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Biomedical subjects

D R Bangham

Publications and source records attributed to D R Bangham.

At least 37 records · Page 2Linked to original sources
PubMed1975

Stability of the 4th International Standard for Insulin.

The stability of the (W.H.O.) 4th International Standard for Insulin, has been assessed by accelerated thermal degradation studies. This is a crystalline preparation of insulin, freed from proteolytic enzymes, sealed in ampoules containing air and with a moisture content of 5--6%. Of the original biological activity 95.8 (92.8--98.9;P = 0.95)% was retained after storage for 12 years in the dark at 20 degrees C and 65.7 (63.4--68.1;P = 0.95)% after 14 years at 37 degrees C. Degradation rate constants were calculated from these data for the Standard at 20 degrees C and 37 degrees C, assuming first order kinetics. The degradation constant at 37 degrees C did not differ significantly from those found in earlier degradation studies at 37 degrees C over shorter periods, thereby supporting the assumption that the degradation of crystalline insulin, at least at 37 degrees C, is a first order reaction. Extrapolation of these data suggest that the Standard stored at -20 degrees C for 20 years would have retained at least 99.93% (P = 0.95) of its original activity and so for practical purposes can be considered to be stable.

Animals↗
PubMed1971

Stability of prothrombin and factor VII in freeze-dried plasma.

The stability of prothrombin and factor VII was studied using accelerated degradation tests in three preparations of freeze-dried pooled normal plasmas. In a previous report (Brozović, Gurd, Robertson, and Bangham, 1971) factor X was shown to be relatively unstable in these preparations of freeze-dried plasma: it was calculated that up to 8% of the original factor X activity would be lost after 10 years at -20 degrees C, up to 54% at 4 degrees C, and up to 90% at room temperature. The losses of factor VII activity were estimated to be negligible at -20 degrees C, between 2 and 18% at 4 degrees C, and between 20 and 70% of the original activity at 20 degrees C, after 10 years of storage. Prothrombin was found to be less stable than factor VII: the expected loss in 10 years at -20 degrees C may be up to 4%, at 4 degrees C up to 30%, and at 20 degrees C up to 83% of the initial activity. These findings indicate that in freeze-dried plasma prothrombin as well as factor X may be insufficiently stable for plasma to serve as long-term reference material for the standardization of the one-stage prothrombin time. Moreover, the loss of prothrombin and factor X in freeze-dried plasma stored at 4 degrees C may be so high that when it is required to preserve these factors it may be necessary to store freeze-dried plasma at lower temperatures.

Cold Temperature↗