Biomedical subjects

T Murata

Publications and source records attributed to T Murata.

At least 19 recordsLinked to original sources

PubMed2001

Quantitative evaluation of magnetic resonance imaging of deep white matter hyperintensity in geriatric patients by multifractal analysis.

Fractal analysis has played an important role in various fields such as physics, biology and medicine. Recently, multifractal analysis based on generalized concepts of fractals has been applied to biological tissues composed of complex structures. Deep white matter hyperintensity (DWMH) on brain magnetic resonance imaging (MRI) is more often observed in patients with geriatric depression than in healthy elderly subjects, and its clinical significance is receiving attention. We applied multifractal analysis to white matter images on brain T2-weighted MRI in 62 patients with geriatric depression (50-75 years). The local fractal dimensions, alpha(max) and alpha(min), which serve as indices of complexity, and their difference, alpha(max) - alpha(min), were closely correlated with the macroscopic grading according to Fazekas classification, suggesting that multifractal analysis is useful for quantitative evaluation of DWMH on MRI.

Aged↗

PubMed2001

Neural interaction of the amygdala with the prefrontal and temporal cortices in the processing of facial expressions as revealed by fMRI.

Some involvement of the human amygdala in the processing of facial expressions has been investigated in neuroimaging studies, although the neural mechanisms underlying motivated or emotional behavior in response to facial stimuli are not yet fully understood. We investigated, using functional magnetic resonance imaging (fMRI) and healthy volunteers, how the amygdala interacts with other cortical regions while subjects are judging the sex of faces with negative, positive, or neutral emotion. The data were analyzed by a subtractive method, then, to clarify possible interaction among regions within the brain, several kinds of analysis (i.e., a correlation analysis, a psychophysiological interaction analysis and a structural equation modeling) were performed. Overall, significant activation was observed in the bilateral fusiform gyrus, medial temporal lobe, prefrontal cortex, and the right parietal lobe during the task. The results of subtraction between the conditions showed that the left amygdala, right orbitofrontal cortex, and temporal cortices were predominantly involved in the processing of the negative expressions. The right angular gyrus was involved in the processing of the positive expressions when the negative condition was subtracted from the positive condition. The correlation analysis showed that activity in the left amygdala positively correlated with activity in the left prefrontal cortex under the negative minus neutral subtraction condition. The psychophysiological interaction revealed that the neural responses in the left amygdala and the right prefrontal cortex underwent the condition-specific changes between the negative and positive face conditions. The right amygdaloid activity also had an interactive effect with activity in the right hippocampus and middle temporal gyrus. These results may suggest that the left and right amygdalae play a differential role in effective processing of facial expressions in collaboration with other cortical or subcortical regions, with the left being related with the bilateral prefrontal cortex, and the right with the right temporal lobe.

Adult↗

PubMed2001

Serial MRI and (1)H-MRS of Wernicke's encephalopathy: report of a case with remarkable cerebellar lesions on MRI.

Before and after the administration of thiamine (vitamin B(1)), MRI and proton magnetic resonance spectroscopy ((1)H-MRS) were serially performed in a patient with Wernicke's encephalopathy demonstrating remarkable cerebellar lesions on MRI. Before thiamine administration, high signal intensities were observed in the thalamus around the third ventricle and in the superior portion of the cerebellar vermis and hemisphere on fluid-attenuated inversion recovery (FLAIR) and T2-weighted MR images. After thiamine administration, the high signal intensity in the former region disappeared immediately, while that in the latter regions persisted. The low level of N-acetylaspartate (NAA)/creatine (Cr) in the thalamus before thiamine administration improved to some degree on the (1)[H]-MRS images taken after thiamine administration. In the cerebellum, a lactate peak was observed before thiamine administration, and the NAA/Cr level did not improve after thiamine administration, suggesting that irreversible necrosis occurred. It is suggested that serial MRI/(1)H-MRS observation may be helpful in determining the neuronal viability of Wernicke's encephalopathy and the prognostic implications of sequelae such as Korsakoff's syndrome and cerebellar ataxia.

Aged↗

PubMed2001

The US11 gene product of herpes simplex virus has intercellular trafficking activity.

The US11 gene product of herpes simplex virus is an abundant virion structural protein with RNA-binding regulatory activity. Its carboxyl-terminal half consists of tandem tripeptide repeats of the sequence RXP. We demonstrate that the US11 protein has intercellular trafficking activity and accumulates in the nucleolus when singly expressed in cultured cells, and that the RXP repeats are responsible for this activity. These same properties were also observed in cells expressing a fusion protein linking US11 to the green fluorescent protein. Furthermore, exogenous US11 protein was internalized by cells at 4 degrees C, which suggests that US11 protein uptake occurs primarily through an energy-independent pathway.

Amino Acid Sequence↗

PubMed2001

sFlt-1 gene-transfected fibroblasts: a wound-specific gene therapy inhibits local cancer recurrence.

Local recurrence occurs frequently at the site of injury after surgical resection. On the other hand, fibroblasts have been shown to accumulate in the injured area to heal and remodel the damaged tissues. Therefore, fibroblasts are likely to be useful as wound-specific vectors for delivery of genes to sites of surgically injury. The present study was performed to investigate wound-specific migration of exogenously administered fibroblasts and efficacy of gene therapy using genetically engineered fibroblasts in an i.p. wound recurrence model in rats. We demonstrated that fibroblasts transfected with the GFP gene accumulated specifically around the site of injury immediately after i.p. injection. Then, fibroblasts transfected with an adenovirus designated as AdFex that encoded the soluble form of Flt-1 (sFlt-1), a vascular endothelial growth factor receptor, were administered i.p. to the rats to examine inhibition of tumor growth. At day 16 after implantation, a significantly smaller tumor volume and less microvessel density in wound sites were observed in the AdFex/fibroblast-treated rats than in controls. Furthermore, this treatment also resulted in an improved survival rate. In conclusion, autologous fibroblasts show promise as a wound-specific vector for gene therapy, and administration of sFlt-1 gene-engineered fibroblasts contributed to local control of the tumor around the injured tissue.

Animals↗

PubMed2001

Roles of prostaglandin I(2) and thromboxane A(2) in cardiac ischemia-reperfusion injury: a study using mice lacking their respective receptors.

BACKGROUND: Prostaglandin (PG) I(2) and thromboxane (TX) A(2), the most common prostanoids in the cardiovascular system, are produced abundantly during cardiac ischemia/reperfusion (I/R); their roles in I/R injury, however, remain undetermined. We intended to clarify these roles of PGI(2) and TXA(2) using mice lacking the PGI(2) receptor, IP(-/-) mice, or the TXA(2) receptor, TP(-/-) mice. METHODS AND RESULTS: The left anterior descending coronary artery was occluded for 1 hour and then reperfused for 24 hours. The size of myocardial infarct in IP(-/-) mice was significantly larger than that in wild-type mice, although the size of the area at risk was similar between the 2 groups of mice. In contrast, there was no such difference between TP(-/-) and wild-type mice. To further determine whether PGI(2) and TXA(2) act directly on the cardiac tissue or indirectly through their action on blood constituents, we perfused excised heart according to the Langendorff technique. The isolated heart was then subjected to global ischemia followed by reperfusion. In IP(-/-) mice, developed tension and coronary flow rate during reperfusion were significantly lower and release of creatine kinase was significantly higher than those in wild-type mice. There were no such differences, however, between TP(-/-) and wild-type mice. CONCLUSIONS: PGI(2), which was produced endogenously during cardiac I/R, exerts a protective effect on cardiomyocytes independent of its effects on platelets and neutrophils. In contrast, TXA(2) has little role in the cardiac I/R injury.

Adenosine Triphosphate↗

PubMed2001

Reduction in asymmetrical dimethylarginine, an endogenous nitric oxide synthase inhibitor, in the cerebrospinal fluid during aging and in patients with Alzheimer's disease.

To investigate the significance of nitric oxide (NO) -mediated neuron death in aging and Alzheimer's disease (AD), the concentration of asymmetrical dimethylarginine (ADMA), an endogenous NO synthase inhibitor, in the cerebrospinal fluid was determined in neurologically normal controls and patients with AD. The ADMA concentration significantly decreased with age, whereas the arginine concentration was unaltered. In patients with AD, the ADMA concentration was significantly decreased, compared with controls of a similar age (-48%, P=0.0001), and it significantly decreased with decreasing cognitive functions (r(s)=0.58, P<0.05), whereas the arginine concentration did not change. These findings suggest that ADMA may play an important role in regulating NO synthesis in brain aging and AD.

Aged↗

PubMed2001

Chronic effect of doxorubicin on vascular endothelium assessed by organ culture study.

We have attempted to determine the chronic effects of doxorubicin, a commonly used anticancer agent, on vascular endothelium using an organ culture system. In rabbit mesenteric arteries treated with 0.3 microM doxorubicin for 7 days, rounding and concentrated nuclei and TUNEL-positive staining were observed in endothelial cells, indicating DNA damage and the induction of apoptosis. However, the endothelium-dependent relaxation induced by substance P and the expression of mRNA encoding endothelial NO synthase (eNOS) did not differ from those in control arteries. In arteries treated with a higher concentration (1 microM) of doxorubicin, apoptosis and damage to nuclei occurred in the endothelial cells at the third day of treatment, and the detachment and excoriation of endothelium from the tunica interna of the vascular wall were also observed. The impairment of endothelium-dependent relaxation was observed at the fifth day of the treatment with 1 microM doxorubicin. Additionally, apoptotic change in the smooth muscle layer was observed at this concentration of doxorubicin. Apoptotic phenomena were further confirmed by DNA fragmentation using isolated bovine aortic endothelial cells (BAECs) and A7r5 vascular smooth muscle cells, and it was revealed that BAECs are more sensitive than A7r5 to the apoptotic effect of doxorubicin. These results suggest that chronic treatment with doxorubicin at therapeutic concentrations induces apoptosis and excoriation of endothelial cells, which diminishes endothelium-dependent relaxation.

Analysis of Variance↗

PubMed2001

ATP-dependent affinity change of Na+-binding sites of V-ATPase.

V-type Na(+)-ATPase of Enterococcus hirae binds about six (6 +/- 1) Na(+) ions/enzyme molecule with a high affinity (Murata, T., Igarashi, K., Kakinuma, Y., and Yamato, I. (2000) J. Biol. Chem. 275, 13415-13419). After the addition of 5 mm ATP, the binding capacity dropped to about 2 (1.8 +/- 0.3) Na(+) ions/enzyme molecule, returning to the initial value concomitant with the decrease of ATP hydrolysis rate. These findings suggest that the affinity of four of six Na(+)-binding sites of the enzyme changes (lowers) in enzyme reaction. The ATP analogs (adenosine 5'-O-(3-thiotriphosphate) or 5'-adenylylimido-diphosphate), ADP, or aluminum fluoride that is postulated to trap ATPases at their transition state did not inhibit the Na(+) binding capacity significantly. Therefore, the affinity decrease of Na(+)-binding sites was unlikely to be due to ATP binding alone or at the transition state of ATP hydrolysis. In the presence of 5 mm ATP, the ATPase showed strong negative cooperativity (n(H) = 0.16 +/- 0.03) for Na(+) stimulation of ATPase activity. The Hill coefficient (n(H)) increased to 1 in parallel to the decrease of ATP concentration in the reaction mixture. Thus, the ATP-dependent affinity change cooperatively occurs in continuous enzyme reaction.

Adenosine Triphosphate↗

PubMed2001

Interaction of Myc-associated zinc finger protein with DCC, the product of a tumor-suppressor gene, during the neural differentiation of P19 EC cells.

Expression of the DCC (deleted in colorectal cancer) protein is strongly induced during the neural differentiation of mouse P19 embryonal carcinoma (EC) cells that occurs when these cells are treated with retinoic acid (RA). Myc-associated zinc finger protein (MAZ) is a DNA-binding protein that is widely expressed and functions in human, mouse and hamster cells as an activator, an initiator or a terminator of transcription. However, the biological functions of MAZ remain elusive. We report here that MAZ associates with the cytoplasmic domain of the DCC protein in vivo and in vitro. Yeast two-hybrid assays confirmed this association. An immunofluorescence study demonstrated that DCC protein is expressed at elevated levels in neuron-like P19 EC cells, in particular in axons, in which the MAZ protein is also expressed. We found that MAZ was translocated from the nucleus to the cytoplasm during the RA-induced terminal differentiation of P19 EC cells with resultant loss of the ability of MAZ to bind to the ME1a1 site of the c-myc promoter. Taken together, our observations imply that the DCC protein might play a critical role as a signaling molecule in the regulation of the transcriptional activity of MAZ during the neural differentiation of P19 EC cells.

Active Transport, Cell Nucleus↗

PubMed2001

A novel fibronectin binding site required for fibronectin fibril growth during matrix assembly.

Fibronectin (FN) assembly into a fibrillar extracellular matrix is a stepwise process requiring participation from multiple FN domains. Fibril formation is regulated in part by segments within the first seven type III repeats (III1-7). To define the specific function(s) of this region, recombinant FNs (recFNs) containing an overlapping set of deletions were tested for the ability to assemble into fibrils. Surprisingly, recFN lacking type III repeat III1 (FNDeltaIII1), which contains a cryptic FN binding site and has been suggested to be essential for fibril assembly, formed a matrix identical in all respects to a native FN matrix. Similarly, displacement of the cell binding domain in repeats III9-10 to a position close to the NH2-terminal assembly domain, as well as a large deletion spanning repeats III4-7, had no effect on assembly. In contrast, two deletions that included repeat III2, DeltaIII1-2 and DeltaIII2-5, caused significant reductions in fibril elongation, although binding of FN to the cell surface and initiation of assembly still proceeded. Using individual repeats in binding assays, we show that III2 but not III1 contains an FN binding site. Thus, these results pinpoint repeat III2 as an important module for FN-FN interactions during fibril growth.

Animals↗

PubMed2001

A large outbreak of foodborne infection attributed to Providencia alcalifaciens.

The enteropathogenicity of Providencia alcalifaciens, a member of the family Enterobacteriaceae, has not yet been well established. In November 1996, a large outbreak of foodborne infection occurred in Fukui, Japan. In this study, the etiology of the outbreak was investigated. No other recognized enteropathogens were detected in patient fecal samples, but P. alcalifaciens was detected in 7 of 18 samples. The isolates were found to be clonal by pulsed-field gel electrophoresis. The patients who presented with gastroenteritis had elevated levels of specific antibody against the isolated P. alcalifaciens. The isolates showed invasion of Caco-2 cells and fluid accumulation in rabbit ileal loops. This study strongly suggests that the outbreak was caused by P. alcalifaciens. This is the first report of a large outbreak of foodborne infection attributed to the organism and provides definitive evidence that P. alcalifaciens is a causative agent of gastroenteritis.

Animals↗

PubMed2001

Protein kinase Calpha plays a critical role in mannosylerythritol lipid-induced differentiation of melanoma B16 cells.

Mannosylerythritol lipid (MEL), a novel extracellular glycolipid from yeast, was found to inhibit the proliferation of mouse melanoma B16 cells in a dose-dependent manner and to induce the apoptosis of B16 cells at concentrations higher than 10 microm (Zhao, X., Wakamatsu, Y., Shibahara, M., Nomura, N., Geltinger, C., Nakahara, T., Murata, T., and Yokoyama, K. K. (1999) Cancer Res. 59, 482-486). We show here that exposure of B16 cells to MEL (5 microm) for 2 days resulted in an increase of the levels of differentiation-associated markers of melanoma cells such as melanogenesis and tyrosinase activity, which were accompanied by morphological changes. The MEL-induced differentiation of B16 cells at this concentration was closely associated with arrest of the cell cycle at G(1) phase, but no significant population of apoptotic cells was identified. Expression of protein kinase Calpha (PKCalpha) was enhanced after exposure of B16 cells to MEL for 48 h. Antisense oligodeoxynucleotides against the mouse gene for PKCalpha prevented MEL-induced melanogenesis in B16 cells. Conversely, the effects of the expression of a constitutively active form of PKCalpha mimicked the effects of MEL on B16 cells. These data suggest that MEL, a yeast-derived glycolipid, triggers the differentiation of B16 melanoma cells through a signaling pathway that involves PKCalpha.

Animals↗

PubMed2001

Total synthesis of (+/-)-scopadulin.

The first total synthesis of (+/-)-scopadulin, an aphidicolane diterpene, is described. The core structure (A/B/C/D ring system) was constructed by an initial synthesis of the B/C/D ring system by our reported methods and a subsequent A ring cyclization by intramolecular aldol condensation. A highly stereoselective cyanation of the tetracyclic enone by Et2AlCN gave a trans-fused A/B ring system with a beta-cyanide at C-4. Stereoselective construction of a quaternary carbon at C-4 was achieved by alpha-alkylation of the cyano group and conversion of the sterically hindered cyano group to a methyl group via our novel reaction for conversion of primary aliphatic amines into alcohols. Finally, the total synthesis of (+/-)-scopadulin was accomplished by a highly chemo- and stereoselective methylation at C-16 and modification of the C-4 alpha-functionality. The stereoselectivity observed in the MeTi(O-i-Pr)3-mediated methylation for the generation of a tertiary axial alcohol at C-16 is extremely high.

Antiviral Agents↗

PubMed2001

Hypoxia impairs endothelium-dependent relaxation in organ cultured pulmonary artery.

In intrapulmonary arteries cultured under hypoxic conditions (5% oxygen) for 7 days, endothelium-dependent relaxation and cGMP accumulation induced by substance P were decreased as compared to those of a normoxic control (20% oxygen). In rabbit mesenteric arteries exposed to chronic hypoxia, however, endothelial dysfunction was not observed. Furthermore, in endothelium-denuded pulmonary arteries exposed to hypoxia, neither relaxation nor cGMP accumulation due to sodium nitroprusside differed from those of the normoxic control. Hypoxia did not change the mRNA expression of endothelial NO synthase (eNOS), the protein expression of eNOS or the eNOS regulatory protein caveolin-1 as assessed by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) or whole-mount immunostaining. Morphological study revealed atrophy of endothelial cells and condensation of the eNOS protein in many cells. These results suggest that chronic hypoxia impaired NO-mediated arterial relaxation without changing either the eNOS protein expression or the NO-sensitivity of smooth muscle cells in pulmonary arteries. Changes in cell structure and organization may be involved in endothelial dysfunction.

Animals↗

PubMed2001

Synthesis and antifungal activities of novel 1,3-beta-D-glucan synthase inhibitors. Part 2.

Highly potent 1,3-beta-D-glucan synthase inhibitors, 7b, 10a, 10b and 12, have been identified by the chemical modification of the ornithine residue of a fungicidal macrocyclic lipopeptidolactone, RO-09-3655 (1), isolated from the cultured broth of Deuteromycotinia spp. These compounds showed stronger antifungal activity against systemic candidiasis as well as pulmonary aspergillosis in mice, and less hepatotoxicity as compared with 1.

Animals↗

PubMed2001

Promoter analysis for daily expression of Drosophila timeless gene.

Drosophila circadian clock gene timeless (tim) displays circadian oscillation in its mRNA level, and such oscillation is transcriptionally regulated. The promoter region up to -756 of tim is suggested to promote the circadian mRNA expression, however, the role of the sequence upstream of tim promoter region in the transcriptional regulation is still unrevealed. We novelly isolated and determined tim 5'-flanking sequence -2764 to -757, and found a putative cAMP-response element, six regions of the half site for PAR-basic leucine zipper transcription factors and six nonpalindromic E-boxes. Our in vivo reporter assay showed that 966 bp of tim promoter region, including a palindromic CACGTG E-box and a half site of PAR-basic leucine zipper transcription factors, was minimally required for its daily mRNA expression. While, the deletion of the 5'-flanking region -1970 to -967 caused a slight decrease in the reporter mRNA levels. These results indicate that the 5'-flanking sequence upstream of the promoter region have a role in the daily regulation of tim mRNA expression in Drosophila.

Animals↗

PubMed2001

The hiiragi gene encodes a poly(A) polymerase, which controls the formation of the wing margin in Drosophila melanogaster.

The hiiragi (hrg) gene plays a key role in the development of the wing margin in Drosophila melanogaster. A mutation in the hrg gene resulted in a decrease in the level of the hrg transcript and was associated with a notched wing phenotype. We report here that the hrg gene encodes a poly(A) polymerase (PAP). The bovine cDNA for PAP type II reversed the phenotype due to mutation of the hrg gene, suggesting that hrg might encode a functional homolog of PAP. A mutation that reduced the enzymatic activity of Hrg failed to reverse the phenotype of hrg mutants, suggesting that the enzymatic activity of Hrg was required to rescue the wing phenotype. The levels of expression of wingless and cut at the presumptive wing margins were reduced in the late third-instar larvae of hrg mutants. These results suggest that the product of hrg is required for the normal expression of a series of genes in this region. Our results provide the first evidence that a PAP in Drosophila plays a key role in the early development of the wing margin, acting to regulate the specific expression of a series of genes via, perhaps, control of the processing of the 3' ends of transcripts.

Amino Acid Sequence↗