Search PubMed⌕ Search

Biomedical subjects

N Fujii

Publications and source records attributed to N Fujii.

At least 55 records · Page 3Linked to original sources
PubMed2001

Alternation of inwardly rectifying background K+ channel during development of rat fetal cardiomyocytes.

The resting membrane potential of rat ventricular myocytes dramatically hyperpolarizes in the late phase of the fetal period. In order to investigate the mechanisms of this hyperpolarization, we examined the electrophysiological properties and molecular structure of the inwardly rectifying background K+ channels of rat fetal ventricular myocytes. In a patch-clamp experiment the whole-cell current of the inwardly rectifying background K+ channel increased 12-fold from between 12 and 18 days after impregnation. In the single channel recording, the large-conductance (35 pS) channels were mainly observed in the 18-day fetal ventricular myocytes. In the 12-day cells, the large-conductance channel was not observed although the low-conductance channels (11 and 16 pS) were infrequently observed. These data of single channel recordings suggested that channel proteins conducting the inwardly rectifying background K+ current were altered during the fetal development. Therefore, we compared the expression of Kir 2.1 mRNA and Kir 2.2 mRNA between 12 days and 18 days using the RT-PCR method, in order to investigate the possible molecular regulation which contributes to the electrophysiological changes. During the fetal period, the expression of Kir 2.2 mRNA increased tremendously (17 times), whereas the increase in the expression of Kir 2.1 mRNA (two times) was not so great. These results show that hyperpolarization in the late fetal period seems to be mainly due to the dramatic increase in expression of Kir 2.2 mRNA rather than expression of Kir 2.1 mRNA.

Action Potentials↗
PubMed2001

Risk factors for cytomegalovirus retinitis following bone marrow transplantation from unrelated donors in patients with severe aplastic anemia or myelodysplasia.

Two cases of cytomegalovirus (CMV) retinitis following bone marrow transplantation (BMT) from unrelated donors are reported. 1 patient had been treated for severe aplastic anemia (SAA) and the other for hypoplastic myelodysplastic syndrome (MDS). Because first line therapy with antithymocyte globulin (ATG) and cyclosporin A (CsA) had failed, BMT was performed following a conditioning regimen of ATG, cyclophosphamide, and total lymphoid irradiation. Treatment for CMV retinitis was successfully carried out with gancyclovir (systemic and intraocular injection), foscarnet, and photocoagulation (Case 1) and gancyclovir and foscarnet (Case 2). Both patients also developed Epstein-Barr virus-associated lymphoproliferative disease (EBV-LPD). We compared these 2 cases with 14 SAA patients who did not develop CMV retinitis after BMT using marrow from either HLA-identical siblings (n = 9) or from unrelated donors (n = 5). Unlike the retinitis patients, the latter 5 patients received ATG only once. The retinitis patients had significantly lower CD4+ T-cell levels in their peripheral blood than the 14 patients who did not develop CMV retinitis. We believe that repeated treatment with ATG and transplantation from unrelated donors may lead to immune dysfunction that could increase the likelihood of CMV retinitis, as well as LPD. For such BMT patients, regular ophthalmic examinations and careful testing for CMV antigenemia are recommended.

Adolescent↗
PubMed2001

Simple and low-cost tele-nuclear medicine conference system with the e-mail protocol.

PURPOSE: Because of the recent innovative growth in computer technology, digital imaging, and the Internet, we can take advantage of these facilities for education and clinical work in nuclear medicine. We developed a tele-nuclear medicine conference system with electronic mail (e-mail) on the Internet. METHODS: Twenty-one physicians (20 radiologists, 1 neurologist), 6 technologists and 2 medical students in six university hospitals (Japan 5, Canada 1), 5 local hospitals in Japan participated in this project. We used digital still cameras (330 k pixels) equipped with a floppy disk drive and 10 x optical zoom to digitize images with JPEG compression (640 x 480 matrix). The images were attached to e-mail messages (containing a brief description of each case). The mail was sent simultaneously to all members on the mailing list. Scintigram and SPECT images as well as other radiological images were sent by e-mail. Reply mails about each case were sent to all members via the mailing list. RESULTS: During a period of 6 months, 18 cases (tumor/infection: 7, bone: 6, cardiovascular: 1, neurology; 3, endocrine: 1) with 144 e-mails (average 5.6/case) were submitted to the conference. The average period of discussion was 15.6 days. The number of attached images was 1 to 9 (average, 4.2/e-mails). JPEG compression rate was 1/10 to 1/20. The quality of the images was good enough for discussion. Some cases required additional images for further discussion. CONCLUSION: Our tele-nuclear medicine conference with an electronic mailing list and digital camera was simple and low-cost. The conference system was useful for education and clinical work.

Canada↗
PubMed2001

Increase of R5 HIV-1 infection and CCR5 expression in T cells treated with high concentrations of CXCR4 antagonists and SDF-1.

The chemokine receptors CXCR4 and CCR5 are considered to be potential targets for the inhibition of HIV-1 replication. We found that the synthetic peptides T134 and T140 (see text for full names) inhibited X4 HIV-1 infection with selectivity and low toxicity because they acted as CXCR4 antagonists. However, high concentrations of T134, T140, and ALX40-4C (see text for full name) increased the expression of CCR5 and R5 HIV-1 infection, as did stromal cell-derived factor 1 (SDF-1). In contrast to CXCR4 antagonists and SDF-1, viral monocyte inflammatory protein (vMIP) II inhibited not only anti-CXCR4 monoclonal antibody (MAb) but also inhibited anti-CCR5 MAb binding to human peripheral blood mononuclear cells, and inhibited both X4 and R5 HIV-1 strains. T134, T140, ALX40-4C, and SDF-1 increased viral transcription in the treated cells. In addition, ALX40-4C and SDF-1 also increased nuclear transcription factor (NF)-kappaB. However, the mechanisms of action of T134 and T140 are different from those of clinically used anti-HIV drugs. Thus, synergistic activities were observed in the concomitant treatment with T134 and reverse transcriptase inhibitors or protease inhibitors. Our findings, presented here, are noteworthy in regard to the potential clinical use of these agents as drugs for the treatment of AIDS.

Animals↗
PubMed2001

Therapeutic effect of anti-TNF-alpha antibody and levofloxacin (LVFX) in a mouse model of enterohemorrhagic Escherichia coli O157 infection.

The ability of an anti-TNF-alpha antibody to confer protection against enterohaemorrhagic Escherichia coli (EHEC) O157 was investigated in germfree IQI mice. The use of an antibiotic levofloxacin (LVFX) alone or with the antibody was also studied. Protection included an increase in survival rate. Treatment with the anti-TNF-alpha antibody inhibited the histological signs associated with EHEC infection but did not prevent the colonization of EHEC or production of Shiga toxin (Stx). No clinical signs were observed and EHEC was completely eliminated in the mouse model receiving both anti-TNF-alpha antibody and LVFX. Anti-TNF-alpha antibody suppressed inflammatory cytokine response in the mouse kidney and brain by EHEC infection.

Animals↗
PubMed2001

Genetics of Epstein-Barr virus infection.

Epstein-Barr (EBV) virus is a member of the human herpesvirus family. EBV is the etiologic agent of acute infectious mononucleosis and is closely associated with the genesis of Burkitt's lymphoma and undifferentiated nasopharyngeal carcinoma. EBV is also implicated in a variety of other diseases, such as X-linked lymphoproliferative syndrome, T-cell non-Hodgkin's lymphoma, Hodgkin's disease, and NK-cell granular lymphoproliferative disorder. Recently, lymphoepithelial carcinoma of the stomach, gastric carcinoma, pyothorax-associated lymphoma, and smooth muscle tumors were also recognized as EBV-associated diseases. It is therefore important to review the genetics and immunological response of EBV infection. In this review we summarize the genetics of EBV, immunological responses and clinical findings of EBV-associated diseases, which would help us to understand the pathophysiology of EBV-associated disease and develop specific treatments.

Epstein-Barr Virus Infections↗
PubMed2001

Synthesis and evaluation of bifunctional anti-HIV agents based on specific CXCR4 antagonists-AZT conjugation.

We have previously found that T140, a 14-amino acid residue peptide, inhibits infection of target cells by T cell-line-tropic strains of HIV-1 (X4-HIV-1) through its specific binding to a chemokine receptor, CXCR4. Here, we report synthesis and evaluation of bifunctional anti-HIV compounds, which are composed of T140 analogues and a reverse transcriptase inhibitor, 3'-azido-3'-deoxythymidine (AZT). Novel conjugated analogues have been proved to have the ability for controlled release of AZT in neutral aqueous media as well as mouse and feline sera, and high selectivity indexes (SIs, 50% cytotoxic concentration/50% effective concentration) caused by a synergistic effect of two different regenerating agents. Thus, these bifunctional compounds have several potential advantages. T140 analogues can possibly work as a carrier of AZT targeting T cells due to their specific affinity for CXCR4 on T cells. A synergistic effect by two types of regenerating agents may enable drug dosage to be reduced, and thus it may effectively suppress toxic side effects and the appearance of drug-resistant virus.

Animals↗
PubMed2001

The earliest stages of B cell development require a chemokine stromal cell-derived factor/pre-B cell growth-stimulating factor.

Environmental factors essential for the first stages of B lymphopoiesis remain elusive. Here, we report that immediately after commitment to B lineage, precursors become dependent on a chemokine SDF-1 and its receptor CXCR4 using mutant and radiation chimeric mice. In bone marrow, generation of the earliest identifiable B cell precursor populations requires CXCR4. In fetal liver, we identified Lin(-)CD19(-)c-kit(+)IL-7Ralpha(+)AA4.1(+), the earliest unipotent B cell precursor population, and found that its development was severely affected in SDF-1(-/-) embryos but not in IL-7(-/-) embryos. Lin(-) T cell progenitors appeared normal in SDF-1(-/-) embryos. Moreover, SDF-1 exhibited specific biologic activities on the earliest B cell precursors. SDF-1 provides the first example of a cytokine responsible for the earliest B lineage stages.

Animals↗
PubMed2001

Hepatic graft-versus-host disease presenting as an acute hepatitis after allogeneic peripheral blood stem cell transplantation.

Hepatic graft-versus-host disease (GVHD) generally presents as cholestatic jaundice, and increased serum alkaline phosphatase (ALP) is followed by hyperbilirubinemia and clinical jaundice. Currently accepted standards for evaluating the clinical severity of GVHD are based not on serum aminotransferase levels but on the serum bilirubin level. We describe a 17-year-old Japanese female who had increased aminotransferases without cholestasis on day 23 after allogeneic peripheral blood stem cell transplantation (allo-PBSCT). Liver biopsy revealed lymphocytic infiltration of the portal tracts and pericentral necrosis of the lobuli. The limiting plates were not clearly defined due to cellular infiltrates. There was periductal lymphocytic infiltration and vacuolization of the biliary epithelial cells with exocytosis, compatible with GVHD of cholangiohepatitic type. These findings indicate that acute hepatic GVHD may present as acute hepatitis and this should be included in the differential diagnosis for patients with increased aminotransferases after allogeneic stem cell transplantation.

Acute Disease↗
PubMed2001

Ethanol production from starch by immobilized Aspergillus awamori and Saccharomyces pastorianus using cellulose carriers.

A simultaneous saccharification and fermentation (SSF) process was investigated to produce ethanol using two kinds of cellulose carriers that were respectively suitable for immobilization of Aspergillus awamori and Saccharomyces pastorianus. The maximum ethanol concentration attained by the batch operation was 25.5 g l(-1). Under suitable conditions, both cellulose carriers with immobilized cells could be reused efficiently for three cycles. The total amount of ethanol production was 66.0 g (per 1 l working volume) after the repeated operation. Ethanol productivity mainly depends on a saccharification process. There is a limit in durability in the repeated batch operation, and it is important to maintain high activity of the fungus in order to produce ethanol efficiently.

Aspergillus↗
PubMed2001

The M locus and ethylene-controlled sex determination in andromonoecious cucumber plants.

Sex determination in cucumber (Cucumis sativus L.) plants is genetically controlled by the F and M loci. These loci interact to produce three different sexual phenotypes: gynoecious (M-F-), monoecious (M-ff), and andromonoecious (mmff). Gynoecious cucumber plants produce more ethylene than do monoecious plants. We found that the levels of ethylene production and the accumulation of CS-ACS2 mRNA in andromonoecious cucumber plants did not differ from those in monoecious plants and were lower than the levels measured in gynoecious plants. Ethylene inhibited stamen development in gynoecious cucumbers but not in andromonoecious ones. Furthermore, ethylene caused substantial increases in the accumulation of CS-ETR2, CS-ERS, and CS-ACS2 mRNA in monoecious and gynoecious cucumber plants, but not in andromonoecious one. In addition, the inhibitory effect of ethylene on hypocotyl elongation in andromonoecious cucumber plants was less than that in monoecious and gynoecious plants. These results suggest that ethylene responses in andromonoecious cucumber plants are reduced from those in monoecious and gynoecious plants. This is the first evidence that ethylene signals may influence the product of the M locus and thus inhibit stamen development in cucumber. The andromonoecious line provides novel material for studying the function of the M locus during sex determination in flowering cucumbers.

Arabidopsis Proteins↗
PubMed2001

Modulation of ventricular repolarization and R-R interval is altered in patients with globally impaired cardiac 123I-MIBG uptake.

BACKGROUND: Cardiac (123)I-metaiodobenzylguanidine (MIBG) imaging is widely used to assess cardiac sympathetic neuronal function. However, physiologic significance of impaired cardiac MIBG uptake is not fully elucidated. The purpose of the present study was to determine influences of abnormal cardiac sympathetic neuronal function on heart rate variability (HRV) and ventricular repolarization process. METHODS: Twenty-nine patients with prior myocardial infarction were divided into two groups by a heart-to-mediastinum ratio (H/M) of MIBG scintigraphy. Ten patients with globally decreased MIBG uptake (group I: H/M < 1.5), 19 patients with partially decreased MIBG uptake (group II: H/M >or= 1.5), and 17 control subjects with normal MIBG uptake (group III) were studied. Holter recording and a standard 12-lead electrocardiography were used for evaluation of HRV, QT-RR relation, and QT dispersion. RESULTS: Low, high, and total frequency components decreased in groups I and II, as compared to that of group III. The reduction of these frequency domain measures was more severe in group I than in group II, but the differences did not reach statistical significance. Circadian variation of frequency domain measures disappeared in group I. The slope of QT-RR relation was significantly greater in group I than in groups II and III. QT dispersion was also greater in group I (64 +/- 25 msec) than in group II (43 +/- 19 msec) and group III (28 +/- 9 msec). CONCLUSION: These results suggest that patients with sympathetic neuronal dysfunction inferred from globally impaired cardiac MIBG uptake have an altered modulation of ventricular repolarization process as well as decreased HRV.

3-Iodobenzylguanidine↗
PubMed2001

Unique monoclonal antibody recognizing the third extracellular loop of CXCR4 induces lymphocyte agglutination and enhances human immunodeficiency virus type 1-mediated syncytium formation and productive infection.

To increase insight into the structural basis of CXCR4 utilization in human immunodeficiency virus type 1 (HIV-1) infection, a new generation of three monoclonal antibodies (MAbs) was developed in WKA rats. The A80 MAb, which binds an epitope in the third extracellular loop (ECL3) of CXCR4, has unique biologic properties that provide novel insights into CXCR4 function. This agent enhanced syncytium formation in activated human peripheral blood mononuclear cells (PBMC) infected with X4 or R5 and CEM cells infected with X4 HIV-1 strains. Exposure to A80 increased the productive infection of activated CD4(+) T cells and CEM cells with R5 and X4 viruses, respectively. This antibody uniquely induced agglutination of PBMC and CEM cells but did not activate calcium mobilization. Agglutination induced by A80 was inhibited by stromal cell-derived factor 1, T22, and phorbol 12-myristate 13-acetate but was not significantly altered by pretreatment of cells with pertussis toxin, wortmannin, or MAbs to LFA-1, ICAM-1, ICAM-2, and ICAM-3. The binding of the A145 and A120 MAbs was mapped to the N-terminal extracellular domain and a conformational epitope involving ECL1 and ECL2, respectively. Both of these MAbs inhibited HIV-1 infection and lacked the novel properties of A80. These results suggest a new role for CXCR4 in homologous lymphocyte adhesion that is ligand independent and in HIV-1 infection.

Amino Acid Sequence↗
PubMed2001

AMP-activated protein kinase activity and glucose uptake in rat skeletal muscle.

The AMP-activated protein kinase (AMPK) has been hypothesized to mediate contraction and 5-aminoimidazole-4-carboxamide 1-beta-D-ribonucleoside (AICAR)-induced increases in glucose uptake in skeletal muscle. The purpose of the current study was to determine whether treadmill exercise and isolated muscle contractions in rat skeletal muscle increase the activity of the AMPK alpha 1 and AMPK alpha 2 catalytic subunits in a dose-dependent manner and to evaluate the effects of the putative AMPK inhibitors adenine 9-beta-D-arabinofuranoside (ara-A), 8-bromo-AMP, and iodotubercidin on AMPK activity and 3-O-methyl-D-glucose (3-MG) uptake. There were dose-dependent increases in AMPK alpha 2 activity and 3-MG uptake in rat epitrochlearis muscles with treadmill running exercise but no effect of exercise on AMPK alpha1 activity. Tetanic contractions of isolated epitrochlearis muscles in vitro significantly increased the activity of both AMPK isoforms in a dose-dependent manner and at a similar rate compared with increases in 3-MG uptake. In isolated muscles, the putative AMPK inhibitors ara-A, 8-bromo-AMP, and iodotubercidin fully inhibited AICAR-stimulated AMPK alpha 2 activity and 3-MG uptake but had little effect on AMPK alpha 1 activity. In contrast, these compounds had absent or minimal effects on contraction-stimulated AMPK alpha 1 and -alpha 2 activity and 3-MG uptake. Although the AMPK alpha 1 and -alpha 2 isoforms are activated during tetanic muscle contractions in vitro, in fast-glycolytic fibers, the activation of AMPK alpha 2-containing complexes may be more important in regulating exercise-mediated skeletal muscle metabolism in vivo. Development of new compounds will be required to study contraction regulation of AMPK by pharmacological inhibition.

3-O-Methylglucose↗
PubMed2001

Physiological and pathological cardiac hypertrophy induce different molecular phenotypes in the rat.

Pressure overload, such as hypertension, to the heart causes pathological cardiac hypertrophy, whereas chronic exercise causes physiological cardiac hypertrophy, which is defined as athletic heart. There are differences in cardiac properties between these two types of hypertrophy. We investigated whether mRNA expression of various cardiovascular regulating factors differs in rat hearts that are physiologically and pathologically hypertrophied, because we hypothesized that these two types of cardiac hypertrophy induce different molecular phenotypes. We used the spontaneously hypertensive rat (SHR group; 19 wk old) as a model of pathological hypertrophy and swim-trained rats (trained group; 19 wk old, swim training for 15 wk) as a model of physiological hypertrophy. We also used sedentary Wistar-Kyoto rats as the control group (19 wk old). Left ventricular mass index for body weight was significantly higher in SHR and trained groups than in the control group. Expression of brain natriuretic peptide, angiotensin-converting enzyme, and endothelin-1 mRNA in the heart was significantly higher in the SHR group than in control and trained groups. Expression of adrenomedullin mRNA in the heart was significantly lower in the trained group than in control and SHR groups. Expression of beta(1)-adrenergic receptor mRNA in the heart was significantly higher in SHR and trained groups than in the control group. Expression of beta(1)-adrenergic receptor kinase mRNA, which inhibits beta(1)-adrenergic receptor activity, in the heart was markedly higher in the SHR group than in control and trained groups. We demonstrated for the first time that the manner of mRNA expression of various cardiovascular regulating factors in the heart differs between physiological and pathological cardiac hypertrophy.

Actins↗
PubMed2001

Role of AMP-activated protein kinase in mechanism of metformin action.

Metformin is a widely used drug for treatment of type 2 diabetes with no defined cellular mechanism of action. Its glucose-lowering effect results from decreased hepatic glucose production and increased glucose utilization. Metformin's beneficial effects on circulating lipids have been linked to reduced fatty liver. AMP-activated protein kinase (AMPK) is a major cellular regulator of lipid and glucose metabolism. Here we report that metformin activates AMPK in hepatocytes; as a result, acetyl-CoA carboxylase (ACC) activity is reduced, fatty acid oxidation is induced, and expression of lipogenic enzymes is suppressed. Activation of AMPK by metformin or an adenosine analogue suppresses expression of SREBP-1, a key lipogenic transcription factor. In metformin-treated rats, hepatic expression of SREBP-1 (and other lipogenic) mRNAs and protein is reduced; activity of the AMPK target, ACC, is also reduced. Using a novel AMPK inhibitor, we find that AMPK activation is required for metformin's inhibitory effect on glucose production by hepatocytes. In isolated rat skeletal muscles, metformin stimulates glucose uptake coincident with AMPK activation. Activation of AMPK provides a unified explanation for the pleiotropic beneficial effects of this drug; these results also suggest that alternative means of modulating AMPK should be useful for the treatment of metabolic disorders.

AMP-Activated Protein Kinases↗
PubMed2001

Correlation between the loss of the chaperone-like activity and the oxidation, isomerization and racemization of gamma-irradiated alpha-crystallin.

Alpha-crystallin possesses a molecular chaperone-like activity that prevents proteins from aggregating; however, the mechanism of this activity is not well known. Here we have taken gamma-irradiated alpha-crystallin and studied the relationship between the decrease in chaperone-like activity and the modifications such as oxidation, isomerization and racemization of amino acids in this molecule. We found that the chaperone-like activity of alpha-crystallin decreased with increasing gamma irradiation. After 4000 Gy gamma irradiation the activity of alpha-crystallin was reduced to 40% of the level of nonirradiated, native alpha-crystallin. The circular dichroism spectrum showed that the secondary structure of the irradiated alpha-crystallin had not changed. However, its tertiary structure appeared to change following more than 1000 Gy irradiation. Sodium dodecyl sulfatepolyacrylamide gel electrophoresis also indicated that cross-linking of alpha-crystallin increased with increasing radiation doses. Irradiated and nonirradiated alpha-crystallin was subjected to trypsin digestion and peptide analysis by reverse-phase high-performance liquid chromatography and mass and sequence analysis. Depending on the radiation dose, Met-1 of alpha A-crystallin was oxidized to methionine sulfoxide. In addition, Asp-151 of alpha A-crystallin was isomerized to the beta-Asp form after irradiation, and racemization of Asp-151 decreased. Thus, the loss of the chaperone-like activity of alpha-crystallin is related to changes in its isomerization, oxidation and racemization.

Animals↗