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T Maruyama

Publications and source records attributed to T Maruyama.

At least 145 records · Page 8Linked to original sources
PubMed2000

Identification of a GPI-anchored type HDL-binding protein on human macrophages.

To identify the HDL3-binding proteins on human macrophages, we examined the involvement of GPI-anchored protein in the binding of HDL3, and tried to purify HDL3-binding protein. From membrane fractions of macrophages, we obtained 80- and 130-kDa HDL3-binding proteins by ligand blotting. Treatment of macrophages with phosphatidylinositol-specific phospholipase C (PI-PLC) significantly decreased the specific HDL3-binding in a dose-dependent manner. Furthermore, treatment with mannosamine, which blocks GPI-anchor formation, decreased specific HDL3-binding in a dose-dependent manner. PI-PLC treatment released from the cells the proteins with an M(r) of 80 kDa, which could also bind HDL3. PI-PLC as well as mannosamine treatment markedly reduced cholesterol efflux from macrophages in association with the decreased HDL-binding. Using HDL3-affinity chromatography, we purified 80-kDa GPI-anchored type HDL3-binding protein. In summary, we demonstrate the implication of 80-kDa GPI-anchored protein in the binding of HDL3 to human macrophages, which might have some role in reverse cholesterol transport.

Binding Sites↗
PubMed2000

Circular dichroism simulation shows a site-II-to-site-I displacement of human serum albumin-bound diclofenac by ibuprofen.

PURPOSE: The purpose of this study was to confirm the hypothesis that a site-II-to-site-I displacement takes place when some nonsteroidal anti-inflammatory drugs are displaced by another drug from their high-affinity binding site to a site of lower affinity on human serum albumin (HSA). METHODS: Diclofenac, sodium salt, was used as a representative example because of its prominent reversal of the Cotton effect. Effects of site-specific drugs on the free fraction of diclofenac were determined by equilibrium dialysis, and effects on induced circular dichroism (CD) of diclofenac bound to HSA were studied by CD and CD simulation techniques. RESULTS: Ibuprofen, a site-II-specific drug, altered the CD spectrum of the diclofenac-HSA complex at a molar ratio of 0.5 : 1 to that obtained at a higher ratio (5:1) without ibuprofen. The induced CD spectrum obtained in the presence of ibuprofen was very similar to one that assumed that all diclofenac displaced from its high-affinity binding site (site II) became rebound to a lower-affinity site (site I). The rebinding could be influenced by a free energy linkage between the two sites which would make site I (or parts thereof) more suitable for diclofenac binding. CONCLUSION: We have confirmed the existence of a site II-to-site I displacement, which is very striking and pharmacologically important, because the concentration of unbound drug being displaced is much lower than expected for a competitive mechanism.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

Association between diabetic retinopathy and genetic variations in alpha2beta1 integrin, a platelet receptor for collagen.

Platelets might be involved in the pathogenesis of diabetic microangiopathy. Wide interindividual variations in the density of a platelet collagen receptor (alpha2beta1 integrin or glycoprotein Ia/IIa) are reportedly associated with polymorphism(s) in the gene encoding the alpha subunit of the receptor, including a Bgl II polymorphism in intron 7. The aim of the present study was to determine the relationship between the Bgl II polymorphism and the susceptibility to diabetic microangiopathy. A case-control study comparing 227 patients with type II diabetes mellitus (119 with versus 108 without diabetic retinopathy) as well as 169 nondiabetic subjects demonstrated that genotypes with Bgl II (+) allele had a significant increase in the risk for retinopathy. The odds ratio for Bgl II (+/+) to Bgl II (-/-) was 3.41 (95% CI, 1.49-7.78, P =.0036) when analysis was confined to those with a disease duration of diabetes of 10 years or more. The present study suggests that the presence of a Bg II (+) allele is a genetic risk factor for diabetic retinopathy. (Blood. 2000;95:1560-1564)

Alleles↗
PubMed2000

Shell structure of nuclei in strong magnetic fields in neutron star crusts

By employing Strutinsky's treatment we demonstrate that the magnetic field gives rise to a phase shift of the shell oscillations in nuclear masses. The proton orbital magnetism is shown to enhance the nuclear shell effect especially when the field influence is comparable to the spin-orbit coupling. The magnetic field of the strength scale B approximately 10(16)-10(17) G is found to shift significantly the nuclear magic numbers of the iron region towards smaller mass numbers.

Journal Article↗
PubMed2000

FK506 binding protein from a thermophilic archaeon, Methanococcus thermolithotrophicus, has chaperone-like activity in vitro.

The in vitro protein folding activity of an FKBP (FK506 binding protein, abbreviated to MTFK) from a thermophilic archaeon, Methanococcus thermolithotrophicus, was investigated. MTFK exhibited FK506 sensitive PPIase (peptidyl prolyl cis-trans isomerase) activity which accelerated the speed of ribonuclease T1 refolding, which is rate-limited by isomerization of two prolyl peptide bonds. In addition, MTFK suppressed the aggregation of folding intermediates and elevated the final yield of rhodanese refolding. We called this activity of MTFK the chaperone activity. The chaperone activity of MTFK was also inhibited by FK506. Alignment of the amino acid sequences of MTFK with human FKBP12 showed that MTFK has two insertion sequences, consisting of 13 and 44 amino acids, at the N- and C-termini, respectively [Furutani, M., Iida, T., Yamano, S., Kamino, K., and Maruyama, T. (1998) J. Bacteriol. 180, 388-394]. To study the relationship between chaperone and PPIase activities of MTFK, mutant MTFKs with deletions of these insertion sequences or with amino acid substitutions were created. Their PPIase and chaperone activities were measured using a synthetic oligopeptide and denatured rhodanese as the substrates, respectively. The far-UV circular dichroism spectra of the wild type and the mutants were also analyzed. The results suggested that (1) the PPIase activity did not correlate with chaperone activity, (2) both insertion sequences were required for MTFK to take a proper conformation, and (3) the insertion sequence (44 amino acids) in the C-terminus was important for the chaperone activity.

Binding Sites↗
PubMed2000

Detection of amplification of a chromosomal fragment at 6p21 including the cyclin D3 gene in a glioblastoma cell line by arbitrarily primed polymerase chain reaction.

DNA from 10 human glioma cell lines was analyzed by arbitrarily primed polymerase chain reaction. By fingerprinting of the DNA fragments obtained, the presence of fragment Qx with an abnormal signal was detected in one of the glioblastoma cell lines, CCF-STTG1. The nucleotide sequence of this fragment of 387 base pairs showed no homology with any known sequences. Southern-blot analysis using Qx as a probe revealed that the abnormal signal was caused by amplification of DNA by about 50-fold. By analysis of radiation hybrid panels, the fragment was shown to be derived from a chromosomal region on 6p21. The cyclin D3 (ccnd3) gene and an EST locus, H40682, both of which were located in this region, were amplified by about 50-fold in this cell line. Two other loci, R75654 and M78872, flanking the Qx, CCND3 and H40682 loci, were not amplified, suggesting that the size of the amplicon was less than 62 cR. Since over-expression of the ccnd3 gene, but not the H40682 locus, was detected in the cell line CCF-STTG1, the increased amounts of cyclin D3 caused by gene amplification could be involved in the development and/or progression of this glioblastoma.

Blotting, Northern↗
PubMed2000

Characterization of native and recombinant peptidyl prolyl cis-trans isomerases derived from Methanococcus thermolithotrophicus based on cDNA sequence.

It is important to establish whether a recombinant protein is an authentic copy of the predicted cDNA sequence. In this study, recombinant protein for native peptidyl prolyl cis-trans isomerase (N-PPIase) and double-labeled (13C- and 15N-) protein (DL-PPIase) appeared on the sodium dodecyl sulfate (SDS) electropherograms as two bands for N-PPIase and four bands for DL-PPIase. Since the N-terminal amino acid residues of all bands were the same, we characterized these bands using the peptide mapping method and amino acid composition analysis. Peptide mapping of the proteins seemed to be almost identical but they could not reflect the whole amino acid sequences of the protein. The bands on the polyvinylidene difluoride (PVDF) membrane, electroblotted after SDS-polyacrylamide gel electrophoresis (SDS-PAGE), were hydrolyzed and their amino acid composition was analyzed using a highly sensitive 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) amino acid analysis and compared with the cDNA sequences for proteins. The matching score (sigma(T%-E%)2) for similarity of proteins was calculated by summation of the square difference between the theoretical (T%) and the experimental (E%) amino acid composition of the recombinant protein. The amino acid composition of all bands of both proteins showed more than 93% of the theoretical values. The major molecular weights of both proteins were 16812 and 17694 by electrospray ionization (ESI)-mass spectrometry. However, the purified proteins also contained minor compounds with Mr of 3721 for N-PPIase and 5285 for DL-PPIase. These compounds were considered to be nonpeptidyl products that comigrated with the protein. Similarities of the amino acid composition of the four bands were more than 98%. Our results indicate that AQC amino acid analysis is the most suitable method for characterization of a recombinant protein.

Amino Acids↗
PubMed2000

Construction of human-rodent hybrid cells containing single transferable fragments of human chromosome 10p.

The introduction of chromosome 10p into human glioblastoma or prostate cancer cells has been demonstrated to suppress their malignant phenotype, suggesting the presence of glioma or prostate tumor suppressor genes on 10p. As a resource for the fine mapping of these genes, a series of human-rodent hybrid cell lines containing single transferable fragments (STFs) of 10p were constructed. Normal chromosome 10 tagged with a neomycin-resistance gene on its short arm was fragmented by gamma-irradiation of 5-10krad, transferred into mouse L cells or Chinese hamster ovary cells by microcell-mediated chromosome transfer (MMCT), and then selected against G418. Thirty-three independent rodent-human hybrids carrying various-sized STFs were obtained. Polymerase chain reaction (PCR)-based genotyping revealed that these STFs contained the whole, or portions, of a 43-cM region on 10p14-pter and could be defined by 19 sequence-tagged-site (STS) markers. Using this panel of hybrids as donors for further MMCT, genes on the refined fragments could be transferred into other cells. This hybrid panel would therefore be a useful resource for the fine mapping of the genes on 10p14-pter to segments of about 2.4 cM by functional complementation.

Animals↗
PubMed2000

Molecular mechanisms, lipoprotein abnormalities and atherogenicity of hyperalphalipoproteinemia.

Hyperalphalipoproteinemia (HALP) is caused by a variety of genetic and environmental factors. Among these, plasma cholesteryl ester transfer protein (CETP) deficiency is the most important and frequent cause of HALP in the Asian populations. CETP facilitates the transfer of cholesteryl ester (CE) from high density lipoprotein (HDL) to apolipoprotein (apo) B-containing lipoproteins, and is a key protein in the reverse cholesterol transport system. The deficiency of CETP causes various abnormalities in the concentration, composition, and function of both HDL and low density lipoprotein (LDL). The significance of CETP in terms of atherosclerosis had been controversial. However, the in vitro evidence showed large CE-rich HDL particles in CETP deficiency are defective in cholesterol efflux. Similarly, scavenger receptor BI (SR-BI) knockout mice show a marked increase in HDL-cholesterol but accelerated atherosclerosis in atherosclerosis-susceptible mice. Recent epidemiological studies in Japanese-Americans and in Omagari area where HALP subjects with the intron 14 splicing defect of CETP gene are markedly frequent, have demonstrated an increased incidence of coronary atherosclerosis in CETP-deficient patients. Thus, CETP deficiency is a state of impaired reverse cholesterol transport which may possibly lead to the development of atherosclerosis. The current review will focus on the molecular mechanisms and atherogenicity of HALP, especially CETP deficiency.

Animals↗
PubMed2000

Age of onset, not type of onset, affects the positivity and evanescence of IA-2 antibody.

Autoantibody against IA-2 (IA-2A) was found to be discordant with autoantibody against glutamic acid decarboxylase (GADA) with respect to both positivity and titer in Japanese, the same as in Caucasians. In this study, 247 type 1 diabetic patients were tested in order to clarify how the type of onset, age of onset, and duration of diabetes affect the frequency and evanescence of IA-2A. Among the young onset patients, the frequency of IA-2A was higher (52.2%), but evanescent (54.5, 66.7 and 36.7% in the insulin therapy duration < or =1, 2-5 years, and > or =6 years groups, respectively), whereas among adult onset patients, the frequency was lower (19.3%) but persistent (19.6, 13.3 and 23.5%, respectively). In addition, in the follow-up study, two of three IA-2A-positive young onset patients converted to negative in only three years, while all five adult onset patients remained positive for over 5 years. Among the adult onset patients, IA-2A frequency was similar in the slowly progressive type and the abrupt onset type. In view of the above findings, IA-2A positivity and evanescence in type 1 diabetic patients appear to be affected by age of onset, not type of onset.

Adolescent↗
PubMed2000

Pacing-induced palmar sweating evaluated by unique hygrometer: possible implications of sympathetic activation during tachycardia.

Although reflex sympathetic activation is a major determinant of the haemodynamic tolerability of ventricular tachycardia (VT), the methods for evaluating this aspect during on-going VT remain invasive and complicated. Palmar sweating as an indirect but non-invasive measure of sympathetic activity was estimated by means of a unique hygrometer under right ventricular (RV) rapid pacing (up to 150 beats min-1) replicating VT, and concurrent monitoring of aortic blood pressure in five patients with various kinds of cardiac arrhythmias in our electrophysiological laboratory. The peak palmar sweating rate in arbitrary units was augmented as the RV pacing rate increased and was proportional to the pacing-induced fall in systolic blood pressure (SBP), with a correlation coefficient of more than 0.903 (P<0.006). The slope of linearity between the sweating rate and the fall in SBP varied among individual patients, with greater sweating amplitude in the younger patients even with the same extent of fall in SBP. This preliminary study suggests sympathetic acceleration caused by haemodynamic deterioration under simulated VT, and therefore this protocol may be able to predict the haemodynamic tolerability of sustained monomorphic VT.

Adult↗
PubMed2000

The 28.3 kDa FK506 binding protein from a thermophilic archaeum, Methanobacterium thermoautotrophicum, protects the denaturation of proteins in vitro.

Two families of FK506 binding protein (FKBP) type peptidyl-prolyl cis-trans isomerase (PPIase) have been found in Archaea. One is the 16-18 kDa short type FKBP family, and another is the 26-30 kDa long type FKBP family. The latter has a longer C-terminal region than the former. In this study, the 28.3 kDa long type FKBP gene from a thermophilic archaeum, Methanobacterium thermoautotrophicum, was expressed in Escherichia coli, and its gene product (MbFK) was characterized. The PPIase activity of MbFK was much lower than those of other FKBPs reported against oligopeptidyl substrates. MbFK protected green fluorescent protein (GFP) and rhodanese from thermal denaturation. Furthermore, MbFK suppressed the aggregation of chemically unfolded rhodanese and elevated the yield of its refolding although this activity was weaker than that of GroEL/ES. We made two deletion mutants, MbFK-N which lacked the C-terminal region, and MbFK-C which had only the C-terminal region. Far-UV CD spectra of these mutants showed that their secondary structures did not change from that of the wild-type. Whereas the PPIase activity of MbFK-N was low but detectable, that of MbFK-C was undetectable. The MbFK-C protected the thermal protein aggregation, and possessed a weak but significant aggregation suppressing activity against chemically unfolded protein. However, the MbFK-N did not suppress the aggregation of chemically unfolded rhodanese while it protected heat induced aggregation of rhodanese. These results may indicate that aggregation suppressing activity of MbFK-W against chemically unfolded protein are exerted mainly by its C-terminal domain while both domains contribute to thermal protein aggregation suppression.

Amino Acid Sequence↗
PubMed2000

In vivo and in vitro study of radio-frequency application with a new long linear probe: implication for the maze operation.

BACKGROUND: The maze operation for atrial fibrillation is effective but highly invasive. We tested, both in vitro and in vivo, a new technique for creating long linear atrial lesions with a custom-made, 25-mm long, stainless-steel, linear probe and a corresponding 500-kHz generator for assistance in the maze operation. METHODS: In the in vitro study with the isolated canine atria, the power of the delivered radio-frequency energy and the saline irrigating flow rate were changed independently, and the sizes of the lesions were measured. In the in vivo study radio-frequency energy was delivered to 4 portions (ie, the smooth and trabeculated portions of the right and left atria). The sizes of the lesions were measured, and the histologic features of the lesions were examined. Electrical isolation of the right atrial appendage from the remaining right atrium was attempted by using this linear probe. RESULTS: In the in vitro study the size of the lesion became larger as the delivered power was increased, although the lesion was limited when the flow rate was high. In the in vivo study the size of the lesion was equal at the 4 different sites. Histologic examinations demonstrated linear and transmural lesions, and electrophysiologic examinations revealed conduction block between the right atrial appendage and the remaining right atrium. CONCLUSIONS: The new original long linear probe was effective for creating transmural linear atrial lesions with the irrigation method, presenting the possibility of an intraoperative technique that mimics the maze procedure.

Animals↗
PubMed2000

Method for the synthesis of uric acid derivatives.

A general procedure to obtain tetra-substituted uric acid by stepwise N-alkylation is described. 2,6-Dichloropurine (1) was condensed with 1-propanol by Mitsunobu reaction to give 9-propyl congener (2). Treatment of 2 with ammonia gave adenine derivative (4a), which was converted to the 8-oxoadenine (5b) in 3 steps. Methylation of 5b proceeded site-specifically to give 6-amino-2-chloro-7,8-dihydro-7-methyl-9-propylpurin-8-one (6) as a sole product. Compound 6 was successively treated with NaNO2 and iodomethane to give 2-chloro-1,6,7,8-tetrahydro-1,7-dimethyl-9-propylpurin-6,8-dione (9) accompanied by the O6-methyl product (8) in 75% and 6.9%, respectively. After nucleophilic substitution of 9 with NaOAc, the product (11) was reacted with iodomethane to give the uric acid (12) and the 2-methoxy product (13) in 46% and 15.5%, respectively. However, the reaction of 11 with the benzylating agents gave only O-benzyl products (14a,b).

1-Propanol↗