Yuki Kuromori

Abdominal adiposity is associated with fatty acid desaturase activity in boys: Implications for C-reactive protein and insulin resistance

Fatty acid composition, which is altered in patients with abdominal obesity, is influenced not only by dietary intake but also by the desaturating enzymes stearoyl-CoA desaturase (SCD), delta-6 desaturase (D6D) and delta-5 desaturase (D5D). We investigated desaturase activities and their associations with metabolic risk factors, C-reactive protein levels (CRP) and insulin resistance in Japanese children. There were 237 school children in this study; 115 were boys. The fatty acid composition of plasma phospholipids was analyzed, and the following desaturase activities were estimated: SCD (16:1n-7/16:0 and 18:1n-9/18:0), D6D (20:3n-6/18:2n-6) and D5D (20:4n-6/20:3n-6). D6D and D5D activities, but not SCD activity, were significantly associated with triglyceride levels, high-density lipoprotein cholesterol levels and insulin resistance in both sexes, and with CRP levels in boys. In addition, increased abdominal adiposity was significantly associated with increased D6D activity, and decreased D5D activity and insulin resistance in both sexes, and with increased CRP levels in boys. The n-6 polyunsaturated fatty acid desaturation pathway may be associated with metabolic risk factors, insulin resistance and increased inflammation in children with abdominal obesity, especially in boys.

Characteristics of obese children with low content of arachidonic acid in plasma lipids

Background: Although there have been many studies on the relationship between obesity and long‐chain polyunsaturated fatty acid (LCPUFA), the results and their interpretation are controversial, especially in children. Arachidonic acid (AA), the product of n‐6 LCPUFA, is reported to be related to insulin resistance. The purpose of the present paper was to investigate the LCPUFA profile in obese children and mechanisms that contribute to reduced AA content.

Relationship between estimated fatty acid desaturase activities and abdominal adiposity in Japanese children

BACKGROUND Abdominal obesity alters the composition of plasma and tissue long chain fatty acids and thus affects a number of important physiological functions relating to the development of cardiometabolic diseases. The fatty acid composition is modulated by desaturases; stearoyl-CoA desaturase (SCD), delta-6 desaturase (D6D) and delta-5 desaturase (D5D). Therefore, we examined the relationship between the desaturase activities and abdominal adiposity. METHODS One hundred eighty-one children (98 males, 83 females), including 42 children with abdominal obesity having waist to height ratio (WHtR) >0.5, were recruited. Fatty acid composition in plasma phospholipids was analyzed by gas chromatography after overnight fast, and SCD activity was estimated by 18:1/18:0 ratio. RESULTS In children without abdominal obesity, WHtR correlated positively with D6D activity (r = 0.252, p = 0.0027) and negatively with SCD activity (r = −0.289, p = 0.0006), but not with D5D activity (r = −0.159, p = 0.0607). While in children with abdominal obesity, WHtR had a positive association with SCD activity (r = 0.332, p = 0.0315), but not with D6D (r = 0.267, p = 0.0847) or D5D activity (r = 0.008, p = 0.9600). CONCLUSION The relationship between the desaturase activities and abdominal adiposity altered in children with abdominal obesity. Especially, SCD activity demonstrated a U-shaped association with WHtR.

Assessment of individual changes in body fatness in boys during early pubertal period

Abstract Background : In order to know whether the changes in indexes of overweight, body mass index (BMI; kg/m2) and percentage of overweight (POW) (%), really represent the tendency toward obesity, we examined longitudinal individual changes in these indexes, and the change in body composition in boys during early pubertal period.

Non-high-density Lipoprotein Cholesterol Levels in Japanese Obese Boys with Metabolic Syndrome.

AIM To investigate the relationship between the clustering of metabolic syndrome (MetS) components and non-high-density lipoprotein cholesterol (non-HDL-C) levels in Japanese obese boys. METHODS Subjects were 58 obese boys aged 12.0±2.6 years, which were categorized into three subgroups: abdominal obesity, pre-MetS (abdominal obesity＋1 component), and MetS (abdominal obesity＋2 or more components). RESULTS Sixteen (27.6%) and 32 (55.2%) of the obese boys were diagnosed as pre-MetS and MetS, respectively. The mean non-HDL-C level in total subjects was 139.0±36.4 mg/dl and that in boys with abdominal obesity, pre-MetS, and MetS were 112.9±34.4, 135.4±37.9, and 149.0±32.6 mg/dl, respectively (p=0.0183, ANOVA). CONCLUSIONS Japanese obese boys with MetS exhibited elevated non-HDL-C levels, suggesting that they may have a higher risk for the development of atherosclerotic diseases.

Concentrations of very long-chain fatty acid in whole blood are associated with cardiovascular risk factors in children

BACKGROUND Fatty acid metabolism has a close relationship with metabolic syndrome. Saturated very long-chain fatty acid (hexacosanoic acid; C26:0) was recently reported to be associated with cardiovascular risk factors in adults. METHODS Eighty-eight children (47 male, 41 female; average age, 10.9 y) participated in this study. Concentrations of C26:0 in whole blood were measured. RESULTS Compared with reported concentrations in the whole blood of adults, children had lower C26:0 concentrations, which had a close relationship with abdominal obesity, increased concentrations of low-density lipoprotein cholesterol and high blood pressure. C26:0 concentrations increased with increasing number of risk factors. CONCLUSIONS Elevation of C26:0 concentrations may be one of the metabolic features of children with cardiovascular risk factors.

Abdominal Obesity, Insulin Resistance, and Very Low-Density Lipoprotein Subclass Profile in Japanese School Children

Background: Alterations in the very low-density lipoprotein (VLDL) subclass profile have been demonstrated in obese and insulin resistant adults; however, little information on VLDL subclasses is available in children. We determined the association between abdominal adiposity, insulin resistance, and triglyceride (TG) levels in each VLDL subclass in Japanese school children. Methods: One hundred sixty-four children (79 boys and 85 girls), 10.9 ± 1.6 years of age (mean ± SD), were recruited. We obtained the waist-to-height ratio (WHtR), lipid profile, and HOMA-R data from all children. The VLDL subclass profile was analyzed by HPLC. Results: Children of either gender with abdominal obesity (WHtR ≥ 0.5) had higher concentrations of large, medium, and small VLDL-TG in conjunction with the shift to larger size and elevated HOMA-R. The WHtR was positively related to concentrations of large (boys: r = 0.5800, p < 0.0001; girls: r = 0.3841, p = 0.0003) and medium (r = 0.5265, p < 0.0001; r = 0.3320, p = 0.0019) VLDL-TG. The small VLDL-TG concentration was positively correlated to the WHtR in boys (r = 0.4902, p < 0.0001), but not girls. In multiple regression analyses, the WHtR was an independent determinant of large, medium, and small VLDL-TG concentrations in boys, but not in girls, taking HOMA-R into account. Conclusions: Abdominal obesity was associated with the VLDL subclass profile in Japanese school children; however, the impact of abdominal adiposity on the VLDL subclass alteration demonstrated a gender difference.

Apolipoprotein A-V level may contribute to the development of obesity-associated dyslipidemia

AIM In a mice study, insulin suppressed apolipoprotein A-V (apoA-V) gene expression in a dose dependent manner. Thus, we investigated the association between apoA-V levels and dyslipidemias in obese children with hyperinsulinemia. METHODS The subjects were 17 obese children (15 male, 2 female) aged 11.8 ± 2.4 years. Total cholesterol (TC), high-density lipoprotein cholesterol (HDLC), triglyceride (TG), apoA-V and insulin levels were determined. RESULTS Obese children with hyperinsulinemia had greater percent overweight, higher TG level, lower HDLC level and lower apoA-V level than those without hyperinsulinemia. In simple regression analysis, apoA-V level correlated negatively with TG (r = -0.613, p = 0.0152) and insulin levels (r = -0.566, p = 0.0279), and positively correlated with HDLC (r = 0.811, p = 0.0002). In stepwise regression analysis, insulin level emerged as the independent determinant of TG level after apoA-V level was taken into account, whereas apoA-V emerged as the independent determinant of HDLC level after adjusting for insulin level. CONCLUSIONS Insulin may be a potent regulator of serum apoA-V level in obesity, and apoA-V level may partly contribute to the development of obesity-associated dyslipidemia.

Effect of cod liver oil supplementation on the stearoyl-CoA desaturase index in obese children: A pilot study

To investigate the effects of n-3 polyunsaturated fatty acids on stearoyl-CoA desaturase (SCD) activity, we treated 10 obese children (mean age: 12.9 years) with cod liver oil once daily for 12 weeks. The effects of cod liver oil supplementation on SCD activity, as estimated by the palmitoleate/palmitate ratio, depended on the docosahexaenoic acid (DHA) contents at baseline. Baseline DHA contents were negatively correlated with baseline SCD activity. After the treatment, baseline DHA contents were found to be significantly associated with the reduction of SCD activity. Cod liver oil supplementation may be a complementary treatment for obese children with low baseline contents of DHA.