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Umbilical cord blood stearoyl-CoA desaturase index and lipoprotein lipase mass level in small-for-gestational age newborns
Prostaglandins, Leukotrienes and Essential Fatty Acids xxx (xxxx) xxxx
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Prostaglandins, Leukotrienes and Essential Fatty Acids journal homepage: www.elsevier.com/locate/plefa
Original research article
Umbilical cord blood stearoyl-CoA desaturase index and lipoprotein lipase mass level in small-for-gestational age newborns Kazumasa Fuwaa, Nobuhiko Naganoa, , Yohei Kitamurac, Fujihiko Iwatab, Tomoo Okadad, Ichiro Moriokaa ⁎
a
Department of Pediatrics and Child Health, Nihon University School of Medicine, Oyaguchi 30-1 Itabashi, Tokyo 173-8610, Japan Wakakusa Kodomo Clinic, Japan c Wellness and Nutrition Science Institute, R&D Division, Morinaga Milk Industry Co., Ltd., Japan d Department of Nutrition and Life Science, Kanagawa Institute of Technology, Japan b
ARTICLE INFO
ABSTRACT
Keywords: Small-for-gestational age Stearoyl-CoA desaturase Lipoprotein lipase mass
We previously reported that triglyceride (TG) levels in small-for-gestational age (SGA) newborns were significantly higher than those in appropriate-for-gestational age (AGA) newborns. Stearoyl-CoA desaturase (SCD) activity is required for TG synthesis, while lipoprotein lipase mass (LPLm) facilitates TG clearance. The purpose of this study is to reveal whether SCD activity or LPLm is the cause of high TG levels in SGA newborns. Fifty-five newborns were classified as AGA (n = 42) and SGA (n = 13). Serum LPLm, TG and fatty acids in umbilical cord blood were analyzed. Then, [16:1 (n-7)]/ [16:0] and [18:1 (n-9)]/ [18:0] were calculated as SCD16 and SCD18 activities, respectively. The SGA group showed significantly higher TG levels and significantly lower LPLm levels than the AGA group. However, SCD16 and 18 activities were lower in SGA newborns than in AGA newborns. In conclusion, LPLm, rather than SCD activity may be involved in the increased TG levels in SGA newborns.
1. Introduction Stearoyl-CoA desaturase (SCD) is a rate limiting enzyme in converting saturated fatty acids (palmitic acid [16:0] and stearic acid [18:0]) to monounsaturated fatty acids (palmitoleic acid [16:1 (n-7)] and oleic acid [18:1 (n-9)]) in the cell, respectively, and is associated with de novo lipogenesis (DNL) [1]. SCD index is known as a surrogate marker for DNL. There are some published studies on SCD index in children [2–6], however, studies on SCD index in neonates are limited [7]. LPL is produced in muscles and adipocytes and exists on the vascular endothelium, and hydrolyzes triglyceride (TG) into three fatty acids and a glycerol. The fatty acids are transferred into muscles and adipocytes and accumulated or consumed there. Thus, LPL is one of the important factors involved in lipid accumulation in adipocytes. In vivo, administration of a monoclonal antibody against LPL in adipose tissues inhibits the hydrolysis of very low-density lipoprotein (VLDL) by LPL and reduces the weight of adipocytes [8]. In experiments with genetically modified model mice, LPL has been reported as a major factor of obesity [9]. Formerly, the activity of LPL in blood samples was measured after the injection of heparin because LPL is released from vascular ⁎
endothelium by heparin. A recent study in patients with LPL-deficiency showed that LPL mass in non-heparinized serum (LPLm) was a physiologically relevant index of LPL-mediated lipolysis of plasma TG [10]. We previously reported that high TG levels and a small accumulation of subcutaneous fat in low birthweight infants are due to a reduced TG uptake into the subcutaneous fat because of low LPLm levels [11]. Moreover, TG levels in small-for-gestational age (SGA) newborns were significantly higher than those in appropriate-for-gestational age (AGA) newborns [12]. However, TG synthesis by enhanced SCD index in SGA newborns still remains unclear. On the contrary, in SGA newborns low LPLm levels also may cause high TG levels like low birthweight infants. The aim of the present study is to determine whether SCD index or LPLm levels are involved in high TG levels in SGA newborns. 2. Subjects and methods Umbilical cord blood samples, which had been collected and stored from 55 newborns (32 males, 23 females) born between October 2007 and September 2008 at Nihon University Itabashi Hospital, were retrospectively analyzed. Newborns were divided into two groups: AGA newborns with birth weight (BW) ≥ the 10th percentile and < the 90th percentile for Gestational age (GA) (n = 42) and SGA newborns with
Corresponding author. E-mail address: [email protected] (N. Nagano).
https://doi.org/10.1016/j.plefa.2019.102028 Received 19 June 2019; Received in revised form 22 September 2019; Accepted 5 November 2019 0952-3278/ © 2019 Elsevier Ltd. All rights reserved.
Please cite this article as: Kazumasa Fuwa, et al., Prostaglandins, Leukotrienes and Essential Fatty Acids, https://doi.org/10.1016/j.plefa.2019.102028
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BW < the 10th percentile for GA (n = 13). All of the mothers were healthy and their pregnancies were without complications. None of the neonates had asphyxia. At birth, the umbilicus was double clamped and the cord blood was sampled from the umbilical vein. Written informed consent was obtained from all of the parents and the study was approved by the University Ethics Committee (Nihon University, Itabashi Hospital, Tokyo, Japan). Triceps, biceps, suprailiac, and subscapular skinfold thicknesses were measured on the left side of the body with a skinfold caliper (Holtain Ltd, Crosswell, Crymych, UK), according to the procedure reported by Schmelzle and Fusch [13]. Subcutaneous fat accumulation was evaluated as the sum of these four skinfold thicknesses. Serum LPLm levels were analyzed by a sandwich enzyme-linked immunosorbent assay using a specific monoclonal antibody against LPL (Daiichi Pure Chemicals, Tokyo, Japan) [10]. Serum TG levels were measured using high-performance liquid chromatography with gel permeation columns (LipoSEARCH; Skylight-Biotec Inc., Akita, Japan) [14]. Plasma and red blood cell (RBC) fatty acids were analyzed by gas chromatography. Briefly, total lipids in red blood cell or plasma were extracted using a methanol-chloroform (1:1 vol/vol) solution. Total lipids were then separated into phospholipids and neutral lipids by the solid-phase extraction. Following the addition of an internal standard (tricosanoic acid methylester, Sigma, Japan), phospholipids were converted to methyl esters using boron trifluoride methanol (14 wt/v%) at 90 °C for 60 min. Fatty acid composition was analyzed with a gas chromatograph equipped with a fused silica capillary column (omegawax-250 30 m × 0.25 mm i.d.; 0.25 μm film, Supelco, Japan). C12-C24 fatty acids were identified using the retention time of the fatty acid methyl ester standards [15]. Finally, palmitoleic acid [16:1 (n-7)]/palmitic acid [16:0] and oleic acid [18:1 (n-9)]/stearic acid [18:0] were calculated as SCD16 and SCD18 indices, respectively [16]. All statistical analyses were conducted with JMP (version 14.0 SAS Institute Inc., Cary, NC, USA). Data are reported as mean ± standard deviation. Differences in measured parameters between AGA and SGA newborns were analyzed by using the Mann-Whitney U test. Bivariable normal ellipses were used to assess the correlation between variables. Multiple regression analyses were used to examine the effect of independent variables on TG levels. We set GA and BW Z score as independent variables. Selection of a priori variables was based on previous literatures [12,17]. P values < 0.05 were considered significant.
Table 2 Comparison between AGA and SGA.
Lipoprotein lipase mass (ng/ ml) Triglyceride (mg/dl) Plasma 16:0 Plasma 16:1(n-7) Plasma Stearoyl CoA desaturase 16 index Plasma 18:0 Plasma18:1(n-9) Plasma Stearoyl CoA desaturase 18 index Red blood cell 16:0 Red blood cell 16:1(n-7) Red blood cell Stearoyl CoA desaturase 16 index Red blood cell 18:0 Red blood cell 18:1(n-9) Red blood cell Stearoyl CoA desaturase 18 index
Gender (Male:female) Gestational age (weeks) Birth weight (g) Birth weight%tile Birth weight Z-score Sum of skinfold thickness (mm)
25:17 34.5 ± 2.34 2180 ± 456 46.5 ± 23.1 −0.0919 ± 0.673 14.4 ± 2.34
7:6 36.5 ± 2.56 1920 ± 354 3.75 ± 3.25 −2.08 ± 0.726 12.2 ± 2.42
0.72 <0.05 0.10 <0.05 <0.05 <0.05
63.0 ± 21.8
44.6 ± 17.5
<0.05
25.9 ± 15.1 28.6 ± 1.21 1.81 ± 0.392 0.0629 ± 0.0137
39.2 ± 21.6 27.7 ± 1.18 1.48 ± 0.304 0.0546 ± 0.0113
<0.05 <0.05 <0.05 0.06
14.2 ± 1.08 8.73 ± 1.10 0.621 ± 0.107
15.8 ± 1.51 8.09 ± 1.18 0.547 ± 0.131
<0.05 0.075 <0.05
23.3 ± 0.873 2.09 ± 0.475 0.0893 ± 0.0199
23.6 ± 1.02 1.89 ± 0.479 0.08 ± 0.0234
0.342 0.175 0.25
14.2 ± 0.681 11.2 ± 1.29 0.794 ± 0.119
14.4 ± 0.848 10.7 ± 1.35 0.742 ± 0.129
0.298 0.175 0.09
Sum of skinfold thickness (mm) Triglyceride level (mg/dl) Lipoprotein lipase mass (ng/ml) Plasma stearoyl CoA desaturase 16 index Plasma stearoyl CoA desaturase 18 index Red blood cell stearoyl CoA desaturase 16 index Red blood cell stearoyl CoA desaturase 18 index
Correlation coeffiecient
p-value
0.572 −0.486 0.619 0.453 0.190 0.178
<0.05 <0.05 <0.05 <0.05 0.165 0.192
0.164
0.233
newborns (p = 0.0636, p = 0.0900). The relationships between BW Z scores and other variables were investigated (Table 3, Fig. 1). We found a positive correlation between the BW Z score and the sum of skinfold thickness (r = 0.572, p < 0.05), LPLm levels (r = 0.619, p < 0.05), and plasma SCD16 index (r = 0.453, p < 0.05) by bivariate normal ellipse analyses. In contrast, a negative correlation was found between the BW Z score and TG levels (r = −0.486, p < 0.05). Moreover, the relationships between the sum of skinfold thickness and other variables were investigated (Table 4, Fig. 2). We found a positive correlation between the sum of skinfold thickness and LPLm levels (r = 0.483, p < 0.05). In contrast, a negative correlation was found between the sum of skinfold thickness and TG levels (r = −0.338, p < 0.05). There was no correlation between the sum of skinfold thickness and all SCD indices. In multiple regression analyses (Table 5), BW Z score was a significant determinant for TG levels, but GA was not a significant determinant. 4. Discussion and conclusions
Table 1 Characteristics of the subjects. p-value
p-value
Table 3 Relation between birth weight Z score and other variables.
Characteristics of the subjects are shown in Table 1. The mean gestational ages of the SGA and AGA newborns were 36.5 ± 2.56 and 34.5 ± 2.34 weeks, respectively (p < 0.05). The sum of skinfold thickness of SGA newborns was significantly less than that of AGA newborns (p < 0.05). A comparison between SGA and AGA newborns is shown in Table 2. SGA newborns showed significantly higher TG levels and significantly lower LPLm levels than AGA newborns (p < 0.05, p < 0.05). However, plasma SCD18 index was significantly lower in SGA newborns than in AGA newborns (p < 0.05). Plasma SCD16 and RBC SCD18 index tended to be lower in SGA newborns than in AGA
SGA (n = 13)
SGA (n = 13)
AGA: Appropriate-for-gestational age, SGA: Small-for-gestational age.
3. Results
AGA (n = 42)
AGA (n = 42)
In this study, we found that SGA newborns had significantly higher TG levels, lower LPLm levels and a tendency of lower SCD index compared to AGA newborns. Therefore, increased TG levels in SGA newborns were caused by decreased TG clearance due to low LPLm levels rather than increased TG synthesis due to enhanced SCD index. We previously reported that LPLm in cord blood was positively correlated with the sum of skinfold thickness and BW Z score, and was negatively correlated with VLDL-TG [11]. These results showed that when LPL is enhanced, the subcutaneous skinfold thickness and body weight increase by hydrolyzing VLDL-TG. However, the impact of the infant's SCD index in VLDL-TG production was still unknown.
AGA: Appropriate-for-gestational age, SGA: Small-for-gestational age. 2
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Fig. 1. Relationships between birth weight Z score and other variables (Sum skinfold thickness, triglyceride level, lipoprotein lipase mass and stearoyl CoA desaturase). The relationships between birth weight (BW) Z score and sum of skinfold thickness, triglyceride level, and lipoprotein lipase mass are in the upper row. The relationships between BW Z score and plasma stearoyl-CoA desaturase 16 and 18 index, and red blood cell stearoyl-CoA desaturase 16 index are in the middle row. The relationship between BW Z score and red blood cell stearoyl-CoA desaturase 18 index is in the lower row.
and a study in obese subjects showed a positive association between SCD index and abdominal adiposity [21,22]. Studies about SCD in neonates are limited. Gestational Diabetes Mellitus newborns had increased SCD index in cord blood [7]. To our best knowledge, this is the first report about SCD index in SGA newborns. The comparison of RBC SCD and plasma SCD enables us to speculate about the role of SCD index in neonates. The composition of fatty acids in erythrocyte membranes reflects the diet during the life of the RBC. On the other hand, the composition of fatty acids in plasma reflects the diet over a few days before sampling [23]. Thus, RBC SCD index may assess DNL during the life of the RBC and plasma SCD index may assess DNL prior to sampling. While plasma SCD index especially reflect DNL in liver [24], RBC SCD index is still incompletely understood. Our study showed inconstant tendency of RBC SCD index. This result might suggest RBC SCD index is modulated by many factors as well as life span of RBC. Genetic backgrounds also relate to the difference between RBC and plasma SCD index. A previous report showed acceptable correlation between plasma SCD index and SCD mRNA expression [25]. In general, epigenetic alterations vary from organ to organ. Therefore, we speculate the phenotype of RBC is different from that of plasma. Further research about RBC SCD index including genetic backgrounds is expected. The correlation between BW Z score and plasma SCD 16 index indicates that increased SCD index may necessary for BW gain in the fetus, but no correlation between subcutaneous skinfold thickness and
Table 4 Relation between the sum of skinfold thickness and other variables.
Triglyceride level (mg/dl) Lipoprotein lipase mass (ng/ml) Plasma stearoyl CoA desaturase 16 index Plasma stearoyl CoA desaturase 18 index Red blood cell stearoyl CoA desaturase 16 index Red blood cell stearoyl CoA desaturase 18 index
Correlation coeffiecient
p-value
−0.338 0.483 0.263 0.114 −0.0124
<0.05 <0.05 0.0536 0.407 0.929
0.136
0.321
We showed that subcutaneous skinfold thickness was positively correlated with LPLm and negatively correlated with TG. Plasma and RBC SCD index were not correlated with subcutaneous skinfold thickness. Therefore, LPLm, not SCD index, was responsible for TG clearance and subcutaneous fat accumulation. The function of SCD is still controversial. In a study of healthy 60 year old men, SCD index that was estimated from [18:1 (n-9)]/ [18:0] had a negative correlation with BMI [16]. Another report showed that SCD index had no relation with BMI or waist circumference [18]. A Japanese study demonstrated that visceral fat thickness correlated positively with SCD index in overweight men, but not in normal-weight men [19]. Additionally, SCD index had a significantly positive relationship with waist circumference in healthy adolescent females [20], 3
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Fig. 2. Relationships between the sum of skinfold thickness and other variables (Triglyceride level, lipoprotein lipase mass and stearoyl CoA desaturase). The relationships between the sum of skinfold thickness and triglyceride level, lipoprotein lipase mass, and plasma stearoyl-CoA desaturase 16 index are in the upper row. The relationships between the sum of skinfold thickness and plasma stearoyl-CoA desaturase 18 index, and red blood cell stearoyl-CoA desaturase 16 and 18 index are in the lower row.
measurement of LPLm and SCD index may reveal the mechanism of metabolic syndrome and help to develop treatments that prevent metabolic syndrome in SGA newborns. In conclusion, in SGA newborns, high TG levels in cord blood are not due to the increased SCD index, but related to the decreased LPLm levels. The changes in lipid metabolism such as SCD index and LPLm in SGA newborns may be key factors in SGA related complications.
Table 5 Independent predictors for Triglyceride levels. Predictor Triglyceride Levels (mg/dl) Birth weight Z-score (g) Gestational age (weeks)
Coefficient
SE
p-value
2
(R = 0.262, p<0.05) −7.08 2.01 1.19 0.894
<0.05 0.187
SE: Standard Error.
Role of funding source
SCD index in our study. In order to prove the relationship between DNL and SCD, the number of cases is small and further study is needed. Generally, BW and subcutaneous fat accumulation of SGA newborns gradually catch up to those of AGA newborns after birth. In other words, there should be a point where SCD index also increases after birth in SGA newborns. However, in this study only cord blood samples were analyzed and further studies of infant blood samples are required. Our study had several limitations. First, this was a retrospective case control study in a single institution and the sample size was limited. Moreover, gestational age could not be matched between SGA and AGA newborns in this study. Therefore, we were unable to eliminate differences of SCD index depending on GA. But in multiple regression analyses, BW Z score was a significant determinant for TG levels, but GA was not a significant determinant. Second, we failed to measure SCD regulating factors, such as insulin and leptin, due to the small sample volumes. Insulin suppresses SCD index [1]. In children with abdominal obesity, leptin has been known as an SCD index suppressor [26]. In further studies, the impact of insulin and leptin on SCD index should be investigated. SGA newborns have metabolic functions that are exposed and adapted to malnutrition in the uterus. Therefore, exposure to excessive nutrition after birth causes accumulation of subcutaneous fat and various metabolic function problems. Therefore, SGA newborns are at high risk of metabolic syndrome, but the detailed mechanisms are unclear. Lipid metabolism such as the LPLm and SCD indices observed in this study may be early changes in the onset of metabolic syndrome in SGA newborns. In the future, a multicenter prospective study including
This work was supported by Grants-in-Aid for Early-Career Scientists of JSPS KAKENHI (grant number: 19K20194). CRediT authorship contribution statement Kazumasa Fuwa: Writing - original draft. Nobuhiko Nagano: Conceptualization, Writing - original draft. Yohei Kitamura: . Fujihiko Iwata: Conceptualization. Tomoo Okada: Conceptualization, Data curation. Ichiro Morioka: Data curation, Writing - original draft. Declaration of Competing Interest None. Acknowledgements We thank the medical and nursing staff of the ward for their assistance in this study. This work was supported by Grants-in-Aid for Young Scientists (grant number: 19K20194) of JSPS KAKENHI. References [1] J.M. Ntambi, M. Miyazaki, Regulation of stearoyl-CoA desaturases and role in metabolism, Prog. Lipid Res. 43 (2004) 91–104. [2] E. Saito, T. Okada, Y. Abe, M. Odaka, Y. Kuromori, F. Iwata, M. Hara, H. Mugishima, Y. Kitamura, Abdominal adiposity is associated with fatty acid desaturase activity in boys: implications for C-reactive protein and insulin resistance, Prostaglandins Leukot. Essent. Fatty Acids 88 (2013) 307–311.
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K. Fuwa, et al. [3] E. Saito, T. Okada, Y. Abe, Y. Kuromori, M. Miyashita, F. Iwata, M. Hara, M. Ayusawa, H. Mugishima, Y. Kitamura, Docosahexaenoic acid content in plasma phospholipids and desaturase indices in obese children, J. Atheroscler. Thromb. 18 (2011) 345–350. [4] T. Venalainen, J. Agren, U. Schwab, V.D. de Mello, A.M. Eloranta, D.E. Laaksonen, V. Lindi, T.A. Lakka, Cross-sectional associations of plasma fatty acid composition and estimated desaturase and elongase activities with cardiometabolic risk in Finnish children – the Panic study, J. Clin. Lipidol. 10 (2016) 82–91. [5] Y. Fujita, T. Okada, Y. Abe, M. Kazama, E. Saito, Y. Kuromori, F. Iwata, M. Hara, M. Ayusawa, H. Izumi, Y. Kitamura, T. Shimizu, Effect of cod liver oil supplementation on the stearoyl-CoA desaturase index in obese children: a pilot study, Obes. Res. Clin. Pract. 9 (2015) 31–34. [6] T. Venalainen, U. Schwab, J. Agren, V. de Mello, V. Lindi, A.M. Eloranta, S. Kiiskinen, D. Laaksonen, T.A. Lakka, Cross-sectional associations of food consumption with plasma fatty acid composition and estimated desaturase activities in Finnish children, Lipids 49 (2014) 467–479. [7] J.K. Yee, C.S. Mao, M.G. Ross, W.N. Lee, M. Desai, A. Toda, S.L. Kjos, R.A. Hicks, M.E. Patterson, High oleic/stearic fatty-acid desaturation index in cord plasma from infants of mothers with gestational diabetes, J. Perinatol. 34 (2014) 357–363. [8] K. Sato, Y. Akiba, Y. Chida, K. Takahashi, Lipoprotein hydrolysis and fat accumulation in chicken adipose tissues are reduced by chronic administration of lipoprotein lipase monoclonal antibodies, Poult. Sci. 78 (1999) 1286–1291. [9] P.J. Voshol, P.C. Rensen, K.W. van Dijk, J.A. Romijn, L.M. Havekes, Effect of plasma triglyceride metabolism on lipid storage in adipose tissue: studies using genetically engineered mouse models, Biochim. Biophys. Acta 1791 (2009) 479–485. [10] J. Kobayashi, H. Hashimoto, I. Fukamachi, J. Tashiro, K. Shirai, Y. Saito, S. Yoshida, Lipoprotein lipase mass and activity in severe hypertriglyceridemia, Clin. Chim. Acta 216 (1993) 113–123. [11] K. Yoshikawa, T. Okada, S. Munakata, A. Okahashi, R. Yonezawa, M. Makimoto, S. Hosono, S. Takahashi, H. Mugishima, T. Yamamoto, Association between serum lipoprotein lipase mass concentration and subcutaneous fat accumulation during neonatal period, Eur. J. Clin. Nutr. 64 (2010) 447–453. [12] N. Nagano, T. Okada, R. Fukamachi, K. Yoshikawa, S. Munakata, Y. Usukura, S. Hosono, S. Takahashi, H. Mugishima, M. Matsuura, T. Yamamoto, Insulin-like growth factor-1 and lipoprotein profile in cord blood of preterm small for gestational age infants, J. Dev. Orig. Health Dis. 4 (2013) 507–512. [13] H.R. Schmelzle, C. Fusch, Body fat in neonates and young infants: validation of skinfold thickness versus dual-energy X-ray absorptiometry, Am. J. Clin. Nutr. 76 (2002) 1096–1100. [14] M. Okazaki, S. Usui, M. Ishigami, N. Sakai, T. Nakamura, Y. Matsuzawa, S. Yamashita, Identification of unique lipoprotein subclasses for visceral obesity by component analysis of cholesterol profile in high-performance liquid
chromatography, Arterioscler. Thromb. Vasc. Biol. 25 (2005) 578–584. [15] N. Nagano, T. Okada, K. Kayama, S. Hosono, Y. Kitamura, S. Takahashi, Delta-6 desaturase activity during the first year of life in preterm infants, Prostaglandins Leukot. Essent. Fatty Acids 115 (2016) 8–11. [16] E. Warensjo, M. Rosell, M.L. Hellenius, B. Vessby, U. De Faire, U. Riserus, Associations between estimated fatty acid desaturase activities in serum lipids and adipose tissue in humans: links to obesity and insulin resistance, Lipids Health Dis. 8 (2009) 37. [17] R. Yonezawa, T. Okada, T. Kitamura, H. Fujita, I. Inami, M. Makimoto, S. Hosono, M. Minato, S. Takahashi, H. Mugishima, T. Yamamoto, N. Masaoka, Very lowdensity lipoprotein in the cord blood of preterm neonates, Metab. Clin. Exp. 58 (2009) 704–707. [18] L.M. Steffen, B. Vessby, D.R. Jacobs Jr., J. Steinberger, A. Moran, C.P. Hong, A.R. Sinaiko, Serum phospholipid and cholesteryl ester fatty acids and estimated desaturase activities are related to overweight and cardiovascular risk factors in adolescents, Int. J. Obes. 32 (2008) 1297–1304. [19] T. Kishino, K. Watanabe, T. Urata, M. Takano, T. Uemura, K. Nishikawa, Y. Mine, M. Matsumoto, K. Ohtsuka, H. Ohnishi, H. Mori, S. Takahashi, H. Ishida, T. Watanabe, Visceral fat thickness in overweight men correlates with alterations in serum fatty acid composition, Clin. Chim. Acta 398 (2008) 57–62. [20] Y.E. Zhou, G.M. Egeland, S.J. Meltzer, S. Kubow, The association of desaturase 9 and plasma fatty acid composition with insulin resistance-associated factors in female adolescents, Metab. Clin. Exp. 58 (2009) 158–166. [21] T. Okada, N. Furuhashi, Y. Kuromori, M. Miyashita, F. Iwata, K. Harada, Plasma palmitoleic acid content and obesity in children, Am. J. Clin. Nutr. 82 (2005) 747–750. [22] A. Kawashima, S. Sugawara, M. Okita, T. Akahane, K. Fukui, M. Hashiuchi, C. Kataoka, I. Tsukamoto, Plasma fatty acid composition, estimated desaturase activities, and intakes of energy and nutrient in Japanese men with abdominal obesity or metabolic syndrome, J. Nutr. Sci. Vitaminol. 55 (2009) 400–406. [23] L. Arab, Biomarkers of fat and fatty acid intake, J. Nutr. 3 (133 suppl) (2003) 925s–932s. [24] M.T. Flowers, The delta9 fatty acid desaturation index as a predictor of metabolic disease, Clin. Chem. 55 (2009) 2071–2073. [25] A. Peter, A. Cegan, S. Wagner, R. Lehmann, N. Stefan, A. Konigsrainer, I. Konigsrainer, H.U. Haring, E. Schleicher, Hepatic lipid composition and stearoylcoenzyme A desaturase 1 mRNA expression can be estimated from plasma VLDL fatty acid ratios, Clin. Chem. 55 (2009) 2113–2120. [26] E. Saito, T. Okada, Y. Abe, M. Odaka, Y. Kuromori, F. Iwata, M. Hara, H. Mugishima, Y. Kitamura, Relationship between estimated fatty acid desaturase activities and abdominal adiposity in Japanese children, Obes. Res. Clin. Pract. 8 (2014) e201–e298.
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Contents lists available at ScienceDirect
Prostaglandins, Leukotrienes and Essential Fatty Acids journal homepage: www.elsevier.com/locate/plefa
Original research article
Umbilical cord blood stearoyl-CoA desaturase index and lipoprotein lipase mass level in small-for-gestational age newborns Kazumasa Fuwaa, Nobuhiko Naganoa, , Yohei Kitamurac, Fujihiko Iwatab, Tomoo Okadad, Ichiro Moriokaa ⁎
a
Department of Pediatrics and Child Health, Nihon University School of Medicine, Oyaguchi 30-1 Itabashi, Tokyo 173-8610, Japan Wakakusa Kodomo Clinic, Japan c Wellness and Nutrition Science Institute, R&D Division, Morinaga Milk Industry Co., Ltd., Japan d Department of Nutrition and Life Science, Kanagawa Institute of Technology, Japan b
ARTICLE INFO
ABSTRACT
Keywords: Small-for-gestational age Stearoyl-CoA desaturase Lipoprotein lipase mass
We previously reported that triglyceride (TG) levels in small-for-gestational age (SGA) newborns were significantly higher than those in appropriate-for-gestational age (AGA) newborns. Stearoyl-CoA desaturase (SCD) activity is required for TG synthesis, while lipoprotein lipase mass (LPLm) facilitates TG clearance. The purpose of this study is to reveal whether SCD activity or LPLm is the cause of high TG levels in SGA newborns. Fifty-five newborns were classified as AGA (n = 42) and SGA (n = 13). Serum LPLm, TG and fatty acids in umbilical cord blood were analyzed. Then, [16:1 (n-7)]/ [16:0] and [18:1 (n-9)]/ [18:0] were calculated as SCD16 and SCD18 activities, respectively. The SGA group showed significantly higher TG levels and significantly lower LPLm levels than the AGA group. However, SCD16 and 18 activities were lower in SGA newborns than in AGA newborns. In conclusion, LPLm, rather than SCD activity may be involved in the increased TG levels in SGA newborns.
1. Introduction Stearoyl-CoA desaturase (SCD) is a rate limiting enzyme in converting saturated fatty acids (palmitic acid [16:0] and stearic acid [18:0]) to monounsaturated fatty acids (palmitoleic acid [16:1 (n-7)] and oleic acid [18:1 (n-9)]) in the cell, respectively, and is associated with de novo lipogenesis (DNL) [1]. SCD index is known as a surrogate marker for DNL. There are some published studies on SCD index in children [2–6], however, studies on SCD index in neonates are limited [7]. LPL is produced in muscles and adipocytes and exists on the vascular endothelium, and hydrolyzes triglyceride (TG) into three fatty acids and a glycerol. The fatty acids are transferred into muscles and adipocytes and accumulated or consumed there. Thus, LPL is one of the important factors involved in lipid accumulation in adipocytes. In vivo, administration of a monoclonal antibody against LPL in adipose tissues inhibits the hydrolysis of very low-density lipoprotein (VLDL) by LPL and reduces the weight of adipocytes [8]. In experiments with genetically modified model mice, LPL has been reported as a major factor of obesity [9]. Formerly, the activity of LPL in blood samples was measured after the injection of heparin because LPL is released from vascular ⁎
endothelium by heparin. A recent study in patients with LPL-deficiency showed that LPL mass in non-heparinized serum (LPLm) was a physiologically relevant index of LPL-mediated lipolysis of plasma TG [10]. We previously reported that high TG levels and a small accumulation of subcutaneous fat in low birthweight infants are due to a reduced TG uptake into the subcutaneous fat because of low LPLm levels [11]. Moreover, TG levels in small-for-gestational age (SGA) newborns were significantly higher than those in appropriate-for-gestational age (AGA) newborns [12]. However, TG synthesis by enhanced SCD index in SGA newborns still remains unclear. On the contrary, in SGA newborns low LPLm levels also may cause high TG levels like low birthweight infants. The aim of the present study is to determine whether SCD index or LPLm levels are involved in high TG levels in SGA newborns. 2. Subjects and methods Umbilical cord blood samples, which had been collected and stored from 55 newborns (32 males, 23 females) born between October 2007 and September 2008 at Nihon University Itabashi Hospital, were retrospectively analyzed. Newborns were divided into two groups: AGA newborns with birth weight (BW) ≥ the 10th percentile and < the 90th percentile for Gestational age (GA) (n = 42) and SGA newborns with
Corresponding author. E-mail address: [email protected] (N. Nagano).
https://doi.org/10.1016/j.plefa.2019.102028 Received 19 June 2019; Received in revised form 22 September 2019; Accepted 5 November 2019 0952-3278/ © 2019 Elsevier Ltd. All rights reserved.
Please cite this article as: Kazumasa Fuwa, et al., Prostaglandins, Leukotrienes and Essential Fatty Acids, https://doi.org/10.1016/j.plefa.2019.102028
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BW < the 10th percentile for GA (n = 13). All of the mothers were healthy and their pregnancies were without complications. None of the neonates had asphyxia. At birth, the umbilicus was double clamped and the cord blood was sampled from the umbilical vein. Written informed consent was obtained from all of the parents and the study was approved by the University Ethics Committee (Nihon University, Itabashi Hospital, Tokyo, Japan). Triceps, biceps, suprailiac, and subscapular skinfold thicknesses were measured on the left side of the body with a skinfold caliper (Holtain Ltd, Crosswell, Crymych, UK), according to the procedure reported by Schmelzle and Fusch [13]. Subcutaneous fat accumulation was evaluated as the sum of these four skinfold thicknesses. Serum LPLm levels were analyzed by a sandwich enzyme-linked immunosorbent assay using a specific monoclonal antibody against LPL (Daiichi Pure Chemicals, Tokyo, Japan) [10]. Serum TG levels were measured using high-performance liquid chromatography with gel permeation columns (LipoSEARCH; Skylight-Biotec Inc., Akita, Japan) [14]. Plasma and red blood cell (RBC) fatty acids were analyzed by gas chromatography. Briefly, total lipids in red blood cell or plasma were extracted using a methanol-chloroform (1:1 vol/vol) solution. Total lipids were then separated into phospholipids and neutral lipids by the solid-phase extraction. Following the addition of an internal standard (tricosanoic acid methylester, Sigma, Japan), phospholipids were converted to methyl esters using boron trifluoride methanol (14 wt/v%) at 90 °C for 60 min. Fatty acid composition was analyzed with a gas chromatograph equipped with a fused silica capillary column (omegawax-250 30 m × 0.25 mm i.d.; 0.25 μm film, Supelco, Japan). C12-C24 fatty acids were identified using the retention time of the fatty acid methyl ester standards [15]. Finally, palmitoleic acid [16:1 (n-7)]/palmitic acid [16:0] and oleic acid [18:1 (n-9)]/stearic acid [18:0] were calculated as SCD16 and SCD18 indices, respectively [16]. All statistical analyses were conducted with JMP (version 14.0 SAS Institute Inc., Cary, NC, USA). Data are reported as mean ± standard deviation. Differences in measured parameters between AGA and SGA newborns were analyzed by using the Mann-Whitney U test. Bivariable normal ellipses were used to assess the correlation between variables. Multiple regression analyses were used to examine the effect of independent variables on TG levels. We set GA and BW Z score as independent variables. Selection of a priori variables was based on previous literatures [12,17]. P values < 0.05 were considered significant.
Table 2 Comparison between AGA and SGA.
Lipoprotein lipase mass (ng/ ml) Triglyceride (mg/dl) Plasma 16:0 Plasma 16:1(n-7) Plasma Stearoyl CoA desaturase 16 index Plasma 18:0 Plasma18:1(n-9) Plasma Stearoyl CoA desaturase 18 index Red blood cell 16:0 Red blood cell 16:1(n-7) Red blood cell Stearoyl CoA desaturase 16 index Red blood cell 18:0 Red blood cell 18:1(n-9) Red blood cell Stearoyl CoA desaturase 18 index
Gender (Male:female) Gestational age (weeks) Birth weight (g) Birth weight%tile Birth weight Z-score Sum of skinfold thickness (mm)
25:17 34.5 ± 2.34 2180 ± 456 46.5 ± 23.1 −0.0919 ± 0.673 14.4 ± 2.34
7:6 36.5 ± 2.56 1920 ± 354 3.75 ± 3.25 −2.08 ± 0.726 12.2 ± 2.42
0.72 <0.05 0.10 <0.05 <0.05 <0.05
63.0 ± 21.8
44.6 ± 17.5
<0.05
25.9 ± 15.1 28.6 ± 1.21 1.81 ± 0.392 0.0629 ± 0.0137
39.2 ± 21.6 27.7 ± 1.18 1.48 ± 0.304 0.0546 ± 0.0113
<0.05 <0.05 <0.05 0.06
14.2 ± 1.08 8.73 ± 1.10 0.621 ± 0.107
15.8 ± 1.51 8.09 ± 1.18 0.547 ± 0.131
<0.05 0.075 <0.05
23.3 ± 0.873 2.09 ± 0.475 0.0893 ± 0.0199
23.6 ± 1.02 1.89 ± 0.479 0.08 ± 0.0234
0.342 0.175 0.25
14.2 ± 0.681 11.2 ± 1.29 0.794 ± 0.119
14.4 ± 0.848 10.7 ± 1.35 0.742 ± 0.129
0.298 0.175 0.09
Sum of skinfold thickness (mm) Triglyceride level (mg/dl) Lipoprotein lipase mass (ng/ml) Plasma stearoyl CoA desaturase 16 index Plasma stearoyl CoA desaturase 18 index Red blood cell stearoyl CoA desaturase 16 index Red blood cell stearoyl CoA desaturase 18 index
Correlation coeffiecient
p-value
0.572 −0.486 0.619 0.453 0.190 0.178
<0.05 <0.05 <0.05 <0.05 0.165 0.192
0.164
0.233
newborns (p = 0.0636, p = 0.0900). The relationships between BW Z scores and other variables were investigated (Table 3, Fig. 1). We found a positive correlation between the BW Z score and the sum of skinfold thickness (r = 0.572, p < 0.05), LPLm levels (r = 0.619, p < 0.05), and plasma SCD16 index (r = 0.453, p < 0.05) by bivariate normal ellipse analyses. In contrast, a negative correlation was found between the BW Z score and TG levels (r = −0.486, p < 0.05). Moreover, the relationships between the sum of skinfold thickness and other variables were investigated (Table 4, Fig. 2). We found a positive correlation between the sum of skinfold thickness and LPLm levels (r = 0.483, p < 0.05). In contrast, a negative correlation was found between the sum of skinfold thickness and TG levels (r = −0.338, p < 0.05). There was no correlation between the sum of skinfold thickness and all SCD indices. In multiple regression analyses (Table 5), BW Z score was a significant determinant for TG levels, but GA was not a significant determinant. 4. Discussion and conclusions
Table 1 Characteristics of the subjects. p-value
p-value
Table 3 Relation between birth weight Z score and other variables.
Characteristics of the subjects are shown in Table 1. The mean gestational ages of the SGA and AGA newborns were 36.5 ± 2.56 and 34.5 ± 2.34 weeks, respectively (p < 0.05). The sum of skinfold thickness of SGA newborns was significantly less than that of AGA newborns (p < 0.05). A comparison between SGA and AGA newborns is shown in Table 2. SGA newborns showed significantly higher TG levels and significantly lower LPLm levels than AGA newborns (p < 0.05, p < 0.05). However, plasma SCD18 index was significantly lower in SGA newborns than in AGA newborns (p < 0.05). Plasma SCD16 and RBC SCD18 index tended to be lower in SGA newborns than in AGA
SGA (n = 13)
SGA (n = 13)
AGA: Appropriate-for-gestational age, SGA: Small-for-gestational age.
3. Results
AGA (n = 42)
AGA (n = 42)
In this study, we found that SGA newborns had significantly higher TG levels, lower LPLm levels and a tendency of lower SCD index compared to AGA newborns. Therefore, increased TG levels in SGA newborns were caused by decreased TG clearance due to low LPLm levels rather than increased TG synthesis due to enhanced SCD index. We previously reported that LPLm in cord blood was positively correlated with the sum of skinfold thickness and BW Z score, and was negatively correlated with VLDL-TG [11]. These results showed that when LPL is enhanced, the subcutaneous skinfold thickness and body weight increase by hydrolyzing VLDL-TG. However, the impact of the infant's SCD index in VLDL-TG production was still unknown.
AGA: Appropriate-for-gestational age, SGA: Small-for-gestational age. 2
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Fig. 1. Relationships between birth weight Z score and other variables (Sum skinfold thickness, triglyceride level, lipoprotein lipase mass and stearoyl CoA desaturase). The relationships between birth weight (BW) Z score and sum of skinfold thickness, triglyceride level, and lipoprotein lipase mass are in the upper row. The relationships between BW Z score and plasma stearoyl-CoA desaturase 16 and 18 index, and red blood cell stearoyl-CoA desaturase 16 index are in the middle row. The relationship between BW Z score and red blood cell stearoyl-CoA desaturase 18 index is in the lower row.
and a study in obese subjects showed a positive association between SCD index and abdominal adiposity [21,22]. Studies about SCD in neonates are limited. Gestational Diabetes Mellitus newborns had increased SCD index in cord blood [7]. To our best knowledge, this is the first report about SCD index in SGA newborns. The comparison of RBC SCD and plasma SCD enables us to speculate about the role of SCD index in neonates. The composition of fatty acids in erythrocyte membranes reflects the diet during the life of the RBC. On the other hand, the composition of fatty acids in plasma reflects the diet over a few days before sampling [23]. Thus, RBC SCD index may assess DNL during the life of the RBC and plasma SCD index may assess DNL prior to sampling. While plasma SCD index especially reflect DNL in liver [24], RBC SCD index is still incompletely understood. Our study showed inconstant tendency of RBC SCD index. This result might suggest RBC SCD index is modulated by many factors as well as life span of RBC. Genetic backgrounds also relate to the difference between RBC and plasma SCD index. A previous report showed acceptable correlation between plasma SCD index and SCD mRNA expression [25]. In general, epigenetic alterations vary from organ to organ. Therefore, we speculate the phenotype of RBC is different from that of plasma. Further research about RBC SCD index including genetic backgrounds is expected. The correlation between BW Z score and plasma SCD 16 index indicates that increased SCD index may necessary for BW gain in the fetus, but no correlation between subcutaneous skinfold thickness and
Table 4 Relation between the sum of skinfold thickness and other variables.
Triglyceride level (mg/dl) Lipoprotein lipase mass (ng/ml) Plasma stearoyl CoA desaturase 16 index Plasma stearoyl CoA desaturase 18 index Red blood cell stearoyl CoA desaturase 16 index Red blood cell stearoyl CoA desaturase 18 index
Correlation coeffiecient
p-value
−0.338 0.483 0.263 0.114 −0.0124
<0.05 <0.05 0.0536 0.407 0.929
0.136
0.321
We showed that subcutaneous skinfold thickness was positively correlated with LPLm and negatively correlated with TG. Plasma and RBC SCD index were not correlated with subcutaneous skinfold thickness. Therefore, LPLm, not SCD index, was responsible for TG clearance and subcutaneous fat accumulation. The function of SCD is still controversial. In a study of healthy 60 year old men, SCD index that was estimated from [18:1 (n-9)]/ [18:0] had a negative correlation with BMI [16]. Another report showed that SCD index had no relation with BMI or waist circumference [18]. A Japanese study demonstrated that visceral fat thickness correlated positively with SCD index in overweight men, but not in normal-weight men [19]. Additionally, SCD index had a significantly positive relationship with waist circumference in healthy adolescent females [20], 3
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Fig. 2. Relationships between the sum of skinfold thickness and other variables (Triglyceride level, lipoprotein lipase mass and stearoyl CoA desaturase). The relationships between the sum of skinfold thickness and triglyceride level, lipoprotein lipase mass, and plasma stearoyl-CoA desaturase 16 index are in the upper row. The relationships between the sum of skinfold thickness and plasma stearoyl-CoA desaturase 18 index, and red blood cell stearoyl-CoA desaturase 16 and 18 index are in the lower row.
measurement of LPLm and SCD index may reveal the mechanism of metabolic syndrome and help to develop treatments that prevent metabolic syndrome in SGA newborns. In conclusion, in SGA newborns, high TG levels in cord blood are not due to the increased SCD index, but related to the decreased LPLm levels. The changes in lipid metabolism such as SCD index and LPLm in SGA newborns may be key factors in SGA related complications.
Table 5 Independent predictors for Triglyceride levels. Predictor Triglyceride Levels (mg/dl) Birth weight Z-score (g) Gestational age (weeks)
Coefficient
SE
p-value
2
(R = 0.262, p<0.05) −7.08 2.01 1.19 0.894
<0.05 0.187
SE: Standard Error.
Role of funding source
SCD index in our study. In order to prove the relationship between DNL and SCD, the number of cases is small and further study is needed. Generally, BW and subcutaneous fat accumulation of SGA newborns gradually catch up to those of AGA newborns after birth. In other words, there should be a point where SCD index also increases after birth in SGA newborns. However, in this study only cord blood samples were analyzed and further studies of infant blood samples are required. Our study had several limitations. First, this was a retrospective case control study in a single institution and the sample size was limited. Moreover, gestational age could not be matched between SGA and AGA newborns in this study. Therefore, we were unable to eliminate differences of SCD index depending on GA. But in multiple regression analyses, BW Z score was a significant determinant for TG levels, but GA was not a significant determinant. Second, we failed to measure SCD regulating factors, such as insulin and leptin, due to the small sample volumes. Insulin suppresses SCD index [1]. In children with abdominal obesity, leptin has been known as an SCD index suppressor [26]. In further studies, the impact of insulin and leptin on SCD index should be investigated. SGA newborns have metabolic functions that are exposed and adapted to malnutrition in the uterus. Therefore, exposure to excessive nutrition after birth causes accumulation of subcutaneous fat and various metabolic function problems. Therefore, SGA newborns are at high risk of metabolic syndrome, but the detailed mechanisms are unclear. Lipid metabolism such as the LPLm and SCD indices observed in this study may be early changes in the onset of metabolic syndrome in SGA newborns. In the future, a multicenter prospective study including
This work was supported by Grants-in-Aid for Early-Career Scientists of JSPS KAKENHI (grant number: 19K20194). CRediT authorship contribution statement Kazumasa Fuwa: Writing - original draft. Nobuhiko Nagano: Conceptualization, Writing - original draft. Yohei Kitamura: . Fujihiko Iwata: Conceptualization. Tomoo Okada: Conceptualization, Data curation. Ichiro Morioka: Data curation, Writing - original draft. Declaration of Competing Interest None. Acknowledgements We thank the medical and nursing staff of the ward for their assistance in this study. This work was supported by Grants-in-Aid for Young Scientists (grant number: 19K20194) of JSPS KAKENHI. References [1] J.M. Ntambi, M. Miyazaki, Regulation of stearoyl-CoA desaturases and role in metabolism, Prog. Lipid Res. 43 (2004) 91–104. [2] E. Saito, T. Okada, Y. Abe, M. Odaka, Y. Kuromori, F. Iwata, M. Hara, H. Mugishima, Y. Kitamura, Abdominal adiposity is associated with fatty acid desaturase activity in boys: implications for C-reactive protein and insulin resistance, Prostaglandins Leukot. Essent. Fatty Acids 88 (2013) 307–311.
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K. Fuwa, et al. [3] E. Saito, T. Okada, Y. Abe, Y. Kuromori, M. Miyashita, F. Iwata, M. Hara, M. Ayusawa, H. Mugishima, Y. Kitamura, Docosahexaenoic acid content in plasma phospholipids and desaturase indices in obese children, J. Atheroscler. Thromb. 18 (2011) 345–350. [4] T. Venalainen, J. Agren, U. Schwab, V.D. de Mello, A.M. Eloranta, D.E. Laaksonen, V. Lindi, T.A. Lakka, Cross-sectional associations of plasma fatty acid composition and estimated desaturase and elongase activities with cardiometabolic risk in Finnish children – the Panic study, J. Clin. Lipidol. 10 (2016) 82–91. [5] Y. Fujita, T. Okada, Y. Abe, M. Kazama, E. Saito, Y. Kuromori, F. Iwata, M. Hara, M. Ayusawa, H. Izumi, Y. Kitamura, T. Shimizu, Effect of cod liver oil supplementation on the stearoyl-CoA desaturase index in obese children: a pilot study, Obes. Res. Clin. Pract. 9 (2015) 31–34. [6] T. Venalainen, U. Schwab, J. Agren, V. de Mello, V. Lindi, A.M. Eloranta, S. Kiiskinen, D. Laaksonen, T.A. Lakka, Cross-sectional associations of food consumption with plasma fatty acid composition and estimated desaturase activities in Finnish children, Lipids 49 (2014) 467–479. [7] J.K. Yee, C.S. Mao, M.G. Ross, W.N. Lee, M. Desai, A. Toda, S.L. Kjos, R.A. Hicks, M.E. Patterson, High oleic/stearic fatty-acid desaturation index in cord plasma from infants of mothers with gestational diabetes, J. Perinatol. 34 (2014) 357–363. [8] K. Sato, Y. Akiba, Y. Chida, K. Takahashi, Lipoprotein hydrolysis and fat accumulation in chicken adipose tissues are reduced by chronic administration of lipoprotein lipase monoclonal antibodies, Poult. Sci. 78 (1999) 1286–1291. [9] P.J. Voshol, P.C. Rensen, K.W. van Dijk, J.A. Romijn, L.M. Havekes, Effect of plasma triglyceride metabolism on lipid storage in adipose tissue: studies using genetically engineered mouse models, Biochim. Biophys. Acta 1791 (2009) 479–485. [10] J. Kobayashi, H. Hashimoto, I. Fukamachi, J. Tashiro, K. Shirai, Y. Saito, S. Yoshida, Lipoprotein lipase mass and activity in severe hypertriglyceridemia, Clin. Chim. Acta 216 (1993) 113–123. [11] K. Yoshikawa, T. Okada, S. Munakata, A. Okahashi, R. Yonezawa, M. Makimoto, S. Hosono, S. Takahashi, H. Mugishima, T. Yamamoto, Association between serum lipoprotein lipase mass concentration and subcutaneous fat accumulation during neonatal period, Eur. J. Clin. Nutr. 64 (2010) 447–453. [12] N. Nagano, T. Okada, R. Fukamachi, K. Yoshikawa, S. Munakata, Y. Usukura, S. Hosono, S. Takahashi, H. Mugishima, M. Matsuura, T. Yamamoto, Insulin-like growth factor-1 and lipoprotein profile in cord blood of preterm small for gestational age infants, J. Dev. Orig. Health Dis. 4 (2013) 507–512. [13] H.R. Schmelzle, C. Fusch, Body fat in neonates and young infants: validation of skinfold thickness versus dual-energy X-ray absorptiometry, Am. J. Clin. Nutr. 76 (2002) 1096–1100. [14] M. Okazaki, S. Usui, M. Ishigami, N. Sakai, T. Nakamura, Y. Matsuzawa, S. Yamashita, Identification of unique lipoprotein subclasses for visceral obesity by component analysis of cholesterol profile in high-performance liquid
chromatography, Arterioscler. Thromb. Vasc. Biol. 25 (2005) 578–584. [15] N. Nagano, T. Okada, K. Kayama, S. Hosono, Y. Kitamura, S. Takahashi, Delta-6 desaturase activity during the first year of life in preterm infants, Prostaglandins Leukot. Essent. Fatty Acids 115 (2016) 8–11. [16] E. Warensjo, M. Rosell, M.L. Hellenius, B. Vessby, U. De Faire, U. Riserus, Associations between estimated fatty acid desaturase activities in serum lipids and adipose tissue in humans: links to obesity and insulin resistance, Lipids Health Dis. 8 (2009) 37. [17] R. Yonezawa, T. Okada, T. Kitamura, H. Fujita, I. Inami, M. Makimoto, S. Hosono, M. Minato, S. Takahashi, H. Mugishima, T. Yamamoto, N. Masaoka, Very lowdensity lipoprotein in the cord blood of preterm neonates, Metab. Clin. Exp. 58 (2009) 704–707. [18] L.M. Steffen, B. Vessby, D.R. Jacobs Jr., J. Steinberger, A. Moran, C.P. Hong, A.R. Sinaiko, Serum phospholipid and cholesteryl ester fatty acids and estimated desaturase activities are related to overweight and cardiovascular risk factors in adolescents, Int. J. Obes. 32 (2008) 1297–1304. [19] T. Kishino, K. Watanabe, T. Urata, M. Takano, T. Uemura, K. Nishikawa, Y. Mine, M. Matsumoto, K. Ohtsuka, H. Ohnishi, H. Mori, S. Takahashi, H. Ishida, T. Watanabe, Visceral fat thickness in overweight men correlates with alterations in serum fatty acid composition, Clin. Chim. Acta 398 (2008) 57–62. [20] Y.E. Zhou, G.M. Egeland, S.J. Meltzer, S. Kubow, The association of desaturase 9 and plasma fatty acid composition with insulin resistance-associated factors in female adolescents, Metab. Clin. Exp. 58 (2009) 158–166. [21] T. Okada, N. Furuhashi, Y. Kuromori, M. Miyashita, F. Iwata, K. Harada, Plasma palmitoleic acid content and obesity in children, Am. J. Clin. Nutr. 82 (2005) 747–750. [22] A. Kawashima, S. Sugawara, M. Okita, T. Akahane, K. Fukui, M. Hashiuchi, C. Kataoka, I. Tsukamoto, Plasma fatty acid composition, estimated desaturase activities, and intakes of energy and nutrient in Japanese men with abdominal obesity or metabolic syndrome, J. Nutr. Sci. Vitaminol. 55 (2009) 400–406. [23] L. Arab, Biomarkers of fat and fatty acid intake, J. Nutr. 3 (133 suppl) (2003) 925s–932s. [24] M.T. Flowers, The delta9 fatty acid desaturation index as a predictor of metabolic disease, Clin. Chem. 55 (2009) 2071–2073. [25] A. Peter, A. Cegan, S. Wagner, R. Lehmann, N. Stefan, A. Konigsrainer, I. Konigsrainer, H.U. Haring, E. Schleicher, Hepatic lipid composition and stearoylcoenzyme A desaturase 1 mRNA expression can be estimated from plasma VLDL fatty acid ratios, Clin. Chem. 55 (2009) 2113–2120. [26] E. Saito, T. Okada, Y. Abe, M. Odaka, Y. Kuromori, F. Iwata, M. Hara, H. Mugishima, Y. Kitamura, Relationship between estimated fatty acid desaturase activities and abdominal adiposity in Japanese children, Obes. Res. Clin. Pract. 8 (2014) e201–e298.
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