Search PubMed⌕ Search

Biomedical subjects

D R Bangham

Publications and source records attributed to D R Bangham.

49 records · Page 3Linked to original sources
PubMed1971

A biological standard for measurement of blood coagulation Factor VIII activity.

Because of the instability of Factor VIII (antihaemophilic factor) in plasma in vitro, and since evidence has accumulated that the level of activity varies significantly between samples of "fresh normal plasma", it is apparent that a stable biological standard is required.Two freeze-dried preparations of Factor VIII, one plasma and one concentrate preparation, were prepared and have been assayed in a collaborative trial by 20 laboratories in 9 countries.The laboratories used their own methods and altogether 248 assays were carried out. Comparison of materials of similar type gave precise estimates with all the methods used, but when materials dissimilar in type and in Factor VIII content were compared less precise results were obtained. Sources of variation, such as differences in method, differences between operators, and day-to-day variations, were analysed.Accelerated degradation tests, carried out on the freeze-dried plasma and concentrate preparations, showed that Factor VIII activity was sufficiently stable in the concentrate for it to be used as a long-term standard but that the Factor VIII activity was less stable in the plasma preparation.

Biological Assay↗
PubMed1970

A collaborative study of heparins from different sources.

Until about 10 years ago heparin was prepared from ox lungs and was regarded as a homogeneous polymer (of a sulfated mucopolysaccharide) with a relatively constant biological activity of about 100 IU/mg. The mucus and mucosa of the intestine of hog, sheep and ox have now become the main industrial source of bulk starting material. Preparations from this new source have much higher specific biological activity and have been shown to consist of mixtures of components with a number of different chemical and physical characteristics. It had been variously reported that preparations of heparins from the 2 sources gave significantly different estimates when bioassayed by the 2 different pharmacopoeial assay methods which are in wide use. If this is in fact the case these discrepancies could cause trouble in commerce, national control and clinical usage.This paper describes an international collaborative study to investigate this and other problems in the assay of heparin. In this study preparations of heparin made from the intestinal mucosa of each of 3 species (hog, sheep and ox) were biossayed with the International Standard for Heparin (from ox lung) established in 1958. Two of these preparations were national standards.The results showed differences between the estimated relative potencies of heparins of lung and mucosal origin, but they were not so consistent as to necessitate a separate international standard for each, although the imprecision of the assays may have concealed significant heterogeneity arising from real differences between the preparations. A further problem brought to light in this study was that, with the 2 pharmacopoeial assay methods in wide use, simple replicate assays using the same substrate gave estimates so precise that an analysis of variance on them was meaningless, whereas estimates between laboratories or with different substrate batches could vary by as much as 40%-50%.It is suggested that estimates of the biological activity of heparin preparations should be based on several independent assays using different batches of substrate.The biological assay methods currently used were devised some 15-20 years ago and, in the light of modern knowledge of mechanisms of blood clotting, are regarded as unsatisfactory in a number of respects. It is hoped that research into the mechanism of action of heparin will lead to improved methods of assay.

Animals↗
PubMed1967

The International Standard for anti-Rh (anti-D) Incomplete Blood-Typing Serum.

Some time ago the WHO Expert Committee on Biological Standardization asked the National Institute for Medical Research, London, to consult with the WHO International Blood Group Reference Laboratory concerning the establishment of an international standard for albumin-potentiated anti-Rh(o) (anti-D) blood-typing serum. This paper describes the collection and testing of sera, the removal of unwanted antibodies, the pooling of the sera and the distribution in equal amounts in 3350 ampoules, which were subsequently freeze-dried. The titres were determined by 29 laboratories in 21 countries by means of four methods-suspension in albumin, replacement with albumin, enzyme (papain) treatment and the anti-human-globulin test. On the basis of the results obtained, the material has been established as the International Standard for Anti-Rh(o) (Anti-D) Incomplete Blood-Typing Serum and the International Unit has been defined, with the agreement of the participants in the collaborative study, as the activity contained in 0.95 mg of the International Standard for Anti-Rh(o) (Anti-D) Incomplete Blood-Typing Serum.

Blood Group Antigens↗
PubMed1966

The international reference preparation of erythropoietin.

The WHO Expert Committee on Biological Standardization authorized the National Institute for Medical Research to establish an International Reference Preparation of Erythropoietin on the basis of the results of an international collaborative assay and to define an international unit with the agreement of the participants.The material investigated was a research standard (Erythropoietin Standard B) that had been in widespread use for some time. The preparation of this material and the estimation of its potency in terms of an earlier research standard (Erythropoietin Standard A) are described. By comparisons with other preparations of erythropoietin, it was found that Erythropoietin Standard B is a suitable standard for the bioassay of many preparations of erythropoietin in current use.On the basis of the information obtained, Erythropoietin Standard B has been established as the International Reference Preparation of Erythropoietin and the International Unit for Erythropoietin has been defined as the activity contained in 1.48 mg of the International Reference Preparation. This amount has equivalent biological activity to the unit of Erythropoietin Standard A and Standard B and thus ensures the continuity of the units already in widespread use.

Animals↗
PubMed1966

The second international standard for serum gonadotrophin.

In 1961 the WHO Expert Committee on Biological Standardization asked the National Institute for Medical Research, London, to collect and study material to replace the first International Standard for Serum Gonadotrophin, stocks of which were running low. This paper describes the material that was contributed, its distribution into ampoules and the international collaborative assay to compare its biological activity with that of the first International Standard. On the basis of the results obtained the material has been established as the second International Standard for Serum Gonadotrophin, with a potency of 1600 International Units per ampoule. The International Unit for Serum Gonadotrophin is thus defined as the activity contained in 0.003569 mg of the second International Standard for Serum Gonadotrophin.

Animals↗
PubMed1965

The international standard for streptokinase-streptodornase.

The National Institute for Medical Research, London, was asked by the WHO Expert Committee on Biological Standardization to take steps to set up an international standard of streptokinase-streptodornase. This paper describes the nature and handling of the material and its establishment as the International Standard for Streptokinase-Streptodornase, with a defined potency of 3100 International Units of Streptokinase and 2400 International Units of Streptodornase per ampoule. The International Unit of Streptokinase is defined as the activity contained in 0.002090 mg of the International Standard for Streptokinase-Streptodornase. The International Unit of Streptodornase is defined as the activity contained in 0.002700 mg of the International Standard for Streptokinase-Streptodornase.

Biological Assay↗