Biomedical subjects

A Takeuchi

Publications and source records attributed to A Takeuchi.

At least 73 records · Page 4Linked to original sources

PubMed1999

Short-term treatment with troglitazone decreases bone turnover in patients with type 2 diabetes mellitus.

Poorly controlled type 2 or non-insulin dependent diabetes mellitus (NIDDM) patients exhibit high bone turnover, which decelerate with treatment according to the degree of improvement in glycemic control. In adults, higher bone turnover results in rapid bone loss. Therefore, deceleration of bone turnover is beneficial for bone. Troglitazone (Tro), a new anti-diabetic drug, is a thiazolidinedione (TZD) which promotes adipocyte differentiation by activating peroxisome proliferator activated receptor gamma (PPARgamma). Because, in the bone marrow, adipocytes and osteoblasts originate in common mesenchymal stem cells that are also essential for osteoclastogenesis, TZDs may directly affect bone metabolism. Thus, we examined the effects of Tro on metabolic bone markers in type 2 DM patients. Tro (400 mg/day) was administered to 33 type 2 DM patients for four weeks. The day before and four weeks after starting Tro, serum and urine samples were collected after overnight fasting. Metabolic bone markers and glycemic indices were assessed. As bone resorption markers, urinary free and total deoxypyridinoline as well as urinary collagen type I C-terminal telopeptide were measured; as bone formation markers, serum bone type and total alkaline phosphatase (BALP and ALP) levels along with osteocalcin (OC) were used. No significant changes in fasting plasma glucose or HbA1c levels were observed in our short-term treatment with Tro. All the bone resorption markers, BALP and ALP were significantly decreased. OC was not significantly changed. The discrepant changes of OC from all the other metabolic bone markers suggest limitation of the use of OC as a reliable bone formation marker in diabetics. Our results that Tro decreased metabolic bone markers before significantly improving glucose metabolism suggest that it has direct effects on bone and decreased bone turnover. TZDs may spare bone mass in NIDDM subjects through its dual effects on glucose and bone metabolism.

Aged↗

PubMed1999

Cloning and functional characterization of a new multispecific organic anion transporter, OAT-K2, in rat kidney.

We have isolated a cDNA coding a new organic anion transporter, OAT-K2, expressed specifically in rat kidney. The OAT-K2 cDNA had an open reading frame encoding a 498-amino acid protein (calculated molecular mass of 55 kDa) that shows 91% identity with the rat kidney-specific organic anion transporter, OAT-K1. Reverse transcription-coupled polymerase chain reaction analyses revealed that the OAT-K2 mRNA was expressed predominantly in the proximal convoluted tubules, proximal straight tubules, and cortical collecting ducts. When expressed in Xenopus oocytes, OAT-K2 stimulated the uptake of hydrophobic organic anions, such as taurocholate, methotrexate, folate, and prostaglandin E2, although its homolog OAT-K1 transported methotrexate and folate, but not taurocholate and prostaglandin E2. In MDCK cells stably transfected with the OAT-K1 and OAT-K2 cDNAs, each transporter was localized functionally to the apical membranes and showed transport activity similar to that in the oocyte. Moreover, the efflux of preloaded taurocholate was also enhanced across the apical membrane in OAT-K2 transfectant. The taurocholate transport by OAT-K2-expressing cells showed saturability (Km = 10.3 microM). Several organic anions, bile acids, cardiac glycosides, and steroids had potent inhibitory effects on the OAT-K2-mediated taurocholate transport in the transfectant. These findings suggest that the OAT-K2 participates in epithelial transport of hydrophobic anionic compounds in the kidney.

Amino Acid Sequence↗

PubMed1999

[5'-Nucleotidase].

Explore the source record for details and available documents.

5'-Nucleotidase↗

PubMed1999

A case of 43-year-old fighter pilot with bronchial asthma.

A Japan Air Self-Defense Force (JASDF) fighter pilot with adult onset atopic bronchial asthma was successfully returned to flying status. This was against the common wisdom of most Japanese military flight surgeons. Bronchial asthma generally results in permanent disqualification from flying duties because of possible acute incapacitation during flight. This JASDF pilot was treated with inhaled medications, including beclomethasone, for 6 mo with suppression of all clinical symptoms. All medications were discontinued and the pilot was observed for another 7 mo before resumption of flying status. This aeromedical disposition was based on the thinking that his long asymptomatic period indicated bronchial inflammation was resolved, bronchial reactivity was improved, and thus the risk of exacerbation was reduced.

Adult↗

PubMed1999

Studies of glomerular permeability factor (GPF) in focal segmental glomerular sclerosis and the relationship between GPF and vascular permeability factor (VPF).

BACKGROUND: We previously demonstrated that the supernatants of cultured concanavalin-A (con-A) stimulated peripheral blood mononuclear cells (PBMC) from patients with minimal change nephrotic syndrome (MCNS) increased the urinary protein excretion in injected rats and suggested that PBMC released a factor, which we called glomerular permeability factor (GPF), changes in the glomerular permeability and thus resulted in proteinuria in MCNS. MATERIAL AND METHODS: In this study we investigated the GPF activity in focal segmental glomerular sclerosis (FGS) and other conditions of chronic glomerulonephritis (CGN), and also the relationship between GPF and vascular permeability factor (VPF). In experiment 1 the supernatants of the cultured con-A stimulated PBMC from patients with 10 FGS, 5 other CGN and 10 controls were tested regarding their ability to produce GPE The GPF activity was defined as positive when the 8-hour urinary protein excretion after the injection of the supernatant in Sprague-Dawley rats exceeded the mean value plus 2 standard deviations (M + 2 SD) of that before injection. RESULTS: Three out of 10 FGS patients and 1 membranous nephropathy patient out of the 5 other CGN patients were positive for GPF activity. In experiment 2 the relationship between GPF and VPF was analyzed using culture supernatants of PBMC from 10 nephrotic MCNS patients and 15 controls. The VPF activity was measured following the method developed by Ovary [1975]. All 7 cases that were positive for GPF activity were simultaneously positive for VPF activity. On the other hand, 16 cases that were positive for VPF activity were not always positive for GPF activity (7 cases were positive and 9 were negative for VPF activity). CONCLUSION: Experiments 1 and 2 thus suggested that GPF was not active in MCNS alone, but also in other CGN conditions and it was therefore not considered to be the same factor/substance(s) as VPF.

Adolescent↗

PubMed1998

Imaging X-ray fluorescence microscope with a Wolter-type grazing-incidence mirror.

A Wolter-type grazing-incidence mirror was used as an objective for an imaging X-ray fluorescence microscope. The microscope was constructed at the beamline 6C2 of the Photon Factory. The shortest wavelength used was approximately 0. 1 nm, which was limited by the grazing-incidence angle of the mirror. To demonstrate the possibility of recording X-ray fluorescence images, several fine grids were used as test specimens. Characteristic X-rays emitted from each specimen could be clearly imaged. Spatial resolution was estimated to be better than 10 micro m.

Journal Article↗

PubMed1998

Sequence analysis of the Porphyromonas gingivalis dipeptidyl peptidase IV gene.

We previously constructed a Porphyromonas gingivalis genomic library and isolated the 2.9 kb EcoRV fragment which specified glycylprolyl dipeptidyl aminopeptidase (GPase). Nucleotide sequencing of this fragment identified the single 2169 bp open reading frame which coded for a 723 amino acid protein. The amino acid sequencing of the NH2-terminal domain of the native and recombinant mature enzymes suggested that the protease possessed a 16 amino acid residue signal peptide. The calculated mass of the precursor and mature proteases were 82,018 and 80,235 daltons, respectively. The homology search of this enzyme in registered protein sequences revealed that this enzyme was homologous to dipeptidyl peptidase (DPP) IV from the Flavobacterium meningosepticum and that from eukaryotic cells, including the human, mouse, and rat. Three amino acid residues, Ser-593, Asp-668, and His-700, were identified as a putative catalytic triad, a common feature of eukaryotic serine proteases. In addition, this enzyme showed a broad proteolytic spectrum toward synthetic substrates capable of splitting not only Gly-Pro-derivative but also Ala-Pro, Lys-Pro, and Phe-Pro-derivatives. Therefore, we conclude that this enzyme belongs to DPP IV rather than GPase.

Amino Acid Sequence↗

PubMed1998

Activation of the rat cyclin A promoter by ATF2 and Jun family members and its suppression by ATF4.

Cyclin A plays an essential role in the G1 to S phase transition in the cell cycle. The expression of cyclin A is restrained during G0 and G1, but steeply induced at the G1/S boundary. Analysis of the rat cyclin A promoter elements with the 5' sequential deletion derivatives of the promoter fused to the luciferase cDNA indicated that the ATF/CRE motif primarily determines the inducibility at G1/S. Gel shift analysis of the complex formed at the ATF/CRE site indicated that the complex was not formed with the G0/G1 cell extract, but maximally formed with the late-G1 cell extract. The complex was supershifted by anti-JunD antibody, and Western blot analysis of the immune complexes prepared with anti-JunD antibody revealed the presence of ATF2, suggesting heterodimerization of JunD with ATF2. The cyclin A promoter in a reporter plasmid was activated by nearly 10-fold in quiescent rat 3Y1 cells by cotransfection with the expression of plasmids encoding ATF2 and Jun family members. In contrast, cotransfection with the ATF4 expression plasmid suppressed the promoter activation mediated by ATF2 and Jun family members. The expression of Jun family members during G1 to S progression was induced biphasically in early and late G1 and the level of JunD increased markedly at the G1/S, while that of ATF family members was gradually increased along with the G1 to S progression. These results indicate that the cyclin A promoter activity is regulated, at least in part, by relative amounts of the ATF and Jun family members.

Activating Transcription Factor 2↗

PubMed1998

Gene 1, one of the dna genes of bacteriophage phi 29, represses other dna genes through binding to mRNA.

The dna genes, essential for protein priming DNA replication of bacteriophage phi 29, are transcribed as a long polycistronic mRNA. In the previous study, gene 1 product (gp1) was shown to repress the expression of the upstream dna genes for DNA polymerase and primer protein. To investigate the details of the repression by gp1, we have examined the amount and integrity of polycistronic mRNA encoding DNA polymerase and primer protein by agarose gel electrophoresis and nuclease S1 protection assay. As a result, the amount, size, and integrity of the polycistronic mRNA were not influenced by the presence of gene 1. Furthermore, the RNA binding ability of gp1 was demonstrated by in vitro system using histidine-tagged gp1. These results strongly suggested that translation of the dna genes was affected by gp1 through binding to mRNA. Other possible mechanisms of gene regulation by gp1 were discussed.

Bacillus Phages↗

PubMed1998

Nuclear factor of activated T cells (NFAT) as a molecular target for 1alpha,25-dihydroxyvitamin D3-mediated effects.

The molecular basis of the immunomodulatory properties of 1alpha,25-dihydroxyvitamin D3 (1alpha,25(OH)2D3) remains elusive. We demonstrate here that 1alpha,25(OH)2D3-mediated suppressive effects on the inducible expression of cytokine genes in human T cells may, in part, be due to diminished activity of the transcription factor NFAT. The vitamin D3 receptor (VDR) and its heterodimeric partner retinoid X receptor alpha (RXR alpha) specifically bound to the distal NFAT site in the human IL-2 promoter, and this binding was abolished by mutating unique regions in the NFAT oligonucleotide. In vitro inhibition of NFAT complex formation was noted when VDR-RXR alpha heterodimers were added to DNA binding reactions containing nuclear extracts from activated B or T cells, whereas in vitro NFkappaB complex formation was not significantly influenced. Furthermore, 1alpha,25(OH)2D3 treatment of activated T cells resulted in decreased formation of NFAT complexes detected upon incubation of nuclear extracts from these cells with 32P-labeled probe. Transient expression of both VDR and RXR alpha, but not of a single component, was capable of inhibiting expression of a NFAT-driven reporter gene in stimulated jurkat cells in a ligand-dependent manner. These results suggest that NFAT plays a crucial role in 1alpha,25(OH)2D3-mediated immunosuppressive activity.

Base Sequence↗

PubMed1998

Characterization of neuronal damage by iomazenil binding and cerebral blood flow in an ischemic rat model.

I-123-iomazenil is a SPECT probe for central benzodiazepine receptors (BZR) which may reflect intact cortical neuron density after ischemic insults. We evaluated whether neuronal damage in rats could be characterized by iomazenil as compared with cerebral blood flow (CBF). Serial changes in I-125-iomazenil for BZR and I-123-IMP for CBF were analyzed after the unilateral middle cerebral artery occlusion in rats by using an in vivo dualtracer technique. Uptake ratios of affected to contralateral regions were calculated. The iomazenil as well as IMP were decreased in all regions except for the cerebellum (remote area). Both iomazenil and IMP increased over time except in the temporal region (ischemic core). The iomazenil uptake was higher than IMP except in the ischemic core between 1 and 3-4 wk when iomazenil was lower than IMP. Iomazenil showed a moderate decrease in the proximal and middle parietal regions (peri-infarct areas) at 3-4 wk. The triphenyl-tetrazolium-chloride (TTC) stain at 1 wk demonstrated unstained tissue in the temporal region indicating tissue necrosis. With hematoxylin-eosin (HE) stain at 1 wk, widespread neuronal necrosis with occasional intact neurons were found in the proximal parietal region, and isolated necrotic neurons were represented in the distal parietal region. Iomazenil correlated well with the neuron distribution and the finding of a discrepancy between iomazenil and IMP might be useful in evaluating the neuronal damage.

Animals↗

PubMed1998

WinArrhythmia: a Windows based application for studying cardiac arrhythmias.

We have developed Windows-based software for ECG training as a tool in teaching physiology. A standard user interface allows the user to choose which arrhythmia to review. The arrhythmia is drawn in real time with sound beeps synchronized to R waves. The system also presents a brief summary or multiple choice question corresponding to the arrhythmia. A ladder diagram shows how simulate the conduction system, which consisted of 4 modules characterized by 4 parameters: automaticity, refractory period, antegrade- and retrograde-conduction time. This system has proved both useful and effective for training medical students in ECG interpretation of arrhythmias.

Arrhythmias, Cardiac↗

PubMed1998

Hepatitis G virus infection from needle-stick injuries in hospital employees.

A new RNA virus, hepatitis G virus (HGV) is known to be transmissible by blood transfusion. The aim of this study was to assess whether HGV is an occupational risk to hospital employees as a result of exposure to needle-stick injuries. Among 220 cases of needle-stick injuries, 21 employees were contaminated with HGV. Initially none of the 21 recipients were HGV positive. Fourteen of the 21 recipients were followed up and further tested for HGV RNA and serum anti-envelope (E2) specific antibody. None of the 21 recipients exposed to HGV developed liver function abnormalities, but one of the 14 recipients became positive for HGV RNA after the injury. Anti-E2 was negative in all recipients tested. These findings suggests a low clinical risk of occupational exposure to HGV in hospital employees. Nevertheless HGV is transmissible by needle-stick injury.

Acute Disease↗

PubMed1998

Microglial NO induces delayed neuronal death following acute injury in the striatum.

We have established a novel injury model in the central nervous system by a stereotaxic injection of ethanol into rat striatum to induce necrosis. With this model, we clarify a function of inducible nitric oxide synthase (iNOS) in a healing mechanism around a necrotic lesion. A semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) revealed that the iNOS mRNA arose at 6 h, peaked at 24 h, and declined to a lower level 48 h after an intrastriatal 5-microL ethanol injection. From in situ hybridization, this iNOS mRNA was expressed in the area surrounding the injury. By immunohistochemistry, mononuclear cells at this boundary area of necrosis were stained with anti-iNOS antibody on the first day after the injury. These cells turned out to be reactive microglia from the positive staining of GSA-I-B4, ED-1 and OX-42. Haematoxylin-eosin (HE) staining showed that neurons in this boundary area gradually disappear up to 5 days after the injury with an increment of microglial cells, and this area became cavernous. Nuclei of neurons in this area were stained positive by the terminal deoxynucleotidyl-transferase-mediated dUTP-biotin nick end-labelling (TUNEL) assay on the first day after the injury. These TUNEL-positive neurons gradually disappeared toward the third day, while microglial cells increased. L-Ng-nitro-arginine methylester (L-NAME), a competitive NOS inhibitor, administration diminished the elimination of neurons by microglia in this boundary area surrounding necrosis. Microglial NO may act as a neurotoxic agent to eliminate damaged neurons near the necrosis in the form of delayed neuronal death, and may reintegrate the neuronal circuits with functionally intact neurons.

Animals↗

PubMed1998

Prevalence of hepatitis G virus RNA and anti-E2 in a Japanese haemodialysis population.

BACKGROUND: Patients on maintenance haemodialysis (HD) are at greater risk of parenterally transmitted infection with not only A-E hepatitis virus but also with hepatitis G virus (HGV) that has been recovered from patients with non A-E hepatitis. The prevalence of HGV infection in HD patients, which is based on the detection of HGV RNA using reverse transcription-polymerase chain reaction techniques, differs widely between countries. Recently, a new assay has been developed that detects an antibody to the envelope protein (E2) of HGV (anti-E2) that appears to be associated with the loss of HGV RNA from the serum and which may be a useful marker for previous HGV infection. METHODS: To determine the actual prevalence of HGV infection in maintenance HD patients, we examined both HGV RNA and anti-E2 antibody in sera from 200 patients undergoing maintenance HD. RESULTS: Thirty patients (15%) tested positive for HGV RNA, and 14 (7%) tested positive for E2 antibody. Of these, two individuals tested positive for both markers. Overall, 21% of these HD patients had been exposed to HGV. A logistic regression analysis failed to show any clinical feature associated with the detection of HGV RNA. The duration of HD and the presence of HCV RNA were associated with anti-E2. Male gender and HCV RNA were risk factors for the elevation of serum ALT activities. HGV RNA sequences of the patients were not identical to each other. CONCLUSIONS: Our data indicate that HGV infection is prevalent in patients undergoing HD but that liver abnormalities are rare. The nosocomial transmission of HGV in the HD unit was not confirmed.

Aged↗

PubMed1998

New Arabidopsis cue mutants suggest a close connection between plastid- and phytochrome regulation of nuclear gene expression.

We searched for new components that are involved in the positive regulation of nuclear gene expression by light by extending a screen for Arabidopsis cue (chlorophyll a/b-binding [CAB] protein-underexpressed) mutants (H.-M. Li, K. Culligan, R.A. Dixon, J. Chory [1995] Plant Cell 7: 1599-1610). cue mutants display reduced expression of the CAB3 gene, which encodes light-harvesting chlorophyll protein, the main chloroplast antenna. The new mutants can be divided into (a) phytochrome-deficient mutants (hy1 and phyB), (b) virescent or delayed-greening mutants (cue3, cue6, and cue8), and (c) uniformly pale mutants (cue4 and cue9). For each of the mutants, the reduction in CAB expression correlates with the visible phenotype, defective chloroplast development, and reduced abundance of the light-harvesting chlorophyll protein. Levels of protochlorophyllide oxidoreductase (POR) were reduced to varying degrees in etiolated mutant seedlings. In the dark, whereas the virescent mutants displayed reduced CAB expression and the lowest levels of POR protein, the other mutants expressed CAB and accumulated POR at near wild-type levels. All of the mutants, with the exception of cue6, were compromised in their ability to derepress CAB expression in response to phytochrome activation. Based on these results, we propose that the previously postulated plastid-derived signal is closely involved in the pathway through which phytochrome regulates the expression of nuclear genes encoding plastid proteins.

Arabidopsis↗

PubMed1998

Hypercapnic acidosis may attenuate acute lung injury by inhibition of endogenous xanthine oxidase.

Relative hypoventilation, involving passively-or "permissively"-generated hypercapnic acidosis (HCA), may improve outcome by reducing ventilator-induced lung injury. However, the effects of HCA per se on pulmonary microvascular permeability (Kf,c) in noninjured or injured lungs are unknown. We investigated the effects of HCA in the isolated buffer-perfused rabbit lung, under conditions of: (1) no injury; (2) injury induced by warm ischemia-reperfusion; and (3) injury induced by addition of purine and xanthine oxidase. HCA (fraction of inspired carbon dioxide [FICO2] 12%, 25% versus 5%) had no adverse microvascular effects in uninjured lungs, and prevented (FICO2 25% versus 5%) the increase in Kf,c following warm ischemia-reperfusion. HCA (FICO2 25% versus 5%) reduced the elevation in Kf,c, capillary (Pcap), and pulmonary artery (Ppa) pressures in lung injury induced by exogenous purine/xanthine oxidase; inhibition of endogenous NO synthase in the presence of 25% FICO2 had no effect on Kf,c, but attenuated the reduction of Pcap and Ppa. HCA inhibited the in vitro generation of uric acid from addition of xanthine oxidase to purine. We conclude that in the current models, HCA is not harmful in uninjured lungs, and attenuates injury in free-radical-mediated lung injury, possibly via inhibition of endogenous xanthine oxidase.

Acidosis↗

PubMed1998

Negative regulation of the rat cdc2 promoter in G1 by the silencer element.

Expression of the cdc2 gene is induced steeply at the G1-S-phase boundary. The previous analysis of promoter elements that confer inducibility revealed the enhancer at positions -276 to -265. Enhancer activity is suppressed by the upstream sequence that seems to contain the silencer. The silencer element was analyzed by fusing several oligonucleotides covering the silencer region upstream of the enhancer in the cdc2 promoter-luciferase construct. Oligonucleotide IV, which suppressed enhancer activity, was further dissected by the introduction of base substitutions and by forming the DNA-protein complexes with quiescent rat cell extract. The silencer element, AAGTAGTAAAAATA, was finally identified at positions -374 to -360, which resembles the enhancer sequencer but contains extra internal AG residues. Silencer complexes were formed with the quiescent cell extract, whereas the amounts of the complexes decreased with the progression of the cell cycle, and nearly no complexes were formed with the late G1 cell extracts. Conversely, the enhancer complex begins to be formed after late G1. Among the three silencer complexes, the formation of the slowest-migrating complex (complex III) was inhibited by the enhancer sequence, suggesting that a common factor interacts with both the silencer and enhancer. These results suggest that the conversion of complex formation from the silencer to the enhancer site regulates the induction of cdc2 promoter activity at the G1-S-phase boundary.

Animals↗