Relevant bibliographies by topics / Antibody avidity

Academic literature on the topic 'Antibody avidity'

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Published: 4 June 2021
Last updated: 1 February 2022

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Journal articles on the topic "Antibody avidity"

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Arifa, Julian Eva, Budiman Bela, Silvia Tri Widyaningtyas, and Jeanne Elvia Christian. "Penggunaan antigen p24, IDR-Gp41 dan ID2-Pol dalam uji aviditas untuk identifikasi kasus baru pada infeksi HIV-1." Jurnal Biotek Medisiana Indonesia 8, no. 1 (December 18, 2019): 1–8. http://dx.doi.org/10.22435/jbmi.v8i1.2578.

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AIDS is a severe immunodeficiency disease caused by HIV. Identification of new HIV infection in a population is required for the evaluation of intervention strategy of HIV-1 transmission. The avidity assay has been promoted for HIV-1 detection. Avidity assay is based on affinity strength of the epitopes of the HIV antigen against its specific corresponding antibodies. The binding of the antigen - the antibody formed in the initial phase of infection is relatively weak and easy to break with chaotropic reagents. In contrary, the antigen-antibody binding formation in long-term infection is strong and not easily broken by addition of chaotropic reagents. Commercial avidity assays are available, however the antigens used might not be compatible with the circulating HIV strains in Indonesia. AbstractThis research aimed to identify the most appropriate antigen candidate for avidity assay, three structural proteins from HIV were used i.e., p24, IDR-gp41 and ID2-Pol employed from the HIV strains circulating in Indonesia. The avidity assay was performed based on ELISA with pH 3 sodium citrate as chaotropic reagent. Serum samples was previously determined as positive and negative reactive by the Indonesian Red Cross. Each sample was tested in triplicates. The results of the avidity index were compared with the corresponding pattern of reactivity shown by Western Blotting. Comparative analysis of the avidity index using the IDR-Gp41 antigen showed correlation with increased value of avidity index with the completeness of the Western Blot reactivity pattern. This finding is not true in antigen ID2-Pol, and p24. Based on the results of the study, it can be concluded that IDR-Gp41 antigen has potential to be used in HIV avidity assay that is based on circulating strains of HIV in Indonesia. AbstrakAIDS merupakan penyakit imunodefisiensi berat yang disebabkan oleh HIV. Penentuan infeksi baru HIV-1 pada level populasi diperlukan guna evaluasi strategi intervensi pencegahan penularan HIV-1. Uji aviditas telah diajukan sebagai salah satu uji deteksi HIV-1. Prinsip uji aviditas adalah kekuatan afinitas epitope antigen HIV terhadap antibodi spesifik yang mengenali epitop tersebut. Ikatan antigen-antibodi yang terbentuk pada fase awal infeksi merupakan ikatan yang lemah dan mudah diputuskan dengan pemberian reagensia chaotropic. Pada fase infeksi lama, ikatan antigen-antibodi yang terbentuk merupakan ikatan yang kuat sehingga tidak mudah diputuskan oleh pemberian reagensia chaotropic. Uji aviditas komersial telah tersedia namun antigen yang digunakan belum tentu sesuai dengan galur HIV yang beredar di Indonesia. Pada penelitian ini digunakan 3 kandidat antigen yaitu p24, IDR-gp41 dan ID2-Pol dari galur HIV yang beredar di Indonesia, untuk menentukan kandidat yang sesuai. Uji aviditas dilakukan dengan prinsip ELISA dengan sodium sitrat pH 3 sebagai reagensia chaotropic. Sampel yang diujikan adalah sampel serum yang telah ditentukan reaktivitasnya sebagai positif dan negatif oleh Palang Merah Indonesia. Sampel diuji secara triplikat. Hasil indeks aviditas sampel dibandingkan dengan pola reaktivitasnya pada uji Western Blot. Analisis perbandingan menunjukkan bahwa peningkatan nilai indeks aviditas yang menggunakan antigen IDR-Gp41 berkorelasi dengan kelengkapan pola reaktivitas uji Western Blot. Hal ini tidak ditemukan pada pengujian menggunakan antigen IDR-Pol2, dan p24. Berdasarkan hasil penelitian, dapat disimpulkan bahwa antigen IDR-Gp41 berpotensi untuk digunakan lebih lanjut dalam pengembangan uji aviditas HIV berbasis galur HIV yang beredar di Indonesia.
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Racine-Brzostek, Sabrina E., Mohsen Karbaschi, Christian Gaebler, P. J. Klasse, Jim Yee, Marina Caskey, He S. Yang, et al. "TOP-Plus Is a Versatile Biosensor Platform for Monitoring SARS-CoV-2 Antibody Durability." Clinical Chemistry 67, no. 9 (April 29, 2021): 1249–58. http://dx.doi.org/10.1093/clinchem/hvab069.

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Abstract Background Low initial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody titers dropping to undetectable levels within months after infection have raised concerns about long-term immunity. Both the antibody levels and the avidity of the antibody–antigen interaction should be examined to understand the quality of the antibody response. Methods A testing-on-a-probe “plus” panel (TOP-Plus) was developed to include a newly developed avidity assay built into the previously described SARS-CoV-2 TOP assays that measured total antibody (TAb), surrogate neutralizing antibody (SNAb), IgM, and IgG on a versatile biosensor platform. TAb and SNAb levels were compared with avidity in previously infected individuals at 1.3 and 6.2 months after infection in paired samples from 80 patients with coronavirus disease 2019 (COVID-19). Sera from individuals vaccinated for SARS-CoV-2 were also evaluated for antibody avidity. Results The newly designed avidity assay in this TOP panel correlated well with a reference Bio-Layer Interferometry avidity assay (r = 0.88). The imprecision of the TOP avidity assay was <10%. Although TAb and neutralization activity (by SNAb) decreased between 1.3 and 6.2 months after infection, the antibody avidity increased significantly (P < 0.0001). Antibody avidity in 10 SARS-CoV-2 vaccinated individuals (median: 28 days after vaccination) was comparable to the measured antibody avidity in infected individuals (median: 26 days after infection). Conclusions This highly precise and versatile TOP-Plus panel with the ability to measure SARS-CoV-2 TAb, SNAb, IgG, and IgM antibody levels and avidity of individual sera on one sensor can become a valuable asset in monitoring not only patients infected with SARS-CoV-2 but also the status of individuals’ COVID-19 vaccination response.
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Pereira Arias-Bouda, Lenka M., Sjoukje Kuijper, Anouk Van Der Werf, Lan N. Nguyen, Henk M. Jansen, and Arend H. J. Kolk. "Changes in Avidity and Level of Immunoglobulin G Antibodies to Mycobacterium tuberculosis in Sera of Patients Undergoing Treatment for Pulmonary Tuberculosis." Clinical Diagnostic Laboratory Immunology 10, no. 4 (July 2003): 702–9. http://dx.doi.org/10.1128/cdli.10.4.702-709.2003.

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ABSTRACT Much is known about specific antibodies and their titers in patients with tuberculosis. However, little is known about the avidity of these antibodies or whether changes in avidity occur during the progression of the disease or during treatment. The aims of this study were to determine the avidity of antibodies to Mycobacterium tuberculosis in patients with pulmonary tuberculosis, to explore the value of avidity determination for the diagnosis of tuberculosis, and to study changes in levels of antibodies and their avidity during treatment. Antibody avidity was measured by an enzyme-linked immunosorbent assay with thiocyanate elution. Avidity indices and serum levels of immunoglobulin G to M. tuberculosis were determined for 22 patients with pulmonary tuberculosis before and during treatment and for 24 patients with other pulmonary diseases. Antibody levels and avidity were both significantly higher in untreated tuberculosis patients than in the controls. Avidity determination had more diagnostic potential than determination of the antibody levels. Tuberculosis patients with a long duration of symptoms had higher antibody avidity than those with a recent onset of symptoms, indicating affinity maturation of specific antibodies during active disease. In the early phase of treatment, a decrease in antibody avidity was observed for 73% of all tuberculosis patients, accompanied by an initial increase in antibody levels in 36% of these patients. These phenomena could be explained by an intense stimulation of the humoral response by antigens released from killed bacteria, reflecting early bactericidal activity of antituberculous drugs leading to the production of low-affinity antibodies against these released antigens.
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Intner, Sara, Michelle Altrich, and Niraj Patel. "Comparison of Pneumococcal Avidity and Antibody Concentration in Children with Recurrent Infections: A Retrospective Pilot Study." Journal of Immunological Sciences 4, no. 4 (October 10, 2020): 24–30. http://dx.doi.org/10.29245/2578-3009/2020/4.1194.

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Measurement of pneumococcal antibody concentration is a frequently used parameter for functional antibody response to vaccination. Antibody concentration in response to vaccination and strength of antigen-antibody (avidity) interaction are both important measurements of functional antibody response. Both antibody concentration and avidity contribute to immunity against invasive pneumococcal disease. Higher avidity is correlated with increasing bactericidal activity and opsonophagocytosis. On the other hand, patients with lower pneumococcal avidity may be more likely to develop clinically significant pneumococcal sinopulmonary infections. Nine patients with recurrent bacterial respiratory infections were identified by retrospective chart review as having adequate pneumococcal antibody concentrations, but with low avidity for multiple serotypes following immunization with pneumococcal vaccine polyvalent (PPSV23). We assessed response with IgG replacement therapy in these patients. The mean number of serotypes with a normal antibody response (>1.3 mg/ml) among 9 children following immunization with pneumococcal vaccine polyvalent was 19.1 (range 12-22) of 23 serotypes while the mean number of serotypes with a normal avidity response (≥1.0) was 4.7 (range 2-7) of 23 serotypes. Flow cytometry was performed for 8 of the 9 patients prior to starting SCIG replacement therapy. 100% of the cohort experienced a significant decrease in yearly infection rate after starting immunoglobulin replacement. This is the first study to assess the clinical response to immune globulin replacement in patients with normal pneumococcal antibody response but poor pneumococcal avidity, and suggests that patients with poor pneumococcal avidity but apparent normal response by pneumococcal antibody following PPSV23 may benefit from IgG replacement therapy.
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Tiburcio, Monique Gomes Salles, Laís Anversa, Kelly Aparecida Kanunfre, Antonio Walter Ferreira, Virmondes Rodrigues Júnior, and Luciana de Almeida Silva. "Anti-Leishmania infantum IgG Antibody Avidity in Visceral Leishmaniasis." Clinical and Vaccine Immunology 20, no. 11 (September 4, 2013): 1697–702. http://dx.doi.org/10.1128/cvi.00367-13.

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ABSTRACTIgG avidity tests are used to discriminate acute from chronic infections. There are few reports on the IgG avidity profile of patients with visceral leishmaniasis (VL). This study investigated the anti-LeishmaniaIgG avidity in patients with classic VL (n= 10), patients showing clinical cure after treatment (n= 18), and asymptomatic subjects with at least one positiveLeishmaniatest (n= 20). All subjects were from areas in Brazil where VL is endemic. Serum samples were collected from each subject on two different occasions. IgG avidity was evaluated by Western blotting. The proportion of high-avidity antibodies was higher in all samples from patients with classic VL. In contrast, low-avidity antibodies predominated in subjects with a history of VL, including 13 cases (72.2%) in the first assessment and 14 (77.8%) in the second. Fifteen (75%) of the asymptomatic subjects presented a predominance of low-avidity antibodies in the first assessment, and the frequency of high-avidity antibodies increased over time in seven subjects (35%) of this group. Antibodies against the 14- and/or 16-kDa antigen fraction were detected in the first assessment in all patients with classic VL, in 10 (55.5%) treated patients, and in 10 (50%) asymptomatic subjects. These were high-avidity antibodies in most cases. In the asymptomatic group, an increase in IgG avidity against the 14- and/or 16-kDa antigen fraction was observed in three cases (15%). The results indicate distinct responses in infected and asymptomatic subjects, probably associated with the length of time after infection. In this respect, IgG avidity tests represent a new approach to better characterize asymptomatic VL.
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Marcipar, Iván S., Marikena G. Risso, Ariel M. Silber, Silvia Revelli, and Alberto J. Marcipar. "Antibody Maturation in Trypanosoma cruzi-Infected Rats." Clinical Diagnostic Laboratory Immunology 8, no. 4 (July 1, 2001): 802–5. http://dx.doi.org/10.1128/cdli.8.4.802-805.2001.

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ABSTRACT The study of antibody avidity changes during infection has improved the understanding of the pathologic processes involved in several infectious diseases. In some infections, like toxoplasmosis, this information is being used for diagnostic purposes. Results of the evolution of antibody avidity for different specific antigens inTrypanosome cruzi-infected rats are presented. A Western blotting technique, combined with avidity analysis to identify antigens that elicit high-avidity antibodies, is suggested. In this system, antibodies showed high avidity values only during the chronic phase of infection and only in relation to antibodies against 21-, 33-, 41-, 42-, 56-, 58-, 66-, and 72-kDa antigens. Finally, a 97-kDa T. cruzi antigen, which was recognized by high-avidity antibodies and occurred in noninfected rats, was identified. These results allow us to evaluate the different antigens in chagasic infection. Our results show that with the correct choice of antigen it is possible to detect differences in maturation of antibodies and to discriminate, in an experimental model, between recent (acute) and chronic infections.
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Alex, Diviya, Tennison Inba Raj Williams, Jaiprasath Sachithanandham, Swaminathan Prasannakumar, John Paul Demosthenes, Veena Vadhini Ramalingam, Punitha John Victor, Priscilla Rupali, Gnanadurai John Fletcher, and Rajesh Kannangai. "Performance of a Modified In-House HIV-1 Avidity Assay among a Cohort of Newly Diagnosed HIV-1 Infected Individuals and the Effect of ART on the Maturation of HIV-1 Specific Antibodies." Current HIV Research 17, no. 2 (September 2, 2019): 134–45. http://dx.doi.org/10.2174/1570162x17666190712125606.

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Background: Viral kinetics impact humoral immune response to HIV; antibody avidity testing helps distinguish recent (<6 months) and long-term HIV infection. This study aims to determine the frequency of recent HIV-1 infection among clients attending ICTC (Integrated Counselling and Testing Centre) using a commercial EIA, to correlate it with a modified in-house avidity assay and to study the impact of ART on anti-HIV-1 antibody maturation. Method: Commercial LAg Avidity EIA was used to detect antibody avidity among 117 treatment naïve HIV-1 infected individuals. A second-generation HIV ELISA was modified for in-house antibody avidity testing and cutoff was set based on Receiver Operating Characteristic (ROC) analysis. Archived paired samples from 25 HIV-1 infected individuals before ART and after successful ART; samples from 7 individuals responding to ART and during virological failure were also tested by LAg Avidity EIA. Results: Six individuals (5.1%) were identified as recently infected by a combination of LAg avidity assay and HIV-1 viral load testing. The modified in-house avidity assay demonstrated sensitivity and specificity of 100% and 98.2%, respectively, at AI=0.69 by ROC analysis. Median ODn values of individuals when responding to ART were significantly lower than pre-ART [4.136 (IQR 3.437– 4.827) vs 4.455 (IQR 3.748–5.120), p=0.006] whereas ODn values were higher during virological failure [4.260 (IQR 3.665 – 4.515) vs 2.868 (IQR 2.247 – 3.921), p=0.16]. Conclusion: This modified in-house antibody avidity assay is an inexpensive method to detect recent HIV-1 infection. ART demonstrated significant effect on HIV-1 antibody avidity owing to changes in viral kinetics.
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Yoshida, Márcia, Maria Carmen Arroyo Sanchez, and Maria Aparecida Shikanai-Yasuda. "Increased Immunoglobulin G Anti-Paracoccidioides brasiliensis Serum Antibody Avidity as a Predictor of Favorable Posttherapeutic Evolution in Paracoccidioidomycosis." Clinical and Vaccine Immunology 16, no. 11 (September 2, 2009): 1583–86. http://dx.doi.org/10.1128/cvi.00265-09.

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ABSTRACT Paracoccidioidomycosis is endemic in Latin America, and ca. 80% of all cases occur in Brazil. Little is known about antibody avidity or the evolution of such avidity in the posttherapeutic period for the different clinical presentations of the disease. In the present study, we evaluated 53 patients with paracoccidioidomycosis and calculated the avidity index. Medium- and high-avidity antibodies were found in 79.5% of patients with chronic presentation (n = 39). Among patients with the acute form (n = 14), 57.1% of the antibodies presented low avidity. In the posttherapeutic period, there was a significant increase in antibody avidity in patients presenting with the chronic multifocal form. In our preliminary study, which needs to be confirmed using a larger number of samples, the optimized method for studying antibody avidity detected differences among the clinical presentations of the mycosis and indicated the value of the avidity index as a marker of posttherapeutic evolution of patients with a multifocal chronic form of the disease.
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Chan, K. H., K. Sonnenberg, M. Niedrig, S. Y. Lam, C. M. Pang, K. M. Chan, S. K. Ma, W. H. Seto, and J. S. M. Peiris. "Use of Antibody Avidity Assays for Diagnosis of Severe Acute Respiratory Syndrome Coronavirus Infection." Clinical and Vaccine Immunology 14, no. 11 (September 19, 2007): 1433–36. http://dx.doi.org/10.1128/cvi.00056-07.

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ABSTRACT An indirect immunofluorescent assay (Euroimmun AG, Luebeck, Germany) was used to investigate the avidity of immunoglobulin G (IgG), IgM, IgA, and total Ig (IgGAM) antibody responses to severe acute respiratory syndrome coronavirus (SARS CoV) infections. Serial serum samples from eight patients collected during the first, third, and ninth months after the onset of infection were evaluated. It was found that low-avidity IgG antibodies were detected in 15/15 (100%), 1/5 (20%), and 0/8 (0%) serum samples collected during the first, third, and ninth months after the onset of symptoms, respectively. Low-avidity antibodies of IgA and IgM subclasses were detected in 14/14 (100%) and 3/14 (21%) serum samples, respectively, collected in the first month after the onset of infection. However, IgA antibodies remained low in avidity in a proportion of patients even during late convalescence. As a consequence, IgG antibody avidity assays gave better discrimination between acute-phase and late-convalescent-phase serum samples than IgM, IgA, or IgGAM assays. In two of these patients, sequential serum samples were also tested for IgG avidity against human CoV strains OC43 and 229E in parallel. While SARS CoV infections induced an anamnestic IgG antibody response to the 229E and OC43 viruses, these cross-reactive antibodies remained of high avidity from early (the first month) postinfection. The results showed that assays to detect low-avidity antibody may be useful for discriminating early from late antibody responses and also for distinguishing anamnestic cross-reactive antibody responses from primary specific responses. This may be useful in some clinical situations.
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Griswold, William R. "A Quantitative Relationship Between Antibody Affinity and Antibody Avidity." Immunological Investigations 16, no. 2 (January 1987): 97–106. http://dx.doi.org/10.3109/08820138709030567.

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Dissertations / Theses on the topic "Antibody avidity"

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Canelle, Quentin. "Real Time Surface Plasmon Resonance Biosensors, a Powerful Technology to Assess Polyclonal Antibody Avidity." Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/216754.

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The present research focused on the development of a new methodology to assess the strength of the interaction between vaccine antigens and elicited polyclonal antibodies through SPR biosensors. Quantifying the binding strength of polyclonal antibodies is of first importance to evaluate the quality of the vaccine as well as to increase the scientific knowledge of immune protection mechanisms. To now the development of such tool has been complicated by the non-specific binding caused by high protein abundance in the blood and serum samples but also by the way of interpreting the data resulting from multi-interaction events measured at the same time. At first, we unsuccessfully tried to segregate the individual affinity contribution of each antibody population by measuring the signal as the sum of singular interactions. Differentiation of the singular contribution would have needed the fulfillment of the “additivity” hypothesis, meaning that each antibody bind identically alone or in mixture with other antibody. This hypothesis was not met and mathematical assessment by the sum of singular contribution led to fitting results that did not reflect the biological reality. It was therefore decided to switch the analysis method and to measure the end association binding level reached by the different samples injected at the same specific antibody content. The dissociation behavior was interpreted by the percentage of binding after long and fixed dissociation time. In a first application, we compared the antibodies elicited by two different commercially available vaccines and we showed that the binding interaction was not concentration dependent as, highly different levels were reached when injecting identical antibody concentration. No statistical significant difference was observed between both vaccines. Research firstly focused on the decrease of the non-specific binding and we found that ionic strength was a key parameter, increasing the buffer salt concentration reduced the non-specific binding without diminishing the binding strength. The sample composition was also a key parameter and purifying the IgG allowed to decrease dramatically the undesired binding events. A second application aimed at showing the equivalence between two different antigen constructions for two antibodies population. Even if identical antigen level immobilization is a challenge, the methodology is completely suitable to perform a 2-dimensional comparison (ligand and analyte). A last application was dedicated to the comparison between D and Q-pan Flu vaccines, and results showed that there was no statistical evidence of significant differences between both vaccines. End association level correlated well with haemagglutination inhibition assay at least when serum samples were not diluted at the same antibody content. This last application also showed that throughput may be extended to more than 50 samples per 80 hours
Doctorat en Sciences agronomiques et ingénierie biologique
info:eu-repo/semantics/nonPublished
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Newman, Peter Michael Pathology UNSW. "Antibody and Antigen in Heparin-Induced Thrombocytopenia." Awarded by:University of New South Wales. Pathology, 2000. http://handle.unsw.edu.au/1959.4/17485.

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Immune heparin-induced thrombocytopenia (HIT) is a potentially serious complication of heparin therapy and is associated with antibodies directed against a complex of platelet factor 4 (PF4) and heparin. Early diagnosis of HIT is important to reduce morbidity and mortality. I developed an enzyme immunoassay that detects the binding of HIT IgG to PF4-heparin in the fluid phase. This required techniques to purify and biotinylate PF4. The fluid phase assay produces consistently low background and can detect low levels of anti-PF4-heparin. It is suited to testing alternative anticoagulants because, unlike in an ELISA, a clearly defined amount of antigen is available for antibody binding. I was able to detect anti-PF4-heparin IgG in 93% of HIT patients. I also investigated cross-reactivity of anti-PF4-heparin antibodies with PF4 complexed to alternative heparin-like anticoagulants. Low molecular weight heparins cross-reacted with 88% of the sera from HIT patients while half of the HIT sera weakly cross-reacted with PF4-danaparoid (Orgaran). The thrombocytopenia and thrombosis of most of these patients resolved during danaparoid therapy, indicating that detection of low affinity antibodies to PF4-danaparoid by immunoassay may not be an absolute contraindication for danaparoid administration. While HIT patients possess antibodies to PF4-heparin, I observed that HIT antibodies will also bind to PF4 alone adsorbed on polystyrene ELISA wells but not to soluble PF4 in the absence of heparin. Having developed a technique to affinity-purify anti-PF4-heparin HIT IgG, I provide the first estimates of the avidity of HIT IgG. HIT IgG displayed relatively high functional affinity for both PF4-heparin (Kd=7-30nM) and polystyrene adsorbed PF4 alone (Kd=20-70nM). Furthermore, agarose beads coated with PF4 alone were almost as effective as beads coated with PF4 plus heparin in depleting HIT plasmas of anti-PF4-heparin antibodies. I conclude that the HIT antibodies which bind to polystyrene adsorbed PF4 without heparin are largely the same IgG molecules that bind PF4-heparin and thus most HIT antibodies bind epitope(s) on PF4 and not epitope(s) formed by part of a PF4 molecule and part of a heparin molecule. Binding of PF4 to heparin (optimal) or polystyrene/agarose (sub-optimal) promotes recognition of this epitope. Under conditions that are more physiological and sensitive than previous studies, I observed that affinity-purified HIT IgG will cause platelet aggregation upon the addition of heparin. Platelets activated with HIT IgG increased their release and surface expression of PF4. I quantitated the binding of affinity-purified HIT 125I-IgG to platelets as they activate in a plasma milieu. Binding of the HIT IgG was dependent upon heparin and some degree of platelet activation. Blocking the platelet Fc??? receptor-II with the monoclonal antibody IV.3 did not prevent HIT IgG binding to activated platelets. I conclude that anti-PF4-heparin IgG is the only component specific to HIT plasma that is required to induce platelet aggregation. The Fab region of HIT IgG binds to PF4-heparin that is on the surface of activated platelets. I propose that only then does the Fc portion of the bound IgG activate other platelets via the Fc receptor. My data support a dynamic model of platelet activation where released PF4 enhances further antibody binding and more release.
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Meireles, Luciana Regina. "Estudo das Fontes de Infecção da Toxoplasmose Humana em Diferentes localidades do Estado de São Paulo." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/42/42135/tde-24112004-110833/.

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A toxoplasmose é uma protozoose de alta prevalência no Brasil, causada pelo Toxoplasma gondii, sendo transmitida pela ingestão de alimentos contaminados com oocistos, excretados em fezes de felinos, ou cistos, em carnes cruas ou mal cozidas. A doença é usualmente assintomática, mas em fetos ou pacientes com imunodepressão, pode ser devastadora. Neste trabalho, estudamos a prevalência sorológica da infecção em animais de diferentes regiões do estado de São Paulo, tanto de vida livre, cães (200/ABC) como indicadores ambientais, e gatos (100/São Paulo) como hospedeiros definitivos, e em animais de produção, bovinos (200/Taquarituba), suínos (200/Osasco), caprinos( 200/Botucatu), ovinos (200/São Manuel) e frangos de corte(185/Botucatu), além de estudos parasitológicos em gatos e águas sob suspeita. Foram padronizados ELISA para cada espécie animal, utilizando índices adequados e reprodutíveis, com confirmação por Western Blotting e determinação da avidez em amostras positivas. A prevalência da toxoplasmose animal foi determinada sendo crescente em suínos (8.5%), bovinos (11%), caprinos (17%), ovinos (31%), felinos (40%) e cães (50,5%), não sendo encontrada em frangos de corte. Em suínos, caprinos, cães e gatos, a freqüência de anticorpos de baixa avidez sugere que a transmissão da infecção é constante durante a vida do animal, mas em bovinos e ovinos não foram encontrados anticorpos de baixa avidez, sugerindo infecção precoce ou sazonal na vida do animal. Pela alta taxa de infecção recente em felinos, é possível prever uma fração significativa de animais excretando oocistos, embora sem comprovação parasitológica. A avaliação da presença de anticorpos anti-T.gondii deve ser criteriosa, sendo que os reagentes de hemaglutinação para uso humano fornecem resultados erráticos nesta medida. A pesquisa de oocistos na água é de baixa sensibilidade, devendo ser feita em materiais colhidos no período de suspeita da transmissão. Em São Paulo, o risco de transmissão da toxoplasmose está relacionado a quase todas as fontes de infecção pesquisadas, tornando necessários estudos para o melhor manejo dos animais de consumo humano e tratamento de água, com eliminação de gatos errantes.
Toxoplasmosis, caused by Toxoplasma gondii and highly prevalent protozoan disease in Brazil, is mainly transmitted by ingestion of contaminated food and water, both by oocysts, excreted in cat feces, or cysts from undercooked meat from warm-blooded animals. Usually asymptomatic, it is extremely severe in the fetus or immunosuppressed patients. In this work, we studied the serological prevalence of toxoplasmosis in animals from several regions of the São Paulo State, both free living, as dogs (ABC) as environmental contamination index, and cats (São Paulo, as definitive hosts, or livestock as cattle (Taquarituba), swine (Osasco), goats (Botucatu), sheep (São Manuel) and fowls (São Paulo), with parasitological studies in cats and suspicious drinking water. We standardized ELISA for each species, using reproducible and adequate indexes, with Western blot confirmation and avidity assays in positive samples. Toxoplasmosis prevalence was increasing in swine (8.5%), cattle (11%), goats (17%), sheep (31%), cats (40%) and dogs (50.5%), without positive sample in fowls. Goats, pigs, dogs and cats presented 5-20% low avidity antibody samples, suggesting sustained transmission during animal life, but cattle and sheep presented only high avidity samples, suggesting an seasonal or early in life infection. Due to the high recent infection rate in cats, it is possible to preview a significant oocyst excreting cat frequency, despite parasitological evidence. Antibody determination must be carefully evaluated, as human hemagglutination reagents give erratic information. Oocyst detection in drinking water presented very low sensitivity and must be performed only in water collected at the period of the infection. In São Paulo, almost all of tested sources are able of toxoplasmosis transmission, reinforcing the need of better management of livestock, adequate water treatment and elimination of free living cats.
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Santana, Silas Silva. "Análise cinética da resposta imune humoral contra a proteína recombinante SAG2A em pacientes com Toxoplasmose aguda." Universidade Federal de Uberlândia, 2011. https://repositorio.ufu.br/handle/123456789/16676.

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Fundação de Amparo a Pesquisa do Estado de Minas Gerais
Recombinant proteins from Toxoplasma gondii have been used in several experimental models, as well as for serodiagnosis of human toxoplasmosis, particularly to differentiate acute from chronic phases of the infection. In the present study, we evaluated the kinetics of IgM, IgA, and IgG isotypes, in addition to IgG1 and IgG3 subclasses, by testing sequential serum samples from patients with acute toxoplasmosis. It was carried out immunoassays by using SAG2A recombinant antigen and soluble antigen of Toxoplasma (STAg). The avidity of IgG1 antibody was assessed using slot blot assay. Additionally, a ratio between IgG1 and IgG3 subclasses (IgG3:IgG1) was determined and evaluated its degree of association with levels of IgM and IgA specific for STAg and the avidity index of IgG1 specific for SAG2A. The results showed a decreasing kinetic profile for SAG2A and STAg for IgM and IgA. The kinetic profile for the IgG antibody was increasing for both antigens. Compared to the avidity for IgG1, it was observed that sera from an early stage showed a low average avidity of IgG1 for SAG2A while the same samples showed intermediate mean avidity of IgG1 when STAg was used as antigen. In a later phase, the average avidity observed was high for STAg and intermediate for SAG2A in the same tested sera suggesting that SAG2A may be a promising tool for the detection of avidity. Associations between IgG3/IgG1 and specific IgM and IgA levels for STAg and the avidity index of specific IgG1 for SAG2A were found, and together these parameters could be used as valuable tools in the diagnosis of human toxoplasmosis, especially in situations when the determination of different phases is critical.
Proteínas recombinantes de Toxoplasma gondii têm sido utilizadas em diversos modelos experimentais, assim como para o diagnóstico sorológico da infecção humana por este parasito, principalmente com o intuito de diferenciar as fases aguda e crônica da toxoplasmose. Neste estudo, foi avaliada a cinética dos anticorpos IgM, IgA ,IgG e subclasses (IgG1 e IgG3) através de imunoensaios realizados em amostras seqüenciais de soros humanos, provenientes de pacientes com toxoplasmose aguda. Estas amostras foram testadas frennte ao antígeno recombinante SAG2A, utilizando-se como paradigma de comparação o antígeno solúvel total de Toxoplasma (STAg). A avidez do anticorpo IgG1 foi avaliada utilizando a metodologia slot-blot. Adicionalmente, a razão entre as subclasses IgG3 e IgG1 (IgG3:IgG1) foi determinada e avaliada quanto ao grau de associação com os níveis de IgM e IgA específicos para STAg e aos índices avidez de IgG1 específicos para SAG2A. Os resultados demonstraram a presença de níveis decrescentes de IgM e IgA para ambos os antígenos utilizados, enquanto que para o isotipo IgG o perfil cinético demonstrou níveis crescentes para ambas preparações antígênicas. Em relação aos índices de avidez para IgG1, foi observado que amostras de soros de uma fase inicial apresentaram baixa avidez média de anticorpos IgG1 dirigidos para SAG2A, enquanto que as mesmas amostras demonstraram avidez média intermediária de IgG1 quando STAg foi utilizado como antígeno. Já em uma fase mais tardia, a avidez média observada foi alta para STAg e intermediária com SAG2A. A razão entre IgG3:IgG1 obtida no primeiro bimestre foi significantemente maior para SAG2A em comparação com STAg. Tomados em conjunto, os resultados obtidos no presente estudo indicam que a proteína recombinantes SAG2A pode se constituir em uma ferramenta efetiva na diferenciação das fases da infecção humana por T. gondii.
Mestre em Imunologia e Parasitologia Aplicadas
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Cilla, Brian. "Comparison of two methods for estimating antibody avidity a thesis submitted in partial fulfillment ... Master of Science in Periodontics ... /." 1989. http://books.google.com/books?id=St89AAAAMAAJ.

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Books on the topic "Antibody avidity"

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Fard, Amir Hossein Mohagheghi. Positivity for and avidity of human herpesviruses IgG antibody determined by ELISA. Manchester: University of Manchester, 1996.

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Bristow, Michelle A. Measurement of antibody avidity for hepatitis B virus. 1996.

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Lyons, Marie. The development of a redioimmunoassay for use in antibody avidity measurements in the diagnosis of human herpesvirus-6 infections. 1995.

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Book chapters on the topic "Antibody avidity"

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Bruderer, U., E. Fürer, S. J. Cryz, and A. B. Lang. "The Role of Human Monoclonal Antibody Specificity and Avidity in the Protection Against Gram-negative Bacteria." In Immunotherapeutic Prospects of Infectious Diseases, 373–77. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-76120-1_50.

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Dakshinamurti, Krishnamurti, and Edward S. Rector. "[12] Monoclonal antibody to biotin." In Avidin-Biotin Technology, 111–19. Elsevier, 1990. http://dx.doi.org/10.1016/0076-6879(90)84266-j.

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KOSTULAS, V., T. OLSSON, and H. LINK. "Detection of Oligoclonal IgG in Unconcentrated Cerebrospinal Fluid by Agarose Isoelectric Focusing and Double Antibody Avidin–Biotin-Peroxidase." In Protides of the Biological Fluids, 171–74. Elsevier, 1985. http://dx.doi.org/10.1016/b978-0-08-031739-7.50044-6.

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Shively, John E., Christoph Wagener, and Brian R. Clark. "[43] Solution-phase RIA and solid-phase EIA using avidin-biotin systems for analysis of monoclonal antibody epitopes and affinity constants." In Immunochemical Techniques Part I: Hybridoma Technology and Monoclonal Antibodies, 459–72. Elsevier, 1986. http://dx.doi.org/10.1016/0076-6879(86)21045-9.

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"from CD99 high expressors but membranes from CD99 low expressors required exposure of 5 minutes before the 32 kD band was apparent [50]. Unfortunately, these tests gave no information about the Xga protein because the position of the Xga band was masked by the antibody light chain which became labelled. However, a 32 kD band was seen in the Xga-immunoprecipitate from Xg(a+) but not from Xg(a-) cells [50]. It has not yet been proved that this is the CD99 protein because this band was not stained by immunoblotting Xga-immunoprecipitates with 12E7. The luciferin-enhanced luminescent proceedure to detect the avidin-biotin label is very much more sensitive than immunoblotting. Our results support the theory that Xga and CD99 may be associated in the membrane. Cloning of the XG gene will increase our understanding of this relationship. The important blood group genes have been cloned but two big problems remain, regulation on antigen expression and the function of blood group polymorphisms. Rare phenotypes should still be studied because they will contribute to unravelling the mechanisms responsible for the polymorphisms. The wealth of serological information which continues to increase includes many examples of variable expression of red cell antigens. Some antigens do not show the same variation on other cells suggesting that some modes of regulation may be limited to red cells. Association of blood group antigens with proteins of known function and identification of red cell antigens on cells other than red cells will contibute to understanding the functions of the blood group polymorphisms. REFERENCES 1. P.L. Mollison, C.P. Engelfreit and M. Contreras, Blood Transfusion in Clinical Medicine. Blackwell Scientfic Publications, Oxford (1993). 2. M. Lewis (Chairman) et al, Vox Sang., 61_, 158-160 (1991). 3. G.L. Daniels, J.J. Moulds (chairman) et al, Vox Sang., 65, 77-80 (1993). 4. A.C. Petty, J. Immunol. Meth., 161. 91-95 (1993). 5. J. M. Moulds, in Immunobiology of Transfusion Medicine. G. Garratty ed. Marcel Dekker. Inc., New York, (1994) pp. 273-297. 6. J.M. Moulds, M.W. Nickells, J.J. Moulds, M.C. Brown and J.P. Atkinson, J. Exp. Med., 173, 1159-1163 (1991). 7. N. Rao, D.J. Ferguson, S-F. Lee and M.J. Telen, J. Immun., 146, 3502-3507 (1991). 8. A.C. Petty, (abs) Transfusion Medicine 3 Suppl 1, 84 (1993). 9. J.M. Moulds, J.J. Moulds, M. Brown and J.P. Atkinson, Vox Sang. 62, 230-235 (1992)." In Transfusion Immunology and Medicine, 198. CRC Press, 1995. http://dx.doi.org/10.1201/9781482273441-16.

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"designation will be used for the 12E7 antigen. CD99 was first detected by 12E7, a monoclonal antibody made in response to a T-cell line, and was initially thought to be a ‘thymus-leukaemia’ marker antigen [41]. Many similar antibodies were made which reacted with different epitopes of the same molecule [see 42]. Independently, CD99 was identified as E2, a T-cell adhesion molecule, and as a marker antigen for Ewing’s tumours [see 40]. CD99 is expressed on many tissues including red cells. By somatic cell hybridization and biochemical studies, Goodfellow and his colleagues have shown that MIC2, the structural locus encoding the 12E7 antigen, is located on the short arm of the X chromosome and on the short arm of the Y chromosome within the pairing regions [43]. MIC2 has been cloned [44]. XG is X-borne. On red cells, CD99 expression is a quantitative polymorphism [45]. Family studies proved that this polymorphism is also caused by regulator genes on X and Y chromosomes. XG appears to be the regulator on the X [46]. There is variation in CD99 expression on cells other than red cells. In a recent publication, CD99 was found on all haemopoeitic cells but was variably expressed during leucocyte differentiation [40]. Use of different monoclonal antibodies and variability of expression during maturation offered an explanation for the previous apparently contradictory findings by different laboratories. Both Xga and CD99 are sialoglycoproteins [47,48,49]. These glycoproteins differ in Mr and in their sialic acid content [49]. Immunostaining of separated membrane components with 12E7 and similar antibodies had demonstated that the MIC2 gene product was a 30-32 kD protein. 12E7 also bound to an intracellular band of 28 kD which was found in mouse cell lines in addition to human cell lines, platelets, lymphocytes and red cells but it was not encoded by the MIC2 gene [47]. Immunoblotting assays have shown that Xga was associated with two diffuse bands of 22-25 kD and 26.5-29 kD [49]. These findings supported the evidence that Xga and CD99 were products of different structural loci. However, XG appears to regulate CD99 expression on red cells and Latron and colleagues found that purified CD99 protein inhibited binding of 12E7 and of anti-Xga to red cells [48]. We have studied the immunochemical relationship of Xga and CD99 [50]. One approach was immunoprecipitation of membrane components from biotin labelled cells. Bands are detected by chemiluminescence via peroxidase-conjugated avidin. The 32 kD protein of CD99 was visualised by this technique and the quantitative polymorphism was also demonstrated since the 32 kD band is seen on X-ray film after 2 minutes in membranes." In Transfusion Immunology and Medicine, 197. CRC Press, 1995. http://dx.doi.org/10.1201/9781482273441-15.

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Conference papers on the topic "Antibody avidity"

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Friess, Thomas, Stefanie Lechner, Esther Abraham, Ann-Marie Broeske, Sabine Bader, Andreas Roller, Meher Majety, et al. "Abstract 952: Induction of avidity-driven hyperclustering of DR5 by a new FAP-DR5 bispecific antibody (RG7386) leads to strong anti-tumor efficacy." In Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA. American Association for Cancer Research, 2015. http://dx.doi.org/10.1158/1538-7445.am2015-952.

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Deak, Laura Laura Codarri, Stefan Seeber, Mario Perro, Patrick Weber, Laura Lauener, Standford Chen, Sonja Offner, et al. "Abstract 2270: RG7769 (PD1-TIM3), a novel heterodimeric avidity-driven T cell specific PD-1/TIM-3 bispecific antibody lacking Fc-mediated effector functions for dual checkpoint inhibition to reactivate dysfunctional T cells." In Proceedings: AACR Annual Meeting 2020; April 27-28, 2020 and June 22-24, 2020; Philadelphia, PA. American Association for Cancer Research, 2020. http://dx.doi.org/10.1158/1538-7445.am2020-2270.

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Narang, Upvan, George P. Anderson, Keeley D. King, Heidi S. Liss, and Frances S. Ligler. "Enhanced biosensor performance using an avidin-biotin bridge for antibody immobilization." In BiOS '97, Part of Photonics West, edited by Richard B. Thompson. SPIE, 1997. http://dx.doi.org/10.1117/12.273534.

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Meyers, K. M., K. J. Wardrop, C. M. Helmick, and F. P. White. "PRESENCE OF VWF IN VASCULAR ENDOTHELIUM BUT NOT PLATELETS FROM CONTROL DOGS AND VIIIR:AG-DEFICIENT DOGS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644501.

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Blood vessels from control and VIIIR:AG-deficient dogs (plasma VIIIR:AG was <5% of control) were surgically removed, cryosectioned, airdried and processed for immunohistochemical detection of VWF using a monoclonal antibody against human VWF, a polyclonal antibody against human VWF, and a polyclonal antibody against canine VWF. All antibodies were monospecific for canine VWF. The secondary antibody was conjugated to fluorescein or rhodamine. A biotin-avidin system was also used. Each antibody detected VIIIR:AG in veins, venules, and arterioles from control and VIIIR:AG-deficient dogs. Immunofluorescence was observed only in areas of the vessel occupied by endothelial cells. There was no detectable difference in the distribution of VIIR:AG or the fluorescence intensity in vessels from control and VIIIR:AG-deficient dogs. Platelets were isolated by gel filtration, adhered to glass slides, fixed, and then incubated with antibodies to VWF. As positive controls, human platelets were processed simultaneously. VWF could not be identified by immunohistochemistry in platelets from control and VIIIR:AG-deficient dogs. Human and canine platelets were also washed and lysed by 5 freeze/thaw cycles or by using the French Pressure Cell Press. The lysate from canine platelets did not have VWF detectable by an ELISA.
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Risberg, B., G. K. Hansson, E. Eriksson, and B. Wiman. "IMMUNOHISTOCHEMICAL LOCALIZATION OF PLASMINOGEN ACTIVATOR INHIBITOR (PAI) IN TISSUE." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644443.

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The origin of tissue plasminogen activator inhibitor (PAI) has not been fully elucidated. Platelets are rich in PAI and endothelial cells (EC) in culture produce the inhibitor (PAI 1), which seems to be a major secretory protein. Another inhibitor (PAI 2) has been demonstrated in the placenta. In the present study we localized PAI 1 in various human tissues using a polyclonal antibody against human PAI 1 and fluorescence technique. Tissue sections were incubated with a polyclonal rabbit-anti-human PAI antibody in various dilutions followed by incubation with biotinylated goat-anti-rabbit IgG and FITC-labelled Avidin. Positive identification using this technique was made in endothelium of liver sinusoids and in hepatocytes. Most vessels in systemic and pulmonary circulation showed positive fluorescence in the endothelial layer. No quantitative evaluation was possible with this technique. Synthesis of PAI in liver could provide an explanation for the efficient inactivation of tissue plasminogen activator (t-PA) during liver passage. Localization of PAI in vascular tissue corroborated studies from EC cultures.
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Mathew, Trupthi, Punarvasu Joshi, Shalini Prasad, Michael Goryll, Andreas Spanias, and Trevor J. Thornton. "Silicon Based Pore Systems for Emerging Biosensor Applications." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11707.

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Recent research in the domain of single molecule biosensors aims at using silicon pore systems for the electrical detection of charged entities. Detection is achieved through resistive pulse measurements also known as Coulter counting. This work demonstrates the use of silicon based cylindrical micropores which can be used to detect biomolecules with high selectivity and robustness. The micropores used in the experiment were patterned using semiconductor processing techniques to have a final diameter of 5μm and a length of 30μm on a siliconsubstrate. The probes used in the study were silica beads which have been functionalized to detect two types of protein immunocomplexes: (i) biotin-avidin and (ii) immunoglobulin-G using its specific antibody within the silicon micropore system.
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Tomaslni, B. R., and D. F. Mosher. "PREFERENTIAL RECOGNITION OF VITRONECTIN (S-PR0TEIN) BY A MONOCLONAL ANTIBODY UPON INTERACTION WITH THROMBIN, ANTITHROMBIN AND GLYCOSAMINOGLYCANS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643634.

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V1tronect1n/S-Prote1n (VN/SP) is a glycoprotein present at a concentration of 200-400 ug/ml 1n plasma and serum. It has been shown to promote cel 1-substratum adhesion and to act as an Inhibitor of the membrane attack complex of complement and of the inactivation of thrombin by antithrombin III in the presence of low levels of heparin. We have previously shown that VN/SP binds more avidly to heparln-agarose and to a monoclonal antibody (MaVN/SP)-Sepharose column when present 1n serum rather than 1n plasma. In order to examine the possibility of a serum-induced conformational change, we utilized, 1n this study, an Indirect enzyme-linked Immunosorbent system to test for the exposure of new antigenic determinants. When MaVN/SP was Incubated with plasma or serum, recognition of VN/SP 1n serum was approximately 50 fold greater than recognition of VN/SP in plasma. Since VN/SP has been shown to Interact strongly with the thromb1n-ant1thrombin complex, we examined the antigenicity of VN/SP when Incubated with thrombin and antithrombin 1n the presence and absence of heparin. Incubation of VN/SP with heparin promoted a 2.5-fold Increase 1n recognition by MaVN/SP. When MaVN/SP was Incubated with thromb1n-ant1thrombin but not thrombin or antithrombin alone, recognition was Increased by 7-fold 1n the absence of heparin and by 32-fold 1n the presence of heparin. This differential recognition of VN/SP was not observed with a second monoclonal antibody raised originally against S-Prote1n. Treatment of VN/SP with various glycosaminoglycans and polysaccharides demonstrated the following relative potencies for Induction of the partial antigenic change: dextran sulfate>fucoidan>heparin> dermatan suIfate>hyaluronic acid. No effect was detected upon Incubation of VN/SP with keratan sulfate, heparan sulfate or chondroltln sulfate. These data suggest a conformational change Induced by thrombin-antlthrombin which may allow VN/SP to Interact more avidly with other molecules such as heparin. The physiological role of this putative conformational change is under investigation.
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Hirai, K., K. Yasunaga, and R. Ryo. "STUDIES ON PLATELET ANTIGENS AGAINST SERA FROM PATIENTS WITH ITP." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644583.

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Chronic idiopathic thrombocytopenic purpura (ITP) is a clinical syndrome characterized by destruction of platelets by antiplatelet antiboodies. The precise pathogenic mechanism of platelet destruction in ITP is not known, although many investigators have reported that platelet-associated IgG (PAIgG) is increased in this desease. We have evaluated PAIgG in 66 patients with ITP by a competitive solidphase microenzyme immunoassay and investigated its specificity aganist antiplatelet antibody in 24 patients with ITP by Western blotting. PAIgG values were elevated in most ITP patients with platelet counts of under 50,000/μl, but within normal range in most patients with platelet count of over 50,000/μl. PAIgG values were also elevated in ITP patients with megakaryocyte counts of over 200/μl, and within normal range in most patients with normal megakaryocyte counts. Western blotting was carried out by SDS-PAGE of whole platelet lysate or platelet membrane lysate and trasfer of the platelet fraction onto nitrocellulose strips. Bound immunoglobulins were detected with an avidin-biotin-peroxidase system. Several bands of bound immunoglobulins were detected in the whole platelet lysates of ITP patients, but most of these could not be detected in platelet membrane lysates. This finding suggests that some immunoglobulins from ITP patients may bind to cytoplasmic proteins in whole platelet lysate. These observations are consistent with the hypothesis that the pathogenesis of ITP involves an immunological mechanism.
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Rodríguez, José A., Héctor E. López-Valdes, Gustavo F. Helguera, Sokuntheavy So, Rosendo Luria-Pérez, Tracy R. Daniels, Andrew C. Charles, and Manuel L. Penichet. "Abstract 4456: Molecular events required for the induction of lethal iron deprivation in malignant hematopoietic cells via an antibody-avidin fusion protein specific for human transferrin receptor 1." In Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC. American Association for Cancer Research, 2010. http://dx.doi.org/10.1158/1538-7445.am10-4456.

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Grøndahl-HANSEN, J., N. Agerlin, L. S. Nielsen, and K. Danø. "SENSITIVE AND SPECIFIC ENZYME-LINKED IMMUNOSORBENT ASSAY FOR UROKINASE-TYPE PLASMINOGEN ACTIVATOR IN HUMAN PLASMA." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644425.

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An enzyme-linked immunosorbent assay (ELISA) was developed for the measurement of human urokinase-type plasminogen activator (u-PA) in plasma and serum. Microtiter plates were coated with a monoclonal antibody and incubated with standard or sample. Bound u-PA was quantitated with polyclonal antibodies conjugated with biotin, followed by avidin-peroxidase. The assay was 10-fold as sensitive as other previously reported ELISAs, the detection limit being approximately 1 pg of u-PA in a volume of 100 μl with a linear dose-response up to 15 pg of u-PA. The assay detected active u-PA and its inactive proenzyme form equally well and the recovery of both forms was higher than 90% in plasma. A variety of structurally related proteins, including t-PA, were tested, but no reaction with proteins other than u-PA and its amino-terminal degradation product were observed. The intra-assay and inter-assay coefficients of variation for determination of u-PA in plasma were 7.6% and 8.4%, respectively. The assay was equally applicable to serum. The values obtained with plasma and serum were similar, and the results were not affected by small variations in the preparation of the samples. The ELISA was used to measure the concentration of u-PA in plasma from 34 healthy donors. The mean values for u-PA in plasma from healthy donors was 1.1 ng/ml ± 0.3 ng/ml (SD) (range 0.6 - 1.5 ng/ml). No significant differences were found between men and women and no correlation between u-PA concentration and age could be demonstrated.The mean u-PA concentration in plasma from healthy donors obtained in this study is substantially lower than that reported by others. This might be due to different methods of determination of the protein content of the standard preparations or to differences in the specificity of the assays.
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