Measurement of cerebral oxygenation in neonates after vaginal delivery and cesarean section using full-spectrum near infrared spectroscopy

To investigate whether or not the mode of delivery produces differences in cerebral oxygenation, cerebral hemoglobin oxygen saturation was measured using full-spectrum near infrared spectroscopy in 26 healthy term newborn infants immediately after birth. Infants in group 1 (n=20) were delivered vaginally, and those in group 2 (n=6) by elective cesarean section. Arterial oxygen saturation in the right hand was also measured simultaneously using a pulse oximeter. Changes in arterial oxygen saturation showed no significant difference between the two groups. The mean+/-S.D. of cerebral hemoglobin oxygen saturation in group 1 increased rapidly after birth, from 29+/-17% at 2 min to 68+/-6% at 8.5 min, followed by an almost constant value (66+/-7% at 15 min). In comparison, cerebral hemoglobin oxygen saturation in group 2 also increased rapidly until 8.5 min, but after this time decreased significantly to 57+/-5% at 15 min after birth. This indicates that the mode of delivery has a marked influence on cerebral oxygenation immediately after birth.     

Abnormal iron delivery to the bone marrow in neonatal hypotransferrinemic mice

Hypotransferrinemic (HP) mice have a splicing defect inthe transferrin gene, resulting in <1% of the normal plasma levels of transferrin. They have severe anemia, suggesting that transferrin is essential for iron uptake by erythroid cells in the bone barrow. To clarify the significance of transferrin on iron delivery to the bone marrow, iron concentration and ⁵⁹Fe distribution were determined in 7-day-old HP mice. Iron concentration in the femur, bone containing the bone marrow, of HP mice was approximately twice higher than in wild type mice. Twenty-four h after injection of ⁵⁹FeCl₃, ⁵⁹Fe concentration in the bone and bone marrow of HP mice was also twice higher than in wild type mice. The present findings indicate that iron is abnormally delivered to the bone marrow of HP mice. However, the iron seems to be unavailable for the production of hemoglobin. These results suggest that transferrin-dependent iron uptake by erythroid cells in the bone marrow is essential for the development of erythrocytes.     

Phosphorylation of retinoblastoma-related protein by the cyclin D/cyclin-dependent kinase complex is activated at the G1/S-phase transition in tobacco

In mammals, D-type cyclin-associated kinases mainly regulate the G1/S transition by phosphorylating the retinoblastoma (Rb) protein. We previously demonstrated that in tobacco, cyclin D (Nicta; CycD3;3) is complexed with the PSTAIRE-containing cyclin-dependent kinase (CDKA) from tobacco. Here, we show that Nicta; CycD3;3-associated kinases phosphorylate both the tobacco Rb-related protein (NtRb1) and histone H1. Although NtRb1 kinase activity was detected only during the middle G1- to early S-phase, histone H1 kinase activity was observed as two peaks in G1- to S-phase and G2/M- to M-phase. Importantly, we show that the proportion of cells in the G1-phase was reduced in transgenic Bright Yellow-2 cells overexpressing Nicta; CycD3;3-GFP. Mutational analyses revealed that phosphorylation of Thr-191 in Nicta; CycD3;3 possibly is required for both full kinase activity and localization predominantly to the nucleus. These data suggest that Nicta; CycD3;3 acts as a rate-limiting regulator in the G1/S transition by forming active complexes with CDKA or its related kinases to phosphorylate Rb-related protein and potentially plays a novel role during G2/M and mitosis.     

Isolation and Characterization of 2-Nitroimidazole Produced by Streptomyces Species as an Inhibitor of Both Carbonic Anhydrase and Shell Formation in the Barnacle Balanus amphitrite

Carbonic anhydrase is thought to be involved in the process of calcium carbonate deposition in calcified tissues of many organisms. Barnacles form hard calcified shells for protection against predation, and represent a class of marine-fouling animals. In order to inhibit barnacle growth by inhibiting shell formation, we searched for carbonic anhydrase inhibitors from microbial secondary metabolites. A simple assay for assessing carbonic-anhydrase-inhibiting activity was developed. Screening of many microorganisms isolated from soil with this assay resulted in a microbial strain that produced a carbonic anhydrase inhibitor. This strain was identified as Streptomyces eurocidicus mf294. The inhibitor was isolated through 4 purification steps and identified as 2-nitroimidazole on the basis of spectroscopic data. 2-Nitroimidazole inhibited barnacle carbonic anhydrase dose-dependently and complete inhibition was reached at the concentration of 1 x 10(-5) M. 2-Nitroimidazole did not affect settlement or metamorphosis of barnacle larvae, but inhibited shell formation at concentrations higher than 1 x 10(-4) M. These findings strongly support the idea that carbonic anhydrase is involved in calcification.     

Influence of iron-saturation of plasma transferrin in iron distribution in the brain

Based on the evidence that iron distribution in the peripheral tissues is changed by iron-saturation of plasma transferrin, the influence of iron-saturation of plasma transferrin in iron delivery to the brain was examined. Mouse plasma was pre-incubated with ferric chloride in citrate buffer to saturate transferrin and then incubated with (59)FeCl(3). Peak retention time of (59)Fe was transferred from the retention time of transferrin to that of mercaptalbumin, suggesting that iron may bind to albumin in the plasma in the case of iron-saturation of transferrin. When mice were intravenously injected with ferric chloride in citrate buffer 10 min before intravenous injection of (59)FeCl(3), 59Fe concentration in the plasma was remarkably low. (59)Fe concentration in the liver of iron-loaded mice was four times higher than in control, while 59Fe concentration in the brain of iron-loaded mice was approximately 40% of that of control mice. Twenty-four hours after intravenous injection of (59)FeCl(3), brain autoradiograms also showed that (59)Fe concentrations in the brain of iron-loaded mice were approximately 40-50% of those of control mice in all brain regions tested except the choroid plexus, in which (59)Fe concentration was equal. These results suggest that the fraction of non-transferrin-bound iron is engulfed by the liver, resulting in the reduction of iron available for iron delivery to the brain in iron-loaded mice. Transferrin-bound iron may be responsible for the fraction of iron in circulation that enters the brain.     

Regulation of angiogenesis by the aging suppressor gene klotho

Advanced age is a major risk factor of peripheral artery disease. We examined the effects of the aging-suppressor gene klotho on angiogenesis in response to ischemia by introducing ischemic hindlimb model in mice heterozygously deficient for the klotho gene and in wild type mice. Blood flow recovery as assessed by laser doppler perfusion imaging and angiogenesis as assessed by density of PECAM-1/CD31-positive positive capillaries were markedly impaired in mice heterozygously deficient for the klotho gene (both <0.05). Our findings show that the aging-suppressor gene klotho affects angiogenesis and the possibility that age-related impairment of angiogenesis might be regulated by the klotho gene. Our results present a new possibility of therapeutic angiogenesis for patients of advanced age.     

Design and functional analysis of actomyosin motor domain chimera proteins

To gain more structural and functional information on the actomyosin complexes, we have engineered chimera proteins carrying the entire Dictyostelium actin in the loop 2 sequence of the motor domain of Dictyostelium myosin II. Although the chimera proteins were unable to polymerize by themselves, addition of skeletal actin promoted polymerization. Electron microscopic observation demonstrated that the chimera proteins were incorporated into actin filaments, when copolymerized with skeletal actin. Copolymerization with skeletal actin greatly enhanced the MgATPase, while the chimera proteins without added skeletal actin hydrolyzed ATP at a very low rate. These results indicate that the actin part and the motor domain part of the chimera proteins are correctly folded, but the chimera proteins are structurally stressed so that efficient polymerization is inhibited.     

MAP2 is required for dendrite elongation,PKA anchoring in dendrites,and proper PKA signal transduction

Microtubule-associated protein 2 (MAP2) is a major component of cross-bridges between microtubules in dendrites, and is known to stabilize microtubules. MAP2 also has a binding domain for the regulatory subunit II of cAMP-dependent protein kinase (PKA). We found that there is reduction in microtubule density in dendrites and a reduction of dendritic length in MAP2-deficient mice. Moreover, there is a significant reduction of various subunits of PKA in dendrites and total amounts of various PKA subunits in hippocampal tissue and cultured neurons. In MAP2-deficient cultured neurons, the induction rate of phosphorylated CREB after forskolin stimulation was much lower than in wild-type neurons. Therefore, MAP2 is an anchoring protein of PKA in dendrites, whose loss leads to reduced amount of dendritic and total PKA and reduced activation of CREB.