Intermediary metabolites and adenine nucleotides in leucocytes of children with protein-calorie malnutrition

Energy production, intracellular amino acid pools, and protein synthesis in chronic renal disease

Intracellular glycolytic regulating enzyme activities, pyruvate kinase (PK) and phosphofructokinase (PFK), adenylate kinase (AK), energy charge (Ech), free amino acids (ICAA), and protein synthesis (PS) were measured in polymorphonuclear leukocytes--used as a cell model--in 62 adults and 12 children with chronic renal failure, and 66 normal adults and 21 children as comparison controls. In normal subjects, children had significantly lower enzyme activities and cell amino acid levels but similar Ech and higher PS than adults. ICAA concentrations were significantly higher than plasma amino acid concentrations (PAA) in both groups, and the PAA were not correlated with, nor indicative of, the ICAA concentrations. The variance (R2) in PS could be largely accounted for by a combination ("set") of six ICAA, as determined by multivariate analysis. The sets differed in children vs adults, suggesting that different proteins were being synthesized. In the uremic patients, reduced PF, PFK, Ech, most ICAAs and PS were indicative of cellular malnutrition. For the uremic adults, the abnormalities in cell metabolism were modified by therapy--nondialyzed uremics being worst, CAPD patients best and approximately normal, and hemodialyzed intermediate. The uremic CAPD children had reduced, PK, PFK, AK, most ICAA, and PS. Ech was increased. Cellular malnutrition in children with chronic renal failure may contribute to their poor growth.

Malnutrition at the cellular level in uremia: a new frontier for research

Previously reported studies showed that protein-calorie malnutrition (PCM) in children is associated with significant alterations in muscle cell composition, characterized by increased cell water and Na, with decreased concentrations of K, Mg, and some glycolytic and citric acid cycle metabolites. In PCM, the i.c. H2O and levels of Na and K were significantly related, by multiple regression analysis, to the combined set of simultaneously measured levels of cell metabolites, phosphoenolpyruvate, pyruvate, alpha-ketoglutarate, and oxaloacetate. Cell bioactivities also were affected by PCM. Activities of the enzymes pyruvate kinase and malic and isocitric dehydrogenases were significantly reduced in muscle homogenates of PCM children. Kinetic analysis of pyruvate kinase indicated an 8-10-fold reduction in maximal velocity of the enzyme, consistent with a reduction in enzyme protein. Additionally, reduced levels of ATP and the equilibrium constant of the adenylate kinase system were observed in leukocytes of PCM children. Alterations in the activity of the energy-dependent Na pump have been noted by others in association with the accumulation of i.c. Na in severe malnutrition. Neither protein synthesis nor amino acid pools was measured in these previously reported studies. Recent data from several laboratories show that the "profiles" of i.c. and plasma amino acids are very different, both in uremics and in control subjects. In control subjects, with leukocytes as the cell model, the level of protein synthesis can be predicted by multiple regression analyses from simultaneously measured levels of plasma or i.c. amino acids. Intracellular amino acids are better predictors. Of 19 intracellular amino acids, a combination of five accounted for 54% of the variance in protein synthesis in normal, healthy adults. Levels of these predictor cell amino acids can, in turn, be predicted by different combinations of apparently unrelated plasma amino acids. In adult uremic patients stabilized by hemodialysis, with leukocytes as the cell model, levels of ATP, energy charge, adenylate kinase and pyruvic kinase activities were reduced. Others have reported increased i.c. water and Na contents, and impaired Na pump activity. Cell levels of methionine and the branched-chain amino acids, valine, leucine, and isoleucine, and protein synthesis also were significantly reduced. By multiple regression analysis, the observed levels of protein synthesis and energy charge in the hemodialyzed uremic patients were largely accounted for by different combinations of intracellular amino acid than in healthy subjects.(ABSTRACT TRUNCATED AT 400 WORDS)

Phagocytic activity of polymorphonuclear leucocytes in burns

The phagocytic function of neutrophils has been studied in 50 Egyptians of both sexes and of various ages, suffering from burns of different depths and extents, and the results compared with data from 50 normal persons of similar sex and age. The nitro blue tetrazolium test (Gifford and Malawista, 1970), and the bacterial killing test (Quie et al., 1967), have been used during the first 24 hours, and then repeated at weekly intervals for 4 weeks. The phagocytic power showed no change during the study except in two patients with extensive burns during fatal septicaemia. The bactericidal capacity, and the formazan cell formation showed similar changes with a steady decrease from the first to the third weeks, followed by a rise during the fourth week. Similar changes were noticed in the serum albumin levels. The decline was more marked in burns of more than 50 per cent of the body surface area and during severe sepsis. Improvement coincided with healing.

The effects of malnutrition on secretory and cellular immune processes

About 15 million children under 5 years of age die each year due to suppressed immunity and the resulting increased infection. In severely malnourished children and animals some immune systems such as T-cell function, secretory IgA and complement are significantly suppressed. Other systems, such as the serum IgG or IgA, are normal or even elevated. Some of these changes are apparently caused by nutritional stress while others may be due to stimulation by increased incidence of infection and antigen load. On the other hand, marginal malnutrition stimulates increased phagocytosis and T-cell function with increased immunity to cancer but decreased resistance to certain microbial agents. The mechanisms of immune suppression by malnutrition, persistence of these effects after renutrition, and the effect of maternal malnutrition on newborn immunity are critically reviewed. Possible non-nutritional means of rapid immunological restoration of malnourished children are described.

Death during recovery from severe malnutrition and its possible relationship to sodium pump activity in the leucocyte

The leucocyte data on four malnourished children who died suddenly when high-energy feeding was started were retrospectively analysed. The pretreatment rate constant for sodium efflux in leucocytes was higher and the intracellular sodium concentration lower in this group than in 13 malnourished children who recovered uneventfully with feeding. Two other children with unusual leucocyte electrolyte values and sodium pump activity were identified and closely monitored when high-energy treatment was begun. They rapidly developed the syndrome of extracellular fluid overload but were successfully treated with diuretics and digoxin. Though the precise relation between the findings in the leucocytes and the development of this overload syndrome is not clear, the pretreatment leucocyte values are nevertheless valuable in predicting which malnourished children are at risk of sudden death when refeeding is started.