Biomedical subjects

Y Tamura

Publications and source records attributed to Y Tamura.

At least 55 records · Page 3Linked to original sources

PubMed2001

The cell surface-expressed HSC70-like molecule preferentially reacts with the rat T-cell receptor Vdelta6 family.

We previously showed that the cell surface-expressed Mr 70,000 heat shock cognate (hsc70, a constitutively expressed member of the hsp70 family) protein-like molecule (#067 molecule) interacts with rat CD3+, CD4-, CD8-, T-cell receptor (TCR)alphabeta-, natural killer recetor-P1- T cells. This 70hsc-like molecule was also suggested to present cellular peptide antigens to these T cells. In the present study, we identified the genetic structure of the TCR by establishing T-cell hybridomas between these T cells and mouse BW5147 cells. Our data indicated that these T cells preferentially used TCRs with the Vdelta6 family. Analysis of the nucleotide sequence of the CDR3 junctional portion showed that there are substantial diversities, with insertion of seven to nine amino acid residues. These data provide indirect evidences for our hypothesis that an hsc70-like molecule could be presented together with cellular peptide antigens to particular T cells with TCR gammadelta chains. Since the expression of this hsc70-like #067 antigen on the cell surface is usually induced along with cell transformation by activated oncogenes, T cells with the TCR Vdelta6 family are likely to contribute to host resistance to tumor cells.

Amino Acid Sequence↗

PubMed2001

Evaluation of long-term sequential changes in bone mass and strength following withdrawal of incadronate disodium (YM175) in ovariectomized rats.

We evaluated the long-term effects of withdrawal of a newer third-generation bisphosphonate, incadronate disodium (YM175), on both cancellous and cortical bone mass and strength in ovariectomized (OVX) rats. One hundred and sixty female SD rats at 13 weeks of age were randomized into four groups: sham-operated, OVX, and low- and high- YM (0.01 or 0.1 mg/kg s.c., three times a week after OVX). After 4 weeks of treatment with vehicle or incadronate disodium, rats from each group (n = 8) were killed at 0 (baseline), 3, 6, 9, and 12 months after the withdrawal of YM175. Histomorphometric studies of the proximal tibia revealed a dose-dependent decrease in OVX-induced bone turnover; cancellous bone volume was significantly higher in the YM groups compared with the OVX control group up to 6 months after withdrawal at low dose and up to 12 months after withdrawal at high dose. The low-dose group showed little effect on tibial diaphyseal cortical bone volume and width, while the high-dose group preserved both cortical parameters 12 months after withdrawal. Mechanical testing of femurs revealed that both metaphyseal and diaphyseal strengths were significantly higher at high dose compared with the OVX group until 12 months after withdrawal. These observations demonstrated that high-dose incadronate disodium preserved both cancellous and cortical bone mass and strength in OVX rats for 12 months after withdrawal of the agent.

Animals↗

PubMed2001

The immunohistochemical localization of Bax and Bcl-2 and their relation to apoptosis during amelogenesis in developing rat molars.

Bax and Bcl-2 are members of a family of intracellular, membrane-associated proteins that regulate programmed cell death. It has been suggested that, when Bax predominates, programmed cell death is accelerated and the apoptosis inhibitory activity of Bcl-2 is suppressed. The present study was undertaken to immunohistochemically (IHC) localize Bax and Bcl-2 in the cells of the enamel organ during amelogenesis in rat molars. Also, apoptotic cells were detected by TUNEL staining. The IHC intense localization of Bcl-2 and light staining for Bax in the pre-ameloblasts suggest that apoptosis is inhibited in the proliferating pre-ameloblasts. This is consistent with an absence of TUNEL staining for apoptosis in these cells. However, in the late secretory and transition ameloblasts, and adjacent stratum intermedium, evidence of apoptosis of the ameloblasts was observed. Bax and Bcl-2 were co-localized in the proximal ends of late secretory, transition and early maturation-stage ameloblasts, but immunoreactivity for Bax markedly increased in the proximal ends of late secretory and transition ameloblasts, while the Bcl-2 staining appeared to be lighter. This suggests that Bax antagonized Bcl-2 function, limiting the ability of Bcl-2 to prolong cell survival. In the early maturation stage, Bax staining faded while the immunoreactivity for Bcl-2 increased. Evidence of distinct apoptosis was reduced in the early maturation stage ameloblasts. When related to the occurrence of apoptosis during amelogenesis, the relative intensity of expression of Bax and Bcl-2 changed in a pattern consistent with that observed in other cell lines. This indicates that these proteins play essential roles in the process of amelogenesis, as predicted by their proposed mechanisms of action in the control of apoptosis.

Age Factors↗

PubMed2001

The LDL receptor is the major pathway for beta-VLDL uptake by mouse peritoneal macrophages.

In order to determine the contribution of the low density lipoprotein receptor (LDL-R) to the removal of apoB-containing native lipoproteins by macrophages, we compared the uptake of beta-VLDL in peritoneal macrophages (MPM) from wild type mice and mice lacking the LDL-R. The d<1.006 g/ml lipoproteins obtained from apoE deficient mice fed a high fat diet were poorly degraded by macrophages and caused only a slight formation of CE in macrophages from both types of mice. On the other hand, d<1.006 g/ml lipoproteins obtained from LDL-R deficient mice fed a high fat diet, beta-VLDL with apoE, were avidly taken up by and markedly stimulated CE formation in wild type macrophages, but not in macrophages lacking the LDL-R. The degradation of 125I-labeled-apoE-containing beta-VLDL by wild type MPM was poorly inhibited by unlabeled human LDL, and beta-VLDL without apoE had no effects. In conclusion, we propose that the in vitro uptake of native apoE-enriched lipoproteins by murine macrophages is primarily mediated by the LDL receptor and not by other apoE-recognizing receptor systems such as: the LDL receptor related protein, the VLDL receptor or the triglyceride-rich lipoprotein receptor.

Animals↗

PubMed2001

Network structures and thermal properties of polyurethane films prepared from liquefied wood.

Polyurethane (PU) films were prepared by solution-casting after co-polymerization of liquefied woods (LWs) and polymeric methylene diphenylene diisocyanate (PMDI). The resulting PU films had various [NCO]/[OH] ratios ranging from 0.6 to 1.4 and contained 5.0-16.8% dissolved woody components at the [NCO]/[OH] ratio of 1.0. The crosslink densities of the films with [NCO]/[OH] ratios of 0.6-1.4 increased remarkably with increasing [NCO]/[OH] ratio. Similarly, there were large increases in glass transition temperatures (Tg). These characteristics could be attributed to effective incorporation of PMDI into the LW. The crosslink densities and Tg of the PU films prepared at the [NCO]/[OH] ratio of 1.0 increased because the amounts of dissolved woody components in the films increased. It is concluded that the dissolved woody components acted as crosslinking points in PU network formations. The thermal degradation of the PU films at an [NCO]/[OH] ratio of more than 0.8 or with more than 10.6% dissolved wood started above 262 degrees C under an N2 atmosphere. The thermostability was lost at low crosslink density or with large amount of co-polymerized glycerol structures in the PU networks.

Calorimetry, Differential Scanning↗

PubMed2001

Scanning electron microscopy description of a new species of Demodex canis spp.

Between 1997 and 1999, the prevalence of Demodex canis mites was determined in 150 dogs. In two dogs, we found two different species of mites; Demodex canis and another, unidentified, Demodex mite. The unidentified Demodex mite species had several different morphological features. First, it had a short opisthosoma and an obtuse end. In addition, the fourth coxisternal plate was rectangular and there was a band-like segmental plate between the fourth coxisternal plate and opisthosoma. Although all of the morphology and the development of male mites could not be investigated in this study, the location of the opisthosoma and the genital pore clearly differed from Demodex canis, suggesting that this unidentified mite is a new species.

Animals↗

PubMed2001

IPF, a vesicular uptake inhibitory protein factor, can reduce the Ca(2+)-dependent, evoked release of glutamate, GABA and serotonin.

Synaptic vesicles in the nerve terminal play a pivotal role in neurotransmission. Neurotransmitter accumulation into synaptic vesicles is catalyzed by distinct vesicular transporters, harnessing an electrochemical proton gradient generated by V-type proton-pump ATPase. However, little is known about regulation of the transmitter pool size, particularly in regard to amino acid neurotransmitters. We previously provided evidence for the existence of a potent endogenous inhibitory protein factor (IPF), which causes reduction of glutamate and GABA accumulation into isolated, purified synaptic vesicles. In this study we demonstrate that IPF is concentrated most in the synaptosomal cytosol fraction and that, when introduced into the synaptosome, it leads to a decrease in calcium-dependent exocytotic (but not calcium-independent) release of glutamate in a concentration-dependent manner. In contrast, alpha-fodrin (non-erythroid spectrin), which is structurally related to IPF and thought to serve as the precursor for IPF, is devoid of such inhibitory activity. Intrasynaptosomal IPF also caused reduction in exocytotic release of GABA and the monoamine neurotransmitter serotonin. Whether IPF affects vesicular storage of multiple neurotransmitters in vivo would depend upon the localization of IPF. These results raise the possibility that IPF may modulate synaptic transmission by acting as a quantal size regulator of one or more neurotransmitters.

Animals↗

PubMed2001

Inhibition of vesicular glutamate storage and exocytotic release by Rose Bengal.

It had been thought that quantal size in synaptic transmission is invariable. Evidence has been emerging, however, that quantal size can be varied under certain conditions. We present evidence that alteration in vesicular [(3)H]L-glutamate (Glu) content within the synaptosome (a pinched-off nerve ending preparation) leads to a change in the amount of exocytotically released [(3)H]Glu. We found that Rose Bengal, a polyhalogenated fluorescein derivative, is a quite potent membrane-permeant inhibitor (K(i) = 19 nM) of glutamate uptake into isolated synaptic vesicles. This vesicular Glu uptake inhibition was achieved largely without affecting H(+)-pump ATPase. We show that various degrees of reduction elicited by Rose Bengal in [(3)H]Glu in synaptic vesicles inside the synaptosome result in a corresponding decrease in the amount of [(3)H]Glu released in a depolarization- (induced by 4-aminopyridine) and Ca(2+)-dependent manner. In contrast, fluorescein, the halogen-free analog of Rose Bengal, which is devoid of inhibitory activity on vesicular [(3)H]Glu uptake, failed to change the amount of exocytotically released [(3)H]Glu. These observations suggest that glutamate synaptic transmission could be altered by pharmacological intervention of glutamate uptake into synaptic vesicles in the nerve terminal, a new mode of synaptic manipulation for glutamate transmission.

4-Aminopyridine↗

PubMed2001

Inhibitory action of a novel proton pump inhibitor, rabeprazole, and its thioether derivative against the growth and motility of clarithromycin-resistant Helicobacter pylori.

BACKGROUND: Clarithromycin-resistant Helicobacter pylori (CRHP) has increasingly been isolated from patients in Japan. The aim of our study was to test whether proton pump inhibitors (PPIs) and their thioether derivatives, which are secreted into the gastric mucosa, could inhibit the growth and motility (a factor in colonization) of CRHP. MATERIALS AND METHODS: CRHP was isolated from patients who had experienced gastritis or peptic ulcers in Tokyo and Niigata. Drugs and related agents tested were omeprazole, lansoprazole, rabeprazole, the thioether derivative of rabeprazole (rabeprazole-TH), clarithromycin, amoxicillin and metronidazole. The MICs of the drugs and agents for H. pylori strains were determined by the agar dilution METHOD: Bacterial swimming in a liquid layer was examined under an inverted, phase-contrast microscope. RESULTS: The PPIs and rabeprazole-TH, but not the anti-H. pylori agents, inhibited the motility of CRHP at both pH 7.4 and 6.0. The concentrations (microg/ml) necessary to inhibit 50% of the motility at pH 7.4 were 0.25-0.5, 8-32, 8-16 and 128-256 for rabeprazole-TH, rabeprazole, lansoprazole and omeprazole, respectively. Rabeprazole-TH exhibited the strongest inhibitory effect against the growth of CRPH (MIC, 0.5 microg/ml). CONCLUSION: Rabeprazole-TH, which is secreted into the gastric mucosa, had the strongest inhibitory action against both the growth and motility of CRHP, suggesting that it is a potential novel agent for CRHP eradication.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed2001

Amplification of the 16S-23S rDNA spacer region for rapid detection of Clostridium chauvoei and Clostridium septicum.

Amplification of the 16S-23S rDNA spacer region by polymerase chain reaction (PCR) was used for the rapid detection of Clostridium chauvoei and C septicum. To assess its specificity, PCR was performed with total DNA from 42 strains of clostridia and three strains of other genera. PCR products specific to C chauvoei or to C septicum were generated from homologous cultures only. Clostridium chauvoer-specific or C septicum-specific amplicons were also generated from tissues of cows experimentally infected with C chauvoei or C septicum and in DNA samples from cows clinically diagnosed as having blackleg or malignant oedema. These results suggest that a species-specific PCR may be useful for the rapid and direct detection of C chauvoei and C septicum in clinical specimens.

Animals↗

PubMed2001

Surgical treatment for recurrent dislocation of the extensor carpi ulnaris tendon.

Twelve patients with recurrent dislocation of the extensor carpi ulnaris tendon were treated with repair or reconstruction of its tendon sheath, and each had a satisfactory result. We found three types of disruption of the fibro-osseous sheath. Type A: the fibro-osseous sheath ruptured ulnarly and the torn sheath lay superficial to the tendon (n=5). These were treated by reconstruction of the sheath using a piece of the extensor retinaculum. Type B: the fibro-osseous sheath ruptured radially and the torn sheath lay in the ulnar groove beneath the tendon (n=3). These were treated by direct suture of the sheath over the tendon. Type C: detachment of the periosteum from the ulnar side of the ulna in continuity with the fibro-osseous sheath formed a false pouch into which the tendon easily dislocated (n=4). These were treated by reattachment of the periosteum.

Adult↗

PubMed2001

Feeding dried purple laver (nori) to vitamin B12-deficient rats significantly improves vitamin B12 status.

To clarify the bioavailability of vitamin B12 in lyophylized purple laver (nori; Porphyra yezoensis), total vitamin B12 and vitamin B12 analogue contents in the laver were determined, and the effects of feeding the laver to vitamin B12-deficient rats were investigated. The amount of total vitamin B12 in the dried purple laver was estimated to be 54.5 and 58.6 (se 5.3 and 7.5 respectively) microg/100 g dry weight by Lactobacillus bioassay and chemiluminescent assay with hog intrinsic factor respectively. The purple laver contained five types of biologically active vitamin B12 compounds (cyano-, hydroxo-, sulfito-, adenosyl- and methylcobalamin), in which the vitamin B12 coezymes (adenosyl- and methylcobalamin) comprised about 60 % of the total vitamin B12. When 9-week-old vitamin B12-deficient rats, which excreted substantial amounts of methylmalonic acid (71.7(se 20.2) micromol/d) in urine, were fed the diet supplemented with dried purple laver (10 microg/kg diet) for 20 d, urinary methylmalonic acid excretion (as an index of vitamin B12 deficiency) became undetectable and hepatic vitamin B12 (especially adenosylcobalamin) levels were significantly increased. These results indicate that vitamin B12 in dried purple laver is bioavailable to rats.

Animals↗

PubMed2001

Visualization of tumor vessels in renal tumors. Comparison between power Doppler ultrasonography and angiography.

PURPOSE: To compare the ability of power Doppler ultrasonography (PDUS) with that of renal angiography for assessment of renal tumor vessels. MATERIAL AND METHODS: We performed PDUS and angiography in 52 histologically proven renal parenchymal tumors (50 renal cell carcinomas (RCCs) and 2 oncocytomas), and compared vascularity on PDUS and angiography. The vascularity of PDUS was graded as follows: grade 0-- no recognizable tumor vessel; grade 1-- hypovascular to surrounding renal interlobar arteries; grade 2-- hyper- or isovascular to surrounding renal interlobar arteries. RESULTS: With PDUS, 41 tumors were grade 2 and 11 were grade 1. With angiography, 44 lesions had iso/hypervascular pattern, 6 hypovascular pattern, and 2 were judged to be avascular. Among 44 iso/hypervascular tumors, 41 were grade 2, and 3 were grade 1. These latter 3 were located deeper than 7 cm. Six hypovascular tumors and 2 avascular tumors were grade 1. The 2 avascular tumors were small and hypovascular. The kappa-level of agreement was 0.81. CONCLUSION: There was very good agreement between PDUS and angiography in visualizing renal tumor vessels. PDUS appears appropriate for assessing renal tumor vascularity as compared to angiography in small and hypovascular lesions, but deep location reduced the detectability of tumor vessels with PDUS.

Adult↗

PubMed2001

Inhibition of HIV-1 replication by 5'LTR decoy RNA.

Long terminal repeats (5'-LTR) contain essential enhancer and promoter elements that act as targets for cellular and viral regulatory proteins. The interplay of these cis-acting sequences with specific transcription factors (NF kappa B, Ap1, and Sp1) present in infected cells determines the rate of transcription initiation from the 5'-LTR promoter element, and thus strongly influences the level of viral replication. Furthermore, Tat functions to enhance transcriptional elongation by binding to the trans-activation response element (TAR). These transcriptional factors enhance the transcriptional elongation from the HIV-1 promoter. HIV-1 genomic RNA packaging is a highly specific process involving interactions between the viral Gag precursor and cis acting packaging signals in the 5' leader sequence of HIV-1 genomic RNA. We examined the suppression effect of HIV-1 expression by the decoy RNAs targeted to these HIV-1 transcriptional and packaging regulatory regions. HIV-1 expression was inhibited by the 5'-LTR decoy RNA, and measured by the amount of HIV-1 gag p24 protein, but no inhibition of HIV-1 packaging could be detected.

Animals↗

PubMed2001

Regional myocardial metabolic rate of oxygen measured by O2-15 inhalation and positron emission tomography in patients with cardiomyopathy.

BACKGROUND: Positron emission tomography (PET) metabolic studies have investigated the pathways involved in fatty acid, glucose, and oxidative metabolism in cardiomyopathy and the impairments that occur in the damaged myocardium, but none have provided absolute quantitative variables. Recently, quantitative measurements of the metabolic rate of oxygen (MMRO2) and oxygen extraction fraction (OEF) using O2-15-labeled oxygen gas have been validated in animals and healthy volunteers. The purposes of the current study were to measure MMRO2 and OEF in cardiomyopathy with left ventricular (LV) dysfunction. METHODS: The authors selected 25 study participants: 16 patients (10 with ischemic and 6 with dilated) cardiomyopathy with LV dysfunction, and 9 healthy volunteers. As evaluated by echocardiography, LV ejection fraction (LVEF) was decreased in patients (35%+/-9% vs. 65%+/-5%, P<0.01). The PET protocol consisted of transmission, C O2-15 static, H2 O-15 dynamic, and O2-15 gas inhalation steady state scans. An entire myocardial region of interest was drawn to encompass the entire LV myocardium on three midventricular slices in each participant. RESULTS: Data showed in patients with dilated cardiomyopathy significant reductions of MMRO2 (0.051+/-0.02 ml x min(-1) x g(-1) vs. 0.108+/-0.02 ml x min(-1) x g(-1), p = 0.01) and OEF (0.55+/-0.15 vs. 0.71+/-0.08, P = 0.01) when compared with healthy volunteers. Furthermore, OEF decreased significantly in lateral and inferior walls. Significant correlations were observed among OEF and the rate-pressure product (RPP) (P = 0.02), LVEF (P<0.001), MMRO2 and RPP (P = 0.04), and LVEF (P = 0.05). In patients with ischemic cardiomyopathy, MMRO2 was significantly reduced (0.039+/-0.02 ml x min(-1) x g(-1) vs. 0.108+/-0.02 ml x min(-1) x g(-1); p = 0.005) but not OEF (0.63+/-0.2 vs. 0.71+/-0.08; P = NS), when compared with healthy volunteers. Significant correlations were observed among OEF and RPP (P = 0.03), LVEF (P = 0.002), MMRO2 and RPP (P<0.01), and LVEF (P = 0.03). CONCLUSIONS: These data show that O2-15 gas inhalation and PET allow myocardial MMRO2 and OEF to be measured in patients with cardiomyopathy.

Administration, Inhalation↗

PubMed2001

Inactivating mutations of calcium-sensing receptor results in parathyroid lipohyperplasia.

Familial hypocalciuric hypercalcemia (FHH) is an autosomal dominant disease characterized by mild hypercalcemia, an inappropriately high parathyroid hormone level, and absence of hypercalciuria. Heterozygous inactivating mutations of calcium-sensing receptor (CaSR) are found in about two thirds of patients with FHH. Histologic examination of parathyroid glands in FHH is reported to show normal histology or chief cell hyperplasia. Thus, histologic features of the parathyroid glands in FHH vary, and there is no clear histologic criterion that indicates FHH. The authors have encountered three hypercalcemic patients with characteristic histologic features of enlarged parathyroid glands. Clusters of parenchymal cells were mixed with fat cells, and the area of fat cells was 33% to 49% of the total area. These features are similar to those described as parathyroid lipohyperplasia. Postoperative evaluation showed that fractional excretion of calcium was low in these patients. Direct sequencing of the polymerase chain reaction product showed that the first patient was heterozygous for an already reported inactivating mutation of CaSR (P55L). The second patient was also heterozygous for a novel inactivating mutation (R220W). The third was homozygous for an inactivating mutation (Q27R). These results indicate that histologic features of parathyroid lipohyperplasia suggest the presence of inactivating mutations of CaSR.

Adipose Tissue↗

PubMed2001

Phylogenetic positions of Clostridium novyi and Clostridium haemolyticum based on 16S rDNA sequences.

The partial sequences (1465 bp) of the 16S rDNA of Clostridium novyi types A, B and C and Clostridium haemolyticum were determined. C. novyi types A, B and C and C. haemolyticum clustered with Clostridium botulinum types C and D. Moreover, the 16S rDNA sequences of C. novyi type B strains and C. haemolyticum strains were completely identical; they differed by 1 bp (level of similarity > 99.9%) from that of C. novyi type C, they were 98.7% homologous to that of C. novyi type A (relative positions 28-1520 of the Escherichia coli 16S rDNA sequence) and they exhibited a higher similarity to the 16S rDNA sequence of C. botulinum types D and C than to that of C. novyi type A. These results suggest that C. novyi types B and C and C. haemolyticum may be one independent species generated from the same phylogenetic origin.

Clostridium↗

PubMed2001

Cluster analysis of human and animal pathogenic Microsporum species and their teleomorphic states, Arthroderma species, based on the DNA sequences of nuclear ribosomal internal transcribed spacer 1.

We performed a cluster analysis of human and animal pathogenic Microsporum species and their teleomorphic states, Arthroderma species, including A. otae-related species (M. canis, M. audouinii, M. distortum, M. equinum, M. langeronii, and M. ferrugineum) and M. gypseum complex (A. fulvum, A. gypseum, and A. incurvatum) using DNA sequences of nuclear ribosomal internal transcribed spacer 1 (ITS1). The dendrogram showed the members of A. otae-related species to be monophyletic and to construct an extremely closely related cluster with a long horizontal branch. This ITS1-homologous group of A. otae was organized in 6 unique genotypes, while sequences of the members of the ITS1-homologous group of M. gypseum complex are more diverse. This ITS1-based database of Microsporum species and their teleomorphic states will provide a useful and reliable species identification system: it is time-saving (takes two to three days), accurate and applicable even to strains with atypical morphological features or in a non-culturable state.

Animals↗