When blood plasma proteins are depleted by bleeding, with return of washed red cells (plasmapheresis), it is possible to bring dogs to a steady state of low plasma protein in the circulation and a uniform plasma protein production on a basal diet. Such dogs become test subjects by which the effect of various factors on plasma protein regeneration can be measured.

Dogs previously the subjects of plasmapheresis, during long rest periods appear to increase their stores of plasma protein building materials and their blood plasma protein concentrations above former normal levels.

A sterile abscess (turpentine) induces a marked reduction in plasma protein regeneration in these test dogs consuming an ample basal diet. The sharp reduction during the initial 24 hours may in part reflect an extravasation of plasma protein into the injured tissue but there also appears to develop a true disturbance of the mechanism which produces plasma proteins.

Digestive disturbances interfere seriously with plasma protein production. Whereas large quantities of live yeast upset digestion and form no plasma protein, autoclaved yeast is well utilized, having a potency ratio of 4.4.

Amino acids have been tested inadequately. A mixture of cystine, glutamic acid, and glycine does seem to have a definite effect upon protein metabolism and plasma protein production.

Iron, under the conditions of these experiments, does not influence the output of plasma proteins. Liver extract (parenteral) is also inert.

The proteins of red blood cells when added to the diet are poorly utilized for plasma protein formation and show a potency ratio of only 10.1.

Kidney protein added to the kidney basal diet shows a potency ratio of about 5 as compared with 4.6 for that basal diet.

A digest of beef stomach and rice polishings shows a potency ratio of about 7.9. Dried powdered serum shows a potency ratio of 3.5, which is much less than fresh serum (2.6).

Powdered thyroid fed in doses sufficient to accelerate body metabolism shows no distinct effect upon plasma protein production not attributable to the protein in the thyroid powder itself.

Long periods (25 to 30 weeks) of plasma depletion and basal diet intake remove much protein from body fluids and tissues. Associated with this protein depletion the dog loses its appetite and may vomit some food. There is loss of hair, a tendency to skin ulceration, and a distinct lowering of resistance to infection. The plasma protein output may fall to fasting levels in spite of food intake sufficient to maintain weight. We believe this condition to be a deficiency state related to severe depletion of the essential protein matrix of the body cells.

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