Zenro Kizaki

SAMD9 mutations cause a novel multisystem disorder, MIRAGE syndrome, and are associated with loss of chromosome 7

Adrenal hypoplasia is a rare, life-threatening congenital disorder. Here we define a new form of syndromic adrenal hypoplasia, which we propose to term MIRAGE (myelodysplasia, infection, restriction of growth, adrenal hypoplasia, genital phenotypes, and enteropathy) syndrome. By exome sequencing and follow-up studies, we identified 11 patients with adrenal hypoplasia and common extra-adrenal features harboring mutations in SAMD9. Expression of the wild-type SAMD9 protein, a facilitator of endosome fusion, caused mild growth restriction in cultured cells, whereas expression of mutants caused profound growth inhibition. Patient-derived fibroblasts had restricted growth, decreased plasma membrane EGFR expression, increased size of early endosomes, and intracellular accumulation of giant vesicles carrying a late endosome marker. Of interest, two patients developed myelodysplasitc syndrome (MDS) that was accompanied by loss of the chromosome 7 carrying the SAMD9 mutation. Considering the potent growth-restricting activity of the SAMD9 mutants, the loss of chromosome 7 presumably occurred as an adaptation to the growth-restricting condition.

The distributions of apoptotic cells in the medial preoptic areas of male and female neonatal rats

The medial preoptic area (MPA) of the hypothalamus of the rat contains two sexually dimorphic nuclei, the periventricular preoptic nucleus (PVpo) and the medial preoptic nucleus (MPN). To examine the relationship between sexual dimorphism and neuronal death, we examined the number of apoptotic cells in the subdivisions of the MPA in neonatal rats of postnatal days 1 (P1), 4 (P4), 7 (P7) and 14 (P14). Apoptotic cells in these areas were classified according to their progression into three stages. P1 and P4 rats contained many apoptotic cells in the subfield along the third ventricle, including the PVpo, and their number was significantly larger in P1 males: in particular, the number of early-stage cells was larger in males than females. The number of apoptotic cells in the MPN was increased in P4 and P7 rats, although no significant sexual differences were seen in the total number or in the number of each progressive stage of apoptotic cells. In P14 rats, very few apoptotic cells were seen in the MPA. Our data revealed that the distribution of apoptotic cells in the MPA of developing rats depends on the sexuality, subdivision of the area and postnatal period.

Stimulation of N-methyl-D-aspartate (NMDA) receptors inhibits neuronal migration in embryonic cerebral cortex: a tissue culture study

We performed a tissue culture study using embryonic rat brain to investigate the effect of excessive stimulation of NMDA receptors on neuronal migration in the cerebral cortex. After progenitor cells in the ventricular zone of E16 cerebral cortex explants were labeled with [(3)H]thymidine, the explants were cultured for 48 h, and distributions of labelled cells were evaluated autoradiographically. Stimulation of NMDA receptors by NMDA and ibotenate, NMDA receptor agonists added to the culture medium in separate studies, caused percentages of labeled cells to decrease significantly in the intermediate zone and increase in the ventricular zone. The results suggest that in rat cerebral cortex, agonist stimulation of NMDA receptors inhibits neuronal migration.

Reduced oxygen protocol decreases the incidence of threshold retinopathy of prematurity in infants of <33 weeks gestation

Background:  The relationship between oxygen and retinopathy of prematurity (ROP) has been studied frequently, and a pulse oximeter has the potential to facilitate the control of oxygen fluctuation in neonates. The objective of the present study was to compare the incidence of threshold ROP (stage 3 requiring laser treatment and stage 4) in infants of <33 weeks gestation after implementing a new clinical O2 management practice.

The Effect of Carnitine on Ketogenesis in Perfused Livers from Juvenile Visceral Steatosis Mice with Systemic Carnitine Deficiency

Juvenile visceral steatosis (JVS) mice have been reported to have systemic carnitine deficiency, and the carnitine concentration in the liver of JVS mice was markedly lower than that of controls (11.6 ± 2.6 versus 393.5 ± 56.4 nmol/g of wet liver). To evaluate the role of carnitine in mitochondrial β-oxidation in liver, we examined the effects of carnitine on ketogenesis in perfused liver from control and JVS mice. In control mice, ketogenesis was increased by the infusion of 0.3 mM oleate, but not by L-carnitine. In contrast, although ketogenesis in JVS mice was not increased by the infusion of oleate, it was increased 2.5-fold by the addition of 1000μM L-carnitine. Addition of 50, 100, and 200 μM L-carnitine increased ketogenesis in a dose-dependent manner. The infusion of 0.3 mM octanoate or butyrate increased ketogenesis in a carnitine-independent fashion in both control and JVS mice. These findings suggest that endogenous long chain fatty acids from accumulated triglycerides may be used as substrates in the presence of carnitine in JVS mice. The relationship between ketogenesis and free carnitine concentration was examined in livers from JVS mice. Ketogenesis increased as free carnitine levels increased until concentrations exceeded about 100 nmol/g of wet liver (340 μM). The free carnitine concentration required for half-maximal ketone body production in liver of JVS mice was 45μM (13 nmol/g of wet liver), which corresponds to a Km value of carnitine palmitoyltransferase I. We conclude that carnitine is a rate-limiting factor for β-oxidation in liver only when the carnitine level in liver is very low.

HLA-class II and class I genotypes among Japanese children with Type 1A diabetes and their families

Sugihara S, Ogata T, Kawamura T, Urakami T, Takemoto K, Kikuchi N, Takubo N, Tsubouchi K, Horikawa R, Kobayashi K, Kasahara Y, Kikuchi T, Koike A, Mochizuki T, Minamitani K, Takaya R, Mochizuki H, Nishii A, Yokota I, Kizaki Z, Mori T, Shimura N, Mukai T, Matsuura N, Fujisawa T, Ihara K, Kosaka K, Kizu R, Takahashi T, Matsuo S, Hanaki K, Igarashi Y, Sasaki G, Soneda S, Teno S, Kanzaki S, Saji H, Tokunaga K, Amemiya S, and The Japanese Study Group of Insulin Therapy for Childhood and Adolescent Diabetes (JSGIT). HLA‐class II and class I genotypes among Japanese children with Type 1A diabetes and their families.

Hematopoietic Contribution to Skeletal Muscle Regeneration in Acid α-Glucosidase Knockout Mice

Recent studies have shown that cells from bone marrow (BM) can give rise to differentiated skeletal muscle fibers. However, the mechanisms and identities of the cell types involved remain unknown. We performed BM transplantation in acid α-glucosidase (GAA) knockout mice, a model of glycogen storage disease type II, and our observations suggested that the BM cells contribute to skeletal muscle fiber formation. Furthermore, we showed that most CD45+:Sca1+ cells have a donor character in regenerating muscle of recipient mice. Based on these findings, CD45+:Sca1+ cells were sorted from regenerating muscles. The cell number was increased with granulocyte colony-stimulating factor after cardiotoxin injury, and the cells were transplanted directly into the tibialis anterior (TA) muscles of GAA knockout mice. Sections of the TA muscles stained with anti-laminin-α2 antibody showed that the number of CD45+:Sca1+ cells contributing to muscle fiber formation and glycogen levels were decreased in transplanted muscles. Our results indicated that hematopoietic stem cells, such as CD45+:Sca1+ cells, are involved in skeletal muscle regeneration.

The Relationship in Japanese Infants between a Genetic Polymorphism in the Promoter Region of the Insulin-Like Growth Factor I Gene and the Plasma Level

Background: Evidence is accumulating that the promoter region of the insulin-like growth factor I (IGF-I) gene polymorphism and low levels of IGF-I are associated with type 2 diabetes, cardiovascular disease and birth weight; however, the number of wild-type alleles is different in each country. Objectives: This study aimed to examine the 737/738 marker, a cytosine–adenine repeat in the promoter region of the IGF-I gene polymorphism, and plasma IGF-I levels in Japanese infants and analyze the genetic background. Methods: Data were collected for 15 months in Kyoto Prefectural University of Medicine. The body composition parameters of all infants were determined at birth. At 5 days after birth, we took blood samples to measure the product size of the promoter region of the IGF-I gene polymorphism and plasma IGF-I. Results: In a population-based sample of 160 subjects, 6 different alleles and 16 genotypes were identified in the promoter region of the IGF-I gene polymorphism. The existence of a 196-bp allele has proved to result in a low plasma IGF-I level, a small head and chest circumference (p < 0.05) and no significant for premature birth, short-birth height and low-birth weight. Conclusions: This is the first study showing the role of the promoter region of the IGF-I gene polymorphism and the level of plasma IGF-I and body composition parameters in Japanese infants. Our results suggest genetical influence on prenatal growth and serum IGF-I levels.

Effect of sports activity on carnitine metabolism Measurement of free carnitine, γ-butyrobetaine and acylcarnitines by tandem mass spectrometry

The effects of sports activity on carnitine metabolism were studied using mass spectrometry. Serum levels of free carnitine, acylcarnitines (acetylcarnitine, propionylcarnitine, C4-, C5- and C8-acylcarnitine) and gamma-butyrobetaine, a carnitine precursor, were determined by tandem mass spectrometry in liquid secondary ion mass ionization mode. The coefficients of variation at three different concentrations were 2.8-7.9% for gamma-butyrobetaine, and 1.2 to approximately 6.7% for free carnitine. The recoveries added to serum were 109.1% for gamma-butyrobetaine, 89.3% for free carnitine. Sports activity caused increased serum levels of gamma-butyrobetaine, acetylcarnitine, C4- and C8-acylcarnitines and decreased serum levels of free carnitine. This method requires a small amount of sample volume (20 microl of serum) and short total instrumental time for the analysis (1 h for preparation, 2 min per sample for mass spectrometric analysis). Therefore, this method can be applied to study carnitine metabolism under various conditions that affect fatty acid oxidation.

Increased Urinary Hva Levels in Neuroblastoma Screens Related to Diet, Not Tumor

At present, urinary vanillylmandelic acid (VMA) and/or homovanillic acid (HVA), metabolites of catecholamines, are the most sensitive diagnostic markers of neuroblastoma. They can be measured by the high-performance liquid chromatographic method, which has been used to screen for neuroblastoma in infants in Japan. From 6486 urine samples of 18-month-old children, 103 samples showed high HVA levels over the cutoff point for neuroblastoma, and most of them also showed markedly high levels of 5-hydroxyindoleacetic acid (5-HIAA), a metabolite of serotonin. One of the causes of high HVA excretion might be due to the ingestion of banana, common weaning food in early childhood. Our study showed that it is better to restrict banana ingestion within 24 hours before taking a urine sample for diagnosis of neuroblastoma and that 5-HIAA is a good marker of a pseudopositive result due to banana ingestion.