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Biomedical subjects

Z Pucar

Publications and source records attributed to Z Pucar.

11 recordsLinked to original sources
PubMed1993

Quantitative and qualitative characterization of virus envelope proteins and specific polyclonal antibodies.

A method for simultaneous qualitative and quantitative characterization of virus envelope proteins and virus-neutralizing antibodies is described. The quantitative estimate is based solely on the precipitation of the antibody/antigen (Ab/Ag) complexes at equivalence under equilibrium conditions. The qualitative analysis is performed by determining the diffusion coefficients, i.e., molecular masses of antigen and antibodies. Isolation, purification, labelling of antigen and antibodies and use of any standards are not required. The analyses are carried out directly in crude biological fluids in which antigen and antibodies naturally occur. The results obtained are independent on the avidity of the Ab/Ag system to be analysed. The method was tested by using antigenic subunits of Newcastle disease virus (NDV) and four chicken anti-NDV immune sera of different avidities.

Animals↗
PubMed1992

Microgravimetric determination of precipitable antigens and antibodies in native biological fluids.

A method for the exact and simultaneous measurements of immunoprecipitable antigens and antibodies in native biological fluids is described. It is based solely on the microgravimetric analysis of at least two immunoprecipitates of different stoichiometric compositions. The volume ratios of antigen and antibody solutions for the preparation of the immunoprecipitates at equivalence are determined by the two-cross immunodiffusion technique. The proposed procedure has advantages over other methods for quantitative determination of proteins, since the separation, purification and labelling of immune components, as well as the use of standards, are not required. The method was tested by using human serum albumin (HSA) and three rabbit antiHSA immune sera of various avidities. Immunoprecipitates of different stoichiometric compositions were prepared at pH 5.0, 5.5, 7.0 and 8.6. The minimal precision of the method was +/- 0.2 micrograms of protein. The coefficients of variation were 0.14 to 0.38% for HSA and 0.03 to 0.08% for antiHSA antibody.

Animals↗
PubMed1985

Effects of polyethylene glycol and dextrans on immunoprecipitations: a two-cross immunodiffusion study.

Precipitating titers and immunochemical titers obtained in a wide range of antigen-to-antibody concentration ratios by the two-cross immunodiffusion technique are compared with the corresponding laser light scatter precipitin curves. The two-cross immunodiffusion technique has also been applied to investigate whether polyethylene glycol of molecular mass 6000 and dextrans of molecular masses from 10,000 to 2,000,000 enhance the immunoprecipitation processes of the system human serum IgG-rabbit immune serum at pH 5.5 and 8.1 at 20 degrees C. It was found that the significant increase of precipitating titers of both precipitating components in the presence of polyethylene glycol is a consequence of a strong decrease of solubility of the primary antigen-antibody complex. The decrease of solubility does not affect the immunochemical titer of the immune serum, indicating stoichiometrical invariance of the precipitate at the equivalence. The apparent strong decrease of diffusion coefficients of both antigen and antibody in 20- and 40-g/liter polyethylene glycol solution is attributed to increase of viscosity of the solutions and to a partial self-association of protein molecules due to steric exclusion. In 40-g/liter polyethylene glycol solutions at pH 5.5 every fourth molecular entity of antigen and every third molecular entity of antibody are present in the form of a two-molecular self-associate, whereas in 20-g/liter polyethylene glycol solutions only 1% of antigen molecules and 8% of antibody molecules are associated. With the increase of pH to 8.1 the self-association of protein molecules is strongly further enhanced. Dextrans in 20-g/liter solutions, without regard to their relative molecular masses, do not influence precipitating titers and solubility of the antigen-antibody system at equivalence and do not enhance self-association of protein molecules. The strong decrease of diffusion coefficients of immunoglobulin G antigen and antibodies in dextran solutions is solely attributed to the increase of viscosity of the dextran solutions; hence there was no evidence of interaction of dextrans with serum IgG proteins.

Animals↗
PubMed1979

Precipitation of calcium phosphates under conditions of double diffusion in collagen and gels of gelatin and agar.

One-dimensional double diffusion was applied to determine critical concentrations at which the precipitation of calcium phosphates occurs in reconstituted connective tissue collagen and agar gels at 37 degrees C and in gelatin gels at 25 degrees C. Experiments were performed in the presence of unbuffered 0.15 mol dm-3 NaCl, or 0.15 mol dm-3 NaCl-veronal adjusted to pH 7.4. It was found that critical concentrations of precipitation of both precipitating components, CaCl2 and phosphate buffer (pH 7.4), were equimolar and independent of the ratios of initial concentrations of the components. Critical concentrations of precipitation were not affected by the concentrations and kinds of gels used. The first-formed precipitates showed amorphous structure by X-ray diffraction analyses. Infrared (IR) spectra of the precipitates indicated CaHPO4 . H2O to be their predominant species. The molar Ca/P ratio obtained by chemical analyses was 1.08. This precipitate transformed in time into octacalcium phosphate. In all experiments, two very thin membranes of precipitate were formed in the gel column at the onset of precipitation simultaneously on both sides of the actual disc of precipitate. IR spectra and chemical analyses showed that both membranes were identical to the actual precipitation discs.

Agar↗