Self and world: large scale installations at science museums

This paper describes three examples of illusion installation in a science museum environment from the author's collaboration with the artist and architect. The installations amplify the illusory effects, such as vection (visually-induced sensation of self motion) and motion-induced blindness, to emphasize that perception is not just to obtain structure and features of objects, but rather to grasp the dynamic relationship between the self and the world. Scaling up the size and utilizing the live human body turned out to be keys for installations with higher emotional impact.     

Agmatine is essential for the cell growth of Thermococcus kodakaraensis

TK0149 (designated as Tk-PdaD) of a hyperthermophilic archaeon, Thermococcus kodakaraensis, was annotated as pyruvoyl-dependent arginine decarboxylase, which catalyzes agmatine formation by the decarboxylation of arginine as the first step of polyamine biosynthesis. In order to investigate its physiological roles, Tk-PdaD was purified as a recombinant form, and its substrate dependency was examined using the candidate compounds arginine, ornithine and lysine. Tk-PdaD, expressed in Escherichia coli, was cleaved into alpha and beta subunits, as other pyruvoyl-dependent enzymes, and the resulting subunits formed an (alphabeta)(6) complex. The Tk-PdaD complex catalyzed the decarboxylation of arginine but not that of ornithine and lysine. A gene disruptant lacking Tk-pdaD was constructed, showing that it grew only in the medium in the presence of agmatine but not in the absence of agmatine. The obtained results indicate that Tk-pdaD encodes a pyruvoyl-dependent arginine decarboxylase and that agmatine is essential for the cell growth of T. kodakaraensis.     

Tachycardia-induced myocardial ischemia and diastolic dysfunction potentiate secretion of ANP, not BNP, in hypertrophic cardiomyopathy

The aim of this study was to investigate what factor determines tachycardia-induced secretion of atrial and brain natriuretic peptides (ANP and BNP, respectively) in patients with hypertrophic cardiomyopathy (HCM). HCM patients with normal left ventricular (LV) systolic function and intact coronary artery (n = 22) underwent rapid atrial pacing test. The cardiac secretion of ANP and BNP and the lactate extraction ratio (LER) were evaluated by using blood samples from the coronary sinus and aorta. LV end-diastolic pressure (LVEDP) and the time constant of LV relaxation of tau were measured by a catheter-tip transducer. These parameters were compared with normal controls (n = 8). HCM patients were divided into obstructive (HOCM) and nonobstructive (HNCM) groups. The cardiac secretion of ANP was significantly increased by rapid pacing in HOCM from 384 +/- 101 to 1,268 +/- 334 pg/ml (P < 0.05); however, it was not significant in control and HNCM groups. In contrast, the cardiac secretion of BNP was fairly constant and rather significantly decreased in HCM (P < 0.01). The cardiac ANP secretion was significantly correlated with changes in LER (r = -0.57, P < 0.01) and tau (r = 0.73, P < 0.001) in HCM patients. Tachycardia potentiates the cardiac secretion of ANP, not BNP, in patients with HCM, particularly when it induces myocardial ischemia and LV diastolic dysfunction.     

Arylamine based cathepsin K inhibitors: investigating P3 heterocyclic substituents

A modification of novel cathepsin K inhibitors I was carried out. The structural design was aimed at reducing the lipophilic character of compounds I for obtaining better pharmacokinetic profiles. This modification afforded several less lipophilic compounds with good inhibitory activities and pharmacokinetic profiles, although the enzyme selectivity over cathepsin S was left at issue.     

Synthesis of functional dipeptide carnosine from nonprotected amino acids using carnosinase-displaying yeast cells

Carnosine (β-alanyl-l-histidine) is one of the bioactive dipeptides and has antioxidant, antiglycation, and cytoplasmic buffering properties. In this study, to synthesize carnosine from nonprotected amino acids as substrates, we cloned the carnosinase (CN1) gene and constructed a whole-cell biocatalyst displaying CN1 on the yeast cell surface with α-agglutinin as the anchor protein. The display of CN1 was confirmed by immunofluorescent labeling, and CN1-displaying yeast cells showed hydrolytic activity for carnosine. When carnosine was synthesized by the reverse reaction of CN1, organic solvents were added to the reaction mixture to reduce the water content. The CN1-displaying yeast cells were lyophilized and examined for organic solvent tolerance. Results showed that the CN1-displaying yeast cells retained their original hydrolytic activity in hydrophobic organic solvents. In the hydrophobic organic solvents and hydrophobic ionic liquids, the CN1-displaying yeast cells catalyzed carnosine synthesis, and carnosine was synthesized from nonprotected amino acids in only one step. The results of this research suggest that the whole-cell biocatalyst displaying CN1 on the yeast cell surface can be used to synthesize carnosine with ease and convenience.     

KIF1Bbeta- and KIF1A-mediated axonal transport of presynaptic regulator Rab3 occurs in a GTP-dependent manner through DENN/MADD

Synaptic proteins are synthesized in the cell body and transported down the axon by microtubule-dependent motors. We previously reported that KIF1Bbeta and KIF1A motors are essential for transporting synaptic vesicle precursors; however the mechanisms that regulate transport, as well as cargo recognition and control of cargo loading and unloading remain largely unknown. Here, we show that DENN/MADD (Rab3-GEP) is an essential part of the regulation mechanism through direct interaction with the stalk domain of KIF1Bbeta and KIF1A. We also show that DENN/MADD binds preferentially to GTP-Rab3 and acts as a Rab3 effector. These molecular interactions are fundamental as sequential genetic perturbations revealed that KIF1Bbeta and KIF1A are essential for the transport of DENN/MADD and Rab3, whereas DENN/MADD is essential for the transport of Rab3. GTP-Rab3 was more effectively transported than GDP-Rab3, suggesting that the nucleotide state of Rab3 regulates axonal transport of Rab3-carrying vesicles through preferential interaction with DENN/MADD.     

Structural insights into the substrate specificity of bacterial copper amine oxidase obtained by using irreversible inhibitors

Copper amine oxidases (CAOs) catalyse the oxidation of various aliphatic amines to the corresponding aldehydes, ammonia and hydrogen peroxide. Although CAOs from various organisms share a highly conserved active-site structure including a protein-derived cofactor, topa quinone (TPQ), their substrate specificities differ considerably. To obtain structural insights into the substrate specificity of a CAO from Arthrobacter globiformis (AGAO), we have determined the X-ray crystal structures of AGAO complexed with irreversible inhibitors that form covalent adducts with TPQ. Three hydrazine derivatives, benzylhydrazine (BHZ), 4-hydroxybenzylhydrazine (4-OH-BHZ) and phenylhydrazine (PHZ) formed predominantly a hydrazone adduct, which is structurally analogous to the substrate Schiff base of TPQ formed during the catalytic reaction. With BHZ and 4-OH-BHZ, but not with PHZ, the inhibitor aromatic ring is bound to a hydrophobic cavity near the active site in a well-defined conformation. Furthermore, the hydrogen atom on the hydrazone nitrogen is located closer to the catalytic base in the BHZ and 4-OH-BHZ adducts than in the PHZ adduct. These results correlate well with the reactivity of 2-phenylethylamine and tyramine as preferred substrates for AGAO and also explain why benzylamine is a poor substrate with markedly decreased rate constants for the steps of proton abstraction and the following hydrolysis.     

Prenatal diagnosis of Hurler's syndrome—Biochemical studies on the affected fetus

Summary A prenatal diagnosis of Hurler's syndrome was made in a pregnancy at risk in a family with two affected children. The fetus was diagnosed as having Hurler's syndrome on the basis of a deficiency of -L-iduronidase in the cultured amniotic cells. The glycosaminoglycans (GAG) content in the supernatant of the amniotic fluid was increased about 1.5 fold compared with that in the control, and increases of heparan sulfate and dermatan sulfate were observed on electrophoresis.The diagnosis could be confirmed by the deficiencies of -L-iduronidase in the liver and brain from the affected fetus. GAG content in the liver from the affected fetus was increased approximately 10 fold as compared with that in the control fetal liver, and most of the GAG were degraded. The GAG content was observed to be increased two fold in the brain, and dermatan sulfate, which was not detected in normal fetal brain, was identified. -galactosidase activities in the affected liver and brain were decreased to 30tt50% of the control, and an altered hexosaminidase A was also observed in the liver.