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Biomedical subjects

D G EVANS

Publications and source records attributed to D G EVANS.

At least 19 recordsLinked to original sources
PubMed1963

FIFTH INTERNATIONAL STANDARD FOR GAS-GANGRENE ANTITOXIN (PERFRINGENS) (CLOSTRIDIUM WELCHII TYPE A ANTITOXIN).

The Fifth International Standard Gas-Gangrene Antitoxin (Perfringens) (Clostridium welchii Type A Antitoxin) was prepared from serum from immunized horses. It was freeze-dried in ampoules each containing 1 ml.Seven laboratories collaborated in assaying its potency in terms of the Fourth International Standard by the intravenous inoculation of mice. The geometric mean value, taking the results of all the laboratories, was 270 International Units per ampoule and the maximum variation between laboratories was 15%.In vitro (lecithinase) tests were also done by three laboratories, giving an average of 261 International Units per ampoule.The dry weight contents of ampoules, determined in three laboratories, varied by less than 3%, with an average of 90.35 mg per ampoule.The standard was stable for 120 hours at 56 degrees C.Each ampoule of the Fifth International Standard for Gas-Gangrene Antitoxin (Perfringens) contains 270 International Units, and one International Unit is contained in 0.3346 mg of the International Standard.

Animals↗
PubMed1962

An international collaborative study of the assay of the potency of poliomyelitis sera.

As a first step towards the standardization of poliomyelitis vaccine, the neutralizing antibody titres of ten test antipoliomyelitis sera were measured in nine laboratories in different countries in comparison with a reference preparation. A standard neutralization test was not used by all laboratories and in general those neutralizing the serum-virus mixtures at a temperature of 37 degrees C obtained higher titres than those laboratories using lower temperatures. When the potencies of the test sera were calculated, in terms of the reference preparation, there was good agreement by all laboratories with sera of similar neutralizing capacity. The reference sera used in this study have proved useful for obtaining relative potencies for poliomyelitis sera of different neutralizing capacity and of different origin. These potencies have been shown to vary much less from one laboratory to another than did the uncorrected titres.For technical reasons, these reference preparations are not considered ideal for international standard preparations, and new sera have been prepared for this purpose.

Biological Assay↗
PubMed1960

A test of pancreatic function in man based on the analysis of duodenal contents after administration of secretin and pancreozymin.

Pancreozymin in man as in animals appears to act as a specific enzyme stimulant. The preparations of pancreozymin used in these experiments also contain cholecystokinin, which causes the gall bladder to contract, and a smooth muscle stimulant, possibly substance P. The duodenal contents obtained in response to a standard dose of secretin and pancreozymin have been collected quantitatively in man and the volume and amount of bicarbonate, amylase, trypsin, and lipase measured in order to study pancreatic function. The results of 105 tests undertaken on a normal group, in pancreatic and biliary disease, and in non-pancreatic steatorrhoea have been analysed. In localized pancreatic lesions and after recovery from acute pancreatitis, normal function is often retained. Mild functional impairment may be demonstrated only by a poor enzyme output in the post-pancreozymin fractions, while at a later stage bicarbonate output is affected and finally the volume of the duodenal contents is reduced. The secretin-pancreozymin test is most valuable, therefore, in the more chronic and advanced forms of pancreatic disease in which it gives a good assessment of residual pancreatic function. In diagnosis care must be taken in interpreting a functional test in terms of anatomical pathology. The test has proved useful not only in diagnosis but also as a guide to treatment and an index of prognosis.

Amylases↗