Cardiopulmonary arrest secondary to compression of the heart owing to esophageal hiatal hernia: a case report.

BACKGROUND: Esophageal hiatal hernia is commonly encountered in clinical practice. We describe a case of cardiac compression caused by an esophageal hiatal hernia that resulted in circulatory failure and cardiac arrest. CASE PRESENTATION: An 82-year-old woman presented to our hospital with vomiting, which progressed to cardiac arrest in the emergency room after computed tomography (CT) imaging. CT revealed gastric herniation into the mediastinum, with marked cardiac compression. Cardiopulmonary resuscitation was performed, and a nasogastric tube was inserted for gastric decompression, which resulted in the return of spontaneous circulation and subsequent hemodynamic stabilization. However, the patient died of aspiration pneumonia 4 days later. CONCLUSION: Gastric decompression can lead to rapid improvements in respiration and circulation in patients with an esophageal hiatal hernia. Nonetheless, to prevent complications, such as those observed in our patient, definitive surgical treatment is warranted.

Cardiovascular safety and effectiveness of vildagliptin in patients with type 2 diabetes mellitus: a 3-year, large-scale post-marketing surveillance in Japan.

Objectives: The dipeptidyl peptidase-4 (DPP-4) inhibitor vildagliptin is indicated for type 2 diabetes mellitus (T2DM). However, the long-term safety, effectiveness, and clinical relationship with cardiovascular events of vildagliptin have not been evaluated in Japan.Methods: The authors conducted post-marketing surveillance (PMS) to evaluate the safety and effectiveness of vildagliptin in more than 3000 Japanese T2DM patients for up to 3 years. Main assessments included demographics, major adverse cardiovascular events (MACE), adverse events (AEs), adverse drug reactions (ADRs), and glycated hemoglobin (HbA1c).Results: In this PMS, 3831 patients (775 sites) were registered in April 2010 - April 2012. The safety analysis population comprised 3769 patients; 2085 patients were aged ≥65 years, and 240, 411, and 114 had renal impairment, hepatic impairment, and heart failure, respectively. The median treatment duration was 2.7 years. The incidence of MACE was 6.04 cases/1000 person-years, mostly attributable to cerebrovascular events (4.27 cases/1000 person-years). The AE and ADR incidences were 26.0% and 5.3%, respectively. The incidence of hypoglycemia was 0.6%. No significant changes in body weight occurred and mean change in HbA1c from baseline at final assessment was -0.74 ± 1.41% (p < 0.0001).Conclusions: In real-world clinical settings, vildagliptin was well tolerated, with similar profiles as previously reported.

Hydrogen produced in rat colon improves in vivo reduction-oxidation balance due to induced regeneration of α-tocopherol.

We investigated whether non-digestible saccharide fermentation-derived hydrogen molecules (H2) in rat colon could improve the in vivo reduction-oxidation (redox) balance via regeneration of α-tocopherol, by assessing their effect on hydroxyl radicals, the α-tocopherol concentration and the redox balance. In Expt 1, a Fenton reaction with phenylalanine (0 or 1·37 mmol/l of H2) was conducted. In Expt 2, rats received intraperitoneally maize oil containing phorone (400 mg/kg) 7 d after drinking ad libitum water containing 0 or 4 % fructo-oligosaccharides (FOS) (groups CP and FP, respectively). In Expt 3, rats unable to synthesise ascorbic acid drank ad libitum for 14 d water with 240 mg ascorbic acid/l (group AC), 20 mg of ascorbic acid/l (group DC) or 20 mg of ascorbic acid/l and 4 % FOS (group DCF). In the Fenton reaction, H2 reduced tyrosine produced from phenylalanine to 72 % when platinum was added and to 92 % when platinum was excluded. In Expt 2, liver glutathione was depleted by administration of phorone to rats. However, compared with CP, no change in the m-tyrosine concentration in the liver of FP was detected. In Expt 3, net H2 excretion was higher in DCF than in the other rats after 3 d of the experiment. Furthermore, the concentrations of H2 and α-tocopherol and the redox glutathione ratio in perirenal adipose tissue of rats were significantly higher in DCF than in DC. To summarise, in rat colon, fermentation-derived H2 further shifted the redox balance towards a more reducing status in perirenal adipose tissue through increased regeneration of α-tocopherol.

Auxin signaling through SCFTIR1/AFBs mediates feedback regulation of IAA biosynthesis.

We previously reported that exogenous application of auxin to Arabidopsis seedlings resulted in downregulation of indole-3-acetic acid (IAA) biosynthesis genes in a feedback manner. In this study, we investigated the involvement of the SCFTIR1/AFB-mediated signaling pathway in feedback regulation of the indole-3-pyruvic acid-mediated auxin biosynthesis pathway in Arabidopsis. Application of PEO-IAA, an inhibitor of the IAA signal transduction pathway, to wild-type seedlings resulted in increased endogenous IAA levels in roots. Endogenous IAA levels in the auxin-signaling mutants axr2-1, axr3-3, and tir1-1afb1-1afb2-1afb3-1 also increased. Furthermore, YUCCA (YUC) gene expression was repressed in response to auxin treatment, and expression of YUC7 and YUC8 increased in response to PEO-IAA treatment. YUC genes were also induced in auxin-signaling mutants but repressed in TIR1-overexpression lines. These observations suggest that the endogenous IAA levels are regulated by auxin biosynthesis in a feedback manner, and the Aux/IAA and SCFTIR1/AFB-mediated auxin-signaling pathway regulates the expression of YUC genes.

Biochemical and Chemical Biology Study of Rice OsTAR1 Revealed that Tryptophan Aminotransferase is Involved in Auxin Biosynthesis: Identification of a Potent OsTAR1 Inhibitor, Pyruvamine2031.

IAA, a major form of auxin, is biosynthesized from l-tryptophan via the indole-3-pyruvic acid (IPyA) pathway in Arabidopsis. Tryptophan aminotransferases (TAA1/TARs) catalyze the first step from l-tryptophan to IPyA. In rice, the importance of TAA/TARs or YUC homologs in auxin biosynthesis has been suggested, but the enzymatic activities and involvement of the intermediate IPyA in auxin biosynthesis remain elusive. In this study, we obtained biochemical evidence that the rice tryptophan aminotransferase OsTAR1 converts l-tryptophan to IPyA, and has a Km of 82.02 µM and a Vmax of 10.92 µM min-1 m-1, comparable with those in Arabidopsis. Next, we screened for an effective inhibitor of OsTAR1 from our previously reported inhibitor library for TAA1/TARs, designated pyruvamine (PVM). Differing from previous observations in Arabidopsis, hydroxy-type PVMs, e.g. PVM2031 (previous name KOK2031), had stronger inhibitory effects in rice than the methoxy-type. PVM2031 inhibited recombinant OsTAR1 in vitro. The Ki of PVM2031 was 276 nM. PVM2031 treatment of rice seedlings resulted in morphological changes in vivo, such as reduced lateral root density. Exogenous IAA rescued this growth inhibition, suggesting that the inhibitory effect is auxin specific. Furthermore, rice roots showed reduced IAA levels concomitant with reduced levels of IPyA in the presence of the inhibitors, suggesting that the IPyA pathway is an auxin biosynthesis pathway in rice. Since PVM2031 showed stronger inhibitory effects on rice auxin biosynthesis than known tryptophan aminotransferase inhibitors, we propose that the hydroxy-type PVM2031 is an effective tool for biochemical analysis of the function of auxin biosynthesis in rice roots.

Transport of pyruvate into mitochondria is involved in methylmercury toxicity.

We have previously demonstrated that the overexpression of enzymes involved in the production of pyruvate, enolase 2 (Eno2) and D-lactate dehydrogenase (Dld3) renders yeast highly sensitive to methylmercury and that the promotion of intracellular pyruvate synthesis may be involved in intensifying the toxicity of methylmercury. In the present study, we showed that the addition of pyruvate to culture media in non-toxic concentrations significantly enhanced the sensitivity of yeast and human neuroblastoma cells to methylmercury. The results also suggested that methylmercury promoted the transport of pyruvate into mitochondria and that the increased pyruvate concentrations in mitochondria were involved in intensifying the toxicity of methylmercury without pyruvate being converted to acetyl-CoA. Furthermore, in human neuroblastoma cells, methylmercury treatment alone decreased the mitochondrial membrane potential, and the addition of pyruvate led to a further significant decrease. In addition, treatment with N-acetylcysteine (an antioxidant) significantly alleviated the toxicity of methylmercury and significantly inhibited the intensification of methylmercury toxicity by pyruvate. Based on these data, we hypothesize that methylmercury exerts its toxicity by raising the level of pyruvate in mitochondria and that mitochondrial dysfunction and increased levels of reactive oxygen species are involved in the action of pyruvate.

Small-molecule auxin inhibitors that target YUCCA are powerful tools for studying auxin function.

Auxin is essential for plant growth and development, this makes it difficult to study the biological function of auxin using auxin-deficient mutants. Chemical genetics have the potential to overcome this difficulty by temporally reducing the auxin function using inhibitors. Recently, the indole-3-pyruvate (IPyA) pathway was suggested to be a major biosynthesis pathway in Arabidopsis thaliana L. for indole-3-acetic acid (IAA), the most common member of the auxin family. In this pathway, YUCCA, a flavin-containing monooxygenase (YUC), catalyzes the last step of conversion from IPyA to IAA. In this study, we screened effective inhibitors, 4-biphenylboronic acid (BBo) and 4-phenoxyphenylboronic acid (PPBo), which target YUC. These compounds inhibited the activity of recombinant YUC in vitro, reduced endogenous IAA content, and inhibited primary root elongation and lateral root formation in wild-type Arabidopsis seedlings. Co-treatment with IAA reduced the inhibitory effects. Kinetic studies of BBo and PPBo showed that they are competitive inhibitors of the substrate IPyA. Inhibition constants (Ki ) of BBo and PPBo were 67 and 56 nm, respectively. In addition, PPBo did not interfere with the auxin response of auxin-marker genes when it was co-treated with IAA, suggesting that PPBo is not an inhibitor of auxin sensing or signaling. We propose that these compounds are a class of auxin biosynthesis inhibitors that target YUC. These small molecules are powerful tools for the chemical genetic analysis of auxin function.

Identification of substrates of F-box protein involved in methylmercury toxicity in yeast cells.

We previously reported that some of the substrate proteins recognized by Hrt3 or Ucc1, a component of Skp1/Cdc53/F-box protein ubiquitin ligase, may include proteins that are involved in the methylmercury toxicity and degraded by the proteasome. In this study, we found that Dld3 and Grs1 bound to Hrt3 and that Eno2 bound to Ucc1 using a yeast two-hybrid screening. We demonstrated that Dld3 and Grs1 are substrates that are ubiquitinated by Hrt3, and Eno2 is a substrate that is ubiquitinated by Ucc1. Moreover, any yeast showing overexpression of Dld3, Grs1, and Eno2 demonstrated higher methylmercury sensitivity. This indicates that Hrt3 and Ucc1 are involved in alleviating the methylmercury toxicity by promoting proteasomal degradation through the ubiquitination of Dld3, Grs1, and Eno2.

Analysis of a putative auxin biosynthesis inhibitor, indole-3-oxoethylphosphonic acid, in Arabidopsis.

Previously we identified indole-3-acetic acid (IAA) biosynthesis inhibitors that act on the conversion of l-tryptophan to indole-3-pyruvic acid in the IAA biosynthesis of Arabidopsis. In the present study, we synthesized a new compound, indole-3-oxoethylphosphonic acid (IOEP), and found that IOEP had an inhibitory effect on IAA biosynthesis in Arabidopsis. The results suggest that IOEP is a novel inhibitor of auxin biosynthesis in Arabidopsis.

A screen-printed endotoxin sensor based on amperometry using a novel p-aminophenol conjugated substrate for a Limulus amebocyte lysate protease reaction.

We developed a novel protease detection method based on amperometry using a p-aminophenol (pAP) conjugated substrate. We prepared Boc-Leu-Gly-Arg-pAP (LGR-pAP) as a novel substrate for a clotting enzyme, which is a protease activated by an endotoxin-induced Limulus amebocyte lysate (LAL) cascade reaction. The basic study using cyclic voltammetry revealed that the oxidation peak potentials of LGR-pAP and pAP were sufficiently separated from each other (0.25 V) to conduct amperometric detection of protease activity. We combined simple amperometric detection with a screen-printed electrode chip to produce a practical protease sensor. As an application of the sensor, we demonstrated quantitative endotoxin sensing. The endotoxin activated zymogens contained in the LAL to generate pAP, which was then electrochemically detected by potential step chronoamperometry (PSCA). The observed oxidation current increased with the concentration of endotoxin in the LAL assay solution. This PSCA detection was performed with a disposable chip sensor consisting of a screen-printed electrode and a fluidic channel with a hydrophilic cover. This chip sensor successfully detected 10-1000 EU L(-1) endotoxin within 60 min. This novel amperometric measurement with a screen-printed electrode not only provides compact, low-cost, and easy-to-use sensors for on-site monitoring of endotoxin, but also shows promise for use in other in vitro protease assays for biochemical research, diagnosis, and drug development.

Prevention of apoptosis by mitochondrial phosphatase PGAM5 in the mushroom body is crucial for heat shock resistance in Drosophila melanogaster.

The heat shock (HS) response is essential for survival of all organisms. Although the machinery of the HS response has been extensively investigated at the cellular level, it is poorly understood at the level of the organism. Here, we show the crucial role of the mushroom body (MB) in the HS response in Drosophila. Null mutants of the mitochondrial phosphatase Drosophila PGAM5 (dPGAM5) exhibited increased vulnerability to HS, which was reversed by MB-specific expression of the caspase inhibitor p35, and similar vulnerability was induced in wild-type flies by knockdown of MB dPGAM5. Elimination of the MB did not affect the HS response of wild-type flies, but did increase the resistance of dPGAM5-deficient flies to HS. Thus, the MB may possess an apoptosis-dependent toxic function, the suppression of which by dPGAM5 appears to be crucial for HS resistance.

Crystal growth of clathrate hydrate in gas/liquid/liquid system: variations in crystal-growth behavior.

This paper reports the visual observations of the formation and growth of structure-II hydrate crystals on a water droplet partially immersed in liquid cyclopentane and exposed to difluoromethane gas. Each of the experiments was performed under prescribed temperature and pressure conditions in the range from 281.7 to 297.0 K and from 0.12 to 1.10 MPa in order to investigate the effect of the driving force for the hydrate crystal growth. The experiments were conducted at 25 different temperature-pressure conditions. It was found that the behavior of the hydrate crystal growth in this three-component system can be classified into three modes, which we called "cover", "expansion" and "line", depending on the temperature and pressure. The descriptions of the three types are summarized as follows. "COVER": Hydrate crystals first formed on the water-droplet surface and then grew to form a polycrystalline layer covering the surface. After complete surface coverage, no more hydrate growth and little change in the shape of the hydrate-covered water droplet were observed. "EXPANSION": Like "cover", the first crystals were observed on the water-droplet surface. They grew not only along the surface, but also toward the gas phase, and then continued to grow for more than several tens of minutes after complete coverage. "LINE": Unlike the other two modes, hydrate crystals first formed at the three-phase interfacial line and grew along this line. The shape of the hydrate crystals eventually became like a doughnut, since the center of the water droplet collapsed when they grew.

The loss of PGAM5 suppresses the mitochondrial degeneration caused by inactivation of PINK1 in Drosophila.

PTEN-induced kinase 1 (PINK1), which is required for mitochondrial homeostasis, is a gene product responsible for early-onset Parkinson's disease (PD). Another early onset PD gene product, Parkin, has been suggested to function downstream of the PINK1 signalling pathway based on genetic studies in Drosophila. PINK1 is a serine/threonine kinase with a predicted mitochondrial target sequence and a probable transmembrane domain at the N-terminus, while Parkin is a RING-finger protein with ubiquitin-ligase (E3) activity. However, how PINK1 and Parkin regulate mitochondrial activity is largely unknown. To explore the molecular mechanism underlying the interaction between PINK1 and Parkin, we biochemically purified PINK1-binding proteins from human cultured cells and screened the genes encoding these binding proteins using Drosophila PINK1 (dPINK1) models to isolate a molecule(s) involved in the PINK1 pathology. Here we report that a PINK1-binding mitochondrial protein, PGAM5, modulates the PINK1 pathway. Loss of Drosophila PGAM5 (dPGAM5) can suppress the muscle degeneration, motor defects, and shorter lifespan that result from dPINK1 inactivation and that can be attributed to mitochondrial degeneration. However, dPGAM5 inactivation fails to modulate the phenotypes of parkin mutant flies. Conversely, ectopic expression of dPGAM5 exacerbated the dPINK1 and Drosophila parkin (dParkin) phenotypes. These results suggest that PGAM5 negatively regulates the PINK1 pathway related to maintenance of the mitochondria and, furthermore, that PGAM5 acts between PINK1 and Parkin, or functions independently of Parkin downstream of PINK1.

Pattern of oxidation products derived from tetrabromobisphenol A in a catalytic system comprised of iron(III)-tetrakis(p-sulfophenyl)porphyrin, KHSO5 and humic acids.

Tetrabromobisphenol A (TBBPA), a commercially used brominated flame retardant, also functions as an endocrine disruptor and is of serious concern in terms of environmental pollution. TBBPA has been detected in leachates from landfills, because hydrophobic interactions with humic acids (HAs) result in an increase in its solubility. In the present study, the oxidation of TBBPA was examined using a biomimetic catalytic system comprised of a combination of iron(III)-tetrakis(p-sulfophenyl)porphyrin (FeTPPS) and KHSO(5). Although more than 90% of TBBPA was oxidized at pH 8 in the absence and presence of HAs, no debromination was observed. An analysis of the oxidation products by GC/MS indicated that 4-(2-hydroxyisopropyl)-2,6-dibromophenol was the main byproduct. However, only about 6-12% of the TBBPA was degraded. In the presence of HAs, the remaining byproducts from TBBPA may be incorporated into HAs via a variety of interactions. Thus, HA fractions in the reaction mixture were separated, and analyzed for their Br content. Based on the analyses, the majority of the Br species (70-80%) were found to be incorporated into HAs after oxidation with TBBPA. In addition, coupling compounds between brominated intermediates from TBBPA and phenolic moieties in HAs were detected by pyrolysis-GC/MS. These results lead to the conclusion that the oxidation of TBBPA in the presence of HAs via catalytic oxidation using FeTPPS resulted in the incorporation of brominated intermediates into the polymeric structures of HAs.

Mitochondrial phosphoglycerate mutase 5 uses alternate catalytic activity as a protein serine/threonine phosphatase to activate ASK1.

Phosphoglycerate mutase (PGAM) is an enzyme of intermediary metabolism that converts 3-phosphoglycerate to 2-phosphoglycerate in glycolysis. Here, we discovered PGAM5 that is anchored in the mitochondrial membrane lacks PGAM activity and instead associates with the MAP kinase kinase kinase ASK1 and acts as a specific protein Ser/Thr phosphatase that activates ASK1 by dephosphorylation of inhibitory sites. Mutation of an active site His-105 in PGAM5 abolished phosphatase activity with ASK1 and phospho-Thr peptides as substrates. The Drosophila and Caenorhabditis elegans orthologs of PGAM5 also exhibit specific Ser/Thr phosphatase activity and activate the corresponding Drosophila and C. elegans ASK1 kinases. PGAM5 is unrelated to the other known Ser/Thr phosphatases of the PPP, MPP, and FCP families, and our results suggest that this member of the PGAM family has crossed over from small molecules to protein substrates and been adapted to serve as a specialized activator of ASK1.

Identification of F-box proteins that are involved in resistance to methylmercury in Saccharomyces cerevisiae.

We searched for F-box proteins that might be related to the mechanism that protects Saccharomyces cerevisiae against the toxic effects of methylmercury. We found that overexpression of Hrt3 and of Ylr224w rendered yeast cells resistant to methylmercury. Yeast cells that overexpressed Hrt3 and Ylr224w were barely resistant to methylmercury in the presence of a proteasome inhibitor. Our results suggest the existence of some protein(s) that enhances the toxicity of methylmercury in yeast cells and, also, that overexpression of Hrt3 or Ylr224w can confer resistance to methylmercury by enhancing the polyubiquitination of this protein(s) and its degradation in proteasomes.