Maria J. Leskiw

Oxidative stress early in pregnancy and pregnancy outcome

The objectives of this study were to determine whether oxidative stress early in pregnancy influenced pregnancy outcome. A combination of assays were used for exogenous and endogenous anti-oxidants together with two well accepted biomarkers for oxidative stress, the urinary excretion of 8-iso-PGF2α (a biomarker marker for lipid oxidation, n=508) and 8-oxo-7,8 dihydro-2 deoxyguanosine (8-OHdG, a biomarker for DNA oxidation, n=487). The two biomarkers tracked different pregnancy outcomes. Isoprostanes were associated with an increased risk of pre-eclampsia and a decreased proportion of female births. In contrast, 8-OHdG tracked lower infant birthweight and shortened gestation duration. Birth defects were associated with low levels of 8-OHdG.

Protein kinetics during and after long-duration spaceflight on MIR

Human spaceflight is associated with a loss of body protein. Bed rest studies suggest that the reduction in the whole body protein synthesis (PS) rate should be ∼15%. The objectives of this experiment were to test two hypotheses on astronauts and cosmonauts during long-duration (>3 mo) flights on MIR: that 1) the whole body PS rate will be reduced and 2) dietary intake and the PS rate should be increased postflight because protein accretion is occurring. The15N glycine method was used for measuring whole body PS rate before, during, and after long-duration spaceflight on the Russian space station MIR. Dietary intake was measured together with the protein kinetics. Results show that subjects lost weight during flight (4.64 ± 1.0 kg, P < 0.05). Energy intake was decreased inflight (2,854 ± 268 vs. 2,145 ± 190 kcal/day, n = 6, P < 0.05), as was the PS rate (226 ± 24 vs. 97 ± 11 g protein/day, n = 6, P < 0.01). The reduction in PS correlated with the reduction in energy intake ( r 2 = 0.86, P < 0.01, n = 6). Postflight energy intake and PS returned to, but were not increased over, the preflight levels. We conclude that the reduction in PS found was greater than predicted from ground-based bed rest experiments because of the shortfall in dietary intake. The expected postflight anabolic state with increases in dietary intake and PS did not occur during the first 2 wk after landing.

Differences in Maternal Circulating Fatty Acid Composition and Dietary Fat Intake in Women With Gestational Diabetes Mellitus or Mild Gestational Hyperglycemia

OBJECTIVE We investigated the relationship between maternal circulating fatty acids (FAs) and dietary FA intake in pregnant women with gestational diabetes mellitus (GDM; n = 49), women with hyperglycemia less severe than GDM (impaired glucose challenge test [GCT] non-GDM; n = 80), and normal control subjects (n = 98). RESEARCH DESIGN AND METHODS A case-control design was nested within a prospective cohort of healthy pregnant women. Fasting concentrations of serum total FAs (enzymatic assay) and FA composition (gas chromatography–mass spectrometry) were determined at entry and the third trimester. Dietary fat intake data were obtained from 24-h recalls. RESULTS There was a graded increase among groups (control subjects, impaired GCT non-GDM, and GDM) during the third trimester for total FAs and individual FAs, including myristic, palmitic, palmitoleic, oleic, linoleic, linolenic, arachidonic, eicosapentaenoic, and docosahexaenoic acids (P for trend <0.03 to P < 0.001). Similar relationships were observed at entry in total FAs and for four FAs (myristic, palmitic, palmitoleic, and eicosapentaenoic acids). Women with impaired GCT non-GDM with BMI ≥25 kg/m2 had the highest levels of FAs at entry, whereas women with GDM with BMI ≥25 kg/m2 had the highest levels during the third trimester, and all grouped FAs were significantly different from lean women with impaired GCT non-GDM or control subjects (P < 0.05). Dietary intake of polyunsaturated FAs was decreased, but saturated FAs were increased in GDM compared with impaired GCT non-GDM or control subjects (P < 0.05). CONCLUSIONS Abnormalities in fat metabolism are present in both GDM and impaired GCT non-GDM women. Reducing pregravid weight and altering diet might prevent the associated elevation of circulating FAs.

Attenuation of the protein wasting associated with bed rest by branched-chain amino acids

Bed rest is generally accepted as being an appropriate ground-based model for human spaceflight. The objectives of this study were to test the hypothesis that increasing the amount of branched-chain amino acids (BCAAs) in the diet could attenuate the protein loss associated with bed rest. Nineteen healthy subjects were randomized into two groups according to diet. During the 6 d of bed rest, the diets were supplemented with either 30 mmol/d each of three non-essential amino acids, glycine, serine, and alanine (control group), or with 30 mmol/d each of the BCAAs, leucine, isoleucine, and valine (BCAA group). Nutrition was supplied as a commercially available defined formula diet at a rate of 1.3 x REE. Nitrogen (N) balance and urinary 3-MeH excretion were determined for the 6 d. In our results, the urine-based estimate of N balance was 22.2 +/- 14.4 (n = 9) mg N.kg-1.d-1 and 60.5 +/- 10.1 mg (n = 8) N.kg-1.d-1 for the control and BCAA-supplemented groups, respectively (P < 0.05). Urinary 3-MeH excretion was unchanged in both groups with bed rest. We conclude that BCAA supplementation attenuates the N loss during short-term bed rest.

Essential Fatty Acid Deficiency in Patients Receiving Simultaneous Parenteral and Oral Nutrition

Essential fatty acid deficiency is a common finding in patients nourished parenterally with hypertonic glucose and amino acids. In this study, we measured the linoleate concentration in the livers of 3 groups of patients. All the patients had operable upper gastrointestinal tract malignancies. Group I ate the hospitals regular diet ad libitum. Group II were given total parenteral nutrition (TPN), Group III received both enteral and parenteral nutrition and obtained about 35% of their caloric intake from food. The percentage of total liver fatty acids as linoleate were group I, 15.2 +/- 1.2%, group II, 3.7 +/- 1.4%, and group III, 2.8 +/- 1.6%. Data are expressed as the mean +/- 1 SEM. The patients who received 35% of their calories by mouth as food and the patients on TPN were found to be equally depleted in linoleate.