A minimally invasive tracer protocol is effective for assessing the response of leucine kinetics and oxidation to vaccination in chronically energy-deficient adult males and children.
In disadvantaged populations, recurrent infections lead to a loss of body nitrogen and worsen nutritional status. The resulting malnutrition, in its turn, produces a greater susceptibility to infection. This study aimed to examine the ability of a new minimally invasive tracer protocol to measure leucine oxidation, and then to use it to quantify the effect of vaccination on leucine kinetics and oxidation. Undernourished men (n = 5; body mass index 16.3 +/- 0.9 kg/m(2)) and children (n = 9; age 4.1 +/- 0.6 y; weight-for-age Z-score -2.3 +/- 0.7) underwent metabolic studies 6 d before and 1 d after vaccination with diphtheria, pertussis and tetanus (DPT). The tracer protocol was performed in the fed state and involved two 3-h sequential periods of frequent (20 min) oral doses of NaH(13)CO(3) or [1-(13)C] leucine. Frequent breath samples and urine collections were made. Blood samples were obtained from the men and used for the determination of the isotopic enrichment of alpha-ketoisocaproic acid. The prevaccination oxidation of leucine (percentage of dose +/- SD) was 18.1 +/- 2.3 (men) and 16.7 +/- 3.8 (children). One day after vaccination, these values had risen to 19. 9 +/- 1.9 (P < 0.05) in the men and to 19.5 +/- 4.6 (P < 0.01) in the children. In the adults, vaccination was associated with a rise in whole-body protein breakdown [mg protein/(kg.h)] from 200 +/- 40 to 240 +/- 10 (P < 0.05). A minor simulated infection increases leucine catabolism in undernourished humans and this new, minimally invasive protocol is sufficiently sensitive to measure these changes.
Kurpad
A V
AV
Nutrition Research Center, Department of Physiology, St. John's Medical College, Bangalore 560034, India.
Jahoor
F
F
Borgonha
S
S
Poulo
S
S
Rekha
S
S
Fjeld
C R
CR
Reeds
P J
PJ
D000293:Adolescent; D000328:Adult; D000886:Anthropometry; D001944:Breath Tests; D002247:Carbon Isotopes; D002675:Child, Preschool; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007194:India; D007553:Isotope Labeling / Q000379:methods*; D007651:Keto Acids / Q000097:blood; D007930:Leucine / Q000378:metabolism* / Q000493:pharmacokinetics; D008297:Male; D009752:Nutritional Status; D010084:Oxidation-Reduction / Q000187:drug effects; D011502:Protein-Energy Malnutrition / Q000378:metabolism*; D017693:Sodium Bicarbonate / Q000378:metabolism
D002247:Carbon Isotopes; D015721:Diphtheria-Tetanus-Pertussis Vaccine; D007651:Keto Acids; C013082:alpha-ketoisocaproic acid; D017693:Sodium Bicarbonate; D007930:Leucine