Jelly Potentiometry, Do It Yourself

Understanding potentiometry is a difficult task when students in initial courses of Analytical Chemistry are first introduced to instrumental techniques. The closest instrument to them is a pH meter, which is frequently used as a “black box”, without a real understanding of how it works. Here we present the assembly of jelly modules that the students can combine in different ways with the purpose of visualizing what reference and indicator electrodes are and their function when they are used in potentiometric measurements with quantitative purposes. This didactic sequence was used during six semesters in a first course of Analytical Chemistry dictated for students becoming laboratory technicians in Chemistry and Chemical Engineering. It is a hands-on experiment to exemplify both a direct potentiometric analysis and a potentiometric titration (indirect analysis). It is simple, low-cost, and easy to apply. It only requires gelatin, salts, pieces of metal, and a multimeter. The students showed interest in its execution, and they were able to identify the functions of the electrodes, discuss the different analytical implications of potentiometric techniques among themselves, and make the requested graphics with very good results.Fil: Sosa, Griselda Leonor. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de General Sarmiento. Instituto de Ciencias; ArgentinaFil: Deluchi, Guido Enrico. Universidad Nacional de General Sarmiento. Instituto de Ciencias; ArgentinaFil: Ramírez, Silvana A.. Universidad Nacional de General Sarmiento. Instituto de Ciencias; ArgentinaFil: Hamer, Mariana. Universidad Nacional de General Sarmiento. Instituto de Ciencias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Cytokines induced by experimental anti-tetanus immunization. Vaccine formulation effect

Fil: Castro, Marisa. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral; Argentina.Fil: Mateo, Nancy A. ANLIS Dr.C.G.Malbrán. Centro Nacional de Control de Calidad de Biológicos; Argentina.Fil: Lavigne, Victoria. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral; Argentina.Fil: Deluchi, Silvana. ANLIS Dr.C.G.Malbrán. Centro Nacional de Control de Calidad de Biológicos; Argentina.Fil: Atzori, Carlos. ANLIS Dr.C.G.Malbrán. Centro Nacional de Control de Calidad de Biológicos; Argentina.Fil: Piudo, Luciana. ANLIS Dr.C.G.Malbrán. Centro Nacional de Control de Calidad de Biológicos; Argentina.Fil: Brero, María Luisa. ANLIS Dr.C.G.Malbrán. Centro Nacional de Control de Calidad de Biológicos; Argentina.Fil: Manghi, Marcela. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral; Argentina.Several factors are involved in the selective activation of T helper 1 or T helper 2 cells, such as the type of antigen-presenting cells involved in the immune response and the different physical characteristics of antigens. The aim of this work was to evaluate if adding other antigens to tetanus toxoid modifies the original immune response. BALB/c mice were immunized with tetanus and diphtheria toxoids associated with whole-cell Bordetella pertussis (DTPw vaccine), B. pertussis soluble antigens (DTPa vaccine) or Salmonella typhi plus DTPa (DTPaSt vaccine). DTPw and DTPaSt immunization induced a T helper 1/T helper 2 (Th1/Th2) anti-tetanus response with gamma interferon and interleukin 5 production. DTPa immunization induced a Th2 response with production of interleukin 5 and interleukin 6. Only DTPw vaccine induced higher levels of IL-12 in non-immunized mice. Our findings indicate that the co-injection of whole-cell antigens such as B. pertussis or S. typhi, modifies the anti-tetanus response shifting it from Th2 to Th1 type. However, the original Th2 immune response is not modified when the vaccine consists only of soluble antigens

Cytokines induced by experimental anti-tetanus immunization. Vaccine formulation effect

Fil: Castro, Marisa. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral; Argentina.Fil: Mateo, Nancy A. ANLIS Dr.C.G.Malbrán. Centro Nacional de Control de Calidad de Biológicos; Argentina.Fil: Lavigne, Victoria. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral; Argentina.Fil: Deluchi, Silvana. ANLIS Dr.C.G.Malbrán. Centro Nacional de Control de Calidad de Biológicos; Argentina.Fil: Atzori, Carlos. ANLIS Dr.C.G.Malbrán. Centro Nacional de Control de Calidad de Biológicos; Argentina.Fil: Piudo, Luciana. ANLIS Dr.C.G.Malbrán. Centro Nacional de Control de Calidad de Biológicos; Argentina.Fil: Brero, María Luisa. ANLIS Dr.C.G.Malbrán. Centro Nacional de Control de Calidad de Biológicos; Argentina.Fil: Manghi, Marcela. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Estudios de la Inmunidad Humoral; Argentina.Several factors are involved in the selective activation of T helper 1 or T helper 2 cells, such as the type of antigen-presenting cells involved in the immune response and the different physical characteristics of antigens. The aim of this work was to evaluate if adding other antigens to tetanus toxoid modifies the original immune response. BALB/c mice were immunized with tetanus and diphtheria toxoids associated with whole-cell Bordetella pertussis (DTPw vaccine), B. pertussis soluble antigens (DTPa vaccine) or Salmonella typhi plus DTPa (DTPaSt vaccine). DTPw and DTPaSt immunization induced a T helper 1/T helper 2 (Th1/Th2) anti-tetanus response with gamma interferon and interleukin 5 production. DTPa immunization induced a Th2 response with production of interleukin 5 and interleukin 6. Only DTPw vaccine induced higher levels of IL-12 in non-immunized mice. Our findings indicate that the co-injection of whole-cell antigens such as B. pertussis or S. typhi, modifies the anti-tetanus response shifting it from Th2 to Th1 type. However, the original Th2 immune response is not modified when the vaccine consists only of soluble antigens

Development of an ELISA for measuring the activity of tetanus toxoid in vaccines and comparison with the toxin neutralization test in mice

An enzyme-linked immunosorbent assay (ELISA) has been developed to measure anti-tetanus toxoid antibody levels in immunized guinea-pig sera as a useful alternative to the currently used toxin neutralization test (TNT) in determining the activity of the tetanus toxoid in vaccines. The ELISA was found to measure antibody levels as low as 5.8 x 10(-5) IU/ml. Furthermore, a comparison of the results from ELISA and TNT involving 132 different commercial vaccines showed a very good correlation (r = 0.94, p < 0.001) between antibody levels measured by both methods. The results suggest that the proposed ELISA is a reliable, simple and economical alternative to the TNT in mice for assessing the activity of tetanus toxoids in vaccines

Development of an alternative method for testing the immunogenicity of diphtheria vaccines

The immunogenicity of the diphtheria component of 73 commercial vaccines from five different manufacturers was tested by the toxin neutralization test (TNT) and the enzyme-linked immunosorbent assay (ELISA) developed in our laboratory. A comparison of the antibody levels measured by both assays showed a very good correlation (r = 0.95, p < 0.001). The results suggest that the proposed ELISA is a reliable, simple and economical alternative to the TNT in guinea pigs. Also, the ELISA was found to measure IgG antibody levels as low as 5.5 x 10(-5) IU ml-1. To evaluate the possibility of accelerating the active immunization during the activity test of vaccines, an alternative schedule using one single human dose was assayed. A very good correlation was observed between the IgG antibody response obtained with this schedule and with the traditional programme. Therefore, the cost and the time required to perform the activity test may be considerably reduced when both the rapid immunization schedule and the ELISA are used

Whole-cell Bordetella pertussis vaccine component modulates the mouse immune response to an unrelated soluble antigen

Fil: Lavigne, María Victoria. Instituto de Estudios de la Inmunidad Humoral, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires; Argentina.Fil: Castro, Marisa. Instituto de Estudios de la Inmunidad Humoral, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires; Argentina.Fil: Mateo, Nancy A. ANLIS Dr.C.G.Malbrán. Centro Nacional de Control de Calidad de Biológicos; Argentina.Fil: Deluchi, Silvana. ANLIS Dr.C.G.Malbrán. Centro Nacional de Control de Calidad de Biológicos; Argentina.Fil: Atzori, Carlos. ANLIS Dr.C.G.Malbrán. Centro Nacional de Control de Calidad de Biológicos; Argentina.Fil: Piudo, Luciana. ANLIS Dr.C.G.Malbrán. Centro Nacional de Control de Calidad de Biológicos; Argentina.Fil: Calcagno, María. Departamento de Físico-Matemática, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires; Argentina.Fil: Brero, María Luisa. ANLIS Dr.C.G.Malbrán. Centro Nacional de Control de Calidad de Biológicos; Argentina.Fil: Manghi, Marcela. Instituto de Estudios de la Inmunidad Humoral, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires; Argentina.Several factors are involved in the selective activation of Th1 or Th2 cells, such as different physical characteristics of antigens and the type of antigen-presenting cells involved in the immune response, among others. To study the influence of a particulate antigen on Th1/Th2 cell differentiation during the immune response to another antigen, we analysed the immune response to tetanus toxoid (soluble antigen) in BALB/c mice immunized with one of the three following vaccines: tetanus and diphtheria toxoids (DT), or DT associated with whole-cell Bordetella pertussis or its soluble antigens (DTPw and DTPa, respectively). Similar total antibody levels were observed for all vaccines. DT vaccine showed a higher IgG1/IgG2a ratio than the similar values observed for DTPw and DTPa vaccines. DT- and DTPa-primed spleen cells showed a Th2 (IL-5) profile while a Th1/Th2 (IFN gamma, IL-5) profile was observed for DTPw. IL-6 was only produced by DTPw-primed cells. Besides, IL-12 levels induced by DTPw were three times higher than the ones induced by both DT and DTPa. Our findings indicate that whole-cell B. pertussis priming modifies the tetanus immune response from Th2 to Th1/Th2 type probably via inflammatory mechanisms. In addition, in the light of conflicting reports regarding the mechanisms of protection induced by DTP vaccines, we studied the pertussis immune response. Only DTPw immunization generated memory T cells capable of proliferating with B. pertussis as an in vitro stimulus. Results might indicate that these cells may not play a key role in protecting against B. pertussis when the host is vaccinated with DTPa