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Biomedical subjects

Y Fukui

Publications and source records attributed to Y Fukui.

At least 55 records · Page 3Linked to original sources
PubMed2002

Complete nucleotide sequence of the genomic RNA of Aconitum latent virus (genus Carlavirus) isolated from Delphinium sp..

We determined the complete nucleotide sequence of Aconitum latent virus (AcLV-D) isolated from Delphinium sp. The genomic RNA of AcLV-D is 8,657 nucleotides in length, excluding the poly (A) tail. Based on computer analysis, six open reading frames (ORFs) were identified as for other carlaviruses. Although each ORF differs from those of previously reported carlaviruses, the coat protein of AcLV and Potato virus M (PVM) shows a high level of identity. The results suggest that AcLV is a distinct carlavirus species but closely related to PVM.

Amino Acid Sequence↗
PubMed2002

Expression of resistin in the adipose tissue is modulated by various factors including peroxisome proliferator-activated receptor alpha.

AIM: Resistin has been suggested to link obesity to diabetes by antagonizing insulin action. However, this model is based on limited observations and how resistin links the two complex processes is not known. In this study, we investigated the effects of various factors on the expression of resistin and examined the generality of the proposal. METHODS: Total RNA was isolated from the adipose tissues of lean, obese and peroxisome proliferator-activated receptor (PPAR)alpha-null mice fed a control diet or that contained a PPAR ligand, and analysed by Northern blotting using cDNAs for resistin, leptin, aP2 and other mRNAs as probes. For quantitative analysis, an image analyser was used. RESULTS: Basal expression of resistin mRNA was suppressed by obesity, but the extent of suppression differed significantly among the mouse strains and types of adipose tissue examined. Anti-diabetic thiazolidinediones induced resistin expression in the lean mice and showed smaller effects in obese mice. Furthermore, PPARalpha was shown to play an important role in constitutive expression of resistin in the adipose tissue. CONCLUSION: Our results indicated that diverse factors modulate the expression of resistin in the adipose tissues of mice, and suggested that resistin is not a master hormone linking obesity to diabetes.

Adipose Tissue↗
PubMed2001

Neurogenesis of heterotopic gray matter in the brain of the microcephalic mouse.

Neurogenesis of heterotopic gray matter in the brain of the microcephalic mouse prenatally exposed to X-rays at embryonic day 13 (E13) was studied immunohistochemically. Bromodeoxyuridine (BrdU) as a marker to label the migrating position of neuroblasts generated at various embryonic stages showed that no "inside-out" pattern of neuronal migration occurred in the heterotopic cell mass similar to that seen in the laminated cortex. Further results in which midkind (MK) immunoreactive radial glial fibers did not appear in the heterotopic cell mass demonstrated that heterotopia formed in the absence of radial glia system. Different types of cells (pyramidal and non-pyramidal neurons) in the heterotopic cell mass were identified with immunoreactivity for anti-parvalbumin and anti-calbindin D-28K antibodies in addition to current histological methods. Two major types of neurons were mixed together with random distribution in the heterotopic cell mass. This finding indicates that irradiation might have no selective effects on the precursors of pyramidal and non-pyramidal neurons. Moreover, anti-glial fibrillary acidic protein (GFAP) immunostaining showed that numerous astrocytes were present in the heterotopic cell mass. The fact that astrocytes appeared in the heterotopia without the transition from classic radial glial cells to astrocytes suggests that astrocytes might be generated directly from a separate astroglial precursor.

Animals↗
PubMed2001

Akt mediates Rac/Cdc42-regulated cell motility in growth factor-stimulated cells and in invasive PTEN knockout cells.

Growth factors promote cell survival and cell motility, presumably through the activation of Akt and the Rac and Cdc42 GTPases, respectively. Because Akt is dispensable for Rac/Cdc42 regulation of actin reorganization, it has been assumed that Rac and Cdc42 stimulate cell motility independent of Akt in mammalian cells. However, in this study we demonstrate that Akt is essential for Rac/Cdc42-regulated cell motility in mammalian fibroblasts. A dominant-negative Akt inhibits cell motility stimulated by Rac/Cdc42 or by PDGF treatment, without affecting ruffling membrane-type actin reorganization. We have confirmed a previous report that Akt is activated by expression of Rac and Cdc42 and also observed colocalization of endogenous phosphorylated Akt with Rac and Cdc42 at the leading edge of fibroblasts. Importantly, expression of active Akt but not the closely related kinase SGK is sufficient for increasing cell motility. This effect of Akt is cell autonomous and not mediated by inhibition of GSK3. Finally, we found that dominant-negative Akt but not SGK reverses the increased cell motility phenotype of fibroblasts lacking the PTEN tumor suppressor gene. Taken together, these results suggest that Akt promotes cell motility downstream of Rac/Cdc42 in growth factor-stimulated cells and in invasive PTEN-deficient cells.

Animals↗
PubMed2001

Sentinel lymph node biopsy in patients with papillary thyroid carcinoma.

BACKGROUND: It remains controversial whether modified radical neck dissection (MRND) for patients with papillary thyroid carcinoma improves prognosis. However, it is highly probable that the incidence of local recurrence is reduced by lymph node dissection. Sentinel lymph node (SLN) biopsy (SLNB) for patients with melanoma and breast carcinoma has been validated as an accurate method for assessing lymph node status. The objective of this study was to determine the feasibility of SLNB for the evaluation of cervical lymph node status in patients with papillary thyroid carcinoma. METHODS: After injection of methylene blue around the tumor in 22 patients with papillary thyroid carcinoma, blue-stained lymph nodes were dissected as SLNs. After the SLNB, all patients also underwent subtotal thyroidectomy and MRND. SLNs and other lymph nodes were investigated with regard to their number, distribution, size, lymph node status, and ratio of metastatic area. RESULTS: There was concordance between the SLN findings and the regional lymph node status in 19 of 21 patients (90.5%; 7 patients had both positive SLN and regional lymph node results, and 12 patients had both negative SLN and regional lymph node results). Two patients had negative SLN results but, in the end, had positive nonsentinel lymph nodes (NSLNs). The overall reliability rate of SLNB was 86.3% (19 of 22 patients). The authors experienced no complications with the use of methylene blue for the detection of SLNs. CONCLUSIONS: SLNB using methylene blue is feasible technically and is safe, and the findings correlate with cervical lymph node status. Therefore, SLNB is a good technique for estimating the status of cervical lymph nodes in patients with papillary thyroid carcinoma.

Adult↗
PubMed2001

Observation of plasma focusing of a 28.5 GeV positron beam.

The observation of plasma focusing of a 28.5 GeV positron beam is reported. The plasma was formed by ionizing a nitrogen jet only 3 mm thick. Simultaneous focusing in both transverse dimensions was observed with effective focusing strengths of order tesla per micron. The minimum area of the beam spot was reduced by a factor of 2.0+/-0.3 by the plasma. The longitudinal beam envelope was measured and compared with numerical calculations.

Journal Article↗
PubMed2001

Malonyl-CoA:anthocyanin 5-O-glucoside-6"'-O-malonyltransferase from scarlet sage (Salvia splendens) flowers. Enzyme purification, gene cloning, expression, and characterization.

The orange to blue coloration of flowers in nature is, in most cases, provided by anthocyanins, a class of plant flavonoids, many of which are modified by malonyl group(s). However, the identity of the enzyme catalyzing the malonylation reaction remains to be established. Here, we describe for the first time the purification, characterization, and cDNA cloning of an anthocyanin malonyltransferase from scarlet sage (Salvia splendens) flowers. The purified enzyme (termed Ss5MaT1) was a monomeric 50-kDa protein catalyzing the regiospecific transfer of the malonyl group from malonyl-CoA to the 6"'-hydroxyl group of the 5-glucosyl moiety of anthocyanins. Ss5MaT1 showed a k(cat) value of 7.8 s(-1) at 30 degrees C and pH 7.0 for the malonylation of bisdemalonylsalvianin (pelargonidin 3-(6"-O-caffeyl-beta-glucopyranoside)-5-beta-glucopyranoside) and K(m) values of 101 microm and 57 microm for bisdemalonylsalvianin and malonyl-CoA, respectively. p-Coumaric acid, which mimics an aromatic acyl group linked to the 3-glucosidic moiety of an anthocyanin substrate, was a competitive inhibitor with respect to the substrate. This strongly suggests that the presence of an aromatic acyl group at the 3-glucosidic moiety of anthocyanin is important for substrate recognition by the enzyme. On the basis of the partial amino acid sequences of the purified enzyme, we isolated a cDNA encoding Ss5MaT1. Ss5MaT1 consisted of 462 amino acids and shared motifs that are commonly found among members of a versatile plant acyltransferase family, which was recently shown to include numerous homologs of unknown biochemical functions. Northern blot analysis revealed that the transcripts of Ss5MaT1 were detected in petals, sepals, bracts, and red stems, in accordance with the pigment accumulation patterns. Phylogenetic analysis suggests that the aliphatic and aromatic acylations of anthocyanins are generally catalyzed by subfamily members of the plant acyltransferase family.

Acyltransferases↗
PubMed2001

Improvement on in vitro maturation, fertilization and development of minke whale (Balaenoptera acutorostrata) oocytes.

The aims of the present study were to improve in vitro maturation, fertilization and subsequent development of minke whale oocytes. We investigated the effects of different concentrations (0, 10 and 20%) of fetal whale serum (FWS) in maturation medium on nuclear maturation, morphological grade (A or B) of cumulus-oocyte complexes (COC) obtained from prepubertal and adult minke whales. Grade A (> or = 5 layers of cumulus cells) COC collected from the adult whales and cultured in the medium with 20% FWS had a higher (P < 0.05) maturation rate (31.8%) than those in the medium without FWS (0%). Adding FWS to the maturation medium significantly (P < 0.01) improved the proportion of oocytes at Metaphase II (M-II): without FWS (7.9%), with 10% (19.4%) and 20% (21.4%) FWS. However, sexual maturity of whales and COC grades were not significantly affected by M-II oocytes. When in vitro fertilization of matured oocytes was performed in the presence of 20% FWS or 0.6% BSA in the fertilization medium, the proportions of sperm penetration and two-pronuclei formation in matured oocytes were not significantly different. Grade A COC cultured in a culture medium supplemented with 10% FWS cleaved at a higher rate (15.4%, P < 0.05) than did Grade A and B COCs cultured in the medium without FWS (0%). Neither Grade A nor B COCs cleaved when the medium was without FWS. The proportions of cleaved oocytes increased (P < 0.05) with FWS supplementation (6.9% and 8.1% for 1.0% FWS and 20% FWS, respectively). Grade A COC was significantly (P < 0.05) superior in its ability to cleave (14.5%) and develop to morula (4.2%) compared with that of the oocytes from Grade B COC (2.5% and 0%). Coculture with granulosa cells during in vitro culture did not significantly affect cleavage and development to the morula stage. These results indicate that FWS addition in the maturation medium improved the rate of in vitro maturation and cleavage after insemination of minke whale oocytes. The BSA supplementation in fertilization medium was as effective as FWS supplementation for in vitro fertilization of matured oocytes. In vitro embryo production beyond the morula stage of minke whale oocytes could be possible, if Grade A COC was selected and cultured in the maturation medium supplemented with 10% or 20% FWS.

Animals↗
PubMed2001

Haematopoietic cell-specific CDM family protein DOCK2 is essential for lymphocyte migration.

Cell migration is a fundamental biological process involving membrane polarization and cytoskeletal dynamics, both of which are regulated by Rho family GTPases. Among these molecules, Rac is crucial for generating the actin-rich lamellipodial protrusion, a principal part of the driving force for movement. The CDM family proteins, Caenorhabditis elegans CED-5, human DOCK180 and Drosophila melanogaster Myoblast City (MBC), are implicated to mediate membrane extension by functioning upstream of Rac. Although genetic analysis has shown that CED-5 and Myoblast City are crucial for migration of particular types of cells, physiological relevance of the CDM family proteins in mammals remains unknown. Here we show that DOCK2, a haematopoietic cell-specific CDM family protein, is indispensable for lymphocyte chemotaxis. DOCK2-deficient mice (DOCK2-/-) exhibited migration defects of T and B lymphocytes, but not of monocytes, in response to chemokines, resulting in several abnormalities including T lymphocytopenia, atrophy of lymphoid follicles and loss of marginal-zone B cells. In DOCK2-/- lymphocytes, chemokine-induced Rac activation and actin polymerization were almost totally abolished. Thus, in lymphocyte migration DOCK2 functions as a central regulator that mediates cytoskeletal reorganization through Rac activation.

Animals↗
PubMed2001

Specificity analysis and mechanism of aurone synthesis catalyzed by aureusidin synthase, a polyphenol oxidase homolog responsible for flower coloration.

Aureusidin synthase, which plays a key role in the yellow coloration of snapdragon flowers, is a homolog of plant polyphenol oxidase (PPO). The enzyme specifically acted on chalcones with a 4-monohydroxy or 3,4-dihydroxy B-ring to produce aurones, for whose production the oxidative cyclization of chalcones must be preceded by 3-oxygenation. However, it exhibited virtually no PPO activity toward non-chalcone phenolics. The enzyme was competitively inhibited by phenylthiourea, a specific PPO inhibitor. These results led us to propose a mechanism of aurone synthesis by aureusidin synthase on the basis of known PPO-catalyzed reactions and conclude that the enzyme is a chalcone-specific PPO specialized for aurone biosynthesis.

Benzofurans↗
PubMed2001

Differential localization and colocalization of two neuron-types of sodium-dependent inorganic phosphate cotransporters in rat forebrain.

We studied by immunohistochemistry the distribution of differentiation-associated sodium-dependent inorganic phosphate (Pi) cotransporter (DNPI) in the rat forebrain, in comparison with brain-specific cotransporter (BNPI). DNPI-staining was principally seen in axonal synaptic terminals which showed a widespread but discrete pattern of distribution different from that of the BNPI-staining. In the diencephalon, marked DNPI-staining was seen in the dorsal lateral geniculate, medial geniculate, ventral posterolateral, ventral posteromedial, anterior, and reticular thalamic nuclei without the colocalization with BNPI-staining. DNPI-staining showed a strong mosaical pattern and overlapped well the BNPI-staining in the medial habenular nucleus. DNPI-staining was moderate over the hypothalamus and notably localized in neurosecretory terminals containing corticotropin-releasing hormone in the median eminence. In contrast, the BNPI-staining was region-related and strong in the ventromedial and mammillary nuclei. In the telencephalon, laminar DNPI-staining was seen over the neocortex, corresponding to the thalamocortical termination, and also found in the retrosplenial cortex and the striatum, with the highest intensity in the accumbens nucleus shell. The present results suggest that DNPI serves as a dominant Pi transport system in synaptic terminals of diencephalic neurons including thalamocortical and thalamostriatal pathways as well as the hypothalamic neuroendocrine system in the rat forebrain.

Animals↗
PubMed2001

Fertilizability and developmental capacity of bovine oocytes cultured individually in a chemically defined maturation medium.

This study investigated effects of adding hypotaurine (HT), beta-merocaptoethanol (beta-ME), or both into a chemically defined maturation medium (TCM-199 containing 0.1% polyvinyl alcohol: PVA) on maturation, fertilization and development of individually (single) cultured bovine oocytes. Mean GSH concentration in the oocytes cultured in the medium supplemented with either beta-ME (1.11 +/- 0.05 nM) or HT plus beta-ME (0.97 +/- 0.03 nM) was significantly (P < 0.05) higher than that in the medium containing PVA alone (0.75 +/- 0.03 nM). Adding beta-ME showed a significantly (P < 0.05) higher rate of the second metaphase stage (93.6 +/- 3.3%) than in the medium containing PVA alone (single-control) (65.2 +/- 7.9%). Adding both HT and beta-ME showed significantly (P < 0.05) higher rates (92.6 +/- 2.7%) of normal fertilization than did adding HT alone (63.5 +/- 4.6%). Also, adding both HT and beta-ME significantly (P < 0.05) lowered the polyspermy rate than did adding HT alone. Adding either beta-ME or both HT and beta-ME showed no significant difference in cleavage. Blastocyst development did not improve significantly adding either HT, beta-ME or both, although beta-ME alone or HT plus beta-ME tended to result in a higher rate of blastocysts (6.4 and 6.8%, respectively) than resulted without additives (1.6%). Our results show that adding beta-ME to a chemically defined maturation medium increased the intracellular GSH level of bovine oocytes cultured individually, and can improve the maturation rate leading to the blastocyst stage throughout in vitro production.

Animals↗
PubMed2001

Plasma and pituitary concentrations of gonadotropins (FSH and LH) in minke whales (Balaenoptera acutorostrata) during the feeding season.

This study investigated plasma and pituitary concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) and steroid hormones (progesterone: P4, testosterone:T, estradiol-17beta: E2) by enzyme-immunoassay (EIA) in minke whales (Balaenoptera acutorostrata) captured during the feeding season (December to March) in the Antarctic Ocean. Plasma FSH and LH levels in female minke whales were higher (P <0.05) than in male whales. Although the pituitary weight was not significantly different between male and female whales, pituitary FSH and LH levels were higher in females than in males (P<0.01) and mature whales than immature whales (P<0.05). Plasma levels of FSH, T and E2 were not significantly different between immature and mature male whales, but plasma LH and pituitary FSH and LH levels were higher (P<0.05) in mature than in immature whales. In both immature and mature whales regardless of gender, pituitary FSH and LH levels were correlated significantly (r=0.69: P<0.01). In mature male whales, plasma T and E2 levels (r=0.60: P<0.01), and testis weight and plasma T levels (r=0.46: P <0.05) were correlated. In immature female whales, plasma FSH and LH levels were highly correlated (r=0.68: P<0.001), but were not for mature female whales. The results show that gender and maturity influence gonadal and pituitary function of minke whales during the feeding season.

Age Factors↗
PubMed2001

Membrane recruitment of DOCK180 by binding to PtdIns(3,4,5)P3.

DOCK180 was originally identified as one of two major proteins bound to the Crk oncogene product and became an archetype of the CDM family of proteins, including Ced-5 of Caenorhabditis elegans and Mbc of Drosophila melanogaster. Further study has suggested that DOCK180 is involved in the activation of Rac by the CrkII-p130(Cas) complex. With the use of deletion mutants of DOCK180, we found that the C-terminal region containing a cluster of basic amino acids was required for binding to and activation of Rac. This region showed high amino-acid sequence similarity to the consensus sequence of the phosphoinositide-binding site; this led us to examine whether this basic region binds to phosphoinositides. For this purpose we used PtdIns(3,4,5)P(3)-APB beads, as reported previously [Shirai, Tanaka, Terada, Sawada, Shirai, Hashimoto, Nagata, Iwamatsu, Okawa, Li et al. (1998) Biochim. Biophys. Acta 1402, 292-302]. By using various competitors, we demonstrated the specific binding of DOCK180 to PtdIns(3,4,5)P(3). The expression of active phosphoinositide 3-kinase (PI-3K) did not enhance a DOCK180-induced increase in GTP-Rac; however, the expression of PI-3K translocated DOCK180 to the plasma membrane. Thus DOCK180 contained a phosphoinositide-binding domain, as did the other guanine nucleotide exchange factors with a Dbl homology domain, and was translocated to the plasma membrane on the activation of PI-3K.

Cell Line↗
PubMed2001

Characterization of anthocyanin p-coumaroyltransferase in flowers of Iris ensata.

Malvidin and petunidin 3-(p-coumaroyl)rhamnosylglucoside-5-glucosides as well as nonacylated 3-rhamnosylglucoside-5-glucoside of these anthocyanidins were detected as major anthocyanins in cyanic flowers of Iris ensata. Enzyme extracts from flower buds of this plant catalyzed the transfer of the p-coumaroyl moiety from p-coumaroyl-CoA to both the anthocyanidin 3-rhamnosylglucoside and 3-rhamnosylglucoside-5-glucoside to form the anthocyanidin 3-(p-coumaroyl) rhamnosylglucoside and 3-(p-coumaroyl) rhamnosylglucoside-5-glucoside, at a ratio of ca. 1 to 4, respectively. The activities of this enzyme were also examined for various cyanic and acyanic cultivars, in addition to the characterization of the p-coumaroyltransferase. The sequence of acylation and 5-glucosylation in the anthocyanin biosynthesis of this plant is discussed.

Journal Article↗
PubMed2001

Enzymatic formation of aurones in the extracts of yellow snapdragon flowers.

The yellow coloration of snapdragon (Antirrhinum majus) flowers is mainly provided by the 6-glucosides of aureusidin and bracteatin. However, the biochemical mechanism of aurone biosynthesis is not well understood. In this study, we have identified aurone-biosynthesizing activity in the extracts of yellow snapdragon flowers. Incubation of 2',4',6',4-tetrahydroxychalcone (THC) with an enzyme preparation in the presence of H(2)O(2) caused the enzymatic formation of a single product, aureusidin, without the formation of a previously proposed 2-(alpha-hydroxybenzyl)coumaranone intermediate. The formation of aureusidin from THC was specifically observed with yellow flowers as well as aurone-accumulating flowers of other colors. The pH optimum for the enzymatic formation of aureusidin was around 5.4. Stoichiometric studies showed that one mole of aureusidin formation was accompanied by the consumption of one mole of oxygen with no detectable consumption of H(2)O(2), which may work as an enzyme activator. The oxidative formation of aureusidin from THC could be explained in terms of the action of a single enzyme, an internal monooxygenase catalyzing the 3-hydroxylation and oxidative cyclization of THC. Incubation of 2',4',6',3,4-pentahydroxychalcone (PHC) with an enzyme yielded both aureusidin and bracteatin at an approximate molar ratio of 6:1. In this case, H(2)O(2) was not required for enzyme activity but rather inhibited the reaction. The 4'-glucosides of THC and PHC could also act as substrates for the formation of the 6-glucosides of aurones. These results suggest that aureusidin can be produced from either THC or PHC, whereas bracteatin is not produced through the 5'-hydroxylation of aureusidin but arise solely from PHC.

Journal Article↗