105 research outputs found
Localized laccase activity modulates distribution of lignin polymers in gymnosperm compression wood
The woody stems of coniferous gymnosperms produce specialised compression wood to adjust the stem growth orientation in response to gravitropic stimulation. During this process, tracheids develop a compression-wood-specific S2L cell wall layer with lignins highly enriched with p-hydroxyphenyl (H)-type units derived from H-type monolignol, whereas lignins produced in the cell walls of normal wood tracheids are exclusively composed of guaiacyl (G)-type units from G-type monolignol with a trace amount of H-type units. We show that laccases, a class of lignin polymerisation enzymes, play a crucial role in the spatially organised polymerisation of H-type and G-type monolignols during compression wood formation in Japanese cypress (Chamaecyparis obtusa). We performed a series of chemical-probe-aided imaging analysis on C. obtusa compression wood cell walls, together with gene expression, protein localisation and enzymatic assays of C. obtusa laccases. Our data indicated that CoLac1 and CoLac3 with differential oxidation activities towards H-type and G-type monolignols were precisely localised to distinct cell wall layers in which H-type and G-type lignin units were preferentially produced during the development of compression wood tracheids. We propose that, not only the spatial localisation of laccases, but also their biochemical characteristics dictate the spatial patterning of lignin polymerisation in gymnosperm compression wood
X-ray magnetic circular dichroism and photoemission study of the diluted ferromagnetic semiconductor ZnCrTe
We have performed x-ray magnetic circular dichroism (XMCD) and valence-band
photoemission studies of the diluted ferromagnetic semiconductor
ZnCrTe. XMCD signals due to ferromagnetism were observed at the Cr
2p absorption edge. Comparison with atomic multiplet calculations suggests that
the magnetically active component of the Cr ion was divalent under the
tetrahedral crystal field with tetragonal distortion along the crystalline a-,
b-, and c-axes. In the valence-band spectra, spectral weight near the Fermi
level was strongly suppressed, suggesting the importance of Jahn-Teller effect
and the strong Coulomb interaction between the Cr 3d electrons
A Report on Hydrographic Activities Following the Great East Japan Earthquake
The Great East Japan Earthquake (Mw9.0) on 11 March 2011 accompanied with a huge tsunami of more than 10 meters in height devastated many cities and ports along the Pacific coast of northeastern Japan, and claimed nearly 20,000 lives with many of them still missing. This report reviews actions taken by the Japan Hydrographic and Oceanographic Department (JHOD) after this unprecedented disaster. Immediately after the earthquake, the JHOD carried out hydrographic surveys for the urgent need to help clear the passage in ports due to sunken debris swept away by the tsunami. These surveys have enabled the vessels with relief supplies on board for the affected areas to enter the ports. The JHOD revisited the affected ports for the next stage of hydrographic surveys. These surveys will contribute to revised nautical charts based on new data collected after the earthquake, and includes the ongoing restoration and reconstruction work of quays and port facilities. This stage includes the re-determination of the datum level of the affected ports, which is necessary because of large subsidence being reported in the areas. All of these efforts by the JHOD clearly demonstrate the significance of the hydrographic activities in case of the post-quake emergency situation, not only for the safety of navigation but also for economic recovery
Deletion of NAD(P)H Oxidase 2 Prevents Angiotensin II-Induced Skeletal Muscle Atrophy
Skeletal muscle atrophy is induced by an imbalance between protein synthesis and degradation. Our previous studies reported that angiotensin II (AII) directly induced muscle atrophy in mice. This study investigated the role of NAD(P)H oxidase 2 (Nox2) activation by AII in the induction of skeletal muscle atrophy. For 4 weeks, either saline (vehicle: V) or AII (1000 ng kg(-1) min(-1)) was infused into male wild-type (WT) and Nox2 knockout (KO) mice via osmotic minipumps. Experiments were performed in the following 4 groups: WT + V, KO + V, WT + AII, and KO + AII. Body weight, muscle weight, and myocyte cross-sectional area were significantly decreased in WT + AII compared to WT + V mice, and these changes were not observed in KO + AII mice. Akt phosphorylation of Ser473 and p70S6K of Thr389 was decreased, gene expression levels of MuRF-1 and atrogin-1 were increased in WT + AII compared to WT + V, and these changes were significantly attenuated in KO + AII mice. The deletion of Nox2 prevented AII-induced skeletal muscle atrophy via improving the balance between protein synthesis and degradation. Therefore, Nox2 may be a therapeutic target for AII-induced skeletal muscle atrophy
Randomized Trial of Effect of Urate-Lowering Agent Febuxostat in Chronic Heart Failure Patients with Hyperuricemia (LEAF-CHF)
Hyperuricemia is an independent predictor of mortality in patients with chronic heart failure. The aim of the study is to determine whether a urate-lowering agent febuxostat, an inhibitor of xanthine oxidase, may improve the clinical outcomes in chronic heart failure patients with hyperuricemia when compared to conventional treatment. This multicenter, prospective, randomized, open-label, blinded endpoint study with a follow-up period of 24 weeks will enroll 200 Japanese chronic heart failure patients with hyperuricemia. The eligibility criteria include a diagnosis of chronic heart failure (New York Heart Association functional class II-III with a history of hospitalization due to worsening of heart failure within the last 2 years), reduced left ventricular systolic function (left ventricular ejection fraction 7.0 mg/dL and ? 10 mg/dL) at the screening visit. The primary outcome is the difference in the plasma BNP levels between the baseline and 24 weeks of treatment. The plasma BNP levels are measured in the central laboratory in a blinded manner. This study investigates the efficacy and safety of febuxostat in chronic heart failure patients with hyperuricemia
AST-120 ameliorates lowered exercise capacity and mitochondrial biogenesis in the skeletal muscle from mice with chronic kidney disease via reducing oxidative stress
Background. Exercise capacity and quality of life are markedly impaired in chronic kidney disease (CKD). Increased plasma uremic toxins such as indoxyl sulfate (IS), which induce oxidative stress, may be involved in this process. An oral adsorbent, AST-120, can reduce circulating IS, however, its effects on skeletal muscle and exercise capacity have not been investigated in CKD. Methods. Subtotal-nephrectomy or sham operation was performed in 8-week-old C57BL/6J mice. They were divided into two groups with or without 8% (w/w) of AST-120 in standard diet for 20 weeks. Sham, Sham + AST-120, CKD and CKD + AST-120 (n = 12, each group) were studied. We also conducted a C2C12 cell culture study to determine the direct effects of IS on oxidative stress. Results. Plasma IS levels were significantly increased in CKD compared with Sham (1.05 +/- 0.11 versus 0.21 +/- 0.03 mg/dL, P < 0.05), which was significantly ameliorated in CKD + AST120 (0.41 +/- 0.06 mg/dL). The running distance to exhaustion determined by treadmill tests was significantly reduced in CKD compared with Sham (267 +/- 17 versus 427 +/- 36 m, P < 0.05), and this reduction was also significantly ameliorated in CKD + AST-120 (407 +/- 38 m) without altering skeletal muscle weight. Citrate synthase activity and mitochondrial biogenesis gene were downregulated, and superoxide production was significantly increased in the skeletal muscle from CKD, and these changes were normalized in CKD + AST-120. Incubation of C2C12 cells with IS significantly increased NAD(P) H oxidase activity. Conclusions. The administration of AST-120 improved exercise capacity and mitochondrial biogenesis of skeletal muscle via reducing oxidative stress. AST-120 may be a novel therapeutic agent against exercise intolerance in CKD
Direct renin inhibitor ameliorates insulin resistance by improving insulin signaling and oxidative stress in the skeletal muscle from post-infarct heart failure in mice
Insulin resistance can occur as a consequence of heart failure (HF). Activation of the renin-angiotensin system (RAS) may play a crucial role in this phenomenon. We thus investigated the effect of a direct renin inhibitor, aliskiren, on insulin resistance in HF after myocardial infarction (MI). MI and sham operation were performed in male C57BL/6 J mice. The mice were divided into 4 groups and treated with sham-operation (Sham, n=10), sham-operation and aliskiren (Sham+Aliskiren; 10 mg/kg/day, n=10), MI (n=11), or MI and aliskiren (MI+Aliskiren, n=11). After 4 weeks, MI mice showed left ventricular dilation and dysfunction, which were not affected by aliskiren. The percent decrease of blood glucose after insulin load was significantly smaller in MI than in Sham (14±5% vs. 36±2%), and was ameliorated in MI+Aliskiren (34±5%) mice. Insulin-stimulated serine-phosphorylation of Akt and glucose transporter 4 translocation were decreased in the skeletal muscle of MI compared to Sham by 57% and 69%, and both changes were ameliorated in the MI+Aliskiren group (91% and 94%). Aliskiren administration in MI mice significantly inhibited plasma renin activity and angiotensin II (Ang II) levels. Moreover, (pro)renin receptor expression and local Ang II production were upregulated in skeletal muscle from MI and were attenuated in MI+Aliskiren mice, in tandem with a decrease in superoxide production and NAD(P)H oxidase activities. In conclusion, aliskiren ameliorated insulin resistance in HF by improving insulin signaling in the skeletal muscle, at least partly by inhibiting systemic and (pro)renin receptor-mediated local RAS activation, and subsequent NAD(P)H oxidase-induced oxidative stress
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