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Biomedical subjects

Y Kurihara

Publications and source records attributed to Y Kurihara.

At least 145 records · Page 8Linked to original sources
PubMed1994

Structures of heat-stable and unstable homologues of the sweet protein mabinlin. The difference in the heat stability is due to replacement of a single amino acid residue.

There are several analogues of the sweet protein mabinlin. In previous studies, we purified the heat-stable analogue, mabinlin II, from the seeds of Capparis masaikai Lévl. and determined its amino acid sequence [Liu, X., Maeda, S., Hu, Z., Aiuchi, T., Nakaya, K. & Kurihara, Y. (1993) Eur. J. Biochem. 211, 281-287] and the disulfide structure [Nirasawa, S., Liu, X., Nishino, T. & Kurihara, Y. (1993) Biochim. Biophys. Acta 1202, 277-280]. We have now purified four additional homologues of mabinlin. The sweet activities of mabinlin III and mabinlin IV were unchanged by incubation for 1 h at 80 degrees C, as was found previously for mabinlin II, while the sweet activity of mabinlin I-1 was completely abolished by a 1-h incubation at 80 degrees C. The circular dichroic spectrum showed that alpha-helical structures of mabinlins II-IV were unchanged by the 1-h incubation at 80 degrees C, while the alpha-helical structures of mabinlin I-1 were completely destroyed by the 1-h incubation in parallel with the decrease of the sweet activity. To compare the structures of the heat-stable and unstable homologues, we determined their amino acid sequences and the disulfide array. The positions of four disulfide bridges of mabinlin I-1 were the same as those of mabinlin II, suggesting that the disulfide bridges do not contribute to the difference in the heat stability among the homologues. There was a high similarity among amino acid sequences of the homologoues. Only three amino acid residues (A-chain residues at positions 22 and 32 and B-chain residue at position 47) were different between mabinlin I-1 and mabinlin III. A-chain residue at position 32 was lacking in mabinlin IV and the A-chain residue at position 22 was identical in both mabinlin I-1 and mabinlin II. The B-chain residue at position 47 was the only residue present in all three heat-stable homologues (mabinlins II-IV) and is not present in the unstable homologue (mabinlin I-1). This suggests that the difference in the heat stability of mabinlin is due to the difference in a B-chain residue at position 47; the difference in the heat-stable homologues is due to the presence of an arginine residue and the difference of the unstable homologue is due to the presence of glutamine.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1994

Isolation and characterization of vascular endothelial cells derived from mice lacking endothelin-1.

Microvascular endothelial cells were isolated from endothelin (ET)-1 knockout mice. The ET-1-lacking endothelial cells represent normal shape and activity of acetyl-LDL uptake. The growth of ET-1-lacking endothelial cells was not different from that of control cells in the presence of serum. Compensatory production of other ET isoforms does not occur in these cells. Conversion of big ET-1 to ET-1 is not different between ET-1-lacking and control cells. These results suggest that ET-1 is not essential to endothelial morphology and growth, that the expression of ET isoforms is not redundant in endothelial cells, and that the machinery processing ET-1 is preserved despite of the absence of its substrate.

Animals↗
PubMed1994

Surface ionization organic mass spectrometry of imipramine, desipramine, clomipramine, and lidocaine.

Surface ionization organic mass spectrometry (SIOMS) has been performed on some clinically important drugs (imipramine, desipramine, clomipramine, lidocaine) by using quadrupole mass spectroscopy in which the thermal ion source has a rhenium oxide emitter. The mass spectra were presented, interpreted in a purely empirical way, by means of evidence from previous investigations, and then compared to conventional EI techniques. Sensitivity and selectivity have also been studied, demonstrating that (a) these drug compounds are efficiently surface-ionized, (b) experimental results rationalize the high sensitivity of the surface ionization detector (SID) of gas chromatography (GC) for the examined drugs, and (c) the GC/SIOMS coupling can be used for sensitive and selective detection of the drugs in the serum. An approach to detection of these drugs in serum by GC/SIOMS and GC with SID is described. The characteristics of both methods provide a reliable, sensitive, and selective method, which is needed for low concentration level measurements in complex mixtures.

Clomipramine↗
PubMed1994

Crystallization and preliminary X-ray diffraction studies of curculin. A new type of sweet protein having taste-modifying action.

A taste-modifying protein, curculin, has been crystallized by the vapor diffusion method using polyethylene glycol 400 as a precipitant. The crystals belong to orthorhombic space group P2(1)2(1)2(1) with unit cell dimensions: a = 105 A, b = 271 A, c = 48.7 A. The crystals diffract X-rays to at least a resolution of 3.0 A and are suitable for X-ray crystallographic studies.

Crystallization↗
PubMed1994

Elevated blood pressure and craniofacial abnormalities in mice deficient in endothelin-1.

The endothelin-1 (ET-1) gene was disrupted in mouse embryonic stem cells by homologous recombination to generate mice deficient in ET-1. These ET-1-/- homozygous mice die of respiratory failure at birth and have morphological abnormalities of the pharyngeal-arch-derived craniofacial tissues and organs. ET-1+/- heterozygous mice, which produce lower levels of ET-1 than wild-type mice, develop elevated blood pressure. These results suggest that ET-1 is essential for normal mouse development and may also play a physiological role in cardiovascular homeostasis.

Animals↗
PubMed1994

Stenotic bicuspid aortic valve associated with a ventricular septal defect in an adult presenting with congestive heart failure: a rare observation.

This report is concerned with an adult presenting with stenotic bicuspid aortic valve associated with a ventricular septal defect (VSD). The association between aortic regurgitation (AR) and VSD has often been described, but that between a stenosed aortic valve and VSD has been rarely observed, although bicuspid aortic valves and ventricular septal defects are probably the two most common congenital heart defects. The development of congestive heart failure in the presented case was considered to be due to an increase in the left to right shunt through the VSD. This was attributable to a progressive elevation in left ventricular pressure as a result of the development, with age, of stenosis of the bicuspid aortic valve.

Aged↗
PubMed1994

Study of hereditary trends in the shape of the murine mandible.

Inbred mice are a suitable material for genetic studies, and mandibular shape in particular provides a highly quantitative hereditary trait. We investigated which genetic trait in F1, F2 and N2 hybrid mice was most strongly affected by the presence of a large or small mandible in the parents. Ten C57BL/6By strain mice as parents with a small mandible and 10 MRL/n strain mice as parents with a large mandible were employed. Twenty-five (C57BL/6By male X MRL/n female) F1 and 67 F2 hybrids, and 28 (F1 male X C57BL/6By female) N2 backcross hybrids were obtained by laboratory mating. The inter-landmarks of the right mandible were measured by an electronic digitizer. Each mean value of horizontal dimensions in F1 mice resembled that in MRL/l mice, and that in N2 mice was intermediate between C57BL/6By and MRL/n mice. On the other hand, the mean values of vertical dimensions in F1, F2 and N2 hybrids were intermediate between those of C57BL/6By and MRL/n mice. Hence we suggest that horizontal dimensions are predominantly inherited by mice with a large mandible, and that vertical dimensions show intermediate inheritance between mice with large and small mandibles in the C57BL/6By and MRL/n strains.

Animals↗
PubMed1993

Disulfide bridge structure of the heat-stable sweet protein mabinlin II.

The heat-stable sweet protein mabinlin was composed of a A-chain of 33 amino-acid residues and a B-chain of 72 amino-acid residues (Liu, X., Maeda, S., Hu, Z., Aiuchi, T., Nakaya, K. and Kurihara, Y. (1993) Eur. J. Biochem. 211, 281-287). A-chain and B-chain contain two and six cysteine residues, respectively. The formation of two interchain disulfide bridges at Cys(A5)-Cys(B21) and Cys(A18)-Cys(B10), and two intrachain disulfide bridges at Cys(B11)-Cys(B59) and Cys(B23)-Cys(B67) were determined by amino-acid sequencing and composition analysis of cystine-containing peptides isolated by HPLC. Cleavage of the disulfide bridges with dithiothreitol results in complete loss of the sweet activity of mabinlin II. It was suggested that the structure fixed by four disulfide bridges contributes to heat stability of mabinlin II.

Amino Acid Sequence↗
PubMed1993

[Acute eosinophilic pneumonia: a report of two cases].

Two cases of acute eosinophilic pneumonia (AEP) are described and the radiographic findings discussed. Two patients presented acute fever and cough, which led to acute respiratory insufficiency in 3 days. There was no past history of asthma, hypersensitivity or allergy. They became well within 5 to 12 days, with corticosteroid in one and spontaneously in another. Bronchoalveolar lavage showed more than 80% eosinophils. Plain chest roentgenogram showed air space consolidation with peripheral predominance in case 1 and ground-glass shadow with reticular pattern in case 2. On CT, dense and faint air-space opacities were noted in both entire lung fields in case 1 and faint opacities with thickened interlobular septa in case 2. Bilateral pleural effusion and mild mediastinal lymphadenopathy were noted in both. The increased lung densities showed non-segmental distribution. However, these findings are non-specific and such opacities are seen in other diffuse lung diseases such as hypersensitive pneumonitis, BOOP and pulmonary edema. Pleural effusion (44% of reported cases including ours) and mediastinal lymphadenopathy were frequently seen, and pleural effusion with or without mediastinal lymphadenopathy could represent specific findings for this disease. The authors stress that in young patients with acute respiratory insufficiency with pleural effusion and/or mediastinal lymphadenopathy on the plain chest radiograph or on CT, the possibility of AEP should be considered in the differential diagnosis.

Acute Disease↗
PubMed1993

Structure, organization, and chromosomal mapping of the human macrophage scavenger receptor gene.

Macrophage scavenger receptors (MSR) mediate the binding, internalization, and processing of a wide range of negatively charged macromolecules. Functional MSR are trimers of two C-terminally different subunits that contain six functional domains. We have cloned an 80-kilobase human MSR gene and localized it to band p22 on chromosome 8 by fluorescent in situ hybridization and by genetic linkage using three common restriction fragment length polymorphisms. The human MSR gene consists of 11 exons, and two types of mRNAs are generated by alternative splicing from exon 8 to either exon 9 (type II) or to exons 10 and 11 (type I). The promoter has a 23-base pair inverted repeat with homology to the T cell element. Exon 1 encodes the 5'-untranslated region followed by a 12-kilobase intron which separates the transcription initiation and the translation initiation sites. Exon 2 encodes a cytoplasmic domain, exon 3, a transmembrane domain, exons 4 and 5, an alpha-helical coiled-coil, and exons 6-8, a collagen-like domain. The position of the gap in the coiled coil structure corresponds to the junction of exons 4 and 5. These results show that the human MSR gene consists of a mosaic of exons that encodes the functional domains. Furthermore, the specific arrangement of exons played a role in determining the structural characteristics of functional domains.

Amino Acid Sequence↗
PubMed1993

Charged collagen structure mediates the recognition of negatively charged macromolecules by macrophage scavenger receptors.

Macrophage scavenger receptors mediate the recognition of a wide range of negatively charged macromolecules including modified low density lipoproteins (LDL). Truncated bovine receptors lacking residues 330-342, which include the conserved lysine cluster of a collagen-like domain, were unable to degrade modified LDL in spite of their expression on the cell surface. Substitution of lysine 337 into alanine abolished the acetyl-LDL degradation and binding at 37 degrees C, but did not abolish the 4 degrees C binding. In contrast, substitution of more than 2 lysines in this region are needed to abolish the oxidized LDL degradation and 37 degrees C binding. Based on computational modeling of this domain, we propose that a "charged collagen" structure containing a lysine cluster forms a positively charged groove which specifically interacts with negatively charged ligands.

Amino Acid Sequence↗
PubMed1993

Purification, complete amino acid sequence and structural characterization of the heat-stable sweet protein, mabinlin II.

A new sweet protein, named mabinlin II, was extracted with 0.5 M NaCl solution from the seeds of Capparis masaikai Lévl. and purified by ammonium sulfate fractionation, carboxymethylcellulose-Sepharose ion-exchange chromatography and gel filtration. The sweetness of mabinlin II was unchanged by at least 48 h incubation at nearly boiling temperature. Purified mabinlin II thus obtained gave a single band having a molecular mass of 14 kDa on SDS/PAGE. In the presence of dithiothreitol, mabinlin II gave two bands having molecular masses of 4.6 kDa and 5.2 kDa on SDS/PAGE. Two peptides (A chain and B chain) were separated from reduced and S-carboxamidomethylated mabinlin II by HPLC. The amino acid sequences of the A chain and B chain were determined by the automatic Edman-degradation method. The A chain and B chain consist of 33-amino-acid and 72-amino-acid residues, respectively. The A chain is mostly composed of hydrophilic amino acid residues and the B chain also contains many hydrophilic residues. High similarity was found between the amino acid sequences of mabinlin II and 2S seed storage proteins, especially 2S albumin AT2S3 in Arabidopsis thaliana (mouse-ear cress).

Amino Acid Sequence↗
PubMed1993

Dynamical monitoring network system for perinatal care.

A new type of monitoring network system for perinatal care is proposed and has been developed. The patient monitoring system and data analyzing system are connected by a local area network (LAN). The doctor can retrieve past sampled data and results of data analysis, and make a detailed analysis at the same time that the patient is being monitored. The mainframe of the hospital information system (HIS) is connected with a data server in the perinatal care area via LAN. The database in perinatal care is supplied to the HIS and the doctor through this monitoring network system. If data sampled at maternity clinics or hospitals are once transmitted to the data server on LAN via the public telephone circuit, these data are available for the specialists on LAN. This function is utilized for supporting the obstetricians.

Computer Systems↗
PubMed1993

Case report: saccular aneurysm of the azygos vein simulating a paratracheal tumour.

We present a case of a large saccular aneurysm arising from the azygos arch in an asymptomatic 62-year-old man. Chest radiography showed a well-defined right paratracheal mass. Dynamic computed tomography revealed marked enhancement of the mass suggesting a vascular structure, but no flow void was demonstrated on magnetic resonance imaging, probably due to slow turbulent flow.

Aneurysm↗
PubMed1993

DNA binding properties of c-Myc-related bHLH/LZ oncoproteins.

Structural features and DNA binding properties of bacterially expressed c-Myc related oncoproteins were examined. The circular dichroism spectra demonstrated highly alpha-helical nature of these proteins. Dimerization and the DNA binding of these proteins were examined by electrophoretic mobility shift assay.

Circular Dichroism↗