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T Fukui

Publications and source records attributed to T Fukui.

At least 73 records · Page 4Linked to original sources
PubMed1996

Affinity labeling of Escherichia coli histidyl-tRNA synthetase with reactive ATP analogues. Identification of labeled amino acid residues by matrix assisted laser desorption-ionization mass spectrometry.

Recent affinity labeling studies have revealed that dimeric histidyl-tRNA synthetase from Escherichia coli displayed half-of-the-sites reactivity toward labeling with pyridoxal 5'-phosphate [Kalogerakos, T., Hountondji, C., Berne, P. F., Dutka, S. & Blanquet, S. (1994) Biochimie (Paris) 76, 33-44]. In the present report, affinity labeling studies were conducted by using other ATP analogues such as pyridoxal 5'-diphospho-5'-adenosine (pyridoxal-ppAdo), pyridoxal 5'-triphospho-5'-adenosine (pyridoxal-pppAdo), pyridoxal 5'-diphosphate (pyridoxal-P2) and 5'-p-fluorosulfonylbenzoyladenosine (FSO2BzAdo). The histidine-dependent isotopic [32P]PP/ATP exchange activity of His-tRNA synthetase was rapidly and completely lost upon incubation with either pyridoxal-ppAdo, pyridoxal-pppAdo or pyridoxal-P2, followed by reduction with sodium borohydride. Complete inactivation of His-tRNA synthetase corresponded to the incorporation of 2.8 mol of either pyridoxal-ppAdo or pyridoxal-P2/mol dimeric synthetase. Incubation of His-tRNA synthetase with FSO2BzAdo also resulted in a complete inactivation of the synthetase. However, contrasting with the pyridoxal derivatives, the plot of the residual enzymatic activity against the amount of covalently bound FSO2BzAdo appeared biphasic. In the early stages of inactivation, the relationship between the amount of residual activity and FSO2BzAdo incorporation was linear and extrapolated to a stoichiometry of 1.1 mol reagent/mol His-tRNA synthetase, suggesting that the labeling of one subunit was sufficient to inactivate one dimeric His-tRNA synthetase molecule. At longer incubation periods, additional reagent incorporation occurred and culminated at 2.5 mol label/mol His-tRNA synthetase. Excess of MgATP protected the enzyme against inactivation by either studied reagent. The labeled amino acid residues were identified by matrix-assisted-laser-desorption-ionization mass spectrometry, by measuring the peptide mass increase caused by the reagents. An identical set of four lysyl residues (Lys2, Lys118, Lys369 and Lys370 of His-tRNA synthetase) was found attached to pyridoxal-ppAdo or pyridoxal-P2. In addition, pyridoxal-ppAdo labeled the alpha-amino group of the N-terminal alanine. In a His-tRNA synthetase sample having incorporated 2.5 mol FSO2BzAdo/mol), the labeled amino acid residues were Lys118, Lys196, Tyr262 (or Tyr263), Lys369 and Lys377. Whatever the used reagent, Lys118 appeared to be the predominantly labeled residue, Lys118 belongs to fragment 112-124 (RHERPQK-GRYRQF) corresponding to motif 2 of class 2 aminoacyl-tRNA synthetases. The other modified lysyl residues (lysines 369, 370 and 377) are close to the catalytic motif 3, in the C-terminal region of the synthetase. Tyr262 and Tyr263 belong to a fragment 256-263 (LVRGLDYY) highly conserved among all known His-tRNA synthetase primary structures. Examination of the recently solved structure of crystalline E. coli His-tRNA synthetase [Amez, J. G., Harris, D. C., Mitschler, A., Rees, B., Francklyn, C. S. & Moras, D. (1995) EMBO J. 14, 4143-4155] shows that, with the exception of lysines 369, 370 and 377, the location of which may account for peculiar accessibility and reactivity, all the amino acid residues identified in this study map near the enzyme nucleotide-binding site, at the N-terminal catalytic domain of the synthetase.

Adenosine Triphosphate↗
PubMed1996

p22phox is a critical component of the superoxide-generating NADH/NADPH oxidase system and regulates angiotensin II-induced hypertrophy in vascular smooth muscle cells.

Superoxide anion formation is vital to the microbicidal activity of phagocytes. Recently, however, there is accumulating evidence that it is also involved in cell growth in vascular smooth muscle cells (VSMCs). We have shown that the hypertrophic agent angiotensin II stimulates superoxide production by activating the membrane-bound NADH/NADPH oxidase and that inhibition of this oxidase attenuates vascular hypertrophy. However, the molecular identity of this oxidase in VSMCs is unknown. We have recently cloned the cytochrome b558 alpha-subunit, p22(phox) (one of the key electron transfer elements of the NADPH oxidase in phagocytes), from a rat VSMC cDNA library, but its role in VSMC oxidase activity remains unclarified. Here we report that the complete inhibition of p22(phox) mRNA expression by stable transfection of antisense p22(phox) cDNA into VSMCs results in a decrease in cytochrome b content, which is accompanied by a significant inhibition of angiotensin II-stimulated NADH/NADPH-dependent superoxide production, subsequent hydrogen peroxide production, and [3H]leucine incorporation. We provide the first evidence that p22(phox) is a critical component of superoxide-generating vascular NADH/NADPH oxidase and suggest a central role for this oxidase system in vascular hypertrophy.

Angiotensin II↗
PubMed1996

A dual computed tomography linear accelerator unit for stereotactic radiation therapy: a new approach without cranially fixated stereotactic frames.

PURPOSE: To perform stereotactic radiation therapy (SRT) without cranially fixated stereotactic frames, we developed a dual computed tomography (CT) linear accelerator (linac) treatment unit. METHODS AND MATERIALS: This unit is composed of a linac, CT, and motorized table. The linac and CT are set up at opposite ends of the table, which is suitable for both machines. The gantry axis of the linac is coaxial with that of the CT scanner. Thus, the center of the target detected with the CT can be matched easily with the gantry axis of the linac by rotating the table. Positioning is confirmed with the CT for each treatment session. Positioning and treatment errors with this unit were examined by phantom studies. Between August and December 1994, 8 patients with 11 lesions of primary or metastatic brain tumors received SRT with this unit. All lesions were treated with 24 Gy in three fractions to 30 Gy in 10 fractions to the 80% isodose line, with or without conventional external beam radiation therapy. RESULTS: Phantom studies revealed that treatment errors with this unit were within 1 mm after careful positioning. The position was easily maintained using two tiny metallic balls as vertical and horizontal marks. Motion of patients was negligible using a conventional heat-flexible head mold and dental impression. The overall time for a multiple noncoplanar arcs treatment for a single isocenter was less than 1 h on the initial treatment day and usually less than 20 min on subsequent days. Treatment was outpatient-based and well tolerated with no acute toxicities. Satisfactory responses have been documented. CONCLUSION: Using this treatment unit, multiple fractionated SRT is performed easily and precisely without cranially fixated stereotactic frames.

Brain Neoplasms↗
PubMed1996

Specialty choice and understanding of primary care among Japanese medical students.

To assess specialty choice and understanding of primary care among Japanese medical students, all students from seven Japanese medical schools (three public and four private) were surveyed, using a written questionnaire. A total of 3377 students provided data for the study. Of the students surveyed, 89.8% wanted to become clinicians, and 79.3% wanted to have general clinical ability. About half of the respondents, 54.9%, replied that they had some, or great, interest in primary care, but it was found that their understanding of primary care was inadequate. Almost half (56.3%) of the students answered that they had some idea of what a general practitioner did. This proportion was nearly the same through all years of medical school. While 1245 (36.9%) students (most of them in the fifth or sixth year) replied that they had received some clinical training while working in hospitals, only 203 (6.0%) students had worked in private clinics (the sites where most primary care is still provided), and 129 (3.8%) students had experience in providing home visits and home care. An even greater number, 64.3%, replied that they had inadequate information about the career options available to them. The study found that although many Japanese medical students want to obtain broad clinical competence, their understanding of primary care is insufficient. In order to increase the number of primary care providers the system of medical education in Japan must provide primary care doctors to act as role models, and must make available information about postgraduate primary care programmes. These programmes need to be increased, as do rewarding positions for programme graduates.

Career Choice↗
PubMed1996

Primary progressive apraxia in Pick's disease: a clinicopathologic study.

A 62-year-old right-handed man gradually experienced increasing difficulty with speech and manual dexterity. He had apraxia of speech, buccofacial apraxia, and complex limb apraxia as well as terminal dementia. At autopsy, focal cortical atrophy, neuronal loss, and neuropil rarefaction in the second and third cortical layers were most prominent in the left opercular, lower precentral, superior parietal, and left temporal pole. Numerous Pick bodies were diffusely present in the temporal and posterior frontal lobes and, to a lesser degree, in the superior parietal lobule. This report demonstrates an association between the distribution of Pick's pathology and several apraxic impairments.

Apraxias↗
PubMed1996

Allelotype analysis in mouse hepatocellular carcinomas; frequent homozygous deletion of mouse homolog of p16/CDKN2 gene on chromosome 4 in culture.

Because allelotype analysis of many tumors has been important in the identification of new tumor suppressor genes, here we have analyzed hepatocellular carcinomas (HCCs) derived from F1 hybrid mice between C3H and MSM in detail. The analysis showed no allelic loss in primary HCCs, while the loss was detected in tumor cell lines established from HCCs. Recently, a candidate tumor suppressor gene termed p16/CDKN2, which was located near the interferon gene cluster on human chromosome 9p21, was identified by virtue of its frequent homozygous deletion in cell lines derived from many different tumor types. Since frequent allelic imbalances in the D4MIT9 locus and loss of heterozygosity in the alpha-interferon gene which was located near the mouse homolog of p16/CDKN2 (mouse p16) gene were detected in tumor cell lines, we investigated homozygous deletion of the mouse p16 gene by the comparative multiplex PCR method. The analysis revealed frequent homozygous deletion of the gene in thirteen of the tumor cell lines (13/25, 52%), but not in primary HCCs (0/25, 0%). These data indicate that gene deletions including the mouse p16 gene on chromosome 4 in tumor cell lines occur during the culture and that allelic imbalances are uncommon in mouse primary HCCs. Our results suggest that mouse p16 plays an important role in mouse hepatocarcinogenesis in vivo in progression or immortalization in vitro.

Alleles↗
PubMed1996

Estimation of the prevalence of non-insulin dependent diabetes mellitus in a rural area of Japan.

The objective of this paper is to describe a method of estimating the prevalence of non-insulin dependent diabetes mellitus (NIDDM) in a community. We first counted subjects with previously diagnosed NIDDM and those newly diagnosed by use of the 75-gram oral glucose tolerance test (OGTT). We then used the OGTT data to predict the prevalence of NIDDM at different levels of fasting plasma glucose (FPG) among the subjects who did not undergo the OGTT. Data were derived from 3,614 residents aged 20 years and older in a rural area where population-based screening for NIDDM was performed using FPG or post-prandial plasma glucose (PG). Of the 318 participants who underwent an OGTT in 1992, 35 (11.0%) were judged to have NIDDM by the 2-hour PG criterion. We applied the above-described method to the 1,179 subjects who had anFPG but failed to undergo the OGTT. The estimated prevalence of NIDDM, which included the previously diagnosed group, the newly diagnosed group and the expected group, was calculated. The estimated prevalence of diabetes in this population aged 20 years and older turned out to be 6.1% (95% CI: 5.3-6.9). As a validation study, the same method was applied to 220 subjects who did not undergo the OGTT in 1992 but did so in 1994. The actual prevalence of NIDDM among these subjects was compared to the prevalence expected from the 1992 data by our method. The actual value was within the 95% confidence interval of the expected value.

Adult↗
PubMed1996

Partner notification program and possibility of including it in the HIV prevention strategies in Japan.

This article discusses the possibility of implementing partner notification program as a part of HIV prevention strategy in Japan. Relevant factors, like HIV seroprevalence, general population attitudes toward HIV, legislation, resources, barriers, behavioral changes, cost and effectiveness are analyzed in Japanese perspectives. Effectiveness of this program is also predicted based on the two informal contact tracing program in Japan. At the same time a review was made on the global perspectives of partner notification program and operational procedures are also outlined. Published literatures were investigated regarding prevalence of new HIV infection among the partners who underwent testing (11-39%), cost per new HIV positive case found (US $810-3,205), and secondary infection rate (11-20%) in Japan. Having considered all relevant factors we recommend that the partner notification program be implemented, initially in a limited area, then all over Japan. Further analysis on cost-benefit of this program remains to be done.

Adult↗
PubMed1996

Studies on fatigue of night duty workers at a newspaper office.

Fatigue of night duty workers in different divisions of a newspaper office was investigated by physiological methods such as the Blinker, Flicker and grip methods. The relationship between fatigue and hematological parameters such as hemoglobin (Hb), the hematocrit (Ht), serum-free amino acid levels, and indices of liver function such as the GOT and GPT levels were also examined. The composing and press room workers mainly complained of the subjective symptom of muscle fatigue, while workers in the photo-engraving and editorial departments mainly complained of mental fatigue. The overall rate of fatigue in the newspaper office was about 38.1%, but varied from one division to another, being especially high in the photo-engraving and editorial departments. The subjects with fatigue had low levels of serum GOT and GPT and high levels of serum-gluconeogenic amino acids, such as aspartic acid, glutamic acid, prolin, glycine, and alanine. These altered levels of serum-free amino acids and GOT and GPT seemed to be due to increased secretion of adrenal corticoid hormone caused by the stress of fatigue.

Adult↗
PubMed1996

Prolonged exposure to agonist results in a reduction in the levels of the Gq/G11 alpha subunits in cultured vascular smooth muscle cells.

Recent studies have shown that G proteins are a potential regulatory site in the transmembrane signaling cascade. The aim of this study was to examine the effects of prolonged agonist exposure on expression of the Gq class of G protein alpha subunits (G alpha q/G alpha 11) in cultured rat vascular smooth muscle cells (VSMC). Treatment with 100 nM angiotensin II (Ang II) led to a substantial sustained down-regulation of cellular levels of immunologically detectable G alpha q/G alpha 11 by 50% within 6 hr. The effect of Ang II was dose dependent with an EC50 of 2 nM and was specifically blocked by the vascular type-1 Ang II receptor-specific antagonist losartan. The Ang II-induced reduction in cellular levels of G protein alpha subunits was specific for G alpha q/G alpha 11. The calcium ionophore ionomycin or activators of ubiquitous protein kinases (phorbol-12-myristate-13-acetate, forskolin, and 8-bromo-cGMP) did not mimic the effects of Ang II. However, [Arg8]vasopressin also induced a significant loss in cellular G alpha q/G alpha 11 levels. Ang II-induced G alpha q/G alpha 11 down-regulation was reversed by prevention of cellular receptor processing with phenylarsine oxide or chronic potassium depletion. The effects of Ang II on G alpha q/G alpha 11 levels were inhibited when protein kinase C activity was abolished. G alpha q mRNA levels were down-regulated by 30% after 4-hr incubation with Ang II, in part by transcriptional regulation. Although a short term vasopressin pretreatment had no effect on inositol-1,4,5-trisphosphate (IP3) generation in response to subsequent Ang II stimulation, a partial heterologous desensitization of the IP3 response was induced after a long term vasopressin pretreatment, which concurrently down-regulated cellular G alpha q/G alpha 11 levels. Homologous desensitization of IP3 generation on a second Ang II stimulation was observed after both a short and long term Ang II pretreatment. In conclusion, prolonged exposure to Ang II induces down-regulation of cellular G alpha q/G alpha 11 levels in intact VSMC. The effect of Ang II appears to be mediated by the signaling pathway sensitive to inhibition of receptor processing. The present study raises the possibility that agonist-induced G alpha q/G alpha 11 down-regulation participates in the mechanism of long term desensitization of the G alpha q/G alpha 11-mediated signaling system in VSMC.

Angiotensin II↗
PubMed1996

[Successful surgical treatment for fungal endocarditis involving the aortic valve: report of a case].

A 50-year-old man who had undergone successful aortic valve replacement for fungal endocarditis was presented. He had been doing well until October 1993, when he suddenly developed shock with high fever. In two weeks he recovered from septic shock with vigorous medical treatment including intravenous administration of antibiotics. The infecting organism was not detected on repeated blood cultures. Four months later he was admitted to our hospital because of left heart failure. Although he was afebrile on admission, a two dimensional echocardiogram revealed vegetation on the aortic valve and massive aortic regurgitation. Inflammatory signs persisted and the vegetation increased in size, and therefore an aortic valve replacement was performed. A surgical specimen of the aortic valve revealed perforation in each of three cusps and vegetation on the non-coronary cusp. Pathological exploration revealed typical colonies of fungi. Following the diagnosis of fungal endocarditis, administration of an anti-fungal drug was started. His post-operative course was uneventful, and there was no evidence of recurrence with the anti-fungal medication for one year postoperatively.

Antifungal Agents↗
PubMed1996

Serial change of mitral regurgitation after mitral valve repair: comparison of anterior with posterior leaflet lesions.

Mitral valve repair is an important operative procedure for correcting mitral regurgitation (MR). However, serial change of residual MR after operation has not been reported. Serial change of MR after mitral valve repair was evaluated by transesophageal color Doppler echocardiography (TEE). Twenty-six patients undergoing mitral valve repair for MR during 1987 to 1991 were examined by TEE just after operation, 6 months after operation, and late follow-up period (mean 3.7 years). Thirteen patients had a lesion of the anterior mitral leaflet before operation (group A). Thirteen patients had a lesion of the posterior mitral leaflet before operation (group P). The MR area was measured by TEE at each stage after operation. In group A, the MR area at late follow-up increased significantly compared with just after operation (1.1 vs 4.3 cm2, p < 0.001). In group P, the MR area at late follow-up did not increase significantly compared with just after operation (0.6 vs 1.3 cm2, p = NS). In conclusion, MR does not increase after mitral valve repair in patients with posterior mitral valve repair, but MR may increase at late follow-up after operation for anterior mitral valve prolapse.

Echocardiography↗
PubMed1995

Processing and activation of recombinant mouse mastocytoma histidine decarboxylase in the particulate fraction of Sf9 cells by porcine pancreatic elastase.

Mature 53 kDa histidine decarboxylase (HDC) peptide is produced from a precursor 74 kDa peptide. The mechanism of specific cleavage by processing enzyme is unknown. Using the recombinant mouse 74 kDa HDC, we found that porcine pancreatic elastase specifically converted the inactive 74 kDa HDC to its active form of 53 kDa HDC.

Animals↗
PubMed1995

Prostaglandin E2 at priming of naive CD4+ T cells inhibits acquisition of ability to produce IFN-gamma and IL-2, but not IL-4 and IL-5.

We investigated the effect of prostaglandin E2 on the acquisition of cytokine-producing ability by naive CD4+ T cells in human cord blood. Naive CD4+ T cells were stimulated for 3 days with mouse monoclonal anti-CD3 Ab, then washed and expanded in IL-2-containing medium for 3 more days. These activated T cells produced IL-2, IL-4, IL-5, and IFN-gamma upon stimulation with PMA and ionomycin. PGE2 added at priming of naive T cells inhibited the production of IL-2 and IFN-gamma, but not of IL-4 and IL-5, in a dose-dependent manner. This change in the cytokine production profile induced by PGE2 was maintained in T cells restimulated with anti-CD3 in the absence of PGE2, expanded by IL-2, and stimulated with PMA and ionomycin. The mRNA expression of IFN-gamma and IL-2, but not that of IL-4, was also decreased in these cells. Forskolin and dibutyryl cAMP had a similar effect. PGE2 must exist at an early stage of T cell activation to inhibit priming for IL-2 and IFN-gamma production. PGE2 also showed this effect, even in the presence of exogenous IFN-gamma, at the primary stimulation. These results indicate that PGE2 inhibits the acquisition of the ability to produce IL-2 and IFN-gamma by acting directly on naive T cells. Our results suggest that PGE2 plays a role in facilitating the development of the Th2-type cytokine production profile.

Animals↗