Biomedical subjects

Y Murakami

Publications and source records attributed to Y Murakami.

At least 577 records · Page 32Linked to original sources

PubMed1994

Initiation of DNA replication by simian virus 40 T antigen is inhibited by the p107 protein.

The p107 protein is related to the Rb protein by a 60-kDa region of homology called the pocket domain that binds cellular proteins such as E2F and cyclins A and E as well as the viral oncoproteins E1A, E7, and SV40 T antigen. The p107 and Rb proteins have both been implicated as negative regulators of cell growth. We have examined the effect of the unphosphorylated pocket domain of p107 on specific stages of the T antigen-mediated replication of SV40 DNA in vitro. The pocket domain inhibited replication by preventing the assembly of T antigen at the SV40 core origin DNA containing binding site II. However, both proteins formed a ternary complex with DNA containing T antigen-binding site I. The pocket domain of p107 did not inhibit the oligomerization of T antigen in the absence of DNA, and the p107 derivative is bound to the intermediates of this reaction. In the unwinding assay, once T antigen was preassembled as hexamers at the core origin, the pocket domain bound to and stabilized the complex, resulting in an increase in the yield of unwound product. Preformed T antigen hexamers complexed with the pocket domain bind to a synthetic replication fork, and this complex supported unwinding. Consistent with this, the p107 pocket domain had no effect on the helicase activity of T antigen in an assay using a partial duplex substrate. However, a complex containing p107 and T antigen assembled at the core origin did not support SV40 DNA replication in HeLa cell crude extracts or in the monopolymerase reaction. This inhibition is due to the inability of the complex to bind to DNA polymerase alpha, which is required for the initiation of DNA synthesis. The data suggest pathways by which the pocket domain of p107 can negatively regulate T antigen-mediated replication in vitro. The binding of T antigen to p107 is discussed with respect to its role in mitigating negative cell growth control, resulting in viral mediated transformation.

Animals↗

PubMed1994

Labeling of v-Src and BCR-ABL tyrosine kinases with [14C]herbimycin A and its use in the elucidation of the kinase inactivation mechanism.

The ansamycin antibiotic, herbimycin A, selectively inactivates cytoplasmic tyrosine kinases, most likely by binding irreversibly to the reactive SH group(s) of kinases. To further investigate the mechanism of herbimycin A action, we attempted to label tyrosine kinases with [14C]herbimycin A. p60v-src and p210BCR-ABL in immune complexes were labeled with [14C]herbimycin A, demonstrating that the antibiotic binds directly to tyrosine kinases. Digestion of [14C]herbimycin A-labeled p60v-src with Staphylococcus aureus V8 protease revealed that the herbimycin A binding site is within the C-terminal 26-kDa fragment of p60v-src, which contains the tyrosine kinase domain. Herbimycin A treatment inhibited labeling of p60v-src by [14C]fluorosulfonylbenzoyl adenosine, an affinity labeling reagent of nucleotide binding sites, indicating that herbimycin A-modified p60v-src cannot interact with ATP. The results suggest that herbimycin A inactivates tyrosine kinases by binding directly to the kinase domain, thereby inhibiting access to ATP.

3T3 Cells↗

PubMed1994

Histatin as a synergistic stimulator with epidermal growth factor of rabbit chondrocyte proliferation.

Histatin 5 dose-dependently increased DNA synthesis in rabbit costal chondrocytes in culture. The level of DNA synthesis was stimulated by histatin 5 to about 4 times that of the control. The combination of histatin 5 and epidermal growth factor (EGF) increased the DNA synthesis to about 40 times that of the control while EGF alone stimulated it 15-fold, indicating synergistic stimulation by both factors. Enzyme-linked immunosorbent assay using anti-histatin 5 demonstrated that human serum contained histatin-like substances. These findings suggest that histatins play an important role in chondrocyte proliferation, presumably as a physiological modulator of the action of EGF.

Adult↗

PubMed1994

Exacerbation of established collagen-induced arthritis in mice treated with an anti-T cell receptor antibody.

OBJECTIVE: To investigate the effect of T cell depletion on established collagen-induced arthritis (CIA) in mice, using monoclonal antibodies (MAb) to T cell receptor alpha/beta (TCR alpha/beta). In addition, experiments using anti-CD3 MAb were performed for comparison. METHODS: CIA was induced in male DBA/1 mice by immunizing them twice with bovine type II collagen (CII). The arthritis score and anti-CII antibody titers were examined serially. Proportions of T cells were determined by fluorescence-activated cell sorter (FACS) analysis on spleen cells or peripheral blood cells. RESULTS: When anti-TCR alpha/beta MAb was injected on the day of CII priming, no arthritis was detected in association with depressed anti-CII antibody titers. Unexpectedly, however, when MAb was given after arthritis was established, a rapid exacerbation of arthritis was observed, which resulted in ankylosis of most joints. Anti-CII antibody titers were not affected. The addition of anti-TCR gamma/delta MAb had no effect on the augmented arthritis. T cell depletion by anti-CD3 MAb during established CIA also caused an enhancement of arthritis, which was, however, weak and only transient. FACS analysis revealed that the early improvement of arthritis after the transient augmentation seen in the mice treated with anti-CD3 MAb paralleled the early recovery of alpha/beta T cells in the periphery. CONCLUSION: The present results support the concept that alpha/beta T cells, in general, may play a regulatory role in the clinical course of murine CIA after disease onset. Therefore, caution is recommended when using intensive T cell-targeted therapy in patients with rheumatoid arthritis.

Animals↗

PubMed1994

Oral administration of idebenone induces nerve growth factor in the brain and improves learning and memory in basal forebrain-lesioned rats.

Nerve growth factor plays an important role in the survival and maintenance of cholinergic neurons in the central neuronal system. In senile dementia of the Alzheimer type, learning and memory are impaired by the loss of neurons in the magnocellular cholinergic neuronal system. It is therefore, of interest to investigate the role of nerve growth factor in this degenerative disorder. Since nerve growth factor does not cross the blood-brain barrier and is easily metabolized by peptidases when administered peripherally, it can be used for medical treatment only when directly injected into the brain. We demonstrate here that the oral administration of idebenone, a potent in vitro nerve growth factors synthesis stimulator, induced an increase in nerve growth factor protein and mRNA, and in choline acetyltransferase activity, in basal forebrain lesioned rats, but not in intact rats. Idebenone also ameliorated the behavioral deficits in habituation, water maze, and passive avoidance tasks in these animals. These results suggest that idebenone stimulated nerve growth factor synthesis in vivo and ameliorates the behavioral deficits which were accompanied with the recovery of the reduced choline acetyltransferase activity in the basal forebrain-lesioned rats.

Animals↗

PubMed1994

Gastrointestinal invasion by herpes simplex virus type 1 inoculated cutaneously into the immunosuppressed mice.

The pathogenesis of infection in mice with herpes simplex virus type 1 (HSV-1) strain 7401H was studied. Mice immunosuppressed by intraperitoneal injection of cyclophosphamide were inoculated cutaneously into the flank with the virus and developed severe zosteriform skin lesions. All of them died within 2 weeks after the infection, while most of the normal mice survived the viral infection with healing of the lesions. In the gastrointestinal tract of the immunosuppressed mice, macroscopic abnormalities were frequently observed, and infectious viruses were detected on days 7 to 9. The viruses were also detectable in the dorsal root ganglia and the spinal cord of thoracolumbar area on days 5 to 7, and in the celiac plexus on day 7. However, no viruses were detected in the blood. Immunohistological examination of the gastrointestinal tract revealed that the viral antigens were localized in Auerbach's myenteric plexus. These results suggest that HSV-1 inoculated into the flank skin invaded the gastrointestinal tract via the nervous system, which gastrointestinal involvement might possibly have caused the death of the mice.

Animals↗

PubMed1994

Valvuloplasty for common atrioventricular valve regurgitation in cyanotic heart diseases.

Valvuloplasty for common atrioventricular valvular regurgitation and bidirectional cavopulmonary shunt were successfully performed in 3 children with univentricular heart and double-outlet right ventricle. The free margins of opposite leaflets of the common atrioventricular valve were sutured together to restore coaptation of the leaflets, and Kay-Reed's or DeVega's annuloplasty was carried out. Postoperative examinations revealed significant reduction of atrioventricular valve regurgitation and improvement of general condition in all patients.

Child↗

PubMed1994

New modification of the Damus-Kaye-Stansel operation.

We report a successful modification of the Damus-Kaye-Stansel operation for transposition of the great arteries when the coronary arteries are unsuitable for transfer. The procedure includes creation of a neoaorta with end-to-end anastomosis of the proximal pulmonary artery to the distal ascending aorta and creation of an aortopulmonary window between the proximal great arteries. A valved conduit is interposed between the right ventricle and the distal pulmonary artery.

Aorta↗

PubMed1994

Characterization of Newcastle disease virus envelope glycoproteins expressed in insect cells.

Recombinant baculoviruses carrying cDNAs of hemagglutinin-neuraminidase (HN) and fusion (F) glycoprotein genes of virulent and avirulent strains of Newcastle disease virus (NDV) were constructed to examine the contribution of the individual proteins in cell fusion. F proteins of both virulent and avirulent strains expressed by the recombinant viruses were glycosylated and translocated onto the cell surfaces and only the F protein of the virulent origin was proteolytically cleaved into F1 and F2 subunits and bound intermolecularly by disulfide bonds. HN proteins of virulent and avirulent strains expressed by the recombinant viruses showed both hemadsorption and neuraminidase activities. Single infection of the recombinant baculoviruses could not induce cell fusion; however, co-infection with the recombinant viruses of the F protein of virulent strain and HN protein of both strains gave clear syncytia in insect cells. The syncytium formation was much clearer in the cells co-infected with the recombinants of F protein of virulent strain and the HN protein of avirulent strain in comparison with those co-infected with F and HN recombinant viruses of virulent origin. The cell fusion was completely blocked by monoclonal antibodies against the F protein but not by those to the HN protein.

Animals↗

PubMed1994

Age-related hearing impairment in senescence-accelerated mouse (SAM).

The auditory brainstem response and histopathology of the cochlea were investigated in an accelerated senescence-prone strain, SAM-P/1 mice and a senescence-resistant strain, SAM-R/1 mice. Each strain displayed an age-related auditory loss expressed as elevated thresholds similar to human hearing loss in that high-frequency losses occurred earlier than middle- or low-frequency losses. SAM-P/1 showed a more rapid decline of hearing with age than did SAM-R/1. Interpeak intervals I-III and I-IV were prolonged with age in both strains, especially at high frequency. The prolongation was more marked in SAM-P/1 than in SAM-R/1. The decrease in amplitude of wave I observed in both strains was greater in SAM-P/1 than in SAM-R/1. The auditory function assessed by thresholds, interpeak intervals and amplitudes of wave I in SAM-P/1 at 12 months of age corresponded roughly to that in SAM-R/1 at 20 months of age. In morphological studies, there was an age-related decrease in the cell density as well as in the size of spiral ganglion neurons in both strains, but these changes were more pronounced in SAM-P/1 than in SAM-R/1. These results reveal that age-related hearing impairment associated with morphological changes in the cochlea is manifested earlier and progresses more rapidly in SAM-P/1 than in SAM-R/1. Thus, the SAM-P/1 strain should prove useful as a model of presbycusis.

Aging↗

PubMed1994

Clinical efficacy of Tranilast on otitis media with effusion in children.

In this open randomized study, we evaluated the efficacy of Tranilast, one of the anti-inflammatory drugs, on otitis media with effusion in children. Sixty-two patients (103 ears) were divided into two groups: Group A was given Tranilast and local treatment (nasal and tubal); Group B only received local treatment (control for Group A). The overall improvement rating assessed as "moderately improved or above" for Group A was 63.6%, Group B 47.9%. There was a significant improvement in Group A as compared to Group B (p < 0.05). In subjects who suffered from otitis media with effusion for over 2 months. Group A exhibited 50.0% of efficacy while Group B only 15.4% (p < 0.05).

Acoustic Impedance Tests↗

PubMed1994

Aberrations of the tumor suppressor p53 gene and p53 protein in solar keratosis in human skin.

Aberrations of the p53 gene in 27 solar keratoses were examined by the polymerase chain reaction and single-strand conformation polymorphism and DNA sequencing analyses. In a series of Japanese patients, eight of 27 cases (30%) of solar keratosis showed structural abnormalities of the p53 gene. Six of eight aberrations of p53 gene were determined to be single nucleotide substitutions, and five of these were located at a dipyrimidine site. In solar keratosis, noticeable mutations were C to T in three cases, and one each of C to A and T to C nucleotide changes. p53 protein was detected immunohistochemically in the nuclei of six of 27 cases (22%) of solar keratosis. Nuclear staining for p53 protein was only significantly correlated with the presence of missense mutation of p53 gene (p < 0.01). Aberrations of the p53 gene in solar keratosis may be a marker to predict early cancerous lesions.

Base Sequence↗

PubMed1994

[Effect of 14-member lactone ring macrolides on anti staphylococcal activity and swarming ability of Pseudomonas aeruginosa].

The purpose of this report is to examine the effect of Macrolides (Erythromycin and Roxythromycin) on swarming ability and antistaphylococcal activity of Pseudomonas aeruginosa. The standard strain (ATCC27854) and clinically isolated P. aeruginosa were used as test strains. The influence of Macrolides on antistaphylococcal activity and swarming ability were determined by the agar plate dilution method. The antistaphylococcal activity of P. aeruginosa was not affected at the concentration of 1.56 micrograms/ml of both Erythromycin and Roxythromycin. But the antistaphylococcal activity was not observed at the concentration over 100 micrograms/ml. The swarming ability was not affected at the concentration up to 12.5 micrograms/ml. It has been proved that Macrolides reveal inhibition of virulent factors of P. aeruginosa such as protease, elastase, piocianin and so on. Furthermore our data revealed that Macrolides inhibited swarming ability of P. aeruginosa, and did not affect the antistaphylococcal activity of P. aeruginosa under 1.56 micrograms/ml concentration. Consequently, these results suggest that Macrolides have exhibited a previously unknown pharmacological effect, and may be of interest in that there may be bacterial interaction between MRSA and P. aeruginosa.

Anti-Bacterial Agents↗

PubMed1994

Porphyromonas gingivalis fimbriae induce a 68-kilodalton phosphorylated protein in macrophages.

The present study was performed to examine whether Porphyromonas gingivalis fimbriae induce specifically a protein kinase-mediated phosphorylated protein that is involved in the mechanism of signal transduction. The fimbriae induced a 68-kDa phosphorylated protein (pp68) in a dose-dependent manner in mouse peritoneal macrophages. A marked appearance of pp68 was observed 20 min after the initiation of fimbrial treatment. The fimbria-induced pp68 was inhibited dramatically by staurosporine, a potent inhibitor of protein kinase C. pp68 induction was also inhibited by H-7, a potent inhibitor of several types of protein kinase. However, the induction was not inhibited by HA-1004 and H-8, relatively high-affinity inhibitors of protein kinase A. Phorbol myristate acetate and 1-oleoyl-2-acetyl-sn-glycerol, activators of protein kinase C, were able to induce pp68 in mouse peritoneal macrophages. This protein was localized in the cytosolic fraction of fimbria-treated macrophages. pp68 also was induced in fimbria-treated human monocyte-like cells. Finally, we observed that gene expression of the fimbria-induced neutrophil chemoattractant KC was inhibited markedly by staurosporine.

Alkaloids↗

PubMed1994

Porphyromonas gingivalis fimbriae stimulate bone resorption in vitro.

Our previous study demonstrated that Porphyromonas gingivalis fimbriae induce the expression of interleukin-1, a potent bone-resorbing cytokine, in macrophages. This demonstration suggested to use the possibility that the fimbriae may stimulate bone resorption via the generation of an inflammatory cytokine(s). The present study was performed to test this suggestion. The bone-resorbing activity was evaluated by measuring the area of resorption lacunae on bone slices incubated with calvarial bone cells taken from 14-day-old mouse embryos. Fimbriae at 0.5 micrograms of protein per ml stimulated the bone-resorbing activity significantly, and the effect was dose and treatment time dependent. Since it is well known that interleukin-1 and granulocyte macrophage colony-stimulating factor induce differentiation of osteoclast lineage cells, we examined the involvement of these cytokines in fimbria-stimulated bone resorption. Fimbria-stimulated bone resorption was abolished significantly by antisera against both cytokines. We observed by Northern (RNA) blot assay that both cytokine genes were markedly expressed in the fimbria-treated calvarial bone cells. Our present data demonstrate that P. gingivalis fimbriae stimulate bone resorption in vitro.

Animals↗

PubMed1994

Use of transcriptional-enhancer elements responsive to ras, protein kinase A and protein kinase C to evaluate inhibitors of specific signal transduction pathways.

To evaluate ras-mediated signal transduction, we constructed a transient transfection assay system that measures chloramphenicol acetyl transferase activity expressed under the transcriptional-enhancer elements responsive to ras, protein kinase C, and protein kinase A in NIH3T3 cells. Characterization of the assay system with several known activators and inhibitors of signal transduction pathways proved that our system could reliably evaluate agents that affect individual pathways. Pirarubicin ((2"R)-4'-tetrahydropyranyladriamycin, THP), which has recently been found able to reverse ras-transformed cells, appeared to selectively inhibit the ras signal transduction pathway.

3T3 Cells↗

PubMed1994

Regio- and stereoselective synthesis of carbocyclic 2',3'-dideoxy-3'-fluoro nucleosides as potential antiviral agents.

The synthesis and antiviral activity of racemic carbocyclic 2',3'-dideoxy-3'-fluoro nucleosides are reported. Carbocyclic 2',3'-dideoxy-3'-fluoro nucleosides were obtained from the 3-fluoro cyclopentane derivative 4, which was prepared by two methods. The SN2-displacement of the hydroxyl group of (+/-)-(1 beta, 2 alpha, 3 beta, 4 beta)-4-acetamido-2-fluoro-3-hydroxycyclopentylmethyl acetate (1) with Ph3P-I2 followed by tin hydride reduction afforded the 3-fluoroamino alcohol derivative 3. Alternatively, the protected fluoroamino alcohol 3 was prepared by regio- and stereoselective bromo-fluorination of cis-4 beta-acetamidocyclopent-2-enemethyl acetate (5) with hydrogen fluoride-pyridine/N-bromosuccinimide followed by tin hydride reduction to remove the bromine atom. Carbocyclic 2',3'-dideoxy-3'-fluoroguanosine (14) thus obtained was moderately active against herpes simplex virus in vitro.

Adenoviridae↗

PubMed1994

Isolation of porcine reproductive and respiratory syndrome (PRRS) virus from Heko-Heko disease of pigs.

Porcine reproductive and respiratory syndrome (PRRS) virus was isolated at high frequency from the sera and lungs of pigs affected with Heko-Heko disease. In addition, a considerable amount of Mycoplasma hyorhinis (Mhr) was also isolated from the lungs. Inoculation of gnotobiote pigs with the first isolate of PRRS virus resulted in the reproduction of proliferative and interstitial pneumonia. The virus was recovered from the inoculated pigs for long periods. Superinfection with PRRS virus and Mhr appeared to produce more serious pneumonia than inoculation with PRRS virus alone. In this study, the presence of PRRS virus was confirmed in Japan, and the PRRS virus was considered as being the most important pathogen for Heko-Heko disease.

Animals↗