Mika Saito

Osaka City University, Ōsaka, Ōsaka, Japan

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Publications (5)10.96 Total impact

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    ABSTRACT: Chorioamnionitis (CAM) can initiate fetal lung injury resulting in neonatal bronchopulmonary dysplasia (BPD). While neonates with BPD have higher amniotic fluid concentrations of proinflammatory cytokines, overexpression of transforming growth factor (TGF)-beta(1) also appears important in the pathogenesis of BPD. The aim of this study was to investigate the relationship between TGF-beta(1) and CAM-induced fetal lung injury. Forty-four amniotic fluid samples were obtained at delivery of preterm infants (median gestation, 28 weeks; birth weight, 908 g). TGF-beta(1) and interleukin (IL)-6 concentrations in the amniotic fluid were measured with ELISA. Both TGF-beta(1) and IL-6 concentrations in the amniotic fluid increased with increasing histological severity of CAM (each p < 0.0001). The presence of both BPD and histological CAM was associated with significantly higher amniotic fluid TGF-beta(1) and IL-6 concentrations than the presence of BPD without histological CAM, or the absence of both (each p < 0.0001). Both concentrations also correlated with the duration of oxygen administration in the neonates (each p < 0.0001). Amniotic fluid TGF-beta(1) seems to be important in CAM-induced fetal lung injury progressing to neonatal BPD.
    Neonatology 04/2009; 96(3):156-61. · 2.57 Impact Factor
  • Journal of Dermatological Science 08/2008; 51(1):62-5. · 3.52 Impact Factor
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    ABSTRACT: The immature brain is more susceptible to seizures than mature brains but less vulnerable to seizure-induced neuronal loss. We studied age-related susceptibility and vulnerability to kainic acid-induced status epilepticus (KASE) in rats in terms of hippocampal expression of brain-derived neurotrophic factor (BDNF) and tyrosine kinase B receptor (TrkB). Immunohistochemical and Western analysis were performed after kainic acid (KA)-induced status epilepticus (SE). KA doses required to induce SE increased from 1.5 mg/kg in 1-week-old rats to 10 mg/kg at 4 weeks of older. After SE the older rats showed spontaneous seizures and hippocampal pyramidal neuronal loss-unlike rats under 4 weeks old. Hippocampal BDNF protein expression had increased fivefold in 1-week-old rats and threefold in 8-week-old rats 1 day after SE, returning to baseline 2 days after SE. TrkB expression showed little effect from KASE at either age. These results indicated that the critical period as for vulnerability to SE was the age of 4-week-old and older in the rat. Since the response patterns of BDNF and TrkB to SE were similar between neonatal and the adult rats, our study revealed that the observed transient upregulation of BDNF did not contribute to cause epilepsy in neonatal rats.
    Osaka city medical journal 01/2008; 53(2):63-71.
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    ABSTRACT: Lung injury alters the expression and release of growth factors that disrupt postnatal pulmonary development in newborns and causes chronic lung disease (CLD). The effect of these factors, released into the airways of newborns with CLD, on cell proliferation and collagen production was characterized in vitro. Human fetal lung fibroblast and alveolar-epithelial-like cell lines (FHs 738Lu and A549, respectively) were exposed to tracheal effluents from infants with CLD (mean gestation, 24.7 +/- 0.9 wk; birth weight, 666 +/- 85 g; postnatal age, 0-62 d). In both cell types, proliferation was assessed by measuring [(3)H]-thymidine uptake; in fibroblasts, collagen production was analyzed by measuring [(3)H]-proline incorporation. The activity of specific growth factors in effluents was determined using anti-growth factor antibodies and the growth factors themselves. Growth factors in tracheal effluents promoted proliferation in a dose-dependent manner and caused up to a 10.2- and 3.1-fold increase in thymidine uptake by fibroblasts and epithelial cells, respectively. Collagen production by fibroblasts increased dose dependently, peaking at 177% of baseline. Antibody against transforming growth factor beta-1 (TGF-beta(1)) inhibited proliferation and the increase in collagen production by 31% (p = 0.01) and 14% (p = 0.045), respectively. Antibody against hepatocyte growth factor (HGF) inhibited proliferation of epithelial cells (25%, p = 0.039). The effects of exogenous TGF-beta(1) on fibroblasts and HGF on epithelial cells resembled those of tracheal effluents. Potent mitogenic and differentiating substances are released into the tracheal effluents of newborns with CLD. TGF-beta(1) may worsen CLD by inducing fibrosis whereas HGF may favor resolution by promoting epithelialization.
    Pediatric Research 07/2004; 55(6):960-5. · 2.67 Impact Factor
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    ABSTRACT: To evaluate the role of growth factors in amniotic fluid and in human milk on gastrointestinal adaptation of the fetus and very low-birth-weight infants, the effects of these fluids and multiple growth factors were investigated in a human fetal small intestinal cell line (FHs 74 Int). After FHs 74 Int cells were incubated with amniotic fluid, human milk, or recombinant growth factors, growth-promoting activity was measured by [3H]-thymidine incorporation into cells. Incubating cells with amniotic fluid or human milk promoted growth dose dependently. Genistein almost completely inhibited growth-promoting activity in amniotic fluid P = 0.002), and growth was partially inhibited by antibodies against epidermal growth factor (EGF) (P = 0.047), insulin-like growth factor-1 (IGF-1, P = 0.047), or fibroblast growth factor (FGF, P = 0.014). This activity in human milk was inhibited almost completely by genistein (P < 0.0001) and partially inhibited by antibodies against EGF (P = 0.036), IGF-1 (P = 0.009), FGF (P = 0.004), hepatocyte growth factor (HGF, P = 0.001), or transforming growth factor-alpha (TGF-alpha, P = 0.001). Although recombinant EGF, IGF-1, FGF, HGF, and TGF-alpha elicited a synergistic trophic response on cultured cells, the response was much less than with amniotic fluid or with human milk. In aminiotic fluid and in human milk, EGF, IGF-1, FGF, HGF, and TGF-alpha have a strong trophic effect on immature intestinal cells and may be involved in perinatal gastrointestinal adaptation.
    Journal of Pediatric Gastroenterology and Nutrition 05/2002; 34(5):524-8. · 2.20 Impact Factor