PubMed · 6181236
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H J Dworkin. 1982. Potential for lymphoscintigraphy.. https://pubmed.ncbi.nlm.nih.gov/6181236/
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Recently, branching sucrases encoded in the genomes of certain Lactic Acid Bacteria (LAB) strains have become novel enzymes to obtain branched α-glucans. In this study an active α-(1 → 2) branching sucrase from Apilactobacillus kunkeei PDER37 was expressed, characterised and distinct branched dextrans was obtained with reactions under different sucrose: dextran ratio. Structural characterisation by 1H and 13C NMR analysis demonstrated the branching of the dextran with (1 → 2)-linked α-d-glucose units with no alteration in the final structure depending on sucrose: dextran ratio (D0) but this ratio was effective for the determination of the molecular weights of the branched dextrans (D1, D2 and D3). FTIR analysis further supported the dextran structures and suggested the higher accumulation of the α-Glc units in the branched dextrans. Thermal characterisation of the branched dextrans obtained by TGA and DSC analysis suggested the increased hygroscopicity of the branching units. Both SEM and AFM analysis demonstrated more porous chain like structures in the branched dextrans. This study provides valuable information on the role of active α-(1 → 2) branching sucrase (BS37) for the production of branched dextrans with potential increased physicochemical status applicable for food and other industries.
Cross-linking of fibrinogen at its COOH-terminal gamma chain cross-linking site occurs in the presence of factor XIIIa due to self-association at a constitutive D domain site ("gammaXL"). We investigated the contribution of COOH-terminal regions of fibrinogen Aalpha chains to the gammaXL site by comparing the gamma chain cross-linking rate of intact fibrinogen (fraction I-2) with that of plasma fraction I-9, plasmic fraction I-9D, and plasmic fragment D1, which lack COOH-terminal Aalpha chain regions comprising approximately 100, approximately 390, and 413 residues, respectively. The cross-linking rates were I-2 > I-9 > 1-9D = D1, and indicated that the terminal 100 or more Aalpha chain residues enhance gammaXL site association. Fibrinogen Dusart, whose structural abnormality is in the COOH-terminal "alphaC" region of its Aalpha chain (Aalpha R554C-albumin), is associated with thrombophilia ("Dusart Syndrome"), and is characterized functionally by defective fibrin polymerization and clot structure, and reduced plasminogen binding and tPA-induced fibrinolysis. In the presence of XIIIa, the Dusart fibrinogen gamma chain cross-linking rate was about twice that of normal, but was normalized in proteolytic fibrinogen derivatives lacking the Aalpha chain abnormality, as was reduced plasminogen binding. Electron microscopy showed that albumin-bound Dusart fibrinogen "alphaC" regions were located in the vicinity of D domains, rather than at their expected tethered location near the fibrinogen E domain. In addition, there was considerable fibrinogen aggregation that was attributable to increased intermolecular COOH-terminal Aalpha chain associations promoted by untethered Dusart fibrinogen aC domains. We conclude that enhanced Dusart fibrinogen self-assembly is mediated through its abnormal alphaC domains, leads to increased gammaXL self-association and gamma chain cross-linking potential, and contributes to the thrombophilia that characterizes the "Dusart Syndrome."
BACKGROUND: Although urea clearance is often increased during high-efficiency and high-flux haemodialysis to compensate for short treatment times, the impact of these treatment modalities on the removal of larger uraemic toxins has not been thoroughly investigated. METHODS: We compared solute removal rates for five haemodialysis treatment strategies in vitro using neutral dextrans (molecular radii between 15 and 50 A) as marker macromolecules. Removal rates were assessed by the decrease in dextran concentration within the reservoir of a model circuit using outdated human plasma as the test solution. Results for high-efficiency haemodialysis (CA110 dialyser at a blood flow rate of 400 ml/min and TAF175 dialyser at a blood flow rate of 300 ml/min) and high-flux haemodialysis (CT190G dialyser at a blood flow rate of 300 ml/min and F60 dialyser at a blood flow rate of 300 ml/min) were compared with those for conventional haemodialysis (CA110 dialyser at a blood flow rate of 200 ml/min). RESULTS: Dextran clearances were dependent on the dialyser employed, and they decreased with molecular size and time for each treatment strategy. Removal rates were greatest using the CT190G and F60 dialysers, intermediate for the TAF175 dialyser, and lowest for the CA110 dialyser at either blood flow rate. CONCLUSION: The results of this study demonstrate that increasing blood flow rates alone to increase urea clearance may not provide adequate removal of high-molecular-weight solutes. The use of high-flux or large surface area, high-efficiency dialysers are more effective in maintaining the removal of high-molecular-weight solutes when treatment time is shortened.