Eiko Nagata

Abdominal obesity is associated with cardiovascular risk in Japanese children and adolescents

Abstract Background: Metabolic syndrome is listed as a risk for atherosclerosis. However, changes in that risk during childhood and adolescence have not been well-documented. It is also unclear whether individuals with abdominal obesity, but with as yet undiagnosed metabolic syndrome, have cardiovascular risks. Methods and results: Ninety-two patients were studied at the Hamamatsu University School of Medicine Department of Pediatrics. Physical measurements including abdominal circumference (AC), body mass index (BMI), body fat (BF), intima media thickness (IMT), arterial elasticity: beta index (Beta), carotid artery compliance (CAC), and Young’s elastic modulus (YEM) using ultrasonography were taken. A positive correlation between systolic blood pressure, AC, BMI, and BF was observed (AC, r=0.717, p<0.001; BMI, r=0.672, p<0.001; BF, r=0.518, p<0.001). IMT showed a weak positive correlation with AC, BMI and BF (AC, r=0.211, p=0.044; BMI, r=0.233, p=0.025; BF, r=0.232, p=0.026). The relationship between AC, BMI, BF and arterial elasticity, especially in AC, positively correlated with beta index and YEM but negatively correlated with CAC. Conclusion: We suggest that AC is the most sensitive marker in the detection of arterial elasticity, even in school age children. Earlier pre-diagnostic intervention, especially in the prevention of abdominal obesity, may reduce the incidence of metabolic syndrome in children and adolescents.

Mamld1 Deficiency Significantly Reduces mRNA Expression Levels of Multiple Genes Expressed in Mouse Fetal Leydig Cells but Permits Normal Genital and Reproductive Development

Although mastermind-like domain containing 1 (MAMLD1) (CXORF6) on human chromosome Xq28 has been shown to be a causative gene for 46,XY disorders of sex development with hypospadias, the biological function of MAMLD1/Mamld1 remains to be elucidated. In this study, we first showed gradual and steady increase of testicular Mamld1 mRNA expression levels in wild-type male mice from 12.5 to 18.5 d postcoitum. We then generated Mamld1 knockout (KO) male mice and revealed mildly but significantly reduced testicular mRNA levels (65-80%) of genes exclusively expressed in Leydig cells (Star, Cyp11a1, Cyp17a1, Hsd3b1, and Insl3) as well as grossly normal testicular mRNA levels of genes expressed in other cell types or in Leydig and other cell types. However, no demonstrable abnormality was identified for cytochrome P450 17A1 and 3β-hydroxysteroid dehydrogenase (HSD3B) protein expression levels, appearance of external and internal genitalia, anogenital distance, testis weight, Leydig cell number, intratesticular testosterone and other steroid metabolite concentrations, histological findings, in situ hybridization findings for sonic hedgehog (the key molecule for genital tubercle development), and immunohistochemical findings for anti-Müllerian hormone (Sertoli cell marker), HSD3B (Leydig cell marker), and DEAD (Asp-Glu-Ala-Asp) box polypeptide 4 (germ cell marker) in the KO male mice. Fertility was also normal. These findings imply that Mamld1 deficiency significantly reduces mRNA expression levels of multiple genes expressed in mouse fetal Leydig cells but permits normal genital and reproductive development. The contrastive phenotypic findings between Mamld1 KO male mice and MAMLD1 mutation positive patients would primarily be ascribed to species difference in the fetal sex development.

MAMLD1 and 46,XY disorders of sex development.

MAMLD1 (mastermind-like domain containing 1) is a recently discovered causative gene for 46,XY disorders of sex development (DSD), with hypospadias as the salient clinical phenotype. To date, microdeletions involving MAMLD1 have been identified in six patients, and definitive mutations (nonsense and frameshift mutations that are predicted to undergo nonsense mediated mRNA decay [NMD]) have been found in six patients. In addition, specific MAMLD1 cSNP(s) and haplotype may constitute a susceptibility factor for hypospadias. Furthermore, in vitro studies have revealed that (1) the mouse homolog is expressed in fetal Sertoli and Leydig cells around the critical period for sex development; (2) transient Mamld1 knockdown results in significantly reduced testosterone production primarily because of compromised 17α-hydroxylation and Cyp17a1 expression in Murine Leydig tumor cells; (3) MAMLD1 localizes to the nuclear bodies and transactivates the promoter activity of a non-canonical Notch target gene hairy/enhancer of split 3, without demonstrable DNA-binding capacity; and (4) MAMLD1 is regulated by steroidogenic factor 1 (SF1). These findings suggest that the MAMLD1 mutations cause 46,XY DSD primarily because of compromised testosterone production around the critical period for sex development. Further studies will provide useful information for the molecular network involved in fetal testosterone production.

Japanese founder duplications/triplications involving BHLHA9 are associated with split-hand/foot malformation with or without long bone deficiency and Gollop-Wolfgang complex

BackgroundLimb malformations are rare disorders with high genetic heterogeneity. Although multiple genes/loci have been identified in limb malformations, underlying genetic factors still remain to be determined in most patients.MethodsThis study consisted of 51 Japanese families with split-hand/foot malformation (SHFM), SHFM with long bone deficiency (SHFLD) usually affecting the tibia, or Gollop-Wolfgang complex (GWC) characterized by SHFM and femoral bifurcation. Genetic studies included genomewide array comparative genomic hybridization and exome sequencing, together with standard molecular analyses.ResultsWe identified duplications/triplications of a 210,050 bp segment containing BHLHA9 in 29 SHFM patients, 11 SHFLD patients, two GWC patients, and 22 clinically normal relatives from 27 of the 51 families examined, as well as in 2 of 1,000 Japanese controls. Families with SHFLD- and/or GWC-positive patients were more frequent in triplications than in duplications. The fusion point was identical in all the duplications/triplications and was associated with a 4 bp microhomology. There was no sequence homology around the two breakpoints, whereas rearrangement-associated motifs were abundant around one breakpoint. The rs3951819-D17S1174 haplotype patterns were variable on the duplicated/triplicated segments. No discernible genetic alteration specific to patients was detected within or around BHLHA9, in the known causative SHFM genes, or in the exome.ConclusionsThese results indicate that BHLHA9 overdosage constitutes the most frequent susceptibility factor, with a dosage effect, for a range of limb malformations at least in Japan. Notably, this is the first study revealing the underlying genetic factor for the development of GWC, and demonstrating the presence of triplications involving BHLHA9. It is inferred that a Japanese founder duplication was generated through a replication-based mechanism and underwent subsequent triplication and haplotype modification through recombination-based mechanisms, and that the duplications/triplications with various haplotypes were widely spread in Japan primarily via clinically normal carriers and identified via manifesting patients. Furthermore, genotype-phenotype analyses of patients reported in this study and the previous studies imply that clinical variability is ascribed to multiple factors including the size of duplications/triplications as a critical factor.

Effects of maternal high-fat diet on serum lipid concentration and expression of peroxisomal proliferator-activated receptors in the early life of rat offspring.

Peroxisomal proliferator-activated receptors (PPARs) play an important role in the regulation of lipid metabolism. The aim of this study was to investigate the effects of a maternal high-fat (HF) diet on serum lipid concentration and PPAR gene expression in liver and adipose tissue in the early life of the rat offspring. Female Sprague-Dawley rats were fed either an HF or control (CON) diet 6 weeks before mating and throughout gestation and lactation. Blood and tissue samplings of male offspring were carried out at birth or weaning. Birth weights were similar and serum triglyceride (TG) and nonesterified fatty acid (NEFA) levels showed no significant difference between HF and CON newborns, despite greatly increased hepatic PPARα mRNA expression in the HF newborns (p<0.05). Both HF newborns and weanlings revealed significantly decreased hepatic PPARγ expression compared with controls (p<0.0001). Hepatic PPARα expression in the HF weanlings was reduced markedly compared with CON weanlings (p<0.0001) and showed a negative correlation with serum TG levels (r=-0.743, p<0.05). However, epididymal expression of PPARγ in the HF weanlings was upregulated significantly compared with controls (p<0.05) and demonstrated a positive correlation with epididymal fat mass (r=0.733, p<0.05). These were accompanied by obesity as well as a rise in serum TG by 79% (p<0.05) and NEFA concentration by 36% (p<0.05) in these HF weanlings. Our findings suggest that maternal HF diet leads to alterations in PPAR gene expression in the weanling offspring, which is associated with the disturbed lipid homeostasis.

Carbenoxolone Alters the Morphology of Adipose Tissues and Downregulates Genes Involved in Adipogenesis, Glucose Transport and Lipid Metabolism in High-Fat Diet-fed Mice

Glucocorticoid (GC) excess promotes adipose tissue accumulation, and 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) plays an important role in the local amplification of GC. Therefore, in this study, we investigated the effects of carbenoxolone (CBX), an 11β-HSD1 inhibitor, on morphological changes in visceral fat, and the expression of genes involved in adipogenesis and lipid metabolism in high-fat (HF) diet-fed mice. Mice were fed a HF diet from 5 weeks of age. At 10 weeks of age, the mice received an intraperitoneal injection of CBX or vehicle every day for 2 weeks. CBX decreased body weight and visceral fat mass, and improved insulin sensitivity in HF-fed mice. This was accompanied by reduced adipocyte size and a decrease in large-sized adipocytes in visceral fat. The expression of adipogenesis (PPARγ and C/EBPα), glucose transport (GLUT4) and lipid metabolism (LPL, ATGL, and HSL)-related genes were suppressed in CBX mice. CBX treatment induced beneficial morphological changes in visceral fat and decreased the expression of adipogenesis, glucose transport and lipid metabolism-related genes. These findings reveal a potential mechanism underling the effects of CBX on reduced fat accumulation and improved insulin sensitivity.

Altered Gene Expressions of Ghrelin, PYY, and CCK in the Gastrointestinal Tract of the Hyperphagic Intrauterine Growth Restriction Rat Offspring

Intrauterine growth restriction (IUGR) is associated with a substantially greater incidence of metabolic syndrome in adulthood. Animal studies have shown that IUGR offspring are hyperphagic during the early postnatal period and therefore exhibit obesity. The molecular mechanisms underlying food intake regulation in the gastrointestinal tract have not been clarified in IUGR. In the present study, we utilized a rat model of IUGR by restricting the food intake of the mother (50% of the normal intake, ad libitum; FR group) from day 7 of gestation until delivery. Pups from undernourished mothers were fostered by control mothers. We examined the food intake and assessed the gene expressions of ghrelin, peptide YY (PYY), and cholecystokinin (CCK) in the alimentary tract of male newborns (postnatal day1) and adult offspring (age, 7 months). Compared to the offspring whose mothers received the standard diet ad libitum (CON offspring), FR offspring were hyperphagic from the weaning time until the end of the experiment, and resulted in a heavier final weight. Both newborn and adult FR offspring had higher ghrelin gene expression in the stomach and higher ghrelin plasma levels than did the controls. Although the gastrointestinal gene expressions and plasma levels of the anorexic peptides, PYY and CCK, were elevated in the FR newborns, they decreased in the FR adults. Our findings suggest that the altered gene expressions of orexigenic and anorexigenic gut peptides in the gastrointestinal tract in the maternal undernutrition-induced IUGR offspring provide a potential mechanism to explain hyperphagia and obesity seen in these offspring.

The lipid fraction of human milk initiates adipocyte differentiation in 3T3-L1 cells.

BACKGROUND The prevalence of childhood obesity has increased worldwide over the past decade. Despite evidence that human milk lowers the risk of childhood obesity, the mechanism is not fully understood. AIMS We investigated the direct effect of human milk on differentiation of 3T3-L1 preadipocytes. STUDY DESIGN AND SUBJECTS 3T3-L1 preadipocytes were treated with donated human milk only or the combination of the standard hormone mixture; insulin, dexamethasone (DEX), and 3-isobututyl-1-methylxanthine (IBMX). Furthermore, the induction of preadipocyte differentiation by extracted lipids from human milk was tested in comparison to the cells treated with lipid extracts from infant formula. Adipocyte differentiation, specific genes as well as formation of lipid droplets were examined. RESULTS We clearly show that lipids present in human milk initiate 3T3-L1 preadipocyte differentiation. In contrast, this effect was not observed in response to lipids present in infant formula. The initiation of preadipocyte differentiation by human milk was enhanced by adding the adipogenic hormone, DEX or insulin. The expression of late adipocyte markers in Day 7 adipocytes that have been induced into differentiation with human milk lipid extracts was comparable to those in control cells initiated by a standard adipogenic hormone cocktail. CONCLUSIONS These results demonstrate that human milk contains bioactive lipids that can initiate preadipocyte differentiation in the absence of the standard adipogenic compounds via a unique pathway.

Dynamics of endogenous glucocorticoid secretion and its metabolism in Kawasaki disease

OBJECTIVE Kawasaki disease (KD) is a severe inflammatory disease that occurs in childhood. Recently, the initial corticosteroid therapy for KD has been reconsidered because its efficacy is controversial. The aim of this study was to evaluate the dynamic change in endogenous glucocorticoid levels and their relation with 11beta-hydroxysteroid dehydrogenase (11beta-HSD) activity in the acute phase of KD. STUDY DESIGN Sixteen KD patients were investigated. Cortisol and cortisone levels, the cortisol/cortisone ratio and C-reactive protein (CRP) levels were measured on admission, before the first intravenous immunoglobulin (IVIG) therapy and convalescence. RESULTS The 16 patients were divided into two groups. Group A included patients who received the first IVIG on admission and blood samples were collected before the first IVIG and convalescence. Group B included patients whose blood samples were collected at three different time points (on admission, before the first IVIG, and convalescence). CRP and cortisol levels and the cortisol/cortisol ratio were markedly higher before the first IVIG than those of convalescence in all patients except in one patient. In Group B patients, both serum cortisol levels and the cortisol/cortisone ratio on admission were significantly increased compared with those before the first IVIG (cortisol: p<0.005, cortisol/cortisone: p<0.001). CONCLUSIONS Decreases in cortisol levels and the cortisol/cortisone ratio before the first IVIG may be explained by a reduction in adrenal secretion and/or local glucocorticoid action through 11beta-HSD activity. These findings suggest that exogenous glucocorticoid treatment in combination with the first IVIG at the acute stage may play a synergetic role in KD.

Haplotype analysis of ESR2 in Japanese patients with spermatogenic failure

The prevalence of spermatogenic failure (SF) has gradually increased during the past few decades at least in several countries. Although multiple factors would be involved in this phenomenon, one important factor would be excessive estrogen effects via estrogen receptors (ERs). Thus, we performed haplotype analysis of ESR2 encoding ERβ in 125 Japanese SF patients and 119 age-matched control males, using single nucleotide polymorphisms (SNPs) 1–9 that are widely distributed on the ∼120-kb genomic sequence of ESR2. Consequently, a linkage disequilibrium (LD) block was detected in an ∼60-kb region encompassing SNPs 2–7 in both groups, and four major estimated haplotypes were identified within the LD block. Furthermore, the most prevalent ‘TGTAGA’ haplotype was found to be significantly associated with SF, with the P-value obtained by the Cochran–Armitage trend test (0.0029) being lower than that obtained by a 100 000-times permutation test (0.0038) to cope with the problem of multiple comparisons. The results, in conjunction with our previous data indicating lack of a susceptibility factor on ESR1 encoding ERα, imply that the specific ‘TGTAGA’ haplotype of ESR2 raises the susceptibility to the development of SF.