PubMed Health⌕ Search

Biomedical subjects

H B Bohidar

Publications and source records attributed to H B Bohidar.

7 recordsLinked to original sources
PubMed2000

Anomalous colloidal stability of protein coated polystyrene latex beads studied by small angle light scattering.

Results of small angle laser light scattering experiments carried out on polystyrene latex beads coated with lysate of Plasmodium falciparum (Pf) antigen (Ag) and human seropositive sera (10:1 ratio) are reported for various NaCl concentrations (0-300 mM). The protein coated beads showed time-dependent coagulation. The normalised intensity of scattered light I(s)(t)/I(0) showed I(s)(t)/I(0)=1+(Gammat)(delta) behaviour with the coagulation rate, Gamma and exponent, delta showing anomalous dependence on NaCl concentration. The coagulation rate exhibited strong increase up to NaCl concentration of 50 mM, above this and up to 300 mM the coagulation rate was found to remain independent of NaCl concentration yielding non-DLVO behaviour. The same was true for delta which increased from 1.04+/-0.06 to 6.94+/-0.07 as NaCl concentration was raised from 0 to 50 mM. Above 50 mM it remained constant with delta=6.94+/-0.07. Results are discussed through Smoluchowski aggregation kinetics and theoretical construction of interparticle interaction potentials relevant to our problem.

Animals↗
PubMed1999

Laser light scattering immunoassay for malaria.

Laser light scattering immunoassay (LIA) was proposed as a prospective diagnostic method for the detection of antibody (or antigen) by monitoring the agglutination of antigen (or antibody) coated carrier particles using dynamic light scattering (DLS) as probe. LIA is a very sensitive assay as it can detect microscopic immune complexes even when antibody (or antigen) level is low. A sizeable number of human sera collected from malaria endemic areas and hospitals have been analysed by ELISA using Pf parasite lysate or a RESA derived synthetic peptide as antigen parallel to LIA using Pf antigen coated polystyrene latex beads. Comparative analysis of data suggests LIA to be as good as ELISA and possibly better in terms of sensitivity and simplicity. LIA can be a simple and inexpensive immunoassay suitable for field use and mass application.

Antigens, Protozoan↗
PubMed1998

Laser light scattering immunoassay: an improved data analysis by CONTIN method.

Laser light scattering immunoassay (LIA) is a diagnostic method for the detection of antibody by monitoring the agglutination of antigen carrier particles mediated by antibody, using dynamic light scattering (DLS) as probe. We have used this method for the detection of antibody to P. falciparum that cause malaria. The data were analysed using CONTIN method and the superiority of the distribution analysis over the conventional interpretation of the data in terms of mean diffusion coefficient or hydrodynamic radius is discussed in detail.

Agglutination↗
PubMed1998

Light scattering and viscosity study of heat aggregation of insulin.

Aggregation behavior and hydrodynamic parameters of insulin have been determined from static and dynamic light scattering experiments and intrinsic viscosity measurements carried out at pH 4.0, 7.5, and 9.0 in the temperature range 20-40 degrees C in aqueous solutions. The protein aggregated extensively at elevated temperatures in the acidic solutions. Intermolecular interactions were found to be attractive and to increase with temperature. The measured intrinsic viscosity [eta], diffusion coefficient D0, molecular weight M, and radius of gyration Rg exhibited the universal behavior: M[eta] = (2.4 +/- 02) x 10(-27) (Re, eta/Re, D)3(D0 eta 0/T)-3 and (D0 square root of n)-1 approximately equal to (square root of pi eta 0 xi beta/kBT) [1 + 0.201)(v/beta 3) square root of n], where n is the number of segments in the polypeptide. The effective hydrodynamic radii deduced from [eta], (Re, eta) and the same deduced from D0, (Re, D) showed a constant ratio, (Re, eta/Re, D = 1.1 +/- 0.1). Re, D/Rg = xi was found to be (0.76 +/- 0.07). From the known solvent viscosity eta 0, the segment length beta was deduced to be (10 +/- 1) A. The excluded volume was deduced to be (5 A)3 regardless of pH. The Flory-Huggins interaction parameter was found to be chi = 0.45 +/- 0.04, independent of pH and temperature.

Chemical Phenomena↗
PubMed1998

Hydrodynamic properties of gelatin in dilute solutions.

Aggregation properties of Gelatin chains in neutral aqueous solutions, are reported in the temperature range T = 35-60 degrees C, from the measured intrinsic viscosity [eta], diffusion coefficient, D(o), molecular weight Mw, and radius of gyration (Rg) data. Gelatin chains doubled their size as the solution was cooled to 35 degrees C from 60 degrees C. The intermolecular interaction was found to be repulsive which showed significant decrease as the temperature was reduced. The data provides excellent fitting to the scaling relations Mw[eta] = (1.96 +/- 0.06) x 10(-26)(Re,eta/Re,D)3(D(o) eta o/T)-3 and (D(o)n1/2)-1 approximately equal to (6 1/2 pie eta o chi beta/kB/T)[1 + 0.201(v/beta 3)n1/2] where n is the number of segments in the chain. The ratio of the hydrodynamic radius (Re,D) (deduced from D(o)) and Rg, (Re,D/Rg = zeta) was found to be 0.555. From the known solvent viscosity eta o, the segment length beta, was deduced to be (15 +/- 2) A. The deduced excluded volume was v approximately equal to (4.1 A)3. The Flory-Huggins interaction parameter (zeta) did not show observable temperature dependence.

Biopolymers↗
PubMed1991

Heat aggregation studies of phycobilisomes, ferritin, insulin, and immunoglobulin by dynamic light scattering.

Dynamic laser light scattering studies on the heat aggregation behavior of phycobilisomes (PBS), ferritin, insulin, and immunoglobulin (IgG) in dilute aqueous solutions has been reported. Except for PBS, results are reported for heat aggregation trends in these proteins for three different pH environments (4.0, 7.5, 9.1). For PBS, studies were performed only in the neutral buffer medium (pH 7.5). The experiments were performed in the very dilute concentration regime (between 0.23 and 1.8 gL-1). For all these samples heat aggregation and dissociation trends were found to be linear with temperature. Upon temperature reversal (self-cooling), hysteresis-like behavior observed in insulin was found to be predominantly large at pH 7.5. PBS, ferritin, and IgG showed no such behavior at any of three pH values, and retraced their path of aggregation while dissociating on temperature reversal. Heat aggregation and dissociation processes in ferritin were found to be independent of pH. The IgG samples showed smooth aggregation tendency only up to 35 degrees C in the buffer media pH 4.0 and 9.1, whereas for pH 7.0 the same could be observed until 60 degrees C. Low polydispersity in the correlation spectra was observed in case of all these samples.

Ferritins↗