibodies and polyvalent liposomal antigens. The model adequately describes the quantitative regularities of the influence of antigen content and the affinity of immunochemical interaction on the quantity and the dynamics of the immune complexes forming. [Copyright &y& Elsevier]

The histological reactions to the implantation of allogenetic and xenogenetic lyophilized and γ-sterilized material into the middle ear of rabbits and men is described. In contrary to the behaviour of allogenetic material the xenogenetic shows a clear minor tendency of revitalisation. The reason is the antigen-antibody-reaction which takes place at the capillary network of the donor and leads to a hylinosis with following obliteration of the vascular rete. Therefore the angiogenetic osteogenesis cannot develop. The clinical usuability of such material is discussed. [ABSTRACT FROM AUTHOR]

The availability of electrophoretically homogeneous rabbit penicillin carrier receptor protein (CRP) by affinity chromatography afforded an ideal in vitro system to calculate the thermodynamic parameters of binding of penicillin and analogues with CRP as well as competitive binding of such analogues with CRP in presence ofC-penicillin G. The kinetics of association of CRP with 7-deoxy penicillin which does not bind covalently with CRP have been studied through equilibrium dialysis withC-7-deoxybenzyl penicillin and found to be K=2·79×10M.−ΔG=8·106 k cal/mole as well as fluorescence quenching studies with exciter λ 280 K=3·573×10M,−ΔG=8·239 k cal/mole. The fluorescence quenching studies have been extended to CRP-benzyl penicillin and CRP-6-aminopenicillanic acid (6APA) systems also. The fluorescence data with benzyl penicillin indicate two conformational changes in CRP-a fast change corresponding to the non-covalent binding to CRP with 7-deoxy penicillin and a slower change due to covalent bond formation. With 6-APA the first change is not observed but the conformational change corresponding to covalent binding is only seen. Competitive binding studies indicate that the order of binding of CRP with the analogues of penicillin is as follows: methicillin > 6APA > carbenicillin > o-nitrobenzyl penicillin > cloxacillin ≈ benzyl penicillin ≈ 6-phenyl acetamido penicillanyl alcohol ≈ 7 phenyl acetamido desacetoxy cephalosporanic acid ≈ p-amino benzyl penicillin ≈ p-nitro benzyl penicillin > ticarcillin > o-amino benzyl penicillin > amoxycillin > 7-deoxy benzyl penicillin > ampicillin. From these data it has been possible to delineate partially the topology of the penicillin binding cleft of the CRP as well as some of the functional groups in the cleft responsible for the binding process. [ABSTRACT FROM AUTHOR]

La reacción hemolítica inmediata inmunológica representa la principal causa de muerte por transfusión. La reacción antígeno-anticuerpo con la subsiguiente hemólisis de los eritrocitos, desencadena un síndrome de respuesta inflamatoria sistémica como consecuencia de la liberación de citocinas (factor de necrosis tumoral a, interleucina 1, interleucina 8, interleucina 6) y activación de sistemas enzimáticos de amplificación (coagulación, fibrinólisis, calicreína-bradicinina). La coagulación intravascular diseminada y el fallo renal agudo son los eventos fisiopatológicos que dominan el cuadro. Se han desarrollado protocolos pre-transfusionales que ofrecen múltiples peldaños de seguridad, cuyo cumplimiento descarta la ocurrencia de reacciones fatales. Sin embargo, aún están presentes y se señalan como sus causas fundamentales los errores de identificación, la falta de conocimiento y la negligenciaThe immediate immunological hemolytic reaction is the main cause of death associated with transfusion. The antigen-antibody reaction with the subsequent .hemolysis of erythrocytes triggers a systemic inflammatory response syndrome resulting from the release of cytokines (tumoral a necrosis factor, interleukin 1, interleukin 8, interleukin 6) and from the activation of enzymatic amplification systems (coagulation, fibrinolysis, calicrein-bradykinin). The disseminated intravascular coagulation and the acute renal failure are physiopathological events that stand out in the clinical picture. Pretransfusional protocols that provide multiple safety steps, and whose fulfiment discards the occurrence of fatal reactions, have been developed. However, the idenfication erros, the lack of knowledge and negligence are still present and are considered as its fundamental causes

Aim: We investigated the frequency of overall biphasic reactions, biphasic reactions that met the diagnostic criteria of anaphylaxis, and biphasic reactions that caused a severe abnormality in vital signs in patients who visited the emergency department of a tertiary hospital., Methods: This retrospective cohort study included patients aged 18 years or over who presented with anaphylaxis at the emergency department of a tertiary care hospital between January 2014 and December 2016. The primary outcome was the incidence of biphasic reactions that caused a severe abnormality in vital signs and developed within 7 days. Secondary outcomes were the frequency of overall biphasic reactions and those that met the diagnostic criteria of anaphylaxis., Results: In total, 437 patients aged over 18 years visited the emergency department during the study period. Among them, 202 were enrolled in this study. The proportion of patients who had overall biphasic reactions, those that met the diagnostic criteria of anaphylaxis, and those with a severe abnormality in vital signs was 8.9%, 3.0%, and 1.0%, respectively. Overall, 32.7% of patients were hospitalized, but hospitalization aided in the treatment of severe biphasic reactions at the early stage in only one patient., Conclusion: We found that 8.9% of adult patients with anaphylaxis had a biphasic reaction, but biphasic reactions together with severe abnormalities in vital signs were rare., Competing Interests: Approval of the research protocol: This research was approved by the institutional review board of Kurashiki Central Hospital (approval no. 2979), and it conforms to the provisions of the Declaration of Helsinki. Informed consent: The need for informed consent was waived because of the retrospective design of the study. Registry and the registration no. of the study/trial: N/A. Animal studies: N/A. Conflict of interest: None., (© 2021 The Authors. Acute Medicine & Surgery published by John Wiley & Sons Australia, Ltd on behalf of Japanese Association for Acute Medicine.)

Glycoforms are otherwise identical proteins with different glycosylation. A lectin, Sambucus sieboldiana agglutinin (SSA), specifically binds glycoforms having α2,6-sialyl residues. The binding is found to inhibit antigen-antibody reaction; e.g., SSA inhibits anti-transferrin antibody binding to α2,6-sialylated transferrin (Tf) (SSA inhibition). SSA inhibition is not observed with other Tf glycoforms, indicating that the inhibition is glycoform-specific. Here we describe the application of SSA inhibition to ELISA as a specific assay for quantifying α2,6-sialylated Tf.

Antibodies are useful for localizing glycoprotein antigens in histochemistry, but they do not differentiate glycoforms in tissue sections because conventional antibodies recognize only protein epitopes rather than glycans. Glycan epitopes are recognized by lectins, which are found, occasionally, to inhibit antigen-antibody reaction in a glycoform-specific manner (lectin inhibition). Here we describe the application of lectin inhibition to immunohistochemistry for visualizing a glycoform in a tissue section.

Immunohistochemistry (IHC) is an integral laboratory staining technique, which is used for the detection of immune cells in mouse/human tissues or tumors. Oncolytic herpes simplex virus (oHSV) treatment or virotherapy of solid tumors results in antitumor immune responses and infiltration of a variety of immune cells into the tumor. Here, we describe a step-by-step chromogen/substrate-based single- and dual-color IHC protocol to stain immune cells in formalin-fixed, paraffin-embedded mouse glioblastoma (GBM) brain tumor sections after oHSV virotherapy. Tumor sections are deparaffinized with xylene, then gradually rehydrated using ethanol, followed by heat-mediated antigen retrieval using appropriate buffers. Tumor sections are incubated with primary antibodies, which detect a specific immune cell antigen, then incubated with peroxidase- or phosphatase-labeled secondary antibodies, followed by incubation with a color-producing substrate and color visualization (of immune cells) by light microscopy. The protocol described herein is also applicable to detect immune cells in other mouse and human tumors or organs after other forms of immunotherapy.

• Protein localization areas in a neuron were observed with SEM. • Proteins were immunologically stained with gold nanoparticles and visualized. • Protein localization areas in SEM images agree well with those found in optical images. • Protein localization areas would not be modified after sample preparation. The localization areas of intracellular proteins in rat cortical neurons were visualized using a scanning electron microscope (SEM) coupled with a focused ion beam (FIB) system. To obtain a clear contrast in the SEM images, gold nanoparticles (GNPs) were bound to specific intracellular proteins by antigen-antibody reactions. By obtaining a cross section of the desired location of the neurons by FIB milling under the SEM imaging condition, it was possible to observe the proteins inside the cells as clear bright spots. When a neuron was stained with anti-tau and anti-histone H1 antibodies, the bright spots were localized in the cross section of the axon and the nucleus, respectively. It was confirmed that targeted proteins in a single neuron on a substrate could be successfully identified. The development of FIB/SEM observation with immunological GNP staining will offer important information for the stable growth of neurons on various substrate structures, since the elongation and turning of axons on the substrates are activated by the redistribution of intracellular proteins. [ABSTRACT FROM AUTHOR]

Antibodies are useful for detecting glycoprotein antigens, but a conventional antibody recognizes only a protein epitope rather than a glycan. Thus, glycan isoform detection generally requires time- and labor-consuming processes such as lectin affinity column chromatography followed by sandwich ELISA. We recently found antigen-antibody reactions that were inhibited by lectin binding to glycans on the glycoprotein antigen, leading to a convenient glycoform-specific assay. Indeed, Sambucus sieboldiana agglutinin (SSA) lectin, a binder to sialylα2,6galactose residue, inhibited antibody binding to α2,6-sialylated transferrin (Tf) (SSA inhibition). SSA inhibition was not observed with other glycoforms, such as periodate-treated, sialidase-treated and sialidase/galactosidase-treated Tf, suggesting that the assay was glycoform-specific. SSA inhibition was also applicable for visualizing localization of α2,6-sialylated-Tf in a liver section. This is the first immunohistochemical demonstration of glycoform localization in a tissue section. SSA inhibition was utilized for establishing ELISA to quantify α2,6-sialylated carcinoembryonic antigen (CEA), a marker for various cancers. In addition, α2,6-sialylated-CEA was visualized in a colonic adenocarcinoma section by SSA inhibition. The method would further be applicable to a simple and rapid estimation of other α2,6-sialylated glycoproteins and have a potential aid to histopathological diagnosis. [ABSTRACT FROM AUTHOR]