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Biomedical subjects

Y Tamura

Publications and source records attributed to Y Tamura.

At least 109 records · Page 6Linked to original sources
PubMed2000

Histomorphometric evaluation of the recovering effect of human parathyroid hormone (1-34) on bone structure and turnover in streptozotocin-induced diabetic rats.

The purpose of this study was to determine whether human parathyroid hormone (h-PTH) enhances trabecular bone mass and connectivities that were reduced by streptozotocin (STZ)-induced diabetes in rats. Seven-month-old female Wistar rats were injected with STZ or its vehicle intraperitoneally. All vehicle-injected normal controls were sacrificed 0, 4, 6, 8, 12, 14, and 16 weeks after injection, and one-third of the STZ-injected rats were sacrificed as the baseline controls 4, 6, and 8 weeks after the injection. Eight-week h-PTH (6. 0 microg/kg, 6 times a week) or its vehicle treatment by subcutaneous injection for residual diabetic rats was started 4, 6, or 8 weeks after the STZ injection. The rats' proximal right tibiae were processed for undecalcified Villanueva bone staining sections for bone histomorphometry. Furthermore, changes in trabecular connectivities were determined by node-strut analysis. The decreased cancellous bone volume (BV/TV) and turnover in diabetic rats were recovered in all PTH-treated groups. In node-strut analysis, the node-related parameters (N.Nd/TV, NdNd/TV) were significantly increased by PTH when it was administered 4 weeks after STZ injection but were not increased when administration was started after 6 weeks. The results indicated that PTH enhanced bone turnover and bone mass but not trabecular connectivity in the late stage of diabetes in rats. Early treatment of osteoporosis is important in preventing fractures caused by decreased bone strength resulting from decreased trabecular connectivity.

Analysis of Variance↗
PubMed2000

Role of circulating vascular endothelial growth factor and hepatocyte growth factor in patients with coronary artery disease.

Vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) are thought to stimulate endothelial cell proliferation and induce angiogenesis in vivo. However. the precise mechanism responsible for VEGF and HGF release in patients with coronary artery disease is still unknown. We studied serum concentrations of VEGF and HGF in 20 patients with acute myocardial infarction (AMI), 20 patients with stable angina pectoris (AP) who had reversible perfusion defects on stress myocardial scintigraphy, and 16 patients with old myocardial infarction (OMI) who had no reversible defects on stress myocardial scintigraphy. The control group consisted of 20 patients with atypical chest pain who had angiographically normal coronary arteries. Serum VEGF and HGF concentrations were measured by enzyme-linked immunosorbent assay. Both the serum VEGF and HGF concentrations in the early stage of myocardial infarction in the patients with AMI were higher than those in the patients with AP and with OMI, and control patients. The VEGF concentration in the patients with AP was higher than in the patients with OMI, whereas the HGF concentration did not differ in the patients with AP and OMI. The VEGF concentration in AMI patients who had had preinfarction angina on admission was higher than that of patients who had had no preinfarction angina, whereas the HGF concentration did not differ between the two groups of patients. These results suggest that the serum VEGF concentration may reflect myocardial ischemia to a greater degree than the serum HGF concentration.

Aged↗
PubMed2000

Human CD8 and CD4 T cell epitopes of epithelial cancer antigens.

Recent human tumor immunology research has identified several genes coding immunogenic peptides recognized by CD8 cytotoxic T lymphocytes (CTLs) in melanoma tumors. Very recently, CD4 T cell antigenic epitopes were also determined in certain melanoma tumors. The use of these peptides in conjunction with human immunotherapy could prove to be of great benefit. However, such peptides in clinically common tumors of epithelial cell origin, such as of the stomach, colon, lung, etc., have not yet been determined extensively. We describe for the first time an HLA-A31 (A*31012)-restricted natural antigenic peptide recognized by the CD8 CTL TcHST-2 of gastric signet ring cell carcinoma cell line HST-2. We also identified the HLA-DRB1*08032-restricted peptide recognized by the CD4 T cell line TcOSC-20 of squamous cell carcinoma OSC-20 derived from the oral cavity. The antigenic peptide of HST-2, designated F4.2, is composed of 10 amino acid residues with two anchor motif residues necessary for binding to HLA-A31 molecules. The synthetic F4.2 peptide enhanced the reactivity of TcHST-2 against HST-2 cells. Furthermore, introduction of an expression minigene coding F4.2 peptide to HLA-A31(+) cells conferred cytotoxic susceptibility to TcHST-2 on the cells. Some stomach cancer lines into which the HLA-A31 gene had been introduced, such as MKN28-A31-2, were lysed by TcHST-2, suggesting the presence of F4.2 peptide in at least some HLA-A31(+) stomach cancers. Furthermore, F4.2 peptide induced an F4.2 peptide-specific CTL response in at least 30-40% of HLA-A31(+) peripheral blood lymphocytes from gastric cancer patients, suggesting that F4.2 peptide could be used as a cancer vaccine for gastric tumors. The natural antigenic peptide of OSC-20 was also determined using acid extraction and biochemical separation and by mass spectrometry. Consequently, OSC-20 peptide was designated as the 6-1-5 peptide, an HLA-DRB1*08032-restricted 16-mer peptide with two possible anchor motifs. It has an amino acid sequence identical to that of human alpha-enolase, suggesting that it was derived from the processed parental alpha-enolase protein. We are presently attempting to determine the genes that code tumor rejection antigens recognized by HLA-A24- and A26-restricted T cells, including those of pulmonary and pancreatic carcinomas. The search for these antigenic peptides may lead to the identification of immunogenic peptide antigens that would be suitable for clinical use in commonly occurring epithelial cancers.

Amino Acid Sequence↗
PubMed2000

Dumb-bell-type teratoma in the lumbar spine.

We report a case of a lumbar teratoma in a 50-year-old woman. The teratoma showed a dumb-bell-type expansion at the level of the left L3/4 foramen with massive erosion of the L3 vertebral body. MRI revealed inhomogeneous signal changes in the tumor, which were histologically compatible with a mixture of bone, muscle, fat, and cyst containing sebaceous material. Complete resection of the tumor and spinal arthrodesis with pedicle screw fixation was necessary to obtain stability of the affected spinal segment.

Bone Screws↗
PubMed2000

Quantitative assessment of regional myocardial blood flow using oxygen-15-labelled water and positron emission tomography: a multicentre evaluation in Japan.

Recently, a method has been proposed for the quantitative measurement of regional myocardial blood flow (MBF) using oxygen-15-labelled water and positron emission tomography (PET). A multicentre project was organized with the intention of evaluating the accuracy of this method, particularly as a multicentre clinical investigative tool. Each of seven institutions performed PET studies on more than five normal volunteers following a specified protocol. The PET study included a transmission scan, a 15O-carbon monoxide static scan and a 15O-water dynamic scan, thereby yielding MBF values which should have been independent of the spatial resolution of the PET scanner employed. Fifty-three subjects (aged 20-63 years, mean+/-SD 36+/-12 years) were studied at rest, and 31 of these subjects were also studied after dipyridamole in five institutions. Inter-institution consistency and intra-subject variation in MBF values were then evaluated. MBF averaged for all subjects was 0.93+/-0.34 ml min(-1) g(-1) at rest and 3.40+/-1.73 ml min(-1) g(-1) after the administration of dipyridamole, and the flow reserve (defined as the ratio of the two MBF values) was 3.82+/-2.12; these values are consistent with previous reports. Resting MBF values were significantly correlated with the heart rate-blood pressure product (RPP) (y=0.31+6.56E-5x, P<0.010), and RPP was in resting MBF observed in all institutions was well explained by the age-dependent RPP. No significant difference was observed in resting MBF among the institutions. Except in one institution, no significant difference was seen in dipyridamole MBF or myocardial flow reserve. No significant difference was found among the myocardial segments. Regional variation was reasonably small in five institutions, but was not acceptable in two institutions, which was attributed to the scanner performance. These observations suggest that the 15O-water PET technique is useful for a multicentre clinical study if the PET scanner can provide time-activity data with good count statistics.

Coronary Circulation↗
PubMed2000

Involvement of NMDA-receptor in kainate-induced neurotoxicity in cultured fetal retinal neurons.

BACKGROUND: Both in vivo and in vitro studies suggest that excess stimulation of non-NMDA receptors can result in massive neuronal death in the retina. In particular, murine amacrine neurons have been known to show marked susceptibility to the toxic effects of kainate. PURPOSE: This study was designed to examine and characterize the role of N-methyl-D-aspartate (NMDA) receptor vs non-NMDA receptor in glutamate-induced neurotoxicity in the retina. METHODS: Primary cultures obtained from fetal rat retina (gestation day 16-19) were used for the experiment. The neurotoxicity was assessed quantitatively using the trypan blue exclusion method. Electrophysiological studies using patch-clamp techniques were performed to record whole-cell currents evoked by these excitatory amino acids. RESULTS: Removal of extracellular Ca2+ from the medium or application of MK-801 reduced the extent of cell death induced by the brief exposure to glutamate, NMDA, and kainate. By contrast, cell death induced by a 60-min exposure to kainate was not affected by MK-801. The electrophysiological study demonstrated that MK-801 abolished the whole-cell currents evoked by NMDA but had no effect on those induced by kainate or AMPA. CONCLUSION: These findings demonstrate that brief exposure to kainate induces cell death by way of activating NMDA receptors in cultured fetal retinal neurons and that NMDA receptors are the predominant route of fetal retinal neurotoxicity induced by brief glutamate exposure.

Animals↗
PubMed2000

Jejunal limb obstruction caused by a cholesterol stone 15 years after a total gastrectomy and 20 years after a cholecystectomy: report of a case.

We present herein the rare case of a 74-year-old woman found to have jejunal limb obstruction caused by a cholesterol stone 15 years after a total gastrectomy with Roux-en-Y anastomosis, and 20 years after a cholecystectomy. The patient complained of repeated episodes of upper abdominal distress on three separate occasions over a period of 20 months, and jejunal limb obstruction was diagnosed by abdominal computed tomography scanning and (99m)Tc scintigraphy. Surgery revealed a stone incarcerated in the jejunal limb, where the anastomosis had become slightly stenotic. The removed stone was 3.5 cm in diameter and was subsequently demonstrated to be a cholesterol stone by chemical analysis. This report is thought to be the first to describe jejunal limb obstruction caused by a gallstone incarcerated in the jejunal limb after a total gastrectomy in a patient with a history of cholecystectomy.

Acute Disease↗
PubMed2000

Insufficiency fractures of the distal tibiae.

We describe two patients with uncommon types of insufficiency fractures that occurred at the distal tibiae. In case 1, a 71-year-old man with secondary osteoporosis due to hypogonadism fracture of his left distal tibia was overlooked because initial radiographs had seemed normal. However, bone scintigram obtained 2 months prior to the onset of fracture had already demonstrated abnormally high uptake at the site. In case 2, a 62-year-old woman with postmenopausal osteoporosis sustained an insufficiency fracture of the left distal tibia. Good clinical results were obtained with nonsurgical treatment. Based on the clinical course of case 1, we believe that bone scintigrams may be useful not only for the early diagnosis of insufficiency fracture but also for predicting such fractures.

Aged↗
PubMed2000

Gene expression and immunolocalization of amelogenin in enamel hypoplasia induced by successive injections of bisphosphonate in rat incisors.

Successive injections of 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) in rats induce enamel hypoplasia. To elucidate the pathogenesis of this hypoplasia, male Wistar rats were daily injected with HEBP or physiological saline for 7 days. After the last injection, they were killed under anaesthesia and their maxillary incisors were examined using an in situ hybridization technique and immunohistochemical staining to detect the gene expression and localization of amelogenin protein, respectively. In the HEBP-injected rats, several islets of partially mineralized enamel were present along crown-analogous surface of the incisor in the secretory stage of amelogenesis and enamel-free zones existed between these islets. In situ hybridization demonstrated amelogenin gene expression over the ameloblasts facing the islets of the matrix enamel as well as over those of the enamel-free zones. Immunohistochemical studies using rabbit antiamelogenin antibody revealed positive reaction both in the enamel matrix of the control group and in the islets of enamel matrix of the HEBP-injected group. Some small granules immunoreactive to amelogenin antibody were found in the distal portions of the ameloblasts in the HEBP-injected rats. The results indicate that HEBP does not alter amelogenin gene expression over ameloblasts, or the protein's existence in enamel matrix. There appeared to be some accumulation of amelogenin in the HEBP-treated ameloblasts. It is therefore suggested that the enamel hypoplasia in this experiment may not be due to a disturbance in amelogenin synthesis but to a disturbance in a later process, presumably of protein secretion.

Amelogenin↗
PubMed2000

Molecular dynamics generation of nonarbitrary membrane models reveals lipid orientational correlations.

This report addresses the following problems associated with the generation of computer models of phospholipid bilayer membranes using molecular dynamics simulations: arbitrary initial structures and short equilibration periods, an Ewald-induced strong coupling of phospholipids, uncertainty regarding which value should be used for surface tension to alleviate the problem of the small size of the membrane, and simultaneous realization of both order parameters and the surface area. We generated a computer model of the liquid-crystalline L-alpha-dimyristoylphosphatidylcholine (DMPC) bilayer, starting from a configuration based on a crystal structure (rather than from an arbitrary structure). To break the crystalline structure, a 20-ps high-temperature pulse of 510 K (but not 450 or 480 K) was effective. The system finally obtained is an all-atom model, with Ewald summation to evaluate Coulombic interactions and a constant surface tension of 35 dynes/cm/water-membrane interface, equilibrated for 12 ns (over 50 ns total calculation time), which reproduces all of the experimentally observed parameters examined in this work. Furthermore, this model shows the presence of significant orientational correlations between neighboring alkyl chains and between shoulder vectors (which show the orientations of the lipids about their long axes) of neighboring DMPCs.

Computer Simulation↗
PubMed2000

A 38 kDa allylic alcohol dehydrogenase from the cultured cells of Nicotiana tabacum.

An NADP+-dependent alcohol dehydrogenase (allyl-ADH) was isolated from the cultured cells of Nicotiana tabacum. The allyl-ADH was found to be efficient for the dehydrogenation of secondary allylic alcohols rather than saturated secondary alcohols and it was specific for the S-stereoisomer of the alcohols. The enzyme catalyzed the reversible reaction whereby the carbonyl group of enones is reduced to the corresponding allylic alcohol or vice versa. Two possible primary structures of the allyl-ADH were deduced by the sequence analyses of full-length cDNAs (allyl-ADH1 and ally-ADH2), which were cloned by the PCR method. These analyses indicated that the allyl-ADHs are composed of 343 amino acids having the molecular weights 38083 and 37994, respectively, and they showed approximately 70% homology to the NADP+-dependent oxidoreductases belonging to a plant zeta-crystallin family.

Alcohol Dehydrogenase↗
PubMed2000

Antiyeast steroidal saponins from Yucca schidigera (Mohave yucca), a new anti-food-deteriorating agent.

A saponin fraction from the stems of Yucca schidigera (Mohave yucca) exhibited potent growth-inhibitory activities against certain food-deteriorating yeasts, film-forming yeasts, and dermatophytic yeasts and fungi. From this fraction, a number of new anti-yeast monodesmosidic spirostanol saponins, named schidigera-saponins A1 (1), A2 (2), A3 (3), B1 (4), C1 (5),C2 (6); 25(R and S) schidigera-saponins D1 (7), D2 (8), E1 (12), F1 (13); and 25(S) schidigera-saponins D3 (9), D4 (10), D5 (11), and F2 (14) were isolated, together with several related known saponins, and the structures were elucidated by spectroscopic methods (see Chart 1). The relationship between the antiyeast activities and the structures of these saponins is described.

Animals↗
PubMed2000

Cytological and cytogenetic effects of the fluoroquinolone ofloxacin on human periodontal ligament fibroblasts.

The fluoroquinolone ofloxacin (OFLX) is one of the candidates of antibacterial agents to be topically used against periodontitis. To estimate the maximum concentration of OFLX which exerts little or no adverse effect on the periodontal ligament, cytological and cytogenetic effects of OFLX on human periodontal ligament fibroblasts (Pel cells) were examined. Treatment of Pel cells with < or =0.3 mM OFLX for 24 or 48 h had little inhibitory effect on cellular growth and survival. DNA, RNA and protein syntheses in Pel cells did not decrease in response to treatment with < or =0.3 mM OFLX. The constitutive level of alkaline phosphatase mRNA was retained in cells treated with < or = 0.03 mM OFLX for 24 or 48 h. The level of type I procollagen mRNA was not affected by treatment with < or = 0.003 mM OFLX for 24 or 48 h. Cytogenetic effects of OFLX were evaluated by the ability of OFLX to induce chromosome aberrations in Pel cells. Treatment with OFLX at 0.3-3.0 mM for 6, 24, or 48 h failed to induce chromosome aberrations in Pel cells. The failure of OFLX to induce chromosome aberrations was seen even in the presence of exogenous metabolic activation using a 5% rat liver post-mitochondrial supernatant mixture. These results indicate that treatment of Pel cells with < or =0.003 mM OFLX has few or no adverse effects on the cytological and cytogenetic endpoints examined, suggesting that there would be little adverse effect on growth and differentiation of the periodontal ligament, as well as little cytogenetic activity, if OFLX were to be topically administered to the gingival crevice at the minimal inhibitory concentration (MIC90) against periodontopathic bacteria (< or = 0.0027 mM). It is important to note, however, that extrapolation of these findings to in vivo conditions has yet to be undertaken.

Alkaline Phosphatase↗
PubMed2000

The expression of a novel natural killer inhibitory molecule, Cho-1, on the chorionic cytotrophoblast cells of successful pregnancy, but not of spontaneous abortion.

The regulatory mechanism of the recognition and cytotoxicity by natural killer (NK) cells in placental tissue remains unclarified. Previous reports indicated that monoclonal antibody Cho-1-defined molecule (Cho-1 molecule) may act as the negative regulator in the cytotoxicity by human NK cells. The Cho-1 molecule is composed of non-covalently associated cell surface molecules of approximately 200 kDa and 40 kDa. In the present study we analyzed the expression of this novel molecule in extravillous cytotrophoblast cells, which are presumed to be exposed to the cytotoxic action by maternal NK cells, from clinical cases of successful pregnancy and spontaneous abortion. By using monoclonal antibody Cho-1, our immunohistochemical data indicated that the Cho-1 molecule is clearly expressed in the cytotrophoblast cells of the early phase of successful pregnancy, but only weakly expressed in those from spontaneous abortion. The cytotrophoblast cells in the late phase (9-10 months) of pregnancy also expressed this molecule. Fluorescence-activated cell sorter analysis also showed that it is expressed on the cytotrophoblast cell surface of successful pregnancy but not on that of spontaneous abortion, suggesting that Cho-1 antigen may act as a negative regulator of the cytotoxicity by NK cells in successful pregnancy of the fetus.

Abortion, Spontaneous↗
PubMed2000

Rapid identification and differentiation of pathogenic clostridia in gas gangrene by polymerase chain reaction based on the 16S-23S rDNA spacer region.

In cattle, sheep, and other ruminants, clostridial myonecrosis (gas gangrene) is mostly caused by Clostridium chauvoei, C septicum, C novyi and C sordellii. A polymerase chain reaction (PCR) system using common primers designed from multiple alignment of the 16S rRNA and 23S rRNA genes of Clostridium species was developed to identify pathogenic clostridia. The PCR was performed with total DNA from 26 strains which included seven different Clostridia species. These bacteria were differentiated at species level by the different PCR product patterns. To characterise the 16S-23S rDNA spacer regions of these clostridia further, most PCR products of these bacteria were sequenced. The smallest PCR products of each bacterium represented the fundamental 16S-23S rDNA spacer region; larger PCR products of each bacterium were caused by insertion sequences, i.e. tRNA gene sequences. The authors' observations indicate that the PCR patterns of the 16S-23S rDNA spacer regions have the potential to be used as an identification marker of pathogenic clostridia in gas gangrene.

Animals↗
PubMed2000

Inhibition of mitochondrial lipid peroxidation by Bakuchiol, a meroterpene from Psoralea corylifolia.

Bakuchiol, a meroterpene isolated from Psoralea corylifolia, prevented mitochondrial lipid peroxidation. Inhibition of oxygen consumption originating in lipid peroxidation was time-dependent. Bakuchiol protected mitochondrial respiratory enzyme activities against both NADPH-dependent and dihydroxyfumarate-induced peroxidation injury. Bakuchiol was shown to be effective to protect mitochondrial functions against oxidative stress.

Animals↗
PubMed2000

Inhibition of human telomerase activity by antisense phosphorothioate oligonucleotides encapsulated with the transfection reagent, FuGENE6, in HeLa cells.

Telomerase, a ribonucleoprotein, synthesizes telomeric repeats (TTAGGG) onto the ends of chromosomes to maintain the constant length of the telomere DNA, and its activity is detectable in approximately 85%-90% of primary human cancers. Thus, it is postulated that human telomerase might be associated with malignant tumor development and could be a highly selective target for antitumor drug design. Antisense phosphorothioate oligonucleotides (S-ODN) were investigated for their abilities to inhibit telomerase activity in the HeLa cell line. The S-ODN were designed to be complementary to nucleotides within the RNA active site of telomerase. As a transfection reagent, FuGENE6 (Boehringer Mannheim, Mannheim, Germany) was used to enhance the cellular uptake of the oligonucleotides in cell cultures. The S-ODN encapsulated with FuGENE6 clearly inhibited telomerase activity in HeLa cells and showed sequence-specific inhibition. The encapsulated S-ODN-3 with a 19-nucleotide, (nt) chain length had inhibitory effects similar to those of the 21-mer and 23-mer S-ODN sequences (S-ODN-4 and 5), but the 15-mer and 17-mer S-ODN sequences (S-ODN-1 and 2) failed to satisfactorily prevent telomerase activity. However, apoptotic HeLa cell death was not associated with telomerase inhibition. Furthermore, the encapsulated S-ODN did not appear to be cytotoxic in terms of the cell growth rate. The oligonucleotides encapsulated with the transfection reagent had enhanced cellular uptake, and cytoplasmic and nuclear localizations were observed. However, weak fluorescent signals were observed within the cytoplasms of HeLa cells treated with the free S-ODN-3. Thus, the activities of the S-ODN were effectively enhanced by using the transfection reagent. The transfection reagent, FuGENE6, may thus be a potentially useful delivery vehicle for oligonucleotide-based therapeutics and transgenes and is appropriate for use in vitro and in vivo.

Capsules↗