Abstract: A sensitive gel-diffusion assay for determination of phospholipase A was developed. PLA standards, serum, faecal and pancreas homogenate samples with PLA-activity were allowed to diffuse from wells into agar-gels containing lecithin-membranes. The turbidity cleared radially upon PLA-activity. The diameters of the cleared zones showed a linear relationship with the log of the enzyme concentration. Serum samples resulted in some turbidity within the cleared zones. This interference originating from serum lipoproteins could be abolished by hydrophobic absorption. The gel-diffusion method was compared with two other methods for PLA, titrimetric and radiometric techniques. Analysis on 37 human patients with acute pancreatitis showed close interrelationship between these methods. The phospholipase A activity in sera from man, the dog, the horse, the cow, the pig and the cat were almost equal, but much less than in the albino rat. No significant differences between PLA activities in pancreatic samples were obtained in different animal species. Of the faecal samples, the cow had the lowest PLA activity. Dogs suffering from pancreatic degenerative atrophy (PDA), had significantly reduced PLA activity both in their pancreas and faeces but not in serum. En känslig gel-diffusionsmetod för bestämning av fosfolipas A (PLA) utvecklades. PLA standards, serum, feces- och pancreashomogenat med PLA-aktivitet fick diffundera från fördjupningar i agargeler innehällande lecitinmembraner. Som en följd av PLA-aktivitet skedde en cirkulär uppklaring av gelen. Diametrarna av de uppklarade zonerna stod i lineärt förhållande til logaritmen av enzymkoncentrationen. Serumprov resulterade i en vis grumlighet inom de uppklarade zonerna. Denna störning, som antagligen beror på lipoproteiner i serum, kunde avhjälpes med hydrofobisk absorption. Geldiffusionsmetoden jämfördes med två andra metoder för PLA, en titrimetrisk och en radiometrisk teknik. Analys av 37 humanpatienter med akut pancreatit visade en nära samstämmighet med dessa metoder. Fosfolipas A-aktiviteten i sera från människa, hund, hast, not, svin och katt var nästan lika, men mycket lägre an hos albinoråtta. Inga signifikanta skillnader mellan PLA-aktiviteterna i pancreasprov från olika djurslag kunde konstateras. Bland de fecala provena hade nöt den lägsta PLA-aktiviteten. Hundar med degenerativ pancreasatrofi (PDA), hade signifikant sänkt PLA-aktivitet både i pancreas och feces, men inte i serum.
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This research outlines the development of a new gel-diffusion assay method for the detection and quantitation of the enzyme phospholipase A (PLA). The method was tested on various samples from humans and animals, and its results were found to correlate with those of traditional methods. The enzyme activity varied across different species and sample types.
Developing the Gel-Diffusion Assay for PLA
The researchers created a sensitive gel-diffusion assay, a type of experiment that allows substances to diffuse, or spread, through a gel for analysis.
In this case, the substances being tested were PLA standards, serum samples, faecal samples, and pancreas homogenate samples, all of which had PLA-activity.
These samples were allowed to diffuse into agar-gels with lecithin membranes, triggering an observable reaction in the presence of PLA.
The clearing of the gel’s turbidity, or cloudiness, was directly related to the presence and activity of PLA.
The researchers noted a linear relationship between the diameters of the cleared zones in the gel and the logarithm of the enzyme concentration, a measure of the amount of PLA present.
Overcoming the Interference from Lipoproteins in Serum
One of the challenges encountered was the interference caused by serum lipoproteins, which caused some turbidity within the cleared zones.
To negate this interference, the researchers carried out hydrophobic absorption, a process that removes interfering components based on their water-fearing (hydrophobic) properties.
Comparison with Other PLA Detection Methods
The novel gel-diffusion method was compared with two existing PLA detection methods: titrimetric and radiometric techniques.
Using samples from 37 human patients with acute pancreatitis, the researchers confirmed that their new method showed a close interrelationship, or correlation, with the other two methods.
PLA Activity Across Different Species
The researchers compared PLA activity across various species, noting that the sera from humans, dogs, horses, cows, pigs, and cats showed similar levels of activity.
The albino rat presented significantly higher PLA serum activity compared to the other species.
The PLA activity in pancreatic samples was quite similar across species, while faecal samples varied with the cow showing the lowest PLA activity.
Dogs suffering from pancreatic degenerative atrophy showed significantly reduced PLA activity in pancreas and faeces, but not in their serum.
Cite This Article
APA
Westermarck E, Lindberg LA, Sandholm M.
(1984).
Quantitation of serum phospholipase A2 by enzyme-diffusion in lecithin agar gels. A comparative study in man and animals.
Acta Vet Scand, 25(2), 229-241.
https://doi.org/10.1186/BF03547267
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