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.
Nutrition Research Center, Department of Physiology, St. John's Medical College, Bangalore 560034, India.
A V
AV
Kurpad
F
F
Jahoor
S
S
Borgonha
S
S
Poulo
S
S
Rekha
C R
CR
Fjeld
P J
PJ
Reeds
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