Kurpad Anura V, Anand Pauline, Dwarkanath Pratibha, Hsu Jean W, Thomas Tinku, Devi Sarita, Thomas Annamma, Mhaskar Rita, Jahoor Farook
Division of Nutrition, St. John's Research Institute, St. John's National Academy of Health Sciences, Bangalore, Karnataka 560034, India.
USDA/Agricultural Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
Clin Nutr. 2014 Feb;33(1):122-9. doi: 10.1016/j.clnu.2012.12.016. Epub 2013 Jan 11.
BACKGROUND & AIMS: There is evidence from a study of pregnant American women that methionine transmethylation (TM) and remethylation (RM) rates increases and transulfuration (TS) decreases as pregnancy progresses from trimester 1 to 3. To determine whether pregnant Indian women can make this adaptation successfully, methionine kinetics, TS, TM, and RM were measured in Indian women in early and late pregnancy.
Measurements were made in the postabsorptive and fed states in the 1st and 3rd trimesters of pregnancy by infusing 1-(13)C,(2)H3-methionine in 24 women, 12 with low (≤150 pmol L(-1)) and 12 with normal (≥200 pmol L(-1)) vitamin B12 status at recruitment.
From trimester 1 to 3, except RM which decreased significantly, there was no change in any weight-specific methionine kinetic parameter. When expressed per whole body, methionine flux from protein breakdown increased significantly from trimester 1 to 3 in the fed and postabsorptive states. Flux to protein synthesis also increased significantly in the fed state. Rates of TM, TS and RM did not change, regardless of vitamin B12 status at recruitment. Protein and methionine intakes correlated with TM and RM rates and the change in RM from trimester 1 to 3 correlated with the change in dietary protein intake.
These results suggest that methionine flux and its utilization for protein synthesis increases in Indian women as pregnancy progresses from trimester 1 to 3. TM and RM rates do not increase however, possibly because of inadequate protein intake and not because of vitamin B12 deficiency at trimester 1.
一项针对美国孕妇的研究表明，随着孕期从第1阶段进展到第3阶段，蛋氨酸转甲基化（TM）和再甲基化（RM）速率增加，而转硫作用（TS）降低。为了确定印度孕妇是否能成功进行这种适应性变化，对印度孕妇孕早期和孕晚期的蛋氨酸动力学、TS、TM和RM进行了测量。
通过向24名女性输注1-（13）C，（2）H3-蛋氨酸，在孕第1和第3阶段的空腹和进食状态下进行测量，其中12名女性在招募时维生素B12水平较低（≤150 pmol L（-1）），12名女性维生素B12水平正常（≥200 pmol L（-1））。
从孕第1阶段到第3阶段，除RM显著降低外，任何体重特异性蛋氨酸动力学参数均无变化。按全身计算时，在进食和空腹状态下，孕第1阶段到第3阶段蛋白质分解产生的蛋氨酸通量显著增加。进食状态下蛋白质合成的通量也显著增加。无论招募时的维生素B12状态如何，TM、TS和RM的速率均无变化。蛋白质和蛋氨酸摄入量与TM和RM速率相关，孕第1阶段到第3阶段RM的变化与膳食蛋白质摄入量的变化相关。
这些结果表明，随着孕期从孕第1阶段进展到第3阶段，印度女性的蛋氨酸通量及其用于蛋白质合成的利用率增加。然而，TM和RM速率并未增加，可能是由于蛋白质摄入不足，而非孕第1阶段维生素B12缺乏。
