Authors:A. Janoki, J. Harwig, J. Slater, and W. Wolf
The effect of a carbodiimide on the gallium binding properties of desferrioxamine as a model for interpreting the low specific activity of gallium-labelled desferrioxamine-human serum albumin conjugate prepared using carbodiimide as the coupling reagent was studied. Desferrioxamine was treated with carbodiimide at various mole ratios and pH, before and after labeling with67Ga. Substantial loss of gallium binding capacity resulted when desferrioxamine was treated with carbodiimide prior to labeling, suggesting that the carbodiimide reacts with the hydroxamic acid groups of desferrioxamine and destroys their ability to bind gallium. No significant metal release occurred when desferrioxamine was labeled with gallium prior to carbodiimide treatment, indicating that the presence of the gallium protects the hydroxamic acid troups from the effects of carbodiimide. These results have important implications for preparing high-specific-activity radiopharmaceuticals using bifunctional chelation.
4-Iodoantipyrine was synthesised from phenazone, labeled with123I and administered to cells in culture. 4-[123I]iodoantipyrine carries the radionuclide across the cell membrane allowing one to study the biological effects of the very
short ranged Auger electrons emitted by this isotope. The formulation used to prepare this compound proves to be free of reagents
that may have an adverse effect on the mitotic activity of cells in culture. By observing micronuclei frequencies in human
lymphocytes and CHO-K1 cells the high-LET characteristics of Auger electrons could be demonstrated. Compared to extracellular
disintegrations from [123I]NaI and123I-human serum albumin, a substantial reduction in the variation in radiosensitivity of these cell types was noted when treated
with 4-[123I] iodoantipyrine.
A new technique for in vitro studies of biomacromolecules interactions, their adsorption at aqueous/organic liquid interfaces
and distribution in the bulk of liquid/liquid systems was developed. The method includes (1) tritium labeling of biomolecules
by tritium thermal activation method and (2) scintillation phase step with organic phase, which can be concerned as a model
of cellular membrane. Two globular proteins lysozyme and human serum albumin tested. We have determined the conditions of
tritium labeling when labeled by-products can be easy separated by means of dialysis and size-exclusion chromatography. Scintillation
phase experiments were conducted for three types of organic liquids. Thus, the influences of the nature of organic phase on
proteins adsorption and its distribution in the bulk of aqueous/organic liquid system were determined. It was found that proteins
possess high surface activity at aqueous/organic liquid interface. Furthermore, values of hydrophobicity of globular proteins
were found by the experiment.
Authors:C. Paik, D. Herman, W. Eckelman, and R. Reba
A new bifunctional chelating agent, N′-(p-diazoniumbenzyl)-N,N N″,N″-diethylenetri-aminetetraacetic acid (DTTA) was synthesized.
The compound as coupled to methyl p-hydroxybenzimidate and the resulting azoimidate was attached to lysine residues of monomeric
human serum albumin (HSA) via the amidination reaction. Blood clearnace of111In-labelled DTTA conjugated to HSA (AAHSA) in rabbits was biphasic. The first phase has a clearance indistinguishable from
that of125I-labeled HSA. During the second phase, the111In-labeled AAHSA was cleared more rapidly so that between 24 hours and 48 hours the percent of the injected dose of111In-labeled AAHSA in the blood was significantly lower than that of125I-labeled HSA. Highly conjugated111In-labeled AAHSA (0.9 DTTA/HSA) showed accelerated clearance at 24 and 48 hours compared to lightly conjugated protein (<0.9
DTTA/HSA). As a result we postulate that the level of conjugation is the critical parameter controlling the blood clearance.
The gel chromatography column scanning (GCS) method was used for the present radioanalytical study of99mTc labelled colloids and macromolecules. The sample to be analyzed was applied at the top of a column filled with gel to a
height of 300 mm. Gels investigated included Sephadex G 25, Sepharose 2B, 4B, 6B (Pharmacia Fine Chemicals, Uppsala, Sweden)
and BioGel A-150m (Bio Rad, Richmond, Cal., USA). Initially the gels were analyzed according to their chromatographic column
caracteristics both for99mTc pertechnetate and for colloids. A standardized technique was then used to compare colloids labelled in different ways with99mTc. The column was developed with 10.0 ml 0.9% NaCl solution. Thereafter the column, which still retains all the radioactivity,
was scanned with a slit collimated NaI(Tl)-crystal detector. The scanning profile gives information on the size distribution
of the labelled colloids and the presence of other99mTc-labelled species in the preparation. The above method has been used for comparative studies of various99mTc-sulfur colloids and99mTc−Sb-sulfur colloid (Philips-Duphar). Colloid formation has also been studied by electrolytically labelling human serum albumin.
Authors:Lee-Ann Briere, Jan-M. Brandt, and John Medley
Differential scanning calorimetry (DSC) was used to evaluate the thermal transitions associated with protein constituents
of synovial fluid samples from three individuals with osteoarthritis. Analysis of the multi-component DSC curves revealed
that major endothermic transitions of synovial fluid occur between 60 and 80 °C and can be resolved into three peaks, likely
due to the unfolding of human serum albumin and immunoglobulins, and that the enthalpies of these transitions can be quantified
in terms of their relative contribution to the total system enthalpy. DSC was also used to analyze a solution of bovine calf
serum, a lubricant used in simulator wear testing of joint replacement implants, and the resulting endothermic transitions
occurred in a temperature range relevant to that produced by frictional heat during such wear simulator testing. Results of
this study indicate a new application for DSC as a direct method for studying thermal stabilities of both bovine calf serum
and synovial fluid. The use of DSC is proposed as a diagnostic tool to detect altered thermal properties or protein concentrations
indicative of a diseased or injured state, and as a development tool to test the efficacy of additives in controlling protein
denaturation associated with increased wear in joint replacement implants.
Authors:B. Kupcsulik, B. Sevella, A. Ballagi, and J. Kozma
Ikegaya, K., Hirose, M., Ohmura, T. & Nokihara, K. (1997): Complete determination of disulfide forms of purified recombinant humanserumalbumin, secreted by the yeast Pichia pastoris . Anal. Chem. , 69 , 1986