Reduced Protein Intake Research Articles

Production of urea nitrogen and creatinine in chronic azotemia and effect of hemodialysis.

Summary1. The daily rate of urea nitrogen and creatinine production was determined in 7 patients with chronic stable azotemia and 3 normal subjects, maintained on a reduced protein intake. In addition, the effect of hemodialysis on urea nitrogen and creatinine production was observed in all the azo-temic patients. 2. In 7 cases predialysis urea nitrogen production was similar to that found in normal subjects and averaged 55% of the nitrogen intake. In 2 cases urea nitrogen production was elevated, being equal to or exceeding the dietary nitrogen. The rate of creatinine production in the azotemic patients was slightly lower than that found in normal subjects. 3. Postdialysis urea nitrogen production increased significantly in 5 cases whose predialysis PUN ranged from 42 to 73 mg%, and decreased in 4 cases with predialysis PUN of 87 to 192 mg%. Creatinine production decreased in all but one case.

Studies on metabolism of vitamin A. Absorption of retinal (vitamin A aldehyde) in rats.

1. Young rats with low reserves of vitamin A were dosed with retinal in groundnut oil, and the stomach, the contents, mucosa and muscles of small intestine, the blood and the liver were analysed at periods up to 24hr. after dosing. 2. Up to 6hr. after the dose, retinal was present in high concentrations in the contents, mucosa and muscles of the intestine. Small but significant amounts were present in blood and liver at all times. 3. The intestinal mucosa and muscles always contained small amounts of retinol and its esters. 4. A study of the distribution of the three forms of the vitamin within the mucosal cell showed that most of the mucosal retinal enters the cell unchanged. 5. When protein-depleted rats were similarly given retinal, the rate of reduction of the aldehyde, and the consequent deposition in the liver of retinol and its esters, progressively decreased with reduced protein intake.

EARLY ATTEMPTS AT REHABILITATION OF TERMINAL URAEMIC PATIENTS BY PERIODIC HAEMODIALYSIS.

SUMMARYEarly experiences with periodic hemodialysis in four patients with terminal renal failure are reported. Initial improvement was followed by mental deterioration, wasting and peripheral neuropathy. These poor results were attributed to inadequate hæmodialysis. Hypertension could not be controlled by hypotensive drugs alone. Prolonged rehabilitation can be achieved only by twice‐weekly hæmodialyses with rigid sodium and water restriction and a reduced protein intake.

On the Protein Requirement of Milk Production

Summary After allowing 0.6 pound apparently digestible crude protein (0.5 pound true protein) per 1000 pounds live weight for maintenance, an intake of crude protein equal to 1.25 times the milk protein of two weeks previous (true protein, 1.03 times the milk protein) caused a slight nitrogen loss with one cow, and a slight retention of nitrogen with the other. The intake, therefore, was close to the requirement. In the same experimental periods the total synthesized protein (milk protein plus positive or minus negative protein balances) was 0.85 to 0.90 of the amount of the crude protein available for increase (protein intake minus the maintenance requirement). It is recognized that this rate of efficiency of production of milk, in relation to the protein intake, applies less definitely to practice than to the conditions of these metabolism experiments. Reduction of the protein intake from the larger to the smaller amounts fed had the effect to reduce, the milk flow. Subsequent increase of protein intake caused a significant increase of milk production with the cow of more pronounced milk-giving tendency (no. 869), but no significant increase with the poorer cow (no. 884), while both cows responded to the increase of protein in the ration by considerable storage of nitrogen in the body. With a low protein intake the utilization of protein for milk production was more efficient than with an intake of protein sufficient to permit of more extensive use for fat and energy production. There is, with the cow, a prominent inclination to produce milk at an individual rate which is determined by inheritance. On account of the ability of the cow to deflect protein from energy production, and to withdraw protein from the tissues, and to use the same, in both cases, for milk production, the immediate effect of reduction of protein intake to reduce the production of milk is only partial in degree, the maximum effect being reached after a period which may extend to a number of weeks. The apparent digestibility of protein by the cow increases prominently with increase in the protein intake, this effect apparently being due to metabolic protein being more nearly a body constant than a variable related directly to the feed.