Threonine and Methionine Are Limiting Amino Acids for Protein Synthesis in Patients with AIDS

Abstract

This study was conducted to identify the most rate-limiting amino acids for whole-body protein synthesis in acquired immunodeficiency syndrome (AIDS) patients. We postulated that an essential amino acid that would be rate limiting in AIDS should have a low basal plasma concentration and should remain at a low level during amino acid infusion. Seven male AIDS patients (median age 37 y, CD4 cell count: 76 mm-3) without any clinically active opportunistic infection during the month before the experiment were infused intravenously with a complete amino acid-glucose mixture for 2.5 h. Eight healthy volunteers were used as controls. Before the infusion, the concentrations of most free essential amino acids (methionine, threonine, histidine, isoleucine, leucine and tryptophan) were significantly lower (P < 0.05) in AIDS patients than in controls. Most plasma free essential amino acids increased significantly during infusion. However, the absolute increase above basal levels for threonine, valine, lysine, (P < 0.05) and methionine (P < 0.073) was smaller in AIDS patients than in control subjects. Thus, threonine and possibly methionine may be rate limiting for whole-body protein synthesis in AIDS patients, suggesting that there are selective amino acid requirements in patients with AIDS.

Effect of medroxyprogesterone acetate on the efficiency of an oral protein-rich nutritional support in HIV-infected patients

“…Plasma cholesterol (4.52 ± 0.54 mmol·L ) were at normal levels and did not differ from those previously found in AIDS patients without opportunistic infection [12]. By contrast, all patients in the present study had high triglyceride levels (2.67 ± 0.89 mmol·L -1 ).…”

“…Because shortterm parenteral alimentation enriched with amino acids is capable of reversing the net protein catabolism [10,11], we hypothesize that some specific amino acid deficiencies may limit the utilization of other nutrients. Accordingly, we previously demonstrated that threonine and possibly methionine may be rate-limiting for whole body protein synthesis in HIV-infected patients [12].…”

“…The response of blood free amino acids to acute intravenous infusion of a glucose-amino acid mixture was used as an indicator of amino acid utilization [12]. We assumed that during infusion, the inhibition of protein synthesis and anabolism due to limiting amino acids would be suppressed; as a result, more amino acids would have been incorporated into body proteins.…”

Responses in whole-body amino acid kinetics to an acute, sub-clinical endotoxin challenge in lambs

“…For example, practical and theoretical arguments have been presented for additional arginine in cardiovascular and pulmonary disorders (7)(8)(9)(10) , for cysteine (11) , leucine (12) and threonine (13) in sepsis, for glutamine in endotoxaemia (10) , and for phenylalanine to support acutephase protein synthesis (14) . In other situations, combinations of AA have been proposed (10,15,16) . Obviously different stages of injury, infection or recovery may require differences in the combinations and absolute quantities of AA.…”

Lysine and threonine plasma concentrations in Ivorian patients living with human immunodeficiency virus

“…The plasma threonine deficiency observed in 17% of HIV positive patients and the female control population could be due to activation of threonine catabolism and/or synthesis of threonine-rich proteins (Laurichesse et al, 1998). Due to the high threonine concentration in immunoglobulins, threonine deficiency may affect the production of immunoglobulins (Richard and Galanaud, 1995).…”