Biomedical subjects

T Noguchi

Publications and source records attributed to T Noguchi.

At least 163 records · Page 9Linked to original sources

PubMed2000

Paralytic toxins in a ribbon worm Cephalothrix species (Nemertean) adherent to cultured oysters in Hiroshima Bay, Hiroshima Prefecture, Japan.

In 1998, during the surveillance of the toxicity of various marine fouling organisms in Hiroshima Bay, Hiroshima Prefecture, Japan, specimens of the ribbon worm, "himomushi" Cephalothrix sp. (Nemertean) adherent to the shells of cultured oysters hanging onto floating culture rafts were found to contain toxins which showed strong paralytic action in mice throughout the survey period, February to May. The maximum toxicity (as tetrodotoxin, TTX) was 14,734 MU/g whole body. Attempts were made to identify the paralytic toxins in this worm. The "himomushi" toxin (HMT) was extracted from the worm with 80% methanol acidified with acetic acid and the extract defatted with dichloromethane. The aqueous layer was chromatographed on activated charcoal and the unbound and bound toxic fractions were analyzed by high-performance liquid chromatography and gas chromatography-mass spectrometry. It was rather unexpectedly revealed from these results that HMT was comprised of TTX, 4-epiTTX, anhydroTTX and three unidentified toxins. To our knowledge, this is the first report of the occurrence of toxic organisms, containing a high concentration of TTX, adherent to cultured bivalves such as oysters.

Animals↗

PubMed2000

Synthesis and biological evaluations of C-23-modified 26,26,26,27,27,27-F6-vitamin D3 analogues.

A convenient synthetic method which could allow flexible modification at C-23 of 26,26,26,27,27,27-hexafluoro-1alpha,25-dihydroxyvitamin D3 (3) has been developed. An effective construction of hexafluoroacetone (HFA) aldol part on the side chain of 10 was achieved by aldol reaction with HFA gas. This route is also attractive as an approach to diverse 26,27-modified vitamin D3 analogues. The preliminary biological activities of 23-modifed 26,27-F6 vitamin D3 analogues are evaluated. The potency of VDR affinities of the C-23-substituted analogues (keto group (4); OH group (5a,5b); fluorine atom (6a,6b); and oxetane ring (7a,7b)) was found to vary depending upon both the nature and stereochemistry of the substituents. In contrast, the HL-60 cell differentiation property was less varied than VDR affinity, and depended upon the nature rather than the stereochemistry of the substituents.

Acetone↗

PubMed2000

An FTIR study on the structure of the oxygen-evolving Mn-cluster of Photosystem II in different spin forms of the S(2) state.

The S(2) state of the oxygen-evolving Mn-cluster of Photosystem II (PS II) is known to have different forms that exhibit the g =2 multiline and g = 4.1 EPR signals. These two spin forms are interconvertible at > 200 K and the relative amplitudes of the two signals are dependent on the species of cryoprotectant and alcohol contained in the medium. Also, it was recently found that the mutiline form can be converted to the g = 4.1 form by absorption of near-infrared light by the Mn-cluster itself at around 150 K [Boussac et al. (1996) Biochemistry 35: 6984-6989]. We have used light-induced Fourier transform infrared (FTIR) difference spectroscopy to study the structural difference in these two S(2) forms. FTIR difference spectra for S(2)/S(1) as well as for S(2)Q(A) (-)/S(1)Q(A) measured at cryogenic temperatures using PS II membranes in the presence of various cryoprotectants, and monohydric alcohols did not show any specific differences except for intensities of amide I bands, which were larger when ethylene glycol or glycerol was present in addition to sucrose. This result was interpreted due to more flexible movement of the protein backbones upon S(2) formation with a higher cryoprotectant content. Light-induced difference spectra measured at 150 K using either blue light without near-infrared light or red plus near-infrared light also did not show any detectable difference. In addition, a different spectrum upon near-infrared illumination at 150 K of the PS II sample in which the S(2) state had been photogenerated at 200 K exhibited no meaningful signals. These results indicate that the two S(2) forms that give rise to the multiline and g = 4.1 signals have only minor differences, if any, in the structures of amino-acid ligands and polypeptide backbones. This conclusion suggests that conversion between the two spin states is caused by a spin-state transition in the Mn(III) ion rather than valence swapping within the Mn-cluster that would considerably affect the vibrations of ligands.

Journal Article↗

PubMed2000

Effect of ephedrine on auditory-evoked potentials during light general anaesthesia.

Ephedrine, a sympathomimetic drug, may stimulate the central nervous system via its amphetamine-like effect under light general anaesthesia. We compared the effect of ephedrine on auditory-evoked potentials with that of etilefrine, a sympathomimetic drug that lacks an amphetamine-like effect, in patients undergoing abdominal surgery under general anaesthesia with 67% nitrous oxide in oxygen and epidural blockade. Ephedrine (0.08 mg x kg-1 intravenously) significantly decreased the latencies of Nb and P1 from 49.5 (4.2) [mean (SD)] and 63.9 (9.1) ms to 45.9 (4.2) and 59.0 (9.9) ms, respectively; whereas etilefrine (0.02 mg x kg-1 intravenously) caused no significant changes in these potentials. In addition, the latencies of Nb and P1 before drug administration were positively correlated with patient age. These findings suggest that ephedrine can cause excitation of the central nervous system during light general anaesthesia, and that auditory-evoked potentials may be a sensitive indicator of the depth of anaesthesia.

Adult↗

PubMed2000

Lesions in the sterol delta reductase gene of Arabidopsis cause dwarfism due to a block in brassinosteroid biosynthesis.

The brassinosteroid (BR) biosynthetic pathway, and the sterol pathway which is prerequisite to the BR pathway, are rapidly being characterized because of the availability of a large number of characteristic dwarf mutants in Arabidopsis. Here we show that the Arabidopsis dwarf5 mutants are disrupted in a sterol Delta7 reduction step. dwf5 plants display the characteristic dwarf phenotype typical of other BR mutants. This phenotype includes small, round, dark-green leaves, and short stems, pedicels, and petioles. Metabolite tracing with 13C-labeled precursors in dwf5 verified a deficiency in a sterol Delta7 reductase activity. All six independent alleles contain loss-of-function mutations in the sterol Delta7 reductase gene. These include a putative mRNA instability mutation in dwf5-1, 3' and 5' splice-site mutations in dwf5-2 and dwf5-6, respectively, premature stop codons in dwf5-3 (R400Z) and dwf5-5 (R409Z), and a mis-sense mutation in dwf5-4 (D257N). The dwf5 plant could be restored to wild type by ectopic overexpression of the wild-type copy of the gene. Both the Arabidopsis dwf5 phenotype and the human Smith-Lemli-Opitz syndrome are caused by loss-of-function mutations in a sterol Delta7 reductase gene, indicating that it is required for the proper growth and development of these two organisms.

Alleles↗

PubMed2000

Engineering analysis of diamond-like carbon coated polymeric materials for biomedical applications.

Diamond-like carbon (DLC) films have received much attention recently owing to their properties, which are similar to diamond: hardness, thermal conductivity, corrosion resistance against chemicals, abrasion resistance, good biocompatibility, and uniform flat surface. Furthermore, DLC films can be deposited easily on many substrates for wide area coat at room temperature. DLC films were developed for applications as biomedical materials in blood contacting-devices (e.g., rotary blood pump) and showed good biocompatibility for these applications. In this study, we investigated the surface roughness by Atomic Force Microscopy (AFM) and Hi-vision camera, SEM for surface imaging. The DLC films were produced by radio frequency glow discharge plasma decomposed of hydrocarbon gas at room temperature and low pressure (53 Pa) on several kinds of polycarbonate substrates. For the evaluation of the relation between deposition rate and platelet adhesion that we investigated in a previous study, DLC films were deposited at the same methane pressure for several deposition times, and film thickness was investigated. In addition, the deposition rate of DLC films on polymeric substrates is similar to the deposition rate of those deposited on Si substrates. There were no significant differences in substrates' surface roughness that were coated by DLC films in different deposition rates (16-40 nm). The surface energy and the contact angle of the DLC films were investigated. The chemical bond of DLC films also was evaluated. The evaluation of surface properties by many methods and measurements and the relationship between the platelet adhesion and film thickness is discussed. Finally, the presented DLC films appear to be promising candidates for biomedical applications and merit investigation.

Anticoagulants↗

PubMed2000

A randomised controlled trial of Prostar Plus for haemostasis in patients after coronary angioplasty.

OBJECTIVES: to clarify the efficacy and safety of Prostar Plus, a new percutaneous vascular surgical device (PVS) for vascular haemostasis. DESIGN: prospective randomised controlled trial. METHODS: a consecutive series of 60 patients were randomised to either PVS (n =30) or conventional manual compression ( n =30) following coronary angioplasty or stenting with femoral access using an 8-F sheath. RESULTS: PVS significantly shortened the time to haemostasis (10 s.d. 3 vs. 27 s.d. 9 min, p <0.001), ambulation (2.2 s.d. 0.9 vs. 11.0 s.d. 1.4 h, p <0.001), and discharge (2.2 s.d. 0.4 vs. 3.1 s.d. 0.7 days, p <0.01), compared with the manual compression group with no major complications. PVS also increased patient comfort assessed by using a visual-analogue scale method. Although these clinical benefits reduced the hospital cost ($1301 s. d. 248 vs. 1613 s.d. 460, p <0.05), the cost of the PVS device (approximately $350) cancelled the cost-saving benefit. CONCLUSIONS: this randomised study indicates that Prostar Plus is safe, more effective and comfortable than conventional manual compression.

Angioplasty, Balloon, Coronary↗

PubMed2000

Immunohistochemical detection of membrane-type-1-matrix metalloproteinase in colorectal carcinoma.

We investigated whether the expression of membrane-type-1 matrix metalloproteinase (MT1-MMP), matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-2 (TIMP-2) was consistent with the proposed roles of these proteins in promoting metastasis in colorectal cancer. The expression of MT1-MMP was significantly more frequent in deeply invasive carcinomas (P = 0.007) and in cases of vascular invasion (P = 0.02). The frequency of detection of MMP-2 in the stroma was much greater in vascular invasion-positive cases (42%) than in negative cases (20%; P = 0.02). The rate of detection of TIMP-2 in tumour cell cytoplasm increased with the depth of invasion (P = 0.03). TIMP-2 in the stroma was found more frequently in tumours with lymphatic invasion and lymph node metastasis (P < 0.05). Significant correlations were found between detection of MT1-MMP and MMP-2 in tumour cell cytoplasm (P < 0.05), of MT1-MMP and TIMP-2 in tumour cell cytoplasm (P < 0.01), and of MMP-2 and TIMP-2 in tumour cell cytoplasm (P < 0.01). Immunohistochemical detection of MT1-MMP and TIMP-2 might be useful for monitoring infiltration in colorectal carcinoma but is not correlated with distant metastases.

Adenocarcinoma↗

PubMed2000

Cytoskeleton mediating transport between the ER system and the Golgi apparatus in the green alga Scenedesmus acutus.

In the green alga Scenedesmus acutus, Golgi bodies are located near the nucleus and supplied with transition vesicles that bud from the outer nuclear envelope membrane. Using this alga, we have shown previously that thiamine pyrophosphatase (TPPase), a marker enzyme of Golgi bodies, migrates in vesicles from the Golgi bodies to the ER via the nuclear envelope in the presence of BFA (Noguchi et al., Protoplasma 201, 202-212, 1998). In this study we demonstrate that both cytochalasin B and oryzalin (microtubule-disrupting agent) inhibit the BFA-induced migration of TPPase from Golgi bodies to the nuclear envelope. However, only actin filaments--not microtubules--can be detected between the nuclear envelope and the Golgi bodies in both BFA-treated and untreated cells. These observations suggest that actin filaments mediate the BFA-induced retrograde transport of vesicles. This mechanism differs from that found in mammalian cells, in which microtubules mediate BFA-induced retrograde transport by the elongation of membrane tubules from the Golgi cisternae. We also discuss the non-participation of the cytoskeleton in anterograde transport from the nuclear envelope to the Golgi bodies.

Antifungal Agents↗

PubMed2000

Protein nutrition and insulin-like growth factor system.

Protein metabolism of growing animals is greatly affected by quantity and nutritional quality of dietary proteins. When animals are fed diets that contain enough proteins of good nutritional quality, they grow well. However, if they are fed diets deficient in protein or in some essential amino acids, their growth rate is markedly depressed. In this paper, we review the response of plasma insulin-like growth factor-I (IGF-I) to quantity and nutritional quality of dietary proteins. The sound correlation between plasma IGF-I concentration and the gain or loss of body proteins under various nutritional conditions suggests that the plasma IGF-I most possibly regulates the growth rate of animals or the rate of whole body protein synthesis. The quantity and nutritional quality of dietary proteins also regulates plasma concentration of IGF-binding proteins (IGFBPs). The changes in plasma concentration of IGFBPs presumably modifies the activity of IGF-I to regulate whole body protein synthesis. Molecular mechanisms of the changes in plasma concentrations of IGF-I and IGFBPs as affected by dietary proteins are also reviewed.

Animals↗

PubMed2000

A global platelet test of thrombosis and thrombolysis detects a prothrombotic state in some patients with non-insulin dependent diabetes and in some patients with stroke.

Platelet aggregation and spontaneous thrombolytic activity were assessed in patients with non-insulin dependent diabetes and stroke using a shear-induced and agonist-induced platelet aggregation test. The Thrombotic Status Analyser (TSA), induces platelet-rich thrombus formation solely by shear forces, while whole blood platelet aggregometry measures platelet reactivity to different agonists. These tests were employed in the present study because in earlier studies they both demonstrated that platelet aggregability in healthy volunteers was unchanged with age. On the other hand, it is known that thrombolytic activity decreases with age in males, but not in females. In diabetic patients shear-induced platelet aggregability varied according to the stage of nephropathy but platelet aggregation to collagen was suppressed at all stages. Platelet reaction to shear stress was enhanced in stroke patients with haemorrhagic episodes but not in patients with lacunar infarction. In contrast, platelet reactivity to collagen was suppressed and changes in ADP-induced platelet aggregability were inconsistent. Suppressed thrombolysis was observed only in diabetes with minor renal defect. Fibrinogen was increased in diabetes with stage III and IV nephropathy. Fibrinopeptide A (FPA) and D-dimer were increased in stroke. Thus, the observed increase in fibrinogen, FPA and D-dimer is inconsistent with changes in platelet aggregability. Our present findings suggest that a shear-induced platelet aggregation test is superior to other tests such as agonist-induced platelet aggregation and thrombotic markers such as fibrinogen, FPA and D-dimer in detecting a prothrombotic state. It is concluded that elderly males may have a prothrombotic state not because of platelet hyper-aggregability but because of suppressed thrombolytic activity. On the other hand, a prothrombotic state in patients with non-insulin dependent diabetes and after stroke may be due to changes in age-independent platelet aggregability.

Adult↗

PubMed2000

Quick selection of representative protein chain sets based on customizable requirements.

MOTIVATION: Protein structure classification has been recognized as one of the most important research issues in protein structure analysis. A substantial number of methods for the classification have been proposed, and several databases have been constructed using these methods. Since some proteins with very similar sequences may exhibit structural diversities, we have proposed PDB-REPRDB: a database of representative protein chains from the Protein Data Bank (PDB), which strategy of selection is based not only on sequence similarity but also on structural similarity. Forty-eight representative sets whose similarity criteria were predetermined were made available over the World Wide Web (WWW). However, the sets were insufficient in number to satisfy users researching protein structures by various methods. RESULT: We have improved the system for PDB-REPRDB so that the user may obtain a quick selection of representative chains from PDB. The selection of representative chains can be dynamically configured according to the user's requirement. The WWW interface provides a large degree of freedom in setting parameters, such as cut-off scores of sequence and structural similarity. This paper describes the method we use to classify chains and select the representatives in the system. We also describe the interface used to set the parameters.

Databases, Factual↗

PubMed2000

Dietary restriction of single essential amino acids reduces plasma insulin-like growth factor-I (IGF-I) but does not affect plasma IGF-binding protein-1 in rats.

The effects of dietary restriction of a single essential amino acid (EAA) on insulin-like growth factor-I (IGF-I) and IGF-binding protein (IGFBP)-1 were investigated in rats. Rats were fed experimental diets containing amino acid (AA) mixtures in which the concentrations of all EAA were at levels recommended by the National Research Council (control), in which a single EAA was restricted to 20% of that of the control diets (Leu(-), Lys(-), Met(-) or Thr(-)), or in which the diet was devoid of amino acids (AA(-)). To eliminate the effect of differences in energy intake, rats were fed the mean amount of food as consumed by the AA(-) group on the previous day. Growth was significantly retarded in rats fed diets restricted in just one EAA compared with that of rats fed the control diet, and further growth retardation was observed in rats fed the AA(-) diet. On the other hand, the plasma IGF-I concentrations in the groups with a single EAA restriction or in the AA(-) group were 66% (P: < 0. 05) and 50% (P: < 0.05) of that of the control group, respectively. The effect of any single EAA restriction was not significantly different from that of total AA deprivation. The plasma IGFBP-1 concentration in the control group did not differ from that of rats fed diets with the single EAA restrictions except for methionine restriction, but it was approximately 6-fold greater in the AA(-) group. Differences in plasma IGFBP-1 concentration under these conditions could be explained by differences in hepatic IGFBP-1 mRNA contents. Based on these results, we conclude that restriction of single EAA does not affect IGFBP-1 synthesis in vivo, although the deprivation of a single EAA has been reported to increase IGFBP-1 production in hepatocyte cultures. Our results also indicated that a single EAA restriction decreased IGF-I production but did not affect IGFBP-1 production. The present study suggests that not only plasma IGF-I, but also IGFBP-1, affects the magnitude of growth retardation in vivo.

Amino Acids, Essential↗

PubMed2000

A putative role for the tomato genes DUMPY and CURL-3 in brassinosteroid biosynthesis and response.

The dumpy (dpy) mutant of tomato (Lycopersicon esculentum Mill.) exhibits short stature, reduced axillary branching, and altered leaf morphology. Application of brassinolide and castasterone rescued the dpy phenotype, as did C-23-hydroxylated, 6-deoxo intermediates of brassinolide biosynthesis. The brassinolide precursors campesterol, campestanol, and 6-deoxocathasterone failed to rescue, suggesting that dpy may be affected in the conversion of 6-deoxocathasterone to 6-deoxoteasterone, similar to the Arabidopsis constitutive photomorphogenesis and dwarfism (cpd) mutant. Measurements of endogenous brassinosteroid levels by gas chromatography-mass spectrometry were consistent with this hypothesis. To examine brassinosteroid-regulated gene expression in dpy, we performed cDNA subtractive hybridization and isolated a novel xyloglucan endotransglycosylase that is regulated by brassinosteroid treatment. The curl-3 (cu-3) mutant (Lycopersicon pimpinellifolium ¿Jusl. Mill.) shows extreme dwarfism, altered leaf morphology, de-etiolation, and reduced fertility, all strikingly similar to the Arabidopsis mutant brassinosteroid insensitive 1 (bri1). Primary root elongation of wild-type L. pimpinellifolium seedlings was strongly inhibited by brassinosteroid application, while cu-3 mutant roots were able to elongate at the same brassinosteroid concentration. Moreover, cu-3 mutants retained sensitivity to indole-3-acetic acid, cytokinins, gibberellin, and abscisic acid while showing hypersensitivity to 2, 4-dichlorophenoxyacetic acid in the root elongation assay. The cu-3 root response to hormones, coupled with its bri1-like phenotype, suggests that cu-3 may also be brassinosteroid insensitive.

Amino Acid Sequence↗

PubMed2000

Biosynthetic pathways of brassinolide in Arabidopsis.

Our previous studies on the endogenous brassinosteroids (BRs) in Arabidopsis have provided suggestive evidence for the operation of the early C6-oxidation and the late C6-oxidation pathways, leading to brassinolide (BL) in Arabidopsis. However, to date the in vivo operation of these pathways has not been fully confirmed in this species. This paper describes metabolic studies using deuterium-labeled BRs in wild-type and BR-insensitive mutant (bri1) seedlings to establish the intermediates of the biosynthetic pathway of BL in Arabidopsis. The first evidence for the conversion of campestanol to 6-deoxocathasterone and the conversion of 6-deoxocathasterone to 6-deoxoteasterone is provided. The later biosynthetic steps (6-deoxoteasterone --> 3-dehydro-6-deoxoteasterone --> 6-deoxotyphasterol --> 6-deoxocastasterone --> 6alpha-hydroxycastasterone --> castasterone --> BL) were demonstrated by stepwise metabolic experiments. Therefore, these studies complete the documentation of the late C6-oxidation pathway. The biosynthetic sequence involved in the early C6-oxidation pathway (teasterone --> 3-dehydroteasterone --> typhasterol --> castasterone --> BL) was also demonstrated. These results show that both the early and late C6-oxidation pathways are functional in Arabidopsis. In addition we report two new observations: the presence of a new branch in the pathway, C6 oxidation of 6-deoxotyphasterol to typhasterol, and increased metabolic flow in BR-insensitive mutants.

Arabidopsis↗

PubMed2000

Loss of function of a rice brassinosteroid insensitive1 homolog prevents internode elongation and bending of the lamina joint.

Brassinosteroids (BRs) are plant growth-promoting natural products required for plant growth and development. Physiological studies have demonstrated that exogenous BR, alone or in combination with auxin, enhance bending of the lamina joint of rice. However, little is known about the function of endogenous BR in rice or other grass species. We report here the phenotypical and molecular characterization of a rice dwarf mutant, d61, that is less sensitive to BR compared to the wild type. We cloned a rice gene, OsBRI1, with extensive sequence similarity to that of the Arabidopsis BRI gene, which encodes a putative BR receptor kinase. Linkage analysis showed that the OsBRI1 gene is closely linked to the d61 locus. Single nucleotide substitutions found at different sites of the d61 alleles would give rise to amino acid changes in the corresponding polypeptides. Furthermore, introduction of the entire OsBRI1 coding region, including the 5' and 3' flanking sequences, into d61 plants complemented the mutation to display the wild-type phenotype. Transgenic plants carrying the antisense strand of the OsBRI1 transcript showed similar or even more severe phenotypes than those of the d61 mutants. Our results show that OsBRI1 functions in various growth and developmental processes in rice, including (1) internode elongation, by inducing the formation of the intercalary meristem and the longitudinal elongation of internode cells; (2) bending of the lamina joint; and (3) skotomorphogenesis.

Amino Acid Sequence↗

PubMed2000

Identification of a two-component signal transduction system involved in fimbriation of Porphyromonas gingivalis.

Porphyromonas gingivalis, a periodontopathogen, is an oral anaerobic gram-negative bacterium with numerous fimbriae on the cell surface. Fimbriae have been considered to be an important virulence factor in this organism. We analyzed the genomic DNA of transposon-induced, fimbria-deficient mutants derived from ATCC 33277 and found that seven independent mutants had transposon insertions within the same restriction fragment. Cloning and sequencing of the disrupted region from one of the mutants revealed two adjacent open reading frames (ORFs) which seemed to encode a two-component signal transduction system. We also found that six of the mutants had insertions in a gene, fimS, a homologue of the genes encoding sensor kinase, and that the insertion in the remaining one disrupted the gene immediately downstream, fimR, a homologue of the response regulator genes in other bacteria. These findings suggest that this two-component regulatory system is involved in fimbriation of P. gingivalis.

Amino Acid Sequence↗

PubMed2000

[Japanese spotted fever complicated by acute respiratory failure].

A 66-year-old male was admitted to our hospital, presenting a high fever and generalized erythema on June 9, 1999. Physical examination revealed many eschars on his legs. Laboratory examinations were as follows: platelet counts, 5.5 x 10(4)/microliter: FDP, 25 micrograms/ml: TAT, 70.9 ng/ml: GOT, 177 IU/l, GPT, 174 IU/l: CRP, 32.3 mg/dl. Based on these findings, he was diagnosed as having rickettsiosis with DIC, and minocycline (200 mg/day) and heparin were started immediately, but had no clinical effect for 3 days. Blood gas analysis showed severe hypoxia and the chest CT scan revealed increased CT value in all lung fields with reticular shadows in the lower fields and pleural effusion, suggested interstitial pneumonia. Methyl-prednisolone pulse therapy was started on June 12, after which he completely recovered. Anti-Rikettia japonica IgM antibody was found to be x8,192 by immunofluorescent test, establishing the diagnosis of Japanese spotted fever. Acute respiratory failure with interstitial pneumonia shadows should be emphasized as a complication of severe rickettsiosis.

Acute Disease↗