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Biomedical subjects

I Shimada

Publications and source records attributed to I Shimada.

At least 127 records · Page 7Linked to original sources
PubMed1990

Binding modes of inhibitors of ribonuclease T1 as elucidated by analysis of two-dimensional NMR.

Aromatic proton and high field shifted methyl proton resonances of RNase T1 complexed with Guo, 2'GMP, 3'GMP, or 5'GMP were assigned to specific amino acid residues by analyses of the two-dimensional NMR spectra in comparison with the crystal structure of the RNase T1-2'GMP complex. These assignments were subsequently correlated to those of free RNase T1 [Hoffmann & Rüterjans (1988) Eur. J. Biochem. 177, 539-560]. The spatial proximities of amino acid residues as elucidated by NOESY spectra were found to be quite similar among free RNase T1 and the inhibitor complexes, showing that large conformational changes did not occur upon complex formation. However, small but appreciable conformational changes were induced, which were reflected by the systematic chemical shift changes of some amino acid residues in the active site. Furthermore, we confirmed that RNase T1 contains two specific binding sites, one for the guanine base and the other for the phosphate moiety. The inhibitors are forced to adapt their conformations to fit the guanine base and the phosphate moiety to each binding site on the enzyme. This is consistent with our previous studies that 2'GMP and 3'GMP take the syn form as a bound conformation, while 5'GMP takes the anti conformation around glycosidic bonds [Inagaki et al. (1985) Biochemistry 24, 1013-1020]. The slow-exchange process between free and bound forms involving Tyr42 and Tyr45 was found to be specific to the recognition of the guanine base.

Amino Acid Sequence↗
PubMed1990

Monoclonal antibody to blood group glycosyltransferases, produced by hybrids constructed with Epstein-Barr-virus-transformed B lymphocytes from a patient with ABO-incompatible bone marrow transplant and mouse myeloma cells.

A patient with chronic myeloid leukemia secreted an antibody to blood group glycosyltransferases after ABO-incompatible bone marrow transplantation (B recipient/O donor). Peripheral B lymphocytes from the recipient were transformed with Epstein-Barr virus, and then fused by polyethylene glycol with mouse myeloma cell line P3-X63/Ag8.653. After the cloning of the hybridoma cells, a cell line which produced human IgM antibody to blood group glycosyltransferases was established. The antibody completely neutralized B transferase activity at low concentration, while a larger amount of immunoglobulins was required to neutralize A transferase activity.

ABO Blood-Group System↗
PubMed1990

Forensic application of angiography on injured brain.

Craniocerebral angiography, injecting radiopaque contrast medium through the common carotid arteries under the normal blood pressure, was a very useful way to search the cerebral injuries, especially the location of arterial rupture. We think our post-mortem examination using angiography will open up a new way to investigate cerebral injuries.

Adolescent↗
PubMed1990

Deletion of D-helix in bovine pancreatic phospholipase A2.

D-Helix-deleted bovine pancreatic phospholipase A2 was designed using molecular mechanic calculations, and synthesized. Effects of the deletion on the enzymatic activity and on the structure were investigated. The enzymatic activity of the mutant protein was about 40% of that of the native one for a micellar substrate of 1,2-dioctanoyl-phosphatidylcholine. Although the Michaelis constant of the mutant enzyme was not changed, the catalytic constant was decreased. The dissociation constant of calcium ion was also changed. 1H NMR study revealed a slight conformation change around the active site of the mutant enzyme in addition to changes around the mutated region. The effect on the activity of the mutation seems to be due to the conformational changes around the active site.

Amino Acid Sequence↗
PubMed1990

[Free internal mammary artery for coronary bypass].

We studied 12 cases of free internal mammary artery (IMA) grafting. We used IMAs as free grafts mainly because of its shortness (6 cases 50%) and injury during dissection (4 cases 33%) and found the varicose change of saphenous vein in 5 cases (42%). Most of the grafting sites are distal parts of coronary arteries. Proximal anastomosis sites are other vein grafts (3 cases), other IMA grafts (3 cases), vein grafts interposing to the aorta (3 cases), and aorta (1 case). Patency rate of the free IMA grafts 4 weeks after operations was good (82%). Free IMA grafting is safe alternative to in situ IMA grafting when IMA grafts are short or injured and saphenous vein grafting is impossible.

Adult↗
PubMed1990

[Right ventricular outflow tract reconstruction in two neonates with pulmonary atresia and intact ventricular septum].

Two neonates, aged 8 and 18 days, with pulmonary atresia and intact ventricular septum underwent right ventricular outflow tract reconstruction with an autologous pericardial transannular patch. Preoperative cardiac catheterization revealed a tripartite right ventricular morphology with suprasystemic right ventricular morphology with suprasystemic right ventricular systolic pressure (right ventricular to left ventricular peak pressure ratio was 1.2 in case 1 and 2.0 in case 2). Right ventricular volume was 73.5% of normal and 115% of normal respectively. Generous resection of the infundibular myocardium was done and a patch was inserted with the heart kept beating as the perfusate temperature of 32 degrees C. In case 1 a modified Blalock-Taussig shunt was added on the postoperative day 21, because of the insufficient growth of the right ventricle, but in case 2 prostaglandin E1 could be discontinued on the postoperative day 9.

Female↗
PubMed1990

[Clinical experience of adjustable pulmonary artery banding].

Pulmonary artery banding has been a useful palliative procedure for infants with congenital cardiac anomalies associated with excessive pulmonary blood flow. We have experienced some cases that the band was not sufficient enough to reduce the pulmonary artery pressure in complex cardiac anomalies. Therefore, we developed a new adjustable pulmonary artery banding system which can be re-adjusted extrathoracically without reoperation. We used this system in seven infants with congenital cardiac lesions and obtained good results.

Heart Defects, Congenital↗
PubMed1989

Three novel oligosaccharides with the sialyl-Lea structure in human milk: isolation by immunoaffinity chromatography.

We have determined the structures of three novel oligosaccharides isolated from human milk using the monoclonal antibody MSW 113. These oligosaccharides were purified by affinity chromatography on a column of the immobilized monoclonal antibody and by high-performance liquid chromatography. From the results of 500-MHz 1H NMR spectroscopy and fast atom bombardment-mass spectrometry, their structures were deduced to be (formula; see text) These oligosaccharides bound to MSW 113 to nearly the same extent as sialyl-Lea hexasaccharide but bound to another sialyl-Lea structure-directed monoclonal antibody, NS 19-9, only weakly.

Carbohydrate Sequence↗
PubMed1989

Polypeptide chain fold of human transforming growth factor alpha analogous to those of mouse and human epidermal growth factors as studied by two-dimensional 1H NMR.

The 1H NMR spectrum of human transforming growth factor alpha (TGF-alpha) was analyzed almost completely by the sequential assignment method using two-dimensional NMR techniques. On the basis of the nearly complete sequence-specific resonance assignment, secondary and tertiary structures of human TGF-alpha in solution (pH 4.9, 28 degrees C) were determined to satisfy the upper limits of proton-proton distances derived from nuclear Overhauser effect experiments. Although human TGF-alpha and mouse epidermal growth factor (EGF) share 27% homology in amino acid sequence, the backbone chain folds in the two growth factors are quite similar. The structure and function of TGF-alpha is well characterized by the "mitten model" previously proposed for mouse EGF. The gross shape of the TGF-alpha molecule resembles a mitten. TGF-alpha interacts with the receptor as a mitten would grasp an object. However, there is an appreciable structural difference between the two growth factors in the back of the mitten that is formed by the N-terminal polypeptide segment. This is consistent with the evidence that the backs of these molecules are not involved in the receptor binding.

Amino Acid Sequence↗
PubMed1989

Accumulation of unique globo-series glycolipids in PC 12h pheochromocytoma cells.

In a previous paper, we reported the presence of a unique globo-series glycolipid as one of the major neutral glycolipid: Gal alpha 1-3Gal alpha 1-4Gal beta 1-4Glc beta 1-1' Cer, in the subcloned PC 12h pheochromocytoma cells (Ariga, T., Yu, R. K., Scarsdale, J. N., Suzuki, M., Kuroda, Y., Kitagawa, H., and Miyatake, T. (1988) Biochemistry 27, 5335-5340). Recently we found that the subcloned PC 12h cells accumulated other unusual neutral glycolipids. In order to characterize these glycolipids, PC 12h cells were subcutaneously transplanted into rats. The induced tumor tissue accumulated four minor neutral glycolipids, which were purified by droplet counter-current, Iatrobeads column, and preparative thin-layer chromatographies. These glycolipid structures were determined by fast atom bombardment-mass spectrometry, proton nuclear magnetic resonance spectroscopy, permethylation study, and sequential degradation with various exoglycosidases to be as follows: A, Fuc alpha 1-2Gal alpha 1-3Gal alpha 1- 4Gal beta 1-4Glc beta 1-1'Cer; B, GalNAc beta 1-3Gal alpha 1-3Gal alpha 1- 4Gal beta 1-4Glc beta 1-1'Cer; C, Gal alpha 1-3Gal alpha 1-3Gal alpha 1- 4Gal beta 1-4Glc beta 1-1'Cer; and D, Gal alpha 1-3Gal alpha 1-3Gal alpha 1- 3Gal alpha 1-4Gal beta 1-4Glc beta 1-1'Cer. Glycolipids A and B were tentatively characterized in normal rat small intestine (Breimer, M. E., Hansson, G. C., Karlsson, K.-A., and Leffler, H. (1982) J. Biol. Chem. 257, 557-568; Angstrom, J., Breimer, M. E., Falk, K.-E., Hansson, G. C., Karlsson, K.-A., and Leffler, H. (1982) J. Biol. Chem. 257, 682-688). Glycolipids C and D have not been reported in the literature.

Adrenal Gland Neoplasms↗
PubMed1989

N-terminal half of a mitochondrial presequence peptide takes a helical conformation when bound to dodecylphosphocholine micelles: a proton nuclear magnetic resonance study.

Two-dimensional proton nuclear magnetic resonance (NMR) spectra of a synthetic peptide (p25) corresponding to the amino-terminus of the yeast mitochondrial cytochrome oxidase subunit IV precursor protein have been analyzed. Sequence-specific resonance assignments of the peptide have been made in the presence of micelles of a phospholipid analog, perdeuterated dodecylphosphocholine (DPC), with the aid of such techniques as HOHAHA, DQF-COSY, and NOESY. The interresidue nuclear Overhauser effects (NOEs) indicate that the N-terminal half of p25 (S3-F11) takes a helical structure while the C-terminal half does not take a regular secondary structure. Addition of DPC to the solution of p25 induced chemical shift changes only of the resonances from the residues in the N-terminal half, suggesting that the N-terminal half of p25 is directly involved in binding to DPC. The induced helical structure in the N-terminal half at a lipid-water interface may be important in the ability of this presequence to direct a "passenger" protein into mitochondria.

Choline↗
PubMed1989

Binding modes of inhibitors to ribonuclease T1 as elucidated by the analysis of two-dimensional NMR.

Aromatic proton and high field shifted methyl proton resonances of RNase T1 complexed with Guo, 2'GMP, 3'GMP or 5'GMP were assigned to specific amino acid residues by 2D-NMR spectra in comparison with the crystal structure of RNase T1-2'GMP complex. The spatial proximities of amino acid residues as elucidated by NOESY spectra were found to be quite similar among free RNase T1 and the inhibitor complexes, showing that large conformational changes did not occur upon complex formation. However, small but appreciable conformational changes were induced which were reflected by the systematic chemical shift changes of some amino acid residues in the active site. Furthermore, we confirmed that RNase T1 contains two specific binding sites, one for the guanine base and the other for the phosphate moiety. The inhibitors are forced to adapt their conformations to fit the guanine base and the phosphate moiety to each binding site on the enzyme. This is consistent with our previous studies that 2'GMP and 3'GMP take syn form as a bound conformation, while 5'GMP takes anti conformation around glycosidic bonds.

Endoribonucleases↗
PubMed1989

[Pulmonary hypertensive crisis after open heart surgery].

Three patients with pulmonary hypertensive crisis (PHC) after open heart surgery for ventricular septal defect are reported. These patients ranged in age from 2 to 47 months, with Rp from 7.0 to 10.6 U.m2, Pp/Ps from 0.67 to 1.0, and Qp/Qs from 1.6 to 1.79. Intraoperative lung biopsy showed pulmonary vascular obstructive disease of Health-Edwards grade 2 in each patient. Atelectasis or pleural effusion on their chest-XP films was found when PHC occurred. The PHC course of the last case was recorded continuously on ABP, PAP and LAP. Administration of prostaglandin-E1 directly through the pulmonary arterial catheter was effective on PHC. Continuous recording of ABP, PAP and LAP during the episode was useful to differentiate PHC from acute left heart failure and/or acute right heart failure.

Alprostadil↗
PubMed1988

1H-NMR investigation of the interaction between RNase T1 and a novel substrate analog, 2'-deoxy-2'-fluoroguanylyl-(3'-5')uridine.

The interaction between RNase T1 and a non-hydrolysable substrate analog, 2'-deoxy-2'-fluoroguanylyl-(3'-5')uridine (GfpU), was investigated using 1H-NMR spectroscopy. In the complex, the Gfp portion takes the syn form around the glycosidic bond and the 3'-endo form for the ribose moiety, similar to those found in 3'-GMP and 2'-deoxy-2'-fluoroguanosine 3'-monophosphate (Gfp). However, in contrast to the cases of these two inhibitors, the complex formation with GfpU at pH 6.0 was found to shift the His-40 C2 proton resonance of RNase T1 to high field as much as 1 ppm. At pH 6.0, this histidine residue appears to be unprotonated in the complex, but is protonated in the free enzyme (pKa of His-40 being 7.9). His-40, rather than Glu-58, is probably involved in the catalytic mechanism as a Lewis base, supporting the recent results from site-directed mutagenesis.

Aspergillus↗