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Biomedical subjects

A Tanaka

Publications and source records attributed to A Tanaka.

At least 289 records · Page 16Linked to original sources
PubMed2000

Stoichiometric analysis of barley plastid ribosomal proteins.

We analyzed the protein composition of plastid 70S ribosomes isolated from the stromal fractions of barley plastids by the radical-free and highly reducing method of two dimensional polyacrylamide gel electrophoresis (RFHR 2D-PAGE). Intactness of the ribosomes was confirmed by the poly(U)-directed phenylalanine polymerization activity and by the reassociation capacity of the subunits into 70S ribosomes. The small and large ribosomal subunits were composed of 23 and 36 proteins, respectively. In addition, one acidic protein associated with ribosomes in low salt buffer but released in high salt buffer was found. The plastid ribosomes contained relatively larger numbers of acidic proteins than prokaryotic ribosomes. Stoichiometric analysis revealed the presence of several ribosomal proteins in low copy numbers, indicating that the ribosomes of plastids were heterogeneous. We also investigated the protein composition of plastid ribosomes from greening barley leaves and found that it did not change during greening.

Centrifugation, Density Gradient↗
PubMed2000

Isolation of two different phenotypes of mycorrhizal mutants in the model legume plant Lotus japonicus after EMS-treatment.

Lotus japonicus has been proposed as a model plant for the molecular genetic study of plant-microbe interaction including Mesorhizobium loti and arbuscular mycorrhizal (AM) fungi. Non-mycorrhizal mutants of Lotus japonicus were screened from a collection of 12 mutants showing non-nodulating (Nod-), ineffectively nodulating (Fix-) and hypernodulating (Nod++) phenotypes with monogenic recessive inheritance induced by EMS (ethylmethane sulfonate) mutagenesis. Three mycorrhizal mutant lines showing highly reduced arbuscular mycorrhizal colonization were obtained. All of them were derived from Nod- phenotypes. In Ljsym72, the root colonization by Glomus sp. R-10 is characterized by poor development of the external mycelium, formation of extremely branched appressoria, and the blocking of hyphal penetration at the root epidermis. Neither arbuscules nor vesicles were formed in Ljsym72 roots. Fungal recognition on the root surface was strongly affected by the mutation in the LjSym72 gene. Unique characteristics in mutant lines Ljsym71-1 and Ljsym71-2 were the overproduction of deformed appressoria and arrested hyphal penetration of the exodermis. Small amounts of internal colonization including degenerated arbuscule formation occurred infrequently in these types of mutants. Not only fungal development on the root surface but also that in the root exodermis and cortex was affected by the mutation in LjSym71 gene. These mutants represent a key advance in molecular research on the AM symbiosis.

Ethyl Methanesulfonate↗
PubMed2000

Structural and functional complexity of the genomic region controlling AK-toxin biosynthesis and pathogenicity in the Japanese pear pathotype of Alternaria alternata.

The Japanese pear pathotype of Alternaria alternata produces host-specific AK-toxin and causes black spot of Japanese pear. Previously, a cosmid clone, pcAKT-1, was isolated that contains two genes, AKT1 and AKT2, within a 5.0-kb region required for AK-toxin biosynthesis. The wild-type strain has multiple, nonfunctional copies of these genes. In the present study, two additional genes, AKTR-1 and AKT3-1, downstream of AKT2 were identified. Transformation of the wild type with AKTR-1- and AKT3-1-targeting vectors produced toxin-deficient (Tox-), nonpathogenic mutants. DNA gel blot analysis, however, demonstrated that the fragments targeted in Tox- mutants were different from those containing AKTR-1 and AKT3-1 on the transforming vectors. A cosmid clone, pcAKT-2, containing the targeted DNA was isolated and shown to carry two genes, AKTR-2 and AKT3-2, with high similarity to AKTR-1 and AKT3-1, respectively. Transcripts from not only AKTR-2 and AKT3-2 but also AKTR-1 and AKT3-1 were found in the wild type. DNA gel blot analysis with pulsed-field gel electrophoresis showed that AKT1, AKT2, AKT3, and AKTR and their homologues are on a single chromosome. These results indicate the structural and functional complexity of the genomic region controlling AK-toxin biosynthesis.

Alternaria↗
PubMed2000

Usefulness of continuous oxygen insufflation into trachea for management of upper airway obstruction during anesthesia.

BACKGROUND: Severe complications associated with upper airway obstruction often occur during the perioperative period. Development of a simple and reliable technique for reversing the impaired airway patency may improve airway management. The purpose of the current study is to evaluate the usefulness of transtracheal oxygen insufflation (TTI) for management of upper airway obstruction during anesthesia and to explore the mechanisms of TTI in detail. METHODS: During propofol anesthesia in eight spontaneously breathing patients, the upper airway cross-sectional area and pressure-flow measurements during neck flexion with TTI were compared with those during triple airway maneuvers (TAM) without TTI. Blood gas analyses assessed efficacy of CO2 elimination during TTI in an additional nine patients. RESULTS: TTI achieved adequate PaCO2 and PaO2 levels equivalent to those during TAM. In addition to a significantly smaller cross-sectional area during TTI, the location and slope of the pressure-flow relation during TTI completely differed from those during TAM, indicating that upper airway resistance was much higher during TTI. Notably, minute ventilation during TTI was significantly smaller than that during TAM, suggesting reduced dead space or other mechanisms for CO2 elimination. CONCLUSIONS: TTI is capable of maintaining adequate blood gases through mechanisms different from those of conventional airway support in anesthetized subjects with upper airway obstruction.

Adult↗
PubMed2000

Application of artificial dermis graft to correct a depression after tissue resection.

The authors present 7 cases of artificial dermis implantation to correct a depression after tissue resection. Four of the seven cases resulted from resection of a malignant tumor (N = 3) and from a benign subcutaneous tumor (N = 1). The other 3 cases were the result of temporal muscle harvest to reconstruct facial palsy. In 1 patient a mild degree of bone deformity also existed. The pieces of artificial dermis employed varied from 35 x 40 to 40 x 80 mm in size. In 5 patients two sheets were implanted, and in 2 patients three sheets were implanted. In 2 patients the dermis sheets were covered by a pedicled temporal fascial flap with a free split-thickness skin graft because whole skin was resected as a result of a malignant skin tumor. There was no postoperative infection or allergic reaction in any of the patients. In all cases there was no postoperative contracture, and the implanted area was soft. An adequate or acceptable thickness of subcutaneous tissue was obtained. Artificial dermis may be a useful option as implantation material to correct a depression after tissue resection, especially for wide and comparatively shallow depressions.

Aged↗
PubMed2000

An evaluation of hard palate mucosa graft as a lining material in alar reconstruction: a 7-year experience applied to the full-thickness alar defect.

The authors present their experience with 25 hard palate mucosa grafts used as lining material in the reconstruction of full-thickness alar defects. Good "take" was obtained in 22 grafts; the other three grafts incurred necrosis of the overriding skin flaps and postoperative infection. Degree of shrinkage was 11 to 15 percent of grafted size in patients with the type of defect that did not include the alar margin; shrinkage was 26 to 35 percent in patients with the type that included more than 50 percent of the alar margin. In all patients who had a good graft take, the nasal cavities were maintained and there was no nasal obstruction or collapsing during strong breathing. The healing time of the palate donor site varied from 7 days to 5 weeks, depending on the size of the defect. No patients experienced any symptoms at the donor site after healing. The authors concluded that hard palate mucosa can be considered a useful material in alar reconstruction because of the ease in graft harvesting and its support features. When the defect is large enough to involve the total unilateral ala nasi, even though the degree of postoperative shrinkage is comparatively high, hard palate mucosa may be the most suitable material to ensure good take of the graft and less possibility of donor-site morbidity.

Adult↗
PubMed2000

Allelic loss of 14q and 22q, NF2 mutation, and genetic instability occur independently of c-kit mutation in gastrointestinal stromal tumor.

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. Since c-kit mutation occurs only in one-third of GIST, there might be other molecular mechanisms. Loss of heterozygosity (LOH), microsatellite instability (MSI) and NF2 gene mutation were investigated in 22 GISTs (9 low-risk and 13 high-risk tumors). LOH and MSI were evaluated using 41 markers on 21 chromosomal arms, and NF2 gene mutation was examined by PCR-SSCP. High frequency of LOH was observed on 14q (9 / 19, 47%), and 22q (17 / 22, 77%). The frequencies were similar in low-risk and high-risk tumors, and were unrelated with gastric or intestinal origin. Two other abnormalities, additional LOH on other chromosomes and MSI at more than two loci, were characteristic of the high-risk tumors (P < 0.05). NF2 gene mutation was identified in two cases showing 22q-LOH (8 bp deletion on the splice donor site of exon 7, and 1 bp insertion at position 432 of exon 4, which resulted in nonsense mutation). There was no significant correlation between these results and c-kit gene mutation, which was observed in 8 of 22 tumors. Suppressor genes on 14q and 22q may be involved, independently of c-kit gene mutation, in the development of GIST. NF2 contributes as a tumor suppressor in a small subset of GIST. These abnormalities are presumably followed by increased genetic instability.

Adult↗
PubMed2000

Inflammation and atherosclerosis. Atherosclerotic lesions in Takayasu arteritis.

Takayasu arteritis is a chronic vasculitis, mainly involving the aorta and its main branches as well as the coronary and pulmonary arteries, causing stenosis and/or obstruction due to thrombus formation or dilatation due to aneurysmal formation and/or rupture of the involved arteries. These characteristic anomalies resulted from ischemia of retinal arteries due to the obstruction of cervical vessels. In Western countries this disease is also known as "pulseless disease," because the pulse is frequently absent due to the obstruction of subclavian or branchial arteries. The pathogenesis of this morbid condition is still unknown. Epidemiologically, it is found mostly in female patients and is more prevalent in Asian and Latin American countries. Affected areas consist of a mixture of both active, productive inflammatory lesions, and old fibrous lesions. Autoimmune processes stimulated by viral infection and other unknown causative factors may play an important role under these pathophysiological conditions because HLA analysis revealed a statistically significant high frequency of haplotype A24-B52-DR2 in these patients in Japan. Documentation of atherosclerotic complications in young female patients with Takayasu arteritis who are generally free from traditional atherosclerosis risk factors may be clinical evidence that inflammation is indeed an important risk factor in atherogenesis.

Arteries↗
PubMed2000

Screening of genes involved in isooctane tolerance in Saccharomyces cerevisiae by using mRNA differential display.

A Saccharomyces cerevisiae strain, KK-211, isolated by the long-term bioprocess of stereoselective reduction in isooctane, showed extremely high tolerance to the solvent, which is toxic to yeast cells, but, in comparison with its wild-type parent, DY-1, showed low tolerance to hydrophilic organic solvents, such as dimethyl sulfoxide and ethanol. In order to detect the isooctane tolerance-associated genes, mRNA differential display (DD) was employed using mRNAs isolated from strains DY-1 and KK-211 cultivated without isooctane, and from strain KK-211 cultivated with isooctane. Thirty genes were identified as being differentially expressed in these three types of cells and were classified into three groups according to their expression patterns. These patterns were further confirmed and quantified by Northern blot analysis. On the DD fingerprints, the expression of 14 genes, including MUQ1, PRY2, HAC1, AGT1, GAC1, and ICT1 (YLR099c) was induced, while the expression of the remaining 16 genes, including JEN1, PRY1, PRY3, and KRE1, was decreased, in strain KK-211 cultivated with isooctane. The genes represented by HAC1, PRY1, and ICT1 have been reported to be associated with cell stress, and AGT1 and GAC1 have been reported to be involved in the uptake of trehalose and the production of glycogen, respectively. MUQ1 and KRE1, encoding proteins associated with cell surface maintenance, were also detected. Based on these results, we concluded that alteration of expression levels of multiple genes, not of a single gene, might be the critical determinant for isooctane tolerance in strain KK-211.

Blotting, Northern↗
PubMed2000

An n-alkane-responsive promoter element found in the gene encoding the peroxisomal protein of Candida tropicalis does not contain a C(6) zinc cluster DNA-binding motif.

When an asporogenic diploid yeast, Candida tropicalis, is cultivated on n-alkane, the expression of the genes encoding enzymes of the peroxisomal beta-oxidation pathway is highly induced. An upstream activation sequence (UAS) which can induce transcription in response to n-alkane (UAS(ALK)) was identified on the promoter region of the peroxisomal 3-ketoacyl coenzyme A (CoA) thiolase gene of C. tropicalis (CT-T3A). The 29-bp region (from -289 to -261) present upstream of the TATA sequence was sufficient to induce n-alkane-dependent expression of a reporter gene. Besides n-alkane, UAS(ALK)-dependent gene expression also occurred in the cells grown on oleic acid. Several kinds of mutant UAS(ALK) were constructed and tested for their UAS activity. It was clarified that the important nucleotides for UAS(ALK) activity were located within 10-bp region from -273 to -264 (5'-TCCTGCACAC-3'). This region did not contain a CGG triplet and therefore differed from the sequence of the oleate-response element (ORE), which is a UAS found on the promoter region of 3-ketoacyl-CoA thiolase gene of Saccharomyces cerevisiae. Similar sequences to UAS(ALK) were also found on several peroxisomal enzyme-encoding genes of C. tropicalis.

Acetyl-CoA C-Acyltransferase↗
PubMed2000

Protective effect of lafutidine against indomethacin-induced intestinal ulceration in rats: relation to capsaicin-sensitive sensory neurons.

BACKGROUND/AIM: We examined the prophylactic effect of lafutidine, a novel histamine H(2)-receptor antagonist [(+/-)-2-(furfurylsulfinyl)-N-[4-[4-(piperidinomethyl)-2-pyr idyl]oxy- (Z)-2 butenyl]acetamide], on indomethacin-induced small intestinal ulcers in rats and investigated the relation of this action to capsaicin-sensitive sensory neurons. METHODS AND RESULTS: Subcutaneously administered indomethacin (10 mg/kg) provoked ulceration in the small intestine, mainly the jejunum and ileum, accompanied by increases in myeloperoxidase (MPO) and inducible nitric oxide synthase (iNOS) activities as well as the enterobacterial numbers invading the mucosa. Intestinal ulcerogenic response to indomethacin was prevented by 16,16-dimethyl prostaglandin E(2) (10 microg/kg, p.o.) and capsaicin (10 mg/kg, p.o. ) as well as ampicillin (800 mg/kg, p.o.), but not omeprazole (100 mg/kg, p.o.). Likewise, lafutidine (1-10 mg/kg, p.o.), but not cimetidine (100 mg/kg, p.o.), reduced the occurrence of intestinal ulcers in response to indomethacin in a dose-dependent manner, and a significant effect was observed at 3 mg/kg or greater. The protective action of lafutidine as well as capsaicin was almost totally abolished by chemical ablation of capsaicin-sensitive sensory neurons. Both lafutidine and capsaicin significantly suppressed the increases in MPO and iNOS activities as well as enterobacterial numbers in the mucosa. These agents also significantly enhanced mucus secretion in the small intestine. CONCLUSION: These results suggest that lafutidine protects the small intestine against ulceration via stimulation of capsaicin-sensitive sensory neurons. This action may be attributable to inhibition of enterobacterial invasion in the intestinal mucosa, probably by increasing the mucus secretion.

16,16-Dimethylprostaglandin E2↗
PubMed2000

Developmental changes in collapsibility of the passive pharynx during infancy.

The upper airway configuration significantly changes during the first year of life in humans, possibly leading to alteration of collapsibility of the pharyngeal airway. The present study evaluated developmental changes of passive pharyngeal mechanics in nine normal infants ranging in age from 2 to 12 mo. The static pressure-area relationship of the passive pharynx was quantified under general anesthesia with complete paralysis. We found a direct association between age and maximal velopharyngeal area (r = 0.840, p = 0.005). Velopharyngeal closing pressure progressively decreased with increasing age (r = -0.809, p = 0.008) and the closing pressures were below atmospheric pressure in all infants (range: -0.7 to -9.8 cm H(2)O; mean +/- SD: -3.6 +/- 2.7 cm H(2)O). Shape of the pressure-area curves became steeper in slope with maturation, indicating increased pharyngeal wall stiffness during development. Accordingly, we conclude that anatomic properties of the pharynx gain stability in favor of maintaining patent airway during development in normal infants.

Airway Resistance↗
PubMed2000

Activation and transforming growth factor-beta production in eosinophils by hyaluronan.

To investigate whether extracellular matrix glycosaminoglycan hyaluronan (HA) modulates eosinophil activation and transforming growth factor (TGF)-beta production by eosinophils, human peripheral blood eosinophils (purity > 99%) from 12 patients with mild to moderate asthma or six healthy subjects were isolated and incubated with increasing concentrations of low molecular weight (mol wt) HA ( approximately 0.2 x 10(6) D) or high mol wt HA (3.0 to approximately 5.8 x 10(6) D). We found that the low mol wt HA has a pronounced effect on eosinophil survival in both patients with asthma and healthy subjects in a dose-dependent fashion on Days 2 and 4. Whereas the high mol wt HA had a smaller effect on eosinophil survival than did the low mol wt HA. The HA-mediated eosinophil survival was partially but significantly inhibited ( approximately 50% inhibition) by a blocking monoclonal antibody for CD44, a specific receptor of HA, and largely inhibited by an anti-granulocyte macrophage colony-stimulating factor (GM-CSF) neutralizing antibody but not by an anti-interleukin (IL)-3 or anti-IL-5 neutralizing antibody. In addition, the low mol wt HA increased GM-CSF messenger RNA (mRNA) expression and protein secretion by eosinophils in a dose-dependent fashion, suggesting that the HA-mediated eosinophil survival is due mainly to induction of GM-CSF release through partial CD44 signaling. Furthermore, we demonstrated that the low mol wt HA results in morphologic changes in eosinophils such as transforming from a round to a spindle shape and in homotypic aggregation, upregulates intercellular adhesion molecule-1 expression, and increases TGF-beta mRNA expression and protein secretion by eosinophils. These observations suggest previously unforeseen interactions between eosinophils and low mol wt extracellular matrix and, thus, novel pathways by which eosinophils may contribute to the regulation of airway inflammation and airway remodeling.

Asthma↗
PubMed2000

Relationship between hyperinsulinemia and remnant lipoprotein concentrations in patients with impaired glucose tolerance.

This study was performed to explore further the association between insulin resistance and plasma remnant lipoprotein (RLP) concentration. For this purpose we used the sum of the plasma insulin concentrations before and 30, 60, 90, 120, and 180 min after a 75-g oral glucose load (sigmaIRI) as a surrogate measure of insulin resistance in 61 subjects with impaired glucose tolerance. SigmaIRI was determined on 2 occasions, before and 16 weeks after initiation of a diet and exercise program. At baseline, sigmaIRI correlated with the sum of the plasma glucose concentrations in response to the 75-g oral glucose load (r = 0.26; P < 0.04) as well as plasma concentrations of triglyceride (r = 0.21; P = 0.09), RLP-cholesterol (r = 0.41; P < 0.001), and RLP-triglyceride (r = 0.46; P < 0.001). In contrast, neither total (r = 0.07) nor high density lipoprotein (HDL) cholesterol (r = 0.04) concentrations correlated with sigmaIRI. SigmaIRI was lower in 42 subjects following life-style intervention, associated with significant (P < 0.005) reductions in sigmaglucose, and fasting glucose, insulin, triglyceride, RLP-cholesterol, and RLP-triglyceride concentrations. However, none of these variables decreased in the 19 subjects whose sigmaIRI did not fall. Finally, the change in sigmaIRI following intervention with diet and exercise was significantly associated with differences in sigmaglucose (r = 0.63; P < 0.001) and fasting glucose (r = 0.26; P < 0.05), insulin (r = 0.79; P < 0.001), triglyceride (r = 0.29; P < 0.03), RLP-cholesterol (r = 0.71; P < 0.001), and RLP-triglyceride (r = 0.49; P < 0.001) concentrations. These results demonstrate that variations in concentrations of RLPs are highly correlated with changes in sigmaIRI, consistent with the possibilities that 1) RLP measurements are useful estimates of insulin resistance; and 2) an increase in RLP concentrations may provide the mechanistic link between insulin resistance and coronary heart disease.

Aged↗
PubMed2000

Highly potent and orally active non-peptide arginine vasopressin antagonists for both V1A and V2 receptors: synthesis and pharmacological properties of 4'-[(4,4-difluoro-5-methylidene-2,3,4,5-tetrahydro-1H-1-benzoazepin-1-y l)carbonyl]-2-phenylbenzanilide derivatives.

A series of compounds structurally related to 4'-[(4,4-difluoro-5-methylidene-2,3,4,5-tetrahydro-1H-1-benzoaz epin-1-yl) carbonyl]-2-phenylbenzanilide were synthesized and evaluated for arginine vasopressin (AVP) antagonistic activity. Compounds with a (Z)-olefin geometry at the 5-position of benzoazepine possessed potent affinity for both the V1A and V2 receptors. Further study has shown that one of these derivatives, (Z)-4'-(¿4,4-difluoro-5-[(4-dimethylaminopiperidino)carbonylmet hylene]-2,3,4,5-tetrahydro-1H-1-benzoazepin-1-yI¿carbonyl)2- phenylbenzanilide monohydrochloride (29, YM-35471), exhibits exceptionally potent affinity for both of V1A and V2 receptors, even when administered orally. The synthesis and pharmacological properties of this compound are detailed in this paper.

Anilides↗