Biomedical subjects

Y Tamura

Publications and source records attributed to Y Tamura.

At least 163 records · Page 9Linked to original sources

PubMed1999

Trabecular remodeling processes in the ovariectomized rat: modified node-strut analysis.

The purpose of this study was to evaluate the trabecular bone remodeling processes in ovariectomized rats, focusing on diminishing trabecular connectivity. We used modified node-strut analysis defining three areas in the trabecular surfaces for the three-dimensional understanding of trabecular resorption derived from two-dimensional conventional sections, in addition to conventional bone histomorphometry and node-strut analysis. Seven-month-old female Wistar rats were used and treated with bilateral ovariectomy (ovx) and sham operation. Six rats in each group were examined at 4 and 8 weeks. We prepared undecalcified sections from the left tibiae with Villanueva bone and Goldner stains. We divided the trabecular bone surfaces (BS) into three areas: node (Nd), terminus (Tm), and strut (St), and measured the bone resorption and formation parameters, including eroded surface (ES), osteoclast surface (Oc.S), osteoid surface (OS), and double-labeled surface (dLS) in each defined area. In conventional bone histomorphometry, the ovx group showed high turnover osteopenia compared with the sham operation group. In node-strut analysis, the ovx group showed significantly lower values for node-related parameters than did the sham operation group. In the modified node-strut analysis, bone resorption parameters in the ovx group showed significantly higher values, particularly for strut and terminus-eroded surfaces (StES/BS, TmES/BS), and for each area of osteoclast surface (NdOc.S/BS, TmOc.S/BS, and StOc.S/BS) compared with the sham operation group. Bone formation parameters in the ovx group also showed significantly higher values, particularly for strut and terminus osteoid surfaces (TmOS/BS, StOS/BS), and for each area of double-labeled surface (NddLS/BS, TmdLS/BS, and StdLS/BS) compared with the sham operation group at 4 weeks. At 8 weeks, each area of bone formation parameter in the ovx group showed significantly higher values than that in the sham operation group. These results suggest that in the ovx group, the trabecular plates became perforated and the perforative cavities progressively enlarged, and/or the edges of plates were eroded regardless of elevated bone formation, resulting in diminished trabecular connectivity, and the node area might not be influenced relatively by bone remodeling in the early resorption.

Animals↗

PubMed1999

Dried green and purple lavers (Nori) contain substantial amounts of biologically active vitamin B(12) but less of dietary iodine relative to other edible seaweeds.

Vitamin B(12) concentrations of dried green (Enteromorpha sp.) and purple (Porphyra sp.) lavers (nori) were determined by both Lactobacillus leichmannii ATCC 7830 microbiological and intrinsic factor chemiluminescence methods. The values determined by using the microbiological method (63.58 +/- 2.90 and 32.26 +/- 1.61 microg/100 g of dry weight) were identical to those found by using the chemiluminescence method (69.20 +/- 2.21 and 25.07 +/- 0.54 microg/100 g of dry weight) in both dried green and purple lavers, respectively. A silica gel 60 thin-layer chromatography of both laver extracts shows that non-coenzyme forms (hydroxo and cyano forms) of vitamin B(12) predominate in both dried lavers. The dried lavers contained lesser amounts of dietary iodine ( approximately 4-6 mg/100 g of dry weight) relative to other seaweeds, suggesting that excessive intake of the dried lavers is unlikely to result in harmful intake of dietary iodine. These results indicate that the dried lavers (nori) are the most excellent source of vitamin B(12) among edible seaweeds, especially for strict vegetarians.

Iodine↗

PubMed1999

Pseudovitamin B(12) is the predominant cobamide of an algal health food, spirulina tablets.

The vitamin B(12) concentration of an algal health food, spirulina (Spirulina sp.) tablets, was determined by both Lactobacillus leichmannii ATCC 7830 microbiological and intrinsic factor chemiluminescence methods. The values determined with the microbiological method were approximately 6-9-fold greater in the spirulina tablets than the values determined with the chemiluminescence method. Although most of the vitamin B(12) determined with the microbiological method was derived from various vitamin B(12) substitutive compounds and/or inactive vitamin B(12) analogues, the spirulina contained a small amount of vitamin B(12) active in the binding of the intrinsic factor. Two intrinsic factor active vitamin B(12) analogues (major and minor) were purified from the spirulina tablets and partially characterized. The major (83%) and minor (17%) analogues were identified as pseudovitamin B(12) and vitamin B(12), respectively, as judged from data of TLC, reversed-phase HPLC, (1)H NMR spectroscopy, ultraviolet-visible spectroscopy, and biological activity using L. leichmannii as a test organism and the binding of vitamin B(12) to the intrinsic factor.

Bacterial Proteins↗

PubMed1999

An adult patient with severe hypercalcaemia and hypocalciuria due to a novel homozygous inactivating mutation of calcium-sensing receptor.

Inactivating mutations in the calcium-sensing receptor (CaSR) cause familial hypocalciuric hypercalcaemia (FHH) and neonatal severe hyperparathyroidism (NSHPT). Earlier investigations showed patients with FHH are heterozygous, and NSHPT are homozygous for inactivating mutations. However, one adult patient with severe hypercalcaemia and hypocalciuria has been reported to have a homozygous inactivating mutation in CaSR (Pro39Ala). This suggested that mutant CaSR in this patient had some residual activity and hypercalcaemia was not so severe as to be fatal. However, the function of this mutant CaSR was not evaluated. In the present study, we describe a novel homozygous mutation in an adult patient with severe hypercalcaemia and hypocalciuria, and evaluate the function of the mutant CaSRs. The DNA sequence of CaSR gene was determined by direct sequencing of the polymerase chain reaction product. The function of mutant CaSR was analysed by creating mutant cDNAs by in vitro mutagenesis, transfection of mutant cDNAs into HEK293 cells and measuring intracellular ionized Ca in response to changes in extracellular Ca. A 26-year-old Japanese woman showed marked hypercalcaemia with an elevated parathyroid hormone (PTH) level. Her consanguineous parents had asymptomatic hypercalcaemia with relative hypocalciuria. The proband had a homozygous mutation at codon 27 of CaSR gene (CAA-->CGA, Gln27Arg). Her parents were heterozygous for this mutation. EC50 for Ca of this mutant CaSR (GIn27Arg) was 4.9 mM. EC50 of another mutant CaSR (Pro39Ala) whose homozygous mutation was discovered in an adult patient was 4.4 mM. These EC50s were significantly higher than that of wild-type CaSR (3.7} 0.1 mM), but were the lowest among the reported EC50s for inactivating mutations of CaSR. These results indicate that serum Ca and PTH levels are determined by residual function of mutant CaSR in patients with homozygous mutation in CaSR, and that patients having homozygous mutant CaSRs with mild dysfunction do not suffer from fatal hypercalcaemia in infancy and can survive into adulthood.

Adult↗

PubMed1999

CD14 transgenic mice expressing membrane and soluble forms: comparisons of levels of cytokines and lethalities in response to lipopolysaccharide between transgenic and non-transgenic mice.

Two different metallothionein promoter-mouse CD14 fusion genes were constructed. The membrane form of the CD14 fusion gene, designated M14M, contained the full-length CD14 cDNA sequence, whereas the soluble form of the fusion gene, designated M14S, was truncated to lack the sequence for the phosphatidylinositol-anchoring site. Expression of transgenic RNA in M14M and M14S mice on the basal diet was abundant in the liver. After maintenance with water containing ZnSO4 (50 mM) for 4 days, expression of transgenic RNA in M14M and M14S mice was strong in the small intestine. Immunohistochemical analysis demonstrated CD14 expression in these organs in M14S and M14M mice. Levels of CD14 in sera from M14S mice after zinc administration were significantly higher than these animals maintained with normal water, M14M mice after zinc administration and non-transgenic mice. Sera from M14S and M14M mice after stimulation with lipopolysaccharide LPS (LPS) demonstrated significantly lower levels of tumor necrosis factor-alpha and IL-6 than those from non-transgenic mice. Lethality in endotoxin shock produced by i.p. injection of 30-40 microg/g body wt LPS was not different between M14S, M14M and non-transgenic mice. However, survival rates in the lethal Shwartzman reaction induced by priming and challenge injections of LPS were significantly higher in M14M and M14S mice than in non-transgenic mice.

Animals↗

PubMed1999

A case of advanced esophageal cancer showing a long-term complete response with chemotherapy with nedaplatin alone.

We describe a case of advanced esophageal cancer treated successfully by chemotherapy with nedaplatin alone. A 60-year-old male with type 2 advanced esophageal cancer, which was located in the upper part of the esophagus and had invaded adjacent organs, was treated with nedaplatin 150 mg/body (100 mg/m2) given intravenously every 4 weeks from January 6, 1991. He achieved a partial response (PR) and was discharged in March 1991. Subsequently, he received nedaplatin 75 mg/body in an out-patient setting almost every month until August 1992. Toxicities were tolerable and included mild thrombocytopenia and nausea/vomiting. From serial evaluation in October 1993, the esophageal tumor was not observed. After 7 years since initial chemotherapy was administered, he still survives without the disease.

Antineoplastic Agents↗

PubMed1999

Phosphorothioate G3T4G3 motifs inhibits the early stage of HIV-1 infection.

It is well known that G-rich phosphorothioate oligonucleotides (G-rich PS) bind to the V3 loop of HIV-1 gp120 and inhibit HIV-1 infection. In this study, we investigated the inhibitory mechanism of a new type of G-rich PS (PS-G3T4G3) on the replication cycle of HIV-1. PS-G3T4G3 inhibits both cell to cell and cell free infections. Binding and entry assays revealed that the inhibitory step of PS-G3T4G3 occurs at the early stage of HIV-1 infection. V3 loop-specific mAb test showed that PS-G3T4G3 binds to the V3 loop and prevents its interaction with chemokine receptors. These results suggest that PS-G3T4G3 may be a novel candidate for an HIV-1 inhibitor.

Base Composition↗

PubMed1999

Development of an HIV-1-dependent expression vector with the Cre/loxP system.

Previously, we used the human methionine tRNA promoter as an expression cassette for hammerhead ribozymes. The tRNA promoter driven ribozyme was targeted against the LTR portion of the HIV-1 NL4-3 strain. We constructed VSV-G-pseudotyped MuLV-based vectors expressing the ribozyme. The ribozyme expressing retrovirus vector strongly suppressed gag p24 antigen production in freshly HIV-1 infected MT-4 cells. In this study, the potential of such a molecular genetic intervention was examined by using the Cre-loxP recombination system. Site-specific excision of HIV-1 was achieved by using this model system with an acute infection. These studies represent one step toward the development of a novel antiviral strategy for the treatment of AIDS.

Animals↗

PubMed1999

Effect of ebselen on contractile responses in perfused rabbit basilar artery.

OBJECTIVE: To evaluate the possible role of the antioxidant ebselen in the treatment of cerebral vasospasm, we examined the effects of ebselen on the vasoactive mechanisms induced by endothelin (ET)-1, oxyhemoglobin, and oxygen-derived radicals. METHODS: Isolated rabbit basilar arteries with intact endothelium were fixed in a perfusion system and perfused intraluminally. Contraction of the artery was detected as an increase in perfusion pressure. RESULTS: Ebselen, in a certain concentration range (3 x 10(-6) and 10(-5) mol/L), significantly reduced the contractile response to ET-1 (10(-10) to 10(-8) mol/L) but not the contraction induced by 40 mmol/L potassium. It reduced the contraction induced by 10(-4) mol/L 1,2-dioctanoyl-sn-glycerol, a protein kinase C activator. Addition of 10(-5) mol/L dithiothreitol, a sulfhydryl-reducing agent, partially reversed the inhibitory effects of ebselen on ET-1- and 1,2-dioctanoyl-sn-glycerol-induced contractions. Ebselen (10(-5) mol/L) as well as a combination of catalase (1000 units/mL) and superoxide dismutase (150 units/mL) inhibited the potentiating effects of oxyhemoglobin (10(-5) mol/L) on ET-1-induced contraction. Both ebselen and catalase inhibited the contractile response to hydroxyl radical generated by ferrous ion (10(-3) mol/L) plus hydrogen peroxide (10(-2) mol/L). Ebselen reduced the response to potassium when a high dose (3 x 10(-5) mol/L) was applied and failed to preserve contractility of the preparation after exposure to hydroxyl radical. CONCLUSION: Ebselen suppressed ET-1-induced contraction and synergetic interaction between oxyhemoglobin and ET-1, where free radical formation was involved. These effects may result from modification of the intracellular regulatory system including protein kinase C, as well as from protection against free radicals.

Animals↗

PubMed1999

A novel negative regulator molecule, Cho-1, is involved in the cytotoxicity by human natural killer cells but not in cytotoxic T lymphocytes.

We previously reported the cytotoxic negative regulatory molecule, Cho-1, that was expressed on the cell surface of rat fetal fibroblast cells in the cytotoxicity by natural killer (NK) cells. This molecule was IFN-gamma-inducible, but appeared to be different from MHC class I. It was expressed on NK-resistant cells but not on NK-sensitive murine target cells such as YAC-1. In this paper, first we determined whether Cho-1 could also act as the negative regulatory molecule in a human NK-resistant HEPM line. Our data strongly suggested that Cho-1 could act as such a negative regulatory molecule in human NK cytotoxicity. The immunoprecipitates made with HEPM cell lysate and anti-MHC class I monoclonal antibody (mAb) did not react against anti-Cho-1 mAb, indicating that Cho-I was different from MHC class I. Second, an assessment was made as to whether or not this molecule is involved in the cytotoxicity of CD8 (+) cytotoxic T lymphocytes (CTL) against human autologous tumor cells. The data indicated that although this cell surface molecule was expressed on certain tumor lines, it was not involved in the cytotoxic mechanism of CTL. Thus, Cho-1 appeared to be the novel regulatory molecule in the NK cytotoxic mechanism.

Animals↗

PubMed1999

Molecular epidemiology of rabies in Thailand.

For the purpose of making clear the dynamics of rabies viruses that are prevalent among dogs in Asia, especially Thailand, nucleoprotein (N) genes of isolates derived from Thailand were partially sequenced, and a phylogenetic analysis was performed on the basis of the sequencing data. Firstly, all 27 isolates from Thailand belonged to one group that was distantly related to an isolate from China and was separated into at least six lineages. On the other hand, the isolate from Japan was related to viruses from the Arctic. Secondly, in order to analyze the diversity of the N gene more conveniently, restriction fragment length polymorphism (RFLP) analysis was performed on the N gene of 27 isolates from Thailand. The RFLP analysis could distinguish the lineages of each isolate, and the lineages of additional 34 isolates were deduced by this method. On examination of the geographical distribution of the six lineages, based on the results of phylogenetic and RFLP analyses, it was clear that infection cycles of the rabies virus in Thailand have tended to be maintained endemically.

Animals↗

PubMed1999

Phylogenetic classification and species identification of dermatophyte strains based on DNA sequences of nuclear ribosomal internal transcribed spacer 1 regions.

The mutual phylogenetic relationships of dermatophytes of the genera Trichophyton, Microsporum, and Epidermophyton were demonstrated by using internal transcribed spacer 1 (ITS1) region ribosomal DNA sequences. Trichophyton spp. and Microsporum spp. form a cluster in the phylogenetic tree with Epidermophyton floccosum as an outgroup, and within this cluster, all Trichophyton spp. except Trichophyton terrestre form a nested cluster (100% bootstrap support). Members of dermatophytes in the cluster of Trichophyton spp. were classified into three groups with ITS1 homologies, with each of them being a monophyletic cluster (100% bootstrap support). The Arthroderma vanbreuseghemii-Arthroderma simii group consists of A. vanbreuseghemii, A. simii, Trichophyton mentagrophytes isolates from humans, T. mentagrophytes var. quinckeanum, Trichophyton tonsurans, and Trichophyton schoenleinii. Arthroderma benhamiae, T. mentagrophytes var. erinacei, and Trichophyton verrucosum are members of the Arthroderma benhamiae group. Trichophyton rubrum and Trichophyton violaceum form the T. rubrum group. This suggests that these "species" of dermatophytes have been overclassified. The ITS1 sequences of 11 clinical isolates were also determined to identify the species, and all strains were successfully identified by comparison of their base sequences with those in the ITS1 DNA sequence database.

Arthrodermataceae↗

PubMed1999

Effect of intravenous dipyridamole on cerebral blood flow in humans. A PET study.

BACKGROUND AND PURPOSE: Dipyridamole increases the concentration of circulating adenosine, which is a potent vasodilator, by inhibition of uptake of adenosine into the erythrocytes, and hence produces coronary vasodilation. However, the effects of dipyridamole on cerebral circulation is not pronounced. This study investigates the effects of intravenous dipyridamole on cerebral blood flow (CBF) in humans with use of positron emission tomography (PET). METHODS: In each of 13 healthy subjects, CBF was measured using (15)O-labeled water and PET at rest and during hypercapnia, hypocapnia, and dipyridamole stress; corresponding CBF values were then compared. RESULTS: CBF values during dipyridamole stress were significantly lower than those measured at rest. The dipyridamole stress PaCO(2) was also significantly lower than the resting PaCO(2). The change in CBF during dipyridamole stress relative to PaCO(2) closely followed the relationship between CBF and PaCO(2) during hypocapnia. CONCLUSIONS: These results indicate that the observed decrease in CBF during dipyridamole stress was caused by a decrease in PaCO(2) rather than by any direct action of dipyridamole on CBF. The decrease in PaCO(2) during dipyridamole stress was most likely due to hyperventilation, which was a side effect of adenosine. These results support the hypothesis that circulating adenosine is largely prevented from binding to adenosine receptors of cerebral vessels by the blood-brain barrier.

Aged↗

PubMed1999

Plasma level of homocysteine is correlated to extracranial carotid-artery atherosclerosis in non-hypertensive Japanese.

BACKGROUND: Results of some epidemiologic studies in Western countries have clarified that hyperhomocysteinemia is a plausible risk factor for atherosclerotic vascular disease, but its role in Japanese communities is not known. DESIGN: A community-based cross-sectional design. METHODS: We performed a cross-sectional study of 474 elderly men aged 60-74 years in two Japanese rural communities (Noichi in southwestern Japan and Ikawa in northeastern Japan). We examined the association between plasma concentrations of homocysteine and the maximum intima-media thickness (assessed by ultrasonography). RESULTS: The prevalence of thickening was 10.7% for the lowest tertile of homocysteine level and 21.1% for the highest tertile. For the subjects without hypertension, the odds ratio for having carotid intima-media thickening was 5.8; it was significantly higher for the highest tertile of homocysteine level than it was for the lowest after adjusting for age, hypercholesterolemia, hypoalphalipoproteinemia, diabetes, and smoking by using a multiple logistic regression model. However, its correlation was not evident for those with hypertension. CONCLUSIONS: High levels of plasma homocysteine are correlated to extracranial carotid artery atherosclerosis in elderly men without hypertension in Japanese rural communities.

Aged↗

PubMed1999

Fibrinolytic factors, serum lipid and C-reactive protein predicting cardiac events in Japanese patients with coronary atherosclerotic lesions.

Although disturbances of the fibrinolytic system and serum lipid, and the presence of inflammation, may be risk factors for coronary artery disease (CAD), few reports have investigated these relationships in Japanese patients. Data on 106 patients (79 men and 27 women, mean age 62.3 years) with atherosclerotic lesions on the coronary angiogram were evaluated prospectively to identify whether the factors were useful in predicting the risk of coronary events during a follow-up of 50+/-4 months. Of the 106 patients who were followed, 11 patients had coronary events (4 acute myocardial infarction and 7 unstable angina pectoris). In univariate Cox analyses, a high level of tissue-plasminogen activator (t-PA), apolipoprotein CII, C-reactive protein (CRP), and a low level of high-density lipoprotein-cholesterol (HDL-C) was each associated with a significant increase in the risk of future cardiac events. The stepwise model of Cox proportional hazards analysis selected only a high level of t-PA and CRP as predictors of cardiac events. Controlling for any risk factor did not lower the relation between t-PA and the risk of cardiac events, whereas the relative risk of cardiac events in CRP was not significant when controlled for HDL-C. Thus, in prospective data obtained from a cohort of Japanese patients with coronary atherosclerotic lesions, the elevation of t-PA was an independent predictor of subsequent cardiac events. The prognostic role of CRP in cardiac events was related to a low level of HDL-C.

Angina Pectoris↗

PubMed1999

Biological activities of lipopolysaccharides extracted from porcine vaccine strains.

Lipopolysaccharides (LPSs) were purified from Actinobacillus pleuropneumoniae serotype 2, Bordetella bronchiseptica and Haemophilus parasuis serotype 5, which were used for vaccine production in Japan, by the phenol-water procedure. In SDS-PAGE analysis, A. pleuropneumoniae LPS, as well as Escherichia coli LPS, demonstrated a typical ladder profile of a smooth-type LPS. On the other hand, B. bronchiseptica and H. parasuis LPSs lacked the ladder profiles. It was found that the biological activity of these LPSs was comparable to those of E. coli LPS in terms of activation of the clotting enzyme of Limulus amoebocyte lysate, mitogenic activity of mouse spleen cells, stimulation of TNF-alpha and nitric oxide production, but IL-6 production could hardly be observed in any LPS.

Actinobacillus Infections↗

PubMed1999

Posterior lumbar interbody fusion: a retrospective study of complications after facet joint excision and pedicle screw fixation in 148 cases.

We retrospectively evaluated neurological and other complications related to posterior lumbar interbody fusion (PLIF) performed by facet joint excision and pedicle screw fixation, in 148 consecutive patients with degenerative disorders. Their mean age at surgery was 59 (19-80) years. The mean follow-up period was 3 (2-6.5) years. Overall, 91 complications in 75 cases were observed. Although no permanent neural damage was detected, transient neural palsy occurred in 8% of the cases. Dural tear, partial misplacement, loosening, breakage of the pedicle screw and loss of correction were seen in 6, 6, 4, 1 and 1 of the cases, respectively. Deep infection of the fused segment developed in 2 cases. We conclude that PLIF, performed by facet joint excision and pedicle screw fixation, demonstrated a very low incidence of osteosynthesis failure, such as screw loosening, breakage and loss of correction. However, the high incidence of other complications, particularly neurological impairment, is still a disadvantage of this technically-demanding procedure.

Adult↗

PubMed1999

Sensitivity of shuttle vector plasmid pZ189 DNA to carbon ion beams.

The sensitivity of shuttle vector plasmid pZ189 DNA to carbon ion beams was studied under dry conditions. This plasmid contains the supF gene that can be used in mutagenesis analysis. The survival curve of the plasmid had both a shoulder and exponential parts, and showed a D10 value of about 17 kGy for both Escherichia coli wild-type and DNA repair-deficient mutant (UV-sensitive) strains. Therefore, it was assumed that the excision repair system was not effective for repairing DNA lesions induced by irradiation with carbon ion beams.

Carbon↗